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A DETRITAL ZIRCON TRANSECT ACROSS THE SON VALLEY SECTOR OF THE VINDHYAN BASIN, INDIA: CONSTRAINTS FOR BASIN EVOLUTION AND

PALEOGEOGRAPHIC IMPLICATIONS FROM U-Pb AND Hf ISOTOPIC DATA

By

CANDLER COYLE TURNER

A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE

OF MASTER OF SCIENCE

UNIVERSITY OF FLORIDA

2012

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© 2012 Candler Turner

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To my folks, my friends, the Earth, and India

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ACKNOWLEDGEMENTS

First and foremost I thank my parents for their never ending support. I thank my

all-knowing advisor Dr. Joseph Meert for his patience and support during my career at

the University of Florida and for extending me all the wonderful opportunities that I have

received along the way. I also thank the many professors that have helped to expand

my knowledge in Geology. I also thank Dr. Matt Smith for helping to make my life as a

teaching assistant much easier. I must thank NSF for their funding of this research. Last

but not least, I thank the many friends that I have gained during my tenure at the

University of Florida for making it quite a fun ride. Finally, I thank mother Earth, for

without her, none of this would have been possible.

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TABLE OF CONTENTS page

ACKNOWLEDGEMENTS ............................................................................................... 4

LIST OF TABLES ............................................................................................................ 6

LIST OF FIGURES .......................................................................................................... 7

LIST OF ABBREVIATIONS ............................................................................................. 9

ABSTRACT ................................................................................................................... 10

CHAPTER

1 INTRODUCTION .................................................................................................... 12

Geologic Setting ..................................................................................................... 16 Vindhyan Basin ................................................................................................ 16 Lower Vindhyan Sequence............................................................................... 17 Upper Vindhyan Sequence............................................................................... 18 Marwar Basin ................................................................................................... 19

Summary ................................................................................................................ 20

2 GEOCHRONOLOGY METHODS ........................................................................... 26

3 RESULTS ............................................................................................................... 29

U-Pb Geochronology .............................................................................................. 29 Vindhyan Samples .................................................................................................. 29 Marwar Samples ..................................................................................................... 30 Hf Isotopes .............................................................................................................. 32

4 DISCUSSION ......................................................................................................... 67

Marwar and Vindhyan Correlations ......................................................................... 67 Provenance of Detrital Zircons from the Marwar and Vindhyan Basins .................. 71

Vindhyan Provenance ...................................................................................... 73 Marwar Provenance ......................................................................................... 77

Paleogeographic Implications ................................................................................. 78 Links between Continental Landmasses from Detrital Zircon Records ............ 78 Rodinia and Gondwana .................................................................................... 78

5 CONCLUSIONS ..................................................................................................... 90

LIST OF REFERENCES ............................................................................................... 92

BIOGRAPHICAL SKETCH .......................................................................................... 103

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LIST OF TABLES

Table page 3-1 Upper Vindhyan U-Pb Isotopic Data .................................................................. 34

3-2 Marwar U-Pb Isotopic Data................................................................................ 50

3-3 Hf Isotopic Data ................................................................................................. 61

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LIST OF FIGURES

Figure page 1-1 Map of continental India and the locations of Purana basins, distribution of

cratons, and tectonic domains (modified from Rao and Reddy 2002). Important Abbreviations: ..................................................................................... 22

1-2 Geologic Map of the Vindhyan Basin. A) Map of continental India; B) Rajasthan Sector; C) Son Valley Sector; D) Bundelkhand Sector. The Narmada-Son Lineament creates the eastern most boundary of the Vindhyan . 23

1-3 Correlations and Stratigraphy of the Vindhyan Supergroup from both the Son Valley and Rajasthan Sectors. Age constraints provided from Gregory et al. (2006), Sarangi et al. (2004), Ray et al. (2003, 2002), De (2006), and Malone .. 24

1-4 Marwar Stratigraphy and correlations to the Salt Range of Pakistan, the Krol-Tal belt of the Himalayas, and the Huqf Supergroup of Oman. Note that the Krol-Tal and Huqf Supergroup contain stratigraphy from the Marinoan time ...... 25

3-1 Detrital zircon probability plots for the select samples from the Son Valley (Kaimur, Rewa/Kaimur, Rewa and Bhander Sandstone) Sector and Rajasthan. .......................................................................................................... 64

3-2 Detrital Zircon probability plots for select samples from the Marwar Supergroup. Note the appearance of <1000 Ma zircons in these plots compared to upper Vindhyan plots that contain no zircons <1000 Ma ............... 65

3-3 εHf(t) vs U-Pb age data for ~1.7-1.8 Ga detrital zircons from both the Marwar and upper Vindhyan sediments. The majority of samples contain negative εHf(t) values corresponding an affinity with ancient crustal material.. ................. 66

4-1 Cumulative U-Pb age Probability Density Plots for Marwar and upper Vindhyan Detrital zircons. Red shaded area represents zircons dated to <1000 Ma.. ......................................................................................................... 84

4-2 Paleomagnetic pole positions at ~1.0-1.1 Ga from Venkateshwarlu and Chalapathi-Rao (in press) kimberlite and lamporite intrusions in the Dharwar craton, Majhgawan kimberlite, ............................................................................ 85

4-3 Geodynamic Map of the supercontinent Rodinia reconstruction from Li et al. (2008). ................................................................................................................ 86

4-4 Generalized Gondwana reconstruction depicting Neoproterozoic and younger orogenic belts that separate the various cratons of West and East Gondwana (Malone et al. 2008; modified from Gray et al. 2007). ...................... 87

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4-5 Locations of Ediacaran-Cambrian Basins in the Arabian-Nubian Shield, Himalayas, Pakistan and Madagascar that correlate with the Marwar Basin as seen in the ‘traditional’ Gondwana reconstruction. ........................................ 88

4-6 Detrital zircon spectra representing the phases of orogenesis advocated by Runcorn (1962) from data published in Hawkesworth et al. (2009). Supercontinents represented.............................................................................. 89

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LIST OF ABBREVIATIONS

AFB Aravalli Delhi Fold Belt

BPMP Bhavani Palghat Mobile Belt

CITZ Central Indian Tectonic Zone

CG Closepet Granites

DFB Delhi Fold Belt

EGMB Eastern Ghats Mobile Belt

GBF Great Boundary Fault

HF Hafnium

LA-ICP-MS Laser Abalation-Ion Coupled Plasma-Mass Spectrometer

NSL Naramada-Son Lineament

Pb Lead

SHRIMP Sensitive High Resolution Ion Microprobe

TIMS Thermal Ionization Mass Spectrometer

U Uranium

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Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the

Requirements for the Degree of Master of Science

A DETRITAL ZIRCON TRANSECT ACROSS THE SON VALLEY SECTOR OF THE VINDHYAN BASIN, INDIA: CONSTRAINTS FOR BASIN EVOLUTION AND

PALEOGEOGRAPHIC IMPLICATIONS FROM U-Pb AND Hf ISOTOPIC DATA

By

Candler Coyle Turner

December 2012

Chair: Joseph Meert Major: Geology

The Vindhyan Supergroup, located in central peninsular India, is one of the

largest and thickest Precambrian sedimentary successions of the world, outcropping

over an area of over 104,000 km2. The Vindhyan is the largest of the so-called

“Purana” basins in India. Split into the upper Vindhyan and the lower Vindhyan, the age

of the Upper Vindhyan sedimentary sequence is the subject of considerable

controversy. This study seeks to determine if the Vindhyan Basin is much older in age

than a previously assigned Neoproterozoic age, the age of basin closure, source of

sediments, and to discuss the nearby “Trans-Aravalli Vindhyans,” or Marwar basin, and

its relationship to the Vindhyan Basin. Multiple hypotheses have been forwarded

concerning basin closure: some argue for an early Neoproterozoic to late

Mesoproterozoic closure (~1050 Ma) of Upper Vindhyan sedimentation whereas others

argue for an Ediacaran-Cambrian age. U-Pb dating of detrital zircons from upper

Vindhyan sedimentary rocks of the Son Valley sector, purported U-Pb detrital zircon

from the Rajasthan sector of the basin and paleomagnetic data from the Majhgawan

kimberlite indicates a Mesoproterozoic age for the upper Vindhyans and supports the

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hypothesis that the Vindhyan and Marwar basin do not share a co-evolutionary history.

However, Hf isotopic data show that the Vindhyan and Marwar shared similar sources,

most likely from the Aravalli region. U-Pb data corroborates other provenances that

provided detritus to the Vindhyan and Marwar basins. Paleographical implications can

also be made from these detrital zircon age populations.

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CHAPTER 1 INTRODUCTION

The understanding of geologic events in the Precambrian is vital to

understanding the evolution of the earth, plate tectonic theory and evolution of life. The

Proterozoic Eon (2500-540 Ma) brackets an important time in Earth’s history that

includes the amalgamation and breakup of supercontinents (Dalziel 1997) such as the

Paleoproterozoic-age Columbia (Rogers 1996; Rogers and Santosh 2002; Meert 2002;

Santosh et al. 2003; Zhao et al. 2004; Pradhan et al. 2011; Kaur et al. 2012), the Meso-

Neoproterozoic age Rodinia (McMenamin and McMenamin 1990; Meert and Torsvik

2003; Meert and Powell 2001; Li et al. 2008; Pradhan et al. 2011) , and the Ediacaran-

Cambrian age Gondwana (Meert et al. 2003; Meert and Lieberman, 2008; Powell and

Pisarevsky, 2002; Meert and Powell 2001; Pesonen et al. 2003; Pradhan et al. 2011).

This time period also included vast global oceanic and atmospheric changes (Hoffman

et al. 1998), the evolution leading up to the beginning of multicellular life (Knoll 1994)

and major changes in upper crustal composition (Taylor and McLennan 1985).

The Indian subcontinent is thought to have played a role in the supercontinent

cycles listed above, with a Precambrian history spanning nearly 3.0 billion years of

geologic time. The assembly of Peninsular India began in the early Archean with the

development and formation of the Aravalli, Bundelkhand, Eastern Dharwar, Western

Dharwar, Bastar, and Singhbhum Cratons in conjunction with the Southern Granulite

Province (Figure 1- 1). The progressive development of each of these nuclei included

the formation of tonalite-trondhjemite gneissic complexes, greenstone belts and late

phase granitic intrusions. While each craton developed independently, there are

several key intervals of time that led to the formation of Peninsular India (Meert et al.,

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2010, represented by basement rocks dated to ~3.6 Ga, ~3.5 Ga, ~3.4 Ga, ~3.3 Ga,

~3.2 Ga, ~2.7 Ga (Meert et al. 2010). These cratonic nuclei are believed to have

stabilized by 2.5-2.6 Ga (Meert et al., 2010; Rogers, 1998), a time interval marked by

widespread granitic magmatism.

The exact timing of ‘proto-India’ assembly is contentious because the nature and

age of tectonic events in the suture zone between the Northern and Southern Indian

blocks, the Central Indian Tectonic Zone (CITZ), may indicate that ‘proto-India’ was not

fully formed until the Mesoproterozoic (Meert et al. 2010 and sources therein; Bhowmik

et al. 2011; 2012). Recent tectono-metamorphic reconstructions (Bhandari et al. 2011)

suggest that Early Mesoproterozoic orogenesis was an integral component of crustal

growth and assembly in central, eastern, and north-eastern India. A variety of ages are

attributed to an array of terranes located in the CITZ, representing orogenic events

occurring at 2.5 Ga,~1.6 Ga, ~1.5 Ga, and ~1.4 Ga to as young as 0.94 Ga. Further

west, in the Aravalli craton, available zircon, monzanite, and Sm-Nd model ages

indicate four important tectono-magmatic and tectono-thermal events in the region at

2.5 Ga, 1.85 Ga, 1.7-1.6 Ga and 1.0-0.9 Ga (Kaur et al. 2011; Mondal et al. 2002; Roy

et al. 2005; Sarkar et al. 1989; Saha et al. 2008; Bhowmik et al. 2009; Chaudhri et al.

2003; Kaur et al. 2007;Lescuyer et al. 1993; Sivaraman and Raval 1995; Biju—Sekhar

et al. 2003; Kaur et al. 2006).

Following cratonic stabilization of the Archean nuclei, a number of large

Proterozoic basins developed on the cratons. The development of the basins was

polyphase, but many of the larger basins formed at about the same time. The earliest

Paleo to early-Mesoproterozoic phase of basin formation is represented in the Aravalli,

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Lower Vindhyan, Lower Chhattisgarh and Cuddapah Basins (Figure 1- 1). During the

late Mesoproterozoic to early Neoproterozoic, sedimentary sequences are found in the

Upper Vindhyan, Upper Chhattisgarh and Indravati Basins. The final phase of

Precambrian basin formation occurred in the Late Neoproterozoic and includes

sedimentary deposits in the Marwar Basin, the Kurnool Group of the Cuddapah Basin,

and several basins now located in Himalayas (Krol-Tal and Salt-Range; Figure 1- 2).

Historically, all of these basins were dubbed the “Purana” (Hindi for ancient) and

collectively cover hundreds of thousands of square kilometers of the Indian

subcontinent (Figure 1- 1; Chaudhuri et al. 2002). The Purana basins are believed to

represent the infill of failed rifts that developed on earlier Archean and/or early

Paleoproterzoic cratonic blocks (Ram et al. 1996; Chaudhuri et al. 2002). The basins

are bounded by normal faults visible on seismic profiles, geologic mapping, and gravity

data and those observations led to a general consensus that all are rift-related (Prasad

and Rao, 2006; Ram et al., 1996; Chaudhuri et al., 2002).

The sedimentary sequences within these basins provide critical ‘ground-truth’

when attempting to decipher the tectonic history of the Indian subcontinent and its role

in global events. In addition to standard sedimentary analyses and interpretations, the

use of detrital zircons from clastic sedimentary rocks has become a popular tool used in

sedimentary correlation and sedimentary provenance studies (Fedo et al. 2003).

U-Pb ages derived from single detrital zircon grains can be used to identify

provenance components in a sedimentary unit, to correlate between sedimentary

sequences, to determine a maximum limit for the age of deposition, and to study crustal

evolutionary processes. This type of geochronology is advantageous because the

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abundance of zircon does not change drastically during sediment transport due to the

inherent stability of zircon (Hietpas et al. 2012). The applicability of these data is further

enhanced when cathodoluminescence (CL) imaging is used to detect zircon zoning. In

the case of zoned zircons, additional information regarding the polyphase magmatic

and/or metamorphic history of the individual zircon can be resolved (Hietpas et al. 2011

and sources therein).

The Marwar Basin lies to the west of the Vindhyan basin across the Aravalli

Mountain range, in northwestern Rajasthan and the Marwar Supergroup is often

referred to as the “Trans Aravalli Vindhyans” (Heron 1932; Kumar and Pandey 2008;

Pandey and Bahadur et al. 2009). These two basins provide promising areas to

conduct sedimentary provenance analyses due to the long depositional history

collectively recorded in both basins (Vindhyan sediments are estimated to have been

deposited between ~1.8 to ~ 1.0 Ga and the deposition of the Marwar is estimated to

span from ~750 Ma to ~521 Ma) along with limited deformation/metamorphism in each

basin. Additionally both basins are located in proximity to the CITZ and Aravalli-Delhi

Fold belts that may have provided a significant component of detritus and therefore may

aid in identifying the ages of different magmatic and metamorphic events in those

regions. These zircons also have the potential to document information on source

lithology in the surrounding region, constrain the timing of sediment deposition into each

basin, and ultimately determine the tectonic setting at the time of deposition.

The Marwar sequence is younger than the neighboring ~750 Ma Malani igneous

rocks. If the Upper Vindhyans (near Rajasthan) are age-correlative, it is possible that

they would also show some input from the Malani Igneous Province, but previous

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studies focused on Upper Vindhyan rocks adjacent to the Malani Igneous province

(comprised of three magmatic phases, a volcanic phase made up of predominant felsic

and minor mafic flows, a granitic pluton phase, and a third phase of felsic and mafic

dyke swarms; Gregory et al. 2009) showed no contribution (Malone et al. 2008). The

work described in this paper serves as an expansion of the work by Malone et al. (2008)

and McKenzie et al. (2011). Vindhyan and Marwar rocks were targeted immediately

adjacent to the Malani igneous province for detrital zircon analyses. Samples span the

entire Upper Vindhyan and Marwar stratigraphy. Our results can be compiled with

those of Malone et al. (2008) and McKenzie et al. (2011) to yield detrital zircon spectra

that should shed light on the regional activity that would have supplied sediment to

these basins. It will also serve as a tool for comparison with other detrital zircon records

from basins located on other cratonic blocks that are hypothesized to be in proximity

with Peninsular India during the Rodinian and Gondwanan supercontinent cycles.

Geologic Setting

Vindhyan Basin

The Vindhyan basin of the Bundelkhand Craton, located in central peninsular

India, occupies a large portion of eastern Rajasthan state and extends well into the

adjacent states of Madhya Pradesh and Uttar Pradesh (Figure 1- 1 and 1. 2). The

Vindhyan Basin covers an area of over 104,000 km2, with additional area covered by

the Deccan Traps (to the south) and Indo-Gangetic alluvium (to the north and east;

Figure 1 & 2; after Venkatachala et al. 1996). The Vindhyan Supergroup is divided into

four Groups: the Semri Group and the Kaimur, Rewa, and Bhander Groups. The latter

three Groups comprise the Upper Vindhyan and the units within the Semri Group are

the Lower Vindhyan (Ray 2006; Figures 1.1 and 1.3). Outcrops of the Vindhyan Basin

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are located in three different sectors: the Rajasthan sector, the Bundelkhand sector, and

the Son Valley Sector (Figure 1- 2).

The southern margin of the basin is delimited by the ENE-WSW trending

Narmada-Son lineament just north of the Satpura Mobile Belt, also known as the CITZ.

This complex Proterozoic orogenic belt formed during the accretion of the Bastar-

Singhbum Craton to the northern Bundelkhand Craton. The Mahakoshal Group and the

Bijawar Group, exposed low-grade metamorphic volcano-sedimentary rocks, are

located near the southern edge of the Vindhyan outcrop and the eastern flank of the

Bundelkhand massif, respectively (Chakraborty 2006). The western margin is marked

by the NE-SW trending Great Boundary Fault (GBF) adjacent to the Aravalli-Delhi

mountain range to the northwest that separates the Aravalli and Bundelkhand cratons.

The basin is believed to continue beneath the Gangetic alluvial plain beyond the

northern-most outcrop existing today (Chakraborty 2006; Figure 1).

Lower Vindhyan Sequence

The Lower Vindhyan sedimentary sequence is often referred to as the Semri

Series (Figure 1- 3). Age constraints on the Semri Series are robust for the bulk of the

sedimentary package. Sedimentation is believed to have started sometime prior to

1721 Ma and continued until about 1600 Ma without any major breaks in deposition

(Ray et al. 2006). The Lower Vindhyan units unconformably lie atop the Bundelkhand

Granite basement rocks of this region dated to 2492 ± 10 Ma (Mondal et al. 2002) or the

1854 ± 7 Ma Hindoli Group (Deb et al. 2003). Geochronologic constraints on lower

Vindhyan sedimentation include a whole rock Pb-Pb age of 1729 Ma on the Kajrahat

Limestone (Sarangi et al. 2004). The Kajrahat is overlain by the Deonar Porcellanite,

Rampur shale and Rhotas limestone. The Deonar Porcellanite yielded two robust U-Pb

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zircon ages of 1630.7 ± 0.4 Ma (TIMS, Ray et al., 2002) and 1628 ± 8 Ma (SHRIMP;

Rasmussen et al. 2002. Zircons from volcaniclastics within the Rampur shale were

dated at 1599 ± 8 Ma (SHRIMP, Rassmussen et al. 2002). Pb-Pb ages from the

Rhotas limestone obtained by Ray et al. (2003) and Sarangi (2004) are comparable

though with somewhat large errors (1601 ± 130 Ma and 1599 ± 48 Ma). Based on

these ages, sedimentation in the Lower Vindhyan basin began <1850 Ma and ended

around ~1550-1600 Ma. A basin wide angular and erosional unconformity separates

the Rhotas limestone from the overlying Kaimur Group.,

Upper Vindhyan Sequence

Ages constraints on Upper Vindhyan sedimentation are more problematic.

Current estimates put the onset of Upper Vindhyan sedimentation in the

Mesoproterozoic (>1100 Ma) and the cessation of sedimentation as young as Cambrian

(Malone et al., 2008, Azmi et al., 2010). The best age constraints for the Upper

Vindhyan sediments are derived from the 40Ar-39Ar age of 1073.5 ± 13.7 Ma for the

Majhgawan kimberlite that intrudes the Baghain sandstone (Kaimur Group; Figure 1- 3;

Gregory et al. 2006). Based on this age, sedimentation of the Kaimur sandstone began

prior to the intrusion and therefore the onset of Upper Vindhyan sedimentation is reliably

constrained to the Mesoproterozoic.

Other attempts to establish the age of the upper Vindhyan sediments give

contradictory results. De (2003, 2006) argued that Upper Vindhyan sedimentation

continued into the Ediacaran based on fossils in the Bhander limestone. Azmi et al.

(2010) reject all geochronological data and argue that sedimentation within the Upper

and Lower Vindhyan sequence is of Ediacaran age.

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Gregory et al. (2006) noted that the virtual geomagnetic pole (VGP) from the

Majhgawan kimberlite was identical to previously published paleomagnetic poles from

the Bhander and Rewa Groups. They suggested that this may signify that deposition of

the Bhander-Rewa Groups was confined to the Mesoproterozoic. Additional support for

this hypothesis was given by Malone et al. (2008) based on an analysis of detrital zircon

in the Vindhyan basin along with a comprehensive paleomagnetic study of the Bhander-

Rewa Groups. Malone et al. (2008) noted a lack of detrital input into the basin younger

than ~1000 Ma. While absence of younger detritus can be due to numerous causes,

the paleomagnetic data from the Bhander-Rewa Groups confirmed the suspicions of

Gregory et al. (2006). Subsequent reinforcement of a Mesoproterozoic depositional age

is derived from a paleomagnetic study of the Mahoba dyke in the Bundelkhand craton

(just north of the Son Valley sector; Pradhan et al., 2012). This dyke is dated to 1090

Ma and also yields a paleomagnetic direction indistinguishable from the Majhgawan and

Bhander-Rewa, supporting the hypothesis that a Mesoproterozoic age may be assigned

to these sediments.

Marwar Basin

To the west the Vindhyan Basin, beyond the Aravalli-Delhi Range is the

Neoproterozoic-Cambrian age Marwar Basin (Figure 1- 4; Davis et al. 2011). The

Marwar Supergroup (MS; Khan 1971) is situated in the state of Rajasthan, India and

extends from south of Nagaur in the east to north of Pokaran in the west, with an

estimated thickness of 1000-2000 m (Figure 1- 3 & 1.4; Pandey and Bahadur 2009).

The Marwar Basin is considered by some to be the westerly extension of the upper

Vindhyans across the Aravalli axis (Figure 1- 1; Heron 1932; Pandey and Bahadur

2009). . The assumption of contemporaneous deposition in both the Upper Vindhyan

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and Marwar basins was based upon lithological similarities, the lack of diagnostic fossils

and the lack of penetrative deformation in both basins (Heron 1932; Heron 1936; Verma

1991).

The lithostratigraphy of the Marwar Supergroup is divided into 3 groups: the

lower Jodhpur Group, the middle Bilara Group, and the upper Nagaur Group (Figure 1-

4). The Pokaran boulder bed of the Jodhpur Group lies unconformably above the 750-

800 Ma Malani Igneous Suite, (Figure 1- 3 & 1.4; Gregory et al., 2009; Van Lente et al.,

2009; Pradhan et al., 2010; Torsvik et al., 2001), and contains cobbles of Malani and

older igneous rocks (Meert et al. 2010; Chakrabartu et al. 2004; Ramakrishnan and

Vaidyanadhan 2008). Recent age estimates would place the Lower Marwar in the time

frame for Gaskiers (~ 580 Ma) or Marinoan (~ 635 Ma) glaciations, but there is no

evidence for a glacial origin of these rocks (i.e. dropstones, striated clasts; Meert et al.

2010). The exact age range of the Marwar Supergroup is not precisely known, but it is

typically correlated with the Ediacaran-Cambrian sequences in the Salt Range of

Pakistan, the Krol-Tal Belt of the Himalayas and the Huqf Supergroup (Oman) based on

similar trace fossils, lithologies and macrofossils (Figure 1- 4; Jones 1970; Kumar and

Pandey 2008, 2010; Cozzi et al., 2012).

Summary

Recent geochronologic data support the hypothesis that the Marwar may not be

a continuation of the Vindhyan Supergroup. Malone et al. (2008) examined the age

spectra of detrital zircons in the Sonia and Girbakhar sandstones from the Marwar

Supergroup that showed distinct differences from that of the nearby Upper Bhander

Group in the Rajasthan sector (Figure 1- 2). In particular, Malone et al. (2008) noted

the presence of <1000 Ma zircons in the Marwar Supergroup. Based partly on this

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difference, Malone et al. (2008) argued for distinct basinal histories for the Marwar and

Vindhyan basins. This difference in zircon populations was reinforced by a recent study

of McKenzie et al. (2011). In addition, new fossil finds (Kumar and Pandey 2009;

Kumar et al. 2009) of Ediacaran and younger biota provide firm evidence that

sedimentation in the Marwar basin is confined to the interval from <750 Ma to the

earliest Cambrian (~521 Ma). Davis et al. (2012) and Cozzi et al. (2012) further limit the

age of sedimentation in the Marwar Supergroup to between 635-521 Ma based on the

lack of glacial deposits in the Marwar and intrabasinal comparisons with Oman.

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Figure 1-1. Map of continental India and the locations of Purana basins, distribution of

cratons, and tectonic domains (modified from Rao and Reddy 2002). Important Abbreviations: Delhi Fold Belt (DFB); Aravalli Fold Belt (AFB); Naramada Son Lineament (NSL); Satpura Mobile Belt (SMB; also known as Central Indian Tectonic Zone, CITZ); Godavari Basin (GB); Mahandi Rift (MR); Closepet Granites (CG); Eastern Ghats Mobile Belt (EGMB); Central Indian Suture (CIS); Bhavani-Palghat Mobile Belt (BPMB).

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Figure 1-2. Geologic Map of the Vindhyan Basin. A) Map of continental India; B)

Rajasthan Sector; C) Son Valley Sector; D) Bundelkhand Sector. The Narmada-Son Lineament creates the eastern most boundary of the Vindhyan Basin, while the Great Boundary Fault (GBF) delimits the western boundary. To the west of the GBF lie the Aravalli/Delhi Fold Belts and their successive sedimentary sequences. Further to the west, the Marwar Supergroup (represented by the Jodphur Sandstone in this figure) overlies the Malani Rhyolites. Detrital zircon whole rock samples were selected from the Rajasthan and Son Valley sectors.

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Figure 3: Figure 1-3. Correlations and Stratigraphy of the Vindhyan Supergroup from both the Son Valley and Rajasthan Sectors.

Age constraints provided from Gregory et al. (2006), Sarangi et al. (2004), Ray et al. (2003, 2002), De (2006), and Malone et al. (2008). Note that an unconformity separates the Lower and Upper Vindhyans.

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Figure 1-4. Marwar Stratigraphy and correlations to the Salt Range of Pakistan, the

Krol-Tal belt of the Himalayas, and the Huqf Supergroup of Oman. Note that the Krol-Tal and Huqf Supergroup contain stratigraphy from the Marinoan time period.

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CHAPTER 2 GEOCHRONOLOGY METHODS

Samples were taken in the Son Valley and Rajasthan sectors of the Vindhyan

basin along with additional samples from the Marwar Supergroup in 2009 and 2011.

The samples were broken down with a sledge hammer and jaw crusher and further disk

milled to reduce sediment into sand grain size. Samples were further separated by size

using a succession of 400 μm (40 mesh) and 250 μm (60 mesh) sieves. Density

separation by water table and heavy liquid was followed by magnetic separation

techniques to isolate individual grains of zircon. These grains were examined with an

optical microscope and handpicked from the appropriate fractions (non-magnetics at 5º,

.5 A). Zircons were then mounted into an epoxy plug and polished to expose surfaces

of the zircons. Cathodoluminescence (CL) imaging was then taken by SEM (Scanning

Electron Microscope), as well as reflected light microscope imaging. The epoxy plugs

were sonicated and cleaned in nitric acid to remove any common Pb surface

contamination.

Zircon U-Pb analyses were carried out at the Department of Geological

Sciences, University of Florida, using the “Nu-Plasma” (Nu Instruments, UK) multi-

collector inductively coupled plasma mass spectrometer (LA-MC-ICP-MS). The

mounted zircon grains were ablated using an attached New Wave 213 nm ultraviolet

laser, using a laser spot size of 30 μm for U-Pb analyses. Ar and He carrier gas was

used for sample transport into the mass spectrometer. Before each ablation, a “zero

measurement was taken for 20 s in order to make on-line corrections for isobaric

interferences, especially from 204Hg, a common component of argon gas. Following this

“zero” period, laser ablation commenced for 30 s, keeping a constant ablation pit depth,

27

therefore reducing elemental fractionation. Ablation spot locations were recorded to

insure the direct correlation of U-Pb ages to the data produced from Hf ablation and to

keep record of where the spot was taken (in this case, if the zircon was zoned, spots

would be taken on both the rim and core of the zircon and recorded accordingly).

Ablations occurred in intervals of 10 zircons, directly preceded and followed by ablation

of 2 FC-1 standard zircons.

The U-Pb and Hf isotopic data were recorded using Nu instruments Time

Resolved Analysis (TRA) software. This software allows the user to calculate isotopic

ratios from a desired time segment of data, aiding in the avoidance of complications due

to grain defects or surface contamination. The raw isotopic data garnered from the LA-

MC-ICP-MS were imported into a Microsoft Excel® spreadsheet (Calamari) where

corrections for instrumental drift and mass bias were undertaken by normalization to

standard zircon FC-1from the Duluth Gabbro, dated at 1099.0 ± 0.7 Ma and 1099.1 ±

0.5 Ma by Mattinson (2010). Figures were generated and errors calculated using

Isopolt/Ex plotting software Version 4.11 by Ludwig (2008).

Following U-Pb analyses, Hf isotopic analyses were undertaken on the same LA-

MC-ICP-MS. The same zircons used in U-Pb analyses were ablated, making sure to

note the identity of each zircon so that U-Pb data and Hf data could be compared. A

laser spot size of 40 μm was used for Hf analyses with a 120 s period of ablation and

monitored with FC-1 zircon (Woodhead et al. 2004).

Hf isotopic measurements were made following the procedures outlined by

Mueller et al. (2008). Measured and mass-bias-corrected 176Lu/177Hf ratios were used

to calculate initial 176Hf/177Hf ratios, as described by Griffin et al. (2000, 2002). Overall,

28

the difference between the present-day measured and calculated initial 176Hf/177Hf ratios

in most cases is <1 epsilon (ε) unit, due to very low Lu/Hf ratios. Depleted-mantle

values are based on a linear model (εHf = 0 at 4.56 Ga and 16 at 0 Ga) from Mueller et

al. (2008). Chondritic Uniform Reservoir (CHUR) values are after Blichert-Toft and

Albarede (1997), as recommended by Patchett et al. (2004). The 176Lu decay constant

(1:867 × 10-11 yr-1) is after Soderlund et al. (2004). Isotopic BSE values (Bulk silicate

earth) are from Bouvier et al. (2008).

29

CHAPTER 3 RESULTS

U-Pb Geochronology

Grains that exhibited a discordance of >10 % were excluded from our analysis. If

analyses produced U-Pb ages of <1000 Ma, 206Pb/238U ages were used in our results,

while ages >1000 Ma are represented by 207Pb/206Pb ages. Discordances for each of

these different isotopic age determinations can be found in Table 3-1 and Table 3-2.

The results of all Marwar and Vindhyan detrital zircon samples are listed in Table 3-1

and Table 3-2 and are shown in Figures 3-1 and 3-2.

Vindhyan Samples

Kaimur sandstone sample I9-GS14 was recovered from a roadcrop just outside

the town of Panna (Lat: 24º 39’ 14.52” N, Long: 80º 16’ 10.38” E). I9-GS14 is a well-

sorted, fine grained, quartz rich sandstone. This sample provided 39 concordant detrital

zircons. These zircons ranged in age from ~1.0 - 2.0 Ga with a modal abundance at

~1.6 Ga.

The Rewa sandstone sample I9-GS16 was collected just above the Kaimur-

Rewa contact near Bhadaphur (Lat: 24º 10’ 49.08” N, Long: 80º 48’ 42.3” E). I9-GS16

is a well-sorted, fine grained, brown sandstone. A total of 33 concordant zircons

exhibited ages between ~1.0-~1.9 Ga along with a single Archean zircon dated at 2555

± 16 Ma. A second cross-bedded Rewa sandstone was collected up section from the

Kaimur-Rewa contact (Lat: 24º 12’ 10.38” N, Long: 80º 48’ 45.66” E). This sample (I9-

GS17) produced 29 concordant ages between ~1.0 –~1.8 Ga, along with two Archean

zircons, dated at ~2.48 Ga and ~2.85 Ga.

30

Three samples from the Bhander sandstones were collected. Sample I9-GS20,

a very fine grained, well-sorted, white sandstone, was collected from a predominately

shale unit near Madhogarh (Lat: 24º 34’ 20.28” N, Long: 80º 52’ 15.90” E). A total of 48

concordant detrital zircons were analyzed, with ages of 1.15–1.8 Ga along with a single

Archean zircon with an age of 3.1 Ga.

Bhander sandstone sample I9-GS23 was collected from folded units within the

Great Boundary Fault zone near Bundi (Lat: 25º 26’ 50.1” N, Long: 75º 36’ 52.26” E).

The sandstone is pink, relatively fine-grained with symmetric ripple marks. A total of 50

zircons yielded concordant ages with ages ranging between ~1.0– ~1.9 Ga. The sample

contains an early Paleoproterozoic zircon dated to 2.3 Ga and an Archean zircon dated

to 2.6 Ga.

Bhander sample I9-GS24 is located near Bundi, but away from the Great

Boundary fault and lower in the section than sample I9-GS23 (Lat: 25º 25’ 51.90” N,

Long: 75º 34’ 56.76”). The sandstone is white, poorly sorted, medium to coarse grained,

and contains pebble sized lithic fragments. This sandstone yielded 64 concordant

detrital zircon ages ranging from ~1 - ~2 Ga. Ages are concentrated in two intervals at

1.6 Ga and 1.8 Ga.

Marwar Samples

Five samples were analyzed from different units of the Marwar Supergroup.

These include(a) Basal Marwar sandstone (contact with Malani Igneous Rocks; I9-GS4)

(b) Marwar sandstone from a quarry in Balesar (I9-GS5),(c) a Nagaur sandstone (I9-

GS6) (d) a Jodhpur Marwar sandstone (G-113), and (e) Lower Marwar sandstone from

the Pokaran area (I11-GS19; Figure 1-4).

31

The basal Marwar sandstone that is near the contact with the Malani Igneous

rocks (sample I9-GS4) yielded 52 concordant detrital zircons. I9-GS4 (Lat: 26º 45’

11.64” N, Long: 71º 33’ 12.66” E) is deep purple/brown in color with white to tan

laminations, with well-sorted, intermediate sized grains. Ages range from ~0.7-1.0 Ga,

~1.6-1.8 Ga, and smaller populations of early Paleoproterozoic to Archean ages ranging

from ~2.3-2.7 Ga.

A Sonia Sandstone, I9-GS5 (Jodphur Group), yielded 26 concordant detrital

zircons (Lat: 26º 24’ 38.28” N, Long: 72º 29’ 11.94” E). I9-GS5 is characterized as a

finely laminated, orange to tan in color, well-sorted, intermediate sized grain quartz

sandstone. The sample contains zircons with ages ranging from ~700-900 Ma, ~1.2,

and ~1.6-1.9 Ga. Relatively large concentrations of abundances are at ~1.7 and ~1.8

Ga.

A Nagaur Formation sandstone, I9-GS6, yielded 25 concordant detrital zircon

ages (Lat: 27º 02’ 42.72” N, Long: 73º 29’ 59.58” E). I9-GS6 is a white to grey, poorly

sorted, coarse to medium grained sandstone with large clasts of pebble sized quartz

and other lithic clasts. Prevalent zircon ages are ~700-900 Ma, ~1.7-1.8 Ga. I9-GS6

contains two Archean zircons dated to 3198 ± 5 Ma and 3260 ± 29 Ma.

A Girbahakar sandstone, I11-GS13, yielded 13 concordant detrital zircons (Lat:

26º 19’ 50.45”, Long: 73º 0’ 19.40”). I11-GS13 is a pebble conglomerate sandstone.

Zircons range in age between ~800 Ma 1.7 Ga,

A Nagaur sandstone collected from near the Inana Village (I11-GS19), yielded 42

concordant detrital zircons (Lat: 27º 6’ 36.25”, Long 73º 50’ 17.74”). I11-GS19 is a

reddish sandstone containing abundant ripple marks and cross bedding. Smaller

32

amounts of younger zircons are present in this sample when compared to other yields

from the Marwar, ranging from ~700-1000 Ma. Other ages range from ~1.7-1.9 Ga.

There are several older zircon grains of early Paleoproterozoic and Archean age that

are 2480 ± 12 Ma, 2512 ± 17 Ma, 3114 ± 52 Ma, 3196 ± 13 Ma, and 3249 ± 17 Ma.

Hf Isotopes

Samples for Hf isotopic study were chosen from the Marwar and Vindhyan

Supergroups that had similar zircon ages between ~1.7-1.8 Ga. Fifty-two detrital

zircons were analyzed from the Marwar sequence and 39 detrital zircons were analyzed

from Upper Vindhyan samples (Table 3-3). Present day 176Hf/177Hf values for this

suite of zircons ranged from 0.28183-0.28133. For Marwar samples, 176Hf/177Hf values

lie between 0.28133 and 0.28173. Vindhyan samples showed 176Hf/177Hf values

between 0.28139 and 0.28183.

Deviations of Hf isotopic composition from chrondritic at any time, t, are

expressed in epsilon units (parts per ten thousand), which is given by the formula:

εHf = [ (176Hf/177Hf)t / (176Hf/177Hf)chondrites – 1 ] × 104 (Kinny and Maas). Marwar and

upper Vindhyan sandstone samples reveal zircons with epsilon (ɛ) Hf(t) values that are

mostly comprised of subchondritic ɛHf(t) values, ranging from -13.8 to -0.2. 12 zircons

(4 Marwar, 8 Vindhyan) exhibited superchondritic ɛHf(t) values (i.e. values between the

Chondritic Uniform Reservoir (CHUR) and depleted mantle (DM) reference lines),

ranging from 0.2 to 9.9 (Table 3-3, Figure 3-3). Negative ɛHf(t) values suggest that

these zircons were derived from ancient crust or reworking of the ancient crust, in whole

or in part. Positive ɛHf(t) values are thought to reflect a strong influence from a juvenile

source(s). TDM values (representing the minimum age for the source region that

produced the zircon-bearing magma) range from 1.94 – 2.67 Ga (Table 3-3). It should

33

be noted that values with a % corrected value of greater than 25% are not reliable, but

were included because they do not form the limits of any group of values in our data.

34

Table 3-1. Upper Vindhyan U-Pb Isotopic Data

Ratios

Ages

Sample *207Pb/ 235U

*2σ % error

206Pb/ 238U

2 σ % error

207Pb/ 206Pb

2 σ % error

206Pb/ 238U (Ma)

2 σ error

*207Pb/ 235U (Ma)

*2 σ error

207Pb/ 206Pb (Ma)

2 σ error

% 207Pb/ 206Pb Disc

% 207Pb/235

U Disc I9GS-14_5r 2.086 2.5 0.1905 2.5 0.07942 0.468 1125 26 1144 17 1183 9.2 5 2 I9GS-14_5r.2 2.105 2.8 0.1905 2.7 0.08014 0.441 1125 28 1150 19 1200 8.7 6 2 I9GS-14_15c 5.874 2.7 0.3386 2.7 0.12583 0.299 1881 44 1957 24 2040 5.3 8 4 I9GS-14_15r 6.404 2.5 0.3714 2.5 0.12506 0.339 2038 44 2032 22 2030 6.0 0 0 I9GS14-3c 4.715 7.5 0.3135 7.4 0.10908 0.991 1759 114 1770 62 1784 18.0 1 1 I9GS14-4c 1.799 7.3 0.1716 7.2 0.07603 1.343 1022 68 1045 47 1096 26.9 7 2 I9GS14-10c 3.770 7.4 0.2783 7.3 0.09826 0.931 1584 102 1586 58 1591 17.4 0 0 I9GS14-16c 2.103 7.2 0.1939 7.1 0.07869 1.006 1143 74 1150 49 1164 19.9 2 1 I9GS14-18c 1.673 7.4 0.1639 7.3 0.07402 1.161 979 67 998 47 1042 23.4 6 2 I9GS14-22c 4.147 5.3 0.3061 4.6 0.09826 2.562 1723 70 1663 43 1591 47.8 -8 -4 I9GS14-23c 2.403 6.0 0.2101 5.5 0.08296 2.602 1230 61 1243 43 1268 50.7 3 1 I9GS14-24c 3.792 5.4 0.2778 4.8 0.09902 2.551 1581 67 1591 43 1606 47.5 2 1 I9GS14-25c 1.975 4.7 0.1879 3.9 0.07623 2.626 1111 40 1107 32 1101 52.5 -1 0 I9GS14-26c 4.656 5.4 0.3087 4.8 0.10940 2.556 1736 73 1759 45 1789 46.5 3 1 I9GS14-27c 4.057 4.7 0.2879 3.9 0.10222 2.575 1632 57 1645 38 1665 47.6 2 1 I9GS14-28c 3.627 5.1 0.2697 4.4 0.09752 2.562 1541 60 1555 40 1577 47.9 2 1 I9GS14-31c 2.168 4.8 0.1964 4.0 0.08003 2.672 1157 42 1171 33 1198 52.6 3 1

35

Table 3-1. Continued

Ratios

Ages

Sample *207Pb/ 235U

*2σ % error

206Pb/ 238U

2 σ % error

207Pb/ 206Pb

2 σ % error

206Pb/ 238U (Ma)

2 σ error

*207Pb/ 235U (Ma)

*2 σ error

207Pb/ 206Pb (Ma)

2 σ error

% 207Pb/ 206Pb Disc

% 207Pb/235

U Disc I9GS14-33c 3.870 5.2 0.2698 4.1 0.10403 3.216 1541 56 1607 41 1697 59.2 9 4 I9GS14-34c 2.196 4.5 0.1996 3.7 0.07979 2.571 1174 40 1180 31 1192 50.7 1 0 I9GS14-37c 2.108 5.0 0.1923 4.1 0.07950 2.796 1135 42 1151 34 1185 55.2 4 1 I9GS14-43c 4.828 4.7 0.3166 4.0 0.11059 2.568 1775 62 1790 40 1809 46.6 2 1 I9GS14-44c 2.163 4.7 0.1985 3.9 0.07903 2.556 1168 42 1169 32 1173 50.5 0 0 I9GS14-51c 3.623 5.2 0.2686 4.5 0.09785 2.552 1535 62 1554 41 1583 47.7 3 1 I9GS14-52c 4.601 4.6 0.3076 3.9 0.10849 2.555 1730 58 1749 38 1774 46.6 2 1 I9GS14-53c 4.158 5.1 0.2932 4.4 0.10284 2.578 1659 64 1665 41 1676 47.6 1 0 I9GS14-54c 2.052 5.3 0.1920 4.6 0.07752 2.592 1133 48 1133 36 1135 51.5 0 0 I9GS14-56c 4.516 4.6 0.3085 3.9 0.10619 2.548 1735 59 1734 38 1735 46.7 0 0 I9GS14-59r 2.932 5.8 0.2290 5.1 0.09287 2.797 1330 61 1390 43 1485 52.9 10 4 I9GS14-64r 3.582 5.0 0.2658 4.3 0.09772 2.582 1521 59 1545 40 1581 48.2 4 2 I9GS14-66c 1.792 5.1 0.1732 4.3 0.07504 2.730 1030 41 1042 33 1070 54.8 4 1 I9GS14-68r 1.699 4.8 0.1684 4.0 0.07314 2.576 1004 37 1008 30 1018 52.1 1 0 I9GS14-71c 2.112 5.3 0.1910 4.5 0.08020 2.769 1128 47 1153 36 1202 54.5 6 2 I9GS14-73c 1.736 4.8 0.1666 4.0 0.07555 2.761 994 37 1022 31 1083 55.3 8 3 I9GS14-75c 2.130 4.7 0.1960 3.9 0.07881 2.556 1155 41 1158 32 1167 50.6 1 0

36

Table 3-1. Continued

Ratios

Ages

Sample *207Pb/ 235U

*2σ % error

206Pb/ 238U

2 σ % error

207Pb/ 206Pb

2 σ % error

206Pb/ 238U (Ma)

2 σ error

*207Pb/ 235U (Ma)

*2 σ error

207Pb/ 206Pb (Ma)

2 σ error

% 207Pb/ 206Pb Disc

% 207Pb/235

U Disc I9GS14-76c 1.693 4.7 0.1657 3.9 0.07414 2.631 989 36 1006 30 1045 53.0 5 2 I9GS14-77c 4.562 4.8 0.3026 4.0 0.10935 2.551 1705 60 1742 39 1789 46.4 5 2 I9GS14-78c 4.630 4.8 0.3096 4.1 0.10846 2.547 1740 63 1754 40 1774 46.4 2 1 I9GS14-79c 2.077 4.7 0.1873 3.9 0.08044 2.631 1107 39 1141 32 1208 51.7 8 3 I9GS14-82c 3.723 6.1 0.2785 6.1 0.09695 0.309 1585 86 1576 49 1566 5.8 -1 -1 I9GS14-83c 2.359 5.8 0.2089 5.8 0.08191 0.883 1224 64 1230 41 1243 17.3 2 1 I9GS14-85c 2.067 6.4 0.1896 6.3 0.07906 0.778 1120 65 1138 43 1174 15.4 5 2 I9GS14-86c 2.125 5.9 0.1970 5.9 0.07824 0.785 1160 62 1157 40 1153 15.6 -1 0 I9GS16_3r 2.059 5.0 0.1855 4.9 0.08049 1.238 1098 49 1135 34 1209 24.3 9 3 I9GS16_3r.2 2.060 5.0 0.1897 4.7 0.07876 1.644 1121 48 1135 34 1166 32.5 4 1 I9GS16_6c 3.829 5.1 0.2852 5.0 0.09738 1.039 1619 71 1599 41 1574 19.4 -3 -1 I9GS16_7c 4.175 4.9 0.2950 4.8 0.10264 1.063 1668 70 1669 40 1672 19.6 0 0 I9GS16_8r 1.943 4.7 0.1810 4.6 0.07783 1.254 1073 45 1096 31 1143 24.9 6 2 I9GS16_8c 1.909 4.5 0.1802 4.3 0.07682 1.146 1069 43 1084 30 1117 22.8 4 1 I9GS16_11r 3.984 4.9 0.2837 4.8 0.10187 1.065 1611 68 1631 39 1658 19.7 3 1 I9GS16_11r.2 3.900 4.6 0.2787 4.5 0.10152 1.049 1586 63 1614 37 1652 19.4 4 2 I9GS16_14r 3.697 4.4 0.2630 4.3 0.10196 1.092 1506 58 1570 35 1660 20.2 9 4

37

Table 3-1. Continued

Ratios

Ages

Sample *207Pb/ 235U

*2σ % error

206Pb/ 238U

2 σ % error

207Pb/ 206Pb

2 σ % error

206Pb/ 238U (Ma)

2 σ error

*207Pb/ 235U (Ma)

*2 σ error

207Pb/ 206Pb (Ma)

2 σ error

% 207Pb/ 206Pb Disc

% 207Pb/235

U Disc I9GS16_17c 1.849 4.8 0.1760 4.6 0.07617 1.482 1046 44 1063 31 1100 29.6 5 2 I9GS16_20r 4.889 6.0 0.3099 4.9 0.11441 3.495 1742 74 1800 50 1871 63.0 7 3 I9GS16_22c 5.365 5.1 0.3425 5.0 0.11361 1.000 1900 82 1879 43 1858 18.0 -2 -1 I9GS16_23c 4.024 4.9 0.2872 4.8 0.10160 1.083 1629 69 1639 39 1654 20.0 1 1 I9GS16_27c 1.697 5.1 0.1650 4.9 0.07457 1.314 986 45 1007 32 1057 26.4 7 2 I9GS16_28c 3.709 4.9 0.2777 4.8 0.09690 1.005 1581 67 1573 39 1565 18.8 -1 0 I9GS16_29c 3.732 5.1 0.2767 4.9 0.09784 1.023 1576 69 1578 40 1583 19.1 0 0 I9GS16_30c 1.711 5.3 0.1650 4.8 0.07519 2.237 985 43 1012 33 1074 44.9 8 3 I9GS16_32c 2.053 4.8 0.1863 4.5 0.07993 1.650 1102 46 1133 33 1195 32.5 8 3 I9GS16_33c 1.716 4.9 0.1677 4.8 0.07419 1.128 1000 44 1014 31 1047 22.7 4 1 I9GS16_34c 2.053 4.9 0.1867 4.8 0.07977 1.039 1104 48 1133 33 1191 20.5 7 3 I9GS16_36c 4.671 4.8 0.3118 4.7 0.10864 1.032 1751 72 1762 40 1777 18.8 1 1 I9GS16_37c 3.483 4.8 0.2649 4.7 0.09535 1.026 1516 63 1523 37 1535 19.3 1 0 I9GS16_39c 5.273 6.4 0.3206 6.1 0.11928 1.895 1794 96 1864 54 1945 33.8 8 4 I9GS16_43c 4.835 5.0 0.3200 4.9 0.10959 1.122 1791 76 1791 42 1793 20.4 0 0 I9GS16_44c 2.852 5.1 0.2370 4.9 0.08727 1.028 1372 61 1369 38 1366 19.8 0 0

38

Table 3-1. Continued

Ratios

Ages

Sample *207Pb/ 235U

*2σ % error

206Pb/ 238U

2 σ % error

207Pb/ 206Pb

2 σ % error

206Pb/ 238U (Ma)

2 σ error

*207Pb/ 235U (Ma)

*2 σ error

207Pb/ 206Pb (Ma)

2 σ error

% 207Pb/ 206Pb Disc

% 207Pb/235

U Disc I9GS16_48c 2.091 4.8 0.1898 4.7 0.07989 1.225 1121 48 1146 33 1194 24.1 6 2 I9GS16_49c 3.059 5.0 0.2393 4.9 0.09269 1.105 1384 61 1422 38 1482 20.9 7 3 I9GS16_51c 11.422 5.3 0.4881 5.2 0.16971 0.990 2565 110 2558 49 2555 16.6 0 0 I9GS16_53c 2.121 5.2 0.1903 4.9 0.08083 1.948 1124 50 1155 36 1217 38.3 8 3 I9GS16_56c 3.751 5.0 0.2779 4.9 0.09791 1.023 1582 69 1582 40 1585 19.1 0 0 I9GS16_59c 1.683 4.8 0.1655 4.7 0.07378 1.129 988 43 1002 30 1035 22.8 5 1 I9GS16_60c 2.296 4.9 0.2064 4.8 0.08070 1.174 1210 53 1211 35 1214 23.1 0 0 I9GS17_9c 2.825 10.4 0.2249

10.1 0.09112 2.450 1309 119 1362 77 1449 46.6 10 4

I9GS17_10c 2.149 10.4 0.1944

10.2 0.08018 2.112 1146 107 1165 71 1201 41.6 5 2

I9GS17_11c 3.479 10.9 0.2550

10.7 0.09893 2.082 1465 139 1522 84 1604 38.8 9 4

I9GS17_11r 3.395 10.4 0.2522

10.2 0.09766 2.102 1451 131 1503 80 1580 39.3 8 3

I9GS17_13c 14.625 10.4 0.5233

10.2 0.20268 2.109 2715 224 2791 97 2848 34.3 5 3

I9GS17_13r 14.399 10.4 0.5158

10.2 0.20247 2.127 2683 222 2776 97 2846 34.6 6 3

I9GS17_16c 3.567 10.6 0.2598

10.4 0.09957 2.084 1490 137 1542 82 1616 38.8 8 3

I9GS17_23c 1.561 10.4 0.1545

10.2 0.07329 2.257 927 88 955 64 1022 45.6 9 3

I9GS17_3r 1.550 10.4 0.1543

10.2 0.07289 2.098 926 87 951 63 1011 42.5 8 3

I9GS17_3c 1.543 10.5 0.1538

10.2 0.07278 2.167 923 88 948 64 1008 43.9 8 3

39

Table 3-1. Continued

Ratios

Ages

Sample *207Pb/ 235U

*2σ % error

206Pb/ 238U

2 σ % error

207Pb/ 206Pb

2 σ % error

206Pb/ 238U (Ma)

2 σ error

*207Pb/ 235U (Ma)

*2 σ error

207Pb/ 206Pb (Ma)

2 σ error

% 207Pb/ 206Pb Disc

% 207Pb/235

U Disc I9GS17_5c 99.432 13.7 0.9461

13.5 0.76220 2.143 4296 417 4680 133 4600 36.9 7 8

I9GS17_58c 4.914 10.5 0.3171

10.3 0.11239 2.103 1777 159 1804 87 1838 38.0 3 2

I9GS17_59c 1.666 10.6 0.1635

10.3 0.07392 2.126 977 93 996 66 1039 42.9 6 2

I9GS17_26c 4.371 11.4 0.2974

11.1 0.10662 2.264 1680 164 1707 92 1742 41.4 4 2

I9GS17_27c 4.305 11.3 0.2887

10.3 0.10817 4.457 1636 149 1694 91 1769 81.3 7 3

I9GS17_28c 10.219 10.5 0.4547

10.2 0.16300 2.134 2418 205 2454 95 2487 35.9 3 1

I9GS17_29c.2 10.125 10.5 0.4512

10.3 0.16275 2.090 2403 205 2446 95 2484 35.2 3 2

I9GS17_30c 3.731 10.5 0.2766

10.3 0.09784 2.221 1575 143 1578 83 1583 41.5 0 0

I9GS17_31c 2.592 10.5 0.2251

10.3 0.08352 2.088 1310 122 1298 76 1281 40.6 -2 -1

I9GS17_32r 2.530 10.5 0.2199

10.3 0.08344 2.084 1282 120 1280 75 1280 40.6 0 0

I9GS17_33r 1.585 10.4 0.1584

10.2 0.07257 2.089 949 90 964 64 1002 42.4 5 2

I9GS17_37c 4.065 10.6 0.2875

10.4 0.10253 2.106 1631 149 1647 85 1670 38.9 2 1

I9GS17_38r 4.007 10.5 0.2857

10.3 0.10170 2.096 1621 146 1635 83 1655 38.8 2 1

I9GS17_39c 3.397 10.6 0.2606

10.4 0.09454 2.089 1494 138 1503 81 1519 39.4 2 1

I9GS17_40c 2.103 10.6 0.1947

10.4 0.07835 2.103 1148 109 1150 72 1156 41.7 1 0

I9GS17_43c 2.178 10.6 0.2006

10.4 0.07874 2.132 1179 111 1174 72 1166 42.2 -1 0

I9GS17_45r 3.086 10.5 0.2473

10.3 0.09052 2.127 1426 131 1429 79 1437 40.5 1 0

40

Table 3-1. Continued

Ratios

Ages

Sample *207Pb/ 235U

*2σ % error

206Pb/ 238U

2 σ % error

207Pb/ 206Pb

2 σ % error

206Pb/ 238U (Ma)

2 σ error

*207Pb/ 235U (Ma)

*2 σ error

207Pb/ 206Pb (Ma)

2 σ error

% 207Pb/ 206Pb Disc

% 207Pb/235

U Disc I9GS17_53c 3.031 10.8 0.2369

10.6 0.09280 2.141 1372 130 1415 81 1484 40.5 8 3

I9GS17_54c 3.623 10.5 0.2669

10.3 0.09843 2.114 1526 140 1554 82 1595 39.4 4 2

I9GS20_2c 2.277 5.7 0.2054 5.5 0.08038 1.281 1206 60 1205 40 1206 25.2 0 0 I9GS20_5c 2.573 5.7 0.2203 5.6 0.08473 1.324 1284 65 1293 42 1309 25.7 2 1 I9GS20_10c 2.114 5.7 0.1946 5.6 0.07879 1.283 1147 59 1153 39 1167 25.4 2 1 I9GS20_11c 4.966 5.7 0.3158 5.5 0.11404 1.254 1771 85 1813 47 1865 22.6 5 2 I9GS20_15c 2.350 6.3 0.2125 6.2 0.08020 1.274 1243 70 1227 45 1202 25.1 -3 -1 I9GS20_22c 2.302 5.9 0.1990 5.6 0.08386 1.569 1171 60 1213 41 1289 30.5 9 3 I9GS20_23c 4.499 5.8 0.3061 5.6 0.10661 1.250 1723 85 1731 47 1742 22.9 1 0 I9GS20_24c 20.559 5.8 0.6195 5.6 0.24071 1.232 3110 138 3118 55 3125 19.6 0 0 I9GS20_25c 3.438 5.6 0.2603 5.5 0.09580 1.271 1492 73 1513 44 1544 23.9 3 1 I9GS20_27c 4.807 5.6 0.3171 5.4 0.10997 1.324 1777 84 1786 47 1799 24.1 1 1 I9GS20_30c 3.710 5.5 0.2741 5.4 0.09816 1.250 1563 74 1573 44 1589 23.3 2 1 I9GS20_31c 5.360 5.8 0.3427 5.7 0.11345 1.244 1901 94 1878 49 1855 22.5 -2 -1 I9GS20_32c 5.211 5.7 0.3311 5.5 0.11414 1.241 1845 88 1854 48 1866 22.4 1 0 I9GS20_35c 2.058 5.6 0.1915 5.5 0.07797 1.263 1130 57 1135 38 1146 25.1 1 0 I9GS20_39c 4.535 5.8 0.3067 5.6 0.10727 1.238 1726 85 1737 48 1753 22.6 2 1

41

Table 3-1. Continued

Ratios

Ages

Sample *207Pb/ 235U

*2σ % error

206Pb/ 238U

2 σ % error

207Pb/ 206Pb

2 σ % error

206Pb/ 238U (Ma)

2 σ error

*207Pb/ 235U (Ma)

*2 σ error

207Pb/ 206Pb (Ma)

2 σ error

% 207Pb/ 206Pb Disc

% 207Pb/235

U Disc I9GS20_40c 2.673 5.6 0.2276 5.4 0.08516 1.263 1323 65 1321 41 1319 24.4 0 0 I9GS20_42c 3.535 5.9 0.2671 5.7 0.09598 1.289 1527 77 1535 46 1547 24.2 1 0 I9GS20_44c 2.123 5.8 0.1958 5.6 0.07862 1.318 1154 59 1156 39 1163 26.1 1 0 I9GS20_46c 3.756 5.6 0.2764 5.5 0.09858 1.274 1574 77 1583 45 1597 23.7 1 1 I9GS20_48c 4.672 5.6 0.3128 5.4 0.10831 1.261 1756 83 1762 46 1771 23.0 1 0 I9GS20_49c 3.724 5.6 0.2766 5.4 0.09763 1.281 1576 76 1576 44 1579 23.9 0 0 I9GS20_50c 2.050 5.7 0.1896 5.5 0.07841 1.438 1120 57 1132 39 1157 28.5 3 1 I9GS20_54c 4.640 5.9 0.3145 5.8 0.10701 1.250 1764 89 1756 49 1749 22.8 -1 0 I9GS20_55c 2.337 5.6 0.2081 5.4 0.08143 1.272 1220 60 1223 39 1232 24.9 1 0 I9GS20_56c 3.637 5.6 0.2674 5.5 0.09866 1.268 1529 74 1557 44 1599 23.6 4 2 I9GS20_59c 4.045 5.7 0.2951 5.5 0.09940 1.249 1669 81 1643 46 1613 23.2 -3 -2 I9GS20_60c 2.818 5.7 0.2351 5.5 0.08692 1.244 1362 68 1360 42 1359 23.9 0 0 I9GS20_61c 2.640 2.5 0.2210 2.2 0.08665 1.168 1288 26 1312 18 1353 22.5 5 2 I9GS20_62c 4.507 3.2 0.3094 3.1 0.10566 0.581 1739 47 1732 26 1726 10.7 -1 0 I9GS20_64c 4.771 2.9 0.3079 2.7 0.11240 0.975 1732 41 1780 24 1839 17.6 6 3 I9GS20_65c 2.171 2.6 0.1968 2.4 0.08002 1.035 1159 25 1172 18 1198 20.4 3 1 I9GS20_66c 3.688 2.4 0.2758 2.4 0.09697 0.572 1572 33 1568 19 1567 10.7 0 0

42

Table 3-1. Continued

Ratios

Ages

Sample *207Pb/ 235U

*2σ % error

206Pb/ 238U

2 σ % error

207Pb/ 206Pb

2 σ % error

206Pb/ 238U (Ma)

2 σ error

*207Pb/ 235U (Ma)

*2 σ error

207Pb/ 206Pb (Ma)

2 σ error

% 207Pb/ 206Pb Disc

% 207Pb/235

U Disc I9GS20_67c 2.128 2.5 0.1967 2.5 0.07849 0.548 1158 26 1158 17 1159 10.8 0 0 I9GS20_68c 3.981 2.3 0.2910 2.2 0.09921 0.599 1648 32 1630 19 1609 11.1 -2 -1 I9GS20_70c 3.671 2.3 0.2718 2.2 0.09797 0.689 1551 31 1565 19 1586 12.9 2 1 I9GS20_72c 3.895 2.5 0.2835 2.4 0.09964 0.578 1610 34 1612 20 1617 10.8 0 0 I9GS20_73c 5.128 2.6 0.3275 2.5 0.11356 0.673 1828 40 1840 22 1857 12.1 2 1 I9GS20_76c 2.920 2.6 0.2399 2.5 0.08829 0.605 1387 31 1387 20 1389 11.6 0 0 I9GS20_77c 2.711 1.9 0.2223 1.8 0.08842 0.582 1295 21 1331 14 1392 11.2 7 3 I9GS20_78c 2.134 2.7 0.1986 2.6 0.07790 0.694 1169 27 1160 18 1144 13.8 -2 -1 I9GS20_79c 5.391 2.5 0.3432 2.4 0.11392 0.558 1904 40 1883 21 1863 10.1 -2 -1 I9GS20_81c 4.769 2.8 0.3164 2.7 0.10929 0.551 1774 42 1779 23 1788 10.0 1 0 I9GS20_82c 2.643 2.8 0.2262 2.7 0.08473 0.572 1316 32 1312 20 1309 11.1 -1 0 I9GS20_83c 3.564 2.5 0.2579 2.4 0.10025 0.834 1480 32 1541 20 1629 15.5 9 4 I9GS20_86c 3.096 2.3 0.2470 2.2 0.09091 0.557 1424 28 1432 17 1445 10.6 1 1 I9GS20_87c 3.513 2.6 0.2649 2.5 0.09619 0.666 1516 34 1530 20 1551 12.5 2 1 I9GS20_89c 5.018 2.4 0.3239 2.3 0.11235 0.700 1810 37 1822 20 1838 12.7 1 1 I9GS20_90c 5.426 2.3 0.3393 2.2 0.11600 0.645 1885 36 1889 20 1895 11.6 1 0 I9GS23-2c 3.354 9.0 0.2599 9.0 0.09358 1.017 1491 119 1493 69 1500 19.2 1 0

43

Table 3-1. Continued

Ratios

Ages

Sample *207Pb/ 235U

*2σ % error

206Pb/ 238U

2 σ % error

207Pb/ 206Pb

2 σ % error

206Pb/ 238U (Ma)

2 σ error

*207Pb/ 235U (Ma)

*2 σ error

207Pb/ 206Pb (Ma)

2 σ error

% 207Pb/ 206Pb Disc

% 207Pb/235

U Disc I9GS23-3c 1.811 9.1 0.1771 9.1 0.07419 1.162 1052 88 1049 59 1047 23.4 0 0 I9GS23-5c 4.814 8.9 0.3220 8.9 0.10843 0.960 1801 139 1787 74 1773 17.5 -2 -1 I9GS23-6c 2.349 9.1 0.2132 9.0 0.07992 0.991 1247 102 1227 63 1195 19.5 -4 -2 I9GS23-8c 5.201 9.0 0.3286 8.9 0.11479 1.293 1833 141 1852 75 1877 23.3 2 1 I9GS23-10c 2.774 9.3 0.2285 9.2 0.08805 1.658 1327 110 1348 68 1384 31.8 4 2 I9GS23-12c 3.497 8.9 0.2627 8.8 0.09652 1.004 1505 118 1526 69 1558 18.8 3 1 I9GS23-13c 4.219 9.6 0.2989 9.5 0.10238 1.386 1687 140 1678 77 1668 25.6 -1 -1 I9GS23-15c 3.019 9.1 0.2426 9.1 0.09025 1.093 1401 114 1412 68 1431 20.8 2 1 I9GS23-17c 5.024 9.6 0.3170 9.5 0.11496 1.419 1776 146 1823 80 1879 25.5 5 3 I9GS23-18c 5.006 11.8 0.3262

11.7 0.11129 1.156 1821 185 1820 98 1821 20.9 0 0

I9GS23-19c 3.565 9.1 0.2648 9.0 0.09765 1.002 1516 121 1542 71 1580 18.7 4 2 I9GS23-23c 2.961 9.6 0.2411 9.6 0.08905 1.036 1394 119 1397 72 1405 19.8 1 0 I9GS23-25c 3.449 10.1 0.2585

10.0 0.09676 0.995 1483 132 1515 78 1563 18.6 5 2

I9GS23-27c 5.112 9.0 0.3263 9.0 0.11363 0.951 1822 141 1838 75 1858 17.2 2 1 I9GS23-28c 11.435 9.0 0.4629 9.0 0.17918 0.959 2454 182 2559 82 2645 15.9 7 4 I9GS23-30c 2.181 9.4 0.1952 9.3 0.08101 1.194 1150 97 1175 64 1222 23.4 6 2 I9GS23-32c 4.184 8.5 0.3049 8.5 0.09953 0.684 1717 128 1671 69 1615 12.7 -6 -3

44

Table 3-1. Continued

Ratios

Ages

Sample *207Pb/ 235U

*2σ % error

206Pb/ 238U

2 σ % error

207Pb/ 206Pb

2 σ % error

206Pb/ 238U (Ma)

2 σ error

*207Pb/ 235U (Ma)

*2 σ error

207Pb/ 206Pb (Ma)

2 σ error

% 207Pb/ 206Pb Disc

% 207Pb/235

U Disc I9GS23-33c 4.803 6.6 0.3237 6.5 0.10760 0.590 1809 103 1785 54 1759 10.8 -3 -1 I9GS23-34c 1.946 8.1 0.1880 8.0 0.07506 0.779 1111 82 1097 53 1070 15.6 -4 -1 I9GS23-35c 4.541 6.1 0.3027 6.1 0.10881 0.639 1706 91 1738 51 1780 11.6 4 2 I9GS23-37c 4.714 7.7 0.3283 7.6 0.10416 0.975 1831 121 1770 63 1700 17.9 -8 -3 I9GS23-38c 3.794 7.2 0.2766 7.2 0.09946 0.575 1576 100 1591 57 1614 10.7 2 1 I9GS23-43c 2.247 7.1 0.2052 7.1 0.07939 1.000 1204 77 1196 50 1182 19.7 -2 -1 I9GS23-44c 3.479 6.0 0.2534 6.0 0.09957 0.645 1457 78 1522 47 1616 12.0 10 4 I9GS23-48c 2.579 6.0 0.2190 6.0 0.08540 0.608 1278 70 1294 44 1325 11.8 4 1 I9GS23-49c 1.931 6.5 0.1802 6.4 0.07771 0.896 1069 63 1092 43 1139 17.8 6 2 I9GS23-50c 2.192 6.8 0.1939 6.6 0.08198 1.566 1144 69 1178 47 1245 30.6 8 3 I9GS23-51c 1.940 5.9 0.1844 5.8 0.07630 0.674 1092 59 1095 39 1103 13.5 1 0 I9GS23-53c 2.160 6.3 0.1980 6.2 0.07910 0.634 1166 66 1168 43 1175 12.5 1 0 I9GS23-54c 2.969 6.5 0.2422 6.5 0.08890 0.588 1399 81 1400 49 1402 11.3 0 0 I9GS23-55c 2.929 6.0 0.2347 6.0 0.09054 0.560 1360 73 1389 45 1437 10.7 5 2 I9GS23-57c 3.341 6.2 0.2579 6.1 0.09398 0.596 1480 81 1491 48 1508 11.2 2 1 I9GS23-58c 4.758 6.3 0.3203 6.3 0.10773 0.590 1793 98 1777 52 1761 10.8 -2 -1 I9GS23-59c 2.022 6.5 0.1868 6.3 0.07850 1.628 1105 64 1123 44 1160 32.2 5 2

45

Table 3-1. Continued

Ratios

Ages

Sample *207Pb/ 235U

*2σ % error

206Pb/ 238U

2 σ % error

207Pb/ 206Pb

2 σ % error

206Pb/ 238U (Ma)

2 σ error

*207Pb/ 235U (Ma)

*2 σ error

207Pb/ 206Pb (Ma)

2 σ error

% 207Pb/ 206Pb Disc

% 207Pb/235

U Disc I9GS23-60c 8.325 6.1 0.4101 5.9 0.14721 1.753 2217 109 2267 55 2314 30.0 4 2 I9GS23-61c 3.001 6.0 0.2444 6.0 0.08906 0.573 1410 76 1408 45 1406 10.9 0 0 I9GS23-62c 2.705 6.0 0.2191 6.0 0.08954 0.639 1278 69 1330 44 1416 12.2 10 4 I9GS23-63c 3.647 6.1 0.2725 6.0 0.09708 0.592 1555 83 1560 48 1569 11.1 1 0 I9GS23-65c 3.571 6.0 0.2649 5.9 0.09778 0.766 1516 80 1543 47 1582 14.3 4 2 I9GS23-66c 1.601 6.2 0.1573 6.1 0.07381 0.977 943 54 971 38 1036 19.7 9 3 I9GS23-70c 2.981 5.9 0.2364 5.9 0.09144 0.578 1369 73 1403 45 1456 11.0 6 2 I9GS23-71c 2.980 6.0 0.2387 6.0 0.09054 0.577 1381 74 1402 45 1437 11.0 4 2 I9GS23-72c 4.437 6.2 0.2976 6.1 0.10813 0.689 1681 90 1719 50 1768 12.6 5 2 I9GS23-73c 2.392 6.1 0.2087 6.1 0.08314 0.654 1223 67 1240 43 1272 12.7 4 1 I9GS23-74c 2.132 6.9 0.1928 6.8 0.08019 0.679 1138 71 1159 47 1202 13.4 5 2 I9GS23-75c 4.115 5.9 0.2788 5.9 0.10707 0.642 1586 83 1657 48 1750 11.7 9 4 I9GS23-79c 4.855 5.9 0.3089 5.9 0.11400 0.585 1737 89 1794 49 1864 10.5 7 3 I9GS23-80c 4.469 6.5 0.2953 6.5 0.10976 0.588 1669 95 1725 53 1795 10.7 7 3 I9GS24_4c 5.986 3.3 0.3554 3.1 0.12217 0.979 1962 53 1974 28 1988 17.4 1 1 I9GS24_5c 2.056 3.9 0.1845 3.6 0.08082 1.669 1092 36 1134 27 1217 32.8 10 4 I9GS24_6c 4.688 3.9 0.3132 3.8 0.10854 1.009 1758 58 1765 32 1775 18.4 1 0

46

Table 3-1. Continued

Ratios

Ages

Sample *207Pb/ 235U

*2σ % error

206Pb/ 238U

2 σ % error

207Pb/ 206Pb

2 σ % error

206Pb/ 238U (Ma)

2 σ error

*207Pb/ 235U (Ma)

*2 σ error

207Pb/ 206Pb (Ma)

2 σ error

% 207Pb/ 206Pb Disc

% 207Pb/235

U Disc I9GS24_7c 4.609 3.8 0.3056 3.7 0.10938 0.993 1720 55 1751 31 1789 18.1 4 2 I9GS24_10c 4.536 3.6 0.3045 3.5 0.10804 0.998 1715 52 1737 30 1767 18.2 3 1 I9GS24_11c 2.053 3.5 0.1885 3.3 0.07900 1.179 1114 34 1133 24 1172 23.3 5 2 I9GS24_13c 2.112 3.6 0.1907 3.4 0.08034 1.131 1126 35 1153 25 1205 22.2 7 2 I9GS24_14c 4.602 3.6 0.3075 3.5 0.10855 0.998 1730 53 1749 30 1775 18.2 3 1 I9GS24_15c 4.651 3.8 0.3115 3.6 0.10829 0.975 1749 56 1758 31 1771 17.8 1 0 I9GS24_16c 4.485 4.4 0.2999 4.3 0.10847 1.042 1692 63 1728 36 1774 19.0 5 2 I9GS24_18c 1.568 3.6 0.1615 3.4 0.07041 1.248 966 31 958 22 940 25.5 -3 -1 I9GS24_21c 2.125 3.5 0.1939 3.4 0.07951 1.013 1143 36 1157 24 1185 20.0 3 1 I9GS24_22c 1.731 4.0 0.1661 3.5 0.07560 1.882 991 32 1020 25 1085 37.7 9 3 I9GS24_28c 1.766 3.6 0.1740 3.4 0.07360 1.103 1035 33 1033 23 1031 22.3 0 0 I9GS24_30c 1.638 3.7 0.1640 3.5 0.07245 1.024 980 32 985 23 998 20.8 2 1 I9GS24_31c 1.642 3.4 0.1623 3.2 0.07337 1.118 971 29 986 22 1024 22.6 5 2 I9GS24_32c 3.752 3.9 0.2745 3.7 0.09913 1.041 1565 51 1582 31 1608 19.4 3 1 I9GS24_33c 4.066 3.3 0.2825 3.2 0.10439 1.001 1605 45 1647 27 1704 18.4 6 3 I9GS24_34c 1.994 3.4 0.1849 3.2 0.07819 1.280 1095 32 1113 23 1152 25.4 5 2 I9GS24_37c 3.608 3.6 0.2650 3.4 0.09874 1.105 1517 46 1551 28 1600 20.6 5 2

47

Table 3-1. Continued

Ratios

Ages

Sample *207Pb/ 235U

*2σ % error

206Pb/ 238U

2 σ % error

207Pb/ 206Pb

2 σ % error

206Pb/ 238U (Ma)

2 σ error

*207Pb/ 235U (Ma)

*2 σ error

207Pb/ 206Pb (Ma)

2 σ error

% 207Pb/ 206Pb Disc

% 207Pb/235

U Disc I9GS24_40c 2.112 3.3 0.1949 3.1 0.07858 1.033 1149 33 1153 23 1162 20.4 1 0 I9GS24_42c 3.638 4.1 0.2630 4.0 0.10033 1.024 1506 54 1558 33 1630 19.0 8 3 I9GS24_49c 1.584 4.1 0.1584 3.9 0.07249 1.015 949 35 964 25 1000 20.6 5 2 I9GS24_51c 2.172 3.7 0.1934 3.5 0.08147 1.211 1141 36 1172 26 1233 23.7 7 3 I9GS24_53c 2.120 3.6 0.1917 3.3 0.08018 1.316 1132 34 1155 25 1201 25.9 6 2 I9GS24_57c 2.049 3.3 0.1896 3.2 0.07839 1.043 1120 33 1132 23 1157 20.7 3 1 I9GS24_58c 3.694 3.5 0.2710 3.4 0.09886 0.994 1547 47 1570 28 1603 18.5 3 1 I9GS24_60c 1.743 3.4 0.1687 3.3 0.07491 1.040 1006 30 1024 22 1066 20.9 6 2 I9GS24_61c 1.743 2.6 0.1716 2.5 0.07364 0.695 1022 24 1024 17 1032 14.0 1 0 I9GS24_62c 2.122 2.7 0.1951 2.6 0.07886 0.689 1150 28 1156 19 1169 13.6 2 0 I9GS24_66c 1.707 2.6 0.1696 2.5 0.07302 0.586 1010 24 1011 17 1014 11.9 0 0 I9GS24_67c 2.124 2.4 0.1956 2.3 0.07879 0.601 1152 25 1157 17 1167 11.9 1 0 I9GS24_68c 4.667 2.7 0.3110 2.6 0.10884 0.571 1747 40 1761 22 1780 10.4 2 1 I9GS24_69c 4.176 2.2 0.2792 2.1 0.10846 0.507 1589 29 1669 18 1774 9.2 10 5 I9GS24_72c 1.595 2.9 0.1573 2.7 0.07351 1.261 943 23 968 18 1028 25.5 8 3 I9GS24_73c 3.207 2.5 0.2487 2.4 0.09354 0.709 1433 30 1459 19 1499 13.4 4 2 I9GS24_74c 1.663 2.5 0.1660 2.5 0.07267 0.555 991 23 994 16 1005 11.3 1 0

48

Table 3-1. Continued

Ratios

Ages

Sample *207Pb/ 235U

*2σ % error

206Pb/ 238U

2 σ % error

207Pb/ 206Pb

2 σ % error

206Pb/ 238U (Ma)

2 σ error

*207Pb/ 235U (Ma)

*2 σ error

207Pb/ 206Pb (Ma)

2 σ error

% 207Pb/ 206Pb Disc

% 207Pb/235

U Disc I9GS24_76c 5.048 2.8 0.3200 2.6 0.11440 0.755 1791 41 1827 23 1870 13.6 4 2 I9GS24_77c 4.958 2.7 0.3169 2.6 0.11347 0.629 1776 40 1812 22 1856 11.4 4 2 I9GS24_79c 3.678 2.7 0.2704 2.6 0.09864 0.783 1544 35 1566 21 1599 14.6 3 1 I9GS24_82c 2.038 2.8 0.1873 2.6 0.07892 1.071 1108 26 1128 19 1170 21.2 5 2 I9GS24_83c 2.133 2.7 0.1946 2.6 0.07950 0.686 1147 28 1159 19 1185 13.5 3 1 I9GS24_86c 2.096 2.7 0.1900 2.5 0.08000 0.948 1122 26 1147 19 1197 18.7 6 2 I9GS24_88c 3.769 2.8 0.2750 2.7 0.09940 0.686 1567 38 1586 22 1613 12.8 3 1 I9GS24_90c 2.186 2.6 0.1983 2.5 0.07994 0.554 1167 27 1176 18 1195 10.9 2 1 I9GS24_92c 4.685 2.5 0.3141 2.4 0.10815 0.551 1762 37 1764 21 1769 10.1 0 0 I9GS24_94c 4.642 2.5 0.3124 2.5 0.10775 0.562 1754 38 1757 21 1762 10.3 0 0 I9GS24_95c 2.337 2.5 0.2087 2.4 0.08122 0.525 1223 27 1224 18 1227 10.3 0 0 I9GS24_96c 1.660 2.5 0.1649 2.3 0.07301 0.851 985 21 993 16 1014 17.2 3 1 I9GS24_97c 3.854 2.5 0.2827 2.4 0.09889 0.525 1606 35 1604 20 1603 9.8 0 0 I9GS24_98c 2.173 2.7 0.1990 2.6 0.07920 0.706 1171 28 1172 19 1177 13.9 1 0 I9GS24_99c 2.179 2.7 0.1983 2.6 0.07968 0.685 1167 28 1174 19 1189 13.5 2 1 I9GS24_101c 3.768 2.5 0.2778 2.4 0.09835 0.556 1582 34 1586 20 1593 10.4 1 0 I9GS24_102c 2.091 3.0 0.1889 2.9 0.08031 0.818 1116 30 1146 21 1205 16.1 7 3

49

Table 3-1. Continued

Ratios

Ages

Sample *207Pb/ 235U

*2σ % error

206Pb/ 238U

2 σ % error

207Pb/ 206Pb

2 σ % error

206Pb/ 238U (Ma)

2 σ error

*207Pb/ 235U (Ma)

*2 σ error

207Pb/ 206Pb (Ma)

2 σ error

% 207Pb/ 206Pb Disc

% 207Pb/235

U Disc I9GS24_103c 2.055 2.7 0.1907 2.7 0.07814 0.692 1126 27 1134 19 1150 13.7 2 1 I9GS24_104c 4.613 3.2 0.3099 3.1 0.10798 0.572 1742 48 1751 27 1766 10.4 1 1 I9GS24_105c 2.079 2.8 0.1919 2.8 0.07858 0.653 1132 29 1142 19 1162 12.9 3 1 I9GS24_109c 1.919 2.8 0.1833 2.7 0.07595 0.594 1086 27 1088 18 1094 11.9 1 0 I9GS24_112c 2.491 2.5 0.2144 2.4 0.08429 0.718 1253 27 1269 18 1299 13.9 4 1 I9GS24_116c 4.591 3.0 0.3092 2.9 0.10769 0.524 1738 44 1747 25 1761 9.6 1 1 I9GS24_117c 4.562 2.6 0.3079 2.5 0.10747 0.563 1732 38 1742 21 1757 10.3 1 1 I9GS24_119c 3.664 2.5 0.2719 2.3 0.09773 0.723 1552 32 1563 19 1581 13.5 2 1 I9GS24_120c 2.174 2.6 0.1968 2.5 0.08015 0.799 1159 27 1173 18 1201 15.7 3 1

50

Table 3-2. Marwar U-Pb Isotopic Data

Ratios

Ages

Sample

207Pb/ 235U

±2δ (%)

206Pb/ 238U

±2δ (%)

207Pb/ 206Pb

±2δ (%)

206Pb/ 238U (Ma) ±2δ

207Pb/ 235U (Ma) ±2δ

207Pb/ 206Pb (Ma) ±2δ

% 207Pb/ 206Pb Disc

% 207Pb/ 235U Disc

I9GS-4_4c 5.040 4.4 0.3169 4.3

0.11536 0.880 1776 66 1826 37 1886 15.8 6 3

I9GS-4_5c 10.621 4.2 0.4566 4.1

0.16869 0.876 2427 83 2490 39 2545 14.7 5 3

I9GS-4_7c 1.337 4.6 0.1390 4.5

0.06978 1.119 839 35 862 27 922 23.0 9 3

I9GS-4_11c 4.627 4.1 0.3039 4.0

0.11045 0.903 1712 59 1754 34 1807 16.4 5 2

I9GS-4_11r 4.777 4.1 0.3143 4.0

0.11022 0.911 1763 62 1781 34 1803 16.5 2 1

I9GS-4_11r.2 4.716 4.1 0.3096 3.9

0.11047 0.944 1740 60 1770 34 1807 17.1 4 2

I9GS-4_17core 4.605 4.3 0.3055 4.2

0.10931 0.946 1720 64 1750 36 1788 17.2 4 2

I9GS-4_17r 4.441 4.1 0.2959 4.0

0.10887 0.912 1672 59 1720 34 1781 16.6 6 3

I9GS-4_17r.2 4.536 4.2 0.3025 4.1

0.10875 0.947 1705 61 1737 34 1779 17.2 4 2

I9GS-4_23c 5.215 4.4 0.3317 4.4

0.11401 0.880 1848 70 1855 38 1864 15.9 1 0

I9GS-4_26c 4.402 4.2 0.3016 4.1

0.10588 0.864 1700 62 1713 35 1730 15.8 2 1

I9GS-4_28c 4.541 4.3 0.3039 4.2

0.10837 0.868 1712 63 1738 35 1772 15.8 3 2

I9GS-4_34c 3.856 4.4 0.2746 4.3

0.10183 0.877 1565 59 1604 35 1658 16.2 6 2

I9GS-4_36c 5.159 4.2 0.3263 4.1

0.11467 0.880 1822 65 1846 36 1875 15.8 3 1

I9GS-4_36r 4.928 5.0 0.3084 4.9

0.11591 0.897 1734 74 1807 41 1894 16.1 8 4

51

Table 3-2. Continued

Ratios

Ages

Sample

207Pb/ 235U

±2δ (%)

206Pb/ 238U

±2δ (%)

207Pb/ 206Pb

±2δ (%)

206Pb/ 238U (Ma) ±2δ

207Pb/ 235U (Ma) ±2δ

207Pb/ 206Pb (Ma) ±2δ

% 207Pb/ 206Pb Disc

% 207Pb/ 235U Disc

I9GS-4_40c 4.181 5.6 0.2839 5.5

0.10681 1.116 1612 78 1670 45 1746 20.4 8 3

I9GS-4_41c 4.387 4.2 0.2976 4.1

0.10692 0.950 1681 60 1710 34 1748 17.4 4 2

I9GS-4_45c 4.418 4.1 0.3027 4.0

0.10586 0.886 1706 60 1715 34 1729 16.2 1 1

I9GS-4_46c 1.303 4.3 0.1382 4.1

0.06843 1.173 835 32 847 25 882 24.2 5 1

I9GS-4_46r 1.340 4.2 0.1399 4.0

0.06945 1.282 845 32 863 24 912 26.3 7 2

I9GS-4_49c 14.058 4.2 0.5164 4.1

0.19746 0.856 2686 90 2753 39 2805 14.0 4 2

I9GS-4_53c 4.346 4.3 0.2967 4.2

0.10624 0.874 1676 61 1702 35 1736 16.0 3 2

I9GS-4_55c 4.365 4.1 0.3002 4.0

0.10548 0.887 1693 59 1706 33 1723 16.3 2 1

I9GS-4_56c 3.641 4.3 0.2617 4.2

0.10089 0.923 1500 56 1558 34 1641 17.1 9 4

I9GS-4_58c 4.488 4.2 0.3002 4.1

0.10841 0.898 1694 61 1728 35 1773 16.4 4 2

I9GS-4_58r 4.483 4.2 0.3005 4.1

0.10820 0.891 1695 61 1728 34 1769 16.3 4 2

I9GS-4_60c 12.625 4.0 0.4952 3.9

0.18491 0.853 2595 84 2652 37 2697 14.1 4 2

I9GS-4_62r 12.287 4.6 0.4870 4.5

0.18296 0.796 2560 95 2626 42 2680 13.1 4 3

I9GS-4_64c 4.287 4.8 0.2942 4.7

0.10567 1.004 1664 69 1691 39 1726 18.4 4 2

I9GS-4_65c 6.561 4.4 0.3689 4.3

0.12899 0.828 2026 75 2054 38 2084 14.5 3 1

I9GS-4_67c 1.351 4.4 0.1407 4.2

0.06962 1.050 849 34 868 25 917 21.6 7 2

I9GS-4_68c 1.603 4.2 0.1593 4.1

0.07296 0.904 954 37 971 26 1013 18.3 6 2

52

Table 3-2. Continued

Ratios

Ages

Sample

207Pb/ 235U

±2δ (%)

206Pb/ 238U

±2δ (%)

207Pb/ 206Pb

±2δ (%)

206Pb/ 238U (Ma) ±2δ

207Pb/ 235U (Ma) ±2δ

207Pb/ 206Pb (Ma) ±2δ

% 207Pb/ 206Pb Disc

% 207Pb/ 235U Disc

I9GS-4_69c 1.121 4.4 0.1225 4.1

0.06635 1.410 745 29 763 23 818 29.4 9 2

I9GS-4_69r 1.124 4.4 0.1243 4.3

0.06558 1.256 756 30 765 24 793 26.3 5 1

I9GS-4_71c 4.182 4.8 0.2796 4.7

0.10845 0.791 1591 66 1670 39 1774 14.4 10 5

I9GS-4_71r 4.225 4.4 0.2812 4.3

0.10895 0.803 1599 61 1679 36 1782 14.6 10 5

I9GS-4_74c 4.138 4.9 0.2782 4.8

0.10786 0.959 1584 67 1662 40 1764 17.5 10 5

I9GS-4_76c 1.340 5.1 0.1386 4.8

0.07010 1.572 838 38 863 29 931 32.2 10 3

I9GS-4_78c 4.404 4.4 0.3011 4.2

0.10606 0.952 1698 63 1713 36 1733 17.4 2 1

I9GS-4_85c 4.303 4.3 0.2955 4.2

0.10562 0.908 1670 62 1694 35 1725 16.6 3 1

I9GS-4_86c 4.893 4.8 0.3081 4.7

0.11516 0.862 1733 71 1801 40 1882 15.5 8 4

I9GS-4_88c 1.381 4.6 0.1444 4.4

0.06936 1.475 870 35 881 27 909 30.3 4 1

I9GS-4_90c 13.422 4.4 0.5038 4.3

0.19321 0.799 2632 92 2709 41 2770 13.1 5 3

I9GS-4_90r 13.109 4.5 0.5002 4.4

0.19009 0.829 2617 95 2687 42 2743 13.6 5 3

I9GS-4_92c 8.422 4.5 0.4149 4.5

0.14722 0.817 2239 84 2277 41 2314 14.0 3 2

I9GS-4_93c 8.513 4.3 0.4191 4.3

0.14733 0.798 2258 81 2287 39 2315 13.7 2 1

I9GS-4_94c 1.639 4.4 0.1600 4.3

0.07429 0.932 958 38 985 28 1049 18.8 9 3

I9GS-4_95c 4.289 4.7 0.2851 4.5

0.10914 1.268 1618 65 1691 38 1785 23.1 9 4

I9GS5-3c 4.040 6.5 0.2857 6.5

0.10254 0.715 1622 92 1642 52 1671 13.2 3 1

53

Table 3-2. Continued

Ratios

Ages

Sample

207Pb/ 235U

±2δ (%)

206Pb/ 238U

±2δ (%)

207Pb/ 206Pb

±2δ (%)

206Pb/ 238U (Ma) ±2δ

207Pb/ 235U (Ma) ±2δ

207Pb/ 206Pb (Ma) ±2δ

% 207Pb/ 206Pb Disc

% 207Pb/ 235U Disc

I9GS5-5c 1.406 5.6 0.1443 5.5

0.07068 1.375 870 44 891 33 948 28.1 8 2

I9GS5-13c 4.246 5.7 0.2917 5.7

0.10559 0.500 1651 83 1683 46 1725 9.2 4 2

I9GS5-14c 2.407 7.2 0.2144 6.6

0.08143 2.813 1253 75 1244 51 1232 55.1 -2 -1

I9GS5-15c 4.432 5.7 0.3021 5.6

0.10641 0.507 1703 84 1718 46 1739 9.3 2 1

I9GS5-19c 2.913 6.9 0.2353 5.8

0.08982 3.838 1363 71 1385 52 1422 73.2 4 2

I9GS5-20c 4.885 6.5 0.3168 6.4

0.11182 0.841 1776 99 1799 54 1829 15.2 3 1

I9GS5-21c 1.198 7.2 0.1327 7.1

0.06551 0.714 804 54 800 39 791 15.0 -2 -1

I9GS5-28c 1.302 6.7 0.1382 6.6

0.06832 1.113 835 52 847 38 878 23.0 5 1

I9GS5-29c 1.391 6.8 0.1441 6.7

0.06998 1.044 869 55 885 40 928 21.4 6 2

I9GS5-30c 5.213 6.8 0.3191 6.7

0.11847 0.704 1787 104 1854 57 1933 12.6 8 4

I9GS5-31c 5.305 7.0 0.3380 7.0

0.11385 0.666 1878 113 1869 59 1862 12.0 -1 0

I9GS5-32c 4.810 6.8 0.3137 6.7

0.11119 1.049 1761 103 1786 56 1819 19.0 3 1

I9GS5-33c 1.189 6.9 0.1325 6.9

0.06509 0.780 803 52 795 38 777 16.4 -3 -1

I9GS5-34c 1.364 6.7 0.1435 6.7

0.06891 0.979 865 54 873 39 896 20.2 3 1

I9GS5-38c 1.214 7.0 0.1313 6.9

0.06705 1.020 796 52 807 38 839 21.2 5 1

I9GS5-40c 5.293 6.7 0.3398 6.6

0.11298 0.853 1887 108 1867 56 1848 15.4 -2 -1

I9GS5-41c 4.889 7.1 0.3197 7.0

0.11093 1.132 1789 109 1800 59 1815 20.5 1 1

54

Table 3-2. Continued

Ratios

Ages

Sample

207Pb/ 235U

±2δ (%)

206Pb/ 238U

±2δ (%)

207Pb/ 206Pb

±2δ (%)

206Pb/ 238U (Ma) ±2δ

207Pb/ 235U (Ma) ±2δ

207Pb/ 206Pb (Ma) ±2δ

% 207Pb/ 206Pb Disc

% 207Pb/ 235U Disc

I9GS5-42c 5.400 7.0 0.3403 7.0

0.11509 0.687 1889 114 1885 59 1881 12.4 0 0

I9GS5-43c 4.533 6.7 0.3117 6.7

0.10549 0.691 1750 102 1737 55 1723 12.7 -2 -1

I9GS5-44c 4.466 9.2 0.2896 9.1

0.11185 1.142 1641 131 1724 75 1830 20.7 10 5

I9GS5-45c 4.726 6.9 0.3127 6.8

0.10960 0.676 1756 105 1772 57 1793 12.3 2 1

I9GS5-46c 4.720 7.2 0.3147 7.1

0.10877 0.815 1765 110 1770 59 1779 14.8 1 0

I9GS5-48c 4.694 6.9 0.3083 6.9

0.11041 0.703 1734 104 1766 57 1806 12.8 4 2

I9GS5-50c 4.922 7.2 0.3181 7.1

0.11223 1.091 1782 110 1806 60 1836 19.7 3 1

I9GS5-51c 2.185 6.6 0.1954 6.6

0.08108 0.739 1152 69 1176 45 1223 14.5 6 2

I9GS5-52c 1.390 6.9 0.1465 6.8

0.06882 0.804 882 56 885 40 893 16.6 1 0

19GS-6_1c 1.180 3.7 0.1293 3.1

0.06622 1.921 784 23 791 20 813 40.1 4 1

19GS-6_4c 3.986 3.8 0.2759 3.3

0.10478 1.888 1572 47 1631 31 1710 34.7 8 4

I9GS-6_6c 5.012 3.8 0.3188 3.3

0.11402 1.858 1785 52 1821 32 1864 33.5 4 2

I9GS-6_7c 5.181 3.8 0.3306 3.3

0.11366 1.879 1843 53 1849 32 1859 33.9 1 0

I9GS-6_9c 4.268 4.1 0.2971 3.6

0.10418 1.873 1678 54 1687 33 1700 34.5 1 1

I9GS-6_9r 4.015 3.8 0.2780 3.3

0.10476 1.861 1583 47 1637 31 1710 34.2 7 3

I9GS-6_13c 1.339 3.9 0.1428 3.5

0.06801 1.878 861 28 863 23 869 38.9 1 0

I9GS-6_13r 1.345 3.8 0.1435 3.3

0.06796 1.878 865 27 865 22 867 38.9 0 0

55

Table 3-2. Continued

Ratios

Ages

Sample

207Pb/ 235U

±2δ (%)

206Pb/ 238U

±2δ (%)

207Pb/ 206Pb

±2δ (%)

206Pb/ 238U (Ma) ±2δ

207Pb/ 235U (Ma) ±2δ

207Pb/ 206Pb (Ma) ±2δ

% 207Pb/ 206Pb Disc

% 207Pb/ 235U Disc

19GS-6_23c 4.829 5.1 0.3047 3.8

0.11497 3.472 1716 57 1790 43 1879 62.5 9 4

I9GS-6_25c 21.283 3.9 0.5926 3.4

0.26046 1.856 3003 81 3151 37 3249 29.2 8 5

I9GS-6_25r 21.700 3.7 0.6014 3.2

0.26172 1.855 3038 78 3170 36 3257 29.2 7 4

I9GS-6_25r.2 22.150 3.6 0.6126 3.1

0.26222 1.854 3083 77 3190 35 3260 29.1 5 3

I9GS-6_34c 4.677 3.8 0.3056 3.3

0.11101 1.998 1720 49 1763 32 1816 36.2 5 2

I9GS-6_39c 4.216 4.0 0.2882 3.5

0.10610 1.862 1634 51 1677 32 1734 34.1 6 3

I9GS-6_39r 4.300 4.0 0.2935 3.5

0.10628 1.866 1660 51 1693 32 1737 34.2 4 2

I9GS-6_45c 1.317 2.9 0.1386 2.8

0.06890 0.569 838 22 853 17 896 11.7 6 2

I9GS-6_51c 4.952 2.8 0.3165 2.8

0.11350 0.432 1774 43 1811 23 1856 7.8 4 2

I9GS-6_53c 4.744 2.8 0.3055 2.8

0.11263 0.392 1720 42 1775 23 1842 7.1 7 3

I9GS-6_59c 1.107 3.3 0.1231 3.3

0.06525 0.593 749 23 757 18 783 12.4 4 1

I9GS-6_60c 1.119 3.0 0.1245 2.9

0.06524 0.593 757 21 763 16 782 12.4 3 1

I9GS-6_64c 20.186 2.9 0.5807 2.9

0.25211 0.331 2954 69 3100 28 3198 5.2 8 5

2011GS19_1c 4.366 5.1 0.3029 5.0

0.10454 1.017 1707 75 1706 42 1706 18.7 0 0

2011GS19_1r 4.420 5.1 0.3078 5.0

0.10415 0.992 1731 76 1716 42 1699 18.2 -2 -1

56

Table 3-2. Continued

Ratios

Ages

Sample

207Pb/ 235U

±2δ (%)

206Pb/ 238U

±2δ (%)

207Pb/ 206Pb

±2δ (%)

206Pb/ 238U (Ma) ±2δ

207Pb/ 235U (Ma) ±2δ

207Pb/ 206Pb (Ma) ±2δ

% 207Pb/ 206Pb Disc

% 207Pb/ 235U Disc

2011GS19_3c 1.242 5.1 0.1364 5.0

0.06601 1.036 825 39 819 29 807 21.7 -2 -1

2011GS19_4c 1.208 5.3 0.1319 5.2

0.06640 1.048 800 39 804 29 819 21.9 2 1

2011GS19_11c 5.177 5.7 0.3175 5.3

0.11826 2.324 1779 81 1849 48 1930 41.6 8 4

2011GS19_12c 10.899 4.8 0.4779 4.7

0.16542 0.991 2520 97 2514 44 2512 16.6 0 0

2011GS19_25c 4.774 6.3 0.3208 6.2

0.10793 0.984 1795 97 1780 52 1765 18.0 -2 -1

2011GS19_25r 4.300 7.4 0.2867 7.3

0.10879 1.049 1626 104 1693 60 1779 19.1 9 4

2011GS19_47r 4.317 6.3 0.2980 6.2

0.10506 0.972 1683 91 1696 51 1715 17.8 2 1

2011GS19_47r.2 4.201 5.2 0.2904 5.1

0.10492 0.981 1645 74 1674 42 1713 18.0 4 2

2011GS19_47r.3 4.737 4.4 0.3284 4.3

0.10463 0.968 1832 69 1774 37 1708 17.8 -7 -3

2011GS19_47r.4 5.135 8.0 0.3171 6.4

0.11744 4.899 1777 99 1842 67 1918 87.7 7 4

2011GS19_47c 4.444 4.5 0.3090 4.4

0.10430 0.962 1737 67 1720 37 1702 17.7 -2 -1

57

Table 3-2. Continued

Ratios

Ages

Sample

207Pb/ 235U

±2δ (%)

206Pb/ 238U

±2δ (%)

207Pb/ 206Pb

±2δ (%)

206Pb/ 238U (Ma) ±2δ

207Pb/ 235U (Ma) ±2δ

207Pb/ 206Pb (Ma) ±2δ

% 207Pb/ 206Pb Disc

% 207Pb/ 235U Disc

2011GS19_51c 18.292 5.3 0.5549 4.1

0.23909 3.288 2848 94 3005 50 3114 52.3 9 5

2011GS19_63r 4.730 4.7 0.3099 4.6

0.11070 0.946 1742 70 1772 39 1811 17.2 4 2

2011GS19_63c 4.909 5.1 0.3236 5.0

0.11003 0.667 1809 79 1803 42 1800 12.1 -1 0

2011GS19_63c.2 5.075 5.3 0.3350 5.3

0.10986 0.626 1864 85 1832 45 1797 11.4 -4 -2

2011GS19_63r 4.816 4.2 0.3193 4.1

0.10938 0.938 1788 64 1787 35 1789 17.1 0 0

2011GS19_63r 4.796 4.2 0.3169 4.1

0.10977 0.541 1776 64 1784 35 1796 9.8 1 0

2011GS19_63r 4.643 7.5 0.3072 7.4

0.10964 0.614 1728 112 1757 61 1793 11.2 4 2

2011GS19_86c 23.847 6.4 0.6644 6.3

0.26033 1.065 3287 161 3262 61 3249 16.7 -1 -1

2011GS19_87r 20.212 12.9 0.5824 12.8

0.25171 0.823 2961 302 3101 121 3196 13.0 7 5

2011GS19_92c 90.326 34.5 0.9390 34.1

0.69766 5.129 4272 1025 4583 320 4600 80.8 7 7

2011GS19_95r 9.818 9.2 0.4389 9.2

0.16225 0.674 2348 180 2417 83 2479 11.3 5 3

58

Table 3-2. Continued

Ratios

Ages

Sample

207Pb/ 235U

±2δ (%)

206Pb/ 238U

±2δ (%)

207Pb/ 206Pb

±2δ (%)

206Pb/ 238U (Ma) ±2δ

207Pb/ 235U (Ma) ±2δ

207Pb/ 206Pb (Ma) ±2δ

% 207Pb/ 206Pb Disc

% 207Pb/ 235U Disc

2011GS19_95c 10.282 5.5 0.4625 5.5

0.16125 0.505 2452 111 2460 50 2469 8.5 1 0

2011GS19_95c.2 10.504 4.5 0.4715 4.5

0.16157 0.498 2492 92 2480 41 2472 8.4 -1 0

2011GS19_95r 10.127 5.6 0.4524 5.6

0.16236 0.693 2408 111 2446 51 2480 11.7 3 2

2011GS19_95r 10.006 3.7 0.4525 3.6

0.16039 0.483 2408 73 2435 34 2460 8.1 2 1

2011GS19_99c 1.274 4.7 0.1382 4.6

0.06683 0.770 835 36 834 26 832 16.0 0 0

2011G19_107c 1.763 5.1 0.1683 4.6

0.07597 2.199 1004 43 1032 33 1094 44.0 8 3

2011G19_110c 1.061 4.9 0.1187 4.8

0.06484 0.734 724 33 734 25 769 15.4 6 1

2011GS19_114r 1.660 4.9 0.1655 4.8

0.07278 0.948 988 44 993 31 1008 19.2 2 1

2011GS19_114r.2 1.693 5.9 0.1642 5.5

0.07479 2.068 981 50 1006 37 1063 41.5 8 2

2011GS19_118c 1.136 5.7 0.1262 5.7

0.06527 0.612 767 41 770 30 783 12.8 2 0

2011GS19_120c 4.380 8.2 0.2889 8.0

0.10993 1.553 1638 116 1708 66 1798 28.2 9 4

59

Table 3-2. Continued

Ratios

Ages

Sample

207Pb/ 235U

±2δ (%)

206Pb/ 238U

±2δ (%)

207Pb/ 206Pb

±2δ (%)

206Pb/ 238U (Ma) ±2δ

207Pb/ 235U (Ma) ±2δ

207Pb/ 206Pb (Ma) ±2δ

% 207Pb/ 206Pb Disc

% 207Pb/ 235U Disc

2011GS19_120r 4.750 5.5 0.3129 5.4

0.11011 1.433 1756 82 1776 46 1801 26.0 2 1

2011GS19_130r 3.713 8.2 0.2652 7.7

0.10153 2.846 1518 104 1574 65 1652 52.7 8 4

2011GS19_130c 4.333 5.8 0.2880 5.5

0.10911 1.905 1633 79 1699 47 1785 34.7 8 4

2011GS19_133c 4.559 6.8 0.3110 6.6

0.10633 1.528 1747 101 1742 56 1738 28.0 -1 0

2011GS19_142c 5.391 6.2 0.3379 6.0

0.11572 1.506 1878 98 1883 53 1891 27.1 1 0

2011GS19_175c 5.095 5.6 0.3377 5.5

0.10942 1.403 1877 89 1835 47 1790 25.5 -5 -2

2011GS19_175r 4.656 6.9 0.3074 6.8

0.10985 1.503 1729 102 1759 57 1797 27.3 4 2

2011GS19_175c 5.118 5.4 0.3399 5.3

0.10920 1.394 1888 86 1839 46 1786 25.4 -6 -3

2011GS19_184c 22.357 339.2 0.6796 240.0

0.23859

239.672 3346 5107 3199 1958 3111 3810.5 -8 -5

2011GS19_185c 24.772 339.1 0.7131 239.9

0.25197

239.672 3473 5225 3299 1963 3197 3784.1 -9 -5

2011GS19_186c 25.496 339.1 0.7273 239.9

0.25424

239.671 3526 5275 3327 1965 3211 3780.3 -10 -6

60

Table 3-2. Continued

Ratios

Ages

Sample

207Pb/ 235U

±2δ (%)

206Pb/ 238U

±2δ (%)

207Pb/ 206Pb

±2δ (%)

206Pb/ 238U (Ma) ±2δ

207Pb/ 235U (Ma) ±2δ

207Pb/ 206Pb (Ma) ±2δ

% 207Pb/ 206Pb Disc

% 207Pb/ 235U Disc

G113-4c 1.356 7.2 0.1419 4.6

0.06935 5.491 856 37 870 42 909 112.9 6 2

G113-14c 1.336 7.5 0.1401 4.8

0.06912 5.753 846 38 861 43 902 118.5 6 2

G113-18c 1.312 6.8 0.1401 4.0

0.06792 5.552 846 32 851 39 866 115.0 2 1

G113-23c 4.362 7.0 0.3078 4.3

0.10279 5.533 1731 65 1705 57 1675 102.1 -3 -2

G113-27c 4.584 6.8 0.3182 4.1

0.10449 5.483 1782 63 1746 56 1705 100.8 -5 -2

G113-48c 1.604 7.3 0.1596 4.6

0.07287 5.709 956 41 972 45 1010 115.6 5 2

G113-52c 4.779 7.5 0.3138 5.1

0.11044 5.493 1761 79 1781 62 1807 99.7 3 1

G113-58c 1.309 7.5 0.1401 4.5

0.06774 6.039 846 35 850 43 861 125.2 2 0

G113-61c 1.261 9.4 0.1352 7.3

0.06763 5.921 818 56 828 53 857 122.8 5 1

G113-69c 1.419 10.1 0.1508 7.9

0.06825 6.241 906 67 897 59 876 129.0 -3 -1

G113-71c 4.892 9.2 0.3357 7.1

0.10569 5.862 1867 115 1801 76 1726 107.5 -8 -4

G113-72c 1.349 11.1 0.1435 7.4

0.06819 8.333 865 60 867 64 874 172.3 1 0

G113-79c 1.556 10.5 0.1550 8.2

0.07281 6.535 930 71 953 64 1009 132.4 8 2

61

Table 3-3. Hf Isotopic Data

Sample #

176Hf/ 177Hf

uncorr. 176Hf/177Hf

corr. error (+/-) εHf Hf (V) 175Lu (V) 172Yb (V)

176Lu/ 177Hf measured and mass biased corrected

176Hf/ 177Hf initial

Model Age (CHUR) By

Model Age (DM) By

176/ 177Hf

(CHUR) T

εHf(t) % corr

I9GS4-11 0.32718 0.281613 0.000018 -41 1.20 0.008 0.018 0.00088 0.281583 1.89 2.26 0.281633 -1.8 14 I9GS4-17 0.28646 0.281493 0.000018 -45 1.19 0.001 0.002 0.00008 0.281490 2.03 2.37 0.281650 -5.7 2 I9GS4-23 0.31382 0.281498 0.000026 -45 1.00 0.004 0.011 0.00059 0.281477 2.05 2.40 0.281596 -4.2 10 I9GS4-26 0.30480 0.281526 0.00003 -44 0.98 0.003 0.007 0.00044 0.281511 2.00 2.35 0.281682 -6.1 8 I9GS4-27 0.31447 0.281489 0.000026 -45 0.77 0.004 0.008 0.00063 0.281468 2.07 2.41 0.281684 -7.7 10 I9GS4-28 0.31328 0.281623 0.000034 -40 0.92 0.004 0.009 0.00059 0.281603 1.85 2.23 0.281654 -1.8 10 I9GS4-32 0.34739 0.281455 0.000027 -46 0.92 0.007 0.020 0.00107 0.281418 2.15 2.49 0.281637 -7.8 19 I9GS4-34 0.30891 0.281461 0.000041 -46 0.86 0.003 0.008 0.00052 0.281444 2.11 2.44 0.281700 -9.1 9 I9GS4-36 0.33351 0.281614 0.000018 -41 1.07 0.008 0.018 0.00097 0.281580 1.89 2.26 0.281590 -0.4 16 I9GS4-41 0.31978 0.281527 0.000032 -44 0.70 0.004 0.009 0.00070 0.281504 2.01 2.37 0.281672 -6.0 12 I9GS4-45 0.33865 0.281674 0.000044 -38 0.75 0.006 0.014 0.00104 0.281639 1.80 2.18 0.281670 -1.1 17 I9GS4-53 0.29846 0.281412 0.000039 -48 0.84 0.002 0.005 0.00036 0.281400 2.17 2.50 0.281679 -9.9 6 I9GS4-58 0.29869 0.281646 0.000024 -39 0.73 0.002 0.004 0.00033 0.281635 1.80 2.18 0.281655 -0.7 6 I9GS4-71 0.32271 0.281499 0.000024 -45 0.97 0.005 0.013 0.00071 0.281475 2.06 2.40 0.281654 -6.4 13 I9GS4-86 0.32118 0.28134 0.000027 -50 0.98 0.005 0.013 0.00071 0.281315 2.31 2.62 0.281585 -9.6 12 I9GS4-95 0.32074 0.281487 0.000027 -45 0.80 0.004 0.011 0.00071 0.281463 2.08 2.42 0.281647 -6.5 12 I9GS5_3 0.32832 0.281627 0.000027 -40 3.63 0.027 0.049 0.00119 0.281589 1.88 2.26 0.281721 -4.7 14 I9GS5_13 0.36518 0.281564 0.000023 -42 4.64 0.053 0.117 0.00176 0.281506 2.02 2.38 0.281686 -6.4 23 I9GS5_15 0.33977 0.28147 0.000014 -46 4.74 0.040 0.088 0.00116 0.281432 2.13 2.47 0.281677 -8.7 17 I9GS5_20 0.32004 0.281449 0.000014 -46 3.46 0.022 0.047 0.00080 0.281421 2.14 2.48 0.281619 -7.0 12 I9GS5_31 0.47335 0.281955 0.000018 -28 2.60 0.093 0.158 0.00482 0.281784 1.52 1.99 0.281598 6.6 40 I9GS5_32 0.29754 0.2815 0.0000079 -45 4.22 0.012 0.023 0.00035 0.281488 2.03 2.38 0.281625 -4.9 5 I9GS5_40 0.30088 0.281334 0.000013 -50 3.73 0.011 0.023 0.00038 0.281321 2.30 2.61 0.281607 -10.2 6 I9GS5_41 0.35325 0.28155 0.000014 -43 4.55 0.049 0.113 0.00143 0.281501 2.02 2.38 0.281628 -4.5 20 I9GS5_42 0.35924 0.281525 0.000015 -44 3.86 0.047 0.097 0.00154 0.281520 2.07 2.42 0.282655 -40.2 22 I9GS5_43 0.35862 0.281355 0.000022 -50 4.07 0.045 0.090 0.00173 0.281298 2.36 2.67 0.281687 -13.8 22 I9GS5_44 0.31620 0.281655 0.000022 -39 4.76 0.024 0.052 0.00068 0.281631 1.81 2.19 0.281618 0.5 11 I9GS5_45 0.30918 0.281508 0.00002 -44 4.56 0.017 0.040 0.00056 0.281489 2.04 2.38 0.281642 -5.4 9 I9GS5_46 0.30298 0.281695 0.000028 -38 4.82 0.021 0.031 0.00066 0.281673 1.74 2.13 0.281651 0.8 7 I9GS5_47 0.33023 0.281505 0.000015 -44 4.41 0.031 0.068 0.00095 0.281473 2.06 2.41 0.281647 -6.2 15 I9GS5_48 0.28527 0.281488 0.000011 -45 4.39 0.002 0.005 0.00007 0.281486 2.04 2.38 0.281633 -5.2 1 I9GS5_50 0.30419 0.281611 0.000013 -41 3.69 0.012 0.027 0.00041 0.281597 1.86 2.23 0.281615 -0.6 7 I9GS6-4 0.29932 0.281593 0.000021 -41 1.10 0.003 0.006 0.00033 0.281582 1.89 2.25 0.281695 -4.0 6 I9GS6-7 0.34183 0.281674 0.00003 -38 0.98 0.008 0.020 0.00108 0.281636 1.80 2.19 0.281596 1.4 18 I9GS6-9 0.36075 0.28161 0.000034 -41 1.02 0.010 0.027 0.00133 0.281567 1.92 2.29 0.281702 -4.8 22 I9GS6-23 0.29899 0.28155 0.000021 -43 1.17 0.003 0.007 0.00031 0.281539 1.95 2.31 0.281587 -1.7 6 I9GS6-34 0.28899 0.281541 0.000015 -43 1.25 0.002 0.003 0.00016 0.281536 1.96 2.31 0.281627 -3.3 3 I9GS6-39 0.32450 0.281581 0.000024 -42 1.40 0.008 0.020 0.00074 0.281557 1.93 2.29 0.281680 -4.4 13 G113_27 0.29659 0.281573 0.00002 -42 4.24 0.008 0.019 0.00027 0.281564 1.92 2.28 0.281698 -4.7 5

62

Table 3-3. Continued

Sample #

176Hf/ 177Hf

uncorr. 176Hf/177Hf

corr. error (+/-) εHf Hf (V) 175Lu (V) 172Yb (V)

176Lu/ 177Hf

measured and mass

biased corrected

176Hf/ 177Hf initial

Model Age (CHUR) By

Model Age (DM) By

176/ 177Hf

(CHUR) T

εHf(t) % corr

G113_52 0.32599 0.281548 0.000014 -43 4.41 0.029 0.059 0.00089 0.281518 1.99 2.35 0.281633 -4.1 14 G113_71 0.36007 0.281504 0.000015 -44 4.12 0.048 0.104 0.00161 0.281451 2.11 2.46 0.281685 -8.3 22 2011GS19-1 0.33863 0.281428 0.000013 -47 3.55 0.030 0.065 0.00115 0.281391 2.20 2.53 0.281698 -10.9 17 2011GS19-25 0.32922 0.281546 0.000015 -43 4.90 0.034 0.072 0.00096 0.281514 2.00 2.36 0.281660 -5.2 14 2011GS19-47 0.30953 0.281503 0.000015 -44 4.88 0.021 0.044 0.00059 0.281484 2.04 2.39 0.281678 -6.9 9 2011GS19-63 0.32975 0.281616 0.000011 -40 4.00 0.030 0.061 0.00105 0.281579 1.89 2.26 0.281608 -1.0 15 2011GS19-78 0.36158 0.281725 0.000011 -37 3.12 0.041 0.078 0.00182 0.281663 1.76 2.16 0.281636 0.9 22 2011GS19-120 0.29616 0.281486 0.000021 -45 5.43 0.010 0.023 0.00026 0.281477 2.05 2.39 0.281639 -5.7 5 2011GS19-130 0.29831 0.281497 0.000013 -45 3.96 0.012 0.021 0.00039 0.281484 2.04 2.39 0.281647 -5.8 6 2011GS19-133 0.33519 0.281473 0.0000084 -45 4.07 0.033 0.070 0.00109 0.281437 2.12 2.46 0.281677 -8.5 16 2011GS19-142 0.43165 0.281538 0.000013 -43 5.07 0.113 0.235 0.00314 0.281425 2.15 2.51 0.281579 -5.5 35 2011GS19-175 0.31603 0.281522 0.000013 -44 4.63 0.021 0.051 0.00060 0.281501 2.02 2.37 0.281644 -5.1 11 I9GS14-3 0.32745 0.281554 0.000023 -43 3.76 0.026 0.054 0.00096 0.281522 1.99 2.34 0.281648 -4.5 14 I9GS14-26 0.34580 0.281571 0.000026 -42 2.93 0.030 0.059 0.00144 0.281522 1.99 2.35 0.281644 -4.3 19 I9GS14-43 0.31279 0.281431 0.000019 -47 4.13 0.021 0.041 0.00067 0.281408 2.16 2.49 0.281632 -7.9 10 I9GS14-52 0.32965 0.281596 0.000017 -41 3.97 0.029 0.063 0.00099 0.281563 1.92 2.29 0.281654 -3.2 15 I9GS14-56 0.32854 0.281415 0.000016 -48 3.68 0.027 0.055 0.00099 0.281382 2.21 2.54 0.281679 -10.5 14 I9GS14-77 0.31078 0.28155 0.000017 -43 3.37 0.015 0.033 0.00061 0.281529 1.97 2.33 0.281645 -4.1 9 I9GS14-78 0.33528 0.281558 0.00001 -42 4.13 0.034 0.073 0.00110 0.281521 1.99 2.35 0.281654 -4.7 16 I9GS16-22 0.33006 0.281417 0.000041 -47 0.66 0.004 0.011 0.00084 0.281400 2.20 2.52 0.281600 -7.1 15 I9GS16-36 0.32041 0.28172 0.000025 -37 0.82 0.005 0.011 0.00085 0.281703 1.71 2.11 0.281652 1.8 12 I9GS17_58 0.30323 0.28139 0.000036 -48 0.82 0.003 0.006 0.00044 0.281375 2.21 2.53 0.281613 -8.5 7 I9GS20_11 0.30111 0.281504 0.000031 -44 0.95 0.003 0.006 0.00052 0.281486 2.04 2.39 0.281596 -3.9 7 I9GS20_23 0.30801 0.281755 0.000019 -36 1.11 0.005 0.009 0.00069 0.281732 1.65 2.05 0.281674 2.0 9 I9GS20_27 0.32498 0.281591 0.000021 -41 1.49 0.014 0.021 0.00134 0.281545 1.95 2.32 0.281638 -3.3 13 I9GS20_32 0.34412 0.281449 0.000025 -46 1.95 0.022 0.039 0.00159 0.281393 2.20 2.53 0.281595 -7.2 18 I9GS20_39 0.29826 0.281598 0.000023 -41 1.30 0.004 0.007 0.00043 0.281584 1.89 2.25 0.281667 -3.0 6 I9GS20_62 0.31998 0.281514 0.000021 -44 1.55 0.008 0.019 0.00073 0.281490 2.04 2.39 0.281685 -6.9 12 I9GS20_64 0.36568 0.281554 0.000016 -43 1.93 0.021 0.053 0.00146 0.281503 2.02 2.38 0.281613 -3.9 23 I9GS20_73 0.33996 0.281553 0.000016 -43 1.76 0.014 0.033 0.00113 0.281513 2.00 2.36 0.281601 -3.1 17 I9GS20_79 0.30426 0.281606 0.000023 -41 1.53 0.005 0.011 0.00041 0.281592 1.87 2.24 0.281597 -0.2 7 I9GS20_81 0.37605 0.281728 0.000016 -36 1.29 0.018 0.041 0.00184 0.281665 1.75 2.16 0.281645 0.7 25 I9GS23-33 0.31512 0.281607 0.000083 -41 2.30 0.016 0.025 0.00093 0.281576 1.90 2.27 0.281664 -3.1 11 I9GS23-58 0.34455 0.281555 0.000017 -43 4.35 0.047 0.089 0.00139 0.281509 2.01 2.37 0.281662 -5.5 18 I9GS23-5 0.34206 0.28156 0.000025 -42 4.09 0.036 0.079 0.00119 0.281520 1.99 2.35 0.281655 -4.8 18 I9GS23-27 0.34131 0.281461 0.00003 -46 3.38 0.040 0.064 0.00162 0.281404 2.18 2.52 0.281600 -7.0 18 I9GS24-92 0.32313 0.281651 0.000023 -39 1.01 0.006 0.014 0.00080 0.281624 1.82 2.20 0.281658 -1.2 13 I9GS24-94 0.32603 0.281617 0.000028 -40 1.03 0.007 0.016 0.00088 0.281600 1.88 2.25 0.281662 -2.2 14 I9GS24-104 0.31677 0.281606 0.000025 -41 0.81 0.004 0.010 0.00064 0.281593 1.88 2.25 0.281659 -2.4 11

63

Table 3-3. Continued

Sample #

176Hf/ 177Hf

uncorr. 176Hf/177Hf

corr. error (+/-) εHf Hf (V) 175Lu (V) 172Yb (V)

176Lu/ 177Hf

measured and mass

biased corrected

176Hf/ 177Hf initial

Model Age (CHUR) By

Model Age (DM) By

176/ 177Hf

(CHUR) T

εHf(t) % corr

I9GS24-116 0.34976 0.28161 0.000026 -41 1.13 0.010 0.024 0.00127 0.281610 1.91 2.29 0.281663 -1.9 19 I9GS24-6 0.32039 0.281534 0.000032 -43 0.63 0.004 0.008 0.00078 0.281508 2.01 2.36 0.281653 -5.2 12 I9GS24-7 0.35807 0.281691 0.000049 -38 0.75 0.006 0.019 0.00142 0.281662 1.79 2.18 0.281644 0.6 21 I9GS24-10 0.30978 0.281543 0.000029 -43 1.04 0.004 0.009 0.00058 0.281543 1.98 2.34 0.281659 -4.1 9 I9GS24-14 0.32114 0.281604 0.000028 -41 1.03 0.006 0.013 0.00075 0.281604 1.89 2.26 0.281653 -1.8 12 I9GS24-15 0.32243 0.281766 0.000045 -35 0.93 0.005 0.012 0.00081 0.281749 1.64 2.05 0.281656 3.3 13 I9GS24-16 0.33389 0.281541 0.000035 -43 0.97 0.007 0.017 0.00101 0.281507 2.01 2.37 0.281654 -5.2 16 I9GS24-33 0.31397 0.281834 0.000036 -33 1.45 0.007 0.015 0.00061 0.281823 1.52 1.94 0.281699 4.4 10 I9GS24-59 0.33679 0.281682 0.000024 -38 1.16 0.009 0.021 0.00105 0.281660 1.79 2.17 0.281654 0.2 16 I9GS24-68 0.33991 0.281527 0.000038 -44 1.75 0.012 0.032 0.00097 0.281488 2.03 2.38 0.281650 -5.7 17 I9GS24-69 0.45806 0.281548 0.000031 -43 1.01 0.021 0.057 0.00295 0.281484 2.12 2.48 0.281654 -6.1 39 I9GS24-76 0.30231 0.281388 0.000025 -48 1.18 0.004 0.008 0.00039 0.281380 2.21 2.53 0.281592 -7.5 7

64

Figure 3-1. Detrital zircon probability plots for the select samples from the Son Valley

(Kaimur, Rewa/Kaimur, Rewa and Bhander Sandstone) Sector and Rajasthan (Bhander Great Boundary Fault Sandstone and Bundi Bhander Sandstone) Sector Upper Vindhyan units. Comparisons between this figure and figure 6 show that Marwar and upper Vindhyan samples can no longer be correlated, strengthening the arguments by Malone et al. (2008) and McKenzie et al. (2011).

65

Figure 3-2. Detrital Zircon probability plots for select samples from the Marwar

Supergroup. Note the appearance of <1000 Ma zircons in these plots compared to upper Vindhyan plots that contain no zircons <1000 Ma

66

Figure 3-3. εHf(t) vs U-Pb age data for ~1.7-1.8 Ga detrital zircons from both the Marwar and upper Vindhyan sediments.

The majority of samples contain negative εHf(t) values corresponding an affinity with ancient crustal material. These zircons also correlate well samples from the Aravalli Mountain Range seen in the study by Kaur et al. (2012), represented by the red shaded cloud. This suggests that ~1.7-1.8 Ga detrital zircons found in both the Marwar and Upper Vindhyan sediments may owe their source to the Aravalli region.

67

CHAPTER 4 DISCUSSION

Marwar and Vindhyan Correlations

Figure 4- 1 shows a complete compilation of detrital zircon data from the Marwar

and Vindhyan basins based on new data reported herein along with data from Malone

et al. (2008) and McKenzie et al. (2011). Data from these three studies are striking in

that there is a complete absence of detrital zircons <1000 Ma throughout upper

Vindhyan sediments in contrast to the Marwar Supergroup that contains abundant

detrital zircons in the 700-900 Ma range.

The difference in the zircon populations between the two basins can have

multiple causes. The two basins may have evolved contemporaneously, but have

different source regions or were separated by a physiographic barrier such as the Great

Boundary Fault (Figure 1- 2). The basins may have evolved at different times as

reflected in the contrasting populations of detrital zircons. Below we lay out our case for

the latter explanation based on several important considerations.

The age of the Marwar basin is certainly younger than the underlying Malani

Igneous Province (<750 Ma; Gregory et al., 2008; Figure 1- 4). We note the lack of

glacially-derived sediments within the Marwar as indicating a post Marinoan age (<650

Ma). Fossil evidence points to an Ediacaran-age for the Jodphur Group (lowermost

Marwar) based on the presence of Arumberia, Beltanelliformis, Aspidella, and

Hiemalora (Kumar and Pandey 2009; Kumar et al. 2009). Pandit et al. (2001) argue

that the Ediacaran-Cambrian boundary should be placed near the upper part of the

Bilara Group (Pondlo dolomite; Figure 1- 4) on the basis of δ13C profiles within the

sequence. Srivastava et al. (2012) discovered priapulid-like fossils in the Nagaur

68

sandstone that, along with the earlier finds of Rusophycus, Dimophichnus, and

Cruziana (Kumar and Pandey, 2008, 2010), support the placement of the Ediacaran-

Cambrian boundary (541 Ma) near the base of the Nagaur sandstone. Stratigraphic

comparisons between Oman (Huqf Supergroup), Pakistan (Salt Range), Lesser

Himalayas (Krol-Tal) indicate that deposition in the Marwar can be reliably constrained

to between 570-521 Ma (Ediacaran-Terreneuvian; Figure 1- 4).

This age estimate for the Marwar Supergroup is supported by the detrital zircon

age distributions in our compilation. The youngest zircon in the population yielded an

age of 536 ± 15 Ma consistent with the above-cited range (Figure 4- 1; Table 3.2).

In contrast, our age determination for Upper Vindhyan sedimentation is based on

the following arguments. The most important age constraint for Upper Vindhyan

sedimentation is derived from the 1073 Ma age of the Majhgawan kimberlite (Gregory et

al., 2006) and the age of the underlying Rhotas shale in the Lower Vindhyan sequence.

Since the kimberlite intrudes the Kaimur Group, the onset of Vindhyan sedimentation

occurred between ~1600 Ma and 1073 Ma.

We also note that our compilation of detrital zircon ages confirms the lack of ages

<1000 Ma within the Upper Vindhyan sequence. The lack of younger detritus into the

Upper Vindhyan is consistent with a Mesoproterozoic age for the basin, but it can also

be explained by the presence of physiographic barriers or lack of local younger source

material. If the Marwar and Vindhyan basins evolved contemporaneously, then we can

reject the argument that there was no source region for <1000 Ma zircons because of

the proximity of both basins to the granite-rhyolite Malani province. Sedimentary strata

in both the Marwar Supergroup and Upper Vindhyan sequence were formed at or near

69

sea-level. Therefore it is likely that reworking of zircons along a common coastline

would supply younger detritus into the Upper Vindhyan sediments (Cawood et al. 2012).

A second possibility is that the Marwar and Vindhyan basins were separated by a

significant physical barrier that isolated the two regions. The most logical barrier to

deposition in the region is the Great Boundary Fault (GBF). We note that the Bhander

Group is deformed along the GBF and therefore it seems unlikely that the GBF formed

a significant impediment to input from the west during the time span of Bhander

deposition (see figure 1- 2). Our Hf data indicates that both the Marwar and Vindhyan

Supergoup received input from a region with significant crustal material in the 1.7-1.8

Ga range. The Aravalli Belt appears to be the most likely source region and it may be

that the Aravalli range acted as both a barrier and a source for sedimentation.

The strongest case for a significant age difference between the Marwar and

Vindhyan basins is based on paleomagnetic arguments. Gregory et al. (2006) first

noted the directional similarity between the 1073 Ma Majhgawan kimberlite virtual

geomagnetic pole (VGP) and previously published results from the Bhander-Rewa

Groups (McElhinney et al., 1978; Klootwijk, 1973, 1975). Malone et al. (2008)

conducted a comprehensive study of the Upper Vindhyan and confirmed the

paleomagnetic similarities. More recently, Pradhan et al. (2012) showed that

paleomagnetic data from the Great Dyke of Mahoba (1090 Ma) is also statistically

identical to the Majhgawan kimberlite and Bhander-Rewa (Figure 4- 2). The available

paleomagnetic data are consistent with a Mesoproterozoic age of deposition for the

Bhander-Rewa Groups.

70

Three new paleomagnetic results provide further support for a Mesoproterozoic

age. Venkateshwarlu and Chalapathi-Rao (in press) studied kimberlite and lamproite

intrusions in the Dharwar craton. These intrusions have a variety of U-Pb perovskite

ages that cluster tightly around 1.1 Ga. The paleomagnetic directions match the

aforementioned poles from the Majhgawan kimberlite, Great Dyke of Mahoba and

Bhander-Rewa (Figure 4- 2). Meert (personal communication) also notes similar

paleomagnetic directions from a limited sampling of the 1.0 Ga Sukhda tuff

(Chhattisgarh basin; Figure 4- 2). Finally, Davis (2012) showed that paleomagnetic

directions from the Marwar Supergroup are significantly different from the Upper

Vindhyan directions (Figure 4- 2).

In summary, we feel the most parsimonious explanation for the distinct detrital

zircon populations in the Upper Vindhyan and Marwar sequences is that the basins

evolved independently. The Upper Vindhyan basin closed around 1000 Ma as

collisional events in the Eastern Ghats, CITZ and Delhi belts disrupted sedimentation.

The Marwar basin formed during the final stages of Gondwana assembly during the

Ediacaran-Cambrian interval (~570-521 Ma). The Marwar is one of several Ediacaran-

age basins within eastern Gondwana that included the Krol-Tal (Lesser Himalayas), Salt

Range (Pakistan) and the Huqf Supergroup (Oman; Figure 1- 4) and perhaps the Molo

Group (Madagascar).

It should be noted that our conclusion regarding the age of the Upper Vindhyan is

consistent with recent age determinations on two other ‘Purana’ basins, the Indravati

Basin (Mukherjee et al. 2012) and the Chhattisgarh Basin (Bickford et al. 2011;

Patranabis-Deb et al., 2007). Depositional age constraints in the Chhattisgarh basin

71

suggest closure at ~1000 Ma (age of the Sukhda tuff at the top of the sedimentary

sequence; Patranabis-Deb et al., 2007). A basal tuff in the Chhattisgarh yielded an age

of 1405 Ma (Bickford et al. 2011). Coincidentally, the Indravati Basin contains a tuff unit

located at the top of the sedimentary succession that yields a weighted-mean average

207Pb/206Pb age of 1001 ± 7 Ma (Mukherjee et al. 2012). The corresponding ~1000 Ma

closure ages for the Vindhyan, Chhattisgarh, and Indravati basins are thought to be

controlled by the collision of East Antarctica and India, producing the Eastern Ghats

Mobile Belt (EGMB) of eastern India. This interval of time was likely accompanied by

uplift that could create barriers to any marine influx into the Purana Basins. Our

hypothesis is consistent with the existence of orogenic pulses in the Delhi Belt (to the

west of the Vindhyan Basin) and in the Eastern Ghats (to the east) at around the same

time (Lescuyer et al. 1993; Sivaraman and Raval 1995; Biju—Sekhar et al. 2003; Kaur

et al. 2006; Kaur et al. 2007; Pandit et al. 2003).

Provenance of Detrital Zircons from the Marwar and Vindhyan Basins

Detrital zircon has been proven to be a powerful tool in understanding ancient

aeolian processes, paleodrainage patterns, terrane discrimination, and

palaeogeographical reconstructions (Hieptas et al. 2011 and sources therein). Despite

numerous successes, many detrital zircon studies fail to identify all source terranes for

the sediments under investigation. As an example, studies of detrital zircons derived

from Paleozoic clastic sequences in the Appalachian orogen failed to fully record the

defining tectonic events of the orogeny (Gray and Zeitler 1997; McLennan et al. 2001;

Eriksson et al. 2004; Thomas et al. 2004; Becker et al. 2005). Provenance

determinations for detrital zircon populations in the Upper Vindhyan region are hindered

by the fact that paleocurrent data from the Vindhyan basin are poorly constrained

72

(Akhtar and Srivastava 1976; Kaur et al. in press; Singh 1984). Previous studies on

Upper Vindhyan sediments suggested that sedimentation sources are located to the

present-day south of the Vindhyan Basin. Akhtar (1996) argued that paleocurrent data

from the Rewa and Bhander Groups is dominated by a unimodal westerly to

northwesterly direction. The Dhandraul Sandstone in the Son Valley sector of the basin

indicates west and northwest-sloping paleoslopes (Akhtar 1996). Interpretations based

on paleocurrent indicators, trends of thickness variation within lithostratigraphic units,

and regional stratigraphic relationships for the marine Rewa basin rocks (Jhiri Shale,

Drammondganj Sandstone, Govindarh Sandstone) in the Son Valley sector provide for

a northwest-southeast oriented paleoshoreline and northeast-sloping paleoslope. In

contrast, analyses of coastal environments for the Bhander Group suggest multi-

directional sediment dispersal (Akhtar 1973, 1975, 1976, 1978; Akhtar and Srivastava

1976). Detrital input (including zircons) is also reported to be from the southern parts of

the Aravalli mountain range and the Bundelkhand massif, suggesting a southerly and

westerly trending paleocurrents (Singh 1984; Malone et al., 2008). Therefore, it must

be noted that the expression of tectonic activity that would play a role in the provenance

of detritus will be dependent on the paleocurrent(s) that transported sediment into these

basins and not all tectonic activity may be recorded in the sedimentary record of the

Vindhyan or Marwar basins. Our complete survey of the entire upper Vindhyan

succession from the Rajasthan and Son Valley sectors (Figure 1- 2); key sandstones

from the bottom to top of the Marwar Supergroup (Figure 1- 4) along with the extensive

compilation of detrital zircon ages (Figure 4- 1) from this study, Malone et al. (2008) and

73

McKenzie et al. (2011) should, however provide some clarity on potential source

regions.

We have compiled data from this study with that of previous research from

Malone et al. (2008) and McKenzie et al. (2011) to provide a comprehensive survey of

detrital zircons from the Marwar and Vindhyan basins (Figure 4-1). These studies, while

showing variable differences in the abundance of certain detrital zircon age populations,

demonstrate very consistent results with that of our own, matching significant

populations found in each study. Given the caveats noted previously regarding

provenance, there are nearby sources that can be identified as potential source regions

for our detrital populations.

Vindhyan Provenance

The results of this study show that upper Vindhyan sediments contain a variety of

different age populations, with common age groups seen throughout the complete

stratigraphy (Kaimur, Rewa, and Bhander). These common populations occur at ~1 Ga,

~1.1 Ga, ~1.5 Ga, ~1.6 Ga, ~1.7 Ga, and ~1.8 Ga (Figure 5 and 9). These ages can be

interpreted in three ways: 1) as a mix of sources that contributed to these formations,

with changing paleocurrents contributing to the deposition of a single formation, or 2)

that reworking of underlying rocks produced similar age populations in all three (i,e, the

Kaimur was reworked and contributed to the Rewa sediments and the Rewa was

reworked to produce similar ages in the Bhander), or 3) a combination of interpretation

1) and 2).

This paper prefers interpretation 3) due to the vast array of age populations seen

in results from Kaimur detrital zircon analyses. Results from McKenzie et al. (2011) and

our own show zircons populations with ages of ~1.0 Ga, ~1.1 Ga, ~1.2 Ga, ~1.5 Ga,

74

~1.6 Ga, ~1.7 Ga and ~1.8 Ga (Figure 4-1). It is difficult to attribute this spread of ages

to a single source, so we discuss multiple provenance locations for the detrital zircons

found in Upper Vindhyan sediments.

Many age populations from our Vindhyan units may be tied to the Central Indian

Tectonic Zone (CITZ; Figure 1- 2) located to the south. Roy and Chakaraborti (2008)

report ages for zircon bearing units in the CITZ. The age ranges in that study fall in

broadly defined groups ranging from ~800-1000 Ma; 1100-1200 Ma; 1400-1600 Ma;

and 1700-1800 Ma. With the exception of the younger (<1000 Ma) ages, most of these

pubished ages fall within error of our compiled detrital zircon database from the Upper

Vindhyan sediments. It is important to note that many of the ages summarized by Roy

and Chakraborti (2008) are Rb-Sr isotopic determinations that are not as reliable as

determined by the U-Pb system in zircon. However, more reliable data have recently

become available that might give insight to the origin of notable age detrital zircon age

populations of ~1.0 Ga, ~1.2 Ga, ~1.5 Ga, and ~1.6 Ga, and smaller populations of

ages such as ~1.3 and ~1.9 Ga, all attributed to Upper Vindhyan sediments. U-Pb

zircon and monazite chemical dating of two granite gneiss samples from the southern

domain of the Sausar Mobile Belt (SMB) broadly constrain magmatic crystallization

between 1603 ± 23 Ma and 1584 ± 17 Ma and an overprinting metamorphic event at

1572 ± 7 Ma (Bhowmik et al. 2011). Later, Bhowmik et al. (2012) suggested a

collisional event in the northern and central region of the SMB between 1.06 Ga and

0.94 Ga, that is purported to represent the final amalgamation of the North and South

Indian blocks. Bhowmik et al. (2012) also suggest that, when combined with data from

other collisional belts further east of the CITZ, such as the Chhotanagpur Gneissic

75

Complex and the Shillong Plateau Gneissic Complex, a commonality of

Mesoproterozoic to Early Neoproterozoic events is evident. Zircons from a metapelite

enclave in the Chottanagpur Gneiss Complex (CGC), yielded mostly concordant

207Pb/206Pb spot ages of 1009 ± 24 Ma, 1270 ± 19 Ma, 1333 ± 27 Ma, 1435 ± 27 Ma,

1649 ± 13 Ma, 1925 ± 110 Ma, and 2569 ± 108 Ma (Rekha et al. 2011). Ages of ~1.3-

1.2 Ga were reported by Chatterjee et al. (2010a) and Chatterjee et al. (2010b) from

monzanite rims in schists from the southern portion of the North Singbhum Mobile Belt

(an eastern extremity of the CITZ; figure 1- 2). If these findings prove robust then it must

be noted that there is limited understanding of whether the process that created the

CITZ, the subduction of the Bastar Craton under the Bundelkhand craton (or vice

versa), would have produced enough uplift and exhumation to provide detrital zircon

input from a crystalline core source to Mesoproterozoic basins from around the region

by ~1 Ga (Bickford et al. 2011). Given this stipulation, it is also possible that ~1.6 Ga

zircons were derived from reworking the underlying Deonar Porcellanites and Rampur

shale from that ages of 1628 ± 8 Ma; 1602 ± 10 Ma and 1593 ± 12 Ma were reported

(Rasmussen et al 2002; Ray et al. 2006).

The Aravalli Mountain region (Figure 1- 2) may be the source for some of the

detrital zircon populations in the Upper Vindhyan sequence. The Aravallis experienced

magmatic and metamorphic events at ~1.7-1.72 Ga (Kaur et al., 2011).

Paleoproterozoic quartzites in the Aravalli region (Khetri Complex) contain an

abundance of ~1.8 Ga zircons and there are numerous 1.85 Ga subduction-related

granitoids. Therefore either reworking of the quartzites or erosion of the granitoids

might be the source of the 1.7-1.8 Ga zircons in the Upper Vindhyan sequence. This

76

seems more likely given the close correlation between the εHf data from Vindhyan rocks

and εHf data from ~1.85 subduction related granitoids and Paleoproterozoic quartzites

from around the same region (Kaur et al., 2011; Figure 3- 3).

It is more problematic to isolate a single source for the 1.0-1.1 Ga populations

that are dominant in the Upper Vindhyan sequence. This interval of time is believed to

be a period of supercontinental assembly and zircons of 1.1-1.0 Ga are found in detrital

zircon populations around the globe (see Hawkesworth et al. 2010; Figure 4- 6). There

are several potential source regions that are close to the Vindhyan basin. Bose et al.

(2011) show that the Eastern Ghats Mobile Belt records episodes of tectonothermal

activity spanning a large time interval, from the Paleoproterozoic (monazite dated to

~1760 Ma);– Mesoproterozoic (zircon and monazites dated to ~1.6-1.0 Ga); Cambrian

(550-500 Ma granulites locally overprinted by amphibolite-facies metamorphism during

this time; Mezger and Cosca 1999). Paleo and Mesoproterozoic zircon populations

matching those cited above are present in the upper Vindhyan. Bickford et al. (2011)

noted that geochronologic/geothermometric/geobarometric studies of EGMB rocks

indicate that collision in the EGMB was ongoing at 1.1 Ga and may be related to the

formation of the Rodinia supercontinent

Bhowmik et al. (2010) suggested that the pre-1.0 Ga Indian landmass consisted

of at least three micro-continental blocks, the North Indian block, the South Indian Block

and the Marwar block, that underwent amalgamation at ~1.0 Ga. Peak and retrograde

stages of metamorphism are recorded in garnet-staurolite-kyanite schist and garnet-

biotite-muscovite-quartz schist from the central domain of the Sausar Mobile Belt as

1062 ± 13 Ma and 993 ± 19 Ma monazite ages (Bhowmik et al. 2012). The

77

Aravalli/Delhi region is also characterized by granitic intrusions with ages of ~1.0 -1.1

Ga (Pandit et al. (2003); Biju-Sekhar et al. 2003; Buick et al. 2006; Just et al. 2011).

Ages of ~1.1 – 0.9 have been obtained from rims of some zircons from granitoid plutons

occurring in the northern part of the Delhi Fold Belt (Biju-Sekhar et al. 2003). Other

granitic rocks from the Aravalli region have been dated to ~1.0-0.9 Ga (Lescuyer et al.

1993; Sivaraman and Raval 1995; Biju—Sekhar et al. 2003; Kaur et al. 2006; Kaur et al.

2007; Pandit et al. 2003).

While we cannot provide a definitive source for the 1.1-1.0 Ga population of

zircon in the Upper Vindhyan sediments, we note the following:

1. 1.1-1.0 Ga zircons form a very small population within the Marwar Supergroup in comparison to the Upper Vindhyan.

2. Point #1 may indicate that the most logical nearby source region for the 1.1-1. Ga zircons is either the CITZ or the EGMB.

3. The presence of 1.1-1.0 Ga zircons may indicate a slightly younger age for basinal closure given that uplift and erosion of source rocks within those regions would not be instantaneous.

4. Future work might focus on Hf isotopes or other isotopic information from the Vindhyan Supergroup in comparison to potential source rocks in the CITZ and EGMB

Marwar Provenance

Our Hf isotopic data shows that the ~1.7-1.8 Ga zircons from Marwar sediments

have strikingly similar εHf values to those in the Aravalli region (see Kaur et al., 2012

and Figure 3- 3). We suggest that the ~1.8 Ga zircons in the Marwar sediments are

derived from either reworked quartzites of the Aravalli orogen that contain significant

abundances of ~1.8 grains, or from ~1.85 Ga subduction-related granitoids also found

in the Aravalli region.

78

A local source also provides a reasonable explanation for the 700-900 Ma

populations in the Marwar sequence. There are abundant sources nearby including the

Malani Igneous Province (750-800 Ma; Torsvik et al., 2001b, Gregory et al. 2008;

Pradhan et al., 2010; van Lente et al., 2009) along with the Erinpura granites and

related felsic intrusions (800-900 Ma; Crawford 1975; Choudhary et al. 1984; Just et al.

2011). If our arguments are correct about the age of the Marwar sequence, then ‘local’

sources might also include the Arabian-Nubian shield and the East African Orogen

region (Figure 4- 4 and 4.5) where there are numerous arc-related source regions with

ages from 700-900 Ma (Mercolli et al. 2006; Bowring et al. 2007 and sources therein).

Because we suggest that detritus for the majority of age populations in Marwar

sediments correspond to the Aravalli/Delhi region, we can also propose that older

zircons (~2.5 Ga) are most likely deriveded from the basement rocks of this area. An

ion microprobe zircon study of granitoid and gneissic basement rocks of the Aravalli

Mountains yielded crystallization ages of ~2.5 Ga (Wiedenbeck et al. 1996).

Paleogeographic Implications

Links between Continental Landmasses from Detrital Zircon Records

We compare data from our study and similar studies using detrital zircon records

to constrain source rock and crustal growth episodes to make connections between the

Marwar and Upper Vindhyan sediments and those of proposed cratonic units involved in

the assembly of the supercontinents Rodinia, and Gondwana (Figures 4.2 and 4.3).

Rodinia and Gondwana

Debate has surrounded the configuration of specific cratons (the Rayner and

Mawson cratonic blocks, Australia, Madagascar, the Seychelles, Sri Lanka and India)

involved in the Mesoproterozoic supercontinent of Rodinia, as well as their successive

79

amalgamation in the supercontinent Gondwana following the Neoproterozoic breakup of

Rodinia (Figure 4- 4; Meert and Van der Voo 1996; Rogers et al., 1995; Weil et al. 1998;

Powell and Pisarevsky 2003; Meert 2003; Meert and Torsvik 2003; Veevers 2004;

Collins and Pisarevsky 2005; Squire et al. 2006; Meert and Lieberman 2008; Malone et

al. 2008; Gregory et al. 2009). Apparent polar wander paths and supercontinent

reconstructions of specific cratonic masses involved in these reconstructions are

hindered by the lack of high quality paleomagnetic data (Meert and Powell 2001;

Malone et al. 2008). Previous hypotheses suggested that a united East Gondwana

(Figure 4- 4) persisted through the Mesoproterozoic as part of Rodinia through the

majority of the Precambrian and until the breakup of Gondwana in the Mesozoic (Powell

et al. 1993; Windley et al. 1994; Dalziel 1997; Yoshida and Upreti 2006). This argument

has been contradicted by high quality paleomagnetic data (Meert and Van der Voo,

1997; Meert, 2001; Torsvik et al. 2001; Collins and Pisarevsky 2005; Gregory et al.

2009). It is suggested that Rodinia was created by ~1 Ga, followed by the

supercontinent fragmenting into separate crustal plates, caused by extension (rifting)

during the Mid-Neoproterozoic (Unrug 1998; Li et al. 2008; Wendorff and Key 2009).

This was then followed by Mid-Neoproterozoic plate collision, with subsequent

extension followed by multiple collisions of smaller crustal plates at ~560 Ma and ~520,

beginning the formation of the Gondwana supercontinent (Figure 4- 2; Meert 2003;

Collins and Pisarevsky 2005; Bingen et al. 2009; Key et al. 2011).

Paleomagnetic data from the Indian subcontinent can be useful in evaluating

these tectonic models. One of the most recent paleomagnetic poles for this time period,

a 771 ± 5 Ma Malani Igneous Suite (MIS; Torsvik et al., 2001a; Gregory et al., 2008),

80

this pole place India at much higher latitudes than coeval poles from Australia (Mundine

dikes; Wingate and Giddings 2000), in a similar position to the Takamaka Dikes in the

Seychelles dated to 750.2 ± 2.5 by Torsvik et al. (2001b), thus negating the idea of an

amalgamated East Gondwana at 750 Ma. Magmatism of this age (~750 Ma) is also

present in Madagascar and the Seychelles (Tucker et al. 2011; Ashwal et al. 2002;

Kochhar 2008; Thomas et al. 2009) and in the Arabian-Nubian shield (Stern and

Dawoud, 1991).

In a best case scenario, we can use detrital zircon data to help determine

whether events corresponding to the amalgamation and breakup of certain

supercontinent cycles may be manifested in upper Vindhyan and Marwar sediments.

Furthermore, similarities/differences in detrital zircon spectra can be used to make a

case for and against proximity to India during specific intervals within these

supercontinent cycles (see Runcorn, 1962; Hawkesworth et al., 2009; Meert, 2012;

Figure 13). Our compilation of detrital zircon ages show input from periods representing

the formation of Rodinia, represented by zircon ages of ~1 Ga, (Vindhyan) as well as

the dispersal of Rodinia and into the amalgamation of Gondwana, seen as zircons with

ages between ~800-500 Ma (seen only in the Marwar Basin; Figures 4.1 and 4.5).

The Marwar basin retains a detrital record that includes zircon populations that

temporally correlate with the assembly and breakup of Rodinia, as well as the assembly

of Gondwana. In a reconstruction of Gondwana (figures 4.4 and 4.5), the Marwar Basin

is positioned near other Neoproterozoic basins in Oman (Huqf Supergroup), Pakistan

(Salt Range) and the Lesser Himalayas (Krol-Tal) and perhaps to the Molo Basin

81

(Madagascar). Numerous authors have noted the similarities among these basins (See

Cozzi et al., 2012; Bowring et al., 2007; figure 1-4).

Previous studies have attempted to correlate the Marwar to similar-aged basins

that would have been in close proximity to the region during Gondwana time such as

the Salt Range of Pakistan, the Ara Formation (Huqf Supergroup) of Oman, and the

Krol Tal succession of the Himalayas, all of which are Ediacaran-Cambrian in age

(Hughes et al. 2005; Jiange et al. 2002, 2003; Kaufan et al. 2006; Maithy and Kumar

2007; Mazumdar and Bhattacharya 2004; Cozzi and Rea 2006; Husseini and Husseini

1990). We suggest that these and other Ediacaran aged sediments, such as the Molo

group correlate well with the Marwar Supergroup, when detrital zircon data are

compared.

The Marwar, Salt Range, and Ara formation of Oman have already been

correlated, due to their nearly identical cycles of carbonate-evaporite deposits (Cozzi

and Rea 2006). McKenzie et al. (2011) provided an age correlation between the Marwar

and the Krol-Tal, due to nearly identical detrital zircon population variations, but while

the Krol-Tal successions contain glacial deposits (Tewari and Sial 2007), neither the

Salt Range nor the Marwar have evidence of glacial deposits. This lack of glacial

detritus is consistent with an age of <635 Ma, marking the end of the Marinoan period

(characterized by worldwide glaciations; Tewari and Sial 2007) and the beginning of the

Ediacaran period. While this might negate the age correlation presented by McKenzie

et al. (2011), the extremely similar detrital zircon age spectra that the Krol-Tal and

Marwar Basins share suggest that the two areas still shared similar provenance,

82

suggesting at least geographical proximity. The Krol-Tal may represent a slightly older

depositional time period.

The Ara Formation of the Huqf Group of Oman from the Arabian-Nubian shield

demonstrate 6-7 nearly identical cycles of carbonate-evaporite deposits (Cozzi and Rea

2006; Figure 1-4). This correlation between the Marwar and the Huqf Group is

strengthened by comparison of detrital zircon records. Notably, detrital zircons analyzed

from key stratigraphic levels of the Huqf Supergroup (basement, Abu Mahara Group,

Nafun Group, and Ara Group of Oman) in a study by Bowring et al. 2007 exhibit ages

that parallel ages in the Marwar Supergroup (~600-900 Ga, in excess of 2.5 Ga),

suggesting proximity of Archean crust during the Neoproterozoic evolution of the

eastern Arabian Peninsula. Bowring suggests that these Archean zircons may originate

from Archean crust in Yemen that ranges in age from about 2.6 to >3.0 Ga. Based on

our hypothesis that the Marwar and Oman basins were in close geographical

relationship to one another, we suggest that this ~2.5 Ga age might be indicative of

basement rock from the Aravalli region that is observed in Marwar sediments. If this is

true, then many of the younger detrital zircon ages seen in the Huqf group may

correspond to areas such as the Erinpura Granites and Malani Igneous suite.

The Ediacaran Molo group of Madagascar, deposited between 623 and 553 Ma

(Cox et al. 2004), also exhibits similar detrital zircon U-Pb spectra to the Marwar

Supergroup. The Molo group contains zircons ranging in age from ~700-1000 Ma as

does the Marwar (Cox et al. 2004). Since it is postulated that the Indian and northern

Madagascar blocks were in close proximity during Gondwana, we submit that these

83

(now metamorphosed) sedimentary rocks formed contemporaneously with the basins in

adjacent Gondwana regions (figures 4-4 & 4-5).

84

Figure 4-1. Cumulative U-Pb age Probability Density Plots for Marwar and upper

Vindhyan Detrital zircons. Red shaded area represents zircons dated to <1000 Ma. Note the absence of ages of <1000 Ma in upper Vindhyan zircons.

85

Figure 4-2. Paleomagnetic pole positions at ~1.0-1.1 Ga from Venkateshwarlu and Chalapathi-Rao (in press) kimberlite and lamporite intrusions in the Dharwar craton, Majhgawan kimberlite, Great Dyke of Mahoba, Bhander-Rewa, Meert (personal communication) paleomagnetic directions from 1.0 Ga Sukhda tuff (Chhattisgarh). Note that the Marwar Supergroup pole from Davis (2012) with paleomagnetic directions differing from Upper Vindhyan directions.

86

Figure 4-3. Geodynamic Map of the supercontinent Rodinia reconstruction from Li et al.

(2008).

87

Figure 4-4. Generalized Gondwana reconstruction depicting Neoproterozoic and

younger orogenic belts that separate the various cratons of West and East Gondwana (Malone et al. 2008; modified from Gray et al. 2007).

88

Figure 4-5. Locations of Ediacaran-Cambrian Basins in the Arabian-Nubian Shield,

Himalayas, Pakistan and Madagascar that correlate with the Marwar Basin as seen in the ‘traditional’ Gondwana reconstruction.

89

Figure 4-6. Detrital zircon spectra representing the phases of orogenesis advocated by

Runcorn (1962) from data published in Hawkesworth et al. (2009). Supercontinents represented by these populations include Columbia, Rodinia, and Pangea, and possibly Gondwana

90

CHAPTER 5 CONCLUSIONS

The Marwar and Vindhyan basins are not coeval. The Marwar basin developed

during Ediacaran-Cambrian time along with several other proximal Gondwana basins

(Oman, Madagascar, Pakistan, Lesser Himalayas and perhaps South China).

Deposition in the Upper Vindhyan basin is confined to the Mesoproterozoic along with

several other Purana basins (Chhattisgarh, Indravati).

The Marwar and Vindhyan basins do share a similar source region. This

conclusion is based on the fact that εHf(t) values for ~1.7-1.8 Ga are similar, ranging

from -13.8 to -0.2 indicative of an ancient crustal source. The Hf data are consistent

with published Hf isotopic data from the Aravalli region making it the likely source for the

1.7-1.8 Ga zircons. Other source areas for younger than ~1.7-1.8 Ga zircons may be

the CITZ, the Bundelkhand Massif, or the EGMB. The CITZ may be responsible for

ages of ~1.5-1.6 Ga or these ages may be derived from the reworking of underlying

materials from the Semri Series. The CITZ, Aravalli/Delhi and EGMB are regions are all

also characterized by younger aged events at ~1 Ga, most likely corresponding to

events stemming from the amalgamation of India with other pieces of Rodinia, or the

amalgamation of the North, South, and Marwar blocks of India. We suggest that

detritus from the EGMB is the least likely due to the fact that the CITZ is demonstrated

to have been in existence at a time before ~ 1 Ga, preventing transport of sediment

from the EGMB to the west into the Vindhyan Basin.

While a similar source region is evident, the upper Vindhyans and Marwar basin

sediments developed in completely different time periods. The upper Vindhyans should

be grouped with other late Mesoproterozoic to early Neoproterozoic sedimentary

91

sequences such as the Upper Chhattisgarh and Indravati Basins. Marwar Supergroup

deposition is now constrained between the Ediacaran and Cambrian time periods,

grouping it with basins such as the Salt Range of Pakistan, the Huqf Group of Oman,

and the Molo Group of Madagascar (Figure 4- 4). The detrital zircon record of the

Marwar basin correlates well with detrital zircon databases from these regions as well,

suggesting that these basins may have shared source regions with the Marwar. If

anything, these terranes exhibited very similar tectonic histories that would have

produced related magmatic emplacement, that in turn was recorded in the depositional

history, strongly paralleling the Marwar Basin.

92

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BIOGRAPHICAL SKETCH

Candler Coyle Turner was born in the city of Cape Canaveral, Florida, to two

loving parents, William and Mary Turner. Soon thereafter, at the tender age of three, he

and his family moved to the town of Merritt Island, FL, where he completed elementary

and middle school at Divine Mercy Catholic School, after which he graduated from

Merritt Island High in 2005, where he was voted Most Talented for his prowess in the art

that is guitar playing. Just before graduating high school, Candler was accepted to the

University of Florida. He gratefully attended the fine institution in the fall of 2005 where

he realized his passion for more than just music: Geology. Candler would go on to

complete his course work in the Geological sciences tract of the College of Liberal Arts

and Sciences, culminating in the reception of his Bachelor of Science in Geology during

the fall of 2009. The young and bold graduate then decided to stay on as a master’s

student under the advising of Dr. Joseph G Meert. The two began a hectic, but

prosperous, two and a half years of research on the Vindhyan and Marwar basins,

finally culminating in the writing and defending of the thesis that you were so fortunate

to have the overwhelming pleasure of reading.