Geology and Geochemistry of Banded Iron Formations from...

www.cafetinnova.org

Indexed in

Scopus Compendex and Geobase Elsevier, Chemical

Abstract Services-USA, Geo-Ref Information Services-USA,

List B of Scientific Journals, Poland,

Directory of Research Journals

ISSN 0974-5904, Volume 07, No. 02

April 2014, P.P.382-392

#02070204 Copyright ©2014 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.

Geology and Geochemistry of Banded Iron Formations from Joga

(Sandur Schist Belt) and associated gold mineralization

S R SURESH AND M BASAVANNA Department of Studies in Geology, Karnataka University, Dharwad-580003, Karnataka, INDIA

Email: [email protected], [email protected]

Abstract: Banded Iron Formations (BIF) is the economically prominent litho-units of the Sandur Schist Belt,

hosting high-grade iron ore deposits. Different cycles of formation of these BIF are well-known. In the Joga area,

oxide-, carbonate- and sulphide-facies of BIF are recognised. These BIF are more siliceous in nature and belong

predominantly to oxide-facies, with clusters of sulphide-facies occurring in tectonically deformed zones. Gold

content of the vein quartz associated with BIF of Joga area varies from 0.02 to 0.49 gram per ton.

Key words: Joga BIF, Sandur Schist Belt, Gold Mineralization, Boudinage structures.

Introduction:

Banded Iron Formation (BIF) is the dominant litho-

units of Archaean greenstone belts all over the world.

They are believed to be derived from marine chemical

precipitates and terrigenous derived sediments. BIFs

have been classified on the basis of their mineralogy

(James 1954; James 1966), tectonic setting (Gross,

1965) and depositional environment (Kimberley, 1978;

Simonson, 1985). James’ (1954) original facies concept

included oxide-, silicate- and carbonate-facies iron

formation, thought to correspond to different water

depths. The fourth facies, viz., the sulphide-facies,

containing pyrite and pyrrhotite was once regarded as

syngenetic in origin (Fripp, 1976), but was subsequently

suggested to be epigenetic (Phillips et al., 1984; Groves

et al., 1987), with a replacement rather than primary

sedimentary origin for sulphide mineralization. Gross

(1965) categorised two main types of iron formations

from the Precambrian, viz., Algoma and Superior. Iron

formations in India are found at different stratigraphic

levels in the greenstone succession, depending upon the

environment of deposition. They are commonly found at

the end of a megacycle of volcanism and sedimentation,

commencing with ultramafic-mafic activity.

The origin of Fe and Si that constitute the bulk of BIF

remains elusive. Some researchers claim that Fe and Si

are of terrigenous origin, having been derived from land

by weathering processes (James 1954, Lepp and

Goldich 1973, Garrels 1987 and Holland 1984). Two

types of the terrigenous origin are generally mentioned,

the first one is that these elements are carried directly

into the oceans as dissolved matter in river water

(James, 1954). The second one assumes that these

elements are leached from the suspended load of rivers

after deposition in the deeper, more reducing part of the

ocean (Holland, 1984). Other workers, however, favour

a volcanogenic hydrothermal origin for most of the

elements in BIF (Goodwin, 1973; Jacobsen and

Pimentel-Klose 1988). The hydrothermal origin, an

analogue of which are the hydrothermal systems

operating along modern mid-ocean ridges, is

particularly favoured for the Algoma type BIF, because

of their strong association with volcanic and/or

volcanoclastic rocks (Jacobsen and Pimentel-Klose,

1988).

Naqvi et al., (1988) proposed stratigraphic sequences of

greenstone belts (schist belts in the Karnataka nucleus),

occurring within five successive cycles of BIF

deposition in older and younger schist belts. In the

Dharwarcraton, deposition of BIFs has taken place at

five stratigraphic horizons in strata formed between 3.5

(?) and 2.6 Ga (Naqvi et al., 1988). The most extensive

and thick horizon is developed in a sedimentary

sequence of stable shelf environment between 3.0 and

2.8 Ga, generally known as the Bababudan Group that

forms the lower division of the types of fine grained

volcanic and terrigenous sediments. The Sandur BIFs

represent BIF3, which are found in stable shelf

association along with stromatolites.

Sandur schist belt, surrounded by Younger Granites, is

unique in the type and occurs between the Eastern and

Western Dharwar blocks (Figure1), having the litho-

assemblage affinity of the Bababudan type, but geogra-

phically located towards the eastern segment (GSI,

2006).

Sandur schist belt is also referred as transitional belt due

to its spatial position and composition of litho-

assemblages, similar to the Eastern and Western

mailto:[email protected]

mailto:[email protected]

383 S. R. SURESH AND M. BASAVANNA

International Journal of Earth Sciences and Engineering

ISSN 0974-5904, Vol. 07, No. 02, April, 2014, pp. 382-392

Dharwar Cratons (Swami Nath and Ramakrishnan,

1981). These BIFs are associated with metavolcanics,

phyllites and granites. They exhibit classical meso- and

micro-banding, and thin interbedding, with

ferrugeneous and siliceous rich bands.

Fig1: Map showing the Dharwar Craton, with Western and Eastern greenstone belts and associated lithounits, and

the Sandur Schist Belt (modified after Chadwick et al., 2000)

384 Geology and Geochemistry of Banded Iron Formations from Joga (Sandur Schist Belt)

and associated gold mineralization



Fig2: Generalised geological map of the Sandur Schist belt with gold occurrences (after Manikyamba et al., 1997)

inset red block showing study area.

1. Yeshwanthnagar volcanic block. 2. Deogiri block. 3. Western volcanic block (BIF block). 4. Central volcanic

block. 5. Greywacke in Central volcanic block. 6. Eastern volcanic (BIF) block. 7. North central acid volcanic block

(greywacke and conglomerate). 8. Sultanpura volcanic block. 9. Metasediments of eastern acid volcanic block. 10.

Acid volcanic rock. 11. Amphibolites. 12. Granitic gneiss. 13. Granite. 14. Faults. 15. Location of the areas, studied

for gold exploration.

Joga study area lies between e. longitudes of 76o 31’53”

and 76 o

36’22” and n. latitude of 15 o

10’36” and 15

o12’15”, which is located on the northern portion of

Sandur schist belt (Fig.2, inset). Joga is a small village,

which is situated 18 km away from Hospet town and is

accessible by all weather metallic roads.

Geology of the Sandur schist belt:

The Sandur schist belt lies within the Archaean Dharwar

Craton of southern India, as defined by Ramakrishnan

(1993). The belt occurs within the Late Archaean high

temperature (HT) metamorphic terrain of the Craton in

the eastern part of Karnataka. This HT terrain is

separated from the Late Archaean low temperature (LT)

terrain in the western part of Karnataka by a steep,

ductile shear zone.

Newbold (1838) took the view that the Sandur schist

belt was intruded by the adjacent granites, but in

contrast, Foote (1895) believed that granites formed its

basement. Foote (1895) interpreted the structure of the

belt in terms of two great synclines. He remarked that

the two synclines were linked by the broad spread of

volcanic rocks in the Joga- Lingadahalli- Sultanpura

area.

Krishna Rao and Hanuma Prasad (1995) interpreted the

chemical composition of fine grained clastic rocks from

the east of the schist belt in terms of mafic components

having been derived from intrabasinaltholeiitic basalts

and felsic material from an extrabasinalgranitoid source.

Geochemical data of acid and basic volcanic rocks

suggest an arc setting (Hanuma Prasad, 1994).

Oak (1990) suggested that HT/LP metamorphism of the

Sandur schist belt has been attributed to regional heating

associated with the intrusion of granites (Roy and

Biswas, 1979). Harris and Jayaram (1982) estimated

peak T of 570±50˚C and P of 2.6 -3.75 kb.

Manikyamba et al., (1997a) have proposed an eight

division classification of the Sandur schist belt, based

on the lithological characteristics, structure and




emplacement of different metavolcanic tectonic blocks

and reported a simplified geological map (Figure 2).

Age of the Sandur schist belt:

The Sandur schist belt is intruded by Younger Granite,

which is dated at 2.4 - 2.6 Ga and has yielded aRb-Sr

date of 2.4 Ga. The basic and acid volcanic suites of the

Sandur belt have yielded a thermal resetting Rb-

Srisochron age of 2.4 Ga (BhaskarRao et al., 1992). The

basic volcanics of the Kudremukh belt (stratigraphically

equated with the basic volcanics of the Sandur belt)

have yielded a Sm-Nd age of ~2.9 Ga (Drury et al.,

1983). The gneissose basement on which this belt is

resting is dated elsewhere at 3.1 Ga (Taylor et al.,

1984). In view of the available radiometric age data, the

age of the Sandur schist belt may be somewhere

between 3.1 and 2.6 Ga. Felsic volcanic from the

Sandur schist belt with U-Pb age of 2658±14 Ma was

reported by Nutman et al., (1996).

Nature of BIF in the Sandur schist belt:

Banded Iron formations of the Sandur schist belt consist

of cherts, ferruginous cherts, cherty BIF (CBIF), shaly

BIF (SBIF), ferruginous shales (FSH) and phyllites. The

BIF categories are designated, based on the variation in

the proportion of SiO2-, Fe2O3- and A12O3-bearing

minerals, as has been earlier found by Beukes (1980) for

the BIF of the Transvaal Basin. Sulfide (pyrite) and

silicate (cummingtonite/grunerite) bands are also found,

but they are not as abundant as the iron oxide bands.

Two types of banding are noticed, one in which along

with the chert, a great concentration of iron minerals is

found. In this type, the Fe and SiO2 rich layers are micro

laminated. The other type is the one in which laminated

chert and carbonates, with sporadic development of

magnetite/haematite, are found. In such cases, a gradual

change from an iron-rich layer to a chert- rich layer is

noticed with the individual thickness of the iron-rich

laminae with abrupt change to chert varies from a few

mm to 2-4 cm. The thickness of the laminae showing a

gradual decrease of iron minerals into chertlaminae are

about 5-10 mm. SBIF usually exhibit microbanding

with chert, iron mineral and shales.

Fig3: Generalised geological map of the Joga area

Field Techniques and Sampling: The study area has

been marked on the Survey of India toposheet number

57A/12 and enlarged it to A3 size scale for field

reference. Geological mapping of the area has been

carried out using a GPS (Garmin make Map 62S model

with 3 to 4 meters accuracy) and compass. All the

outcrop data like location coordinates, trends and

descriptions were recorded during the geological

traverses and processed with MapInfo software to

prepare a generalised geological map (Figure 3). In

addition to this, Google satellite image data is also used

to delineate the regional gabbroic dyke. During

geological mapping, a few fresh outcrop samples from

the representative litho units were identified and

collected from the in-situ outcrops. The representative

samples were analysed for their major element

geochemistry, using XRF/ICPMS at CESS, Trivandrum.

A few samples were also collected for preparation of

thin sections at the PPOD Lab, GSI, Bangalore, for

petrographic studies.

Geology of the Joga area:





Joga area consists of litho-units like metavolocanics,

BIFs, phyllite, coarse grained gabbro, fine to medium

grained dolerite dykes, dolomite, ankerite, aplite and

granite. Metavolcanic rocks are massive, vesicular and

pillowed type. Banded iron formations are the

prominent linear bands, running approximately east -

west in the periphery to granite intrusion (Fig.3).

Coarse grained gabbro dyke is regional in extent,

running for several kilometres along NE - SW direction,

and cuts across various litho-units of the Sandur Schist

belt. The granite of the study area is Closepet granite,

which is juvenile. The total linear extent of the Joga

BIFs is approximately 2 km and the width varies from 1

to 20 m. The joga area BIFs comprise BHQ, BCQ,

BMQ, etc., with the general trend of BIF being N 800 E,

S 80o W and varying at places to N 40-50

o W, S 40-50

o

E and dipping towards east predominantly and in

exceptional cases towards west (Fig.3).

General Stratigraphy of the study area

Gabbroic dyke/Doleritic Dyke

Granites (Closepet) Sultanpura volcanic block (SVB)/Taluru Formations Metavolcanics

BIF with intercalations of Dolomite

Joga study area, comprising local stratigraphy,

correlated with the Sultanpura Volcanic block (SVB) of

Manikyamba et al., (1997) and Taluru formations of

Chadwick et al., (1996).

Structural Geology:

Litho-units of the study area show a general trend of N

70˚-80˚E to S70˚-80˚W and dipping towards south. At

the centre of the study area, the BIF band is folded into

syncline and anticline, adjacent to the granite intrusion.

Rose diagram (Fig. 5) shows bedding trends in the study

area. BIFs are showing prominent folding (Fig.4), with

axial planes trending N 40o E and N 80

o E, suggesting

(F1) first generation of folding.

Fig4: Photograph showing multiple tight isoclinal and

broad folds, with thickened hinges and thin drawn

limbs.

0

90

180

270

BEDDING TRENDS SHOWN BY BIF OF JOGA AREA

Fig5: Rose diagram showing trends of BIF bands from

the Joga area.

Geochemistry:

Based on the composition (wt. %) of SiO2, Al2O3 and

Fe2O3 content, the samples analysed are grouped as

Banded Cherty Quartzite, Banded Ferruginous

Quartzite, Banded Magnetite Quartzite and Banded

Hematite Quartzite. Samples show mixtures of SiO2 and

Fe2O3, varying from 46 to 95%. SiO2 and Fe2O3 are

varying from 39 to 62.5% and 6.6 to 36.92%,

respectively. Al2O3 lies between 0.83 and 1.2% in all

the three samples, suggesting a cherty BIF, with the

exception of sample no. 195 showing Al2O3 of 14.2%,

which is a shaly BIF. CaO is varying from 1.9 to 9.87%,

justifying the BIF association with carbonates. Sample

no. 567 has 49.69% of CaO due to its association with

Ankerite. Alkalies - Na2O+K2O - are less than 1%, with

the exception of sample no. 195, which is a shaly BIF.

Lack of correlation of Al2O3, CaO and alkalies suggests

little input of detrital feldspar in the BIF.




Table1: Average chemical composition (in wt. %) of BIF samples from the Joga area, compared with world

standard samples.

Lake

Superior#

Algoma# Archaean

*

Eastern

India*

CBIF^ 701

@ 603

@ 195

@ 567

@

1 2 3 4 5 6 7 8 9

SiO2 47.2 50.5 47.3 47.02 51.8 55.4 62.5 53.17 39.76

Al2O3 1.39 3 1.25 0.07 0.23 0.83 1.2 14.2 1.11

Fe2O3t 35.4 26.9 22.94 44.16 44.3 36.9 33.18 0.18 6.61

CaO 1.58 1.51 2.84 0.17 0.09 4.42 1.966 11.81 49.69

MgO 1.24 1.53 3.66 0.13 0.5 1.58 0.272 9.87 1.67

MnO 0.73 0.22 0.59 0.06 0.09 0.07 0.049 5.98 0.608

Na2O 0.12 0.31 0.22 0.1 0.19 0.00 0.273 1.94 0.099

K2O 0.14 0.58 0.09 0.13 0.07 0.01 0.179 0.79 0.0364

P2O5 0.06 0.21 0.22 0.07 0.08 0.16 0.17 0.13 0.00

# Gross and Mcleod (1980)

* Gole and Klein (1981)

^ Manikyamba et al., (1993)

@ Joga BIF – XRF values

The major and trace element data (Table 1) indicates

that major elements like K2O, Al2O3, MgO and P2O5 of

Algoma facies iron formation is at least twice that of the

Superior facies iron formations (Gross and Mcleod,

1980). The average values of the above elements of the

Joga samples are similar to those of the average values

of the Superior type. Sample nos. 701 and 603 are

showing more concentration of Fe2O3 and SiO2. This

might be because of their close association with high

grade iron ore deposits. Sample no.195 is showing more

content of Al2O3, MnO, MgO and CaO, indicating

carbonate facies of BIF. Sample nos. 603 and 701 are

showing less MnO concentration against the Algoma

and Superior type. When plotted on the triangular

diagrams of Lepp and Goldich (1964) and Govett

(1966) (Figures 7A and 7B), the Joga samples are

within and nearer to the Precambrian field. Further

discrimination is not possible on geochemical basis.

When the average values of the Archaean, Proterozoic,

Superior, Algoma types and the Joga BIF are plotted

against the respective oxide percentages (Figure 6), it is

observed that there is no significant variation in respect

of any of the elements, with exceptional cases of Cao,

MgO and Fe2O3.

Fig6: Composition of major elements of the Joga BIF samples, compared with Global and Indian standards.

The major elements composition of Joga BIF samples (701 and 603) is showing correlation with Algoma and

Archaean BIF of world standard, whereas sample no. 195 is showing similarity with comparatively higher

concentration of Al2O3 and lesser Fe2O3, indicating a cherty type BIF.





Table2: Analytical results of Au (in ppm) and SO3 (in wt. %) of samples from the study area

Sample no. Sample description Au by FA* SO3**

30

Sulphur sample from the mineralized zone, yellowish

and whitish powdery type sample with strong sulphur

smell, collected over a width of 30 cm across strike

with fragments of altered BIF

< 0.01 31.88

703 Vein quartz sample with lot of fresh sulphides, within

BIF 0.34 5.04

708 Vein quartz sample over a width of 50 cm, brownish red

in colour, emplaced within BIF 0.49

701 Banded Iron Formation sample associated with

Metavolcanics 0.145

603 Banded cherty Quartzite, 5 m wide and showing minor

folding 0.14

567 Banded cherty quartzite, associated with ankerite band 0.405

*FA- Fire Assay analysis of Au, carried out by the Shiva Analytical Labs., Bangalore,

**SO3 analysis, carried out by XRF method at CESS, Trivandrum.

Fig7A: Ternary plot of CaO+MgO, Fet and SiO2

Fig7A: Ternary plot of CaO+MgO, Fe and SiO2

indicating BIF samples are showing affinity to

Precambrian field. Sample nos. 701 and 603 are falling

within the Precambrian boundary, whereas sample nos.

567 and 195 are falling outside the Precambrian

boundary (after Lepp and Goldich, 1964)

Fig7B: Ternary plot of SiO2, Al2O3 and FeO

Fig7B: Ternary plot SiO2 , Al2O3 and FeO, showing

Sample nos. 701 and 603 are falling within Precambrian

field, where as sample nos. 195 and 567 are in

proximity of Precambrian BIF (after Govett, 1966).

Samples nos. 195 and 567 are identified as Banded

Cherty Quartzites, based on the field observations and

petrographic studies, however, the chemical

composition of the samples suggests the divergence on

the BIF nomenclature. This may be due to close

association of carbonate band with BIF.

Fig8: SiO2 versus Al2O3 discrimination diagram (after

Bonatti, 1975)

Fig8: SiO2 versus Al2O3 discrimination diagram (after

Bonatti, 1975) for Joga BIF indicating their

hydrothermal origin affinity. Sample no.195 is

indicating hydrogeneous deposit character and deep sea

sediments. The source of Iron in BIF could be due to

submarine volcanism and associated hydrothermal

circulation by exhalitemodel proposed by Gross (1965,

1960). In Figure 8, three samples collected from BIF

outcrops from the study area are showing affinity to

hydrothermal origin, indicating that the BIF of Joga

study area is of hydrothermal origin.




Fig9: Boudin structure shown by BIF from the study area (Reference pen length is 15.5 cm).

Boudin structure is observed from the in situ outcrop of

BIF, near Joga reservoir (Figure 9).

‘Boudin’ structure (Sausage like) in BIF might be due to

uniform fracturing of BIF bands due to tectonic stress

and deformation. It is noticed that the iron oxide layers

were more brittle than the adjacent quartz layers. The

interval of fracturing in the iron oxide layers is

approximately equal to the thickness of these layers and

apparently the strike of the fracture planes was parallel

to the strike of the bedding and thus produced uniform

long ‘boudin’ like structures. This deformation might

have taken place during later stage in the diagenesis and

compaction of the rock (cf. Chakraborty, 1992).

Petrographic study: Representative samples from each

individuallitho-unit from the Joga study area have been

collected and petrographic studies on their thin sections

were carried out under microscope. BIF sample has

shown the mineralogical assemblage of Quartz (40%),

Carbonates (20%), and minor minerals of Chlorite (5%),

opaque (5%) and epidote (5%) (Fig. 10).

BIF is very fine grained, banded with alternating iron-

rich and iron-poor bands. The rock is proportionately

more cherty and highly carbonated. The width of chert-

rich layer varies from 0.05 mm to 1 mm, in which grain

size variation is from 0.02 mm to 0.1mm. The layer is

dominantly composed of quartz that has grains of 2

modal sizes, the grains are subhedral to anhedral, which

shows typical granoblastic texture and development of

triple point junctions (recrystallization).

A few euhedral carbonate grains are also noticed with

well-developed cleavages. Fe-rich layer is composed of

iron oxides, carbonates, opaques, chlorite and quartz.

The quartz and carbonate crystals are subhedral to

anhedral in form, along with development of epidote

grains.

A slip plane has also been observed, which is

continuous and consistent, and may be a fracture plane

or related to shearing (probable S-C plane). The quartz

veins have been boudinaged and the spaces in between

are filled by carbonates, suggesting that these

carbonates are fracture-filling.

A few carbonate veins with subhedral to anhedral grains

of carbonate having perfect rhombic cleavages are

present, which are mainly fracture- fillings. In some

grains, the cleavages are kinked (Fig. 10). Minor

chlorite andepidote have also been noticed.

Metabasalts associated with BIF, from the mineralized

zone, have revealed the presence of Iron oxides like

hematitie and goethite. Sulphide minerals are

represented by pyrrhotite, pentalandite, chalcopyrite,

and pyrite.

Figure10: Photomicrograph of BIF sample.

Economic importance of the Joga BIF:

National Geophysical Research Institute (NGRI),

Hyderabad and Gold Research Group (G.R. Group)

have carried out extensive research on the study area

and reported Joga as the most important locality of a





possible mineable gold deposit, where a few sulphidic

BIF bands, having E-W strike with a combined strike

length of 20,000 m, are found. These bands are hosted

in metavolcanics, which are interpreted to be of

Archaean oceanic ridge basalts. These metabasalts are

classified as Sultanpura volcanic block and Taluru

formation. The triple junctions of the pillows near

sulphidic band are also sulphidic and contain more than

0.6 gpt gold. Fifty bulk samples were collected and

analysed, which have indicated a concentration of gold

varying from 0.3 to 2.9 gpt (Manikyamba et al., 1997).

Figure11: photograph showing whitish

sulphurmineralisation associated with reddish BIF:

At the surface most of the sulphides are oxidized and

sulphur smelling prominent near the highly fractured

and weathered BIF outcrops. Thin argillaceous

carbonate bands, probable equivalents of pelagic

sediments are also associated. Gabbro and doleritic

dykes are numerous and in close association. The entire

sequence may be a relict Archaean Oceanic ridge

assemblage and a pseudoophiolite. The sulphidic

deposits in these oceanic basalts most probably are

partial analogue of modern ridge smoker deposits,

where high concentrations of gold are found. Aplite,

pegmatite and quartz veins of 0.5 to 1 m wide cut across

these rocks near the granitic contact, and these do not

contain gold. Whitish yellow sulphurmineralisation

associated with reddish BIF is prominent and a sample

was collected from this zone, which is suspected to be a

prominent mineralized zone. The outcrop is showing

highly fractured BIF due to brittle deformation and a

lensoidal zone with yellowish and whitish concretionary

type sulphur nodules over a width of 20 to 30 cm is

found within the banded iron formation.

The sulphur mineralization appears as localised

phenomena and occurs as a pocket type. This type of

sulphur mineralization is also noticed in metabasalt,

where sulphur mineralization is found at cracks and

crevasses within metabasalt, which is adjacent to the

sheared zone.

A BIF sample with prominent oxidation stains (708) has

indicated a value 0.49 gpt of Au by Fire Assay method

(Table 2). The sample, collected from the in situ outcrop

of quartz vein over a width of 50 cm, is associated with

banded iron formation. This vein quartz emplacement is

showing a brownish colour due to oxidation of

sulphides, the vein quartz emplacement is lensoidal and

shows prominent pinching and swelling structures.

Gold deposits of the eastern greenstone belts are

comparable to those of the younger greenstone belts of

Canada, Zimbabwe and Australia, where the

mineralization is associated with quartz carbonate veins

often in iron-rich metabasic rocks. The gold was

emplaced as hydrothermal fluids, derived from early

komatiitic and tholeiitic magmas, and injected into

suitable dilatent structures Devaraju et al., (2009).

The BIF band is discontinuous and occurs within

metabasalt over a strike length of 8 km. BIF bands on

the eastern side of the study area are of oxide facies, and

found not containing any sulphides.

Metavolcanics adjoining to sulfidic BIF are showing

brecciated texture and numerous vein quartz and

carbonate veins are found along the sheared zones sub-

parallel to local trend of E-W. These metavolcanic rocks

are containing plenty of fresh sulphides of pyrite,

pyrrhotite, azurite, chalcopyrite, etc.

Conclusions:

Based on the geological, lithological, structural and

geochemical data of the Joga BIF, the following

conclusions can be drawn.

1. The main source for the iron and silica were

hydrothermal solutions, generated at AMOR.

Fluvial contribution of FeO and REEs in the form

of dissolved load from the land cannot be denied.

2. Signatures of volcanoclastic debris are preserved in

Cr and Ni content of BIF.

3. The banding of the BIF represents the break in

precipitation of iron due to the non-availability of

oxygen or hydro-thermal FeO or both.

4. Joga sulfide facies BIF is discontinuous, pocket

type.

5. Gold was emplaced as hydrothermal fluids, derived

from earlier tholeiitic magma and deposited in

suitable dilatant structures.

Acknowledgement:

Authors express gratitude to Dr. TejaswiLakkundi for

critical review of the paper, which has improved the

manuscript significantly. Authors are thankful to

Dr.Kantaraj and Mr.Chandankurmar for helping in

preparation of maps and diagrams. Authors are grateful

to the Dr. R.Dhanraju, Director AMD (Retd), whose

suggestions improved the quality of the manuscript

tremendously. Authors express their regards to




Dr.D.V.Reddy, Editor in Chief, IJEE for making this

publication successful.The authors are thankful to

PPOD (Petrology Petrochemisty Ore Dressing) lab.,

Bangalore for providing the petrographic facility and

CESS, Trivandrum, for XRF analyses. Authors are

grateful to Chairman, Department of Studies in

Geology, Karnataka University, for providing the

necessary facility to prepare this paper.

Reference:

[1] N.Beukes, Suggestion towards and classification of

and nomenclature for iron forations. Transvaal

Geological Society, South Africa, 285-290pp, 1980.

[2] Brian Chadwick, V.N. Vasudev, Nazeer Ahmed,

The Sandur Schist Belt and its adjacent plutonic

rocks implications for Late Archaean crustal

evolution in Karnataka, Jour. Geol. Soc. India,

vol.47,Jan 1996,pp 37-57,1996.

[3] Brian Chadwick, V.N.Vasudev and G.V.Hegde,

The Dharwar craton, southern India, and its late

Archaean Plate tectonic setting: current

interpretations and controversies, Proc. Indian

Acad.Sci (Earth Planet. Sci.), 106, No.4, December,

pp 249-258, 1997.

[4] Y.J.Bhaskar Rao, T.V.Sivaraman, G.V.C, Puntulu.,

K. Gopalan, and S.M. Naqvi. Rb-Sr ages of Late

Archaean metavolcanics and granites, Dharwar

craton, South India, and evidence for Early

Proterozoic thermotectonic event(s). Precamb. Res.

v.59, pp 145-170, 1992.

[5] K.L. Chakraborthy and Tapan Majumdar,

Geological Aspects of the Banded Iron Formation

of Bihar and Orissa, Jour. Geol. Soc. India, vol 28,

pp.109 to 133,1986.

[6] K.L. Chakraborty, T.Majumdar. An unusual

diagenetic structure in the Precambrian banded iron

formation (BIF) of Orissa, India, and its

interpretation. Mineral Deposita, 55-57pp, 1992.

[7] T.C.Devaraju., K.S. Anantha Murthy, and S.D.

Khanadali., Iron formation of the

Chiknayakanahalli Greenstone Belt, Karnataka,

India, Jour. Geol. Soc. India, vol. 28, pp 201 to

217,1986.

[8] R.B.Foote, Geology of the Bellary District. Madras

Presidency. Geol. Surv. India, Mem.25, 216p,

1895.

[9] R.E.P, Fripp. Stratabound gold deposits in

Archaean banded iron formation, Rhodesia,

Economic Geology, 71, 58-75pp.1976.

[10] R.M.Garrels. A model for the deposition of the

microbanded Precambrina iron formations.

American Journal of Science, 169-183pp, 1987.

[11] M.J.Gole and C.Klein. Banded Iron formation

through much of time. J.Geol.89:169-183pp, 1981.

[12] G.J.S.Govett,. Origin of Banded Iron Formation.

Geological Society of America, Bulletin, 1191-

1212pp, 1966.

[13] A. M. Goodwin., Archaean iron-formations and

tectonic basins of Canadian Shield. Econ. Geol. 68:

915-933pp, 1973.

[14] D.I.Groves, N.Phillips, S.M.Housoun,

C.A.Standing., ‘Craton-scale distribution of

Archaean greenstone gold deposits: predictive

capacity of the metamorphic model’, Economic

Geology,82,2045-2058pp.

[15] S.B.Jacobsen, M.R.Pimentel-Klose., A Nd isotopic

study of the Hamersley and Michipicoten banded

iron formations: the source of REE and Fe in

Archaean oceans. Earth Planet. Sci.Lett. 87, 29-

44pp, 1988.

[16] H.L.James., Sedimentary facies iron formations.

Economic Geology , v49, 253-293pp,1954.

[17] H.L.James,’ Chemistry of the iron-rich sedimentary

rocks’. In: Fleisher M (ed), ‘Data of Geochemistry’

6th

Edition, paper 440-W, U.S. Govt. Printing

Office, Washington D.C, 1966.

[18] R.M.K.Khan., S.M.Naqvi., Geology, geochemistry

and genesis of BIF of Kushtagi schist belt,

Archaean Dharwar craton, India, Mineralium

Deposita, 31,123-133pp (1996).

[19] M.M.Kimberley, ‘Palaeoenvironmental

classification of iron formations’, Economic

Geology, 73, 215-229, 1978.

[20] B. Krishna Rao. and M.Hanuma Prasad.

Geochemistry of the phyllites of the copper

Mountain region, Sandur schist belt, Karnataka.

Jour. Geo. Soc. India. v.46, pp.485-495, 1995.

[21] H.Lepp and Govitt. Origin of Precambrian iron

formation. Economic Geology, 1025-1060pp, 1964.

[22] MAH Maboko, (2001) the geochemistry of Banded

Iron Formations in the Sukumaland greenstone belt

of Geita, Northern Tanzania: Evidence for Mixing

of Hydrothermal and Clastic sources of the

chemical elements. Tanzania Journal of

Science,Vol. 27, 2001.

[23] C. Manikyamba., V. Balaram. and S.M. Naqvi.

Geochemical signatures of polygenetic origin of a

banded iron formation (BIF) of Archaean Sandur

greenstone belt (Schist belt) Karnataka nucleus,

India, Precambrian Research, 61, 137-164pp, 1993.

[24] C. Manikyamba., R. Kerrich. Geochemistry of

black shales from the Neoarchaean Sandur

Superterrane, India: First cycle volcanogenic

sedimentary rocks in an intraoceanic arc-trench

complex. GCA 70, 4663-4679p, 2006.

[25] C. Manikyamba. S.M.Naqvi., R.H. Sawkar and

G.R.Group. Identification of Sandur Schist belt as a

potential gold field. Research Communication,

Current Science, Vol.72, No.7, 10 April 1997.





[26] R.C.Morris, Genesis of Banded Iron Formation,

Jour.Geol.Soc.India, vol. 28, pp 227 -236, 1986.

[27] S.M.Naqvi, B.Uday Raj., D.V.Subba Rao,

C.Manikyamba. S. Nirmal Charan.V. Balaram, D.

Srinivas Sarma. Precambrian Research 114, 177-

197pp, 2002.

[28] T.J.Newbold. Description of the valley of Sandur.

Jour.Lit.Soc.Madras, v.8, pp 128-152, 1838.

[29] A.P.Nutman. SHRIMP U-Pb zircon ages of acid

volcanic rocks in the Chitradurga and Sandur

Groups and granites adjacent to Sandur Schist belt,

Karnataka. Journal Geological society of India,

153-165, 1996.

[30] K.A.Oak. The Geology and Geochemistry of the

Closepet Granite. Karnataka. South India. Unpubl.

Ph.D Thesis, Council for National Academic

Awards, U.K. (Oxford Polytechnic), 1990.

[31] G.N.Phillips G.N., D.I.Groves., J.E.Martyn., ‘An

epigenetic origin for Archaean banded iron

formation hosted gold deposits’. Economic

Geology, 79,162-171pp, 1984.

[32] M. Ramakrishnan., Tectonic evolution of the

Granulite Terrains of southern India. In:

B.P.Radhakrishna (Ed). Continental Crust of South

India. Jour. Geol. Soc. India, Mem.25, pp 35-44,

1993.

[33] B.P.Radhakrishna., T.C. Devaraju, and

B.Mahabaleshwar. Banded Iron Formation of India,

Jour. Geol. Soc. India, vol.28, pp 71-91.1986.

[34] A.Roy and S.K. Biswas,. Metamorphic history of

the Sandur schist belt, Karnataka. Jour. Geol. Soc.

India, v.20, pp.35-44, 1979.

[35] C. Sakthi Saravanan, B.Mishra., Uniformity in

sulphur isotope composition in the organic gold

deposits from the Dharwar Craton, Southern India,

Minera Deposita 44:597-605pp,2009.

[36] B.M.Simonson., Sedimentological constraints on

the origins of Precambrian iron formations’.

Geological society of America Bulletin, 96, 244-

252 pp, 1985.

[37] J.Swaminath, M. Ramakrishnan, Early Precambrian

Supracrusltals of Southern Inida. Memoir. Vol.

112, GSI, pp 1-350, 1981.

[38] Tarun.C.Khanna, Geochemical evidence for a

paired arc back arc association in the Neoarchaean

Gadwal greenstone belt, eastern Dharwar Craton,

India. Research Communications, Current Science,

Vol.104, No. 5, and 2013.

Books:

[1] GSI, Misc. Publication No. 30, Geology and

Mineral Resources of the States of India, Part VII,

Karnataka and Goa, compiled by Operation:

Karnataka and Goa, Bangalore 2006.

[2] G.Gross,. The geology of Iron deposits in Canada

in General Geology and evaluation of Iron deposits.

Geological Survey of Canada1965.

[3] M.Hanuma Prasad., Geological setting,

Petrography and Geochemistry of Supracrustal

Rocks of Copper Mountain Area, Bellary District,

Karnataka. Unpubl. Ph.D thesis. University of

Mysore 1994.

Date post:	07-Mar-2018
Category:	Documents
Upload:	truongthuan
View:	214 times
Download:	0 times

Geology and Geochemistry of Banded Iron Formations from...

Documents