Research Article Determination of Provenance and Tectonic ...

Research ArticleDetermination of Provenance and Tectonic Settings of NigerDelta Clastic Facies Using Well-Y Onshore Delta State Nigeria

S O Oni A S Olatunji and O A Ehinola

Department of Geology University of Ibadan Ibadan 200284 Oyo State Nigeria

Correspondence should be addressed to S O Oni talk2nicesamhotmailcom

Received 25 August 2014 Revised 8 November 2014 Accepted 10 November 2014 Published 28 December 2014

Academic Editor Franco Tassi

Copyright copy 2014 S O Oni et alThis is an open access article distributed under the Creative CommonsAttribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Provenance analysis serves to reconstruct the predepositional history of a sedimentsedimentary rock This paper focuses on thereconstruction of the provenance and tectonic settings of the Niger delta clastic facies using geochemical approachThemain typesof geochemical tests include major trace and rare earth element (REE) tests Twenty-one samples of shales and sandstones unitswere purposely collected from a depth between 1160 and 11480m grinded pulverized and sieved with a lt75 120583m About 5 g waspacked and sent to Acme analytical Laboratory Ltd Vancouver Canada The analyses were carried out by both induced coupledplasma-mass spectrometry (ICP-MS) and induced coupled plasma-emission spectrometry (ICP-ES) Bulk-rock geochemistry ofmajor oxides trace elements and rare earth elements was utilized for the provenance and tectonic setting determination Based onthe discrimination diagram for major oxides the probable provenance of the south eastern Delta clastic sediments was mainly ofthe active continental marginsThe bivariate plots of La versusTh LaY versus ScCr and TiZr versus LaSc and the trivariate plotsof La-Th-Sc Th-Sc-Zr10 andTh-Co-Zr10 are all plotted on the fields of active continental margin sediments which is consistentwith the known actively opening of a failed arm of triple junction The trace elements and REE analysis indicates that they arevirtually Fe-rich lithicquartz arkosic sandstones The normalizing factors used for the REE are Wakita chondrite Their rare earthelements (REE) pattern displays high light REEheavy REE (LREEHREE) ratio flat HREE and a significant negative Eu anomalywhich correlate well with the UCC and PAAS average composition The source area may have contained felsic igneous rocks

1 Introduction

The samples were taken from Y-field in Niger delta Thecoordinates of the study area were not given because of theproprietary nature of the data but the estimated locationis shown in Figure 1 The Niger delta extends from aboutlongitudes 3∘ E and 9∘ E and latitudes 4∘301015840 N to 5∘211015840 NThe Niger delta is located in the southern part of NigeriaThe Niger delta is situated in the Gulf of Guinea whichnorthwards merges with the structural basin in the Benueand middle Niger terrain holding thick marine paralic andcontinental sequence The onshore portion of the Niger deltaprovince is delineated by the geology of southern Nigeriaand southwestern Cameroon The Niger delta was formedas a result of basement tectonics related to the crustaldivergence during the late Jurassic to cretaceous continentalrifting of Gondwanaland that led to the separation of SouthAmerican African continentsTheNiger delta is large arcuate

to lobate tropical constructivewave of dominated type Activedeposition is presently occurring simultaneously in thesedepobelts under fluviatile conditions where there is interplaybetween terrestrial and marine influences

The Niger delta basin to date is the most prolific andeconomic sedimentary basin in Nigeria It is an excellentpetroleum province The Niger delta is situated in the Gulfof Guinea and extends throughout the Niger delta provinceFrom the Eocene to the present the delta has progradedsouthwestward forming depobelts that represent the mostactive portion of the delta at each stage of its development[1] These depobelts form one of the largest regressive deltasin theworldwith an area of some 300000 km2 [2] a sedimentvolume of 500000 km3 [3] and a sediment thickness of over10 km in the basin depocenter [4]

The Niger delta province contains only one identifiedpetroleum system [2 5] This system is referred to here asthe tertiary Niger delta (Akata-Agbada) petroleum system

Hindawi Publishing CorporationJournal of GeochemistryVolume 2014 Article ID 960139 13 pageshttpdxdoiorg1011552014960139

2 Journal of Geochemistry

5∘E 6∘E 7∘E 8∘E

0 50 100

(km)

8∘

6∘

5∘

9∘

7∘

4∘

Study areaEocene recent cycle withapproximate coast lines

Albian-Santonian cycleMetamorphic basement complex (precretaceous)VolcanicsCampanian-Paleocene cycle

Figure 1 Generalized and simplified geological map of Niger deltabasin as obtained from httpwwwintechopencom

The maximum extent of the petroleum system coincideswith the boundaries of the province The minimum extentof the system is defined by the areal extent of fields andcontains known resources (cumulative production plusproved reserves) of 345 billion barrels of oil (BBO) 938trillion cubic feet of gas (TCFG) and 149 billion barrels of oilequivalent (BBOE) [6] Currently most of this petroleum isin fields that are onshore or on the continental shelf in watersless than 200 meters deep and occurs primarily in largerelatively simple structures Among the provinces ranked inthe US Geological Surveyrsquos World Energy Assessment [7]the Niger delta province is the twelfth richest in petroleumresources with 22 of the worldrsquos discovered oil and 14of the worldrsquos discovered gas [6]

2 Materials and Methods

21 Sample Collection andAnalysis Twenty-one core sampleswere collected and subjected to inorganic analysis whichincludesmajor oxides trace elements and rare earth elementThe samples are first dried To avoid contamination thesamples are then washed in deionized water and dried againAfter preparation the samples are grinded and pulverizedSample reduction entails comminuting by sieving or crushingand grinding Standard procedure at most laboratories is tosieve soils and sediments to lt75 120583m The samples are thussieved with lt75 120583mThis is because sample preparation mustreduce the sample volume to a size suitable for analysis yetpreserves the bulk geochemical signature of the larger bodyAbout 3 g of the pulverized sample was then packed in asuitable bag and sent to Acme labs Vancouver Canada foranalysis

Oceanic island arc

Discriminant

Passive margin

Active continental margin

CIA

Series 1

5040

40

3020

2000

1000

minus10minus20

minus20

minus30minus40

minus40

minus50minus60

minus60minus70minus80

minus80

minus90minus100

minus100

Disc

rimin

ant f

unct

ion2

Figure 2 The plot of discriminant 2 against discriminant 1 thediscriminant function diagram for sandstones (after [8]) showingfields for sandstones from passive continental margins oceanicisland arcs continental island arcs and active continental marginsThe CIA at the centre represents continental island arc

0 4 8 12 16 20

Passive margin


Continental arc

Oceanic arc

0

02

04

06

08

10Ti

O2

()

Fe2O3(total ) + MgO ()

Figure 3 Bivariate plot of TiO2

versus (Fe2

O3

+MgO) diagrams forsandstones (after [8]) The fields are oceanic island arc continentalisland arc active continental margin and passive margins

3 Results

31 Tectonic Settings of Niger Delta Based on Major OxidesSee Table 1 and Figures 2 and 3

32 Results andDiscussion Knowledge of the tectonic settingof a basin is important for the exploration of petroleum andother resources as well as for paleogeography Some authorshave described the usefulness of major element geochemistryof sedimentary rocks to infer tectonic setting based ondiscrimination diagrams (eg [8 9]) This is because platetectonics processes impart distinctive geochemical signa-ture to sediments in two separate ways Firstly tectonicenvironments have distinctive provenance characteristics andsecondly they are characterized by distinctive sedimentaryprocess

Bhatia [8] proposed major element geochemical criteriato discriminate plate tectonic settings for sedimentary basinsfrom identified well-defined sandstone suites He compiled

Journal of Geochemistry 3

Table 1 Table of the eleven major element oxides in percentages

Samples depth Lithology FeO Fe2O3 CaO P2O5 MgO TiO2 Al2O3 Na2O K2O MnO SiO2 Total

1160ndash1180 Sand 05 05 11 00 01 01 17 02 02 00 955 10001560ndash1580 Sand 04 05 06 00 01 01 15 04 03 00 960 10001960ndash1980 Sand 10 11 08 00 01 01 17 06 06 00 938 10002960ndash2980 Shale 22 24 04 00 02 03 51 18 17 00 858 10003960ndash3980 Shale 43 47 04 01 04 07 111 26 30 00 727 10004560ndash4580 Shale 39 44 04 01 04 07 135 33 31 00 701 10005460ndash5480 Shale 36 40 02 00 01 03 38 46 29 00 804 10005760ndash5780 Shale 47 52 02 01 01 08 65 45 29 00 749 10006160ndash6180 Shale 34 38 07 01 02 06 110 37 28 00 738 10007060ndash7080 Sand 29 32 07 02 01 03 31 60 43 00 792 10007260ndash7280 Sand 28 32 07 01 01 03 44 68 47 00 769 10007560ndash7580 Sand 32 36 06 01 02 03 54 60 45 00 760 10007760ndash7780 Shale 43 48 08 01 06 06 90 19 31 00 747 10007960ndash7980 Shale 28 31 08 01 02 03 54 47 39 00 786 10008060ndash8080 Shale 29 32 14 00 06 02 35 10 17 00 855 10008160ndash8180 Sand 30 34 31 01 16 03 48 07 17 00 812 10008560ndash8580 Sand 38 42 17 01 04 02 39 10 16 00 829 10008960ndash8980 Shale 47 52 09 01 04 08 117 09 25 00 727 100010360ndash10380 Shale 27 30 05 01 03 04 60 13 28 00 828 100011060ndash11080 Shale 77 86 07 02 09 08 135 12 27 01 636 100011460ndash11480 Shale 61 68 05 01 05 09 146 11 21 01 672 1000

the average chemical compositions of medium- to fine-grained sandstones (eg arkose greywacke lithic areniteand quartz arenite) and modern sands from various regionsof the world and used these average values to proposediscrimination diagrams

Bhatia [8] used these diagrams to infer the tectonicsettings of five Paleozoic sandstone suites of easternAustraliaHe then proposed discriminant functions (functions 1 and2) by using 11 major element oxides (shown in Table 1) asdiscriminant variables to construct a territorial map for thetectonic classification of sandstones Discriminant scores offunctions 1 and 2 [8] were calculated from the unstandardizedfunction coefficient and the actual abundance of majorelement oxides in the average Bhatia [8] considered thetectonic setting of sandstones that he studied and generallyconcluded that sedimentary basins may be assigned to thefollowing tectonic settings based on the 11 major oxides(Table 1)

(1) oceanic arc fore arc or back arc basins adjacent tovolcanic arcs developed on oceanic or thin continen-tal crust

(2) continental island arc inter arc fore arc or back arcbasins adjacent to a volcanic arc developed on a thickcontinental crust or thin continental margins

(3) active continental margin Andean type basin devel-oped on or adjacent to thick continental margins andstrike-slip basins also developed in this environment

(4) passive continental margin rifted continental mar-gins developed on thick continental crust on the edges

of continents and sedimentary basins on the trailingedge of continent

These diagrams are used for the recovered sedimentsfrom well-Y southwestern Niger delta in order to determinethe tectonic setting of the area in Figure 2

Bhatia [8] proposed a discrimination diagram based ona bivariate plot of first and second discriminant functionsof major element analysis The sandstones were chosen torepresent the four different tectonic settings assigned onthe basis of comparison with modern sediments as shownin Figure 2 When this diagram is used samples with highcontent of CaO as carbonate must be corrected for carbonatecontent This discrimination diagram is used to classify thesuites of various samples into different tectonic settings Thediscriminant functions are

discriminant function 1 minus00447SiO2minus 0972TiO

2+

0008Al2O3minus 0267Fe

2O3+ 0208FeO minus 3082MnO +

0140MgO + 0195CaO + 0719Na2O minus 0032K

2O +

7510P2O5+ 0303

discriminant function 2 minus0421SiO2+ 1998TiO

2minus


2O3minus 1610FeO + 2720MnO +

0881MgO minus 0907CaO minus 0177Na2O minus 1840K

2O +

7244P2O5+ 4357 (after [8])

The discriminant plot is shown in Figure 2Modern sandstones from oceanic and continental arcs

and active and passive continental margins have variablecomposition especially in their Fe

2O3+MgO Al

2O3SiO2

K2ONa

2O and Al

2O3(CaO + Na

2O) contents Bhatia [8]


00

01

10

100

1000

10000

540 640 740 840 940 1040

Oceanic islandarc

Activecontinentalmargin

Passive continental margin

672 03

SiO2

Log

K 2ON

a 2O

Figure 4 The plot of log K2

ONa2

O-SiO2

discrimination diagramsof Roser and Korsch [9] for sandstone mudstone suites showing thedifferent tectonic settings

used this chemical variability to discriminate between differ-ent tectonic settings on a series of bivariate plots Figure 3shows the discrimination diagrams for sandstones (after [8])based upon a bivariate plot of TiO

2versus (Fe

2O3+ MgO)

The fields are oceanic island arc continental island arc activecontinental margin and passive margins

Roser and Korsch tectonic settings determinant diagramsare as follows the three tectonic settings passive continentalmargin PM active continental margin ACM and oceanicisland arc (ARC) are recognized on the K

2ONa2O-SiO

2dis-

crimination diagrams of Roser and Korsch [9] for sandstonemudstone suites as shown in Figure 4 Where sediments arerich in carbonate components the analysis was recalculatedas CaCO

3-free Failure to do this will shift samples to lower

SiO2values and from passive margin field into volcanic arc

field The other data values are plotted in active continentalmargin but could not show on the negative side of the verticallogarithmic scale (Figure 4)

33 Provenance or Source Rock Determination Using MajorOxides Discrimination diagram proposed by Roser andKorsch [9] distinguish the sources of the sediments into fourprovenance zones mafic intermediate felsic igneous prove-nances (Figure 5) The analysis was based on the chemicalanalyses in whichAl

2O3SiO2 K2ONa

2O and Fe

2O3+MgO

proved the most valuable discriminant The plot of the twodiscriminant functions is based upon the oxides of Ti AlFe Mg Ca Na and K and most effectively differentiatesbetween the provenances in Figure 5 The plot is based onthe discriminant functions 1 and 2 which are ratio for rawplots The plots using the raw oxides (Figure 5) revealedthat the sediments in the well were sourced from felsic andvery little from quartzoze sedimentary provenances Theproblem of biogenic CaO in CaCO

3and also biogenic SiO

2is

circumvented by using ratio plots in which the discriminantfunctions are based upon the ratios of TiO

2 Fe2O MgO

Na2O and K

2O all to Al

2O The formula for the raw oxides

used in Figure 5 is given as

discriminant function 1 minus1773TiO2+ 0607Al

2O3+

076Fe2O3(total) minus15MgO+0616CaO+0509Na

2Ominus

1224K2O minus 909

minus4 minus28

5

19

6

0

minus8

minus92

minus8 minus2 minus06 0 31 8 9

Mafic

Intermediate

Discriminant function 1

Disc

rimin

ant f

unct

ion2

Quartzoze

ProvenanceFelsic

Figure 5 Discriminant function diagram for the provenance signa-tures of sandstonemudstone suites usingmajor elements after Roserand Korsch [9]The fields were dominantly mafic intermediate andfelsic igneous provenances Also shown is the field with quartzozesedimentary provenance

discriminant function 2 0445TiO2+ 07Al

2O3minus

025Fe2O3(total) minus 1142MgO + 0438CaO +

1475Na2O + 1426K

2O minus 6861

Also the discrimination diagram for detrital grains afterGrigsby [10] using detrital grains as a provenance indicatoris shown in Figure 6 Grigsby proposed that the provenancesource for sedimentary grains can be determined by the plotin Figure 6

The trace element oxide distributions as plotted inFigure 7 generally show positive correlation with Al

2O3

reflecting association of most elements with the clay fractionSiO2content has a strong negative correlation with Al

2O3

reflecting that much of SiO2is present as quartz grains It also

confirms the quartz enrichment in the sand fractionWith theexception of SiO

2 Na2O and CaO the other oxides broadly

follow the trend of positive correlation with (increasing asAl2O3increases) indicating that they are associated with

micaceous andor clay minerals in the sediments Plottinggraphs of major oxides versus Al

2O3(Figure 7) variation

diagrams Fe2O3 MnO

2 MgO TiO

2 FeO P

2O5 and K

2O

show positive correlationThe observed depletion in Na

2O and CaO (negative cor-

relation) indicates that the studied sediments have sufferedfrom weathering and recycling [11 12] Generally Ca Naand K contents are controlled by feldspars and thus strongdepletion in CaO and Na

2O further suggests destruction

of plagioclase due to chemical weathering in the source orduring transport (Table 2)

34 Trace Elements Discrimination diagram to describesource rock composition is the ZrTi-NbY discriminationdiagram after Winchester and Floyd [13] and the ThSc-ZScdiagram after McLennan et al [14]


Table 2 ThSc-Zr-Sc La Co Th and Sc values

Samples depth Lithology ThSc ZrSc La Co Th Sc Zr101160ndash1180 Sand 28 366 89 19 34 12 4391560ndash1580 Sand 24 295 81 14 26 11 3241960ndash1980 Sand 20 275 92 39 32 16 442960ndash2980 Shale 17 283 167 13 55 32 9043960ndash3980 Shale 14 230 301 132 99 71 1634560ndash4580 Shale 12 172 317 129 104 86 1485460ndash5480 Shale 15 373 91 9 38 25 9335760ndash5780 Shale 13 401 96 174 58 44 17656160ndash6180 Shale 09 206 232 97 68 75 15487060ndash7080 Sand 14 409 89 117 26 19 7787260ndash7280 Sand 06 373 46 12 17 27 10077560ndash7580 Sand 07 270 64 192 22 31 8367760ndash7780 Shale 13 236 161 132 66 49 11567960ndash7980 Shale 08 263 59 294 22 29 7638060ndash8080 Shale 19 383 81 115 34 18 698160ndash8180 Sand 22 363 179 124 64 29 10528560ndash8580 Sand 15 215 115 414 38 25 5388960ndash8980 Shale 16 248 26 85 10 63 15610360ndash10380 Shale 25 375 186 114 66 26 97611060ndash11080 Shale 11 196 376 214 101 93 182311460ndash11480 Shale 08 175 292 224 9 109 1908Average value 15 291

Intermediate

Felsic(plutonic)

Maficplutonic

MgO(MgO + Al2O3)

MgO

(M

gO+

Al 2

O3)

TiO +V2O3

00000

00000

01000

02000

03000

04000

05000

06000

07000

08000

09000

10000

50000

100000

150000

200000

250000

300000

Figure 6 Discrimination plot of TiO2

+V2

O3

versusMgO(MgO+Al2

O3

) for detrital grains after Grigsby [10]

Floyd and Winchester in a series of papers (eg [13 16ndash18]) specifically addressed the identification of rock typeThe most commonly used approach is their ZrTiO

2-NbY

diagram [13] which has subsequently been updated usinga much larger dataset and statistically drawn boundaries

by Pearce [19] This diagram is essentially a proxy for theTAS classification diagram where NbY is a proxy foralkalinity (Na

2O + K

2O) and ZrTiO

2is a proxy for silica

NbY increases from subalkalic to alkalic compositions andZrTiO

2increases from basic to acid compositions

ThSc-ZSc diagram after McLennan et al [14] plot givesinsight in the degree of fractionation of the source rockswhich is expressed in ThSc ratio Furthermore this plotdescribes the degree of sediment recycling that is expressedin the ZrSc ratio Increased recycling concentrates zirconin sedimentary rocks (increase in Zr concentration) atthe expense of volcanic material contained in the detritus(decrease in Sc-concentrations) The plot of ThSc versusZrSc diagram is shown in Figure 8 describing most ofthe sediments found in the zone of recycling and zirconconcentration of upper continental crust

Trace elements such as La Th Zr Nb Y Sc Co andTi have been recognized as valuable provenance signaturesfor shales arenites and wackes [15 20 21] Bivariate plotsof TiZr-LaSc as well as triangular La-Th-Sc Th-Sc-Zr10Th-Sc-Zr10 and Th-Co-Zr10 plots are useful means todiscriminate the tectonic settings of clastic sedimentary rocks[15]

Distinctive fields for four environments are recognizedon the trivariate plots of La-Th-Sc Th-Sc-Zr10 and Th-Co-Zr10 On La-Th-Sc plot the fields of active continentalmargin sediments and passive continental margin sediments


02468

10121416

0 02 04 06 08 10

5

10

15

20Magnesium oxide MgO

02468

10121416

0 1 2 3 4 502468

1012141618

0 2 4 6 8 10

Iron II oxide FeO

02468

1012141618

0 2 4 6 8 1002468

10121416

0 005 01 015 02

02468

1012141618

0 001 002 003 004 005 006 007 00802468

10121416

0 1 2 3 4 5 6 7 8

02468

10121416

0 05 1 15 2 25 3 35

Calcium oxide CaO

00 05 10 15 20

Titanium oxide TiO2

y = 15419x minus 00404R2 = 08463

y = 29156x + 5628

R2 = 00656

Potassium oxide K2O

y = 0948x + 43228

R2 = 00808

y = 20126x minus 00903

R2 = 0658

Iron III oxide Fe2O3

y = 181x minus 00903

R2 = 0658 R2 = 03403

Phosphorus oxide P2O5

y = 56849x + 21434

Manganese oxide MnO2

y = 18581x + 18806

R2 = 04864

Sodium oxide Na2O

y = minus01004x + 69868

R2 = 00025

0 20 40 60 80 100 120

1614121086420

minus2

y = minus16841x + 81044

R2 = 00647 R2 = 07614

Silica oxide SiO2

y = minus04227x + 40228

Figure 7 Covariation of Al2

O3

versus major elements for the 11 major oxides There is a positive correlation of Al2

O3

with almost all themajor elements SiO

2

shows negative correlation

overlap but theTh-Sc-Zr10 andTh-Co-Zr10 show completeseparation

La-Th-Sc discrimination diagram for greywackes inFigure 9

Th-Sc-Zr10 discrimination diagrams for greywackesin Figure 10

Th-Co-Zr10 discrimination diagrams for greywackesin Figure 11 (after [15])

Also the various plots that indicate the felsic provenanceof the samples are as shown in Figures 12 and 13 (Table 4)

35 Various Trace Elemental Ratios Used in EvaluatingProvenance and Depositional Conditions Elevated values of


0

05

1

15

2

25

3

0 10 20 30 40 50

ThS

c

ZrSc

Upper continental crust

Lower continental crust

Zone of sediment recyclingand zircon concentration

Figure 8 ThSc versus ZrSc diagram after McLennan et al [14]reflecting reworking and upper crust input

1 0

0

02

02

04

04

04

06

06

06

08

08

08

10

1 La

Th Sc

A

B

C

D

02

Figure 9 The plot of La-Th-Sc showing the provenance of thesediments to be mainly of active continental margin (after [15])Thefields are A oceanic island arc B continental island arc C activecontinental margin and D passive margin

A

B

C

D

Th

Sc Zr10

Figure 10 Th-Sc-Zr10 plot showing the provenance of the sedi-ments to be still mainly of active continental margin (after [15])

Th

Co Zr10A

B

CD

middot

Figure 11 Th-Co-Zr10 plot showing the provenance of the sedi-ments to be active continental margin (after [15])

100

10

01

00001 01 1 10

LaSc

ThC

o

Basicrocks

Felsic

Figure 12ThCo versus LaSc for the samplesThe logarithmic plotshows that the samples are sourced from felsic or acidic silicic rocksand very few of the samples tend towards intermediate provenance

thorium with respect to uranium can indicate a felsic sourceThe ThU ratio which is often used in relation to Th- andU-concentrations as present in weathering under oxidizingconditions has been used to determine felsic provenance[14 22] Weathering under oxidizing conditions results inthe mobilization of uranium as U6+ whereas thorium (Th)remains immobile This causes the ThU ratio to increasesignificantly Higher abundances of incompatible elementslike Th indicate felsic rather than mafic sources Materialssuch as granodiorite source from old upper continental crustand from felsic gneisses are good examples The ThU ratiocan only be used for sedimentary rocks The ThU ratio hasan average of 41 (Table 3) which is very close to that ofupper continental crust of 38 The high ratios of ThSc andZrSc indicate a slight input of felsic materials from recycledsedimentary provenance

Al2O3TiO2ratios of most clastic rocks are essentially

used to infer the source rock compositions because ratioAl2O3TiO2increases from 3 to 8 for mafic igneous rocks

from 8 to 21 for intermediate rocks and from 15 to 70 for felsicigneous rocks [27] It will be observed that almost all values


Table 3 Table of various elemental ratios

Sample (in meters) Lithology KCs ratio ThU ratio CrTh ThCo Al2O3SiO2 LaSc ThSc1160ndash1180 Sand 02 49 29 18 17 742 2831560ndash1580 Sand 03 43 27 19 15 736 2361960ndash1980 Sand 04 40 38 08 17 575 2002960ndash2980 Shale 11 34 65 04 17 522 1723960ndash3980 Shale 11 35 71 08 16 424 1394560ndash4580 Shale 10 37 77 08 19 369 1215460ndash5480 Shale 20 48 166 04 13 364 1525760ndash5780 Shale 13 48 141 03 8 218 1326160ndash6180 Shale 09 40 99 07 18 309 0917060ndash7080 Sand 32 52 235 02 10 468 1377260ndash7280 Sand 33 15 553 01 15 170 0637560ndash7580 Sand 29 28 568 01 18 206 0717760ndash7780 Shale 20 41 86 05 15 329 1357960ndash7980 Shale 33 31 755 01 18 203 0768060ndash8080 Shale 14 31 121 03 18 450 1898160ndash8180 Sand 16 43 80 05 16 617 2218560ndash8580 Sand 23 48 518 01 20 460 1528960ndash8980 Shale 19 43 94 12 15 413 15910360ndash10380 Shale 34 60 70 06 15 715 25411060ndash11080 Shale 11 53 92 05 17 404 10911460ndash11480 Shale 08 47 107 04 16 268 083Average 17 41 190 737 159

Table 4 Range of elemental ratios for felsic and mafic igneousrocks and corresponding upper continental crust values The tableof range of mafic and felsic rocks is after Cullers [23 24] Cullersand Podkovyrov [25] Cullers et al [26] and the UCC values areafter Taylor and McLennan [20]

Elementalratios Felsic rocks Mafic rocks Upper continental

crustThSc 084ndash2005 005ndash022 079ThCo 027ndash194 004ndash14 063ThCr 013ndash27 0018ndash0046 013CrTh 400ndash1500 25ndash500 776LaTh 250ndash163 043ndash086 221

for the Al2O3TiO2ratio are above 15 with an average of 159

(Table 3) which is an indication that the source rock is felsicor acidic igneous rock such as granite granodiorite rhyolitedacite or aplite The elevated ZrSc ratios reflect significantreworking and a clear input fromupper crust igneous sourcesThSc values for the analyzed samples (Table 3) were in therange of 083ndash283 implying a felsic igneous provenanceThesame applies for the ThCo ratio (Table 3) as most of thevalues are above 027 and less than 195 However it will beobserved that 7060ndash7080 7260ndash7280 7560ndash7580 and 7960ndash7980 their ThCo ratio is less than 022 (implying maficsource) and their CrTh ratios are greater than 1500 around50 and even 755 for 7960ndash7980 and this also implies a maficsource input

0123456789

10

0 2 4 6 8 10

LaTh

More mafic

More felsic

ThYb

Figure 13 LaTh versus ThYb plot showing felsic versus maficcharacter after McLennan et al [20]

The LaTh versus ThYb plots have been used to differ-entiate between felsic and mafic nature of source rocks [1528] In these plots Figure 13 the studied samples show felsiccharacter of source rocks by its unusually high LaTh (felsicprovenance) as compared withThYb (mafic provenance)

36 Provenance from Rare Earth Elements Rare earth ele-ments (shown in Table 5) comprise the lanthanide elements[La-Lu] as well as Y [29] Since Y mirrors the heavylanthanides Dy-Ho in terms of geochemical behavior it istypically included with them for discussion Sc may also beincluded because in low temperature aqueous fluids such asseawater it behaves similarly to REE in having exceptionally


Table 5 Rare earth elements concentrations in ppm for the analyzed samples

Sample (in meters) La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Yppm ppm ppm ppm ppm ppm ppm ppm ppm ppm ppm Ppm ppm ppm ppm

1160ndash1180 89 2001 2 89 15 01 12 01 1 01 04 lt01 04 lt01 331560ndash1580 81 1811 19 8 13 lt01 1 01 08 01 03 lt01 04 lt01 281960ndash1980 92 1938 21 96 16 02 14 01 11 02 05 lt01 05 lt01 462960ndash2980 167 3608 39 169 28 04 22 03 18 03 07 01 08 01 713960ndash3980 301 6814 76 353 57 1 44 06 35 06 16 02 16 02 1474560ndash4580 317 6795 76 337 52 09 48 06 35 06 17 02 16 02 1425460ndash5480 91 2118 26 124 19 03 17 02 12 02 05 lt01 06 lt01 495760ndash5780 96 2582 31 147 28 05 25 03 19 03 08 01 09 01 576160ndash6180 232 5884 73 348 58 11 49 06 38 06 14 02 15 02 1497060ndash7080 89 249 34 155 26 05 27 03 18 03 07 lt01 08 lt01 857260ndash7280 46 1537 22 11 18 03 16 02 13 02 06 lt01 06 lt01 547560ndash7580 64 194 26 137 23 05 23 03 16 03 07 lt01 06 lt01 67760ndash7780 161 4568 6 277 45 08 34 04 24 05 1 01 1 01 1077960ndash7980 59 175 23 121 21 04 18 02 14 02 05 lt01 06 lt01 538060ndash8080 81 2261 28 135 22 04 16 02 12 02 05 lt01 05 lt01 498160ndash8180 179 4158 48 228 36 06 29 03 21 03 08 01 09 01 98560ndash8580 115 285 32 159 26 05 2 03 15 03 06 lt01 06 lt01 628960ndash8980 26 6017 71 318 48 09 36 04 28 05 11 02 13 02 11510360ndash10380 186 404 44 204 3 05 24 03 18 03 07 01 08 01 7111060ndash11080 376 9197 96 443 73 11 61 08 5 08 22 03 22 03 20111460ndash11480 292 7709 96 437 74 13 63 08 49 08 2 03 21 03 197Average 16 16 15 15 12 VALUE 10 08 08 06 06 04 06 09

low concentrations and by entering the sixfold coordinatedmineral sites Low atomic number members of the seriesfrom La-Sm are termed the light rare earth elements (LREE)Those with higher atomic numbers from Gd-Yb are termedthe heavy rare earth elements (HREE)

The patterns of shapes and trending structure on REEdiagrams can be used to evaluate the petrology of a rockMost important is the Europium anomaly that at most timesis enriched or depleted and as such assumes position whichoften lies off the general trend This anomaly is definedby the other elements on the REE diagram and termedeuropium anomaly If the plotted composition lies above thegeneral trend then the Eu anomaly is described as positiveand if it lies below the general trend it is described asnegative

The REE pattern of average sediments is interpretedto reflect the average upper continental crust and thus anegative Eu anomaly is found in most sedimentary rocksThis indicates that shallow intercrustal differentiation involv-ing plagioclase differentiation (through either melting orfractional differentiation) must be a fundamental process incontrolling the composition and element distribution withinthe continental crust [20] Before the plot the REE valuesin ppm as obtained from the analyzed samples have to benormalized The REE chondrite normalizing factors used forthis study are from Wakita et al [30] as shown in Figure 14Also the North American shale composition is used as shown

in Figure 15 Besides the normalized plot other parametersused to characterize the REE abundant in rocks include

fractionation indices represented by (LaYb)cn whichis an index of the enrichment of the light rare earthelements (LREE) over heavy rare earth elements(HREE)Eu anomalyCe anomalyHREE depletion represented by (GdYb) gt 20grain size

37 Fractionating IndicesDegree of Fractionation of REE Thedegree of fractionation of REE pattern can be expressed byconcentration of light REE (La or Ce) ratio to the concentra-tion of heavy REE (Yb) The lanthanum (La) and ytterbium(Yb) are often used which will have to be normalized andthis ratio is expressed as (LaNYbN) This combined withEu anomaly is very important parameter that describes REEpatterns and can be used in determining the source rockThese fractionation indices represented by (La)N(Yb)N thatis [(La sampleLa chondrite)(Yb sampleYb chondrite)]ratio can be used to define relative behavior of LREE to theHREEThis ratio has been calculated for all the samples in thepresent study as presented in Table 6 It is within the range of197 and 546 with an average value of 308 indicating that theHREE are very much depleted with respect to LREE in thepresent study


00000

05000

10000

15000

20000

25000

La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Y

Series 1Series 2Series 3Series 4Series 5Series 6Series 7



Figure 14 Wakita chondrite normalized spider diagrams


15

1

05

0

minus05

minus1

minus15

minus2




Figure 15 NASC normalized spider diagram

371 Europium (Eu) and Cerium (Ce) Anomaly Within rareearth elements under reducing conditions as within themantle or lower crust europium may exist in the divalentstate (Eu2+) This results in an increase in the ionic radius ofabout 17 making it essentially identical to Sr2+ The conse-quence of this is that Eu substitutes freely in place of Sr infeldspars notably plagioclase feldspars leading to distinctivegeochemical behavior of ldquoEurdquo compared with other REE Ingeneral anomalous activity of Eu is an indication of an earlierevent that occurred in a reducing igneous environmentwhicheventually evolved into upper continental crust [20]

Similarly in oxidizing conditions Ce3+ may be oxidizedto Ce4+ leading to a decrease in the ionic radius of about15 The only place where this reaction occurs on a largescale is marine environment associated with the formation ofmanganese nodulesWhen Ce3+ oxidizes to Ce4+ it separatesas an insoluble phosphate if it is in a marine environmentThis will cause a distinctive Ce depletion in ocean waters andphases precipitated in equilibrium with seawater Apart fromthose anomalies the REE behaves in an unusually coherentgroup of elements There is a continuous decrease in ionicradii from La to Lu and this is termed lanthanide contractionThe decrease in ionic radii is due to increase in the effectivenuclear charge pulling the electrons towards the nucleusthereby reducing the electron radii

38 Eu Anomaly Europium anomaly usually represented by[EuEulowast] may be quantified by comparing the normalizedmeasured Eu concentration with an expected concentration(Eulowast) The Eulowast is obtained by interpolating between thenormalized values of Sm and Gd that is Eulowast = (Smn +Gdn)2

The Eu used in this study is the concentration of Euin the sediments that is Wakita chondrite normalized andEulowast is a calculated value obtained by linear interpolation oraverage between Smn (samarium chondrite normalized) andGdn (gadolinium chondrite normalized) So the europiumanomaly is given by

Eu

Eulowast=

Average value of chondrite normalized Eu of the data EunAverage value of chondrite normalized (Smn + Gdn) 2

(1)

Taylor and McLennan [20] recommended the use of ageometric mean for calculating the Eu anomaly as follows

EuEulowast= radic

EunSnn times Gdn

(2)

Although a number of elements or minerals may deter-mine the distribution of Eu during igneous processes themost important is feldspar particularly plagioclase Europiumanomalies are majorly controlled by feldspars particularlyin felsic magmas This is because Eu2+ (divalent form ofEu) is present in plagioclase and potassium feldspars arecompactable in contrast with the incompatible trivalent REEThus the removal of feldspar from a felsic melt by crystalfractionation or partial melting of a rock in which feldsparis retained or present in the source will give rise to a negativeEu anomaly In plagioclase substantial Eu2+ may substitutefor Ca2+ in place of Sr thus the Eu anomaly (EuEulowast) reflectsthe extent of plagioclase fractionation leading to pronouncedenrichments of its associated trivalent REE and depletion ofEu Thus liquids that formed where plagioclase is a stableresidual phase or from which plagioclase is crystallized andlost will tend to be significantly depleted in Eu so will havea negative Eu anomaly On the other hand Rudnick [31]suggested that the positive Eu anomaly is mainly due to theeffect of areas prominent in hydrothermal vents or due to thefeldspar origin


Table 6 REE chondrite normalized elemental ratios used in analyzing the provenance of the sediments

Samples Lithology EuEulowast LaYb CeCelowast GdYb ZrTiO2 ΣLREE ΣHREE ΣLΣH LaY LaV1160ndash1180 Sand 048 546 102 256 004 60 22 28 270 2701560ndash1580 Sand 000 530 103 225 003 58 19 31 289 0741960ndash1980 Sand 081 402 100 205 004 61 28 22 200 0662960ndash2980 Sand 083 302 101 165 003 74 47 16 235 0443960ndash3980 Sand 079 226 101 143 002 88 68 13 205 0464560ndash4580 Sand 078 229 101 147 002 88 69 13 223 0455460ndash5480 Shale 087 328 102 187 003 64 33 19 186 0285760ndash5780 Shale 086 237 104 161 002 68 49 14 168 0146160ndash6180 Shale 079 220 103 153 003 86 68 13 156 0337060ndash7080 Sand 085 253 106 181 003 68 43 16 105 0317260ndash7280 Sand 090 260 112 181 003 58 34 17 085 0147560ndash7580 Sand 091 293 108 217 002 63 40 16 107 0187760ndash7780 Shale 083 255 105 170 002 81 56 14 150 0327960ndash7980 Shale 092 284 107 193 002 61 34 18 111 0198060ndash8080 Shale 094 386 106 221 003 65 32 20 165 0378160ndash8180 Sand 083 281 102 171 003 78 50 16 199 0698560ndash8580 Sand 092 351 103 203 002 70 39 18 185 0388960ndash8980 Shale 083 244 102 148 002 86 62 14 226 04810360ndash10380 Shale 085 310 101 172 003 76 47 16 262 06611060ndash11080 Shale 074 204 103 137 002 94 78 12 187 04011460ndash11480 Shale 076 197 103 141 002 92 78 12 148 033Average 079 302 104 180 003 733 474 170 181 041

Values greater than 085 indicate positive Eu anomalyvalues less than 085 indicate a negative Eu anomaly and avalue of precisely 085 indicates no anomaly In the presentstudy as illustrated in Table 6 Eu anomaly values varyfrom 000 to 092 with an average of 079 corresponding tonegative Eu anomaly This is also shown in Figures 14 and15 as spider diagrams Felsic rocks and sediments usuallyhave negative anomalies due to lithospheric or intracrustalfeldspar fractionation or breakdown of feldspars duringweathering processes [32] Felsic igneous rocks usually con-tain higher LREEHREE ratios and more pronounced nega-tive Eu anomalies while mafic igneous rocks contain lowerLREEHREE ratios with few or no Eu anomalies [24] Inaddition Cullers [23] proposed that sediments with CrThratios ranging from 25 to 195 and EuEulowast values from 048 to078 comemainly from felsic not mafic sources According tothe study of McLennan et al [21] active margin sedimentsin contrast to passive margin sediments often show lowerEuEulowast

39 CeAnomaly CeCelowast anomaly is usually given byCeCelowast= 5 timesCen4Lan+Smn

The samples values (Table 6) range from100 to 108 with calculated average value of 104 This isno anomaly as it is approximately 1 Ce anomaly (CeCelowast)can indicate REE redistribution during weathering possiblya consequence of fractionation also for Sm and Nd isotopesSince the CeCelowast ratios are close to 1 the small differencein CeCelowast for the studied rocks is within the uncertaintiesof the measurements Thus no anomalous CeCelowast can bededuced

310 (GdYb)119873

Ratio The (GdYb)N ratio also documentsthe nature of source rocks and the composition of thecontinental crust [20] Archean crust generally has higher(GdYb)N ratio recording typically values above 20 insedimentary rocks whereas the post-Archean rocks have(GdYb)N values commonly between 10 and 20 [33ndash35] About four of the twenty-one analyzed samples have(GdYb)N ratios greater than 20 (Table 6) indicating thepossibility of the post-Archean rocks being the source rocksfor the formation

311 Grain Size and REE REE in various grain sizes has beenexamined by Cullers et al [36] and Cullers et al [26] Theyfound that clay contains the largest fraction of REE (highLaYb) followed by silt which is of lesser proportionfractionand lowest fractions in sands (least LaYb) than finer grainsizes The presence and magnitude of Eu anomalies arehowever similar for all grain sizes Because sandstones tendto have lower REE than shales their REE patterns are moreprone to be considerably dominated by heavy minerals

4 Conclusion

41 Provenance of the Sediments Based on major oxidesmost of the sample plots in the fields were felsic igneousprovenances suggesting high content of silica from an acidrock most probably granite or gneiss or dacite or any acidic(felsic) igneous rock

The provenance and prevalent conditions of depositionfrom various elemental ratios indicate that the ThU ratio


has an average of 41 which is very close to that of uppercontinental crust of 38 The high ratios of ThSc and ZrScindicate a slight input of felsic materials from recycled sed-imentary provenance Higher abundances of incompatibleelements like Th indicate felsic rather than mafic sourcesElevated values of thorium with respect to uranium mayimply a felsic source It will be observed that most valuesfor the Al

2O3TiO2ratio fall between 15 and 70 (the range

for igneous rock) which is an indication that the source rockis felsic or acidic igneous rock such as granite granodioriterhyolite dacite or aplite ThSc values for the analyzedsamples were in the range of 083ndash283 implying a felsicigneous provenance The same applies for the ThCo ratio asmost of the values are above 027 and less than 195 (ThScand ThCo values for felsic rocks are 084ndash2005 and 027ndash195 resp) Thus the source of the rock weathered to give thesediment is a felsic or acidic igneous rock probably graniteThCo versus LaSc logarithmic plot shows that the samplesare sourced from felsic or acidic silicic rocks and very few ofthe samples tend towards intermediate provenance

Provenance from REE and negative EU anomaly pointsto the fact that average REE pattern of the sediments isinterpreted to reflect the average upper continental crustCoupled with a negative Eu anomaly conclusions can bedrawn that shallow intercrustal differentiation involving pla-gioclase differentiation (through either melting or fractionaldifferentiation) must be a fundamental process in removalof feldspar from a felsic melt The LREE enrichment as wellas relatively flat HREE pattern also confirms felsic sourcerock The relative REE patterns and Eu anomaly size havealso been utilized to deduce sources of sedimentary rocks[20 37] Mafic rocks contain low LREEHREE ratios andtend not to contain Eu anomalies whereas more felsic rocksusually contain higher LREEHREE ratios and negative Euanomalies [38] A negative Eu anomaly is a confirmation ofthe sedimentrsquos provenance from felsic sources Thus from theenrichment LREE or higher LREEHREE we can concludethat the provenance of the sediments is felsic rock

42 Tectonic Settings Frommajor oxides it can be concludedthat the tectonic setting of theNiger delta is active continentalmargin and this confirms the cretaceous rift systems ofWest and Central Africa The rift system extends for over4000 km from Nigeria northwards into Niger and Libya andeastwards to Sudan and Kenya This cretaceous rift systemforms a trough in which those sediments are depositedThe trace elements confirmed the tectonic settings of thesediments as active continental margins The trivariate plotsof La-Th-Sc Th-Sc-Zr10 and Th-Co-Zr10 all register theprovenance of the sediments to be active continental marginThe ThSc versus ZrSc diagram after McLennan et al [14]confirms the zone of sediment recycling in upper crustinput

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

References

[1] H Doust and E Omatsola ldquoNiger Deltardquo in DivergentPassiveMargin Basins J D Edwards and P A Santogrossi Eds AAPGMemoir 48 pp 239ndash248 American Association of PetroleumGeologists Tulsa Okla USA 1990

[2] H Kulke ldquoNigeriardquo in Regional PetroleumGeology of theWorldPart II Africa America Australia and Antarctica H Kulke Edpp 143ndash172 Gebruder Borntraeger Berlin Germany 1995

[3] J Hospers ldquoGravity field and structure of the Niger DeltaNigeria West Africardquo Bulletin of the Geological Society ofAmerica vol 76 no 4 pp 407ndash422 1965

[4] A Kaplan C U Lusser and I O Norton ldquoTectonic map ofthe world panel 10rdquo scale 110000000 American Associationof Petroleum Geologists Tulsa Okla USA 1994

[5] C M Ekweozor and E Daukoru ldquoNorthern delta depobeltportion of the Akata-Agbada petroleum system Niger DeltaNigeriardquo in The Petroleum SystemmdashFrom Source to Trap L BMagoon and W G Dow Eds AAPG Memoir 60 pp 341ndash358American Association of Petroleum Geologists Tulsa OklaUSA 1994

[6] Petroconsultants Petroleum Exploration and ProductionDatabase Petroconsultants Houston Tex USA 1996

[7] T R Klett T S Ahlbrandt J W Schmoker and J L DoltonldquoRanking of the worldrsquos oil and gas provinces by knownpetroleum volumesrdquo US Geological Survey Open-File Report97-463 1997

[8] M R Bhatia ldquoPlate tectonics and geochemical composition ofsandstonesrdquo Journal of Geology vol 91 no 6 pp 611ndash627 1983

[9] B P Roser and R J Korsch ldquoDetermination of tectonicsetting of sandstone-mudstone suites using SiO

2

content andK2

ONa2

O ratiordquoThe Journal of Geology vol 94 no 5 pp 635ndash650 1986

[10] J D Grigsby ldquoDetrital magnetite as a provenance indicatorrdquoJournal of Sedimentary Petrology vol 60 no 6 pp 940ndash9511990

[11] Y J Joo Y I Lee and Z Bai ldquoProvenance of the QingshuijianFormation (Late Carboniferous) NE China implications fortectonic processes in the northern margin of the North Chinablockrdquo Sedimentary Geology vol 177 no 1-2 pp 97ndash114 2005

[12] Z Jin F Li J Cao S Wang and J Yu ldquoGeochemistry of DaihaiLake sediments Inner Mongolia north China implications forprovenance sedimentary sorting and catchment weatheringrdquoGeomorphology vol 80 no 3-4 pp 147ndash163 2006

[13] J A Winchester and P A Floyd ldquoGeochemical discriminationof different magma series and their differentiation productsusing immobile elementsrdquo Chemical Geology vol 20 pp 325ndash343 1977

[14] S M McLennan S Hemming D K McDaniel and G NHanson ldquo Geochemical approaches to sedimentation prove-nence and tectonicsrdquo in Processes Controlling the Compositionof Clastic Sediments M J Johnsson and A Basu Eds vol284 Geological Society of America Special Paper pp 21ndash40Geological Society of America 1993

[15] M R Bhatia and K AW Crook ldquoTrace element characteristicsof graywackes and tectonic setting discrimination of sedimen-tary basinsrdquo Contributions to Mineralogy and Petrology vol 92no 2 pp 181ndash193 1986

[16] P A Floyd and J A Winchester ldquoMagma type and tectonicsetting discrimination using immobile elementsrdquo Earth andPlanetary Science Letters vol 27 no 2 pp 211ndash218 1975


[17] P A Floyd and J A Winchester ldquoIdentification and discrim-ination of altered and metamorphosed volcanic rocks usingimmobile elementsrdquo Chemical Geology vol 21 no 3-4 pp 291ndash306 1978

[18] J A Winchester and P A Floyd ldquoGeochemical magma typediscrimination application to altered and metamorphosedbasic igneous rocksrdquo Earth and Planetary Science Letters vol28 pp 459ndash469 1976

[19] J A Pearce ldquoSources and settings of granitic rocksrdquo Episodesvol 19 no 4 pp 120ndash125 1996

[20] S R Taylor and S M McLennan The Continental Crust ItsComposition and Evolution Blackwell Publishing Oxford UK1985

[21] S M McLennan S R Taylor M T McCulloch and J B May-nard ldquoGeochemical and NdSr isotopic composition of deep-sea turbidites crustal evolution and plate tectonic associationsrdquoGeochimica et Cosmochimica Acta vol 54 no 7 pp 2015ndash20501990

[22] J AHurowitz and SMMcLennan ldquoGeochemistry of Cambro-Ordovician sedimentary rocks of the northeastern UnitedStates Changes in sediment sources at the onset of Taconianorogenesisrdquo Journal of Geology vol 113 no 5 pp 571ndash587 2005

[23] R L Cullers ldquoThe controls on the major and trace elementvariation of shales siltstones and sandstones of Pennsylvanian-Permian age from uplifted continental blocks in Colorado toplatform sediment in Kansas USArdquoGeochimica et Cosmochim-ica Acta vol 58 no 22 pp 4955ndash4972 1994

[24] R L Cullers ldquoThe geochemistry of shales siltstones andsandstones of Pennsylvanian-Permian age Colorado USAimplications for provenance and metamorphic studiesrdquo Lithosvol 51 no 3 pp 181ndash203 2000

[25] R L Cullers and V N Podkovyrov ldquoGeochemistry of theMesoproterozoic Lakhanda shales in Southeastern YakutiaRussia implications for mineralogical and provenance controland recyclingrdquo Precambrian Research vol 104 no 1-2 pp 77ndash93 2000

[26] R L Cullers A Basu and L J Suttner ldquoGeochemical signa-ture of provenance in sand-size material in soils and streamsediments near the Tobacco Root batholith Montana USArdquoChemical Geology vol 70 no 4 pp 335ndash348 1988

[27] K-I Hayashi H Fujisawa H D Holland and H OhmotoldquoGeochemistry of sim19 Ga sedimentary rocks from Northeast-ern Labrador Canadardquo Geochimica et Cosmochimica Acta vol61 no 19 pp 4115ndash4137 1997

[28] S M McLennan W B Nance and S R Taylor ldquoRare earthelement-thorium correlations in sedimentary rocks and thecomposition of the continental crustrdquo Geochimica et Cos-mochimica Acta vol 44 no 11 pp 1833ndash1839 1980

[29] R J PuddephattThePeriodic Table of Elements OxfordUniver-sity Press 1972

[30] H Wakita P Rey and R A Schmitt ldquoAbundances of the 14rare-earth elements and 12 other trace elements in Apollo 12samples Five igneous and one breccia rocks and four soilsrdquo inProceedings of the Second Lunar Science Conference pp 1319ndash1329 Pergamon Press Oxford UK 1971

[31] R L Rudnick ldquoRestites Eu anomalies and the lower continentalcrustrdquoGeochimica et Cosmochimica Acta vol 56 no 3 pp 963ndash970 1992

[32] K C Condie M D Boryta J Liu and X Qian ldquoThe originof khondalites geochemical evidence from the Archean toEarly Proterozoic granulite belt in the North China cratonrdquoPrecambrian Research vol 59 no 3-4 pp 207ndash223 1992

[33] S M McLennan ldquoRare earth elements in sedimentary rocksinfluence of provenance and sedimentary processes Geochem-istry and mineralogy of the rare earth elementsrdquo Reviews inMineralogy and Geochemistry vol 21 pp 169ndash200 1989

[34] S M McLennan and S R Taylor ldquoSedimentary rocks andcrustal evolution tectonic setting and secular trendsrdquo TheJournal of Geology vol 99 no 1 pp 1ndash21 1991

[35] S M McLennan and S Hemming ldquoSamariumneodymiumelemental and isotopic systematics in sedimentary rocksrdquoGeochimica et Cosmochimica Acta vol 56 no 3 pp 887ndash8981992

[36] R L Cullers T Barrett R Carlson and B Robinson ldquoRare-earth element and mineralogic changes in Holocene soil andstream sediment a case study in theWet Mountains ColoradoUSArdquo Chemical Geology vol 63 no 3-4 pp 275ndash297 1987

[37] D J Wronkiewicz and C C Kent ldquoGeochemistry and prove-nance of sediments from the Pongola Supergroup SouthAfricaevidence for a 30-Ga-old continental cratonrdquo Geochimica etCosmochimica Acta vol 53 no 7 pp 1537ndash1549 1989

[38] R L Cullers and J L Graf ldquoRare-earth elements in igneousrocks of the continental crust intermediate and silicic rocks-orepetrogenesisrdquo in Rare Earth Element Geochemistry P Hender-son Ed pp 275ndash316 Elsevier Amsterdam The Netherlands1984

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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Applied ampEnvironmentalSoil Science

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Mining


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GeochemistryHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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Advances in


MineralogyInternational Journal of


MeteorologyAdvances in

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ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014


Geological ResearchJournal of


Geology Advances in


5∘E 6∘E 7∘E 8∘E

0 50 100

(km)

8∘

6∘

5∘

9∘

7∘

4∘

Study areaEocene recent cycle withapproximate coast lines

Albian-Santonian cycleMetamorphic basement complex (precretaceous)VolcanicsCampanian-Paleocene cycle

Figure 1 Generalized and simplified geological map of Niger deltabasin as obtained from httpwwwintechopencom

The maximum extent of the petroleum system coincideswith the boundaries of the province The minimum extentof the system is defined by the areal extent of fields andcontains known resources (cumulative production plusproved reserves) of 345 billion barrels of oil (BBO) 938trillion cubic feet of gas (TCFG) and 149 billion barrels of oilequivalent (BBOE) [6] Currently most of this petroleum isin fields that are onshore or on the continental shelf in watersless than 200 meters deep and occurs primarily in largerelatively simple structures Among the provinces ranked inthe US Geological Surveyrsquos World Energy Assessment [7]the Niger delta province is the twelfth richest in petroleumresources with 22 of the worldrsquos discovered oil and 14of the worldrsquos discovered gas [6]

2 Materials and Methods

21 Sample Collection andAnalysis Twenty-one core sampleswere collected and subjected to inorganic analysis whichincludesmajor oxides trace elements and rare earth elementThe samples are first dried To avoid contamination thesamples are then washed in deionized water and dried againAfter preparation the samples are grinded and pulverizedSample reduction entails comminuting by sieving or crushingand grinding Standard procedure at most laboratories is tosieve soils and sediments to lt75 120583m The samples are thussieved with lt75 120583mThis is because sample preparation mustreduce the sample volume to a size suitable for analysis yetpreserves the bulk geochemical signature of the larger bodyAbout 3 g of the pulverized sample was then packed in asuitable bag and sent to Acme labs Vancouver Canada foranalysis

Oceanic island arc

Discriminant

Passive margin


CIA

Series 1

5040

40

3020

2000

1000

minus10minus20

minus20

minus30minus40

minus40

minus50minus60

minus60minus70minus80

minus80

minus90minus100

minus100

Disc

rimin

ant f

unct

ion2

Figure 2 The plot of discriminant 2 against discriminant 1 thediscriminant function diagram for sandstones (after [8]) showingfields for sandstones from passive continental margins oceanicisland arcs continental island arcs and active continental marginsThe CIA at the centre represents continental island arc

0 4 8 12 16 20

Passive margin


Continental arc

Oceanic arc

0

02

04

06

08

10Ti

O2

()

Fe2O3(total ) + MgO ()

Figure 3 Bivariate plot of TiO2

versus (Fe2

O3

+MgO) diagrams forsandstones (after [8]) The fields are oceanic island arc continentalisland arc active continental margin and passive margins

3 Results

31 Tectonic Settings of Niger Delta Based on Major OxidesSee Table 1 and Figures 2 and 3

32 Results andDiscussion Knowledge of the tectonic settingof a basin is important for the exploration of petroleum andother resources as well as for paleogeography Some authorshave described the usefulness of major element geochemistryof sedimentary rocks to infer tectonic setting based ondiscrimination diagrams (eg [8 9]) This is because platetectonics processes impart distinctive geochemical signa-ture to sediments in two separate ways Firstly tectonicenvironments have distinctive provenance characteristics andsecondly they are characterized by distinctive sedimentaryprocess

Bhatia [8] proposed major element geochemical criteriato discriminate plate tectonic settings for sedimentary basinsfrom identified well-defined sandstone suites He compiled















2+




2O +

7510P2O5+ 0303


2minus




2O +

7244P2O5+ 4357 (after [8])



2O3+MgO Al

2O3SiO2

K2ONa

2O and Al

2O3(CaO + Na



00

01

10

100

1000

10000

540 640 740 840 940 1040

Oceanic islandarc



672 03

SiO2

Log

K 2ON

a 2O


ONa2

O-SiO2



2versus (Fe

2O3+ MgO)



2ONa2O-SiO

2dis-






2O3SiO2 K2ONa

2O and Fe

2O3+MgO



2is


2 Fe2O MgO

Na2O and K

2O all to Al




2O3+


2Ominus

1224K2O minus 909

minus4 minus28

5

19

6

0

minus8

minus92


Mafic

Intermediate


Disc

rimin

ant f

unct

ion2

Quartzoze

ProvenanceFelsic



2O3minus


1475Na2O + 1426K

2O minus 6861



2O3


2O3







diagrams Fe2O3 MnO

2 MgO TiO

2 FeO P

2O5 and K

2O










Intermediate

Felsic(plutonic)

Maficplutonic

MgO(MgO + Al2O3)

MgO

(M

gO+

Al 2

O3)

TiO +V2O3

00000

00000

01000

02000

03000

04000

05000

06000

07000

08000

09000

10000

50000

100000

150000

200000

250000

300000


+V2

O3

versusMgO(MgO+Al2

O3



2-NbY



2O + K

2O) and ZrTiO








02468

10121416

0 02 04 06 08 10

5

10

15


02468

10121416

0 1 2 3 4 502468

1012141618

0 2 4 6 8 10

Iron II oxide FeO

02468

1012141618

0 2 4 6 8 1002468

10121416

0 005 01 015 02

02468

1012141618

0 001 002 003 004 005 006 007 00802468

10121416

0 1 2 3 4 5 6 7 8

02468

10121416

0 05 1 15 2 25 3 35

Calcium oxide CaO

00 05 10 15 20

Titanium oxide TiO2

y = 15419x minus 00404R2 = 08463

y = 29156x + 5628

R2 = 00656

Potassium oxide K2O

y = 0948x + 43228

R2 = 00808

y = 20126x minus 00903

R2 = 0658


y = 181x minus 00903

R2 = 0658 R2 = 03403


y = 56849x + 21434


y = 18581x + 18806

R2 = 04864

Sodium oxide Na2O

y = minus01004x + 69868

R2 = 00025

0 20 40 60 80 100 120

1614121086420

minus2

y = minus16841x + 81044

R2 = 00647 R2 = 07614

Silica oxide SiO2

y = minus04227x + 40228


O3


O3


2









0

05

1

15

2

25

3

0 10 20 30 40 50

ThS

c

ZrSc





1 0

0

02

02

04

04

04

06

06

06

08

08

08

10

1 La

Th Sc

A

B

C

D

02


A

B

C

D

Th

Sc Zr10


Th

Co Zr10A

B

CD

middot


100

10

01

00001 01 1 10

LaSc

ThC

o

Basicrocks

Felsic














0123456789

10

0 2 4 6 8 10

LaTh

More mafic

More felsic

ThYb















00000

05000

10000

15000

20000

25000







15

1

05

0

minus05

minus1

minus15

minus2









Eu

Eulowast=


(1)


EuEulowast= radic

EunSnn times Gdn

(2)








310 (GdYb)119873



4 Conclusion











References










2

content andK2

ONa2









































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in















2+




2O +

7510P2O5+ 0303


2minus




2O +

7244P2O5+ 4357 (after [8])



2O3+MgO Al

2O3SiO2

K2ONa

2O and Al

2O3(CaO + Na



00

01

10

100

1000

10000

540 640 740 840 940 1040

Oceanic islandarc



672 03

SiO2

Log

K 2ON

a 2O


ONa2

O-SiO2



2versus (Fe

2O3+ MgO)



2ONa2O-SiO

2dis-






2O3SiO2 K2ONa

2O and Fe

2O3+MgO



2is


2 Fe2O MgO

Na2O and K

2O all to Al




2O3+


2Ominus

1224K2O minus 909

minus4 minus28

5

19

6

0

minus8

minus92


Mafic

Intermediate


Disc

rimin

ant f

unct

ion2

Quartzoze

ProvenanceFelsic



2O3minus


1475Na2O + 1426K

2O minus 6861



2O3


2O3







diagrams Fe2O3 MnO

2 MgO TiO

2 FeO P

2O5 and K

2O










Intermediate

Felsic(plutonic)

Maficplutonic

MgO(MgO + Al2O3)

MgO

(M

gO+

Al 2

O3)

TiO +V2O3

00000

00000

01000

02000

03000

04000

05000

06000

07000

08000

09000

10000

50000

100000

150000

200000

250000

300000


+V2

O3

versusMgO(MgO+Al2

O3



2-NbY



2O + K

2O) and ZrTiO








02468

10121416

0 02 04 06 08 10

5

10

15


02468

10121416

0 1 2 3 4 502468

1012141618

0 2 4 6 8 10

Iron II oxide FeO

02468

1012141618

0 2 4 6 8 1002468

10121416

0 005 01 015 02

02468

1012141618

0 001 002 003 004 005 006 007 00802468

10121416

0 1 2 3 4 5 6 7 8

02468

10121416

0 05 1 15 2 25 3 35

Calcium oxide CaO

00 05 10 15 20

Titanium oxide TiO2

y = 15419x minus 00404R2 = 08463

y = 29156x + 5628

R2 = 00656

Potassium oxide K2O

y = 0948x + 43228

R2 = 00808

y = 20126x minus 00903

R2 = 0658


y = 181x minus 00903

R2 = 0658 R2 = 03403


y = 56849x + 21434


y = 18581x + 18806

R2 = 04864

Sodium oxide Na2O

y = minus01004x + 69868

R2 = 00025

0 20 40 60 80 100 120

1614121086420

minus2

y = minus16841x + 81044

R2 = 00647 R2 = 07614

Silica oxide SiO2

y = minus04227x + 40228


O3


O3


2









0

05

1

15

2

25

3

0 10 20 30 40 50

ThS

c

ZrSc





1 0

0

02

02

04

04

04

06

06

06

08

08

08

10

1 La

Th Sc

A

B

C

D

02


A

B

C

D

Th

Sc Zr10


Th

Co Zr10A

B

CD

middot


100

10

01

00001 01 1 10

LaSc

ThC

o

Basicrocks

Felsic














0123456789

10

0 2 4 6 8 10

LaTh

More mafic

More felsic

ThYb















00000

05000

10000

15000

20000

25000







15

1

05

0

minus05

minus1

minus15

minus2









Eu

Eulowast=


(1)


EuEulowast= radic

EunSnn times Gdn

(2)








310 (GdYb)119873



4 Conclusion











References










2

content andK2

ONa2









































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in


00

01

10

100

1000

10000

540 640 740 840 940 1040

Oceanic islandarc



672 03

SiO2

Log

K 2ON

a 2O


ONa2

O-SiO2



2versus (Fe

2O3+ MgO)



2ONa2O-SiO

2dis-






2O3SiO2 K2ONa

2O and Fe

2O3+MgO



2is


2 Fe2O MgO

Na2O and K

2O all to Al




2O3+


2Ominus

1224K2O minus 909

minus4 minus28

5

19

6

0

minus8

minus92


Mafic

Intermediate


Disc

rimin

ant f

unct

ion2

Quartzoze

ProvenanceFelsic



2O3minus


1475Na2O + 1426K

2O minus 6861



2O3


2O3







diagrams Fe2O3 MnO

2 MgO TiO

2 FeO P

2O5 and K

2O










Intermediate

Felsic(plutonic)

Maficplutonic

MgO(MgO + Al2O3)

MgO

(M

gO+

Al 2

O3)

TiO +V2O3

00000

00000

01000

02000

03000

04000

05000

06000

07000

08000

09000

10000

50000

100000

150000

200000

250000

300000


+V2

O3

versusMgO(MgO+Al2

O3



2-NbY



2O + K

2O) and ZrTiO








02468

10121416

0 02 04 06 08 10

5

10

15


02468

10121416

0 1 2 3 4 502468

1012141618

0 2 4 6 8 10

Iron II oxide FeO

02468

1012141618

0 2 4 6 8 1002468

10121416

0 005 01 015 02

02468

1012141618

0 001 002 003 004 005 006 007 00802468

10121416

0 1 2 3 4 5 6 7 8

02468

10121416

0 05 1 15 2 25 3 35

Calcium oxide CaO

00 05 10 15 20

Titanium oxide TiO2

y = 15419x minus 00404R2 = 08463

y = 29156x + 5628

R2 = 00656

Potassium oxide K2O

y = 0948x + 43228

R2 = 00808

y = 20126x minus 00903

R2 = 0658


y = 181x minus 00903

R2 = 0658 R2 = 03403


y = 56849x + 21434


y = 18581x + 18806

R2 = 04864

Sodium oxide Na2O

y = minus01004x + 69868

R2 = 00025

0 20 40 60 80 100 120

1614121086420

minus2

y = minus16841x + 81044

R2 = 00647 R2 = 07614

Silica oxide SiO2

y = minus04227x + 40228


O3


O3


2









0

05

1

15

2

25

3

0 10 20 30 40 50

ThS

c

ZrSc





1 0

0

02

02

04

04

04

06

06

06

08

08

08

10

1 La

Th Sc

A

B

C

D

02


A

B

C

D

Th

Sc Zr10


Th

Co Zr10A

B

CD

middot


100

10

01

00001 01 1 10

LaSc

ThC

o

Basicrocks

Felsic














0123456789

10

0 2 4 6 8 10

LaTh

More mafic

More felsic

ThYb















00000

05000

10000

15000

20000

25000







15

1

05

0

minus05

minus1

minus15

minus2









Eu

Eulowast=


(1)


EuEulowast= radic

EunSnn times Gdn

(2)








310 (GdYb)119873



4 Conclusion











References










2

content andK2

ONa2









































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in




Intermediate

Felsic(plutonic)

Maficplutonic

MgO(MgO + Al2O3)

MgO

(M

gO+

Al 2

O3)

TiO +V2O3

00000

00000

01000

02000

03000

04000

05000

06000

07000

08000

09000

10000

50000

100000

150000

200000

250000

300000


+V2

O3

versusMgO(MgO+Al2

O3



2-NbY



2O + K

2O) and ZrTiO








02468

10121416

0 02 04 06 08 10

5

10

15


02468

10121416

0 1 2 3 4 502468

1012141618

0 2 4 6 8 10

Iron II oxide FeO

02468

1012141618

0 2 4 6 8 1002468

10121416

0 005 01 015 02

02468

1012141618

0 001 002 003 004 005 006 007 00802468

10121416

0 1 2 3 4 5 6 7 8

02468

10121416

0 05 1 15 2 25 3 35

Calcium oxide CaO

00 05 10 15 20

Titanium oxide TiO2

y = 15419x minus 00404R2 = 08463

y = 29156x + 5628

R2 = 00656

Potassium oxide K2O

y = 0948x + 43228

R2 = 00808

y = 20126x minus 00903

R2 = 0658


y = 181x minus 00903

R2 = 0658 R2 = 03403


y = 56849x + 21434


y = 18581x + 18806

R2 = 04864

Sodium oxide Na2O

y = minus01004x + 69868

R2 = 00025

0 20 40 60 80 100 120

1614121086420

minus2

y = minus16841x + 81044

R2 = 00647 R2 = 07614

Silica oxide SiO2

y = minus04227x + 40228


O3


O3


2









0

05

1

15

2

25

3

0 10 20 30 40 50

ThS

c

ZrSc





1 0

0

02

02

04

04

04

06

06

06

08

08

08

10

1 La

Th Sc

A

B

C

D

02


A

B

C

D

Th

Sc Zr10


Th

Co Zr10A

B

CD

middot


100

10

01

00001 01 1 10

LaSc

ThC

o

Basicrocks

Felsic














0123456789

10

0 2 4 6 8 10

LaTh

More mafic

More felsic

ThYb















00000

05000

10000

15000

20000

25000







15

1

05

0

minus05

minus1

minus15

minus2









Eu

Eulowast=


(1)


EuEulowast= radic

EunSnn times Gdn

(2)








310 (GdYb)119873



4 Conclusion











References










2

content andK2

ONa2









































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in


02468

10121416

0 02 04 06 08 10

5

10

15


02468

10121416

0 1 2 3 4 502468

1012141618

0 2 4 6 8 10

Iron II oxide FeO

02468

1012141618

0 2 4 6 8 1002468

10121416

0 005 01 015 02

02468

1012141618

0 001 002 003 004 005 006 007 00802468

10121416

0 1 2 3 4 5 6 7 8

02468

10121416

0 05 1 15 2 25 3 35

Calcium oxide CaO

00 05 10 15 20

Titanium oxide TiO2

y = 15419x minus 00404R2 = 08463

y = 29156x + 5628

R2 = 00656

Potassium oxide K2O

y = 0948x + 43228

R2 = 00808

y = 20126x minus 00903

R2 = 0658


y = 181x minus 00903

R2 = 0658 R2 = 03403


y = 56849x + 21434


y = 18581x + 18806

R2 = 04864

Sodium oxide Na2O

y = minus01004x + 69868

R2 = 00025

0 20 40 60 80 100 120

1614121086420

minus2

y = minus16841x + 81044

R2 = 00647 R2 = 07614

Silica oxide SiO2

y = minus04227x + 40228


O3


O3


2









0

05

1

15

2

25

3

0 10 20 30 40 50

ThS

c

ZrSc





1 0

0

02

02

04

04

04

06

06

06

08

08

08

10

1 La

Th Sc

A

B

C

D

02


A

B

C

D

Th

Sc Zr10


Th

Co Zr10A

B

CD

middot


100

10

01

00001 01 1 10

LaSc

ThC

o

Basicrocks

Felsic














0123456789

10

0 2 4 6 8 10

LaTh

More mafic

More felsic

ThYb















00000

05000

10000

15000

20000

25000







15

1

05

0

minus05

minus1

minus15

minus2









Eu

Eulowast=


(1)


EuEulowast= radic

EunSnn times Gdn

(2)








310 (GdYb)119873



4 Conclusion











References










2

content andK2

ONa2









































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in


0

05

1

15

2

25

3

0 10 20 30 40 50

ThS

c

ZrSc





1 0

0

02

02

04

04

04

06

06

06

08

08

08

10

1 La

Th Sc

A

B

C

D

02


A

B

C

D

Th

Sc Zr10


Th

Co Zr10A

B

CD

middot


100

10

01

00001 01 1 10

LaSc

ThC

o

Basicrocks

Felsic














0123456789

10

0 2 4 6 8 10

LaTh

More mafic

More felsic

ThYb















00000

05000

10000

15000

20000

25000







15

1

05

0

minus05

minus1

minus15

minus2









Eu

Eulowast=


(1)


EuEulowast= radic

EunSnn times Gdn

(2)








310 (GdYb)119873



4 Conclusion











References










2

content andK2

ONa2









































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in









0123456789

10

0 2 4 6 8 10

LaTh

More mafic

More felsic

ThYb















00000

05000

10000

15000

20000

25000







15

1

05

0

minus05

minus1

minus15

minus2









Eu

Eulowast=


(1)


EuEulowast= radic

EunSnn times Gdn

(2)








310 (GdYb)119873



4 Conclusion











References










2

content andK2

ONa2









































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in












00000

05000

10000

15000

20000

25000







15

1

05

0

minus05

minus1

minus15

minus2









Eu

Eulowast=


(1)


EuEulowast= radic

EunSnn times Gdn

(2)








310 (GdYb)119873



4 Conclusion











References










2

content andK2

ONa2









































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in


00000

05000

10000

15000

20000

25000







15

1

05

0

minus05

minus1

minus15

minus2









Eu

Eulowast=


(1)


EuEulowast= radic

EunSnn times Gdn

(2)








310 (GdYb)119873



4 Conclusion











References










2

content andK2

ONa2









































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in







310 (GdYb)119873



4 Conclusion











References










2

content andK2

ONa2









































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in









References










2

content andK2

ONa2









































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in

































Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in










Volume 2014

Mining


Journal of



Geophysics







Journal of




Advances in











Geology Advances in

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