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Econ. Environ. Geol. 2023; 56(3): 259-275

Published online June 30, 2023

https://doi.org/10.9719/EEG.2023.56.3.259

© THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY

Geochemistry and Petrogenesis of Pan-african Granitoids in Kaiama, North Central, Nigeria

Aliyu Ohiani Umaru1,4,*, Olugbenga Okunlola2, Umaru Adamu Danbatta3, Olusegun G. Olisa5

1Pan African University of Life and Earth Science Institute including (Health and Agriculture), University of Ibadan, Oyo state, Nigeria
2Department of Geology, University of Ibadan, Oyo state, Nigeria
3Department of Geology, Ahmadu Bello University, Kaduna state, Nigeria
4Department of Geology, University of Maiduguri, Borno State, Nigeria
5Department of Earth Sciences, Olabisi Onabanjo University, Ago Iwoye, Ogun state, Nigeria

Correspondence to : *umaru.aliyu@paulesi.org.ng

Received: March 30, 2023; Revised: May 7, 2023; Accepted: May 16, 2023

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided original work is properly cited.

Abstract

Pan African granitoids of Kaiama is comprised of K-feldspar rich granites, porphyritic granites, and granitic gneiss that are intruded by quartz veins and aplitic veins and dykes which trend NE-SW. In order to establish the geochemical signatures, petrogenesis, and tectonic settings of the lithological units, petrological, petrographical, and geochemical studies was carried out. Petrographic analysis reveals that the granitoids are dominantly composed of quartz, plagioclase feldspar, biotite, and k-feldspar with occasional muscovites, sericite, and opaque minerals that constitute very low proportion. Major, trace, and rare earth elements geochemical data reveal that the rocks have moderate to high silica (SiO2=63-79.7%) and alumina (Al2O3=11.85-16.15) contents that correlate with the abundance of quartz, feldspars, and biotite. The rocks are calc-alkaline, peraluminous (ASI=1.0-<1.2), and S-type granitoids sourced by melting of pre-existing metasedimentary or sedimentary rocks containing Al, Na, and K oxides. They plot dominantly in the WPG and VAG fields suggesting emplacement in a post-collisional tectonic setting. On a multi-element variation diagram, the granitoids show depletion in Ba, K, P, Rb, and Ti while enrichment was observed for Th, U, Nd, Pb and Sm. Their rare-earth elements pattern is characterized by moderate fractionation ((La/Yb)N=0.52-38.24) and pronounced negative Eu-anomaly (Eu/Eu*=0.02-1.22) that points to the preservation of plagioclase from the source magma. Generally, the geochemical features of the granitoids show that they were derived by the partial melting of crustal rocks with some input from greywacke and pelitic materials in a typical post-collisional tectonic setting.

Keywords granitoids, peraluminous, tectonic setting, petrography, partial melting

Article

Research Paper

Econ. Environ. Geol. 2023; 56(3): 259-275

Published online June 30, 2023 https://doi.org/10.9719/EEG.2023.56.3.259

Copyright © THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY.

Geochemistry and Petrogenesis of Pan-african Granitoids in Kaiama, North Central, Nigeria

Aliyu Ohiani Umaru1,4,*, Olugbenga Okunlola2, Umaru Adamu Danbatta3, Olusegun G. Olisa5

1Pan African University of Life and Earth Science Institute including (Health and Agriculture), University of Ibadan, Oyo state, Nigeria
2Department of Geology, University of Ibadan, Oyo state, Nigeria
3Department of Geology, Ahmadu Bello University, Kaduna state, Nigeria
4Department of Geology, University of Maiduguri, Borno State, Nigeria
5Department of Earth Sciences, Olabisi Onabanjo University, Ago Iwoye, Ogun state, Nigeria

Correspondence to:*umaru.aliyu@paulesi.org.ng

Received: March 30, 2023; Revised: May 7, 2023; Accepted: May 16, 2023

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided original work is properly cited.

Abstract

Pan African granitoids of Kaiama is comprised of K-feldspar rich granites, porphyritic granites, and granitic gneiss that are intruded by quartz veins and aplitic veins and dykes which trend NE-SW. In order to establish the geochemical signatures, petrogenesis, and tectonic settings of the lithological units, petrological, petrographical, and geochemical studies was carried out. Petrographic analysis reveals that the granitoids are dominantly composed of quartz, plagioclase feldspar, biotite, and k-feldspar with occasional muscovites, sericite, and opaque minerals that constitute very low proportion. Major, trace, and rare earth elements geochemical data reveal that the rocks have moderate to high silica (SiO2=63-79.7%) and alumina (Al2O3=11.85-16.15) contents that correlate with the abundance of quartz, feldspars, and biotite. The rocks are calc-alkaline, peraluminous (ASI=1.0-<1.2), and S-type granitoids sourced by melting of pre-existing metasedimentary or sedimentary rocks containing Al, Na, and K oxides. They plot dominantly in the WPG and VAG fields suggesting emplacement in a post-collisional tectonic setting. On a multi-element variation diagram, the granitoids show depletion in Ba, K, P, Rb, and Ti while enrichment was observed for Th, U, Nd, Pb and Sm. Their rare-earth elements pattern is characterized by moderate fractionation ((La/Yb)N=0.52-38.24) and pronounced negative Eu-anomaly (Eu/Eu*=0.02-1.22) that points to the preservation of plagioclase from the source magma. Generally, the geochemical features of the granitoids show that they were derived by the partial melting of crustal rocks with some input from greywacke and pelitic materials in a typical post-collisional tectonic setting.

Keywords granitoids, peraluminous, tectonic setting, petrography, partial melting

    Fig 1.

    Figure 1.(A) Geological sketch map of Nigeria, showing the different lithostratigraphic components, adapted from NGSA (2004), (B). Geological map of Kwara state (adapted from NGSA, 2004), the location of the study area is in a black rectangle, (C) Geological map of the study area (Kaiama) showing the granitoids (adapted from Umaru et al., 2022).
    Economic and Environmental Geology 2023; 56: 259-275https://doi.org/10.9719/EEG.2023.56.3.259

    Fig 2.

    Figure 2.Generalized geological map of Nigeria within the framework of the Geology of west Africa (Modified from Wright, 1985).
    Economic and Environmental Geology 2023; 56: 259-275https://doi.org/10.9719/EEG.2023.56.3.259

    Fig 3.

    Figure 3.A) Low-lying outcrop of porphyritic granite B) Close view of porphyritic granite showing phenocryst of feldspar on fine groundmass of quartz and biotite (long axis=4cm; short axis= 2.5cm).
    Economic and Environmental Geology 2023; 56: 259-275https://doi.org/10.9719/EEG.2023.56.3.259

    Fig 4.

    Figure 4.Photomicrograph of porphyritic granite in Cross Polarized Light (CPL) showing Qz=Quartz, Pl=Plagioclase, Se=Sericite, B=Biotite, Kfs=Alkali feldspar, and Ms=muscovite.
    Economic and Environmental Geology 2023; 56: 259-275https://doi.org/10.9719/EEG.2023.56.3.259

    Fig 5.

    Figure 5.A) Low lying outcrop of granite gneiss with porphyroblast of plagioclase feldspar, B) granite gneiss showing mafic enclave inclusion.
    Economic and Environmental Geology 2023; 56: 259-275https://doi.org/10.9719/EEG.2023.56.3.259

    Fig 6.

    Figure 6.Photomicrograph of granite gneiss showing Pl=plagioclase, Qz=quartz, Mc=microcline and B=biotite.
    Economic and Environmental Geology 2023; 56: 259-275https://doi.org/10.9719/EEG.2023.56.3.259

    Fig 7.

    Figure 7.Low lying outcrop of K-feldspar rich granite around Kaiama settlement.
    Economic and Environmental Geology 2023; 56: 259-275https://doi.org/10.9719/EEG.2023.56.3.259

    Fig 8.

    Figure 8.Photomicrograph of K-feldspar rich granite showing Pl=Plagioclase, Mc=Microcline, Qz=Quartz and B=Biotite
    Economic and Environmental Geology 2023; 56: 259-275https://doi.org/10.9719/EEG.2023.56.3.259

    Fig 9.

    Figure 9.Harker diagram for K-feldspar rich granites, Porphyritic granites, and Granite gneiss showing the variation of SiO2 with some selected major elements. (Note: red squares are K-feldspar rich granites, blue triangles are porphyritic granites and green diamonds are granite gneiss).
    Economic and Environmental Geology 2023; 56: 259-275https://doi.org/10.9719/EEG.2023.56.3.259

    Fig 10.

    Figure 10.Harker variation diagram of K-feldspar rich granites, Porphyritic granites, and Granite gneiss showing SiO2 variation with selected trace elements.
    Economic and Environmental Geology 2023; 56: 259-275https://doi.org/10.9719/EEG.2023.56.3.259

    Fig 11.

    Figure 11.Primitive mantle normalized multi-element variation plot (Sun and McDonough, 1989) for the granitoids.
    Economic and Environmental Geology 2023; 56: 259-275https://doi.org/10.9719/EEG.2023.56.3.259

    Fig 12.

    Figure 12.Chondrite-normalized rare earth elements (REE) plot of the granitoids with normalization values after Boynton, (1984).
    Economic and Environmental Geology 2023; 56: 259-275https://doi.org/10.9719/EEG.2023.56.3.259

    Fig 13.

    Figure 13.Na2O+K2O versus SiO2 chemical classification diagram for the granitoids (after Middlemost, 1994).
    Economic and Environmental Geology 2023; 56: 259-275https://doi.org/10.9719/EEG.2023.56.3.259

    Fig 14.

    Figure 14.Normative mineral composition of the granitoids after (O’Connor, 1965).
    Economic and Environmental Geology 2023; 56: 259-275https://doi.org/10.9719/EEG.2023.56.3.259

    Fig 15.

    Figure 15.K2O+Na2O versus SiO2 plot of MacDonald and Katsura (1964), showing the sub alkaline compositions of the rocks.
    Economic and Environmental Geology 2023; 56: 259-275https://doi.org/10.9719/EEG.2023.56.3.259

    Fig 16.

    Figure 16.AFM classification plot after Irvine and Barager, (1971) Alphabets stands for (A: total alkalis, F: total Iron, and M: MgO).
    Economic and Environmental Geology 2023; 56: 259-275https://doi.org/10.9719/EEG.2023.56.3.259

    Fig 17.

    Figure 17.A/NK against A/CNK diagram after Shand, (1943) discriminating the granitoids as S-type and of peraluminous compositions.
    Economic and Environmental Geology 2023; 56: 259-275https://doi.org/10.9719/EEG.2023.56.3.259

    Fig 18.

    Figure 18.Molar CaO/FeOt+MgO vs Al2O3/FeOt+MgO of granites in the study area (after Alther et al.,2000).
    Economic and Environmental Geology 2023; 56: 259-275https://doi.org/10.9719/EEG.2023.56.3.259

    Fig 19.

    Figure 19.FeOt versus MgO diagram after Zorpi et al., (1989) for
    the granitoids of the study area.
    Economic and Environmental Geology 2023; 56: 259-275https://doi.org/10.9719/EEG.2023.56.3.259

    Fig 20.

    Figure 20.a). Tectonic setting discrimination of the granitoids on an Rb versus (Y + Nb) plot after Pearce et al., (1984). VAG stands for volcanic arc granites; ORG stands for oceanic ridge granites; WPG stands for within plate granites; Syn-COLG stands for syn-collision granites. b). Tectonic setting discrimination of the granitoids on an Nb versus Y plot after Pearce et al., (1984).
    Economic and Environmental Geology 2023; 56: 259-275https://doi.org/10.9719/EEG.2023.56.3.259

    Table 1 . Major elements oxides (wt%), trace and rare earth elements (ppm) composition of granitoids in Kaiama area.

    Sample NoK-feldspar rich granitesPorphyritic granitesGranite gneiss
    Oxides (%)P1P2P3P4P5PG1PG2PG3PG4PG5PG6PG7G1G2G3G4G5G6
    SiO278.876.679.777.376.872.47373.171.972.272.573.868.269.267.469.26364.7
    Al2O312.2513.311.8512.412.3513.1513.713.813.31413.113.815.414.214.7515.1516.116.15
    Fe2O30.951.361.041.241.282.061.842.182.0622.12.073.614.954.943.776.135.86
    CaO0.140.180.510.50.151.161.240.951.241.111.30.832.382.132.022.422.963.2
    MgO0.030.020.060.020.020.260.240.270.280.250.280.270.780.980.790.61.21.12
    Na2O3.823.964.064.194.123.483.753.723.643.853.763.533.853.113.153.213.313.43
    K2O4.995.153.744.434.544.494.54.54.314.5444.533.394.284.854.774.543.93
    TiO20.050.030.050.040.030.190.180.220.210.190.220.20.540.720.710.430.980.86
    MnO0.040.050.020.020.020.030.030.040.040.040.040.040.050.060.070.050.080.08
    P2O5BDL0.01BDLBDLBDL0.040.040.040.060.050.050.060.20.270.290.10.350.35
    LOI0.510.510.480.460.440.810.830.540.930.381.110.821.060.50.320.440.470.55
    Total101.5101.1101.5100.699.798.1699.4499.4798.0798.7198.55100.0699.55100.5199.42100.2399.29100.38
    K/N1.31.30.921.051.11.291.21.211.181.171.061.280.881.371.531.481.371.14
    N+K8.819.117.88.628.667.978.258.227.958.397.768.067.247.3987.987.857.36
    A/CNK1.361.431.421.361.41.441.441.51.441.471.441.551.61.491.471.451.481.52
    K0.410.430.310.370.380.370.370.370.360.380.330.380.280.360.40.40.380.33
    K/Rb8.508.1912.357.887.9315.2214.6814.8014.2813.7014.1014.8416.0917.3020.0521.2221.6521.49
    Ba/Rb0.260.080.670.090.062.592.623.242.862.462.533.143.413.344.603.406.927.13
    Rb/Sr33.9459.665.6947.3750.421.811.691.591.661.921.651.720.630.870.881.340.660.53
    Trace element concentration (ppm)
    AuBDLBDLBDLBDLBDLBDLBDLBDLBDLBDLBDLBDLBDLBDLBDLBDLBDLBDL
    Co456339787151684440475138555993696372
    Ni412113255154774464
    Cu450323119213282771378715
    Zn5165376273524953585551496586897010493
    As59<55<55<5<5<59<5<5<5<5<5<5<5<5
    Rb482525251469479243252250252276234256174208199.5188.5175.5153.5
    Sr14.28.844.19.99.5134.5149.5157151.5144141.5149275240227140.5267287
    Sn11.17.989.310.36.16.46.67.610.36.45.72.92.63.73.13.22.7
    Ba123.542.5167.540.730.863066181072068059280559469491764112151095
    Pb616845605834323233383232232534232623
    Ta7.36.27.66.57.23.34.14.23.34.54.13.41.111.61.621.9
    Y122.514474.8114118.540.440.462.339.149.348.678.323.43326.824.227.225.3
    Nb61.24850.357.249.422.42327.721.722.325.123.215.519.922.116.5525.121.2
    Hf5.996.244.75.985.915.755.476.125.545.537.215.617.6710.59.517.478.49.93
    Zr11610779115115188164185182164230176293412389282363414
    Th48.839.429.143.644.617.419.121.421.226.82319.7513.1522.56.1622.56.152.03
    V<5<5<5<5<510101314121311405241346260
    Ga31.235.828.635.53424.925.425.423.925.124.524.724.722.122.42124.523.6
    Mo27<114<11<11<11<1111<111
    Cs4.616.624.826.435.737.197.047.217.5329.58.037.21.232.943.184.533.242.64
    Rare earth elements concentration (ppm)
    La11.913.59.514.611.834.432.467.736.639.165.256.25997.546.595.331.929.2
    Ce4638.222.440.733.270.563.912175.980.713097.912220499.819768.962.7
    Pr4.695.753.1764.927.877.26158.38.9713.6513.3513.32311.521.78.768.03
    Nd2127.41427.623.730.625.65532.534.54850.945.778.542.674.834.732
    Sm7.4111.45.1511.759.876.446.0510.76.517.319.3212.058.313.657.9212.557.396.62
    Eu0.130.080.270.090.10.720.791.150.730.760.841.291.721.631.981.382.352.6
    Gd9.8115.857.2514.613.056.35.5710.355.827.197.512.36.4810.555.988.896.346.37
    Tb1.992.841.692.82.390.980.961.790.991.261.282.130.991.381.041.131.020.92
    Dy16.821.813.219.418.156.515.8510.055.897.47.6412.54.766.785.855.445.14.76
    Ho3.524.582.673.63.691.271.332.111.261.591.742.620.861.250.990.961.061.02
    Er12.1514.858.5611.5512.254.234.016.013.834.984.847.932.493.372.542.332.832.54
    Tm2.092.441.391.731.930.610.660.980.570.770.841.280.290.420.350.310.330.3
    Yb14.917.49.411.513.54.234.126.423.785.225.287.781.762.432.11.682.031.95
    Lu2.032.331.161.731.960.510.650.910.620.730.861.110.240.370.340.270.280.28
    Rb/Sr33.9459.665.6947.3750.421.811.691.591.661.921.651.720.630.870.881.340.660.53
    Rb/Ba3.912.351.511.5215.550.390.380.310.350.410.40.320.290.30.220.290.140.14
    Y/Nb231.491.992.41.81.762.251.82.211.943.381.511.661.211.461.081.19
    K/Rb0.0010.0010.0010.0010.0010.0020.0010.0010.0010.0010.0010.0010.0020.0020.0020.0020.0020.002
    (Ce/Yb) N0.80.570.620.920.644.314.014.885.1946.373.2517.9321.1712.2930.338.788.32
    (Ce/Sm) N1.50.811.050.840.812.642.552.732.812.663.371.963.553.613.043.792.252.29
    (Gd/Yb) N0.530.740.621.020.781.21.091.31.241.111.151.282.973.52.34.272.522.64
    (La/Yb) N0.540.520.680.860.595.485.37.116.535.058.334.8722.627.0514.9338.2410.5910.1
    (La/Sm) N1.010.741.160.780.753.363.373.983.543.364.43.934.474.493.694.782.722.77
    Eu/Eu*0.050.020.140.020.030.350.420.330.360.320.310.320.720.420.880.41.051.22
    ⅀REE154.4178.499.8167.6150.5175.1159.1309.1183.3200.4296.9279.3267.8444.8229.4423.7172.9159.2

    KSEEG
    Apr 30, 2024 Vol.57 No.2, pp. 107~280

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