Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

M. Aslam ¹, M. Arora ², R. C. Tewari ³

Affiliations
1 Department of Geology, Aligarh Muslim University, Aligarh, IN
2 Geochemistry Section, NGRI, Uppal Road, Hyderabad, IN
3 Department of Geology, D. S. College, Aligarh, IN

Abstract

Heavy mineral analysis of the Barakar Sandstone from a drill core (117 m) from the Moher-Subbasin of the Singrauli coalfield shows relative abundance of epidote, zircon and rutile in the finer (.088-.074 mm) and garnet, muscovite and staurolite in the coarser (0.177-0.149 mm) fraction. Stratigraphically, the heavy species do not exhibit marked variation in their relative abundance, though garnet forms the bulk of the heavy crop at 94 m depth.

The study indicates that basic and acid igneous rocks, low to medium and high-grade metamorphic rocks, and metasedimentary rocks to the south and southeast of the study area, probably the Manpat ridge, supplied the bulk of the sediment debris during the early Permian Barakar times.

Keywords

Sedimentology, Barakar Sandstone, Singrauli, Gondwana.

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M. Arora ¹, S. M. Naqvi ¹

Affiliations
1 National Geophysical Research Institute, Hyderabad 500 007, IN

Abstract

Sandy matrix of QPC of Archaean Bababudan schist belt is distinguished, by the abundance of well rounded detrital pyrite, uraninite, chromite, zircon, rutile and micas, and clasts of fuchsite quartzite. Presence of detrital pyrite and uraninite in mature arenites deposited during the initial stage of shallow stable basin, indicate the anoxic nature of ambient atmosphere. Compositional characteristics such as the abundance of Al₂O₃, K₂O, MgO, Cr, Ni, Co, Zr, V, Sc, Rb, Sr and ∑REE reveal that only restites could survive intense chemical weathering and strong hydrodynamic action. High to moderately fractionated REE patterns (LaN/LuN-10) with essentially negative Eu anomalies of the matrix of QPC, typically resemble the Archaean arenitic and pelitic rocks. These characlcristics of the QPC indicate removal of mafic-ultramafic and other unstable constituents of provenance to the deeper part of the basin. Silicic and other resistive part of provenance were deposited on the margin of the basin. Geochemical parameters of these rocks show that initial anoxic stage was changed to rhythmically oxidizing environment, in which very thick oxide facies of BIF got precipitated. Stable tectonic condition was changed to active margin setting, in which immature Kaldurga polymictic conglomerate (KCM) with greywacke matrix was deposited. Available data on various rock types of the Bababudan basin, demonstrate that the composition of atmosphere changes in tectonic setting and depositional environment resulted in the deposition of sediments of divergent type in the basin at various stratigraphic levels.

Keywords

Geochemistry, Arenites, Banded Iron Formation, Bababudan Belt, Karnataka.

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R. M. K. Khan ¹, S. Nirmal Charan ¹, M. Arora ¹, S. M. Naqvi ¹

Affiliations
1 National Geophysical Research Institute, Hyderabad-500007, IN

Abstract

The iron-formations ofKudremukh mainly contain magnetite, recrystallized chert, gruneritecu mmingtonite (X_Mg 0.21 to 0.33), hornblende, bioti te along with minor amounts of ankerite (X_Mg O. 30 to 0.52), calcite (X_Mg 0.06 to 0.22), chamosite and pyri teo Chamosite, a rare relict mineral, was probably formed by reaction between high Al-clay and Fe. Magnetite was formed during metamorphism. Along with the precipitation of alternating layers rich in silica and iron, clayey material in the form of montmorillonite, illite and/or glauconite along with Fe-Mg carbonates were also deposited, which after metamorphism (430-520°C) gave rise to the present mineralogy.

Keywords

BIF, Mineral Chemistry, Kudremukh Schist Belt, Karnataka.

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