Geochemistry of Hindoli Group metasediments,SE Aravalli Craton,NW India: Implications for palaeoweathering and provenance |
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| Authors: | Asha Saxena M K Pandit |
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| Institution: | 1.Department of Geology,University of Rajasthan,Jaipur,India;2.BMG, Western Off-shore Basin,ONGC,Sion, Mumbai,India |
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| Abstract: | The southeastern fringe of the Precambrian Aravalli fold belt has been designated as Jahazpur Belt, which includes two greenschist facies metasedimentary lithopackages, Hindoli (Late Archean/Paleoproterozoic) and Jahazpur (Paleoproterozoic) Groups. We present geochemical data on metapelite (phyllite) and metagreywackes from the Hindoli Group. Metapelites are enriched in alumina while metagreywackes show a wide range and higher abundance of silica. Covariance between TiO2 — Al2O3, K2O — Al2O3 pairs and moderate to high SiO2/MgO ratios indicate a strong weathering control. Chemical Index of Alteration (CIA = 68 for metagraywackes; 75 for metapelites) reveals moderately weathered protoliths for them. Fractionated LREE pattern with almost flat HREE trend and moderate to high Eu anomalies (Eu/Eu* = 0.66 to 0.8) indicate feldspar bearing granite — granodiorite as probable compositions in the provenance. Very high PIA values (93) for metapelites reflect almost complete feldspar dissolution while the corresponding values for metagraywackes (68) are relatively lower. The diagnostic immobile trace elements (Sc, Zr, Th) can be interpreted as a variable felsic source (mainly granitic and subordinate granodioritic) for metagreywackes and a granodioritic (more mafic) one for metapelites. Considering the broad Precambrian geological set-up of NW India, the Banded Gneiss Complex (BGC), which predominantly comprises TTG gneisses and granites, amphibolite, etc. seems to be the most likely provenance for Hindoli sediments. |
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