Geochemistry of sandstones from the Upper Cretaceous Sillakkudi Formation, Cauvery Basin, southern India: Implication for provenance

摘要: Major, trace and rare earth elements (REE) composition of sandstones from the Upper Cretaceous Sillakkudi Formation, Ariyalur Group, Cauvery Basin were studied to decipher their weathering provenance history. Texturally, these are immature, poorly sorted grain supported. Abundance feldspars especially, plagioclase indicates rapid deposition sediments a nearby source rocks. Using geochemical classification diagram classified as fe-sand, quartz arenite, litharenite, sub-litharenite, sub-arkose, arkose, wacke types, which is also supported by petrography study. The transition like Co, Ni, V higher in than upper continental crust (UCC) values. However, lower Cr (mean ∼21) content average UCC value (∼ 35). poor correlation between Ni (r = 0.08, number samples n 20) imply that derived felsic Similarly, Eu/Eu* (0.35–1.73), La/Sc (1.93–9.36), Th/Sc (0.41–6.57), Th/Co (0.14–5.01), Th/Cr (0.23–2.94), Cr/Th (0.34–4.28) ratios support for sandstones. significant enrichment Zr, Hf, Th sub-arkose litharenite could be related presence heavy minerals, especially zircon. zircon geochemistry did not affect REE distribution its patterns Chondrite normalized characterized relatively flat HREE (Gd/YbCN ∼ 0.73–2.41; subscript CN refers chondrite value), enriched LREE (La/SmCN 3.39–5.82) negative Eu anomaly 0.80). Gd/YbCN (∼0.73–2.50) less 2.5, suggest depleted comparison anomalies rocks reveals received major contribution Dharwar craton.