Reconstruction of the Early Miocene Stratigraphy of Kutch Using Sedimentological and Paleontological Proxies

Jain, Mansi (2015) Reconstruction of the Early Miocene Stratigraphy of Kutch Using Sedimentological and Paleontological Proxies. Masters thesis, Indian Institute of Science Education and Research Kolkata.

PDF (MS dissertation of Mansi Jain (10MS94)) Mansi_Jain-10MS94.pdf - Submitted Version Restricted to Repository staff only Download (2MB)

Abstract

Establishing a complete stratigraphic network of a basin is important to understand the basin history. This provides a basic framework for all studies that involve the stratigraphy of a region. With its well developed fossiliferous Tertiary sequence, Kutch, Gujrat merits to be considered as a Tertiary stratotype for shallow marine sediments in India. This study is primarily focused on the reconstruction of the stratigraphy of two formations, Khari Nadi formation (Aquitanian (23-20.4 my)) and Chassra formation (Burdigalian (20.4 – 15.9 my)) of the Early Miocene of this region with some focus on the interpretation of depositional environment and paleoenvironmental conditions. This has been done with the help of sedimentological and paleontological evidences and geochemical proxies. Here we have used the Strontium isotopic ratios using shells of Ostrea angulata to get the precise age of the strata. The shells of Ostrea angulata, Ostrea latimarginata and Pectinidae were used for the ICPMS analysis to get the Me/Ca ratios and to observe their variation with time. Whole rock XRD analysis was done to draw interpretation about the depositional environment of the sediments. Since the results obtained from the Me/Ca ratios does not show any characteristic trend, it suggests that Ostrea angulata cannot be used to measure paleoenvironmental proxies. The grain size analysis and the semi-quantitative XRD data indicates the existence of transgressive sea which is consistent with the earlier findings.

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