Multiproxy analysis constraining climatic control over the Cenozoic depositional history of Kachchh, Western India

Abstract

A well‐developed 86 m‐thick Cenozoic sedimentary succession in the Matanomadh area, western Kachchh, was studied to assess the stratigraphic positions of different units, ascertain depositional environments, and the degree of climatic controls over time depositional processes. Age‐diagnostic nannoplankton species Cyclicargolithus floridanus (46.29–12.1 Ma), Reticulofenestra dictyoda (53–30.8 Ma), Reticulofenestra minuta (50.5–2.59 Ma) and foraminiferal species, for example, Orbulinoides beckmanni (41–39.5 Ma) found across studied units envisage the stratigraphic age and palaeoenvironment. CaO with strong negative elemental correlation, binary/ternary discriminant tectonic and depositional regimes cross‐plot from units indicate the biogenic origin of limestones and shales were formed in typical passive, marginal, shallow littoral settings with plausible detritus influx from Deccan basaltic provenance. Total organic carbon with TE‐REE respectively connotes a sedimentation process in a nearly consistent open shallow marine, locally transient semi‐restricted marginal basin in a tropical‐equatorial region. Furthermore, principal component analysis (PCA) of weathering indices based on elemental abundance and X‐ray diffraction data of clays deterministically suggest with empirical relation between humid tropical climate‐induced weathering and fluctuant terrestrial influx. Palaeoredox indices with biological data demonstrate localized redox‐stratified conditions. However, coherent signatures of the global events such as Eocene Thermal Maximum‐2, Middle Eocene Climatic Optimum, and Mid Miocene Climatic Optimum can be traced and validated by synthesizing geochemical data for direct/indirect estimation of sediment routing, rainfall (αAlMg and αAlCa) and climate proxies (PCA), productivity indices (Babio, Cubio and Nibio), and localized periodic oxic‐dysoxic environment (V/Cr, U/Th, Ni/Co) from core samples.