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Environmental and Climatic Conditions during the K-T Transition in the Cauvery Basin, India: Current Understanding Based on Chemostratigraphy and Implications on the KTB Scenarios
The environmental and climatic conditions prevalent during the transition from Cretaceous-Tertiary boundary (KTB) that caused extinction of marine and terrestrial fauna have been among the intensively studied geological phenomena. Cataclysmic meteoritic impact, Deccan volcanism, sea level fluctuation, acid rain, ocean acidification, contamination of marine and terrestrial ecosystems and atmosphere etc., by sulfur and methane are proposed to be the cause(s) of the extinction. In addition, the pattern of extinction itself, namely, sudden extinction due to extra-terrestrial catastrophic event and stepwise extinction due to multiple events and processes, is debated by the geoscientists. The Cauvery Basin, South India, contains more or less complete stratigraphic record of Barremian-Danian and thus has been studied by many researchers for the cause(s) of extinction pattern across K-T. This chapter presents the initial results of recently identified continuous K-T section located near Niniyur village in the Cauvery Basin and discusses the inferences in the light of regional and global models proposed as to the cause(s) of the extinction pattern. Results of the study indicate the predomination of influence of sea level fluctuations (which in turn might have been influenced by Deccan volcanism) over the depositional pattern of the Cauvery Basin. In addition, prevalence of many events namely off-seasonal floods, sharp, and sudden climatic reversals, destabilization of gas hydrates, and release of methane, all of which predating KTB and coincidental with similar events in geographically widely separated stratigraphic sections as indicated by geochemical anomalies are also recorded by the present study. Thus, present analysis supports the interpretation of regional and global scale, multicausal stepwise extinction pattern across KTB. © 2015 Elsevier Inc. All rights reserved.
Chemostratigraphy: Concepts, Techniques, and Applications
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