DEPOSITION AND PALEOWEATHERING OF MAASTRICHTIAN (UPPER CRETACEOUS) TERRESTRIAL DEPOSITS AT MAREPALLI QUARRY, CENTRAL INDIA

The Deccan Volcanic Province (DVP) and the Late-Cretaceous mass extinction have been linked on the basis of volcanically-induced environmental destabilization. Sedimentary deposits stratigraphically underlying and between basalt flows have yielded diverse fossil assemblages, and their depositional context reveals possible paleoclimatic changes as eruptions transformed regional topography and atmospheric conditions. Recent collections at Marepalli Quarry (Maastrichtian, Upper Cretaceous), Telangana, India have yielded fish, turtle, and crocodilian fossil material. Here we provide depositional and paleoclimatic context for these biotic remains based on first-hand study of the fossil site. The quarry exposes 12 m of stratigraphic section dominated by clay conglomerates, with clasts ranging from silt-pebble to clay granules. Both matrix and clast clays lithologically resemble clays found elsewhere in the DVP that have been associated with olivine-rich basalt sources. The clay units of Marepalli are overlain by 1.5 m of limestone and capped by a largely unaltered basalt flow, and all units have a south-trending depositional dip. Further analysis of the sources of the clays and the structure of this site suggest this site to be a lacustrine deltaic environment on the basis of the variable conglomerate as well as the dip of the beds, interpreted as the result of a topographic low. Major elements were identified, and Chemical Index of Alteration values for each lithologic unit were calculated to characterize paleoclimate as humid or arid. These results are used to test the hypothesis that the clays are basalt-derived and were weathered and deposited under humid conditions.