Signatures of hyperthermal events in the Late Paleocene-Early Eocene limestone succession of the Jaisalmer basin, India

Here, radiogenic strontium isotopes, and stable carbon and oxygen isotopes analyses of the Paleocene-Eocene limestones of the Jaisalmer basin, Western India are carried out to find out the evidences of Paleocene-Eocene thermal maximum and Early Eocene Climatic Optimum. The occurrence of Numulites burdigalensis suggests the succession to be a Paleocene-Eocene interval that is also confirmed by the radiogenic strontium isotope ratios. The low Mn/Sr ratio (< 2) of the studied limestones suggest that they are pristine and can present the original isotopic signatures. The delta C-13 values of the limestones in the studied succession are negative and there are two prominent shifts in delta C-13 curve towards the more negative side, one in the lower part and another in the middle of the succession. The lower one represents the Paleocene-Eocene Thermal Maximum and the middle one represents the Early Eocene Climatic Optimum. These two peaks are interpreted as the addition of carbon from the atmosphere or land as a result of the regional tectonics which could be connected with India-Asia collision. Also, the shift in the delta O-18 (-6.38 to -9.84 parts per thousand), values can be linked with the Eocene warming events that are coeval with the carbon isotopic stages I and II. The effect of risen temperatures during these two hyperthermal events (PETM and EECO) was such that the succession is rich in larger foraminifera at carbon isotope stage I and carbon isotope stage II.