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 δ13C values of the limestones in the studied succession are negative and there are two prominent shifts in δ13C 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 δ18O (−6.38 to −9.84‰), 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.

中文翻译：

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印度斋沙默尔盆地晚古新世-早始新世石灰岩序列中高温事件的特征

在这里，对印度西部斋沙默尔盆地的古新世-始新世石灰岩进行放射性锶同位素和稳定碳氧同位素分析，以寻找古新世-始新世热最大值和早始新世气候最适的证据。Numulites burdigalensis 的出现表明该序列是一个古新世-始新世间隔，这也被放射性锶同位素比率证实。所研究石灰岩的低 Mn/Sr 比 (< 2) 表明它们是原始的，可以呈现原始的同位素特征。研究序列中石灰岩的 δ13C 值为负，δ13C 曲线有两个显着的向更负侧移动，一个在序列的下部，另一个在序列的中间。下部代表古新世-始新世热最大值，中间代表早始新世气候最适。这两个峰值被解释为由于区域构造可能与印度-亚洲碰撞有关，大气或陆地中的碳增加。此外，δ18O 的变化（-6.38 到 -9.84‰）值可以与与碳同位素 I 和 II 阶段同时期的始新世变暖事件相关联。在这两次超高温事件（PETM 和 EECO）期间温度升高的影响是，在碳同位素 I 阶段和碳同位素 II 阶段，该序列富含较大的有孔虫。这两个峰被解释为由于区域构造可能与印度-亚洲碰撞有关，从大气或陆地中添加了碳。此外，δ18O 的变化（-6.38 到 -9.84‰）值可以与与碳同位素 I 和 II 阶段同时期的始新世变暖事件相关联。在这两次超高温事件（PETM 和 EECO）期间温度升高的影响是，在碳同位素 I 阶段和碳同位素 II 阶段，该序列富含较大的有孔虫。这两个峰值被解释为由于区域构造可能与印度-亚洲碰撞有关，大气或陆地中的碳增加。此外，δ18O 的变化（-6.38 到 -9.84‰）值可能与始新世变暖事件有关，这些事件与碳同位素 I 和 II 阶段同时期。在这两次超高温事件（PETM 和 EECO）期间温度升高的影响是，在碳同位素 I 阶段和碳同位素 II 阶段，该序列富含较大的有孔虫。