The Paleocene–Eocene Thermal Maximum (PETM, ~56 Ma) is a large negative carbon isotope excursion (CIE) that testifies to a massive perturbation of the global carbon cycle and has been considered to be an ancient, deep-time analogue for present and future climate change. However, the environmental and carbon isotopic response to the PETM in shallow-water carbonate platforms has remained largely elusive. This study presents new sedimentological, biostratigraphic, and carbon isotopic data to evaluate the impact of the PETM on a shallow-water carbonate platform from more proximal southern parts of the northern Indian continental margin. Detailed biostratigraphy and carbon isotope data indicate that the PETM occurs 3 m below the boundary between nodular and thin-bedded limestones, is maintained up to the thin-bedded limestone and calcareous marl interval, and is followed by recovery at the base of thick-bedded limestone interval. Microfacies analysis testifies to a regression from open to restricted shallow-marine environments at the transition from PETM onset to PETM core, and shallowing continued through the PETM core. Restricted lagoonal deposition was renewed during PETM recovery. These environmental changes were associated with two major turnovers of shallow-water biota. We infer that the first sudden biotic change at the PETM onset may relate to intensified continental weathering, whereas the second biotic change at PETM recovery may have been caused by sea-level fall. The smaller magnitude of the CIE observed in proximal, shallower-water than in distal, deeper-water environments is ascribed to increased primary productivity due to increased nutrients' supply associated with intensified continental weathering.

古新世-始新世热最大值 (PETM, ~56 Ma) 是一个大的负碳同位素偏移 (CIE)，它证明了全球碳循环的巨大扰动，并被认为是现在和未来的气候变化。然而，浅水碳酸盐平台对 PETM 的环境和碳同位素响应在很大程度上仍然难以捉摸。本研究提供了新的沉积学、生物地层学和碳同位素数据，以评估 PETM 对印度北部大陆边缘更近南部的浅水碳酸盐台地的影响。详细的生物地层学和碳同位素数据表明，PETM 发生在结节状和薄层状石灰岩边界以下 3 m 处，一直维持到薄层灰岩和钙质泥灰岩层段，然后在厚层灰岩层段底部恢复。微相分析证明，在从 PETM 开始到 PETM 核心的过渡过程中，从开放到受限的浅海环境的回归，并且浅层继续通过 PETM 核心。在 PETM 恢复期间，限制性泻湖沉积被更新。这些环境变化与浅水生物群的两个主要周转有关。我们推断，PETM 开始时的第一次突然的生物变化可能与强化的大陆风化有关，而 PETM 恢复时的第二次生物变化可能是由海平面下降引起的。在近端浅水中观察到的 CIE 幅度比在远端更小，