The Deccan Traps in Western India is hypothesized to have caused significant fluctuations in climatic condition and organic matter (OM) productivity across the Cretaceous-Paleogene Boundary (K/PgB). The periodic release of large amounts of volatiles into the atmosphere is thought to drive these changes. Yet, direct impact of volcanism on the carbon cycle and ecosystem remains relatively unconstrained. For the first time, we attempt to trace changes in both marine and terrestrial carbon reservoirs from pre- and intervolcanic sedimentary units (infra- and inter-trappeans respectively) from Rajahmundry, ~1500 km SE of main eruption sites in Western India. Molecular level characterization of OM and stable isotope composition of carbonates (δ¹³C_carb), bulk OM (δ¹³C_org), and n-alkane (δ¹³C_alk and δD_alk) have been analysed to provide a chemo-stratigraphic framework. In Rajahmundry, high CO₂ concentration estimated from infra-trappean carbonate nodule is synchronous with the onset of the Deccan Traps and the Late Maastrichtian warming episode. Impact of the warming event is reflected in Rajahmundry from a major shift in the terrestrial ecosystem. Marine OM production also seems to have been low throughout the infra-trappean. A steady decrease in δ¹³C_carb values, increase in mortality rates and dwarfism in invertebrates immediately below the first volcanic units in Rajahmundry suggest stressed conditions from eruption in the western part of India ~40–60 kyrs prior to K/PgB. A significant increase in heterotrophic activity is observed after the volcanic deposits in Rajahmundry that seems to have controlled the marine carbon reservoir for a maximum of ~200 kyrs after the boundary. Advent of pteridophytes, increase in carbon content and positive shifts in δ¹³C_carb and δ¹³C_alk values in the upper inter-trappean units mark the onset of recovery in terrestrial and marine environments. Overall, our results suggest significant perturbations in the carbon reservoir as a consequence of the Deccan eruption.

中文翻译：

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德干火山活动引起的碳储层扰动：印度东部浅海环境的稳定同位素和生物分子视角

据推测，印度西部的德干圈闭引起了白垩纪-古近纪边界 (K/PgB) 气候条件和有机质 (OM) 生产力的显着波动。大量挥发物定期释放到大气中被认为是推动这些变化的原因。然而，火山活动对碳循环和生态系统的直接影响仍然相对不受限制。我们首次尝试追踪印度西部主要喷发地点东南约 1500 公里的 Rajahmundry 的火山前和火山间沉积单元（分别为下层和层间）的海洋和陆地碳储层的变化。OM 的分子水平表征和碳酸盐的稳定同位素组成 (δ ¹³ C _carb )、本体 OM (δ ¹³C _org ) 和正烷烃 (δ ¹³ C _alk和 δD _alk ) 已被分析以提供化学地层框架。在拉贾蒙德里，从下层碳酸盐结核估计的高 CO _{2浓度与德干圈闭的开始和马斯特里赫特晚期变暖事件同步。}变暖事件的影响反映在拉贾蒙德里，来自陆地生态系统的重大转变。海洋 OM 的产量似乎也一直很低。^{δ 13} C_{碳水化合物}的稳定下降Rajahmundry 的第一个火山单元正下方的无脊椎动物死亡率增加和侏儒症表明印度西部喷发的压力条件在 K / PgB 之前约 40-60 kyrs。在 Rajahmundry 的火山沉积物之后，观察到异养活动显着增加，这似乎已将海洋碳储库控制在边界后最多约 200 kyrs。蕨类植物的出现，碳含量的增加和 δ ¹³ C _carb和 δ ¹³ C _{alk的正变化}上层间单位的值标志着陆地和海洋环境恢复的开始。总体而言，我们的结果表明，由于德干火山喷发，碳储层发生了显着扰动。