Sea level, biotic and carbon-isotope response to the Paleocene-Eocene thermal maximum in Tibetan Himalayan platform carbonates
Sea level, biotic and carbon-isotope response to the Paleocene-Eocene thermal maximum in Tibetan Himalayan platform carbonates
复制标题
海平面、生物和碳同位素对青藏喜马拉雅台地碳酸盐岩古新世-始新世热最大值的响应
DOI：
10.1016/j.gloplacha.2020.103316
复制
发表时间：
2020-11-01
影响因子：
3.9
通讯作者：
BouDagher-Fadel, Marcelle
中科院分区：
文献类型：
--
作者：
Li, Juan;Hu, Xiumian;BouDagher-Fadel, Marcelle
在古新世 - 始新世极热事件（PETM，约5600万年前）期间，一次大规模的负碳同位素偏移（CIE）证明了全球碳循环受到了巨大扰动。浅海环境对于理解与PETM相关的环境和生态变化以及大陆环境和开阔海洋环境之间的联系至关重要。对西藏南部特提斯喜马拉雅地区一套近乎连续的浅海碳酸盐岩地层进行详细的沉积学、古生物学和地球化学分析表明，海平面相对上升与PETM开始时间一致，在PETM核心阶段持续，并且随着PETM恢复阶段的海退而终止。在PETM开始时，对应于SBZ4/SBZ5界线，未观察到对生物群尤其是对大型底栖有孔虫（LBF）有明显影响。主要的生物变化发生在稍后的PETM恢复阶段，对应于SBZ5/SBZ6界线。我们的数据表明，在PETM期间，相对海平面而非温度对底栖生物群起主要控制作用。尽管深海和浅海大陆边缘的有机质δ13C（org）值相似，但碳酸盐岩整体的δ13C（carb）值明显贫13C，我们将此归因于相对海平面波动驱动的环境变化。
During the Paleocene-Eocene Thermal Maximum (PETM, similar to 56 Ma), a large, negative carbon-isotope excursion (CIE) testifies to a massive perturbation of the global carbon cycle. Shallow-marine settings are crucial to understand the environmental and ecological changes associated with the PETM and the connection between continental and open-marine environments. Detailed sedimentological, paleontological, and geochemical analysis of a quasi-continuous succession of shallow-marine carbonates in the Tethys Himalaya of southern Tibet indicates that a relative rise in sea level coincided with PETM onset, continued through PETM core, and terminated with a regression at PETM recovery. At PETM onset, corresponding to the SBZ4/SBZ5 boundary, no obvious impact on biota and specifically on larger benthic foraminifera (LBF) is observed. The major biotic change occurs later on at PETM recovery, corresponding to the SBZ5/SBZ6 boundary. Our data suggest that relative sea level, rather than temperature, exerted the main control on benthic biota during the PETM. Although the delta C-13(org) values of organic matter are similar in the deep sea and shallow-marine continental margins, the delta C-13(carb) value of bulk carbonates are significantly C-13-depleted, which we attribute to environmental change driven by relative sea-level fluctuations.