Investigating Ocean Deoxygenation During the PETM Through the Cr Isotopic Signature of Foraminifera
Investigating Ocean Deoxygenation During the PETM Through the Cr Isotopic Signature of Foraminifera
复制标题
DOI：
10.1029/2018pa003372
复制
发表时间：
2019-06
影响因子：
3.5
通讯作者：
Serginio R. C. Remmelzwaal;Sophie Dixon;I. Parkinson;D. Schmidt;F. Monteiro;P. Sexton;M. Fehr;C. Peacock;Y. Donnadieu;R. James
中科院分区：
文献类型：
--
作者：
Serginio R. C. Remmelzwaal;Sophie Dixon;I. Parkinson;D. Schmidt;F. Monteiro;P. Sexton;M. Fehr;C. Peacock;Y. Donnadieu;R. James
在过去的几十年里，由于气温上升引发了对未来气候变化影响的担忧，氧气最低限制区迅速扩大。要更好地理解这种扩张背后的驱动因素，一种方法是评估过去气候和海水除氧之间的联系，特别是在地质上突然发生气候变化的时期，如古新世-始新世最热时期(PETM)，这是一个具有良好特征的快速升温约56 Ma的时期。我们已经开发和应用了有孔虫铬同位素(δ53Cr)和Ce异常(Ce/Ce*)的新型氧化还原替代物，以评估氧可获得性变化引起的古氧化还原条件的变化。在中至上深海深度，δ53Cr和Cr浓度均显著降低，表明溶解氧浓度普遍下降。δ~(53)Cr的大小与海底δ~(18)O漂移之间的明显相关性表明，温度是公海脱氧的主要控制因素之一。海洋钻探计划在太平洋和东南大西洋的1210个地点和1263个地点表明，除氧作用与气候变暖和环流变化有关，这一点得到了Ce/Ce*数据的支持。我们的地球化学数据得到了中等复杂性气候模型(CGENIE)模拟的支持，该模型表明，在PETM期间，缺氧主要限于特提斯海，而由于大气中二氧化碳的增加(从工业化前的1到6倍)，缺氧更加普遍。
Over the past several decades, oxygen minimum zones have rapidly expanded due to rising temperatures raising concerns about the impacts of future climate change. One way to better understand the drivers behind this expansion is to evaluate the links between climate and seawater deoxygenation in the past especially in times of geologically abrupt climate change such as the Palaeocene‐Eocene Thermal Maximum (PETM), a well‐characterized period of rapid warming ~56 Ma. We have developed and applied the novel redox proxies of foraminiferal Cr isotopes (δ53Cr) and Ce anomalies (Ce/Ce*) to assess changes in paleoredox conditions arising from changes in oxygen availability. Both δ53Cr and Cr concentrations decrease notably over the PETM at intermediate to upper abyssal water depths, indicative of widespread reductions in dissolved oxygen concentrations. An apparent correlation between the sizes of δ53Cr and benthic δ18O excursions during the PETM suggests temperature is one of the main controlling factors of deoxygenation in the open ocean. Ocean Drilling Program Sites 1210 in the Pacific and 1263 in the Southeast Atlantic suggest that deoxygenation is associated with warming and circulation changes, as supported by Ce/Ce* data. Our geochemical data are supported by simulations from an intermediate complexity climate model (cGENIE), which show that during the PETM anoxia was mostly restricted to the Tethys Sea, while hypoxia was more widespread as a result of increasing atmospheric CO2 (from 1 to 6 times preindustrial values).