Coupled evolution of temperature and carbonate chemistry during the Paleocene-Eocene; new trace element records from the low latitude Indian Ocean
Coupled evolution of temperature and carbonate chemistry during the Paleocene-Eocene; new trace element records from the low latitude Indian Ocean
复制标题
DOI：
10.1016/j.epsl.2020.116414
复制
发表时间：
2020-09-01
影响因子：
5.3
通讯作者：
Littler, Kate
中科院分区：
文献类型：
--
作者：
Barnet, James S. K.;Harper, Dustin T.;Littler, Kate
古近纪早期代表了地球历史上最近的一段时间，其特征是数百万年时间尺度上的全球温室效应变暖，但我们对低纬度地区，特别是印度洋长期气候和碳循环演变的理解仍然非常有限。在这里，我们提出了第一个长期的亚偏心率分辨率的稳定同位素（三角洲C-13和三角洲O-18）和微量元素（Mg/Ca和B/Ca）记录跨越晚古新世-早始新世（类似于58-53马）的表面深水文重建的北方印度洋，解决晚古新世405 kyr节奏的旋回性和PETM恢复的一部分。我们的新记录显示，在水柱的所有深度，长期变暖类似于4-5摄氏度，绝对表面海洋温度和变暖幅度与低纬度太平洋相当。由于变暖，我们观察到的混合层的三角洲O-18（SW）的长期增加，这意味着净蒸发量的增加。我们还观察到崩溃的温度梯度之间的混合层和温跃层居住的物种从类似的57-54马，可能是由于一个更均匀的水柱与更厚的混合层的发展，或深度迁移的Morozovellain响应变暖。低纬和高纬同步变暖，沿着南极有孔虫中B/Ca比值的降低，表明海洋pH值的降低和/或溶解无机碳的增加，表明全球气候在此期间受到大气CO2浓度升高的影响。(C)2020作者（S）由爱思唯尔公司出版
The early Paleogene represents the most recent interval in Earth's history characterized by global greenhouse warmth on multi-million year timescales, yet our understanding of long-term climate and carbon cycle evolution in the low latitudes, and in particular the Indian Ocean, remains very poorly constrained. Here we present the first long-term sub-eccentricity-resolution stable isotope (delta C-13 and delta O-18) and trace element (Mg/Ca and B/Ca) records spanning the late Paleocene-early Eocene (similar to 58-53 Ma) across a surface-deep hydrographic reconstruction of the northern Indian Ocean, resolving late Paleocene 405-kyr paced cyclicity and a portion of the PETM recovery. Our new records reveal a long-term warming of similar to 4-5 degrees C at all depths in the water column, with absolute surface ocean temperatures and magnitudes of warming comparable to the low latitude Pacific. As a result of warming, we observe a long-term increase in delta O-18(sw) of the mixed layer, implying an increase in net evaporation. We also observe a collapse in the temperature gradient between mixed layer- and thermocline-dwelling species from similar to 57-54 Ma, potentially due to either the development of a more homogeneous water column with a thicker mixed layer, or depth migration of the Morozovellain response to warming. Synchronous warming at both low and high latitudes, along with decreasing B/Ca ratios in planktic foraminifera indicating a decrease in ocean pH and/or increasing dissolved inorganic carbon, suggest that global climate was forced by rising atmospheric CO2 concentrations during this time. (C) 2020 The Author(s). Published by Elsevier B.V.