Biotic Response to Early Eocene Warming Events: Integrated Record From Offshore Zealandia, North Tasman Sea
Biotic Response to Early Eocene Warming Events: Integrated Record From Offshore Zealandia, North Tasman Sea
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DOI：
10.1029/2020pa004179
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发表时间：
2021-07
影响因子：
3.5
通讯作者：
L. Alegret;D. Harper;C. Agnini;C. Newsam;T. Westerhold;M. Cramwinckel;E. Dallanave;G. Dickens;R. Sutherland
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文献类型：
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作者：
L. Alegret;D. Harper;C. Agnini;C. Newsam;T. Westerhold;M. Cramwinckel;E. Dallanave;G. Dickens;R. Sutherland
西南太平洋早期始新世高温事件的环境和生物响应对新生代温室间期的全球古气候重建至关重要，但从这个时间和地点通常缺乏详细的多学科研究。始新世碳酸盐沉积物是在国际海洋发现计划第371次远征期间在塔斯曼海洛德-豪隆起南部的U1510站点发现的。根据精细的钙质超微化石生物地层学资料和块状沉积物和底栖有孔虫的碳稳定同位素记录，确定了早始新世气候最佳时期(EECO；53.26-49.14 Ma)的一部分和叠加的过热事件。在EECO中识别出四个与负氧同位素漂移相关的负碳同位素漂移(CIES)。与全球台址的对比表明，这些CIE与K事件(始新世最大热值3)相关，并初步与S、T和U事件相关。整个EECO中碳酸盐含量较高的沉积物为研究这些CIE提供了极好的机会，因为碳酸盐的溶解往往会影响其他地方的相关记录。指示温暖水域的底栖有孔虫和钙质超微浮游动物类群在K事件期间最丰富，这是EECO最显著的过热事件。K事件期间表层水的富营养化并没有导致海底营养条件的增加，而在较小的高温期间观察到了耦合反应。生物更替为高温事件的古环境后果提供了新的线索。
Environmental and biotic responses to early Eocene hyperthermal events in the southwest Pacific are critical for global paleoclimate reconstructions during Cenozoic greenhouse intervals, but detailed multidisciplinary studies are generally missing from this time and location. Eocene carbonate sediments were recovered during International Ocean Discovery Program Expedition 371 at Site U1510 on southern Lord Howe Rise in the Tasman Sea. Part of the Early Eocene Climatic Optimum (EECO; 53.26–49.14 Ma) and superimposed hyperthermal events have been identified based on refined calcareous nannofossil biostratigraphic data and carbon stable isotope records on bulk sediment and benthic foraminifera. Four negative carbon isotope excursions (CIEs) associated with negative oxygen isotope excursions are recognized within the EECO. Comparison with a global compilation of sites indicates these CIEs correlate to the K event (Eocene Thermal Maximum 3), and tentatively to the S, T, and U events. Sediments with a high carbonate content throughout the EECO provide an excellent opportunity to examine these CIEs, as carbonate dissolution often impacts correlative records elsewhere. Benthic foraminifera and calcareous nannoplankton taxa indicative of warm waters are most abundant during the K event, the most prominent hyperthermal of the EECO. Eutrophication of surface waters during the K event did not lead to increased trophic conditions at the seafloor, whereas a coupled response is observed during smaller hyperthermals. The biotic turnover sheds new light on the paleoenvironmental consequences of hyperthermal events.