Late Eocene Record of Hydrology and Temperature From Prydz Bay, East Antarctica
Late Eocene Record of Hydrology and Temperature From Prydz Bay, East Antarctica
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东南极洲普里兹湾晚始新世水文和温度记录
DOI：
10.1029/2020pa004204
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发表时间：
2021-04
影响因子：
3.5
通讯作者：
E. J. Tibbett;H. Scher;S. Warny;J. Tierney;S. Passchier;S. Feakins
中科院分区：
文献类型：
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作者：
E. J. Tibbett;H. Scher;S. Warny;J. Tierney;S. Passchier;S. Feakins
始新世-渐新世过渡（EOT）标志着南极冰川作用在33.7 Ma开始。虽然海底氧同位素记录确定了主要的大陆冰盖扩张，但最近的沉积和地球化学证据表明存在更早的短暂冰盖。来自大洋钻探计划第119和188航段的沉积物岩心提供了东南极洲主要排水系统的情况档案。我们研究生物标志物和微体化石证据，以了解植被和气候如何在36和33 Ma之间变化。花粉主要是改造二叠纪Glossopterid裸子植物，然而，准同生始新世花粉组合表明，一些植被生存的冰川进步。在EOT时，brGDGT土壤生物标志物表明从13°C突然冷却到8°C，土壤pH值从6.0增加到6.7，表明干燥，这进一步得到了植物蜡氢和碳同位素位移分别为20‰和1.1‰的支持，以及来自风化代理的干燥证据。虽然陆地土壤生物标志物的流入主要排除了TEX 86的使用，但我们发现始新世晚期的12°C的海面温度在EOT时冷却到8°C。海洋生产力在冰川推进后持续增加，这可能是由于海洋环流的增强。在37.3 Ma的Priabonian Oxygen Maximum和33.7 Ma的EOT这两次冰川激增事件之间，我们观察到35.7和34.7 Ma的变暖2-5°C，准同期花粉增加，海洋生产力增强，捕获了南极温暖的最后一闪。
The Eocene‐Oligocene transition (EOT) marks the onset of Antarctic glaciation at 33.7 Ma. Although the benthic oxygen isotope record defines the major continental ice sheet expansion, recent sedimentary and geochemical evidence suggests the presence of earlier ephemeral ice sheets. Sediment cores from Ocean Drilling Program Legs 119 and 188 in Prydz Bay provide an archive of conditions in a major drainage system of East Antarctica. We study biomarker and microfossil evidence to discern how the vegetation and climate shifted between 36 and 33 Ma. Pollen was dominated by reworked Permian Glossopterid gymnosperms; however, penecontemporaneous Eocene pollen assemblages indicate that some vegetation survived the glacial advances. At the EOT, brGDGT soil biomarkers indicate abrupt cooling from 13°C to 8°C and soil pH increases from 6.0 to 6.7, suggesting drying which is further supported by plant wax hydrogen and carbon isotopic shifts of 20‰ and 1.1‰, respectively, and evidence for drying from weathering proxies. Although the terrestrial soil biomarker influx mostly precludes the use of TEX86, we find sea surface temperatures of 12°C in the late Eocene cooling to 8°C at the EOT. Marine productivity undergoes a sustained increase after the glacial advance, likely promoted by enhanced ocean circulation. Between the two glacial surge events of the Priabonian Oxygen Maximum at 37.3 Ma and the EOT at 33.7 Ma, we observe warming of 2–5°C at 35.7 and 34.7 Ma, with increase in penecontemporaneous pollen and enhanced marine productivity, capturing the last flickers of Antarctic warmth.