Antarctic climate, Southern Ocean circulation patterns, and deep water formation during the Eocene
Antarctic climate, Southern Ocean circulation patterns, and deep water formation during the Eocene
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始新世期间的南极气候、南大洋环流模式和深水形成
DOI：
10.1002/2017pa003135
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
Huck C
中科院分区：
文献类型：
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作者：
Huck C
为了评价南大洋环流在长期新生代气候变化中的作用，对南大洋深海钻探点的早至中始新世海水钕（Nd）同位素记录进行了评估。我们的研究地点战略性地位于塔斯曼门户的两侧，位于浅（<500米）到中/深（~ 1000-2500米）古水深范围内。非放射性成因的海水Nd同位素组成，由中/深印度洋中远洋地点(Ocean Drilling Program （ODP) Site 738和757以及deep Sea Drilling Project (DSDP) Site 264）的鱼齿重建，表明南大洋对区域深水的贡献占主导地位（εNd(t)= - 9.3±1.5）。adsamlie Land海岸外的IODP站点U1356是现代南极底水生产的场所，被认为是从始新世早期到渐新世持续形成深水的地点。在Tasman门户以东，在西南太平洋的ODP Site 277推断出了一个额外的中/深水形成的本地来源（εNd(t)= - 8.7±1.5）。南极-近陆架站点（ODP站点1171和站点U1356）在49 ~ 48 Ma之间显示了明显的侵蚀事件，表现为海水化学对这些站点大块沉积物组成的~2εNdunit负偏移。这一侵蚀事件与始新世早期气候最佳期之后全球变暖峰值的终止相吻合，并与研究区域的文献记载的变冷和南极深水出口的增加有关，突出了始新世温室气候中南大洋环流的复杂性和重要性。
We assess early‐to‐middle Eocene seawater neodymium (Nd) isotope records from seven Southern Ocean deep‐sea drill sites to evaluate the role of Southern Ocean circulation in long‐term Cenozoic climate change. Our study sites are strategically located on either side of the Tasman Gateway and are positioned at a range of shallow (<500 m) to intermediate/deep (~1000–2500 m) paleowater depths. Unradiogenic seawater Nd isotopic compositions, reconstructed from fish teeth at intermediate/deep Indian Ocean pelagic sites (Ocean Drilling Program (ODP) Sites 738 and 757 and Deep Sea Drilling Project (DSDP) Site 264), indicate a dominant Southern Ocean‐sourced contribution to regional deep waters (εNd(t)= −9.3 ± 1.5). IODP Site U1356 off the coast of Adélie Land, a locus of modern‐day Antarctic Bottom Water production, is identified as a site of persistent deep water formation from the early Eocene to the Oligocene. East of the Tasman Gateway an additional local source of intermediate/deep water formation is inferred at ODP Site 277 in the SW Pacific Ocean (εNd(t)= −8.7 ± 1.5). Antarctic‐proximal shelf sites (ODP Site 1171 and Site U1356) reveal a pronounced erosional event between 49 and 48 Ma, manifested by ~2εNdunit negative excursions in seawater chemistry toward the composition of bulk sediments at these sites. This erosional event coincides with the termination of peak global warmth following the Early Eocene Climatic Optimum and is associated with documented cooling across the study region and increased export of Antarctic deep waters, highlighting the complexity and importance of Southern Ocean circulation in the greenhouse climate of the Eocene.