Deep hydrography of the South China Sea and deep water circulation in the Pacific since the Last Glacial Maximum
Deep hydrography of the South China Sea and deep water circulation in the Pacific since the Last Glacial Maximum
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末次盛冰期以来南海深层水文学和太平洋深水环流
DOI：
10.1029/2017gc007377
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Dang H.
中科院分区：
文献类型：
--
作者：
Wan S.;Jian Z.;Dang H.
利用南海50个岩心上、下岩心位置的晚全新世和末次盛冰期（LGM） 2个时间片，对深海底栖有孔虫（cibicidoides）的氧（δ18O）和碳（δ13C）同位素组成进行了重建。南海δ18O和δ13C的测深剖面在冰川期与全新世晚期表现出相似的变化趋势，但在冰川期，中水（~ 500 ~ 1000 m）和深水（~ 500 ~ 1500 m）之间的δ18O梯度明显增大，表明冰川期南海中深水分层加剧，垂向混合减弱。对南大洋（印度洋-太平洋部分）和西南太平洋、赤道西太平洋（即Ontong爪哇高原）、日本外边缘以及南海的水深δ18O和δ13C剖面进行了空间比较。经向δ13C剖面显示深层(~ 1200 ~ 2600 m) δ13C由南向北递减（“老化效应”），反映了LGM期间深水从西南太平洋（上游）向低纬度西北太平洋和南海（下游）的北流路径。与全新世相比，这些上游和下游深水δ18O梯度（~ 1200 ~ 2600 m）较高，表明LGM期间北源的δ18O特征相对较低的北太平洋中间水（NPIW）对低纬太平洋深水的贡献较大。
The oxygen (δ18O) and carbon (δ13C) isotopic compositions of benthic foraminiferCibicidoides wuellerstorfias reliable proxies of deep water properties were compiled from 50 core‐top and down‐core sites in the South China Sea (SCS) for two time slices of the late Holocene and Last Glacial Maximum (LGM) to reconstruct the glacial deep hydrographic structure. The bathymetric profiles of both δ18O and δ13C in the SCS show similar trends between the LGM and the late Holocene, but the δ18O gradients between intermediate (∼500–1,000 m) and deep (>1,500 m) waters obviously increased during the LGM, indicating an intensified bathyal stratification and weakened vertical mixing between intermediate and deep waters in the SCS during the glacial period. A spatial comparison of bathymetric δ18O and δ13C profiles was also made for the Southern Ocean (Indo‐Pacific sector) and southwest Pacific, western equatorial Pacific (i.e., Ontong Java Plateau), off‐Japan margin as well as the SCS. The meridional δ13C profiles indicate a decreasing trend of δ13C (“aging effect”) in the deep layer (∼1,200–2,600 m) from south to north, reflecting a northward flow pathway of deep waters from the southwest Pacific (upstream) to the low‐latitude northwest Pacific and the SCS (downstream) during the LGM. The gradients of deep water δ18O (∼1,200–2,600 m) between these upstream and downstream regions were higher during the LGM relative to the Holocene, implying that a greater contribution of the northern‐sourced North Pacific Intermediate Water (NPIW) with a relatively low δ18O signature to the deep waters in the low‐latitude Pacific during the LGM.