Early interglacial carbonate-dilution events in the South China Sea: Implications for strengthened typhoon activities over subtropical East Asia
Early interglacial carbonate-dilution events in the South China Sea: Implications for strengthened typhoon activities over subtropical East Asia
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南海早期间冰期碳酸盐稀释事件：对亚热带东亚台风活动加强的影响
DOI：
10.1016/j.quascirev.2015.08.007
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发表时间：
2015
影响因子：
4
通讯作者：
Yang Wenguang
中科院分区：
文献类型：
--
作者：
Huang Enqing;Tian Jun;Qiao Peijun;Wan Sui;Xie Xin;Yang Wenguang
南海中国海北部陆坡晚第四纪海洋沉积记录的汇编证实，在全新世早期，沉积碳酸钙浓度在11.0~8.5ka BP之间下降了15%-50%。这一低碳酸盐%事件发生在地区海平面从−50米上升到−10米的时候，淹没了大片大陆架，特别是台湾海峡附近和内部的大陆架。这一事件与上陆坡的整体沉积速率显著增加和细粒碎屑的相对丰富有关。沉积物物源分析表明，与全新世其他时期的陆源沉积背景相似，低碳酸盐事件期间陆源物质的输入主要来自台湾，吕宋的贡献较小。两个类似的低碳酸盐%事件，分别来自海洋同位素阶段5.5和7.3的开始，也被识别出来，指出了相似的原因。虽然碳酸盐溶解和碳酸盐堆积速率不是主要原因，但陆源输入和稀释的增加被认为是早期间冰期反复发生的低碳酸盐%事件的主要原因。我们进一步推测，在间冰期早期，由于台风活动增强，台湾和吕宋的河流泥沙流量增加，这两个末端的大量细粒沉积物可能通过表层和深海洋流输送到南海北部陆坡。东亚台风活动在全新世早期增强的猜想，得到了盛行拉尼娜现象的西太平洋暖池区高海洋热含量的支持。
A compilation of many late Quaternary marine sediment records from the northern South China Sea (SCS) continental slope confirms 15–50% reductions in sedimentary calcium carbonate concentrations between 11.0 and 8.5 ka BP in the early Holocene. This low carbonate% event occurred at a time when the regional sea level rose from −50 m to −10 m, which drowned large areas of continental shelves especially those near and within the Taiwan Strait. This event is associated with a significant increase in bulk sedimentation rates on the upper continental slope and the relative abundance of fine-grained detritus. Sediment provenance analyses suggest a dominant terrigenous input from Taiwan and a minor contribution from Luzon during the low carbonate% event, similar to the background terrigenous deposition in other periods of the Holocene. Two comparable low carbonate% events, respectively from the beginning of marine isotope stages 5.5 and 7.3, have also been recognized, pointing to similar causal factors. While carbonate dissolution and carbonate accumulation rate should not have been responsible, increased terrigenous input and dilution is considered as the main cause for the recurrent low carbonate% events in early interglacials. We further hypothesize that, during early interglacials, fluvial sediment discharge from Taiwan and Luzon intensified due to stronger typhoon activities, and massive fine-grained sediments from these two end members may have been transported to the northern SCS continental slope via surface and deep ocean currents. The conjecture of strengthened typhoon activities over East Asia during the early Holocene is supported by high ocean heat contents in the West Pacific Warm Pool area with the prevailing La Niña-like conditions.