Late Neogene evolution of the East Asian monsoon revealed by terrestrial mollusk record in Western Chinese Loess Plateau: From winter to summer dominated sub-regime
Late Neogene evolution of the East Asian monsoon revealed by terrestrial mollusk record in Western Chinese Loess Plateau: From winter to summer dominated sub-regime
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中国西部黄土高原陆生软体动物记录揭示的东亚季风晚第三纪演化：从冬季到夏季主导的亚制度
DOI：
10.1016/j.epsl.2008.07.038
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发表时间：
2008-10-15
影响因子：
5.3
通讯作者：
Pei, Yunpeng
中科院分区：
文献类型：
--
作者：
Li, Fengjiang;Rousseau, Denis-Didier;Pei, Yunpeng
越来越多的证据表明，东亚季风的爆发可以追溯到渐新世-中新世边界（约23 Ma）。然而，迄今为止，其演变过程仍鲜为人知。在这里，我们通过分析中国黄土高原 (CLP) 的陆生软体动物序列来研究其新近纪晚期的演化，涵盖 7.1 Ma 至 3.5 Ma 的时期。考虑到这些生物的现代生态要求，我们能够定义两组冷干旱（CA）和热湿（TH）物种，分别代表EA冬季和夏季季风变化，如先前在第四纪冰期-间冰期循环中定义的那样。这两组的变化表明 7.1-3.5 Ma 期间有两个不同的季风主导时期。首先，7.1~5.5 Ma期间，周期性为100 kyr的东亚冬季风占主导地位。其次，5.1~4 Ma期间，东亚夏季风占主导地位，周期为41 kyr。此外，我们的软体动物记录提供了宝贵的证据，证明中新世晚期-上新世从冬季季风主导到夏季季风主导的转变大约为 400 kyr，与从弱 100 kyr 到 41 kyr 的周期性转变相关。加强的冬季季风间隔具有100 kyr的周期性，与轨道尺度的全球冰量变化同时发生，同时青藏高原的隆起可能加强了冬季季风子区域。相反，巴拿马和印度尼西亚航道的关闭，与 5.1 至 4 Ma 之间的倾角变化有关，可能是观测到的频率为 41 kyr 的主导夏季风的主要强迫因素，有利于低纬度和高纬度之间的热量和水分输送，从而使 TH 软体动物在 CLP 中生长和发育。 (C) 2008 Elsevier B.V. 保留所有权利。
More and more evidence indicates that the onset of the East Asian (EA) monsoon can be traced back to the Oligocene-Miocene boundary (at about 23 Ma). However, the process of its evolution is still less well-known until now. Here we investigate its late Neogene evolution by analyzing a terrestrial mollusk sequence, from the Chinese Loess Plateau (CLP), covering the period between 7.1 and 3.5 Ma. Considering the modern ecological requirements of these organisms, we were able to define two groups of cold-aridiphilous (CA) and thermo-humidiphilous (TH) species, representing the EA winter and summer monsoon variations, respectively, as previously defined in the Quaternary glacial-interglacial cycles. Variations in these two groups indicate two different monsoon dominated periods during 7.1-3.5 Ma. First, between 7.1 and 5.5 Ma, the EA winter monsoon, with a 100-kyr periodicity, was dominant. Second, between 5.1 and 4 Ma, the EA summer monsoon dominated, with a 41-kyr periodicity. Furthermore, our mollusk record yields valuable evidence for a late Miocene-Pliocene transition of about 400 kyr from winter monsoon dominated towards summer monsoon dominated, associated with a periodicity transition from weak 100 kyr to 41 kyr. The strengthened winter monsoon interval, with a 100-kyr periodicity, is coeval with orbital-scale global ice-volume changes, in conjunction with the uplift of the Tibetan Plateau which probably reinforced the winter monsoon sub-regime. Conversely, closures of the Panama and Indonesian seaways, associated with changes in obliquity between 5.1 and 4 Ma, are probably major forcing factors for the observed dominant summer monsoon with 41-kyr frequency, favoring heat and moisture transports between low and high latitudes to allow TH mollusks to grow and develop in the CLP. (C) 2008 Elsevier B.V. All rights reserved.