南海北部末次冰盛期晚期以来冰融水与气候事件记录：长链脂肪醇陆源输入指示

摘要

The distribution andδ13C composition of long chain n-alcohols from the late Last Glacial Maximum (LGM) to the Holocene in Site 4B core sediments from the continental slope of the northern South China Sea was discussed in this paper. The distribution of carbon preference index (CPI, 10.49~24.56), average chain length (ACL, 28.91~29.99) and average carbon isotope (–28.85‰±0.97‰ to–32.92‰±1.38‰) of long chain n-alcohols reflected a C3 higher plant source and a dominated n terrigenous input of organic materials into the sediments. The relatively low terrigenous input was related to the extensive melt water pulse (MWP) events (19ka-MWP, MWP-1A and MWP-1B), and Bølling-Allerød (B/A) warming event from the end of the LGM to the end of the Late Pleistocene in Site 4B sediments (65~102cm, 19.343 to ~ 11.636 ka BP) without glacial period/interglacial period cycle. However, the distribution of the terrigenous input reflected intensified/weakened winter monsoon/summer monsoon cycle during the late LGM and Holocene, with the winter monsoon maximum periods recorded during the late LGM and the summer monsoon maximum periods in about 9.940ka BP. Compared with the cycle climate change of global glacial period/interglacial period, the distribution of the terrigenous input from the end of the LGM to the end of the Late Pleistocene in Site 4B sediments (19.343 to~11.636 ka BP) reflected ambiguous regional comparability, probably related to the regional environmental activity in low latitudes.%对南海北部陆坡 Site4B 站位末次冰盛期晚期至全新世(30~120cm)长链脂肪醇分布及碳同位素组成进行讨论,结果表明,长链脂肪醇碳优势指数(CPI,10.49~24.56)、平均碳链长(ACL,28.91~29.99)以及平均碳同位素组成(–28.85±0.97‰~–32.92±1.38‰)均反映了陆源 C3植物来源,代表了沉积物中陆源输入。Site4B 站位末次冰盛期末至晚更新世末(65~102cm,19.343~11.636ka BP)普遍较低的陆源输入均响应了大规模的冰融水事件19ka-MWP、MWP-1A、MWP-1B (melt water pulse, MWP)和暖气候事件(B/A事件),不具冰期/间冰期旋回变化特征。在末次冰盛期晚期(102~120cm)和全新世(30~60cm,10.490~约7.104 ka BP)陆源输入的旋回变化均反映了加强/减弱的冬季风/夏季风旋回变化,其中在末次冰盛期晚期记录一次冬季风最强事件,在早全新世至9.940ka BP记录一次夏季风最强事件。通过Site4B站位末次冰盛期末至晚更新世末(19.343~约11.636 ka BP)千年尺度陆源输入分布特征和全球冰期/间冰期旋回气候变化的对比,发现不具明确的区域对比性,可能受到低纬地区局地环境的作用所致。