末次盛冰期以来中国东部陆架层序地层研究现状

Current Research of Sequence Stratigraphy in Eastern China Shelf since the Last Glacial Maximum

本文中笔者总结了多年来国内外中国东部陆架晚更新世地层结构研究的主要认识,系统阐述了层序地层与沉积环境演化。中国东部陆架沉积物输运量高、沉积作用受海平面变化影响强烈,是分析晚更新世沉积演化史的理想场所。末次盛冰期(22kaBP)之前,海面的持续下降形成以浅海、三角洲及海陆交互沉积为主的强制海退体系域。进入盛冰期后,一个新的旋回开始,在海退体系域之上,相继形成了包括低位体系域、海侵体系域及高位体系域在内新的4级层序:22～15kaBP盛冰期时期,海面降至最低,形成低位体系域,包括陆架深切河湖沉积及风成沉积,以及陆架边缘三角洲和潮流砂体等;盛冰期结束的15～7kaBP时期,全球海平面快速上升,形成含河道充填、湖泊、盐沼、潮坪、潮流砂体及浅海沉积的退积型海侵体系域;约7kaBP以后,海面与现今海面位置基本相当,形成高位体系域,主要为三角洲和潮流砂等近岸陆架的沉积。

The correlations between sedimentation and relative sea-level changes in the Eastern China Shelf region play a role in analyzing the Late Pleistocene sedimentary evolution. The relative sea-level continued to drop since the Last Glaciation. While in the Last Glacial Maximum （LGM） it starts a new cycle, and a fourth order sequence was formed in the West Pacific shelf. This paper summarizes the major achievements of many researchers obtained from the Eastern China Shelf in many years. It discusses the structure of strata, sequence and evolutions of sedimentary environments since the Late Pleistocene. The sequence with LST, TST and HST formed on the top of FRST of the former sequence. （ 1 ） Before 22 ka BP, with the decline of sea-level, the FRST was formed by the sediments of shallow sea, delta, and alternate terrestrial and marine facies. （2） During 22 - 15 ka BP of the LGM period, the incised-valley fills, terrestrial lakes and aeolian sediments on continental shelf, delta and tidal sand on shelf edge were deposited and the LST was established. （ 3 ） The rapid rise of sea-level from 15 to 7 ka BP made the TST formed in sediments of infilled river channels, lakes and salt marshes, tidal flats, tidal sand and shallow sea. （4） In the period of highstand after -7 ka BP, HST was produced mainly by delta and tidal sand on inshore shelf.