南黄海中西部晚更新世沉积地层结构及其意义

Late Pleistocene Sedimentary Stratigraphic Structure and Its Implication in the Central and Western Areas of Southern Yellow Sea

利用1992-1993航次和1999航次获得的2000多公里的浅地层剖面资料,结合QC2钻孔岩芯的测年数据,对南黄海中西部海域晚更新世沉积地层结构进行了分析,并对地层进行了地质年代标定。研究结果表明,南黄海中西部晚更新统可划分出8个地震地层单元(U1～U8),它们所反映的相对海平面变化与全球海平面变化基本上相一致。根据沉积厚度、QC2孔岩心和地震反射结构特征推测,晚更新世早期(氧同位素5e)QC2孔附近区域发育古长江水下三角洲;而晚更新世中期(氧同位素3期),研究区西部也发育古三角洲沉积,究竟是古长江还是古黄河形成的还有待于进一步研究。南黄海北部盆地边界断层的构造活动一直延续到全新世初期,在一定程度上影响了来自西部沉积物的空间分布特征,并对晚更新世海平面上升时岸线向陆的推进、大面积湖泊的形成起了重要作用。

Based on more than 2 000 km of subbottom profiling data collected during 1992 to 1993 cruise and 1999 cruise and the dating data of sediment from core QC2, the late Pleistocene sedimentary stratigraphic structure in the central and western areas of southern Yellow Sea was analysed, and the geological ages of different strata were determined. It is shown from the study results that the late Pleistocene stratum in the central and western areas of southern Yellow Sea can be divided into 8 seismic stratigraphic units (U1 to U8), and the relative sealevel changes reflected by 8 units are basically consistent with the global sealevel changes. It is inferred from the sediment thickness, sediment structure of core QC2 and seismic reflection structure that the paleoYangtze River submerged delta was developed in core QC2 neighboring area during the early stage of late Pleistocene (about oxygen isotope period 5e); the paleodelta was developed in the western study area during the middle stage of late Pleistocene, but whether it is paleoYangtze River delta or paleoYellow River deta remains to be further studied. The tectonic activities of boundary faults of the northern basin of socthern Yellow Sea lasted until the early Holocene to influence the spatial distribution characteristics of sediment coming from the west and to play an important role in the shoreward advance of paleoshoreline and the formation of extensive lake during the transgression in late Pleistocene.