东海陆架晚第四纪层序地层及其沉积环境

LATE QUATERNARY SEQUENCE STRATIGRAPHY AND SEDIMENTARY ENVIRONMENT OF EAST CHINA SEA CONTINENTAL SHELF

受全球性气候变化影响,晚第四纪以来东海陆架经历了多次海平面升降过程,在沉积地层中留下了明显的地质记录。根据穿越东海陆架的浅地震剖面解释研究,海底以下约120ms时间深度内可识别出6个主层序反射界面,即QT0、QT1、QT2、QT3、QT4和QT5界面,5套反射层序(反射波组),据反射层序的结构及地震相特征和与区内的钻孔地质资料对比分析,可见每套反射层序在沉积环境上均由一个海进海退沉积序列组成。以层序地层学为理论基础,在对中更新世以来的地层层序及其沉积环境条件分析研究基础上,建立了东海陆架晚第四纪地层层序及其发育模式,以期为东海陆架区晚第四纪地层发育层序提供初步认识。

Sea level fluctuations caused by globe climate change during Late Quaternary are the main reason to form the stratigraphic sequences of the sediments on the East China Sea Continental Shelf.6reflections,i.e.QT0,QT1,QT2,QT3,QT4 and QT5,or 5stratigraphic sequences,can be recognized on the seismic profiles across the whole continental shelf of East China Sea for the sediments 120 mbelow the sea bottom.Comparing the structure and reflection characteristics of the sequences with drilling data,it is found that every stratigraphic sequence is composed of a regressional sub-sequence and a transgressional sub-sequence.Using sequence stratigraphy as a tool,this paper described the stratigraphic sequences since Middle Pleistocene,and the depositional environment of the region was deduced accordingly.A conceptual model was then proposed as a clue for stratigraphic correlation.