The Formation and Evolution of the Paleo-Yunmeng Lake Group in the Jianghan Plain and Its Influencing Mechanism
Gu Yansheng
Guan Shuo
Li Yuenan
Abstract：The Paleo-Yunmeng Lake Group(PYMLG)in the Jianghan Plain has been significant of historical,geographical,cultural,and ecological environment research since the Xia and Shang Dynasties.Owing to rare historical records and limited borehole surveys,the cause and spatiotemporal pattern of the PYMLG remain ambiguous.Based on previous historical documents and borehole survey,this paper first conducted high resolution research on the boreholes sedimentary environment and reconstructed a 4 000-year evolution history of PYMLG.This study systematically revealed the relationship among the PYMLG sedimentary landform process and regional neotectonic movement,climate change,river channel migration and human activities.Multiple borehole analyses revealed the diverse sedimentary environments including riverbed,floodplain,lake,and delta facies,indicating a composite sedimentary system marked by a composite sedimentary system of"river-lake-delta".The distribution of sedimentary facies from west to east shows a certain pattern:the west is mainly floodplain and delta facies,the central part is mainly floodplain,delta and lake facies,and the east is dominated by lake facies.Paleogeographic reconstruction indicated that the PYMLG is always a landscape of changeable lake group developed in the interriver depressions in the Interior of Jianghan Plain.A 4 000-year evolution history of the PYMLG experienced four stages ranging from a peak period(Xia and Shang Dynasties)to a siltation period(Zhou,Qin,and Han Dynasties),a shrinkage period(Wei,Jin,and Southern and Northern Dynasties),and a breakup period(Tang and Song Dynasties).Our results indicate that the PYMLG is jointly influenced by the superposition of neotectonic movements,climate change,river flooding and migration of the ancient Yangtze River channels,and human activities:(1)The neotectonic subsidence created space conditions for the distribution of the PYMLG,and the main water and sand of the Yangtze River created the emergence of the PYMLG,but the subsequent southward migration of dominant channels of ancient Yangtze River determines the evolutionary process of the PYMLG;(2)the ENSO-related abnormal precipitation and river flooding have promoted the rise of PYMLG,and the expansion of the Jingjiang Delta has been the driver of the siltation and shrinkage of the PYMLG;(3)since the Tang and Song Dynasties,the shaping of the unified riverbed of the Jingjiang River and increasing embankments and reclamations of lakes accelerated the breakup of the PYMLG.This study first systematically reveal the spatiotemporal pattern of the PYMLG and its complex influencing mechanism,providing reliable answers to long-standing controversies and important references for the protection of current Jianghan Lake Group.
Keywords：changeable lake groupriver-lake-delta sedimentary systemrive channel migrationENSO-related floodinghuman activitysiltation processsedimentologyclimate change
Publication Date：2025-03-14
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：16( 830-845 )