Astronomical forcing and sedimentary noise modeling of lake-level changes in the Middle Eocene Chezhen Sag,Bohai Bay Basin,eastern China  

作　　者：Xuwei LUAN Jinliang ZHANG Na LI Tao CHEN Long SUN Xuecai ZHANG 

机构地区：[1]Faculty of Geographical Science,Beijing Normal University,Beijing 100875,China [2]College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China [3]Management Center of Oil and Gas Exploration,Sinopec Shengli Oilfield,Dongying 257000,China

出　　处：《Frontiers of Earth Science》2024年第2期446-459,共14页地球科学前沿（英文版）

摘　　要：The accurate determination of geological age is a key to understanding the history and process of paleolake evolution and oil and gas exploration in continental lake basin.However,improving the accuracy of geological age has always been a difficult scientific problem.A 609-m-thick,continuous lacustrine mudstone and sandstone succession in Chezhen Sag(eastern China)provides an ideal middle Eocene sedimentary record for establishing a high-resolution stratigraphic chronology framework.Based on spectrum analysis and sliding window spectrum analysis of the natural gamma(GR)logging data of well Che 271(C271)in Chezhen Sag,the periods of 405 kyr and 40.1 kyr were filtered by a Gaussian bandpass filter,and a“floating”astrochronological time scale(ATS)was established.The total number of 405 kyr eccentricity cycles were 13.6 and 40.1 kyr obliquity cycles were 138 which recorded from the upper member 4(Es4U)to the member 3(Es3)of the Eocene Shahejie Formation,and the depositional duration was 5.53 Myr.Correlation Coefficient(COCO)analysis and evolutionary Correlation Coefficient(eCoCo)analysis found that the optimal sedimentary rate of different strata.Sedimentary noise simulation revealed the history of paleolake water changes in the Middle Eocene in the Chezhen Sag,according to which four sequences are divided.The study shows that the lake level change of Chezhen Sag in the middle Eocene shows prominent 1.2 Myr cycles and an antiphase well-coupled relationship with obliquity modulation.Finally,we propose a model to explain the relationship between the orbital cycle and lake level change in the continental lake basin.When the obliquity of the earth increases,the middle and high latitudes of the earth will be closer to the sun,the direct sunlight will be higher,and the meridional sunshine will increase,thus accelerating the evaporation process of lake basin water.When the seasonal changes are obvious(maximum period of 1.2 Myr ultra-long obliquity),this effect is more significant.The relative lake level change based on

关 键 词：Chezhen Sag CYCLOSTRATIGRAPHY astrochronological time scale sedimentary noise 

分 类 号：P618.13[天文地球—矿床学]