The Study On Stratigraphic Sequences And Change Of Palaeoenvironment Since Late Pleistocene In Baiyangdian Area

The paper seclected the quaternary stratigraphic in Baiyangdian aera as researchobject divided age stratum in Baiyangdian aera according to lithology change featuresand OSL dating results and established the stratigraphic sequence. On the basis of thecharacteristics of grain sizing analysis and magnetic susceptibility analysis, discussedthe evolution trend of paleoenvironment since Late Pleistocene in Baiyangdian.This paper analyzed the four stratigraphic sections grain size characteristics andmagnetic susceptibility, by describing the sediment lithology and use of particle sizeanalysis and magnetic susceptibility analysis and compared with the results ofprevious studies, the main conclusions are as follows:1. OSL dating results shows that the stratigraphic section record depositionprocess since the Late Pleistocene, the bottom of Ouzhuang formation of upperPleistocene Series is129.4±5.2kaBP, borderline of Holoeene and Late Pleistocene10kaBP.2. Ouzhuang formation can be divided into two stages, on the basis of lithologyfeatures and OSL dating results. The lower of Ouzhuang formation (129.4±5.2～60.9±3.0kaBP): The main sedimentary facies aer river facies and fluvial facies,sediments are mainly clay, silty and clayey silt; The upper of Ouzhuang formation（60.9±3.0～10kaBP）: sedimentary facies are mainly fluvial facies, lake facies andfluvial facies, sediments are clayey silt, silty and fine sand and clay, with calcium TBand Gastropoda; the Holoeene serise can be divided three stages,the lower of Holoeeneserise(10～7.5kaBP):the sedimentary facies is fluvial facies, sediments are mainlysilty clay, silt, developed colored clay layer, the middle of Holoeene serise(7.5～2.5kaBP): sedimentary facies are mainly fluvial facies and lake facies, sediment are siltyclay and clayey silt, developed colored clay layer widely, Gastropoda and Musselsfossil are rich; the upper of Holoeene serise(2.5ka～): the sedimentary facies is fluvialfacies, sediment are silty clay and clayey silt.3. On the basis of the characteristics of magnetic susceptibility analysis andcompare with the results of previous studies, discussed the evolution trend ofpaleoenvironment since Late Pleistocene in Baiyangdian. The climate characteristicalis the Interglacial climate of the early-Late Pleistocene, the late-Late Pleistoceneclimate turn into cold, called glacial climate.The Holoeene climate has gone throughcold dry-Megathermal-cool stages. Baiyangdian area since late pleistocene sediments of magnetic susceptibility and deep sea oxygen isotope records exist goodcorresponding relation by studies.