Quaternary Stratigraphic Architecture And Sedimentary Evolution In Western Of Xiong'an New Area

Xiong'an New Area located at transition zone of piedmont area of Taihang Mountain and Huabei Plain.The western of Xiong'an New Area has a wide,thick and continuous Quaternary deposition,which was brought by erosion accumulation of upstream.It is a good record of paleo-climate changes.This paper mainly studies Quaternary stratigraphic architecture of borehole GB014 in western of Xiong'an New Area.The main conclusions are as follows:(1)System demagnetization and the fruits of previous research were conducted to establish a chronological framework.The depths of Matuyama/Brunhes and Guass/Matuyama boundary are 33.8m and 135 m,respectively.There are 4 normal magnetozones and 3 reverse magnetozones,the normal magnetozone N1(0 ? 33.8m),N2(60.7 ?66.0m),N3(94?116.8m),N4(135?140m)identified here can be correlated with C1 n,C1r.1n,C2 n,C2An.1n,repectively.The reverse magnetozones R1,R2,R3 can be correlated with C1 r.1r,C1 r.2r,C2 r.1r,respectively.(2)From bottom to top,according on the chronological framework and sedimentary facies,five sedimentary units have been identified: Unit ?,with the depth of 146.6?200m and sedimentary rate of 49.0m/Ma,whose age is 2.81?3.90 Ma,has been dominated by alluvial fan facies with coarse grain sediments.Unit ?,with the depth of 108?146.6m and sedimentary rate of 27.6m/Ma,whose age is 1.88?2.81 Ma,has been dominated by flood plain facies with fine grain sediments.Unit ?,with the depth of 57.6 ? 108 m and sedimentary rate of 58.6m/Ma,whose age is 1.02?1.88 Ma,has been dominated by braided channel facies with coarse particle sediments.Unit ?,with the depth of 35.8?57.6m and sedimentary rate of 94.8m/Ma,whose age is 0.79?1.02 Ma,has been dominated by flood plain facies with fine grain sediments.Unit?,with the depth of 0?35.8m and sedimentary rate of 45.3m/Ma,whose age is 0?0.79 Ma,has been dominated by flood plain interbedded with crevasse fan facies.(3)In borehole GB014,two tectonic movements occurred at 2.81?3.90 Ma and 0.79?1.88 Ma have been recorded since late Pliocene,and sediment provenance has been changed probably during 1.02?1.88 Ma.The piedmont area in the Taihang Mountain have deposited widely two layers of coarse grain sediments resulted by these two tectonic movements,and sand layers in Middle and Late Pleistocene were mainly related to the marine transgression in Bohai Bay and the enhance of East Asian monsoon system.