The Research On Meso-and Neoproterozoic Lithofacies-Paleogeographical Characteristic Based On Geophysical Signature In Jizhong Depression

On the basis of full collecting, and sorting various outcome from predecessor in the central depression, applying sedimentology and fundamental principle and approaches of basin analysis, combined with data analyzing in field geology section, logging data and seismic data, the thesis has made a systematic and ingoing research in depositional system type, attribute and lithofacies.palegeographical characteristics in the region of interest following careful study on areal tectonic setting.The Meso- and Neoproterozoic in JiZhong totally identified 2 types of depositional systems group and 7 types of depositional systems. Respectively, they are carbonate platform depositional system, coastal depositional system, shelf depositional system and storm depositional system, which belong to marine sedimentary systems group, and alluvial fan depositional system, fluvial depositional system and lacustrine depositional system, which belong to terrestrial depositional system group.Finally, according to the characteristics of sedimentary system types and evolution, sedimentary facies pattern, combing the characteristics of regional tectonic background in central hebei, the thesis has established Meso. and Neoproterozoic ithofacies.paleogeographical map by the new correlation of strata scheme reflecting different periods paleogeoraphical aspect. On the west and north of the gleam of QuYang.JinXian.HenShui.CangZhou there is no depositional area in most Meso. and Neoproterozoic period, except for GaoYuzhuang group and WuMishan group which are wide.ranging marine invasion time. In the early stage of marine invasion, the great wall epoch mainly developed fluvial and offshore.shallow facies with thin deposition rock. GaoYuzhuang group was the most scale marine invasion in the research region, mainly grew infra.shallow dolomite. JiXian epoch was the thickest deposition period and the WuMshan group sedimentation played a main role in this period, whose marine invasion scale secondly only to GaoYuzhuang series, with cryptal gal dolomite developing in restricted sea basin with affluent stromatolite and creature. The region has experienced one more marine regression since HongShuizhuang group period, resulting in the basin area reduction. The JiXian epoch late period chiefly settled mud and dolomite flat resulting from steady hydrodynamic condition, the cessation of deposition emerged afterwards, and then, the earth crust descended again, causing another marine invasion lasting into the late period of XiaMaling period. The last marine ingression occurred in the QingBaikou epoch, when the sea water intruded into low.lying district, JiZhong took sedimentation, the fluvial and offshore.neritic ocean deposition playing a main role. JiZhong developed sand and arenaceous politic flat and shore land sand beach facies with disarray and low.mature rock.