Tectonic-paleogeomophic Evolution In Guaizihu Depression,Yin-E Basin

The Guaizihu depression is located in the northern part of the Yin-E Basin,it has a double-layer geological structure of rift-depression.In the fault depression period,the basin was a typical single fault-type basin.In the plane,the fault depression was divided into the south,middle and north depression belts;The area of the middle depression in the study area is about 800 km~2,and the maximum depth is about 5,000meters;The area of the south depression in the study area is about 500 km~2,and the maximum depth is about 6200 meters;The degree of geological exploration in the study area is low.In recent years,drilling has shown good oil and gas properties.Comprehensive analysis of basin tectonic-paleogeomophy is the premise for studying the characteristics of basin sedimentary filling and reservoir development,and is of great significance for oil and gas exploration.This paper made good use of geophysical data?drilling and well logging data,and under the guidance of structural geology,seismic stratigraphy and sedimentology theory,combined with regional tectonic background,comprehensively studied the tectonic-paleogeomophy features of the Guaizihu depression.Seismic data accurately indicates that there are three levels of faults in the study area:primary basin fractures,secondary sediment-control faults,and tertiary regulating faults;The tectonic evolution stages of the study area can be divided into fault depression period?transition period and depression period.And the tectonic activities during fault depression period have weak-strong-weak trends.The characteristics of boundary fault activities determine the structure of the basin.The direction of the middle depression in the Guaizihu depression is NNE,it is a dustpan-like fault depression of faulting in east and overlapping in west.While the south depression is just the opposite.Using 3D seismic data to analyze the key interface characteristics and seismic filling characteristics in the study area to qualitatively identify the paleo-geomorphy,combining the tectonic evolution characteristics of the study area to analyze the development and evolution rules of ancient geomorphology,to quantitative restoration of original sedimentary features,we used erosion thickness restoration and compaction correction and so on.The comprehensive analysis shows that there are obvious paleo-geomorphologic characteristics of the gentle slope belt,the depression belt and the steep slope belt in the east-west direction of the Guaizihu depression.Paleogeomorphic units with different evolutionary stages also have large differences;In the early period of fault depression,the geomorphic pattern of multiple semi-mantles coexists.With the continuous development of boundary faults and the weakening of the activity of the secondary faults in the basin,the original multiple semi-mantle paleo-geomorphic structures gradually evolved into a typical dustpan-like fault depression lake basin.The landforms of the uplifts and depressions have gradually become gentle.The stages and intensity of Yanshan movement tectonics determine the evolution of the basin structure;The development of key faults affected the regional division and the characteristics of the zone division of the interior paleo-geomorphy.The structural erosion in the margins of the basin and in the interior of the basin affects the inclination of the slope and the filling and filling pattern in the basin.