Research On Structural Features Of Hanzhong Basin Based On Gravity Data

Hanzhong Basin begins from Wuhou Town in Mianxian in the west,extending toward east to Longtingpu in Yangxian and south of the Hanzhong Basin including Hanzhong City.It is about 116 kilometers long from east to west and 5 to 25 kilometers wide from north to south.The geographical coordinates are between 33°～33°18’N and 106°40‘～107°40’E.The predecessors’ research on Hanzhong Basin mainly focused on tectonic evolution and activity analysis of the basin’s peripheral faults.Due to the lack of seismic data and drilling data in the study area,the study of sediments and basement structures in Hanzhong Basin is relatively low.In order to be able to further study the structural characteristics of the Hanzhong Basin and understand the stratigraphic distribution characteristics of the Hanzhong Basin,it will provide a certain geophysical basis for the future research on the basic geology and structural geology of the Hanzhong Basin.Based on the previous research results in this area,this paper uses the existing gravity data,seismic data and regional geological data in the study area to conduct a comprehensive study on the fault structure system and stratigraphic development characteristics of Hanzhong Basin.The research results can provide a certain geophysical basis for the further study of basic geology and structural geology in the Hanzhong Basin,and play a certain reference significance.In this paper,the existing gravity data is systematically collected and sorted,and the gravity data is processed using relevant professional software to obtain the Bouguer gravity anomaly map and various gravity conversion parameter maps in the study area,combined with the basic geology of the study area.,Earthquakes and other related data have conducted a comprehensive study of gravity anomalies,analyzed the characteristics of the gravity field,inferred the cause of local gravity anomalies and the fault structure system in the study area,and discussed the development characteristics of the stratum in the study area.The main results and conclusions achieved in this article are as follows:(1)Gravity anomalies in the Hanzhong Basin are mainly distributed in the NE and NEE directions,reflecting the structural features of the western fault depression and the eastern shallow fault depression from west to east.The structural characteristics of the MiCangshan uplift zone and the Qinling orogenic belt also show the distribution and strike characteristics of the Hanzhong basin fault zone.(2)The local high gravity anomalies in the study area(11)are mainly caused by high-density formations and local uplift of the basement,and the local low gravity anomalies(11)are mainly caused by the local thickening of medium-acid,acidic intrusive rocks or Cenozoic caused.(3)The fault structure is relatively developed in the study area.The main fault trend is basically the same as the regional structural trend.The fault scale is large and the extension distance is long.It controls the scope,boundary and development of the stratum in the Hanzhong Basin.The scale of secondary faults is relatively small,they generally cut off the main faults,which are the faults within the sedimentary layer of the basin;the main faults in the study area constitute the main structural framework of the area,control the main boundaries of each structural unit,and control distribution characteristics of strata in the study area.(4)The surface of the Hanzhong Basin is almost entirely covered by the Cenozoic strata,with an average thickness of about 500m,and is generally thick in the west and north,and is thin in the east and south,mainly develop the lower paleozoic and Sinian strata,and Mesozoic strata have not been developed;the base of the Hanzhong Basin is mainly the metamorphic basement of the Archean-Lower Proterozoic.