Gravity And Magnetic Field And Tectonic Characteristics Of The Chukchi Borderland In The Arctic

Chukchi Borderland is an underwater plateau about 600 km long from north to south and400 km wide from east to west,located in the western Arctic Ocean,where the Chukchi Continental Shelf meets the Canada Basin.The Arctic has great potential for oil and gas resources,which is an important strategic field for the future development of oil and gas industry at home and abroad.Chukchi Borderland is a necessary place for every Arctic expedition in China.However,due to the limitations of climatic conditions and geographical location,it is difficult to obtain geological data,and previous studies on it are relatively low.In order to study the geological structure characteristics of Chukchi Borderland,this paper systematically collects,processes and explains the gravity and magnetic data of Chukchi Borderland and its adjacent areas.The transfer parameter maps of gravity and magnetic anomalies,such as moving average anomaly map,vertical second derivative anomaly map,magnetic pole anomaly map of variable magnetization dip Angle and total horizontal derivative anomaly map,are obtained.In this paper,the gravity and magnetic field characteristics of Chukchi Borderland are comprehensively studied in combination with geological and seismic data,and the fault structural characteristics of Chukchi Borderland are deduced,and the tectonic units are divided.The main achievements and conclusions are as follows:(1)There are two obvious characteristics of free air gravity anomaly in the study area: The anomaly trend is macroscopically NE direction and nearly SN direction,and the general characteristics are parallel distribution of high gravity anomaly zone and low gravity anomaly zone;There is a big difference between high and low gravity values,most of which are the reflection of trough and ridge,and the cascade zone is relatively developed between high and low gravity values.(2)The magnetic anomalies of Chukchi Borderland are very obvious and can be generally divided into three parts: In the west,the gradient changes are steeper and spread in the NE direction,and the ladder zone between the high value and the low value is relatively developed.The magnetic anomaly in the NE direction spread in the northwest is consistent with the anomaly in the northwest of the study area,which should be a part of the magnetic anomaly zone of the Mendeleev ridge,and it is presumed that this area also belongs to the oceanic crust.The gradient changes gently in the middle and south of the study area,and the magnetic negative anomalies are the main ones.The high magnetic anomaly zone is only found in the Northwind basin,but the distribution range is small.The eastern and northern regions are also dominated by magnetic negative anomalies,but the abnormal characteristics on both sides are obviously different at the boundary.The abnormal amplitude in the region is low and the gradient changes gently,while the abnormal amplitude outside the region is high and the gradient changes steeply.This obvious linear transition zone is the boundary position of the eastern and northern regions.(3)The internal structure of Chukchi Borderland is complex and fractured.There are three main faults: the main faults are nearly SN,nearly EW,NW and NE,with large scale and long distance,which mainly control the boundary between them and the outside.The secondary faults are mainly distributed in the direction of near SN,NE and NW,with relatively small scale and short extension distance.The near NW faults usually cut off the near SN and NE faults,mainly to control the boundary of the internal structural units.(4)Based on the comprehensive study of Chukchi Borderland,four tectonic units are divided into Chukchi Plateau,Northwind Basin,Northwind complex tectonic belt and Northwind Ridge.