Study On The Northern Border And Tectonic Division Of Pearl River Mouth Basin By Using Satellite Gravity Data

Pearl River Mouth Basin is located in the northern South China Sea continentalshelf-slope area, an area of complex geological structure. Pearl River Mouth Basin formed inthe background of the passive continental margin development and evolution. It is a Mesozoicand Cenozoic extensional Basin, which developed from the the Paleozoic Caledonian foldbasement and restructured in the Mesozoic era. Pearl River Mouth Basin is a north-easttrending basin which is roughly parallel to the coastline of the South China sea andgeographically belongs to the edge of the South China underwater extension. The basin ismainly composes of five tectonic units: Northern uplift, North depression, Central uplift,Southern depression, and Southern uplift. The Pearl River Mouth Basin Present north-southzonation and stuff block pattern. Predecessors have studied a lot on the structuralcharacteristics and evolution of the Pearl River Mouth Basin. Due to lack of seismic data,drilling data and other geophysical data, the northern border region of the Pearl River MouthBasin were less studied. In this article,the topography data, satellite gravity data,physicalproperty data and geology data in the Pearl River Mouth Basin are collected, and thepetrophysical variation laws of the layers and rocks are analysised. Based on the analysis andprocessing of the satellite gravity data, the northern boundary and structural units of the PearlRiver Mouth Basin were also redrawed. With gravity anomaly NVDR_THDR technology andEuler deconvolution mothod, faults on both sides of the north boundary of the Pearl RiverMouth Basin were identified, and the the length,the depth, the trend and the characterizationsof the faults were inversed. The ‘depression’ and ‘uplifting’ structures were identified byresidue gravity abnormal and gravity abnormal vertical first derivative. By comprehensivestudy on breaking, depression and uplift, the northern tectonic units of the Pearl River MouthBasin were re-divided. As the results show, the new northern boundary of the Pearl RiverMouth Basin and northern uplift zone is about20km to north of the old boundary, and itmeans that Huizhou sag, Xijiang sag, Enping sag, Hanjiang sag and Lufeng sag are4365km2,1936km2,1416km2,3143km2,1614km2bigger respectively than before, and the new sag areain total is12574km2. This study provides geophysical basis for the furture study on the structural divisions of the northern part of the Pearl River Mouth Basin, and for achievementof a breakthrough on oil and gas exploit.