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Geoscience ›› 2021, Vol. 35 ›› Issue (05): 1471-1479.DOI: 10.19657/j.geoscience.1000-8527.2021.101

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Study on Gravity and Magnetic Response Characteristics Based on Forward Modeling: An Example from Permian Volcanic Rocks in the Western Sichuan Basin

PAN Li1,2(), HE Qinglin2, LIANG Shengxian1,3(), CHEN Xianjie1, CHEN Wen4, XIE Guanghua4, LI Yang2, XIA Qing2, MA Qian2   

  1. 1. College of Geophysics, Chengdu University of Technology, Chengdu, Sichuan 610059, China
    2. Exploration and Development Research Institute, PetroChina Southwest Oil and Gas Field Company, Chengdu, Sichuan 610041, China
    3. Chengdu Center, China Geological Survey, Chengdu, Sichuan 610081, China
    4. Communication and Information Technology Center, PetroChina Southwest Oil & Gas Field Company, Chengdu, Sichuan 610051, China
  • Received:2021-03-02 Revised:2021-06-07 Online:2021-10-10 Published:2021-11-04
  • Contact: LIANG Shengxian

Abstract:

Recent exploration results of deep volcanic rocks in the western Sichuan Basin indicate that the Permian volcanic rocks in this region have great exploration potential. However, it is still difficult for seismic exploration methods to describe the distribution of volcanic rocks in detail. Therefore, it is necessary to provide more favorable evidence for volcanic exploration through gravity and magnetic methods. This paper takes advantage of the latest gravity and magnetic data to analyze the characteristics of gravity and magnetic properties in the western Sichuan Basin based on existing geological knowledge, and summarizes the gravity and magnetic response characteristics of deep volcanic rocks in this region based on the gravity and magnetic forward simulation results of different models. Through the processing of measured gravity and magnetic data, the distribution characteristics of faults and the distribution law of high magnetic anomalies in the study area are analyzed. The results show that: (1) The forward modeling results show that magnetic anomalies are sensitive to volcanic rocks, and gravity anomalies are sensitive to faulted structures, but not to volcanic rocks. (2) Magnetic anomaly has an outstanding ability to depict volcanic rocks, which can identify the volcanic rocks with a thickness of more than 45 m, but it is difficult to identify the buried depth and lithology changes of volcanic rocks. (3) The fault structures interpreted by gravity anomalies in the study area are in good agreement with the known fault structures in the study area. Meanwhile, the distribution of volcanic rocks described by magnetic anomalies is comparable to the existing understanding. It is concluded that gravity and magnetic exploration plays an important role in volcanic exploration in Sichuan Basin. Gravity exploration can identify the development of deep and large faults that control the distribution of volcanic rocks, and magnetic exploration can identify the plane distribution characteristics of volcanic rocks and quickly delineate the favorable target areas, thus providing favorable gravity and magnetic basis for volcanic exploration.

Key words: Western Sichuan Basin, Permian volcanic rock, gravity and magnetic response, forward modeling, deep large fault

CLC Number: