| Abstract:The Qiangtang Basin had experienced strong magmatic activities and many magmatic bodies are exposed on the surface. Magmatic activity not only reflects the tectonic evolution characteristics of the basin, but also plays an important role in the formation and preservation of oil and gas in the basin. Therefore, the study of magmatic rock characteristics of the basin can not only provide a basis for the tectonic evolution of the basin, but also serve the investigation of oil, gas and mineral resources in the Qiangtang Basin. Based on high-precision airborne gravity and magnetic data from Qiangtang Basin, this paper first uses airborne gravity and magnetic potential field conversion processing and other methods to achieve the scope of buried rock mass. Then, a large number of rock physical properties collected in the field are statistically analyzed, and combined with geological and geochemical results, the typical airborne gravity and magnetic characteristics of rock mass are summarized. The analysis shows that volcanic rocks, intermediate acid intrusive rocks and basic and ultrabasic rocks are the main factors causing local anomalies of the elevated positive and heavy magnetic fields in the region. Based on the connection between physical characteristics and geophysical field, magmatic rock mapping is carried out, and the distribution of basic-ultrabasic rock mass, acid-neutral rock mass and volcanic rock mass are formed. The results show that the Mesozoic intrusive rocks and Cenozoic volcanic rocks are very developed in and around the investigation area, which are the most important geological factors causing the changes of gravity and magnetic anomalies in this area. It is of great significance for oil and gas accumulation to identify a number of hidden intrusive rock bodies in the South Qiangtang Depression and Puruo Kangri and Gladandong areas in the North Qiangtang Depression. A large number of buried volcanic rocks have been identified in the eastern part of North Qiangtang Depression, and it is speculated that there may be low-density anomalous bodies in the deep part. The research results improve the understanding of the distribution characteristics of magmatic rocks, and provide a more reliable basis for the regional geological structure, basin evolution and oil and gas resources evaluation. |
