Distribution of magmatic rocks in eastern Yin'e Basin revealed by 3D gravity and magnetic inversion

Abstract

Magmatic activity has important influence on sedimentary cap structure, hydrocarbon generation and reservoir formation. There are multiple periods of volcanic activities in Yin'e Basin and it is of great significance to study the distribution of magmatic rocks in the basin for the prospective investigation of oil and gas resources. The residual gravity and magnetic anomalies are extracted from the original gravity and magnetic data in the eastern area of Yin'e Basin and used for 3D inversion. The spatial distribution of magmatic rocks in the study area is explained based on the inverted 3D density and magnetic susceptibility. The physical properties of the magmatic rocks in Yin'e Basin are distinctly different from their surrounding rocks in physical properties. The acidic igneous rocks are mainly low-density and medium-high magnetic (a few are weakly magnetic), and the intermediate-basic igneous rocks are mainly high-density and high-magnetic. The local low gravity anomaly with high magnetic anomaly area may be caused by the acidic igneous rocks intruding into the Carboniferous and Permian basement, while the local high gravity anomaly with high magnetic anomaly area may be caused by the intrusion of intermediate-basic igneous rocks. 14 weakly magnetic acidic igneous rocks, 16 medium-strong magnetic acidic igneous rocks and 25 intermediate-basic igneous rocks are inferred from the 3D inverted density and magnetic susceptibility. Acidic igneous rocks, which are distributed in the whole region, have large scale and mainly banded along the NEE direction. The intermediate-basic igneous rocks, which are generally small and most of them are equiaxed, are mainly distributed along the boundary of Zongnaishan-Chulu Uplift and Shangdan Depression, as well as the southern basin periphery of Shangdan Depression. The well-developed acidic magmatic rocks in Suhongtu and Shangdan Depressions, whose scale is relatively large, may be of great significance to the formation and distribution of oil and gas in Yin'e Basin.