Abstract:
Based on seismic profiles, aeromagnetic data, drilling data and field outcrops, Guang’an-Shizhu paleo-uplift was discovered in the eastern Sichuan Basin and demonstrated in detail. It is believed that the paleo-uplift is an extension of the central Sichuan paleo-uplift to the east. By restoring the thickness of Longwangmiao Formation in Sichuan Basin, the planar distribution of Guang’an-Shizhu paleo-uplift was demonstrated, generally shown as a NW-SE trending nose structure, characterized with far EW-trending extension, narrow SN-trending expansion, and local paleo-highs in the east. The fine interpretation results based on logging and seismic data show that the evolution of Guang’an-Shizhu paleo-uplift began in the Early Sinian and ended in the Late Cambrian. During the Sinian to Cambrian period, the sedimentation in Guang’an-Shizhu paleo-uplift was characterized by overlapping from the slope to the core, fold deformations were formed under multiple tectonic compressions, and a paleo-trap with small uplift was formed in Shizhu area on the east side of the paleo-uplift. Based on the development characteristics of Guang’an-Shizhu paleo-uplift, the reconstructed geological process shows that the paleo-uplift has undergone four evolution stages, including the prototype stage in the Early Sinian, the development stage from the Late Sinian to the Middle Early Cambrian, the adjustment and formation stage from the Late Early Cambrian to the Late Cambrian, and the uplifting activity termination stage in the Ordovician. The formation of Guang’an-Shizhu paleo-uplift was controlled by the factors such as basement uplift, plate movement, tectonic activity and granite emplacement. In the paleo-uplift development area, a large scale of mound and shoal deposits were developed in Dengying Formation, Longwangmiao Formation and Xixiangchi Formation, and transformed by late dolomitization and epigenic karstification. They are high-quality reservoirs in the eastern Sichuan Basin and are of important petroleum geological significance.