Cenozoic Tectonic Difference and Its Formation Mechanism of the Tiantai Slope in the Xihu Sag

doi:10.19657/j.geoscience.1000-8527.2022.081

Abstract

Abstract:

The Tiantai slope is located in the southern section of the western slope of the Xihu Sag. After 35 years of exploration, only four wells have been drilled and no commercial discoveries have been made, and the poorly-known geological conditions have restricted the local oil and gas exploration. Based on three-dimensional (3D) seismic data interpretation and comprehensive geological analysis, the Cenozoic tectonic style of the different sections of the Tiantai slope, and its geometrical features and formation mechanism are systematically summarized. From north to south, the Tiantai slope is characterized by a complex slope in the northern section (controlled by two-way faults), a complex gentle slope in the middle section (controlled by antithetic faults), and a simple gentle slope in the southern section (controlled by a synthetic fault). The regional structural differences of the Tiantai slope are closely related to its Cenozoic tectonic evolution. From Paleocene to Eocene, the differential extension may have controlled the different degrees of fault development and structural styles in the northern, middle and southern sections of the Tiantai slope. A special arc-shaped fault development zone may have formed between the northern and middle sections.

Key words: tectonic difference, extensional transformation, arc-shaped fault, Tiantai slope, Xihu Sag

CLC Number:

P618.13

QI Peng, GUO Gang, CUI Min, WANG Xin, LI Feng, LI Linzhi. Cenozoic Tectonic Difference and Its Formation Mechanism of the Tiantai Slope in the Xihu Sag[J]. Geoscience, 2023, 37(02): 307-315.

Figures/Tables 7

Fig.1 Map showing the structural branches and fault distributions in the Tiantai slope[8]

Fig.2 Seismic profile showing interpreted structures of the Tiantai slope (northern branch)

Fig.3 Seismic profile showing interpreted structures of the Tiantai slope(middle branch)

Fig.4 Seismic profile showing interpreted structures of the Tiantai slope (southern branch)

Fig.5 Tectonic activity differences between the middle and southern branch of the Xihu sag

Fig.6 Summary diagram of Cenozoic tectonic evolution in the southern part of the Xihu sag

Fig.7 Schematic diagrams showing the Paleocene-Eocene fault development of the Pinghu and Tiantai slope in the Xihu sag

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