Abstract:

The Tangbei fault zone is located in the northern Tangguzibasi sag, and has superimposing deformation features of segmented deformation and multi-stage activities. Based on defined interpretation of seismic profiles using fault-related fold theory and drilling data, this paper addresses the segmented deformation and activity characteristics of the Tangbei fault zone. The results show that detachment thrust faults and basement-involved thrust faults with fault propagation folds on hangingwall are well developed in the Tangbei fault zone. According to the shapes and deformation intensity, the Tangbei fault zone can be divided into three segments along strike, i.e.the western, central and eastern segments. From west to east, the deformation intensity and thrust angle decrease gradually. The Tangbei fault zone experienced four major tectonic activities in the Early Caledonian, the Middle Caledonian (phase I and III), and the Lately Caledonian-Early Hercynian. During the Early Caledonian and Middle Caledonian (phase I), the middle segment was highly active, and the seismic center gradually shifted westward. The multi-stage activities of the Tangbei fault zone are crucial for the formation of trap and, reservoir properties, as well as hydrocarbon migration.

Key words: Tangbei fault zone, fault-related fold, segmentation, growth index, hydrocarbon accumulation