Method for determining activity stages of underground small and medium scale strike-slip faults in basin

Abstract

The invention discloses a method for determining activity stages of underground small and medium scale strike-slip faults in a basin. The method includes the following steps: defining longitudinal stratification characteristics of the strike-slip faults and determining development horizons of underlying vertical strike-slip segments and overlying en echelon normal faults of the strike-slip faults; obtaining slip directions of the underlying vertical strike-slip segments and paleostress environment corresponding to activity of the underlying vertical strike-slip segments; obtaining slip directions of the en echelon normal faults and paleostress environment corresponding to activity of the en echelon normal faults; and determining the stages of the activity of the strike-slip faults. The method disclosed by the invention can be widely applied to the study of the activity stages of the strike-slip faults in craton.

Description

technical field [0001] The invention relates to the technical field of geological structure analysis, in particular to a method for determining the active phase of small and medium-scale strike-slip faults underground in a basin. Background technique [0002] The slip distance of strike-slip faults in cratons usually does not exceed several kilometers (Mann P. Global catalogue, classification and tectonic origins of restraining-and releasing bends on active and ancient strike-slip fault systems[J]. Geological Society, London, Special Publications, 2007, 290(1): 13-142), this type of strike-slip fault is a widely developed local structure and a three-dimensional geological body with complex structure (Caine J S, Evans J P, Forster C B. Fault zone architecture and permeability structure [J]. Geology, 1996, 24(11): 1025-1028). Due to the small activity intensity and the limitation of the resolution of seismic data, the analysis of the subsurface activity phases of this type of...

AI Technical Summary

Problems solved by technology

[0005] Although the predecessors have used these two methods to judge the activity phase of strike-slip faults with small and medium-scale slip distances in the subsurface of the basin, the application of the method itself depends on the prerequisites such as stratigraphic unconformity and echelon activities accompanied by sedimentary phenomena. It is not applicable to the cases where the signs of stratigraphic unconformity are not obvious (parallel unconformity) and the phenomenon of syn-sedimentation is not obvious when the echelon normal fault is developed.

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