The use of Stress Tensor Discriminator Faults in separating heterogeneous fault-slip data with best-fit stress inversion methods

Abstract

A widely accepted best-fit stress inversion method is applied on synthetic extensional heterogeneous fault-slip data generated by two driving Andersonian stress tensors having similar stress ratios, and σ3 axes with different trends, in order to examine whether the misfit angle (MA) minimization criterion can be used for separating heterogeneous fault-slip data. The examination shows that the resolved best-fit stress tensors have σ3 axes that tend to the bisector of the σ3 axes of the driving stress tensors, and stress ratios smaller than those of the latter. Moreover, there is a tendency towards determining radial extension stress regimes, although such regimes are rare in the Earth's crust. More importantly, the best-fit stress inversion methods that use solely the MA minimization criterion cannot be used for the separation of heterogeneous fault-slip data, especially when the extensional driving stress tensors have stress ratios smaller than R = 0.5, i.e., as are the favored paleostresses in the Earth's crust. In contrast, the percentage of the Stress Tensor Discriminator Faults (STDF) can be a very useful discriminator tool for the establishment and comparison between two resolved stress tensors as the latter have been determined by a best-fit stress inversion method. Moreover, the existence of fault-slip data that can been considered as possible STDFs during the recording stage advocate for the heterogeneous origin of the fault-slip dataset.