Characteristics of Magnetic Fabrics in Western Segment of the Altun Fault Belt and Its Tectonic Significance

Abstract

AbstractThe parameters of magnetic fabric of deformed rocks such as Kmax,Kint,Kmin, P, T, F,L and E can be used to quantitatively display the behaviors and stages of tectonic deformation. Characteristics of magnetic fabrics in the west segment of Altun fault belt (from Guozhacuo to Kongkashankou) were analyzed in this investigation. These characteristics suggest that the segment had undergone multiple stages of mobility, and the deformation feature had experienced a successive transformation from ductile, to ductile‐brittle and to brittle deformation. Stress mechanisms are indicative of shear, stretch and compress with shear. The direction of principal stress is NNE‐SSW and approximately S‐N. The fabric characteristics of the minimum magnetic susceptibility axis (Kmin) are different between the two blocks of the strike‐slip fault, and in different areas they have different movement vectors. Sinistral strike slip is proved to be the main movement style of the Altun fault belt. Magnetic fabric data also indicate that the Altun fault belt has the character of semi‐symmetry with the most intensive deformation in the middle, and a gradual decreasing towards both sides, showing that the deformation during the early period gradually decreased from east to west along the strike‐slip fault belt. The stress, strain and the character of deformation revealed by magnetic fabrics are consistent with field features, microstructure and paleostress data.