Physical simulation of the influence of lithological differences on fault zone structure

The controlling stratigraphic elements for fault zone structure were studied. Possible fault zone structures in sand and mudstone formations were simulated in view of sand and mudstone mechanical properties and contents. The Poisson's ratio and content of mudstone controlled fault zone structure and its internal unit size. The Poisson's ratio of sand did not directly determine fault zone structure, which might be explained by the brittle deformation of sand in the experiment. On the contrary, sand content was a key element for fault zone structure. When mudstone content was fixed, the Poisson's ratio of sand controlled the width of the fault zone. When the ratio of mud to sandstone Poisson's ratio was 1-1.33, dualistic structure developed in the fault zone. When the Poisson's ratios of sand and mudstones were less than 0.28 and 0.34, respectively, a unitary fault zone with loose structure formed. When the Poisson's ratios of sand and mudstones were more than 0.35 and 0.38, respectively, a closed unitary sliding surface developed.