Structural analysis of Late Paleozoic deformation of central Dalabutefault zone, West Junggar, China

Researches of strike-slip faults play a significant role in the research of the accretion and evolution process of the Altaids, whose main tectonic units all separated by regional strike-slip faults. Dalabute fault is an important strike-slip fault developed within the West Junggar Orogen. The fault was hotly debated on its kinematics and age. Some representative models have been proposed: strike slip fault, thrust fault or transpressional fault, etc. We discussed the kinematics and age of the Dalabute fault in this article based on our field observation in central part of the fault, combined with research results of previous geochronological studies of the volcanic rocks, turbidites and post-collisional granite plutons. We have confirmed the existence of two-stage deformation between Late Carboniferous and Permian. The early one concerns a Late Carboniferous (320Ma) ductile sinistral strike-slip event which is the main deformation event, and the second one shows a folding event which presented by folds with SE-inclined axial planes developed within the ductile-brittle transitional condition, and formed before the deposition of the Permian strata. We also reported some geological structure showing dextral strike-slip, and they might be the result of folding of the early sinistral strike-slip structure, or the relics of an earlier dextral strike-slip event. The multi-stage deformation along the Dalabute fault is a record of post-orogenic extension and strike-slip tectonic adjusting in the West Junggar area, and it's a concrete reflection of the large scale intracontinental tectonic adjusting developed within Central Asia from Late Carboniferous to Early Permian.