Chronology evidence of ESR dating for the late movements of the Piqiang fault in the Tarim Basin and its geological implication
The Piqiang fault is a NW-trending strike-slip fault in the Keping uplift on the north margin of Tarim Basin.Satellite images of the fault show a left-lateral strike-slip faulting structure with local right-lateral characteristics in the south.The Piqiang fault and Selibu fault on the Bachu uplift in the basin shows well spatial matching relationship.Therefore,chronology evidence of ESR dating of the Piqiang fault bears great significance to the study of late deformation of Tarim Basin.Field surveys shows that the fault offset the Paleozoic in the Keping uplift and dragged it to the surface.The Ordovician in the area is dominated by carbonates and contains well-developed large calcite veins due to faulting and late fluid filling and crystallization.The dating of calcite veins in the fault belt indicates that the age recorded by the Piqiang fault at late stage is 62-66 ka,and that recorded by the middle part of the fault is 3 583±350 ka.The similar chronological age data of the southern and northern parts shows that the Piqiang fault has the characteristics of synchronous activity during the later period.Based on the genetic analysis of the big age differences of the calcite veins in the Piqiang fault,it is suggested that the Keping uplift still possibly experienced vertical uplifting even after overthrusting of Keping Uplift in SW direction.The vertical uplifting in turn is the result of differential modification at the south and north ends of the Piqiang fault.