Tectono-thermal Evolution Of The Gissar Basin,Uzbekistan

The Gissar Basin in Uzbekistan geographically locates in the southwestern end of the South Tianshan.Compared to the Kyzylkum area in the central Uzbekistan,the studies on the tectono-thermal evolution of the Gissar Basin are very few.For further enriching the cognition about the tectonic evolution of the Central Asia,the provenance and tectono-thermal evolution of the Gissar Basin since the Mesozoic were systematically studied in this paper by combining with zircon U-Pb,apatite fission track(AFT),and apatite(U-Th)/He(AHe)data.The zircon U-Pb ages in the Gissar Basin mainly consist of three age populations of 422Ma?402Ma,324Ma?277Ma and254Ma?207Ma,which indicated that the westside of the Talas-Fergana Fault in the Central Tian Shan and Karakum and Kyzylkum in the South Tian Shan provided sediments for the Gissar Basin from Jurassic to Paleogene.Since the Paleogene,the Pamir Plateau become the provenance of the Gissar Basin following the closure of the New Tethys Ocean.This is certified by the youngest zircon U-Pb ages with40Ma?30Ma from the Neogene strata in the Gissar Basin.The AFT central ages in the Gissar Basin range from 65.46 Ma to 2.43 Ma,and the AHe ages are between 30.76 Ma and 8.87 Ma.They are all younger than the corresponding stratigraphic ages,indicating that these samples experienced high-temperature resetting after deposition in the Gissar Basin.The thermal modeling results by the AFT and AHe ages reveals that the Gissar Basin experienced two rapid cooling events occurred in the Eocene-Oligocene(52Ma?26Ma)and Miocene-Pliocene(22Ma?3Ma),respectively.They were all related to the southward subduction of the Pamir Plateau.This study provides new insights for the provenance and tectono-thermal evolution of the Gissar Basin during Mesozoic and Cenozoic which are significant for the tectonic evolution of the Tian Shan and the Central Asia.