Basin-mountion Coupling Mechanism Of The Northern Margin Of Qaidam Basin: Evidences From Fission-track Thermochronology

Qinghai-Tibet Plateau is the largest and topmost plateau in China, with a global unique geographical unit of the world, and it is a great event in global geological pro-cesses that the formation and uplift of the Plateau in Cenozoic. The evolution of the Plateau has a huge impact for the geological-topographic evolvement of Central Asia or even global environmental change. Although study of the Qinghai-Tibet Plateau has acquired remarkable achievements by geological workers all over the world had worked hard for last decades, so far, the time, process, range and form of the Plateau uplift and its resources-environment's effects etc have not yet obtained the consistent know. The Qaidam Basin is an inland basin formed by the north-south di- rection co-mpressive stress which caused by the collision of India and Eurasia plate, it located between Asia axial and Tethyan-Himalayan tectonic domain structurally, has depo-sited huge thick strata of Cenozoic, the strata and bedrock around the mountains whi-ch had supplied sediments to the Basin was reserved detailed information about the Plateau uplift and the Basin evolution.In this paper, according to principle of thermochronology, combined with the re-gional geological evolution of Northern margin of Qaidam Basin(NMQB), had colle-cted rock samples which from different times and places of the margin to tests apatite fission-track data. The analysis of fission-track length distribution showed that bedro-cks of NMQB has been gradually uplifting since the early Yanshan; By detailed stat-istic of AFT ages and distribution of AFT apparent age, we proposed the NMQB has experienced five thermo-tectonic events since the early Jurassic, their ages were (186±10) Ma, (139±8) Ma, (112±7.5) Ma, (89±6.67) Ma,and (53.25±5.25) Ma, respectively.Spatial distribution of AFT ages show thrust-fold belt of NMQB has the overstep propagation, and that provides reliable evidence for the basin-mountain cou-pling mechanism of NMQB, also pointed out that it has a significant different uplifti-ng-cooling from the east to west. By thermal history modeling of all AFT data, we are not only proved NMQB had experienced five Thermo-tectonic events, but also infer the thrust-fold belt of overstep propagation in NMQB may be formed in the early Hi-malayan, but NMQB rapid uplift and cool since Quaternary, its uplift rate is about 731-12m/Ma.