Detrital zircon U-Pb dating of the Paleogene lower Ganchaigou Formation in the Qaidam basin and discussion of basin-mountain coupling
The Qaidam basin is surrounded by the Qilian Mountains,Altun Mountains and Kunlun Mountains.The unique lithology and sedimentary pattern of the Paleogene lower Ganchaigou Formation(E2)in the basin indicate the complex basin mountain system and the diverse genesis of the source area.In this paper,the structure and provenance of the Qaidam basin are systematically analyzed by using detrital zircon U-Pb dating and other analytical methods.The results show that the E32 zircon ages of the samples from well XX-1 in the front of the Qilian Mountains range from 2692 Ma to 156 Ma,and the main peak ages were 448 Ma and 249 Ma.The E2 zircon ages of samples from the well L6-1 ranged from 2693 Ma to 220 Ma,with the main peak ages of 499 Ma and 415 Ma.The E2 zircon ages of samples from the well YIT-1 located in the Western subsidence center of the basin ranged from 2796 Ma to 266 Ma,with the main peak ages of 423 Ma and 255 Ma.The E2 zircon ages of samples from the well N-105 in front of the Altun Mountains ranged from 2481 Ma to 242 Ma,and the main peak ages were 422 Ma and 259 Ma.The E2 zircon ages of samples from the well N-109 ranged from 2638 Ma to 228 Ma,and the main peak ages were 444 Ma and 246 Ma.Compared with the ages of the main source areas,the provenance of E2 in different structural zones of the basin is different.The provenance of E2 in wells XX-1 and L6-1 near the front of the Qilian Mountains mainly comes from the interior of the Qilian Mountains.The main source of wells N-105 and N-109 located in front of the Altyn Tagh Mountains is from the interior of the Altyn Tagh Mountains,but well N-109 has the contribution of the Qilian Mountains.The source of the well YIT-1 in the Chaixi depression is jointly controlled by the Qilian Mountains and the East Kunlun Mountains.The results of provenance analysis show that the Qilian Mountain has been uplifted on a large scale in the Paleogene,and as the northern boundary of the Qinghai-Tibet Plateau,it continues to provide provenance for the Qaidam basin.The Altun Mountains and Kunlun Mountains had taken shape in the E2 period,but did not rise on a large scale,resulting in a complex provenance system in the piedmont zone.
国家科技期刊平台
NSTL
万方数据
