The zircon U-Pb LA-ICP-MS geochronology of volcanic rocks in Baogutu areas, western Junggar
西准噶尔包古图地区地层火山岩锆石LA-ICP-MS U-Pb年代学研究

There is a great thickness of bathyal- and slope-facies volcanic-volcaniclastic sedimentary sequence at Baogutu area in southeast of western Junggar, which are named as Tailegula Formation, Baogutu Formation and Xibeikulas Formation, respectively. There have been controversies about the geological ages and stratigraphic subdivision about these strata for a long time. So we surveyed the stratum section at Baogutu area and separated zircons from basalt of the Tailegula Formation and tuff of Baogutu Formation and Xibeikulas Formation. LA-ICP-MS U-Pb dating on these zircon grains gives the 206Pb/238U weighted mean ages of 357.5±5.4Ma, 332.1±3.0Ma and 336.3±2.5Ma, respectively, indicating that the strata sequence from bottom to top should be Tailegula Formation, Baogutu Formation and Xibeikulas Formation in turn, which were formed from Tournaisian to Visean of Early Carboniferous.