SHRIMP U-Pb zircon ages of tuff in Baogutu Formation and their geological significances
新疆西准噶尔包古图组凝灰岩锆石SHRIMP年龄及其地质意义

Lower Carboniferous volcanic-sedimentary rocks including Tailegula, Baogutu and Xibeikulasi formations are widely distributed in western Junggar. The ages of the three formations were defined by fossils before. Three altered tuff samples are dated to be 328.4Ma (MSWD=0.72), 342.6Ma (MSWD=0.76) and 336.5Ma (MSWD=1.6) by zircon SHRIMP, respectively, which helps constraining the age of the Baogutu Formation. A combination of the zircon SHRIMP ages and the distribution relationship between the three formations suggest that the Tailegula Formation is the youngest, and the Xibeikulasi Formation is the oldest in the Lower Carboniferous.