Isotopic Dating of Basalt from Gongpoquan Group in Yingmaotuo Area of the Beishan Mountain, Gansu Province, and Its Geological Significance
甘肃北山营毛沱地区公婆泉群中玄武岩 同位素定年及其地质意义

The U-Pb isotopic dating of zircon from basalt of Gongpoquan Group in Yingmaotuo area of the Beishan Mountain yields the ages of (333.1?9.8) Ma and (358?17) Ma. The former indicates that the basic rocks were formed in Early Carboniferous and the latter suggests that the Gongpoquan Group included some Devonian events. A comparative study of this discovery and fossils of Gongpoquan Group has led the authors to believe that this group is composed of Silurian, Devonian and Lower Carboniferous strata instead of merely Silurian strata. In other words, the effect of subduction and collision between the Tarim plate and the Kazakhstan plate probably continued into Lower Carboniferous.