Characteristics and geochronology of volcanic rocks of Batamayineishan Formation in Kalamaily, Eastern Junggar, Xinjiang.

The volcanic rocks of the Batamayineishan Formation are widely distributed in eastern Junggar Basin and its neighboring margins. It is the main reservoir of giant gas field in Ludong, Wucaiwan area. Comparing two measured sections and a well lithologic section, the continental volcanic rocks of Batamayineishan Formation are obviously multiple stages and intermittent volcanic activities interrupted by the sedimentary interbeds which are the main indicators of discontinuous interfaces. The thickness of the volcanic rocks vary greatly in different places, changing dramatically not only in lithology but also in lithofacies. Petrochemical analysis suggests the rock types are mainly basic-intermediate which belongs to subalkaline-alkaline and K rich series. This paper report a 350.0 +/- 6.3Ma age of volcanic rock by the SHRIMP zircon U-Pb geochronology. Combined with the fossil evidences from the overlying strata, it can be concluded that the Batamayineishan Formation is the Lower Carboniferous.