Geochemical characteristics and petrogenic age of volcanic rocks in the Shikebutai iron deposit of West Tianshan Mountains

Abstract: Located in the western part of the West Tianshan Awulale iron metallogenic belt, the Shikebutai iron deposit is a representative deposit in this belt. It mainly occurs in the Carboniferous Yishijilike Formation volcanic rocks dominated by tuff. Based onj rock geochemistry and LA-ICPMS zircon U-Pb dating of volcanic rocks in the Shikebutai iron deposit, this paper discusses the tectonic environment and petrogenic age of the volcanic rocks. Geochemical analysis shows that most of the volcanic rocks vary from high potassium calc-alkaline volcanic rocks to shoshonite series in chemical composition. The major elements indicate that volcanic rocks are mainly composed of andesite, dacite, rhyolite and dacite, belonging to calc-alkaline series. Trace elements and rare earth elements indicate that the tectonic environment for the formation of the volcanic rocks was active epicontinental volcanic arc. LA-ICPMS zircon U-Pb dating shows that 206Pb/238U weighted average ages of volcanic rocks are 301±1Ma and 313±2Ma, suggesting that volcanic rocks in this deposit were formed in early Late Carboniferous. Combined with regional geological data, the authors hold that the high-K calc-alkaline volcanic rocks of shoshonite series in the ore district may be the product of the late subduction of continental arc magmatism, and the tectonic environment for the formation of the volcanic rocks was active epicontinental arc. The chemical characteristics of the volcanic rocks are on the whole similar to features of Lower Carboniferous Dahalajunshan Formation volcanic rocks.