Temporal and spatial distribution of Dahalajunshan Group volcanic rocks in the Awulale Metallogenic belt of West Tianshan Mountains and its geological significance

Abstract: There exist widely-developed volcanic rocks of Dahalajunshan Formation along the Awulale metallogenic belt in West Tianshan Mountains. They are volcano-sedimentary rocks composed mainly of a set of rhyolite, trachyte, trachyandesite and intermediate-acidic tuff as well as a small amount of basalts. In this paper, the authors used LA-ICPMS zircon U-Pb dating method to determine the rock-forming age of volcanic rocks from Songhu, Shikebutai and Beizhan iron ore deposits. In addition, the authors sorted out the high-precision geochronological data previously obtained from the Awulale metallogenic belt. There exists the gradual change regularity from west to east: Chronologically, the age tends to change from old to young eastward, the Early Carboniferous volcanic rocks tend to pinch eastward, and the lithologic character varies in order of andesite lithology - basaltic andesite - rough endoplasmic lava - pyroclastic rocks. On the basis of data obtained and remote sensing image features, the authors determined the temporal and spatial distribution of the volcanic rocks in Dahalajunshan Formation, extracted the characteristics of the caldera and judged the spatial relationship between typical ore deposits and the caldera, thus investigating the genetic relationship between typical deposits and volcanic apparatuses. In combination with tectonic evolution characteristics, the geological significance is also discussed.