Himalayan Geology, Vol. 42 (1), 2021, pp. 93-108, Printed in India
Geochemical stratigraphy and tectono-magmatic evolution: Insights from intermediate-acidic volcanic rocks from well Y-2 in the Shiyingtan area, northern Xinjiang, China
HAN SIJIE1,2, SANG SHUXUN2*, LIANG JINGJING2,3, WANG WENFENG2,3, ZHANG GUANLONG4, WANG SHENGZHU4
1Low Carbon Energy Institute, China University of Mining and Technology, Xuzhou, 221008, China
2Key Laboratory of Coalbed Methane Resources and Reservoir Formation Process of the Ministry of Education, China University of Mining and Technology, Xuzhou, 221008, China
3School of Resource and Earth Sciences, China University of Mining and Technology, Xuzhou, 221116, China
4Geological Scientific Research Institute, Shengli Petroleum Administration, SINOPEC, Dongying, 257000, China
*Email (Corresponding author): shuxunsang@163.com
Abstract: Various volcanic rocks are widely distributed in and around the Junggar Basin, which is considered as a natural laboratory for investigating multiple subduction and continental crust accretion events during the Late Paleozoic. These subduction-related volcanic rocks provide significant clues to understanding magmatic evolution and provide reliable evidence for the closure of the western Keramaili oceanic basin during the Late Carboniferous. Here, we report geophysical, petrographic, and geochemical data for the upper Carboniferous volcanic rocks in well Y-2 and show their geochemical stratigraphy in the profile using representative high field strength elements and rare earth elements. Using discrimination diagrams and variations in geochemical stratigraphy, we discuss the petrogenesis of different volcanic units and propose a tectono-magmatic evolution in the Shiyingtan area during the Late Carboniferous. The results show that the volcanic rocks in well Y-2 are high-K calc-alkaline andesite-dacite assemblages that erupted during the Late Carboniferous. The upper and lower volcanic units in well Y-2 are derived from different magmatic sources and the continental crust components significantly increase over time. The upper Carboniferous volcanic rocks (303Ma-310Ma) in well Y-2 were formed in a subduction-related tectonic setting. The sources of these volcanic rocks were derived from various degrees of melting with an increasing involvement of the crust component. The geochemical stratigraphy and results of the upper and lower volcanic rocks indicated that the continental marginal arc in the Shiyingtan area experienced a process of vertical growth of the continental crust during the Late Carboniferous.
Keywords: Geochemical stratigraphy, High-K calc-alkaline, Subduction, Tectono-magmatic evolution, Late Carboniferous, Shiyingtan area
