Physicochemical Control of the Early Permian Xiangshan Fe-Ti Oxide Deposit in Eastern Tianshan(Xinjiang),NW China
Physicochemical Control of the Early Permian Xiangshan Fe-Ti Oxide Deposit in Eastern Tianshan(Xinjiang), NW China作者机构:Beijing Institute of Geology for Mineral ResourcesBeoing 100012China School of Earth Sciences and ResourcesChina University of GeosciencesBeijing 100083China Faculty of Land Resource EngineeringKunming University of Science and TechnologyKunming 650093China
出 版 物:《Journal of Earth Science》 (地球科学学刊(英文版))
年 卷 期:2018年第29卷第3期
页 面:520-536页
核心收录:
学科分类:070903[理学-古生物学与地层学(含:古人类学)] 081803[工学-地质工程] 0709[理学-地质学] 07[理学] 08[工学] 0818[工学-地质资源与地质工程]
基 金:financially supported by the National Natural Science Foundation of China(No.41372102) the National Basic Research Program of China(No.2014CB440803) the China Geological Survey(No.DD20160071)
主 题:eastern Tianshan magmatic Fe-Ti oxide deposits gabbros layered intrusion zircon U-Pb age geochemistry.
摘 要:The Xiangshan mafic-ultramafic complex is one of the major Early Permian maficultramafic intrusions in eastern Tianshan (Xinjiang, NW China), and consists of two major intrusive phases. The first intrusive phase is mainly gabbroic rocks hosting ilmenite mineralization, while the second intrusive phase is mainly lherzoilite associated with Ni-Cu sulfide mineralization. The Xiangshan ilmenite orebodies hosted in the Fe-Ti oxide-bearing gabbro occur along the contact between hornblende gabbros and leucogabbros. The hornblende gabbros and Fe-Ti oxide rich gabbros at Xiangshan are newly dated to be Early Permian (280.1 and 279.2 Ma, respectively). Major and trace element compositions of zircons and whole rocks from Xiangshan hornblende gabbro and Fe-Ti oxide gabbro have been measured by in situ excimer laser ablation ICP-MS. Zircon Ce^4+/Ce^3+ ratios based on lattice-strain model and Ti-in-zircon temperatures of hornblende gabbro and Fe-Ti oxide gabbro of the Xiangshan complex are calculated to evaluate the physicochemical variations during the ilmenite mineralization. Whole-rock geochemistry and zircon trace element geochemistry suggest that Fe-Ti oxide gabbros were formed from a basaltic parent magma which had undergone a transfromation from being H2O-rich to H2O-poor. During the magmatic evolution, primitive, HEO-poor basaltic melts may have been replenished into the system, increasing its solidus temperature and decreasing its oxygen fugacity and H2O contents. This may have supperessed the Ti-rich poikilitic hornblende fractionation and promoted the plagioclase fractionation, which consequently concentrated the ore-forming components in the residual melts and generated the ilmenite mineralization.