Magma plumbing system in orogenic belts and its role for the formation of magmatic sulfide deposit:the case study of the Huangshandong intrusion (Xinjiang,NW China)
The Eastern Tianshan Orogenic Belt (ETOB) hosts ~120 mafic-ultramafic intrusions with variable Cu-Ni mineralization.Being the largest among these,The Permian (~ 270 Ma) Huangshandong mafic-ultramafic intrusion,the contains 135 million tons of sulfide ores with an average grade of 0.3 wt.% Ni,0.16 wt.% Cu and 0.024% Co.The intrusion consists of a layered unit of lherzolite,gabbro and diorite intruded by a massive unit of olivine gabbronorite and gabbronorite.These two units of the Huangshandong intrusion formed from magmas that have undergone different processes through the evolution of the magma plumbing system.The early magma pulse gained sulfur-saturation with small amounts of sulfide (<0.03%) removed before emplacement and was thus PGE-depleted.This magma achieved sulfide-saturation again in the staging magma chamber through crustal contamination and fractional crystallization of olivine and Cr-spinel (AFC process) to form the layered unit.A second magma pulse underwent fractionation of more olivine but less sulfide (<0.003%) in the early stage and the evolved magma was emplaced into the magma chamber.Mixing of magmas triggered sulfide-saturation.Sulfide melts then segregated from different parts of mixed magmas and have different compositions due to different ratios of mixed magmas.
Jian-Feng Gao Mei-Fu Zhou Peter C.Lightfoot Liang Qi Min Sun
Department of Earth Sciences,the University of Hong Kong,Hong Kong,China Vale,Highway 17 West,Sudbury,Ont P0M 1N0,Canada State Key Lab of Ore Deposit Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,Guiy
国际会议
贵阳
英文
208-208
2012-06-16（万方平台首次上网日期，不代表论文的发表时间）