高校地质学报2017，Vol.23Issue(1)：39-52,14.DOI:10.16108/j.issn1006-7493.2016003
黄山东铜镍矿的韧性变形特征和磁黄铁矿形成机制研究
Ductile Deformation Characteristics and Formation Mechanism of Pyrrhotite in the Huangshandong Ni-Cu Sulfide Deposit
摘要
Abstract
Huangshandong Ni-Cu sulfide deposit,located in the Huangshan-Jing'erquan ductile shear zone,belongs to the Jueluotage island arc belt of the Eastern Tianshan area,Central Asian Orogenic Belt.The Huangshandong mafic-ultramafic pluton,in shape of fusiform,intruded in the Late Carboniferous volcanic rocks with intensive foliation near the margin of the pluton which is consistent with the strike of the regional ductile shear zone.Some orebodies in the deposit also show intensive ductile deformation.The No.17 orebody was totally controlled and hosted by the ductile shear zone.The rocks and ores from the No.17 orebody show intensive deformation and alteration and could be called as ore mylonites.Considerable amounts of network and veinlet copper-rich carbonate-sulfide veins can be also observed in this ductile shear zone.In this contribution,detailed microscopy petrography and mineralography observation were carried out on different types of ores from the Huangshandong deposit.Combined with field geological investigation and ore fabric observation,three different types of ores were distinguished,that is,magmatic ores,deformed ores and fluid-overprinted ores.Magmatic ores with sideronitic fabric are barely altered and deformed,and sulfide minerals in it only show some brittle fractures.Deformed ores develop intensive deformation fabric in silicate and sulfide minerals,such as the kink bands,wavy extinction of uralite,domino structure of phlogopite and the elongation of pyrrhotite.Fluid-overprinted ores are characterized by strongly deformation,flattened grains and recrystallization of pyrrhotites,and annealing of pyrrhotites can also be occasionally observed.Intruding of Huangshandong pluton is coeval with ductile deformation and regional ductile shearing.During intruding and cooling of the pluton,intensive regional ductile shearing induced ductile deformation of sulfide ores and then ore mylonites formed.Gangue minerals in the deformed orebodies were crushed to fine-grained minerals and altered.In these processes,fluid and metallogenic elements were released and overprinted into deformed rocks and ores,forming network and veinlet ores.Owing to containing higher iron in original sulfide solid solution,the magmatic Ni-Cu sulfide ores in Huangshandong deposit could only form hexagonal pyrrhotite without associated monoclinic pyrrhotite and pyrite during the crystallization process of sulfide solid solution.During hydrothermal overprinting process,fluid overprinting occurred along margins and fractures of earlier stage magmatic hexagonal pyrrhotite,formed monoclinic pyrrhotite reactional rims.Our studies argued that monoclinic pyrrhotite can also be formed during hydrothermal precipitation processes.In this process,monoclinic pyrrhotites can exsolved from hexagonal grains in high oxygen and sulfur fugacity environments,as the cooling of such hydrothermal fluids.关键词
铜镍硫化物矿床/矿石结构/韧性变形/热液叠加/六方和单斜磁黄铁矿Key words
Ni-Cu sulfide deposit/ore fabric/ductile deformation/fluid-overprinting/hexagonal and monoclinic pyrrhotites分类
天文与地球科学引用本文复制引用
谢思文,吴昌志,顾连兴,雷如雄,杨涛,党奔..黄山东铜镍矿的韧性变形特征和磁黄铁矿形成机制研究[J].高校地质学报,2017,23(1):39-52,14.基金项目
国家自然科学基金(41272098 （）
40872050) （）
南京大学内生金属矿床成矿机制研究国家重点实验室(ZZKT-201111)联合资助 （ZZKT-201111）
