Fluid inclusion study of the Nannihu giant porphyry Mo-W deposit, Henan   Province, China: Implications for the nature of porphyry ore-fluid   systems formed in a continental collision setting

doi:10.1016/j.oregeorev.2012.02.003

CORC > 北京大学 > 地球与空间科学学院

	Fluid inclusion study of the Nannihu giant porphyry Mo-W deposit, Henan Province, China: Implications for the nature of porphyry ore-fluid systems formed in a continental collision setting
	Yang, Yong-Fei ; Li, Nuo ; Chen, Yan-Jing
刊名	ore geology reviews
	2012
关键词	Fluid inclusion Nannihu porphyry Mo-W deposit Qinling Orogen Continent-continent collision High-salinity carbonic fluid MESOZOIC MOLYBDENUM DEPOSITS FREEZING-POINT DEPRESSION DABIE OROGENIC BELT TECTONIC IMPLICATIONS LUANCHUAN COUNTY MAGMATIC FLUIDS FUJIAN PROVINCE FORMING FLUIDS EASTERN CHINA GOLD DEPOSITS
DOI	10.1016/j.oregeorev.2012.02.003
英文摘要	The Nannihu Mo-W deposit, located in the Henan Province of China, is a giant porphyry deposit formed in the Qinling Orogen during the Jurassic continental collision between the North China and Yangtze Cratons. Mo-W mineralization is associated with the Nannihu porphyritic monzogranite, occurring as numerous stockwork veinlets in the altered wallrocks and the causative porphyry. Both the porphyry stock and wallrocks underwent intense hydrothermal alteration, ranging outwardly from potassic to phyllic alteration, and to carbonation zones with increasing distance from the intrusion. The hydrothermal ore-forming process can be divided into four stages characterized by veinlets, from early to late: (1) quartz + potassic feldspar +/- molybdenite +/- pyrite; (2) quartz + molybdenite veins containing minor pyrite and chalcopyrite; (3) quartz + polymetal sulfide; and (4) quartz + carbonate + fluorite. Most of the ores are formed during stages 2 and 3. Four types of fluid inclusions (FIs) are distinguished in this study based on petrographic and microthermometric criteria, i.e. pure CO2, NaCl-H2O, CO2-H2O and daughter mineral-bearing fluid inclusions. All of the four types of FIs can be observed in the hydrothermal quartz formed in stages 1, 2 and 3; while the stage 4 minerals contain only NaCl-H2O fluid inclusions. Fluid inclusions of stage 1 are mainly homogenized between 350 and 460 degrees C, with salinities ranging from 5.7 to 17.9 wt.% NaCl equiv. The stage 2 FIs yield homogeneous temperatures of 300-380 degrees C and salinities of 3.5-16.9 wt.% NaCl equiv. FIs of stage 3 are homogenized between 250 and 370 degrees C, with salinities of 1.8-14.3 and 28.6-39.1 wt.% NaCl equiv. FIs of stage 4 are homogenized at temperatures of 115 to 265 degrees C, yielding salinities of 0.5 to 1.2 wt.% NaCl equiv. Daughter minerals, such as halite, chalcopyrite and some unknown minerals, are frequently present in stage 3 FIs, which probably represent a reducing and oversaturated fluid-system resulting from fluid-boiling. The daughter mineral-bearing FIs coexist with vapor- and liquid-rich NaCl-H2O FIs that have contrasting salinities. These FIs are homogenized in divergent ways at similar temperatures, suggesting that fluid boiling took place in stages 2 and 3. The estimated pressures range from 70 to 270 MPa in stage 1, through 30-150 MPa in stage 2, to 30-85 MPa in stage 3, corresponding to a depth of no less than 3 km. In other words, the ore-forming fluids are characterized by high temperature, high salinity, high fO(2) and high CO2 content; and fluid-boiling resulted in CO2 release, fO(2) decrease and ore mineral precipitation. We suggest that the CO2-rich fluid is a distinctive feature of porphyry systems developed in continental collision setting, in transitional compressional to extensional regime, contrasting to the CO2-poor NaCl-H2O fluids observed in volcanic arcs. (c) 2012 Elsevier B.V. All rights reserved.; Geology; Mineralogy; Mining & Mineral Processing; SCI(E); EI; 0; REVIEW; 83-94; 46
语种	英语
内容类型	期刊论文
源URL	[http://ir.pku.edu.cn/handle/20.500.11897/232607]
专题	地球与空间科学学院
推荐引用方式 GB/T 7714	Yang, Yong-Fei,Li, Nuo,Chen, Yan-Jing. Fluid inclusion study of the Nannihu giant porphyry Mo-W deposit, Henan Province, China: Implications for the nature of porphyry ore-fluid systems formed in a continental collision setting[J]. ore geology reviews,2012.
APA	Yang, Yong-Fei,Li, Nuo,&Chen, Yan-Jing.(2012).Fluid inclusion study of the Nannihu giant porphyry Mo-W deposit, Henan Province, China: Implications for the nature of porphyry ore-fluid systems formed in a continental collision setting.ore geology reviews.
MLA	Yang, Yong-Fei,et al."Fluid inclusion study of the Nannihu giant porphyry Mo-W deposit, Henan Province, China: Implications for the nature of porphyry ore-fluid systems formed in a continental collision setting".ore geology reviews (2012).