Pyrite-anhydrite-magnetite-pyroxene-type deposits and coexisting hydrothermal fluids in Mesozoic volcanic basins, Yangtze River Valley, China

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	Pyrite-anhydrite-magnetite-pyroxene-type deposits and coexisting hydrothermal fluids in Mesozoic volcanic basins, Yangtze River Valley, China
	Zhang, RH (Zhang, Ronghua); Zhang, XT (Zhang, Xuetong); Hu, SM (Hu, Shumin)
刊名	ORE GEOLOGY REVIEWS
	2011
卷号	43 期号:1 特刊 SI 页码:315-332
关键词	Anhydrite-magnetite-pyroxene mineral assemblage Hydrothermal alteration zone Temperature gradient Chemical constraint Activity diagram
ISSN号	0169-1368
英文摘要	Anhydrite-pyrite-magnetite-pyroxene-type deposits occur in the Mesozoic volcanic areas of the Middle-Lower Yangtze Valley in China. These deposits are hosted in alkaline basaltic rocks, and are generally accompanied by melanocratic and leucocratic alteration zones, both of which are characterized by a distinct vertical zonation pattern. Investigation of these zones indicates that the chemical compositions of solid solutions and polymorphs of various minerals vary spatially in the alteration profile, upwards from the lowest level, and outwards from the center. Here we report a case study on the Luohe deposit. In the melanocratic-alteration zone, the composition of magnetite (including trace elements Ti, V, Mg, Mn), pyroxene (Mg, Fe(2+), Fe(3+), Al(2)O(3)), plagioclase (An(x)Ab(1-x)), pyrite (Co, Ni) and apatite (F, CeO(2) + Y(2)O(3) +La(2)O(3)) changes with depth. The isotherms of hydrothermal fluids determined from fluid inclusion data, including homogenization temperature and salinity, also vary with depth. Activity diagrams were constructed from mineral and isotherm analysis to estimate the chemical constraints on the alteration-mineral assemblages and the coexisting hydrothermal solutions for the Na(2)O-K(2)O-CaO-MgO-FeO-Fe(2)O(3)-Al(2)O(3)-SiO(2)-H(2)SO(4)-H(2)S-HCl-H(2)O system at 350 to 600 degrees C and 500 bars (50 MPa), assuming that the major alteration mineral assemblages along the profile reflect the nature of the coexisting hydrothermal solutions. The activity diagrams adopted the major minerals as buffers to fix the activities of the aqueous species in the system, simulating the physicochemical conditions of the magnetite-anhydrite-pyroxene equilibrium and of solid solutions of diopside-hedenbergite, grossular-andradite and anorthite-albite found in the profile. This study provides an approach to modeling the chemical constraints of coexisting fluids in ore-alteration zones based on field observations. (C) 2011 Elsevier B.V. All rights reserved.
学科主题	矿床地质
WOS关键词	THERMODYNAMIC PROPERTIES ; AQUEOUS-SOLUTIONS ; HIGH-PRESSURES ; LUZONG ; MIDDLE ; TEMPERATURES ; MINERALS ; RIDGE ; ROCK ; ORE
WOS研究方向	Geology ; Mining & Mineral Processing
语种	英语
出版者	ELSEVIER SCIENCE BV
WOS记录号	WOS:000298906600024
内容类型	期刊论文
源URL	[http://119.78.100.197/handle/2HKVOGP0/39310]
专题	中国地质调查局
作者单位	Chinese Acad Geol Sci, Inst Mineral Resources, Lab Geochem Kinet, MLR Key Lab Metallogeny & Mineral Assessment, Beijing 100037, Peoples R China
推荐引用方式 GB/T 7714	Zhang, RH ,Zhang, XT ,Hu, SM . Pyrite-anhydrite-magnetite-pyroxene-type deposits and coexisting hydrothermal fluids in Mesozoic volcanic basins, Yangtze River Valley, China[J]. ORE GEOLOGY REVIEWS,2011,43(1 特刊 SI):315-332.
APA	Zhang, RH ,Zhang, XT ,&Hu, SM .(2011).Pyrite-anhydrite-magnetite-pyroxene-type deposits and coexisting hydrothermal fluids in Mesozoic volcanic basins, Yangtze River Valley, China.ORE GEOLOGY REVIEWS,43(1 特刊 SI),315-332.
MLA	Zhang, RH ,et al."Pyrite-anhydrite-magnetite-pyroxene-type deposits and coexisting hydrothermal fluids in Mesozoic volcanic basins, Yangtze River Valley, China".ORE GEOLOGY REVIEWS 43.1 特刊 SI(2011):315-332.