科研之友
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摘要
The Huangtan (including Jinling) Au-Cu-Zn deposit is an auriferous volcanogenic massive sulfide (VMS) deposit discovered in East Tianshan, Central Asian Orogenic Belt. The deposit is hosted in volcanic breccia and tuff of the Silurian Hongliuxia Formation. The ore bodies consist of concordant massive sulfide lenses and discordant sulfide veins. Chalcopyrite Re-Os dating constrained the age of mineralization in the Huangtan deposit at 432 Ma. Quartz and barite host abundant liquid-rich, liquid-only and minor vapor-rich aqueous fluid inclusions. The fluid inclusions in barite from the exhalative-sedimentary units mainly have homogenization temperatures at 140-260 degrees C, and calculated salinities of 3-9 wt% NaCl equiv.; Those values are at 120-300 degrees C, and 1-9 wt% NaCl equiv. for varieties in quartz from the vein ores and alteration assemblages. Fluid inclusions extract from pyrite have He-3/He-4 ratios of 0.929-1.374 Ra, Ar-40/Ar-36 of 388-520, and Ar-40/He-4 of 0.355-0.836. The quartz and barite yielded delta O-18 values of 7.4 parts per thousand to 10.1 parts per thousand and the delta DV-SMOW values of the fluid inclusions in the quartz and barite range from - 69 to - 42 parts per thousand. The He-Ar and H-O isotopes imply that the ore-forming fluids were derived from a magmatic source with the addition of deeply circulating seawater. The delta S-34(V-CDT) values of pyrite and chalcopyrite range from - 2.0 to 1.5 parts per thousand, and those of barite samples range from 24.1 to 24.8 parts per thousand, which indicates that sulfur was derived from magmatic sulfur, and was subjected to fractionation between sulfide and sulfate. Linked to the ore geology, geochronology data, isotope compositions and fluid inclusions obtained in this study with those of previously published adjacent VMS deposits in the Kalatag area suggest that the Huangtan deposit and adjacent VMS deposits formed in the same metallogenic system.
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单位中国科学院
