The Hanshan gold deposit in the Caledonian North Qilian orogenic belt, NW China

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• 作者：Mao Jingwen ; Zhang Zuoheng ; Yang Jianmin and Zhang Zhaochong
• 刊名：Mineralium Deposita
• 出版年：2000
• 出版时间：January 2000
• 年：2000
• 卷：35
• 期：1
• 页码：63-71
• 全文大小：393 KB

文摘

The recently discovered Hanshan gold deposit in northern Gansu Province, northwestern China, is hosted by a WNW-striking shear zone in Ordovician andesite and basalt. Mineralization consists of surface to near-surface oxidized ore (the yellow sandy gossan type) and three types of primary ore, i.e. early-stage quartz-sericite-pyrite ores in stockworks, early-stage disseminated ore, and the most important late-stage quartz ¡À calcite-sulfide veins. The ore system is characterized by variable degrees of potassic and silicic alteration. Late-stage gold-related fluid inclusions have homogenization temperatures between 170 to 310 ¡ãC, with a peak around 260 ¡ãC and low salinities. The ore fluids had high contents of CO₂, CH₄, and N₂. Sulfur isotope measurements of −1.9 to +1.7 per mil for hydrothermal pyrites could be consistent with a hydrothermal fluid source from the mantle, but the oxygen and carbon isotope data from calcite and quartz suggest mixing between mantle and crustal fluid sources. K-Ar ages for hydrothermal sericite from ore zones are 213.9 ¡À 3.1 and 224.4 ¡À 3.2 Ma. Due to the arid Cenozoic climate, a yellow gold-bearing gossan developed, which consists of jarosite, gypsum, and relict quartz. It could be a widespread and useful prospecting guide for gold in northwestern China.