Geology, mineralization, and geochronology of the Qianhe gold deposit, Xiong’ershan area, southern North China Craton
Geology, mineralization, and geochronology of the Qianhe gold deposit, Xiong’ershan area, southern North China Craton
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DOI：
10.1007/s00126-012-0451-2
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发表时间：
2013-01
影响因子：
4.8
通讯作者：
K. Tang;Jian-wei Li;D. Selby;Mei‐Fu Zhou;Shi-Jian Bi;Xiao-Dong Deng
中科院分区：
文献类型：
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作者：
K. Tang;Jian-wei Li;D. Selby;Mei‐Fu Zhou;Shi-Jian Bi;Xiao-Dong Deng
熊耳山地区前河金存款矿床位于华北太古宙-古元古代陆缘沿着。该存款由六个矿体组成，其容矿岩为古元古代安山岩至玄武安山岩，构造受大致EW向断裂控制。个别矿体由含金石英脉和脉两侧或附近热液蚀变岩中的浸染状含金黄铁矿组成。与矿石有关的热液蚀变产生了各种钾长石、石英、绢云母、云母、绿帘石、碳酸盐和硫化物的混合物。黄铁矿是最重要的矿石矿物，伴生有少量的方铅矿、闪锌矿和黄铜矿。其他微量矿物包括白硅钙石、毒砂、白钨矿、金红石、磷钇矿和钯矿。金主要以自然金和银金矿的形式赋存于黄铁矿中或硫化物和石英的微裂隙沿着。对含金石英中原生包裹体的显微测温表明，金及其伴生矿物是在160-305 °C的温度范围内从盐度为6- 22wt%NaCl当量的含水流体或碳质-含水流体中沉淀出来的。与含金黄铁矿共生的绢云母样品的Re-Os模式年龄为134-135 Ma，与含金黄铁矿共生的绢云母样品的40 Ar/39 Ar坪年龄为127 ~ 124 Ma。Re-Os和~（40）Ar/~（39）Ar年龄与前河金矿及其邻区的河峪杂岩体和花岗质脉岩中黑云母二长花岗岩的锆石U-Pb年龄（134.5 ± 1.5和127.2 ± 1.4Ma; 1σ）一致，表明金矿化与花岗质岩浆活动有密切的时间关系和成因关系。从含金石英中提取的流体包裹体沃茨的δD值为−80 ~ −72 ‰，而计算的δ 18 OH 2 O值为3.1 ~ 3.8 ‰。本研究和以往工作的氢氧同位素表明，成矿流体可能来自岩浆脱气，并加入少量的大气降水。前河金矿化与整个华北东部克拉通普遍的双峰式岩浆活动、广泛的断陷-盆地形成和变质核杂岩的发育是暂时性的，反映了该克拉通自古元古代晚期形成以来长期稳定后，在中生代晚期的重新活化。据此认为，前河金存款是克拉通活化事件的产物。
The Qianhe gold deposit in the Xiong’ershan area is located along the southern margin of the Archean-Paleoproterozoic North China Craton. The deposit consists of six orebodies that are hosted in Paleoproterozoic andesites to basaltic andesites and structurally controlled by roughly EW-trending faults. Individual orebodies comprise auriferous quartz veins and disseminated Au-bearing pyrite within hydrothermally altered rocks on both sides of, or close to, the veins. Ore-related hydrothermal alteration has produced various mixtures of K-feldspar, quartz, sericite, chlorite, epidote, carbonate, and sulfides. Pyrite is the most important ore mineral, associated with minor amounts of galena, sphalerite, and chalcopyrite. Other trace minerals include molybdenite, arsenopyrite, scheelite, rutile, xenotime, and parisite. Gold occurs mostly as native gold and electrum enclosed in pyrite or along microfractures of sulfides and quartz. Microthermometric measurements of primary inclusions in auriferous quartz suggest that gold and associated minerals were precipitated in the range of 160–305 °C from aqueous or carbonic-aqueous fluids with salinities of 6–22 wt% NaCl equiv. Samples of molybdenite coexisting with Au-bearing pyrite have Re–Os model ages of 134–135 Ma, whereas ore-related hydrothermal sericite separates yield40Ar/39Ar plateau ages between 127 and 124 Ma. The Re–Os and40Ar/39Ar ages are remarkably consistent with zircon U–Pb ages (134.5 ± 1.5 and 127.2 ± 1.4 Ma; 1σ) of the biotite monzogranite from the Heyu-intrusive complex and granitic dikes in and close to the Qianhe gold mine, indicating a close temporal and thus possibly genetic relationship between gold mineralization and granitic magmatism in the area. Fluid inclusion waters extracted from auriferous quartz haveδD values of −80 to −72 ‰, whereas the calculatedδ18OH2Ovalues range from 3.1 to 3.8 ‰. The hydrogen and oxygen isotopes from this study and previous work indicate that ore fluids were likely derived from degassing of magmas, with addition of minor amounts of meteoric water. Gold mineralization at Qianhe is temporarily coincident with pervasive bimodal magmatism, widespread fault-basin formation, and well development of metamorphic core complexes in the whole eastern North China Craton that have been interpreted as reflecting reactivation of the craton in the late Mesozoic after prolonged stabilization since its formation in the late Paleoproterozoic. It is therefore concluded that the Qianhe gold deposit formed as a result of this craton reactivation event.