Ar-40/Ar-39 dating of the Jiehe gold deposit in the Jiaodong Peninsula, eastern North China Craton: Implications for regional gold metallogeny
Ar-40/Ar-39 dating of the Jiehe gold deposit in the Jiaodong Peninsula, eastern North China Craton: Implications for regional gold metallogeny
复制标题
华北克拉通东部胶东半岛界河金矿床Ar-40/Ar-39定年：对区域金矿成矿的启示
DOI：
10.1016/j.oregeorev.2017.03.027
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发表时间：
2017
影响因子：
3.3
通讯作者：
Zhao Xin-Fu
中科院分区：
文献类型：
--
作者：
Bi Shi-Jian;Zhao Xin-Fu
界河金存款是胶东半岛的一个焦家型金存款矿床，已探明金储量34 t。矿体产于侏罗系磨山黑云母花岗岩与白垩系上庄斑状花岗闪长岩的接触带内，受北北东-北东向的望儿山-河东断裂控制。硫化物矿物主要由黄铁矿和少量黄铜矿、方铅矿和闪锌矿组成。热液蚀变严格受断裂带的控制，其中浸染状硫化物和自然金在空间上与普遍的绢云母蚀变有关。矿物学、结构学和野外关系表明，蚀变和成矿作用经历了4个阶段，包括含黄铁矿的乳白色块状石英（第1阶段）、浅灰色粒状石英-黄铁矿（第2阶段）、石英-多硫化物（第3阶段）和石英-碳酸盐（第4阶段）阶段。根据绢云母Rb-Sr年龄测定，界河存款形成于始新世（46.5 ± 2.3 Ma）。然而，本研究中绢云母的40 Ar/39 Ar定年结果在118.8 ± 0.7 Ma和120.7 ± 0.8 Ma之间得到了定义明确的、可重复的坪年龄。这些40 Ar/39 Ar年龄与胶东地区其他金矿床的年代学资料相一致，表明胶东地区所有金矿床都是在120 Ma左右的短期内形成的。该巨型金矿化事件与伸展构造体制有密切关系，是古太平洋板块俯冲和岩石圈破坏在华北克拉通东部的浅部地壳成矿响应。
The Jiehe gold deposit, containing a confirmed gold reserve of 34 tonnes (t), is a Jiaojia-type (disseminated/stockwork-style) gold deposit in Jiaodong Peninsula. Orebodies are hosted in the contact zone between the Jurassic Moshan biotite granite and the Cretaceous Shangzhuang porphyritic granodiorite, and are structurally controlled by the NNE- to NE-striking Wangershan-Hedong Fault. Sulphide minerals are composed predominantly of pyrite with lesser amounts of chalcopyrite, galena, and sphalerite. Hydrothermal alteration is strictly controlled by fracture zones, in which disseminated sulfides and native gold are spatially associated with pervasive sericitic alteration. Mineralogical, textural, and field relationships indicate four stages of alteration and mineralization, including pyrite-bearing milky and massive quartz (stage 1), light-gray granular quartz–pyrite (stage 2), quartz–polysulfide (stage 3) and quartz–carbonate (stage 4) stages. Economic gold is precipitated in stages 2 and 3.The Jiehe deposit was previously considered to form during the Eocene (46.5 ± 2.3 Ma), based on Rb-Sr dating of sericite. However,40Ar/39Ar dating of sericite in this study yields well-defined, reproducible plateau ages between 118.8 ± 0.7 Ma and 120.7 ± 0.8 Ma. These40Ar/39Ar ages are consistent with geochronological data from other gold deposits in the region, indicating that all gold deposits in Jiaodong formed in a short-term period around 120 Ma. The giant gold mineralization event has a tight relationship with the extensional tectonic regime, and is a shallow crustal metallogenic response of paleo-Pacific slab subduction and lithospheric destruction in the eastern NCC.