Structural controls on the Jiaodong type gold deposits and metallogenic model
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    Abstract:

    The Jiaodong type gold deposits are controlled by a faulted structure. Structural control of ore deposition has always been the focus of geological exploration and research. For expanding the study on the fault control of gold mineralization based on a large number of ore deposits exploration and geological survey data, through the structural analysis of typical faults sections and the spatial relationship between faults and ore bodies, this paper determined the properties of the faults and stress state in metallogenic period, and discussed the ore- controlling mechanism by fault attitude change, and proposed a new structural metallogenic model of the Jiaodong type gold deposits. The main ore- controlling faults in the Jiaodong Peninsula are divided into grade I gently dip fault, grade Ⅱ steeply dip fault, and grade Ⅲ steeply dip tensile veins, which controlled the fracture altered rock type gold deposits, composite type gold deposits and quartz vein type gold deposits respectively. Gold ore bodies mainly occur at the turning part of the fault attitude. Altered rock type ore bodies occur at the part where fault dip angle decreases. However, quartz vein type ore bodies occur in the part where fault dip becomes steeper. Ore bodies controlled by the gently dipping fault have the characteristics of “double pitch” where the overall pitch angle is small and pitch angle of ore shoot is large. The relationship between the ore bodies attitude and the fault attitude indicates that the Sanshandao, the Jiaojia and the Zhaoping ore- controlling faults all belong to dextral normal slip fracture or right- lateral transtensional fault during mineralization, while the Jinniushan fault has the characteristics of left- lateral normal slip. The σ1 (regional tectonic stress field) of the Jiaoxibei gold metallogenic district, the Jiaojia fault and northern section of the Zhaoping fault is 294°∠82°and 269°∠78°; 300°∠67°, 311°∠78° and 321°∠81°; and 130°∠65° and 138°∠69°, respectively. These indicate that the distribution area of the Linglong granitic pluton in the northwest of Jiaodong Peninsula is mainly dominated by vertical principal stress, while the principal stress orientation of the boundary faults on the east and west sides is along the SE—NW direction to the pluton, and the faults are in NW—SE extensional state during mineralization. The σ1 of the Denggezhuang gold field in eastern Jiaodong is 287°∠0°, and is dominated by horizontal principal stress. It is concluded that the faults with variable occurrence and tensional property are favorable ore- hosting structures for gold deposits, and the change of fault attitude has obvious control on gold ore bodies. The key factor of stepped mineralization of gold deposit is the change of fault and fluid properties. The attitude transition of fault along strike and dip jointly controls the pitch of gold ore bodies. The rapid emplacement of a large number of deep magma during the Early Cretaceous in the Jiaodong Peninsula resulted in strong crustal uplift that generates extensional structure. Magma from different depths and source regions intruding in echelon provide thermodynamic conditions and flow channels for activation and migration of deep gold- bearing fluid. The gold- bearing fluid arrived at the shallow crust and mineralization occurred in the decompression and expansion space of fault attitude change.

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Song Mingchun, Ding Zhengjiang, Liu Xiangdong, Li Shiyong, Li Jian, Dong Leilei, Wei Xufeng, Bao Zhongyi, Wang Bin, Zhang Qibin, Zhang Liangliang, Liu Hongbo, He Chunyan.2022. Structural controls on the Jiaodong type gold deposits and metallogenic model[J]. Acta Geologica Sinica,96(5):1774-1802

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History
  • Received:April 23,2022
  • Revised:May 04,2022
  • Adopted:
  • Online: May 23,2022
  • Published: