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Title:: Characteristics of Ore-controlling Structures of Huachanggou Orogenic Gold Deposit in Mianlue Area of Shaanxi, China

Author(s):: YANG Hao; WANG Dong-sheng; WANG Zong-qi; WANG Li-xin; CHEN Lei; 1. School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China; 2. MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China; 3. Huachanggou Gold Deposit of Lueyang County, Shaanxi Province, Lueyang 724312, Shaanxi, China

Keywords:: structural analysis; orogenic gold deposit; tectonic stage; contraction; strike-slip; Indosinian; Shaanxi

Abstract:: Huachanggou orogenic gold deposit is located on the northwest side of Mianxian-Lueyang-Ningqiang metallogenic belt, which belongs to Shaanxi-Gansu-Sichuan metallogenic province. Macro- and micro-structural observations were conducted in the ore district and peripheral area; based on the previous results obtained in the orefield, the ore-controlling structures of Huachanggou gold deposit were analyzed accordingly; combined with the tectonic evolution, the effect and control of structures on mineralization were discussed. The results show that there are at least two stages of tectonic movements in Huachanggou mine during Indosinian, i.e. intensively SN-direction contraction (D₁) results from the subduction-collision process and nearly EW-direction strike-slip (D₂); EW-direction strike structures (schistosity and tight folds), which are formed by SN-direction contraction (D₁), are main host structures; metallogenic material (auriferous pyrite) transfers to the hinge of folds, causing the enrichment of orebodies; EW-direction strike-slip (D₂) contributes to the formation of ductile shear belts, including dextral shear and left shear movements; ductile shear belts intensely reform the auriferous pyrite, leading to the formation of microcracks, which may supply the room for gold; this plays an important role on the enrichment of orebodies and belongs to host structures. It is suggested that Huachanggou gold deposit is closely related to orogenic processes.