XU Bi-liang¹, TAN Qin-ping^2*, XIA Yong², ZHAO Yi-meng², CHEN Ming³, WANG Ze-peng³

(1. Guizhou Zijin Mining Co. Ltd, Zhenfeng 562200, China; 2. State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China; 3. No. 105 Geological Team, Guizhou Bureau of Geology and Mineral Exploration and Development, Guiyang 550018, China)

Abstract: The Shuiyindong deposit is the largest, concealed, strata-bound Carlin-type gold deposit in the Yunnan-Guizhou- Guangxi region in southwestern China. In this paper, calcites located in five different spatial positions (e.g. fissures of ores, wall rocks, fault zones, altered structural zone of the unconformity between Middle and Upper Permian strata at the Shuiyindong gold deposit, and fissures of surficial unmineralized rocks far away from the Shuiyindong deposit) were collected to analyze their contents of race earth elements (REE), As, Sb, Tl, and Y, in order to reveal the geochemical information of ore-forming fluids, and to explore applicable geochemical indicators of clacites for prospecting concealed gold ore bodies in the Dian-Qian-Gui area. Calcites associated with gold mineralization in fissures/fractures of ore bodies have obviously MREE-enriched distribution patterns with positive Eu anomalies (δEu=1.01-1.51), indicating that the ore-forming fluid could be a relatively MREE enriched and Eu superabundant reductive fluid. The REE patterns and Eu anomalies (δEu=0.60～1.58) of the calcites from other four spatial positions are complex and diverse, showing multi-source, multi-phase, and complexity of those calcites. There is no obvious difference among contents of As, Sb, and Tl of calcites from different spatial locations. It is hard to identify if there is relationship between the gold mineralization and the contents of ore-related elements (such as As, Sb, Tl, etc.) of calcites. In the ？MREE-δEu and Y/Ho-La/Ho diagrams, the calcites in fissures of ores can be distinguished from the calcites occurred in other spatial positions. Thus, these two diagrams can be used to discriminate if the calcites are related to the gold mineralization. It is believed that after the gold precipitation from the ore-forming fluid , the evolved fluid could further continuously migrate along various faults and micro-cracks to the relatively shallow level, and even to the surface of the crust. Therefore, REE characteristics of calcites can be used as a new indicator for prospecting concealed Carlin-type gold deposits in the Yunnan-Guizhou-Guangxi region, southwestern China.

Keywords: Shuiyindong; Carlin-type gold deposit; Calcite; Race earth elements

ACTA MINERALOGICA SINICA Vol. 40, No.6, 2020, page 685-694