Source of Fluid and Genesis of Jinchangzi Gold Deposit in Weiningbeishan, Ningxia: Evidence from Fluid Inclusions and C-H-O Isotopes

被引：2
|
作者：
Hai L. [1 ,2 ,3 ]
Liu A. [4 ]
Tao R. [3 ]
Bai J. [3 ]
Song Y. [3 ]
机构：
[1] School of Earth Resources, China University of Geosciences, Wuhan
[2] National Demonstration Center for Experimental Mineral Exploration Education, Wuhan
[3] Mineral and Geological Survey Institute of Ningxia Hui Autonomous Region, Yinchuan
[4] Yifu Museum of China University of Geosciences, Wuhan
来源：
Liu, Anlu (3515669203@qq.com) | 1600年 / China University of Geosciences卷 / 46期
关键词：
Fluid inclusions; Genesis of ore deposit; Jinchangzi gold deposit; Source of ore-forming fluid; Stable isotope; Weiningbeishan;
D O I：
10.3799/dqkx.2021.101
中图分类号：
学科分类号：
摘要：
The Weiningbeishan area is the most promising polymetallic ore target area in Ningxia, where numerous Au, Ag, Cu, Pb, Zn, Fe, Co, and other ore occurrences have been found. The Jinchangzi gold deposit is the largest gold deposit found in the area, and the ore bodies are mainly hosted in the intra-layer fault fractures, with an east-west distribution and near-uniform with the bedding. Magmatism is weak in this district, with several diorite porphyrite having been identified in exposures adjacent to the gold veins. In order to explore the nature, source and genesis of the ore-forming fluid of the Jinchangzi gold deposit, the fluid inclusions and C-H-O isotopes in the study area were studied. The ore-forming hydrothermal period of the deposit can be divided into 4 metallogenic stages, from early to late, they are sericite-pyrite-quartz stage (Ⅰ), pyrite-barite-quartz stage (Ⅱ), polymetallic sulfide-carbonate-quartz stage (Ⅲ) and pyrite-carbonatite stage (Ⅳ), of which stage Ⅲ is the main metallogenic stage. There are four types of fluid inclusions in the mineralization stage, which are aqueous solution inclusions, pure CO2 inclusions, CO2-H2O inclusions and multiphase inclusions containing daughter crystals. The completely homogenous temperature of the ore-forming fluids is between 171-396 ℃, the salinity is between 1.30%-10.99% NaCl equiv, and the density is 0.24-0.78 g/cm3, which are CO2-H2O-NaCl systems with medium-low temperature, low salinity, low density, CO2 rich, and a small amount of N2. The δD value of hydrothermal quartz is -66.0‰ to -32.0‰, and the δ18OV-SMOW value is (+19.7‰)-(+22.6‰), indicating that the ore-forming fluid is metamorphic and the magmatism is not obvious. The C isotope shows that the δ13C of calcite and siderite in the late stage (stage IV) is between -2.540‰ and -0.736‰, indicating that C in the ore-forming fluid has the characteristics of mixed sources. The fluids formed by the metamorphic dehydration of Ordovician-Carboniferous terrigenous clastic rocks and carbonate rocks may be the main source of gold ore-forming fluids. During the ore-forming process, the fluids had an obvious immiscibility phenomenon, which was an important factor causing gold precipitation. The genetic type of the deposit is an orogenic gold deposit. © 2021, Editorial Department of Earth Science. All right reserved.
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页码：4274 / 4290
页数：16
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