GEOLOGY AND GENESIS OF ZHULAZHAGA GOLD DEPOSIT, INNER MONGOLIA, CHINA
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摘要: 朱拉扎嘎金矿是一个大型矿床,赋矿围岩为中元古界变质钙质砂岩、粉砂岩、板岩、大理岩、流纹岩.主矿体和围岩产状基本一致.划分出两个矿带,总体走向35°.矿体受层间裂隙控制,共发现56个矿体,规模为长10余米到300 m,厚度几十厘米到4.5 m,延伸可达200 m.主要蚀变有透辉石化、阳起石化、绿帘石化、冰长石化,还有碳酸盐化、绿泥石化、硅化.矿石类型有蚀变变质砂岩型、蚀变火山岩型、交代岩型、喷流沉积岩型和石英脉型.自然金和银金矿是矿石中金的最主要赋存形式.含金较高的原始沉积岩层,比较发育的层间裂隙或破碎带,与多次构造活动相伴的多次热液活动和多次矿化作用,便形成本区的岩浆热液蚀变型金矿床.Abstract: Zhulazhaga gold deposit, located in Inner Mongolia Autonomous Region, is the first large-scale deposit found in the Middle-Upper Proterozoic strata along the western part of the north margin of North China Platform. The wall rocks of the ore bodies are a series of epimetamorphic rocks, which are mainly composed of metacalcareous sandstone, siltstone and slate with minor thin-bedded carbonate rocks. The authors discover the widespread acidic volcanic rocks within the strata. The occrrence of the main ore body is similar to that of the wall rocks. The intensive hydrothermal alteration in the deposit is closely related to the ore-forming process. Five ore types are identified, which are SEDEX type, altered volcanic rock type, altered sandstone type, metasomatic rock type and quartz vein type. Most gold minerals appear as native gold and electrum. Based on the detailed research, it is supposed that the mineralizing process may experience two epoches. In the earlier epoch, the SEDEX type of mineralized beds was formed during the Middle Proterozoic volcanic activity. During the latter epoch, different types of ore and orebodies were formed in the gold-bearing thermal fluid, when the fluid was evolved from the granitic magma which intruded during the late Hercynian movement, and replaced the wall rocks intensively. The apperance of the quartz vein type of orebodies demostrates the end of the endogenetic ore forming.
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Key words:
- gold deposit /
- altered rock type /
- magmatic hydrothermal fluid /
- granite-porphyry /
- Zhulazhaga /
- Inner Mongolia
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