新疆和静县大山口金矿床地质特征及其与穆龙套金矿床对比

GEOLOGICAL CHARACTERISTICS OF DASHANKOU GOLD DEPOSIT IN HEJING COUNTY OF XINJIANG: CONTRAST WITH MURUNTAU GOLD DEPOSIT

大山口金矿区赋矿地层为上志留统 -下泥盆统大山口组含碳细碎屑岩建造 ,赋矿构造为大山口韧性剪切带 .矿区总体构造线走向NWW向 ,总体构造格架为大山口断裂和可肯达板断裂两个断裂所夹持的乌兰赛尔 -大山口韧性剪切带 ,该剪切带宽度 2～ 3km ,长度大于 10 0km ;矿区内长度大于 1 7km ,强剪切带宽度 3 0 0～ 5 0 0m .韧性剪切带宏观上表现为强烈的片理化带、S -C组构、b型褶皱、构造透镜体发育 ,石英细脉表现为肠状褶曲 .剪切带主要由糜棱岩和糜棱岩化岩石组成 .大山口金矿床即产于该韧性剪切带内 ,由石英大脉 -网脉及其边部的蚀变糜棱岩构成金矿石 ,金矿体几乎无一例外地均产于大山口韧性剪切带内 .矿区内未见有大的侵入岩体出露 ,但是有较多的闪长岩、英安斑岩岩脉侵入于韧性剪切带内 .将矿床与乌兹别克斯坦共和国境内的穆龙套金矿床进行了对比 ,并参考了穆龙套金矿区超深钻新资料 .通过对比可以看出 ,两矿床的成矿地质条件基本相同 ,应属于同一个金矿类型 ,但也存在一定的差别 .我们认为 ,在大山口金矿区 ,除应进一步加强区域上金矿成矿条件的勘查与研究外 ,应注意深部成矿的勘查与研究 ,以期解决大山口金矿床地表金矿化“只见星星、没有月亮”的困境 .

Dashankou gold orebodies are situated in Upper Silurian Lower Devonian carbon containing fine grained clastic rocks of Dashankou fm.The ore control structure is Dashankou ductile shear zone.The general structure in the mine trends NWW.The main tectonic framework is Wulansaier Dashankou ductile shear zone which is confined by Dashankou and Aikendaban faults.The ductile shear zone is 2～3 km wide and more than 100 km long. In the ore district the outcropping length of the ductile shear zone is 1 7 km and the width of strong shear mylonite zone is 300～500 m. The ductile shear zone shows as an intense schistosity zone.The S-C febrics,b type folds and structural lenticules are commonly seen,and the quartz veinlet appear in ptygmatic folds.The ductile shear zone consists of mylonite and mylonitized rocks.Dashankou gold deposit,whose ore is composed of quartz vein,stockwork quartz veinlet and alteration mylonite,is located in the ductile shear zone.The gold orebodies all occur in the mylonite and mylonitized rocks.There are no bigger intrusive rock mass.Some veins of diorite and dacite intrude into the ductile shear zone.This paper studies Dashankou gold deposit by contrasting it with Muruntau gold deposit on ore bearing formation,ore control structure,magmatism,orebody characteristics,constitution of mineral and element,scale of gold deposit and mineralized area,and also referring to the newest data of ultradeep drill of Muruntau gold deposit.The conclusion is that the two gold deposits belong to the same type although they have some differences.The authors also emphasize that more attention should be paid to the exploring and researching on deep mineralization besides on regional mineralization condition,in order to resolve the problem that “there are plenty of smaller gold orebodies but not bigger ones in Dashankou goldfield”.