甘肃北山地区南金山金矿床隐爆角砾岩体的发现及成矿规律研究

地质研究发现,南金山金矿区出露的下石炭统白山组上岩组的部分岩石为隐爆角砾岩,其中厚层-块状变花岗质砂砾岩为隐爆岩浆角砾岩,厚层-块状变凝灰质砂砾岩为隐爆凝灰角砾岩。隐爆角砾岩体呈近EW向带状分布,隐爆岩浆角砾岩分布于岩体中部,构成岩体的内带,隐爆凝灰角砾岩对称分布于岩体南北两侧,构成岩体的外带。经矿床地质研究,提出了新的认识,认为该矿床的形成受隐爆角砾岩体及隐爆断裂构造的控制,金矿体分布于隐爆角砾岩体外带的隐爆凝灰角砾岩及隐爆断裂中;提出了隐爆角砾岩体外带成矿、对称成矿和双层成矿等3条矿体分布规律。采用EH-4连续电导率成像仪进行了深部地球物理测量,测量结果验证了隐爆角砾岩体控矿及其成矿规律。

Discovery of cryptoexplosive breccia in Nanjinshan gold deposit of Beishan area, Gansu Province and study of metallogenic regularity

The authors discovered for the first time cryptoexplosive breccia in the Nanjinshan gold deposit based on a detailed geological study of the gold deposit. The cryptoexplosive breccia belongs to the Upper Subformation of Lower Carboniferous Baishan Formation. The thick-bedded and massive metamorphic granite glutenite should be cryptoexplosive magmatic breccia, and the thick-bedded and massive metamorphic tuff glutenite should be cryptoexplosive tuff breccia. The cryptoexplosive breccia body shows a nearly EW-extending zonal distribution. The cryptoexplosive magmatic breccia occurs in the center of the rock body, forming an inner belt of the cryptoexplosive breccia body. The cryptoexplosive tuff breccia occurs on the opposite sides of the rock body, forming the outer belt of the rock body. Based on a geological study of the ore body, the authors put forward the new idea that the cryptoexplosive breccia body and cryptoexplosive faults and fractures controlled the formation of the Nanjinshan gold deposit, and the ore bodies are distributed in the cryptoexplosive tuffaceous breccia and the cryptoexplosive faults of the outer belt. The EH-4 electrical conductivity image system was used to measure the sequence resistivity of the cryptoexplosive breccia body and the ore body. The results can prove the correctness of the authors' idea concerning the formation of the Nanjinshan gold deposit and the distribution of the ore bodies.