陕西山阳色河铺地区隐爆角砾岩特征及其铜矿找矿意义

Characteristics of Cryptoexplosive Breccia and Its Prospecting Significance in the Copper Deposit in Sehepu,Shanyang County,Shaanxi Province

陕西山阳色河铺地区位于南秦岭印支褶皱带东段、凤镇-山阳大断裂近南侧。区内广泛发育隐爆角砾岩,其受凤镇-山阳大断裂及其次级断裂和云镇-冷水沟-牛耳川复背斜的联合控制。隐爆角砾岩是岩浆前锋在近地表封闭条件下发生剧烈爆炸所形成的一套浅成—超浅成（0.5~3km）相碎屑岩建造。隐爆角砾岩可进一步划分为熔浆质隐爆角砾岩、混合质隐爆角砾岩、热液震裂岩3类。从岩石学、岩石化学、微量元素、稀土元素特征等方面对其进行初步的研究,认为它们在空间上紧密共生,具一定的分带性,其间呈过渡关系。该区蚀变、矿化主要发生在热液震裂岩中,在混合质隐爆角砾岩中很少,在熔浆质隐爆角砾岩中更少见。蚀变和矿化类型有黄铁矿化、碳酸盐化、硅化、镜铁矿化、石英铁白云石化、黄铜矿化、孔雀石化等,具有Hg、Sb、As异常。热液震裂岩是容矿岩石,是寻找铜矿的主要勘查对象。Hg、Sb、As可作为找Cu的指示元素。

The Sehepu area in Shangyang, Shaanxi province is located at the east of Indosinian fold belt in the southern Qinling, and the south of Fengzheng -Shanyang fault. Cryptoexplosive breccia is widely developed in this region and controlled by the Fengzheng-Shanyang fault and its secondary fracture combined with Yunzheng-Lengshuigou-Niuerchuan anticlinorium. Cryptoexplosive breccia is a set of hypabyssal and ultra-hypabyssal （0.5-3 km） facies clastic rock formation formed by violent explosions of magmatic front occurred under the closed condition in the near surface. Cryptoexplosive breccia can be further divided into magmatic cryptoexplosive breccia, mixed cryptoexplosive breccia, and hydrothermal cryptoexplosive breccia. According to the preliminary research of petrology and geochemistry, we think they are symbiosis on space, with some zonality and transition of each other. The alteration and mineralization occurred mainly in hydrothermal cryptoexplosive breccia, rarely in mixed cryptoexplosive breccia and less in magma cryptoexplosive breccia. The types of alteration and mineralization contain , carbonatization, silicification, specularite-quartz-ankerition, chalcopyrition, malachition et al. , with Hg, Sb and As anomaly. Hydrothermal cryptoexplosive breccia is the ore-bearing rock and the main exploration target for copper. In addition, Hg, Sb and As can be used as indicator elements for prospecting of copper deposit.