随州淮河—小林地区燕山期构造银金控矿作用研究

Study of Electrum Ore-controlling Role of Yanshanian Structure in Huaihe-Xiaolin Area

淮河—小林地区与河南桐柏处于同一成矿带上,成矿条件十分优越。同河南桐柏相比,淮河—小林地区银金矿受陡倾断裂控制作用明显。对淮河—小林地区燕山期南北向、北东向断裂蚀变带进行了较为系统的岩石构造地球化学取样。分析及统计表明,南北向断裂控银、北东向断裂控金作用明显。该区燕山期岩浆岩出露规模大,由于岩浆的侵位作用,在岩体内部,古老的北西向构造(断裂)被呑噬,金银主要受南北向和北东向断裂蚀变带控制。该区地表南北向和北东向韧性剪切带不发育,表现为脆性断裂控矿,银金矿(化)体在规模上不可能与北西向大型层控矿床相比。南北向、北东向断裂蚀变带中的地表氧化矿品位普遍偏低,往下变富。因此,加强南北向、北东向断裂蚀变带中的地表氧化矿的寻找和综合评价,对于找矿突破意义十分重要。

Huaihe-Xiaolin area and Tongbai are in the same metallogenic belt, the metallogenic conditions are very favorable. In contrast with Tongbai, electrum deposits are obviously controlled by steep dipping fault in Huaihe-Xiaolin area. In this paper, the authors have carried out a systematic and geochemical sampling of rocks structure in Ns-trending and Netrending fracture alteration zone of Huaihe-Xiaolin area. Analysis and statistics show that the effects of Ns-trending silvercontrolling and Ne-trending gold-controlling are obvious. The Yanshanian magmatic rocks outcrop on a large scale, due .to the role of magma emplacement, NW-trending fracture is phagocytosed inside rock mass. Gold and silver deposits are controlled by Ns-trending and Ne-trending fracture alteration zone. Compared with Tongbai, ductile shear zones in Ns-trending and Ne-trending are not developed in this area, which is brittle fracture. The surface oxidized ore grade is generally low. Therefore,it is very important to strengthen the exploration and comprehensive evaluation of surface oxidation in Nstrending and Ne-trending fracture alteration zone.