智利Candelaria-Punta del Cobre铁氧化物铜金矿床地质和成矿作用

智利Copiapó附近海岸东部边缘有一宽5km、长20km的铁氧化物铜金矿床带,包括Candelaria矿床和位于其北东方向3km处的Punta del Cobre矿集区的中小型矿床。初步估计,该成矿带的铜矿石资源量可达7×108~8×10~8t(含铜量1%)。矿石矿物主要为黄铜矿、黄铁矿、磁铁矿、赤铁矿。矿石产状为脉状、角砾状、细脉状等。含矿围岩主要为Punta del Cobre组的火山岩及火山碎屑岩。该矿带中大部分大型矿脉位于北西—北北西向高角度脆性断层与块状火山岩和火山碎屑岩接触带交汇处。Candelairia矿区主要发育黑云母-钾长石±钙角闪石±绿帘石蚀变矿物组合。在Punta del Cobr矿集区,矿床深部的矿石围岩蚀变情况与Candelairia地区一致,但是浅部的矿石赋存于黑云母-钾长石或钠长石-绿泥石±方解石蚀变带中。

Geology and mineralization of the Candelaria-Punta del Cobre Fe oxide Cu-Au deposits, Chile

There is a 5km wide and 20km long belt of Fe oxide Cu-Au deposits along the eastern margin of the coastal batholith near Copiapó, Chile. It includes the Candelaria deposit and a group of middle and small sized deposits in the Punta del Cobre district, which is located about 3km northeast of the Candelaria mine. It is estimated that the amount of copper ore resources in the belt is 700-800 million tons at 1.0 percent Cu. The ore minerals are mainly chalcopyrite, pyrite, magnetite, hematite. The ores occur in veins, breccia and stringer bodies. The orebodies are hosted mainly by volcanic and volcaniclastic rocks of the Punta del Cobre Formation. Most of the larger orebodies in the belt are situated along NW to NNW trending high-angle brittle faults which intersect the contact between massive volcanic and volcaniclastic rocks. The ores occur mainly in zones with biotite-K feldspar±calcic amphibole±epidote alteration at Candelaria. In the Punta del Cobre district, alteration associated with ores in the deeper parts of the deposits is similar to that at Candelaria, whereas at their shallow levels ores occur in biotite-K-feldspar or albite-chlorite±calcite alteration zones.