菲律宾北甘马仁省杜马可(Domaco)铁(铜)矿床地质特征及成因

Geological characteristics and genesis of the iron (copper) ore deposit in Domaco, Camerines North,Philippines

杜马可(Domaco)铁(铜)矿床产于菲律宾板块俯冲吕宋岛被动陆缘岛弧带上,处于菲律宾中央走滑断裂带近旁。含矿层位于古近系渐新上统蚀变安山岩、角砾岩和古新统的角岩、角岩化页岩的喷溢角度不整合追踪断裂带上。矿质发育大面积的安山岩、角砾岩的褪色化蚀变和带状展布的灰绿色热液交代蚀变岩系,矿体就产于蚀变岩系中,呈似层状,透镜状。铁矿体在上部层位,铜矿体在铁矿体下部,与贫磁铁矿相伴产出,铁矿体伴生铜、钼;铜矿体又伴生铁、钼、金、银和钴等。矿石中的金属矿物以磁铁矿为主,其次有黄铁矿、黄铜矿、辉钼矿、磁黄铁矿和沥青铀矿、自然金等。元素组合除铁、铜、钼外,还有金、银、钴、铀等。与奥林匹克坝、Candelaria(智利)典型的(IOCG)氧化铁型铜金矿床类比,杜马可矿床属于(IOCG)氧化铁型铜矿床新类型。

Domaco iron （copper） deposit is located at the island arc zone, induced by Phillippines plate subducting the passive margin of Luzon Island, and near the central strike - slip zone of the Phillippines. The strata containing minerals exist in the tracing fault zone, which is the effusive angle unconformity interface between the alternation andesite, breccia of the late Paleogene and the hornfelsized shale of the middle Paleogene. These deposits occur in the zone, in which there arefaded alternations of the extensive andesires and breccias, and linear distributed green - grey hydrothermal metasomatism alternations. The orebodies are layer like or lenticular. The iron orebodies are on the upper and the copper orebodies are belowwith the low - grade magnetite. There are the associated dements such as Cu and Mo in the iron orebodies, and the eompanying elements are Fe, Mo, Au, Ag and Co in the copper orebodies. The metal minerals of ore are mainly magnetite, and others are pyrite, chalcopyrite, molybdenite, pyrrhotite and pitchblende, gold. The element assemblages are Fe - Cu - Mo, and Au - Ag - Co - U. Domaco deposit is a new type of （IOCG） Iron - oxide - Copper - Gold Deposits, by comparison with the typical IOCG in Olympic Dam, South Australia and Candelaria, Chile.