智利中部埃尔特尼恩特斑岩型铜钼矿床地质、成矿特征及成因

智利中部埃尔特尼恩特矿床是世界级超大型铜钼矿床之一,其铜矿石(含铜0.62%)储量达12.4×10~8t,钼矿石(含钼0.018%)储量达7.8×10~8t。矿床位于智利中部安第斯山脉晚中新世—早上新世铜-钼成矿省。该成矿省赋存于晚中新世火山活动带。埃尔特尼恩斑岩型铜-钼矿床赋存于中—晚中新世代伐尔隆斯建造,后者伏于科亚-玛查理建造之下,两者之间呈构造不整合或局部不整合接触关系。矿床产于伐尔隆斯的组成部分晚中新世火山深成杂岩中,该杂岩由厚层的玄武质至流纹质喷出岩及侵入岩组成。矿床围岩为安山岩、长英质-中性侵入岩和布莱登岩筒角砾岩。该矿床流体包裹体组合特征表明,岩浆热液演化及成矿作用经历了4个阶段。流体包裹体成分研究表明,该矿床的形成是富含Cu和可能还富含S的深源流体向不断脱挥发分的巨型次火山岩浆房发生贯入作用的结果。

Geology, metallogenic features and genesis of the El Teniente porphyry copper-molybdnum deposit in Central Chile

The El Teniente deposit, one of the world''s largest known copper-molybdenum deposits, contains 12.4 billion metric tons copper ore at 0.62 percent Cu and 7.8 billion metric tons molybdenum ore at 0.018 percent Mo. It is located in the Late Miocene to Early Pliocene copper-molybdenum metallogenic province of Central Chile Andean Cordillera. The deposit occurs in a Late Miocene volcanic active belt. The mid-Late Miocene Farellones Formation hosts the El Teniente copper-molybdenum deposit. The Farellones Formation is underlain by the Coya-Machali Formation. The contact between the two formations is structural or locally unconformable. The El Teniente deposit occurs in a late Miocene volcano-plutonic complex, which is part of the Farellones Formation, consisting of a thick sequence of eruptive and intrusive rocks of basaltic to rhyolitic compositions. The main host rocks of the deposit are andesites, felsic-intermediate intrusive rocks and the Braden pipe breccia that intruded into andesites. The characteristics of the fluid inclusion assemblages suggest that the hydrothermal activity and mineralization at El Teniente can be divided into four stages. The fluid inclusion component research shows that the ore-forming process of the El Teniente deposit resulted from injection of a deep-sourced Cu-rich and probably S-rich fluid into a more continuously devolatilizing subvolcanic large magma chamber.