碱性岩相关铜-金(钼)矿床的研究进展

由于超过20%的大型-超大型铜-金(钼)矿床与碱性岩浆有关,因此,该类矿床引起矿床学家的广泛关注。碱性岩有关的铜-金矿床的成矿岩体、物化条件及围岩种类各具特色,成矿成因类型多样,主要的成因类型为斑岩型铜-金(钼)、浅成低温热液脉型金-铜(钼)。总体上,该类矿床的矿化和蚀变具有一定的特征:该类矿床多产出在伸展环境下、均富碲化物矿化、有大量的钾质交代作用、含有氟矿物质和钒云母等,成矿蚀变亦有一定的规律。长英质岩石中经常发生钾长石蚀变,而绢云母、碳酸盐和钾长石的混合蚀变常出现在中基性侵入岩中,水热合成石英和酸性蚀变十分罕见。这种特征矿化可能与碱性岩浆流体演化有关,这种流体富含CO_2,且在高氧逸度、低硫逸度条件下释放。在伸展背景下的碱性-钙碱性省寻找此类矿床具有巨大的勘查潜力,尤其在碱性岩体中心及其外围可能形成勘探的靶区。在中国与碱性岩有关的金矿床亦有广阔的找矿前景,在借鉴国外寻找此类矿床经验的同时,仍需加强对与矿化作用有关的岩浆体活动的研究。

The progress in the study of Cu-Au (Mo) deposits related to alkaline rocks

Cu-Au (Mo) deposits related to alkaline rocks have attracted more and more attention throughout the world, because more than 20% of the world-class Au-Cu (Mo) deposits are associated with shoshonitic and alkaline rocks. Although they include most of the usual types of Au-Cu (Mo) deposits such as porphyry type and gold-rich epithermal deposits, they share the same characteristics of mineralization and alteration on the whole. As a group, these deposits are characterized by Te-rich mineralization, abundant K metasomatism and minerals such as fluorite and roscoelite. Most of these unique mineralization characteristics may be attributed to the evolution of composition of orerelated alkaline magmas, and the fluids were under the condition of CO₂-richness, relative oxidation and low sulfidation. Most Cu-Au (Mo) deposits developed in alkaline provinces in a stretching environment also constitute exploration targets in and around alkaline igneous centers. The perspectives of Cu-Au (Mo) deposits related to alkaline rocks in China are tremendous. To better find new deposits of this type, researchers should pay more attention to petrogenesis and their relation to Cu-Au mineralization.