摘要
近十几年来，含金夕卡岩矿床的勘查与研究在国内外取得了很大的进展，发现了一批大型矿床，从而引人注目。含金夕卡岩矿床主要集中分布于环太平洋成矿带，按其产出构造环境可分为三类，即中（新）生代褶皱带、古生代褶皱带和地盾（台）区。控矿地层主要为石炭—二叠系和三叠系碳酸盐岩，次为第三系和寒武系等。有关岩浆岩大多为浅成钙碱性中酸性侵入岩，属Ⅰ型；时代以燕山期和喜山期为主，少数为华力西期、加里东期和印支期。含金夕卡岩绝大多数为钙夕卡岩，只有少数属镁夕卡岩，又可进一步划分为还原型和氧化型。金属矿物组合的特征是常有砷化物、铋化物和碲化物存在，Ｃｕ，Ａｕ，Ａｇ，Ａｓ，Ｂｉ，Ｔｅ，Ｃｏ和Ｓｅ等元素组合是含金夕卡岩特征性的地球化学标志。矿床（田）常具明显的交代矿化分带，并可构成一定成矿系列，其综合交代矿化分带模式，自岩体向碳酸盐围岩方向依次为：Ｃｕ（Ｍｏ）→Ｃｕ（Ｆｅ）→Ｃｕ（Ａｕ）→Ａｕ→Ａｕ（Ｐｂ，Ｚｎ，Ａｇ）。矿物共生组合和流体包裹体研究表明，夕卡岩矿物形成于６８０～３２０℃，盐度为ｗ（ＮａＣｌ）＝５９５％～１８６％，金的沉淀发生在夕卡岩期后的退化热液交代阶段，大致相当于温度为３５０～１５３℃，盐度ｗ（ＮａＣｌ）＝２４％～?
In the past decade, great progress has been made in the exploration and investigation of gold skarn deposits in the world and many large deposits have been discovered. Au bearing skarn deposits are distributed mainly in the Circum Pacific metallogenic belt. According to their tectonic settings may be divided into three types: the Mesozoic / Cenozoic fold belts, the Paleozoic fold belts, and the shield/platformal areas. The Au bearing skarns are hosted mainly by Carboniferous Permian and Triassic carbonate clastic pyroclastic formations, subordinately Tertiary, Cambrian, and et al. The related intrusives are mainly hypabyssal calc alkaline intermediate and intermediate acid diorite, quartz monzodiorite, quartz monzonite, granodiorite and the rocks of their hypabyssal facies. Most of them are of Yanshanian and Himalayan, locally, are of Caledonian or Uariscan. The Au bearing skarns are chiefly calcic, only a few are magnesian. The later occurs in the mobile platform or shield. Most of the Au bearing skarns occurring in the island arc setting consist mainly of hedenbergites and belong to the reducing type, but in the mobile platform, the Au bearing skarns are chiefly composed of andradite and diopside, and belong to the oxidizing type.In the ores, gold is often intimately associated with arsenides, bismuthide, and tellurides. In many Au skarns occurring in the mobile platforms, the selenides are identified. Therefore, Cu, Au, As, Bi, Te, Ag, Co(Se) are more specific metallic elements for Au bearing skarns, and referred to as an important geochemical ore searching indicators. In many gold skarn deposits the mineralized zone is very clear. The comprehensive zonal model from intrusive to carbonate wall rocks is : Cu(Mo)→Cu(Fe)→Cu(Au)→Au→Au(Pb,Zn,Ag). The study of mineral paragenesis and fluid inclusions suggests that the gold minerals were precipitated in the postskarn retrograde metasomatic stage in the temperature 350～153℃ with salinities w (NaCl)=24%～2.5%. Skarns were formed in the temperatures 680～320℃ with salinities w (NaCl)=59.5%～8.7%.
出处
《地学前缘》
EI
CAS
CSCD
1999年第1期181-183,共3页
Earth Science Frontiers
基金
国家自然科学基金
关键词
含金
夕卡岩矿床
构造环境
地质地球化学
Au bearing skarn deposits, tectonic environment, geologic geochemistry, evaluation criterion
