矽卡岩矿床的研究现状

本文评述了矽卡岩矿床类型划分、矽卡岩形成的物理化学条件、成矿流体以及矿物成分与矿化关系的某些进展。镁矽卡岩形成于各种深度，而钙矽卡岩则形成于较浅和较低温的环境；限制矽卡岩形成的主要参数是ＣＯ＿２、深度以及岩浆期后诸元素的活度（如Ｍｇ￣（２＋）、Ｃａ￣（２＋）…）、ｐＨ和Ｅ＿ｈ值。当前已应用非平衡热力学去研究矽卡岩成岩成矿过程。接触交代带中存在两种流体，一种来自岩浆，另一种是天水循环来源；同位素资料提供水／岩反应的信息，而Ｓ、Ｐｂ、Ｓｒ等同位素资料提供矿质来源的标志。矽卡岩矿物如辉石、石榴石的化学成分与矿化关系密切，可以指示矿化类型。文中总结了矽卡岩型金矿特点，其蹄、铋矿物及退化蚀变是重要的找矿标志。含矿流体及成矿动力学是今后研究的重要方向。

ADVANCES IN SKARN DEPOSITS

Some progresses in the classification of skarn deposits, physicochemical condi-tions of skarn formation, ore-forming fluids, and the relations between mineral composi-tions and ore-forming conditions are reviewed. Skarn is divided into two types : magnesianskarn and calcic skarn. Magnesian skarn was formed at all depths at magmatic stage butcalcic skarn was formad only at lower pressure and temperature. The main parameterswhich control the formation of skarns are aco_2, p, PH, En and the activities of elements(such as Ca￣(2+), Mg￣(2+)…) . Nonequilibrium thermodynamics and kinetics have been used tostudy skarn-forming and ore-forming processes. There were two types of fluids in contactmetasomatic zone, one derived from magma and the other from meteoric hydrothermal sys-tem. Stable isotope data (such as C, O) provide information on water/rock ratios, whileS, Pb, Sr isotopes indicate sources of ore-forming materials. There are close relationshipsbetween the compositions of skarn minerals and the types of mineralization. The charac-teristics of skarn gold deposits are summarized in this paper. The occurances of Bi- andTe-bearing minerals and retrograde alteration are important criteria for gold prospecting.Researches on skarn diposits in the future will be focused on studies of ore-forming fluidsand kinectics.