斑岩钨矿床及其成矿花岗岩

Porphyry Tungsten Deposits and Their Ore—forming Granites

已知典型矿床研究表明,斑岩钨矿床具以下基本特点:(1)成因上与特定的岩浆岩建造密切相关。(2)空间上受深断裂控制成群成带分布。(3)受含矿母岩浆制约具特定的蚀变类型组合及其分带规律。(4)常与Cu、Mo、Pb,Zn、Au、Ag等伴生成矿。形成斑岩钨矿床的所谓特定的岩浆岩建造,成因上属作者所划分的过渡型花岗岩类的花岗质潜火山杂岩;时代上集中于燕山早期晚阶段(晚侏罗世)、构造演化阶段处于陈国达教授所划分的地洼发展阶段激烈期。杂岩体演化成矿是斑岩钨矿床形成的基本途径;其成矿岩体几乎无一例外地均是岩浆充分分异演化的分异杂岩体。但随着杂岩体由早而晚岩性由基而酸的演化,壳质组分向岩浆晚期的逐渐聚集,斑岩钨矿床的形成总是与杂岩体既期高酸富碱富挥发分的壳质斑岩直接相关。所以,斑岩钨矿床既具与斑岩铜矿床相类似的成岩成矿机理,又具与斑岩铜矿床明显有别的成岩成矿物质来源。前者是斑岩钨矿床赖以确立的依据;后者则决定了斑岩钨矿与斑岩铜矿不同的含矿岩体岩石—地球化学标志及其找矿方向。

The priliminary research on known typical porphyry tungsten deposits has proved that the deposits are characterized by the following: (1) genetically, they have a close relationship with a certain specific magmatic formation, (2)spatially, they are controlled by deep fualts and distributed in the form of groups and zones, (3)they are restricted by ore-bearing parent magma, and have a specific type of altered mineral assemlage and a particular alteration zoning, (4)they are usually accompanied by such elements as Cu, Mo Pb, Zn, Au, Ag, and others. Tne So-Called specific magmatic formation forming porphyry tungsten deposits genetically belongs to a granitic subvocanic complex (named by the author) of transitional type granitoid. It came into being mostly in the late stage of the Ear- ly Yanshanian Oreginic Cycle(the late Jurassic), 1. e., the intense phace of Diwa development proposed by Prof. Chen Guoda. The main way of the formation of the porphyry tungsten deposits is through the evolution of the complex. Their ore-forming rock bodies are almost exclusively the differentiated complex formed by full differentiation of magma. It is obvious that with the evolution of the complex from basic in the early stage to the acid in the late, and the gradual concentration of the CrustComponent in the magma, the crust component-bearing porphyry with high acid, alkali-and volatiterich matters would be formed. It is this kind of crust component-bearing porphyry that has a direct relationship with the formation of porphyry tungsten deposits. Judging from this, the porphyry tungsfen deposits have both a diagenetic and minerogenic mechanism similar to that of porphyry copper deposits, anda diagenetic and minerogenic matetral source obviously different from that of porphyry copper deposits. The iormer is the foundation on which the porphyry tungsten deposits rely for existence. The latter determines the petro-geochemical prospecting criteria and target of the porphyry tungsten deposits, which are different from those of porphyry copper deposits.