环太平洋地区的矽卡岩矿床

环太平洋地区是世界上最重要的巨型矽卡岩矿床成矿带。在地跨亚、美、澳三大洲二十多个沿岸国家中,共分布有一千多个不同类型的矽卡岩矿床。按含矿矽卡岩主要金属元素的不同,可把本区矽卡岩矿床划分为铁、铜、铅-锌、钨、锡、钼、金七类。文中对各类矽卡岩矿床的分布和主要地质特征作了概括介绍。按含矿矽卡岩矿物组合的不同,又可分为镁矽卡岩型、钙矽卡岩型、锰质矽卡岩型和碱质矽卡岩型四类。太平洋东西两岸的矽卡岩矿床有许多共同点,但在矿化强度、分布规律和成矿时代等方面又有一定差异。文中还论述了本区矽卡岩矿床的成矿系列和岩浆岩成矿金属性问题。

Skarn deposits in the circum-pacific belt

The Circum-Pacific region is one of the most important gigantic skarn-metallogenic belts in the world. In more than 20 coastwise countries of this region, there exist thousands of skarn deposits of different types. According to the differences in major metallic elements, the skarn deposits may be classified into seven subtypes, i.e., iron, copper, lead, zinc, tungsten, tin, molybdenum and gold skarn deposits. In this paper, the distribution and geological characteristics of the above-mentioned types of skarn deposits are described briefly. Skarn deposits may also be classified on the basis of the dominant calc(magnesian)-silicate mineral assemblages into four types, i. e., magnesian, calcic, manganoan, and alkaline skarn types. Magnesian skarns may be associated with iron, copper, gold, tin, boron and beryllinm mineralizations, calcic skarns are concerned with iron, copper, tungsten, molybdenum, gold, beryllium, lead, zinc and tin mineralizations, manganoan skarns are only related to lead and zinc(silver) mineralizations, and alkaline skarns occur together with uranium(thorium, niobium)deposits. Although skarn deposits along both east and west Pacific rims have many general characteristics, they show some differences in geotectonic setting, mineralization intensity, distribution and metallogenic epoch. In this paper, ore-forming series and metallogenic specialization of magmatic rocks related to skarn deposits are also discussed.