新西兰科罗曼德尔半岛金(铜)矿床地质特征、成因及找矿意义

Geological features, metallogenesis and prospecting significance of the gold-copper deposits in Coromandel Peninsula, New Zealand

新西兰科罗曼德尔半岛火山岩带是世界知名的浅成低温热液型金矿成矿省，也是新西兰最为重要的金银矿矿集区，在环太平洋成矿带内占有重要的地位。科罗曼德尔半岛浅成低温热液型金矿主要赋存于科罗曼德尔群中新世安山岩和英安岩中，矿化类型主要为石英脉型和角砾岩型2种。矿床的成矿流体特征表现出明显的大气降水特征，并显示有少量的岩浆水加入，成矿物质具岩浆来源特征，为石英±方解石±冰长石±伊利石亚型浅成低温热液型金矿。区内金矿成矿时代为16．3-2．0Ma，主要集中于7．0-6．0Ma之间，金矿的大规模形成与诺特兰德火山弧与科尔维一劳火山弧共同作用有关，区域构造背景由挤压转变为伸展环境的转折期，为金矿形成的高峰期。区内零星出露与浅成低温热液型金矿化有关的斑岩型铜矿化表明，该地区具有较好的斑岩型铜矿化潜力。

Coromandel volcanic zone is a world-famous epithermal gold metallogenic province, and is also the most important goldsilver ore concentration area in New Zealand. Ore deposits in the Coromandel epithermal gold ore field occur mainly in Miocene andesites and dacites of Coromandel Group, with the mineralization mainly consisting of quartz vein type and breccias type. The ore-forming fluid in the deposit shows the characteristics of meteoric water mixed with minor magmatic water, whereas the ore- forming materials indicate magmatic origin, thus belonging to the quartz±calcite±adularia±illite hypotype epithermal gold deposit. The metallogenic epoch is between 16.3Ma and 2.0Ma with the climax time at 7.0~6.0Ma. Large-scale formation of the gold ore field was related to the combined action of the Northland volcanic arc and the Colville-Lau volcanic arc, and gold mineralization reached a peak during the transformation process of the regional tectonic setting from contraction to extension. The sporadically outcropped porphyry copper mineralization associated with epithermal gold mineralization suggests great potentials of porphyry copper mineralization in this region.