华南中、低温成矿带元素组合和流体性质的区域分布规律——兼论华南燕山期热液矿床的巨型分带现象和大规模成矿作用

REGIONAL PATTERN OF ELEMENT COMPOSITION AND FLUID CHARACTER IN MEDIUM_LOW TEMPERATURE METALLOGENIC PROVINCE OF SOUTH CHINA

华南中、低温成矿带主要由江南古陆的“江南型”金＿锑矿带、湘黔汞矿带、西南卡林型金矿区和湘中锑矿带组成。其成矿时代有自东向西从燕山早期到中、晚期有变新的趋势； 矿种分布和成矿元素组合表现出对元古宇基底的继承性； 成矿流体的温度和盐度在大区域内从东到西和自南向北分别呈现降低和增高的趋势， 并且在古陆西、北侧的盆地中有盆地卤水混合的现象。研究表明， 华南中、低温成矿带的时空分布和成矿元素组合演化与华南燕山期花岗岩强烈活动的华南钨（ 锡） 成矿域有密切的联系。这些大型矿集区都集中形成于燕山期， 并与川东南油气田一起， 共同构成了一个自南东向北西的高—中—低温热液矿床和油气矿藏的区域性矿化巨型分带。从而表现出大华南地区（ 东南、中南和西南）

The medium_low temperature metallogenic province in South China is composed of the “Jiangnan_type” gold and antimony belt in Jiangnan old land, the Hunan_Guizhou mercury belt, the Southwest Carlin_type gold zone,and the Central Hunan antimony zone. It holds nearly 80% Sb ore reserves of the world and the same proportion of Hg in China. In the last twenty years, a series of important fine impregnation gold deposits, similar to the Carlin_type ones in the United States, have been discovered in the western belt of the province. Its metallogenic epoch is isotopically dated at 180×10 6 a to 80×10 6 a, mostly falling into Yanshanian and tending to become younger from the early Yanshanian in the southeastern to the middle and late Yanshanian in the northwestern. Similarity in composition and overlapping in space between the association of ore_forming elements in the Proterozoic basement and the economically important metallic paragenesis in the deposits indicates their inheritance relationship. According to the data from nearly thirty important Au, Sb Hg, As and Pb_Zn deposits in this belt, there is an obvious decreasing and in_ crerasing tendency respectively in temperature and salinity of the ore_forming fluids from the east to the west. Salinity of inclusion fluids has a large variation range, from 0.3 to higher than 25 NaCl eq. wt%, in the low temperature Au, Sb and Hg deposits in the western and northern basins around the Jiangnan old land, showing evidence for a strong brine mixing process during the formation of the ore deposits. The present paper suggests that there was a close relationship in origin between the medium_low temperature metallogenic province and the world_class tungsten (tin) province in the southeast during the Yanshanian event though the former hardly had any regional magmatic activity while the latter was always associated with granite. These two provinces make up a huge metallogenic super_province with a continent_scale mineralization zoning composed of pneumatolytic_hypothermal_mesothermal_epithermal_low temperature deposits from the sou_ thestern to northwestern, together with oil_gas and coal fields in southeastern Sichuan. This shows that in Yanshanian the “Pan_South China region” (Southeast China, Central South China and Southwest China) experienced large_scale fluid migration and mineralization under the action of the unified thermal field.