论中国金矿床成矿时代特点

中国金矿床成矿时代特点可以概括为“一老一新成矿 ,东西南北有别”。“一老一新成矿”表现为主要成矿时代为早元古代 (2 6 0 0～ 14 0 0Ma)和中生代 (部分晚古生代 30 0～ 10 0Ma) ,且中生代形成的金矿床所占的比例更大。“南北有别”表现为 :我国早期成矿作用在扬子地块和华南地区主要以中元古代 (180 0～ 14 0 0Ma)为主 ,而华北地区以早元古代 (2 6 0 0～ 180 0Ma)为主 ,甚至存在晚太古代的金矿床 ;我国晚期成矿作用在华南地区以印支期—燕山早期为主 (如海南—粤西地区为 2 30～ 190Ma) ,在华北、胶东地区为燕山中晚期 (14 0～10 0Ma)。“东西有别”表现为我国东部地区中生代是金矿床成矿的最重要时期 ,而西部地区晚古生代是金矿床成矿的重要时期 (以北山、天山和北疆地区最明显 ,成矿年龄以 30 0～ 2 30Ma为主 )。同时 ,我国的金矿床普遍具有“成矿物质来源老 ,矿床定位年龄新”、“多期成矿作用叠加明显”和以“岩浆热液型为主”的特征。上述特征是受中国独特的大地构造及其演化历史所控制的。

A DISCUSSION ON THE METALLOGENIC EPOCH OF GOLD DEPOSITS IN CHINA

The metallogenic epoch of gold deposits in China can be summarized as "one older epoch and one younger epoch, different between the east and the west and between the south and the north of China". The older gold metallogenic epoch from Neo Archean era to Paleo Mid Proterozoic (2 600～1 400 Ma), and the younger metallogenic epoch is mainly in the Mesozoic era and partly in the Upper Paleozoic era (300～100Ma). The older gold metallogenic epoch ranges from Neo Archean to Paleo Proterozoic (2 600～1 800 Ma) in North China, but Mid Proterozoic (1 800～1 400 Ma) in South China, while the younger metallogenic epoch is from Yanshanian (140～100Ma) in North China (e.g. Jiaodong area) to Indo Chinese (230～190Ma) in South China (Hainan, West Guangdong, and part of Fujian ). Similarly, Mid Proterozoic (140～100Ma) is the most important metallogenic epoch in East China, but Upper Paleozoic (300～230Ma) is only in West China (Beishan, Tianshan and North Xinjiang are the typical areas). Meanwhile, gold deposits in China have some other features: (1) the age of metallogenic material is much older than the age of the deposit; (2) multi periodic superimposed metallogenesis is very common; and (3) gold deposits of the magmatic hydrothermal type are the most important in China. All above is controlled by the distinctive geotectonic framework and evolutionary history of China.