楚雄盆地有机质、膏盐与砂岩铜矿生成关系的有机地球化学证据与机理

Organic Geochemical Evidence and Meachanism of the Genetic Relationship between Organic Matter, Evaporite, and Sandstone-hosted Copper Deposits in Chuxiong Basin,China

云南楚雄中生代陆相盆地发育了良好的含煤、含铜和含膏盐的三位一体的建造组合。煤、膏盐和砂岩铜矿床中有机质在丰度、类型、成熟度、可溶有机质及生物标志物上既有一定差异，又有一定的相似性。煤和膏盐均参与了砂岩铜矿成矿作用，煤系为改造成矿作用提供了丰富的还原性有机质，膏盐提供了氧化性的ＳＯ２－４，间接提供了硫源。

There occur, from down to up, coal-bearing formation (T 3p T 3g),red cupiferous terrigenous formation(J K 2d) and red evaporite terrigenous formation (K 2j K 2z) in the Mesozoic continental Chuxiong basin, Yunnan Province, China. Differences in and relationships of them were stated in the present paper on the basis of studies on assemblage of formations, total organic carbon(TOC), dispersive organic matter, soluble organic matter and kerogen. Some conclusions were obtained as follows:(1).the Kangdian continental rift controlled the occurrence of evaporites, copper deposits and coals . Sandstone-hosted copper deposits occurred in the red sandstone which formed when the basin withered, and TOC decreased and salt content increased in the lake water. (2). Organic matter (OM) being the type Ⅱ 2 in evaporites had a lower content, and had reached the higher mature stage. However, OM being the type Ⅲ in coal-bearing formation was the richest and had also reached the higher mature stage. OM in copper deposit was the type Ⅲ, but it had even reached the ultimate methane stage. (3). OM and evaporites had played an improtant role in the formation of the copper deposit. OM came mainly from beds and near mudrocks and mobilized and transported copper during the diagenetic mineralization stage. However, during the transformation OM came mainly from coal-bearing formation in the form of reduced copper-and OM-rich deep fluid, while natural water leached evaporites and formed oxidized SO 2- 4-rihc saline water. Metallic sulfide formed during the mixing of deep fluid and SO 2- 4-rich saline water because OM reduced SO 2- 4 into H 2S.