摘要
本文通过微量元素、稀土元素及铅、硫同位素研究,对龙山金锑矿床成矿物质来源作了详细探讨。研究认为龙山及湘西一带在中晚元古界至震旦系中发育有金的富集层。龙山金锑矿床有两期矿化:第一期为Cu-P(?)-Au矿化;第二期为Sb—Au矿化。第一期矿化成矿物质来自深部较老地层,第二期矿化成矿物质来自控矿地层。
The Longshan gold-amimony deposit, lying on the well-known gold ore belt of western Hunan, occurs mainly in the veinlike or filling forms within the fracture zone of Jiangkou Formation. Two stages of mineralizations can be recognized in this deposit: the first stage is dominated by Cu-Pb-Au and the second by Sb-Au.
The ore-controlling strata have rather high Au and Sb contents and are basically consistent with the second stage mineralization in Pb/Zn and Cu/Pb molar ratios and REE patterns, suggesting that the metallogenic materials of the second stage mineralization were derived from the ore-controlling strata.13 samples from the first and second stage mineralizations and the ore-controlling strata have been analysed for lead isotope composition. Stibnite from the second stage mineralization is similar to ore-controlling strata in lead isotope composition and model age; Galena from the first stage mineralization is different from the ore-controlling strata and stibnite in lead isotope composition, and its model age is 950 Ma, being larger than the oldest age of the ore-controlling strata. All these data suggest that ore materials of the second stage mineralization came from the ore-controlling strata, while those of the first stage mineralization were derived from the older strata at depth.The δ^(34)S values of various sulfides in the deposit range from -3‰ to +5‰, the δ^(34)S_(∑s) values of ore-forming fluids are from -5‰ to +7‰, and the δ^(31)S value of the fine-grained pyrite from the unmineralized strata is about +9‰.The total sulfur falls in the magma region; Nevertheless, as volcanic rocks of this area are not developed, it is quite unlikely that the sulfur came from the volcanic materials. The small δ^(34)S value and its unremarkable variation are probably attributed to the homogeneous mixing of isotopically light sulfur in the fluids with heavy sulfur in ore-bearing strata.
出处
《矿床地质》
CAS
CSCD
北大核心
1989年第4期39-48,共10页
Mineral Deposits
