滇东南老君山矿集区三保锰银矿床碳氧同位素特征及其意义

对三保锰银矿床进行了系统的碳氧同位素及电子探针研究，发现矿石中的菱锰矿和共生方解石的碳同位素值均偏负，氧同位素值为正，而围岩的碳同位素组成在零值附近。研究结果表明：三保锰银矿床的碳可能主要来自地幔源或深部岩浆系统，但是其碳同位素组成并没有完全落在深部地幔δ13C的范围，暗示着成矿流体中的碳除了主要来源于深部系统之外，还加入了部分大气降水循环淋滤围岩中的碳。该矿床的矿体展布形态以似层状、透镜状和囊状为主，而并非规则层状。另外，微区矿物学还发现矿石中还有少量的典型岩浆型副矿物，如锆石和金红石等。上述研究结果表明，该矿床应属于热液成因，而非一般的海相沉积型。该研究成果不仅阐述了锰银矿床的稳定碳氧同位素特征，而且有助于深化对矿床成因的认识，丰富找矿信息，从而提高找矿效果。

Carbon-Oxygen Isotopic Characteristics and Its Significance of Sanbao Mn-Ag Deposit in Laojunshan Ore District，Southeastern Yunnan Province

A systematic study of carbon-oxygen isotope and electron microprobe for Sanbao Mn-Ag deposit was carried out.It was found that the carbon isotope composition of primary rhodochrosite and coexisted calcite were negative and the oxygen isotopic value were positive，while the carbon isotope value of wall rock was near zero.The results show that the carbon in Sanbao Mn-Ag deposit mainly derives from the mantle source or deep magma system，but its carbon isotope value of this deposit doesn’t completely within δ13C value of deep mantle.It implies that the carbon in the ore-forming fluid may derive mainly from deep system，at the same time，atmospheric precipitation is added to cyclic leaching partial carbon produced from wall rock.The morphology of the ore bodies is stratoid layers，lentoid and lenticular and cystic，rather than typical of layered structure. Additionally，some magmatic accessory minerals such as zircon and rutile are discovered in the Mn-Ag ores.Comprehensive analysis show that the genetic type of Sanbao Mn-Ag deposit belongs to hydrothermal origin and not marine sedimentary deposit.Therefore，this study not only reports characteristics of stable carbon-oxygen isotope but is helpful to deepen the understanding on deposit genesis，broaden exploring information and improve prospecting effect.