滇西北铜厂沟Mo-Cu矿床成矿流体和成矿物质来源:矽卡岩矿物学与稳定同位素证据

发布时间：2018-03-25 04:28

  本文选题：矽卡岩　切入点：矿物学　出处：《岩石学报》2017年07期

【摘要】：义敦地体位于三江特提斯成矿域中北段,晚三叠世和晚白垩世斑岩-矽卡岩型Mo-Cu多金属成矿作用强烈。铜厂沟Mo-Cu矿床位于义敦地体最南端,是近年来该区新探明的Mo-Cu矿床之一,已探明资源量142.5Mt。矽卡岩在铜厂沟矿区广泛出露,是该矿区最主要的赋矿岩石。根据矿物组合及共生关系,可将矽卡岩划分为石榴子石矽卡岩、透辉石矽卡岩和透闪石矽卡岩三种类型。通过详细的地质填图和钻孔岩心编录,发现铜厂沟矿区矽卡岩矿物组合受花岗闪长斑岩体与大理岩空间分布的控制:(1)由大理岩向外依次发育透辉石矽卡岩→透闪石矽卡岩→石榴子石矽卡岩;(2)由浅至深,石榴子石粒度逐渐变大;③矿化与透闪石、绿帘石等退化蚀变矿物密切相关,矿体多形成于外接触带。矽卡岩中最主要的矿物是石榴子石,多呈自形粒状或粒状集合体产出,颜色较深,均质性,以钙铝榴石为主(62.2%~78.3%),其次为钙铁榴石(16.7%~34.2%),少量锰铝榴石、铁铝榴石和镁铝榴石,属于钙铝榴石-钙铁榴石固溶体系列(Gro62-78And17-34Spe+Pyr+Alm2-6)。石榴子石Fe~(2+)/Fe~(3+)比值变化范围为0.00~0.20,平均值为0.06,指示石榴子石形成于酸性的氧化环境。石榴子石的δ~(18)OSMOW变化范围为5.2‰~9.5‰,反映矽卡岩可能直接继承斑岩体的氧同位素组成;金属硫化物具有较为均一的S-Pb同位素范围(δ~(34)S(CDT)=-0.7‰~1.4‰;~(206)Pb/~(204)Pb=18.332~18.694,~(208)Pb/~(204)Pb=38.454~39.088,~(207)Pb/~(204)Pb=15.588~15.663),表明成矿流体和成矿物质均来源于壳源的长英质岩浆。
[Abstract]:The Yidun terrane is located in the northern section of the Tethys metallogenic domain of Sanjiang, and the late Triassic and late Cretaceous porphyry skarn type Mo-Cu polymetallic mineralization is strong. The Tongchanggou Mo-Cu deposit is located at the southernmost tip of the Yidong terrane, and is one of the newly proved Mo-Cu deposits in the area in recent years. Skarn is widely exposed in Tongchanggou mining area and is the main ore-bearing rock. According to mineral assemblage and symbiotic relationship, skarn can be divided into garnet skarn. Three types of diopside skarn and tremolite skarn. Detailed geological mapping and drilling core cataloguing, It is found that the skarn mineral assemblage in Tongchanggou mining area is controlled by the spatial distribution of granodiorite and marble. The diopside skarn is developed from marble to outside in turn. 鈫扵remolite skarn. 鈫扚rom shallow to deep, the granularity of pomegranate is gradually larger. The mineralization is closely related to the degenerative alteration minerals such as tremolite and verdite, and the orebodies are mostly formed in the external contact zone. The most important mineral in skarn is pomegranate. Most of them are self-shaped granular or granular aggregates, with dark color and homogeneity, mainly calcium and aluminum garnet 62.2 and 78.3%, followed by calcium iron garnet 16.734. 2, a small amount of manganese and aluminum garnet, iron and aluminium garnet and magnesium aluminum garnet. It belongs to the series of calcium allogite and calcium iron garnet solid solution series Gro62-78 And17-34Spe Pyr Pyr Alm2-6. The ratio of pomegranate Fe~(2 / Feanzhu3) varies in the range of 0.000. 20 and the average value is 0. 06, indicating that the pomegranate is formed in an acidic oxidation environment. The 未 18 OSMOW of the pomegranate varies from 5.2 鈥，

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