摘要
个旧锡矿是同燕山中、晚期侵入的斑状黑云母花岗岩及粒状黑云母花岗岩相联系的气成热液矿床,其岩体分布见图1。斑状黑云母花岗岩钾—氩法年龄值84—115百万年,SiO_(2)67.32—73.95%,富钾,偏基性,斜长石An 24—39。特征副矿物为褐帘石、榍石、磷灰石。同成矿关系密切的马拉格—松树脚岩体,年龄为84—103百万年,SiO_(2)>72%,成岩温度>800℃。
Gejiu tin deposits are large polymetallic tin-bearing deposits,with cassiterite-sulfide and cassiterite-quartz mineralizations(including the cassiterite-tourmaline)as the main types.The tin resources in Gejin areas are enormous,and in addition,there are abundant associated elements such as Cu,Pb,Zn,W,and rare earth elements.The country rocks of ore bodies are middle Triassic carbonate types.Genetically,the deposits are closely associated with the middle and late Yanshan porphyritic biotite-granite and equigranular biotite-granite The K-Ar age of granitic intrusion is of 84-115 m.y.and 64-80 m.y.respectively.Petrochemically,the granite is characterized by its high content of SiO_(2)(70-74%)and rich in potassium.There are plenty of accessory minerals such as allanite,sphene,apatite,zircon,monazite,xenotime,etc.in the intrusions.The formation temperature of granite is more than 800℃.The mineralization may be divided into four stages,namely silicate,oxide,sulfide,and carbonate stages,their formation temperature being 425℃,238-358℃,277-386℃and 290-305℃respectively.The major tin mineral is cassiterite,with minor stannite etc.It is considered that the deposits should belong to the pneumato-hydrothermal type owing to the high salinity and great content of CO_(2),OH and H_(2)S in the fluid inclusion,which signify the nature of the ore solutions during the ore-forming process.In view of intergrowing of significant amount of flourite and mica with cassiterite,the transportation of tin may essentially be in the form of K_(2)[Sn(OH,F)_(6)]and Na_(2)[Sn(OH,F)_(6)].During the sulfide stage mineralization,in addition to the two forms mentioned above,tin is also transported as Na_(2)SnS_(3) complex.
作者
汪志芬
Wang Zhifen(No.308 Exploration Team,Southwest Geological Exploration Company,MMI)
出处
《地质学报》
1983年第2期154-163,共10页
Acta Geologica Sinica
