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本文总结了巴西两个最重要的滑石产地,Parana和Bahia区中滑石矿床的地质特征,并探讨了这些矿床的可能成因。巴西的滑石在世界滑石储量与产量中占有十分重要的地位。巴西Parana和Bahia区的滑石矿主要产于前寒武纪地体中。尽管该区的滑石具有不同的地质产状,与变质火山岩和变质沉积岩共生的滑石最为重要。其他类型的滑石,如与镁铁质-超镁铁质岩共生的、在花岗岩与白云质大理岩接触带的、在花岗岩体中呈包体或顶垂体状的、则相对不重要。在巴西与岩浆活动有关的滑石矿化主要发生在前寒武纪(Bahia区)和白垩纪(Parana区)。滑石的成因模式主要有两类:一为与岩浆热液有关的热液交代成矿模式,另一是起源于盆地热卤水的变质流体交代成矿模式。其中后一种成因模式可用来解释巴西的大多数大型滑石矿床,同时也适用于其他地区,如中国辽宁和乌拉尔南部的滑石成矿。
This paper summarizes the two most important sources of talc in Brazil, the geological features of the talc deposits in Parana and Bahia, and explores the possible causes of these deposits. Talc in Brazil occupies a very important position in the world’s talc reserves and production. Talc deposits in the Parana and Bahia regions of Brazil are predominantly Precambrian. Despite the different geological occurrences of talc in the area, talc, which is associated with metamorphic and metamorphic sediments, is of the utmost importance. Other types of talc, such as symbiotic with mafic-ultramafite, are relatively unimportant in granite and dolomitic marble contact bands, and in granite bodies in the form of inclusions or top pituitary. Talc mineralization associated with magmatism in Brazil occurs predominantly in the Precambrian (Bahia area) and Cretaceous (Parana area). There are mainly two types of genetic models for talc: one is the hydrothermal metasomatism pattern associated with magmatic hydrothermal fluids, and the other is the metamorphic fluid metasogensis pattern originating from thermal brine in the basin. The latter genetic model can be used to explain most of the large-scale talc deposits in Brazil and also apply to other areas such as talc mineralization in Liaoning and Urals, southern China.