摘要
受泛非地质事件（约550 Ma）影响,马达加斯加南部Tranomaro地区加里东期紫苏花岗岩侵位于古元古界富含碳酸盐的Tranomaro群变沉积岩中,钍矿化主要产在二者接触部位及附近的透辉石岩中,少量产在大理岩和方柱石岩中。钍矿物主要为方钍石及铀方钍石,多为自型粒状,浸染状分布,多包裹于透辉石、方柱石、橄榄石等矿物内部,部分分布在粒间。钍矿石具有富CaO、MgO、REE、Zr、W、Sn、Bi、Pb及与气-液流体有关的Cl、F、SO_3、CO_2等,贫SiO_2、K_2O、Na_2O等特征,富Mg的矿石中还富含B。钍矿床具有夕卡岩型矿床成矿特征,钍成矿年龄与侵入岩体年龄及赋矿透辉石岩的年龄相近。钍主要来源于含F、CO_2等组分的超临界气-液流体,且矿化形成于温度t≥850℃,压力P≈0.3~0.5GPa的地质环境中。
With the effect of Pan-African event（about 550 Ma）,in the region of Tranomaro,Southern Madagascar Caledonian charnockite intruded into the Paleoproterozoic Tranomaro group of metasediment which is rich in carbonate.Thorium mineralization is predominantly occured in the diopsidite located at the contact zone,minority in the marble and werneritite.The main ore minerals are uranothorianite and thorianite,which occurs as disseminated euhedral crystals.Thorianite and uranothorianite are mostly wrapped in diopside,scapolite and olivine,partly distributed in intergranular regions.Thoruim ores are rich in CaO,MgO,REE,Zr,W,Sn,Bi,Pb and CI,F,SO_3,CO_2 which are related to pneumato-hydatogenetic fluid,and poor in SiO_2,K_2O,Na_2O,et al.,magnesium rich ore is also rich in B.The genesis of thorium deposits is related to skarnization,and the thorium mineralization age is similar to that of intrusion rock and diopsidite.A possible source of Th could be the supercritical fulid which was rich in F,CO_2.The temperature of thorium mineralization was equal or over 850℃ and the pressure was 0.3~0.5GPa.
出处
《世界核地质科学》
CAS
2016年第1期1-7,共7页
World Nuclear Geoscience
关键词
钍矿床特征
钍矿化成因
Tranomaro地区
马达加斯加
characteristics of thorium deposit
genisis of thorium mineralization
Tranomaro region
Madagascar
