WANG Feng-gang1, FAN Hong-hai1, FAN Cun-kun2
(1. CNNC Key Laboratory of Uranium Resource Exporation and Eveluation Tecnology, Beijing Research Institute of Uranium Geology, Beijing 100029, China;
2. Fuzhou DongXin Mining Technology Co.Ltd, Fuzhou 350000, China)
Abstract: In Tranomaro, Sourthen Madagascar, meionite (Me=87.8%－99.2%) which is extremely rare in the nature is discovered in thorium ore. Meionite mainly originated in marble and calcareous skarns which formed at the contact point of Anosyan granite body (main component is charnockite) and carbonite is symbiotic with diopside, garnet, olive, wollastonite, phlogopite,anorthite,calcite,amphibole, and etc. The chemical analysis indicates that apart from the main components SiO2 (40.95%－43.91%), Al2O3 (29.48%－36.10%), CaO (19.23%－21.86%), Na2O (0.30%－1.60%), meionite also contains CO2- 3,F,Cl,SO3,and etc. Meionite synthesis experiments and mineralogical studies show that meionite formed in geological environment at temperature ≥850 ℃, under the pressure of about 300－500 MPa and also rich in CO2 and Ca. The discovery of meionite in thorium ore shows that the temperature to form thorianite is higher than 850 ℃ at the depth of about 9.9－16.6 km. The fluid associated with thorium minerogenic is supercritical air-liquid fluid. The liquid which is rich in F and CO2 plays a crucial role for thorium minerogenic in this region.
Keywords: meionite; Tranomaro area; Madagascar
Email: wfg9818@163.com
ACTA MINERALOGICA SINICA Vol. 35, No. 3, 2015, Page 406-411
