US EPA

4696097 

Journal Article 

Hydrothermal Rare Earth Element (Xenotime) Mineralization at Maw Zone, Athabasca Basin, Canada, and Its Relationship to Unconformity-Related Uranium Deposits 

Rabiei, M; Chi, G; Normand, C; Davis, WJ; Fayek, M; Blamey, NJF 

2017 

Yes 

Economic Geology and the Bulletin of the Society of Economic Geologists
ISSN: 0361-0128
EISSN: 1554-0774 

112 

6 

1483-1507 

10.5382/econgeo.2017.4518 

WOS:000426874800009 

The Maw zone rare earth element (xenotime) deposit is hosted in brecciated sandstones in the Athabasca Basin and is associated with silicification, hematitization, and tourmalinization magnesiofoitite. Petrographic son-lies indicate that xenotime precipitated after significant compaction of the host rocks and was coeval with the main phase of tourmaline and drusy quartz. Sensitive high-resolution ion microprobe U-Pb dating of xenotime yielded a Pb-207/Pb-206 age of 1547 +/- 14Ma. In situ secondary ion mass spectrometry-oxygen isotope analysis of coeval tourmaline and quartz gives temperatures from 89 degrees to 385 degrees C (average 185 degrees C) and delta O-18,(VSMOW-Fluid) values from -6.2 to +10.8%(0) (average +1.6%(0). l'he coexistence of different types of fluid inclusions (liquid dominated biphase, vapor-dominated biphase, vapor only, and halite-bearing triphase) in individual fluid inclusion assemblages in drusy quartz suggests boiling and heterogeneous trapping. Excluding the heterogeneously entrapped find inclusions, the liquid-dominated biphase inclusions yielded homogenization temperatures from 63 degrees to 178 degrees C, ice-melting temperatures mainly from -37.4 degrees to -21.8 degrees C, and salinities mainly from 22.0 to 28.3 wt %. Raman spectroscopic and mass spectrometric analyses indicate low nonaqueous volatile concentrations (<1 mole %). In conjunction With regional stratigraphy indicating burial depth less than 2.5 km at the time of mineralization, these data suggest an epithermal mineralization environment The similarities in wall-rock alteration, paragenesis, mineralization age, oxygen isotopes, and fluid inclusion attributes between the Maw zone rare earth element deposit and unconformity-related uranium deposits in the region invokes a possible genetic link between them. The hydrothermal fluid at Maw zone probably represents one of the Wilds that carried reducing agents and caused uraninite precipitation in the unconformity-related uranium deposits.