TY - JOUR
T1 - Uranium mobility and deposition over 1.3 Ga in the Westmoreland area (McArthur Basin, Australia)
AU - Gigon, Joséphine
AU - Mercadier, Julien
AU - Annesley, Irvine R.
AU - Richard, Antonin
AU - Wygralak, Andrew S.
AU - Skirrow, Roger G.
AU - Mernagh, Terrence P.
AU - Nancy, Ion Probe Team
N1 - Publisher Copyright:
© 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature.
PY - 2021/10
Y1 - 2021/10
N2 - The Westmoreland area is located in the southern part of the McArthur Basin (Australia) and hosts several uranium (U) deposits and prospects. Previous studies proposed that U mineralisation formed under conditions similar to the unconformity-related U deposits of the Alligator Rivers Uranium Field (ARUF), located north of the McArthur Basin. Detailed mineralogical, geochemical and geochronological studies on mineralised intervals from the Redtree, Junnagunna, and Huarabagoo deposits, and integration with previous studies, identified at least six generations of uranium oxides. These formed between ca. 1680 and 350 Ma, highlighting protracted mobility of U over 1.3 Ga. Each generation of uranium oxide has a specific chemical composition, indicating variable physicochemical conditions for their formation throughout this period. Although the 1680-Ma mineralising event formed at the same time and with similar mineralising fluids as the unconformity-related U deposits from the ARUF, the physicochemical conditions differed between the two areas. Deposits of the Westmoreland area lack the typical Mg– and B–metasomatism of the unconformity-related U deposits in the ARUF: in the Westmoreland area, the chlorite is Mg-poor and no B minerals are observed, whereas the ARUF is marked by Mg-rich chlorite, between clinochlore and Mg–amesite, Mg–foitite, and alumino–phosphate–sulfate minerals. The chondrite-normalised REE patterns of uranium oxides are enriched in light rare earth elements (LREEs) or flat, compared with the typical bell shape of the unconformity-related U deposits. Chlorite thermometry indicates significantly higher temperature conditions (> 300 °C) than in the ARUF for the early U stages. Based on these results, mineralisation in the Westmoreland area is thus significantly different from the unconformity-related U deposits in the ARUF and in other sedimentary basins. Collectively, the data point towards atypical ore-forming processes for basin-related U deposits in the Westmoreland area, but show some similarities with those known in the U deposits of the Otish Basin (Québec, Canada).
AB - The Westmoreland area is located in the southern part of the McArthur Basin (Australia) and hosts several uranium (U) deposits and prospects. Previous studies proposed that U mineralisation formed under conditions similar to the unconformity-related U deposits of the Alligator Rivers Uranium Field (ARUF), located north of the McArthur Basin. Detailed mineralogical, geochemical and geochronological studies on mineralised intervals from the Redtree, Junnagunna, and Huarabagoo deposits, and integration with previous studies, identified at least six generations of uranium oxides. These formed between ca. 1680 and 350 Ma, highlighting protracted mobility of U over 1.3 Ga. Each generation of uranium oxide has a specific chemical composition, indicating variable physicochemical conditions for their formation throughout this period. Although the 1680-Ma mineralising event formed at the same time and with similar mineralising fluids as the unconformity-related U deposits from the ARUF, the physicochemical conditions differed between the two areas. Deposits of the Westmoreland area lack the typical Mg– and B–metasomatism of the unconformity-related U deposits in the ARUF: in the Westmoreland area, the chlorite is Mg-poor and no B minerals are observed, whereas the ARUF is marked by Mg-rich chlorite, between clinochlore and Mg–amesite, Mg–foitite, and alumino–phosphate–sulfate minerals. The chondrite-normalised REE patterns of uranium oxides are enriched in light rare earth elements (LREEs) or flat, compared with the typical bell shape of the unconformity-related U deposits. Chlorite thermometry indicates significantly higher temperature conditions (> 300 °C) than in the ARUF for the early U stages. Based on these results, mineralisation in the Westmoreland area is thus significantly different from the unconformity-related U deposits in the ARUF and in other sedimentary basins. Collectively, the data point towards atypical ore-forming processes for basin-related U deposits in the Westmoreland area, but show some similarities with those known in the U deposits of the Otish Basin (Québec, Canada).
KW - Australia
KW - Chlorite thermometry
KW - Uraninite REE patterns
KW - Uranium
KW - U–Pb isotopic ages
KW - Westmoreland
UR - http://www.scopus.com/inward/record.url?scp=85099199726&partnerID=8YFLogxK
U2 - 10.1007/s00126-020-01031-2
DO - 10.1007/s00126-020-01031-2
M3 - Article
SN - 0026-4598
VL - 56
SP - 1321
EP - 1344
JO - Mineralium Deposita
JF - Mineralium Deposita
IS - 7
ER -