Uranium ores from saline arid-zone groundwaters


Uraniferous calcrete. A) Location and mechanisms involved in formation of channel and playa secondary U deposit formation in the northern Yilgarn Craton (modified from Noble et al., 2011; Mann and Deutscher, 1978). B) General model of saline water–rock interaction, processes and hydrogeochemistry in regions of uraniferous calcrete (after Morgan, 1993)

In the arid desert zone that is the northern Yilgarn region of West Australia, uranium deposits occur in playa and paleochannel calcretes, with an intermediary third type occurring geomorphologically between the two settings, typically designated as platform or delta calcretes, often located where channel drainages enter playas (A). All deposits are at or near the land surface and have a similar capillary-driven genesis and ore mineralogy. They are responses to concentrative changes in shallow groundwater redox interfaces, with circulations driven by evaporation, and U-precipitates typically dominated by carnotite (K2(UO2)2(VO4)2·3H2O). Uranium-rich secondary silica is also important locally in the mineralised zones (B). Carnotite deposits occur along the drainage systems throughout the Yilgarn region and include the world-class Yeelirrie deposit (A). Other potential U-resources on the Yilgarn craton are the Lake Maitland, Centipede and Lake Way prospects.


 Size of major valley channel and playa calcrete-hosted U deposits in the Yilgarn area, including the worldclass Yeelirrie Deposit (after Noble et al., 2011). Delta deposits are transitional between channel and playa types.

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