The Kintyre uranium deposit is hosted by the poly-deformed,Palaeoproterozoic terrain of the Paterson Orogenic Belt in north-westernAustralia. Uranium mineralisation occurs in the form of swarms of narrow,high-grade pitchblende veins that are developed where localised north-westoriented damage zones intersect the host stratigraphy. To understand thecontrols on the development of mineralisation at Kintyre, Cameco completeda focused genetic study that included a revision of the regional deformationhistory. A protracted deformation and alteration history is recorded in the hostrocks, which at Kintyre are a sequence of intercalated, metamorphosed Ferichpelites and calc-silicates. The onset of the ~1800 Ma Yapungku Orogeny(D2) resulted in the development of recumbent folding, limb parallel thrustfaulting and upper amphibolite to lower granulite facies metamorphism(M1–2). At Kintyre this phase of deformation generated a series of overturned,south-east verging isoclinal folds with south-east dipping limb parallelthrusts. Following the Yapungku deformation event, the Kintyre host rocks wereoverprinted by a phase of magnetite-carbonate-chlorite replacement stylehydrothermal alteration. This alteration assemblage is best developedalong D2 fold axis’s and shears. The relative timing and composition of thisalteration phase suggests that it could be associated with the intrusion offelsic granitoids in the Kintyre district between 1476 and 1286 Ma.Uplift, erosion and retrograde metamorphism of the Palaeoproterozoicstratigraphy occurred prior to the formation of a series of intra-continentalstrike-slip sedimentary basins during the Mesoproterozoic. The basal unitof the Yeneena Group deposited in these basins is the Coolbro Sandstone, which in the immediate Kintyre area is an immature, fluvial sequence,comprising 0.5 to 7 m thick, upward fining arkosic sandstone beds toppedby 1 to 2 m wide siltstone layers.The onset of the Miles Orogeny (D3) resulted in the formation ofasymmetrical, upright north-west plunging isoclinal folds, NW-SE orienteddip-slip faults and a penetrative, spaced to crenulation cleavage (S_3).Prograde upper greenschist metamorphism (M_3) is associated with thisphase of deformation.An overprinting weak spaced crenulation cleavage accompanied by lower tomid-greenschist facies metamorphism (M_4) was developed during a regionalbrittle, NNE–SSW oriented compressional event deformation event (D_4) thatwas previously unrecognised at Kintyre. Significantly this event reactivatesthe pre-existing structural architecture, generating dilational jogs along theS3 cleavage. Uranium mineralisation is interpreted to be contemporaneouswith this D4 event with basement-derived uranium enriched hydrothermalfluids moving into the dilational void space and uranium precipitating fromsolution due to a combination of pressure/temperature decreases and redoxprocesses. Uranium mineralisation is accompanied by focused, intense Mgchlorite-dolomite alteration and veining.
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