Authors / CoAuthors
Needham, R.S. | Stuart-Smith, P.G.
Abstract
Host rocks to the Coronation Hill U-Au mine have long been regarded as agglomerate occupying a volcanic vent, and, as such, the deposit has been regarded as volcanogenic and radically different from the other U-Au stratabound, unconformity-related deposits of the South Alligator Valley district. The agglomerate is reinterpreted as a polymictic debris-flow conglomerate, consisting of rounded to angular clasts of quartz, quartzite, sandstone, carbonaceous shale, rhyolite, and volcaniclastics in a greywacke matrix. Its development was unrelated to volcanism. The deposit lies on the flank of a basinal conglomerate-sandstone-volcanic succession (Coronation Sandstone of the late Early Proterozoic El Sherana Group) that is unconformable on carbonaceous shale (Early Proterozoic Koolpin Formation). The ore surrounds an intensely faulted wedge-shaped area of conglomerate, altered volcanics, and carbonaceous schist. Uranium mineralisation is classified as epigenetic sandstone type, with uranium-enriched felsic volcanics as the source rock, sandstone beds as conduit rocks, and the carbonaceous schist, either as fault wedges or as clasts in the conglomerate, acting as reductant. In other deposits of the region, precipitation took place within in-situ carbonaceous shale faulted against the conduit sandstone. Intense chlorite alteration in the volcanics is unrelated to uranium mineralisation, but may be related to the gold mineralisation, which in places forms ore shoots that are separate from uranium ore and pass into the altered volcanics.
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document
eCat Id
81210
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Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
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Keywords
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- GA PublicationJournal
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- NT
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_External
Publication Date
1987-01-01T00:00:00
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Topic Category
geoscientificInformation
Series Information
BMR Journal of Australian Geology and Geophysics 10:2:121-131
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Unknown
Parent Information
Extents
[-15.78, -10.48, 129.94, 135.3]
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