|
Rum Jungle - Whites, Dysons, Intermediate, Browns, Mount Burton, Mount Fitch |
|
|
Northern Territory, NT, Australia |
| Main commodities:
U Cu Co Pb Zn
|
|
 |
|
|
 |
Super Porphyry Cu and Au
|
IOCG Deposits - 70 papers
|
All papers now Open Access.
Available as Full Text for direct download or on request. |
|
|
The Rum Jungle uranium field is located 90 km south of Darwin in the Northern Territory, Australia and, was the first to be discovered (in 1949) in the Pine Creek uranium province (#Location: 12° 59' 15"S, 131° 0' 31"E).
The Rum Jungle uranium field lies on the western side of the Pine Creek Inlier where Palaeoproterozoic low-grade greenschist facies metasediments are unconformably draped around two Archaean granitic basement complexes - the Rum Jungle Complex to the north and the Waterhouse Complex to the south (Fraser, 1980; Crick, 1987). Uranium and base metal mineralisation is hosted by graphitic or chloritic pyritic phyllite of the Whites Formation at its contact with the underlying dolomite-magnesite of the Coomalie Dolomite. The Palaeoproterozoic sequence is locally unconformably overlain by hematite quartzite breccia (a palaeo-regolith?) and by late Palaeoproterozoic sandstone and conglomerate. The larger deposits (White's, Dyson's and Rum Jungle Creek South) as well as many of the smaller prospects show a spatial association with this unconformity. The two basement complexes together with the Proterozoic rocks are displaced dextrally by 4 to 5 km along the regional Giant's Reef Fault, creating a wedge-shaped embayment of sedimentary rocks, juxtaposed against the Rum Jungle Complex in the south-eastern block.
A broad mineral zoning trend has been noted by Miezitis (1969) and Fraser (1975, 1980). Four of the uranium and base metal deposits are in the Embayment, namely: Dyson's (uranium) in the north-east, followed to the south-west by White's (uranium, copper, lead, cobalt, nickel), Intermediate (copper, uranium; immediately south-west of White's) and Brown's (lead, zinc, copper, cobalt, nickel; 1 km south-west of Intermediate). The Mount Burton (uranium, copper) and Mount Fitch (uranium, copper) deposits are peripheral to the Rum Jungle Complex 5 km west and 7 km north-west of White's. Rum Jungle Creek South (uranium) is 5 km south-west of White's.
Mineragraphic studies (Roberts 1960) on ore samples from White's deposit indicated that uraninite and pyrite mineralisation preceded a period of shearing, which was followed by the introduction of copper, cobalt and lead sulphides. Richards (1963) obtained a 207Pb/206Pb age of 1015 Ma on a uraninite sample from White's deposit, although it seems this was more liklely the age of alteration. Isotopic dating of mineralisation at the Kylie prospect yielded ages of 1627 ± 45 Ma (Ahmad & others, 1993).
Four deposits were mined in the Rum Jungle uranium field - Dyson's, White's, Mount Burton and Rum
Jungle Creek South - two of which also produced copper. The geology of these depsoist can be summarised as follows:
Dyson's - The deposit was 60 m long, 8 m wide and 100 m deep and was mined by both underground and open pit operations. Mineralisation was hosted in strongly sheared graphitic slate of the Whites Formation near its contact with the Coomalie Dolomite. Near surface secondary uranium minerals were saleeite and lesser autunite and sklodowskite. Below 25 m, pitchblende was present as veins and disseminations. Drilling showed that uranium mineralisation persisted as narrow zones to depths in excess of 100 m.
White's - approximately 1 km south-west of Dyson's. Mining was by open cut methods to a depth of 112 m. The orebody was about 150 m long and some of the mineralisation persists to depths beyond 300 m. Uranium and base metal mineralisation was hosted by graphitic, sericitic, chloritic and pyritic phyllites of the Whites Formation close to its contact with the underlying Coomalie Dolomite. The ore minerals were present in four conformable layers, with zoning from the top downwards towards the Coomalie Dolomite contact as follows (Spratt 1965 and Fraser 1980):
i). Cobalt-lead zone: up to 5 m (galena, lesser sphalerite and carrollite);
ii). Cobalt-nickel zone: up to 3 m (linnaeite, carrollite, bravoite, gersdorffite);
iii). Copper-cobalt zone: up to 3 m (bornite, chalcocite, linnaeite, carrollite);
iv). Uranium-copper zone: up to 18 m wide (pitchblende and chalcopyrite; minor galena, aikinite, native bismuth, gersdorffite).
Only the uranium-copper zone out-cropped at the surface, as a narrow gossan containing torbernite, autunite with lesser phosphuranylite, gummite, saleeite and johannite.
The White's East prospect, which lies between White's and Dyson's, appears to represent unconformity-related type mineralisation and is very similar to the deposits in the Alligator Rivers uranium field. Uranium ore zones are hosted within the Palaeoproterozoic Whites Formation near its unconformable contact with the late Palaeoproterozoic sandstone and breccia-conglomerate of the Depot Creek Sandstone. The primary ore assemblage is dominated by pitchblende, which together with chlorite and/or sericite and hematite occupies kinked and brecciated zones associated with reverse faulting. Chlorite is the most widespread alteration mineral associated with the uranium mineralisation at White's East, and magnesian alteration is prominent adjacent to, and along, structures controlling uranium deposition. A multiphase hydrothermal mineralising process was proposed for the origin of the uranium mineralisation, and two generations of uranium mineralisation have been identified (Paterson & others, 1984). South-east of White's mine, copper was the dominant metal at the Intermediate mine, while lead, zinc, copper, cobalt and nickel occur in Brown's deposit at the south-western end of the Embayment.
Rum Jungle Creek South which was the largest of the Rum Jungle uranium deposits, is located to the south of the Embayment, on the southern side of the Giant's Reef Fault. The deposit was 245 m long and 60 m wide within a much broader zone of apparently random uranium mineralisation. The orebody was hosted by the Whites Formation close to the underlying Coomalie Dolomite (Ahmad & others, 1993), with ore-grade mineralisation confined to pyritic and chloritic phyllites, with some uranium in the underlying graphitic phyllite, in a synclinal structure. The sole ore mineral was pitchblende, as a fine sooty coating on cleavage planes and joints. The deposit was mined by open cut from 1961 to 1963 to a maximum
depth of 68 m.
Mount Burton was discovered as near-surface secondary uranium mineralisation at the Whites Formation/Coomalie Dolomite contact. Mineralisation was confined to the crest of an anticlinal fold at the dolomite-slate contact (Berkman 1968). The oxidised zone contained torbernite, malachite and minor chalcocite and native copper. Pitchblende, pyrite and chalcopyrite are found below the weathered zone.
The Mount Fitch prospect is a low grade uranium-copper deposit, where uranium occurs in a shallow syncline at the contact of the Coomalie Dolomite and Whites Formation. The main uranium body is confined to a breccia zone in the
magnesite. Secondary copper in residual clays was estimated to amount to 290 000 t ore with a possible average grade of 0.6% Cu. The uranium mineralisation occurs in sheared and brecciated rocks along steeply dipping fault
zones (Pagel & others, 1984), with brecciated chloritised dolomite and dolomite/chlorite/graphite schist being
the dominant hosts. The mineralised fault zones transect stratigraphic boundaries at high
angles and extend beyond the limits of drilling.
The Kylie prospect is 400 m from the southern margin of the Waterhouse Complex and occurs in a sequence of dolomite/magnesite with lenses of graphite-, chlorite-, tremolite-, tourmaline- and biotite-rich metapelites. This sequence overlies the Crater Formation and belongs to the Coomalie Dolomite. Uranium mineralisation is hosted in steeply dipping metapelite and carbonate next to a downfaulted block of the Palaeoproterozoic Depot Creek Sandstone. Mineralisation is generally confined to zones of brecciation and chloritisation in dolomite/magnesite rock and quartz-chlorite schist. Extensive alteration is shown by complex association of chlorite/magnesite, talc, tourmaline, fluorapatite, rutile, silica and sericite with the mineralisation. Mineralisation also occurs in fault-gouge zones (Pagel & others, 1984).
The South-east Kylie prospect is 2 km south-east of Kylie and the main mineralised zone is in sheared metapelite where mineralisation is associated with brecciated quartz-chlorite schist, sheared pyritic carbonaceous schist and minor chloritic carbonaceous dolomite. Copper and lead are also associated with the uranium mineralisation.
Production and reserves are:
Dyson's - 0.157 Mt @ 0.34% U3O8
White's - 0.403 Mt @ 0.27% U3O8, 2.7% Cu -and- 0.295 Mt @ 2.8% Cu, 0.3% Co
Mount Burton - 0.006 Mt @ 0.21% U3O8, 1.04% Cu
Rum Jungle Creek South - 0.665 Mt @ 0.43% U3O8
Mt Fitch - reserve of 1500 t of U3O8
This description drawn from McKay A D and Miezitis Y, 2001 - Australia's uranium resources, geology and development of deposits; AGSO - Geoscience Australia, Mineral Resource Report 1.
The most recent source geological information used to prepare this decription was dated: 2001.
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd. Unauthorised copying, reproduction, storage or dissemination prohibited.
Dyson's
|
|
|
|
Foster C B, Robbins E I and Bone Y, 1990 - Organic tissues, graphite, and hydrocarbons in host rocks of the Rum Jungle Uranium Field, northern Australia: in Ore Geology Reviews v5 pp 509-523
|
Fraser W J, 1975 - The embayment line of mineralization, Rum Jungle: in Knight C L, (Ed.), 1975 Economic Geology of Australia & Papua New Guinea The AusIMM, Melbourne Mono 5 pp 271-277
|
McCready A J, Stumpfl E F, Lally J H, Ahmad M, Gee R D, 2004 - Polymetallic Mineralization at the Browns Deposit, Rum Jungle Mineral Field, Northern Territory, Australia: in Econ. Geol. v99 pp 257-277
|
|
Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge. It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published. While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo, its employees and servants: i). do not warrant, or make any representation regarding the use, or results of the use of the information contained herein as to its correctness, accuracy, currency, or otherwise; and ii). expressly disclaim all liability or responsibility to any person using the information or conclusions contained herein.
|
Top | Search Again | PGC Home | Terms & Conditions
|
|
