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Panorama District - Sulphur Springs, Kangaroo Caves, Bernts |
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Western Australia, WA, Australia |
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Zn Cu Pb
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Super Porphyry Cu and Au
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IOCG Deposits - 70 papers
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All papers now Open Access.
Available as Full Text for direct download or on request. |
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The Panorama district and the Sulphur Springs, Kangaroo Caves and Bernts massive sulphide deposits of the Pilbara Craton in Western Australia are found within a 3.24 Ga volcanic pile associated with an underlying coeval subvolcanic intrusive, some 110 km south-east of the town of Port Hedland and ~50 km west of Marble Bar.
These deposits occur within a 35 km long belt of mineralised volcanic rocks, which is contained within a NNE-trending tectonostratigraphic domain known as the Lalla Rookh-Western Shaw Corridor, one of five fault bounded domains forming the Pilbara Craton. The sequence in the surrounding district comprises the 3.46 Ga Warrawoona Group of mafic to ultramafic rocks with interbedded cherts and lesser felsic volcanics, unconformably overlain by the 3.33 Ga Sulphur Springs and Kelly Groups, represented in the Panorama area by intermediate to felsic volcanic rocks, cut by the 3.24 Ga Strelly Granite (a sub-volcanic complex) and its coeval volcanics rocks that form the "Strelley succession". Widespread iron formation and clastic meta-sediments of the Gorge Group overlie both the Kelly Group and the "Strelley succession". Granitoid domes have been intruded between the greenstone sequences representing the final stages of cratonisation.
The Sulphur Springs Group comprises five main units. These are the basal Six Mile Creek and Leilira Creek Formations, which contain mixed sedimentary and volcanic rocks; the Kunagunarrina Formation, which is composed of magnesian basalt, komatiite, and chert; the Kangaroo Caves Formation, which contains submarine, mainly tholeiitic basalt-andesite-dacite-rhyolite volcanics and subvolcanic intrusives; all of which are cut by the Strelley Granite. The widespread iron-formation and clastic sedimentary units of the Gorge Creek Group locally overlie the Sulphur Springs Group, which, in turn, is unconformably overlain by siliciclastic sedimentary strata of the De Grey and Fortescue Groups (Venturex, 2012).
The host volcanics form a sequence of about 1.5 km in thickness composed of sub-marine tholeiitic volcanics and volcaniclastics ranging from basaltic to rhyolitic in composition. VHMS deposits are sited within or immediately below a regionally extensive unit of strongly silicified siltstone at the contact between the Kangaroo Caves Formation of the "Strelley succession" and the overlying Gorge Group clastics. The favourable horizon, the "Marker Chert" is typically < 5 m thick, but may reach 80 m near massive sulphides. In addition to the conformable massive sulphides there are also zones of transgressive veining in both the volcanics and the Strelley Granite. Dating indicates that the both the Kangaroo Caves Formation and the Strelley Granite were formed at ~3.24 Ga, with the Strelley Granite emplaced as a concordant, high-level, synvolcanic intrusion into the base of the Kangaroo Caves Formation.
Four alteration facies are recognised: i). Background albite and/or K feldspar-chlorite-calcite and/or ankerite-quartz-pyrite ±leucoxene ±magnetite ±sericite in all units and throughout the pile; ii). feldspar-sericite-quartz mainly in the felsic volcanics; iii). sericite-quartz in the felsic volcanics or granite and iv). chlorite-quartz in all units but largely restricted to immediately below massive sulphide mineralisation, and above the sericite-quartz and feldspar-sericite-quartz zones.
The Sulphur Springs deposit is a strata-bound copper-zinc rich massive sulphide lens extending approximately 500 m east-west along strike and for a similar distance down dip, and can be up to 50 m thick in places. It is underlain by a copper rich stringer zone which is far more variable, though typically it is between 2 and 50 m thick. The deposit dips moderately towards the north at about 50°.
Mineralisation appears to migrate from the felsic volcanic "Marker Chert" contact in the west and central parts of the deposit to the upper part of the "Marker Chert" in the east of the deposit. This is interpreted to be a post mineralisation structural phenomenon rather than a primary emplacement feature. Mineralisation is generally zoned from copper dominant at the base to zinc rich at the top of the deposit. The contact between the chert and top of the massive sulphide ore is generally sharply defined while the lower contact to the underlying stringer zone is more gradational (Venturex, 2012).
The stringer zone mineralisation comprises volcanic rocks strongly altered to chlorite, sericite, carbonate, pyrite and quartz, with network veins containing pyrite, chalcopyrite, sphalerite and sometimes barite, and by definition contains less than 20% sulphide. The boundary between the massive sulphide and the stringer zone may be gradational, beginning where a decrease in sulphide mineralisation permits host volcanic lithologies to be recognised, and where the sulphides become granular with a denser disseminated style rather than massive. In contrast, the lower boundary of the stringer zone is more arbitrary. Sulphide mineralisation (pyrite±chalcopyrite±sphalerite) occurs throughout the felsic volcanic sequence, with the boundary being drawn where there is less than 1.0% chalcopyrite within the rock. Pyrite, which is the dominant sulphide, is ubiquitous throughout the system. The principal zinc mineral is a pale brown coloured, iron-poor sphalerite, which may occur as fine-grained disseminations throughout the deposit, preferentially concentrated with pyrite in massive sulphide lenses towards the top of the VHMS system. Within the lenses, sphalerite occurs as massive, blebby or disseminated grains (Venturex, 2012).
Chalcopyrite is the main copper mineral, occurring as pervasive coarse disseminations, veins and fracture infill, concentrated in the lower part of the VHMS system at Sulphur Springs. Minor bornite and tennantite-tetrahedrite are also apparent, probably containing the bulk of the silver. Chalcocite has been recorded in some of the shallower weathered intersections and malachite is locally prominent in the gossan on the upper contact of the "Marker Chert". Minor amounts of very fine grained galena are associated with the zinc-rich portions of the deposit. A mushroom-shaped footwall alteration zone defines a broad pipe-like mass of alteration localised between the synvolcanic West and Main faults. The inner zone of the footwall alteration zone is characterised by strong, higher temperature, pervasive chlorite-quartz alteration. A zone of sericite-ankerite, decreasing in intensity stratigraphically downwards, surrounds the chlorite zone. Within the hanging wall units, alteration above the mineralisation is indicative of late stage (potentially post mineralisation) hydrothermal activity and consists of an inner quartz-chlorite zone passing into an outer carbonate assemblage (Venturex, 2012).
The larger massive sulphide deposits include:
Sulphur Springs with 5.3 Mt @ 6.1% Zn, 2.2% Cu,
Kangaroo Caves with 1.7 Mt @ 9.8% Zn, 0.6% Cu.
The smaller Bernts deposit of 0.6 Mt @ 7.8% Zn, 1.7%Pb is also within the "Strelley succession" but at a different stratigraphic level.
According to CBH Resources (2008) resource and reserve figure were:
Sulphur Springs resource of 13.8 Mt @ 3.7% Zn, 1.4% Cu, including
reserves of 10.0 Mt @ 3.7% Zn, 1.5% Cu
Kangaroo Caves resource of 1.7 Mt @ 9.6% Zn, 0.6% Cu,
Bernts resource of 0.6 Mt @ 7.6% Zn, 1.7% Pb, 0.6% Cu.
Resources and reserves at Sulphur Springs in 2011 (Venturex, 2012) were:
Measured + indicated + inferred resources - 19.035 Mt @ 1.2% Cu, 3.2% Zn, 0.2% Pb, 17.0 g/t Ag,
Probable reserves - 5.663 Mt @ 1.7% Cu, 3.6% Zn, 0.4% Pb, 25.0 g/t Ag.
For more detail consult the reference(s) listed below.
The most recent source geological information used to prepare this decription was dated: 2007.
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.
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Brauhart C W, Groves D I, Morant P 1998 - Regional alteration systems associated with volcanogenic massive sulfide mineralization at Panorama, Pilbara, Western Australia: in Econ. Geol. v93 pp 292-302
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Brauhart C W, Huston D L and Andrew A S 2000 - Oxygen isotope mapping in the Panorama VMS district, Pilbara Craton, Western Australia: applications to estimating temperatures of alteration and to exploration: in Mineralium Deposita v35 pp 727-740
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Brauhart C W, Huston D L, Groves D I, Mikucki E J, Gardoll S J 2001 - Geochemical mass-transfer patterns as indicators of the architecture of a complete volcanic-hosted massive Sulfide hydrothermal alteration system, Panorama District, Pilbara, Western Australia: in Econ. Geol. v96 pp 1263-1278
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Drieberg S L, Hagemann S G, Huston D L, Landis G, Ryan C G, van Achterbergh E and Vennemann T, 2013 - The Interplay of Evolved Seawater and Magmatic-Hydrothermal Fluids in the 3.24 Ga Panorama Volcanic-Hosted Massive Sulfide Hydrothermal System, North Pilbara Craton, Western Australia : in Econ. Geol. v.108 pp. 79-110
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Morant P 1998 - Panorama zinc-copper deposits: in Berkman D A, Mackenzie D H (Ed.s), 1998 Geology of Australian & Papua New Guinean Mineral Deposits The AusIMM, Melbourne Mono 22 pp 287-292
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Schardt C, Jianwen Yang and Large R 2005 - Numerical Heat and Fluid-Flow Modeling of the Panorama Volcanic-Hosted Massive Sulfide District, Western Australia: in Econ. Geol. v100 pp 547-566
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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.
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