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Tanami Gold Province - Dead Bullock Soak, Callie, Auron, Villa, Triumph Hill, Colliwobble, Dead Bullock Ridge, Federation, Granites, East Bullakitchie, Hurricane-Repulse, Old Pirate, Buccaneer, Kookaburra, Sandpiper, Groundrush, Hyperion, Coyote |
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Northern Territory, NT, Australia |
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Au
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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 Tanami Gold Province deposits are distributed over an area of ~160 x 100 km, located ~500 to 600 km to the NW of Alice Springs in the Tanami Desert of the Northern Territory and north-eastern Western Australia. It includes a number of goldfields and individual deposits, including The Granites, Dead Bullock Soak and Tanami goldfields, the Twin Bonanza District and the Groundrush and Hyperion deposits in the Northern Territory, as well as the Coyote deposit and Bald Hill Area in Western Australia, as described below.
(#Location: Dead Bullock Soak - 20° 31' 40"S, 129° 55' 57"E).
Regional Setting and Structure
The deposits lie within the Granites-Tanami Orogen which contains a metamorphosed and multiply deformed Palaeoproterozoic sedimentary succession that is intruded by the ~1864 Ma Coora dolerite, and overlies poorly exposed Archaean crystalline basement which locally constitutes the 2514 ±3 Ma Billabong Complex. The deepest exposed rocks in the stratigraphy of the deposit area are siltstone, chert and lesser fine-grained sandstone interbedded with dolerite sills of the Dead Bullock Formation, deposited between 1865 ±12 and 1838 ±6 Ma. The dolerites are interpreted to be laterally equivalent to those of the Mount Charles Formation in the central Tanami, and the Stubbins Formation in the western Tanami (Bagas et al., 2013). The Coora Dolerite is inferred on the basis of intrusive realtionships to be younger than 1864 Ma. The Dead Bullock and Stubbins Formations are conformably overlain by a regionally extensive blanket of sandy turbidites of the Killi Killi Formation. Deposition of the Killi Killi turbidites is considered by Bagas et al. (2013) to mark the transition of the Tanami Basin from a back-arc to collisional setting (Pendergast, Baggott and Schmeider, 2017).
The structural evolution of the region has been interpreted to involve between three (western Tanami; Bagas et al., 2013) and at least six (eastern Tanami; Crispe, Vandenberg and Scrimgeour, 2007) deformation events. Supracrustal rocks of the Granites-Tanami Orogen were intruded by three suites of granite over the period from 1825 to 1790 Ma, broadly coincident with protracted regional deformation. Regional metamorphism was typically lower- to middle-greenschist facies, though zones of lower and higher metamorphic grade are known locally (Huston et al., 2007). The Granites-Tanami Orogen is host to a suite of structurally controlled, late tectonic orogenic gold deposits localised in and around the axes of anticlinoria, e.g., Dead Bullock Soak, Coyote and Old Pirate, or by brittle to ductile strain partitioning within and around rheological heterogeneities in the rock package e.g., The Granites, Groundrush and Tanami (Pendergast, Baggott and Schmeider, 2017).
THE GRANITES AND DEAD BULLOCK SOAK GOLDFIELDS
Gold was first discovered in the Granites-Tanami region in 1900, although the first significant deposit was not delineated until 1983 at The Granites, with the first gold pour in 1986. Subsequent exploration has located a series of deposits 40 km to the west mined from the Callie, Auron, Federation, Villa, Dead Bullock Ridge, Triumph Hill and Colliwobble pits and the Dead Bullock Soak underground mine, which are spread over a length of 3 km. Open pit mining commenced on these deposits in 1991, and by 1999 had extracted 62 t of gold.
Dead Bullock Soak Goldfield
The Dead Bullock Soak/Callie deposits are entirely hosted within metasedimentary rocks, with the bulk of the ore occurring within 100 m either side of the contact between the Callie and Ferdies Members of the Dead Bullock Formation. Each of the orebodies are structurally controlled within individual stratigraphic horizons. All of the sedimentary units within in the mine stratigraphy are conformable with transitional contacts.
The lowest member of the Dead Bullock Formation in the deposit area is the Ferdies Member, which comprises an interbedded package of massive to planar- and convolute-laminated siltstone, and lesser massive to cross- and slump-bedded sandstone. This member is differentiated from the overlying Callie Member by its generally higher energy lithofacies. It comprises, from the base (Pendergast, Baggott and Schmeider, 2017), the:
• >50 m thick Terran Beds with slumped bedding;
• ~30 m thick Lower Auron Beds planar laminated sedimentary rocks;
• ~15 m thick Auron Beds characterised by convoluted bedding;
• ~30 m thick Upper Auron Beds with nodular cherts and rip up clasts; overlain by the
• ~40 m thick Lower Blake Beds with amphibole-carbonate pods in planar bedded to laminated rocks which straddles the contact at the top of the Ferdies Member into the Callie Member.
The upper contact of the Ferdies Member is defined as the uppermost sandstone unit within the Dead Bullock Formation (Crispe, Vandenberg and Scrimgeour, 2007). Within the Ferdies Member, the most important host to economic gold mineralisation is the Lower Auron beds which are the principal host to the Auron Orebody. These beds are characterised by planar laminated siltstone containing coarse-grained, ilmenite-bearing laminations that locally have an intimate spatial relationship with gold mineralisation.
The Callie Member overlies the Ferdies Member, and comprises banded and nodular chert-bearing, ferruginous and locally carbonaceous planar bedded and planar laminated siltstone and shale. The Coora dolerite (approximate thickness 200 m) sill intrudes near the middle of the package. The sequence contains an increasing proportion of greywacke towards its upper contact with the overlying Killi Killi Formation. The sequence comprises, from the top of the transitional Lower Blake Beds (Pendergast, Baggott and Schmeider, 2017):
• ~10 m thick Callie Laminated Beds planar laminated sedimentary rocks;
• ~15 m thick Magpie Schist carbonaceous beds;
• ~10 m thick Callie Boudin Chert nodular chert;
• ~200 m thick Upper Blake Beds carbonaceous planar bedded to planar laminated beds;
• ~55 m thick Orac Formation planar bedded ferruginous siltstone with nodular chert interbeds;
• ~200 m thick Coora Dolerite varies from fine to coarse grained and are foliated, and is an equigranular, porphyritic, poikilitic dolerite to quartz diorite, with primary minerals of plagioclase clinopyroxene, hornblende and magnetite;
• ~20 m thick Dead Bullock Soak Member planar bedded with carbonaceous and nodular chert interbeds;
• ~20 m thick Schist Hill Iron Member planar bedded to planar laminated ferruginous siltstone with nodular chert interbeds;
• ~50 m thick Colgate Schist planar bedded with carbonaceous planar interbeds;
• ~30 m thick Manganiferous Chert planar laminated beds;
• ~30 m thick Seldom Seen Schist planar bedded with carbonaceous planar interbeds;
• >50 m thick Madigan Beds planar bedded with nodular chert interbeds.
The key economic units in the Callie Member are planar laminated siltstone of the Callie laminated beds and Magpie schist. The critical feature that distinguishes these units from other horizons of planar laminated siltstone in the Callie Member is - as is the case for the lower Auron beds - the presence of coarse-grained ilmenite-bearing laminations in the rock that are spatially associated with coarse gold. In addition, the banded chert-bearing ferruginous siltstone of the Orac Formation and Schist Hills Iron Member host the Villa and the Dead Bullock Ridge-Triumph Hill-Colliwobble Ridge deposits respectively. They are distinguished from the other subunits of the Callie Member by their locally significantly elevated iron abundances (Pendergast, Baggott and Schmeider, 2017).
The Killi Killi Formation conformably overlies the Callie Member and comprises planar bedded turbiditic sedimentary rocks with lithic clasts. Regionally the formation comprises a thick succession of micaceous greywacke, quartz greywacke, lithic greywacke, quartz sandstone and lithic sandstone, interbedded with siltstone (in part carbonaceous) and mudstone, and occasional thin chert beds. Sedimentary structures include graded bedding and cross-bedding, and incomplete Bouma sequences (Ahmad, Vandenberg and Wygralak, 2013).
As of 31 December, 2016, the mineralised units and their known gold endowment were (Pendergast, Baggott and Schmeider, 2017):
• Lower Auron Beds - 159 t of contained gold;
• Magpie Schist and Callie Laminated Beds - 243 t of contained gold;
• Orac Formation - 6.5 t of contained gold;
• Schist Hill Iron Member - 10.9 t of contained gold.
The structure of the Dead Bullock Soak deposit area is dominated by the moderately east-plunging Dead Bullock Soak Anticlinorium with an average plunge of ~36° and azimuth of ~100°), that formed through local NNE-WSW shortening during D1. Folding within the anticlinorium is disharmonic, a result of the contrasting rheological properties of the constituent stratigraphic units. The anticlinorium is composed of two main anticlines and an intervening syncline. On the northern, and in the central portions of the anticlinorium, the Lantin Anticline and adjoining Challenger Syncline respectively, are plunge-continuous from the Callie open pit to the deepest portion of the underground mine. The Callie Anticline adjoins the southern limb of the Challenger Syncline, extending eastward from the Callie open pit to a point where it terminates and is replaced by the Federation Anticline. The Federation Anticline does not crop out. No axial planar S1 fabric was developed during folding, although a bedding parallel cleavage is locally evident in banded chert of the Callie Member, and more Widespread barren, bedding parallel, veins, may have formed during D1 (Pendergast, Baggott and Schmeider, 2017).
A set of prominent 70° oriented corridors of mineralised, centimetre-scale, sheeted quartz veins and an enclosing S2 foliation traverse the anticlinorium at a low angle to the fold axis and are regarded to be the result of D2. A set of poorly exposed outcrop-scale folds with ENE-WSW striking axial planes with doubly plunging axes are also interpreted to be D2 structures. Other kinematic indicators, such as elongation lineations, bedding offsets across veins, vein dilatancy and asymmetric vein deformation patterns are regarded as consistent with NW-SE shortening and a reverse-dextral sense of motion along the D2 mineralised corridors (Pendergast, Baggott and Schmeider, 2017).
These mineralised structural corridors are interpreted to have been offset during D3, which was the result of ENE-WSW to E-W shortening by a set of moderately to steeply east-dipping reverse ±dextral faults. D3 and earlier structures were subsequently offset by the steeply SSE-dipping dextral D4 Kerril fault, which reactivated a plane of weakness subparallel to the D2 mineralised corridors, either during further E-W shortening, or NW-SE shortening. The last major deformation event recognised in the deposit area involved sinistral displacement on the D5 steeply NNE-dipping Bayban fault during a final phase of ENE-WSW to E-W shortening. A D6 event, involving spatially restricted, low displacement faults and fractures along steeply ESE-dipping brittle structures is tentatively recognised, likely due to NW-SE directed shortening (Pendergast, Baggott and Schmeider, 2017).
Metamorphic assemblages at Dead Bullock Soak vary according to the composition of the hosts rocks. They typically include porphyroblasts of biotite, amphibole (cummingtonite-grunerite and actinolite-hornblende) and garnet, but also contain abundant plagioclase, epidote, quartz and chlorite. Pseudomorphs of what was possibly cordierite are also widespread in certain stratigraphic units, although the relationship between this and the other minerals listed is not well understood. There is no obvious zonation of metamorphic assemblages, and these assemblages are taken to be indicative of peak upper-greenschist to lower amphibolite facies conditions. Metamorphic porphyroblasts are typically aligned within the S2 foliation, or overgrow S2 in random orientations. These textures are interpreted to be consistent with either a pre- to syn-peak metamorphic timing for mineralisation, or multiple thermal events, with one post-dating gold deposition (Pendergast, Baggott and Schmeider, 2017).
Mineralisation and Alteration
Two styles of gold mineralisation are recognised at Dead Bullock Soak. They are mutually exclusive, but appear to both have similar principal controls. Orebodies are localised at the intersection between the mineralised corridors and prospective host stratigraphic units in the Dead Bullock Soak Anticlinorium. Mineralisation is enhanced in and around the hinges of folds, which are interpreted to have acted as structural traps, and in which the prospective stratigraphy is thickened. In addition, south-dipping fold limbs are more prospective as they provide the lowest angle of intersection between the prospective stratigraphy and the mineralised corridors. These low intersection angles coupled with the plunge of the anticlinorium has allowed the formation of orebodies that are up to a few hundred metres in horizontal width, and are plunge extensive subparallel to the anticlinorium over distances locally in excess of 2 km (Pendergast, Baggott and Schmeider, 2017).
The most economically significant of the two styles of mineralisation comprises coarse, nuggety visible gold that is restricted to quartz veins, as at the Callie, Auron and Federation orebodies, where head grades are ~6 g/t Au, and make up >97% of all gold mined. This ore waas amenable to both open pit and underground mining. Coarse gold is nucleated where the auriferous veins intersect ilmenite-bearing laminations in the host rock, generating this style of mineralisation (Pendergast, Baggott and Schmeider, 2017). The interpreted mechanisms of gold depositional would involve redox reactions (Williams, 2007) and/or phase separation of the ore fluid (Williams, 2007; Mernagh and Wygralak, 2007).
The less economically significant style comprises gold associated with disseminated pyrrhotite-pyrite and arsenopyrite in the wall rock, and in lesser chlorite and quartz veins as at the Villa, Dead Bullock Ridge, Triumph Hill and Colliwobble Ridge orebodies. This style of mineralisation resulted in head grades of ~3 g/t Au, and was amenable to mining at surface rather than underground. Orebodies of this style are only hosted by the most ironrich rocks in the mine stratigraphy. The gold depositional mechanism has been interpreted to most likely have been the result of destabilisation of auriferous bi-sulphide complexes in the ore fluid via interaction with the iron-rich wall rocks (Pendergast, Baggott and Schmeider, 2017).
The hydrothermal alteration related with gold mineralisation is not well understood (as at 2017). There is an absence of lateral alteration fronts around mineralised veins that can be recognised by the naked eye, although locally millimetre-scale biotitic selvedges are evoident around some ore-stage veins in the Callie, Auron and Federation orebodies. Hyperspectral scanning of drill core has exposed variations in chlorite chemistry that may be an important vector to mineralisation (Pendergast, Baggott and Schmeider, 2017).
The similarity of principal controls on the two styles of mineralisation and the absence of evidence for multiple mineralising events has been interpreted to suggest the two styles are coeval. U-Pb dating of gold-associated hydrothermal xenotime from the Callie orebody has yielded an age of 1803 ±19 Ma for the mineralisation (Cross et al., 2005).
The Granites Goldfield
The Granites goldfield is located ~35 km east of Dead Bullock Soak, with similar mineralisation to that at Callie. It is also hosted by the Callie Member of the Dead Bullock Formation. However, in contrast to Callie, the host contains banded ironstone and the sedimentary rocks have been metamorphosed to amphibolite facies. Gold occurs in a shear zone within tightly folded and steeply dipping strata on the margins of an 1825 to 1790 Ma Grimwade Suite granite (Huston et al., 2007). Five deposits, East Bullakitchie, West Bullakitchie, Quorn, Shoe and Bunkers Hill, have been defined in the goldfield, of which East Bullakitchie is the largest and highest-grade. Individual lodes are 2 to 8 m thick and 50 to 600 m long, persisting to depths of at least 250 m depth.
The East Bullakitchie deposit comprises four lodes grading from 7.5 to 8.5 g/t Au, contained in quartz and calcite veins hosted by amphibolite grade iron-rich metasedimentary rocks. Gold is closely associated with shears reactivated during folding. The lodes dip at 70 to 90° and strike E to NE. The mineralised zone containing these auriferous veins is up to as much as 30 to 40 m thick. Narrow (~10 mm) selvages envelope most mineralised veins. The quartz veins have an associated hornblende ±cummingtonite ±epidote assemblage, whilst calcite veins have an accompanying diopside-clinozoisite alteration assemblage (Wygralak, Huston and Mernagh, 2017).
Production, Reserves and Resources
Dead Bullock Soak Goldfield
At the end of 1996, the identified mineral resource in the iron formation deposits at The Granites, which was then part of the same operation, totalled 6.4 Mt @ 3.5 g/t Au, while the Dead Bullock Soak (Callie) style mineralisation had a resource of 16.2 Mt @ 5.6 g/t Au for 90 t of contained Au.
Production from the operation during 2007 totalled 13.65 t of recovered Au (Newmont, 2008).
The remaining reserve at Dead Bullock Soak at the end of 2007 was 5.8 t of contained Au in a proved + probable reserve of 11.63 Mt @ 4.47 g/t Au.
As of 31 Dec. 2016, production, Ore Reserves and Mineral Resources at Dead Bullock Soak/Callie (Pendergast, Baggott and Schmeider, 2017) were:
Total past production to 2016 - Open pit - 56 t of gold; Underground - 190 t of gold;
Ore Reserves - 140 t of contained gold comprising,
Proved Reserves - 5.7 Mt @ 5.26 g/t Au;
Probable Reserves - 17.5 Mt @ 6.23 g/t Au;
TOTAL Reserves - 23.2 Mt @ 6.00 g/t Au;
Mineral Resources - 34 t of contained gold (additional to Ore Reserves) comprising,
Indicated Resources - 2.6 Mt @ 5.53 g/t Au;
Inferred Resources - 3.2 Mt @ 5.85 g/t Au;
TOTAL Resources - 5.8 Mt @ 5.71 g/t Au;
TOTAL known endowment as of 31 December, 2016 - 420 t of contained gold.
Remaining Ore Reserves and Mineral Resources at the Tanami Operation as at 31 Dec. 2020 (Newmont Reserve and Resource Report, 2021) were:
Proved + Probable Reserves - 36.2 Mt @ 5.05 g/t Au (additional to Mineral Resources);
Open Pit Measured + Indicated Resources - 17.8 Mt @ 1.77 g/t Au;
Open Pit Inferred Resources - 7.6 Mt @ 2.07 g/t Au;
Underground Measured + Indicated Resources - 3.3 Mt @ 4.46 g/t Au;
Underground Inferred Resources - 12.0 Mt @ 5.71 g/t Au;
TOTAL Ore Reserve + Mineral Resource - 76.9 Mt @ 4.07 g/t Au for 313 t of contained gold.
The Granites Goldfield
Total past production was 29.3 t of gold @ grades of 1.5 to 9.3 g/t Au (Ahmad, Vandenberg and Wygralak, 2013; Huston et al., 2007);
Remaining resource is 7 t of gold (Wygralak et al., 2005).
Tanami Goldfield
The Tanami Goldfield is located ~45 km north of Dead Bullock Soak and comprises ~60 small deposits, ~40 of which have been mined along a 15 km long, NNE-trending corridor. Mineralisation is hosted by the Mount Charles Formation which is considered to be a equivalent to the lithologically similar Dead Bullock Formation. Both are intruded by dolerite, and are interpreted to conformably underlie the Killi Killi Formation and unconformably overlie Archaean basement (Bagas et al., 2014). However, Crispe, Vandenberg and Scrimgeour (2008) interpret the Mount Charles Formation to be considerable younger, unconformably above the Killi Killi Formation. Geoscience Australia suggests it was deposited between 1913 and 1790 Ma. It comprises fine-grained turbiditic sedimentary rocks with basal quartzic sandstone and lesser interbedded basalt beds of up to 20 m in thickness. Deposition is assigned to the period 1.80 to 1.79 Ga (Ahmad, Vandenberg and Wygralak, 2013). The immediate host lithologies include volcaniclastic rocks, mudstone, chert and greywacke. Gold occurs in clusters of quartz-carbonate veins with associated white mica-pyrite. These veins strike in three discrete direction ranges, 350 to 010°, 20 to 40° and 60 to 80° (Wygralak et al., 2005). The mineralised vein cluster lodes are 1 to 20 m thick, 20 to 300 m in length and persist over vertical intervals of 10 to 70 m. The principal gangue minerals include calcite, siderite and quartz, and pyrite is the main sulphide (Wygralak, Huston and Mernagh, 2017).
The largest mined deposit within the goldfield was Hurricane-Repulse which constituted three orebodies: Repulse, Gap and Hurricane that produced 13.1 t of gold (Ahmad, Vandenberg and Wygralak, 2013). The southernmost of these, the Hurricane orebody is hosted by siltstone and comprises three lodes controlled by a shallow SE-dipping fault system. The central Gap lode has a cigar-shaped shoot following the intersection of steeply east-dipping quartz veins and a south-west-dipping basalt host. The north-plunging Repulse shoot is controlled by two subparallel steeply NNE-dipping faults, localised almost entirely within a basal host, and is terminated to the south by a steep ENE-trending fault (Wygralak, Huston and Mernagh, 2017).
The deposits of the Tanami Goldfield produced 27.4 t of gold from ore grading 2.4 g/t Au. The remaining mineral resources amount to 50.7 t of gold in ore grading 3.2 g/t Au (Huston et al., 2007)
Twin Bonanza District
The Twin Bonanza District includes two main deposits and styles of mineralisation. The first of these, the Old Pirate deposit, is characterised by coarse-free gold in quartz veins hosted by the Killi Killi Formation. Mineralisation is preferably developed in shale rather than sandstone. The host rocks are folded into a south-plunging anticline. The quartz veins vary 0.2 to several metres in width, but only over short strike lengths. The overall mineralisation comprises multiple zones extending over a strike length of 1.8 km (Wygralak, Huston and Mernagh, 2017). The global resource at Old Pirate in 2014 totalled 1.88 Mt @ 10.1 g/t Au for 19 t of contained gold (Eiloart et al., 2014).
The second deposit Buccaneer is the only gold system in the Tanarni gold province interpreted to be related to felsic intrusives. Mineralisation occurs within a 3 x 1.6 km syeno-monzonite porphyry, which is almost entirely anomalous in gold as well as in As, Sb, Bi, Mo, W and Cu (Bagas et al., 2014). The porphyry was subjected to early potassic hydrothermal alteration expressed as biotite-quartz-K feldspar veinlets which were overprinted by shearing and faulting that was, in turn, accompanied by phyllic (silica-white mica-pyrite) alteration near the margins. Gold occurs in stockwork quartz veins related to both alteration events (Wygralak, Huston and Mernagh, 2017).
The resource in 2016 was 15.3 Mt @ 2.54 g/t Au for 28.9 t of contained gold (Wygralak, Huston and Mernagh, 2017).
Other deposits
Other deposits in the province include:
Groundrush and Hyperion which are located ~35 km and 53 km respectively NE of the Hurricane-Repulse deposits of the Tanami Goldfield. The host to mineralisation is a foliated dolerite dyke that intrudes the Killi Killi Formation (Huston et al., 2007). Mineralisation is found as anastomosing zones of quartz veining that trend NNE and dip at 70 to 80°W. The lode zones are 10 to 30 m wide and associated with chIoritic alteration of the wall rocks. Gold occurs as the native metal, or is associated with arsenopyrite, pyrite and pyrrhotite (Wygralak, Huston and Mernagh, 2017).
Production from Groundrush totalled 5.5 t of Au from 1.4 Mt ore at an average grade of 4.5 g/t Au. Remaining Indicate Mineral Resources are 6.9 Mt @ 4.5 g/t Au for 31.1 t of contained gold (Wygralak, Huston and Mernagh, 2017).
Hyperion is located 18 km NNE of Groundrush and also comprises mineralisation hosted by quartz-carbonate veins controlled by a WNW-trending shear in dolerite. The deposit had an Inferred Resource of 6.28 Mt @ 2.11 g/t Au (Bagas et al., 2014).
Coyote is 40 km NW of the Twin Bonanza District in Western Australia and was mined until 2010 after producing 1.28 t of Au (Register of Australian Mining 2014-15). Operations ceased due to high costs, although remaining Mineral Resources were ~3 Mt @ 5.6 g/t Au for 16.8 t of contained gold (Tanami Gold NL, 2013). Mineralisation is hosted by the Killi Killi Formation, which locally comprises a greywacke-dominated sequence within the Coyote Anticline. Gold occurs in bedding-parallel veins dipping at 10 to 15°W and was still open at a depth of 450 m (Bagas et al., 2014). Mineralisation is predominantly free gold associated with quartz veins, with lesser arsenopyrite, calcite, K feldspar, biotite, pyrite, galena, sphalerite, chalcopyrite and bismuth minerals (Wygralak, Huston and Mernagh, 2017).
The Bald Hill area is also in Western Australia, ~25 km north of Coyote, and comprises two separate deposits, Kookaburra and Sandpiper. Both are hosted by the Bald Hill sequence of the Stubbins Formation. The Stubbins Formation is interpreted to be the lowermost unit of the Tanami Group in Western Australia and has been mapped in the Bald Hill area (Bagas et al, 2009). It comprises a 2 to 3 km thick lower succession of turbiditic sandstone, siltstone, shale and dolerite sills, which is conformably overlain by an upper 200 m thick succession known as the Bald Hill Member. The latter is composed of iron-rich siltstone and shale, carbonaceous shale, chert, pillow basalt, dolerite and minor rhyolite which has been dated at 1864 ±3 Ma (zircon U/Pb SHRIMP; Bagas et al., 2009). This is the oldest known unit in the Tanami Group, but it has not been mapped in the Northern Territory. The Stubbins Formation underlies the Killi Killi Formation and may represent a unit equivalent to or immediately underlying the main Dead Bullock Formation and Mount Charles Formation (Ahmad, Vandenberg and Wygralak, 2013). Gold bearing veins are found in east-trending shears and consist of quartz, carbonate ±pyrite ±arsenopyrite. This mineralisation is associated with strongly deformed white mica-quartz ±biotite ±sulphide schist interpreted as an alteration assemblage. Sulphides in the schist include arsenopyrite, pyrite, galena, cllalcopyrite, sphalerite and altaite (Huston et al., 2007).
The deposits originally contained 1.4 Mt @ 2.0 g/t Au at Kookaburra and 1.2 Mt @ 2.9 g/t Au at Sandpiper (Wygralak, Huston and Mernagh, 2017).
The most recent source geological information used to prepare this decription was dated: 2017.
Record last updated: 28/4/2021
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.
Dead Bullock Soak
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Adams G J, Both R A and James P, 2007 - The Granites gold deposits, Northern Territory, Australia: evidence for an early syn-tectonic ore genesis : in Mineralium Deposita v42 pp 89-105
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Anonymous 1998 - Granites, The Dead Bullock Soak (NFM): in Register of Australian Mining 1997/98 pp 202-203
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Anonymous 1998 - North Flinders Mines Limited: in Extracts form the North Flinders Mines Ltd 1996 Annual Report pp 1, 3-11
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Anonymous 1998 - Normandy Mining Limited: in Extracts from the Normandy Mining Limited 1997 Annual Report pp 12-14, 17, 26-28.
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Bagas L, Huston D L, Anderson J and Mernagh T P, 2007 - Paleoproterozoic gold deposits in the Bald Hill and Coyote areas, Western Tanami, Western Australia : in Mineralium Deposita v42 pp 127-144
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Crispe A J, Vandenberg L C and Scrimgeour I R, 2007 - Geological framework of the Archean and Paleoproterozoic Tanami Region, Northern Territory : in Mineralium Deposita v42 pp 3-26
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Cross, A.J. and Crispe, A.J., 2007 - SHRIMP U-Pb analyses of detrital zircon: a window to understanding the Paleoproterozoic development of the Tanami Region, northern Australia : in Mineralium Deposita v.42, pp. 27-50.
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Huston, D.L., Vandenberg, L., Wygralak, A.S., Mernagh, T.P., Bagas, L., Crispe, A., Lambeck, A., Cross, A., Fraser, G., Williams, N., Worden, K., Meixner, T., Goleby, B, Jones, L., Lyons, P. and Maidment, D., 2007 - Lode-gold mineralization in the Tanami region, northern Australia : in Mineralium Deposita v.42, pp. 175-204.
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Lambeck A, Huston D and Barovich K, 2010 - Typecasting prospective Au-bearing sedimentary lithologies using sedimentary geochemistry and Nd isotopes in poorly exposed Proterozoic basins of the Tanami region, Northern Australia: in Mineralium Deposita v.45 pp. 497-515
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Lovett D R, Smith M E H, Pring P I, Sando B G 1997 - The Dead Bullock Soak Gold Deposits: in Berkman D A, Mackenzie D H (Eds), Geology of Australian and Papua New Guinean Mineral Deposits The AusIMM, Melbourne pp 449-460
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Mayer T E 1990 - The Granites Gold field: in Hughes F E (Ed.), 1990 Geology of the Mineral Deposits of Australia & Papua New Guinea The AusIMM, Melbourne Mono 14, v1 pp 719-724
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Mernagh T P and Wygralak A S, 2007 - Gold ore-forming fluids of the Tanami region, Northern Australia : in Mineralium Deposita v42 pp 145-173
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Nicholson P M 1990 - Tanami Gold deposit: in Hughes F E (Ed.), 1990 Geology of the Mineral Deposits of Australia & Papua New Guinea The AusIMM, Melbourne Mono 14, v1 pp 715-718
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Pendergast, W.J., Baggott, M.S. and Schmeider, S., 2017 - Dead Bullock Soak including Callie: in Phillips, G.N., (Ed.), 2017 Australian Ore Deposits, The Australasian Institute of Mining and Metallurgy, Mono 32, pp. 551-556.
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Petrella, L., Thebaud, N., Fougerouse, D., Evans, K., Quadir, Z. and Laflamme, C., 2020 - Colloidal gold transport: a key to high-grade gold mineralization?: in Mineralium Deposita v.55, pp. 1247-1254.
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Scrimgeour I, Sandiford M 1993 - Early Proterozoic metamorphism at the Granites Gold mine, Northern Territory: implications for the timing of fluid production in high-temperature, low-pressure terranes: in Econ. Geol. v88 pp 1099-1113
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Tunks A J and Cooke D R, 2007 - Geological and structural controls on gold mineralization in the Tanami District, Northern Territory : in Mineralium Deposita v42 pp 107-126
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Tunks A, Marsh S 1998 - Gold deposits of the Tanami Corridor: in Berkman D A, Mackenzie D H (Ed.s), 1998 Geology of Australian & Papua New Guinean Mineral Deposits The AusIMM, Melbourne Mono 22 pp 443-448
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Williams N C, 2007 - The role of decarbonization and structure in the Callie gold deposit, Tanami Region of northern Australia : in Mineralium Deposita v42 pp 65-87
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Wygralak, A.S., Huston, D.L. and Mernagh, T.P., 2017 - Gold deposits of the Tanami gold province: in Phillips, G.N., (Ed.), 2017 Australian Ore Deposits, The Australasian Institute of Mining and Metallurgy, Mono 32, pp. 547-550
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