Project
Gettysberg and Sellheim Prospects, Pyramid EPM 12887
The Pyramid project is located within EPM 12887 in the Drummond Basin, North Queensland and is located on a major north-northeast trending belt of gold mineralisation developed over a strike length of 20 km. (Fig.1)
Access is from Townsville ia the Flinders Highway to Mingela, then sealed road to the Burdekin Dam Falls and then by graded council road to Pyramid Station. This northern route via the Burdekin Dam is frequently closed during the wet season. Alternative access routes are by sealed road from Charters Towers to the Scartwater Homestead turn off, then by graded council road to Ukalunda Homestead which continues east to Collinsville and Bowen. Station tracks afford reasonable access to most parts of the EPM. The area is essentially open range grazing country, accessible by 4WD vehicle.
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(Fig.1) Pyramid Project Location
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Prospect Description:
Pyramid is composed of low hills and ranges between 200 and 300 m in elevation, with scattered topographic highs being generally formed by igneous plutons. Within the project area the highest elevation is 408 m, corresponding with the small volcanic peak at the Sugarloaf Prospect known as Breccia Knoll. The Bulgonnunna Volcanics form an elevated volcanic range to the northeast, with elevations up to 610 m.
Drainage in the project area flows northerly into the Sellheim River, which flows north-westerly into the Burdekin Dam
Within the project area, the land surface is in an advanced state of dissection, with only a few scattered remnants of a Tertiary sediment and laterite profile (at approximately 300 m elevation), having been largely stripped off to reveal scattered low hills and a small range of Anakie Metamorphics.
The climate of the area is sub-tropical to semi-arid, being warm and dry in winter and hot and wet in summer. During the winter months of June to August, fine sunny days are usually accompanied by cool nights, with mean minimum and maximum daily temperatures ranging from 0 to 25°C. The summer months of November to March are warm to hot with little humidity and a mean daily temperature range from 18 to 35°C in January.
Average annual rainfall for the region is approximately 750 mm which is spread throughout the year, although the summer months of December to March are generally the wettest, with January recording an average of 90 mm. The driest months are April and May, each with an average rainfall of 40 mm.
Vegetation is dominantly open savannah grassland, with scattered eucalyptus and rosewood trees. The area has been largely cleared for cattle grazing purposes.
Regional Geology:
The Pyramid Project lies in the northeast of the Devonian to Carboniferous Drummond Basin and contains a north-northeast trending inlier of Late Ordovician Anakie Metamorphics The inlier of Anakie Metamorphics divides this region from the main area of Drummond Basin sedimentation to the west. A thick wedge of the Late Carboniferous Bulgonunna Volcanics forms the Bulgonunna Block to the east. (Fig. 2) and Geology Legend (Fig.3)
The Drummond Basin is a large intracratonic basin that formed in response to east-west directed extension during the Late Devonian - Early Carboniferous. The basin has a NNW trend and is terminated at its northern boundary by a series of E-W trending faults, which define the southern margin of the Ordovician to Devonian Lolworth - Ravenswood Igneous Complex. To the east, the Drummond Basin is overlain by sediments of the Permian Bowen Basin, while Permo-Triassic sediments overlie the basin to the west.
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(Fig.2) Regional Geological Map EPM 12887 "Pyramid" |
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(Fig.3) Regional Geology Legend
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Gettysberg Host Rocks for Mineralisation:
The host rocks are the ‘Saint Ann’s Formation’ sediments (siltstones, and sandstones). The Saint Ann’s Formation is dominated by a sedimentary package consisting of feldspathic quartz sandstones, micaceous siltstones, thin beds of algal limestone’s and quartz pebble conglomerates. Other surrounding Saint Ann’s Formations that consist of gold hosting mineralisation in the Drummond Basin are located at the Pajingo, Yandan, Wirralie and Twin Hills gold deposits.
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Qtz Breccia.
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Structurally the area is complex and consists of a series of NNE and NNW plunging anticlines, with fault contacts near the conglomerates. An argillic altered rhyodacite dyke is present in the NW and narrow NNW trending andesite porphyry (boninite) dykes are also present
Mineralisation at the Pyramid Project consists of Epithermal quartz veins, graphite-pyrite-sericite stylolitic veinlets and breccia matrix infills. This mineralisation is only hosted in micaceous sandstones of the Saint Anns Formation and appears to be of epithermal style. The gold mineralisation appears to plunge shallowly to the north and there has been limited drilling in this direction. Potential for extensions to the high-grade mineralisation is high.
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Tabular Qtz Breccia Body 1.5m thick.
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Previous Investigations:
The Pyramid Project is located near the Sellheim River area, where numerous small silver-lead-zinc deposits were worked during the late 1880's, including the Sunbeam, Sunset, Carrington and Walhalla deposits From the late 1970's, several mining companies have explored the area around the EPM 12887 (Table 1).
Exploration in the area has been mainly directed towards locating epithermal gold mineralization.
(Table.1) Summary of Previous Exploration
Summary of Previous Drilling conducted over Pyramid
Previous Drilling and Soil Sampling Results (Gettysberg):
Gettysberg prospect was discovered from follow up of a stream sediment anomaly. Highly anomalous rock chip assays up to 2000 g/t Au were located in siliceous breccias.
Soil sampling delineated a 400 x 100 m anomaly of >175 ppb Au (1500 ppb Au peak) at the Devils Den and Culps areas, trending NE. Several zones of >50 ppb Au occur outside the main anomalous zone.
Dalrymple drilled 26 RC holes (MRDC-25 to MRDC-50) and 2 diamond core holes (MDD-1 to MDD-2; MDD-3 was a diamond extension) over a strike extent of 400m, which intersected widespread significant gold mineralisation in 21 holes. The highlights of this drill program are presented in table 2.
(Table.2) Significant Gettysberg Intersections
The holes intersected fine grained micaceous quartzose sandstone and interbedded fissile siltstones. Mineralisation consists of comb/cockade quartz vein stockworks and graphite-pyrite-dolomite breccia zones (Photograph 1). Visible gold was noted in the core holes associated with the graphite-pyrite matrix, as indicated in Photograph 2. Andesite porphyry dykes (boninite) were also associated with the breccia zones.
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Photograph 1. Photograph of drill core from MDD-001. Typical chalcedony-comb quartz vein stockwork mineralised zones in sericite altered thinly bedded sandstone at the Gettysberg prospect. Note the black chlorite-graphite-pyrite stylolite margins to chalcedony-comb quartz vein breccia. (Assay 70-71m: 0.37 ppm Au).
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Photograph 2. Photograph of drill core from MDD-001. Note presence of visible gold within a low amplitude, black graphite-chlorite-pyrite stylolite seam, within sericite altered, hydrofractured sandstone. (Assay 75-76m: 12.0 g/t Au).
Proposal for New Drill Holes:
Twelve holes @ 150m deep are proposed to test the down dip and along strike potential of the gold mineralised zone and the potential for Bulk-Low Grade Mineralisation associated with pyritic graphitic veinlets / dispersions and disseminations in sericite altered schistous zone is as important as the proposal for drill holes to test potential for gold associated with tabular quartz breccia bodies.