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ActivEX’s Pentland Gold Project (total 264 km2) is located in north east Queensland, approximately 100km west of Charters Towers. ActivEX Limited holds 100% interest in three tenements, namely EPMs 14332, 15055, and 15185.
North east Queensland is highly prospective for both intrusive related gold, and epithermal gold ± silver deposits, with a number of known high tonnage deposits located throughout the region (Table 1).
Table 1. Major deposits of north east Queensland
The Pentland Gold Project is a large land holding with all tenements in good standing. The project contains five established prospects where ActivEX has carried out extensive ground based surveys and these areas are drill-ready with a number of targets already identified. Outside of these areas, the project package is only lightly explored and significant potential remains.
Mt Remarkable Prospect:
Norwood Prospect area:
Numerous other less well understood prospects occur in the area requiring further ground surveys to develop prospects to drill target status. They include:
EPMs 14332, 15055 and 15185 are located in the Charters Towers district of northern Queensland, with the eastern edge of the EPMs approximately 100 km west of Charters Towers. The township of Pentland is located within the tenement area, in the southeast of EPM 14332.
The tenements lie in the eastern portion of the Hughenden 1:250,000 sheet area and are centred on longitude 145°56’ E and latitude 20°19’ S (Figure 1).
Pentland is situated on the Flinders Highway and access into most of the eastern and central tenement areas is via the unsealed Cape Road and well defined station tracks. Access into the western area of the tenement is via sparse station tracks and poorly defined access tracks constructed by previous explorers.
Project tenure comprises three, 100% ActivEX Limited held tenements in North Queensland with a combined area of 264 km2.
Table 2. Summary of individual tenement details
A single Native Title Claim Application present in the project area. An Application by Yirendali Core Country overlaps the south-west portion (approximately 10%) of EPM 15055. This is a recently lodged claim and as yet no negotiations have been entered into.
Figure 2. Pentland Gold Project tenements
The Pentland tenements encompass much of the Cape River Gold and Mineral Field. Alluvial, deep lead and primary gold were discovered along the Cape River in 1867. Recorded production from the field was around 45,000 ounces (approximately 1400kg), but true production was considerably more as there is no record of the amount extracted by the Chinese miners, who were almost as numerous as Europeans during the productive years of the field in the late 1800’s. Several areas within the Exploration Permits have seen small scale mining since that time.
The Pentland tenements cover an area in which a wide variety of mineralisation styles have been identified and worked in part, including quartz vein gold, alluvial, elluvial and deep lead gold, shear-zone hosted gold, epithermal and porphyry-related gold, porphyry-related copper-molybdenum, and shear-breccia zone hosted Pb-Cu-Au.
Review of the results of this extensive work showed that significant gold, copper and molybdenum mineralisation had been identified and while considerable IP and ground magnetics had been carried out, little follow up of the surveys have occurred.
Table 3. Summary of historic exploration
The three Pentland Gold Project EPMs comprise an elongate area which trends northwest and takes in approximately 65 kilometres of strike length of the northwest trending (S2 foliation) Neo-Proterozoic Cape River Metamorphics (Figure 3) consisting of predominantly mica schists and meta-arenites with minor calc-silicates.
The Cape River Beds are bounded on the northeast by granitoids of the Ordovician-Silurian Macrossan Province and the Silurian-Early Devonian Pama Province.
In the area of the Pentland tenements, the northwest trending belt of Macrossan Province granitoids largely comprise variably foliated to gneissic tonalite to granodiorite of the Fat Hen Creek Complex. In the east of EPM 14332, quartzite and calc-silicate gneiss of the Cape River Metamorphics occur as rafts and xenoliths in the gneissic granite. Non-deformed granites occur in a belt along the south-western part of the complex, from north of Mount Remarkable to the southern end of Gorge Creek. These granites have numerous meta-sedimentary enclaves, and are interpreted as S-type granites derived by partial melting of the Cape River Metamorphics. The smaller Ballabay Complex, which is mapped as a roughly equant area that straddles the boundary between EPMs 14332 and 15185, has also been assigned to the Macrossan Province, and consists of hornblende gabbro, granodiorite, and altered granite.
The younger Pama Province granitoids (late Silurian-early Devonian) consist of a series of adamellites, granodiorites, quartz diorites and granites. This intrusive complex (formerly known as the Lolworth Complex) borders the tenement area to the northwest. This igneous event is considered to be the source of mesothermal vein systems at the historic Charters Towers field.
Scattered intrusive and extrusive igneous rocks of the Permo-Carboniferous Kennedy Province Intrusives and Volcanics are located in the southeast and northwest of the tenement area. The Kennedy Province units largely consist of the Deep Water Creek Granophyre and Gypsy Pocket Granodiorite in the northwest, and the Elimeek Volcanics in the southeast. Several small occurrences of brecciated quartzite and meta-arenite are also attributed to the Kennedy Province Intrusives, including the Mo-anomalous breccia identified by Central Coast Exploration at Eight Mile Creek (located within EPM 15185). The Kennedy Permo-Carboniferous igneous event is considered to be related to a number of north Queensland deposits, including the Mt Leyshon and Kidston gold breccias, and the Red Dome porphyry and skarn copper-gold deposit.
To the southwest of Pentland, the Cape River Metamorphics and Permo-Carboniferous units are covered by unconformably overlying Permian to Triassic shallow marine sediments (including coal formations) of the Galilee Basin. The basal unit, the Betts Creek Beds, comprises sandstone, siltstone and shale and is in turn overlain by the Warang Sandstone.
The Tertiary Campaspe Formation covers about 8000 km2 between Charters Towers and Pentland, and residuals of the Formation occur scattered through the tenement area, particularly in the southeast. The Campaspe Formation is a continental fluviatile assemblage comprising mainly immature sandstones with minor siltstone, and includes the gold bearing gravels that were extensively worked in the Pentland area.
Figure 3. Pentland Gold Project geology
The Pentland tenement hosts the best understood and most promising prospects across the Pentland Gold Project tenement package. Gold, copper and molybdenum mineralisation is hosted in breccia zones containing diorite fragments in a vuggy quartz-sulphide matrix and steeply dipping, vuggy quartz-galena-sphalerite veins. There are many mineral occurrences in the tenement with four prospects currently under investigation at various stages in the exploration process.
The Mt Remarkable Cu-Mo-Au prospect area is located approximately 10km west-northwest of the township of Pentland and coincides with a northwest trending topographic high.
The Mt Remarkable prospect occurs within a complex altered diorite intrusive located on the northwest trending contact between metasediments of the Cape River Province and intrusives of the Fat Hen Creek Complex. The diorite is a northwest trending elongate body around 5.5km long considered either Ordovician or Permian aged. The main prospect area is located near the northwest end of this diorite body, and at the northern end of a northeast trending zone of gold-bearing quartz veins and associated felsic porphyry dykes (Permian) referred to as the “Vein Corridor”. Limited drilling in the Vein Corridor has intersected narrow high grade vein systems with assays up to 1m @ 9.8g/t Au and wide zones of anomalous copper, gold and molybdenum mineralisation including 47m @ 0.92g/t Au from 259m to the bottom of the hole (Table 4).
Drilling by previous explorers and by ActivEX revealed alteration and mineralisation is largely hosted in quartz diorite intruded by variably altered felsic dykes. The source of mineralised hydrothermal fluids is not immediately clear, although a younger quartz-feldspar porphyry and microgranite (seen as granite and aplite dykes hosting potassic alteration and molybdenum rosettes) are considered possible sources.
Within the diorite, propylitic alteration (silica-chlorite-sericite-epidote) is overprinted by locally intense zones of quartz-sericite-pyrite. The Cu-Mo mineralisation occurs as disseminations and associated with quartz-pyrite-chalcopyrite-molybdenite breccias, veins and veinlets described as stockwork. Some veins are described with potassic (secondary biotite) alteration selvages and with selvages of quartz-sericite-pyrite. The sulphide-bearing veins are commonly overprinted by a clay-dominated assemblage that appears to partially leach the sulphides and may be due to a late overprint by relatively low temperature and low pH fluids. Magnetite depletion evident in a magnetic low zone highlights the argillic/pyrite alteration zone controlled by north-east trending structures which have had only limited drill testing.
The propylitic and potassic stage of the porphyry system are the primary exploration targets at Mt Remarkable. Re-evaluation of the previous drilling in the area has shown that propylitic and potassic alteration styles have been intersected south of Mt Remarkable in holes DDH 4 and 6 and PN05 and 09. This target is particularly highlighted by an area of the strongest geochemistry, intense demagnetisation and high resistivity at the intersection of the north-east trending vein corridor and the north-west trending argillic zone.
In addition, IP surveys carried out by previous explorers have highlighted other anomalies around Mt Remarkable, some of which have been partially drill tested. However, remodelling of data and recent geophysical surveys completed by ActivEX have shown significant extensions of anomalies which require further drill testing.
Table 4. Drill highlights at the Mt Remarkable prospect
The Norwood prospect is located approximately 12km west of the township of Pentland and incorporates the area known as Norwood including Red White and Blue and Golden Mount prospects. The prospect area lies approximately 5km south of the Mt Remarkable prospect and at the southern end of the Vein Corridor extending from Mt Remarkable.
The area is hosted within an outlier of volcanics of the Permian Kennedy Province which onlap unconformably onto the older Neo-Proterozoic – Cambrian basement of the Cape River Province (Morepork Member). Younger overlying sediments of the Galilee basin and Tertiary Campaspe Beds obscure the southern half of the area and mask the basement magnetic signatures.
Mineralisation in the Red White and Blue – Norwood area has been noted in pebble dykes, as disseminated sulphides and fissure filled quartz sulphide veins. Haematite and limonite boxworks after pyrite are widespread throughout the volcanic breccia although the greatest concentrations lie within 200m of historic workings. The workings target elluvial and in-situ boxworked and veined volcanics including steeply dipping narrow structures hosted by brecciated volcanics. The volcanics consist of matrix and clast supported breccias and medium to coarse grained fragmentals which vary from boulder conglomerates to dacitic volcanic breccias. Past explorers have interpreted the volcanics as a diatreme/breccia complex based on steep outer contacts as well as intrusions of dacite, micro-tonalite and auto-brecciated flow banded rhyolite (interpreted as a resurgent lava dome). The volcanics have alternatively been interpreted as a sequence of layered fragmentals.
The prospect area hosts a complex zone of intersecting structures coinciding with the most intense part of an east-north-east trending magnetic anomaly which in part is attributed to magnetite bearing diorite and monzo-diorite intrusives. Drilling has revealed the porphyry intrusion resides within a diatreme breccia body suggesting it as the cause of brecciation. Lying immediately west of the main magnetic feature is the 600m long Red White and Blue gold anomalous zone hosted in a mineralised phase of the diatreme breccia with significant intersections of 8 metres @ 2.28g/t Au and 4 metres @ 2.53g/t Au (Table 5).
Copper and molybdenum have a different distribution. They are coincidently anomalous in the area of most intense high magnetic character and probably reflects the influence of the diorite intrusive phases. Importantly, copper and molybdenum appear only weakly related to the gold distribution indicating several distinct mineralising events. Both copper and molybdenum anomalous areas are confined by the north-east trending structures in the area.
Modelling of the recent and past IP data has defined three styles of chargeability anomalies:
The south dipping anomalies appear to represent clay alteration zones with associated pyrite within the diatreme and may indicate a blanket of argillic alteration. These targets were drill tested and no mineralisation was found to be associated. The other chargeability anomalies are yet to be tested.
The primary target is the strong deep chargeability effect on Line 9400E which is interpreted as a strong development of sulphides within the diatreme. This suggests it may represent a feeder pipe or fluid conduit to the mineralising system.
Table 5. Significant drill intersections from the Norwood – Golden Mount prospect area
The Sarah Howson area covers approximately 10 km2 and is located about 4 kilometres north of the township of Pentland. The gold anomalous area consists of a number of historical gold vein workings, plus the Stanley epithermal prospect. Historical records suggest the mines were high grade, narrow in width, but extensive along strike (e.g. Sarah Howson Reef: approximately 1 m wide, 3 km long, with grades of 1-2 ounces per ton/30-60ppm).
The Stanley gold prospect is located around two kilometres to the west of the Sarah Howson-Twilight trend. It comprises a zone of intense alteration plus epithermal veins and breccias with moderately to highly anomalous gold, hosted by foliated granite and gneiss.
The mineralisation has an overall east-west trend and is partially obscured by overlying Tertiary sediments, particularly in the west and northwest and by sandy recent alluvial deposits. The prospect is partly held under ML 1631, Stanley’s Hope, held by Chinalco Yunnan Copper Australia Limited (CYU) in which ActivEX has no interest. Previous explorers carried out limited shallow drilling programs in the area of historical gold workings and over the Stanley epithermal prospect. The best drill intersections are summarised in Table 6.
Recent drilling in the ML area by CYU has intersected 14 metres @ 1.1g/t Au in the Stanley’s Hope Lease area less than 100 metres from the lease boundary. Interpretations by CYU indicate a gentle south dipping vein array which strike approximately east-west and extends 700 metres to the east, well into the ActivEX EPM. Little drill testing has occurred outside of the lease area, mainly due to the lack of outcrop in the area.
Work by ActivEX has traced epithermal veining from the Stanley’s Hope area across to Sarah Howson workings. Further sampling and mapping is required to highlight gold bearing areas of the epithermal system and areas of high vein density.
Table 6. Significant drill intersections from the Sarah Howson prospect area
The Nipple Breccia is an area of intense brecciation with anomalous copper, bismuth and molybdenum, with peripheral gold mineralisation (Deadmans prospect – 10m @ 1.1g/t Au) and anomalous base metals, silver, bismuth and tellurium. Previous exploration has centred on the old gold workings and around the Nipple Breccia outcrop but recent mapping has shown more extensive brecciation and has identified the unique geochemical distribution in the area. Further detailed sampling is required to refine the anomalous geochemistry and define drill targets.
Oxley Creek – EPM 15055 (Figure 2) includes the Gypsy Pocket intrusive and volcanic complex which is shedding gold and base metals from the intrusive and its brecciated contact aureole. The prospect bares a similar magnetic signature to the Norwood – Mt Remarkable complex but appears to have been more deeply eroded (stronger magnetically, less volcanics, more intrusives mapped). Geochemistry (anomalous base metals and gold in stream samples) and scattered alluvial gold occurrences led to the identification of the Quartz Hill, Scrubby Creek Shear and Chinamans prospects by previous explorers.
At Quartz Hill, a copper and molybdenum prospect, a chargeability anomaly was detected by a minor (2 lines) dipole IP survey and a gold anomalous zone has been identified in stream sediment samples. A single drill hole in this zone returned 186m grading 0.13% copper and 13ppm molybdenum hosted completely in meta-sediments cut by a series of quartz veins which carry the mineralisation. Further soil sampling is required to evaluate the area in detail.
Gold associated with elevated base metals (particularly lead) occurs within the Scrubby Creek and adjacent shears including several linear structures in biotite-muscovite schist of the Cape River Metamorphics. The linear structures trend east-northeast to east-west and comprise crushed zones with clay, chlorite and carbonate alteration, with local quartz-sulphide-carbonate veins. Drilling was limited to the Scrubby Creek Shear and the adjacent “67 Shear” and returned narrow intersections up to 1m grading 6.7g/t gold (SCDDH2), 1m grading 2.32g/t gold (SCRC011) and 3m grading 0.73g/t gold (SCRC011). Nine lines of dipole IP were also carried out but results were not anomalous.
The only work carried out at Chinamans was limited to a single IP line, however this area lies in a zone of significant stream copper, lead, zinc and gold anomalism related to the intrusion of the Gypsy Pocket pluton. No systematic geochemistry has been used in the Gypsy Pocket aureole to follow up the steam geochemical anomalies.
The Norwood South tenement consists of three separate land parcels covering extensions of mineralised trends (Figure 3). The southern section of the EPM covers an area south of the Pentland tenement (EPM 14332). The “vein corridor” responsible for mineralisation at Mt Remarkable and Norwood is believed to continue along the southwest trend beyond the Pentland tenement boundary. EPM 15185 will account for any extension of mineralisation from the known prospects at depth. The remaining two sections of the tenement cover the most prospective areas lying between the Pentland and Oxley Creek tenements on the mineralised northwest structural trend.
The Pentland Gold Project is located in the Cape River Province approximately 100km west of Charters Towers in North Queensland.
The tenement package covers a number of porphyry and IRGS related prospects at various stages in the exploration process. Current walk up drill targets exist in the Mt Remarkable and Norwood prospect areas with previous drilling highlights of 46m @ 0.92 g/t Au (Mt Remarkable), 18m @ 0.98 g/t Au and 8m @ 2.28 g/t Au (Norwood).
Significant potential exists at numerous other prospects with mineralised breccia zones, epithermal veins, shear zones and structural corridors discovered. A number of geophysical and geochemical targets at these prospects are yet to be drill tested.