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The Ravenswood Gold Project consists of granted EPMs 18424, 18426, 18637 and 25466, and EPM application 25467, and comprises a total of 117 sub-blocks encompassing an area of 380 sq. km. The Project is located in the Charters Towers Province within the Thompson Orogen in northeast Queensland, approximately 90km south-southeast of Townsville. ActivEX Limited holds 100% interest in all the tenements.
The Project tenements are located in the highly prospective Charters Towers – Ravenswood region, an area that has produced over 12Moz of Au, and hosts the 3.8Moz Mount Leyshon and 1Moz Mount Wright Au deposits.
The Ravenswood Gold Project is located in one of the most prospective terrains in northeast Queensland, along trend from the 3.8Moz Mount Leyshon Au deposit, and in an area where anomalous precious and base metal mineralisation is widespread. Mount Leyshon was one of Australia’s largest Au producers during the 1990’s. From 1986 until mine closure in 2002 the deposit produced approximately 3.8Moz of Au and 2.4Moz of Ag.
Characteristics of the Ravenswood Gold Project that enhance its prospectivity include:
Mineralisation styles in the area of the Ravenswood Gold Project include:
The southwestern Ravenswood tenements are located within the Mount Leyshon Corridor, a broad zone trending several kilometres northeast from the Mount Leyshon deposit and encompassing a number of occurrences of highly altered and mineralised breccias associated with Carboniferous – Permian intrusions. The ActivEX tenement package provides continuous coverage of over 30km of the prospective Mount Leyshon Corridor, along a northeast trend from the Mount Leyshon deposit.
The Ravenswood Gold Project is located in northeast Queensland, 20 to 30km south, east and northeast of the town of Charters Towers (Figure 1).
The Project tenements are located in variably undulating and partially cleared cattle grazing land. Access to most areas is good and attained via gazetted sealed and gravel roads and station tracks. Access to some areas may be restricted during the summer wet season due to flooded creeks and rivers.
The Ravenswood Gold Project is within the area covered by the Charters Towers (SF5502) and Townsville (SE5514) 1:250,000 map sheets, and the Charters Towers (8157), Ravenswood (8257) and Mingela (8258) 1:100,000 map sheets.
Figure 1. Ravenswood Gold Project location
The Ravenswood Gold Project comprises granted exploration tenements, EPMs 18424, 18426, 18637 and 25466 and exploration tenement application, EPMa 25467. All tenements are held 100% by ActivEX Limited.
Table 1. Summary of Individual Tenement Details
EPMs 18637 and 18426 (and 25467 upon its grant) are subject to an Exploration Agreement with the Birriah People. EPMs 18424 and 25466 were granted under the Native Title Protection Conditions and currently there is no Native Title Claim over the tenements.
Figure 2. Ravenswood Gold Project tenements (also showing Mining Leases – not held by ActivEX)
The Charters Towers – Ravenswood area was a focus of extensive exploration activity during the 1980’s and into the 1990’s. Activities were largely focussed on the search for Au associated with Late Palaeozoic intrusions, and for polymetallic VHMS style mineralisation in Cambrian metavolcanics. In common with many other areas, exploration activity in the region declined into the late 1990’s and onwards. However, despite this decline, there has been low key but consistent exploration ongoing within the region that has resulted in the definition of extensions to known deposits e.g. Pajingo, and the definition of resources at historical occurrences, e.g. Welcome Breccia Au, Waterloo polymetallic deposit. The success of these ongoing programmes highlights the exploration potential of the region, and underlines the opportunities presented by a highly prospective terrain that has been underexplored in recent years.
Exploration highlights in the region in the last three decades include:
The Ravenswood Gold Project tenements are located in the Charters Towers Province within the Thompson Orogen. The Charters Towers Province is characterized by Neoproterozoic to early Palaeozoic assemblages.
The geology of the Ravenswood Gold Project area is dominated by Ordovician-Silurian granitoids of the Macrossan association which crop out as plutons and screens between Silurian – Devonian granitoids of the Pama association. Rocks of the Late Cambrian – Early Ordovician Seventy Mile Range Group occur in the southwest of the Project area, in the southern sub-blocks of EPM 18424. Carboniferous to Permian intrusive and extrusive rocks of the Kennedy association occur scattered throughout the Project area.
The Mount Leyshon Au-Ag deposit is the most significant deposit within the immediate area of the Ravenswood Gold Project. It is hosted in a Permo – Carboniferous (~290Ma) breccia complex that straddles the contact between Cambrian Puddler Creek Formation metasediments and the Ordovician Fenian Granite.
Mount Leyshon and other intrusion/porphyry related occurrences largely occur within a northeast trending corridor referred to as the Mount Leyshon Corridor.
Figure 3. Ravenswood Gold Project geology with main mineral occurrences/prospects
Figure 4. Ravenswood Gold Project merged regional airborne magnetics
The area encompassed by EPM 18424 hosts numerous occurrences of anomalous Au, locally associated with Ag and/or base metals. The prospects that have generated most exploration activity in the last two decades are located in the northeast of the EPM, within the Mount Leyshon Corridor. The tenement is also cross-cut by the northwest trending Merri Monarch Corridor, which intersects the Mount Leyshon Corridor approximately halfway between Mount Leyshon and Seventy Mile Mount.
There is a long history of exploration over the prospects which occur in and around this tenement; this history is summarised in Appendix 1. The most recent period of active exploration was from 2001 to 2009, when the tenement area was held by Leyshon Resources. In 2003 Leyshon Resources entered into a joint venture agreement with Newcrest Mining (the Fenian Joint Venture) with Newcrest the manager of the exploration program. The main activity during the Fenian Joint Venture period was the drilling of several deep diamond holes into prospects identified within the Mount Leyshon Corridor.
Seventy Mile Mount (and nearby Middle Mount) were identified as breccia pipes in the mid 1970’s. The breccias are located on two topographic highs approximately 9km northeast of Mount Leyshon, within the Mount Leyshon Corridor.
Seventy Mile Mount comprises a multi-phase breccia pipe that intrudes Ravenswood granodiorites; brecciation occurs over an area at least 250m long and 20m to 130m wide. Rocks associated with the breccia include igneous units that have been correlated with the Mount Leyshon Volcanic Complex. The breccia near surface is mainly quartz-sericite altered and cut by quartz-sulphide cavities and veins. Intense hematite-albite-illite-pyrite alteration is reported from drill holes, overprinting propylitic altered granodiorite.
In 2002 Leyshon Resources summarized the best drill intercepts from previous drilling (see Table 2), identified a mineralised envelope of low-grade 0.1 to 0.5g/t Au material, and proposed that the earlier drilling had been carried out sub-parallel to the principal fault direction, i.e. northwest-southeast.
During the period of the Fenian Joint Venture with Newcrest Mining two angled diamond holes, 383.3m and 471m deep, were drilled at Seventy Mile Mount to test below shallow Au intersections. The best result from this drilling was 0.4m at 5.5g/t Au (Table 2).
Although almost 50 holes have been drilled in and around the Seventy Mile Mount breccia, most have tested to less than 100m below surface, and the prospect remains prospective and in need of further testing.
The quartz-sericite-pyrite breccia at Middle Mount occurs as three outcropping areas. The breccias comprise milled and altered granodiorite and rare aplitic fragments in a matrix of altered and comminuted granodioritic material. Alteration associated with the breccias is dominantly white mica-quartz assemblages. Additional alteration products are pyrite, tourmaline, topaz, siderite, barite and rutile.
Approximately 150m to 250m to the east-southeast of Middle Mount, strongly sericite altered aplite porphyry exhibits “brain rock” textures (i.e. unidirectional solidification textures). This textural rock type is has been commonly observed associated with North Queensland Au deposits related to high level intrusives, e.g. the Kidston Au deposit.
Historical surface sampling returned only weakly to moderately anomalous Au (up to 1g/t in rock chip samples), typically with low base metals. There has been very little drilling in the immediate area of the prospect; limited drilling by Pan Australia in 1991 did not intersect Au values above 0.06g/t, and a diamond hole drilled by Newcrest in 2004 did not return anomalous Au values. However, the Newcrest hole did intersect locally anomalous Cu and Mo, with best intersections from FEN004 including:
In addition, the presence of brain rock along with halogen-bearing alteration minerals (e.g. tourmaline, topaz) strongly suggests this prospect is occurring near the apical region of an intrusion, and provides important geological context for the alteration and mineralization in the adjoining areas within the Mount Leyshon corridor.
Table 2. Assay intersections >1.5g/t Au from historic drilling at Seventy Mile Mount
The Matthews Pinnacle and Black Knight prospects are located within the Mount Leyshon Corridor, 6.7km northeast of Mount Leyshon and 2.4km southwest of Seventy Mile Mount. The Black Knight prospect is located approximately 300m south of Matthews Pinnacle.
A main focus of previous exploration was a rhyolite porphyry and breccia pipe complex similar to that at Mount Leyshon, with associated sericite-quartz-pyrite and argillic alteration. Two styles of quartz veining were identified:
Surface sampling and drilling by previous explorers identified only local weakly anomalous Au and Ag, however, moderately to highly anomalous Cu, Pb, Zn and Mo results were returned. Historical soil data indicate a close spatial relationship between coincident Mo and base metal anomalies and a reverse polarity magnetic low associated with Matthews Pinnacle – Black Knight.
While over 100 holes have been drilled within a one kilometre radius of the prospect area - within the large area of anomalous surface geochemistry that encompasses the Matthews Pinnacle and Black Knight prospects - many of the early holes were assayed for Au only. In addition, nearly all of the drill holes were less than 100m deep, and more than half are RAB holes less than 20m deep. There has been only limited deep drill testing of the area, and this was carried out by Normandy Mount Leyshon and Newcrest Mining. The most recent drilling, by Newcrest Mining during the period of the Fenian Joint Venture, confirmed the presence of anomalous base metals and Mo.
Fenian JV hole FEN005, targeted on a magnetic low at Black Knight, intersected zones of silica-pyrite altered quartz porphyry rhyolite and cavity breccia; the breccia and alteration were reported to be visually similar to the Mount Leyshon breccia. Extensive intersections of anomalous base metals and Bi were intersected, along with local minor anomalous Mo and Au. Best drill intersections included:
Fenian JV hole FEN008, collared on the north side of Matthews Pinnacle and drilling to the south under an area of anomalous Mo in soils, confirmed the presence of anomalous base metals and Mo at depth on the northern side. The assay data from this hole included scattered intervals of many hundreds to thousands of ppm Mo – up to 4900ppm. Elevated Mo was locally associated with highly anomalous Zn (to 4%), Pb (to 0.13%), Cu (to 0.16%), Bi (to 832ppm) and Ag (to 67.5ppm). Gold results were very low, with only three assays returning greater than 0.1g/t Au from intercepts of 1m or less. Anomalous intersections included:
The Matthews Pinnacle – Black Knight area comprises an extensive zone of anomalous metals, with associated brecciation and alteration, and a magnetic low (reverse polarity?) feature suggesting the presence of Permian intrusive body. The prospect area presents numerous features characteristic of intrusion-related mineralisation and, given the limited testing to date, remains highly prospective.
This is an area at the intersection of the Mount Leyshon and Merrie Monarch Corridors. The intersection is marked by:
This is a topographically flat and relatively low-lying area. Some of the soil anomalies may be due to transport down-slope from anomalous elevated areas to the east and west. However, the presence of a coincident magnetic low, suggesting alteration of the magnetic diorite in a possible dilation zone, indicates this area warrants further investigation. To further speculate on the significance of this area, the regional aeromagnetic image suggests this area is also located at the intersection of a number of broad curvilinear features. The significance of these features is unknown, but perhaps they reflect the effects of movement along the northeast and northwest trends represented by the Mount Leyshon and Merrie Monarch Corridors.
Within EPM 18637 there are several small Au mineral occurrences. The occurrences that have received most attention from modern explorers are the King Solomon and the Rose of Allendale. Exploration activities by ActivEX Limited since acquiring the tenement have consisted of a review of previous exploration.
In the immediate area of EPM 18637 the most significant mineralization occurs at the Welcome Breccia deposit, located 1km to the north of the EPM, and currently held under mining lease by Carpentaria Gold Pty Ltd.
The Au mineralization at Welcome Breaccia occurs in and near a breccia pipe located within granodiorite at the intersection of the Alex Hill Shear Zone with a north trending cross fault (Mustard, 2003: CR 33909). The breccia pipe is approximately 50m x 20m at surface with an adjacent quartz-sulphide vein array that extends up to 30m from the breccia, and is at least 600m deep. Recent exploration by Carpentaria Gold delineated a total resource of 2.04Mt @ 3.2g/t Au.
The King Solomon prospect is located in steeply dipping shear zones within altered diorite and gabbro. Mineralisation appears to be localised along east-west trending contacts between granitic and dioritic rocks, and associated with an east-west trending magnetic low.
A program of 20 shallow percussion and reverse circulation drilling by Metals Exploration/Gold Mines of Kalgoorlie in the early 1990’s intersected several intervals of moderately to highly anomalous Au, including:
At the Rose of Allandale, Au mineralisation is associated with a vein trending east-northeast for 350m along the contact between sheared diorite and granodiorite. Historical soil sampling delineated a broad zone of anomalous Au about 300m long, coincident with a magnetic low. A program of 18 shallow percussion and reverse circulation drill holes by Metals Exploration/Gold Mines of Kalgoorlie intersected weakly to moderately anomalous Au, with best intersections including:
The Cornishman EPM 18426 is located northeast of Mount Leyshon, along the trend of the Mount Leyshon Corridor. The ground was most recently held by Tamaya Resources. Previous companies who had carried out significant exploration over this area were Planet Metals, Sovereign Minerals, Union Oil Development, and Aurora Gold.
In 2007 Tamaya announced exploration results, with several prospect areas in the west of the EPM marked as encouraging and warranting follow-up work. The area considered most prospective was the circular Cornishman Complex, which is encompassed by EPM 18426. The Carboniferous – Permian felsic to mafic units of the Cornishman Complex comprise breccia, quartz-feldspar porphyry, rhyolites, andesites, gabbros, dacite and ignimbrites.
The quartz-feldspar porphyry of the Cornishman Complex has been described as an intrusive dyke breccia complex with a similar appearance to the Main Pipe Breccia at Mount Leyshon. The breccia is fault bounded and covers an area of 2 sq. km with an anomalously low magnetic response.
Mapping and rock chip sampling in the Cornishman project area by Tamaya Resources identified several prospects. The highest Au assays were obtained from narrow vein Au. A breccia located in the centre of the project area returned anomalous base metal and Bi results in rock chip samples. Several targets were proposed for drill testing:
Tamaya Resources went into liquidation in 2009 and no further work was carried out. The prospective areas remain untested.
Charlie CreeK – EPM 25466
This EPM covers an area of Siluro-Devonian Deane Creek Granodiorite. Although the Deane Creek Granodiorite is shown on the government geological maps as one unit of granodiorite-granite-monzodiorite, with a core of trondhjemite, the airborne geophysical data indicate the intrusion is compositionally complex. Based on the aeromagnetic data, the area of Deane Creek Granodiorite encompassed by the EPM is cut by a northeast trending linear feature that is a continuation of the trend of the Mount Leyshon Corridor.
This tenement provides continuous coverage of the Mount Leyshon Corridor for ActivEX Limited, adjoining both EPM 18424 Mount Leyshon and EPM 18426 Cornishman.
This EPM is located in an area of Siluro-Devonian and Ordovician granitoids. The most recent exploration over the tenement areas was carried out by Carpentaria Gold, who identified several prospects which were investigated with soil and rock chip sampling.
Carpentaria also carried out a high resolution aeromagnetic survey that covered EPM Application 25467, and the results suggest there is greater complexity and more fault-related contacts than shown in the government geological mapping. Also, in the northeast of the tenement there is a curious northeast trending elliptical magnetic low feature with a slightly more magnetic core. This feature cannot be fully explained by the mapped geology. It occurs in the same area as Carpentaria Gold’s Au anomalous soils at the Grass Hut prospect, and perhaps is reflecting variations due to alteration and/or an unmapped or buried intrusion.
The best results from Carpentaria’s rock chip sampling program came from the Grass Hut prospect. Six rock chip samples of quartz veined mullock collected in the vicinity of Grass Hut returned greater than 1g/t Au, with the highest values:
Based on Carpentaria’s work, the Grass Hut area warrants further investigation as it presents highly anomalous surface geochemistry associated with a curious magnetic feature.
The Ravenswood Gold Project comprises four granted EPMs and one EPM application in the Charters Towers – Ravenswood area of northeastern Queensland.
The Project is located in one of the most prospective terrains in northeast Queensland, along trend from the 3.8Moz Mount Leyshon Au deposit, and in an area where anomalous precious and base metal mineralisation is widespread.
The ActivEX tenement package provides continuous coverage of over 30km of the prospective Mount Leyshon Corridor, along a northeast trend from the Mount Leyshon deposit.
Several Au, Mo and base metal occurrences have been identified within the tenements; many of these occur with breccias and associated with Late Palaeozoic intrusions.
Many of the prospects identified by previous explorers have had little or no drilling deeper than 50m, and prospective geology, surface geochemistry and geophysical anomalies remain inadequately tested.