Ardea Resources Limited - Shallow Gold Resource at Mount Aubrey, NSW.
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Release date- 28082019 - Ardea Resources Limited (Ardea or the Company) is pleased to announce an initial Inferred Mineral Resource estimate, following JORC Code 2012 guidelines, for its Mount Aubrey epithermal gold deposit in the Lachlan Fold Belt, central New South Wales.
Ardea CEO, Andrew Penkethman commented: 'The Mount Aubrey Gold Project is being vended into Godolphin Resources, Ardea's planned IPO of its NSW gold and base metal assets. The maiden Mount Aubrey Inferred Mineral Resource is just the beginning for this project and only extends over one kilometre of a seven-kilometre epithermal vein system. With the limited drilling completed over this one kilometre only extending to an average depth of 40 metres, the mineral system is wide open and presents a compelling target for Godolphin Resources to start drilling on the day of listing.'
Mount Aubrey Mineral Resource Summary
Mount Aubrey is a 1989-91 open pit gold mine (BHP Gold) located in central western NSW that was backfilled and rehabilitated as agreed with the land holder upon completion of mining of near-surface mineralisation. Historic data collated by Ardea has enabled estimation of an Inferred Mineral Resource that will serve as the platform from which future exploration and resource definition by spinout Godolphin Resources will build upon.
This is the second in a series of announcements providing resource updates that mark the conclusion of Ardea's extensive work programs on selected NSW projects in preparation for the Godolphin Resources IPO towards the end of 2019. These announcements will provide clarity to investors regarding the NSW portfolio and highlight the potential it holds, notably for the rapid definition of additional gold resources and development of open pit gold deposits.
The Mount Aubrey project area is located approximately 40 km northeast of Parkes NSW, 32 km southeast of Peak Hill, and 30 km southwest of Yeoval NSW. The tenement is also located approximately 48 km southeast from the operating Tomingley Gold Mine. The project is located within the Lachlan Fold Belt (LFB) which is Australia's premier domain for porphyry and epithermal gold and base metal deposits. The resource area is readily accessible by well-maintained sealed and unsealed roads.
Geology and Geological Interpretation
The Mount Aubrey resource area is located at the northern margin of the highly prospective, WNWtrending Lachlan Transverse Zone of the Lachlan Fold Belt. The Transverse Zone is recognised as having a strong association with a number of other significant mineral deposits in Central NSW, such as the worldclass Cadia Ridgeway and Northparkes copper-gold mining operations.
The Mount Aubrey deposit is hosted by a volcano-sedimentary package of the Silurian-Devonian Dulladerry Volcanics. Most mineralisation is hosted by pillow-textured, subaqueous amygdaloidal basalt that is up to 130 m thick. It is both overlain and underlain by pyroclastic rhyolitic ignimbrites that are variably interbanded with sedimentary units. The rhyolites commonly contain pervasive sericite alteration. Nearby, the Yeoval Batholith to the northeast is spatially and genetically associated with Cu-Au-Mo mineralisation.
This Cu-Au-Mo-fertile Yeoval intrusive complex consists of a suite of calc-alkaline granite and adamellite, intermediate and basic intrusive rocks with associated andesitic volcanic rocks. The batholith formed during a Late Silurian to Early Devonian melting and rifting event that split the Ordovician to Early Silurian Macquarie Arc. Continued extension resulted in accumulation of significant thicknesses of sedimentary and volcanic rocks during the Middle to Late Devonian Dulladerry Rift. Most if not all of the epithermal style gold mineralisation at and around Mount Aubrey is related to this extensional phase during the Middle to Late Devonian. The entire sequence is overlain by much younger, locally thick Tertiary-aged gravels.
The Mount Aubrey deposit is located within a WNW-trending quartz vein system with a strike extent of at least 7 km. The main mineralised vein pinches and swells, often bifurcating into parallel veins and some associated stockwork veins hosted within basaltic and felsic rocks of the Dulladerry Volcanics. The mineralisation style is well suited to open pit mining, including bulk tonnage style operations (which characterise the LFB).
The highest gold grades at Mount Aubrey are developed where epithermal-style quartz veins are hosted by basaltic rocks. Limited exploration suggests that overlying felsic ignimbrite volcanic rocks and underlying felsic volcanics and interbedded sediments generally contain less well-developed vein systems, but this impression could be a function of poor sample representation outside the known mineralised zones.
The WNW orientation of mineralised vein systems within the thick volcano-sedimentary pile at Mount Aubrey may be partly controlled by the underlying Lachlan Transverse zone. A similar WNW structural regime is well-developed in the Yeoval Batholith to the north and is visible in most of the geophysical imagery throughout the region. The partially outcropping Mount Aubrey deposit is considered to be a low-sulphidation, silica-rich epithermal deposit. However, the source of the gold-bearing fluids is not clear, and could either be granitic, structurally-controlled orogenic, or magmatic (related to the accumulation of the Dulladerry Volcanics).
The Mount Aubrey gold deposit was discovered and defined by BHP-UTAH and mined by BHP Gold Mines in 1989-91. Ore was treated at the London-Victoria Mine near Parkes. The Aubrey Mine consisted of three small open cut pits that extended over one kilometre of strike, within a much larger mineral system occurring over a 7 km east-west trending vein system. These pits were backfilled at the request of the then-landowner upon completion of mining operations in 1991.
BHP was curtailed in their mining operations by an agreement with the landowner that there would be no drilling or blasting during the operation of the project which precluded pit cut-backs to recover ore in the base of pits (Ardea and Godolphin are fortunate that the current landowners are supportive). As such, the BHP operation was a free-dig one limited by the abilities of the then-available excavators. The high-grade nature of the near-surface mineralisation and the low operation costs offset the low, sub- $400 (US) gold prices of the time. BHP reportedly recovered 120,000 tonnes at 3.3 g/t gold for 12,700 oz of gold. No mill reconciliation data is available.
Gold mineralisation was originally discovered around 1880-1890 by the Hodges family, and was worked on a small scale at varying stages through to 1939.
Sampling and Sub-Sampling Techniques
The Mount Aubrey Resource data comprises several decades' data from 219 drill holes for a total of 9,382 m. Reverse circulation (RC) drilling, diamond drilling (DD), rotary air blast (RAB) drilling and aircore drilling have contributed to the Mount Aubrey resource database. Average downhole depth was 42.8 m. Most sampling was undertaken at 1 m intervals.
The Resource is based on sub-surface samples obtained by the above drilling. Earliest drilling tested the delineated mineralized quartz veins and anomalous soils forming the Mount Aubrey deposit. This progressed into drilling on grid sections to test the mineralisation at intervals appropriate for improving confidence in mineralised continuity and mostly on a 20m spacing.
Two main periods of data collection were as follows:
1987-1990 (BHP Gold) - Diamond, RC and RAB drilling, with samples analysed at Australia Analytical Laboratory (AAL), Orange. Gold assayed by fire assay. Selected base metals and path finders including Ag, As, Cu, Pb, Zn, Sb, W assayed by atomic absorption spectrometry (AAS).
2007-2011 (YTC Resources) - Diamond, RC, and RAB drilling, with samples analysed either at the SGS laboratory, West Wyalong, and/or the ALS laboratory, Orange. Gold assayed by fire assay. Multi-element suites were assayed using inductively coupled plasma mass spectrometry (ICP-MS).
The resource is largely constructed from the results of percussive drilling. In summary, percussive drilling techniques used at Mount Aubrey are as follows:
28 Aircore holes were drilled by YTC resources using a 90mm aircore blade bit.
31 RAB holes were drilled by BHP Gold with limited information on drill rig configuration given except that a standard RAB open hole with RAB blade bit were used. Drill chips were retrieved from the drill hole and collected in bulk bags through the use of a drill rig-mounted cyclone.
157 RC holes were drilled by BHP and YTC Resources. In both cases a standard reverse circulation drilling configuration was used with a hammer and drill bit of 150mm size (approximate) used. Drill chips were retrieved from the drill hole and collected in bulk bags through the use of a drill rig-mounted cyclone.
Several diamond holes were also drilled. In total there were four such holes, though only three were used in the resource due to loss of historic data from one hole (MAD001 - BHP Gold). Drill holes MAD002,003 and 004 were drilled by YTC Resources using triple tubed HQ and NQ diameter core from surface and were oriented using an orientation tool and a downhole camera. Most drill holes were drilled towards the NNE (mostly bearing 018) and at an inclination of -60. Drill collars were picked up by a surveyor or using a handheld GPS, providing adequate spatial control.
The entire Mount Aubrey resource estimate is classified as an Inferred Mineral Resource under JORC 2012 criteria. The Inferred Resource is estimated to be 1.21 Mt at 1.61 g/t gold, when using a 0.5 g/t Au cut off. The Resource is estimated to contain approximately 62,400 oz gold metal.
In making this classification, numerous factors have been considered, including:
Drill data spacing of 20m x 20m and coordinate accuracy are sufficient for the style of mineralisation (could potentially be Indicated to Measured status but downgraded to Inferred to reflect old historic data and relying on Ground Penetrating Radar for pit void shapes as opposed to a pit survey).
The continuity of gold mineralisation along modelled veins is generally very good.
The domains that have been constructed seem appropriate in relation to the information available and currently understood epithermal model of formation of the gold mineralisation.
The result of this estimation does reflect the competent person's view of the deposit based on the information available. The domains are consistent with historic reports of the mined veins and modelling has constrained strike extensions of geology so as not to extend far beyond data limits. The model grades also reflect the raw composite grades and is not over-estimating the grade in the deposit.
Sample Analysis and Estimation Methodology
Resource modelling of the Mount Aubrey Project deposit is based on estimating grades for gold by inverse distance using LeapFrog Edge software. Search parameters were based on the variogram models with ellipsoid searches being used to set a maximum of 20 and minimum of 10 samples for each interpolation. The distribution of gold was reviewed for the project area. Mineralised domains were defined based on a 0.5 g/t gold threshold and varying vein distributions and orientations. No top cuts were applied.
In total, four separate domains were defined by implicit modelling in Leapfrog, with each domain containing sub-parallel sets of epithermal veins. A resource for each set of parallel veins was individually estimated, with individual estimation neighbourhoods to ensure tailored criteria for optimal results.
Grades were interpolated using inverse distance estimation. A sub-blocked block model was built using the quartz veins and a digital terrain model of the surface. Only the quartz veins were domained and modelled. The parent cell of 5m x 10m x 10m in the X, Y and Z dimensions was chosen to reflect observed 2-8m vein width. This also reflects the drill hole intercept spacing of 20m x 20m for a significant portion of the deposit. The parent blocks were sub-celled to 1m x 1m x 1m to accurately estimate the volume of material inside each lens domain.
The specific gravity used for the estimation was 2.7 t/m3 . This is the density of quartz (2.65 t/m3 ) plus an additional allowance for sulphides such as pyrite, which are present within the mineralised host rock. The specific gravity used in the resource estimate is therefore considered appropriate. It is expected that increasing gold grade would increase the SG beyond 2.7 t/m3 and thus this estimate would represent the lower end of the tonnage spectrum for this resource. Bulk density calculations are planned on the core produced from the first/next diamond drill program. Validation of outputs was conducted against historic production reports.
There are presently no extreme outlier values in the Mount Aubrey dataset, with the maximum gold grade (over 1 m composite) being 16.5 g/t Au. Therefore, for the Mount Aubrey resource estimate, it is considered that at this stage no top cuts to gold grades are required in this study
Mining and Metallurgical Methods and Parameters and Other Modifying Factors
There have been no geotechnical or metallurgical studies completed on drill samples from the Mount Aubrey project area. However, given the historic operations, it has been assumed that the mineralisation would be amenable to conventional open pit mining and mineral processing as per other low-sulphidation epithermal gold deposits of the Lachlan Fold Belt.
Project Potential and Work Planned
Significant scope exists for expansion of the Mount Aubrey resource. The resource is open in all directions and is clearly part of a much larger set of veins that extent for over 7 km strike in outcrop, subcrop, and the subsurface. Most of these veins have not been drilled. Mount Aubrey is a typical low-sulphidation epithermal gold system. Such systems commonly display well documented, predictable vertical zonation patterns related to temperature and pressure zonation. At Mount Aubrey, most alteration in the mined, topmost 40 m is silicification. Some examples of quartz-illite+/-adularia alteration have been documented at depth, consistent with the vertical zonation expected, and it is this alteration assemblage that is commonly associated with high-grade gold (and silver) mineralisation.
It is appropriate to draw parallels to the Pajingo gold deposit of northern Queensland. On the Vera-Nancy orebodies, similar grades and mineralisation distributions to those at Mount Aubrey were encountered near surface. Higher-grade, more extensive gold and silver mineralisation corresponds to quartzillite+/-adularia alteration at depth. By comparison, it is clear that future drilling at Mount Aubrey must be targeted below the current depth of most historic drilling to target high-grade gold.
The work undertaken by Ardea on the Mount Aubrey gold project has set Godolphin Resources up with a well-defined gold resource that represents a walk-up drill target where additional ounces are expected to be defined quickly and cost effectively. Historically, only one kilometre of a seven-kilometre mineral system has been tested by drilling. Drilling of this compelling target is set to commence immediately after Godolphin resources lists on the ASX.
About Ardea Resources
Ardea Resources ('Ardea' - ASX:ARL) is an ASX listed resources company, with 100% controlled Australian-based projects, prioritising a three-pronged value creation strategy which is:
development of the Goongarrie Nickel Cobalt Project, which is part of the Kalgoorlie Nickel Project, a globally significant series of nickel-cobalt deposits which host the largest nickel-cobalt resource in the developed world, coincidentally located as a cover sequence overlying fertile orogenic gold targets;
advanced-stage exploration at WA gold and nickel sulphide targets within the Eastern Goldfields world-class nickel-gold province and the Godolphin Resources Limited demerger of the NSW gold and base metal assets with planned in-specie share distribution, with all projects located within the Lachlan Fold Belt world-class goldcopper province, specifically within the Lachlan Transverse Zone (hosts McPhillamy's gold and Cadia and Northparkes copper-gold) and splay fault of the Gilmore Suture (hosts Cowal gold).
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CAUTIONARY NOTE REGARDING FORWARD-LOOKING INFORMATION
This news release contains forward-looking statements and forward-looking information within the meaning of applicable Australian securities laws, which are based on expectations, estimates and projections as of the date of this news release. This forward-looking information includes, or may be based upon, without limitation, estimates, forecasts and statements as to management's expectations with respect to, among other things, the timing and ability to complete the Ardea spin-out of Godolphin Resources Limited, the timing and amount of funding required to execute the Company's exploration, development and business plans, capital and exploration expenditures, the effect on the Company of any changes to existing legislation or policy, government regulation of mining operations, the length of time required to obtain permits, certifications and approvals, the success of exploration, development and mining activities, the geology of the Company's properties, environmental risks, the availability of labour, the focus of the Company in the future, demand and market outlook for precious metals and the prices thereof, progress in development of mineral properties, the Company's ability to raise funding privately or on a public market in the future, the Company's future growth, results of operations, performance, and business prospects and opportunities. Wherever possible, words such as 'anticipate', 'believe', 'expect', 'intend', 'may' and similar expressions have been used to identify such forward-looking information. Forward-looking information is based on the opinions and estimates of management at the date the information is given, and on information available to management at such time.
Forward-looking information involves significant risks, uncertainties, assumptions and other factors that could cause actual results, performance or achievements to differ materially from the results discussed or implied in the forward-looking information. These factors, including, but not limited to, the ability to complete the Ardea spin-out of Godolphin Resources Limited on the basis of the proposed terms and timing or at all, fluctuations in currency markets, fluctuations in commodity prices, the ability of the Company to access sufficient capital on favourable terms or at all, changes in national and local government legislation, taxation, controls, regulations, political or economic developments in Australia or other countries in which the Company does business or may carry on business in the future, operational or technical difficulties in connection with exploration or development activities, employee relations, the speculative nature of mineral exploration and development, obtaining necessary licenses and permits, diminishing quantities and grades of mineral reserves, contests over title to properties, especially title to undeveloped properties, the inherent risks involved in the exploration and development of mineral properties, the uncertainties involved in interpreting drill results and other geological data, environmental hazards, industrial accidents, unusual or unexpected formations, pressures, cave-ins and flooding, limitations of insurance coverage and the possibility of project cost overruns or unanticipated costs and expenses, and should be considered carefully. Many of these uncertainties and contingencies can affect the Company's actual results and could cause actual results to differ materially from those expressed or implied in any forward-looking statements made by, or on behalf of, the Company. Prospective investors should not place undue reliance on any forward-looking information.
Although the forward-looking information contained in this news release is based upon what management believes, or believed at the time, to be reasonable assumptions, the Company cannot assure prospective purchasers that actual results will be consistent with such forwardlooking information, as there may be other factors that cause results not to be as anticipated, estimated or intended, and neither the Company nor any other person assumes responsibility for the accuracy and completeness of any such forward-looking information. The Company does not undertake, and assumes no obligation, to update or revise any such forward-looking statements or forward-looking information contained herein to reflect new events or circumstances, except as may be required by law.
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|Date:||Aug 29, 2019|
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