Aeris Resources’ exploration activities are focussed on two highly-prospective areas:
- The package of tenements surrounding the Tritton Copper Operations in NSW; and
- The Torrens project in South Australia
Tritton Regional Exploration
Aeris has a number of prospective exploration tenements in NSW surrounding the current Tritton Copper Operations collectively referred to as the Tritton tenement package.
To date over 750,000 tonnes of copper, including the Current Mineral Resource deposits has been discovered within the bottom half of the tenement package within a 50 kilometre corridor adjacent to a stratigraphic unit referred to as the Budgery Sandstone. Geological mapping has extended the known extents of the Budgery Sandstone unit a further 65 kilometres through the northern half of the tenement package, with potential to extend for a further 40 kilometres.The package covers an area of 2,160km2 and is 100% owned by Aeris. There is also a small tenement at nearby Canbelego held in joint venture (30%) with Helix Resources.
Tritton Mine Tenement Package
A strategic greenfields exploration program is underway, focussed on the current tenement package and looking for Tritton-sized orebodies of more than 10-million tonnes.
Six major geological complexes have been identified to date: Tritton, Girilambone, Budgery, Kurrajong, Miandetta and Exley. These complexes are found within a sequence of sedimentary and volcanogenic rocks extending over a combined strike length of more than 100 kilometres.
Within a single volcanic complex it is common to find one or two large deposits and numerous smaller deposits. A large deposit may be 20 million tonnes, such as the Tritton Deposit, while the smaller deposits can be sub one million tonnes or up to two million tonnes in size.
The exploration plan is to test each of the volcanic complexes, looking deeper than previously, with a focus on discovering larger, Tritton-sized (10Mt+) deposits.
The exploration techniques and technology utilised to date have been very effective in identifying and defining copper deposits within the tenement package, with a focus on exploring within 250 metres from surface. This strategy has been successful in discovering more than 750,000 tonnes of copper in the southern half of the Tritton tenement package along a geological trend of approximately 50 kilometres in strike. Importantly, the northern half of the package has had very little exploration undertaken to date. A geological mapping program completed in 2017 extended the strike length of the known geological trend by a further 65 kilometres with a further 40 kilometres extension interpreted from geophysical surveys prompting the company to acquire a new exploration tenement, EL8810.
The majority of the deposits are detectable from electromagnetic (EM) geophysical methods, which were instrumental in the discovery of the Tritton Deposit.
The current exploration program includes the application of new high power electromagnetic technologies to detect mineralisation at greater depths, down to 500 metres below surface.
In-conjunction with the ground based EM surveys two airborne EM surveys have been completed within the Tritton tenement package. Although the airborne EM surveys are not able to detect a conductive body to similar depths as the ground based system, the airborne EM surveys are a cost effective first pass evaluation approach to efficiently vector toward a mineralised system.
The first airborne EM survey utilising the VTEMTM technology was conducted in January 2017 from which 4 new EM anomalies were detected warranting follow-up exploration. The survey totalling 228km2 covered four separate survey areas within the tenement package from which four new EM anomalies were identified.
A second airborne EM survey was conducted in December 2018. The survey of 617km2 covering the northern half of the tenement not previously covered by the initial VTEM survey. The survey area was divided into 8 sections to ensure flight line orientations were close to perpendicular to the interpreted geological trend. Survey flight lines were spaced either 150 metres or 200 metres apart to ensure appropriate coverage to detect sulphide bodies with similar strike dimensions to the known deposits within the tenement package.
A total of 25 new mid-to-late time EM anomalies have been identified from the December 2018 AEM survey. Of these 25 new anomalies, 9 are considered high priority targets. Systematic and focused greenfields exploration over the northern half of the tenement package has been limited to date. The results from the AEM survey confirms the Company’s view that there is significant potential to discover additional copper sulphide deposits in the northern half of the Tritton tenement package. The number of EM anomalies identified to date on the northern half of the tenement now totals 29, including 4 anomalies detected from the initial AEM VTEM-MaxTM survey completed in January 2017.
Preliminary geophysical modelling commenced. Once the geophysical modelling is completed each EM anomaly will be ranked according to prospectivity, in preparation for first pass ground-based moving loop EM (MLTEM) surveying, which will commence in the September 2019 quarter.
Plan view of the airborne EM Survey Coverage and potential bedrock conductors through the northern extents of the Tritton tenement Package
The Kurrajong prospect is a known copper mineralised system defined by a broad surface geochemical anomaly and associated shallow historical workings. With the completion of a 14 hole drill program as announced on 8 July 2019 - Exploration Target Defined at Kurrajong, the Company defined an initial Exploration Target for Kurrajong ranging between 3 to 4 million tonnes at a copper grade between 1.5% to 2.0%.
Cu cut-off grade (%)
|Tonnage Range (Mt)||
Cu grade range (%)
Cu metal range (kt)
|Kurrajong||0.6||3 - 4||1.5 – 2.0||45 - 80|
The potential quantity and grade of the Exploration Target is conceptual in nature and is therefore an approximation. There has been insufficient exploration drilling to estimate a Mineral Resource and it is uncertain if further exploration will result in the estimation of a Mineral Resource.
Two previous drill programs completed at Kurrajong intersected sulphide mineralisation containing copper from a limited number of drillholes. Best drill intersections included TKJD007 4.0m @ 2.46% copper, TKJD008 6.0m @ 3.92% copper and TKJD012 10.0m @ 2.43% copper.
The modelled EM conductor plates from the current MLTEM survey correlate favourably with the historical higher grade drillhole intersections. Three-dimensional modelling of the MLTEM conductors at Kurrajong defined two stacked layers of moderate strength (1,500S to 2,000S) conductors positioned approximately 400 metres below surface, with dimensions in the range of 125 metres (strike) by 150 metres (depth).
Based on the EM conductor plates defined at Kurrajong an initial six hole drill program was undertaken from April 2018 to test for extensions to the high grade copper mineralisation intersected previously.
Five drillholes intersected sulphide mineralisation, with four intersecting massive sulphides containing high grade copper mineralisation.
The first drillhole (TKJD014) was designed to intersect copper mineralisation 150 metres down plunge from the three drillholes which had intersected high grade copper mineralisation from an earlier 2012-2013 drill campaign. TKJD014 intersected a significant zone of massive and semi-massive sulphides from 676.6m down hole. Assay results include:
- 19.4m @ 2.18% Cu, 0.30g/t Au, 7g/t Ag from 676.6m
TKJD015 was designed to test the interpreted up-plunge continuity of the high grade system within an area not previously drill tested. Previous electromagnetic surveying at Kurrajong had not detected a conductive body in this area. Two massive/semi-massive sulphide lenses were intersected from 403.4 metres down hole. The upper lens contained massive sulphides, dominated by pyrite and chalcopyrite over a 4.6 metre interval. The lower lens is characterised by banded/semi-massive sulphides (notably pyrite and chalcopyrite) with chalcopyrite veining in places. A 10.1 metre weakly mineralised (<0.5% Cu) to barren turbidite unit separates the mineralised lenses. Assay results returned include:
- 4.60m @ 5.09% Cu, 0.79g/t Au, 17g/t Ag from 403.4m
- 5.65m @ 2.52% Cu, 0.20g/t Au, 6g/t Ag from 418.1m
Drillhole TKJD016 was designed to target the DHEM off-hole anomaly detected along strike from TKJD014. The drillhole deviated further than expected and intersected the margin of the modelled plate, rather than the centre of the plate as planned. The drillhole intersected a broad zone of stringer sulphide mineralisation containing <10% contained sulphides (visual estimate). Assay results through the interval returned 45.4m @ 0.14% Cu.
The DHEM survey results from TKJD016 constrained the existing modelled DHEM plates and reaffirmed earlier observations that TKJD016 has not adequately tested the modelled DHEM plate. The DHEM plate remains a legitimate drill target and will be tested at a future date.
TKJD017 was designed to test the interpreted down-plunge extension of the high grade copper sulphide intersection in TKJD014. TKJD017 successfully intersected sulphide mineralisation including a 5 metres thick massive sulphide lens. Assay results returned from the sulphide zone include:
• 17.0m @ 2.59% Cu, 0.30g/t Au, 7g/t Ag from 753.0m including
• 5.0m @ 6.09% Cu, 0.83g/t Au, 20g/t Ag from 765.0m
Results from the initial six hole drill program exceeded expectations and the drill program was extended with a further eight drillholes (five parent drillholes and three wedge holes) completed at Kurrajong. The additional drillholes were completed by December 2018.
Drilling results from the extended program continued to intersect further high grade copper mineralisation. TKJD019 (4.5m @ 5.16% Cu) and TKJD023 (6.4m @ 4.55% Cu) intersected massive sulphide mineralisation toward the upper extents of the known mineralised system whilst TKJD017W2 (3.35m @ 6.51% Cu) intersected massive sulphide mineralisation along strike from a high grade copper interval reported previously from TKJD017 (17m @ 2.59% Cu).
Drillhole TKJD019 was designed to test the up-plunge extents of the high grade copper massive sulphide zone intersected in TKJD015 (4.6m @ 5.09% Cu and 5.65m @ 2.52% Cu). Drillhole TKJD019 intersected a 4.5 metres thick massive sulphide interval from 340.4 metre down hole. Assay results returned from the massive sulphide zone include:
• 4.5m @ 5.16% Cu, 0.48g/t Au, 16g/t Ag
A downhole electromagnetic (DHEM) survey completed from TKJD019 identified two conductive EM bodies. A small (35mx35m) low conductance (750S) in-hole conductor was detected which correlates with the massive sulphide intersected in the drillhole. The second conductive body is a significantly larger (75mx250m) strong conductance (4,000S-5,000S) off-hole conductor which aligns with the interpreted massive sulphide zone below TKJD015.
The deepest drillhole completed to date, TKJD024W1, intersected a broad zone of pyrite and chalcopyrite mineralisation (17.0m @ 1.25% Cu) approximately 300 metre down plunge from previous drillhole data (TKJD017 17.0m @ 2.59% Cu). The mineralised system has now been traced up to 1,100 metre down plunge and remains open in this direction and along strike to the north.
Drillhole TKJD017W2 was designed to test for high grade copper mineralisation along strike (south) from TKJD017 (17m @ 2.59% Cu).
A 3.35 metres thick massive/semi-massive sulphide interval was intersected from 753.35 metres downhole correlating with the predicted position of the interpreted massive sulphide horizon. The high grade copper intersection is approximately 40 metres south from the high grade copper interval intersected in TKJD017. Assay results returned from TKJD017W2 include:
• 3.35m @ 6.51% Cu, 0.62g/t Au, 17g/t Ag
Intersecting high grade copper mineralisation along strike from a previously drilled high grade copper intersection is very encouraging. Whilst the deposit is very continuous down plunge the along strike continuity has been inferred from DHEM plates. The high grade copper intersection from TKJD017W2 correlates well with DHEM modelled plates in the area meaning more confidence can be placed on the DHEM plates to assist with interpreting the extents of massive sulphide mineralisation.
Drillhole TKJD023 was designed to test continuity of the high grade copper massive sulphide zone between drillholes TKJD019 and TKJD015. TKJD023 successfully intersected massive/semi-massive sulphide mineralisation at the predicted position over a 6.4 metres interval from 401.60 metres downhole. Assay results returned from the massive/semi-massive sulphide zone include:
• 6.4m @ 4.55% Cu, 0.27g/t Au, 11g/t Ag
At the completion of drilling TKJD023 a DHEM survey was completed which detected an in-hole moderate strength conductive body (1,000S to 1,500S), coinciding with the high grade copper horizon intersected in the drillhole.
Drillhole TKJD017W1 was designed to test the strike continuity of high grade copper mineralisation north of TKJD017 (17m @ 2.59% Cu). The drillhole intersected the target horizon approximately 45 metre along strike from TKJD017. The drillhole intersected a broad (approximately 30 metres thick) banded and stringer pyrite dominant sulphide mineralisation with minor visible chalcopyrite at the target horizon.
A DHEM survey completed on TKJD017W1 detected an in-hole conductor at mid-time channels migrating to an off-hole conductor at later time channels. The in-hole response is likely associated with the banded/stringer pyrite dominant mineralisation whilst the off-hole conductor is interpreted to represent the massive sulphide zone indicating the drillhole was within 10 metres to 15 metres from intersecting the massive sulphide horizon.
TKJD020 was drilled 100 metre north of the interpreted massive sulphide horizon. The drillhole intersected approximately 5 metres of stringer pyrite with minor chalcopyrite mineralisation. A DHEM survey completed at the end of the drillhole detected a large (75mx250m) strong off-hole DHEM conductor (4,000S to 5,000S) positioned in line with the interpreted massive sulphide horizon between TKJD015 and TKJD010.
TKJD021 and TKJD022 were designed to test the up plunge extents of the massive sulphide horizon above TKJD019. Neither drillhole intersected notable sulphides. DHEM surveying on both drillholes did not detect off-hole conductive bodies indicating the massive sulphide horizon has either pinched out or broken up into smaller segments (<50mx<50m), below the DHEM detection limit.
With completion of the current phase of drilling at Kurrajong work has now shifted to the building of a detailed geological interpretation and predictive model. An output from this work will be the development of an exploration target model delineating potential tonnage and copper grade ranges based on current drillhole data. It is envisaged the interpretative geological work will be completed over the course of several months.
The Exploration Target is based entirely on diamond drill core from two drill programs completed between 2012 to 2018. Copper grade and density were estimated via Ordinary Kriging. The Exploration Target being conceptual in nature, does not take into account geological complexity or economic parameters, including potential mining methods or modifying factors.
Long section view of the interpreted Kurrajong mineralised system showing the modelled Exploration Target
SIGNIFICANCE OF RESULTS
The geometry of the modelled Kurrajong Exploration Target is similar to other copper deposits discovered within the Company’s Tritton tenement package. A feature, common to each known deposit is a long down plunge dimension, which at Tritton has been traced in-excess of 2 kilometres. Drilling at Kurrajong has traced the copper sulphide system 1,100 metres down plunge to date and remains open below this.
Additionally, sulphide mineralisation, albeit at lower copper grades (≤0.5% Cu), continues along strike to the north indicating there is potential for further higher grade copper systems to develop. Clustering of deposits is common in other areas within the Tritton tenement package, with multiple deposits occurring within several kilometres of each other.
THE PATH FORWARD
Further work at the Kurrajong deposit is justified on account of:
• The size and grade range of the Exploration Target;
• Geological similarities between Kurrajong and other deposits within the Company’s Tritton tenement package; and
• The prospectivity at Kurrajong and the potential to increase the size of the Exploration Target with further drilling.
The Company is currently planning the next stage of drilling which would be focused on updating the Exploration Target to an Inferred Mineral Resource. Initial work will focus on seeking the necessary regulatory approvals to allow further drilling to occur at Kurrajong.