Aeris Resources has kicked-off its two-year, $7.5 million greenfields exploration strategy with a significant regional electromagnetic geophysical survey over the Tritton and Kurrajong volcanic massive sulphide corridors within its Tritton tenement package in New South Wales. The EM survey is targetinglarge, Tritton sized, plus 10 million tonne deposits, utilising a high power Moving Loop EM technique to detect conductive bodies to depths in excess of 500m below surface.
- A high power surface electromagnetic (EM) geophysical survey will commence this weekend on Aeris’ highly prospective Tritton tenement package
- The EM survey represents the initial phase of Aeris’ reinvigorated two-year $7.5M exploration commitment
- The EM survey will cover approximately 240km2 and is expected to be completed by June 2017.
Aeris Resources Limited (Aeris) (ASX: AIS) will this weekend commence a significant regional electromagnetic (EM) geophysical survey over the Tritton and Kurrajong volcanic massive sulphide (VMS) corridors within its Tritton tenement package in New South Wales.
The EM survey forms the first part of Aeris’s commitment to ramp-up exploration over the highly prospective Tritton tenement package (see ASX announcement – 28 July 2016), aimed at discovering large Tritton sized, plus 10 million tonne deposits.
The electromagnetic geophysical survey will utilise a high power Moving Loop EM (MLEM) technique to detect conductive bodies to depths in excess of 500m below surface.
Known copper rich mineralised systems within the Tritton tenement package are detectable via EM geophysical techniques. Recent trial test work over the Kurrajong prospect successfully detected the known mineralised system from 400m below surface.
Aeris holds a significant exploration portfolio in central New South Wales surrounding its Tritton Operations. The Tritton tenement package incorporates six exploration licences and three mining licences, totaling in excess of 1,800km2 over the highly prospective Tritton VMS field.
Within the Tritton tenement package copper mineralisation is interpreted to occur in close association with volcanic complexes, of which six major complexes have been identified to date: Tritton, Girilambone, Budgery, Kurrajong, Miandetta, and Exley. These major complexes occur within a sequence of sedimentary and volcanic rocks extending over a combined strike length of more than 100 kilometres (Figure 1).
These copper rich mineralised systems are characterised by clustered deposits of various sizes, ranging from sub 1 million tonnes to more than 20 million tonnes. Within the Tritton and Girilambone mafic complexes the clustered deposits are defined by one large deposit (Tritton and Murrawombie) with many smaller sub two million tonne deposits.
The exploration strategy employed to date has included electromagnetic geophysical survey techniques, which has been very effective in identifying and defining copper deposits within the tenement package, focusing on exploring within 250 metres from surface. This strategy has yielded more than 375,000 tonnes of copper to date and generated a significant number of exploration targets requiring follow up work (Figure 2).
There has been a long history of exploration over the Tritton tenement package, dating back to the discovery of the Murrawombie copper oxide deposit in the late 1800s. The Budgery deposit was discovered in the early 1900s and sporadic exploration continued over the following 50 years exploring for shallow copper oxide deposits.
Between 1960 and the early 1980s exploration efforts increased resulting in the discovery of the Girilambone North copper oxide deposits (North East, Larsens and Hartmans) and down dip extensions to the Murrawombie copper oxide resource. From the late 1980s through to the discovery of the Tritton deposit in 1995, exploration focused on the detection of leachable oxide copper resources for treatment through the Girilambone Copper Company solvent extraction electrowinning (SXEW) processing plant.
Following the discovery of the Tritton deposit, which is a sulphide orebody, the focus of exploration shifted from exploring for shallow oxide copper mineralisation to primary copper mineralisation. In the following years, extensions to the Budgery, Murrawombie, North East and Larsens deposits were identified in conjunction with the discovery of several new VMS mineralised systems, most notably Avoca Tank and the Kurrajong prospect.
Unlike other deposits discovered within the field, the Tritton deposit neither outcrops at surface nor contains an obvious geochemical response. The deposit was discovered via a surface EM geophysical survey which detected the upper extension of the deposit from 180m below surface (Figure 3).
Following the discovery of Tritton, electromagnetic surveys were continued over a three-year period covering a significant portion of the known Tritton and Kurrajong stratigraphic corridors. Depth of penetration by the EM geophysical surveys is thought to be in the order of 200m to 250m below surface and is representative of the EM technology available at that time. In many parts of the surveyed area conductive overburden hampered signal response and detection depths are likely to be less than 200m below surface in these areas. Recent technological advances in EM surveys now enables depth penetration of more than 500m.
Aeris is now planning to undertake an extensive regional high powered MLEM survey over a majority of the known Tritton and Kurrajong stratigraphic corridors covering approximately 240km2 (Figure 4) and utilising the latest available EM technology. The planned survey will total approximately 8,600 station readings and is expected to take approximately seven months to complete.
The EM survey method involves placing a large 300m by 300m wire loop along the ground which is charged with a high amperage low voltage current from a portable generator. An electromagnetic field is generated around the loop which is transmitted through the rocks in the vicinity of the loop. As the electromagnetic field passes through a conductive body (VMS deposit) it generates its own electromagnetic field which is detected by a sensor on surface once the transmitting current through the loop finishes. The sensor is able to detect electromagnetic fields at varying time based intervals which are used to interpret the size and depth of the conductive body(s). A reading is taken every 100m across strike and 300m along strike.