Southern Hemisphere geophysics scores big Chilean copper target
The large low-resistivity anomaly identified from the MT survey is in addition to the recent reveal of a possible large copper-gold porphyry deposit at the company's Curiosity target, which was also identified from the MT survey. Both targets are part of Southern Hemisphere's flagship Llahuin copper-gold-molybdenum project, 350 kilometres north of Santiago in Chile.
Management is particularly interested in a deep zone of low-resistivity defined by 3D inversion modelling of the MT dataset at Ferro West, its newly named target.
It subjected the area to a detailed surface geological mapping program, which identified black copper wad oxides at surface.
The company believes this is a positive sign as black oxides were also seen at Ferro South during drill pad construction prior to the Ferro South extension discovery from a 2024 drilling program.
Management believes testing the newly defined target will require about six holes to be hammered into its diameter.
Previous management plunged a reverse circulation drill hole into the ground that extended into the low resistivity target, intersecting low-grade copper.
The company says a sub-optimal drill technique was employed on the historic hole, which is now being evaluated for further drilling to target a deeper extension through the target using a diamond drill rig.
Southern Hemisphere expects to make significant time and cost savings if it utilises the existing hole, which has already been drilled to 190m depth.
An MT survey is an electromagnetic geophysical method for measuring the electrical resistivity of the earth's sub-surface. The surveys were used to identify some world-class copper porphyry deposits in the region, including Atex Resources' 61-square-kilometre Valeriano deposit in northern Chile.
Both 2D and 3D inversion models for the distribution of resistivity in the target's area generally indicate zones of moderate to low resistivity.
Low resistivity indicates that a material readily allows the flow of electric current, meaning the ground material has high conductivity and may represent conductive ore deposits.
Deeper zones of moderate to low resistivity may indicate the presence of conductive metallic sulphide mineralisation.
The company used a portable X-ray fluorescence (pXRF) technique to confirm copper oxides in the surface black material. The technology beams X-rays at a sample to interact with its atoms, causing the atoms to emit characteristic X-rays.
By analysing the X-rays emitted, it is possible to identify the elements present and their estimated concentration levels.
The pXRF works fast and can provide results quickly, which is a great advantage when working out in the field.
The historical drill pad where the black copper oxides were previously identified has not been used and could be utilised for part of the planned drilling program.
Management is seeking quotes for the upcoming campaign from experienced companies with a demonstrated history of drilling to depths of 2km to test the new target and the deeper Curiosity copper-gold target.
It says the configuration of the Curiosity MT target is remarkably similar to an MT target at the large Valeriano porphyry copper-gold deposit.
The Curiosity target is within the Southern Porphyry prospect. The target is 550m below the previous Santa Maria gold workings and is about 1km in diameter and up to 2km deep.
The Curiosity target is supported by a soil geochemistry anomaly at surface and two shallow drill holes that produced drill intervals of 164m at 0.16 per cent copper equivalent from 2m and 106m running 0.13 per cent copper equivalent from 28m.
A 2m slice grading 1.45 per cent copper equivalent from 168m provides further encouragement that Southern Hemisphere may be onto something.
Southern Hemisphere's recent drilling program has sought to add scale to a copper resource that consists of 169 million tonnes grading 0.4 per cent copper equivalent for 680,000t of copper equivalent material, which was measured under the 2004 JORC guidelines.
Results from a recent program comprised a large 128m hit stretching from a depth of 16m, which returned a grade of 0.41 per cent copper equivalent ending in mineralisation. This included a 32m section going 0.57 per cent copper equivalent from 66m.
Southern Hemisphere plans to achieve an updated 2012 JORC-compliant mineral resource this year. With many thick intervals from surface or shallow depths, the company feels it has a compelling opportunity to bolster the resource with near-surface tonnes and provide for a potential open pit operation at the project.
The use of geophysics is proving to be a positive move for Southern Hemisphere as it kicks up newly identified prospective targets that provide the opportunity for the company to potentially grow Llahuin into a significant project.
Is your ASX-listed company doing something interesting? Contact:
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