Kalgoorlie Gold Mining is getting set to run high-resolution geophysics across about 9.5 square kilometres enclosing prospective sites at its Pinjin gold project, 140 kilometres north-northeast of Kalgoorlie.
The company plans to launch its sub-audio magnetic (SAM) survey in mid-June to better define sub-surface geological structures and mineralised zones that often escape detection or effective resolution, due mainly to extensive surface cover.
Surface cover in the Pinjin area includes a mix of clays, sands, small pebbles and other weathering and erosion debris. A lot of transported cover material – or regolith - can be hard for traditional survey methods to penetrate, presenting a host of physical, geological and chronological puzzles for the mineral explorer to unravel.
KalGold hopes its SAM survey will help resolve some of the puzzle by measuring total magnetic intensity and magnetometric conductivity through the cover, which can then be integrated into maps of the underlying rock types, their alteration and structural trends.
The SAM survey appeals because it can provide valuable information about the regolith cover and the underlying weathered and fresh rock. It is an active-source geophysical method that channels current into conductive sub-surface features, generating an electromagnetic field that is detected at the surface.
It produces high-resolution images of the conductivity structure in the near-surface regolith and bedrock that can be useful for prospect-scale mineral exploration.
The SAM transmitter is a time-variant electrical source using a frequency from 1 to 20 Hertz, which injects 2 to 10 amps of current into the ground over a generally small survey area.
SAM surveys can offer a high degree of spatial resolution and depth penetration, enabling detection of hidden shear zones, alteration halos and sulphide accumulations.
The method is well-suited to picking out gold mineralised zones similar to those at KalGold’s Lighthorse, Kirgella Gift and Providence gold deposits at Pinjin, where the company aims to identify more shear-hosted gold mineralisation.
The technique may also help refine interpretations of near-surface gold anomalism identified in the company’s previous and future shallow scout drilling.
KalGold also intends to run the survey over its T12 and T15 prospects, which feature extensive gold anomalous alteration footprints, and also exhibit gold mineralisation below gold-bearing palaeochannel sediments.
The proposed new SAM survey runs over T12 and T15 will produce the first data since Newmont and Renaissance Minerals explored the two areas about 15 years ago.
Both prospects lie 1.7km north and 1.5km south respectively from KalGold’s Kirgella Gift and Providence deposits, along a more than 500-metre-wide trend highlighted by magnetics data. The trend forms a key element of the broad Laverton Tectonic Zone.
KalGold managing director Matt Painter said: “The planned SAM survey is highly complementary to our systematic exploration strategy at Pinjin. By leveraging high-resolution geophysics to help define gold mineralisation and anomalism trends, we aim to generate new, high-confidence drill targets and unlock the full potential of our underexplored tenement package.”
The Laverton Tectonic Zone is about 250km long and is a significant gold-bearing, crustal-scale tectonic structure, which is a major conduit for gold-bearing fluids.
It hosts more than 20 significant gold deposits in a prolific gold district that has seen more than 30 million ounces in historical production, reserves and resources and it remains endowed with extensive exploration potential.
Significant LTZ-hosted gold projects include the world-class 10.3-million-ounce Sunrise Dam, the 11.8M-ounce Wallaby and the 5.8M-ounce Granny Smith deposits, as well as deposits such as Matsa Resources’ Red October and Ramelius Resources’ 1.4M-ounce Rebecca resource.
Rebecca sits about 21km south of KalGold’s combined 76,400-ounce Kirgella Gift/Providence resources.
KalGold expects the geophysical survey to provide new details that will guide more effective and focused exploration across the company’s tenure in a prospective but largely underexplored part of the southern zone.
Once completed, the processed and interpreted survey data will likely influence the company’s future priorities and designs for its next round of drilling, slated for later this year.
Is your ASX-listed company doing something interesting? Contact: matt.birney@businessnews.com.au
By Doug Bright
