Legacy Minerals Ltd (ASX:LGM)’s geophysics program has demonstrated a “significant” potential increase in the size of its gold system, situated within the Bauloora Low Sulphidation Epithermal Gold-Silver Project in New South Wales.
The company’s analysis of Advanced Spaceborne Thermal Emission (ASTER) hyperspectral data over the Bauloora Project defines a potential district-scale hydrothermal alteration footprint with anomalies across an area of 150 square kilometres.
Nine new ‘look-alike’ high-priority hydrothermal alteration anomalies were interpreted to be consistent with those of known gold-silver bearing low sulphidation epithermal veins mapped elsewhere at Bauloora within the 15 square-kilometres of the ‘Gold Zone’.
An extensive geochemical soil program is nearing completion across a number of these newly identified anomalies with results soon to be received.
Moving forward, these results will feed into the company’s target ranking over Bauloora and further help prioritise reconnaissance on-ground mapping.
Nine new “look-alikes”
Legacy technical director Thomas Wall said: “This is the first-time satellite spectral data has been acquired and interpreted over Bauloora and we are greatly impressed with the results.
“Legacy Minerals has employed modern ‘smarter’ exploration techniques across its tenure to screen the whole project systematically for unidentified opportunities and to focus on the key targets, reducing time and expenditure.
“The results from the ASTER data have supported the interpretation of the Bauloora epithermal project’s potential to host significant gold-silver epithermal deposits.
“Nine new ‘look-alike’ alteration anomalies are interpreted to be consistent with those over known Au-Ag bearing low sulphidation epithermal veins mapped elsewhere at Bauloora within the 15km2 ‘Gold Zone.
“The newly identified strong and coherent 48km2 propylitic signature situated in the centre of the 100% owned Legacy Minerals tenure, potentially demonstrates the effects of a large, buried magmatic system.
ASTER results
The 62 alteration anomalies were interpreted using a combination of alteration mineral distribution, abundance, composition, and crystallinity maps.
Anomalies are characterised by a summary alteration assemblage and have been attributed if they intersect iron oxide, silica and quartz responses, their proximity to or on strike from a major structure, and the host lithology.
Initial review shows ASTER alteration anomalies associated with known mineral occurrences are dominantly argillic, trending to phyllic, with strong muscovite-illite dominant assemblages.
Aside from the nine new ‘look-alikes’, a further twenty-seven anomalies that are consistent with signatures of low and intermediate sulphidation epithermal silver-gold mineral systems were identified.
Wall adds: “Encouragingly, broad windows of advanced argillic to argillic alteration associated with strong silica responses suggest areas of high-level, acid alteration that have never been visited or worked by previous explorers.
“The spectral response transitions to a dominant phyllic alteration in the east that possibly represents outflows from this central propylitic zone.
“This correlates with the extensive outcrops of sinter-related rocks and gold-silver bearing crustiform-colloform banded epithermal veins and hydrothermal breccias at the Breccia Sinter, Mee Mar and Quarry Prospects.
“Legacy Minerals will focus on incorporating this data with the other geoscientific datasets including geochemistry and geophysics to build a detailed system model prior to further on-ground field reconnaissance work.”
Advanced Spaceborne Thermal Emission workflow and outputs
About ASTER
The ASTER is one of five state-of-the-art instrument sensor systems operating on the Terra spacecraft.
ASTER utilises a unique combination of wide spectral coverage and high spatial resolution in the visible near-infrared through shortwave infrared to the thermal infrared regions.
It is a partnership between NASA, Japan's Ministry of Economy, Trade and Industry, the National Institute of Advanced Industrial Science and Technology in Japan, and Japan Space Systems.
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