Burra Projects- South Australia

Burra Projects- South Australia

The Burra Projects, covering 970 sq km comprising three project areas in South Australia. Ausmex is targeting IOCG or porphyry copper-gold targets, Burra-style base metal deposits and vein-style gold deposits at its projects near Burra in South Australia.

Ausmex has two projects, Mt Bryan and World’s End, on strike from the famous Monster Mine which produced 10% of the world’s copper in 1851 and which became a copper boomtown and largest inland population centre in Australia at that time. Ausmex’s third South Australian project, Redbanks, is set on the same geological unit as the prolific Mongolata goldfield north-east of Burra with added prospectivity for phosphate.These areas contain structural features with potential for

These areas contain structural features with potential for mineralization produced by transportation of deeply sourced fluids typical of porphyry or IOCG style deposits and are also prospective for Burra-style base metal deposits and vein style gold deposits.

Mt Bryan Copper Gold Project Block

The Mt Bryan Block is about 12 km northwest of the township of Burra and in the same geological trend as the Monster Mine at Burra. The Burra region is reported to have historically produced 86,000 tonnes of copper in its history and produced 40,000 tonnes in the period 1969 to 1981 in its ‘second life’. The Monster Mine at Burra is reported to have produced 10% of the world’s copper supply in 1851 (ref. Copper Mining and Treatment in South Australia – Ken F. Bampton, Consultant Geologist).

The Monster Mine ore zone is hosted in a fractured and brecciated zone within the Skilogalee Dolomite member of the Adelaidean Burra Group of Neoproterozoic age. The geological unit consists of limestone, dolomite and dolomitic siltstone of which the Skilogalee dolomite forms the country rock. A group of volcanic porphyry dykes located within the current pit environment are interpreted as a possible source of the copper. Significantly Phoenix Copper in its Burra Group – Annual Technical Report 2009 to 2010 stated: “A small lens of sulphide- mineralized intrusive feldspar porphyry was exposed in the open pit. It is possible that this exposure represents an offshoot from a larger igneous body at depth, and if such a body is present it may well be the host of the primary mineralization from which the oxide bodies have been derived.”

Ausmex wishes to pursue a target based on a north south structural feature containing the magnetic high which is a proposed hidden porphyry model and deep seated intrusive.

Redbanks Gold Phosphate Project Block

The Redbanks Block is about 10 km east of the township of Burra adjoining the Mongolata gold field hosted within the Cox Sandstone unit. The Cox Sandstone unit which extends south across Redbanks project area is the host to the large number of Mongolata gold deposits (see diagram below).

Former tenement holder Phoenix Copper summarised the Mongolata goldfield geological model to the north of the Redbanks Block in its Burra Group- Annual Technical Report 2009 to 2010 which stated: 49 “The host formation for mineralisation in the goldfield is a feldspathic, sandy siltstone named the Cox Sandstone, belonging to the Neoproterozoic Tarcowie Siltstone Formation; which overlies the Tapley Hill Formation units. The Cox Sandstone outcrops for approximately 12 kilometres along the eastern scarp of the Mt Lofty Ranges, with most of the gold developments concentrated within a 4- kilometre extent within this outcrop. These formations are developed within a deformed (Delamerian orogeny) Neoproterozoic basin of greenschist facies metamorphism termed the Nackara Arc, this basin joins the larger Adelaide Geosyncline to the west. Gold mineralisation is hosted in a network of cross-cutting quartz-veins, with large flat-lying veins recording the highest gold production. Exceptional high-grade coarse-grained gold occurs at the intersection of these lodes with steeply-dipping veins. Mineralisation within veins and breccias outward into the hanging or foot-walls of the Cox Sandstone is also reported. The interface between the Cox Sandstone and the underlying laminated metasiltstone is characterised by the bedding- parallel “Limonite Lode”.” (p16-17).

A typical model cross section for the significant Cox Sandstone Unit hosting these gold zones is shown above. Ausmex wishes to pursue a target based on potential for similar mineralization to that of the Mongolata Goldfield just to the north of the EL. This model is underscored by the Redbanks Block outline map above providing potential along the Cox Sandstone trendline for many gold targets given the multitude of gold deposits within the Cox Sandstone unit to the north.

In addition, given the existence of phosphate deposits to the south of the Redbanks Block, a phosphate prospectivity zone has been highlighted by past explorers including Phoenix Copper shown by the phosphate trend line in the diagram above. Ausmex will conduct a dual gold and phosphate exploration program in EL 5881 (SA).

World’s End Copper Gold Project Block

The World’s End Block area is about 15 km south east of the township of Burra and in the same geological trend as the Monster Mine at Burra. As referred to earlier the 50 Monster Mine ore zone is hosted in a fractured and brecciated zone within the Skilogalee Dolomite member of the Adelaidean Burra Group of Neoproterozoic age. The geological unit consists of limestone, dolomite and dolomitic siltstone of which the Skilogalee dolomite forms the country rock. Petrographic analysis shows a series of tuffaceous and volcaniclastic beds within the dolomite sequence without any large body of intrusives.

The World’s End prospect area is an interesting prospect as it lies in a trend zone having a number of common structural and geological features within the Skilogallee Dolomite that hosts the Monster Mine and thus is a prime drilling target once confirmatory work is done to validate the targets.