The Jamieson project is located on unrestricted crown land within a geological province known as the Mt Useful Slate Belt. The region was founded on gold mining in the 1850s and a number of gold mines have operated or are currently in production in the region.
The project covers a “window” of Cambrian-aged volcanic rocks similar to the Mt Read Volcanics in western Tasmania, a world-class VHMS district. Typically, VHMS deposits occur in clusters and often define significant mining camps. Gold-rich VHMS deposits are particularly attractive targets given their high-grade and polymetallic nature. VHMS deposits are also attractive as exploration targets because they typically respond well to geophysical techniques, and in areas of little or no transported cover such as Jamieson, surface geochemistry and mapping are proven to be effective exploration methods.
Jamieson Project location plan
The most advanced prospect at Jamieson is the Hill 800 gold-copper prospect, a volcanic-hosted massive sulphide (VHMS) gold-copper system with many similarities in host rock, age and mineralisation style to the 1.5Moz Henty gold deposit in western Tasmania. There are also several other high-priority prospects at Jamieson including Hill 700, Mt Sunday Road and Rhyolite Creek, all of which have been identified from a combination of mapping, surface geochemistry and drilling.
Hill 800 was discovered by New Holland Mining NL in 1994, with drilling beneath outcropping gold-rich gossans identifying high-grade gold mineralisation. Carawine’s maiden diamond drilling program was completed in June 2018, with outstanding assay results exceeding the Company’s expectations of both the width and grade of gold mineralisation. A second phase of diamond drilling commenced at Hill 800 late in November 2018 and continued into 2019. To date the Company has completed 20 diamond drill holes for a total 4,059m. These programs have resulted in a significant, new interpretation of the geometry and orientation of the mineralised system with two distinct mineralised zones identified.
Hill 800 long section (+/- 60m), looking west with selected intervals labelled
The 800 Zone is an outcropping, coherent body of gold mineralisation characterised by intense silica-sericite-pyrite alteration. The zone has a north-northeast strike with a low dip to the south-southwest and is stacked against the steep, northeast trending Prelude Fault. The low-angle southwest dipping NSX Fault approximates the base of the 800 Zone. Preliminary interpretation suggests that this zone may have formed from the preferential replacement of a more permeable, volcaniclastic or brecciated layer of the host andesite sequence.
Significant intervals from the 800 Zone include:
(0.3g/t Au cut-off)
(1.0g/t Au cut-off)
(Downhole widths, for a full listing of intervals and further details see ASX announcement dated 27 May 2019.)
Approximate dimensions of the 800 Zone from drilling to date are 240m long x 80m wide x 50m high, with mineralisation closed by drilling and outcrop.
Hill 800 Plan View showing mineralised zones and drilling to date
The Main Zone sits below the 800 Zone and has a northeast strike, with a dip that rotates from steep in the south to moderate in the north. Importantly, the Main Zone increases in strike, width and grade at depth where it remains open.
The Main Zone comprises intense silica-sericite-pyrite-gold alteration similar in style to the 800 Zone mineralisation. This surrounds a stockwork of high-grade, centimetre-scale pyrite and chalcopyrite “Stringer” veins within altered and brecciated andesitic lava, with coarse free gold observed within veins and selvedges to these veins. A similar alteration assemblage is observed in the historic drill hole HED5, at least 350m down-dip from surface, providing confidence that the Main Zone alteration system extends at least to these depths.
Significant intervals from the Main Zone include:
The potential for very high grades within the Main Zone can also be seen in selected intervals above a 10g/t Au cut-off, as follows:
(10g/t Au cut-off)
(Downhole widths, for a full listing of intervals and further details see ASX announcements dated 27 May 2019.)
The Main Zone at Hill 800 is now defined over a 170m strike length, with an estimated true width ranging from 23m to 47m (average 35m), extending from surface to over 175m down-dip and remains open.
Hill 800 cross-section J-J' showing Main Zone (window +/- 10m)
Mineralisation Style and Metallurgy
Petrographic work indicates gold within the 800 Zone and silica-sericite-pyrite ("SSP") alteration of the Main Zone occurs within fractures and on the boundaries of pyrite grains. In the Stringer style in the Main Zone gold occurs as free, coarse grains. The Company plans to conduct a scoping-level metallurgical test program using core samples from the current drilling program.
Hill 800 mineralisation styles
Rhyolite Creek is located 5km to the south of Hill 800, discovered by previous explorers after targeting a linear magnetic anomaly in an area of surface gold-silver-base metal anomalism in surface geochemical samples. The discovery diamond core hole RCD001 intersected a zone of strong albite-chlorite-silica alteration and sulphide mineralisation, returning an interval of:
(Downhole widths, see the Company’s IPO Prospectus released on 12 December 2017 for details)
Zinc mineralisation was identified as being related to low-iron sphalerite and the footwall to this high-grade zone was reported as being strongly altered intermediate volcanics with significantly elevated zinc values over 52m downhole. Carawine believes the high-grade zinc-gold-silver horizon intersected in RCD001 is potentially associated with a VHMS seafloor or sub-seafloor deposit, occurring at the contact of intermediate and felsic volcanic sequences, with wide zones of footwall alteration and anomalism. Additional holes drilled by previous explorers have intersected this position over a strike length of about 400m, leaving it open along strike to the south.
Rhyolite Creek cross-section through RCD001 and RCD002
Sitting above, and either side of the zinc target is a large, anomalous gold-copper mineral system. This is defined by a surface gold soil anomaly above 0.1g/t gold over a 500m x 500m area, with sparse historic drilling returning highly encouraging assay results. Two areas have been initially been identified as requiring follow-work: the Zig Zag Track, 500m southwest of RCD001, and; the Jamieson River South area about 1km southeast of RCD001.
Rhyolite Creek prospect area with historic surface gold and copper anomalism and selected drill intervals
At the Zig Zag Track area, brecciated rhyolite and fragmented epiclastic units with massive sulphides adjacent to a “silica knob” outcrop in two holes yielded the following results (re-calculated from historic data):
At the Jamieson River South area Hole RCK002 intersected near surface gold mineralisation:
(downhole widths, for details refer to the Company’s IPO Prospectus released on 12 December 2017)
Both areas have had only limited follow-up drilling and as such are targets for future drilling.
The Hill 700 prospect, about 600m immediately south of Hill 800, is defined by a coherent 300m long surface gold anomaly above 25ppb Au, with individual samples above 100ppb Au (0.1g/t Au). Of a similar tenor is the Mt Sunday Road prospect where a surface gold anomaly over 500m above 50ppb Au has been defined from historic work (for details see the Company’s IPO Prospectus released on 12 December 2017).
These prospects demonstrate the potential for significant mineralisation beyond the excellent results from Hill 800 and support the Company’s belief that the Jamieson Project can deliver multiple mineral discoveries with further exploration. Evaluation of these prospects along with exploration program design and planning is in progress.
Jamieson Project regional prospects and surface geochemical coverage