The Jamieson Project is located on unrestricted crown land within the Mt Useful Slate Belt geological province. The region was founded on gold in the 1850s, with several historic and currently operating gold mines. Carawine is advancing two main prospect areas at the Jamieson Project: Hill 800 and Rhyolite Creek, and regionally searching for porphyry-related gold-copper mineralisation.
The project comprises granted exploration licences EL5523 and EL6622, covering Ordovician and Silurian aged sediments and Cambrian age volcanic rocks in the Mt Useful Slate Belt geological province. The focus of Carawine’s work is the “window” of Cambrian volcanic rocks known as the “Jamieson Volcanics”.
Jamieson Project location plan
The Mt Useful Slate Belt within the Melbourne Zone is located in the Lachlan Fold Belt of southeastern Australia. The Jamieson project covers a window of Cambrian-aged volcanic rocks known as the Jamieson Volcanics, which together with the Stavely Volcanics are the only Cambrian-aged, calc-alkaline volcanic belts in Victoria and therefore share similar settings for their formation and evolution. This link is further supported by tectonic reconstructions of eastern Gondwanaland which join the Mt Stavely Volcanics with the Jamieson Volcanics and the Mt Read Volcanics in Tasmania at the time of their formation/deposition (refer ASX announcement 16 October 2019).
The association of the Jamieson Volcanics with the Mt Stavely Volcanics and the Mt Read Volcanics (a well-established, major metallogenic region of Australia), is considered to significantly add to the prospectivity of Carawine’s Jamieson Project to host significant mineral deposits.
Lachlan Fold Belt, southeastern Australia
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 and confirming Hill 800 as the Company's most advanced prospect within the Jamieson Project.
To date the Company has completed a number of drilling campaigns at Hill 800, returning outstanding widths and grades of gold and copper mineralisation from intensely altered volcanics, including:
Hill 800 long projection in the plane of mineralisation, looking southeast.
Hill 800 cross section A-A'
The main zone of mineralisation has a northeast strike and a dip that rotates from steep in the south to moderate in the north. It is defined in drilling over a 170m strike length, with an estimated true width ranging from 23m to 47m (average 35m), extending from surface to over 250m down-dip and importantly, remains open down dip and to the south.
Mineralisation is associated with intense silica-sericite-pyrite (SSP) altered rhyodacite in a broad, lower-grade zone, and high-grade vein array shoots comprising chalcopyrite-pyrite-quartz veins and chalcopyrite-pyrite veinlets, with narrow sericite vein selvedges in chlorite-altered andesite. Recent drilling has defined one of these vein array shoots extending for at least 150m down-dip and remaining open, containing individual 1m samples ranging from 13.7g/t Au (HEC47) up to 148g/t Au (H8DD022) and 0.4% Cu (H8DD022) up to 2.1% Cu (HED1) - highlighting exceptionally high gold and copper grades and a nuggety nature (refer ASX announcement 14 May 2020).
Petrographic work indicates gold within the SSP alteration of the main zone occurs within fractures and on the boundaries of pyrite grains. In the stringer veins gold occurs as free, coarse grains.
Hill 800 mineralisation styles
Porphyry-Related Mineralisation and Targets
In September 2019 the Company established the potential for gold and copper mineralisation at its Hill 800 prospect to be related to a copper-gold porphyry system, based on an analysis of multi-element geochemical data and the recognition of an alteration pattern typical of porphyry mineral systems (refer ASX announcements 11 September and 16 October 2019). This followed the identification of several new prospects around Hill 800 with strong magmatic / porphyry geochemical signatures, and the recognition of two broad but distinct regional-scale magnetic anomalies at Hill 800 and Rhyolite Creek (refer ASX announcement 15 July 2019). The key outcomes of the study (completed by Dr. Scott Halley) linking the mineralisation at Hill 800 with a porphyry copper-gold source are as follows:
Schematic diagram showing the pathfinder geochemical and alteration patterns of a typical porphyry copper-gold mineral system and the relative location of Hill 800 (modified from Halley et.al, 2015), and relative locations of recent drill holes targeting the porphyry system.
The geochemical data also defines an alteration pattern at Hill 800 which is typical of porphyry mineral systems. Proximal to and associated with the main mineralised zone at Hill 800, the intense silica-sericite (paragonite)-pyrite alteration has a geochemical signature consistent with phyllic alteration. Associated with lower gold grades and more distal to the main mineralised zone, moderate sericite-chlorite alteration has a geochemical signature consistent with propylitic alteration. For further details of Dr Halley's findings refer to ASX announcement dated 11 September 2019.
The targeting of potential porphyry systems was immediately advanced with the completion of a detailed helicopter-borne magnetic and radiometric (“heli-mag”) geophysical survey over the Jamieson Volcanics in November 2019 (refer ASX announcement 3 December 2019). Typical copper-gold porphyries can display a magnetic “potassic zone” at the core of the system which can result in a magnetic response comprising a magnetic high surrounded by a magnetic low. Where the system is more complex, multiple intrusions and/or structural disruption can result in more complex magnetic responses. Magnetic anomaly complexes therefore provide excellent drill targets for copper-gold porphyry systems.
Detailed heli-mag survey image and contours of RTP magnetics and magnetic anomaly complex targets.
Analysis and 3D modelling of the heli-mag survey data identified fourteen anomalies around Hill 800 and the surrounding area, and two anomalies at Rhyolite Creek. From these, seven anomalies are prioritised for initial drill testing based on their size, depth, and location relative to known mineralisation and surface geochemical anomalism. These are anomalies M2 to M5 and M14 in the Hill 800 area, and M15 & M16 at Rhyolite Creek (refer ASX announcement 29 January 2020).
Drill testing of these anomalies has commenced, with the two drill holes completed to date (H8DD021 and H8DD023) intersecting intensely altered volcanics, likely potassium-feldspar veins and boxworks after sulphide in quartz veins, wide zones of elevated magnetite alteration and very high pathfinder assay values including molybdenum (Mo) (refer ASX announcements 30 March and 14 May 2020).
These results are considered encouraging in the context of the Company’s copper-gold porphyry exploration model, returning alteration assemblages and geochemical vectors consistent with the exploration model, increasing the potential for one of the remaining untested magnetic anomaly targets to be related to a mineralised copper-gold porphyry system.
3D magnetic inversion and anomaly model results in the Hill 800 area, looking towards the northeast
The Rhyolite Creek prospect is about five kilometres south of Hill 800 and comprises three distinct targets which require follow-up drilling: two potential large-tonnage, low-grade gold-copper targets and one seafloor-position VHMS gold and base-metal target. At surface, the prospect is defined by an extensive gold and copper soil anomaly in rhyolitic rocks and as with Hill 800, sits directly above a significant regionally anomalous magnetic high. This suggests, as with Hill 800, a potential magmatic input or control on the shallower, near-surface mineralisation.
Rhyolite Creek prospect area with historic surface gold and copper anomalism, selected drill intervals and magnetic anomaly targets
Historic drilling of the gold and copper soil anomaly is limited but has produced encouraging results including:
The mineralisation in these drill holes is reported as being associated with brecciated rhyolite and fragmented epiclastic rocks, and provides an excellent target for follow-up drilling to understand the style of mineralisation and explore for extensions and/or higher grades.
Stratigraphically below the main anomaly, historic drill hole RCD001 intersected a high grade zinc-gold-silver horizon at the contact between andesite (below) and rhyolite (above), representing a classic seafloor volcanogenic massive sulphide (VMS) mineralised position:
The footwall to this high-grade zone was reported as being strongly altered intermediate volcanics, with significantly elevated zinc values over more than 50m downhole width, containing several individual 1m assay values of 1.1% to 2.5% Zn, e.g. 59m @ 0.5% Zn from 228m (refer ASX announcement 12 December 2017).
Rhyolite Creek cross-section through RCD001 and RCD002
Follow-up drilling by previous explorers intersected the horizon up to 400m to the north of RCD001, intersecting significant zinc anomalism (e.g. 4.2m @ 2.2% Zn, 0.55g/t Au, 9.75g/t Ag in drill hole RCD004) but without repeating the high grades in RCD001 suggesting the potential for a large system. The target VMS horizon remains open to the south, with potential for the mineralised horizon to thicken either there, or within the current drill pattern to the north.
Both areas have had only limited follow-up drilling and as such are targets for drill testing.
Please note: these pages include information that relates to Exploration Results prepared and first disclosed under the JORC Code (2012). The information was extracted from the Company’s previous ASX Announcements which can be viewed in the Investor Information & News section of this website by clicking here.