- Rockchip and soil sampling programmes completed at Core's Barrow Creek Project in the NT confirm the pegmatite field to be highly prospective for LCT type lithium mineralisation
- Core holds 2,500km2 of recently granted tenements in the Barrow Creek and Anningie Pegmatite Fields
- Barrow Creek has a long history of tin and tantalum production, similar to Core's Finniss Lithium Project (and Greenbushes)
- Core's soil sampling suggest a substantially larger footprint of lithium anomalism than depicted by historic pegmatite workings
- 13 potential pegmatite targets identified to date at Barrow Creek
- 3 targets rank as high priority for follow up drilling based on surface geochemistry and mapped scale
- Newly-defined Tesla lithium soil anomaly has 5 km of strike potential for pegmatites
- Barrow Creek is close to rail connection that links direct to Darwin Port
- Expands potential for Darwin to become long-term, central processing and transport hub for NT spodumene production for Core
Core's baseline exploration highlighted a new large prospect area called Tesla, where elevated lithium in soils form a 5 km long arcuate trend highlighting previously unmapped pegmatites.
At the Ringing Rocks Prospect a distinct lithium-in-soils anomaly is coincident with the outcrop position of two large pegmatite bodies, with surface expressions measuring 700m x 220m and 360m x 150m that may represent a single pegmatite body of approximately 1200m x 300m with surface rock chips assaying up to 0.6% Li2O.
On a local scale, rockchips and detailed mapping have confirmed the lithium potential of a number of historic prospects, including Jump Up, Ballace's Claim 1 & 2, Tabby Cat, Hugo Jack's, Boyce's Corner, Johannson's, Jody's, Slippery and Krakatoa.
Many other pegmatite occurrences were identified and investigated during the conduct of regional reconnaissance work.
Ringing Rocks Prospect
Ringing Rocks is characterised by significant coincident Li-Cs-Sn-Rb anomalism and moderate coincident Li-Ta-W anomalism in pegmatite rockchips and soil geochemistry (Figure 2). A distinct lithium-in-soils anomaly is coincident with the outcrop position of two large pegmatite bodies, with surface expressions measuring 700m x 220m and 360m x 150m. These can be interpolated under cover to be a single body of approximately 1200m x 300m (orange dashed line in Figure 2 in link below).
Peak rock chip results include 0.6% and 0.2% Li2O, while the average content is 151 ppm Li (or 324 ppm Li2O). This grade at surface is consistent with surface-weathered material observed by Core at the Finniss Project prior to discovery of the high grade Grants, BP33 and Far West lithium deposits with drilling. This result is a strong indication of lithium anomalism associated with the large pegmatite body.
Tesla is defined by a large (5km long, 1km wide), crescent shaped ENE to N trending Li-Cs-W-Sn-Rb (+Au-Ag-As-Cu-Pb) multi-element soil anomaly (Figure 1 and Figure 3 in link below). In particular, peak Li anomalism and coincident Cs-Sn-Rb anomalism defines a number of high priority target areas.
The largest of these targets is approximately 800m east of the Johannsons prospect, where pegmatite rock chips contain up to 362 ppm Li. The Tesla anomaly lies within or adjacent to the regional contact aureole of a large granite body. Early mapping shows that there is a pegmatite dyke swarm in the area.
Jump Up Prospect
A highly weathered NW-to NNW striking 500m-wide swarm of pegmatite dykes at the Jump Up prospect is anomalous in lithium with a maximum Li rock chip content of 312 ppm (Figure 4). Anomalous lithium in pegmatite rock chips is also coincident with a high lithium soil anomaly. Coincident multi-element anomalism includes good correlation of Li with Sn, Cs and Rb anomalism. This prospect has been worked historically for Sn and Ta, and the pegmatites disappear under cover in all directions.
Soil Surveys and Reconnaissance Mapping, EL 31058 Barrow Creek
Regional and prospect scale exploration over EL 31058 has included 2,342 soil samples, 404 rock chip samples and prospect mapping by Core's geologists. The Company has focussed its mapping and rock chip sampling efforts on historic pegmatite workings within the Barrow Creek Tin-Tantalum-Tungsten Field, but soil samples were collected over a much broader portion of the Project area (Figure 1).
Historical pegmatite prospects and mine areas considered prospective for Lithium-Caesium-Tantalum (L-C-T) Type pegmatite were geologically appraised and mapped, then sampled to determine representative whole rock geochemistry.
The main prospects targeted were Ringing Rocks, Jump Up, Ballace's Claim 1 & 2, Tabby Cat, Hugo Jack's, Boyce's Corner, Johannson's, Jody's, Slippery and Krakatoa (Figure 1). Many other pegmatite occurrences were also opportunistically investigated during the course of regional soil sampling.
Pegmatite from many of these prospects appear to be highly weathered, and it is likely that the pegmatites may be more widespread than currently revealed, under thin cover.
Soil sample grids generally utilised 200m x 400m or 400m x 400m spacing to establish regional coverage. Two historical prospects (Tabby Cat and Jump Up) were subject to more detailed 50m x 100m spaced grids (Figure 1).
Analysis of assay results from the current program suggests coincident soil/rockchip lithium anomalism and pathfinder element associations (Cs-Ta-W-Sn-Rb) at a number of prospects. Combined with mapping data, Core has prioritised the targets.
The most notable are Ringing Rocks, Jump Up and the newly discovered Tesla Prospects.
As with Greenbushes in WA and Core's Finniss Project in the Bynoe Pegmatite Field in the NT, the Barrow Creek Pegmatite Field has also had a long history of tin and tantalum mining prior to lithium mineralisation being recognised.
Core's Anningie and Barrow Creek Lithium Projects encompass five Exploration Licences covering over 2,500 square kilometres in and around the Anningie and Barrow Creek Tin Tantalum Pegmatite fields in the north Arunta Region of the NT, which are considered highly prospective for lithium (Figure 6).
Core believes there is an excellent fit between the lithium potential of Barrow Creek Pegmatite Field, direct rail link to Darwin Port and Core's objectives to make Darwin and Core's Finniss Lithium Project near Darwin a central processing and global transport hub for NT lithium and spodumene production as forecast lithium demand keeps growing (Figure 5 and Figure 6 in link below).
Core has the opportunity to commence drilling at the Barrow Creek Project in February-March 2018 once the current field season is completed at the Finniss Lithium Project.
With this in mind, Core has initiated a heritage clearance with the Aboriginal Areas Protection Authority (AAPA) to enable ground disturbing works at a number of the key prospects. Core would then expect to undertake RAB and RC drilling to test the highest priority targets, as outlined above.
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About Core Exploration Ltd
Core Exploration Ltd (ASX:CXO) aims to grow shareholder value through the exploration for and discovery of commercially robust base metal and uranium deposits in South Australia and the Northern Territory. Core Exploration's projects have been carefully acquired in geology which hosts world-class mines and within some of the most prospective geological terrains for base metals and uranium in Australia.
Core Exploration Ltd