On 21 October 2016, Northern Star entered a Joint Venture for Pioneer's Acra Gold Project, to fast track exploration. Read the Joint Venture announcement.
The Acra Project covers an area of 340 km² and is located 60 km north east of Kalgoorlie, WA.
The Acra Project has a 20 km long, north-west trending, structural corridor, which is evident in aeromagnetic data with elements observable in field mapping, and which is considered prospective for gold.
Physical gold has been recovered from small gold workings that date from the 1890s until WW2, and more recently from nugget patches that are still being located and worked. Most exploration undertaken from the early 1970s to the present, however, has focussed on identifying nickel mineralisation.
Drilling completed under Joint Venture
During the December 2017 quarter, an intensive aircore drilling campaign was undertaken at the Camel Dam (E27/548) prospect. In addition, resampling of Kalpini South diamond core and reinterpretation of the central Acra area was completed based, to a large extent, on litho-geochemical data from the Camel Dam aircore.
Although there were no significant gold intersections, in the context of a wide spaced, first-pass program to define stratigraphy and future targets, there were significant pathfinder element results. The fresh rock samples showed significantly elevated silver, arsenic, antimony, tellurium and tungsten in the south west of the area. Infill lines will be drilled in Q3 to follow up this anomalism.
- Infill aircore drilling planned for Camel Dam
- Follow up investigation of known workings for RC target evaluation
- Organisation of heritage surveys for northern Acra
- Drill hole planning for Jubilee, Mountain Maid and Iron Province
Background Acra - Pre-Joint Venture
An aeromagnetic survey over a large area of the Eastern Goldfields of Western Australia, including over the Company's Acra Project, was undertaken, with flight lines at 100m line spacing. This is a great improvement on the previously available data.
The Company engaged Dr David Isles (Southern Geoscience Consultants) to generate gold targets within an area of 2,200 km², including the Acra Gold Project, using the new aeromagnetic data. This highlighted 14 areas for further work.
Discovering Gold Deposits
Prior to Pioneer, the Acra Project area had been held predominantly by base metal, rather than gold, explorers. This is despite the number of historical gold workings, including the Jubilee Gift, Mountain Maid, Evelyn Gladys, King Edward and Josephine. The Project also has a number of gold nugget patches more recently identified by prospectors.
Over the past three years Pioneer has identified new, significant gold occurrences at Kalpini South, Jubilee East and Camelia South Prospects. These gold occurrences demonstrate the Project's gold endowment, and potential for the discovery of commercial deposits of gold within the 20 km long target zone.
Drilling Results confirm gold endowment
- KSRC004:10m at 6.38g/t from 61m
- KSRC004: 5m at 3.29g/t from 100m
- KSRC004: 8m at 1.45g/t from 85m
- KSRC005: 9m at 5.31g/t from 36m
- KSRC007: 13m at 3.31g/t from 94m
- KSRC007: 12m at 0.91g/t from 113m
- KSRC010: 3m at 5.44g/t from 128m
- KSRC010: 8m at 1.41g/t from 85m
- KSRC018: 18m at 1.98g/t from 97m
- KSRC021: 6m at 1.89g/t from 85m
- KSRC031: 9m at 6.17g/t from 60m
- KSRC032: 7m at 1.93g/t from 106m
- KSRCD024: 0.22m at 116.5g/t from 131m
- KSRCD025: 2.2m at 12.17g/t from 145.42m
- JERC002: 13m at 2.84g/t from 27m
- JERC003: 2m at 12.42g/t from 57m
- JERC007: 4m at 8.1g/t from 34m
- JERC010: 7m at 2.6g/t from 101m
- JERC038: 8m at 2.14g/t from 52m
Kalpini South Gold Deposit
Two reverse circulation drill holes completed at the Kalpini South Prospect confirmed the presence of reasonably shallow (from a depth of approximately 35m below surface) high grade supergene gold mineralisation, which is an excellent ore-style for open pit mining. This work was a precursor to further infill drilling, to enable a mineral resource to be estimated.
- KSRC031: 9m at 6.17g/t Au from 60m. Includes high grade lode gold - 2m at 20.7g/t - at a depth of 55m vertically below surface (see Figure 2); and
- KSRC032: 7m at 1.92g/t from 106m, including 3m at 3.56g/t, at a point 40m further ‘down-dip’ of the KSRC031 intersection.
The two RC drill holes were completed as step outs from the Kalpini South discovery holes KSRC004 (10m at 6.38g/t1) and KSRC005 (9m at 5.31g/t1).
Two RC holes were extended by diamond core drilling beneath the Kalpini South mineralisation.
The drill holes intersected the prospective andesitic volcanoclastic unit, with iron-arsenic sulphide nodules and layers at the targeted depth, however no significant gold assays were returned from the intervals submitted for assay. Geological structure information obtained from the core is helping to clarify the orientation of the known mineralisation.
New Target Generation Aircore Drilling Near Kalpini South and Deep River Areas
Traverses of aircore drill holes were completed over a number of geochemical and geophysical targets adjacent to the Kalpini South Prospect and, on a more regional basis, potential gold structures at the Deep River Area. Drill holes that return gold anomalies will be further delineated by aircore drilling before target confirmation by RC drilling is completed.
To date, approximately 15% of preliminary composite samples have been assayed. The balance, amounting to 784 composite and quality control samples, are currently being processed, with results expected by mid-February.
Three close spaced, parallel, mineralised structures have been recognised through mapping old workings and correlating this with historical shallow RAB drilling. In this area the main working is the Jubilee Gift South Mine which produced 1,738 tonne of ore grading 22.4g/t between 1899 and 19032.
Two RC holes drilled under the old workings returned anomalous values in preliminary composite assays.