The Spinifex Well Project comprises four tenements (E37/793, E37/749, E37/760, and E37/800) and is located in the Mount Malcolm District of the Mount Margaret Mineral Field in WA, about 70km north of Leonora and 250km north of Kalgoorlie. Access from Leonora is by way of the major Leonora-Nambi main road.
The Project covers a substantial portion of a large magnetic granodiorite complex on the eastern side of the Bundarra Batholith. Previous explorers have identified a number of gold anomalies hosted within quartz veins. However, these anomalies have only been tested with limited drilling; insufficient to evaluate their potential.
Regional Geology
The regional geological setting of the Spinifex Well Project area is dominated by the Bundarra Batholith, a large intrusive granitoid which is located between the Keith Kilkenny and Celia Lineaments, at the southern end of the Yandal Greenstone Belt.
The batholith is generally granodioritic. However, various younger phases have been identified from geophysical (magnetic) data. The Bundarra Batholith and its enclosed dioritic complexes contain a number of gold bearing quartz lode systems.
Project Geology
The Spinifex Well Project is extensively soil covered with outcrop confined to the northern, central, and southern parts of the tenement area where biotite monzogranite and synogranite/alkali feldspar granites are exposed. Therefore, the bulk of any potential gold mineralisation has been effectively masked by alluvial/colluvial cover.
Geophysical (magnetic) interpretation has identified a number of areas within the prospect. It is believed that these areas may be prospective for Bronzewing-style gold mineralisation. These areas include a greenstone raft about 3km east of Stack Well, in the northern part of E37/749. Ferruginous quartz veining and stockworks prospective for gold mineralisation have been identified in the Spinifex Well/Three Dagoes Well areas.
Exploration by Exploration Research (Australia) Pty Ltd and Placer Exploration Ltd has identified a number of gold bearing quartz sulphide hematite vein systems associated with the Bundarra Batholith within Fairstar's tenement area.
An extensive, but generally thin, cover of sand, soil, and hardpan effectively masks several lineaments which have been inferred from geophysical evidence. These lineaments are believed to provide favourable sites for bulk tonnage gold bearing quartz vein stockwork targets.
Previous explorers have identified several gold anomalies, which as yet have not been drill tested. These anomalies will, if warranted by further investigation, be the subject of a reconnaissance drilling program. A study of aeromagnetic data by a geophysical consultant together with the results of previous exploration indicates that the Fairstar tenements are intersected by major structural lineaments and contact zones which may provide favourable sites for gold mineralisation.
In addition, the indicated presence of remnant greenstone rafts and felsic volcanic (porphyry) bodies in contact with granodiorite and associated auriferous quartz vein stockworks, quartz iron gossans and gold bearing sulphides, indicate the prospectivity of the Spinifex Well Project.
Spinifex Well Exploration 2006-2007
Exploration work for the Project area in 2006-07 included: study of earlier explorers' work, reconnaissance field visits, study of airborne magnetic and radiometric data, high resolution digital photography for geological and regolith mapping, and rock chip sampling.
The field reconnaissance has identified presence of at least two sub-parallel porphyry zones, each having a strike length of between 15km to 20km, and up to 100m in width in the area.
Additionally, gold mineralised quartz vein stockworks up to 2m wide, associated with gold bearing sulphides were identified in rock chip samples taken from gossanous quartz vein material. These samples returned values of up to 114g/t gold in narrow quartz veins, hosted within porphyries intruding a 50m shear zone. To date, none of these zones has been investigated by follow up exploration.
In November 2006, Fairstar purchased the multi-client airborne geophysical data for the Spinifex Well tenements, and geophysical consultants Cowan Geodata Services (CGS) were contracted to undertake data analysis and identify potential targets and preliminary depth estimates for exploration.
CGS produced a 'terraced total magnetic intensity map' of the area that assisted in understanding the geological intricacies of the Project area, which was hitherto unknown. In addition to the known targets, the following targets have been suggested for drill testing:
Possible Breccia Pipe Target
This target was described as a three dimensional negative magnetic anomaly superimposed on a series of NW linear magnetic lows. CGS suggested this anomaly could possibly be a breccia pipe or an intrusive complex with evidence of alteration, and that the entire zone may be prospective.
The magnetic signature of the target zone is composite and both curvilinear and more three dimensional anomalies. The strongly negative anomaly has similarities to Mount Leyshon in Queensland and Blue Rose, north of the Anambra granite in South Australia, and is considered to be a high priority target
Fracture System Targets: Targets 1 to 4
Four clearly anomalous fracture system targets have been selected by CGS. These are either in areas of prominent reversely magnetised anomalies or defined areas of magnetic lows and are associated with clear geologic offsets, which could provide potential conduits to solutions emanating from late granitoid intrusives of the Late Archaean. CGS has selected the intersections of fractures 2 and 3 as site for immediate follow up ground prospecting.
Late Stage Plug Targets
The aeromagnetic data has highlighted a number of discrete ovoid anomalies interpreted by CGS as probable late synorogenic intrusive phases or plugs. These ovoid features have both positive and negative polarity suggesting different generations of intrusives. Plug targets 1 and 2 have negative polarity and are relatively large. All the plug type targets will be inspected in the field during the third quarter of 2007.
The bulk of the reported gold occurrences in the Project area lie within shear zones. These have been termed the "West" and "East" Spinifex Shears respectively.
The sheared margins to the Bundarra Batholith are litho-structural zones. To ascertain the potential of these sheared zones for gold mineralisation a detailed field examination before decision for drill testing is a must.
The strong east-west linear features shown on Figure 9 are Proterozoic-age basic dykes which are irrelevant in respect of gold mineralisation.
The geophysical study together with field observations by both Fairstar and others confirm the presence of at least two sub-parallel porphyry horizons, associated contact zones and major lineaments, within the tenement area; all suggestive of Project areas' high potential for gold mineralisation. The strike length of each porphyry horizon is as much as 20 km and between 50 - 100 m in width. In addition, the contact zone between magnetic granodiorite and the non-magnetic batholith is a proven host for gold mineralisation in the area, e.g. the nearby Tarmoola Mine with resource of ~ 4 million ounces.
Outlook
During the third quarter of 2007 geological and regolith mapping of the Project tenements is scheduled. Based on this mapping exercise further exploration will be planned.
