Earaheedy Project

Location of Castle’s Earaheedy Project exploration licence applications
Location of the Withnell exploration licence application and geology (after GSWA)
Castle’s Tableland applications in the southeast margin of the Earaheedy Basin

Castle Minerals Limited has applied for seven exploration licences (870.5km²) covering prospective lithologies in the Earaheedy Basin which abuts the north-eastern margins of the Archaean Yilgarn block, Western Australia.

The five applications at the western end of the basin, which are situated between 40km and 100km east of the De Grussa copper mine and ~120km north of Wiluna, have been grouped into the “Terra Rossa” and the “Withnell” sub-projects. The two applications located in the southeast margin of the basin have been grouped into the “Tableland” sub-project.

The applications are consistent with Castle’s strategy of positioning itself at low-cost in regions prospective for base and precious metals and which have generally not received much recent attention or the benefit of the latest available exploration tools.

The Withnell application area is immediately north of and, in part, appears to be along strike from the recent Chinook – Magazine zinc-lead discovery (Refer Rumble Resources Limited ASX:RTR releases 8 April 2021 and 19 April 2021). An initial appraisal of historical reports and 1:100,000 scale GSWA mapping covering the Withnell application area indicates that the west extremity and southern portion of the licence most likely encompass the Frere Iron Formation and its unconformable contact with the underlying, prospective Sweetwaters Well member of the Yelma Formation. Importantly, much of the historical exploration in the region occurred in the 1990s with a number of prospects delineated within the Sweetwater Well and overlying Frere Formation. The Withnell application was made on the basis that one such prospect, the Sioux prospect, appears to occur within the Withnell licence area. The exact location and nature of the Sioux prospect has yet to be verified in the field.

The four contiguous Terra Rossa applications are grouped immediately to the east of the Thaduna copper deposit.

The largely unexplored Tableland applications encompass Yelma and Frere Formation stratigraphic units and their associated unconformity which has been shown elsewhere in the basin to be prospective for both Mississippi Valley and SEDEX style base and precious metals mineralisation. Importantly, GSWA regional aeromagnetic data indicates a series of north-south and subsidiary northwest trending structures traversing the Tableland areas. These structures appear to be deep-seated and traceable through both the Archean and Paleoproterozoic terranes and may have created a viable framework for the migration of mineralised brines and hydrothermal fluids during early basin formation.

Castle has commenced the collation and critical review of publicly available historical data and is also evaluating work being undertaken by other companies now active in the region as a prelude to determining the prospectivity of its licence areas and the logical way forward for each of the licences.

The Company particularly notes that the Withnell application is adjacent to licences hosting the recent Chinook – Magazine zinc-lead discovery (refer Rumble Resources Limited ASX:RTR releases 8 April 2021 and 19 April 2021) (“Rumble”).

All seven licence applications are at an early stage of the grant process and there is no certainty that the applications will be granted.

Table 1: Summary of Earaheedy Project Exploration Licence applications
Project Licence Blocks Area (km²) Mineral Field
Withnell ELA69/3860 65 200 Warburton
Terra Rossa ELA52/3927 70 218 Peak Hill
Terra Rossa East ELA52/3930 34 106 Peak Hill
Terra Rossa South ELA52/3931 39 121 Peak Hill
Marymia ELA52/3928 70 218 Peak Hill
Tableland ELA38/3641 18 6 Mt Margaret
Tableland ELA38/3641 3 1 Mt Margaret

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