An area centred approximately 130 km north-northwest of Kimba has been explored for possible economic primary uranium mineralisation, where the principal target is the igneous rock succession of Mesoproterozoic Gawler Range Volcanics (GRV) and...
An area centred approximately 130 km north-northwest of Kimba has been explored for possible economic primary uranium mineralisation, where the principal target is the igneous rock succession of Mesoproterozoic Gawler Range Volcanics (GRV) and co-magmatic Hiltaba intrusions, which the exploration model which was being followed inferred might contain volcanic-hosted uranium deposits associated with a high-level Hiltaba granite stock intruded into the base of the massive upper GRV felsic lava pile. The Tanner Dam Project acreage was centred about a large (12 km x 7 km), oval shaped, magnetic and gravity low feature that is crossed by a series of prominent NW and NE-trending fracture zones, broadly coincident with several circular strong magnetic low features and complexes (Rankin, 1997). During the first licence year, work undertaken involved: - a review of historical geological, geochemical and geophysical public domain data; - the definition of drill targets based on the Streltsovska uranium model; - the preparation and presentation to DMITRE of an application for the grant of PACE Initiative drilling project subsidy funds; - liaison with Pastoral Lease holders, plus the submission of relevant statutory forms; and - obtaining a Work Area Environmental and Heritage Clearance from the Gawler Ranges Native Title Claimant Group, to allow for the conduct of a proposed reverse circulation (RC) drilling programme. The licensee's review of geological and exploration data previously obtained from the GRV and at Tanner Dam established that several key ingredients of volcanic-hosted uranium systems, known from studies of major deposits elsewhere, are also present there. Globally, it has been demonstrated that uranium mineralisation may occur in felsic to intermediate volcanic and volcaniclastic rocks associated with calderas and mid- to high level intrusive plutonic bodies. In particular, the combination of fluorine- and uranium-enriched magmas typical of A-type melts, coincident with a hydrothermal fluid driver, are essential components of such mineralised systems. In early 2012, a proposal for the grant of SA Government partial subsidy funding for mineral exploratory drilling, as part of Year 7 of the PACE Initiative Theme 2 programme – “Drilling Collaboration between DMITRE and Industry”, was submitted to DMITRE. This successful proposal, which became approved drilling project DPY7-11, was awarded a PACE funds grant of up to $40,000 to assist with completing two 350 m deep RC or rotary mud drillholes to test selected geophysical anomalies located within the Tanner Dam "granite" in positions where they are cross-cut by prominent north-west trending structures. During the second licence year, field-based exploration activities on EL 5104 were limited to one drillhole targeted on a magnetic anomaly interpreted from an historic magnetic survey. This initial PACE subsidised hole, vertical hole 13RSDRC01, was drilled by Renaissance Uranium during early June 2013 to a total depth of 220 m, to test the NW margin of the Tanner Dam granite intrusive complex at a place where a discrete intense magnetic high had been recognised lying along the granite - dacite stratigraphic contact. The company's examination of semi-detailed residual gravity data for this proposed drillsite had concluded that it may lie peripheral to apophyses of granite/rhyolite intruded high into the basal strata of the Yardea Dacite. The target magnetic anomaly was interpreted as possibly representing a contact zone where high magnetite concentrations have arisen through intense metasomatism, a process which could also have given rise to the leaching and recycling of uranium from GRV and/or Hiltaba granite source rocks into spatially coincident structural and dilational traps (veins, stockworks and breccias). 13RSDRC01 encountered a variably magnetic sequence of dacite and lesser rhyodacite that is weakly anomalous in uranium over the depth interval 155 to 165 m, with the best assay result obtained from assaying 5 m composite 1-metre drill cuttings samples being 5 m @ 8.25 ppm U from the depth interval 160–165 m. This particular sample intercept came from a non magnetic, base metal - poor rhyodacite. A 5 m wide zone of elevated silver-lead-zinc base metal values was recorded from 195-200 m depth. No further work on the Sherry Dam target was considered necessary. Because of the drastically falling market price of uranium in 2013, and the lack of significant grade uranium intercepts made in hole 13RSDRC01, Renascor Resources later decided to allow tenure of EL 5104 to lapse at the end of its second year.
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