Exploration of an area located approximately 90 km south-west of Coober Pedy was directed primarily at finding possible economic sedimentary uranium mineralisation within the subcropping Tertiary Garford Palaeochannel strata, as well as addressing...
Exploration of an area located approximately 90 km south-west of Coober Pedy was directed primarily at finding possible economic sedimentary uranium mineralisation within the subcropping Tertiary Garford Palaeochannel strata, as well as addressing the vein style gold potential within buried Archaean metamorphic basement, and also the diamond mineral potential of any Mesozoic kimberlitic intrusions. To begin with, a 1456.8 line km airborne electromagnetic and magnetic (TEMPEST) survey was flown for Tasman Resources in August 2006 by Fugro Airborne Surveys, over a block of tenements covering an inferred portion of the Garford Palaeochannel and its tributaries. The survey, which was flown along north-south lines at 1000 m line spacings and a flying height of 120 m, was aimed at more accurately defining the palaeochannel location within two blocks denoted Garford East and Garford West. Roughly 140 line km of EM was flown over EL 3712. Data from the survey was reprocessed for Tasman Resources by Resource Potentials, and a set of conductivity depth images (CDIs) prepared. The CDI at 40 m depth (? matching the prognosed base of the palaeochannel) suggests that the interpreted course of this palaeochannel, which is based mainly on the location of a string of low-lying salt lakes and the outcomes of limited stratigraphic drilling, is essentially correct. Interpretation of the EM data suggests that it trends in a NNW direction through EL 3712 before turning to the west. The survey also outlined the presence of some deeper palaeochannels, to a maximum depth of approximately 140 m, which, based on limited previous stratigraphic drilling data, are likely to be of Mesozoic to Permian in age. A west-trending remnant of one of these possibly lies beneath the western portion of EL 3712, as shown by the 70 m conductivity depth image. Later in 2006 an Aboriginal Heritage survey was conducted with the Antakirinja Native Title claimants over portions of the Garford Palaeochannel, including EL 3712, that had been selected for drilling along existing tracks and fence lines. However, issues arose with clearing the large number of clay pans present in the southern part of the licence area, that served to delay the drilling work approval process. Eventually it was permissible to start drilling, and two aircore holes for a total penetration of 69 m were completed during April 2008, with one being downhole gamma ray logged. This drilling outlined the western margin of the Garford Palaeochannel within EL 3712, and encountered a 7 m thickness of mostly oxidised Pidinga Formation fluvial sands in hole AC08G042. The geophysical logging of this hole did not record any significant radioactivity. After Flinders Mining farmed into the licence late in 2007 to look for diamonds, that company undertook the reprocessing and interpretation of all available regional aeromagnetic data to identify potential kimberlite targets for follow-up low level airborne magnetic (helimag) survey confirmation. A limited field reconnaissance of selected magnetic anomalies and surface loam sampling for kimberlite indicator minerals was made, and Flinders also collected and examined samples of regolith recovered from previous drillholes in the area. During June-July 2008 Tasman Resources performed calcrete soil geochemical sampling for gold (81 samples) on an 800 m x 800 m grid in the northern portion of the tenement area. No significant gold anomalism was detected, although the low level values returned did reflect the trend of recently discovered gold mineralisation found by the Southern Gold / Dominion Mining consortium on tenements lying just to the south. However, planned infill calcrete sampling and RAB drilling of any resultant discrete gold anomalies did not occur, for the reason given below. No further field work took place on EL 3712 during Year 3, before tenure was allowed to lapse, owing to the Commonwealth Department of Defence denying access for on-ground activities after April 2009 to a newly created restricted access zone of the Woomera Prohibited Area that covered the northern 70% of the licence.
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