Within the subject south-eastern Eucla Basin tenements, Iluka's ongoing exploration has targeted the Tertiary-aged beach sands deposited during the five marine incursions that occurred from the Middle Eocene to the Pliocene, with a focus on...
Within the subject south-eastern Eucla Basin tenements, Iluka's ongoing exploration has targeted the Tertiary-aged beach sands deposited during the five marine incursions that occurred from the Middle Eocene to the Pliocene, with a focus on exploring for zircon rich heavy mineral (HM) sand deposits. Iluka has also commenced uranium exploration within these tenements, initially by investigating the Neogene Narlaby Palaeochannel in an attempt to locate areas having favourable sediment and redox conditions for uranium deposition to occur. During the 2007 to 2008 reporting period, one uranium and three HM drill programmes were undertaken across ELs 3163, 3201, 3203 and 3267. Regional exploration drill holes were typically drilled 400 m apart along traverses, and were later infill drilled at 200 m or 100 m hole spacings along the traverse lines if encouraging geological settings or anomalous heavy mineral content (i.e. >0.5% HM visual estimate) were intersected. The first HM programme took place completely within EL 3267, for a total of 62 holes and 1342.6 m of penetration along 4 traverses. The drilling intersected a preserved beach environment abutting a granitic headland. Mineralisation found there has been named the Dromedary prospect, and it contains HM grades of up to 14.6%. The best intercept made so far at this discovery occurs on traverse 1, of 10% HM over 3 m at a depth of 25.5 m. Bulk mineralogical analysis indicates that the HM assemblage contains approximately 17% zircon. Particle size analysis for bulk samples of the Dromedary HM mineralisation and host sediments revealed that both are fine to medium grained, predominantly in the 106-150 micrometer range. All of the HM grain sizes are within the above 53 ?m range, making their separation and processing compatible with Iluka’s current methods. The second HM drill programme took place across ELs 3201, 3203 and 3163. A total of 159 holes for 5198.2 m were drilled across 15 traverses, some of which were infill holes to previous drill placements. This programme encountered a mixture of interpreted estuarine, dunal and beach sands. The mineralisation intersected during this program has HM grades up to 6.7%, warranting follow-up drilling. The third HM drilling programme took place on the northern margin of EL 3267, as part of a drilling campaign targeting other Iluka tenements to the north-west. 18 holes for 445.5 m were completed within EL 3267 along one traverse only. The sands encountered were terrestrial and strongly indurated, and were mostly barren with respect to HM. The maximum HM grade encountered was an estimated 0.6%. The uranium exploration drilling occurred mostly within EL 3267, but some also occurred to the north on EL 3322. A total of 39 holes for 3469 m were drilled along 7 traverses. An airborne EM survey (Tempest) was undertaken beforehand, during March 2008, to assist in targeting for this programme. The drillholes encountered mostly palaeochannel sediments overlain by lacustrine sands, with some dunal sands also present. The sediments' uranium content is yet to be determined by an external laboratory. Some positive indications were given by readings obtained from the scintillometer and spectrometer used on site. Only trace HM levels were encountered during this programme. In December 2007, Iluka relinquished a combined total of 964 square km of ground from its Eyre Peninsula Group of tenements. The parts relinquished were considered non-prospective, based upon a data analysis of the results of previous drilling that occurred in the area. Iluka has an agreement with PIRSA allowing for an amalgamated relinquishment entitlement over all of its Eucla Basin tenements, and the Eyre Peninsula reporting group tenements' area size reductions made up the majority of the 2007 relinquishment requirement. Also in December 2007, Fugro Airborne Surveys was contracted by Iluka to perform an airborne EM survey over the Narlaby Palaeochannel and the Yarranna uranium prospect within it, which is located directly north of Nunjikompita. The job was flown in March 2008, and the final results were received in June 2008. A total of 4400 line km were surveyed, including 2900 line km flown across EL 3267. The east-west flight line spacing was 400 m, and the sensor elevation above the ground surface was 120 m. Bulk composites of the heavy mineral assemblage from the Dromedary prospect were submitted for Method 4 mineralogical analysis, which found that they have ~57% ilmenite, ~17% zircon and ~4% leucoxene (note: the leucoxene fraction contains 2.5% rutile). The zircon has moderate U+Th (~450 ppm) which falls within the market specifications for zircon. The ilmenite is chemically similar to other Eucla Basin ilmenite occurrences. The HM concentrate contains >5% kyanite, which suggests a nearby high pressure metamorphic provenance for this mineral. Saprolite of Proterozoic-aged (approx. 1650 Ma) granitic and gneissic basement rocks of the St Peter Suite and Hiltaba Suite encountered by drilling was sampled early in 2008 for the purpose of multi-element analysis. No significant assay results were returned. In May 2008, Iluka undertook its first uranium exploration drilling campaign within EL 3267, targeting the known Yarranna prospect and the Narlaby Palaeochannel. Preliminary scans of drill cuttings with the GR135 spectrometer showed low levels of uranium mineralisation up to 45 ppm U3O8. Infill holes drilled at Yarranna D failed to repeat the high level uranium intercepts made previously by CEC. Groundwater samples were also collected for analysis. During the 2008 to 2009 reporting period one uranium and two HM drill programmes were undertaken across ELs 4232, 3201, 3267 and 3879. The uranium drilling took place within EL 3267, where a total of 68 holes and 5400 m were drilled. This work encountered mostly palaeochannel sediments overlain by lacustrine sands, with some dunal sands also present. Although some positive indications were given from the scintillometer and spectrometer used on site, there was no significant uranium mineralisation indicated by the assay results. Minor amounts of HM were encountered. The first HM drilling programme took place completely within EL 3267, totalling 66 holes for 1489 m. No HM greater than 1% was intersected. The second HM drilling programme took place across ELs 4232, 3879 and 3201, where a total of 79 holes for 3023.7 m were completed, some of which were infill holes to previous drilling. This work encountered a mixture of interpreted estuarine, dunal and beach sands. No significant HM were intersected. No field work was carried out on the subject tenements during the 2009-2010 reporting year.
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