This report details work undertaken by Iluka Resources to meet the agreed conditions for grant of PACE Initiative Year 5 exploration drilling project partial subsidy funds. Specifically, Iluka undertook heavy mineral sands exploratory drilling...
This report details work undertaken by Iluka Resources to meet the agreed conditions for grant of PACE Initiative Year 5 exploration drilling project partial subsidy funds. Specifically, Iluka undertook heavy mineral sands exploratory drilling during November-December 2008 along an interpreted Neogene-aged shoreline present on tenements EL 3322, EL 3267 and EL 3330. Drilling was undertaken to both the south-east and north-west of the Dromedary prospect, which had been discovered in 2007 (under a PACE scheme Round 4 grant). A total of 8 drilling traverses, comprising 78 aircore NQ holes for a total penetration of 1781 m, were completed. From the recovered drillhole cuttings Iluka submitted 127 samples for heavy mineral (HM) assay and determination of slimes content. The aims of the subject drilling programme were: - to gain a thorough stratigraphic overview of the region in order to pinpoint prospective areas more definitively. - to define the extent of beach sequences (both for geological and strategic reasons). - to identify key elevations for the development of HM concentrations. - to broadly characterize all HM occurrences. - to understand the effect that inferred neotectonic activity may have had on the geomorphology, distribution of beach sequences, shorelines and HM occurrences. - to understand the distribution and morphology of the basement for the development of coastlines and thus the deposition of HM. - to develop and present geological models to convey the drilling interpretations. The palaeo-shoreline surrounding Dromedary prospect was targeted by the Year 5 PACE drilling mainly due to its inferred geomorphological similarities to the settings hosting the Jacinth, Ambrosia and Tripitaka heavy mineral discoveries. Secondly it was targeted for its proximity to the eastern margin of the Bunda Plateau, because it was thought that this area would be subject to longshore drift. The drilling undertaken by Iluka both in 2007 and 2008 has found that the palaeo-shoreline (and Dromedary) is formed around a shallow basement feature. The Dromedary prospect sits in a 'J'-shaped bay that formed near the south-eastern end of the shoreline, and was constrained by apparent rises in basement RL to the south-east and north-east. In both these directions the latest step-out drilling has demonstrated that there are significant differences in the spatial extent of various Tertiary stratigraphic units, which are fully described in the subject report. Briefly explained, this means that to the north-west of Dromedary, the marine sand (Unit 1) has been progressively eroded (and replaced) by fluvial sand and dunal material. Here, Unit 1 has been eroded and Unit II overlies basement (Traverses 4-9). Low grade mineralisation is generally hosted in dunal sands (such as that on Traverse 5). To the south-east/east of Dromedary, the shoreline sediments originally deposited there have been eroded up until the deposition of Unit IV (tentatively classified as the Bridgewater Formation). Consequently, indurated silty sands and pedogenic calcrete directly overlie shallow basement. There is no mineralisation associated with these Unit IV sands. Some distance further to the west, Tertiary lacustrine facies sediments were encountered on EL 3330 beneath younger dunal and marine cover. To summarise the programme results, unlike the outcome of the 2007 drilling, no substantial intersections of mineralised beach sands transpired in 2008, although a few isolated intervals of between 0.5% and 1% HM were found. As had been revealed by the drilling done in 2007, with confirmation from the 2008 drilling, four distinct stratigraphic units comprise the Neogene palaeo-shoreline. Dromedary appears to be the only remaining occurrence of mineralised beach sands along this shoreline. It is postulated that the Dromedary mineralisation and host sands are of Eocene age, whilst the dune-dominated sequences above it have been deposited at a later date, most likely during Late Miocene time.
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