Year 4 annual and final report on exploration activities for EL 23994 Tanaburs NE

Abstract

EL 23994 'Tanaburs NE' was granted to Gravity Diamonds Ltd ('Gravity') on 8 September 2004. The EL forms part of broader project area where Gravity is conducting diamond exploration, much of which is under an exploration agreement with Rio Tinto group companies and Diamond Mines Australia (DMA), which is a 100%-owned subsidiary of Gravity. During 2003 and 2004, DMA through an exclusive arrangement with BHP Billiton deployed the Falcon Airborne Gravity Gradiometer system in diamond exploration in Australia. The Falcon system has proved an effective diamond exploration tool since its development by BHP Billiton in the late 1990's. During the first year of tenure Falcon data was acquired over part of EL 23994. The system includes airborne gravity gradient data, high resolution magnetics and accurate elevation data derived from on-board differential GPS and laser scanner devices. The area of coverage amounted to approximately 27 km(2) (~295 line kms). During the second year of tenure, detailed targeting based on the acquired gravity gradiometer data within the south-western part of EL 23994 was completed. Although some second order preliminary targets were proposed, no priority targets were identified for follow-up within the portion of the EL covered by the Falcon survey. A single gravel sample was collected within EL 23994 as part of a broader sampling program in the Tanaburs project area. The sample reported negative for kimberlite indicator minerals. A detailed review of previous diamond exploration within the whole tenement was subsequently conducted during the 3rd year of tenure. This review suggested that whilst previous heavy mineral sampling coverage was adequate, results from Gravity Diamonds sampling programs elsewhere in the Northern Territory that several sampling programs carried out by previous explorers suffered from poor site and sample collection. Additionally advances in heavy mineral processing through micro-DMS plants has increased the recovery and decreased the effective grainsizes of heavy mineral recovered. To test a historic sample reporting 4 chromites, three samples were collected during Year 3. During Year 4 of the licence the single chromite collected during the previous year was reassessed and was not deemed sufficiently anomalous to continue intensive exploration with respect to other targets within the district and the region. EL 23994 was surrendered on 5 September 2008.