DART MINING NL Dart Mining NL announced that reverse circulation drilling of significant soil Cu-Au anomalism has commenced on its wholly-owned Granite Flat project in Northeast Victoria. The 1600m, 15-hole drill program is designed to test the strike extent of Cu-Au mineralisation through the centre of a large 2.4x1.8km soil copper anomaly. Previous drilling undertaken by Dart Mining has demonstrated Cu-Au mineralisation within this soil Cu-Au anomaly, and drill holes in this program are planned to provide infill in a 700m gap along strike between previous drill holes, all of which have demonstrated long intercepts of low-grade Cu-Au mineralisation, or narrow intervals of vein-hosted, moderate to high-grade Cu and Au mineralisation.
Target depth for all holes is between 100-120m below surface. At the time of release, five of the fifteen planned holes have been completed, with sulphides encountered in all holes. The Granite Flat prospect is located nine kilometres southeast of Mitta Mitta township and is accessed via the Omeo Highway.
Historically, the prospect was mined at several small production centres between 1856 and 1918, following an initial discovery identified by tracing the source of alluvial gold in the Mitta River upstream. Previous explorers have targeted the area with geophysical surveys, rock chip, soil and stream sediment sampling, and drilling and trenching. Historic soil grids have established several large, strong Cu-Au anomalies that have seen variable drilling efforts across the prospect.
In total, 18 costeans, 52 reverse circulation (RC) and 19 diamond drillholes have been completed by previous explorers between 1986-1997 (Meltech Ltd., CRA Exploration [now Rio Tinto], and Perseverance Mining Ltd.). The broad intersections of low grade Cu-Au mineralisation returned in historic drilling and Dart's recent 42 hole RAB drilling program are hosted within potassic, chlorite and epidote-altered granodiorite, further confirming the potential for porphyry-style mineralization. Mineralised zones at Granite Flat are hosted within the Banimboola Quartz Monzodiorite (BQM).
The BQM has been broadly identified as hosting a porphyry style of Cu-Au mineralisation associated with I-type granitoid and sulphide veins, with alteration varying from silicic to argillic to propylitic, with moderate to high background copper. Monzonite intrusive bodies are often the host of porphyry systems in the Lachlan Fold Belt. Additionally, the Granite Flat prospect lies adjacent to the Gilmore Suture, a significant crustal-scale structure that is associated with the emplacement of several porphyry Cu-Au systems across the border in New South Wales.
Whilst still in the early stages of exploration, Dart Mining geologists believe that many of the geological characteristics and mineralised features of the Granite Flat prospect correspond with key elements of the porphyry exploration model.
