The Bellevue gold deposit: Re-emergence of a historic high-grade gold field through the application of modern exploration techniques

摘要

The Bellevue mine is located in the Agnew-Wiluna Greenstone Belt, in the Leinster region of the North-Eastern Goldfields of Western Australia. Historic production from the mine was approximately 800,000oz @ approximately 15 g/t from a predominantly underground gold operation, active between 1987 and 1997. The operation closed with mineralisation interpreted to be faulted out at the 13th level by a regional strike slip feature named the Highway Fault. The project was subsequently used to accommodate dewatering from the adjacent Cosmos nickel mine and no further exploration for gold was conducted after 1997, an exploration gap of 20 years. Modern exploration recommenced in 2017 with a revisited geological model and subsequent drill programs, which has resulted in the discovery of significant new high-grade gold resources. Currently the project's JORC 2012 resources stand at 5.pmt @ 11.1 g/t gold in the inferred resource category (which excludes the recent Deacon discovery). Mineralisation is associated with N-NNW striking, westerly dipping, mineralised shear zones and conjugate low-angle mineralised shears. Within the shear zones, gently southerly plunging high-grade ore shoots are associated with massive to semi-massive pyrrhotite and folded and boudinaged quartz veins, with a predominant biotite amphibole alteration assemblage. The high pyrrhotite content of the ore system means down-hole electro-magnetic (DHEM) is an effective exploration tool at the project for the direct targeting of gold mineralisation, with the method routinely used to vector drilling. This utilisation of this vectoring tool has most recently led to the discovery of the Deacon lode.