The Discovery of the Edna Beryl Gold Deposit – a journey with the destination of multiple mineral discoveries

Abstract

The discovery of the greater Edna Beryl mineralisation marks a successful journey of systematic, science based exploration over a nine-year period. It is as much about the tenacity of the Emmerson exploration team and the quest for unlocking the geological code as the capability of the Board to secure funding to support this aggressive exploration during the usual peaks and troughs of the capital markets. Like most successful endeavours, the journey has always been with a clear business focus around effective and efficient exploration, taking into account the probabilities of discovery whilst using the failures as the fertiliser for improvement. The Tennant Creek Mineral Field is famous in terms of hosting some of the highest-grade gold and copper deposits in Australia, the majority successfully discovered by either surface prospecting or, some innovative modelling of the various magnetic geophysics - the obvious “tool of choice” considering the host to the gold and copper is predominantly hydrothermal magnetite (locally termed ironstone). In 2008 when Emmerson commenced exploration in Tennant Creek, it was recognised that most if not all of the obvious magnetic anomalies had been tested, thus leading Emmerson on a very different journey that was predicated on refining the exploration models with a more holistic view of the entire mineral system across all geological scales. Emanating from this was the hypothesis that oxidised fluid sources played a far more important role in the genesis of these deposit types and that these fluids were in fact instrumental in the deposition of ultra-high grades of gold and copper. Thus much of the research and data collection is specifically aimed at trying to better understand the role of these fluids, their possible connection to the Tennant Event and their pathways via refining the 3D structural framework. Ultimately this approach has been successful in discovery of the Goanna and Monitor copper-gold systems, the Mauretania gold and the more recent, ultra-high-grade Edna Beryl gold mineralisation. All displaying the common theme of an association with highly oxidised, hematite rich fluids and typically associated with little or at best very weak magnetic signatures. This has opened up the entire Tennant Creek Mineral Field to a new generation of predominantly hematite hosted deposits which by virtue of their different geophysical signature, remain largely untested by previous explorers.