Success and development in discovering beach placers in the Eucla Basin, southern Australia

Abstract

One of the most zircon-rich heavy mineral sand (HMS) deposits on Earth has been discovered in part due to interrogation of new geoscientific models. The minerals are associated with fossil beaches, which formed almost 40 million years ago, along a huge margin of the Eucla Basin, southern Australia. The exploration implications of the proposed new geoscientific models have been realised by exploration companies (eg. Iluka Resources & Adelaide Resources), resulting in the recent discoveries of new zircon-rich HMS deposits in the eastern basin. The new discoveries, namely Jacinth, Ambrosia and most recently Tripitaka in South Australia, are hailed as the most significant discoveries of their type in nearly 30 years. This exciting outcome highlights the innovative nature and quality of geoscientific research a nd demonstrates how the resources industry can translate this research into economic benefits. The research successfully addresses National Research Priority Three ? frontier technologies to transform industry. Our models of landscape evolution and revised interpretation of the dynamics of sediment accumulation in palaeorivers and associated shoreline deposits has been extensively utilised to develop a new understanding of Cainozoic marine transgressions and deposition in the region. GIS based palaeogeographic reconstructions were based on digital elevation models, remotely sensed imagery, geological and drillhole data, and sedimentological analysis. On a more detailed scale, preliminary heavy mineral analyses utlising the AutoGeoSEM suggests that the heavy mineral suite at Jacinth is dominated by zircon, pseudorutile, rutile/anatase and ilmenite. Less common minerals include a variety of aluminosilicates (tourmaline), aggregates of hematite, quartz and clay, monazite and chromite. Our recent work indicates that the zircon contribution to this heavy mineral suite was dominantly derived from the Precambrian rocks of the Musgrave Province vs Officer Basin with minor grains from the Gawler Craton. We conclude that the Eucla Basin has become a world-class HMS province.