Amadeus Basin statigraphic characterisation
The Amadeus Basin is a Neoproterozoic-Palaeozoic intracratonic basin that covers about 170,000 km2 in central Australia.
It has a relatively long history of exploration for and subsequent production of, gas and oil, although by world standards it remains significantly underexplored.
Mineral exploration has been sporadic and largely focused on investigating surface mineralisation rather than strategically testing for major styles or models of mineralisation.
To date only gold and uranium have been found in economic quantities, however the basin holds significant potential for base metals, as well as other metal commodities.
The project aims to develop an understanding of basin architecture and its tectonic framework, to characterise and clarify its depositional history, and address existing issues of correlation across the basin.
This work will provide the basis for identification of mineral deposit models related to specific stratigraphic units, identification of key fluid pathways and timing, and provide valuable datasets to assist with mineral and hydrocarbon exploration.
During 2014 a combined field and laboratory based approach was taken to the characterisation of the Neoproterozoic stratigraphy of the Basin.
The field component involved examining key sections of the stratigraphy where it is well-represented and well-exposed in the northeastern Amadeus Basin.
The aims were to:
- Document the lithologies, facies and facies variations that characterise each lithostratigraphic unit.
- Identify key characteristics that can be used to recognise the different stratigraphic units in the field as a basis for future NTGS mapping, and to assist other workers in the Basin.
- Provide a framework for subdividing the Neoproterozoic stratigraphy in areas where this has not previously been done; specifically in Henbury 1:250 000 map sheet (HENBURY) starting in the 2015 field season.
- Provide a comparative basis for the future further characterisation of the stratigraphy in drill core, which will again further assist other workers in the Basin.
- Compile a comprehensive dataset for each identified unit of the Neoproterozoic. This dataset will include, but not be limited to, geochronology (provenance and maximum deposition ages), whole rock geochemistry.
The second phase entails mapping of HENBURY. In this area the Neoproterozoic succession has been historically mapped as two informal units (Inindia beds and Winnall beds).
The aim of this project is to try to resolve the Neoproterozoic succession into the formations characterised in the northeast of the basin (see above), as well as characterise the Palaeozoic stratigraphy of the central part of the basin which is well exposed in this area.
This project commenced in 2015 with field work concentrated in the southern part of the mapsheet where the majority of the Neoproterozoic succession is exposed. In 2016 the main focus will be the largely Palaeozoic succession in the northern part of HENBURY.
CODES – ARC Centre of Excellence in Ore Deposits, University of Tasmania
Isotope Geochemistry Group, School of Earth Sciences, University of Melbourne
- the Bitter Springs Formation and its constituent members upgraded and formalised at group and formation level respectively; and the new type sections formally established
- definition of the Wallara Formation (formerly ‘Finke beds’) that occupies a key time interval in the Basin and potentially globally
- identification of type sections for a number of units where these did not previously exist
- recognition of additional reference sections that contribute to the full characterisation of the units and their facies variations
- U-Pb zircon provenance patterns have been determined for the Neoproterozoic stratigraphy in the NE of the Amadeus Basin and show the dominant sources of sediment are the bounding basement terranes of the Arunta Region and Musgrave Province
- Hf provenance spectra have also been determined and are currently being interpreted which complement the U-Pb zircon data providing additional constraints on provenance and may allow identification of specific source rocks in some instances
- baseline geochemical data has been collected for many units.
- ll outcrops of Inindia beds have been resolved into the constituent formations recognised and described in the northeast of the basin (see above)
- Winnall beds has been subdivided into a series of formations that are currently being formally defined
- Bitter Springs Formation (now Group) outcrops have been identified as belonging to the Loves Creek Formation
- Johnnys Creek Formation and the newly defined Wallara Formation have been recognised and described
- U-Pb zircon data has been collected for most units on the mapsheet, and Hf data will be collected in the near future
- petrography and whole rock geochemistry data has also been collected for most units
Edgoose CJ, Normington VJ, 2014. A systematic appraisal of the Neoproterozoic stratigraphy of the Amadeus Basin – building a framework for assessing resource potential. In Annual Geoscience Exploration Seminar (AGES) 2014. Record of abstracts. Northern Territory Geological Survey, Record 2014-001.
Normington VJ, Donnellan N, Edgoose CJ, 2015. Neoproterozoic evolution of the Amadeus Basin; evidence from sediment provenance and mafic magmatism. In Annual Geoscience Exploration Seminar (AGES) 2015. Record of abstracts. Northern Territory Geological Survey, Record 2015-001.