Hydrogeochemistry for Resource Evaluation

Scientist out in the field taking hydrogeochemistry measurements in the Northern Territory

The Hydrogeochemistry for Resource Evaluation project aims to use groundwater chemistry to better understand the bedrock-regolith system and develop new methods for recognising mineral system footprints within and below cover (Schroder and Caritat, 2017).

This work is conducted in selected areas to identify the most suitable chemical indicators that apply to various mineral systems. Initially targeting areas of shallow cover near known mineral deposits as well as in barren areas, the project will then extend into regions of deeper cover to develop and test diagnostic tools. Focus areas are up to three 1:250,000 scale map sheets, targeting existing groundwater bores that afford a suitable spatial coverage. The Tennant Creek and McArthur Basin regions have been identified as preliminary focus areas.

In addition to standard measurements including bulk parameters (e.g., temperature, pH, electrical conductivity), major anions, major cations and trace elements, selected groundwater samples will be analysed for a comprehensive suite of isotopes (e.g. Oxygen, Hydrogen, Carbon, Sulfur, Chlorine, Strontium, Lead, Radon), organic compounds, hydrocarbons and dissolved gases.

If suitable chemical indicators are recognised and can be mapped spatially, hydrogeochemistry may be used more widely as an exploration tool in Australia, with the capability of identifying and targeting parts of mineral systems under cover. The hydrochemical data will provide baseline data for improved understanding of regional aquifers, hydrogeologic processes and broad scale groundwater quality for diverse stakeholders. This baseline data can be used to assess the impacts of any future development in the area.

Progress

During the 2017 field season, the hydrochemistry project team collected 118 groundwater samples from 106 bores across the Tennant Creek and McArthur areas using sampling techniques suitable for up to 27 analytes per site. These samples are currently being analysed with an additional 20 samples included for quality control purposes (blanks and lab duplicates).

Outputs

  • A publicly available dataset of quality-controlled hydrochemical data generated from the project will be released as data becomes available. The first data release is planned for mid-2018;
  • Recommendations on using groundwater geochemistry in northern Australia as a tool for mineral exploration under cover;
  • Presentation of results to stakeholders at appropriate conferences/workshops.

Collaborations

We are collaborating with the Northern Territory Geological Survey (NTGS) and NT Department of Environment and Natural Resources (Water resources); further collaboration with external industry, academia and other government and research organisations (e.g., CSIRO) greatly enhances the type of data collected and the quality and breadth of analysis and data interpretation.