research program 1
regolith geoscience
Northern Territory Regolith
Project Leader : Mike Craig, Geoscience Australia
Start date and duration: July 2003; 26months i.e. September 2005
Participants : Geoscience Australia, CSIRO Exploration and Mining, Northern Territory Geological Survey (NTGS)
Brief project description :
This project provides a regional regolith-landform framework of the Northern Territory for mineral exploration and land management.
The Australian regolith is a product of weathering, erosion, deposition and chemical transformation. In tropical and arid environments of the geologically stable Northern Territory , these processes are reflected in the landforms, desert sands and loams, internal and external drainage systems, and ancient weathering surfaces that we see today through various forms of imagery.
In 1975 the BMR (now Geoscience Australia ) produced a Cenozoic Geological Map of the Northern Territory , based on surficial units as represented on First Edition 1:250,000 scale geological maps. The Regolith Landform Map of Australia (1:5Million) was produced in 1984. These two maps showed some major alluvial-colluvial systems, and some major areas of ferruginous duricrust. However it did not address the integrity of the palaeodrainage systems that are largely covered by dunefields particularly in the southern and central parts of the Territory. Nor did it address the question of the evolution of land surfaces and regolith materials. Since, there has been considerable advances in understanding regolith processes in the Cratonic regions of Australia . In addition there is a wealth of new data provided by Second Edition geological mapping, Landsat 7, DTM and radiometric data from high-resolution airborne surveys, and drill data from mineral exploration.
A detailed regolith study of a pilot area in the Tanami Region was undertaken by LEME in 1999. The study was based on detailed surface, sub-surface observations and regolith information extracted from remotely sensed imagery, and showed extensive deposits (up to 100 metres thick in places) of transported material on buried palaeo surfaces of significant relief, with minor buried 'relics' of ferruginous duricrust.
A considerable amount of detailed site-specific regolith work has been done in continental Australia, especially through LEME, however to date there has been few attempts, with the exception of the Gawler Craton regolith studies undertaken by CRCLEME from 1998-to2002, to extend these site-specific models to the extensive cratons of the Australian continent.
The excellent regional and detailed datasets coupled with detailed studies at a new site should now provide an extended basis for regional regolith-landform framework of the Northern Territory . An understanding of the regolith is necessary for effective mineral and diamond exploration, and provides a framework for understanding landscape evolution, extractive and placer mineral occurrences, groundwater potential, rangeland management, and environmental geoscience.
Deliverables (outputs) and expected impacts of research (outcomes):
• Regolith-landform map (1:2.5 Million scale) of the Northern Territory , as a companion to other Territory-wide maps (such as Geology, TMI, DTM and Radiometrics)
• Reports (Atlas) and scientific publications in national/international journals
Milestones - Achieved:
• Compilation of datasets
• Selection of key areas
• Regolith models
• Regional regolith-landform map
Synthesis report and scientific publications
|
