Regolith Guides in Case Study Areas

 

CRC LEME created a series of explorer guides through regolith in case study areas. The following sections link back to these established guides and provides updates where relevant.

Deep Cover

A guide for mineral exploration through and within the regolith in the southwestern Thomson Orogen, New South Wales.
Steve Hill, John Greenfield, Phil Gilmore and Bill Reid

The guide provides an introduction to the regolith and landscape history of the region, together with advice on strategies and methods that can assist with exploration for mineral deposits within and through the regolith. It is designed to assist mineral explorers working in the regolith-dominated terrains of the southwestern Thomson Orogen in far northwestern NSW–in particular the Tibooburra–Milparinka area.

Bedrock exposure accounts for less than 1% of the landscape, with the remainder of the region having sedimentary basin cover. Within the deepest parts of the sedimentary basins, the sediment thickness may exceed hundreds of metres. Sediment thicknesses may decrease to less than 1 metre within the bedrock inliers, but even here the thin cover of sediments is typically extensively transported, thereby obscuring the underlying bedrock.

Highlights:

• Geology and mineralisation
• Regolith material overview, with explanations of how materials evolve in the landscape.
• Landscape history with links to paleoclimate.
• Landscape and regolith evolution models.
• Regolith mineral exploration including; mapping, regolith geochemistry, biogeochemistry and sampling strategies.

Medium to Deep cover

A guide for mineral exploration through the regolith in the Curnamona Province, South Australia
Adrian Fabris, Malcolm Sheard, John Keeling, Steven Hill, Ken McQueen, Colin Conor and Patrice de Caritat

This guide is designed to assist mineral explorers working in regolith-dominated regions of the Curnamona Province. Although the information presented may be applied across the Curnamona region, the focus is on the southern Curnamona Province where there has been the greatest number of regolith studies. It provides an introduction to the regolith and landscape history of the area, as well as advice on appropriate exploration strategies and techniques for exploring through, and within, the regolith.

Deep and or transported cover is present throughout the region. Although there are large areas with more than 1 kilometre in thickness of sediment cover there are extensive areas where predicted depth to bedrock is less than 100 metres. The bedrock exposures account for less than 10% of the landscape. Around bedrock inliers, sediment thickness may decrease to less than 1 metre, but, even here, the thin cover is usually comprised of distally transported deposits. Regolith profiles throughout the Curnamona are therefore highly variable and dominated by thick transported deposits in basinal areas.

Highlights include:

• Landscape history and regolith profile development
• Overview of regolith materials.
• Element dispersion during weathering.
• Regolith mapping tools, including use of geophysical techniques.
• Overview of element mobility in the regolith.
• Exploration strategies – including sample media, analytical approach and methods.

A guide for mineral exploration through the regolith of the central Gawler Craton, South Australia.
MJ Sheard, JL Kealing, MJ Lintern, B Hou, KG McQueen & SM Hill

This guide is designed to assist mineral explorers working in the regolith-dominated terrains of the central region of the Gawler Craton in South Australia: in particular those areas of weathered bedrock where dominantly terrestrial deposits form a patchy and comparatively thin (< 100 m) cover. It provides an introduction to the regolith and landscape history of the region, together with advice on strategies and methods that can assist with exploration for mineral deposits within, or beneath, the regolith.

Highlights include:

• Ore deposit types and exploration targets.
• Landscape history from the Permian.
• Regolith architecture showing that the distribution and architecture of regolith across the region are the result of in situ profile development, modification, erosion, renewed deposition and burial since the very Late Permian.
• Descriptions of typical regolith profiles and regolith materials and minerals.
• Regolith geochemistry including dispersion controls.
• Regolith mapping with emphasis on paleodrainage and paleo coastal deposits.
• Exploration challenges and strategies including analytical approaches and methods.

Shallow to medium cover

A guide for mineral exploration through the regolith in the Cobar Region, Lachlan Orogen, New South Wales
Ken McQueen

This guide is designed to assist mineral explorers working in the regolith dominated terrain of the Cobar region and surrounding areas of western New South Wales. This region is a major metallogenic province with a long history of metal production and remains highly prospective for deposits of copper, gold, silver, lead and zinc. The guide provides a basic introduction to the regolith and landscape history of this area, as well as advice on appropriate exploration strategies and techniques for exploring through the different types of regolith cover.

The thickness of this cover varies considerably (2-80 m) particularly across the numerous palaeochannels. Transported regolith, commonly less than 5 m thick is present over many areas of the central region.

Highlights:

• Ore deposit types and exploration targets.
• Provides a guide to sample media, strategies and techniques.
• Shows common regolith landform settings and element dispersion pathways and suggests geochemical sampling media.
• Guide to analytical approach and methods including comments on QA/QC.

Palaeolandscape report of the Cobar region
Hamid Zekri

Further work has been undertaken in MinEx CRC within the Cobar region. This report has focused on an introduction to Cobar region, including regional geology, basement rocks, geological groups and also cover sequences that occur in the Cobar Basin. In this preliminary study, landscape evolution and palaeolandscape of the Cobar region have been summarised along with an investigation on various types of regolith profiles and the associated chemical and mechanical weathering processes. A broad literature review has been performed spanning previous regolith studies over the last few decades in the region, especially by the Cooperative Research Centre for Landscape Environments and Mineral Exploration (CRC LEME; 2001-2008). Mineralogical, geochemical and geophysical signatures reflected in regolith based on various mineralisation types across the region have been listed as a useful guide for future work and inform the main goals of this project.

Highlights:

• Regional geology of the basement rocks, cover sequences, and palaeolandscape evolution, with descriptions of Ordovician to Devonian geological formations and their mineralisation potential.
• Various regolith features and types including transported, ins-situ, indurated, and lag types.
• Literature review on regolith mineralogy and the impact of weathering on geochemical signatures.
• Regolith response to various mineralisation types in Cobar, highlighting major types in the Cobar region (e.g., CSA, New Cobar, Endeavor), along with geochemical and geophysical exploration criteria for buried systems.

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