WESTERN AUSTRALIAN DIVISION
West Australian Geologist (WAG)
Bi-monthly newsletter of the Western Australian Division of the Geological Society of Australia Inc.
Number 510: February ̶ March 2015 (2.0 Mb PDF file)
Time: 5.30 pm for 6.00 pm formal start (bar open upstairs before talk)
Venue: Irish Club of WA,
NEXT MONTHLY MEETING
Wednesday 4th March, 2015
Talk title: Geochemical dispersion through transported cover in regolith-dominated terrains – towards an understanding of process
Speaker: Dr Ravi Anand, Chief Research Scientist, CSIRO & Adjunct Professor, Curtin University of Technology, Perth, Western Australia
Abstract: As mineral exploration moves into regions dominated by transported cover, conventional techniques may not be applicable and thus, increasingly, there is a need for new, innovative approaches. To develop these approaches, potential mechanisms that transfer metals from buried mineral deposits through cover to the surface need to be identified. This presentation provides an overview of some of the experimental and field trials conducted in Australia as part of an industry-supported three year CSIRO/AMIRA Project and other research. The objective was to define vadose zone processes that might form elemental anomalies at surface over buried deposits in semi-arid and arid terrains, and to compare methods that detect these anomalies. Studies were conducted representing Au, VMS (Cu-Zn-Ag) and Ni mineralization with transported cover ranging in thickness from 2 m to 100 m. Three vertical metal migration mechanisms are important in vadose environments; i) biological, ii) gaseous and, iii) capillary. An integrated approach, combining different mechanisms with the nature and evolution of transported regolith and climatic settings, was considered to obtain the best prediction of metal transfer. Regions and landforms of highly weathered transported cover with current or past water tables residing within the cover and long-standing vegetation will favour combined mechanisms such as electrochemical, plant uptake, bioturbation and capillarity. Fresh, relatively unweathered and thick (>30 m) transported cover may prove the most unlikely to develop surface geochemical anomalies.
Upward element transfer by vegetation (Acacia aneura and Eucalyptus spp.) occurs in areas of transported cover up to 30 m thick, but not in environments which lack supergene enrichment and have hypersaline acid groundwater. Termite studies have demonstrated vertical movement of soil from up to five meters depth. Termite activities influence relative elemental abundances in soils immediately adjacent to mounds. Metals, detected by gas collectors, are transferred to surface as gases. However, gas mechanisms have limitations. Greater cover depths (>30 m), especially those with variable stratigraphy and/or unweathered cover, are where many of the upward metal transfer mechanisms are least effective. In these environments, interface is a highly effective sampling medium. The material on the interface can include diverse materials from a variety of sources, depending on the degree of palaeoexhumation of the palaeoweathering profile. This reinforces the importance of precisely defining the palaeosurface and mapping the palaeotopography which will continue to host the best direct geochemical indicators of buried mineral systems in areas of deep cover.
Soil pit experiments show strong geochemical anomalies can form rapidly (over 7 months) through 2 m of transported cover, and assist in understanding the genesis of natural geochemical anomalies. Seasonal variations suggest migration of elements from source to surface may vary in time and intensity. Anomaly formation in the pit experiments is an episodic process largely driven by capillarity, in which batches of metals in water-soluble form are translocated. Soil forming processes may form false anomalies and the data need to be interpreted with care.
About the speaker: Dr Ravi Anand is a Chief Research Scientist at CSIRO and an Adjunct Professor in regolith geology and geochemistry at Curtin University of Technology, Perth, Western Australia. He joined CSIRO in 1987 as a Research Scientist in the Division of Mineralogy, carrying out research into methods of exploring for concealed mineral deposits in Australia’s deeply weathered terrains. Ravi was Applications Coordinator of the CRC for Landscape Evolution and Mineral exploration (1995-2001) and Program leader of Program 2 for Landscape Environments and Mineral Exploration (2001-2008). He has over 30 years research experience in regolith geoscience and exploration geochemistry, mainly in developing procedures for gold, base metals, bauxites and uranium exploration in deeply weathered terrains. His current research in collaboration with the industry is focussed on understanding metal dispersion processes through transported cover. He led many industry-funded research projects in Australia, and has undertaken consultancies and delivered courses and field workshops to industry, university extension and government in Australia, Canada and several countries in South America and Africa. Ravi has authored/co-authored over 300 papers, edited monographs and reports. The outcomes of his research have been major contributors to the discovery of many mineral deposits.
GSA-WA Student Bursary
The GSA-WA offers bursaries to assist students in their studies and research.
Up to $1000 can be granted for any meritorious project, for 1 or several students, such as field trips, for laboratory costs, for travel costs or conferences.
Applications close 31 March and 30 September each year.
View the flyer for further information and complete the application form to submit a nomination.
Bursary Flyer download: PDF doc
Bursary Application Conditions download: MS Word doc
Bursary Application Form download: MS Word doc
2015 Gibb Maitland Medal
The Gibb Maitland Medal is awarded by the Western Australia Division of the Geological Society of Australia in order to recognize individuals who have made substantial contributions to geoscience in Western Australia. It is named for Andrew Gibb Maitland, Government Geologist from 1896 to 1926, who established the Geological Survey of Western Australia. The Medal is usually awarded each year and nominations are now sought for the 2015 Gibb Maitland medallist.
2015 Gibb Maitland guidelines & nomination form download: MS Word doc
Nominations closed Monday 1 December 2014 and the winner will be announced shortly.
Yilgarn Retrospective 2-Day Symposium
30th & 31st March 2015
The Yilgarn Craton (WA) in the second half of the 20th century witnessed a transformative period in the resources industry which included the discovery and successful exploitation of a new deposit type (komatiite-hosted nickel sulphide), a massive boom in exploration and mining of Archaean lode gold, and developments in a number of other commodities.
This two day symposium will look at the who, why and how of this momentous era 1950 to 1999. The meeting will be a deliberate acknowledgement and record of the achievements of teams and individuals, some of whom are no longer with us.
Further event details are available on the AIG website http://www.aig.org.au/?s=yilgarn+retrospective.
2014 GSA-WA Division AGM Minutes
The GSA-WA Division 2014 Annual General Meeting was held at the Irish Club, Subiaco on Wednesday 2 April 2014.
modified: 13 February 2015