Monday, June 16, 2008

Council for Geoscience provides expertise for mapping project in Madagascar

The Council for Geoscience (CGS) is currently involved in a large mapping project in Madagascar, which forms part of a mapping project funded by international bank World Bank, which provides loans to developing countries for development programmes, reports CGS project manager and scientific leader for the Madagascar project Paul Macey.

The British Geological Survey (BGS), the US Geological Survey (USGS), as well as geological survey groups from Germany and France, are similarly involved in the Madagascar mapping project funded by the World Bank.

“The government and people of Madagascar are our final clients, but the products are audited by a World Bank- appointed supervision team. In the case of the CGS, the project is cofunded by the South African Department of Science and Technology,” reports Macey.

The World Bank is set to build a modern digital geological, geochemical, and geophysical base map and database dataset for Madagascar, principally to promote mineral resource exploration.

The project also serves to provide support to sustainable social development projects, including those concerning the environment, urban development, agriculture and hydrogeology, explains Macey.

The Madagascar project began in 2005 and initially produced high-resolution magnetic and radiometric data for six selected areas of Madagascar, while reconnaissance geological mapping by the CGS, as well as the BGS, the USGS, Germany’s geological survey group, and France’s Bureau of Mines and Geology, followed the geophysical survey, and was accompanied by regional geochemical stream sediment sampling, reports Macey.

He adds that the project focused on the Precambrian and Cretaceous rocks of Madagascar.

“Specifically, the CGS is contracted to produce 34 fully digital geology, geohydrology and mineral resource maps, 102 stream- sediment geochemical maps and two geological explanations for the two regions in a total area coverage of about 30 000 km2,” states Macey.

The CGS mapping project began in September 2005, and involved several mapping and sampling seasons in the autumn to spring months of 2005, 2006 and 2007.

“The project is nearing completion with the first submission due at the end of July 2008. Overall, we have achieved about 80% completion to date,” reports Macey.

He says that the main challenge in the project has been access to the mapping regions, given the limited time resources allowed in the project.
“Most of the work was done on foot or by motorcycle, but we also made use of white water rafting trips and, for a very remote area, a helicopter. We also had some security problems with the cattle bandits of the region,” mentions Macey.

However, the Council achieved its objective of providing high-quality digital geological and geochemical maps, states Macey.

“The geochronological, structural and petrological research associated with this work has contributed directly to a much improved understanding of the Archean to Cambrian, and Cretaceous, magmatic, tectonic and metamorphic history of central and north-west Madagascar, and, specifically, the formation and dispersal of supercontinents Rodinia and Gondwana,” he highlights.

The CGS is also involved in geological and mining exploration research projects with the Department of Minerals and Energy, with which it has undertaken two large project reports, reports CGS’s Mineral Resources and Development geologist Robert Hansen.

The first research project is to assist small-scale miners, who wish to start a small-mining venture by providing geological services, such as deposit evaluation, and the second is to study ownerless and abandoned mines in order to determine the environmental as well as sociological impact, reports Hansen.

He is currently participating in the study of abandoned mines, which is aimed at assessing the impact of heavy-metal mobility from mine wastes and its impact on the local environment.
Hansen says that the core function of the CGS is to do regional mapping to assist with the promotion and development of South Africa’s mineral resources; however, the focus has moved to mapping in foreign countries, especially in Africa, in places such as Morocco, Ghana and Madagascar.

The CGS provides mining companies in South Africa with specific geological information, mostly in the form of printed maps, as well as mineral commodity data, as a geographic information systems product.

“Our laboratory also provides a range of analytical services to mining companies, especially smaller companies,” adds Macey.

In recent years, the CGS has focused on diversification of its core functions in a changing geological environment. CGS has added environmental geosciences and water geosciences units, in addition to its seismology, geophysics, mineral resource development, geochemistry, engineering geosciences and laboratory units.

“They all perform statutory as well as commercial obligations for specific clients needing specific geoscientific services,” states Macey.
He says that important advances made by the CGS includes the purchase of the new X-ray fluorescence (XRF) and inductively coupled plasma mass spectroscopy machines, that have significantly reduced turnaround time and increased analytical precision.

“The XRF will be used to determine the major element content of clay, as well as any potential impurities in a clay deposit mining project, and the purposes for which the clay can be used. Various other methods in our clay laboratory will be used to determine clay characteristics, such as its structural integrity or plasticity and water-retention capabilities.

Waste from an abandoned mine might be polluting a local stream or groundwater system of a rural town with heavy metals. It is important to know where the metals are coming from, what the controls on their distribution are, and how the situation can be remediated. Methods such as XRF and sequential extraction will be used to answer these questions,” explains Hansen.
He says that the CGS serves the public of South Africa by assisting small-scale miners to determine the quality of the commodity they wish to mine.

“The CGS aims to provide expert earth-science information and services to improve the management of natural resources and the environment for a better quality of life for all,” concludes Macey.



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