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DEVELOPMENT OF GEOCHEMICAL GEOPHYSICAL AND REMOTE SENSING METHODS FOR THE PROSPECTING OF GOLD DEPOSITS WITH PARTICULAR ATTENTION TO THE ROLE OF HYDROGEOCHEMISTRY

Objective

This project is aimed at developing and testing a hydrogeochemical method for strategic prospecting of gold deposits in Sardinia (Italy) and in the United Kingdom.
A study aimed to test the use of hydrogeochemical methods, in comparison with traditional geochemical, remote sensing and geophysical methods, for gold prospecting was carried out in Sardinia and the U.K. The remote sensing and geophysical methods (magnetometry and VLF) provided baseline information on the most promising potential areas of gold exploration in Sardinia; traditional geochemistry located gold occurrences in Sardinia; hydrogeochemistry and traditional geochemistry delineated local gold occurrences, both in Sardinia and the U.K.; geoelectric methods defined the three dimensional feature of mineralized bodies. Results obtained in this project suggest that an integrated multidisciplinary strategy is an efficient prospecting tool for gold.
The project involves the following work.
Development of a reliable preconcentration and analysis technique in order to determine the concentrations of gold in solution in natural waters at the nanogrammes to subnanogrammes per litre level.
Geological, structural and hydrogeological studies of target areas in Sardinia, together with lithological sampling for mineralogical and petrographic studies.
Application of geophysical and remote sensing methods which allow the classification of the weathering associated with epithermal gold mineralization. Electrical methods (resistivity and induced polarization) and electromagnetic (very low frequency, high and Rho) will be applied. Remote sensing will be based on thematic mapping images of Landsat 5 and will be evaluated by principal component analysis.
Sampling will be carried out in the United Kingdom and in Sardinia. Sampling of stream sediments, rock and soil will be undertaken in Sardinia, after the geological studies, to determine gold and associated element contents to be consistent with the aims of the research programme and to bring the basis of the study to a similar level as that for the United Kingdom. About 300 samples will be collected in each area. About 120 samples of water will be taken in Sardinia and 150 samples in the United Kingdom.
Analysis of the gold content, physico chemical parameters and major elements in a total of about 270 ground and surface water samples will be carried out. Analysis of a similar number of samples for suitable pathfinder elements (including arsenic, silver, antimony and mercury) will also be undertaken. Preliminary analysis will be carried out by inductively coupled plasma-optical emission spectroscopy(ICP-OES) and inductively coupled plasma-mass spectrometry(ICP-MS) (without preconcentration) with specific gold analysis by ICP-MS after preconcentration. Preliminary analyses will also be carried out mainly by atomic absorption spectrometry (flame atomic absorption spectroscopy(FAAS) and graphite furnace atomic absorption spectroscopy(GFAAS)) and ICP-OES, with specific gold analysis by GFAAS after preconcentration. Gold and other trace elements in suspension (0, 4 mm) from the United Kingdom and Sardinia will be analyzed by instrumental neutron activation analysis(INAA). Gold and pathfinders in stream sediments, rock and soil samples will be analyzed by FAAS for gold and DCP for the other elements.
2 sites in each country showing gold anomalies will be monitored, at a minimum monthly interval, over a period of one year. This programme will enable variations of pH, Eh, gold and other chemical parameters to be determined in relation to the hydrological regime.
Calibration of the soluble gold analysis and related techniques will be carried out jointly. This will include the interchange of samples from each area and exchange of personnel between the laboratories.
Joint evaluation of hydrogeochemical results in relation to the geological, geochemical, geophysical and remote sensing data. Recommendation of an optimum hydrogeochemical method for gold prospecting. Joint preparation of final report.

Coordinator

PROGEMISA S.P.A.
Address
Via Contivecchi 7
09122 Cagliari
Italy

Participants (3)

NERC British Geological Survey
United Kingdom
Address

NG12 5GG Keyworth
Universitaire Instelling Antwerpen
Belgium
Address
1,Universiteitsplein
2610 Wilrijk
Università degli Studi di Cagliari
Italy
Address
Via Trentino 51
09100 Cagliari