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INNOVATIVE ANALYTICAL AND GEOPHYSICAL TECHNOLOGIES FOR DETECTING BLIND POLYMETALLIC OREBODIES IN SOUTHERN SPAIN

Objective


The main results that come out of this project are:

1. Instrumental:
a. interactive 3D modelling software MODGM-5D for integrated geological and geophysical data (gravimetry, magnetism);
b. software package for a downhole 3-axis EM system ARLETT (acquisition, representation and interpretation of data); the 3-axis EM system was developed to both recognise and locate conductive bodies within a radius of about 150 m of a barren borehole
c. development of a selective gas sampler based on the use of charcoal (activated carbon fibre tissue TCA) as sorbant, capable of trapping volatile organo-metallic compounds derived from underlying mineralization
d. development of a powerful laser ablation mass spectrometer (ICP-MS) to provide multi-elemental and multi-isotopic analyses in sold geological sample (laboratory support).

2. Methodological:
a. better geological knowledge of the Pyrite Belt, with a new regional structural sketch, and characterization of discriminant criteria for sulphide orebodies, such as hydrothermal alteration factors (Ni/Co ratio in rocks), metallic enrichment factors (Au correlations and Sn-Co grades);
b. constitution of a regional database for the Spanish part of the Pyrite Belt, assembling a wide variety of spatial data collected from diverse geoscience sources and, using a GIS based on a geo-relational data model.;
c. block-modelling of the Los Frailes orebody;
d. simultaneous use of tools and synergic data interpretation under operational conditions (exploration methodology).
In the South Iberian Province, mineral extraction is on the decline because all of the major outcropping and near surface occurrences of sulphide have been discovered and exploited. The discovery of new polymetallic deposits is now dependent on innovative exploration technologies capable of recognising anomalies associated with blind orebodies. Thus it is necessary to develop these new technologies in the field and the laboratory whilst at the same time achieving significant reduction in the costs of exploration. With this in mind it is proposed to re-evaluate the mineral potential of a precisely defined area by developing the following prototype tools:

a) new, advanced software to derive three-dimensional images from geophysical data (gravimetry, 3-axis down-hole electro-mangetism), for the exploration of dense and conductive mineralizations;

b) novel selective gas sampler for capture and analysis of organo-metallic gases which will aid in geochemical explorations and environmental control;

(c) a prototype laser ablation inductively couplet mass spectrometer (laser ICP-MS) capable of fast multi-element analysis at sub-ppm levels from ablated areas of 10 microns or less, as laboratory support tools for geochemical exploration.

The successful development of these tools will lead to the identification of a target which will be drilled and tested. The discovery of new blind orebodies would regenerate the ailing mining sector in the South Iberian Province. Advanced exploration tools and new methodology will be of long-term benefit for mineral exploration.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Bureau de Recherches Géologiques et Minières (BRGM)
Address
Avenue De Concyr
45060 Orléans
France

Participants (6)

ANDALUZA DE PIRITAS SA
Spain
Address
Minas De Aznalcollar
41870 Sevilla
Fisons Scientific Equipment
United Kingdom
Address
Ion Path Road Three
CW7 3BX Winsford
INST TECNOLOGICO GEOMINERO
Spain
Address
Rios Rosas 23
28003 Madrid
RIO TINTO MINERA SA
Spain
Address
Apartado 1
21660 Huelva
Seiemsa
Spain
Address
Foxo De Somosaguas
28023 Madrid
UNIV SEVILLA
Spain
Address
Campus De La Rabida
21819 La Rabida/huelva