Innovative analytical and geophysical technologies for detecting polymetallic orebodies in southern Spain

摘要

The depletion of near-surface mineral resourcesin the Iberian Pyrite Belt (IPB) necessitates exploration fordeeper orebodies. Surface geochemical and geophysicaltechniques produce numerous anomalies, but the problem is toselect those with genuine potential for polymetallicmineralization. A project was undertaken, therefore, with theobjective of developing an effective, low-cost explorationmethodology that would improve the chances of detectingburied, potentially economic, polymetallic sulphide depositswithin the Iberian Pyrite Belt.The project centred on the development, testing andapplication of new geochemical and geophysical techniquescombined with refined geological interpretation. In practicalterms, the work concentrated on the development of newexploration field tools, more powerful data-processing andmodelling systems, a new inductively coupled plasma-massspectrometry (ICP-MS) laser ablation probe and a refinedsystem ol exploration methodology.The products of the project include: interactive, three-dimensional modelling software (MODGM-SD) for theintegration of geological and geophysical data (gravity andmagnetics); software for a downhole, three-axiselectromagnetic probe system designed to detect conductivebodies within a radius of about 150 m of a barren borehole; aselective gas sampler capable of trapping volatile organo-metallic compounds derived from underlying mineralization; apowerful laser ablation mass spectrometer capable ofproducing multi-element and multi-isotopic analyses fromsolid geological samples; a regional geotechnical database forthe Spanish part of the Pyrite Belt in which data from diversesources are combined and incorporated into a geographicalinformation system; characterization of discriminantgeochemical and mineralogical criteria (includinghydrothermal alteration and metal enrichment factors) forsulphide orebodies; and block-modelling of the Los Frailespolymetallic sulphide orebody.