Chapter

3D, 4D and Predictive Modelling of Major Mineral Belts in Europe

Part of the series Mineral Resource Reviews pp 231-261

Date:

Modelling of the Neves Corvo Area

  • C. InvernoAffiliated withLaboratório Nacional de Energia e Geologia (LNEG) Email author 
  • , C. RosaAffiliated withEmpresa de Desenvolvimento Mineiro SA (EDM)
  • , J. MatosAffiliated withLNEG
  • , J. CarvalhoAffiliated withLaboratório Nacional de Energia e Geologia (LNEG)
  • , J. M. Castello-BrancoAffiliated withGeology and Geotechnics Consultores Lda.
  • , M. J. BatistaAffiliated withLaboratório Nacional de Energia e Geologia (LNEG)
  • , I. GranadoAffiliated withLaboratório Nacional de Energia e Geologia (LNEG)
  • , J. T. OliveiraAffiliated withLaboratório Nacional de Energia e Geologia (LNEG)
  • , V. AraújoAffiliated with
    • , Z. PereiraAffiliated withLNEG
    • , P. RepresasAffiliated withLaboratório Nacional de Energia e Geologia (LNEG)
    • , A. R. SoláAffiliated withLaboratório Nacional de Energia e Geologia (LNEG)
    • , P. SousaAffiliated withLNEG

Abstract

3D, 4D and predictive geological modelling, including all known geoscientific data, were applied to the 100 × 25 km large Neves Corvo project area located in the Portuguese part of the Iberian Pyrite Belt. The lowermost unit in the area is the Givetian to Famennian-Strunian Phyllite-Quartzite Group (PQG), which is overlain by three SE-plunging volcanic axes with the Strunian to Visean Volcanic Sedimentary Complex (VSC), hosting in its lower sequence the Neves Corvo VHMS giant deposit. The VSC is covered with mid late Visean and Serpukhovian to Bashkirian flysch rocks [Mértola and Mira formations of the Baixo Alentejo Flysch Group (BAFG), respectively]. Six NE-SW deep 2D reflection seismic profiles acquired by LNEG between Neves Corvo mine and the Spanish border (60 km to the SE) during the ProMine project, allowed to extend a 3D-model of the Neves Corvo main thrust (that brings VSC rocks onto Mértola Fm. very close to VHMS ores) throughout the eastern part of the area. NE-SW to ENE-WSW (sinistral) and N-S to NNW-SSE (dextral) late Variscan strike-slip oblique faults (a few >5 km deep) displaced all former geological units and structures, as shown by the 3D models. In late Variscan time, small vein-type Cu (and other metals) deposits were emplaced along them.

The 4D model enabled to establish a clear age sequence of mineralization types, inferring also that VHMS mineralization may possibly exist at depth between the Neves Corvo mine and the Alcoutim sector (near the Spanish border). The 3D predictive model, constructed exclusively for the restricted area of the Neves Corvo mine, pinpoints, both through the 3D-density (from gravity inversion) and the % Cu-drill hole-based block diagrams, not only the known Neves Corvo orebodies, but also other possible extensions. The regional extension of the Neves Corvo model increases significantly the overall exploration potential of the whole IPB region in this study.