Geological context and origin of the mineralization of the historic and prehistoric iron mines in the Gavà area, Catalonia, NE Iberian Peninsula

  1. Yael Díaz-Acha
  2. Marc Campeny 1
  3. Joan Carles Melgarejo 2
  4. Joaquín A. Proenza 2
  5. Aleu Andreazini 2
  6. Míriam Pastor 2
  7. Núria Pujol-Solà 2
  8. Sandra Amores 2
  9. Xu Jingyao 2
  10. Júlia Farré 2
  11. Josep Bosch 3
  12. Saleh Lehbib 2
  13. Lisard Torró 2
  14. Montgarri Castillo-Oliver 2
  15. Antoni Camprubí 4
  16. Cristina Villanova-de-Benavent 5
  1. 1 Museu de Ciències Naturals de Barcelona
  2. 2 Universitat de Barcelona
    info

    Universitat de Barcelona

    Barcelona, España

    ROR https://ror.org/021018s57

  3. 3 Museu de Gavà
  4. 4 Universidad Nacional Autónoma de México
    info

    Universidad Nacional Autónoma de México

    Ciudad de México, México

    ROR https://ror.org/01tmp8f25

  5. 5 University of Brighton
    info

    University of Brighton

    Brighton, Reino Unido

    ROR https://ror.org/04kp2b655

Journal:
Boletín de la Sociedad Geológica Mexicana

ISSN: 1405-3322

Year of publication: 2019

Tome: 71

Issue: 2

Pages: 321-342

Type: Article

DOI: 10.18268/BSGM2019V71N2A6 DIALNET GOOGLE SCHOLAR lock_openOpen access editor

More publications in: Boletín de la Sociedad Geológica Mexicana

Abstract

Mining for iron resources in the Gavà area of Catalonia occurred intermittently during the Iberian and Roman epochs, the Middle Ages, and continuing until the industrial era, as evidenced by historical and archaeological documents.. Iron mining in this area could have occurred even earlier, during the Neolithic period. Iron ores were formed in two stages: (1) a regional hydrothermal alteration associated with Hercynian thrusts that produced the ankeritization of limestones within the Paleozoic series, and (2) the karstic replacement of these iron-rich carbonates during the Pliocene and Quaternary by means of supergenic fluids that produced ochres with goethite and hematite. The style of mineralization largely depends on the characteristics of the replaced protolith, and three styles of mineralization can be defined: (1)The supergenic replacement of ankeritized massive Pridolian limestones only produced local replacements that were restricted to structural or stratigraphic discontinuities, therefore, the mineralization has reduced dimensions and occurs as irregular veinlets or pipes; (2) The replacement of interbedded ankeritized limestones and pyrite-bearing shales (Lockovian) produced massive ores in pod-shaped bodies rich in silica impurities derived from the altered shales; and (3) The replacement of carbonates overthrust by pyrite- and phosphate-rich shales favored the formation of massive stratabound deposits, which are the largest and highest grade deposits in the study area, and may be locally enriched in minerals of the alunite supergroup and Ca- and Fe-rich phosphates. Outcrops of all of these styles of mineralization were mined by the Iberian cultures, during the roman period and in the Middle Ages, taking advantage of the relatively high metallurgical quality of the ores.Therefore, the exploitation during these epochs was artisanal by means of trenches or small pits. In contrast, during the industrial era only the massive stratabound deposits were exploited in open pits and underground galleries.