Cadomian metabasites of the Eastern Pyrenees revisited

Authors

  • Núria Pujol-Solà Departament de Mineralogia, Petrologia i Geologia Aplicada. Facultat de Ciències de la Terra, Universitat de Barcelona. Carrer Martí i Franquès, s/n, 08028, Barcelona, Spain
  • Josep Maria Casas Departament de Dinàmica de la Terra i de l’Oceà. Facultat de Ciències de la Terra, Universitat de Barcelona. Carrer Martí i Franquès, s/n, 08028, Barcelona, Spain
  • Joaquín A. Proenza Departament de Mineralogia, Petrologia i Geologia Aplicada. Facultat de Ciències de la Terra, Universitat de Barcelona. Carrer Martí i Franquès, s/n, 08028, Barcelona, Spain
  • Idael F. Blanco-Quintero Departamento de Ciencias de la Tierra y del Medio Ambiente. Facultad de Ciencias, Universidad de Alicante. Carretera de San Vicente del Raspeig s/n, 03690, Alicante, Spain
  • Elena Druguet Departament de Geologia, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
  • Montserrat Liesa Departament de Mineralogia, Petrologia i Geologia Aplicada. Facultat de Ciències de la Terra, Universitat de Barcelona. Carrer Martí i Franquès, s/n, 08028, Barcelona, Spain
  • Manuel J. Román-Alpiste Instituto Andaluz de Ciencias de la Tierra (CSIC-UGR), Avda. de las Palmeras 4, E-18100 Armilla, Granada, Spain
  • J. Javier Álvaro Instituto de Geociencias (CSIC-UCM), Dr. Severo Ochoa 7, 28040 Madrid, Spain

DOI:

https://doi.org/10.1344/GeologicaActa2022.20.13

Keywords:

Pan-African, Cadomian, Inherited zircon, Peri-Gondwanan, Iberian Massif

Abstract

This study presents a new geochemical, petrological, and geochronological U–Pb dataset from Ediacaran metabasites of the Canigó and Cap de Creus massifs, Eastern Pyrenees. The rocks are composed of calcic amphibole + plagioclase + chlorite + epidote ± quartz plus titanite + apatite + ilmenite ± biotite ± rutile as accessory phases and show relict igneous textures. Peak pressure-temperature determinations share common conditions, ranging 452–482ºC and 5.2–7.7kbar. These intermediate P-T conditions suggest Barrovian-type metamorphism, most likely related to a collisional setting. The metabasites correspond to evolved basaltic rocks (Mg#<0.55) with moderate TiO2 content (up to 2.08wt.%) and relatively low Cr (43–416ppm). The rocks are moderately enriched in light rare earth elements (LREE) relative to heavy rare earth elements (HREE) (average (La/Lu)n of 2.7) and the N-MORB normalized multi-element patterns show negative slopes, with prominent negative Nb anomalies ((Nb/La)NMORB=0.33–0.78). These variations are akin to island arc tholeiites generated in back-arc basins and to other metabasites described in the Eastern Pyrenees with a putative Ediacaran age, and they differ from the Ordovician tholeiitic metabasites from the Canigó massif, which derived from a contaminated E-MORB source. The positive ƐNd(T) values (0.82–3.05) of the studied metabasites preclude a notable contribution from an older continental crust. U-Pb dating (LA-ICP-MS) of one chlorite-rich schist sample in contact with the metabasites from the Canigó massif yielded a main peak at ca. 632Ma. We argue that the Cadomian metabasites from the Pyrenees formed during back-arc extension in the continental margin of Gondwana and were later affected by (probably early Variscan) medium-P metamorphism before the HT-LP metamorphism classically described in the Pyrenees.

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Published

2022-11-25

Issue

Section

The panafrican and cadomian orogenies in North Africa and western Europe