Cadomian metabasites of the Eastern Pyrenees revisited
Pujol-Solà, Núria (Universitat de Barcelona. Departament de Mineralogia, Petrologia i Geologia Aplicada)
Casas Tuset, Josep Maria (Universitat de Barcelona. Departament de Dinàmica de la Terra i de l'Oceà)
Proenza, Joaquín A (Universitat de Barcelona. Departament de Mineralogia, Petrologia i Geologia Aplicada)
Blanco-Quintero, Idael Francisco (Universitat d'Alacant. Departament de Ciències de la Terra i del Medi Ambient)
Druguet, Elena (Universitat Autònoma de Barcelona. Departament de Geologia)
Liesa Torre-Marín, Montserrat (Universitat de Barcelona. Departament de Mineralogia, Petrologia i Geologia Aplicada)
Román-Alpiste, Manuel J. (Consejo Superior de Investigaciones Científicas. Instituto Andaluz de Ciencias de la Tierra)
Álvaro, Jose Javier (Consejo Superior de Investigaciones Científicas. Instituto de Geociencias)

Data:	2022
Resum:	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.
Ajuts:	Agencia Estatal de Investigación CGL2017-87631-P Agencia Estatal de Investigación PGC2018-093903-B-C22
Nota:	Acknowledgement. This research was financially supported by the Spanish Projects CGL2017-87631-P and PGC2018-093903-B-C22, Ministerio de Ciencia, Innovación y Universidades/Agencia Estatal de Investigación/Fondo Europeo de Desarrollo Regional, Unión Europea. Additional funding was provided by a Margarita Salas grant to NPS by the Universitat de Barcelona with funds from the Ministerio de Universidades/NextGenerationEU/PRTR/Plan de recuperación, transformación y resiliencia. We are deeply indebted to María José Aguilar Pérez for sample preparation and processing. Reviewers Antonio Castro and M. Francisco Pereira, and editor Martim Chichorro are deeply acknowledged for their constructive criticism and their very useful comments, which have helped to greatly improve the quality of the present manuscript.
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan aquestes es distribueixin sota la mateixa llicència que regula l'obra original i es reconegui l'autoria de l'obra original.
Llengua:	Català
Document:	Article ; recerca ; Versió publicada
Matèria:	Pan-African ; Cadomian ; Inherited zircon ; Peri-Gondwanan ; Iberian Massif
Publicat a:	Geologica acta, Vol. 20 (2022) , p. 1-III (The panafrican and cadomian orogenies in North Africa and western Europe) , ISSN 1696-5728

Adreça alternativa: https://raco.cat/index.php/GeologicaActa/article/view/411934
Adreça alternativa: https://raco.cat/index.php/GeologicaActa/article/view/408498
Adreça alternativa: https://revistes.ub.edu/index.php/GEOACTA/article/view/39230
DOI: 10.1344/GeologicaActa2022.20.13

30 p, 7.5 MB

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