RT Journal Article
T1 Cadomian metabasites of the Eastern Pyrenees revisited
A1 Pujol Solà, Núria
A1 Casas Tuset, Josep María
A1 Proenza, Joaquín A.
A1 Blanco Quintero, Idael Francisco
A1 Druguet, Elena
A1 Liesa Torre Marín, Montserrat
A1 Román Alpiste, M.J.
A1 Álvaro, J.J.
AB 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.
PB Instituto de Ciencias de la Tierra "Jaume Almera" (Barcelona)
SN 1695-6133
YR 2022
FD 2022-11-25
LK https://hdl.handle.net/20.500.14352/72878
UL https://hdl.handle.net/20.500.14352/72878
LA eng
NO Ministerio de Ciencia, Innovación y Universidades
NO Agencia   Estatal de Investigación
NO Fondo Europeo de Desarrollo Regional, Unión Europea
NO Universitat  de  Barcelona
NO Ministerio de Universidades/
DS Docta Complutense
RD 16 may 2024