The Late Neoproterozoic magmatism in the Ediacaran series of the Eastern Pyrenees: new ages and isotope geochemistry

Abstract

Geochronological U-Pb (LA-ICP-MS), geochemical and isotopic data from metavolcanic felsic rocks of the Canigó and Cap de Creus massifs in the Eastern Pyrenees provide evidence of an Ediacaran magmatic event lasting 30 m.y. in NE Iberia. Data also constrain the age of the Late Neoproterozoic succession in the Cap de Creus massif, where depositional ages range from 577 to 558 Ma, and in the Canigó massif, where the data (575 to 568 Ma) represent minimum ages. Geochemistry indicates that the rocks were formed in a back-arc environment and record a fragment of a long-lived subduction-related magmatic arc (620 to 520 Ma) in the active northern Gondwana margin. The homogeneity shown by all these crustal fragments along this margin suggests that the individualization of the Pyrenean basement from the Iberian Massif started later, probably during its transition from an active to a passive margin in Cambro-Ordovician times.

Cadomian volcanosedimentary complexes across the Ediacaran–Cambrian transition of the Eastern Pyrenees, southwestern Europe

“…The Nyer Formation is overlain by the Olette Formation (Álvaro et al in press), a monotonous shaly succession with interbedded feldspar-rich tuffs (VS2 sensu Laumonier et al 2015a, b, c). The latter yielded variable U-Pb zircon ages, ranging from 575.1 ± 3.6 Ma in the Puigmal unit (Casas et al 2015) to 548 ± 8 Ma in the Roc de Frausa unit, and 560 ± 11 Ma in the Cap de Creus unit (Castiñeiras et al 2008). Despite the different U-Pb methods used by the authors, these ages suggest a protracted and episodic volcanic activity throughout the Ediacaran.…”

“…The heterolithic Pic de la Clape Formation has been sampled and studied at seven localities in the Puigmal unit, which are, from west to east: Pic de Finestrelles summit, along the road GIV-5265 in the vicinity of Tregurà village (locality sampled by Casas et al 2015), the Fabert village, the Molló-Setcases transect, the Pic de la Clape and Tour de Mir summits, and the Coll d'Ares pass (Figs. 1,2).…”

“…1). The dominance of unfossiliferous fine-grained siliciclastic sediments interrupted by marbles and scattered igneous rocks has rendered correlation and dating difficult b Geological map of the study area; modified from Baudin et al (2008), Laumonier et al (2015a, b) and Casas et al (2015) 1 3 (Guitard et al 1998;Deloule et al 2002;Laumonier et al 2004;Cocherie et al 2005;Castiñeiras et al 2008).…”

“…Despite the recent publication of numerous U-Pb zircon ages (e.g. Cocherie et al 2005;Castiñeiras et al 2008;Casas et al 2015;Laumonier et al 2015a, b, c), the age of some Cadomian-related volcanosedimentary complexes included in the Canaveilles Group remains contentious. In addition, many of their correlations are still exclusively based on lithostratigraphic comparisons.…”

“…Unfortunately, zircon U-Pb dating of these rocks yielded some confusion in what was considered a handful of correlatable stratigraphic marker beds encompassing a geochronological interval of ca. 32 my (580-548 Ma; Cocherie et al 2005;Castiñeiras et al 2008;Casas et al 2015;Laumonier et al 2015a, b, c). Therefore, a reassessment of available radiometric ages, completed with new U-Pb dating of zircon obtained by LA-ICP-MS, appears to be necessary for better understanding the volcanogenic record preserved in the Eastern Pyrenees across the Ediacaran-Cambrian transition.…”