Cambrian Age 3 small shelly fossils from the Terrades inlier, southern Pyrenees, Spain: Biostratigraphic and paleobiogeographic implications

Abstract

The Cambrian stratigraphic succession of the Pyrenees (SW Europe) has undergone a complex Variscan and Alpine tectonothermal history leading to marked metamorphism and development of cleavage networks, which might partly explain the lack of Cambrian fossiliferous beds. This gap has traditionally precluded its paleobiogeographic and biostratigraphic relationships with other neighboring peri-Gondwanan units. Correlations are only based on lithostratigraphic comparisons and radiometric constraints. In this general scheme, the Terrades inlier (Gerona Province, Spain) provides the only significant and indisputable ‘early Cambrian’ fossil record of the Pyrenees. This predominantly siliciclastic outcrop consists of multiple patch reefs and bioherms having yielded archeocyaths dated at Cambrian Epoch 2, Age 3. This paper describes, for the first time, the microfossil assemblage included in the archeocyathan-microbial reefal complex that crops out in the Terrades inlier to clarify its age and affinities with surrounding tectonostratigraphic units. Reefal flanks of patch reefs have yielded bradoriids, brachiopods, molluscs, tommotiids, chancelloriids, hyoliths, and the problematic fossil (and chronostratigraphically significant) Rhombocorniculum cancellatum Cobbold, 1921. In addition to confirming the previously assigned age of the succession, the recovered fauna emphasizes strong affinities with the surrounding Occitan Domain (Montagne Noire, southern Massif Central, France) and Sardinia (Italy). Along with lithostratigraphic comparison and tectonic considerations, this further supports the recent reconstructions positioning the Pyrenean domain between the Montagne Noire (to the southwest) and Sardinia (further to the northeast) on the Gondwana margin during Cambrian times.

Shifts in the Ediacaran to Lower Ordovician sedimentary zircon provenances of Northwest Gondwana: the Pyrenean files

“…The basement of south-western Europe includes, among others, the core of the Iberian and Armorican massifs, the French Massif Central and the Pyrenees. Recent palaeogeographic re-appraisals based on litho- (Padel et al, 2018) and biostratigraphic revisions (Wallet et al, 2022), completed with correlations of the mid-Ordovician Sardic Phase (Álvaro et al, 2020 and references within) have placed the Ediacaran-Ordovician Pyrenean margin of Gondwana as a lateral continuity of neighbouring domains, such as the Occitan Domain (including Montagne Noire and the Mouthoumet massifs) and SW Sardinia. As a result, the Cambrian Pyrenean Basin has been recently integrated in the reconstruction of pre-Variscan palaeogeographic puzzles along NW Gondwana, after combining structural, magmatic and stratigraphic comparisons (e.g.…”