Mechanics of thick-skinned Variscan overprinting of Cadomian basement (Iberian Variscides)

• Type: Article in International Scientific Journal
• Date: 2009

Authors

Antonio Ribeiro (Author) Other; Jose Munha (Author) Other; Antonio Mateus (Author) Other; Paulo Fonseca (Author) Other; Eurico Pereira (Author) Other; Fernando Noronha (Author) FCUP; Jose Romao (Author) Other; Jose Rodrigues (Author) Other; Paulo Castro (Author) Other; Carlos Meireles (Author) Other; Narciso Ferreira (Author) Other

Journal

Title: Comptes Rendus - Geoscience

Vol. 341

Pages: 127-139

ISSN: 1631-0713

Publisher: Academie des Sciences

Indexing

ISI Web of Knowledge - 7 Citations

Scopus - 11 Citations

Scientific classification

FOS: Natural sciences > Earth and related Environmental sciences

Other information

Authenticus ID: P-003-NCC

DOI: 10.1016/j.crte.2008.12.003

Abstract (EN): Remnants of the Cadomian basement can be found in the Iberian Variscides (IBVA) in several key sectors of its autochthonous units (composed of Neoproterozoic to Lower Palaeozoic metasedimentary sequences) and within the Continental Allochthonous Terrane (CAT). Comprehensive characterization of these critical exposures shows that the prevailing features are related to major geological events dated within the age range of 620-540 Ma. Indeed, near the Cambrian-Ordovician boundary, the IBVA Internal Zones experienced pervasive basement thinning and cover thickening, reflecting diffusive displacement of intracratonic rifting that continued until Lower Devonian times. In the thick-skinned Internal Zones, Helvetic/Penninic style nappes were generated, whereas flower upright axial structures developed along transpressive, intraplate shear zones. These features contrast with those preserved in the thin-skinned IBVA External Zones, dominated by decollements above (un-)deformed Palaeozoic and Cadomian basement. The inferred attenuation of rheological contrast between Cadomian basement and Palaeozoic cover can be explained by inherited fabrics due to thermal softening operated during the Cambrian-Lower Devonian extensional regime. Deeper decollements (and subsequent strain partitioning) are also expected to develop at the upper-lower crust (and at the Moho?) transition, as imaged by the available seismic profiling and MT surveys. The whole data implies a significant discontinuity between Cadomian and Variscan Cycles that should have constrained subsequent lithospheric evolution. To cite this article: A. Ribeiro et al., C. R. Geoscience 341 (2009).

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 13