Status of basement terranes in orogens. Insights from the Cadomian domain of the North Armorican Variscides, Western France.

Type Article
Date 2021-05
Language English
Author(s) Le Gall B.ORCID1, Authemayou C.1, Graindorge David1, Duperret A.2, Kaci T.ORCID2, Ehrhold AxelORCID3, Schmitt T.4
Affiliation(s) 1 : IUEM, UMR 6538 CNRS Géosciences OcéanF‐29280 Plouzané, France
2 : UMR 6294, LOMC CNRS/UNILEHAVRE F‐76600 Le Havre, France
3 : IFREMER, Centre de Bretagne GM Géodynamique et Enregistrement Sédimentaire, F‐29280 Plouzané, France
4 : Service Hydrographique Océanographique de la Marine, F‐29228 Brest, France
Source Tectonics (0278-7407) (American Geophysical Union (AGU)), 2021-05 , Vol. 40 , N. 5 , P. e2020TC006578 (25p.)
DOI 10.1029/2020TC006578
WOS© Times Cited 1
Keyword(s) Cadomian terranes, deformation, North Armorican massif, onshore, offshore approach, Variscan overprint
Abstract

The stable vs mobile behaviour of basement terranes in orogens is discussed about the North Armorican Cadomian‐floored domain (NAD) in the Armorican Variscides, Western France. Our onshore/offshore structural study demonstrates the heterogeneous nature of the NAD which comprises: i) a southern part which remained stable during both the Paleozoic extensional and compressional (Variscan) events and ii) a northern part which was initially the locus of extensive Paleozoic sedimentary basins before recording Variscan deformation. Our work supplies a more complete structural picture of the Variscan pattern in Northern Armorica as a whole: i) as precising the spatial distribution of Variscan strain, ii) as emphazing its importance with a bulk shortening estimated at 30 % in the North Cotentin fold‐and‐thrust belt and iii) as regarding a newly identified pattern of sinistral ductile shear zones in the Morlaix area as lateral ramps that parallel the western edge of the rigid (southern) Cadomian block in a indenter kinematic setting. At a wider scale, compiling structural dataset from others Cadomian terranes in the Variscan belt of Central (Bohemia) and Western (Iberia) Europe leads us to hypothetize that their stability vs reworking during the Variscan orogeny relies primarily on the mechanical/thermal state of their lithosphere at the end of the Paleozoic extensional stage.

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Le Gall B., Authemayou C., Graindorge David, Duperret A., Kaci T., Ehrhold Axel, Schmitt T. (2021). Status of basement terranes in orogens. Insights from the Cadomian domain of the North Armorican Variscides, Western France. Tectonics, 40(5), e2020TC006578 (25p.). Publisher's official version : https://doi.org/10.1029/2020TC006578 , Open Access version : https://archimer.ifremer.fr/doc/00694/80589/