Syncontractional extension and exhumation of deep crustal rocks in the east Greenland Caledonides

Abstract

Abstract.Tectonic models for the North Atlantic Caledonides typically show Baltica being subducted below Laurentia prior to late orogenic collapse and exhumation of deep crustal rocks, conveniently explaining the high-and ultrahighpressure provinces in the Scandinavian Caledonides. However, these models offer no tectonic explanation for the deformation and overthickening of the overriding Laurentian plate.

Evidence from Rb–Sr mineral ages for multiple orogenic events in the Caledonides of Shetland, Scotland

“…An alternative solution is that the western margin of the Caledonides in NW Shetland is located some distance offshore of North Roe. However, we acknowledge that we cannot preclude significant extensional displacement(s) across the Uyea Shear Zone, and note the close correspondence in age to extensional detachments in East Greenland and Scandinavia (Krabbendam & Dewey 1998;Hartz et al 2001;Fossen 2010). The tectonic significance of the Uyea Shear Zone is therefore uncertain at present.…”

“…In both Norway and East Greenland there is evidence for metamorphism up to eclogite facies and examples of hinterland-directed synconvergent extensional shear zones, perhaps indicative of 'channel flow' (e.g. Hartz et al 2001;Andresen et al 2007;Grimmer et al 2015). In mainland Scotland, the Northern Highland Terrane (Fig.…”

The Tooth of Time: Lauge Koch's Last Lecture

“…If the crust was thinned yet is of normal thickness today, it was either thickened again after being thinned or was thicker than normal before being thinned. Orogenic collapse, the thinning of tec-tonically overthickened crust, is a logical inference from East Greenland structure, when viewed as being adjacent to the great thrust nappes of western Norway and in the context of Caledonian collision between Baltica and Laurentia (McClay et al 1986;Hartz and Andresen 1995;Torsvik 1998;Hartz et al 2001;Gilotti and McClelland 2008;Henriksen and Higgins 2008;Cocks and Torsvik 2011). The idea of 'nappe tectonics in an extending orogen' was developed 3 km east of his office at Harvard (Wernicke 1981(Wernicke , 2009), but I know of nothing to suggest that Haller ever viewed East Greenland tectonics in a pre-Atlantic drift framework.…”

Geotermobarometria de granulitos do Cinturão Ribeira na porção norte do estado do Rio de Janeiro: seção Italva (RJ) – Patrocínio do Muriaé (MG)

“…Este processo também é atribuído ao escape lateral de massa e à extrusão tectônica (Jones et al 1997), como observado nos cinturões Caledonides (Lyberis & Mamby 1999, Harz et al 2001, Alpes (Ratschbacher et al 1991, Mancktelow 1992, Himalaias (Inger 1998) e Ribeira .…”