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Late orogenic collapse and thermal doming in the northern Gondwana margin incorporated in the Variscan Chain: a case study from the Ozieri Metamorphic Complex, northern Sardinia, Italy

Casini, Leonardo and Oggiano, Giacomo (2008) Late orogenic collapse and thermal doming in the northern Gondwana margin incorporated in the Variscan Chain: a case study from the Ozieri Metamorphic Complex, northern Sardinia, Italy. Gondwana Research, Vol. 13 (3), p. 396-406. ISSN 1342-937X. Article.

Full text not available from this repository.

DOI: 10.1016/j.gr.2007.11.004

Abstract

A branch of the South European Variscan chain is noticeably exposed in Sardinia. The early stage of collision between the Northern Gondwana margin and the Armorica Terrane Assemblage (ATA) generated syn-metamorphic folding and thrusting. The evidences of such deformation are well preserved in the nappe zone, a structural domain characterized by stacking of different tectonic units under metamorphism of Barrovian greenschist facies. A late, post-nappe, shortening, under retrograde metamorphic conditions, gave rise to wide, upright, N120-N160 trending antiforms that control the trend of the chain. The structural analysis of the Ozieri Metamorphic Complex (OMC) shows evidence of an important phase of late-Variscan extensional tectonics. Deformation results in, the formation of oppositely dipping, normal shear zones, which developed at upper and middle structural level along the limbs of major regional antiforms causing fabric reactivation, crustal thinning, and exhumation of the OMC core. Within the OMC, the activity of the shear zones was coeval with HT-LP metamorphism as suggests the occurrence of syn-kinematic cordierite + andalusite ± sillimanite + biotite. Whereas syntectonic dykes and a tonalite body in the deeper part of the OMC indicate that early emplacement of melt along shear zones and/or in the antiform hinges possibly supplied the heat for the anomalous thermal gradient and triggered the exhumation of a core complex-like structure.

Item Type:Article
ID Code:1992
Status:Published
Refereed:Yes
Uncontrolled Keywords:HT-LP metamorphic complexes, post-orogenic collapse, northern Sardinia, extensional tectonics, Variscan Chain
Subjects:Area 04 - Scienze della terra > GEO/03 Geologia strutturale
Divisions:001 Università di Sassari > 01 Dipartimenti > Scienze botaniche, ecologiche e geologiche
Publisher:Elsevier
ISSN:1342-937X
Deposited On:18 Aug 2009 10:06

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