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Geodynamic evolution of the Jurassic Ligurian Tethys viewed from the mantle perspective

Giovanni B. Piccardo
Geodynamic evolution of the Jurassic Ligurian Tethys viewed from the mantle perspective (in Alps and Apennines; a natural laboratory of structural geology and geodynamics; papers presented at the International meeting in honour of Gaetano Giglia and Tonino Decandia, Giovanni Capponi (editor), Michele Marroni (editor), Enrico Tavarnelli (editor) and Fernando Calamita (editor))
Italian Journal of Geosciences (June 2009) 128 (2): 565-574

Abstract

Present knowledge on structure and petrology of the various masses of Alpine-Apennine ophiolitic peridotites provides evidence that Triassic-Jurassic rifting and spreading in the Ligurian-Piemontese domain was accomplished through successive stages of lithosphere evolution well recorded in the mantle peridotites. The early stages of rifting, active during Triassic times, were dominated by overall extension and thinning of the continental lithosphere and exhumation of the sub-continental lithospheric mantle via km-scale extensional shear zones. This represents a tectonic-dominated stage. Subsequent stages of rifting, starting from Early Jurassic times, were characterized by asthenosphere adiabatic upwelling and decompression melting triggered by lithosphere extension and thinning. These rifting stages were dominated by the interaction of tectonic and magmatic processes. MORB-type melts from the asthenosphere percolated through the overlying lithospheric mantle along the axial zone of the future oceanic basin and large volumes of the extending mantle lithosphere were modified by melt-rock interaction. Melt percolation induced the thermo-mechanical erosion of the mantle lithosphere resulting in the weakening and softening of the lithosphere. It was a controlling factor in the transition from distributed continental deformation to localised oceanic spreading. MORB magmas intruded the sub-continental mantle along the axial zone of the future oceanic basin forming km-scale gabbroic bodies. The oceanic stage (i.e. formation of the oceanic lithosphere) was characterized by complete failure of the continental crust during Late Jurassic times, and by the direct exposure of mantle peridotites on the sea-floor. Sub-continental peridotites were exposed at ocean-continent transition (OCT) zones and melt-modified sub-continental peridotites at more internal oceanic (MIO) settings. MORB magmas reached the sea-floor, extruded above the mantle peridotites to form the oceanic lithosphere (i.e. the association of sub-continental peridotites and Jurassic MORB basalts) of the Ligurian Tethys basin.


ISSN: 2038-1719
Coden: BOGIAT
Serial Title: Italian Journal of Geosciences
Serial Volume: 128
Serial Issue: 2
Title: Geodynamic evolution of the Jurassic Ligurian Tethys viewed from the mantle perspective
Title: Alps and Apennines; a natural laboratory of structural geology and geodynamics; papers presented at the International meeting in honour of Gaetano Giglia and Tonino Decandia
Author(s): Piccardo, Giovanni B.
Author(s): Capponi, Giovannieditor
Author(s): Marroni, Micheleeditor
Author(s): Tavarnelli, Enricoeditor
Author(s): Calamita, Fernandoeditor
Affiliation: Universita di Genova, Dipartimento per lo Studio del Territorio e delle sue Risorse, Genoa, Italy
Pages: 565-574
Published: 200906
Text Language: English
Summary Language: Italian
Publisher: Societa Geologica Italiana, Rome, Italy
Meeting name: Alps and Apennines; a natural laboratory of structural geology and geodynamics; International meeting in honour of Gaetano Giglia and Tonino Decandia
Meeting location: Pisa, ITA, Italy
Meeting date: 20071025Oct. 25-26, 2007
References: 78
Accession Number: 2011-009281
Categories: Structural geologyIgneous and metamorphic petrology
Document Type: Serial Conference document
Bibliographic Level: Analytic
Illustration Description: illus. incl. sketch map
N43°45'00" - N44°40'00", E07°45'00" - E10°04'60"
Country of Publication: Italy
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 201106
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