Petrogenesis of basalts and gabbros from an ancient continent–ocean transition (External Liguride ophiolites, Northern Italy)

Montanini, Alessandra; Tribuzio, R.; Vernia, L.

doi:10.1016/j.lithos.2007.09.007

Cited by 72 publications

(68 citation statements)

References 75 publications

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“…This hypothesis conforms to the interpretations proposed for ophiolite sequences of the Alps and Apennines as shown in [24][25][26][27][28][29][30][31]. Worth of note, recent oceanographic studies emphasize that the petrological characteristics of the current day oceanic rocks are more heterogeneous to that assumed in the past [32][33][34][35][36] and, hence, the "ophiolite concept" interpreted as "fossil oceanic lithosphere with a unique and complete lithologic sequence" has also to be revisited and updated [33].…”

Section: Introductionsupporting

confidence: 91%

The Betic Ophiolites and the Mesozoic Evolution of the Western Tethys

et al. 2017

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Abstract:The Betic Ophiolites consist of numerous tectonic slices, metric to kilometric in size, of eclogitized mafic and ultramafic rocks associated to oceanic metasediments, deriving from the Betic oceanic domain. The outcrop of these ophiolites is aligned along 250 km in the Mulhacén Complex of the Nevado-Filábride Domain, located at the center-eastern zone of the Betic Cordillera (SE Spain). According to petrological/geochemical inferences and SHRIMP (Sensitive High Resolution Ion Micro-Probe) dating of igneous zircons, the Betic oceanic lithosphere originated along an ultra-slow mid-ocean ridge, after rifting, thinning and breakup of the preexisting continental crust. The Betic oceanic sector, located at the westernmost end of the Tethys Ocean, developed from the Lower to Middle Jurassic (185-170 Ma), just at the beginning of the Pangaea break-up between the Iberia-European and the Africa-Adrian plates. Subsequently, the oceanic spreading migrated northeastward to form the Ligurian and Alpine Tethys oceans, from 165 to 140 Ma. Breakup and oceanization isolated continental remnants, known as the Mesomediterranean Terrane, which were deformed and affected by the Upper Cretaceous-Paleocene Eo-Alpine high-pressure metamorphic event, due to the intra-oceanic subduction of the Jurassic oceanic lithosphere and the related continental margins. This process was followed by the partial exhumation of the subducted oceanic rocks onto their continental margins, forming the Betic and Alpine Ophiolites. Subsequently, along the Upper Oligocene and Miocene, the deformed and metamorphosed Mesomediterranean Terrane was dismembered into different continental blocks collectively known as AlKaPeCa microplate (Alboran, Kabylian, Peloritan and Calabrian). In particular, the Alboran block was displaced toward the SW to occupy its current setting between the Iberian and African plates, due to the Neogene opening of the Algero-Provençal Basin. During this translation, the different domains of the Alboran microplate, forming the Internal Zones of the Betic and Rifean Cordilleras, collided with the External Zones representing the Iberian and African margins and, together with them, underwent the later alpine deformation and metamorphism, characterized by local differences of P-T (Pressure-Temperature) conditions. These Neogene metamorphic processes, known as Meso-Alpine and Neo-Alpine events, developed in the Nevado-Filábride Domain under Ab-Ep amphibolite and greenschists facies conditions, respectively, causing retrogradation and intensive deformation of the Eo-Alpine eclogites.

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Section: Introductionsupporting

confidence: 91%

The Betic Ophiolites and the Mesozoic Evolution of the Western Tethys

et al. 2017

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“…6) are comparable to the worldwide modern MORB patterns, which show decreasing Ti, Mn, Na, P, and increasing A1, Ca, Ni, Cr values with increasing Mg#s (Wilkinson, 1982). N-MORB extrusive rocks in the External Liguride ophiolites in the Apennines (Italy) (Montanini et al, 2008) and in the Alpine ophiolites in Corsica (France) display correlations similar to those of our dike samples from the South and North Baer and Cuobuzha massifs. The External Liguride and Corsican ophiolites represent a mid-ocean ridge-generated Jurassic oceanic lithosphere (Saccani et al, 2008;Furnes, 2011, 2014).…”

Section: Mantle Melt Source and Magma Evolution Of Mafic Dikes Mantlesupporting

confidence: 83%

Melt evolution of upper mantle peridotites and mafic dikes in the northern ophiolite belt of the western Yarlung Zangbo suture zone (southern Tibet)

et al. 2018

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The Yarlung Zangbo suture zone (YZSZ) in southern Tibet is divided by the Zhongba terrane into two subparallel belts in its western end. The northern belt (NB) is tectonically juxtaposed against an accretionary prism complex and the Gangdese magmatic arc of Eurasia along dextral oblique-slip faults. Peridotite massifs in this belt are intruded by mafic dikes, providing critical geochemical, geochronological, and isotopic information about the melting-melt extraction history of the Tethyan mantle. Peridotites consist of harzburgite and clinopyroxene harzburgite with minor Iherzolite and dunite-chromitite. Dolerite and microgabbro dikes crosscutting these peridotites display U-Pb zircon ages of 128-122 Ma, and show normal mid-oceanic ridge basalt (N-MORB) like rare earth element patterns with negative Nb, Ta, and Ti anomalies, high ε Nd (t) Pb of 37.724-37.845, suggesting that their N-MORB-like mantle source was modified by island arc melts. Slab rollback-induced extension in an arc-trench system along the Eurasian continental margin led to ~7%-12% partial melting of subduction-influenced, spinel lherzolite peridotites, producing dike magmas. The NB peridotite massifs and ophiolites thus represent a suprasubduction zone oceanic lithosphere formed in close proximity to the late Mesozoic active continental margin of Eurasia.

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“…Myers, 1980;Jolly and Sanderson, 1995;Klausen, 2006). (ii) Whereas most correlative rift-related mafic rocks in the Scandinavian Caledonides have enriched geochemical signatures similar to ocean island basalt (OIB) and enriched mid-ocean ridge basalt, the gabbro and dolerite of the KIC have compositions spanning transitional-to N-MORB, similar to dolerite and gabbro in ancient OCTs (Desmurs et al, 2002;Montanini et al, 2008), and to earliest ocean-floor basalts recovered from the Iberian and Newfoundland passive margins (e.g. Seifert et al, 1997;Müntener and Manatschal, 2006;Fitton, 2007).…”

Section: Age Of the Kicmentioning

confidence: 99%

Root zone of a continental rift: the Neoproterozoic Kebnekaise Intrusive Complex, northern Swedish Caledonides

Kirsch

Svenningsen²

2015

GFF

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Mafic magmatic rocks formed between ca. 615 and 560 Ma along the Neoproterozoic margins of Baltica and Laurentia are classically attributed to continental rifting heralding the opening of the Iapetus Ocean. We report new data for the Kebnekaise Intrusive Complex (KIC) exposed in the Seve Nappes in northern Sweden. The KIC consists of sheeted dolerite dykes and gabbroic bodies with mutually intrusive relations. Major and trace element data exhibit a transitional-to normal-mid-ocean-ridge basalt-type geochemical signature. Differentiation processes and late-stage liquid immiscibility of a tholeiitic melt are considered to account for the compositional range exhibited by the KIC igneous rocks. U/Pb SIMS geochronological data from zircon rims yield an emplacement age of 578^9 Ma. The KIC is thus younger and more depleted than coeval mafic rocks found in the Seve Nappe, and is interpreted to represent a highlevel magma plumbing system in a late-stage continental rift. The composition and volume of rift-related igneous rocks in the Seve Nappes are inconsistent with a mantle plume origin, but are thought to record progressive lithospheric thinning and increasing involvement of an asthenospheric mantle component.

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Petrogenesis of basalts and gabbros from an ancient continent–ocean transition (External Liguride ophiolites, Northern Italy)

Cited by 72 publications

References 75 publications

The Betic Ophiolites and the Mesozoic Evolution of the Western Tethys

The Betic Ophiolites and the Mesozoic Evolution of the Western Tethys

Melt evolution of upper mantle peridotites and mafic dikes in the northern ophiolite belt of the western Yarlung Zangbo suture zone (southern Tibet)

Root zone of a continental rift: the Neoproterozoic Kebnekaise Intrusive Complex, northern Swedish Caledonides

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