scholarly journals Comparative analysis of the sedimentary cover units of the Jurassic Western Tethys ophiolites in the Northern Apennines and Western Alps (Italy): Processes of the formation of mass transport and chaotic deposits during seafloor spreading and subduction zone tectonics

2021 ◽  
Author(s):  
Andrea Festa ◽  
Francesca Meneghini ◽  
Gianni Balestro ◽  
Luca Pandolfi ◽  
Paola Tartarotti ◽  
...  
Keyword(s):  
Comparative Analysis ◽  
Mass Transport ◽  
Subduction Zone ◽  
Sedimentary Cover ◽  
Western Alps ◽  
Seafloor Spreading ◽  
Northern Apennines ◽  
Western Tethys

How does the Alpine belt end between Spain and Morocco ?

2002 ◽  
Vol 173 (1) ◽  
pp. 3-15 ◽  
Author(s):  
André Michard ◽  
Ahmed Chalouan ◽  
Hugues Feinberg ◽  
Bruno Goffé ◽  
Raymond Montigny
Keyword(s):  
Subduction Zone ◽  
Plate Boundary ◽  
Western Alps ◽  
Late Eocene ◽  
African Plate ◽  
Northern Margin ◽  
Thrust Tectonics ◽  
Rif Belt ◽  
Transitional Crust ◽  
Roll Back

Abstract The Betic-Rif arcuate mountain belt (southern Spain, northern Morocco) has been interpreted as a symmetrical collisional orogen, partly collapsed through convective removal of its lithospheric mantle root, or else as resulting of the African plate subduction beneath Iberia, with further extension due either to slab break-off or to slab retreat. In both cases, the Betic-Rif orogen would show little continuity with the western Alps. However, it can be recognized in this belt a composite orocline which includes a deformed, exotic terrane, i.e. the Alboran Terrane, thrust through oceanic/transitional crust-floored units onto two distinct plates, i.e. the Iberian and African plates. During the Jurassic-Early Cretaceous, the yet undeformed Alboran Terrane was part of a larger, Alkapeca microcontinent bounded by two arms of the Tethyan-African oceanic domain, alike the Sesia-Margna Austroalpine block further to the northeast. Blueschist- and eclogite-facies metamorphism affected the Alkapeka northern margin and adjacent oceanic crust during the Late Cretaceous-Eocene interval. This testifies the occurrence of a SE-dipping subduction zone which is regarded as the SW projection of the western Alps subduction zone. During the late Eocene-Oligocene, the Alkapeca-Iberia collision triggered back-thrust tectonics, then NW-dipping subduction of the African margin beneath the Alboran Terrane. This Maghrebian-Apenninic subduction resulted in the Mediterranean basin opening, and drifting of the deformed Alkapeca fragments through slab roll back process and back-arc extension, as reported in several publications. In the Gibraltar area, the western tip of the Apenninic-Maghrebian subduction merges with that of the Alpine-Betic subduction zone, and their Neogene roll back resulted in the Alboran Terrane collage astride the Azores-Gibraltar transpressive plate boundary. Therefore, the Betic-Rif belt appears as an asymmetrical, subduction/collision orogen formed through a protracted evolution straightfully related to the Alpine-Apenninic mountain building.

The Late Cretaceous Asteroussia event as recorded in the Cyclades: a potential key to Western Tethys tectonic evolution

2021 ◽  
Author(s):  
Sonia Yeung ◽  
Marnie Forster ◽  
Emmanuel Skourtsos ◽  
Gordon Lister
Keyword(s):  
Subduction Zone ◽  
Late Cretaceous ◽  
Ore Deposits ◽  
Western Tethys ◽  
Pressure Medium ◽  
Flat Slab Subduction ◽  
Extreme Extension ◽  
Metamorphic Core ◽  
Tectonic Slice ◽  
Ar Geochronology

<div> <p>The Cretaceous arc system formed during closure of West Tethys closure has long been a research focus for crustal geometry and associated ore deposits. Understanding the Africa-Europe motion across time is the key to its resolution. Evidence as to the time that Tethys subduction initiated is preserved in subduction accreted tectonic slices such as in the Gondwanan basement terranes on Ios, Cyclades, Greece. <sup>40</sup>Ar/<sup>39</sup>Ar geochronology in its granitoid basement and the structurally overlying garnet-mica schist tectonic slice identified a Late Cretaceous high pressure, medium temperature (HP–MP) metamorphic event. The timing and metamorphic conditions are comparable with geochronology and metamorphic conditions reported from other Cycladic islands. We suggest the northward extension of the Asteroussia crystalline terrane on Crete should therefore include the Ios basement tectonic slices, thus revising the regional geometry of the terrane stack. The northern part of the Hellenic terrane stack is overlain by individual Cycladic Eclogite-Blueschist terrane slices (e.g., on Ios) and the southern part is underplated by the tectonic units of the external Hellenides (Crete). To make such an architecture possible, we propose a 250-300 km southward jump of the subduction megathrust when the Ios basement terranes were accreted to the European terrane stack. Such a significant leap of the subduction megathrust supports a tectonic mode switch in which crust above the subduction zone was first subjected to shortening followed by a stretching event.  Accretion of the Asteroussia slices to the terrane stack likely commenced at or about ~38 Ma. During accretion, the already stretched and exhumed terranes of the Cycladic Eclogite-Blueschist Unit begun to thrust over the newly accreted Ios basement. The subduction jump had likely been accomplished by ~35 Ma, with rollback recommencing after a period of flat slab subduction followed by slab break off in the new subduction zone. This would allow explanation of the extreme extension that exhumed the Ios basement terrane, with the Asteroussia slices defining the core of the Ios metamorphic core complex, followed by the onset of Oligo-Miocene extension and accompanying magmatism in the Cyclades.</p> </div>

scholarly journals Oligocene-Miocene extension led to mantle exhumation in the central Ligurian Basin, Western Alpine Domain

2019 ◽  
Author(s):  
Anke Dannowski ◽  
Heidrun Kopp ◽  
Ingo Grevemeyer ◽  
Dietrich Lange ◽  
Martin Thowart ◽  
...  
Keyword(s):  
Gravity Data ◽  
Sedimentary Cover ◽  
Seafloor Spreading ◽  
Wide Angle ◽  
The South ◽  
Seismic Line ◽  
Acoustic Basement ◽  
North West ◽  
The North ◽  
Ligurian Basin

Abstract. The Ligurian Basin is located in the Mediterranean Sea to the north-west of Corsica at the transition from the western Alpine orogen to the Apennine system and was generated by the south-eastward trench retreat of the Apennines-Calabrian subduction zone. Late Oligocene to Miocene rifting caused continental extension and subsidence, leading to the opening of the basin. Yet, it still remains enigmatic if rifting caused continental break-up and seafloor spreading. To reveal its lithospheric architecture, we acquired a state of the art seismic refraction and wide-angle reflection profile in the Ligurian Basin. The seismic line was recorded in the framework of SPP2017 4D-MB, the German component of the European AlpArray initiative, and trends in a NE-SW direction at the centre of the Ligurian Basin, roughly parallel to the French coastline. The seismic data recorded on the newly developed GEOLOG recorder, designed at GEOMAR, are dominated by sedimentary refractions and show mantle Pn arrivals at offsets of up to 70 km and a very prominent wide-angle Moho reflection. The main features share several characteristics (i.e. offset range, continuity) generally associated with continental settings rather than documenting oceanic crust emplaced by seafloor spreading. Seismic tomography results are augmented by gravity data and yield a 7.5–8 km thick sedimentary cover which is directly underlain by serpentinised mantle material at the south-western end of the profile. The acoustic basement at the north-eastern termination is interpreted to be continental crust, thickening towards the NE. Our study reveals that the oceanic domain does not extend as far north as previously assumed and that extension led to extreme continental thinning and exhumation of sub-continental mantle which eventually became serpentinised.

Subduction polarity reversal at the junction between the Western Alps and the Northern Apennines, Italy

2008 ◽  
Vol 450 (1-4) ◽  
pp. 34-50 ◽  
Author(s):  
Gianluca Vignaroli ◽  
Claudio Faccenna ◽  
Laurent Jolivet ◽  
Claudia Piromallo ◽  
Federico Rossetti
Keyword(s):  
Western Alps ◽  
Northern Apennines ◽  
Polarity Reversal

scholarly journals Carbonation of subduction-zone serpentinite (high-pressure ophicarbonate; Ligurian Western Alps) and implications for the deep carbon cycling

2016 ◽  
Vol 441 ◽  
pp. 155-166 ◽  
Author(s):  
Marco Scambelluri ◽  
Gray E. Bebout ◽  
Donato Belmonte ◽  
Mattia Gilio ◽  
Nicola Campomenosi ◽  
...  
Keyword(s):  
High Pressure ◽  
Carbon Cycling ◽  
Subduction Zone ◽  
Western Alps

scholarly journals Alpine subduction zone metamorphism in the Paleozoic successions of the Monti Romani (Northern Apennines, Italy)

2021 ◽  
Author(s):  
Samuele Papeschi ◽  
Alessio Pontesilli ◽  
Claudia Romano ◽  
Federico Rossetti ◽  
Thomas Theye
Keyword(s):  
Subduction Zone ◽  
Northern Apennines

Tracking Fe mobility and Fe speciation in subduction zone fluids at the slab-mantle interface in a subduction channel: A tale of whiteschist from the Western Alps

2019 ◽  
Vol 267 ◽  
pp. 1-16
Author(s):  
Yi-Xiang Chen ◽  
Wenning Lu ◽  
Yongsheng He ◽  
Hans-Peter Schertl ◽  
Yong-Fei Zheng ◽  
...  
Keyword(s):  
Subduction Zone ◽  
Western Alps ◽  
Subduction Channel ◽  
Fe Speciation
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