Hyperextension of continental to oceanic-like lithosphere: The record of late gabbros in the shallow subcontinental lithospheric mantle of the westernmost Mediterranean

Hidas, Károly; Varas-Reus, Maŕia Isabel; Garrido, Carlos J.; Marchesi, Claudio; Acosta-Vigil, Antonio; Padrón‐Navarta, José Alberto; Targuisti, Kamal; Konc, Z.

doi:10.1016/j.tecto.2015.03.011

Cited by 23 publications

(8 citation statements)

References 98 publications

(149 reference statements)

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“…Note also that the arc volcanism is registered in the Alboran domain only since approximately 20 Ma (Duggen et al, ), leading to hypothesize that roll‐back started only at that period of time (Frizon de Lamotte et al, ). However, magmatic products like tholeitic dykes and gabbroic intrusion inside the hyperstretched Western Alboran lithosphere suggest ongoing active roll‐back upper plate extension since Oligocene time (Hidas et al, ). The subduction of the volcanic arc and the entire fore‐arc during the continental margin obduction can explain the absence of outcrop of arc volcanism older than 20 Ma.…”

Section: Discussionmentioning

confidence: 99%

“…The crustal thickness above the peridotites has been locally reduced to less than 50 m, testifying of hyperstretching during Oligo‐Miocene times (Frasca et al, ). Consistently, partial melting occurs at the end of the extensional deformation of the peridotites (Marchesi et al, ), locally leading to gabbros intrusion (Frasca et al, ; Hidas et al, ). Michard et al () and Tubía et al () already suggested a continental margin affinity for the Ronda peridotites and their crustal envelopes.…”

Section: Geological Settingmentioning

confidence: 93%

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Western Mediterranean Subcontinental Mantle Emplacement by Continental Margin Obduction

et al. 2019

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Obduction is the tectonic process that results from thrusting of an oceanic lithosphere section (ophiolite) onto a continent. In contrast, thrusting of subcontinental mantle, observed in several mountain belts, remains a major unknown of plate tectonics. In the western Mediterranean, the Ronda and Beni Bousera peridotites are the largest worldwide subcontinental mantle exposure. From a geological point of view, the Ronda peridotites are exhumed by hyperstretching of the continental lithosphere in a back‐arc immediately followed by thrusting, explaining their present‐day position inside the Alboran crust. Using 2‐D and 3‐D modeling of new gravimetric data combined with local seismic tomography, we show that the Ronda peridotites are rooted inside the Alboran mantle along the entire Gibraltar arc. On these bases, we propose that the emplacement of the Ronda peridotites occurred in a back‐arc setting and corresponds to the thrusting of an entire hyper‐stretched continental margin onto a continent, a process that we define as continental margin obduction. This results from two successive deformation events: continental upper plate extension driven by slab roll‐back, immediately followed by upper plate shortening, likely triggered when a buoyant continental domain enters the subduction. We propose that this process affected the entire western Alboran domain, with peridotite bodies embedded within the crust along the whole Gibraltar Arc. We suggest that other examples such as the Alps Ivrea mantle body could likely represent continental margin obduction at the onset of continental collision.

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Section: Discussionmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 93%

Western Mediterranean Subcontinental Mantle Emplacement by Continental Margin Obduction

et al. 2019

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“…This interpretation is similar to that drawn by Hidas et al . [] to explain the orientation of constituent phases in gabbroic veins, which crosscut peridotites in the Ojén peridotite massif (Ronda peridotite).…”

Section: Discussionmentioning

confidence: 99%

Flow in the western Mediterranean shallow mantle: Insights from xenoliths in Pliocene alkali basalts from SE Iberia (eastern Betics, Spain)

et al. 2016

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Mantle xenoliths in Pliocene alkali basalts of the eastern Betics (SE Iberia, Spain) are spinel ± plagioclase lherzolite, with minor harzburgite and wehrlite, displaying porphyroclastic or equigranular textures. Equigranular peridotites have olivine crystal preferred orientation (CPO) patterns similar to those of porphyroclastic xenoliths but slightly more dispersed. Olivine CPO shows [100]‐fiber patterns characterized by strong alignment of [100]‐axes subparallel to the stretching lineation and a girdle distribution of [010]‐axes normal to it. This pattern is consistent with simple shear or transtensional deformation accommodated by dislocation creep. One xenolith provides evidence for synkinematic reactive percolation of subduction‐related Si‐rich melts/fluids that resulted in oriented crystallization of orthopyroxene. Despite a seemingly undeformed microstructure, the CPO in orthopyroxenite veins in composite xenoliths is identical to those of pyroxenes in the host peridotite, suggesting late‐kinematic crystallization. Based on these observations, we propose that the annealing producing the equigranular microstructures was triggered by melt percolation in the shallow subcontinental lithospheric mantle coeval to the late Neogene formation of veins in composite xenoliths. Calculated seismic properties are characterized by fast propagation of P waves and polarization of fast S waves parallel to olivine [100]‐axis (stretching lineation). These data are compatible with present‐day seismic anisotropy observations in SE Iberia if the foliations in the lithospheric mantle are steeply dipping and lineations are subhorizontal with ENE strike, implying dominantly horizontal mantle flow in the ENE‐WSW direction within vertical planes, that is, subparallel to the paleo‐Iberian margin. The measured anisotropy could thus reflect a lithospheric fabric due to strike‐slip deformation in the late Miocene in the context of WSW tearing of the subducted south Iberian margin lithosphere.

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“…Two main features finally characterize the Pl-tectonite: (1) the presence of podiform chromite layers, also present further west in the Spl-tectonite and in other peridotite massifs. Some of these chromites contain zoned zircons with a large range of ages from the Precambrian to 20 Ma (González-Jiménez et al, 2017), ( 2) the occurrence of ultramylonitic complexes nearby the granular domain (not at the base of the massif) and only observed at the extreme west of the Pl-tectonite domain (Hidas et al, 2013(Hidas et al, , 2015Précigout et al, 2013).…”

Section: History Of Deformation In the Peridotitementioning

confidence: 99%

Lateral variations of pressure-temperature evolution in non-cylindrical orogens and 3-D subduction dynamics: the Betic-Rif Cordillera example

Bessière

Jolivet²,

Augier

et al. 2021

Preprint

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Orogens closely linked to 3-D subduction dynamics are frequently non-cylindrical and the Mediterranean region is a perfect natural laboratory to observe several of them, as well as their interactions. Through the succession of extension, subduction and sometimes collision events, the kinematic reconstructions of such orogens can be difficult and the subject of active debates. The internal zones are often non-consensual, especially when their long-term Pressure-Temperature-time-deformation (P-T-t-d) evolutions are studied. This complexity is mostly due to pre-orogenic inheritance or complex interactions between the subducting lithosphere, the overriding plate and the asthenosphere. All these elements are described and documented in Mediterranean orogens, i.e., a complex shape of the Eurasian and African margins in pre-orogenic times and a complex slab retreat and tearing dynamics. Their 3-D geometry results in strongly arcuate belts, such as the Betic-Rif Cordillera, located in the westernmost part of the Mediterranean region.Focused on the Internal Zones of the Betic-Rif Cordillera and based on recent findings (Orogen Project framework), a synthesis of the tectono-metamorphic evolution shows the relations in space and time between tectonic and P-T evolutions. The reinterpretation of the contact between peridotite massifs and Mesozoic sediments as an extensional detachment leads to a discussion of the geodynamic setting and timing of mantle exhumation. Based on new 40Ar/39Ar ages in the Alpuj&#225;rride Complex (metamorphic formations of the Betic Internal Zones) and a discussion of published ages in the Nevado-Filabride Complex (metamorphic formations of the Betic Internal Zones), we conclude that the age of the HP-LT metamorphism is Eocene in all the Internal Zones. A first-order observation is the contrast between the well-preserved Eocene HP-LT blueschists-facies rocks of the Eastern Alpuj&#225;rride-Sebtide Complex and the younger HT-LP conditions reaching partial melting recorded in the Western Alpuj&#225;rride. We propose a model where the large longitudinal variations in the P-T evolution are mainly due to (i) differences in the timing of subduction and exhumation, (ii) the nature of the subducting lithosphere and (iii) a major change in subduction dynamics at ~20 Ma associated with a slab-tearing event.

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Hyperextension of continental to oceanic-like lithosphere: The record of late gabbros in the shallow subcontinental lithospheric mantle of the westernmost Mediterranean

Cited by 23 publications

References 98 publications

Western Mediterranean Subcontinental Mantle Emplacement by Continental Margin Obduction

Western Mediterranean Subcontinental Mantle Emplacement by Continental Margin Obduction

Flow in the western Mediterranean shallow mantle: Insights from xenoliths in Pliocene alkali basalts from SE Iberia (eastern Betics, Spain)

Lateral variations of pressure-temperature evolution in non-cylindrical orogens and 3-D subduction dynamics: the Betic-Rif Cordillera example

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