Metamorphic diamonds in a garnet megacryst from the Edough Massif (northeastern Algeria). Recognition and geodynamic consequences

Caby, Renaud; Bruguier, Olivier; Fernandez, Laure; Hammor, Dalila; Bosch, Delphine; Mechati, Mehdi; Laouar, Rabah; Ouabadi, Aziouz; Abdallah, Nachida; Douchet, Chantal

doi:10.1016/j.tecto.2014.10.017

Cited by 24 publications

(14 citation statements)

References 61 publications

(54 reference statements)

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“…A main mylonite zone delineates the high-grade metamorphic unit from the Kef Lakhal amphibolite massif above. This zone has been interpreted as a mélange zone and contains relics of Oligocene UHP units including diamond-bearing metamorphic rocks (Bruguier et al, 2017;Caby et al, 2014). These metamorphic rocks were accreted to the base of the overriding Kef Lakhal Complex during its exhumation and thrusting onto the African margin at 20.85 ± 0.34 Ma (Fernandez et al, 2016).…”

Section: Geodynamical and Geological Settingmentioning

confidence: 99%

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Vestiges of a fore-arc oceanic crust in the Western Mediterranean: Geochemical constraints from North-East Algeria

Fernandez

Bosch

Bruguier

et al. 2020

Lithos

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The present day architecture of the Western Mediterranean mainly results from the interplay of different lithospheric plates and the Cenozoic consumption of various branches of the Alpine Tethys and Neo-Tethys Oceans. Identifying relics of these oceanic domains in the peri-Mediterranean belts enables pinpointing the earliest stages of this evolutionary framework. In NE Algeria, the Kef Lakhal Complex (Edough Massif) is composed of amphibolites and meta-gabbros metamorphosed under amphibolite facies conditions and thrust onto the northern African margin during earliest Miocene. Geochemical analyses reveal that amphibolites and metagabbros have major and trace element signatures characteristic of tholeiitic basalts and gabbros and display N-MORB (La/ Sm N = 0.7-0.9) to E-MORB (La/Sm N = 1.1-1.2) affinities. Enrichments in U and alkalis (Cs, Rb) and high 87 Sr/ 86 Sr i ratios on bulk rocks and minerals (up to 0.70856) are typical of seawater alteration and indicate that the Kef Lakhal Complex represents a piece of altered oceanic crust. Parental magmas were derived from a Depleted Mantle source (WR εNd i = 8.2-9.9 and εHf i = 10.4-14.4) that preserved some canonical MORB ratios (Ti/Eu = 5700-7600 and Y/Ho = 27.4-29.0), but which was contaminated by a component akin to recycled oceanic crust and associated sediments (Ce/Pb = 10.5-22.2; 206 Pb/ 204 Pb i = 18.41-18.74; 207 Pb/ 204 Pb i = 15.49-15.59; 208 Pb/ 204 Pb i = 37.73-38.37). The sedimentary component is consistent with a volcaniclastic origin and substantiates an intra-oceanic setting. The geochemical characteristics of the Kef Lakhal rocks are comparable to present day (Mariana, W Pacific Ocean) or fossil (Xigaze, SE Tibet) fore-arc oceanic crust. An overview of the Western Mediterranean geodynamic indicates that the most likely period for initiating formation of a fore-arc corresponds either to the Early/Late Cretaceous or to the Middle Eocene. 40 Ar/ 39 Ar dating on amphibole further indicate that after thrusting onto the African margin, the Kef Lakhal Complex cooled down to c.550°C at 18.14 ± 0.27 Ma (2σ).

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Section: Geodynamical and Geological Settingmentioning

confidence: 99%

“…Kef Lakhal is KL. C) Enlargement of the geological sketch map of the Kef Lakhal area in the Edough Massif from NE Algeria (modified after Caby et al, 2014; reported foliations are from Ahmed-Said and .…”

Section: Analytical Techniquesmentioning

confidence: 99%

Vestiges of a fore-arc oceanic crust in the Western Mediterranean: Geochemical constraints from North-East Algeria

Fernandez

Bosch

Bruguier

et al. 2020

Lithos

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“…Fernandez et al, 2016;Mahdjoub et al, 1997;Montel et al, 2000;Peucat and Bossière, 1981;Saadallah and Caby, 1996;Sánchez-Gómez et al, 1999;Zeck, 1999). However, it is mainly characterized by the signature of the Alpine events, ranging from HP-LT for the earliest events (Bruguier et al, 2017;Caby et al, 2014;Mahdjoub et al, 1997) to HT-LP for the most recent ones during Early to Middle Miocene (Fernandez et al, 2016;Michard et al, 2006;Platt et al, 2013;Rossetti et al, 2010 with references therein). The Edough massif presents a peculiar case.…”

Section: The Alkapeca and Flyschs Domainsmentioning

confidence: 99%

“…The Edough massif presents a peculiar case. It has either been interpreted as an external or an internal massif (Bruguier et al, 2017;Caby et al, 2001;Caby et al, 2014;Hilly, 1962;Michard et al, 2006;Vila, 1970). This difficulty stems from the poorly defined contact between the external zones and the Edough massif.…”

Section: The Alkapeca and Flyschs Domainsmentioning

confidence: 99%

“…Caby et al (2001) demonstrated that this contact is not a stratigraphical one but tectonic, still approving the external nature of the Edough Massif. They considered it to be an African metamorphic core complex, developed after the emplacement of the Tellian nappes (and following them, among others, Caby et al, 2014;Fernandez et al, 2016;Bruguier et al, 2017). Following Michard et al (2006) on the basis of metamorphic data and Paleozoic remnants within the massif, it is considered as belonging to the internal zones rather than the external ones.…”

Section: The Alkapeca and Flyschs Domainsmentioning

confidence: 99%

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The Tell-Rif orogenic system (Morocco, Algeria, Tunisia) and the structural heritage of the southern Tethys margin

Leprêtre

Lamotte

Combier

et al. 2018

BSGF - Earth Sci. Bull.

106

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-The Tell-Rif (Tell in Algeria and Tunisia; Rif in Morocco) is the orogenic system fringing to the south the West Mediterranean basins. This system comprises three major tectonic-palaeogeographic zones from north to south: (1) the internal zones (AlKaPeCa for Alboran, Kabylies, Peloritan, Calabria) originating from the former northern European margin of the Maghrebian Tethys, (2) the "Flyschs zone" regarded as the former cover of the oceanic domain and (3) the external zones, forming the former southern Maghrebian Tethys margin more or less inverted. The Tell-Rif is interpreted as the direct result of the progressive closure of the Maghrebian Tethys until the collision between AlKaPeCa and Africa and, subsequently, the propagation of the deformation within Africa. This gives a consistent explanation for the offshore Neogene geodynamics and most authors share this simple scenario. Nevertheless, the current geodynamic models do not completely integrate the Tell-Rif geology. Based on the analysis of surface and sub-surface data, we propose a reappraisal of its present-day geometry in terms of geodynamic evolution. We highlight its non-cylindrical nature resulting from both the Mesozoic inheritance and the conditions of the tectonic inversion. During the Early Jurassic, we emphasize the development of NE-SW basins preceding the establishment of an E-W transform corridor connecting the Central Atlantic Ocean with the Ligurian Tethys. The Maghrebian Tethys developed just after, as the result of the Late Jurassic-Early Cretaceous left-lateral spreading between Africa and Iberia. By the Late Cretaceous, the occurrence of several tectonic events is related to the progressive convergence convergence between the two continents. A major pre-Oligocene (pre-35 Ma) compressional event is recorded in the Tell-Rif system. The existence of HP-LT metamorphic rocks associated with fragments of mantle in the External Metamorphic Massifs of the Eastern Rif and Western Tell shows that, at that time, the western part of the North-African margin was involved in a subduction below a deep basin belonging to the Maghrebian Tethys. At the same time, the closure of the West Ligurian Tethys through east-verging subduction led to a shift of the subduction, which jumped to the other side of AlKaPeCa involving both East Ligurian and Maghrebian Tethys. Slab rollback led to the development of the Oligo-Miocene back-arc basins of the West-Mediterranean, reworking the previous West Ligurian Tethys suture. The docking of AlKaPeCa against Africa occurred during the Late Burdigalian (17 Ma). Subsequently, the slab tearing triggered westward and eastward lateral movements that are responsible for the formation of the Gibraltar and Tyrrhenian Arcs respectively. The exhumation of the External Metamorphic Massifs occurred through tectonic underplating during the westward translation of the Alboran Domain. It resulted in the formation of both foredeep and wedge-top basins younger and younger westward. The lack of these elements in the eastern part ...

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Hydrogeochemical processes controlling surface water quality for irrigation in a Mediterranean wetland ecosystem, Northeast Algeria

Zahi,

Drouiche,

Medjani

et al. 2024

Environ Monit Assess

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Metamorphic diamonds in a garnet megacryst from the Edough Massif (northeastern Algeria). Recognition and geodynamic consequences

Cited by 24 publications

References 61 publications

Vestiges of a fore-arc oceanic crust in the Western Mediterranean: Geochemical constraints from North-East Algeria

Vestiges of a fore-arc oceanic crust in the Western Mediterranean: Geochemical constraints from North-East Algeria

The Tell-Rif orogenic system (Morocco, Algeria, Tunisia) and the structural heritage of the southern Tethys margin

Hydrogeochemical processes controlling surface water quality for irrigation in a Mediterranean wetland ecosystem, Northeast Algeria

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