40Ar/39Ar dating of shear zones in the Variscan basement of Greater Kabylia (Algeria). Evidence of an Eo-Alpine event at 128 Ma (Hauterivian–Barremian boundary): geodynamic consequences

Cheilletz, Alain; Ruffet, Gilles; Marignac, Christian; Kolli, Omar; Gasquet, Dominique; Féraud, Gilbert; Bouillin, Jean-Pierre

doi:10.1016/s0040-1951(99)00047-5

Cited by 53 publications

(48 citation statements)

References 25 publications

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“…Nevertheless, the humpshaped age spectrum yielded by this sample suggests, as earlier evidenced by e.g. Cheilletz et al (1999), that the experiment is altered by a recoil of the 39 Ar as a consequence of the presence of chlorite interlayered in the biotite. In this topic the observed intermediate to high temperature apparent ages and integrated age are too old as a result of the displacement and probably loss of the neutron-induced atom during irradiation.…”

Section: Biotitessupporting

confidence: 67%

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Alpine and late-hercynian geochronological constraints in the Argentera Massif (Western Alps)

Corsini

Ruffet

Caby

2004

Eclogae geol. Helv.

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Alpine and late-hercynian geochronological constraints in the Argentera Massif (Western Alps) 3 ABSTRACT Located in the southern part of the Western Alps, the Argentera massif belongs to the paleo-European basement of the external domain. It experienced a polyphased deformation history, Hercynian and Alpine. The Alpine history is characterized by the development of a network of ductile shear zones. An 39 Ar-40 Ar study of single grains of Hercynian muscovites and Alpine phengites allowed to constrain various events. A muscovite cooling age at ca 296-299 Ma is proposed for the Argentera granite, clearly later than the estimated cooling age at ca 310-315Ma for the low-pressure anatexis. Neocrystallized phengites collected within an Alpine shear zone (Frema Morte) crosscutting the late Hercynian Argentera granite yielded an age at 22.2 ± 0.3 Ma (1σ). This is one of the first unequivocal absolute age constraint of a late Alpine metamorphism in the external crystalline massifs of the Western Alps. Our P-T conditions estimates indicate a regional temperature at ca 350 °C for pressure at 0.35-0.4 GPa for this Alpine metamorphism. These estimates imply a minimum burial of 14 km for the Argentera massif, which could result from the overloading imposed by the internal nappes emplacement, probably between 28 Ma and 22.2 Ma. RESUME Le massif de l'Argentera est le massif cristallin externe le plus méridional externe de la chaîne alpine. Rattaché au socle européen, ce massif est marqué par une histoire polyphasée, hercynienne et alpine. La déformation alpine se concentre essentiellement dans un réseau de zones de cisaillements ductiles. Une étude 39 Ar-40 Ar sur monograins de muscovites hercyniennes et de phengites alpines permet de mieux comprendre l'évolution du massif. Un âge à environ 296-299 Ma obtenu sur les muscovites du granite de l'Argentera montre que sa mise en place est postérieure à l'épisode d'anatexie crustale tardi-collisionnelle qui se manifeste à environ 310-315Ma. L'analyse des phengites néo-formées provenant de la zone de cisaillement alpine de Frema Morte qui recoupe le granite hercynien de l'Argentera a fourni un age à 22.2 ± 0.3 Ma (1σ). Ce résultat permet de contraindre l'âge du métamorphisme alpin qui affecte tardivement les massifs cristallins externes dans les Alpes occidentales. Notre étude sur les conditions du métamorphisme alpin suggère d'autre part une température régionale d'environ 350 °C pour une pression de 0.35-0.4 GPa. Ces estimations impliquent un enfouissement minimum du massif de l'Argentera d'environ 14 km, en relation avec les nappes internes qui se mettent en place probablement entre 28 Ma et 22.2 Ma.

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Section: Biotitessupporting

confidence: 67%

“…Cheilletz et al (1999), Tremblay et al (2000, Castonguay et al (2001) or Alexandrov et al (2002). Whatever it may be, the apparent low impact of the disturbing event on the K-Ar isotopic system of these samples does not allow to constrain precisely its age even if it is probably Alpine.…”

Section: Muscovitesmentioning

confidence: 99%

Alpine and late-hercynian geochronological constraints in the Argentera Massif (Western Alps)

Corsini

Ruffet

Caby

2004

Eclogae geol. Helv.

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“…Even if some dubious Early Cretaceous ages (i.e., Eo-Alpine) clustering around 130 Ma were documented in the southern CPO (Rb-Sr and K-Ar methods; Schenk, 1980;Laurenzi et al, 1986), as well as the occurrence of more constrained data derived from Greater Kabylian (Ar-Ar in situ mica ages; Cheilletz et al, 1999), we interpret this early metamorphic stage as the result of relatively high pressure Meso-Alpine evolution. This consideration derives from a comparison between the tectonometamorphic evolution of the LMG with: (a) absolute ages of the northern CPO ophiolite units (De Roever, 1972;Dubois, 1976); and (b) reconstruction of the metamorphic evolution of the Mesozoic Alì series, which is characterized by an anchi-metamorphic sedimentary sequence developed from early Lias to Tithonian-Neocomian Pezzino, 1991, 1994 and references therein), and therefore, still forming during Eo-Alpine stages (i.e., 128-130 Ma).…”

Section: Discussionmentioning

confidence: 65%

Alpine Metamorphism in the Aspromonte Massif: Implications for a New Framework for the Southern Sector of the Calabria-Peloritani Orogen, Italy

Pezzino

Angì

Fazio

et al. 2008

International Geology Review

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Structural, petrologic, and thermobarometric data presented in this paper contribute to our understanding of the tectono-metamorphic evolution of the lowest tectonic slices of the Aspromonte Massif (southern Calabria, Italy), which crop out in three main tectonic windows. Despite previously being considered different units, they exhibit the following similar features: the same tectonic evolution, analogous blasto-deformation relationships, and absence of Hercynian mineralogical assemblage relics. Similar P-T paths indicate early HP-LT Meso-Alpine metamorphism (400-600° C at 0.95-1.35 GPa), evolving in the Oligocene-Miocene toward a subsequent retrograde shearing event ranging from 480° to 610°C and 0.50 to 0.95 GPa. The latest retrograde evolution is characterized by 350-480°C and 0.32-0.62 GPa. In this new tectonic framework, it is proposed to group the metapelite sequences defining the Madonna di Polsi Unit. Data presented herein suggest that the pre-Alpine geodynamic setting of southern Calabria was a thinned continental margin made up of Hercynian basement and Mesozoic terrigenous-carbonate sedimentary cover. This continental margin evolved during the early Meso-Alpine stage into a subduction zone beneath the European plate, followed by Neo-Alpine syn-convergent exhumation along a deep-seated mylonitic shear zone. These processes are responsible for the Alpine metamorphic overprint on the Hercynian terranes, as well as for Alpine metamorphism of their Mesozoic cover.

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“…The high-temperature metamorphism coeval with anatexis has been dated as Lower Permian (Peucat et al, 1996;Hammor et al, 2006). Tectono-metamorphic events took place also during the Mesozoic period according to 40 Ar/ 39 Ar ages of 128 Ma on white micas (Cheilletz et al, 1999). Formation of metamorphic cores, exhumation of the middle and lower crustal units and unroofing of the non-metamorphic upper units took place in the Miocene, during the major syn-to late-metamorphic extensional event (Monié et al, 1988).…”

Section: Geological Framework Of the Maghrebides In Algeriamentioning

confidence: 99%

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

et al. 2014

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40Ar/39Ar dating of shear zones in the Variscan basement of Greater Kabylia (Algeria). Evidence of an Eo-Alpine event at 128 Ma (Hauterivian–Barremian boundary): geodynamic consequences

Cited by 53 publications

References 25 publications

Alpine and late-hercynian geochronological constraints in the Argentera Massif (Western Alps)

Alpine and late-hercynian geochronological constraints in the Argentera Massif (Western Alps)

Alpine Metamorphism in the Aspromonte Massif: Implications for a New Framework for the Southern Sector of the Calabria-Peloritani Orogen, Italy

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

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