Hercynian anatexis in the envelope of the Beni Bousera peridotites (Alboran Domain,Morocco): Implications for the tectono-metamorphic evolution of the deep crustal roots of the Mediterranean region |
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| Institution: | 1. Dipartimento di Scienze, Università Roma Tre, Roma, Italy;2. Institut für Anorganische Chemie, Universität Stuttgart, Stuttgart, Germany;3. Département de Géologie, Université de Rabat, Rabat, Morocco;4. Institute für Geowissenschaften, Goethe University, Frankfurt, Germany;5. Frankfurt Isotope and Element Research Center (FIERCE), Goethe University Frankfurt, Germany;6. Istituto di Geoscienze e Georisorse, CNR, Pisa, Italy;1. Instituto Andaluz de Ciencias de la Tierra (IACT), CSIC-UGR, Avda. de las Palmeras 4, 18100 Armilla, Granada, Spain;2. Departamento de Mineralogía y Petrología, Facultad de Ciencias, Universidad de Granada, Avenida Fuentenueva s/n, 18002 Granada, Spain;3. Géosciences Montpellier, UMR 5243, CNRS–Université de Montpellier, Place E. Bataillon, 34095 Montpellier, France;4. Dipartimento di Geoscienze, Università di Padova, Via Gradenigo 6, 35131 Padua, Italy;5. Departamento de Geodinámica, Facultad de Ciencias, Universidad de Granada, Avenida Fuentenueva s/n, 18002 Granada, Spain;1. Géosciences Montpellier, Université de Montpellier II, CNRS-UMR 5243, Place E. Bataillon, 34095 Montpellier cedex 5, France;2. Laboratoire de Recherche Géologie, Faculté des Sciences de la Terre, Université Badji Mokhtar, BP.12, Annaba 23000, Algeria;3. Université des Sciences et Techniques Houari Boumedienne, Bab Ezzouar, Laboratoire de Géodynamique, Géologie de l''Ingénieur et Planétologie, (LGGIP/FSTGAT/USTHB), Alger, Algeria |
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| Abstract: | The metamorphic core of the Betic-Rif orogenic chain (Alboran Domain) is made up of lower crustal rocks forming the envelope of the Ronda (Spain) and Beni Bousera (Morocco) peridotites. The deepest sections of the crustal envelopes are made of migmatitic granulites associated with diffuse acidic magmatic products, making these exposure and ideal site to investigate the textural and petrological connection between crustal anatexis and granite magmatism in the contintental crust. However, still debated is the timing of intracrustal emplacement of the peridotite bodies, with models proposing either Alpine (early Miocene) or Hercynian ages, and still uncertain is the linkage between peridotite emplacement and crustal anatexis. In this study, by combining rock textures with whole-rock geochemistry, metamorphic thermobarometry, the U-Pb zircon geochronology and the analysis of the garnet and zircon REE chemistry, we document the P-T-t evolution of the granulite facies migmatites that form the immediate envelope of the Beni Bousera peridotites of the Rif belt. A main episode of Permo-Carboniferous (ca. 300–290 Ma) deep crustal anatexis, melt extraction and migration is documented that we link to the crustal emplacement of the Beni Bousera peridotites during collapse of the Hercynian orogen. Correlation at a regional scale suggests that the Beni-Bousera section can be tentatively correlated with the pre-Alpine (Permo-Carboniferous) basement units tectonically interleaved within the orogenic structure of the Alpine chain. The results of this study provide ultimate constraints to reconstruct the tectono-metamorphic evolution of the Alboran Domain in the Western Mediterranean and impose re-assessment of the modes and rates through which Alpine orogenic construction and collapse occurred and operated in the region. |
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