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Subduction dynamics, mineralization and related magmatism in eastern Mediterranean: insight from kinematic reconstructions

Abstract : Mineralization and magmatism in subduction zones are intimately controlled by the thermal structure and hydrous and magmatic fluid dynamics in the underlying mantle. Most of studies dedicated to the spatial and temporal distribution of ore deposits and related magmatism along different active margins, consider the present-day tectonic plates configuration. However, in regions where subduction zones are laterally constrained, the 3D geometry of the slab evolves quickly, leading to fast kinematic changes at the surface. Integration of kinematic reconstructions is thus necessary to visualize the evolution of subduction zones and to better understand the interactions between subduction dynamics, magmatism and mineralization. We have applied this approach in the eastern Mediterranean, where the Tethyan active margin is characterized by successive subductions of oceanic and continental ribbons, slab retreat episodes and possible slab tearing processes since the late Cretaceous. Using G-Plates software, we modeled the paleogeographic evolution of the eastern Mediterranean, accounting for paleomagnetic rotations, the tectono-metamorphic history, displacements along large-scale structures, ages of metamorphism and magmatism. We propose a geodynamical evolution of this subduction zone since 120 Myr, with a temporal resolution of 1 Myr. From late Cretaceous to lower Paleocene, calc-alkaline magmatism and porphyry Cu deposits emplaced in the Balkans. The active margin was then similar to the Andean one with the Tethyan oceanic lithosphere subducting along a long linear trench. Afterward, a barren period occurred from late Paleocene to Eocene while the Pelagonian microcontinent was buried within the subduction zone. Since the Oligocene, Au-rich deposits and related K-rich magmatism emplaced in the Rhodope, the Aegean and western Anatolian domains, where extension dominated in response to fast slab retreat. Asthenospheric flow and back-arc warmer environment induced partial melting of subduction-modified lithospheric mantle where Au was previously stored. The raising of magmas was then often controlled by large-scale active structures such as detachments (e.g. Au-rich deposits along the Strymon detachment). Finally, large-scale block rotations, alkaline volcanism and westward migration of magmatism and mineralization emplacement in the Menderes massif and the Cyclades occurred since the middle Miocene. These events are a possible consequence of slab tearing and related mantle flow, as suggested by tomographic models below western Anatolia. These results highlight the importance of mantle flow on the emplacement of mineralization and magmatic bodies. We performed 3D thermo-mechanical numerical modeling to further test the effects of slab retreat and tear-off on the flow and thermal field within the mantle. Preliminary models suggest that the asthenospheric flow induced by slab tear-off may affect the location, the timing of emplacement and the origin of potentially fertile magmas within the upper plate.
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Contributor : Nathalie Pothier <>
Submitted on : Tuesday, April 8, 2014 - 10:08:04 AM
Last modification on : Wednesday, September 23, 2020 - 4:36:31 AM

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Armel Menant, Laurent Jolivet, Denis Thiéblemont, Pietro Sternai, T. Gerya, et al.. Subduction dynamics, mineralization and related magmatism in eastern Mediterranean: insight from kinematic reconstructions. American Geophysical Union, Fall Meeting, Dec 2013, San Francisco, United States. pp.2620. ⟨insu-00975184⟩

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