3D subduction dynamics: A first-order parameter of the transition from copper- to gold-rich deposits in the eastern Mediterranean region
Résumé
The natural variability of geometry and dynamics of subduction zones leads to a variety of mantle and crustal processes that may influence the genesis of ore deposits in the overriding plate. These complex interactions cannot be fully represented by two-dimensional (2D) models but require that the spatial and temporal evolution of ore deposits be examined in a detailed 3D tectonic framework. We compare and discuss the geodynamic and metallogenic evolution of the eastern Mediterranean subduction zone since the late Cretaceous by integrating a newly compiled metallogenic database with a recent kinematic reconstruction model. The resulting paleotec-tonic maps identify (1) a late Cretaceous Cu-rich metallogenic period with large deposits formed above a linear and stable subduction zone that produced large amounts of potentially fertile magmas in a narrow magmatic arc and (2) a late Eocene-Miocene Pb-Zn-followed by Au-rich metallogenic period with generally smaller deposits spread over a wide back-arc basin that was opened due to subduction retreat and lateral slab tearing. Supported by high-resolution numerical modeling, the proposed dynamic arc and back-arc metallogenic models emphasize (1) the influence of 3D slab dynamics and associated asthenospheric flow on ore distribution in space and time and (2) the importance of exhuming metamorphic domes in extensional back-arc setting to focus metal-bearing fluid circulations. These models differ from collision and post-collision models and may be valid on the western and eastern terminations of the whole Tethyan orogenic belt (i.e. Mediterranean and southeast Asia) where fast 3D subduction dynamics has influenced the geodynamic and metallogenic evolution of the overriding plate.
Origine : Publication financée par une institution
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