New data collected in central Crete on the ophiolite-bearing units, result in a better understanding of the role and tectonic significance of these units in the construction of this segment of the Hellenides. These nappes are composed of three main tectonic units that, characterized by different metamorphic facies conditions, are represented by an un-metamorphosed lower unit, a greenschist to HP greenschist-facies intermediate unit and a blueschist-facies upper unit. These chaotic thrust-nappes include blocks of oceanic and continental deriving rocks and can be considered as a remnant of an accretionary complex. The lower unit represents the toe of the wedge whereas the intermediate and upper units refer to the innermost and deeper subducted portions exhumed and superimposed on top of each other during the early stages of continental collision. The structural evolution of the accretionary wedge was controlled by four main contractional deformation events that, including distinct groups of structures developed at different crustal levels, were driven by SSE and SSW directions of tectonic transport. Our data strongly suggest that the ophiolite-bearing tectonic wedge was accreted during the Paleogene subduction of a Late Jurassic-Cretaceous oceanic realm beneath the continental margin of the Pelagonian domain and it was successively involved in the continental collision with the Adria Block. The greenschist to blueschist facies metamorphism and the subsequent exhumation and emplacement of the intermediate and upper units above the frontal portion of the wedge may mainly be due to deep duplexing marking the onset of continental collision. We thus suggest that the ophiolite-bearing units of Crete represent a single suture zone related to the closure of a unique oceanic domain (Pindos-Cycladic Ocean) subducted beneath the Internal Hellenides Platform continental domains thus assuming the significance of a southern oceanic seaway of the largest eastern Neotethys developed since the Triassic between Eurasia and Africa.
The Cretan ophiolite-bearing melange (Greece): a remnant of Alpine accretionary wedge
Catalano S;Cirrincione R.;Tortorici G.
2012-01-01
Abstract
New data collected in central Crete on the ophiolite-bearing units, result in a better understanding of the role and tectonic significance of these units in the construction of this segment of the Hellenides. These nappes are composed of three main tectonic units that, characterized by different metamorphic facies conditions, are represented by an un-metamorphosed lower unit, a greenschist to HP greenschist-facies intermediate unit and a blueschist-facies upper unit. These chaotic thrust-nappes include blocks of oceanic and continental deriving rocks and can be considered as a remnant of an accretionary complex. The lower unit represents the toe of the wedge whereas the intermediate and upper units refer to the innermost and deeper subducted portions exhumed and superimposed on top of each other during the early stages of continental collision. The structural evolution of the accretionary wedge was controlled by four main contractional deformation events that, including distinct groups of structures developed at different crustal levels, were driven by SSE and SSW directions of tectonic transport. Our data strongly suggest that the ophiolite-bearing tectonic wedge was accreted during the Paleogene subduction of a Late Jurassic-Cretaceous oceanic realm beneath the continental margin of the Pelagonian domain and it was successively involved in the continental collision with the Adria Block. The greenschist to blueschist facies metamorphism and the subsequent exhumation and emplacement of the intermediate and upper units above the frontal portion of the wedge may mainly be due to deep duplexing marking the onset of continental collision. We thus suggest that the ophiolite-bearing units of Crete represent a single suture zone related to the closure of a unique oceanic domain (Pindos-Cycladic Ocean) subducted beneath the Internal Hellenides Platform continental domains thus assuming the significance of a southern oceanic seaway of the largest eastern Neotethys developed since the Triassic between Eurasia and Africa.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
