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Evolution of the northern and western Dinarides : a tectonostratigraphic approach

The Dinarides are a Late Jurassic to recent, mainly SW-vergent fold and thrust belt that extends from the Southern Alps in the NW to the Albanides/Hellenides in the SE. Main tectonostratigraphic units of the Dinarides are related to: a) Early and Middle Triassic rifting: was marked by strong magmatism and horst to graben related deposition overlying Variscian basement. Rift-related magmatism migrated westward through the Early to Late Triassic. Deposition was fault controlled and sedimentation patterns demonstrate a strong differentiation between shelf, slope and basin lithologies. Along the "eastern" Apulian margin toward the Sava-Vardar ocean rifting was followed by subduction-generated extension during Early Triassic till Late Jurassic. Subduction-related attenuation of continental crust along the eastern margin of Apulia caused a generation of the back-arc basin type of the oceanic crust. The remnants of that active continental margin lithologies are found within the Eastern thrust belt as the ophiolite melange of the Central Dinarides Ophiolite Belt. b) Late Jurassic to present day compression that generated: -Eastern thrust belt, foredeep and foreland. Continental convergence was progressive from Late Jurassic and was first expressed on the eastern margin to the Dinarides as the Eastern thrust belt and its foredeep. During Early Cretaceous compressional stresses began to be transmitted westward through the Dinarides, causing the migration of the foredeep basin and regional uplift of the Eastern thrust belt. - Northern Dinarides accretionary wedge. Subduction of the oceanic plate along the northern margin of the Dinarides culminated from Maastrichtian to Eocene. That is evidenced by accretionary wedge deposits located by oil wells in the basement of the South Pannonian Basin, an east-west trending remnants of the magmatic arc and well exposed retroarc flysch-like deposits. - Western thrust belt, foredeep and foreland: At the end of the Cretaceous the entire carbonate platform was uplifted until the Early Eocene. During Eocene the Dinaridic carbonate platform was finally drowned under the flysch deposits in the broad foredeep basin of the Western thrust belt. -Eastern Adria imbricated structures: At the beginning of the Oligocene collision and progressive underthrusting of the Adria below the Dinarides created the imbricare structures of Adria provenience in front of the Western thrust belt. The structural style of the Dinaridic thrust belt depends on the polyphase tectonic compression and the competence of the sedimentary units involved. The decollements are Permian shales locally interbedded with gypsum, fine-grained Early/Mid Triassic clastics and Late Jurassic-Early Crataceous anhydrites. The competent carbonate rocks are the most responsible for the structural style of the thrust belt. The compression started with ramping along the deep decollement from the root zone with a southwestern tectonic transport. In this way, by progressive overstepping of the thrust faults the various structural forms were created along the Eastern and Western thrust belt such as fault bend folds, tear fault related folds and folded thrust structures reworked by footwall deformations. - Wrenching and tectonic inversion: NE-SW striking system of the dextral strike slip faults during Oligocene Miocene was followed by NW-SE striking wrenching in Early and Middle Miocene, affecting South Pannonian Basin. Western thrust belt and Adriatic foreland. It is reflected as tectonic inversion in Mid-Bosnian Schists Mts. and as the system of the right-lateral strike and oblique slip faults, creating the large Sava and Drava depressions of the South Pannonian Basin and narrow pull-apart basins and large flower structures of the Dinaridic thrust belt.

Tectonostratigraphic units, extension, compression, collision, thrust belt, Dinarides, Adria

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