Meso-Tethyan oceanic sutures and their deformation

Abstract

On the basis of comparative stratigraphie and paleontologic analysis, supported by some key paleomagnetic data and interpretations, it is shown that during the Mesozoic and the Cenozoic the Eurasian continent grew by accretion of microcontinents. These microcontinents separated basins with oceanic crust from the main ocean. During the Late Cretaceous and the early Cenozoic the collision of the microcontinents with Eurasia resulted in the closure of the basins, and Meso-Tethyan oceanic sutures originated. In the region under consideration, from the Carpathians to Tibet, there are two main Meso-Tethyan sutures: the Carpathian-Lesser Caucasus and the Afghan-Tibet suture. The above-mentioned main structures also had branches, which remained as sutures of small basins: the Kamennopotock, Interpontide, Nain-Baft basins and others. In the West Carpathians the Carpathian-Lesser Caucasus suture is overlain by a widespread Gemeric-Tatric allochton. From the West Carpathians the suture passes through the Pannonian basin into the Vardar ophiolite zone and farther to the ophiolites of the Izmir-Ankara zone. Being displaced along the North Anatolian right-lateral strike-slip fault, the main suture passes from the Eastern Pontides into the Lesser Caucasus, where it is marked by ophiolites of the Amasia area, the Shirak, Bozum and Zangezur ridges. Sunsequently, it can be observed through the Iranian Qara Dagh mountains to Lake Urumiyeh and the North Anatolian strike-slip fault. Being again shifted along the strike-slip fault, the Carpathian-Lesser Caucasus Meso-Tethyan suture ends in the Western Zagros near the Cenozoic Neo-Tethyan suture. The Afghan-Tibet Meso-Tethyan suture is situated in the Pamirs in the Rushan-Pshart zone. The east prolongation of the suture has been displaced along the Pamir-Karakorum right-lateral strike-slip fault in Tibet. West of the Pamirs this suture is also displaced along strike-slip faults and continues in the Farahrud zone in Afghanistan, and than passes through the Zabol-Baluch and Daz Murian ophiolite zones and approaches the Neo-Tethyan suture. The paleomagnetic data allow us to reconstruct the location of those sutures in the Late Cretaceous-early Cenozoic. If one compares the present position of the Carpathian-Lesser Caucasus and Afghan-Tibet Meso-Tethyan sutures with the Late Cretaceous-early Cenozoic reconstructions of these sutures it is possible to trace the inner deformation of the Alpine belt. According to these data, the Carpathian-Lesser Caucasus suture moved northwards over 1200 km ahead of the Arabian-Turkish syntaxis with the displacement direction across the fold belt. At the border of the Dinarides and Hellenides, the displacement decreases to 400–500 km, and its direction is along the fold belt. The amplitude of the suture displacement increases in the Pannonian region and again decreases towards the Eastern Alps. The displacement of the Afghan-Tibet suture was > 2000 km during the Alpine deformation. A great ensemble of Cenozoic nappes, folds and structural arcs of the Pamir-Punjab and Arabian-Turkish syntaxes and Carpathian loop is the result of lateral shortening of the Alpine belt through the collision.