Tectonics of the Mediterranean Cimmerides: nature and evolution of the western termination of Palaeo-Tethys

Abstract

The Cimmeride orogenic system was produced during the closure of Palaeo-Tethys, the original, triangular embayment of the Permo-Triassic Pangaea, and its immediate dependencies, and includes a multi-strand suture network that extends from the eastern Carpathians to the Pacific shores of Asia. Its westernmost segment, the Mediterranean Cimmerides, extends from the eastern Carpathians and the North Dobrudja to the eastern end of the Greater Caucasus thereby enclosing the Black Sea. It may be subdivided into three longitudinal sections, viz. the Balkan/Carpathian Cimmerides, the Anatolian Cimmerides (including the North Dobrudja), and the Caucasian Cimmerides. The Balkan/Carpathian Cimmerides reach from the eastern Dacides to the island of Thásos and are characterized by a diachronous Lias-Dogger (? locally later) collision that developed from north to south along a semi-cryptic suture. Owing to extreme later overprinting, neither the original orogenic polarity nor the fingerprints of the Palaeo-Tethyan suture are everywhere recognizable in them. The Anatolian Cimmerides stretch between Thásos and Artivin region and are represented by a ‘doubleorogen’. The main trunk in the north consists of five main north-vergent allochthons resting on the southern periphery of the Moesian platform and probably on those parts of the Scythian platform now separated from it by the later opening of the Black Sea. The lowermost allochthons represent remnants of Palaeo-Tethyan oceanic material with ages from possibly Devonian to the earliest Dogger, whereas the higher ones are pieces of the former Cimmerian continent. All of these allochthons were emplaced during the latest Lias-earliest Dogger. The subordinate S trunk of the Antolian Cimmerides is also north-vergent and is the product of the Late Triassic collapse of the Karakaya marginal basin of Palaeo-Tethys, the effects of which cover most of Turkey south of the north trunk. The Caucasian Cimmerides are south-vergent and consist almost entirely of the Greater Caucasus. Palaeo-Tethyan closure along the Caucasian Cimmerides took place during the ?latest Triassic. The northern foreland of the Mediterranean Cimmerides was the site of compressional deformation during the Late Triassic and Early Jurassic, whereas to the south, the medial Triassic opening of the eastern Mediterranean and the Liassic rifting of the northern branch of Neo-Tethys indicate the presence of dominantly extensional tectonics that in part may have been related to back-arc activity. Around the African promontory, these Palaeo-Tethys-related rifting events interfered with one another, and with the Atlantic-opening-related rifting phases to generate a hitherto problematic, complex, protracted, and polyphase rifting history, so characteristic of the central Mediterranean Tethyan orogens. The most outstanding problems of the Mediterranean Cimmerides are the structural/palaeogeographic relations between their constituent tectonic units and the precise delineation of the areal extent of the Cimmeride orogen.