Tectonic evolution of a part of the Tethyside orogenic collage: The Kargi Massif, northern Turkey

Abstract

The central part of the Rhodope‐Pontide fragment, one of the major tectonic units in Turkey, provides critical data for evaluating the Cimmeride and Alpide evolution of the Mediterranean Tethysides. Tectonic events that affected the central part of the Rhodope‐Pontide fragment since the end of the Paleozoic, generated east‐west trending belts with the event of every episode redeforming and partly obliterating the structures of previous episodes. This evolution may be conveniently described in terms of three major episodes: (1) Two different realms of pre‐Dogger oceanic rocks are present in the area. The northern realm coincided with main branch of Paleo‐Tethys that was being actively destroyed by south dipping subduction. The southern realm, the Karakaya ocean, a back arc basin related to this subduction, began opening by rifting of a retroarc carbonate platform during the Permo‐Triassic. To the west a continental domain with sparse magmatism seperated the two oceanic areas. Toward the east the two oceans become united by the wedging out of the continental domain. These two pre‐Dogger oceans closed during the Lias, and their remnants were emplaced between the southern margin of Laurasia and the fragments of the Cimmerian continent. (2) The second episode partly overlapped the first with rifting south of the Cimmerian continent fragment during the Lias. This rifting was followed by a transgression which covered the ruins of the Cimmeride orogenic belt by the Malm. This rifting concurrently led to the development of the northern branch of the Neo‐Tethys and a south facing Atlantic‐type continental margin. A southerly thickening sedimentary prism developed on this margin during the Lias to early Cretaceous interval. (3) The floor of the northern branch of Neo‐Tethys began to be consumed along the north dipping subduction zone beneath the previosly constructed continental margin. This convergent margin generated a magmatic arc to the north and to the south a subduction accretion complex, present width of which approaches 80 km. To the south of the subduction accretion complex yet another convergent margin is indicated by the presence of the remnants of an ensimatic arc. The northern branch of the Neo‐Tethys was totally consumed in the late Cretaceous to Eocene interval.