TECTONIC DEVELOPMENT OF THE BITLIS-ZAGROS SUTURE MOUNTAINS OF THE SOUTH EAST ANATOLIAN OROGENIC BELT

Extensive field mapping project which covered large areas including the western, cental and eastern sectors of the SE Anatolian orogenic belt provide extensive and multi disciplinary data to review the evolutionary models proposed on the Bitlis-Zagros suture mountains of south east Anatolia. This mountain range may be divided into three approximately east-west trending zones. From south to north, they are the Arabian Platform, followed by a zone of imbrication, and then a zone of nappes.

The Arabian Platform includes a mostly marine, sedimentary succession deposited from early Cambrian to Middle Miocene time. The zone of imbrication is a narrow belt sandwiched between the Arabian Platform and the zone of nappes. It consists of imbricated thrust slices emplaced onto a Late Cretaceous to early Miocene sequence. The zone of nappes is the highest tectonic unit, consisting of two stacks of nappes simply designated the lower and upper nappes. The lower nappe is represented by the slices of a polyphase metamorphic ophiolitic assemblage and the upper nappe rests on the lower nappe and is represented by metamorphic massifs.

Southern Anatolia underwent two major episodes of Alpide deformation. The first occurred during the Late Cretaceous period, when ophiolite was emplaced on the Arabian Platform. This event was not the consequence of a continental collision. The ophiolite obduction onto the Arabian Platform was followed by a regionwide extension and a new marine transgression over the platform immediately after the ophiolite obduction. The second episode of deformation occurred during middle Eocene-Miocene time in two distinct stages as a result of the progressive elimination and complete closure of the ocean (s) which led to the collision between the zone of nappes located to the north (being a part of Eurasia) and the Arabian plate.

The southeast Anatolian orogenic evolution may be summarized as progressive relative (southerly) movement of the nappes toward the Arabian plate during Late Cretaceous-Miocene time. This caused progressive accretion of the different tectonic units into the present nappe stack, which itself finally accreted to the Arabian continental margin.

It this presentation consecutive stages of evolution of the Bitlis-Zagros suture Mountains of SE Anatolia will be discussed.