TECTONOSTRATIGRAPHY AND KINEMATICS OF THE EASTERN END OF THE SIVAS BASIN (CENTRAL EASTERN TURKEY) - IMPLICATIONS FOR THE SO-CALLED ANATOLIAN BLOCK

Abstract

The eastern end of the Sivas Basin, just west of Erzincan, is known as the Kemah Basin. The lithostratigraphy of the Kemah Basin thus corresponds with the general characteristics described for the Sivas Basin: the upper stratigraphic sequence begins with the Kemah Limestones of Burdigalian age. Above these, the sediments (grey limy marls, sandstones and conglomerates) are not yet dated, but probably span Late Miocene to Plio-Quaternary times. The lower sequence is made of (Late Oligocene?) non-fossiliferous, mainly continental deposits (variegated clays, silts and gypsum at the base; conglomerates, sandstones and some volcanics in the footwall of the limestones). Both the basin deposits and substratum (arc volcanics, volcanoclastics and ophiolites) are involved in thrust systems with displacements consistently directed to the SSE. The sequence of thrusting deduced from the geometrical pattern of the imbricate zone and from the stratigraphic record includes at least two stages of thrust propagation. The sequence shows the rise of successive waves of active new thrusts and folds from the north, cutting through earlier thrusts in a general 'break-back' sequence. The southern edge of the Neogene basin against the ophiolites covering the Munzur Limestones (Taurides) shows a moderate northward tilting. A first attempt at a (incomplete) balanced cross-section and restoration along the Burdigalian limestones as datum gives a minimum displacement of 11 km along a section length of 12 km. The kinematics and the contraction ratio question the concept of an 'Anatolian block' and related displacement models during the Late Neogene.