Paleocene carbonate turbidites of the Şarkişla region, Turkey — their significance in an orogenic basin

Abstract

A Paleocene carbonate sequence occurs in the southwestern part of the Sivas-Refahiye Basin, Şarkişla province (Sivas, Turkey), and is located in the northeast of Central Anatolia. Conclusions concerning the Late Mesozoic to Early Cenozoic sedimentary evolution have been derived mainly from the carbonate turbidites. The vertical and lateral relationships of these rocks suggest deposition in a submarine fan complex. Three major megacycles characterized by a thickening- and coarsening-upward trend, are seen in the Upper Cretaceous-Lower Paleocene succession. They are considered to represent basin facies in the lower levels, passing upward into sediment attributed to distal fan facies on the basis of bed thickness distributions and bioclastic/hemipelagic ratios. Agglomerates occur as laterally discontinuous mass flow deposits which formed on the slopes of local volcanoes located in the deeper part of the basin. Thin lava sheets are the products of stratovolcanoes which result from regional tectonic subsidence. Olistoliths occurring at several stratigraphic levels probably are the result of seismic events related to contemporaneous volcano-tectonic activity. Two major turbiditic megacycles occur also in the middle and upper parts of the succession (Middle and Upper Paleocene). The lower megacycle of this sequence conforms to the distal division of a suprafan lobe while the upper part is marked by a conspicuous thickening- and coarsening-upward character indicating a suprafan lobe environment. This evidence is consistent with an overall progradation of the fan complex during the Paleocene. Paleocurrent features and slump structures indicate that the marginal slopes of the basin extended in a northeast-southwest direction and were inclined to the north. Sedimentologic, stratigraphic, tectonic and volcanic data from this sequence suggest that during the Paleocene this area formed as an arc-related basin.