THE MID-CARBONIFEROUS BOUNDARY IN CENTRAL TAURIDES (TURKEY): CONODONTS, FORAMINIFERS AND SEQUENCE STRATIGRAPHY

The aim of this study is to delineate the mid-Carboniferous boundary by using conodonts, foraminiferal biostratigraphy, and sequence stratigraphy based on meter-scale cycles. The section measured in the Yaricak Formation of the Aladag Unit (Hadim region, Central Taurides, Turkey) is mainly composed of carbonate rocks with intercalations of sandstones. The measured section spanning the Upper Serpukhovian – Lower Bashkirian interval, contains an important assemblage of conodont taxa including Declinognathodus noduliferus, Declinognathodus lateralis, Adetognathus lautus and Kladognathus sp. The upper part of the succession is characterized by the presence of Declinognathodus noduliferus, the index taxon used for the delineation of the Mid-Carboniferous boundary at the GSSP in Arrow Canyon and elsewhere in the world. Besides the conodonts, many foraminiferal taxa have been recovered from the closely sampled limestone beds. The mid-Carboniferous boundary is drawn based on first appearances of Plectostaffella bogdanovkensis and Plectostaffella jakhensis and the disappearance of Eostaffella ex gr. ikensis. The boundary fixed by the foraminiferal biostratigraphy matches up perfectly with the first appearance of the index, Declinognathodus noduliferus. Detailed petrographical studies have led to the recognition of several microfacies types. Based on the stacking patterns of these microfacies, six types of meter-scale cycles have been recognized and they have been used to define cycles of higher order divisible into systems tracts. The correlation of the sequence boundaries within the established biostratigraphical frame indicates that cycles were deposited under the control of eustatic events and the mid-Carboniferous boundary does not coincide with one of these sequence boundaries but falls within one of the third-order sequences.