GRAPTOLITE RESEARCH IN TÜRKIYE: AN OVERVIEW OF STUDIES UNDERTAKEN IN THE FIRST QUARTER OF THE 21ST CENTURY

Abstract

This paper presents a comprehensive synthesis and critical re-evaluation of graptolite research undertaken in Türkiye since the beginning of the twenty-first century, with particular emphasis on Ordovician and Silurian successions of the İstanbul–Zonguldak Composite Terrane, the Tauride–Anatolide Terrane, and the Southeastern Anatolian Autochthon. Drawing upon published studies, unpublished reports, and new taxonomic and chronostratigraphic revisions, this review summarizes graptolite occurrences, biostratigraphic frameworks and depositional settings across these tectonostratigraphic units. Ordovician data document the timing and nature of early Palaeozoic marine transgressions, refine correlations of Tremadocian–Darriwilian successions, and reveal peri-Gondwanan palaeobiogeographical affinities, including links with Avalonia–Armorica. Silurian successions are shown to preserve a detailed record of the post-Hirnantian transgression, maximum flooding events and subsequent regression, expressed in widespread graptolitic black shale records, condensed sections and regionally significant stratigraphic gaps. Comparison with coeval successions from Europe, North Africa and Arabia indicates that the Turkish terranes occupied key positions along the northern Gondwanan margin and followed distinct palaeogeographic trajectories during closure of the Rheic Ocean. This synthesis highlights the central role of graptolites in correlating Lower Palaeozoic successions across Anatolia and emphasizes their importance for reconstructing terrane evolution, palaeoceanography and basin development in the eastern Mediterranean region.