First recovery of late Early Triassic (Spathian) pelagic assemblages (radiolarians and conodonts) from block in the Upper Karakaya Complex near Ankara City, central Turkey: Biostratigraphical remarks and correlation

Abstract

The Upper Karakaya Complex, belonging to the Karakaya Complex, includes different blocks and tectonic slices within a Triassic sheared matrix. This wide-spread unit mainly exposed in northern Turkey also crops out to the southern part of Ankara city near Gokcehuyuk village. Instead of a continuous sequence of Carboniferous to Permian age described in a previous study, five different blocks of various origins and ages are identified in this study. One of the pelagic blocks composing of cherty limestone includes radiolarian and conodont assemblages typical of Spathian age, representing the Triassospathodus homeri Conodont Zone. It corresponds also to the Hozmadia ozawai Radiolarian Zone although the zonal guide could not be obtained from the radiolarian assemblage. This is so far the first recovery of pelagic assemblages (radiolarians and conodonts) from the Karakaya Complex. This result clearly indicates that pelagic sedimentation took place in the Karakaya Complex during late Early Triassic time. Compared to previous studies, it can be stated that radiolarian cherts have been deposited in the Karakaya Complex in two different time span from Middle to Late Devonian and Late Permian (Changhsingian) to early Late Triassic (Carnian) time, respectively.