Trace fossils in the clastics of Yoncali formation (middle eocene) between Derbent and Kirim villages, Yozgat, Turkey

The Yoncalı Formation (Middle Eocene) has widespread outcrops around Yozgat, situates to the north of the city as a belt about in the East ? West direction beneath the İzmir-Ankara-Erzincan thrust coming from North toward South. In this study, trace fossils in the silisiclastics of this unit were investigated to obtain the paleoenvironment of the unit.Generally basic and branched structures represent shallow water trace fossils, loosely clasped meandering structures and honeycomb structures represent deep water trace fossils. In the study area three groups; basic and branched structures, loosely clasped meandering structures and honeycomb structures, and ten traces; Paleodiction strozzii, Thalassinoides isp., Cruziana isp., Ophiomorpha annulata, Bergaueria isp., Helminthopsis isp., Scolicia vertebralis, Scolicia prisca, Planolites isp. and Ophiomorpha isp. were identified.According to these identifications basic and branched structures represent shallow water of the Yoncalı Formation, northern outcrops in the map; loosely clasped meandering structures and honeycomb structures represent deep water (slope) of the unit, southern outcrops in the map. Also the coarse graind filled slope channels cutting the thick shale stacks in the study area support the slope environments here.Key Words: Yoncalı Formation, silisiclastics, trace fosil, Yozgat