10. Arkeometri Sonuçları Toplantısı - Kültür ve Turizm Bakanlığı

The geology of the area is rather complicated as a result of tectonicmovements and volcanic activity during the Neogene. On a broad scale,sedimentation and basin evolution in central Turkey were probably relatedto the extensional neotectonics of Anatolia and the development ofthe North-Anatolian transform fault in the Neogene (cf.Erol, 1981; İnci,1991; Angelier et aL., 1981). Preliminary geological mapping by the projectmembers has confiımed that the multiple layers of tuff and basalt underliemost of the sediments that belong to the Sinap Formation. However,the interrelationships between separate tuff and basalt units andmeso-scale tectonic features are stili largely unknown. Thick accumulationsof clastic sediments rest on the basaltic basement of the LowerMember of the Sinap Formation and are extremely well exposed on theflanks of the prominent hills in the area.it has recently became clear that the Sinap Formation spans about13-14 million years of time, from the Middle Miocene (MN 6) localitiesknown in the Sinap Project as 24 and 24A (="Inönü I" of the older literature)to the earliest Pleistocene (MN 15/16) localities 82 and 85 of theUpper Sinap Member (Alpagut et aL. 1993, in press; Kappelman et aL., inpress). Although considerable gaps stili remain in the sequence each seasonhas reduced them, to the extent that all MN units from 6 to 12 nowappear to be represented by at least one locality (unpublished data as ofthe 1993 field season). The central part of the sequence, exposed on Sinaptepeitself and adjoining hills and in the Kavakdere syncline, has beenfound to span MN 8-1 ı. The fossiliferous part of this sequence has beenpalaeomagnetically calibrated as spanning the time interval of about 11-6Maago.Although the Sinap Formation has been known to be rich in Neogenefossils since the pioneeıing work of Ozansoy (1955, 1957, 1965), its considerabletemporal coverage remained unrecognised for a long time. Şen(1990b), writing only about the sequence on Sinaptepe itself, confirmedOzansoy's interpretation of three meınbers, of Astaracian, ValIesian andPleistocene age, respectively. It was only during the third and fourth fieldseasons of the present project (Alpagut et aL., 1993) that it became apparent,however, that the Sinap Formation presents a relatively continuoussequerıce, covering at least MN units 6-12, with a few localities in MN14 (Şen, 1977) and MN 15/16 (Şen, 1990b).A K/Ar date from abasalt flow underlying the basal part of the SinapFormation provided the first radiometric tiepoint, at 15.2 +/-0.3 Ma (AIpagutet aL., in press). The palaeomagnetic sequences from Sinaptepe andKavakdere are among the longest known for the terrestrial Neogene of179