Niğde Ömer Halisdemir Üniversitesi Mühendislik Bilimleri Dergisi

Yazarlar: Mustafa SÖNMEZ, Faruk AYDİN, Abdurrahman LERMİ, Simge OĞUZ SAKA

Konular:Mühendislik

DOI:10.28948/ngumuh.502395

Anahtar Kelimeler:Keçiboyduran,Stratovolcano,Quaternary,Volcanostratigraphy,Ar-Ar dating

Özet: The Keçiboyduran Stratovolcano and its near surrounding monogenic cones are located in the Niğde Volcanic Complex (NVC) in the south part of the Cappadocia region, central Anatolia. The units belonging to the stratovolcano are represented by volcanic products that occur in two stages. The first stage starts with pyroclastic surge deposits containing occasionally volcanic breccia and tuff levels, and then these deposits are overlapped by amphibole-rich, pyroxene-bearing lava flows with andesitic-dacitic composition. This stage ends with pyroclastic flow deposits containing block and ash flows. 40Ar/39Ar age (2.21±0.06 Ma) obtained from the amphibole-rich dacites indicate that the first volcanic activity formed in the Early Lower Pleistocene. The second stage starts with more pyroxene-rich, but amphibole-free andesitic-dacitic lava flows, and these are covered by two-levels of pyroclastic flow deposits. The debris flow deposits are the last products of this stage. 40Ar/39Ar ages obtained from the andesitic lava flows and ignimbrites (1.63±0.02 Ma and 1.26±0.18 Ma, respectively) show that the formation time of the second volcanic activity is the Late Lower Pleistocene. Acidic Hasandağı Volcanites begin with biotite-rich rhyolites that have flow-banding (0.53-0.45 ± 0.04 Ma) and end with pumice-rich ash fall and surge deposits (0.44-0.34 ± 0.05 Ma). Karataş Volcanics, which accompany to this acidic volcanism actived in the Middle Pleistocene consist of olivine-bearing basaltic lava flows (0.65-0.22 ± 0.0 2Ma) and strombolian-type scoria fall and surge deposits.

---