Surface exposure dating of Holocene basalt flows and cinder cones in the Kula volcanic field (Western Turkey) using cosmogenic 3He and 10Be

Heineke C, Niedermann S, Hetzel R, Akal C

Abstract

The Kula volcanic field in Western Turkey comprises about 80 cinder cones and associated basaltic lava flows of Quaternary age. Based on geomorphological criteria and K-Ar dating, three eruption phases, β2–β4, were distinguished in previous studies. Human footprints in ash deposits document that the early inhabitants of Anatolia were affected by the volcanic eruptions, but the age of the footprints has been poorly constrained. Here we use 3He and 10Be exposure dating of olivine phenocrysts and quartz-bearing xenoliths to determine the age of the youngest lava flows and cinder cones. In the western part of the volcanic field, two basalt samples from a 15-km-long block lava flow yielded 3He ages of 1.5±0.3ka and 2.5±0.4ka, respectively, with the latter being in good agreement with a 10Be age of 2.4±0.3ka for an augen gneiss xenolith from the same flow. A few kilometers farther north, a metasedimentary xenolith from the top of the cinder cone Çakallar Tepe gave a 10Be age of 11.2±1.1ka, which dates the last eruption of this cone and also the human footprints in the related ash deposits. In the center of the volcanic field, a basalt sample and a metasedimentary xenolith from another cinder cone gave consistent 3He and 10Be ages of 2.6±0.4ka and 2.6±0.3ka, respectively. Two β4 lava flows in the central and eastern part of the volcanic province yielded 3He ages of 3.3±0.4ka and 0.9±0.2ka, respectively. Finally, a relatively well-preserved β3 flow gave a 3He age of ~13ka. Taken together, our results demonstrate that the penultimate eruption phase b3 in the Kula volcanic field continued until ~11ka, whereas the youngest phase b4 started less than four thousand years ago and may continue in the future.