Late Pleistocene zircon ages for intracaldera domes at Golcuk (Isparta, Turkey)


Schmitt A. K. , Danisik M., Siebel W., ELİTOK Ö. , Chang Y., Shen C.

JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH, cilt.286, ss.24-29, 2014 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 286
  • Basım Tarihi: 2014
  • Doi Numarası: 10.1016/j.jvolgeores.2014.08.027
  • Dergi Adı: JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH
  • Sayfa Sayıları: ss.24-29

Özet

Pleistocene to Quaternary volcanism in the Isparta region (SW Anatolia, Turkey) comprises potassic lavas and pyroclastic deposits, which are largely centered around Golcuk caldera. Trachytic intracaldera lava domes represent the latest eruptive event at Golcuk, and their eruption age is crucial for defining a minimum age for the preceding caldera-forming explosive eruption. Here, we present combined U-Th and (U-Th)/He zircon geochronological data for two intracaldera lava domes constraining their crystallization and eruption ages, respectively. U-Th zircon crystallization ages peak between ca. 15 and 25 ka. In rare instances U-Th zircon crystallization ages date back to ca. 59 and 136 ka. U-Th zircon crystallization ages also permit (U-Th)/He eruption ages from the same crystals to be individually corrected for uranium series decay chain disequilibrium, which is mainly due to the deficit of the intermediate daughter Th-230 in zircon. Average disequilibrium-corrected (U-Th)/He zircon ages are 14.1 +/- 0.5 and 12.9 +/- 0.4 ka (1 sigma). These ages are indistinguishable within analytical uncertainties suggesting that both lavas erupted quasi simultaneously. This contradicts published K-Ar ages that suggest an extended hiatus from ca. 52 to 24 ka between intracaldera dome eruptions. Evidence for protracted zircon crystallization over several thousands of years prior to eruption indicates the presence of a long-lived magma reservoir underneath Golcuk caldera. Implications of the revised eruptive geochronology presented here include younger ages for the latest effusive eruptions at Golcuk, and potentially also a more recent explosive eruption than previously assumed. (C) 2014 Elsevier B.V. All rights reserved.