Akademik Veri Yönetim Sistemi
JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH, 2025 (SCI-Expanded)
The Ulukisla Caldera is a collapse structure within the active Hasanda.g Volcanic Complex (Central Anatolia), situated along the southern branch of the Tuz Golu Fault Zone (TGFZ). This study aims to reconstruct the volcanic history of the Ulukisla Caldera by characterising its associated pyroclastic deposits using tephrostratigraphy, glass chemistry (major and trace elements), and geochronological data (Ar-40/Ar-39 and U-(Th)-Pb). Our findings reveal that the Ulukisla Caldera has undergone at least three major explosive rhyolitic eruptions, which formed the pyroclastic deposits of the Yenipinar Eruption (similar to 442 ka), the Belbashani Eruption (similar to 400 ka), and the Ulukisla Eruption (similar to 326 ka). The Yenipinar unit was produced by an unsteady eruption column originating from paleo-Ulukisla volcanic structure, that deposited pumice fallout layers and interbedded pyroclastic density current (PDC) deposits. The Belbashani Eruption began with a Plinian column that deposited the Belbashani Pumice fallout. This phase was followed by the emplacement of thick PDC deposits and co-ignimbrite lithic lag breccias during the collapse, which ultimately led to the formation of the Ulukisla Caldera. The volume of the Belbashani deposits, including the pumice fallout and the caldera-forming ignimbrite, could reach up to 10 km3 DRE (Dense Rock Equivalent), corresponding to an eruption of magnitude similar to 6. The Ulukisla Pumice resulted from a post-caldera eruption, which did not generate PDCs. The Ulukisla Caldera exhibits an elongated morphology, which is strongly influenced by the NW-SE alignment of the TGFZ. Based on this morphology and the regional tectonic setting, we conclude that the Ulukisla Caldera is a strike-slip/graben caldera. Reconstructing the volcanic history of this newly identified caldera is essential for enhancing our understanding of the Hasanda.g Volcanic Complex. Our findings offer valuable context for future eruptive behaviour, improving the hazards assessment for potential caldera collapses, and contribute to mitigating associated risks.