Gökhan Atıcı , Bjarne Friedrichs , Mehmet Çobankaya , Martin Danišík , Evren Atakay , Esra Yurteri , Axel K. Schmitt
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引用次数: 0
Abstract
Modern Lake Gölcük near the city of Isparta partially fills a caldera that is the focal point of protracted alkaline, potassic–ultrapotassic volcanism in southwestern Anatolia. Because of Gölcük's proximity to a major regional urban center, and field indications for far-reaching pyroclastic density currents (PDC) erupted from this caldera, improved constraints on eruptive recurrence and timing are required. Through field work and combined UTh and (UTh)/He zircon geochronology, the duration of known volcanism at Gölcük has been extended, both to older and, importantly, to younger ages than previously reported. Early activity in the Late Miocene–Pliocene (Stage 1, 6.0–4.2 Ma) was mostly effusive, whereas explosive activity started in the Early Pleistocene (Stage 2, 2.2–1.8 Ma) forming nine PDCs of the Serençay valley ignimbrite sequence. Following a hiatus, PDC and fallout emplacement resumed during Stage 3 (520–480 ka) and Stage 4 (150 ka), with the modern caldera likely being the result of the Stage 4 Çay ignimbrite eruption. UTh zircon crystallization ages of antecrysts, especially in Stage 4 and 5 pumice, clearly implicate Gölcük as the source of the Stage 2 and 3 explosive eruptions. Stage 5 includes effusive activity and dome formation, but also at least four explosive eruptions starting at c. 24 ka. The discovery of the here termed Isparta ignimbrite, which erupted from Gölcük caldera at 10.7 ± 0.7 ka (2 σ uncertainty), identifies it as an active volcano. Frequent eruptions at recurrence intervals of 4–5 ka during the Late Pleistocene–Holocene transition warrant future research regarding its hazard potential. This also implies that Gölcük may have erupted distal tephra markers for this climatically important interval.
期刊介绍:
An international research journal with focus on volcanic and geothermal processes and their impact on the environment and society.
Submission of papers covering the following aspects of volcanology and geothermal research are encouraged:
(1) Geological aspects of volcanic systems: volcano stratigraphy, structure and tectonic influence; eruptive history; evolution of volcanic landforms; eruption style and progress; dispersal patterns of lava and ash; analysis of real-time eruption observations.
(2) Geochemical and petrological aspects of volcanic rocks: magma genesis and evolution; crystallization; volatile compositions, solubility, and degassing; volcanic petrography and textural analysis.
(3) Hydrology, geochemistry and measurement of volcanic and hydrothermal fluids: volcanic gas emissions; fumaroles and springs; crater lakes; hydrothermal mineralization.
(4) Geophysical aspects of volcanic systems: physical properties of volcanic rocks and magmas; heat flow studies; volcano seismology, geodesy and remote sensing.
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(6) Volcano hazard and risk research: hazard zonation methodology, development of forecasting tools; assessment techniques for vulnerability and impact.