Late Quaternary rhyolitic eruptions from the Acigöl Complex, central Turkey

Abstract

Two major rhyolitic tephra units (Lower and Upper Acigöl Tuffs) have been erupted from the Acigöl Complex. The Lower Acigöl Tuff (>13km 3 uncompacted volume) was erupted more than c. 180 ka ago, forming an extensive Plinian pumice-fall deposit with associated ashfall and ignimbrite. Well-developed ignimbrite veneer facies are preserved where the pyroclastic flows passed over hilly topography. Following the eruption, a thick rhyolite coulée (Bogazköy obsidian) was extruded. The Upper Acigöl Tuff eruption (age 70 < t< 150 ka) generated a second major Plinian deposit, an ignimbrite preserved up to 24 km from the vent, and an 80 m thick proximal succession of surge and fallout deposits; it resulted in collapse of the 6×5 km Acigöl caldera. The two major tuffs are chemically similar but can be distinguished on the basis of lithic populations. Subsequent rhyolitic activity formed the c. 0.25 km 3 dome of Kocadag Tepe (c.70ka) and five dome/maar clusters (c. 20 ka). Late Quaternary and/or Holocene basalts and andesites surround the Acigöl caldera, which developed in a zone of sinistral shear associated with approximate N-S compression. Vent distribution patterns, the eruption of young basalts, and the crystal-poor nature of the c. 20 ka rhyolites are consistent with basaltic stoking of a sizeable silicic magma chamber beneath the Acigöl Complex.

Tephrostratigraphic studies on a sediment core from Lake Prespa in the Balkans

“…The only known source with mainly alkaline volcanism in the surrounding of Lake Prespa are the volcanic districts of the Italian Peninsula, which also would match with predominant westerly winds in the region. Volcanic products of the Aegean area (e.g., Greece, Santorini) and Central Anatolia (e.g., Turkey) show mainly calc-alkaline affinity (e.g., Keller et al, 1990;Druitt et al, 1995;Paterne et al, 2008) and those of Germany (Eifel volcanic district) and France (Massif Central) have never been recorded close to the study area (e.g., Van den Bogaard, 1995;Schmincke et al, 1999;Walter-Simonnet et al, 2008;Riede et al, 2011). Traces of the Vedde Ash from Iceland were recently found in the Lake Bled, Slovenia (Lane et al, 2011a), but not yet on the Balkan Peninsula.…”

Growth, destruction and volcanic facies architecture of three volcanic centres in the Miocene Uşak–Güre basin, western Turkey: Subaqueous–subaerial volcanism in a lacustrine setting

“…250 m. Andesitic lava flow sequences, some of which flowed up to 1.5 km radially, drape the flanks of the dome structure (e.g. Acıgöl complex in Turkey, Druitt et al, 1995; Nemrut Caldera in Turkey, Karaoğlu et al, 2005). Intense potassic and argillic-type hydrothermal alterations are observed at the southern part of the edifice, while the centre of the volcano has been subjected to magma-water interactions such as pyroclastic surge deposits for explosive and baked surfaces along lavas and unconsolidated lacustrine deposits for effusive volcanism (e.g.…”

Weak compositional zonation in a silicic magmatic system: Incesu ignimbrite, Central Anatolian Volcanic Province (Kayseri – Turkey)

“…The volcanics vary from rhyolite to basalt (Beekman, 1963;Pasquare, 1968;Keller, 1974;Innocenti et al, 1975;Batum, 1978a;Ercan, 1987;Ercan et al, 1987Ercan et al, , 1990Druitt et al, 1995;Aydar and Gourgaud, 1998). Most of the volcanics have a medium to high-K calc-alkaline composition that is typical of the collisionrelated volcanism.…”