Holocene paleoenvironmental evolution of the Acıgöl paleo maar lake (Nevşehir, Central Anatolia)

Acıgöl (Nevşehir, Central Anatolia) is a drained crater lake. Acıgöl maar was formed by the violent vapor explosions due to the interaction of hot rhyolitic magma with the (sub-)surface water during the latest Pleistocene. A 844 cm-deep borehole was drilled at the maar and 713 cm-thick Acıgöl Core Succession (ACS) was retrieved. The ACS is mainly composed of lower laminated and upper non-laminated mudstones (sandy, silty, and clayey) with rare organic and volcanic interlayers. Eleven ostracod taxa (Cypris pubera, Plesiocypridopsis newtoni, Heterocypris salina, Eucypris cf. heinrichi, Candona candida, Candona meerfeldiana, Pseudocandona marchica, Cyclocypris sp., Ilyocypris bradyi, Limnocythere inopinata, and Darwinula stevensoni) were determined in this study. Along with ostracods, gastropods (Gyraulus piscinarum and Stagnicola sp.), pelecypods (Pisidium personatum), charophytes, and fish remains were also observed, while diatoms are the most frequent and abundant assemblage of the ACS. The assemblage at the lower parts of ACS mainly indicates wetter, freshwater to oligohaline, and oligotrophic and relatively deep lacustrine conditions alternating with short lake shrinkage intervals. On the other hand, the fauna at the upper part of the ACS points out to saline, shallow, and warmer lacustrine conditions.