Volcanic, climatic and geodynamic factors controlling the evolution of Lake Van (Turkey)

该项目的目标是在碱性的Van湖（土耳其）沉积物中钻取约220米长，约600万年历史的沉积物岩心，其中包含约500个相互层状的tephra层。在选择合适的样品之前，将对原始来源的Tephra层进行岩性检查，并通过EMP和XRF进行分析，这些样品含有足够的斜长石（40Ar/39Ar）和锆石/chevkinite斑晶(U-Th)/He单晶定年。稳健的年代框架将允许校准几种类型的古气候和地球动力学代用物。第二个目标是基于对主要地震反射体的岩性和年龄的分析，重建凡湖主要湖泊水位变化的震级、年龄、频率和起源（气候与地球动力学）。初步研究表明，特别是较老的反射物（约200-600 ka）主要是邻近的Nemrut火山大量喷发时产生的同烟灰岩浊积岩。第三个目标涉及两个主要火山源Nemrut和s<s:1>潘的化学-矿物学-时间演化，以及对未来爆炸性喷发和相关危害的预测。高分辨率的时间框架也将允许更精确地确定从淡水到碱性湖泊条件的转变，因此Nemrut火山的生长时间可能是导致Van盆地大坝和隔离的核心因素。

The goal of the project is a high-resolution chronology of a ca. 220 m long and ca. 600 ka old sediment core drilled in the alkalic Lake Van (Turkey) sediments, containing ca. 500 interbedded tephra layers. Tephra layers of primary origin will be scrutinized lithologically and analyzed by EMP and XRF prior to selection of suitable samples containing sufficient anorthoclase for 40Ar/39Ar and zircon/chevkinite phenocrysts for (U-Th)/He single crystal dating. The robust chronological framework will allow calibrating several types of paleoclimate and geodynamic proxies. A second goal concerns reconstruction of magnitude, age, frequency and origin (climate vs. geodynamics) of major lake level changes of Lake Van based on an analysis of the lithology and age of the main seismic reflectors. Preliminary studies suggest that especially the older reflectors (ca. 200-600 ka) are mainly syn-ignimbrite turbidites generated during voluminous ignimbrite eruptions from adjacent Nemrut volcano. A third objective concerns the chemical-mineralogical-temporal evolution of the two main source volcanoes Nemrut and Süphan and the prediction of future explosive eruptions and associated hazards. The high-resolution temporal framework will also allow to more precisely determine the transition from freshwater to alkaline lake condition and therefore the timing of the growth of Nemrut volcano probably the central factor leading to damming and isolation of Van basin.