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

控制凡湖演化的火山、气候和地球动力学因素（土耳其）

• 批准号: 270753745
• 负责人: Professor Dr. Hans-Ulrich Schmincke
• 金额: --
• 依托单位: Forschungseinheit Magmatische und Hydrothermale Systeme
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/270753745?language=en
• 关键词: Volcanic; climatic; geodynamic; factors; controlling

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.

该项目的目标是获得一个长约220米、约600ka的古老沉积岩芯的高分辨率年代学，该岩心是在(土耳其)碱性的Van湖沉积物中钻取的，包含约500个互层的Tephra层。在选择含有足够的斜长石(40Ar/39Ar)和锆石/雪金石斑晶(U-Th)/He单晶测年的合适样品之前，将对原生来源的Tephra层进行岩石学和EMP和XRF分析。强大的年代学框架将允许校准几种类型的古气候和地球动力学指标。第二个目标是基于对主要地震反射层的岩性和年龄的分析，重建凡湖主要湖面变化的震级、年龄、频率和来源(气候与地球动力学)。初步研究表明，尤其是较老的反射体(约200-600ka)主要是邻近涅姆鲁特火山大量褐沸石喷发时产生的同辉沸石浊积岩。第三个目标涉及两个主源火山Nemrut和Süphan的化学-矿物学-时间演化以及对未来爆炸性喷发和相关危险的预测。高分辨率的时间框架还将允许更准确地确定从淡水到碱性湖泊条件的转变，从而确定内姆鲁特火山增长的时间，这可能是导致凡盆地筑坝和隔离的核心因素。