Permafrost history in Arctic Siberia - insights from the cryogenic weathering record at El'gygytgyn Crater, NE Siberia

我建议用北极西伯利亚永久冻土条件的变化来确定气候变化。我特别感兴趣的是建立一种沉积学方法，这种方法可以通过地质时间估计低温风化程度和古土壤温度。我的研究探索了北极西伯利亚Elgytgyn火山口湖的湖泊沉积物记录，跨越了过去300.000年，代表了目前北极最长的陆地古气候和环境档案，跨越了过去14.000年的集水区的永久冻土沉积物，以及一组代表现代条件的表面样本。我将研究湖泊、冻土和表层沉积物中的下列矿物学性质，它们被认为反映了东北西伯利亚冰缘的长期动力学：(1)选定的粒度组分中的石英和长石的比率将被用作反映霜冻风化程度的指标。(2)对颗粒的扫描电子显微镜进行图像分析，以提供霜冻风化引起的石英颗粒形态和表面特征的量化。(3)重矿物将作为物源标志，以确定源岩成分和低温碎屑的变化。这些结果为通过第四纪冰川旋回确定永久冻土条件的强度和估计北西伯利亚北极的古土壤温度提供了一个基本工具。这是ICDP资助的深井钻探未来岩芯的概念性成果。

I propose to determine climate variations expressed in variations of permafrost conditions in Arctic Siberia. Particularly I am interested in establishing a sedimentological method that allows estimating the degree of cryogenic weathering and palaeo soil temperatures through geologic time. My studies explore a lake sediment record from Elgygytgyn Crater lake, Arctic Siberia, spanning the last 300.000 years and representing the longest terrestrial palaeoclimate and -environment archive for the Arctic at present, permafrost sediments from the catchment spanning the last 14.000 years, and a set of surface samples representing modern conditions. I will study the following mineralogical properties in lake, permafrost, and surface sediments, which are considered to mirror long term periglacial dynamics in NE Siberia: (1) The ratio of quartz to feldspar in selected grain size fractions will be used as an indicator reflecting the degree of frost weathering. (2) Image analysis of scanning electron micrographs of particles will be performed to provide a quantification of quartz grain morphology and surface features stemming from frost weathering. (3) Heavy minerals will be used as provenance indicators to define changes in source rock composition and cryogenic detritus. The results prepare a fundamental tool that allows determining the intensity of permafrost conditions through Quaternary glacial cycles and estimating palaeo soil temperatures in the North Siberian Arctic. This is a conceptual outcome of future cores from ICDP funded deep drillings.