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

我建议确定气候变化的永久冻土条件在北极西伯利亚的变化表示。我特别感兴趣的是建立一种沉积学方法，可以估计整个地质时期的低温风化程度和古土壤温度。我的研究探讨了湖泊沉积物记录Elgygytgyn火山口湖，北极西伯利亚，跨越过去300.000年，代表最长的陆地古气候和环境档案北极目前，多年冻土沉积物从集水区跨越过去14.000年，和一组表面样品代表现代条件。本文将研究西伯利亚东北部湖泊、冻土和表层沉积物中的以下矿物学特征，这些矿物学特征被认为反映了西伯利亚东北部长期的冰缘动力学：（1）在选定的粒度级中，石英与长石的比值将被用作反映霜冻风化程度的指标。(2)将对颗粒的扫描电子显微照片进行图像分析，以提供石英颗粒形态和霜冻风化产生的表面特征的量化。(3)重矿物将被用作物源指标，以确定源岩成分和低温碎屑的变化。结果准备了一个基本的工具，可以通过第四纪冰川循环和估计古土壤温度在北西伯利亚北极的冻土条件的强度。这是ICDP资助的深钻的未来岩心的概念性结果。

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.