Doctoral Dissertation Research: Varves and Varve-Forming Processes in a High Arctic Lake

北极高纬度地区的古环境重建对于一系列目的来说都是极其宝贵的信息来源，特别是作为气候变化的指标，这种变化在高纬度地区更为明显。 北极高纬度湖泊一直是许多古环境重建的信息来源，因为它们的流域和沉积物通常是不受干扰的，冰盖限制了风驱动的干扰，而且它们接收高度季节性的沉积物输入。 高纬度北极地区的冰川湖泊沉积物特别有用，因为每年到半年的温度分辨率是可能的，沉积物供应通常是不受限制的。 这个博士论文研究项目将研究如何在北极湖泊形成纹藻（不同的年度沉积层）。 该项目将研究加拿大努纳武特埃尔斯米尔岛图堡湖的纹管和纹管形成过程。 图堡湖是由冰穿过峡湾口形成的，形成了一个湖泊，海水被困在淡水之下。 这导致了水柱的强烈化学和密度分层，以及湖底的缺氧。 因此，穴居生物无法干扰河流和溪流带入湖泊的沉积物，每年都有相对未受干扰的沉积物层积累。 沉积物以这种方式积累了3,000多年，因此该湖包含了异常长的原始环境变化记录。 该项目的具体任务是通过监测湖中的物理过程来了解沉积物的现代分布和沉积情况，并阐明最近沉积的沉积物（上世纪左右沉积的沉积物）在空间、时间、物理和化学方面的变化。 将记录物理过程，以监测湖泊内的条件和沉积物的运动。 将同时测量气温和降水量，并将与网络的良好的日期短的重力core.This研究将提供深入了解来自图堡湖的未受干扰的沉积物的气候意义，通过提供一个更好的理解纹形成过程的网络分析最近的沉积。 这些分析将增进对高纬度地区过去气候变化的了解，从而为从长期角度看待未来的变化提供一个框架。 作为博士论文研究改进奖，该奖项还将提供支持，使有前途的学生建立一个强大的独立的研究生涯。

Paleoenvironmental reconstructions from high Arctic settings have been extremely valuable sources of information for a range of purposes, but especially as indices of climatic change, which is amplified at high latitudes. High Arctic lakes have been sources of information for many paleoenvironmental reconstructions because their watersheds and sediments usually are undistrurbed, ice cover limits wind-driven disturbance, and they receive highly seasonal sediment inputs. Glacial lake sediments from the high Arctic are particularly useful, because annual to semiannual temperature resolution is possible and sediment supplies usually are not limited. This doctoral dissertation research project will study of how varves (distinct annual layers of sediments) form in Arctic lakes. The project will examine the varves and varve-forming processes of Lake Tuborg on Ellesmere Island in Nunavut, Canada. Lake Tuborg was formed when ice advanced across the mouth of a fiord, creating a lake with seawater trapped beneath freshwater. This has led to strong chemical and density stratification of the water column and a lack of oxygen at the bottom of the lake. Burrowing organisms therefore could not disturb the sediments that have been carried into the lake by rivers and streams, allowing relatively undisturbed layers of sediment to accumulate each year. The sediments have accumulated in this way for more than 3,000 years, so the lake contains an unusually long, pristine record of environmental change. The specific tasks of this project are to understand the modern distribution and deposition of sediment by monitoring physical processes in the lake and to elucidate spatial, temporal, physical and chemical changes in recently deposited sediments (those deposited over the last century or so). Physical processes will be recorded to monitor within lake conditions and the movement of sediment. Concurrent measurements of air temperature and precipitation will be made, and recent sedimentation will be analyzed with networks of well-dated short gravity cores.This study will provide insight into the climatic significance of undisturbed sediments from Lake Tuborg by providing a better understanding of the varve-forming process. These analyses will improve understanding of past climate change at high latitudes, thereby providing a framework for placing future changes in a long-term context. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising student to establish a strong independent research career.