Glacial meltwater evolution during the deglaciation of THE Fennoscandian Ice Sheet

全球气温上升可能会对冰川融水的产生、分布及其对当代冰块的季节性演变产生影响(例如，Kinglake等人，2017年)。为了更好地分析这种气候驱动的增加的影响，需要更好地了解融水如何从冰上环境向冰下环境移动及其对冰盖动力学和沉积物沉积-侵蚀过程的影响。当涉及到低估季节性和年度融水演变时，冰床界面发挥着关键作用--例如，在高效和分布式冰下排水系统之间的潜在切换(Andrews等人，2014年)。融化水可获得性的这种变化可以在一系列空间和时间尺度上对冰川物质平衡和冰川速度提供重要的内部反馈。例如，在加压期间，分布在冰川下的融水排水系统可能会导致冰川速度的增加。这种冰速增加的必然结果是，它可能会通过增加冰通量，将冰面冰拉到平衡线以下，使更多的冰更容易表面融化，并在正反馈中产生更多融水，从而潜在地施加质量平衡影响。这些过程需要被充分理解，以便有效地集成到或用于检验数值冰盖模式。考虑到在当代冰床界面观察融水过程的困难，地质记录可以为研究过去冰盖融水的演化提供理想的机会。该项目探索了芬兰南部最后一次芬诺斯坎迪亚冰盖消融期间的地质记录。这里提出的工作将利用2米分辨率的激光雷达数字地形模型来绘制EKER及其相关冰川沉积的密集网络。这些特征可能捕捉到了年轻仙女木期Salpausselkämoraine沉积后融水演化和冰盖排放的记录(Stroven等人，2016)。这是一个特别重要的时期，因为它的特点是全球气温上升和伴随而来的冰盖退缩，这可能代表着目前的情况。这一案例研究将提供有关融水可用性如何随时间变化的新细节，以及这与环境变化的其他替代记录之间的关系。地图将被用来计划一系列实地工作活动，以调查最重要的地貌。在这些活动中，学生将收集地球物理数据集，如探地雷达(50 MHz、100 MHz和160 MHz的探地雷达频率)、电阻率层析成像和地震折射，沿倾角和走向剖面。这项实地工作还将使学生能够收集补充的无人机摄影测量、浅层沉积物岩心和基岩样本，以编制地质年代学，以及可用于地面真实地球物理调查的露头测井和采样。学生将掌握收集地质和地球物理测量、野外工作规划和数据管理方面的新技能，这些技能将对广泛的潜在环境、学术和行业职业有用。

Rising global temperatures are likely to lead to an impact on the generation of glacial meltwater, its distribution, and its seasonal evolution on contemporary ice masses (e.g. Kingslake et al., 2017). To better analyse the impacts of this climate-driven increase requires an improved understanding of how meltwater moves from supra- to subglacial settings and its resultant impact on ice sheet dynamics and sediment depositional-erosional processes. The ice-bed interface plays a key role when it comes to understating seasonal and annual meltwater evolution - e.g. potential switches between efficient and distributed subglacial drainage systems (Andrews et al., 2014). Such variations in meltwater availability can provide important internal feedbacks on glacial mass balance and ice velocity across a range of spatial and temporal scales. For example, during episodes of pressurising, a distributed subglacial meltwater drainage system can lead to an increase in ice velocity. The corollary of such an increase in ice velocity is that it could potentially exert a mass balance impact by increasing ice flux, drawing down the ice surface ice below the equilibrium line, making more ice susceptible to surface melting, and generating more meltwater in a positive feedback. These processes need to be robustly understood in order to be effectively integrated into, or used to test, numerical ice sheet models.Given the difficulty in observing meltwater processes at the contemporary ice-bed interface, geological records can provide the ideal opportunity to investigate past ice sheet meltwater evolution. This project explores the geological record of southern Finland during the deglaciation of the last Fennoscandian ice sheet. The work proposed here will exploit the availability of a 2 m resolution LiDAR digital terrain model to map a dense network of eskers and their associated glaciofluvial deposits. These features likely capture a record of meltwater evolution and ice sheet discharge after the deposition of the Salpausselkä moraine during the Younger Dryas (Stroeven et al., 2016). This is a particularly important time period because it is characterised by an increase in global temperature and concomitant ice sheet retreat, that could represent a proxy for the present. This case study will provide new details on how meltwater availability changed through time and how this relates to other proxy records of environmental change. The mapping will be used to plan a number of fieldwork campaigns to survey the most important landforms. During these campaigns the student will collect geophysical datasets, such as ground-penetrating radar (GPR - frequencies of 50 MHz, 100 MHz and 160 MHz), electrical resistivity tomography, and seismic refraction, along dip and strike profiles. This fieldwork will also allow the student to collect supplemental drone-based photogrammetry, shallow sediment cores and bedrock samples for developing a geochronology, as well as outcrop logging and sampling that can be used to ground-truth geophysical surveys. The student will be equipped with new skills in the collection of geological and geophysical surveying, fieldwork planning, and data management that will be useful for wide range of potential environmental, academic, and industry careers.