Origin and Climatic Significance of Rock Glaciers in the McMurdo Dry Valleys: Assessing Spatial and Temporal Variability

本研究的重点是南极洲麦克默多干谷地区岩石冰川和埋藏冰川的历史。岩石冰川是流动的冰和沉积物的混合物，在地球和火星的高山和高纬度地区很常见。尽管外表相似，岩石冰川可以在高度变化的环境和水文条件下形成。主要的研究问题是：1)什么样的环境和气候条件促进了南极岩石冰川的长期保存；2)岩石冰川在南极景观演变和当地水循环中发挥了什么作用；3)岩石冰川可以揭示以前冰川推进的程度和时间？该项目将涉及两个南极实地季节，使用探地雷达对南极岩石冰川内部进行成像，收集冰芯进行化学分析，并收集地表沉积物进行年代测定。干谷是世界的宿主？S最南端陆地生态系统（土壤、河流和湖泊微生物和苔藓）；岩石冰川和地面冰是这些生态系统融水和营养物质的重要来源，但研究很少。这项研究将阐明干谷地区的冰川和水文历史，以及形成岩石冰川的一般环境条件，这些特征通常发生在温暖和/或潮湿的地方。这项研究将为五名研究生/本科生提供支持，他们将在实地积极收集数据，然后对数据进行解释、传播和展示。此外，研究人员还将参与一系列教育活动，包括与马萨诸塞州洛厄尔地区当地K-12的外展活动，如夏季研讨会和课堂参观以及实践活动。一系列水文过程的延时图像，以及该领域研究人员的视频，将成为社区和学校演讲的戏剧性核心。科学界段落：岩石冰川在麦克默多干谷很常见，但集中在几个孤立的地区：泰勒谷西部、赖特谷西部、皮尔斯谷和布尔帕斯。研究人员假设，这些特征的起源和年龄因地区而异：皮尔斯和泰勒山谷的岩石冰川起源于埋藏的冰川冰，而莱特山谷的岩石冰川则是通过永久冻土过程形成的，比如富含冰的talus的动员。为了解决这些假设，该项目将：1)通过野外测绘和对上盖沉积物的光学刺激发光定年，开发岩石冰川的相对和绝对年表；2)通过稳定同位素分析评估干净冰芯的起源；3)确定当今的土壤湿度和温度条件是否有利于岩石冰川的形成/保存。拟议的研究将深入了解麦克默多干谷中埋藏的冰川冰和融水衍生的地面冰的时空分布，对冰川历史的影响，以及岩石冰川在区域水文循环中的潜在作用（以及地面冰作为当地生态系统的水分和营养来源的作用）。该项目将提供形成永久冻土岩石冰川的气候和水文条件的一般约束条件，这些特征通常发生在比现在的麦克默多干谷更温暖、更潮湿的条件下。OSL和宇宙成因暴露的应用对于岩石冰川来说是新颖的，尽管它们在南极洲无处不在并且具有潜在的科学重要性，但地貌特征已被证明难以确定日期。这项研究将为五名研究生/本科生提供支助，他们将参与实地工作，然后解释、传播和介绍数据。研究人员将参加一系列教育活动，包括与马萨诸塞州洛厄尔地区当地K-12的外展活动，如夏季研讨会和课堂参观以及实践活动。

Paragraph for Laypersons:This research focuses on the history of rock glaciers and buried glacial ice in the McMurdo Dry Valleys region of Antarctica. Rock glaciers are flowing mixtures of ice and sediments common throughout alpine and high-latitude regions on Earth and Mars. Despite similar appearances, rock glaciers can form under highly variable environmental and hydrological conditions. The main research questions addressed here are: 1) what environmental and climatological conditions foster long-term preservation of rock glaciers in Antarctica, 2) what role do rock glaciers play in Antarctic landscape evolution and the local water cycle, and 3) what can rock glaciers reveal about the extent and timing of previous glacial advances? The project will involve two Antarctic field seasons to image the interior of Antarctic rock glaciers using ground-penetrating radar, to gather ice cores for chemical analyses, and to gather surface sediments for dating. The Dry Valleys host the world?s southernmost terrestrial ecosystem (soil, stream and lake micro-organisms and mosses); rock glaciers and ground-ice are an important and poorly-studied source of meltwater and nutrients for these ecosystems. This research will shed light on the glacial and hydrological history of the Dry Valleys region and the general environmental conditions the foster rock glaciers, features that generally occur in warmer and/or wetter locations. The research will provide support for five graduate/undergraduate students, who will actively gather data in the field, followed by interpretation, dissemination and presentation of the data. Additionally, the researchers will participate in a range of educational activities including outreach with local K-12 in the Lowell, MA region, such as summer workshops and classroom visits with hands-on activities. A series of time-lapse images of hydrological processes, and videos of researchers in the field, will serve as a dramatic centerpiece in community and school presentations.Paragraph for Scientific Community:Rock glaciers are common in the McMurdo Dry Valleys, but are concentrated in a few isolated regions: western Taylor Valley, western Wright Valley, Pearse Valley and Bull Pass. The investigators hypothesize that the origin and age of these features varies by region: that rock glaciers in Pearse and Taylor valley originated as buried glacier ice, whereas rock glaciers in Wright Valley formed through permafrost processes, such as mobilization of ice-rich talus. To address these hypotheses, the project will: 1) develop relative and absolute chronologies for the rock glaciers through field mapping and optically stimulated luminescence dating of overlying sediments, 2) assess the origin of clean-ice cores through stable isotopic analyses, and 3) determine if present-day soil-moisture and temperature conditions are conducive to rock glacier formation/preservation. The proposed research will provide insight into the spatial and temporal distribution of buried glacier ice and melt-water-derived ground ice in the McMurdo Dry Valleys, with implications for glacial history, as well as the potential role of rock glaciers in the regional hydrologic cycle (and the role of ground-ice as a source for moisture and nutrient for local ecosystems). The project will provide general constraints on the climatic and hydrologic conditions that foster permafrost rock glaciers, features that generally occur under warmer and wetter conditions than those found in the present-day McMurdo Dry Valleys. The application of OSL and cosmogenic exposuredating is novel to rock glaciers, geomorphic features that have proven difficult to date, despite their ubiquity in Antarctica and their potential scientific importance. The research will provide support for five graduate/undergraduate students, who will participate in the field work, followed by interpretation, dissemination and presentation of the data. The researchers will participate in a range of educational activities including outreach with local K-12 in the Lowell, MA region, such as summer workshops and classroom visits with hands-on activities.