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

外行人段：这项研究的重点是南极洲麦克默多干燥山谷地区岩石冰川和埋藏的冰川的历史。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，但岩石冰川可以在高度多变的环境和水文条件下形成。这里涉及的主要研究问题是：1)什么环境和气候条件促进了南极洲岩石冰川的长期保存；2)岩石冰川在南极地貌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范围和时间？该项目将包括两个南极野外季节，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，并收集表层沉积物进行测年。干燥的山谷拥有世界最南端的陆地生态系统(土壤、溪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化水和营养物质的重要来源，但研究很少。这项研究将阐明干旱山谷地区的冰川和水文历史，以及孕育岩石冰川的一般环境条件，这些特征通常出现在较温暖和/或较潮湿的地区。这项研究将为五名研究生/本科生提供支助，他们将积极收集实地数据，然后对数据进行解释、传播和介绍。此外，研究人员还将参加一系列教育活动，包括与马萨诸塞州洛厄尔地区的当地K-12学校进行外联活动，如暑期讲习班和带实践活动的课堂访问。一系列延时的水文过程图像和实地研究人员的视频将作为社区和学校演示的戏剧性中心。科学社区段落：岩石冰川在麦克默多干谷很常见，但集中在少数与世隔绝的地区：西部泰勒山谷、西部莱特谷、皮尔斯山谷和牛山口。研究人员假设，这些特征的起源和年代因地区而异：皮尔斯和泰勒山谷的岩石冰川起源于埋藏的冰川，而莱特山谷的岩石冰川是通过永久冻土过程形成的，例如动员富含冰的距骨。为了解决这些假设，该项目将：1)通过实地测绘和上复沉积物的光激发发光测年，编制岩石冰川的相对和绝对年表；2)通过稳定的同位素分析评估干净冰芯的来源；3)确定当今的土壤水分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河谷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水分和养分来源的作用)。该项目将对促进永久冻土岩石冰川形成的气候和水文条件提供一般限制，这些冰川特征通常出现在比目前麦克默多干燥山谷更温暖、更潮湿的条件下。OSL和宇宙成因暴露测年在岩石冰川上的应用是新颖的，尽管它们在南极洲无处不在，而且具有潜在的科学意义，但事实证明，这些地貌特征很难确定日期。这项研究将为五名研究生/本科生提供支持，他们将参与实地工作，随后将对数据进行解释、传播和介绍。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学校的外联活动，如暑期讲习班和课堂访问实践活动。

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.