Collaborative Research: The Pulse of Holocene Glaciations in New Zealand's Southern Alps

人类文明是在大约11500年前开始的全新世时期发展起来的。全新世被经典地认为是气候非常稳定的时期。然而，最近的古气候记录表明，全新世确实发生了气候突变，其中一些变化与人类历史的曲折不谋而合。尽管全新世气候直接影响人类栖息地、时空格局、自然变异性和驱动机制，但人们对全新世气候变化的可靠评估造成了困难。全新世的气候波动大到足以影响人类，但小到足以迷失在噪音中？大多数地质气候记录中的自然变异性。然而，地球上许多地区的冰川对全新世的气候变化做出了敏感而迅速的反应，并产生了独特的地貌或冰雹。这些地貌的年龄直接指示了这些大陆全新世气候变化的发生时间，但到目前为止，还缺乏一个强大、统一和可靠的冰雹测年工具。宇宙成因测年领域的最新进展表明，冰雹可以在整个全新世时期以前所未有的精度进行测年，这为研究全新世气候变化的特征提供了新的视角。这笔赠款是一项跨学科、多小组的工作，旨在通过应用高精度的10Be表面暴露测年(SED)和10Be生产率的本地校准来确定新西兰-S南阿尔卑斯山全新世冰川序列的年龄，以评估潜在的气候变化，并从半球间的角度分析结果。新西兰似乎是进行这项研究的理想地点：(1)受热带和极地信号影响，中纬度南部的陆地古气候数据稀少，迫切需要评估气候变化的区域足迹；(2)个别冰川前保存了多达5个或更多不同的全新世冰川，使人们能够深入了解中纬度南部全新世气候变化的细节，包括？小冰期？；(3)南部中纬度地区的冰川对大气/海洋变化做出反应(没有大陆气候影响)；(Iv)新西兰的一般地貌背景和岩石类型非常适合我们的SED方法；(V)新西兰已经绘制了一套详细的冰川地貌(地貌)图？S已经绘制了南阿尔卑斯山，详细重建了古雪线，我们的合作者正在进行冰川建模研究，使其成为地球上研究得最好的冰川记录之一。为了获得中纬度南部黄金地段的区域详细冰川年表，我们将把半干旱的阿尔卑斯山东侧和非常潮湿的南阿尔卑斯山西侧的大型山谷冰川系统与较小的山谷冰川系统结合起来，评估不同降水制度对冰川的重要性。我们将把我们的冰川年代学与来自新西兰和其他地方的少数几个记录进行比较，测试全新世冰川脉动的区域到半球之间的特征。这里的焦点之一将是被称为小冰期的时间段，那里有欧洲冰川的详细历史记录。智力上的优点和更广泛的影响：我们希望通过解决以下关键问题来极大地提高我们对全新世中纬度南部冰川波动驱动因素的理解：全新世冰川是跨半球的吗？是大气环流变化导致了这些事件，还是全球和区域力量同时参与了这些事件？该项目是创建南中纬度全新世冰川波动参考数据集的独特机会。这些数据对于校准气候模型以及气候科学家和冰川地质学家的广大社区应该具有很高的价值。我们进一步发展了宇宙成因的10Be测年方法，我们的地球化学/年代学工具包将适用于未来的全新世冰雹测年项目。在这个项目期间，新的南阿尔卑斯山中段地貌图将根据我们的冰川年代学进行更新。除了扩展LDEO/CU的课程外，还将教育一名女硕士学生，几名早期职业科学家将参与其中，以及高中生和教师(拉蒙特-多尔蒂中学现场计划？)将积极参与这一项目。除了标准的数据发布，我们还将在公共活动中介绍该项目，例如一年一度的L-DEO开放日(通常有4,000名参观者)，并将利用我们与纽约公共媒体的密切联系，在报纸(纽约时报)和电视(历史频道)上对该项目进行报道。该项目将促进拉蒙特-多尔蒂地球天文台、缅因州大学、加州大学伯克利分校和新西兰GNS科学中心之间富有成效的合作。

Human civilizations have developed during the Holocene epoch that began approximately 11,500 years ago. The Holocene is classically considered a period of outstanding climate stability. However, recent paleoclimate records suggest that abrupt climatic shifts did occur within the Holocene and that some of those coincided with twists and turns in human history.Although directly influencing human habitat, temporal and spatial patterns, natural variability and driving mechanisms of Holocene climate are not well understood, hampering reliable evaluation of current climate change. Holocene climate swings were large enough to impact humans but small enough to get lost in the ?noise? of natural variability in most geological climate records. Glaciers in many areas on Earth, however, have responded sensitively and quickly to the Holocene climate changes and have produced distinctive landforms, or moraines. The age of these landforms directly indicates when these continental Holocene climate changes occurred, but so far a robust, uniform and reliable dating tool for moraines was lacking.Recent progress in the field of cosmogenic dating demonstrates that moraines can be dated with unprecedented accuracy throughout the Holocene period, allowing novel perspectives on the characteristics of Holocene climate changes. This grant is an interdisciplinary, multi-group effort to date the Holocene moraine sequences in New Zealand?s Southern Alps by applying high-precision 10Be surface exposure dating (SED) combined with local calibration of the 10Be production rate, to evaluate the underlying climate changes, and to analyze the results within an interhemispheric perspective. New Zealand appears to be an ideal location for such a study: (i) terrestrial paleoclimate data from southern mid-latitudes, influenced by tropical and polar signals, are sparse and urgently needed to evaluate the regional footprint of climate changes; (ii) up to five or more different Holocene moraines are preserved in front of individual glaciers, allowing insight into the details of the Holocene climate changes in southern mid-latitudes, including the ?Little Ice Age?; (iii) glaciers in southern mid-latitudes respond to atmospheric/oceanic changes (no continental climate effects); (iv) the general landform setting and rock type is well suited for our SED approach; (v) a suite of detailed glacier landform (geomorphologic) maps of New Zealand?s Southern Alps have been developed, paleo-snowlines have been reconstructed in detail, and glaciological modeling studies are ongoing by our collaborators, making this one of the better investigated glacier records on Earth. To achieve a regional, detailed chronology of glaciations on a prime site in southern mid-latitudes, we will combine large valley glacier systems with smaller valley glaciers on both, the semi-arid east flank as well as on the very humid west flank of the Southern Alps, evaluating the importance of different precipitation regimes for glaciations. We will compare our glacial chronologies to the few records available from New Zealand and elsewhere, testing the regional to inter-hemispheric character of the Holocene glacial pulse-beat. One of the foci herein will be the time period known as the ?Little Ice Age, where detailed historical records are available for European glaciers.Intellectual Merit and Broader Impacts: We expect to greatly improve our understanding of drivers of Holocene glacier fluctuations in southern mid-latitudes by tackling key questions such as: Were Holocene glaciations inter-hemispheric? Were atmospheric circulation changes involved in driving these events or were both, global and regional forces involved? This project represents a unique opportunity to create a reference data set of Holocene glacial fluctuations in southern mid-latitudes. These data should be of high value to calibrate climate models and to the broad community of climate scientists and glacial geologists. We further develop the method of cosmogenic 10Be dating and our geochemical/geochronological tool-kit will be applicable to future Holocene moraine-dating projects. The new atlas of geomorphic maps of the central Southern Alps will be updated with our glacial chronologies during this project.In addition to extending the LDEO/CU curriculum, a female master student will be educated, several early-career scientists will be involved, and high school students and teachers (?Lamont-Doherty Secondary School Field Program?) will actively participate in this project. Beyond standard data dissemination, we will present the project at public events, such as the annual L-DEO Open House (typically 4,000 visitors) and will use our close contacts to New York public media to seek coverage of this project in newspapers (New York Times) and television (History Channel). The project will foster the fruitful collaboration between the Lamont-Doherty Earth Observatory, the University of Maine, the UC Berkeley, and the GNS Science, NZ.