EAGER: Testing Late-Pleistocene and Holocene Climate Change in Southeastern Australia with Multi-proxy Analyses of Alpine Lake Sediments, Kosciuszko National Park, Australia

该项目由探索性研究早期概念基金(AGUGER)奖概念资助，旨在基于对澳大利亚新南威尔士州雪山最高部分三个高山岩层(湖泊)沉积岩芯的多重代理分析，测试关于澳大利亚东南部晚更新世至晚全新世气候变化的想法。尽管最近努力重建南半球主要冰川后气候事件(如南极气候逆转、小冰期)的规模和空间分布，但替代数据中的主要差距，尤其是在澳大利亚，阻碍了这些重建；这一差距反映了南半球缺乏保存高分辨率、连续古气候记录的地点。新南威尔士州科斯丘兹科国家公园(KNP)的阿尔卑斯湖是这一问题的显著例外：自18,000-20,000年前冰川消融以来，五个湖一直充当着沉积物陷阱的角色。KNP的所有湖泊在澳大利亚冬季的高峰期(7-9月)冻结，这为深层取心提供了稳定的表面。蓝湖此前的岩芯形成于20世纪70年代的S，尽管对这些岩芯的分析有限，但它们表明，自18000年前的冰川消融以来，蓝湖一直在捕获沉积物。在西华盛顿大学(WWU)的小额资助下，研究人员于2016年从该湖收集了一个试点岩芯，以测试从该湖收集连续记录的可行性。在iTrax多扫描仪上对岩心进行的初步分析表明，沉积物保存完好，结构高度合理。目视图像和X射线图像都表明整个岩心都有亚厘米级的地层；根据上面的年龄估计，这种地层学将在整个岩心提供亚百年的分辨率(约20年/厘米)。如果通过测年来证实，这种分辨率在澳大利亚南部将是史无前例的。这个单一的岩心展示了仅在蓝湖保存下来的特殊地层记录，并意味着在公园的其他较小的鞑靼中可能存在类似的、互补的记录。为了测试这一点，研究人员提议在公园里另外两个塔尔湖：阿尔比纳湖和俱乐部湖；虽然比蓝湖浅，但这两个湖都占据着基岩盆地，所以比起淤泥堰塞湖，更不容易受到与干旱有关的湖面波动的影响。它们不同的大小、深度和盆地几何形状可能会为蓝湖提供补充记录，使研究人员能够根据岩心的相关性测试区分本地和区域信号。除了收集岩芯外，澳大利亚将在现有的澳大利亚基金下在坎特伯雷大学/昆士兰大学进行一系列分析，以测试这些湖泊的岩芯的古气候潜力。更广泛的影响包括提供新的数据和洞察过去可能发生的干旱和温度变化的频率和程度，以及为当地机构和水电公司的资源经理提供信息。该项目还将为早期职业科学家、本科生和研究生提供有价值的培训。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This project is funded, under the auspices of the EArly Concept Grant For Exploratory Research (EAGER) award concept, to test ideas on late-Pleistocene through late-Holocene climate change in southeastern Australia based on multiproxy analyses of sediment cores collected from three alpine tarns (lakes) in the highest portions of the Snowy Mountains, New South Wales, Australia. Despite recent efforts to reconstruct the magnitude and spatial distribution of major post-glacial climate events in the Southern Hemisphere (e.g., Antarctic Climate Reversal, Little Ice Age), key gaps in proxy data, most notably in Australia, hinder these reconstructions; this gap reflects a dearth of sites on the continent that preserve high resolution, continuous paleoclimate records. The alpine tarns in Kosciuszko National Park (KNP), New South Wales, represent notable exceptions to this problem: five tarns have acted as continuous sediment traps since deglaciation 18,000-20,000 years agoAll lakes in KNP freeze during the peak of the Austral winter (July-September), which provides stable surfaces for deep coring. Blue Lake was previously cored in the 1970’s, and although analyses of those cores were limited, they indicated that the lake has trapped sediment continuously since deglaciation (18,000 years ago). With a small grant from Western Washington University (WWU), the researchers collected a pilot core from the lake in 2016 in order to test the viability of collecting continuous records from the lake. Initial analysis of the core on an ITRAX multi-scanner demonstrates that the sediments are well preserved and highly structured. Both visual and X-ray imagery indicate sub-centimeter scale strata throughout the core; based on the age estimates from above, this stratigraphy would provide sub-centennial resolution (ca. 20 year/cm) throughout the core. If borne out by dating, such resolution would be unprecedented in southern Australia.This single core demonstrates the exceptional stratigraphic record preserved in Blue Lake alone, and implies that similar, complementary records likely exist in the other, smaller tarns in the park. To test this, the researchers propose to core two additional tarns in the park: Lake Albina, and Club Lake; although shallower than Blue Lake, both occupy bedrock basins and so are less susceptible to lake-level fluctuations related to droughts than sediment dammed lakes. Their differing sizes, depths, and basin geometries might provide complementary records to Blue Lake, allowing the researchers to distinguish between local and regional signals based on correlation testing of the cores.In addition to collecting cores, a suite of analyses to test the paleoclimate potential of cores from these lakes will be conducted at University of Canterbury/University of Queensland by Australian collaborators under existing Australian funding.The Broader Impacts include providing new data and insights into the frequency and magnitude of possible past droughts and temperature variations as well as informing resource managers in local agencies and water and power utility companies. The project will also provide valuable training of early career scientists and undergraduates and graduate students.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.