Detangling Flow Regimes and Paleoclimate in the Deepest Section of the EDML Ice Core using U-series Ages.

Aciego/1043367该奖项支持开发一种新的方法来确定来自深冰芯的样品的绝对年龄。该项目将：(1)证明铀系列测年方法在高积累速率冰芯上的有效性，以及(2)解决EPICA Dronning-Maud Land冰芯在较低300m处测年的不确定性。测年良好的冰芯上部(在2415.7米处至15000年)将为验证U系列方法确定的年龄提供极好的约束。经过验证，并可能对实验室化学进行调整后，该方法将应用于EDML冰芯下部的一套未知年龄的冰样。在这个冰芯下方300米范围内，冰层的倾斜和折叠干扰了气候记录，而且由于冰如何流动的不确定性，无法确定是否可以获得准确的年龄数据来获取气候变化的记录，或者冰的混合是否过于不连贯。作为方法的一部分，PI将使用为超小样本开发的气体吸附技术来测量冰中包括的粉尘的表面积；这些测量将在BET纳米尺度上进行，该纳米尺度将从该项目的资金中购买。学术价值：拟议中的研究将有助于我们理解冰层折叠和倾斜的地球物理过程。这将允许从物理上变形和干扰的冰芯中恢复新的古气候记录，而这些冰芯以前不能进行准确的年代测定。更广泛的影响：这笔资金将为一名博士生提供支持，并为他们作为地球化学和古气候研究人员的培训做出贡献。PI将教授地球表面过程(包括冰川学)和高级同位素地球化学课程。与本研究相关的工作将作为教学工具整合到课堂中，提供动手的、相关的学习体验。此外，作为这项研究的一部分进行检查的样本将从德国不来梅港的AWI档案馆获得，这是美国的PI与欧洲冰芯社区合作的一部分。

Aciego/1043367This award supports the development of a new method for determining the absolute age of samples from deep ice cores. The project will: (1) prove the efficacy of the Uranium-series dating method on a high accumulation rate ice core, and (2) address the uncertainties in the age dating of the EPICA Dronning-Maud Land (EDML) ice core in the lower 300 m. The well-dated upper section of the ice core (down to 150,000 years at 2415.7 m) will provide excellent constraints to validate the ages determined by the U-series method. After verification, and possible adjustments to the laboratory chemistry, the method will be applied to a suite of ice samples of unknown age in the lower part of the EDML ice core. Within the lower 300 m of this ice core, the climate records are disturbed by tilting and folding of the ice, and, due to the uncertainties in how the ice has flowed, it is impossible to determine if accurate age dates can be obtained to access the record of climate change, or if mixing of the ice is too incoherent. As part of the methodology, the PI will measure surface area of dust included in the ice using a gas adsorption technique developed for ultra-small samples; these measurements will be made on a BET nano-scale which is to be purchased from the funding of this project. Intellectual Merit: The proposed research will contribute to our understanding of geophysical processes that fold and tilt ice. This will allow new paleoclimate records to be recovered from ice cores that have been physically deformed and disturbed and previously did not permit accurate dating. Broader Impacts: This funding will provide support for one PhD graduate student and contribute to their training as a researcher in geochemistry and paleoclimate studies. The PI will teach classes in earth surface processes (including glaciology) and in advanced isotope geochemistry. Work related to this research will be integrated as a teaching tool into the classroom to provide a hands-on, relevant learning experience. Furthermore, samples examined as part of this research will be made available from the AWI archive in Bremerhaven, Germany as part of the collaboration between the PI in the United States and the European ice core community.