Collaborative Research: Synchronizing the WAIS Divide and Greenland Ice Cores from 30-65 ka BP Using High-resolution 10Be Measurements

该奖项支持一个项目，该项目使用南极西部冰盖（WAIS）分裂冰芯的现有样本，使用共同的年代标记将其时间尺度与格陵兰冰芯的时间尺度对齐。WAIS Divide岩心上部2850米处的钻孔深度为3405米，测年精度很高。剩下的（底部）550米的核心的时间尺度具有较大的不确定性，限制了我们对南极气候突变事件的时间的理解，相对于格陵兰岛在最后一个冰河时期的气候突变事件。这个项目的智力价值在于进一步限制格陵兰岛和南极洲这些突发气候事件的相对时间，以获得对潜在机制的关键见解。该项目的主要目标是通过使用铍-10（一种由宇宙射线在大气中产生的Be的放射性同位素，并在其产生后的1-2年内沉积在雪上）中的共同信号，将WAIS Divide核心与格陵兰冰芯同步，从而将当前的时间尺度从31,000年提高到65,000年。10Be通量在很大程度上与气候信号无关，因为它的产生随太阳活动和地磁场的变化而变化。该项目将进一步加强伯克利和普渡大学的PI与美国和欧洲的冰芯研究人员之间的合作，让本科生参与其研究的许多方面，并继续向代表性不足的学生提供服务。利用宇宙成因10Be对WAIS分水岭冰芯与格陵兰冰芯年代学（GICC05）的直接冰-冰同步，有望将格陵兰和南极洲20多个气候突变事件的相对时间的不确定性降低到几十年。为了实现这一目标，研究人员将在WAIS Divide岩芯中获得2850 ~ 3390 m深度的连续高分辨率10Be记录，并将获得的10Be记录与格陵兰冰芯（包括GISP2和NGRIP）的现有10Be记录进行比较。科学家们将从WAIS分裂核心的约1000个冰样品中分离出10Be，并使用加速器质谱法（AMS）测量每个样品中的10Be浓度。10Be测量的更广泛的影响是，它们还将提供关于拉尚事件的信息，拉尚事件是大约4.1万年前一个长达2000年的低地磁场强度时期，并改进了3万年以上有机样品的14C定年方法的校准。该项目的更广泛影响包括：(1)参与和培训本科生进行冰芯研究和加速器质谱测量；(2)将冰芯和气候研究纳入普渡大学和伯克利SSL正在进行的推广项目；(3)更好地了解过去的气候突变将提高我们预测未来气候变化的能力。(4)评估未来几百年地磁偏移可能带来的威胁。该奖项不需要南极洲的支持。

Welten/1644128 This award supports a project to use existing samples from the West Antarctic Ice Sheet (WAIS) Divide ice core to align its timescale with that of the Greenland ice cores using common chronological markers. The upper 2850 m of the WAIS Divide core, which was drilled to a depth of 3405 m, has been dated with high precision. The timescale of the remaining (bottom) 550 m of the core has larger uncertainties, limiting our understanding of the timing of abrupt climate events in Antarctica relative to those in Greenland during the last ice age. The intellectual merit of this project is to further constrain the relative timing of these abrupt climate events in Greenland and Antarctica to obtain crucial insight into the underlying mechanism. The main objective of this project is to improve the current timescale of the WAIS Divide core from 31,000 to 65,000 years ago by synchronizing this core with the Greenland ice cores using common signals in Beryllium-10, a radioactive isotope of Be that is produced in the atmosphere by cosmic rays and is deposited onto the snow within 1-2 years of its production. The 10Be flux is largely independent of climate signals since its production varies with solar activity and the geomagnetic field. This project will further strengthen collaborations between the PI's in Berkeley and Purdue with ice core researchers in the US and Europe, involve undergraduate students in many aspects of its research, and continue outreach to under-represented students. The direct ice-to-ice synchronization of the WAIS Divide ice core with the Greenland Ice Core Chronology (GICC05) using cosmogenic 10Be is expected to reduce the uncertainty in the relative timing of more than 20 abrupt climate events in Greenland and Antarctica to a few decades. To achieve this goal the investigators will obtain a continuous high-resolution record of 10Be in the WAIS Divide core from 2850 to 3390 m depth, and compare the obtained 10Be record with existing 10Be records of the Greenland ice cores, including GISP2 and NGRIP. The scientists will separate 10Be from ~1000 ice samples of the WAIS Divide core and measure the 10Be concentration in each sample using accelerator mass spectrometry (AMS). Broader impacts of the 10Be measurements are that they will also provide information on the Laschamp event, a ~2000 year long period of low geomagnetic field strength around 41,000 years ago, and improve the calibration of the 14C dating method for organic samples older than 30,000 years. The broader impacts of the project include (1) the involvement and training of undergraduate students in ice core research and accelerator mass spectrometry measurements, (2) the incorporation of ice core and climate research into ongoing outreach programs at Purdue University and Berkeley SSL, (3) better understanding of abrupt climate changes in the past will improve our ability to predict future climate change, (4) evaluating the possible threat of a future geomagnetic excursion in the next few hundred years. This award does not require support in Antarctica.