ESH: Magnetic Studies of Lake Sediments: Climate Variability in Alaska During the Last 14,000 Years

9809150 Banerjee该项目的主要目标是提供新的，高时间分辨率的数据，在过去14,000年中，在阿拉斯加的地方和区域气候变化的反应。为此，在阿拉斯加西南部（祖父，Ongivinuk）和碎屑输入的两个湖序列将通过岩石磁性，岩石磁性，化学和粒度方法进行分析。 高灵敏度的磁信号也将与我们现有的（和部分出版）花粉和沉积记录从相同的网站。 由于这种跨学科的方法的质量和复杂性的平均晚更新世和全新世气候记录的阿拉斯加，现在主要是基于花粉数据，将得到验证和纠正。 在该项目的最后阶段，这一改进的记录将与北大西洋和格陵兰岛类似高纬度地区的气候记录进行比较。初步研究表明，在晚冰期-全新世过渡期间，全新世开始和7500年前的茂盛植被的到来期间的短暂热波动都可以在目标湖泊沉积物的某些磁性中看到。 这表明磁信号准确地反映了环境变化。 通过使用额外的磁性代理，原位氧化和还原过程可以从碎屑信号中分离出来，磁性晶粒尺寸也可以估计。 通过化学元素分析、非磁性粒度测定和穆斯堡尔谱来验证这些代理，并将这些代理与现有的植被数据进行比较，将使我们能够重建过去14,000年的高分辨率气候记录。

9809150BanerjeeThe primary objective of the project is to provide new, high temporal resolution data on local and regional responses to climate change in Alaska during the last 14,000 years.For this purpose two lacustrine sequences in southwest Alaska (Grandfather, Ongivinuk) and detrital input will be analyzed by rock magnetic by rock magnetic, chemical and granulometric methods. The high-sensitivity magnetic signal will also be compared with our existent (and partly published) pollen and sedimentological records from the same sites. Due to this interdisciplinary approach the quality and complexity of the average Late Pleistocene and Holocene climate record of Alaska, now dominantly based on pollen data, will be validated and corrected. In the last stage of this project, this improved record will be compared with the climate records at similar high latitudes in the North Atlantic and Greenland.Preliminary studies show that short thermal fluctuations during the Late Glacial-Holocene transition, the beginning of the Holocene and the arrival of a lusher vegetation 7500 years BP are all visible in some of the magnetic properties of the target lake sediments. This indicates that the magnetic signal accurately reflects environmental changes. By using additional magnetic proxies, in situ oxidation and reduction processes can be separated from the detrital signal, and magnetic grain size can also be estimated. Validating these proxies by chemical elemental analysis, non-magnetic grain size determinations, and Mossbauer spectra and comparing these proxies with the existing vegetational data, will allow us to reconstruct a high-resolution climate record over the last 14,000 years.