Nature of Late Pleistocene Climatic Ameliorations in Eastern Beringia

这是一项与科罗拉多大学、阿拉斯加大学和沙漠研究所的主要研究人员合作的提案。西伯利亚、阿拉斯加和加拿大西北部的大部分地区在更新世晚期形成了一块未被冰川覆盖的陆地，被称为白令陆桥。以前的白令陆桥古气候研究只得出了定性的温度估计。有必要进行定量估计，以便更好地了解气候变化的幅度和区域表现。首席研究员将尝试通过使用热释光（TL）测年技术对昆虫化石、花粉和植物大化石进行分析，来量化古温度。他们将使用化石甲虫分析和古植物学研究的共同气候范围（MCR）方法来估计最暖月（TMAX）和最冷月（TMIN）的平均温度，以及估计年平均温度（MAT）。他们将在阿拉斯加中部和北部的五个研究地点重建过去的环境，沉积物的年龄范围从同位素阶段6结束到全新世。首席调查员将把重点放在最后一次间冰期之前和期间的样本上。他们将通过TL及其更新的变体——光子激发发光法测定沉积物14 -5万年的年代。将讨论两个研究主题。第一个主题是研究第六阶段到第五阶段的气候转变的本质，并确定老乌鸦的火种在这个序列中的位置。第二个研究主题是确定末次间冰期白令陆桥气候改善的性质。

OPP-99-19048EliasOPP-00-02362Edwards OPP-00-02361BergerThis is a collaborative proposal with Principal Investigators from the Universities of Colorado, Alaska, and the Desert Research Institute. Large portions of Siberia, Alaska, and northwestern Canada formed an unglaciated land-mass during the late Pleistocene known as Beringia. Previous Beringian paleoclimatic studies have yielded only qualitative temperature estimates. There is a need to develop quantitative estimates to gain a better understanding of the magnitude and regional expression of climate change. The Principal Investigators will attempt to quantify the paleotemperatures through the analysis of fossil insects, pollen, and plant macrofossils using thermoluminescence (TL) dating. They will use the Mutual Climatic Range (MCR) method of fossil beetle analysis and paleobotanical studies to produce estimates of mean temperatures of the warmest (TMAX) and coldest months (TMIN), as well as estimates of mean annual temperature (MAT). They will reconstruct past environments at the five study sites in central and northern Alaska with sediments ranging in age from the end of isotope stage 6 to the Holocene. The Principal Investigators will focus on samples from just before and during the last interglacial interval. They will date sediments from 140-50 thousand years by TL and its newer variant, photon-stimulated-luminescence. Two research themes will be addressed. The first theme is to study the nature of the climatic transition of stage 6 to stage 5 and to determine where the Old Crow tephra fits in this sequence. The second research theme is to determine the nature of climatic amelioration in Beringia during the last interglacial period.