Marine Climates of the U.S. Alaskan Coastal Plain During the Late Neogene and Quaternary Interglacials

摘要 该奖项支持一个项目，比较现代海洋气候与白令海峡地区最后一次间冰期的气候。 该项目的两个主要目标是：（1）详细记录现代和末次间冰期软体动物壳的稳定同位素组成所记录的季节温度范围，（2）从稳定同位素数据推断每个时间段内主要水团的分布。 在该项目的第一阶段，将应用稳定同位素方法评价白令海-楚科奇海区域的现代水文地理。 对大陆架介形类和软体动物进行稳定的氧和碳同位素分析，可以量化水团分布和纬度温度梯度的区域差异。 软体动物的同位素分布将提供温度季节变化的记录，并可能有助于区分季节性无冰和有冰的条件。 在现代系统中进行的这一校准实验将验证贝壳碳酸盐和海水的同位素组成之间的关系，并确定主要水团的地球化学特征。 在第二阶段，现代系统的结果将用于评估末次间冰期高峰期的条件。 将对从Pelukian海侵的新兴海岸平原沉积物中收集的化石软体动物和介形类进行稳定同位素分析。 采集点横跨从圣劳伦斯岛到巴罗点附近的骷髅崖的相对较宽的纬度范围;采集点的这种分布沿沿着南北温度梯度对不同的水团和点进行采样。 从垂直露头剖面以不连续的间隔采集的介形虫标本将提供海侵单元内同位素组成变化的记录。 温度范围和水团变化可以解释从软体动物的同位素剖面作为补充介形虫数据，以量化海洋古气候的季节性成分。 该项目的基本科学目标是调查控制热量通过白令海峡平流进入北冰洋的物理过程，并确定这些过程在间冰期之间是否有很大变化。

Abstract This award supports a project to compare the modern marine climate with that of the last interglacial episode in the Bering Strait region. The two primary goals of the project are to: (1) produce detailed records of seasonal temperature ranges as recorded in the stable isotopic composition of mollusk shells for the modern and the last interglacial, and (2) infer from the stable isotope data the distribution of the major water masses during each time slice. In the first phase of the project, stable isotope methods will be applied to an evaluation of the modern hydrography of the Bering Sea - Chukchi Sea region. Stable oxygen and carbon isotope analyses of ostracodes and mollusks from the shelf will allow quantification of regional differences in water-mass distribution and latitudinal temperature gradients. Isotope profiles of the mollusks will provide a record of the seasonal range of temperature and might be useful in distinguishing seasonally ice- free from ice-covered conditions. This calibration experiment in the modern system will verify the relationship between the isotopic composition of shell carbonate and seawater and identify the geochemical signature of the principal water masses. In the second phase, the results from the modern system will be used to evaluate conditions during the highstand of the last interglacial. Stable isotope analyses will be performed on fossil mollusks and ostracodes collected from the emergent coastal plain deposits of the Pelukian transgression. Collection sites span a relatively broad latitudinal range from St. Lawrence Island to Skull Cliff near Point Barrow; this distribution of sites samples different water masses and points along the north- south temperature gradient. Ostracode specimens collected at discrete intervals from vertical outcrop sections will provide a record of isotopic composition changes within the transgressive units. Temperature ranges and water-mass variations can be interpreted from isotope profiles of mollusks as a complement to the ostracode data to quantify the seasonal components of marine paleoclimate. The underlying scientific goal of the project is to investigate the physical processes which control the advection of heat into the Arctic Ocean through the Bering Strait, and to determine whether these processes have varied significantly between interglacial episodes.