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

新近纪晚期和第四纪间冰期美国阿拉斯加沿海平原的海洋气候

• 批准号: 9423663
• 负责人: David Krantz
• 金额: $ 4.24万
• 依托单位: University of Delaware
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-08-01 至 1997-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9423663&HistoricalAwards=false
• 关键词: Marine; Climates; U.S.; Alaskan; Coastal

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.

该奖项支持一项将白令海峡地区现代海洋气候与上一次间冰期气候进行比较的项目。该项目的两个主要目标是：(1)制作现代和末次间冰期软体动物贝壳稳定同位素组成中记录的季节温度范围的详细记录，以及(2)从稳定同位素数据推断主要水团在每个时间段的分布。在该项目的第一阶段，将应用稳定同位素方法对白令海-楚科奇海地区的现代水文学进行评估。对大陆架上的介形类和软体动物进行稳定的氧和碳同位素分析，将能够量化水团分布和纬度温度梯度的区域差异。软体动物的同位素图谱将提供温度季节范围的记录，可能有助于区分季节性无冰和有冰的条件。这项现代系统的标定实验将验证贝壳碳酸盐与海水的同位素组成之间的关系，并识别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。将对从鹈鹕海侵的新出现的沿海平原沉积中收集的软体动物和介形虫化石进行稳定同位素分析。采集点横跨相对较宽的纬度范围，从圣劳伦斯岛到巴罗角附近的骷髅悬崖；这些采集点的分布沿着南北温度梯度对不同的水团和点进行采样。从垂直露头剖面以离散间隔收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。从软体动物的同位素分布可以解释温度范围和水量变化，作为介形虫数据的补充，以量化海洋古气候的季节成分。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显著差异。