Pleistocene Interglacial Marine Climates, U.S. Mid-Atlantic and Southeastern Coastal Plains

该项目将研究美国大西洋沿岸三个中、晚更新世间冰期的海洋气候。该项目将有两个主要目标：1)制作弗吉尼亚州和南卡罗来纳州海岸在这些间冰期的季节性温度范围的详细记录，以及2)利用锶同位素地层学潜在地改进这些海侵事件的年代学。季节性古温度范围将根据软体动物化石贝壳的稳定氧(O)和碳(C)同位素剖面计算出来。将测量壳层生长增量，以确定截断同位素剖面的壳层生长停止时期。生长增量数据还将用于根据个体发育生长趋势的地理变化来评估独立的古温度计。更新世侵入大西洋海岸平原的时间是关于氨基酸外消旋和铀系列测年方法的各种解释的激烈辩论的主题。拟议项目中包括的锶同位素分析应提供一套独立的数据，说明这些单位的地质年代学。所有的地球化学分析都将在对氨基酸消旋进行分析的同一标本上进行，这样气候和地质年代学信息就可以直接进行比较。

The project will examine the marine climate along the Atlantic Coast of the U.S. during three middle and late Pleistocene interglacial periods. The project will have two main goals: 1) produce detailed records of seasonal temperature ranges for the Virginia and South Carolina coasts during these interglacial periods, and 2) potentially improve the chronology of these transgressive events using strontium-isotope stratigraphy. The seasonal paleotemperature ranges will be calculated from the stable oxygen ( O) and carbon ( C) isotope profiles of fossil mollusk shells. Shell growth increments will be measured to identify periods of cessation of shell growth that truncate the isotope profiles. The growth increment data will also be used to assess an independent paleothermometer based on the geographic variation in ontogenetic growth trends. The timing of the Pleistocene transgressions onto the Atlantic Coastal Plain is the subject of an active debate over various interpretations of amino acid racemization and uranium-series dating methods. The strontium isotope analyses included in the proposed project should provide an independent set of data that addresses the geochronology of these units. All geochemical analyses will be performed on the same specimens that have been analyzed for amino acid racemization, so that the climatic and geochronologic information will be directly comparable.