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

该项目将考察美国大西洋沿岸三个更新世中晚期间冰期的海洋气候。该项目将有两个主要目标：1)在间冰期为弗吉尼亚和南卡罗来纳海岸提供季节温度范围的详细记录；2)利用锶同位素地层学可能改善这些海侵事件的年代学。根据软体动物化石壳的稳定氧(O)和碳(C)同位素剖面计算季节古温度差。将测量贝壳生长增量，以确定截断同位素剖面的贝壳生长停止期。生长增量数据还将用于评估一个独立的古温度表，该温度表基于个体生长趋势的地理变化。更新世海侵进入大西洋沿岸平原的时间是对氨基酸外消旋作用和铀系定年方法的各种解释进行积极辩论的主题。拟议项目中包括的锶同位素分析应提供一套独立的数据，以解决这些单元的地质年代学问题。所有的地球化学分析都将在氨基酸消旋化分析的同一标本上进行，因此气候和地质年代学信息将直接比较。

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.