Evolution of Sea Surface Temperatures in the Coastal Antarctic Paleoenvironment During the Late Cretaceous and Paleogene

该奖项由极地方案办公室南极地质和地球物理方案提供，支持建立白垩纪晚期和古近纪早期气候的长期记录的研究，以评估南极沿海边缘地区的年度季节性温度。在西摩岛收集的保存完好的双壳类贝壳的稳定同位素和元素组成将成为用于重建古环境条件的主要数据来源。通过沿双壳贝壳生长结构的高分辨率采样收集的季节性温度记录将使人们能够在不同气候状态和快速气候变化期间评估季节性。此外，高地层学分辨率将使该项目能够探测到可能延伸到如此高纬度的短暂热漂移的存在和频率。为了汇编可靠的古气候时间记录，将开展两个主要研究途径：1)通过使用几何投影的图形技术，在大片地理区域内精确地放置化石(因此，将在时间上)放置化石；2)将进行稳定同位素和元素分析，以得出古温度，并评估壳体物质的成岩蚀变。为了提供地层层间古温度的真实比较，这项研究将专注于单一的分类群，从而避免由于该地区先前研究中遇到的动物群组合混合而造成的复杂情况。西摩岛的近岸海洋化石记录为解决许多关于南极古环境的问题提供了独特的机会，包括季节性与不同气候状态的关系，气候对特定类群生物地理分布的影响，从晚白垩世到始新世冰量变化对稳定同位素记录的影响，以及这段时间内高纬度底水形成的可能性。特别是，将收集的关于季节性模式和是否存在短期热漂移的信息，对于了解高纬度地区在气候从全球凉爽向全球温暖条件转变期间的反应将非常有价值。

This award, provided by the Antarctic Geology and Geophysics Program of the Office of Polar Programs, supports research for construction of a long-term record of climate during the late Cretaceous and early Paleogene to assess the annual seasonality in temperature on the coastal margin of Antarctica. Stable isotope and element compositions of well-preserved bivalve shells collected on Seymour Island will be the primary source of data used to reconstruct paleoenvironmental conditions. Seasonal temperature records collected through high-resolution sampling along growth structures in bivalve shells will allow seasonality to be assessed during different climate states and during periods of rapid climate change. In addition, high stratigraphic resolution will enable this project to detect the presence and frequency of short-lived thermal excursions that may have extended to such high latitudes.To compile a reliable temporal record of paleoclimate, two major avenues of investigation will be undertaken: 1) precise stratigraphic (and therefore, temporal) placement of fossils over a large geographic area will be employed through the use of a graphical technique employing geometric projections; 2) stable isotope and elemental analyses will be performed to derive paleotemperatures and to evaluate diagenetic alteration of shell materials. To provide realistic comparisons of paleotemperatures across stratigraphic horizons, this study will focus on a single taxon, thus avoiding complications due to the mixing of faunal assemblages that have been encountered in previous studies of this region.The near-shore marine fossil record on Seymour Island provides a unique opportunity to address many questions about the Antarctic paleoenvironment, including the relation between seasonality and different climate states, the influence of climate on biogeographic distribution of specific taxa, the effect of ice-volume changes on the stable isotope record from the late Cretaceous through the Eocene, and the plausibility of high-latitude bottom water formation during this time interval. In particular, information that will be collected concerning patterns of seasonality and the presence (or absence) of short-lived thermal excursions will be extremely valuable to an understanding of the response of high latitude sites during climate transitions from globally cool to globally warm conditions.