Sedimentary Records of Past Marine Environments

海洋沉积物是宝贵的气候档案，记录了各种类型的环境信息，可用于增进我们对海洋-大气系统的了解。然而，目前的许多研究认为，大部分沉积物只是作为载体的信息提供者，如浮游生物的化石遗骸。这种忽视大量沉积物及其大小特征的做法导致a）在解释某些地区的海洋沉积记录方面存在模糊性，以及B）丢失了有关海底沉积环境的宝贵信息。在这个建议中，我们解决这个问题，通过调查现有的沉积物芯的粒度组成。我们的方法是基于10-63微米大小的颗粒（淤泥），这是根据底流速度大小排序的已知行为。在赤道东太平洋，目前对沉积记录的解释存在争议，将把粒度分析与地球化学测量结合起来，以准确地量化从海面到海底的气候相关物质（如碳酸盐、有机物）的通量。这将使我们能够确定底流的横向沉积物运动是否使以前在该地区的解释有偏差。关于赤道太平洋过去行为的可靠数据对于更好地了解太平洋在从年际（即厄尔尼诺）到冰期-间冰期的全球气候变化中所起的作用至关重要。在离家更近的地方，在斯科舍大陆架上，我们正在使用同样的方法，但目标不同。在这里，风暴被认为是从海床上重新悬浮沙粒，并将它们重新沉积在其他地方的特征床中。通过分析战略位置的核心颗粒组成，我们将产生过去10，000年的风暴记录。这一记录将大大扩展仪器记录，并有助于改善未来风暴的预测。由于风暴预计将对大西洋沿岸沿着的人民和基础设施产生越来越大的影响，这项研究将直接使加拿大受益。

Marine sediments are valuable climate archives and record diverse types of environmental information, which is used to improve our understanding of the ocean-atmosphere system. However, many current studies consider the bulk of the sediment only as the carrier for the information provider, such as fossil remains of plankton. This approach of ignoring the bulk sediment and its size characteristics has led to a) ambiguity in the interpretation of the marine sedimentary record in some areas and b) a loss of valuable information about the depositional environment on the sea floor. In this proposal, we address this issue by investigating the grain size composition of existing sediment cores. Our approach is based on the known behaviour of particles between 10-63 micrometer in size (silts), which are size-sorted according to bottom current speed. In the eastern equatorial Pacific, an area where current interpretations of the sedimentary record are controversial, grain size analyses will be combined with geochemical measurements to accurately quantify the flux of climate relevant material (e.g. carbonate, organic matter) from the sea surface to the sea floor. This will enable us to determine whether or not lateral sediment movement by bottom currents has biased previous interpretations in this region. Reliable data on the past behaviour of the equatorial Pacific are crucially important for a better understanding of the role that the Pacific plays in global climate change on time-scales ranging from interannual (i.e. El-Niño) to glacial-interglacial. Closer to home, on the Scotian Shelf, we are using the same approach with a different goal. Here, storms are thought to resuspend sand grains from the sea bed and redeposit them in characteristic beds elsewhere. By analysing the down core grain size composition of strategically located sites, we will generate a record of storminess over the last 10,000 years. This record will significantly extend the instrumental record and contribute to improving projections of storms in the future. As storms are expected to have an ever increasing impact on people and infrastructure along the Atlantic coast, this research will be of direct benefit to Canada.