Sedimentary Records of Past Marine Environments

过去海洋环境的沉积记录

• 批准号: 418518-2012
• 负责人: Kienast, Stephanie
• 金额: $ 2.04万
• 依托单位: Dalhousie University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2013
• 资助国家: 加拿大
• 起止时间: 2013-01-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=531220
• 关键词: Sedimentary; Records; Past; Marine; Environments

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.

海洋沉积物是宝贵的气候档案，记录了多种类型的环境信息，可用于增进我们对海洋-大气系统的了解。然而，目前许多研究认为大部分沉积物仅作为信息提供者的载体，例如浮游生物的化石遗骸。这种忽视大量沉积物及其尺寸特征的方法导致：a）某些地区海洋沉积记录的解释含糊不清；b）有关海底沉积环境的有价值信息的丢失。在本提案中，我们通过研究现有沉积物岩心的粒度组成来解决这个问题。我们的方法基于尺寸在 10-63 微米之间的颗粒（淤泥）的已知行为，这些颗粒根据底部电流速度进行尺寸排序。在赤道东太平洋，目前对沉积记录的解释存在争议，颗粒尺寸分析将与地球化学测量相结合，以准确量化气候相关物质（例如碳酸盐、有机物）从海面到海底的通量。这将使我们能够确定底部水流引起的横向沉积物运动是否使该地区先前的解释产生偏差。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-间冰期等时间尺度上的全球气候变化中所发挥的作用至关重要。言归正传，在斯科舍大陆架上，我们正在使用相同的方法来实现不同的目标。在这里，风暴被认为会使海床上的沙粒重新悬浮，并将它们重新沉积到其他地方的特征床中。通过分析战略位置地点的核心颗粒尺寸组成，我们将生成过去 10,000 年的暴风雨记录。该记录将显着扩展仪器记录，并有助于改善对未来风暴的预测。由于预计风暴将对大西洋沿岸的人民和基础设施产生越来越大的影响，这项研究将为加拿大带来直接利益。