REU: The Stratigraphy of Late Pleistocene Amazon Fan Sediments

REU：晚更新世亚马逊扇沉积物的地层学

• 批准号: 8817637
• 负责人: William Showers
• 金额: $ 5.22万
• 依托单位: North Carolina State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-03-01 至 1991-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8817637&HistoricalAwards=false
• 关键词: REU; Stratigraphy; Late; Pleistocene; Amazon

The Amazon Deep-Sea Fan is a typical large modern deep-sea fan. Past studies have documented the structure and surface morphology of the fan, including the location and character of the most recently active channel which crosses the fan. Cores collected in the vicinity of this channel sample the sediments deposited by channelized flows before activity ceased following post-glacial sea level rise. We propose here (1) to use morphological and sedimentological data to determine the likely characteristics of channelized turbidity currents and (2) to develop a stratigraphy which will allow us to determine the age of sedimentary activity on the fan. The stratigraphy will be based on delta 0-18 curves supplemented with AMS C-14 dates. New techniques developed at NCSU can measure 0-18 on samples containing few foraminifera, an advantage in cores with high sedimentation rates. AMS C-14 dates on the biogenic carbonates and pollen analysis will help to constrain the stratigraphic dates. Benchmark isotope stratigraphies, developed in the middle and lower fan areas where downslope flows are minimal, will applied to the most recently active channel/levee areas where downslope flows are more common. Such a stratigraphy will allow us to determine the ages associated with depositional events such as the cessation of flow down abandoned channels and the emplacement of major debris flows. We can then determime rates for fan processes and tie depositional patterns to sea level. The high-resolution 0-18 stratigraphy will also be valuable for assessing the late glacial/early interglacial role of the amazon River in determining paleoclimate and paleoceanograhic changes.

亚马逊深海扇是典型的大型现代深海扇。 过去的研究记录了扇体的结构和表面形态，包括穿过扇体的最近活跃通道的位置和特征。 在冰河后海平面上升后活动停止之前，在该河道附近收集的岩心对河道流沉积的沉积物进行了采样。 我们在此建议（1）使用形态学和沉积学数据来确定渠道化浊流的可能特征；（2）开发地层学，使我们能够确定扇上沉积活动的年龄。 地层学将基于 delta 0-18 曲线并辅以 AMS C-14 日期。 北卡罗来纳州立大学开发的新技术可以对含有少量有孔虫的样品进行 0-18 的测量，这对于具有高沉降速率的岩心来说是一个优势。 AMS C-14 生物碳酸盐年代和花粉分析将有助于限制地层年代。 在下坡流最少的中下扇区开发的基准同位素地层将应用于下坡流较常见的最近活跃的河道/堤坝区域。这样的地层学将使我们能够确定与沉积事件相关的年龄，例如废弃河道的流动停止和主要泥石流的就位。 然后我们可以确定扇过程的速率并将沉积模式与海平面联系起来。 高分辨率 0-18 地层学对于评估亚马逊河在确定古气候和古海洋变化方面的晚冰期/早间冰期作用也很有价值。