REU: The Stratigraphy of Late Pleistocene Amazon Fan Sediments

亚马逊深海风扇是典型的现代大型深海风扇。过去的研究记录了风扇的结构和表面形态，包括穿过风扇的最近活动通道的位置和特征。在这条海峡附近采集的岩心采样了在冰川后海平面上升后活动停止之前由沟道化水流沉积的沉积物。我们建议(1)利用形态和沉积学资料来确定槽化浊流的可能特征；(2)发展地层学，以确定扇上沉积活动的年龄。地层将以三角洲0-18曲线为基础，辅以AMS C-14测年。NCSU开发的新技术可以在含有很少有孔虫的样品上测量0-18，这在高沉积速率的岩心中是一个优势。对生物碳酸盐的AMS C-14测年和孢粉分析将有助于限制地层测年。基准同位素地层学是在下坡水流最少的中下扇地区开发的，将应用于下坡水流较常见的最近活跃的河道/堤防地区。这样的地层学将使我们能够确定与沉积事件有关的年龄，例如沿废弃河道的水流停止和主要泥石流的侵位。然后我们可以确定扇过程的最小速率，并将沉积模式与海平面联系起来。高分辨率0-18地层学也将对评估亚马逊河在确定古气候和古海洋地理变化中的晚冰期/早间冰期作用具有价值。

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.