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首页> 外文学位 >Late Holocene evolution of Currituck sound, North Carolina, USA: Environmental change driven by sea-level rise, storms and barrier island morphology.
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Late Holocene evolution of Currituck sound, North Carolina, USA: Environmental change driven by sea-level rise, storms and barrier island morphology.

机译：美国北卡罗来纳州Currituck声音的全新世晚期演化：环境变化是由海平面上升，风暴和屏障岛形态驱动的。

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摘要

Coastal evolution is an increasingly important area of study, especially with the projected rise in sea level, increase in storm intensity, and population increases along the nation's coasts. In order to predict how the coastal environment will respond to these changes in the future, we need to first understand the evolution of coastal systems in the past. Here I address the late Holocene evolution of Currituck Sound, North Carolina, by examining time periods with different barrier island and inlet configurations interpreted from core data.;Chirp seismic data and 13 vibracores have been used to interpret the Holocene development of this region. Four depositional units have been defined, based on lithofacies, biofacies, geophysical, and geochronologic data. The lowermost depositional unit (Unit I) is represented by quartz sand, barren of foraminifera, and is Pleistocene in age based on an OSL age estimate of 33.7 ka. Unit II consists of slightly muddy sand that fines upward to slightly sandy mud; it is barren of foraminifera, contains rooted horizons in several cores, and is interpreted as a fresh water swamp forest deposit (radiocarbon dating provide age estimates of ca. 4000 to 2800 cal y BP). Unit III is characterized by slightly sandy mud to mud containing a calcareous foraminiferal assemblage and oyster bioherms; these characteristics indicate a back-barrier estuarine environment with high salinity (ca. 25 to 35) due to open inlets in the barrier islands to the east. Radiocarbon age estimates for Unit IV range from ca. 1700 to 500 cal y BP. The topmost unit (Unit IV) is composed of sediment with variable composition, ranging from clean quartz sand to mud, and contains foraminiferal assemblages that are generally mixed calcareous/agglutinated at the base overlain by entirely agglutinated assemblages. This unit represents the modern (post- ca. 1827), mid- to low salinity (less than 10), back-barrier lagoon with no inlets open in the barrier island.;Sediment and microfossil-based paleoenvironmental and geomorphic reconstructions, including variable numbers of inlets, have been used as input into the Delft3D hydrodynamic model to understand inlet related changes to tides and currents within the Sound. This modeling indicates that impacts of inlets are very localized and only inlets in the direct vicinity of Currituck Sound (i.e., between historic Caffey's Inlet and Kill Devil Hills) have a significant impact on the water levels and currents in the study area.
机译：沿海演变是一个日益重要的研究领域，尤其是随着预计的海平面上升，风暴强度增加以及全国沿海人口增加的情况。为了预测未来沿海环境将如何应对这些变化，我们需要首先了解过去沿海系统的演变。在这里，我通过检查具有不同屏障岛和入口构造的时间段来解决北卡罗来纳州Currituck Sound的全新世演化的晚期问题;;线性地震数据和13个振子被用来解释该地区的全新世发展。根据岩相，生物相，地球物理和年代学数据，已经定义了四个沉积单元。最低的沉积单元（单元I）由有孔虫的贫瘠的石英砂代表，根据OSL年龄估计为33.7 ka，该年龄为更新世。第二单元由略微浑浊的沙子组成，向上细化为稍呈细沙状的泥土。它是有孔虫的贫瘠之地，在数个核心处都有生根的地层，被解释为淡水沼泽森林沉积物（放射性碳年代测定的年龄估计约为BP 4000至2800 cal）。第三单元的特征是泥土略带沙质，含有钙质有孔虫组合和牡蛎生物体。这些特征表明，由于东部屏障岛开放的入口，盐度较高（约25至35）的后屏障河口环境。第四单元的放射性碳年龄估计范围约为1700至500 cal y BP。最上层的单元（单元IV）由沉积物组成，其组成从清洁的石英砂到泥浆不等，并且包含有孔虫组合，这些组合物通常在钙质/凝结的基础上被钙质/凝结物完全凝集地混合在一起。该单元代表了现代（约1827年后），中低盐度（小于10），后屏障礁湖，屏障岛上没有任何入口。；基于沉积物和微化石的古环境和地貌重建，包括可变的数量的入口已被用作Delft3D流体动力学模型的输入，以了解与Sound相关的潮汐和水流相关入口变化。该模型表明，进水口的影响非常局限，只有在Currituck Sound附近的进水口（即在历史悠久的Caffey入口和Kill Devil Hills之间）对研究区域的水位和水流有重大影响。

著录项

  • 作者

    Moran, Kelli.;

  • 作者单位

    East Carolina University.;

  • 授予单位 East Carolina University.;
  • 学科 Geology.;Environmental Sciences.
  • 学位 M.S.
  • 年度 2012
  • 页码 102 p.
  • 总页数 102
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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