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An investigation of the role of framework geology on modern barrier island transgression

机译：框架地质学在现代屏障岛侵害中的作用研究

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摘要

The framework geology controls on modern barrier island transgression and the relationship of these controls to subsurface structure, hydrology, and island geomorphology are not well understood. Recent evidence suggests that alongshore variations in pre-Holocene geology of barrier islands modify nearshore hydrodynamic processes and sediment transport, ultimately affecting how barrier islands will respond to storms and relative sea-level rise. Explorations of Holocene barrier island geology are usually based on cores to supplement bathymetric, onshore/offshore seismic and/or ground-penetrating radar (GPR) surveys. Alternative near-surface geophysical methods including electromagnetic induction (EMI) sensors are increasingly being used for coastal research because they are non-invasive, provide continuous subsurface information across a variety of sub-environments, are capable of characterizing large areas in a short time, and are considerably more cost effective than the abovementioned techniques. This dissertation demonstrates the utility of using EMI methods for mapping large-scale (10.;1 -- 10.;2 km) barrier island framework geologyat Padre Island National Seashore (PAIS), Texas, USA. Instrument calibrations and tidal experiments suggest that although hydrology influences EMI signals along the beach, the effect of changing hydrology is not statistically significant over large spatial scales. For the first time, this study shows the importance of statistically modeling EMI spatial data and digital elevation model (DEM) extracted morphometrics to examine the statistical relationships (or lack thereof) between framework geology and geomorphology. A family of fractional autoregressive integrated moving average ARIMA (p,d,q) models demonstrate each spatial data series is most accurately modeled by a single parameter, d, indicating a strong tendency towards long-range dependence (LRD) that suggests self-similarity. Dune height and EMI ?a have nearly identical d-values (∼ 0.35), which suggests a statistically significant connection between framework geology and dune height at a global scale (100 km). Variations in d at both regional (∼30 km) and local (10 km) scales differ by varying degrees, providing further evidence that framework geology controls are more important at the largest spatial scales. By integrating EMI and DEM morphometrics with multivariate analysis and ARIMA modeling, this study offers a robust and novel way for accurately quantifying the entire geological complexity of a barrier island using only three parameters (p,d,q). Moreover, this study shows that EMI sensors are complementary to and offer significant advantages over traditional methods in support of an improved understanding of large-scale barrier island transgression.
机译：对于现代屏障岛侵害的框架地质控制以及这些控制与地下结构，水文和岛屿地貌的关系尚不十分了解。最新证据表明，障碍岛全新世前地质的近岸变化改变了近岸水动力过程和沉积物的输送，最终影响了障碍岛对风暴和相对海平面上升的反应。全新世隔离岛地质勘探通常以岩心为基础，以补充测深，陆上/近海地震和/或探地雷达（GPR）调查。包括电磁感应（EMI）传感器在内的替代近地表地球物理方法正越来越多地用于沿海研究，因为它们是非侵入性的，可在各种子环境中提供连续的地下信息，并能够在短时间内表征大面积区域，并且比上述技术更具成本效益。本文证明了使用EMI方法绘制美国得克萨斯州帕德里岛国家海岸（PAIS）的大规模（10.; 1-10.; 2 km）屏障岛框架地质图的实用性。仪器校准和潮汐实验表明，尽管水文学会影响海滩上的EMI信号，但在较大的空间尺度上，水文学变化的影响在统计学上并不显着。此项研究首次显示了对EMI空间数据和数字高程模型（DEM）提取的形态计量学进行统计建模以检查框架地质与地貌之间的统计关系（或缺乏统计关系）的重要性。分数阶自回归积分移动平均ARIMA（p，d，q）模型系列表明，每个空间数据系列均由单个参数d最精确地建模，表明存在很强的长期依赖（LRD）趋势，这表明自相似性。沙丘高度和EMIαa具有几乎相同的d值（约0.35），这表明在全球范围内（100 km）框架地质与沙丘高度之间存在统计学上的显着联系。 d（区域（〜30 km）和局部（10 km））的变化程度不同，这提供了进一步的证据，表明在最大的空间尺度上，框架地质控制更为重要。通过将EMI和DEM形态计量学与多变量分析和ARIMA建模相集成，这项研究提供了仅使用三个参数（p，d，q）准确量化障碍岛的整个地质复杂性的可靠而新颖的方法。此外，这项研究表明，EMI传感器是对传统方法的补充，并提供了优于传统方法的显着优势，以支持对大规模障碍岛越界的更好理解。

著录项

  • 作者

    Weymer, Bradley Allen.;

  • 作者单位

    Texas A&M University.;

  • 授予单位 Texas A&M University.;
  • 学科 Geology.;Geophysics.;Statistics.
  • 学位 Ph.D.
  • 年度 2016
  • 页码 202 p.
  • 总页数 202
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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