Geomorphic Evolution and Heterogeneity of Holocene Carbonate Tidal Sand Shoals

全新世碳酸盐潮沙浅滩地貌演化和异质性研究堪萨斯大学吉恩·兰基地球表面变化的档案包含在地层记录中。 特别是卵状体（球形同心层状颗粒）的沉积物为数十亿年来海洋的物理和化学变化提供了关键的见解。 正在进行的研究表明，可变的基岩配置，潮汐和波浪如何导致不同的几何形状（潮汐三角洲，潮汐沙脊，抛物线酒吧，S形酒吧）在潮汐为主的今天活跃的鲕粒沙浅滩。 这项研究将扩大这些见解，探索假设，这些变量的过程赋予一个独特的和独特的地层记录，每个浅滩的几何形状。 为了解决这些问题和测试的假设，本研究将利用高分辨率的海底地球物理剖面，取芯，并从一套全新的巴哈马浅滩的年龄测定不同的过程和地貌的特点。 在比较的厚度，高程的基岩下浅滩，浅滩内的沉积趋势，这项研究的结果将导致这些鲕粒系统的演化，并在一般的潮汐砂浅滩的理解。 此外，精确的年代测定的鲕粒沉积物将揭示地貌变化的速度，信息难以确定的硅质岩系统。 总的来说，这些数据将提供关键的见解，以更好地约束对地球历史的解释，以响应全球变化，预测地下鲕粒沉积岩的分布和变化（例如，在水或碳氢化合物储层中），并了解从砂开采中可能的回收率。 该提案将资助在巴哈马伊柳塞拉岛岛屿学校为巴哈马和国际学生提供的几个学期的课程、动手实验室和实地经验。

Geomorphic Evolution and Heterogeneity of Holocene Carbonate Tidal Sand ShoalsGene Rankey, University of KansasThe archive of change on the Earth's surface is contained in its stratigraphic record. Deposits of ooids (spherical concentrically laminated grains) in particular have provided key insights into physical and chemical variability in the ocean over billions of years. On-going research has illustrated how variable bedrock configurations, tides and waves lead to different geometries (tidal deltas, tidal sand ridges, parabolic bars, sigmoidal bars) in tidally dominated oolitic sand shoals that are active today. This study will expand on those insights, exploring the hypothesis that these variable processes impart a distinct and unique stratigraphic record to each shoal geometry. To address these questions and test the hypothesis, this study will utilize high-resolution subbottom geophysical profiling, coring, and age dating from a suite of Holocene Bahamian shoals characterized by different processes and landforms. In comparing the thicknesses, the elevation of the bedrock beneath the shoals, and sedimentologic trends within the shoals, the results of this study will lead to enhanced understanding of evolution of these oolitic systems, and to tidal sand shoals in general. Furthermore, precise age dating of the oolitic sediments will reveal the rates of geomorphic change, information difficult to ascertain in siliciclastic systems. Collectively, these data will provide key insights to better constrain interpretation of the planet's history in response to global change, to predict the distribution and variability of oolitic sedimentary rocks in the subsurface (e.g., in water or hydrocarbon reservoirs), and to understand possible rates of recovery from sand mining. This proposal will fund development of mix of lecture, hands-on lab, and field experiences on ooid shoals for Bahamian and international students, offered by the PI and student for several semesters, at the Island School on Eleuthera Island in The Bahamas.