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Comparative morphology and dynamics of Holocene carbonate systems, northwestern Abaco Islands, Bahamas.

机译:巴哈马西北阿巴科群岛的全新世碳酸盐岩系统的比较形态和动力学。

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摘要

Although the physical processes controlling siliciclastic shallow marine tidal sand bodies are reasonably well-understood, the role of these processes in shaping carbonate sand systems has not been systematically explored. To what extent are these processes important in shaping the geomorphology of such carbonate systems, in which sands can be "born, not made?" The tidal sand bodies of the northwestern Abaco Islands, Bahamas, provide a unique opportunity to explore these processes in a heterogeneous carbonate system.; Tropical cyclones commonly are cited as being influential, or even dominant, controls on the geomorphologic evolution of carbonate systems. An opportunity to explore the effects of storms on platform systems occurred when two strong tropical cyclones (Frances and Jeanne) passed directly over the shoals and reefs of the Abacos, northern Bahamas, in 2004. Observations of the influence of tropical cyclones coupled with hydrodynamic observations and wave models provide insights into the role of these types of events in carbonate platform geomorphic evolution. These results illustrate that these storms were neither sufficient to drive major change nor necessary to explain the geomorphic evolution of this tidally influenced system. Further observations of wind, wave, and tidal forces acting on this carbonate system indicate that these quotidian processes may be an important factor in controlling the geomorphology of the system. A conceptual morphologic model developed from observations and numerical modeling illustrates how feedbacks amongst bathymetry, hydrodynamics, and sedimentology lead to systematic trends in granulometry and geomorphic trends in the carbonate tidal deltas akin to their siliciclastic counterparts.; A closer look at the daily tidal forces effecting the oolitic sand bodies of the northwestern Abacos indicate that links between the tidal currents and bathymetry can set up a circular flow pattern, explaining the presence of the shoals and the oolitic grains creating them. Numerical modeling experiments indicate that flow restriction creating current jets and the presence of a sediment source are two necessary (but perhaps not sufficient) factors controlling the morphodynamics of oolitic tidal deltas.; The results of this study represent a first step in advancing carbonate facies models beyond qualitative concepts towards quantitative, specified environmental and sedimentologic characterizations.
机译:尽管控制硅质碎屑浅海潮汐砂体的物理过程已被很好地理解,但尚未系统地探讨这些过程在塑造碳酸盐砂岩系统中的作用。这些过程在何种程度上对塑造此类碳酸盐系统的地貌具有重要意义,而在这种碳酸盐系统中,沙子可能“生而无生”?巴哈马西北阿巴科群岛的潮汐砂体为在非均质碳酸盐体系中探索这些过程提供了独特的机会。热带气旋通常被认为是对碳酸盐系统地貌演化的影响,甚至占主导地位。 2004年,当两个强热带气旋(弗朗西斯和珍妮)直接越过巴哈马北部阿巴科斯的浅滩和礁石时,就有机会探索风暴对平台系统的影响。热带气旋的影响观测与流体动力学观测相结合波浪模型提供了洞悉这些类型事件在碳酸盐台地貌演化中的作用的见解。这些结果说明,这些风暴既不足以推动重大变化,也无必要解释受潮汐影响的系统的地貌演化。进一步观察到作用在该碳酸盐系统上的风,浪和潮汐力表明,这些quotidian过程可能是控制系统地貌的重要因素。从观测和数值模型发展而来的概念形态模型说明了测深法,水动力学和沉积学之间的反馈如何导致碳酸盐岩潮汐三角洲的粒度学和地貌趋势的系统性趋势,类似于硅质碎屑对应物。仔细研究影响阿巴科斯西北部的砂质岩体的每日潮汐力,可以发现潮汐流和测深仪之间的联系可以建立一个圆形的流动模式,从而解释了浅滩和形成它们的浅质颗粒的存在。数值模拟实验表明,形成流动射流的流量限制和沉积物源的存在是控制潮汐三角洲形态动力学的两个必要(但可能不足)的因素。这项研究的结果代表了将碳酸盐相模型从定性概念发展为定量,特定环境和沉积特征的第一步。

著录项

  • 作者

    Reeder, Stacy Lynn.;

  • 作者单位

    University of Miami.;

  • 授予单位 University of Miami.;
  • 学科 Geology.
  • 学位 Ph.D.
  • 年度 2007
  • 页码 144 p.
  • 总页数 144
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 地质学;
  • 关键词

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