Comparative Ichnological Studies of Tertiary Depositional Sequences, Alabama Coastal Plain

阿拉巴马沿海平原第三纪沉积层序的比较地学研究

• 批准号: 9004923
• 负责人: Charles Savrda
• 金额: $ 8万
• 依托单位: Auburn University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1990
• 资助国家: 美国
• 起止时间: 1990-06-15 至 1993-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9004923&HistoricalAwards=false
• 关键词: Comparative; Ichnological; Studies; Tertiary; Depositional

Sequence stratigraphic studies of the Alabama Tertiary have resulted in the delineation of approximately twenty depositional sequences, which are interpreted to reflect distinct eustatic sea-level cycles of varying magnitude. The PI recently completed detailed studies of two of these sequences. Significant variations in degree of bioturbation, general ichnofabrics, and discrete trace fossils are observed within and between component systems tracts, and reflect changes in substrate consistency, physical environmental energy, sedimentation rate, and bottom- and/or pore-water chemistry that are consistent with both the phase and magnitude of the associated eustatic cycles. These results demonstrate the potential of extended trace fossil studies in the context of sequence stratigraphy. In order to more fully assess this potential, detailed studies of strata representative of all of the twenty depositional sequences delineated in the Alabama Tertiary are proposed. The objectives of these analyses are: 1) to further assess the response of trace-fossil assemblages to predicted sea- level-mediated paleoenvironmental changes; and 2) to evaluate the ichnological variability that exists between and within systems tracts as a function of differences in depositional environment, lithofacies, and phase and magnitude of associated eustatic cycles. This research will 1) provide an independent test of sequence stratigraphic concepts and interpreted sea-level histories, 2) establish an improved set of ichnological criteria that can be incorporated into models useful for recognizing the eustacy signal, and 3) improve our overall understanding of trace fossils as paleoenvironmental indicators.

亚拉巴马第三纪的层序地层学研究 结果描绘出了大约20个沉积物 层序，这些层序被解释为反映不同的海平面变化 海平面变化幅度的周期。 PI最近完成了 对其中两个序列的详细研究。 显著 生物扰动程度的变化，一般遗迹组构， 在组件内部和组件之间观察到离散的遗迹化石 体系域，并反映基质稠度的变化， 物理环境能量、沉积速率和底质- 和/或孔隙水化学性质， 相关的海平面升降周期的相位和幅度。 这些 结果表明，扩展的痕迹化石的潜力 层序地层学背景下的研究。 为了更全面地评估这一潜力， 对代表所有20个国家的 亚拉巴马第三纪的沉积层序是 提出了 这些分析的目的是：（1）进一步 评估遗迹化石组合对预测的海- 水平介导的古环境变化; 2）评价 存在于系统之间和系统内部的遗迹学变异 作为沉积环境差异的函数， 岩相、相关海平面变化的阶段和幅度 自行车. 这项研究将1）提供一个独立的测试， 层序地层学概念与解释海平面 2）建立一套改进的遗迹学标准 可以被纳入模型，用于识别 eustacy信号，以及3）提高我们对痕迹的整体理解 化石作为古环境指标。