COLLABORATIVE RESEARCH: Experimental Study of Basin Stratigraphy

合作研究：盆地地层学实验研究

• 批准号: 9725471
• 负责人: Lincoln Pratson
• 金额: --
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-05-01 至 1998-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9725471&HistoricalAwards=false
• 关键词: COLLABORATIVE; RESEARCH; Experimental; Study; Basin

9725471 Pratson We propose a three-year program of experimental studies o the formation of physical stratigraphy, using a large new experimental basin with a subsiding floor at the St. Anthony Falls Laboratory (SAFL). This facility allows study of scaled basin processes with complete control of base level, sediment supply and, especially, subsidence pattern and rate. The basin is 13m by 6.5m and allows up to 1.3m of accommodation space for deposition. The subsiding floor comprises 432 independently controllable subsidence cells arranged in a honeycomb pattern. This design allows the creation of a nearly unlimited range of spatial and temporal subsidence patterns. Sediment and water can be fed from anywhere along the basin margin and base level (i.e. water level) is independently controllable. Our first experiments will be aimed at testing some of the first-order predictions of models that have been proposed for formation of physical stratigraphy at basin scales, such as: (1) the relationship of shoreline migration and associated stratigraphy to the interplay between subsidence rate and eustatic sea level; (2) the control of subsidence rate and geometry, and sediment supply, on alluvial coarse-facies distribution (i.e. the origin of syntectonic gravel's); and (3) the influence of subsidence rate and sediment supply on the development of alluvial architecture. Initial results suggest that the experiments can also provide insight on processes such as growth faulting that have not been widely incorporated into existing models. These experiments will use relatively simple subsidence and sediment-feed geometries and will focus on demonstrating "unit" stratigraphic response to changes in one or at most two variables simultaneously. The second set of experiments will focus on 3-D effects in both subsidence and sediment supply, including: 1) 3-D effects of base-level change; 2) propagating active folding in the proximal basin associated with blind thrusts and development of progressive unconformities; 3) sedimentation in an asymmetric half graben combining both transverse and axial drainage. The principal products of the experiments will include: time records of the imposed variables (water and sediment supply, base level, and basement topography); measurements of bed-surface topography through time; video records of flow pattern, shoreline position and other surface features; 3-D block diagrams of the resulting deposits, presented both as directly digitized (photographic) and synthetic seismic images; and synthetic geophysical logs of selected profiles. The synthetic seismics are a crucial link with field observations, since the only way that researchers can obtain views of the rock record comparable to those generated by the experimental basin is through the filter of seismic reflection profiling. The synthetic seismics and well logs, when contrasted against the actual experimental stratigraphy, will also advance our understanding of what is and is not retained from the rock record when it is imaged via these widely used techniques. The experimental results would represent the first test under fully controlled conditions of a wide variety of theoretical predictions of stratigraphic response that have been developed since Pitman's (1978) model of shoreline response to changing sea level. They would also provide a template that could be compared with field observations and interpretations based on seismic and outcrop data. Although laboratory scale models can never capture all of the complex processes that occur in real basins, they serve as a bridge between untested theoretical models and difficult-to-constrain natural examples.

9725471 Pratson我们提出了一项为期三年的物理地层学形成实验研究计划，利用圣安东尼瀑布实验室（SAFL）一个带有沉降底板的大型新实验盆地。该设施可以在完全控制基准面、沉积物供应，特别是沉降模式和速率的情况下，研究规模化的盆地过程。水池长13米，宽6.5米，有1.3米的容纳空间用于沉积。沉降底板包括432个独立可控的沉降单元，以蜂窝状布置。这种设计允许创造几乎无限范围的空间和时间下沉模式。泥沙和水可以从盆地边缘的任何地方进入，而基准面（即水位）是独立可控的。我们的第一个实验将旨在测试一些已经提出的在盆地尺度上形成物理地层学的模型的一阶预测，例如：(1)岸线迁移和相关地层学与沉降率和海平面上升之间的相互作用的关系；(2)沉降速率、沉降形态和泥沙供给对冲积粗相分布（即同构造砾石的成因）的控制作用；(3)沉降速率和输沙量对冲积结构发育的影响。初步结果表明，实验还可以提供对生长断层等尚未广泛纳入现有模型的过程的见解。这些实验将使用相对简单的沉降和泥沙供给几何图形，并将着重于证明“单位”地层对同时发生的一个或至多两个变量变化的反应。第二组实验将重点研究沉降和泥沙供给的三维效应，包括：1)基准面变化的三维效应；2)盆地近端扩展的活动褶皱与盲目逆冲和渐进式不整合发育有关；3)横向排水和轴向排水相结合的非对称半地堑沉积。实验的主要成果将包括：施加变量（水和沉积物供应、基准面和基底地形）的时间记录；床面地形随时间的测量；流型、岸线位置和其他地表特征的视频记录；生成的矿床的三维方框图，以直接数字化（摄影）和合成地震图像的形式呈现；以及选定剖面的合成地球物理记录。合成地震是野外观测的一个关键环节，因为研究人员获得与实验盆地产生的岩石记录相媲美的唯一方法是通过地震反射剖面的过滤。将合成地震和测井资料与实际的实验地层学进行对比，也将有助于我们了解通过这些广泛使用的技术进行成像时，岩石记录中保留了什么，没有保留什么。自皮特曼（Pitman, 1978）提出海岸线对海平面变化的反应模型以来，已经发展了各种各样的地层反应理论预测，实验结果将是在完全控制条件下的第一次测试。它们还将提供一个模板，可与基于地震和露头数据的实地观测和解释进行比较。尽管实验室规模的模型永远无法捕捉到真实盆地中发生的所有复杂过程，但它们可以作为未经检验的理论模型和难以约束的自然例子之间的桥梁。