Collaborative Research: Experimental Study of Basin Stratigraphy

小行星9720416 我们提出了一个为期三年的物理地层形成实验研究计划，使用圣安东尼福尔斯实验室（SAFL）的一个带有沉降底板的大型新实验盆地。 该设施允许研究尺度盆地过程，完全控制基准面，沉积物供应，特别是沉降模式和速率。 该盆地长13米，宽6.5米，可容纳1.3米的沉积空间。 沉降底板包括432个以蜂窝图案布置的独立可控沉降单元。 这种设计允许创建几乎无限范围的空间和时间沉降模式。 沉积物和水可以从沿着盆地边缘的任何地方注入，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一阶预测模型，已提出的形成在盆地尺度的物理地层，如：（1）海岸线迁移和相关的地层之间的相互作用沉降率和海平面之间的关系;（2）沉降速率、沉降形态和沉积物供给对冲积粗相分布的控制（3）沉降速率和沉积物供给对冲积建筑物发育的影响。 初步结果表明，这些实验还可以提供对生长断层等过程的深入了解，这些过程尚未被广泛纳入现有模型。 这些实验将使用相对简单的沉降和沉积物进料几何形状，并将重点展示“单位”地层对一个或最多两个变量同时变化的反应。 第二组实验将侧重于沉降和沉积物供应的三维效应，包括：1）基准面变化的三维效应; 2）与盲冲断层和渐进不整合面发展相关的近端盆地中的活动褶皱的传播; 3）结合横向和轴向排水的不对称半地堑中的沉积。 实验的主要成果将包括：施加变量的时间记录（水和沉积物供应、基准面和基底地形）;随时间推移对床面地形的测量;流态、海岸线位置和其他表面特征的视频记录;所产生沉积物的三维方框图，（摄影）和合成地震图像;以及选定剖面的合成地球物理测井。 合成地震是与实地观测的一个关键环节，因为研究人员能够获得与实验盆地产生的岩石记录相比较的岩石记录视图的唯一途径是通过地震反射剖面的过滤器。 与实际的实验地层学相比，合成地震和测井也将促进我们对岩石记录中保留和不保留的内容的理解，当岩石记录通过这些广泛使用的技术成像时。 实验结果将代表自皮特曼（1978）的海岸线对海平面变化的响应模型以来，在完全受控条件下对各种地层响应的理论预测的第一次检验。 它们还将提供一个模板，可与实地观察和基于地震和露头数据的解释进行比较。 虽然实验室规模的模型永远无法捕捉到真实的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实例之间的桥梁。

9720416 Heller 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 u nconformities; 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.