The Effects of Rate of Base‐Level Fluctuation on Coastal‐Plain, Shelf and Slope Depositional Systems: An Experimental Approach
The Effects of Rate of Base‐Level Fluctuation on Coastal‐Plain, Shelf and Slope Depositional Systems: An Experimental Approach
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基准面升降速率对沿海平原、陆架和斜坡沉积系统的影响：一种实验方法
DOI：
10.1002/9781444304015.ch3
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发表时间：
2009
期刊：
影响因子：
--
通讯作者：
S. Schumm
中科院分区：
文献类型：
--
作者：
L. Wood;F. Ethridge;S. Schumm
层序地层学的发展提出了许多关于沿海平原、陆棚和斜坡系统沿着被动边缘对基准面变化的反应方式的假设。为了验证这些假设，在一个长7 m、宽4.5 m、深0.9 m的非循环水槽中进行了一系列实验。结果表明，基准面变化率对陆棚和陆坡上形成的下切谷数量、填谷和三角洲沉积的厚度、特征和几何形状以及河流、三角洲和陆坡沉积的保存潜力有很大影响。基准面的快速下降产生了薄的、广泛的陆棚三角洲沉积物、多个薄的、细粒的、时间同步的陆棚边缘三角洲沉积物和多个直的河流河道。一个山谷最终捕获了所有的流量。在随后的基准面上升过程中，该山谷充满了来自腹地的粗粒沉积物，而其他山谷则充满了主要是细粒沉积物。一个快速上升导致薄，后退，海侵三角洲，比以前的低水位deposit.In相比之下，基准面的缓慢下降产生较厚的，不太广泛的陆棚三角洲比那些在基准面的快速下降和一个单一的，大的弯曲的山谷形成在陆棚休息和货架上形成。在缓慢下降过程中形成了一系列大型的、穿时的陆棚边缘三角洲。在随后的基准面上升过程中，单个山谷被来自河流的粗粒沉积物填充。它包含了较厚的海侵三角洲沉积物比那些形成在基准面快速上升。由于基准面的快速上升，这些海侵沉积物的粒度比以前的低水位期沉积物更粗。
Developments in sequence stratigraphy have suggested many assumptions about the manner in which coastal‐plain, shelf and slope systems along passive margins react to base‐level changes. A series of experiments were performed in a 7 m long by 4.5 m wide by 0.9‐m deep non‐recirculating flume to test these assumptions.Results suggest that the rate of base‐level change has a strong influence on the number of incised valleys that develop on the shelf and slope, on the thickness, character and geometry of the valley‐fill and delta deposits and on the preservation potential of fluvial, deltaic and slope deposits. A rapid fall of base level produced thin, widespread shelf delta deposits, multiple, thin, fine‐grained, time‐synchronous shelf margin delta deposits and multiple, straight fluvial channels. One valley eventually captured all of the flow. During subsequent base‐level rise, this valley filled with coarse‐grained sediments from the hinterland while the others filled with dominantly fine‐grained sediment. A rapid rise resulted in thin, backstepping, transgressive deltas that were much coarser grained than previous lowstand deposits.In contrast, a slow fall in base level produced thicker, less widespread shelf deltas than those that formed during the rapid fall of base level and a single, large sinuous valley formed at the shelf break and on the shelf. A series of large, diachronous shelf margin deltas formed during slow fall. During subsequent base‐level rise, the single valley was filled with coarse‐grained sediments from the fluvial channel. It contained thicker transgressive delta deposits than those formed during a fast rise of base level. As in the rapid base‐level rise, these transgressive deposits were coarser grained than the deposits of the previous lowstand time.