Shoreline Trajectories and Sequences: Description of Variable Depositional-Dip Scenarios
Shoreline Trajectories and Sequences: Description of Variable Depositional-Dip Scenarios
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DOI：
10.1306/d42683dd-2b26-11d7-8648000102c1865d
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发表时间：
1996-07
影响因子：
2
通讯作者：
W. Helland‐Hansen;O. Martinsen
中科院分区：
文献类型：
--
作者：
W. Helland‐Hansen;O. Martinsen
摘要岸线迁移模式可以用岸线轨迹来描述，岸线轨迹是沿剖面沉积-倾角剖面观察的岸线路径。海岸线轨迹的离散类别可以定义为：增长和非增长强迫回归；正常回归；以及增长和非增长海侵。“海积”意味着提供给海岸线的沉积物参与确定海岸线轨迹，而“非海积”意味着现有的地形决定了该轨迹。在后一种情况下，海岸线的平移在没有显著沉积的情况下进行。海岸线轨迹和上述类别的方向为描述单个海岸线北东向漂移、堆积海岸线迁移模式、体系域和沉积旋回的可变海岸线行为提供了基础。当海平面下降时，海岸线上沉积的沉积物很少或没有沉积时，就会发生非吸积强迫退缩。当海平面下降伴随着海岸沉积物堆积时，就会发生吸积强迫退缩。沉积强迫海退的结构受冲积环境和海洋环境的坡度以及海岸线轨迹的控制。当海岸线的路径与前缘沉积基础汇合时，最有可能形成海洋侵蚀的退化面。在正常海退过程中，岸线轨迹和沉积基础通常会发生分叉，并伴随着进积岸线前方水域的加深。非增殖型海侵是指在海侵开始时，海侵的岸线轨迹与冲积面重合的海侵。在海侵开始时，海岸线向陆地一侧可能存在也可能不存在通融，但在海侵期间不会在那里产生通融。当海侵开始时，海岸线轨迹相对于冲积沉积面发散时，就会发生海侵。这意味着，在后退的海岸线后面，不断地产生和填充着住宿。如果海侵面是在海侵过程中形成的，那么只有在海侵过程中积累的沉积物仅被保存在海侵海岸线的海面(而不是海侵海岸线)的情况下，它的年代地层学意义才能保持。随着海岸线向不同方向移动，形成了复合堆积模式、体系域和沉积旋回，以及缓慢沉积、不沉积或侵蚀的表面或薄层段。这些水平可以用来包裹沉积旋回。旋回可细分为两个或四个体系域。最大海侵面最适用于旋回的圈定。与陆下不整合合并或侵蚀的沟槽面，与最大海退面相结合，也可用于圈闭旋回。
ABSTRACT Shoreline migration patterns can be described in terms of the shoreline trajectory, which is the shoreline path viewed along a cross-sectional depositional-dip section. Discrete classes of shoreline trajectories can be defined: accretionary and non-accretionary forced regression; normal regression; and accretionary and non-accretionary transgression. "Accretionary" implies that sediment supplied to the shoreline participates in determining the shoreline trajectory, whereas "non-accretionary" implies that existing topography dictates the trajectory. In the latter case, translation of the shoreline takes place without significant deposition. The directions of the shoreline trajectories and the above classes provide a basis for describing variable shoreline behavior for individual shorel ne excursions, for stacked shoreline migration patterns, for systems tracts, and for depositional cycles. A non-accretionary forced regression takes place when little or no sediment is deposited at the shoreline as sea level falls. Accretionary forced regressions occur when sea-level fall is accompanied by coastal sediment accumulation. The architecture of accretionary forced regressions is controlled by the slopes of the alluvial and marine environments, and the shoreline trajectory. A regressive surface of marine erosion is most likely to be formed when the path of the shoreline converges with the fronting depositional foundation. During normal regression, the shoreline trajectory and the depositional foundation usually diverge, with accompanying deepening of water in front of the prograding shoreline. A non-accretionary transgression is defined as a transgression with a shoreline trajectory coinciding with the alluvial depositional surface at the onset of transgression. Accommodation may or may not be present at the landward side of the shoreline at the onset of transgression, but will not be generated there during transgression. An accretionary transgression takes place when the shoreline trajectory diverges relative to the alluvial depositional surface at the onset of transgression. This implies that accommodation is continuously generated and filled behind the retreating shoreline. If a ravinement surface is formed during transgression, its chronostratigraphic significance is maintained only if sediments accumulating during transgression are solely preserved seaward (and not lan ward) of the transgressing shoreline. As the shoreline migrates in various directions, composite stacking patterns, systems tracts, and depositional cycles, as well as surfaces or thin intervals of slow deposition, nondeposition, or erosion are formed. These levels can be used to envelop the depositional cycles. The cycles can be subdivided into two or four systems tracts. The maximum transgressive surface is the most applicable for delineation of cycles. A ravinement surface that merges with or erodes into the subaerial unconformity, in combination with the maximum regressive surface, can also be useful for bracketing cycles.