Process-physics-based, coupled hydrodynamic–morphodynamic delta models are constructed to understand preserved facies heterogeneities that can influence subsurface fluid flow. Two deltaic systems are compared that differ only in the presence of waves: one river dominated and the other strongly influenced by longshore currents. To understand an entire preserved deltaic succession, the growth of multiple laterally adjacent delta lobes is modeled to define delta axial to marginal facies trends through an entire regressive–transgressive depositional succession. The goal is to refine a facies model for symmetrical wave-dominated deltas (where littoral drift diverges from the delta lobe apex). Because many factors change depositional processes on deltas, the description of the river-dominated example is included to provide a direct reference case from which to define the impact of waves on preserved facies patterns. Both systems display strong facies trends from delta axis to margin that continued into inter-deltaic areas. River-dominated delta regression preserved a dendritic branching of compensationally stacked bodies. Transgression, initiated by sea-level rise, backfilled the main channel and deposited levees and splays on the submerging delta top. Wave-dominated deltas developed dual clinoforms: a shoreface clinoform built as littoral drift carried sediment away from the river month and onshore, and a subaqueous delta-front clinoform composed of sediment accumulated below wave base. Although littoral drift in both directions away from the delta axis stabilized the position of the river at the shoreline, distributary-channel avulsions and lateral migration of river flows across the subaqueous delta top produced heterogeneities in both sets of clinoform deposits. Separation of shoreface and subaqueous delta-front clinoforms across a subaqueous delta top eroded to wave base produced a discontinuity in progradational vertical successions that appeared gradual in some locations but abrupt in others. Littoral drift flows away from adjacent deltas converged in inter-deltaic areas, producing shallow water longshore bars cut by wave-return-flow channels with associated terminal mouth bars. Transgression initiated by sea-level rise initially led to vertical aggradation of wave-reworked sheet sands on the subaqueous delta top and then retreating shoreface barrier sands as the subaerial delta top flooded. Pseudo inter-well flow tests responded to local heterogeneities in the preserved deposits. As expected, abandoned channels in the river-dominated case defined shoreline-perpendicular preferential flow paths and wave-dominated delta deposits are more locally homogeneous, but scenarios for development of more pronounced shore-parallel heterogeneity patterns for wave-influenced deltas are discussed. The results highlight the need to consider the dual clinoform nature of wave-dominated delta deposition for facies prediction and subsurface interpretation.

中文翻译：

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河流为主和对称波浪为主的三角洲沉积物之间的对比相型

基于过程物理学的耦合水动力-形态动力三角洲模型可以理解可能影响地下流体流动的保留相非均质性。比较了两种三角洲系统，它们仅在波浪存在时有所不同：一条河流占主导地位，另一条河流受到长岸流强烈影响。为了理解整个保留的三角洲演替，对多个横向相邻的三角洲凸起的增长进行了建模，以定义通过整个回归-海相沉积演替而形成的从轴向到边缘相的三角洲趋势。目标是为对称波为主的三角洲（沿岸三角洲漂移与三角洲三角洲顶点分叉）完善相模型。由于许多因素都会改变三角洲上的沉积过程，包括以河流为主导的示例的描述，以提供直接参考案例，从中可以定义波浪对保留相模式的影响。两种系统都显示出从三角轴到边缘的强相趋势，并一直延伸到三角洲间地区。以河流为主的三角洲回归保留了补偿性堆积体的树枝状分支。海平面上升引发的海侵，使主河道回填，并在淹没的三角洲顶部沉积了堤坝和张径。波浪主导的三角洲形成了双重斜面形式：沿海岸漂流而建的岸面斜面形式将沉积物带离河月和陆上，而水下三角洲前斜面形式则由沉积在波浪基之下的沉积物构成。尽管沿远离三角洲轴线的两个方向的沿海漂移稳定了河流在海岸线上的位置，但在两类斜状沉积物中，分布河道的撕脱和河水在三角洲水下的横向流动都产生了异质性。在侵蚀到波基的水底三角洲上，水面和水底三角洲前斜形的分离产生了渐进的垂直演替的不连续性，在某些位置逐渐出现，但在另一些地方则突变。沿岸漂流远离在三角洲间区域汇聚的相邻三角洲，从而产生了浅水长岸横条，该横条被带有相关终端口条的回波流通道所切割。海平面上升引发的海侵最初导致水下三角洲顶面的波加工薄板砂垂直沉降，然后随着水下三角洲顶面的泛滥而撤退岸面屏障砂层。伪井间流动测试响应了保留矿床中的局部异质性。不出所料，在以河流为主的情况下，沿岸线垂直的优先流动路径和以波浪为主的三角洲沉积物的废弃河道在局部上更加均匀，但是讨论了对于受波浪影响的三角洲开发更为明显的沿岸平行非均质模式的方案。结果强调需要考虑波浪为主的三角洲沉积的双重斜面性质，以进行相预测和地下解释。伪井间流动测试响应了保留矿床中的局部异质性。不出所料，在以河流为主的情况下，沿岸线垂直的优先流动路径和以波浪为主的三角洲沉积物的废弃河道在局部上更加均匀，但是讨论了对于受波浪影响的三角洲开发更为明显的沿岸平行非均质模式的方案。结果强调需要考虑波浪为主的三角洲沉积的双重斜面性质，以进行相预测和地下解释。伪井间流动测试响应了保留矿床中的局部异质性。不出所料，在以河流为主的情况下，沿岸线垂直的优先流动路径和以波浪为主的三角洲沉积物的废弃河道在局部上更加均匀，但是讨论了对于受波浪影响的三角洲开发更为明显的沿岸平行非均质模式的方案。结果强调需要考虑波浪为主的三角洲沉积的双重斜面性质，以进行相预测和地下解释。但是讨论了开发波影响三角洲更明显的岸平行异质性模式的方案。结果强调需要考虑波浪为主的三角洲沉积的双重斜面性质，以进行相预测和地下解释。但是讨论了开发波影响三角洲更明显的岸平行异质性模式的方案。结果强调需要考虑波浪为主的三角洲沉积的双重斜面性质，以进行相预测和地下解释。