Resolving Facies Architectures of the Fraser River Delta - Past and Present

三角洲是重要的沉积环境，无论在现代海岸线上还是在岩石记录中都是如此。在地下，它们拥有大量的水和碳氢化合物资源。三角洲体系是复杂的，受波浪、潮汐和河流过程的影响，其结构部分受粒度、沉积坡度、气候和构造的控制。限制三角洲体系中可预期的沉积形态范围是具有挑战性的，但为了预测地下储集体的形态和模拟流体流动，这是必要的。如果要发展和完善预测模型来解释古三角洲层序，解决现代三角洲的结构和控制沉积的沉积过程是至关重要的。 通过这一研究计划，将建立一个综合的沉积学和生物过程-响应模型和弗雷泽河三角洲的三维相结构。过程-响应模型将提供现代三角洲的基线数据，以便在理解三角洲演化方面进行比较。三维建筑模型可用于绘制渗透性沉积物中的流体流动图，根据历史数据改进斜坡破坏的估计，并根据相分析改进三角洲的沉积历史。该相模型还将作为深水三角洲的模拟，特别是那些受潮汐影响但也形成于高梯度环境中的三角洲。为了实现过程-响应模型和三维三角洲体系结构的最终目标，定义了六个研究项目：1)潮汐控制的淡水皮特河和皮特河三角洲的沉积学特征；2)泥质湾潮汐小溪的河道迁移和泥沙堆积速率的量化以及海湾沉积模型的建立；3)边界湾砂坪的描述和与泥质湾泥滩的比较；4)弗雷泽河泥沙沉积和泥质推移质输运条件的确定；5)完成了整个弗雷泽河三角洲从潮汐回水的陆地边界到前三角洲的海洋边界的沉积学-生物模型；以及6)建立了三角洲的三维地下模型，重点是利用地球物理测井数据、地震剖面和重新解释岩心数据来识别三角洲次环境。还将开展第七个项目，将弗雷泽河三角洲的地下相图沿弗雷泽河谷向上延伸至美国华盛顿(即跨越弗雷泽低地)。 对泥石湾、边界湾和皮特河的研究将“完成”已经为三角洲获得的数据集，并将使我们能够模拟从潮汐死水的陆地边界到佐治亚州海峡底部的沉积学和生物趋势。完整的Fraser数据集将使我们能够定义区分振动岩心和地球物理测井中的三角洲亚环境的标准。为目前的三角洲开发的模型将用于构建和完善现有的地下模型，并绘制沉积相图。沉积相构成了对流经三角洲的流体流动的主要控制，三角洲的三维结构为绘制流体流动提供了高分辨率的格架。最后，相结构将延伸到弗雷泽低地，以确定弗雷泽河沉积的范围。

Deltas are important depositional environments, both on modern coastlines and in the rock record. In the subsurface, they host significant quantities of water and hydrocarbon resources. Delta systems are complex; they are affected by wave, tidal and river processes, and their architectures are partly controlled by grain size, depositional slope, climate and tectonics. Constraining the range of depositional morphologies that can be expected in deltaic systems is challenging, yet it is necessary in order to predict the morphologies of reservoir bodies in the subsurface and to model fluid flow. Resolving the architecture of modern deltas and the depositional processes that control sedimentation is essential if development and refinement of predictive models are to be achieved for interpreting paleo-deltaic successions. Through this research program a comprehensive sedimentological and ichnological process-response model and a three-dimensional facies architecture of the Fraser River Delta will be developed. The process-response model will provide baseline data on the modern delta for comparison in understanding delta evolution. The 3D architectural model can be used to map fluid flow through permeable sediments, refine estimates of slope failures based on historical data and refine the depositional history of the delta based on facies analysis. The facies model will also act as an analogue for deep-water deltas, particularly those that are tide influenced but also form in high gradient settings. To reach the final goal of a process-response model and a 3D delta architecture, six research projects are defined: 1) sedimentological characterization of the tide-dominated, freshwater Pitt River and Pitt River Delta; 2) quantification of channel migration and sediment accumulation rates in tidal creeks in Mud Bay and development of a depositional model for the bay; 3) characterization of the Boundary Bay sand flats and comparison to the Mud Bay mud flats; 4) determination of the conditions under which mud deposition and muddy bedload transport occurs in the Fraser River; 5) completion of a sedimentological-ichnological model for the entire Fraser River Delta from the landward limit of the tidal backwater to the seaward limit of the prodelta; and 6) construction of a three-dimensional subsurface model of the delta, focused on the recognition of delta subenvironments using geophysical-log data, seismic profiles, and the re-interpretation of core data. A seventh project will also be undertaken to extend subsurface facies mapping of the Fraser River Delta up the Fraser valley and into Washington, USA (i.e., across the Fraser lowlands). Research on Mud Bay, Boundary Bay and the Pitt River will "complete" the dataset already acquired for the delta, and will enable us to model sedimentological and ichnological trends from the landward limit of the tidal backwater to the base of the Strait of Georgia. The complete Fraser dataset will enable us to define criteria for differentiating delta subenvironments in vibracore and on geophysical logs. The models developed for the present delta will be used to construct and refine existing subsurface models, and to map out sedimentary facies. Sedimentary facies constitute the dominant control on fluid flow through the delta, and the 3D architecture of the delta provides a high-resolution framework for mapping fluid flow. Finally, the facies architecture will be extended across the Fraser lowlands to define the extent of sediment deposition from the Fraser River.