Sedimentation from forced wall jets versus free gravity flows: integrating tank experiments and field data into a physics-based depositional model

最近，人们越来越认识到弗劳德超临界密度流对深水碎屑沉积体系的影响。这些沉积物主要保存在扩张流区，那里的加积作用最强。这种膨胀流动的区域可以被建模为超临界射流。淹没平面壁射流，从孔口进入静止水体并减速，可以被认为是与扩展相关的沉积过程的基本模型，点源流，如海底扇和水下冰接触扇。扩张超临界流的形态动力学有很大的影响，沉积物的分散和由此产生的沉积体系结构的水下冰接触风扇，沉积的射流，和海底风扇，沉积的重力流，分别。喷流及其沉积物显示出明显的近远分带。密度弗劳德数施加的流动动力学和从惯性驱动的射流到密度驱动的重力流的演变的主要控制。平壁射流与重力流之间的过渡对膨胀流的沉积有很大的影响。现有的知识射流和重力流，它们的水动力和地貌动力学的演变，以及它们的存款是不够的，以解释的特点床形和相序列。该项目旨在调查这两种流动类型，并通过整合水槽实验和现场数据的观察结果来制定其沉积物的识别标准。在该项目的实验部分，将在水槽实验中描述射流和重力流的形态动力学特征，从而能够系统地改变控制水流和沉积物的参数。在该项目的实地部分，将研究与粗粒超临界海底扇的流动膨胀区有关的沉积物。这些现场实例必须能够详细描述沉积结构和相序，并提供足够的细节来反演流动强迫。通过整合实验和露头的观测结果，将开发一个通用的、基于物理学的超临界密度流膨胀沉积模型。

Recently, the impact of Froude supercritical density flows on deepwater clastic depositional systems has been increasingly recognized. These deposits are mainly preserved in the regions of expanding flows, where the aggradation is highest. Such regions of expanding flow can be modeled as supercritical jet flows. Submerged plane-wall jet flows, which emerge from an orifice into a standing water body and decelerate, can be considered as basic model for depositional processes related to expanding, point-sourced flows, like submarine fans and subaqueous ice-contact fans. The morphodynamics of expanding supercritical flows have a large impact on the dispersal of sediment and the resulting depositional architecture of subaqueous ice-contact fans, deposited by jet flows, and submarine fans, deposited by gravity flows, respectively. Jet flows and their deposits display a distinctive proximal to distal zonation. The densimetric Froude number exerts a primary control on the flow dynamics and the evolution from inertia-driven jets into density-driven gravity flows. The transition between plane-wall jets and gravity flows has a large impact on the deposition by expanding flows. The existing knowledge of jet flows and gravity flows, their hydrodynamic and morphodynamic evolution, and their deposits is insufficient to explain the characteristic bedform and facies successions. This project is designed to investigate these two flow types and develop recognition criteria for their deposits by integrating observations from tank experiments and field data. In the experimental part of the project, the morphodynamics of jet flows and gravity flows will be characterized in tank experiments, enabling the systematic variation of the controlling flow and sediment parameters. In the field part of the project, deposits related to zones of flow expansion from coarse-grained supercritical submarine fans will be studied. These field examples must enable a detailed characterization of the depositional architecture and facies successions and provide sufficient detail to invert for flow forcing. By the integration of the observations from the experiments and the outcrops a generic, physics-based model for deposition by expanding supercritical density flows will be developed.