The Role of Particle Size and Concentration in Defining the Flow Structure of Turbidity Currents and the Morphology of their Deposits: Insights from Computed Tomography

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Title: The Role of Particle Size and Concentration in Defining the Flow Structure of Turbidity Currents and the Morphology of their Deposits: Insights from Computed Tomography
Authors: Tilston, Michael Christopher
Date: 2017
Abstract: Turbidity currents are turbulent particle suspensions that are the primary mechanism for transporting terrestrial sediments to the deep marine, and generate some of the largest depositional features on Earth. However the fluid-particle interactions that sustain these currents are poorly understood, principally due to the technical challenges posed by obtaining accurate velocity and density measurements, which are critical for describing flow behavior and depositional characteristics. Numerous studies have bypassed these issues by using saline density currents, but this negates the ability to link flow processes with depositional features, and it is unclear whether their density structures are representative of particle gravity flows. Consequently, numerous questions remain over the flow conditions that build up a significant part of the deep-marine geologic record. In this thesis I reports on the flow processes and depositional features of sediment-gravity currents across a broad range of particle sizes and concentrations. The technical challenges of obtaining reliable density data are overcome by running the experimental flows through a medical grade computed tomography (CT) scanner, and pair this data with three-dimensional velocity measurements using an ultrasonic Doppler velocity profiler (UDVP-3D) to get one of the first glimpses of the internal structure of turbidity currents. Unlike previous studies where flow processes are described in terms of the velocity field, this thesis demonstrates that fluid-particle interactions are controlled by momentum characteristics, and that the velocity field is determined largely by the current’s density structure. Moreover, the density structure also exerts a first order control on the morphology of their deposits.
URL: http://hdl.handle.net/10393/35828
http://dx.doi.org/10.20381/ruor-20111
CollectionThèses, 2011 - // Theses, 2011 -
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