Environmental controls on turbidity current dynamics


  • Supervisors: Dr Iris Verhagen, University of Liverpool
    Dr C Stevenson, University of Liverpool
    Dr S De Angelis, University of Liverpool

  • External Supervisors:

  • Contact:

    Dr I Verhagen, University of Liverpool, verhagen@liverpool.ac.uk

  • CASE Partner:

Application deadline: 10 January 2020

Introduction:

Turbidity currents are one of the most important mechanisms to transport sediment in the marine environment.  Consequently deep-water turbidites form the largest sediment accumulations on the planet (e.g. Talling et al., 2012). Understanding how these flows behave and characterising their deposits is crucial not only for hydrocarbon exploration purposes, but also the engineering of offshore infrastructure, dispersal of pollutants, and general sediment dynamics.

Most of the research in turbidity current processes is focussed on laboratory experiments, since observing turbidity currents in the natural environment is challenging (Xu et al., 2004; Sumner and Paull, 2014). To date, most experimental studies have used simplified, present-day conditions (i.e. silica sediment, fresh water at room temperature) to study flow dynamics and deposition from turbidity currents.

This PhD project will explore and quantify the effect of more extreme environmental conditions on the flow behaviour and resulting deposit characteristics of turbidity currents. These conditions are not only applicable to different periods in Earth’s history (i.e. icehouse vs. greenhouse situations) but could potentially be applied to sediment dynamics on other planets.

The overall aim of this project is to establish the key controls on the variability of flow dynamics in turbidity currents and the potential effects of this on the resulting deposits. To do this, project laboratory experiments will be conducted to simulate turbidity currents, followed by the analysis of both the flow dynamics, interaction with the substrate (if present) and the deposits.

Project Summary:

This laboratory-based PhD project will conduct a quantitative exploration of the impact of environmental controls on the flow dynamics and deposition of turbidity currents. The work will involve detailed flume tank experiments that simulate gravity flows under stretched environmental conditions, such as elevated/reduced water temperatures/densities, mixed sediment composition and increased salinity. Subsequently the flow properties (e.g. velocity and turbulence) and sediment characteristics of the deposits (e.g. grain-size, sorting, geometry, run-out distance, etc.) will be examined in detail.

During the project the candidate will work in a multidisciplinary team with members of staff from the sedimentary geology and petroleum geology research groups within the Department of Earth, Ocean and Ecological Sciences and collaborate with staff in the Hydraulics Laboratory, which is based in the School of Engineering. The PhD candidate will receive training in the design and running of flume experiments and the use of multiple analytical techniques including ultrasonic velocimetry (UDVP). Additionally, the candidate will be trained in scientific writing and will publish work in international peer-reviewed journals. The project comprises both pure and applied aspects of (petroleum) geology and will therefore be suitable for candidates who wish to pursue a career in either academia or in industry.

References:

Sumner, E.J. and Paull, C.K., 2014. Swept away by a turbidity current in Mendocino submarine canyon, California. Geophysical Research Letters, 41(21), pp.7611-7618. 

Talling, P.J., Masson, D.G., Sumner, E.J., and Malgesini, G., 2012. Subaqueous sediment density flows: Depositional processes and deposit types. Sedimentology, 59, 1937-2003 

Xu, J.P., Noble, M.A. and Rosenfeld, L.K., 2004. In‐situ measurements of velocity structure within turbidity currents. Geophysical Research Letters, 31(9).

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