Understanding drainage development and hanging wall stratigraphy in
extensional terrains: a coupled geomorphic-subsurface study.
Supervisors: Dr Chris Jackson (c.jackson@imperial.ac.uk) & Dr Alex Whittaker
(a.whittaker@imperial.ac.uk); Dr Mikael Attal (University of Edinburgh)
Background: The location, nature and magnitude of sediment supply to basins in
extensional settings exert a first order control on the characteristics of hanging wall
stratigraphy. Analysis of recent systems, and numerical modelling suggest close
coupling between the timing and rates of fault growth (via slip and lateral growth),
and the export of sediment from the uplifting fault block. To-date, the majority of
research has focused on the evolution footwall catchments that directly supply the
proximal hanging wall in rift basins.
However, little research has been conducted on the evolution of catchments
which drain away from the footwall fault, specifically feeding “dip-slope”
depositional systems (Fig. 1). These systems are often volumetrically significant in
modern and ancient examples. A significant research challenge is therefore to
quantify the circumstances in which these dip-slope depositional systems develop,
and to evaluate the implications this has for basin stratigraphy. This project addresses
these key questions through a combined modelling-geomorphology-subsurface study
of drainage development and normal fault interaction in modern and ancient rift
basins.
Footwall
Hanging wall
Fig. 1: An active normal fault in the Gulf of Suez (black). While a small catchment (blue arrow)
sources sediment directly to a hanging wall fan delta, much of the footwall in the image is eroded by
catchments which drain away from the fault, down the dip-slope of the footwall to the hanging wall
basin of the fault system to the north (red arrows), forming the valley in the centre of the picture.
Understanding what controls the evolution of these drainages is crucial for determining sediment
supply to basins and predicting the characteristics of depositional stratigraphy.
Methods:
The project has 3 interlinked elements:
(i) Analysis of modern drainage systems in extensional basins – Digital
Elevation Model (DEM) analysis will be undertaken of regional drainage patterns in a
range of normal fault-bounded basins, such as the Italian Apennines and Gulf of Suez
(e.g. Whittaker et al., Basin Research, 2010). Basins with a range of fault-slip rates
and of degrees of fault interaction will be chosen. This element of the study will
quantify the controls on the significance, spatial extent and sediment transport
capacity of hanging wall and footwall drainage systems in modern systems.
(ii) Analysis of ancient drainage systems in extensional basin stratigraphy –
Subsurface analysis (seismic and well data) will be undertaken on a series of hanging
wall dipslope locations within the Late Jurassic North Sea Rift System and the
following will be quantified: (a) lithological variations across and within the main
hanging wall dipslope drainage catchments; (b) three-dimensional geometry of
hanging wall dipslope catchments; and (c) estimation of the volume of sediment
exported from hanging wall catchments.
(iii) Coupled drainage-tectonic modelling – This will be undertaken using the
Channel-Hillslope Integrated Landscape Development (CHILD) model coupled to a
fault growth model of normal fault array development. We will investigate how the
development of hanging wall drainage systems is promoted or hindered for a given
range of fault slip rates and fault segment interaction times. This will provide generic
insights into the controls on sediment supply to hanging wall basins and will generate
results which can then be explicitly compared with observations in both modern and
ancient subsurface examples (above).
Outcomes: The proposed project will produce novel insights into the controls on
hanging wall sedimentation in extensional settings, and will provide new data on the
dynamic coupling of tectonics, erosion and sediment deposition through time. Results
from the PhD will be published in high-impact journals and the student will also get
the chance to present key findings both at UK conferences and at least one
international meeting.
Training: This PhD is ideally suited for a candidate with an interest structural
geology, sedimentology and/or geomorphology. The candidate will hold a strong (2:1
or higher or equivalent) undergraduate (BSc or equivalent) and/or masters level
degree in geology, geophysics or a related physical science. The student will receive
training in GIS software such as ARCGiS, subsurface analysis software such as Petrel
and Kingdom Suite, and will use the CHILD landscape evolution model. The project
would provide a really good starting point for a student looking for a future career in
industry or in academia. For further information on this project please contact Dr
Christopher Jackson (c.jackson@imperial.ac.uk) and Dr Alex Whittaker
(a.whittaker@imperial.ac.uk).
Reference:
Whittaker, A. C., Attal, and Allen, P. A., 2010, Characterising the
origin, nature and fate of sediment exported from catchments perturbed by active
tectonics, Basin Research, v. 22, p. 809-828, doi: 10.1111/j.1365-2117.2009.00447.x.