Understanding drainage development and hanging wall stratigraphy in extensional terrains: a coupled geomorphic-subsurface study.

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22 Φεβ 2014 (πριν από 3 χρόνια και 1 μήνα)

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Understanding d
rainage 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 i
n
extensional settings
exert a first order control o
n 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 b
lock
.
To
-
date, t
he

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 feed
ing


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
stratigr
a
phy
.

This project
addresses

th
ese

key question
s

through a
combined modelling
-
geomorphology
-
subsurface study
of drainage development and normal fault inter
action in modern and ancient rift
basins
.




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
c
atchments which
drain

away from the fault, down

the
dip
-
slope of the footwall

to the hanging wall
basin of the fault system to the
n
orth
(red arrows)
,
forming the

valley in the centre of the picture
.
Understanding what controls the evolution of these drai
nages 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
Elevati
on 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
Hanging wall

Footwall

(e.g. Whittaker et al.,
Basin Research
, 20
10
). 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.

(i
i)
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
)
l
it
hological

variations
across

and within

the main
hanging wall

dipslope drainage
catchments
; (
b
)
t
hree
-
dimensional g
eometry of
hanging wall

dipslope

catchments
;

and

(
c
)
e
stimation of the volume

of sediment

exported from hanging

wall catchments
.

(iii)
Coupl
ed 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 e
xplicitly 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 t
he

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
interna
tional 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 ARC
GiS,

subsurface analysis
software such as Petrel
and Kingdom Suite
, and will use the CHILD landscape evolution model
.

The proje
ct
would provide
a really good

starting point for a student

looking for a future career
in
i
ndustry

or

in

academia.

For further information on this project please contact Dr
Christopher Jackson (
c.jackson@impe
rial.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 catchme
nts perturbed by active
tectonics,
Basin Research,

v. 22, p. 809
-
828, doi: 10.1111/j.1365
-
2117.2009.00447.x.