Dear colleagues,

I should be grateful if you could bring the following project to the
attention of any suitably qualified students.

Roger Searle

----------------------------------------------------------------------------
---------------------------------------------------
PhD Research Project

Title: Creation and early evolution of oceanic lithosphere: new
methodologies with high resolution magnetic anomalies

Supervisor:  Roger Searle, Professor of Geophysics and a former chairman of
the international research organisation InterRidge.  Over 25 years
experience researching mid-ocean ridges: [log in to unmask];
http://www.dur.ac.uk/~dgl0www/Staff/rcs.html

The project:  Oceanic lithosphere, which covers over half the planet, is
created at mid-ocean ridges within the space of about one million years.
During this time it is formed by dyke injection and other forms of igneous
intrusion and extrusion, is rapidly deformed by faulting and fissuring, and
is highly altered by oxidation and other chemical reactions, especially
near hydrothermal circulation cells.  All of these processes affect the
natural magnetization of the seafloor rocks, which thus carry a record of
their formation in their magnetization.  Current models of lithosphere
formation encompass a range of variable processes, from continuous,
symmetric igneous accretion to highly asymmetric, purely tectonic extension
on large-scale detachment faults.  These models can be tested and
constrained by the use of magnetic anomalies.
Traditionally marine geologists and geophysicists have used records of the
reversals of the Earth's field to date seafloor spreading; however, we are
now entering a time when much more information can be obtained from the
anomalies.  One way of doing this is to measure the magnetic field close to
the seafloor, either from a deeply towed vehicle or from a manned
submersible, in order to increase resolution.  Another is to record the
vector field (magnitude and direction), not just the magnitude as has been
done in the past, in order to be able to infer rotations of seafloor blocks 
At Durham we have begun to collect vector magnetic field data from both
deep-towed vehicles and submersibles.  Data exist from the slow-spreading
Mid-Atlantic Ridge and from the ultra-slow spreading South West Indian
Ridge.  We have plans to collect further data from the Reykjanes Ridge
(which is dominated by the Iceland mantle plume) and elsewhere.  We and our
colleagues have begun to develop methodologies for analysing and modelling
these data, but such work is in its infancy.  In this project, the student
will apply existing methodologies and develop new ones to infer and model
the distribution of the magnetisation vector in mid-ocean ridge rocks, and
use this information to constrain models of the magmatic and tectonic
processes involved in creation of the oceanic lithosphere.

Training:  The student will obtain training in the analysis, modelling and
inter-pretation of marine magnetic anomalies, in modern geophysical
computing, and in the geology of mid-ocean ridges.  All of our students
have access to the University's training courses, including a wide range of
computing courses and a special Postgraduate Skills programme aimed
specifically at the needs of research students.

The student:  The project will involve extensive computation and
geophysical analysis.  It would be appropriate for someone with a first
degree in geophysics or physics, or possibly a highly numerate geologist or
an applied mathematician with an interest in Earth Sciences.

Application:  Please send a CV and names and addresses of three academic
referees to Prof. Searle at: Department of Geoogical Sciences, University
of Durham, DH1 3LE.  Selected applicants will be asked to come for
interview during the period 17-19 March, 1999.

R. C. Searle
Professor of Geophysics and Chairman
Department of Geological Sciences
University of Durham
Durham, DH1 3LE
UK
Phone +44 (0)191 374 2537
Fax     +44 (0)191 374 2510


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%