ABSTRACT
A mathematical model for granitoid diapirism has been developed
that
accounts for the time dependent thermal and rheological conditions
encountered
by the intruding body. This model is derived by the simultaneous
solution
of the partial differential equations of energy, continuity, and
momentum
utilizing scaling analysis. The underlying assumption is that
deformation
of the surrounding country rock is confined to a relatively thin
layer
with a temperature dependent Newtonian viscosity. When the country
rock
is modeled as a power-law fluid, the effective viscosity is
dependent upon
temperature and shear strain rate.
This model allows for realistic temperature gradients within the
crust
and variable shear strain rates. This is made possible through use
of a
numerical approximation referred to as the "snapshot" approach.
This method
allows the pluton to ascend in finite time increments while the
boundary
conditions remain fixed. Following each snapshot, the ascent
velocity is
calculated and new boundary and initial conditions are set for the
next
increment of time.
Several model runs have been performed using a FORTRAN program.
The
results exhibit time dependent variations in the ascent velocity
due to
corresponding changes in the overall rheology, and thickness, of
the deformation
layer. One of the conclusions from this study is that larger
plutons ascend
at slower rates, but emplace higher in the crust due to the
additional
energy available relative to smaller plutons.
Mahon, K.I., 1985. A numerical approach for determining the
variable
ascent velocity of a granitoid diapir. Unpublished MSc.
thesis, State
University of New York at Albany. 158 pp., +ix
University at Albany Science Library call number: SCIENCE
Oversize
(*) QE 40 Z899 1985 M35
thesis (scanned
text) - 4.8MB pdf file
Return to MS Theses completed in the
Geological
Sciences Program, University at Albany