TITLE:
Temperature-Dependent Newtonian Rheology in Advection-Convection Geodynamical Model for Plate Spreading in Eastern Volcanic Zone, Iceland
AUTHORS:
Md. Tariqul Islam, Erik Sturkell
KEYWORDS:
Mid-Atlantic Ocean Ridge, Advection-Convection, Plate Spreading, Geodynamic Modeling, Newtonian Rheology
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.3 No.5,
July
17,
2015
ABSTRACT: Geodynamic process as advection-convection
of the Mid-Atlantic Ocean Ridge (MAR), that is exposed on land in Iceland is
investigated. Advection is considered for the plate spreading velocity.
Geodetic GPS data during 2000-2010 is used to estimate plate spreading velocity
along a profile in the Eastern Volcanic Zone (EVZ), Iceland striking N102。E,
approximately parallel to the NUVEL-1A spreading direction between the Eurasian
and North American plates. To predict subsurface mass flow patterns,
temperature-dependent Newtonian rheology is considered in the finite-element
models (FEM). All models are considered 2-D with steady-state, incompressible
rheology whose viscosity depends on the subsurface temperature distribution.
The thickness of lithosphere along the profile in the EVZ is identified by 700。C
isotherm and 1022 Pa s iso-viscosity, those reach 50 ± 3 km depth at distance
of 100 km from rift axis. Geodetic observation and model prediction results
show the ~90% of spreading is accommodated within ~45 km of the rift axis in
each direction. Model predicts ~8.5 mm.yr-1 subsidence at the surface of rift
center when magmatic plumbing is inactive. The rift center (the highest
magmatic influx is ~11 mm.yr-1) in model shifts ~10 - 20 km west to generate
observed style surface deformation. The spreading velocity, isotherm and depth
of isotherm are the driving forces resulting in the surface deformation. These
three parameters have more or less equal weight. However, as the center of
deformation in the EVZ shifts and most of the subsidence takes place in the
volcanic system that is currently the active which is the located of plate
axis.