TY - JOUR
T1 - Numerical modelling of rise and fall of a dense layer in salt diapirs
AU - Chemia, Zurab
AU - Koyi, H.
AU - Schmeling, H.
PY - 2008
Y1 - 2008
N2 - Numerical models are used to study the entrainment of a dense anhydrite
layer by a diapir. The anhydrite layer is initially horizontally
embedded within a viscous salt layer. The diapir is down-built by
aggradation of non-Newtonian sediments (n = 4, constant temperature)
placed on the top of the salt layer. Several parameters (sedimentation
rate, salt viscosity, perturbation width and stratigraphic position of
the anhydrite layer) are studied systematically to understand their role
in governing the entrainment of the anhydrite layer. High sedimentation
rates during the early stages of the diapir evolution bury the initial
perturbation and, thus, no diapir forms. The anhydrite layer sinks
within the buried salt layer. For the same sedimentation rate,
increasing viscosity of the salt layer decreases the rise rate of the
diapir and reduces the amount (volume) of the anhydrite layer
transported into the diapir. Model results show that viscous salt is
capable of carrying separate blocks of the anhydrite layer to relatively
higher stratigraphic levels. Varying the width of the initial
perturbation (in our calculations 400-800 m), from which a diapir
triggers, shows that wider diapirs can more easily entrain an embedded
anhydrite layer than the narrower diapirs. The anhydrite layer is
entrained as long as rise rate of the diapir exceeds the descent rate of
the denser anhydrite layer. We conclude that the four parameters
mentioned above govern the ability of a salt diapir to entrain an
embedded dense layer. However, the model results show that the entrained
blocks inevitably sink back if the rise rate of the diapir is less than
the rate of descent of the anhydrite layer or the diapir is permanently
covered by a stiff overburden in case of high sedimentation rates.
AB - Numerical models are used to study the entrainment of a dense anhydrite
layer by a diapir. The anhydrite layer is initially horizontally
embedded within a viscous salt layer. The diapir is down-built by
aggradation of non-Newtonian sediments (n = 4, constant temperature)
placed on the top of the salt layer. Several parameters (sedimentation
rate, salt viscosity, perturbation width and stratigraphic position of
the anhydrite layer) are studied systematically to understand their role
in governing the entrainment of the anhydrite layer. High sedimentation
rates during the early stages of the diapir evolution bury the initial
perturbation and, thus, no diapir forms. The anhydrite layer sinks
within the buried salt layer. For the same sedimentation rate,
increasing viscosity of the salt layer decreases the rise rate of the
diapir and reduces the amount (volume) of the anhydrite layer
transported into the diapir. Model results show that viscous salt is
capable of carrying separate blocks of the anhydrite layer to relatively
higher stratigraphic levels. Varying the width of the initial
perturbation (in our calculations 400-800 m), from which a diapir
triggers, shows that wider diapirs can more easily entrain an embedded
anhydrite layer than the narrower diapirs. The anhydrite layer is
entrained as long as rise rate of the diapir exceeds the descent rate of
the denser anhydrite layer. We conclude that the four parameters
mentioned above govern the ability of a salt diapir to entrain an
embedded dense layer. However, the model results show that the entrained
blocks inevitably sink back if the rise rate of the diapir is less than
the rate of descent of the anhydrite layer or the diapir is permanently
covered by a stiff overburden in case of high sedimentation rates.
U2 - 10.1111/j.1365-246X.2007.03661.x
DO - 10.1111/j.1365-246X.2007.03661.x
M3 - Journal article
SN - 0956-540X
VL - 172
SP - 798
EP - 816
JO - Geophysical Journal International
JF - Geophysical Journal International
IS - 2
ER -