Geology Reference
In-Depth Information
Fig. 6.39
Reconstruction at 33 Ma (C13 - Rupelian),
illustrating the acceleration field of Pacific (
red arrows
)
and the global plate velocities (
black arrows
).
P
PAC
is the
pole of acceleration of the Pacific plate.
Black
areas are
LIPS. Coastlines are overlaid for reference
Fig. 6.40
Reconstruction at 19 Ma (C6 - Burdigalian),
illustrating the acceleration field of Nazca (
green arrows
)
and the global plate velocities (
black arrows
).
P
NAZ
is
the pole of acceleration of Nazca.
Black
areas are LIPS.
Coastlines are overlaid for reference
acceleration of Nazca between C6 and C5
(
11 Ma - Tortonian) (Fig.
6.40
). In conclusion,
eight major phases of non-equilibrium kinematics
could have occurred during the last 230 Myrs.
These episodes interested individual plates,
which experienced a stage of accelerated motion,
accompanied by fast spreading on one boundary
and rapid subduction along an opposite boundary.
In some cases, the plates were subject to a sudden
slowdown rather than to increasing velocity. In
any event, the force exerted by the downgoing
slabs was not balanced by the resistive viscous
