Vertical Axis Rotation of
Rigid Crustal Blocks Driven
by Mantle Flow
Scott Giorgis
Michelle Markley
Basil Tikoff
20 April 2004
Wrench Tectonics - Different End
Members
(Sylvester, 1988)
1
A Reminder Two Models of Crustal Dynamics
Side-Driven
1.
•
i.e. driven by plate interaction
Bottom-Driven
2.
•
•
i.e. driven by mantle flow
Investigated in this paper
Another Reminder - Two Tools
Paleomagnetism
1.
•
Constrains crustal block rotation
Shear Wave Splitting
2.
•
•
Constrains mantle anisotropy, and (we think)
deformation
Found in zones stretching for 100s of km away
from the plate boundary
2
Mantle-Crust Interaction
Kinematic Regimes
3
Rotation of Material Lines
Rotation of Rigid Ellipse
(R=1.75:1)
4
Experimental Apparatus
(Markley & Tikoff, 2002)
Matchstick Experiment
(Oblique Divergence, α=165˚)
5
Matchstick Results
Rigid Ellipse Experiment
(Oblique Convergence, α=-165˚)
6
Rigid Ellipse Results
Eastern Transverse Ranges
7
Marlborough Fault Zone
Shear Wave Splitting Results
8
Mantle-Crust Interaction
9
Driving Forces
Plate boundary
Assumptions (Valid?)
No interaction between tectonic blocks
2. Initially isotropic mantle
1.
10