Geology Reference
In-Depth Information
11.5.2
Domino-Block Predictive Model
Dominoes are formed by parallel planar faults for which both bedding and the faults
rotate (Fig. 11.24). Found typically in extensional and wrench regimes, the amount of
rotation may be large, 30° to 60° or more. Such large rotations by other models require
very large internal strains and seem not to be favored. This was one of the first kine-
matic models to be quantified (Thompson 1960; Morton and Black 1975). As the blocks
extend, they rotate. Following the approach of Wernicke and Burchfiel (1982), the re-
lationship between the extension and the geometry is
e
=[sin(
φ
+
δ
)/sin
φ
] - 1 ,
(11.37)
where
φ
= the final dip of the fault,
δ
= the final dip of bedding. The initial dip of the
fault is
φ
0
=
φ
+
δ
allowing Eq. 11.37 to be rewritten as
e
=[sin
φ
0
/sin(
φ
0
-
δ
)] - 1 .
(11.38)
The slip on the fault depends on the width of the fault block, the wider the block, the
greater the slip on each block. The fault slip is (Axen 1988)
S
r
=
L
0
sin
δ
/sin
φ
,
(11.39)
where
S
r
= rotational fault slip and
L
0
= the original horizontal distance between two
adjacent faults. The rotational slip is calculated using the
L
0
value of the hangingwall
block.
The correct frame of reference for calculating domino block strain is the median
line through the blocks or, equivalently, the enveloping surfaces that touch the corners
Fig. 11.24.
Domino kinematics and strain (after Axen 1988).
L
0
:
The original horizontal distance be-
tween two adjacent faults;
L
1
:
final horizontal distance between two adjacent faults;
φ
0
:
initial dip of the
fault;
φ
:
final dip of the fault;
δ
:
final dip of bedding;
S
f
:
slip on fault.
a
Before extension.
b
After exten-
sion.
c
Relationship among variables
