Tectonic significance of fault-slip data

Research areas:
Year:
2000
Authors:
Journal:
JOURNAL OF STRUCTURAL GEOLOGY
Volume:
22
Number:
7
Pages:
881-888
Month:
July
ISSN:
0191-8141
BibTex:
Abstract:
The statistical analysis of populations of minor faults is commonly used
by structural geologists working in areas of brittle rock. It is based
on measurements of fault attitude, direction and sense of slip. At
individual sampling localities, results are classically interpreted as
indicators of stress or strain rate fields, assuming a homogeneous
stress or strain rate tensor, respectively. However, fault patterns are
expected to vary with time because of displacements, rigid rotations,
and internal strains, which generally occur along boundaries of
fault-bounded blocks as deformation proceeds. Thus, in the general
situation where early faults accumulate displacements and rigid
rotations, and where new faults develop during progressive deformation,
fault-slip data can be rather complex and variable in space, and reflect
neither local stress or strain rate tensors, nor finite strains and
finite rotations in a simple way.
We use two examples of faulted regions to illustrate the spatial
variability of fault-slip data. This can be due to local complications
at the edges of fault blocks, or to complex kinematic conditions at
regional boundaries. Such complications may make it difficult to deduce
a consistent and simple pattern of either stresses or strain rates.
Instead, our results suggest that information contained in fault-slip
data can be pertinent to finite deformation. In particular, the
principal axes that we have deduced from the analysis of fault-slip data
are consistent with the finite displacements at block boundaries that we
have calculated by numerical restoration. (C) 2000 Elsevier Science Ltd.
All rights reserved.