The Australian Geologist - Geological Society of Australia

Book Reviews
High-Strain Zones: structure
and physical properties
D Bruhn and L Burlini (Eds)
2005
Geological Society of London
Special Publication 245
Pages ISBN
£95
www.geolsoc.org.uk
This book contains several paper presented at
a special session on High Strain Zones at the
EGS–AGU–EUG meeting in 2003 in Nice,
France. It starts with an excellent review of
strain softening mechanisms identified over
20 years ago and considers these in the light
of more recent results arising from the application
of new novel laboratory deformation
techniques such as high strain in torsion
experiments. It is clear from my own field
studies that the Earth’s lithosphere is
deformed by localised, narrow high strain
zones on a range of scales from regional to
outcrop. Recent studies by myself and my
excellent honours students reveal parts of
the Wyangala Granite are transected by discontinuous
high strain zones of hundreds of
metres width and kilometres length often
near lithological (and hence rheologically
important) boundaries. The localization of
deformation in high strain zones appears to
be a universal property of rocks.
This volume consists of 22 well-edited
papers, which are clearly illustrated and
beautifully bound to the very high standard.
The papers can be divided into six main
groups, although there is some overlap. In
the first group there are six papers on field
studies of high strain zone (HSZ) including
the relationship between deformation and
metamorphism. In the second group there
are five papers on the physical properties of
HSZ in the field and laboratory. In the third
group there are five papers on the rheology
of HSZ and in the fourth group two papers
on the interaction of deformation and metamorphism.
In the fifth group there are two
papers on phenomena related to HSZ in rocks
and in the final group there are two papers
on numerical modeling applied to HSZ.
The inclusion of a comprehensive index at
the rear is a good. I will briefly comment on
some of the papers I found most enlightening
given my current research interests.
Sidman et al demonstrate the use of the
AMS method as a robust indicator of fabric
over a wide range of deformation conditions
using the Bitterroot shear zone, Western
Montana. They advocate the rolling-hinge
model for exhumation of the Bitterroot core
complex, which is in fact a magma-dominated
core complex. J-P Burg et al document
shear zones in the middle crust-upper mantle
of the Kohistan palaeo-island arc. They show
that shear strain localisation began within
compositional gradients and that anastomosing
patterns of shear zones develop in
gabbros more commonly than diorites and
granites. Their sketches of anastomosing
ductile shear zones resemble those we’ve
observed in the Wyangala Batholith.
Teyessier et al use a range of datasets to
suggest the Cordilleran orogen collapsed
through the development of channel and
rolling-hinge detachments. They use the Rey
et al (2001) gravitational collapse model
for continental crust to critically test the
tectonic development of the Shuswap MCC.
Passchier et al document a different
deformation in a gently dipping, ductile
shear zone over a core complex from China.
They suggest simple shear in the top of
the shear zone and non-coaxial flow with
volume increase and stretching by vein
intrusion towards the footwall, which they
call an ‘expanding-footwall shear zone.’
High strain deformation tests on natural
gympsum aggregates in torsion by Barberini
et al suggest that gypsum in nature will flow
plastically at shear stress levels lower than
those expected from previous studies. This is
due to dynamic recrystallisation at temperatures
lower than that which causes gypsum
dehydration.
This compilation of papers is of a universally
good standard and clearly aimed at structural,
tectonic and metamorphic geologists
within academia. The price will deter some
from purchasing this volume despite the
currency of the papers.
PAUL LENNOX
Regolith Landscape
Evolution across Australia:
a compilation of regolith
landscape case studies with
regolith landscape evolution
models
Anand R R & de Broekert P (eds)
2005
CRC LEME
354 pages ISBN 1 921039 30 2
$30
www.crcleme.com.au
and
Regolith Expression of
Australian Ore Systems:
a compilation of exploration
case histories with
conceptual dispersion,
process and exploration
models
Butt C R M, Robertson I D M, Scott K M &
Cornelius M (Eds)
2005
CRC LEME
420 pages ISBN 1 921039 28 0
$30
www.crcleme.com.au
The editors of these two volumes and their
many contributors have done anyone with
even a passing interest in the Australian
regolith a great favour in bringing together a
large number of case studies of regolith
development both as a characteristic of the
regions and as it relates to the occurrence of
ore bodies around the continent. The volumes
are greatly enriched by introductory review
chapters on the science and applications of
the regolith.
The reviews are of Australian regolith and
landscape patterns (Anand, reproduced in
both volumes); regolith age determination
(Pillans) and regolith-landform mapping
(Craig) in Anand & de Broekert; ore deposit
types (McQueen), sampling media (Butt et al)
and geochemical dispersion (Butt) in Butt et
al; and, very briefly, Australian climate (Butt)
and vegetation (Butt) patterns (both
volumes). The longer chapters are excellent
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