Skip to Main Content
Book Chapter

Magnetic fabric constraints on oroclinal bending of the Texas and Coffs Harbour blocks: New England Orogen, eastern Australia

By
Charles Aubourg
Charles Aubourg
1
Laboratoire de Tectonique, UMR 7072, Université de Cergy-Pontoise, 8 Avenue du Parc, Le Campus, Bât I, 95031 Cergy Cedex, France e-mail: charly.aubourg@geol.u-cergy.fr
Search for other works by this author on:
Chris Klootwijk
Chris Klootwijk
2
Department of Earth and Marine Sciences, Australian National University, Canberra ACT 0200, Australia
Search for other works by this author on:
Russell J. Korsch
Russell J. Korsch
3
Australian Geodynamics Cooperative Research Centre, Geoscience Australia, GPO Box 378, Canberra ACT 2601, Australia
Search for other works by this author on:
Published:
January 01, 2004

Abstract

We have carried out a magnetic fabric study on deformed, clay-rich rocks from the Carboniferous Texas beds and Coffs Harbour Association in order to test the hypothesis of oroclinal bending of the Texas and Coffs Harbour blocks of the southern New England Orogen, eastern Australia. The magnetic susceptibility is dominated by paramagnetic phyllosilicates, with site-dependent contributions from the ferromagnetic minerals pyrrhotite, magnetite and hematite. Pyrrhotite is ubiquitous in the Texas block and in the central part of the Coffs Harbour block, and may be important as an indicator of the grade of low-temperature metamorphism. The magnetic fabric results, in general, show good agreement with structural observations in the Texas and Coffs Harbour blocks. The magnetic foliation is related to the pervasive cleavage associated with accretionary deformation prior to oroclinal bending. The magnitudes of the anisotropy parameters and the plunge of the magnetic lineation indicate an increase in the intensity of deformation from east of the Coffs Harbour orocline towards the Texas orocline. An imprint from oroclinal deformation is suggested by a significant increase in the anisotropy parameter and by the development of steeply plunging magnetic lineations towards the hinges of the Texas and Coffs Harbour oroclines. The Terrica beds from the Early Permian (Allandale) Terrica inlier in the Texas orocline also show another, pre-tilt induced, tectonic imprint. Remanence data from volcanics in the Alum Rock inlier (293 Ma) and magnetic fabric data from this inlier tentatively constrain the onset of oroclinal bending as prior to extrusion of the Alum Rocks, and the completion of bending as post-Terrica beds deposition and pre-Illawarra Reversal (est. 265 Ma).

You do not currently have access to this article.

Figures & Tables

Contents

Geological Society, London, Special Publications

Magnetic Fabric: Methods and Applications

F. Martín-Hernández
F. Martín-Hernández
Faculty of Geosciences, Utrecht University, The Netherlands
Search for other works by this author on:
C. M. Lüneburg
C. M. Lüneburg
Department of Geology and Geophysics, University of New Orleans, USA
Search for other works by this author on:
C. Aubourg
C. Aubourg
Laboratoire de Tectonique, Université de Cergy-Pontoise, France
Search for other works by this author on:
M. Jackson
M. Jackson
Institute for Rock Magnetism, University of Minnesota, USA
Search for other works by this author on:
Geological Society of London
Volume
238
ISBN electronic:
9781862394865
Publication date:
January 01, 2004

GeoRef

References

Related

Citing Books via

Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal