Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4727925 | Gondwana Research | 2009 | 13 Pages |
Abstract
A newly identified northwest-southeast oriented, deeply-rooted, steep to vertical, large-scale structural system within the Proterozoic Curnamona Province, Australia, which we term the “Benagerie Shear Zone”, is imaged in regional magnetic and gravity datasets. In this study, we use a combination of field analysis and quantitative geophysical methods, to establish a 1100Â Myr history of activity along the Benagerie Shear Zone during which the location of younger geological structures are influenced by the pre-existing shear zone. This deformational system is interpreted to have 1) aided ascent and emplacement of the ca. 1600Â Ma Ninnerie (magmatic) Supersuite; 2) controlled the loci of nucleation of normal faults during rifting and continental breakup at ca. 800Â Ma; and 3) influenced the development of fold structures as well as acting as a plane co-linear to the rotation axis of pre-existing normal faults such that they were steepened and reactivated as strike slip structures during the ca. 500Â Ma Delamerian Orogeny. We interpret that the Benagerie Shear Zone has not undergone uni-directional propagation during its evolution but rather through reactivation was a primary influence on controlling the nucleation of Neoproterozoic rift faults, thereby playing a major role in accommodating strain over a significant period of the evolution of the Curnamona Province. This study demonstrates that crustal-scale shear zones can evolve over hundreds of millions of years, have strike-lengths of hundreds to thousands of kilometers, and have vastly different surface expressions along strike.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Geology
Authors
H.A. Williams, P.G. Betts,