The structural evolution of the Northern Hastings Block and southern Nambucca Block,southern New England Orogen,eastern Australia |
| |
| Authors: | J Yan P G Lennox R Offler |
| |
| Institution: | 1. School of Biological, Earth and Environmental Sciences, The University of New South Wales , Sydney, NSW 2052, Australia;2. School of Earth Sciences, East China University of Technology , Nanchang, Jiangxi 330013, PR China;3. School of Biological, Earth and Environmental Sciences, The University of New South Wales , Sydney, NSW 2052, Australia;4. New South Wales Institute of Frontiers Geosciences, University of Newcastle , Newcastle, NSW 2308, Australia |
| |
| Abstract: | The Hastings Block is a weakly cleaved and complexly folded and faulted terrain made up of Devonian, Carboniferous and Permian sedimentary and volcanic rocks. The map pattern of bedding suggests a major boundary exists that divides the Hastings Block into northern and southern parts. Bedding north of this boundary defines an upright box-like Parrabel Anticline that plunges gently northwest. Four cleavage/fold populations are recognised namely: E–W-striking, steeply dipping cleavage S1 that is axial surface to gently to moderately E- or W-plunging; F1 folds that were re-oriented during the formation of the Parrabel Anticline with less common N–S-trending, steeply dipping cleavage S2, axial surface to gently to moderately N-plunging F2 folds; poorly developed NW–SE-striking, steeply dipping cleavage S3 axial surface to mesoscopic, mainly NW-plunging F3 folds; and finally, a weakly developed NE–SW-striking, steeply dipping S4 cleavage formed axial surface to mainly NE-plunging F4. The Parrabel Anticline is considered to have formed during the D3 deformation. The more intense development of S2 and S3 on the western margin of the Northern Hastings Block reflects increasing strain related to major shortening of the sequences adjacent to the Tablelands Complex during the Hunter–Bowen Orogeny. The pattern of multiple deformation we have recorded is inconsistent with previous suggestions that the Hastings Block is part of an S-shaped orocline folded about near vertically plunging axes. |
| |
| Keywords: | Northern Hastings Block ductile deformation folds cleavages structural history Nambucca Block oroclines |
|
|
