Venue: Kalbarri, Western Australia
Travel report by Caroline Forbes
The 2003 conference for the Specialist Group in Tectonics and Structural Geology (SGTSG) was held in Kalbarri, Western Australia from 22 to 26 September. The conference focused on advances in the areas of structural geology and tectonics, and was attended by 100-150 Australian and overseas delegates from industry and academia. Attending and presenting at the SGTSG is highly beneficial for postgraduate students wishing to pursue the field of structural geology and tectonics as it is a small, relaxed and very social conference. This creates an environment that presents a fantastic opportunity to display your own skills to your peers, learn what other institutions are researching, create firm contacts within industry and academia, and also meet other postgraduate students interested in similar field(s) of geology.
I gave an oral presentation titled ‘Early high-temperature shear zones in the Broken Hill Block, NSW’ in the session ‘Making and remaking the Australian continent’. This presentation was co-authored by Dr Pete Betts and Professor Gordon Lister, and was a report on field mapping followed by structural and geometrical analysis of the Allendale Mine Area, located in the northern Palaeoproterozoic Broken Hill Block, NSW. A major result of this work has been the identification of a north-south-trending high-strain zone (shear zone) active during the earliest stages of the ca 1.60-1.58 Ga Olarian Orogeny. The shear zone bounds two structural domains (the eastern and western domains) characterised by differing structural geometries. Type 2 ‘mushroom’ fold interference patterns resultant from overprinting of F2 non-cylindrical recumbent by F3 upright fold generations are preserved to the west of the shear zone (western domain). Conversely, to the east of the shear zone (eastern domain), F2 recumbent folds are not developed, and F3 upright folds dominate the structural geometry. From these observations, the shear zone has been interpreted to be a local detachment over which lateral transportation of hanging wall rocks (the western domain) occurred, producing non-cylindrical F2 recumbent folds. The recumbent folds did not develop in the detachment footwall (the eastern domain). Subsequent deformation resulted in the development of upright F3 folds that are preserved in both the hanging wall and footwall of the early detachment. This resulted in the development of different structural geometries and strain partitioning across the Allendale Mine Area.