Ediacaran–Cambrian basin evolution in the Koonenberry Belt (eastern Australia): Implications for the geodynamics of the Delamerian Orogen
Johnson, Emma L., Phillips, Glen, & Allen, Charlotte M. (2016) Ediacaran–Cambrian basin evolution in the Koonenberry Belt (eastern Australia): Implications for the geodynamics of the Delamerian Orogen. Gondwana Research, 37, pp. 266-284.
Contention surrounds the Ediacaran–Cambrian geodynamic evolution of the palaeo-Pacific margin of Gondwana as it underwent a transition from passive to active margin tectonics. In Australia, disagreement stems from conflicting geodynamic models for the Delamerian Orogen, which differ in the polarity of subduction and the state of the subduction hinge (i.e., stationary or retreating). This study tests competing models of the Delamerian Orogen through reconstructing Ediacaran–Cambrian basin evolution in the Koonenberry Belt, Australia. Thiswas done through characterising the mineral and U–Pb detrital zircon age provenance of sediments deposited during postulated passive and active margin stages. Based on these data,we present a newbasin evolution model for the Koonenberry Belt, which also impacts palaeogeographic models of Australia and East Gondwana. Our basin evolution and palaeogeographic model is composed of four main stages, namely:
(i) Ediacaran passive margin stage with sediments derived from the Musgrave Province;
(ii) Middle Cambrian (517–500 Ma) convergent margin stage with sediments derived from collisional orogens in central Gondwana (i.e., the Maud Belt of East Antarctica) and deposited in a backarc setting;
(iii) crustal shortening during the c. 500 Ma Delamerian Orogeny, and;
(iv) Middle to Late Cambrian–Ordovician stage with sediments sourced from the local basement and 520–490Ma igneous rocks and deposited into post-orogenic pull-apart basins.
Based on this newbasin evolution model we propose a new geodynamic model for the Cambrian evolution of the Koonenberry Belt where:
(i) the initiation of a west-dipping subduction zone at c. 517 Mawas associated with incipient calc-alkaline magmatism (Mount Wright Volcanics) and deposition of the Teltawongee and Ponto groups;
(ii) immediate east-directed retreat of the subduction zone positioned the Koonenberry Belt in a backarc basin setting (517 to 500 Ma), which became a depocentre for continued deposition of the Teltawongee and Ponto groups;
(iii) inversion of the backarc basin during the c. 500 Delamerian Orogeny was driven by increased upper and low plate coupling caused by the arrival of a lower plate asperity to the subduction hinge, and;
(iv) subduction of the asperity resulted in renewed rollback and upper plate extension, leading to the development of small, post-orogenic pull-apart basins that received locally derived detritus.
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|Item Type:||Journal Article|
|Keywords:||Koonenberry Blet, Delamerian, Tasmanides, U-Pb detrital zircon geochronology, geodynamics, Sedimentary petrography|
|Divisions:||Current > Schools > School of Earth, Environmental & Biological Sciences
Current > Institutes > Institute for Future Environments
Current > QUT Faculties and Divisions > Science & Engineering Faculty
|Facilities:||Central Analytical Research Facility|
|Copyright Owner:||Copyright 2016 Elsevier|
|Deposited On:||07 Aug 2016 23:20|
|Last Modified:||08 Aug 2016 22:50|
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