Book contents
- Frontmatter
- Contents
- Colophon
- Preface
- Acknowledgements
- Maps
- Units of measurement and abbreviations
- 1 Geology: An Australian perspective
- 2 The Earth: A geology primer
- 3 Telling geological time: The great canvas
- 4 The cratons: Building the core of Precambrian rocks
- 5 Mountain building: Paleozoic orogenic rock systems
- 6 Warm times: Tropical corals and arid lands
- 7 Icehouse: Carboniferous and Permian glaciation
- 8 Mesozoic warming: The great inland plains and seas
- 9 The birth of modern Australia: Flowering plants, mammals and deserts
- 10 Fossils: The Australian record of past life in context
- 11 The land stirs: Volcanoes and the eastern highlands
- 12 The outline and submerged terrace: Building the continental shelf and coastlines
- 13 The coral reefs: Unique parts of the continental shelf
- 14 Patterns of change: Cycles in Australia's journey
- Epilogue
- Sources and references
- Index
- References
5 - Mountain building: Paleozoic orogenic rock systems
- Frontmatter
- Contents
- Colophon
- Preface
- Acknowledgements
- Maps
- Units of measurement and abbreviations
- 1 Geology: An Australian perspective
- 2 The Earth: A geology primer
- 3 Telling geological time: The great canvas
- 4 The cratons: Building the core of Precambrian rocks
- 5 Mountain building: Paleozoic orogenic rock systems
- 6 Warm times: Tropical corals and arid lands
- 7 Icehouse: Carboniferous and Permian glaciation
- 8 Mesozoic warming: The great inland plains and seas
- 9 The birth of modern Australia: Flowering plants, mammals and deserts
- 10 Fossils: The Australian record of past life in context
- 11 The land stirs: Volcanoes and the eastern highlands
- 12 The outline and submerged terrace: Building the continental shelf and coastlines
- 13 The coral reefs: Unique parts of the continental shelf
- 14 Patterns of change: Cycles in Australia's journey
- Epilogue
- Sources and references
- Index
- References
Summary
Through the Paleozoic a convergent plate boundary was located adjacent to what is now eastern Australia. Dynamics of this boundary shaped and substantially added to the crust of eastern Australia. It was the site of mighty fold-and-thrust mountain ranges formed by crustal compression and seamed with a succession of continental magmatic arcs and associated explosive volcanism. The contrast between the Paleozoic and the present-day aspects of eastern Australia is profound.
ASSEMBLY OF THE GONDWANA SUPERCONTINENT
The Precambrian core of Australia provided the foundation of the continent and a frame of reference for later crustal addition, including the widespread development of sedimentary basins that formed on top of the Precambrian craton. At the close of the Precambrian, Australia was part of an extensive continental configuration, the supercontinent Gondwana, in which Africa, South America, India and Antarctica were also united (see Figure 5.1) Following the breakup of the earlier supercontinent Rodinia, amalgamation of continental fragments to form Gondwana progressed through the late Precambrian and continued into the early Paleozoic (650–500 Ma). Australia through this interval of time was already united with Antarctica and India and was little affected by collisional sutures which developed as a consequence of the amalgamation process and which characterise the geology of eastern Africa, in particular, and are also clearly evident in Madagascar and Antarctica.
By the time Gondwana came into existence the Paleo-Pacific Ocean had long been formed as a consequence of the Rodinian breakup. This ocean developed when eastern Australia separated from Laurentia. During the Cambrian, the Paleo-Pacific Ocean began to close, through subduction, along the entire ocean-facing edge of Gondwana. For Australia, the consequences of subduction along its eastern margin became clearly evident in the late Cambrian and persisted through the remainder of the Paleozoic, an interval of at least 250 Ma. As expected of subducting plate boundaries, large volumes of igneous rocks were generated throughout that interval.
OROGENIC PROCESSES AND PATTERNS
The details of the plate dynamics that affected eastern Australia through the Paleozoic are complex. There were times when the Paleo-Pacific plate boundary adjacent to eastern Australian continental crust retreated oceanwards (roll back) and the continental borderland stretched. Back arc basins, to be infilled with sediment and volcanics, developed as a consequence.
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- The Geology of Australia , pp. 109 - 130Publisher: Cambridge University PressPrint publication year: 2016