AUSTRALIA
The Australian continent has large areas of ancient crusts preserved throughout what is now Central, Northern, and Western Australia. The rest of present-day Australia is made up of relatively young sedimentary rocks which were originally linked to similar sedimentary basins now located in China and North and South America. The older parts of the Australian continent had their beginnings as part of the primordial Archaean supercontinental crustal assemblage. This ancient assemblage later extended in surface area as new sedimentary basins opened and extended around its margins.
The continental crustal development of Australia on an Expansion Tectonic Earth. The outline of the pre-Jurassic Australian crust is shown as a black line. During the Precambrian to late-Palaeozoic times Australia was orientated north-south prior to rotating counter clockwise to the present east-west orientation. This occurred during opening of the modern Pacific Ocean. The horizontal red line represents the location of the ancient equator.
Throughout the various Precambrian and Palaeozoic Eras most of ancient Australia was located in the northern hemisphere and the long axis of the primitive Australian continent was orientated north-south relative to the ancient equator. Once the ancient Pangaea supercontinent started to breakup and the modern Pacific Ocean commenced opening during the Mesozoic Era, the newly formed Australian continent then rotated counter clockwise to its present east-west orientation and migrated south into its present location in the southern hemisphere.
During these ancient times the Australian crusts abutted directly against crusts from primitive China to the north, Canada and North America to the east, South America to the south, and East Antarctica to the west. At that time ancient Australia was located within mid- to high-northern latitudes relative to the ancient equator and the ancient equator passed through what is now Central and Northern Australia.
During this pre-breakup supercontinent time the ancient sedimentary basins of Northern and Central Australia formed part of an extensive global network of sedimentary basins. These basins extended north into the Proterozoic basins of Alaska, Canada, Northern Russia, and Asia, and to the east and south these basins were also linked to the Proterozoic basins of North America, Central America, and South America. Deposition of sediments within these ancient Australian sedimentary basins was most active to the south—within what is now Eastern Australia—and this deposition extended into adjoining regions in primitive New Zealand, South America, North America, and Antarctica. Breakup of this extensive sedimentary basin occurred during Permian times during initial opening of the South Pacific Ocean. Remnants of this basin are now preserved in East Australia, New Zealand, Central and South America, North America, and Antarctica
Crustal movement during this time was accompanied by ancient mountain building events, mainly within the network of sedimentary basins in what is now Central and Eastern Australia. Remnants of these mountain building events are also preserved as the Andean mountain events of South America, the Appalachian and Grenville Mountain events of Eastern North America, and the Cordilleran mountain event of Western North America and Canada. Events in Central and Northern Australia were also associated with periods of crustal movement and jostling of the various ancient crusts located between Australia and North America. This jostling occurred as each of the ancient crusts adjusted for changing surface curvature.
Continental crustal rupture to form the modern Australian continent first commenced during early-Permian times in areas located to the northeast of Australia, relative to the ancient equator, adjacent to what is now the Pilbara and Kimberley regions of Western Australia. Opening also occurred in the south, adjacent to Eastern Australia, separating Australia from New Zealand. The outline of the modern Australian continent then began to take shape in these areas once the North and South Pacific and similarly the Indian Ocean began to open.
After slowly opening during the Permian and Triassic Periods, the early North and South Pacific Oceans then started to rapidly open, separating Australia from North and South America, while initially retaining a brief land link between Queensland in East Australia and California in North America. These previously separate North and South Pacific Oceans merged during the Jurassic Period, finally separating Australia and New Zealand from North and South America.
Similarly, the Indian Ocean commenced opening during the Jurassic Period and was located adjacent to what is now Northwest Australia. As a result, Australia separated from China and South East Asia as the Indian Ocean continued to open and extend southwards along the west coast of Western Australia. At that time lands connecting Australia with adjoining continents remained attached to South East Asia to the north and East Antarctica to the south allowing plant and animal species migration between each of these continents.
Rifting between Australia and East Antarctica commenced during the Paleocene—about 66 million years ago—during opening of the Southern Ocean. Australia and Antarctica are continuing to drift apart to the present-day leaving both continents as separate island continents. During this rifting event, Australia migrated south from mid-northern latitudes crossing the ancient equator into its present-day mid-southern latitude location. Bear in mind that migration is apparent and it is the opening of the oceans that causes this apparent migration.
Rocks exposed throughout Australia now reflect this geographic migration history, with extensive coral reef deposits located along the full length of Eastern Australia reflecting its original equatorial location throughout the Palaeozoic Era. This was followed by a prolonged period of tropical weathering as Australia rotated and crossed the equator, which is marked by extensive deposits of laterite rocks—rocks that have undergone deep chemical weathering from tropical rains—throughout present-day West and Northeast Australia. This was then followed by a progressive drying and desertification of the landscape to the present-day as Australia continued to migrate south away from the equator. Once the Southern Ocean began to open, Australia then remained geographically isolated from its neighbouring continents and has continued to progressively migrate further south into low- and mid-southern latitudes.
This southern migration of Australia is at odds with plate tectonic studies where it is insisted that Australia is migrating north, out of more temperate to polar climate zones, to collide with South East Asia. This interpretation is based primarily on palaeomagnetic apparent-polar-wander studies and this interpretation is in fact contrary to what the rock-record shows. Irrespective of what plate tectonics insists, coral reef deposits and tropical weathering simply cannot occur in high polar latitudes; they are diagnostic of equatorial latitudes.
