Teaching Earth Sciences - Earth Science Teachers' Association

The formation of Gondwana (and Laurussia) [750 to
500Ma]
During the period 750 to 500Ma plate tectonic forces
caused the ancient cratonic areas of South America and
Africa to collide with what was left of Rodinia (which by
now had been locked together for at least 600Ma – a time
span longer than the Phanerozoic). This collision formed a
new super-continent, called Gondwana made up of South
Africa, and South America in the west, and Australia,
India and Antarctica in the east (Figure 4). This huge
continent, and the evidence contained in its late Paleozoic
and Mesozoic rocks, occupies a special place in the
development of the Continental Drift/Plate Tectonics story.
Figure 2 Sketch map of the main structural elements of Australia (adapted from
Johnson and Lane). Cratons: P = Pilbara; Y = Yilgarn; G = Gawler. Amadeus,
Musgrave and Capricorn are examples of Precambrian basins and fold belts.
The Tasman Line divides Precambrian from Post Precambrian Australia.
with a roughly WNW – ESE strike (Figure 2). The Gawler
craton collided towards the end of this period, completing
the main scaffolding of Australia’s continental core as we
now know it. Just a couple of millennia later this nucleus
had been expanded by further collisions to form a supercontinent
called Rodinia.
The formation of Rodinia. [1300 to 750Ma]
When re-assembled, Rodinia comprises the Australian
cratons, most of Antarctica, India and Laurentia (which
is currently, of course, in the northern hemisphere).
Fragmentary evidence also suggests that the African
cratons of Congo, Kalahari and West Africa, plus the
Amazonian craton of South America, and possibly
fragments of China were also close by. Igneous rocks
related to these collisions have been dated at 1300 to
1100Ma.
The break-up of this supercontinent left only the India-
Australia-Antarctica ‘remnants’ of Rodinia locked together.
This fragmentation is signaled in the geological record by
basic intrusions and volcanics in places that are now as far
apart as Australia, India, Madagascar and North America.
These events have recently given radiometric dates between
830 and 795Ma indicating a significant period of basic
magmatism related to this period of continental rifting.
Meanwhile, in the northern hemisphere, other fragments
of continental crust were beginning to come together to
form a second super-continent called Laurussia. During
the Carboniferous and Permian periods this northern
super-continent, collided with the northwestern edge
of Gondwana, forming a single slab of continental crust
containing almost all of the known continental fragments
of the time. This really enormous slab of crust is called
Pangaea (Figure 5).
The formation of Pangaea [350 to 225Ma]
Such a large piece of continental crust was not able to
remain together for more than a few million years before
rifting caused fragmentation about 240Ma. Plate tectonic
forces caused the fragments to disperse around the globe
– no doubt only to collide again at some future point on
Figure 4 Gondwana at 180 Ma (adapted from Johnson). An = Antarctica;
Au = Australia; In = India; Af = Africa; Sa = South America
Figure 3 Rodinia at around 750Ma,
soon after its breakup (adapted
from Johnson). An = Antarctica;
Au = Australia; Ba = Baltica; In =
India; La = Laurentia; Si = Siberia;
TL = Tasman Line. (At this time the
Antarctic peninsular was not in its
present position, nor was the eastern
seaboard of Australia. The precise
form and extent of the northern
Indian crust is unclear, and is now
buried below the Himalaya.)
Figure 5 Pangaea around 200 Ma (loosely adapted from the uwgb website).
An = Antarctica; Au = Australia; In = India; Af = Africa; Sa = South America
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