The Nubie craton (NUB) and several small blocs were
amalgamated between 750 and 600 Ma. This event was the
first phase of the East African orogeny dated to between 750
and 600 Ma. A little further east, the convergence of the
Congo-Sao Francisco (CG-SF) and Amazon (AMZ) cratons
led to the closure of the Adamastor ocean, and their collision
around 650 Ma caused the Brazilian orogeny. This assembly
of cratons formed part of the future Gondwana continent. At
the end of Precambrian, around 550 Ma, Laurentia and
Amazonia separated, marking the opening of the Iapetus
ocean, while the cratons of Australia, Antarctica, West
Antarctica and India assembled to form another part of the
future Gondwana continent. This event is reflected in the
Kuunga and Pinjarra orogens. The closure of the ocean
separating the Kalahari and Congo-Sao Francisco cratons
leads to their collision shortly after 520 Ma, instigating the
Damara/Zambezi orogeny. This event occurred approximately synchronously with the final amalgamation of the
Gondwana continent around 530 Ma. This final stage in the
construction of the Gondwana continent brought about a
new orogenic phase in Eastern and Southern Africa (which
was superimposed on the older one dated at 600 Ma). In the
final step in the construction of Gondwana, the passive
margin that bordered the western part of this continent
became an active margin (the oceanic crust was subducted
under the Gondwana continent) over nearly 18,000 km, as
evidenced by the ages of magma activity between 550 and
500 Ma. This active margin is linked with the
Ross-Delamerian orogeny in Australia and Antarctica, the
Saldanian orogeny in Southern Africa and Pampean orogeny
in South America. The final assembly of Gondwana and the
establishment of an active margin mark the end of the orogens along the sutures of the Gondwana mosaic. It is clear
that the height of the reliefs remains very hypothetical, but
the intensity of the collisions and geological evidence suggest that the reliefs were high.
The Gondwana continent would continue to exist for
nearly 400 million years until it ended during the Cretaceous. At the beginning of the Ordovician (*480 Ma), the
Avallon plate, originally located close to the South Pole (its
remnants can be found in northeastern North America and
Western Europe), separated from Gondwana, causing the
birth of a new ocean, the Rheic Ocean (Nance et al. 2012).
The Avallon plate migrated towards the north and collided
with Baltica at the end of the Ordovician around 440 Ma. At
the end of the Silurian (*420 Ma), the collision between
Laurentia and Avalonia + Baltica completed the disappearance by subduction of the Iapetus Ocean and leads to the
Taconic orogeny in Laurentia. A new continent, Laurussia,
was formed. This collision brought about the
Caledonian/Acadian orogeny, which affected Scandinavia,
Greenland, Western Europe and the northeast part of North
America. The Rheic Ocean was gradually subducted
underneath Laurussia, inexorably bringing Laurussia and
Gondwana closer together. The closure of this ocean continued until the Devonian (*360 Ma), after which period a
generalized collision occurred along the suture between
Gondwana and Laurussia (Matte 1986). On the Laurussia
side, this resulted in the Alleghanian orogeny in North
America and the Hercynian (or Variscan) orogeny in Europe. The Alleghanian orogeny affected the eastern margin of
the North American continent (Canada and the United
States) and extended south through the state of Texas in the
United States to Mexico with the Ouachita orogeny. The
Hercynian orogeny can also be observed on the Gondwana
side through the Mauritanide orogeny in West Africa (Villeneuve 2008). The dating of deformation and metamorphism associated with this collision ranges from 340 to
270 Ma. The Hercynian orogeny affected much of western
and central Europe. This event is dated to between 340 and
290 Ma. At the end of the Carboniferous, these reliefs could
have been as high as those of the Himalayas at the present
time (Matte 1986). The amalgamation of Gondwana with
Laurussia would go on to form the Pangea supercontinent,
which would exist until 170 Ma. This supercontinent
reached its maximum size with the accretion of the
Siberian-Kazakhstan plate in response to the closure of the
Uralian ocean at the northeastern margin of Pangea during
the Permian, giving rise to the uplift of the Urals. The active
margin on the south of Gondwana experienced a new orogenic cycle that occurred between the late Carboniferous
(*310 Ma) and the Upper Triassic (*220 Ma). The
Gondwanide orogeny affected Australia, southern Africa and
southern regions of South America, already deformed by the
Ross-Delamerian, Saldanian and Pampean orogenies during
the Cambrian.
The Lower Permian marked the beginning of the separation of an assemblage of plates, called the Cimmerian
plate, from the northeastern margin of Gondwana, leading to
the opening of a new ocean, Neotethys (also known as Meso
Tethys) (Metcalfe 2002). The Cimmerian plate (southern
China, Indochina, Lhasa, Qiangtang and others) drifted
northward, closing the Paleo Tethys Ocean by subduction
under the northeastern margin of Pangea (the eastern part of
Laurussia and Kazakhstan) and under Tarim and North
China, while to the south the Neotethys Ocean continued to
open. This string of plates could have, for a while, isolated
the Paleo Tethys Ocean from the Panthalassa Ocean.
The configuration of the Pangea is full of uncertainties
(this debate is not shown in the maps of Fig. 2.6). The
Pangea reconstruction is well constrained by geological and
geophysical data for the Late Triassic-Early Jurassic at the
beginning of continental breakup. This is not the case for the
pre-Late Triassic. Bullard et al. (1965) used to rotate the two
APWPs in a common frame permit to restore the paleopositions of two landmasses during these periods. Doing that, it
2 The Changing Face of the Earth Throughout the Ages
43
amalgamated between 750 and 600 Ma. This event was the
first phase of the East African orogeny dated to between 750
and 600 Ma. A little further east, the convergence of the
Congo-Sao Francisco (CG-SF) and Amazon (AMZ) cratons
led to the closure of the Adamastor ocean, and their collision
around 650 Ma caused the Brazilian orogeny. This assembly
of cratons formed part of the future Gondwana continent. At
the end of Precambrian, around 550 Ma, Laurentia and
Amazonia separated, marking the opening of the Iapetus
ocean, while the cratons of Australia, Antarctica, West
Antarctica and India assembled to form another part of the
future Gondwana continent. This event is reflected in the
Kuunga and Pinjarra orogens. The closure of the ocean
separating the Kalahari and Congo-Sao Francisco cratons
leads to their collision shortly after 520 Ma, instigating the
Damara/Zambezi orogeny. This event occurred approximately synchronously with the final amalgamation of the
Gondwana continent around 530 Ma. This final stage in the
construction of the Gondwana continent brought about a
new orogenic phase in Eastern and Southern Africa (which
was superimposed on the older one dated at 600 Ma). In the
final step in the construction of Gondwana, the passive
margin that bordered the western part of this continent
became an active margin (the oceanic crust was subducted
under the Gondwana continent) over nearly 18,000 km, as
evidenced by the ages of magma activity between 550 and
500 Ma. This active margin is linked with the
Ross-Delamerian orogeny in Australia and Antarctica, the
Saldanian orogeny in Southern Africa and Pampean orogeny
in South America. The final assembly of Gondwana and the
establishment of an active margin mark the end of the orogens along the sutures of the Gondwana mosaic. It is clear
that the height of the reliefs remains very hypothetical, but
the intensity of the collisions and geological evidence suggest that the reliefs were high.
The Gondwana continent would continue to exist for
nearly 400 million years until it ended during the Cretaceous. At the beginning of the Ordovician (*480 Ma), the
Avallon plate, originally located close to the South Pole (its
remnants can be found in northeastern North America and
Western Europe), separated from Gondwana, causing the
birth of a new ocean, the Rheic Ocean (Nance et al. 2012).
The Avallon plate migrated towards the north and collided
with Baltica at the end of the Ordovician around 440 Ma. At
the end of the Silurian (*420 Ma), the collision between
Laurentia and Avalonia + Baltica completed the disappearance by subduction of the Iapetus Ocean and leads to the
Taconic orogeny in Laurentia. A new continent, Laurussia,
was formed. This collision brought about the
Caledonian/Acadian orogeny, which affected Scandinavia,
Greenland, Western Europe and the northeast part of North
America. The Rheic Ocean was gradually subducted
underneath Laurussia, inexorably bringing Laurussia and
Gondwana closer together. The closure of this ocean continued until the Devonian (*360 Ma), after which period a
generalized collision occurred along the suture between
Gondwana and Laurussia (Matte 1986). On the Laurussia
side, this resulted in the Alleghanian orogeny in North
America and the Hercynian (or Variscan) orogeny in Europe. The Alleghanian orogeny affected the eastern margin of
the North American continent (Canada and the United
States) and extended south through the state of Texas in the
United States to Mexico with the Ouachita orogeny. The
Hercynian orogeny can also be observed on the Gondwana
side through the Mauritanide orogeny in West Africa (Villeneuve 2008). The dating of deformation and metamorphism associated with this collision ranges from 340 to
270 Ma. The Hercynian orogeny affected much of western
and central Europe. This event is dated to between 340 and
290 Ma. At the end of the Carboniferous, these reliefs could
have been as high as those of the Himalayas at the present
time (Matte 1986). The amalgamation of Gondwana with
Laurussia would go on to form the Pangea supercontinent,
which would exist until 170 Ma. This supercontinent
reached its maximum size with the accretion of the
Siberian-Kazakhstan plate in response to the closure of the
Uralian ocean at the northeastern margin of Pangea during
the Permian, giving rise to the uplift of the Urals. The active
margin on the south of Gondwana experienced a new orogenic cycle that occurred between the late Carboniferous
(*310 Ma) and the Upper Triassic (*220 Ma). The
Gondwanide orogeny affected Australia, southern Africa and
southern regions of South America, already deformed by the
Ross-Delamerian, Saldanian and Pampean orogenies during
the Cambrian.
The Lower Permian marked the beginning of the separation of an assemblage of plates, called the Cimmerian
plate, from the northeastern margin of Gondwana, leading to
the opening of a new ocean, Neotethys (also known as Meso
Tethys) (Metcalfe 2002). The Cimmerian plate (southern
China, Indochina, Lhasa, Qiangtang and others) drifted
northward, closing the Paleo Tethys Ocean by subduction
under the northeastern margin of Pangea (the eastern part of
Laurussia and Kazakhstan) and under Tarim and North
China, while to the south the Neotethys Ocean continued to
open. This string of plates could have, for a while, isolated
the Paleo Tethys Ocean from the Panthalassa Ocean.
The configuration of the Pangea is full of uncertainties
(this debate is not shown in the maps of Fig. 2.6). The
Pangea reconstruction is well constrained by geological and
geophysical data for the Late Triassic-Early Jurassic at the
beginning of continental breakup. This is not the case for the
pre-Late Triassic. Bullard et al. (1965) used to rotate the two
APWPs in a common frame permit to restore the paleopositions of two landmasses during these periods. Doing that, it
2 The Changing Face of the Earth Throughout the Ages
43