Rifting and break-up of Pangaea
[/align]Pangaea separation animation[/align][/align][/align]There were three major phases in the break-up of Pangaea. The first phase began in the
Early-
Middle Jurassic, when Pangaea created a rift from the
Tethys Ocean from the east and the
Pacific from the west. The rifting took place between North America and Africa, the rift produced multiple failed rifts,
Mississippi River being the largest. The rift resulted in a new
ocean, the
Atlantic Ocean.
The Atlantic Ocean did not open uniformly; rifting began in the North-Central Atlantic. The
South Atlantic did not open until the
Cretaceous.
Laurasia started to rotate clockwise and moved northward with
North America to the north, and
Eurasia to the south. The clockwise motion of Laurasia also lead to the closing of the Tethys Ocean. Meanwhile, in the other side of
Africa, new rifts were also forming along the adjacent margins of east Africa,
Antarctica, and
Madagascar that would lead to the formation of the Southwest
Indian Ocean that would also open up in the Cretaceous.
The second, major phase in the break-up of Pangaea began in the
Early Cretaceous (150-140 million years ago), when the minor supercontinent of Gondwana separated into four multiple continents (
Africa,
South America,
India and
Antarctica/
Australia). About 200 million years ago, the continent of
Cimmeria, as mentioned above ("The Formation of Pangaea"), collided with
Eurasia. However, a subduction zone was forming, as soon as Cimmeria collided.
This subduction zone was called the
Tethyan Trench. This trench might have subducted what is called the Tethyan
mid-ocean ridge, a ridge responsible for Tethys Ocean's expansion. It probably caused Africa, India and Australia to move northward. In the Early Cretaceous,
Atlantica, today's South America and Africa, finally separated from Eastern Gondwana (Antarctica,
India, and Australia), causing the opening of a "South Indian Ocean". In the middle
Cretaceous,
Gondwana fragmented to open up the South Atlantic Ocean as South America started to move westward away from Africa. The South Atlantic did not develop uniformly, rather it rifted from south to north like a zipper.
Also, at the same time
Madagascar and
India began to separate from
Antarctica and moved northward, opening up the
Indian Ocean. Madagascar and India separated from each other 100 - 90 million years ago in the Late
Cretaceous. India continued to move northward toward
Eurasia at 15 centimeters per year (a plate tectonic record), closing the
Tethys Ocean, while Madagascar stopped and became locked to the
African Plate.
New Zealand and
New Caledonia began to move from Australia in an eastward direction towards the
Pacific, opening the
Coral Sea and
Tasman Sea. They have been independent islands since.
The third major and final phase of the break-up of Pangaea occurred in the early
Cenozoic (
Paleocene -
Oligocene).
North America/
Greenland broke free from
Eurasia, opening the
Norwegian Sea about 60-55 million years ago. The
Atlantic and
Indian Oceans continued to expand, closing the
Tethys Ocean.
Meanwhile,
Australia split from
Antarctica and moved rapidly northward, just as
India did more than 40 million years earlier, and is on a collision course with
Eastern Asia. Both Australia and India are currently moving in a northeast direction at 5-6 cm/year. Antarctica has been near or at the
South Pole since the formation of Pangaea (since about 280 Ma). India started to collide with
Asia beginning about 35 million years ago, forming the
Himalayan orogeny, and also finally closing the
Tethys Seaway; this collision continues today. The
African Plate started to change directions, from west to northwest toward
Europe, and
South America began to move in a northward direction separating it from
Antarctica, allowing complete oceanic circulation around
Antarctica for the first time, causing a rapid cooling of the continent and allowing
glaciers to form. Other major events took place during the
Cenozoic, including the opening of the
Gulf of California, the uplift of the
Alps, and the opening of the
Sea of ***an. The break-up of Pangaea continues today in the
East Africa Rift; ongoing collisions may indicate the incipient creation of a new
supercontinent.
Caldoc
Genesis 10 The Continents divide.??
I got in her about 5:30 AM but didn't see anything. This time I brought my stand home.
