The final stages of the breakup of
Pangaea occurred during the Paleogene as
Atlantic Ocean rifting and
seafloor spreading extended northwards, separating the
North America and
Eurasian plates, and
Australia and
South America rifted from
Antarctica, opening the
Southern Ocean.
Africa and
India collided with Eurasia forming the
Alpine-Himalayan mountain chains and the western margin of the
Pacific plate changed from a
divergent to
convergent plate boundary.
Alpine–Himalayan orogeny Alpine orogeny The
Alpine orogeny developed in response to the collision between the African and Eurasian plates during the closing of the
Neotethys Ocean and the opening of the Central Atlantic Ocean. The result was a series of arcuate mountain ranges, from the
Tell-
Rif-
Betic cordillera in the western
Mediterranean through the
Alps,
Carpathians,
Apennines,
Dinarides and
Hellenides to the
Taurides in the east. Convergence between the
Iberian and European plates led to the
Pyrenean orogeny and, as Adria pushed northwards the Alps and Carpathian orogens began to develop. Between about 40 and 30 Ma, subduction began along the western Mediterranean arc of the Tell, Rif, Betic and Apennine mountain chains. The rate of convergence was less than the subduction rate of the dense
lithosphere of the western Mediterranean and
roll-back of the subducting slab led to the arcuate structure of these mountain ranges.
Zagros Mountains The
Zagros mountain belt stretches for c. 2000 km from the eastern border of
Iraq to the
Makran coast in southern
Iran. It formed as a result of the convergence and collision of the
Arabian and Eurasian plates as the Neotethys Ocean closed and is composed sediments scraped from the descending Arabian Plate. From the Late Cretaceous, a
volcanic arc developed on the Eurasia margin as the Neotethys crust was subducted beneath it. A separate intra-oceanic subduction zone in the Neotethys resulted in the
obduction of ocean crust onto the Arabian margin in the Late Cretaceous to Paleocene, with break-off of the subducted oceanic plate close to the Arabian margin occurring during the Eocene. To the south of this zone, the Himalaya are composed of
metasedimentary rocks scraped off the now subducted Indian continental crust and
mantle lithosphere as the collision progressed. Debate about the amount of deformation seen in the geological record in the India–Eurasia collision zone versus the size of Greater India, the timing and nature of the collision relative to the decrease in plate velocity, and explanations for the unusually high velocity of the Indian plate have led to several models for Greater India: 1) A Late Cretaceous to early Paleocene subduction zone may have lain between India and Eurasia in the Neotethys, dividing the region into two plates, subduction was followed by collision of India with Eurasia in the middle Eocene. In this model Greater India would have been less than 900 km wide; 3) This model assigns older dates to parts of Greater India, which changes its paleogeographic position relative to Eurasia and creates a Greater India formed of extended continental crust 2000–3000 km wide.
South East Asia The Alpine-Himalayan Orogenic Belt in
Southeast Asia extends from the Himalayas in India through
Myanmar (
West Burma block)
Sumatra,
Java to
West Sulawesi. During the Late Cretaceous to Paleogene, the northward movement of the Indian plate led to the highly oblique subduction of the Neotethys along the edge of the West Burma block and the development of a major north-south
transform fault along the margin of Southeast Asia to the south. Extension between North America and Eurasia, also in the early Eocene, led to the opening of the Eurasian Basin across the Arctic, which was linked to the Baffin Bay Ridge and Mid-Atlantic Ridge to the south via major strike slip faults. From the Eocene and into the early Oligocene, Greenland acted as an independent plate moving northwards and rotating anticlockwise. This led to compression across the
Canadian Arctic Archipelago,
Svalbard and northern Greenland resulting in the
Eureka orogeny.|alt=Cliff face showing three layers of rock; the bottom layer is sedimentary rock; the middle layer forms columns, whilst the layer above is blocky in appearance. The
North Atlantic Igneous Province stretches across the Greenland and northwest European margins and is associated with the proto-Icelandic
mantle plume, which rose beneath the Greenland lithosphere at c. 65 Ma. The arrival of the proto-Iceland plume has been considered the driving mechanism for rifting in the North Atlantic. However, that rifting and initial seafloor spreading occurred prior to the arrival of the plume, large scale magmatism occurred at a distance to rifting, and that rifting propagated towards, rather than away from the plume, has led to the suggestion the plume and associated magmatism may have been a result, rather than a cause, of the plate tectonic forces that led to the propagation of rifting from the Central to the North Atlantic. With the Laramide uplift the
Western Interior Seaway was divided and then retreated. Over the Paleogene, changes in plate motion and episodes of regional slab shallowing and steepening resulted in variations in the magnitude of crustal shortening and amounts of magmatism along the length of the
Andes.
Caribbean The
Caribbean plate is largely composed of oceanic crust of the
Caribbean Large Igneous Province that formed during the Late Cretaceous. During the Eocene (c. 45 Ma), subduction of the Farallon plate along the Central American subduction zone was (re)established. By the Oligocene, the intra-oceanic
Central American volcanic arc began to collide with northwestern South American. The resulting changes in stress between the Pacific and
Philippine Sea plates initiated subduction along the
Izu-Bonin-Mariana and
Tonga-Kermadec arcs. leading to major strike-slip movements and the formation of the
San Andreas Fault.
Antarctica Slow seafloor spreading continued between Australia and East Antarctica. Shallow water channels probably developed south of Tasmania opening the
Tasmanian Passage in the Eocene and deep ocean routes opening from the mid Oligocene. Rifting between the Antarctic Peninsula and the southern tip of South America formed the
Drake Passage and opened the Southern Ocean also during this time, completing the breakup of Gondwana. The opening of these passages and the creation of the Southern Ocean established the
Antarctic Circumpolar Current.
Glaciers began to build across the Antarctica continent that now lay isolated in the south polar region and surrounded by cold ocean waters. These changes contributed to the fall in global temperatures and the beginning of icehouse conditions. To the west, in the early Oligocene,
flood basalts erupted across
Ethiopia, northeast
Sudan and southwest
Yemen as the
Afar mantle plume began to impact the base of the African lithosphere. Rifting across the southern
Red Sea began in the mid Oligocene, and across the central and northern Red Sea regions in the late Oligocene and early Miocene. == Climate ==