Wednesday, September 26, 2012

List of tectonic plates


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Global earthquake epicentres, 1963–1998
The 15 major plates
Plate tectonics map from NASA
This is a list of tectonic plates on Earth. Tectonic plates are pieces of the Earth's crust and uppermost mantle, together referred to as the lithosphere. The plates are around 100 km (62 mi) thick and consist of two principal types of material: oceanic crust (also called sima from silicon and magnesium) and continental crust (sial from silicon and aluminium). The composition of the two types of crust differs markedly, with basaltic rocks ("mafic") dominating oceanic crust, while continental crust consists principally of lower density granitic rocks ("felsic"). See also Plate tectonics

Contents

Current plates

The following tectonic plates currently exist on the Earth's surface with roughly definable boundaries.

Primary plates

These seven plates comprise the bulk of the seven continents and the Pacific Ocean.

Secondary plates

These smaller plates are generally shown on major plate maps, but with the exception of the Arabian and Indian plates do not comprise significant land area.

Tertiary plates

Tertiary plates are grouped with the major plate that they would otherwise be shown as part of on a major plate map. Mostly these are tiny microplates, although in the case of the Nubian-Somalian and Australian-Capricorn-Indian plates these are major plates that are rifting apart. Some models identify more minor plates within current orogens like the Apulian, Explorer, Gorda, and Philippine Mobile Belt plates. The remainder of the tertiary plates are the dwindling remains of much larger ancient plates. There may or may not be scientific consensus as to whether a tertiary plate is a separate plate yet, is still a separate plate, or should be considered a separate plate, thus new research could change this list.[1][2][3][4]

Ancient continental formations

In the history of Earth many tectonic plates have come into existence and have over the intervening years either accreted onto other plates to form larger plates, rifted into smaller plates, or have been crushed by or subducted under other plates (or have done all three).

Ancient supercontinents

A supercontinent is a landmass consisting of multiple continental cores. The following list includes the supercontinents known or speculated to have existed in the Earth's past:

Ancient plates and cratons

Not all plate boundaries are easily defined, this is especially true for ancient pieces of crust. The following list of ancient cratons, microplates, plates, shields, terranes, and zones no longer exist as separate plates. Cratons are the oldest and most stable parts of the continental lithosphere and shields are the exposed area of a craton(s). Microplates are tiny tectonic plates, terranes are fragments of crustal material formed on one tectonic plate and accreted to crust lying on another plate, and zones are bands of similar rocks on a plate formed by terrane accretion or native rock formation. Terranes may or may not have originated as independent microplates since a terrane may not contain the full thickness of the lithosphere.

African plate

Antarctica plate

Eurasian plate

Indo-Australian plate

Basic geological regions of Australia, by age.
Map of chronostratigraphic divisions of India

North American plate

North American Cratons and basement rocks.

South American plate

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