The Mozambique Belt is a band in the earth's crust that extends from

East Antarctica East Antarctica, also called Greater Antarctica, constitutes the majority (two-thirds) of the Antarctic continent, lying on the Indian Ocean side of the continent, separated from West Antarctica by the Transantarctic Mountains. It lies almost ...

through

East Africa East Africa, Eastern Africa, or East of Africa, is the eastern subregion of the African continent. In the United Nations Statistics Division scheme of geographic regions, 10-11-(16*) territories make up Eastern Africa: Due to the historica ...

up to the

Arabian-Nubian Shield The Arabian-Nubian Shield (ANS) is an exposure of Precambrian crystalline rocks on the flanks of the Red Sea. The crystalline rocks are mostly Neoproterozoic in age. Geographically - and from north to south - the ANS includes parts of Israel, Jor ...

. It formed as a suture between plates during the

Pan-African orogeny The Pan-African orogeny was a series of major Neoproterozoic orogenic events which related to the formation of the supercontinents Gondwana and Pannotia about 600 million years ago. This orogeny is also known as the Pan-Gondwanan or Saldanian Oro ...

, when

Gondwana Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period The Jurassic ( ) is a geologic period and st ...

was formed. The Mozambique Belt includes components created when the Mozambique Ocean opened and others created when the ocean later closed.

Extent

The western portion of the Mozambique Belt is mostly composed of upper

amphibolite Amphibolite () is a metamorphic rock that contains amphibole, especially hornblende and actinolite, as well as plagioclase feldspar, but with little or no quartz. It is typically dark-colored and dense, with a weakly foliated or schistose ( ...

-grade

gneiss Gneiss ( ) is a common and widely distributed type of metamorphic rock. It is formed by high-temperature and high-pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. Gneiss forms at higher temperatures an ...

es, reworked rocks from the

Tanzania craton The Tanzania Craton is an old and stable part of the continental lithosphere in central Tanzania. Some of the rocks are over 3 billion years old. Setting The Tanzania Craton forms the highest part of the East African Plateau. The craton is surr ...

and Usagaran Belt, emplaced between 2,970 and 2,648 million years ago. The eastern portion has high-grade arc-derived rocks ranging in age from 841 to 632 million years ago. Both terranes also include

Neoproterozoic The Neoproterozoic Era is the unit of geologic time from 1 billion to 538.8 million years ago. It is the last era of the Precambrian Supereon and the Proterozoic Eon; it is subdivided into the Tonian, Cryogenian, and Ediacaran periods. It is pre ...

metasedimentary rocks. The differences may indicate origins in two different basins, with the eastern basin rocks being thrust over those of the western basin during closure of the Mozambique Ocean between 585 and 550 million years ago.

Formation

Many geologists consider that the Mozambique Ocean formed during the break-up of

Rodinia Rodinia (from the Russian родина, ''rodina'', meaning "motherland, birthplace") was a Mesoproterozoic and Neoproterozoic supercontinent that assembled 1.26–0.90 billion years ago and broke up 750–633 million years ago. were probabl ...

between 800 and 700 million years ago, accompanied by volcanic activity. Magmatism from this period is found in East Africa and Madagascar, although not in the southern Mozambique Belt. The ocean probably separated the

Kalahari craton The Kalahari Craton is a craton, an old and stable part of the continental lithosphere, that occupies large portions of South Africa, Botswana, Namibia and Zimbabwe. It consists of two cratons separated by the Limpopo Belt: the larger Kaapvaal C ...

from the combined Congo -

Tanzania Tanzania (; ), officially the United Republic of Tanzania ( sw, Jamhuri ya Muungano wa Tanzania), is a country in East Africa within the African Great Lakes region. It borders Uganda to the north; Kenya to the northeast; Comoro Islands an ...

craton, and separated the Madagascar-India block from the Congo-Tanzania block. The ocean began closing between Madagascar-India and Congo-Tanzania between 700 and 580 million years ago, with closure between 600 and 500 million years ago. Exposed rocks in

Kenya ) , national_anthem = " Ee Mungu Nguvu Yetu"() , image_map = , map_caption = , image_map2 = , capital = Nairobi , coordinates = , largest_city = Nairobi ...

and

include

rift In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-graben wi ...

sediments and

passive margin A passive margin is the transition between oceanic and continental lithosphere that is not an active plate margin. A passive margin forms by sedimentation above an ancient rift, now marked by transitional lithosphere. Continental rifting crea ...

metasediments from the early

continental margin. They also include older crustal material from the Tanzanian craton that has been reworked. At one time the belt was thought to have been caused by the collision of east and west Gondwana. According to a more recent theory, Gondwana formed over an extended period from

accretion Accretion may refer to: Science * Accretion (astrophysics), the formation of planets and other bodies by collection of material through gravity * Accretion (meteorology), the process by which water vapor in clouds forms water droplets around nucl ...

of independent

terrane In geology, a terrane (; in full, a tectonostratigraphic terrane) is a crust fragment formed on a tectonic plate (or broken off from it) and accreted or " sutured" to crust lying on another plate. The crustal block or fragment preserves its own ...

s. The Mozambique Belt rocks formed from magmatic underplating and a period of residence in the mid-lower crust followed by cooling between 640 and 620 million years ago. The rocks were exhumed over 500 million years ago. The deeper crustal levels were elevated by the closure of the Mozambique Ocean and the upper crustal arc remnants were removed by erosion.

References

Sources

* * * {{refend Neoproterozoic orogenies Orogenies of Africa Earth's crust