The Transamazonian orogeny was a mountain building event in the Paleoproterozoic, affecting what is now the São Francisco Craton and Guyana Shield. During the orogeny from 2.14 to 1.94 billion years ago two small

Archean The Archean ( , also spelled Archaean or Archæan), in older sources sometimes called the Archaeozoic, is the second of the four geologic eons of Earth's history of Earth, history, preceded by the Hadean Eon and followed by the Proterozoic and t ...

proto-continents—including the greenstone belt-dominated Gavião Block and the calc-alkaline charnockite and enderbite-dominated Jequié Block—collided. The Contendas-Jacobina Lineament represents a suture zone where the collision occurred and the Gavião Block partially subducted under the Jequié Block. At the same time, another small continental fragment, the Serrinha Block, may have collided as well and was extensively reworked and metamorphosed, with orthogneiss and migmatite reaching

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 on the sequence of metamorphic facies. The Serrinha Block is the basement rock of the Rio Itapicuru granite-greenstone belt. Several magmatic arcs formed between the colliding proto-continent blocks, including the Salvador-Curaçá Belt, Contendas-Mirante Belt, Jacobina-Mundo Novo Belt and Itabuna-Atlantic Belt. To the west of the Gavião Block, the Guanambi-Urandi Batholith formed with monzonite,

granite Granite ( ) is a coarse-grained (phanerite, phaneritic) intrusive rock, intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly coo ...

intrusions and syenite, which was subsequently covered by

Neoproterozoic The Neoproterozoic Era is the last of the three geologic eras of the Proterozoic geologic eon, eon, spanning from 1 billion to 538.8 million years ago, and is the last era of the Precambrian "supereon". It is preceded by the Mesoproterozoic era an ...

sedimentary rocks. In the Guyana Shield, the Transamazonian orogeny resulted in refolding and reactivation of older tectonic features from the Guriense orogeny, producing horst and graben areas and intense pyroclastic ignimbrite and

rhyolite Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture (geology), texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained matri ...

eruptions.

References

Orogenies of South America Geology of South America Archean orogenies {{Orogeny-stub

See also

References