4-D Framework of Continental Crust
Proterozoic accretionary belts in the Amazonian Craton
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Published:January 01, 2007
Within the Amazonian Craton, Archean crust is restricted to the Carajás granite-greenstone terrain. The younger Maroni-Itacaiunas province, including supra-crustal sequences and associated calc-alkaline granitoids, is linked with the Birimian system in West Africa, making up a large Paleoproterozoic cratonic nucleus. Beginning at ca. 2.0 Ga, accretionary belts formed along the southwestern margin of this nucleus, giving rise to the Ventuari-Tapajós (2000–1800 Ma), Rio Negro–Juruena (1780–1550 Ma), and Rondonian–San Ignacio (1500–1300 Ma) tectonic provinces. Continued soft-collision/accretion processes driven by subduction produced a very large “basement” in which granitoid rocks predominate, many of them with juvenile-like Nd isotopic signatures. Felsic volcanics are also widespread; however, there is no evidence of Archean basement inliers, and regions with high-grade metamorphics are restricted.
The Sunsas-Aguapeí (1250–1000 Ma) orogenic belt, at the southwestern end of the craton, was originated in an extensional environment, later deformed during the Grenvillian collision between Amazonia and Laurentia. Over the cratonic area, a widespread anorogenic granitic magmatism (1000–970 Ma) is a reflection of this orogeny over the stable foreland. After the termination of the Sunsas orogeny, continental fragmentation affected the eastern margin of the Amazonian Craton. The intra-oceanic Goiás magmatic arc, closely associated with the Transbrasiliano megasuture, is the evidence of a large oceanic domain that started its consumption between 900 and 800 Ma, giving rise to juvenile material represented by calc-alkaline orthogneisses. Later, these units were deformed during the Brasiliano orogeny (700–500 Ma), in the process of amalgamation of Gondwana.
- absolute age
- accreting plate boundary
- basement
- Borborema Province
- Brazil
- Brazilian Shield
- calc-alkalic composition
- Cambrian
- Carajas mineral province
- continental crust
- cratons
- crust
- dates
- forelands
- geochemistry
- Goias Brazil
- Gondwana
- greenstone belts
- high-grade metamorphism
- igneous rocks
- intrusions
- ion probe data
- island arcs
- isotope ratios
- isotopes
- Laurentia
- magmas
- magmatic differentiation
- magmatism
- mantle
- mass spectra
- metals
- metamorphic belts
- metamorphism
- Nd-144/Nd-143
- neodymium
- Neoproterozoic
- nesosilicates
- orogenic belts
- orogeny
- orthosilicates
- paleogeography
- Paleoproterozoic
- Paleozoic
- Para Brazil
- petrology
- plate tectonics
- plutonic rocks
- Precambrian
- Proterozoic
- rare earths
- Rodinia
- Sao Francisco Craton
- SHRIMP data
- silicates
- South America
- South American Plate
- spectra
- stable isotopes
- subduction
- tectonics
- U/Pb
- upper Precambrian
- zircon
- zircon group
- Rio Negro-Juruena Province
- Ventuari-Tapajos Province
- Rondonian-San Ignacio Province
- Maroni-Itacaiunas Province
- continental amalgamation
- Goias Arc
- Sunsas-Aguapei Belt
- Central Amazonian Province