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The Rio Negro Province in the NW Amazon craton is composed of three domains (northeastern, central, and southwestern) in turn separated into several regional terrains, showing main NE-SW and WNW-ESE structures and being composed of high-grade polydeformed basement with 1840–1700 Ma protolith ages. The Northeastern Domain shows basements dominated by high-K calc-alkaline to shoshonitic metagranitoids, orthogneisses, migmatites, augen gneisses, and local A-type leucogneisses (1810–1760 Ma, Cauaburi Complex). In Venezuela, this basement is not widely known, but encompasses the oldest rocks of the province (1840–1820 Ma, San Carlos Metamorphic Terrane). The Southwestern Domain comprises medium- to high-K calc-alkaline orthogneisses (Querari Complex) with an extended compositional range (diorite to granite), NE-trending main foliation, and 1740–1700 Ma protolith ages. The Central Domain comprises peraluminous crustal-derived granites (1520–1480 Ma), supracrustal rocks, paragneisses, and some Cauaburi Complex inliers. The Nd isotope data for the basement rocks indicates mantle sources with decreasing crustal contributions and younger TDM ages from east (2.54–1.96 Ga) to west (1.97–1.82 Ga). The Rio Negro Province is interpreted as an accretionary orogen formed by a long-lived magmatic arc system active during three phases: 1.84–1.82 Ga, 1.81–1.76 Ga (main flare up) and 1.75–1.70 Ga. Later, this arc system was affected by collisional orogenies at ~1500 Ma (Içana Orogeny) and ~1300 Ma (Putumayo Orogeny), as showed by the Ar–Ar step heating plateau ages (biotite, hornblende) and U-Pb SHRIMP ages (zircon, titanite) recording two main metamorphic events at 1520–1480 Ma (medium–high T) and 1400–1310 Ma (low–medium T), with important tectonothermal effects also further east in the Tapajós-Parima Province. Based on similar accretionary histories, the Rio Negro Province has also apparent long-lived connections with Laurentia and Baltica (Transscandinavian Belt), forming the core of the Columbia Supercontinent. [ABSTRACT FROM AUTHOR]

During the Grenvillian assembly of Rodinia, the Namaqua-Natal Metamorphic Province (NNMP) was formed as a result of the convergence of the Laurentia and Kalahari cratons. A detailed model for this accretion along the southeastern margin of the Kalahari Craton has been established, but the tectonic history of the NNMP along the western margin of the Kalahari Craton has remained highly controversial. U-Pb SHRIMP zircon age dating of gneiss in the Kakamas Domain of the NNMP, as well as U-Pb SHRIMP age dating of detrital zircons and 40Ar/39Ar dating of metamorphic muscovite from sediments overlying the gneiss, confirms the presence of at least two separate events during the Namaqua-Natal Orogeny at ~1 166 Ma and 1 116 Ma. These events occurred after the Areachap Terrane was accreted onto the western margin of the Proto-Kalahari Craton during the Kheis Orogeny. 40Ar/39Ar ages derived from metamorphic muscovite formed in the metasediments of the Kheis terrane does not provide evidence for the timing of the Kheis Orogeny but suggests that it most likely only occurred after ~1 300 Ma and not at 1 800 Ma as commonly accepted. A U-Pb concordia age of ~1 166 Ma was derived from granitic gneiss in the Kakamas Domain of the Bushmanland Subprovince, possibly reflecting subduction and the initiation of continent-continent collision between the Proto-Kalahari Craton and the Bushmanland Subprovince. This granitic gneiss is nonconformably overlain by the metasediments of the Korannaland Group that contains metamorphic muscovite with 40Ar/39Ar ages of ~1 116 Ma. This age suggest that complete closure of the ocean between the Proto-Kalahari Craton and Bushmanland Subprovince probably occurred about 50 Ma after the intrusion of the ~1 166 Ma granitic gneisses. [ABSTRACT FROM AUTHOR]