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Towards Columbia: Paleomagnetism of 1980–1960Ma Surumu volcanic rocks, Northern Amazonian Craton

2013; Elsevier BV; Volume: 244; Linguagem: Inglês

10.1016/j.precamres.2013.08.005

1872-7433

Franklin Bispo-Santos, Manoel S. D’Agrella-Filho, Liliane Janikian, Nélson Joaquim Reis, Ricardo I.F. Trindade, Maria Anna A.A. Reis,

Paleontology and Stratigraphy of Fossils

We present a paleomagnetic study on the well-dated 1980–1960 Ma (U-Pb) volcanic rocks from the Surumu Group, northern Roraima State (Amazonian Craton). After thermal and AF demagnetization, characteristic northwestern remanent magnetization (ChRM) directions with downward inclinations were isolated (mean: Dm = 298.6°, Im = 39.4°, α95 = 10.1°, N = 20, K = 11.4), which yielded a paleomagnetic pole (SG) located at 234.8°E, 27.4°N (A95 = 9.8°). Magnetic mineralogy experiments show that ChRM is carried by high-Hc, and high-unblocking temperature Ti-poor titanomagnetite and/or hematite. The well-dated pole SG contributes to better define the apparent polar wander (APW) path for the Guiana Shield during the Paleoproterozoic (2070–1960 Ma). Comparison of the Amazonian and West African Craton's APW paths for the same time interval suggests that these cratonic blocks were linked together at about 1980–1960 Ma ago in a paleogeography along which the Guri (Guiana Shield) and Sassandra (West Africa Craton) shear zones were aligned as previously proposed.