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

Author(s)

Bispo-Santos, Franklin ; D'Agrella-Filho, Manoel S. ; Janikian, Liliane ; Reis, Nelson J. ; Trindade, Ricardo I. F. ; Reis, Maria Anna A. A.

• Document type: Journal article
• Source: Precambrian Research; v. 244, p. 16-pg., 2014-05-01.

Abstract

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 degrees, I-m =39.4 degrees, alpha(95) = 10.1 degrees, N = 20 degrees, K=11.4 degrees), which yielded a paleomagnetic pole (SG) located at 234.8 degrees E, 27.4 degrees N (A(95)= 9.8 degrees). 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 Guni (Guiana Shield) and Sassandra (West Africa Craton) shear zones were aligned as previously proposed. (C) 2013 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 11/50887-6 - Paleomagnetism of proterozoic geological units from the Amazonian Craton, and its participation in the Columbia, Rodinia, and Gondwana supercontinents
• Grantee: Manoel Souza D'Agrella Filho
• Support Opportunities: Regular Research Grants
• FAPESP's process: 12/50327-3 - The Amazonian Craton and the supercontinent Columbia: paleogeographic implications based on the paleomagnetic study of Paleo-mesoproterozoic geological units
• Grantee: Franklin Bispo dos Santos
• Support Opportunities: Scholarships in Brazil - Post-Doctoral