The long life of SAMBA connection in Columbia: A paleomagnetic study of the 1535 Ma Mucajai Complex, northern Amazonian Craton, Brazil

Autor(es)

Bispo-Santos, Franklin ^[1] ; D'Agrella-Filho, Manoel S. ^[1] ; Pesonen, Lauri J. ^[2] ; Salminen, Johanna M. ^{[2, 3]} ; Reis, Nelson J. ^[4] ; Silva, Julia Massucato ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, Rua Matao 1226, BR-05508090 Sao Paulo, SP - Brazil

^[2] Univ Helsinki, Phys Dept, POB 64, FIN-00014 Helsinki - Finland

^[3] Univ Helsinki, Dept Geosci & Geog, POB 64, FIN-00014 Helsinki - Finland

^[4] Geol Survey Brazil, Manaus Agcy, Av Andre Araujo 2160, Manaus, Amazonas - Brazil

• Tipo de documento: Artigo Científico
• Fonte: GONDWANA RESEARCH; v. 80, p. 285-302, APR 2020.
• Citações Web of Science: 0

Resumo

In recent years, there has been a significant increase in the paleomagnetic data of the Amazonian Craton, with important geodynamic and paleogeographic implications for the Paleo-Mesoproterozoic Columbia supercontinent (a.k.a., Nuna, Hudsoland). Despite recent increase of paleomagnetic data for several other cratons in Columbia, its longevity and the geodynamic processes that resulted in its formation are not well known. A paleomagnetic study was performed on rocks from the similar to 1535 Ma AMG (Anorthosite-Mangerite-Rapakivi Granite) Mucajai Complex located in the Roraima State (Brazil), in the northern portion of the Amazonian Craton, the Guiana Shield. Thermal and AF treatments revealed northwestern/southeastern directions with upward/downward inclinations for samples from twelve sites. This characteristic remanent magnetization is mainly carried by Ti-poor magnetite and in a lesser amount by hematite. Site mean directions were combined with previous results obtained for three other sites from the Mucajai Complex, producing the dual polarity mean direction: Dm = 132.2 degrees; Im = 35.4 degrees (N = 15; alpha(95) = 12.7 degrees; k = 10.0) and a paleomagnetic pole located at 0.1 degrees E, 38.2 degrees S (A(95) = 12.6 degrees; K = 10.2). The Mucajai pole favours the SAMBA (South AMerica-BAltica) link in a configuration formed by Amazonia and Baltica in Columbia. Also, there is geological and paleomagnetic evidence that the juxtaposition of Baltica and Laurentia at 1.76-1.26 Ga forms the core of Columbia. The present paleomagnetic data predict a long life 1.78-1.43 Ga SAMBA connection forming part of the core of the supercontinent. (c) 2019 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved. (AU)

• Processo FAPESP: 16/13689-5 - O Cráton Amazônico e o Bloco Rio Apa na formação de paleocontinentes com base em estudos paleomagnéticos de unidades geológicas Proterozoicas.
• Beneficiário: Manoel Souza D'Agrella Filho
• Modalidade de apoio: Auxílio à Pesquisa - Regular