New constraints for paleogeographic reconstructions at ca. 1.88 Ga from geochronology and paleomagnetism of the Carajas dyke swarm (eastern Amazonia)

Autor(es):Mostrar menos -

Antonio, P. Y. J. ^{[1, 2]} ; D'Agrella-Filho, M. S. ^[1] ; Nedelec, A. ^[2] ; Poujol, M. ^[3] ; Sanchez, C. ^[4] ; Dantas, E. L. ^[5] ; Dall'Agnol, R. ^{[6, 7]} ; Teixeira, M. F. B. ^[8] ; Proietti, A. ^[9] ; Martinez Dopico, I, C. ; Oliveira, D. C. ^[7] ; Silva, F. F. ^[7] ; Marangoanha, B. ^[7] ; Trindade, R. I. F. ^[1]

Afiliação do(s) autor(es)

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

^[2] Univ Toulouse, UPS, Geosci Environm Toulouse GET, CNRS, IRD, CNES, 14 Ave E Belin, F-31400 Toulouse - France

^[3] Univ Rennes 1, Geosci Rennes, UMR CNRS 6118, F-35042 Rennes - France

^[4] Univ Paris Saclay, Univ Paris Sud, GEOPS, CNRS, Rue Belvedere, Bat 504, F-91405 Orsay - France

^[5] Univ Brasilia, Inst Geociencias, ICC Ctr, Campus Univ Darcy Ribeiro Asa Norte, BR-70910900 Brasilia, DF - Brazil

^[6] Inst Tecnol Vale, Belem, Para - Brazil

^[7] Univ Fed Para UFPA, Inst Geociencias IG, BR-66075900 Belem, Para - Brazil

^[8] Univ Fed Oeste Para, Santarem, Para - Brazil

^[9] Ctr Microcaracterisat Raimond Castaing, 3 Rue Caroline Aigle, F-31400 Toulouse - France

• Tipo de documento: Artigo Científico
• Fonte: Precambrian Research; v. 353, FEB 2021.
• Citações Web of Science: 0

Resumo

The Uatuma event is a silicic large igneous province (SLIP) covering an area of 1.500.000 km(2) of the Amazonia craton at ca. 1890-1850 Ma. New paleomagnetic data and U-Pb apatite ages for coeval microgranitic, andesitic, and basaltic dykes in the Carajas Province (southeastern Amazonia craton) are presented. Two primary characteristic remanent magnetizations (ChRMs) were isolated for the Carajas dykes which were combined with published results for coeval rocks in the Sao Felix do Xingu area, producing two grand mean poles: (1) ``CA1{''}, dated at 1880 Ma on zircon and apatite, whose mean site directions cluster around the mean D-m = 132.8 degrees, I-m = 76 degrees (N = 26, alpha(95) = 5 degrees, k = 32.7), yielding the paleomagnetic pole at 328.7 degrees E, 23.3 degrees S, (A(95) = 8.7 degrees K = 11.7), and (2) ``CA2{''} from well-dated microgranitic dykes of the Velho Guilherme Suite (1855 Ma U-Pb on zircon and apatite). Site mean directions group around the mean D-m = 240.3 degrees, I-m = 11.8 degrees (N = 18, c( 95 = 10.8 degrees, k = 11.1), which yielded the paleomagnetic pole at 221.3 degrees E, 30.2 degrees S, (A(95) = 8.8 degrees, K = 16.2). The remanent magnetization of the Velho Guilherme microgranitic dykes is carried by pseudo-single domain (PSD) magnetite. Its primary origin is supported by a positive baked contact test. Two younger secondary components were also isolated in the Carajas dyke swarm: one probably associated to the Mesozoic Central Atlantic magmatic province (CD3), and another component (CD4) with yet undefined age. A new configuration for the Amazonia and West Africa during the Paleoproterozoic, which aligns the Sassandra shear zone (in Africa) and the North Guiana Through and other shear zones (in Guiana Shield), is supported by geological and paleomagnetic data. The large angular distance between the 1880 Ma CA1 and 1855 Ma CA2 (Q similar to 6) poles that are relatively close in age implies in a high plate velocity for the Amazonia craton, which is not consistent with modern plate tectonics. A similar large discrepancy between 1880 and 1860 Ma poles was also observed at least as many as six cratons. Although other hypotheses can be invoked, such as non-uniformitarian magnetic fields, the occurrence of large-scale true polar wander at this time may be the most parsimonious explanation of the widespread discrepancies. (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
• Processo FAPESP: 12/20335-4 - Paleomagnetismo e petrogênese de unidades Paleoproterozóicas do evento Uatumã no norte do Craton Amazônico
• Beneficiário: Paul Yves Jean Antonio
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 17/18840-6 - Um teste para a conexão Amazônia-Oeste África e os eventos de deriva polar verdadeira durante o Neoproterozóico
• Beneficiário: Paul Yves Jean Antonio
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado