New high-quality paleomagnetic data from the Borborema Province (NE Brazil): Refinement of the APW path of Gondwana in the Early Cambrian

Autor(es)

Jean Antonio, Paul Yves ^[1] ; Ferreira Trindade, Ricardo Ivan ^[1] ; Giacomini, Bruno ^[1] ; Brandt, Daniele ^[1] ; Tohver, Eric ^[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

• Tipo de documento: Artigo Científico
• Fonte: Precambrian Research; v. 360, JUL 15 2021.
• Citações Web of Science: 0

Resumo

The Neoproterozoic-Paleozoic transition (similar to 541 Ma) was a turning point in Earth's history resulting in great biological changes between the microbial Precambrian life and the Ediacaran biotic revolution with the occupation of the sedimentary substrate, the dawn of biomineralization and the appearance of the earliest multicellular organisms. In parallel, this period is marked by a large plate reorganization leading to the assembly of Gondwana and by major climatic changes (extreme glacial events). Due in part to a poor paleomagnetic database for the different cratons in the Ediacarian-Cambrian times, the global paleogeography at that time remains controversial. In this study we present a new high-quality paleomagnetic pole (R = 7) for the Monteiro dyke swarm in the Borborema Province (NE Brazil) located at 18.2 degrees S and 344.9 degrees E (A95 = 11.7 degrees K = 9.3). They are fine-grained hornblende dolerite dated by U-Pb on zircon at similar to 538 Ma. Rock magnetic data indicate that magnetite and pyrrhotite are the main remanence carriers. Positive baked-contact tests support the primary remanence obtained for these dykes (19 sites). A positive reversal test (classified C) was also obtained from the 14 sites with negative inclination and the 5 sites with positive inclination, indicating that the paleosecular variation was eliminated. Our new key pole is not consistent with the classical apparent polar wander path of the Gondwana which consists of a long track from a southern polar position at similar to 590 Ma to an equatorial position at similar to 520 Ma, and suggests instead rapid and small oscillations of the APW, after the end of the large IITPW at ca. 560 Ma. These TPWs are supposedly caused by changes in the inertia tensor of the Earth due to internal mass redistribution, related to rapid changes in subduction velocity. Links of these rapid oscillations and the timing of the Cambrian radiation could be crucial to understand the early history of animal life. (AU)

• Processo FAPESP: 18/23755-0 - Um teste para a conexão Amazônia-Oeste África: novos pólos paleomagnéticos para Oeste África
• Beneficiário: Paul Yves Jean Antonio
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Pós-Doutorado
• Processo FAPESP: 16/06114-6 - O Sistema Terra e a evolução da vida durante o Neoproterozoico
• Beneficiário: Ricardo Ivan Ferreira da Trindade
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• 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