HR: 14:00h
AN: GP33A-03    [Abstracts]
TI: Discrimination of Multiple Magmatic Episodes in a Dike Swarm Along the Brazilian Southeast Coast
AU: * Ernesto, M
EM: marcia@iag.usp.br
AF: University of Sao Paulo, Rua do Matao, 1226, Sao Paulo, SP 05508-090 Brazil
AU: Marques, L S
EM: leila@iag.usp.br
AF: University of Sao Paulo, Rua do Matao, 1226, Sao Paulo, SP 05508-090 Brazil
AU: Piccirillo, E M
EM: picciril@univ.trieste.it
AF: University of Trieste, Via E. Weiss, 8, Trieste, 34127 Italy
AU: Bellieni, G
EM: giuliano@epidote.dmp.unipd.it
AF: University of Padova, Corso Garibaldi, 37, Padova, 35137 Italy
AU: de Min, A
EM: demin@univ.trieste.it
AF: University of Trieste, Via E. Weiss, 8, Trieste, 34127 Italy
AB: Integrated paleomagnetic, geochemical and geochrological data allowed the identification of four magmatic episodes (Jurassic to Tertiary) within the NE-SW trending dike swarm that extends from Santos to Rio de Janeiro cities, along the southeast Brazilian border. The Early Cretaceous, Late Cretaceous and Tertiary rocks were already known in literature and are discriminated by their tholeiitic (Early Cretaceous), and alkaline (Late Cretaceous and Tertiary) character, as well as by the magnetic polarities. The Jurassic dike group, however, has not yet been dated, and was recognized among the tholeiitic rocks by their distinct chemical signature and paleomagnetic characteristic magnetization. The corresponding paleomagnetic pole correlates with South American Early Jurassic poles putting some new constraints on the tectonic history of the South American margin before the Atlantic opening.
DE: 1025 Composition of the mantle
DE: 1035 Geochronology
DE: 1527 Paleomagnetism applied to geologic processes
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2005 Joint Assembly