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Instituto de Investigação
em Vulcanologia e Avaliação de Riscos

Painéis ► em encontros internacionais

 

Referência Bibliográfica


BÉGUIN, A., PIMENTEL, A., DE GROOT, L.V. (2019) - A multimethod paleointensity approach for Pico Island, Azores; towards a robust paleosecular variation curve. AGU Fall Meeting 2019, San Francisco (USA), 9-13 de dezembro.

Resumo


​Regional variations of the Earth's magnetic field can be described by paleosecular variation curves. Reliable estimates of the past strength of the Earth's magnetic field, however, are often hampered by thermal or chemical alteration of the magnetic signal. The multi-method paleointensity approach combines classical (double) heating methods, e.g. IZZI-Thellier, with iso-thermal paleointensity methods minimizing the effects of thermal alteration, i.e. microwave and pseudo-Thellier protocols, increasing the success rate for obtaining reliable paleointensity estimates from lavas. Here we present new paleointensity estimates from Pico Island, located in the Mid-Atlantic Ocean, derived with the multimethod approach. Extensive rock magnetic studies including susceptibility and magnetization as function of temperature, hysteresis analyses and scanning electron microscopy show suitable paleomagnetic carriers. Besides the new paleointensities, we also present a new way to take the uncertainty estimates of the calibration of radiocarbon ages to calendar years into account. We bootstrap the age distribution in combination with the paleointensity error distribution to produce a curve that fits the data as good as possible. Together with available data from Sã​o Miguel and Terceira we present a full-vector paleosecular variation curve for the Azores Archipelago for the last 5500 years. 

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