The ENE-WSW Juzbado-Penalva do Castelo Shear Zone (JPCSZ), 200 km long and 5-15 km wide, is a first order structure of the Iberian Variscides with a sinistral component emphasized by a 65 km ductile reject of the major D1 structures (Iglesias & Ribeiro, 1981); the NW-SE regional trend (e.g. Marão and Tamames structures) changes to E-W (e.g. Moncorvo and Poiares synclines) when approaching the JPCSZ and even to ...
The islands of the Azores archipelago emerge from an oceanic plateau built on lithosphere increasing in age with distance from the Mid-Atlantic Ridge from 10 to 45 Ma. Here, we present the first comprehensive major and trace element and Sr–Nd–Pb isotope data from Santa Maria, the easternmost island of the archipelago, along with published data from the other Azores islands situated much closer to the Mid-Atlant...
Geochemical characterization of alkaline gneissic rocks of Alentejo (Portugal) J. Carrilho Lopes1, J. Munhá2, C. Pin3, J. Mata2 1Departamento de Geociências, Universidade de Évora & Centro de Geologia da Universidade de Lisboa, Portugal. 2Departamento de Geologia & Centro de Geologia da Universidade de Lisboa, Portugal. 3Département de Géologie, C.N.R.S., Université Blaise Pascal, France. carrilho@uevora.pt Thi...
We present He and Ne isotopic data from subaerial and submarine samples collected along the Terceira Rift. Graciosa Island as well as the western end of S. Miguel Island and D. João de Castro Bank display 4He/3He ratios similar to those observed along the MAR segments located to the north of the Azores Triple Junction area. Conversely, samples from the south Hirondelle Basin display a 4He/3He ratio similar to t...
Neste trabalho foram obtidas razões isotópicas de He e Ne em fenocristais de olivina separados a partir de lavas amostradas no arquipélago dos Açores e, em particular, ao longo da fronteira de placas designada por Rift da Terceira. Nele são apresentados os primeiros dados isotópicos de Ne obtidos para lavas basálticas das ilhas de S. Miguel, da Graciosa e do Faial. De igual modo, merecem destaque os dados de ga...
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