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Research Article |
1 Dipartimento de Geoscienze, Universita di Padova, Via Giotto 1, 35137 Padova, Italy
2 Present address: University of Western Australia, School of Earth and Geographical Sciences, 35 Stirling Highway, Crawley, WA 6009, Australia
3 Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, CA 94709, USA
4 Western Australian Argon Isotope Facility, Department of Applied Geology and JdL-CMS, Curtin University of Technology, GPO Box U1987, Perth, WA 6845, Australia
5 Department of Earth and Planetary Science, University of California, Berkeley, CA 94720, USA
6 Department of Applied Geology, Curtin University of Technology, GPO Box U1987, Perth, WA 6845, Australia
7 Laboratoire de Planétologie et Géodynamique, UMR-CNRS 6112, Université de Nantes, 2 rue de la Houssinère, 44322 Nantes cedex 3, France
*Corresponding author (e-mail: rmerle{at}cyllene.uwa.edu.au)
Supplementary material: A detailed Ar measurements dataset is available at http://www.geolsoc.org.uk/SUP18359.
The Tore–Madeira Rise is a seamount chain located 300 km off the Portugal and Morocco coasts attributed to hotspot activity. U–Pb ages of lavas from the northern and central Tore–Madeira Rise range between 103 and 80.5 Ma whereas 40Ar/39Ar ages from the central and southern Tore–Madeira Rise yield ages ranging from 94.5 to 0.5 Ma. We performed new 40Ar/39Ar measurements to better understand the geodynamic history of the Tore–Madeira Rise. Plagioclase ages from the Bikini Bottom and Torillon seamounts suggest ages of >90 Ma and 
60 Ma, respectively. Amphiboles from the Seine seamount yield an age of 24.0 ± 0.8 Ma. Biotites from lavas of the Ashton seamount give ages of 97.4 ± 1.1 Ma and 97.8 ± 1.1 Ma. The geochronological database available on the Tore–Madeira Rise has been filtered on statistical criteria to eliminate unreliable ages. The resulting database reveals three pulses of alkaline magmatism on the Tore–Madeira Rise at 103–80.5 Ma, at c. 68 Ma and between 30 Ma and the present. The magmatism was continuous from 103 Ma until c. 68 Ma and from c. 30 Ma until the present on the Tore–Madeira Rise, the surrounding seamounts and the Portugal coast. We suggest that the space–time distribution of this magmatism results from the interaction between a wide thermal anomaly emitting magmatic pulses and the complex motion of the Iberian plate.
