Journal ArticleDOI
Interaction between the Mid-Atlantic Ridge and the Azores hot spot during the last 85 Myr: Emplacement and rifting of the hot spot-derived plateaus
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In this paper, multiple and single-beam bathymetric data are compiled over the Azores plateau to produce a 1 km × 1 km grid between latitudes 32°N and 49°N, and longitudes 22°W and 43°W.Abstract:
[1] Multiple- and single-beam bathymetric data are compiled over the Azores plateau to produce a 1 km × 1 km grid between latitudes 32°N and 49°N and longitudes 22°W and 43°W. Mantle Bouguer anomalies are then calculated from this grid and the satellite-derived gravity. These grids provide new insights on the temporal and spatial variations of melt supply to the ridge axis. The elevated seafloor of the Azores plateau is interpreted as resulting from the interaction of a mantle plume with the Mid-Atlantic Ridge (MAR). The presence of a large region of elevated seafloor associated with a thick crust between the Great Meteor Seamounts and the Azores platform on the Africa plate, and less developed conjugate structures on the North America plate, favors genetic relations between these hot spot-derived structures. This suggests that a ridge-hot spot interaction has occurred in this region since 85 Ma. This interaction migrated northward along the ridge axis as a result of the SSE absolute motion of the Africa plate, following a direction grossly parallel to the orientation of the MAR. Kinematic reconstructions from chron 13 (∼35 Ma) to the present allow a proposal that the formation of the Azores plateau began around 20 Ma and ended around 7 Ma. A sharp bathymetric step is associated with the beginning of important melt supply around 20 Ma. The excess of melt production is controlled by the interaction of the ridge and hot spot melting zones. The geometry and distribution of the smaller-scale features on the plateau record episodic variations of the hot spot melt production. The periodicity of these variations is about 3–5 Myr. Following the rapid decrease of widespread volcanism, the plateau was subsequently rifted from north to south by the Mid-Atlantic Ridge since 7 Ma. This rifting begins when the MAR melting zone is progressively shifted away from the 200-km plume thermal anomaly. These results bear important consequences on the motion of the Africa plate relative to the Azores hot spot. They also provide an explanation to the asymmetric geochemical signature of the Azores hot spot along the Mid-Atlantic Ridge.read more
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Journal ArticleDOI
Heat flow variations on a slowly accreting ridge: Constraints on the hydrothermal and conductive cooling for the Lucky Strike segment (Mid-Atlantic Ridge, 37°N)
Francis Lucazeau,Alain Bonneville,Javier Escartín,Richard P. Von Herzen,Philippe Gouze,H. Carton,Mathilde Cannat,Valérie Vidal,Valérie Vidal,Claudia Adam,Claudia Adam +10 more
TL;DR: In this paper, 157 closely spaced heat flow measurements along the Lucky Strike segment in the Mid-Atlantic Ridge (MAR) for ages of the ocean floor between 0 and 11 Ma were reported.
Journal ArticleDOI
Constraints on the structure of the crust and lithosphere beneath the Azores Islands from teleseismic receiver functions
Kathrin Spieker,Kathrin Spieker,Stéphane Rondenay,Ricardo S. Ramalho,Ricardo S. Ramalho,Ricardo S. Ramalho,Christine Thomas,George Helffrich +7 more
TL;DR: In this article, the authors used data from nine seismic stations located on the Azores Islands to investigate the crustal structure with teleseismic P-wave receiver functions and found that the base of the volcanic edifice is located approximately 1 to 4 km depth beneath the different islands and that the crust-mantle boundary has an average depth of ∼17 km.
Journal ArticleDOI
Correlated Changes Between Volcanic Structures and Magma Composition in the Faial Volcanic System, Azores
TL;DR: In this paper, the authors investigate how variable the magmatic and tectonic processes are in space and time and how they interact, based on bathymetric, geophysical, geochemical and Sr-Nd-Pb isotope data from Faial Island and the surrounding seafloor.
Journal ArticleDOI
Volcano-tectonic evolution of a linear volcanic ridge (Pico-Faial Ridge, Azores Triple Junction) assessed by paleomagnetic studies
Pedro Silva,Pedro Silva,Bernard Henry,Fernando O. Marques,A. Hildenbrand,Ana Rita Lopes,Ana Rita Lopes,Pedro Madureira,José Firmino Aguilar Madeira,João Carlos Nunes,Zuzana Roxerová +10 more
TL;DR: In this paper, the analysis of the paleomagnetic directions obtained on well-dated volcanic rocks is used as a tool to assess tilting related to tectonics and large-scale volcano instability along the Pico-Faial linear volcanic ridge (Azores Triple Junction, Central North Atlantic).
Journal ArticleDOI
Helium isotope systematics in the vicinity of the Azores Triple Junction : constraints on the Azores geodynamics
Pedro Madureira,Manuel Moreira,João Mata,João Carlos Nunes,Cécile Gautheron,Nuno Lourenço,Rosário Carvalho,Manuel Pinto de Abreu +7 more
TL;DR: In this paper, He isotopic data from subaerial and submarine samples collected along the Terceira Rift (Azores Plateau) in order to constrain the sources involved in the Azores magmatism in the unique geodynamic context of Azores triple junction is presented.
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