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
Citations
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Journal ArticleDOI
Submarine explosive volcanism in the southeastern Terceira Rift/São Miguel region (Azores)
TL;DR: In this article, the authors describe a study combining morphological data with high-resolution seismic reflection data collected over cones within the southeastern Terceira Rift, a succession of deep basins, volcanic bathymetric high and islands (e.g. Sao Miguel) representing the westernmost part of the Eurasian-Nubian plate boundary.
Journal ArticleDOI
Submarine sedimentation processes in the southeastern Terceira Rift/São Miguel region (Azores)
TL;DR: In this article, the authors focused on the impact of volcanism, erosion, tectonics, time-variant sediment supply and climatic/oceanographic conditions on the submarine sedimentation processes in the southeastern Terceira Rift (Azores Plateau).
Journal ArticleDOI
The role of lithospheric processes on the development of linear volcanic ridges in the Azores
TL;DR: In this article, a 3D finite-element representation of the brittle lithosphere and underlying ductile mantle is presented, where the brittle layer is described by an elastoplastic rheology with progressive damage and fractures are assumed to be analogous to localized shear bands.
Journal ArticleDOI
Insights into the Origins and Compositions of Mantle Plumes: A Comparison of Galápagos and Hawai'i
Karen S. Harpp,Dominique Weis +1 more
Journal ArticleDOI
Evolution of the accretion processes along the Mid-Atlantic Ridge north of the Azores since 5.5 Ma: An insight into the interactions between the ridge and the plume
TL;DR: In this paper, a period of increased magmatism was identified at the southern limit of the study area (near 40°N) around anomaly 5. This pulse probably marks the northernmost and last significant arrival of material from the Azores plume to the MAR axis.
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Journal ArticleDOI
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