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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

TLDR
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.

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Source to surface model of monogenetic volcanism: a critical review

TL;DR: Small-scale volcanic systems are commonly monogenetic in the sense that they are represented at the Earth's surface by fields of small volcanoes, each the product of a temporally restricted eruption of a compositionally distinct batch of magma, and this is in contrast to relatively large edifices built by multiple eruptions over longer periods of time involving magmas with diverse origins.
Journal ArticleDOI

Is the ‘Azores Hotspot’ a Wetspot? Insights from the Geochemistry of Fluid and Melt Inclusions in Olivine of Pico Basalts

TL;DR: In this article, He isotope and major, trace and volatile element compositions for basaltic scoriae from five monogenetic cones emplaced along the fissure zone of Pico Island, the youngest island of the Azores archipelago.
Journal ArticleDOI

Global gravity, bathymetry, and the distribution of submarine volcanism through space and time

TL;DR: In this paper, the authors used the satellite-derived gravity anomaly to predict the bathymetry for different values of Te, which is a proxy for the long-term strength of the lithosphere.
References
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Journal ArticleDOI

Revised plate motions relative to the hotspots from combined Atlantic and Indian Ocean hotspot tracks

TL;DR: In this paper, the authors used an updated model for global relative plate motions during the past 130 m.y.p. together with a compilation of bathymetry and recently published radiometric dates of major hotspot tracks to derive a plate-motion model relative to major hotspots in the Atlantic and Indian oceans.
Journal ArticleDOI

Current plate velocities relative to the hotspots incorporating the NUVEL-1 global plate motion model

TL;DR: The NUVEL-1 model is incorporated into HS2-NUVEL1, a global model for plate velocities relative to hotspots as discussed by the authors, and the results thus obtained are compared with those of the AM1-2 model of hotspot-relative plate velocity.
Journal ArticleDOI

Hotspot Tracks and the Early Rifting of the Atlantic

TL;DR: In this paper, the authors reconstruct the motion of the continents over hotspots for the past 200 million years and find that the relative motions of the plates are determined from magnetic anomaly isochrons in the oceans.
Journal ArticleDOI

Evidence from gravity data for focused magmatic accretion along the Mid-Atlantic Ridge

TL;DR: Gravity data from the Mid-Atlantic Ridge between latitudes 27°50′N and 30°40′N show that the accretion of magma at the ridge is focused at discrete centres along the spreading axis as mentioned in this paper.
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