Flow of Canary mantle plume material through a subcontinental lithospheric corridor beneath Africa to the Mediterranean

Duggen, Svend; Hoernle, Kaj; Hauff, Folkmar; Klügel, Andreas; Bouabdellah, Mohammed; Thirlwall, M. F.

doi:10.1130/g25426a.1

Cited by 131 publications

(159 citation statements)

References 31 publications

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“…As for the Canary Islands, the existence of a mantle plume is more debated, but many have related their volcanism to a mantle plume activity (e.g. Hoernle and Schmincke, 1993;Carracedo et al, 1998;Duggen et al, 2009). Both the volcanic islands have developed rift zones (Fig.…”

Section: Volcano-tectonic Settingmentioning

confidence: 99%

Basaltic feeder dykes in rift zones: geometry, emplacement, and effusion rates

Galindo

Guðmundsson

2012

Nat. Hazards Earth Syst. Sci.

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Abstract. Most volcanic hazards depend on an injected dyke reaching the surface to form a feeder. Assessing the volcanic hazard in an area is thus related to understanding the condition for the formation of a feeder dyke in that area. For this latter, we need good field data on feeder dykes, their geometries, internal structures, and other characteristics that distinguish them from non-feeders. Unfortunately, feeder dykes are rarely observed, partly because they are commonly covered by their own products. For this reason, outcrops are scarce and usually restricted to cliffs, ravines, and man-made outcrops. Here we report the results of a study of feeder dykes in Tenerife (Canary Islands, Spain) and Iceland, focusing on their field characteristics and how their propagation is affected by existing structures. Although Holocene fissure eruptions have been common in both islands, only eleven basaltic feeder dykes have been identified: eight in Tenerife and three in Iceland. They are all well preserved and the relation with the eruptive fissure and/or the deposits is well exposed. While the eruptive fissures are generally longer in Iceland than in Tenerife, their feeders show many similarities, the main ones being that the feeder dykes (1) are generally sheet-shaped; (2) are segmented (as are the associated volcanic fissures); (3) normally contain elongated (prolate ellipsoidal) cavities in their central, topmost parts, that is, 2-3 m below the surface (with solidified magma drops on the cavity walls); (4) contain vesicles which increase in size and number close to the surface; (5) sometimes inject oblique dyke fingers into the planes of existing faults that cross the dyke paths; and (6) may reactivate, that is, trigger slip on existing faults. We analyse theoretically the feeder dyke of the 1991 Hekla eruption in Iceland. Our results indicate that during the initial peak in the effusion rate the opening (aperture) of the feeder dyke was as wide as 0.77 m, but quickly decreased to about 0.56 m. During the subsequent decline in the effusion rate to a minimum, the aperture decreased to about 0.19 m. At a later abrupt increase in the effusion rate, the feeder-dyke opening may have increased to about 0.34 m, and then decreased again as the effusion rate gradually declined during the end stages of the eruption. These thickness estimates fit well with those of many feeders in Iceland and Tenerife, and with the general dyke thickness within fossil central volcanoes in Iceland.

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Section: Volcano-tectonic Settingmentioning

confidence: 99%

Basaltic feeder dykes in rift zones: geometry, emplacement, and effusion rates

Galindo

Guðmundsson

2012

Nat. Hazards Earth Syst. Sci.

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“…For the same reason we cannot confirm the continuation of this low velocity anomaly to the west into the Canary Islands, as the model below 300 km seems to indicate. Some authors have proposed the existence of a corridor in the sublithospheric mantle extending from the Canary Islands to the Alboran sea that would be responsible for the observed Cenozoic volcanism in Morocco (Duggen et al, 2009). Oyarzun et al (1997) propose that volcanism in western North Africa and in the European Cenozoic rift systems (Goes et al, 1999;Ziegler, 1992) …”

mentioning

confidence: 99%

Subduction and volcanism in the Iberia–North Africa collision zone from tomographic images of the upper mantle

et al. 2015

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Subduction and volcanism in the Iberia-North Africa collision zone from tomographic images of the upper mantle, Tectonophysics (2015Tectonophysics ( ), doi: 10.1016Tectonophysics ( /j.tecto.2015 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT2 AbstractNew tomographic images of the upper mantle beneath the westernmost Mediterranean suggest that the evolution of the region experienced two subduction-related episodes. First subduction of oceanic and/or extended continental lithosphere s, now located mainly beneath the Betics at depths greater than 400 km, took place on a NW-SE oriented subduction zone. This was followed by a slab-tear process that initiated in the east and propagated to the west, leading to westward slab rollback and possibly lower crustal delamination. The current position of the slab tear is located approximately at 4W, and to the west of this location the subducted lithosphere is still attached to the surface along the Gibraltar arc. Our new P-wave velocity model is able to image the attached subducted lithosphere as a narrow high-velocity body extending to shallow depths, coinciding with the region of maximum curvature of the Gibraltar Arc, the occurrence of intermediate-depth earthquakes, and anomalously thick crust. This thick crust has a large influence in the measured teleseismic travel time residuals and therefore in the obtained Pwave tomographic model. We show that removing the effects of the thick crust significantly improves the shallow images of the slab and therefore the interpretations based on the seismic structure.

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“…These features coincide with a marked lithospheric thinning that has been modelled with potential fields Zeyen et al, 2005;Fullea et al, 2007), and has been associated either to Canary mantle plume flow beneath Africa (Duggen et al, 2009 or to the interplay between the Alpine contractional structures and the thermal erosion of the lithosphere (Berger et al, 2009). In either case, all authors agree that the velocity anomalies originate by low degree partial melting of sublithospheric mantle sources (Raffone et al, 2009;Duggen et al, 2009;Bouabdellah et al, 2010;El Azzouzi et al, 2010). The amount of partial melting necessary to explain the electrical resistivity observed in structure A (2-5 m) is between 2% and 8% according to the Modified Brick Layer Model (MBLM) suggested by (Partzsch et al (2000).…”

Section: Lower Crustmentioning

confidence: 62%

“…At deeper levels, the electrical resistivity model across the central Atlas in Morocco reveals two major resistivity anomalies at lower crustal depths. The first one, below the Moulouya plain, we interpret as due to the presence of small amounts of partial melt in the Atlas crustal root, the consequence of either the Canary mantle plume flow (Duggen et al, 2009) or thermal erosion of a metasomatized lithosphere (Berger et al, 2009). The anomaly found below the Anti-Atlas could be due to either ancient subduction of oceanic sediments or to minerals precipitated from fluids released from the mantle during the Precambrian accretion of the Anti-Atlas to the West African super continent.…”

Section: Discussionmentioning

confidence: 97%

Electrical signature of modern and ancient tectonic processes in the crust of the Atlas mountains of Morocco

Ledo

Jones

Siniscalchi

et al. 2011

Physics of the Earth and Planetary Interiors

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a b s t r a c tThe Atlas Mountains in Morocco are considered as type examples of intracontinental mountain chains, with high topography that contrasts with moderate crustal shortening and thickening. Whereas recent geological studies and geodynamic modelling suggest the existence of dynamic topography to explain this apparent contradiction, there is a lack of modern geophysical data at the crustal scale to corroborate this hypothesis. To address this deficiency, magnetotelluric data were recently acquired that image the electrical resistivity distribution of the crust from the Middle Atlas to the Anti-Atlas, crossing the tabular Moulouya plain and the High Atlas. All tectonic units show different, distinct and unique electrical signatures throughout the crust reflecting the tectonic history of development of each one. In the upper crust, electrical resistivity values and geometries can be associated to sediment sequences in the Moulouya and Anti-Atlas and to crustal scale fault systems in the High Atlas developed likely during Cenozoic times. In the lower crust, the low resistivity anomaly found below the Moulouya plain, together with other geophysical (low velocity anomaly, lack of earthquakes and minimum Bouguer anomaly) and geochemical (Neogene-Quaternary intraplate alkaline volcanic fields) evidences, infer the existence of a small degree of partial melt at the base of the crust. Resistivity values suggest a partial melt fraction of the order of 2-8%. The low resistivity anomaly found below the Anti-Atlas may be associated with a relict subduction of Precambrian oceanic sediments, or to precipitated minerals during the release of fluids from the mantle during the accretion of the Anti-Atlas to the West African Supercontinent during the Panafrican orogeny (ca. 685 Ma).

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Flow of Canary mantle plume material through a subcontinental lithospheric corridor beneath Africa to the Mediterranean

Cited by 131 publications

References 31 publications

Basaltic feeder dykes in rift zones: geometry, emplacement, and effusion rates

Basaltic feeder dykes in rift zones: geometry, emplacement, and effusion rates

Subduction and volcanism in the Iberia–North Africa collision zone from tomographic images of the upper mantle

Electrical signature of modern and ancient tectonic processes in the crust of the Atlas mountains of Morocco

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