Crustal structure under the central High Atlas Mountains (Morocco) from geological and gravity data

Ayarza, P.; Álvarez-Lobato, F.; Teixell, Antonio; Arboleya, María Luisa; Tesón, Eliseo; Julivert, Manuel; Charroud, Mohammed

doi:10.1016/j.tecto.2005.02.009

Cited by 92 publications

(80 citation statements)

References 29 publications

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“…As a compressional belt, the High Atlas exhibits a relatively small crustal root that contributes to the mountain topography, as revealed by gravity [7], lowresolution [8], [11] and a high resolution wide-angle reflection seismic experiment [28]. However, the total elevation of the Atlas system (where the mean altitude of the mountain belts exceeds 2000 m over large areas and some of the undeformed foreland basins stand above 1200 m) is only partially explained by shortening and crustal thickening, being the system in a state of isotactic under-compensation at the crustal scale [5], [7], [15], [29].…”

Section: Geological Settingmentioning

confidence: 99%

“…However, the total elevation of the Atlas system (where the mean altitude of the mountain belts exceeds 2000 m over large areas and some of the undeformed foreland basins stand above 1200 m) is only partially explained by shortening and crustal thickening, being the system in a state of isotactic under-compensation at the crustal scale [5], [7], [15], [29].…”

Section: Geological Settingmentioning

confidence: 99%

“…A Bouguer anomaly of about -120 mGal [7]- [9], implies that the observed crustal thickness is not sufficient to compensate the topography.…”

mentioning

confidence: 99%

“…All these uncommon features make this orogen very attractive for diverse studies, like field investigations mostly of structural geology since 1976 by Michard [10], and later by other authors [4], [5], gravimetric crustal model calculation [7], [9], [11], teleseismic P wave tomography [12], magnetotelluric investigations [1], [13], [14] low-resolution seismic refraction profile [8], [15], receiver functions analysis [16], [17], GPS measurements [18] and potential fieldbased lithospheric model [19]. Yet the Atlas Mountains are still the subject of ongoing research in an effort to constrain the deep structure in which most models have their basis [20] but also the velocity structure of its upper subsurface.…”

mentioning

confidence: 99%

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New numerical and theoretical model to characterize the upper crustal structure of the Moroccan atlas from wide-angle seismic reflection data

Ouraini¹,

Gueraoui²,

Ayarza³

et al. 2015

ces

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Section: Geological Settingmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

“…A Bouguer anomaly of about -120 mGal [7]- [9], implies that the observed crustal thickness is not sufficient to compensate the topography.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

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New numerical and theoretical model to characterize the upper crustal structure of the Moroccan atlas from wide-angle seismic reflection data

Ouraini¹,

Gueraoui²,

Ayarza³

et al. 2015

ces

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“…Sandvol et al (1998) and van der Meijde et al (2003), using receiver functions, proposed the existence of multiple velocity jumps at the base of the crust, taken to imply duplication of the Moho discontinuity in the northern part of the High Atlas (35-38 km). Ayarza et al (2005) combined the previous geophysical results with gravity data and detailed geological cross sections of the area to obtain a crustal-scale density distribution model. In this model, Ayarza et al (2005) infer crustal-scale thrusting affecting the Moho and penetrating into the mantle.…”

Section: Introductionmentioning

confidence: 99%

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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Piecewise delamination of Moroccan lithosphere from beneath the Atlas Mountains

Bezada

Humphreys

Dávila

et al. 2014

Geochem. Geophys. Geosyst.

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The elevation of the intracontinental Atlas Mountains of Morocco and surrounding regions requires a mantle component of buoyancy, and there is consensus that this buoyancy results from an abnormally thin lithosphere. Lithospheric delamination under the Atlas Mountains and thermal erosion caused by upwelling mantle have each been suggested as thinning mechanisms. We use seismic tomography to image the upper mantle of Morocco. Our imaging resolves the location and shape of lithospheric cavities and of delaminated lithosphere 400 km beneath the Middle Atlas. We propose discontinuous delamination of an intrinsically unstable Atlas lithosphere, enabled by the presence of anomalously hot mantle, as a mechanism for producing the imaged structures. The Atlas lithosphere was made unstable by a combination of tectonic shortening and eclogite loading during Mesozoic rifting and Cenozoic magmatism. The presence of hot mantle sourced from regional upwellings in northern Africa or the Canary Islands enhanced the instability of this lithosphere. Flow around the retreating Alboran slab focused upwelling mantle under the Middle Atlas, which we infer to be the site of the most recent delamination. The Atlas Mountains of Morocco stand as an example of large-scale lithospheric loss in a mildly contractional orogen.

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Crustal structure under the central High Atlas Mountains (Morocco) from geological and gravity data

Cited by 92 publications

References 29 publications

New numerical and theoretical model to characterize the upper crustal structure of the Moroccan atlas from wide-angle seismic reflection data

New numerical and theoretical model to characterize the upper crustal structure of the Moroccan atlas from wide-angle seismic reflection data

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

Piecewise delamination of Moroccan lithosphere from beneath the Atlas Mountains

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