Nouvelles données géochronologiques et isotopiques sur le volcanisme cénozoïque de l'Ahaggar (Sahara algérien) :des arguments en faveur de l’existenced’un panache

Aït-Hamou, Farida; Dautria, Jean-Marie; Cantagrel, J. M.; Dostal, J.; Briqueu, Louis

doi:10.1016/s1251-8050(00)00217-2

Cited by 17 publications

(34 citation statements)

References 24 publications

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“…W2, W3 and W5 (this study); crosses: alkaline lavas from Gharyan, Libya (Beccaluva et al 2008). Fields of alkaline (Halliday et al 1990;Nkouathio et al 2008) and transitional (Moundi et al 2007) lavas from the Cameroon Volcanic Line, tholeiitic and alkaline lavas from Hoggar (in Aït-Hamou et al 2000) and Ethiopian flood basalts (Pik et al 1999) are given for comparison. b 208 Pb/ 204 Pb vs 206 Pb/ 204 Pb of Libyan volcanic rocks, compared to common mantle reservoirs.…”

Section: Sr Nd and Pb Isotopesmentioning

confidence: 99%

“…Crosses: as in a. Fields of alkaline lavas from the Cameroon Volcanic Line (Halliday et al 1990) and from Hoggar (Aït-Hamou et al 2000) plus Ethiopian flood basalts (Pik et al 1999) are given for comparison observed in W2 and W5, respectively. Isotope data are available only for two other Libyan samples, from Gharyan volcanic field (Beccaluva et al 2008) (Fig.…”

Section: Sr Nd and Pb Isotopesmentioning

confidence: 99%

“…Schilling 1973;White and McKenzie 1989;Marty et al 1993), Hoggar (e.g. Dupuy et al 1993;Aït-Hamou et al 2000), Sudan (e.g. Franz et al 1994) and Cameroon (e.g.…”

Section: Xenolith Versus Mantle Compositionmentioning

confidence: 99%

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Miocene to recent alkaline volcanism between Al Haruj and Waw an Namous (southern Libya)

Bardintzeff

Deniel

Guillou

et al. 2011

Int J Earth Sci (Geol Rundsch)

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International audienceUnspiked K-Ar ages, petrological, geochemical and isotopic data are reported on samples from southern Libya (Wan an Namous--Al Haruj area). The Wan an Namous intracaldera cone dated at 0.2 Ma consists of unusually undersaturated foidite, representing the most extreme compositions among Libyan and Tibestian lavas. A basanitic and a basaltic lava flow located north-west of Wan an Namous, and probably belonging to the Al Haruj volcanic field, were dated at 5.1 Ma and 8.1 Ma. These data extend the range of ages previously reported for Al Haruj lavas. REE and multi-element patterns are typical of alkaline intraplate magmas. Sr ratios range from 0.70314 to 0.70812, whereas Nd ratios are very homogeneous (0.51290-0.51293). Pb ratios (19.231 < 206Pb/204Pb < 19.547, 15.607 < 207Pb/204Pb < 15.641 and 38.859 < 208Pb/204Pb < 39.242) are typical of HIMU-FOZO compositions. Such isotope characteristics are very similar to those available on two Gharyan (northern Libya) lavas and largely overlap those of Hoggar and Cameroon Line alkaline rocks. These lavas were produced by low and variable degrees of partial melting of a garnet- and amphibole-bearing mantle source, constraining the depth of melting between 80 and 150 km. Crustal contamination was also probably involved for the oldest sample. Mineral compositions of a dunite-harzburgite xenolith clearly indicate that the lithospheric mantle was affected by partial melting and metasomatic processes by magmatic liquids, probably associated with the genesis of Cenozoic lavas. Lithospheric delamination and asthenospheric upwelling, due to the reactivation of lithospheric megastructures induced by the Africa-Europe convergence, could represent a model for the genesis of Libyan lavas, as in Hoggar

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Section: Sr Nd and Pb Isotopesmentioning

confidence: 99%

Section: Sr Nd and Pb Isotopesmentioning

confidence: 99%

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Miocene to recent alkaline volcanism between Al Haruj and Waw an Namous (southern Libya)

Bardintzeff

Deniel

Guillou

et al. 2011

Int J Earth Sci (Geol Rundsch)

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“…Chemical compositions of primitive mafic lavas of Djebel Taharaq volcanic complex (major elements are from Aït-Hamou et al (2000) and Aït-Hamou (2000). Sample Analyses reported by Aït-Hamou et al (2000) and b analyses reported by Dupuy et al (1993). Concentrations of Rb and Sr were determined by X-ray fluorescence.…”

Section: Discussionmentioning

confidence: 99%

“…Cenozoic intraplate magmatism in the Hoggar region ( Figure 1) started in the centre of the dome with the main magmatic episode that produced the Djebel Taharaq (Anahef) volcanic complex dated at about 34 Ma (Rognon et al 1983;Maza et al 1995;Aït-Hamou 2000;Aït-Hamou et al 2000). This volcanic centre is exposed over an area of about 400 km 2 and forms an eroded plateau 300-700 m high.…”

Section: Geologymentioning

confidence: 99%

Complex geometry of the Cenozoic magma plumbing system in the central Sahara, NW Africa

Keppie

Dostál

Murphy

2010

International Geology Review

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Topographic uplifts in the central Sahara occur in the Hoggar-Aïr and Tibesti-Gharyan swells that consist of Precambrian rocks overlain by Cenozoic volcanic rocks. The swells and associated Cenozoic volcanism have been related either to mantle plumes or to asthenospheric upwelling and to partial melting due to rift-related delamination along pre-existing Pan-African mega-shears during the collision between Africa and Europe. The Cenozoic volcanic rocks in the Hoggar generally range from Oligocene tholeiitic/transitional plateau basalts, which occur in the centre of the dome, to Neogene alkali basalts characterized by a decrease in their degree of silica undersaturation and an increase in their La/Yb ratios. The alkali basaltic rocks occur mainly along the margins of the dome and typically have less radiogenic Nd and Sr isotopic ratios than the tholeiitic/ transitional basalts. The geochemistry of the most primitive basaltic rocks resembles oceanic island basalt (OIB) tholeiitic -in particular high-U/Pb mantle (HIMU)-type -and is also similar to those of the Circum-Mediterranean Anorogenic Cenozoic Igneous (CiMACI) province. These characteristics are consistent with, but do not require, a mantle plume origin. Geophysical data suggest a combination of the two mechanisms resulting in a complex plumbing system consisting of (a) at depths of 250-200 km, an upper mantle plume (presently under the Aïr massif); (b) between 200 and 150 km, approximately 700 km northeastward deflection of plume-derived magma by drag at the base of the African Plate and by mantle convection; (c) at approximately 150 km, the magma continues upwards to the surface in the Tibesti swell; (d) at approximately 100 km depth, part of the magma is diverted into a low S-wave velocity corridor under the Sahara Basin; and (e) at approximately 80 km depth, the corridor is tapped by Cenozoic volcanism in the Hoggar and Aïr massifs that flowed southwards along reactivated Precambrian faults.

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The South West Atakor Volcanic District (Hoggar-Algeria): Petrography and Mineralogy from the Taessa Lavas

Benhallou

Megueni

Boussisse

et al. 2019

Advances in Science, Technology &Amp; Innovation

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Nouvelles données géochronologiques et isotopiques sur le volcanisme cénozoïque de l'Ahaggar (Sahara algérien) :des arguments en faveur de l’existenced’un panache

Cited by 17 publications

References 24 publications

Miocene to recent alkaline volcanism between Al Haruj and Waw an Namous (southern Libya)

Miocene to recent alkaline volcanism between Al Haruj and Waw an Namous (southern Libya)

Complex geometry of the Cenozoic magma plumbing system in the central Sahara, NW Africa

The South West Atakor Volcanic District (Hoggar-Algeria): Petrography and Mineralogy from the Taessa Lavas

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