Cenozoic alkaline volcanism of the Atakor massif, Hoggar, Algeria

Azzouni-Sekkal, Abla; Bonin, Bernard; Benhallou, Amel; Yahiaoui, Rachid; Liégeois, Jean-Paul

doi:10.1130/2007.2418(16)

Cited by 19 publications

(12 citation statements)

References 35 publications

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“…Magmatic activity in the Hoggar area began at the Eocene–Oligocene boundary ( ca . 34 Ma) and has continued until the present (Girod, ; Aït‐Hamou et al ., ; Liégeois et al ., ; Azzouni‐Sekkal et al ., ).…”

Section: Geological Settingmentioning

confidence: 99%

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Intraplate uplift: new constraints on the Hoggar dome from the Illizi basin (Algeria)

et al. 2016

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Section: Geological Settingmentioning

confidence: 99%

“…Hoggar, Tibesti, Darfur; Fig. ), consistent with the involvement of sublithospheric processes (Sahagian, ; Wilson & Guiraud, ; Burke, ; Liégeois et al ., ; Azzouni‐Sekkal et al ., ; Beccaluva et al ., ).…”

Section: Introductionmentioning

confidence: 99%

Intraplate uplift: new constraints on the Hoggar dome from the Illizi basin (Algeria)

et al. 2016

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“…The southwestern end of the fault is the continental-scale N-S oriented 4°50′ fault, at a distance of about 95 km from the center of the study area ( Figure 2). It represents the sharp eastern boundary of the Tahalra volcanic field on the Tefedest terrane, in which the latest eruption was as recent as the historical time [Assouni-Sekkal et al, 2007]. Relative to the Laouni terrane, the Tefedest has a much better developed brittle fault system ( Figure 2) [Ball, 1980;Liegeois et al, 2005].…”

Section: Introductionmentioning

confidence: 99%

Spatial variations of crustal characteristics beneath the Hoggar swell, Algeria, revealed by systematic analyses of receiver functions from a single seismic station

Liu

Gao

2010

Geochem Geophys Geosyst

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[1] The Hoggar swell in Algeria is one of the significant massifs of northwest Africa. The paucity of highresolution geophysical studies of the crust and mantle beneath the massifs is mostly responsible for the heated debates about the depth of the source region of the Cenozoic volcanism and the closely related uncertainty about the mechanism that formed and maintains the high elevation of the swells. Here we report results from a systematic study of 1386 high-quality receiver functions (RFs) recorded by station TAM, the only permanent broadband seismic station on the Hoggar swell. The resulting crustal thickness is about 34 km and the V p /V s is 1.77 when all the RFs from the station are stacked. Our study reveals a sharp contrast in the amplitude of the P-to-S converted phases between the volcanic, highly-fractured Tefedest terrane and the non-volcanic, less fractured Laouni terrane. The former has a stacking amplitude that is comparable to typical cratonic areas, and the latter has an amplitude that is only about 25% as large. Spatially consistent crustal thickness and an intermediate-mafic crust are inferred on the Tefedest terrane, while spatially variable crustal thickness and a felsic crust is inferred beneath the Laouni terrane. The observations can be best explained by a mantle-derived underplated magmatic layer beneath the mechanicallystronger Laouni terrane, and magmatic diking and resultant volcanism associated with the mechanically weaker Tefedest crust. The study demonstrated the significance of a long-running station in the investigation of spatial variations of crustal characteristics.

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“…In this scenario, we have to mention even the Hoggar volcanic activity. The Cenozoic alkaline volcanism of the Atakor massif (300 km far from the Amguid crater), has three main volcanic episodes [6].…”

Section: Foundations Of the Present Investigations And Studied Materialsmentioning

confidence: 99%

Mineralogical and Chemical Investigations of the Amguid Crater (Algeria): Is there Evidence on an Impact Origin?

et al. 2020

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Mineralogical and chemical investigations were carried out on intra-craterial bedrocks (Lower Devonian sandstone) and regolithic residual soil deposits present around the Amguid structure, to discuss the hypothesis of its formation through a relatively recent (about 0.1 Ma) impact event. Observations with an optical microscope on intra-craterial rocks do not unequivocally confirm the presence of impact correlated microscopic planar deformation features (PDFs) in quartz crystals. Field observations, and optical and instrumental analysis (Raman spectroscopy) on rocks and soils (including different granulometric fractions) do not provide any incontrovertible pieces of evidence of high energy impact effects or products of impact (e.g., high pressure-temperature phases, partially or totally melted materials, etc.) either in target rocks or in soils. A series of selected main and trace elements (Al, Fe, Mg, Ni, Co and Cu) were analysed on rocks and soils to evaluate the presence in these materials of extraterrestrial sources. Comparative chemical data on rocks and soils suggest that these last are significantly enriched in Fe-poor Mg-rich materials, and in Co, Ni and Cu, in the order. A large number of EDAX-SEM analyses on separated soil magnetic particles indicate an abnormally high presence of Al-free Mg-rich sub-spherical or drop-like silicate particles, showing very similar bulk chemistries compatible with forsterite olivine. Some particles were found associated with a Ni-rich iron metal phase, and this association suggests a specific extraterrestrial origin for them. Electron microscope analysis made on a large number of soil magnetic particles indicates that 98% of them are terrestrial phases (almandine garnet, tourmaline and Fe-oxides, in abundance order), whereas, only a few grains are of questionable origin. One of the Mg-rich silicate particles was found to be a forsterite (Mg = 0.86) Mn-rich (MnO: 0.23%) Cr-free olivine, almost surely of extraterrestrial sources. Electron microprobe analysis of three soil particles allowed identification of uncommon Cr-rich (Cr 2 O 3 about 8%) spinels, poorly compatible with an origin from terrestrial sources, and in particular from local source rocks. We propose a specific extraterrestrial origin for sub-spherical olivine particles characterised by quite similar magnesian character. Excluding any derivation of these particles from interplanetary dust, two other possible extraterrestrial sources should be considered for them, i.e., either normal micrometeorite fluxes or strongly un-equilibrated, or the Vigarano type Carbonaceous (CV) chondrite meteorite material. In this case, further studies will confirm an impact origin for Amguid, as such magnesian olivine components found in soils might represent the only remnants of a vaporised projectile of ordinary non-equilibrated meteoritic composition.

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Cenozoic alkaline volcanism of the Atakor massif, Hoggar, Algeria

Cited by 19 publications

References 35 publications

Intraplate uplift: new constraints on the Hoggar dome from the Illizi basin (Algeria)

Intraplate uplift: new constraints on the Hoggar dome from the Illizi basin (Algeria)

Spatial variations of crustal characteristics beneath the Hoggar swell, Algeria, revealed by systematic analyses of receiver functions from a single seismic station

Mineralogical and Chemical Investigations of the Amguid Crater (Algeria): Is there Evidence on an Impact Origin?

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