L'activité éruptive dans l'algérois : nouvelles données géochronologiques

Bellón, Hervé; Lepvrier, Claude; Magné, Jean; Raymond, Daniel P.

doi:10.3406/geolm.1977.1010

Cited by 7 publications

(3 citation statements)

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“…The Mitidja basin is characterized by the presence of magmatic rocks formations, ranging from 16 to 9 Ma old (Ait‐Hamou, ; Belanteur, ; Lepvrier et al, ). Petrographic and geochronologic studies show that rhyolites were first emplaced around 16 to 15 Ma, followed by andesites at 13–11 Ma and dacite around 9 Ma (Ait‐Hamou, ; Belanteur et al, ; Bellon et al, ; Hernandez & Lepvrier, ). In several places, the volcanic rocks are intercalated within the Miocene sedimentation.…”

Section: Geological Settingmentioning

confidence: 99%

“…A paleomagnetic study of favorable exposures of accessible Miocene volcanic sequences was performed in the Mitidja basin in an attempt to determine the magnitude, direction, and the spatial distribution of block displacements and/or rotations that may have accompanied or followed the crustal deformation (Figure ). Different volcanic sequences in the Mitidja basin are represented by rhyolite, andesite, and basalt sequences corresponding to the two groups of age (16–15 and 13–11 Ma) determined from isotopic dating (Ait‐Hamou, ; Belanteur et al, ; Bellon et al, ; Hernandez & Lepvrier, ).…”

Section: Paleomagnetic Sampling and Analytical Proceduresmentioning

confidence: 99%

“… Note . Sites with coordinates, emplacement age (A) with 1 and 2 indicating 16–15 and 13–12 Ma (Ait‐Hamou, ; Belanteur et al, ; Bellon et al, ; Hernandez & Lepvrier, ), respectively, number of samples (n) and of samples allowing reliable data (n ret ), NRM intensity (M) in 10 −3 A/m, dip value (P) and direction (G), declination (D) and inclination (I) before (D g , I g ) and after (D s , I s ) bedding correction, confidence angle (α 95 ), precision parameter (k), rotation angle (θ) with its uncertainty (Δθ) according to Demarest (). Orange color for sedimentary sites; italics for site with scattered directions (k < 40), bold for retained sites belonging to areas with large continuous outcrops.…”

Section: Paleomagnetic Sampling and Analytical Proceduresmentioning

confidence: 99%

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Strong Neotectonic Block Rotations, Related to the Africa‐Eurasia Convergence in Northern Algeria: Paleomagnetic Evidence From the Mitidja Basin

et al. 2019

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Significant tectonic clockwise rotations were evidenced in the Tell Atlas (Neogene Algerian Cheliff basin) by previous paleomagnetic studies. For northwestern Africa and in the context of the Africa-Eurasia convergence, they provided a new argument validating a kinematic model, based on transpression with shortening accommodated by clockwise block rotations. To corroborate this deformation pattern at a larger scale, new paleomagnetic studies were performed on 349 cores in the Mitidja basin, of Mio-Plio-Quaternary age, in the Algerian Tell Atlas. This intramontaneous basin is structured by two regional major E-W to WNW-ESE dextral shear zones. Primary magnetization data were obtained in 43 out of the 49 sampled sites. This magnetization is carried by Ti-poor titanomagnetite. Its direction shows that significant tectonic block rotations affected this basin since 16 Ma. Zones located between the E-W and WNW-ESE major structures are affected by coherent clockwise rotations (average magnitude of 48°) of large blocks, compartmented by presently associated sinistral NE-SW faults. Along the shearing structures, smaller blocks, resulting from the fragmentation of the large blocks, show various rotations, many of which are of large magnitude. These rotations, similar to those highlighted previously in the Cheliff basin, are interpreted as resulting from bookshelf, consequence of the Africa-Eurasia plates convergence in the Tell Atlas.

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Section: Geological Settingmentioning

confidence: 99%

Section: Paleomagnetic Sampling and Analytical Proceduresmentioning

confidence: 99%

Section: Paleomagnetic Sampling and Analytical Proceduresmentioning

confidence: 99%

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Strong Neotectonic Block Rotations, Related to the Africa‐Eurasia Convergence in Northern Algeria: Paleomagnetic Evidence From the Mitidja Basin

et al. 2019

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Hydrogeochemical and isotopic assessment for characterizing groundwater quality in the Mitidja plain (northern Algeria)

Yahiaoui

Meddi

Razack

et al. 2023

Environ Sci Pollut Res

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Neogene rotations of the Chenoua massif, northern Algeria, from remagnetizations

Aı̈fa

2013

Arab J Geosci

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International audienceThe tectonics of the Chenoua massif suggests block rotations of Neogene nappes associated with the African–European plate convergence. To estimate the extent of these rotations, a Paleomagnetic study on rhyolites and andesites of Langhian–Serravallian age and sandstones of Burdigalian age was carried out on 23 sites (200 specimens). The sites are distributed in the northwestern, southeastern and southern Chenoua massif. One or two components of magnetization, mainly carried by magnetite, pyrrhotite and/or hematite, were isolated in sandstones and volcanics. The sandstone sites reveal magnetizations in sandstones from the Cap Blanc syncline that are post-folding. However, both polarities are found, which is consistent with data from Africa during the Upper Miocene. Clockwise and counterclockwise rotations were recorded, dating back to the Neogene times in volcanics and sediments. From the faulted Cap Blanc syncline counterclockwise rotations of 1 ± 4° to 18 ± 28° around a vertical axis occurred in sediments since the Miocene with respect to Africa. In fact, remagnetizations occurred at several periods of time and in different sites, providing information on the evolution of post-tectonic rotations. Some volcanics record counterclockwise rotations of about 30° since the Miocene, whereas others do not show any significant rotation. This can be explained by the direction of the principal compressive stress axis σ 1 and by lateral extrusions related to an indentation model, in which we expect both clockwise and counterclockwise rotations

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L'activité éruptive dans l'algérois : nouvelles données géochronologiques

Abstract: La comparaison des données stratigraphiques, géochronologiques et géomagnétiques obtenues sur les laves et intrusions associées au Néogène des bassins tarditectoniques de l'Algérois permet de mettre en évidence trois paroxysmes éruptifs qui se situent entre -15,6 et -8,9 M.A.

Cited by 7 publications

References 0 publications

Strong Neotectonic Block Rotations, Related to the Africa‐Eurasia Convergence in Northern Algeria: Paleomagnetic Evidence From the Mitidja Basin

Strong Neotectonic Block Rotations, Related to the Africa‐Eurasia Convergence in Northern Algeria: Paleomagnetic Evidence From the Mitidja Basin

Hydrogeochemical and isotopic assessment for characterizing groundwater quality in the Mitidja plain (northern Algeria)

Neogene rotations of the Chenoua massif, northern Algeria, from remagnetizations

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