Triassic Pollen Date Moroccan High Atlas and the Incipient Rifting of Pangea as Middle Carnian

Cousminer, Harold L.; Manspeizer, Warren

doi:10.1126/science.191.4230.943

Cited by 52 publications

(19 citation statements)

References 8 publications

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“…Permian sediments are present to the north of the study area, north of the Ourika-Zar Anticline, although they are absent from the Oukaimeden-Ourika Valley (Figure 4). Early or middle Triassic sediments have not been recorded to date in the Central High Atlas Basin (Cousminer and Manspeizer 1976). Formations F3 to F6 have been dated as late Triassic in age (Cousminer and Manspeizer 1976;Biron and Courtinat 1982).…”

Section: Stratigraphy and Depositional Environmentsmentioning

confidence: 97%

“…Due to a lack of an angular unconformity between Permian and Triassic rocks, and limited dating of this dominantly continental succession (Beauchamp 1988), the age of the series is only poorly constrained by available palaeontological (e.g. Dutuit 1976;Jalil and Janvier 2005), palynological (Cousminer and Manspeizer 1976;Olsen et al 2000) and radiometric data (Van Houten 1977).…”

Section: Stratigraphy and Depositional Environmentsmentioning

confidence: 98%

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Structural style and evolution of a Late Triassic rift basin in the Central High Atlas, Morocco: controls on sediment deposition

2009

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Late Triassic continental sediments deposited in an active-rift setting are exposed in the Oukaimeden-Ourika Valley, located in the Central High Atlas Basin of Morocco. The Oukaimeden Sandstone Formation is dominated by ephemeral and perennial braided fluvial facies, and is an outcrop analogue for Triassic sandstone hydrocarbon reservoirs found in Atlantic margin and North African basins. This paper documents detailed analysis of the outcrop data to investigate the influence of tectonics on deposition and the interplay with climatic controls. The geodynamic evolution of the basin is interpreted to be influenced by Atlantic rifting to the west and the formation of the Tethys Sea to the north, which led to the development of ENE and NNE striking normal faults. The present-day fault and outcrop geometry reflects later inversion due to the Alpine compression that led to uplift of the High Atlas and subsequent erosion.The ENE trending rift-basin is bound by normal faults, which are probably in part reactivated older Hercynian structures. The facies distribution was controlled by a complex interplay of tectonic and climatic controls. Evidence for syn-sedimentary movement of both fault sets is observed, with stratigraphic thickening and associated progressive change in bedding dip. These faults controlled the basin dimension, geometry of the half-graben and created the accommodation for sediment deposition. The presence of breccia deposits close to the main ENE bounding faults indicates footwall erosion and deposition of basin margin fans. The location and orientation of the main fluvial system was controlled by these structures, and the main channel belts ran parallel and proximal to the controlling faults, whereas away from the main syn-depositional faults overbank deposits dominate. Smaller contemporaneous NNE oriented faults are generally shorter with less throw, and had only a limited influence on gross sedimentation patterns. These faults are interpreted to be syn-sedimentary, displaying characteristics that suggest basal detachment within the Triassic, and as such provide evidence for the extension direction during late Triassic time. A periodic change from ephemeral to perennial systems, with associated changes in architectural style, is potentially attributed to climatic control, although a structural influence cannot be dismissed.

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Section: Stratigraphy and Depositional Environmentsmentioning

confidence: 97%

Section: Stratigraphy and Depositional Environmentsmentioning

confidence: 98%

Structural style and evolution of a Late Triassic rift basin in the Central High Atlas, Morocco: controls on sediment deposition

2009

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“…Ces dépôts sont constitués essentiellement par une puissante série carbonatée, généralement formée de dolomies bréchiques d'âge Lias inférieur. Cette couche aquifère renferme une importante nappe d'eau qui est retenue par un plancher imperméable constitué d'argilites rouges du Trias supérieur-Lias inférieur (Cousminer & Manspeizer, 1976 ;Biron & Courtinat, 1982 ;Baudelot et al, 1986 ;Sabaoui, 1987). Toutefois on constate d'autres circulations de celle-ci au niveau des basaltes tholeiitique de Mimet et de Bhalil, situées au NW et à l'W de ce bassin.…”

Section: Introductionunclassified

Rôle De La Fracturation Dans La Circulation Des Eaux Souterraines Et La Répartition Des Sources : Cas Du Bassin Hydrogéologique De Sefrou (Moyen Atlas Septentrional, Maroc)

Idrissi¹,

Hinaje

Cherai³

et al. 2016

ESJ

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The formation of the basin of Sefrou is related to the normal successive movements of the faults N130, N80, N30 and N170 which follow one another since the upper Miocene until the recent medium-Quaternary. Seeing the dynamic of groundwater in the carbonated lands (Liasic dolomites) is primarily guided by the fractures and the cracks; we propose to study the influence of brittle tectonics on the spatial organization of the flows and the relation of the groundwater circulation with the fracturing. The analysis of the fracturing (affecting the Flavio-lake and travertines deposits of plio-quaternary age and their Miocene and Jurassic substratum) and the structural cuts as well as the correlation of the piezometric map established from the piezometric reports with that of the fracturing, allowed us to note that the fractures play a very important part in the geometry of the Liasic aquifer and the mode of the circulation of groundwater. This circulation is dependent on the zones of weaknesses along the faults and fractures. Water European Scientific Journal August 2016 edition vol.12, No.24 ISSN: 1857 -7881 (Print) e -ISSN 1857 278 emergences are very variable and controlled by the paramount influence of the nature of the lithological formations and the tectonic structure on underground circulations. Indeed, the sources of water located in the basin of Sefrou are indexed, according to their origin, inside two types: sources of emergence and sources of discharge.Keywords: Moroccan Middle Atlas, Sefrou basin, brittle tectonic, Fracturing, groundwater circulation, sources RésuméLa formation du bassin de Sefrou est liée aux jeux normaux successifs des failles N130, N80, N30 et N170 qui se succèdent depuis le Miocène supérieur jusqu'au Quaternaire moyen-récent. Etant donné que la dynamique des eaux souterraines dans les terrains carbonatés (dolomies liasiques) est essentiellement guidée par les fractures et les fissures; nous nous proposons d'étudier l'influence de la tectonique cassante sur l'organisation spatiale des écoulements et la relation de la circulation des eaux souterraines avec la fracturation. L'analyse de la fracturation (affectant les dépôts fluvio-lacustres et travertinaux d'âge plio-quaternaire et leurs substratums miocène et jurassique) et des coupes structurales réalisées ainsi que la corrélation de la carte piézométrique établie à partir des relevées piézométriques avec celle de la fracturation, nous ont permis de constater que les fractures jouent un rôle très important dans la géométrie de l'aquifère liasique et le mode de la circulation des eaux souterraines. Cette circulation est tributaire des zones de faiblesses le long des failles et fractures. Les émergences d'eaux sont très variables et contrôlées par l'influence primordiale de la nature des formations lithologiques et de la structure tectonique sur les circulations souterraines. En effet, les sources d'eau repérées dans le bassin de Sefrou sont répertoriées, selon leur origine, à l'intérieur de deux types : sources d'émergence et sourc...

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“…This would account for much of the sediment which must have been eroded during the formation of the "K" un- to those documented in New England (deBoer, 1968;McHone, 1978) and Morocco (Cousminer and Manspeizer, 1976;Manspeizer et al, 1978).…”

Section: Velocity-lithofacies Mapsmentioning

confidence: 99%

“…Ballard and Uchupi (1975) (Cousminer and Manspeizer, 1976;Manspeizer et al, 1978). In New England, the graben-fill ranges in age from Late Triassic to Early Jurassic (Cornet and Traverse, 1975).…”

Section: Velocity-lithofacies Mapsmentioning

confidence: 99%

Geology of the passive margin off New England

Austin¹

1978

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Triassic Pollen Date Moroccan High Atlas and the Incipient Rifting of Pangea as Middle Carnian

Cited by 52 publications

References 8 publications

Structural style and evolution of a Late Triassic rift basin in the Central High Atlas, Morocco: controls on sediment deposition

Structural style and evolution of a Late Triassic rift basin in the Central High Atlas, Morocco: controls on sediment deposition

Rôle De La Fracturation Dans La Circulation Des Eaux Souterraines Et La Répartition Des Sources : Cas Du Bassin Hydrogéologique De Sefrou (Moyen Atlas Septentrional, Maroc)

Geology of the passive margin off New England

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