The Sinemurian carbonate mud-mounds from central High Atlas (Morocco): stratigraphy, geometry, sedimentology and geodynamic patterns

Chafiki, Driss; Canérot, J.; Souhel, Abdellatif; Hariri, Khadija El; Eddine, K. Taj

doi:10.1016/j.jafrearsci.2004.07.063

Cited by 19 publications

(8 citation statements)

References 16 publications

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“…The variations in the shape of the stromatolitic laminations (sometimes within the same thin-section), from horizontal or undulated into inclined and curved (microdomical), as well as the emphasized layering aspect due to diVerent peloid/micrite packing density, generating lighter/darker bands, have been commonly documented in studies of stromatolites from diVerent ages and stratigraphical settings (e.g., Leinfelder et al 1993;ChaWki et al 2004;Riding and Tomás 2006;Mary and Woods 2008). The locally cuspate morphology and termination of laminae against massive micrite, suggest multiple episodes of growth and lithiWcation; the spongiostrome microfabric, exhibiting its characteristic sponge-like network of clotted micrite and irregular spar/microspar zones, coupled with an "over-imposed" banded fabric, is similar to many previously reported examples (see for instance Riding 2000;Flügel 2004; and references therein).…”

Section: Discussionmentioning

confidence: 99%

“…In fact, in the Moroccan High Atlas, the Early to Late Sinemurian transition is marked by the birth and growth of carbonate mudmounds (mainly sponge and thrombolite buildups, very rare stromatolites), which increase in size through time, with the Wrst and smaller structures corresponding to the latest Early Sinemurian (ChaWki et al 2004). The onset of this moundrich interval is considered by ChaWki et al (2004) to be closely linked to sea Xoor morphologic changes related to breakup of the extensive Moroccan Sinemurian shallow platform, with the mounds disappearing towards the Sinemurian-Pliensbaquian boundary when the establishment of a larger basin resulted in persistent hemipelagic silting conditions; Wilmsen and Neuweiler (2008) also relate these sedimentary and biotic changes at the Early-Late Sinemurian boundary of Morocco to a subsidence pulse and corresponding deepening trend, integrating them in a wider biosedimentological post-extinction context.…”

Section: The Sedimentary Succession-palaeoenvironmental Interpretatiomentioning

confidence: 99%

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Subtidal stromatolites from the Sinemurian of the Lusitanian Basin (Portugal)

Azerêdo

Silva

Duarte

et al. 2009

Facies

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Well-preserved dome-shaped carbonate stromatolites occur in the lowermost part of the Sinemurian of the Lusitanian Basin (Portugal), at S. Pedro de Moel region (W of the basin). Deposition in the region took place on a westward-dipping carbonate ramp. The stromatolitic mounds are not found anywhere else in the Sinemurian of the basin and therefore are regarded as speciWc bioevents. In contrast to marginal-marine stromatolitic crusts, subtidal carbonate mounds other than sponge-mounds have been seldom reported in the Lower Jurassic, in particular in the Sinemurian, either from Europe or North-Africa. Therefore, the case documented here contributes to enhance the knowledge on stromatolites of this age in the Peri-Tethyan and Proto-Atlantic regions. The depositional setting of the studied succession is interpreted as a mainly low-energy, restricted marine one, punctuated by higher-energy episodes and, locally, subjected to more open marine inXuence. The existence of a topographic high and detached shoals at a more distal location of the ramp is likely, considering regional seismic evidence, the record in oVshore (to the W) wells of peloidal/ooid wacke-packstones with detrital quartz and occurrence of a few ooid grainstones in the studied section. The inferred positive relief would act as a physical constraint that, coupled with the low-gradient of the ramp, deWned an embayment-like environment in which the prevailing ecological conditions must have been, for the part of the succession bearing the stromatolites, unfavorable for many benthic organisms, favoring the microbial community. The upper part of the succession suggests stepwise environmental openness to more marine inXuence alternating with frequent environmental restriction.

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Section: Discussionmentioning

confidence: 99%

Section: The Sedimentary Succession-palaeoenvironmental Interpretatiomentioning

confidence: 99%

Subtidal stromatolites from the Sinemurian of the Lusitanian Basin (Portugal)

Azerêdo

Silva

Duarte

et al. 2009

Facies

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“…Chafiki et al . (2004) found a deep‐water mound in the Lias of Morocco where the core of the build‐up was formed by sponges (hexactinellid and lithistids) and structures (stromatolites and thrombolites) of ‘algal origin’. However, they did not perform any sedimentological or geochemical study in order to discern the taxonomic identity of these microbialites.…”

Section: Discussionmentioning

confidence: 99%

From fossil associations to ecological communities: a case study from the ‘Cipit boulders’ of the upper Ladinian–lower Carnian St Cassian Formation, Dolomites, NE Italy

Sánchez‐Beristain

Reitner²

2021

LET

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The definition of a fossil ecological community from fossil associations has always been problematic. Determining coevality of the members of a fossil association has posed one of the most ravelling problems in this matter. However, in case of relicts of fossil reefs, this problem seems, to some extent, solvable due to the frequency of fossil findings in life position. In addition, the interaction between these fossils poses the possibility of performing statistical analyses in order to effectively quantify the relation that existed among the members of a fossil association as well as between fossil associations. In this paper, we present a method to obtain fossil communities by means of a combined algorithm (WPGMA‐Jaccard Index) performed onto 14 fossil associations from the Cipit boulders from the Middle‐to‐Late Triassic St Cassian Formation (Dolomites, Northeastern Italy), which have been previously reported in the literature. Presence/absence data of environmentally diagnostic micro‐encrusters and hexactinellid sponges were input into a matrix, which underwent cluster analysis. This analysis rendered a phenogram, where five different communities (phena) could be recognized. Each community has its particular palaeoenvironmental constraints, defined in turn by the particular array of micro‐encrusters/hexactinellid sponges. The method used in this work could be successfully applied in other Triassic reef deposits, taking into account the extensive amount of reports performed in the last decade.

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“…Another recent synthesis on the Atlas rifting by Laville et al (2004) leads to an interpretation rather different from that presented here. Numerous papers address the question of the successive sedimentary systems in the Tethyan Atlas, among which: i) for Lower and Middle Jurassic (Middle Atlas): Fedan (1989), Benshili (1989), Benshili & Elmi (1994), Charrière et al (1994a,b), Elmi (1999), El Arabi et al (1999, Charrière (2000), Akasbi et al (2001), EL Hammichi et al, 2002;for Lower to Middle Jurassic (High Atlas) : Jossen (1987), Warme (1988), Sadki (1992), El Kochri & Chorowicz (1996, Souhel et al (1998Souhel et al ( , 2000, Aït Addi et al (1998), Elmi et al (1999), Igmoullan et al (2001), Kaoukaya et al (2001), Neuweiler et al (2001), Milhi et al (2002), Mehdi et al (2003), Chafiki et al (2004), Ettaki & Chellai (2005), Aït Addi (2006).…”

Section: Early and Middle Jurassic: The Two Branches Of The Atlas Riftmentioning

confidence: 99%