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Ediacaran biota and associated microbial matground in the Anti-Atlas (Morocco) :
Towards a complete snapshot of the ediacaran biosphere
El Kabouri J.1*, Errami E.1,2, Becker-Kerber B.3, Triantafyllou A.4, Ennih N.1, Youbi N.5, Zouicha
A.6, Fellah C.4 & Linnemann U.7
1 Faculté des Sciences, Université Chouaïb Doukkali, EGGPG, B.P. 20, 24000, El Jadida, Morocco
(jamalelkabouri1995@gmail.com)
2 Faculté Polydisciplinaire de Safi, Universit´e Cadi Ayyad, Got, B.P. 4162, 46 000, Safi, Morocco
3 Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials
(CNPEM)
4 Laboratoire de Géologie de Lyon (LGL-TPE), Lyon I University, Villeurbanne, France
5 Department of Geology, Faculty of Sciences-Semlalia, Cadi Ayyad University, Marrakech, Morocco
6 Geodynamic and Geomatic Laboratory, Department of Geology, ChouaïbDoukkali University, B.P. 20,
El Jadida, 24000, Morocco
7 SenckenbergNaturhistorischeSammlungen Dresden, Museum für Mineralogie und Geologie,
GeoPlasmaLab, KönigsbückerLandstraße 159, D-01109, Dresden, Germany
Abstract: The Neoproterozoic Era records the most important geological evolution in the history
of the Earth. This era marks a change in the Earth's geodynamic and biosphere, with the second
increase in oxygen dissolved in the ocean (Neoproterozoic Oxygenation Event), repeated glacial
periods, the appearance of the first multicellular lifeand the development of the
Gondwanasupercontinent. In particular, the Ediacaran period shows the first appearance of
abundant macroorganisms (Ediacaran biota) in an environment dominated by microbial
substrates. However, in the West African Craton, this assemblage of macro- and micro-organisms
is still poorly recorded; hence, its understanding is crucial to create a complete snapshot of the
Ediacaran ecosystem.
New surveys carried out in the Ediacaran sequence of the Ouarzazate Supergroup in the eastern
Anti-Atlas provide a record of typical Ediacaran macrofossils and microfossils associated with an
extensive microbial mat in shallow marine and terrestrial environments. In the shallow marine
siliciclastic and carbonate sediments of the Izelf Formation (567-550 Ma) (Ouarzazate Group,
Ougnat Enclave), we report for the first time a slightly diverse Ediacaran assemblage, including
Aspidella, Ivesheadiomorphs, frond-like organisms, Cf. Arkarua and other problematic structures
of probable biological origin. In association, spheroidal microfossils similar to acritarchs and
sulfur-oxidizing bacteria are preserved. Microbial mats recorded as stromatolites and microbially
induced sedimentary structures (MISS) are widespread in the shallow environment of marine,
lacustrine and fluvial sediments deposited in an active volcanic environment. MISS are recorded
over 20 Ma across up to 3 km of sediment. In the MISS archive, the reticular microbial mats
morphotype is dominant. This morphotype shows tufts, bubble structures and abundant sponge
pore fabric, indicating that they were formed by photosynthetic cyanobacteriamicro-organisms.
The widespread microbial mats in various paleoenvironments indicate that extensive microbial
activity was widespread in the marine and terrestrial environments of the Anti-Atlas. In
particular, the close association of Ediacaran biota with the MISS in the Izelf Formation provides
an example of interaction between macro-organism and microbial mats. The latter may also
corroborate the role of photosynthetic cyanobacterial mats in the production of oxygen oases
where multicellular organisms thrived during the Ediacaran Period.
Keywords: Ediacaran biota, Microbially induced sedimentary structures, Anti-Atlas, oxygen
oasis