Abderrazak El Albani

• Professor
• Professor (Full) at Université de Poitiers

Tamdakht meteorite is the most massive observed fall in Morocco with a total recovered mass of ~500 kg. Most of the specimens investigated in this study are covered by a well‐developed primary fusion crust with thickness that reaches up to 12 mm. Macroscopic investigations reveal the development of complex fusion crust features indicative of unusua...

Proof of life on Earth is preserved in many methods but a common one is the mineralization of organic tissues by pyritization. Thus, pyrite permitted the preservation of traces of life in different environments from first steps of life development until present days. It is also the sink of trace elements that depend on many factors for their incorp...

Understanding the emergence and evolution of life is a fundamental question in exobiology and the early biosphere on Earth. One approach to elucidate the biogenicity criteria in early Earth involves the analysis of trace elements (e.g., As, Zn, Ni, Fe, Cu and Co) preserved in ancient marine sedimentary rocks. Hence, trace elements hold the unique p...

The concentration of redox sensitive trace metals and their isotopic composition preserved in Precambrian marine sediments, are critical for the reconstruction of ocean-atmosphere oxygenation history. Particularly, the concentration of Fe, its redox speciation, and isotopic distribution, have gained widespread use for inferring the biogeochemical p...

The concentration of redox sensitive trace metals (RSTEs) and their isotopic composition preserved in Precambrian marine sediments, are critical for the reconstruction of ocean–atmosphere oxygenation history. Particularly, the concentration of Fe, its redox speciation, and isotopic distribution, have gained widespread use for inferring the biogeoch...

Recent evidence from marine sedimentary rocks suggests that clay minerals were important in the supply of bioessential nutrients to seawater at the end of the Sturtian Snowball Earth glaciation that occurred ∼ 717–660 million years ago. However, little is known about the identity of these clay minerals, their abundance and distribution in the pre-g...

Knowledge of Cambrian animal anatomy is limited by preservational processes that result in compaction, size bias, and incompleteness. We documented pristine three-dimensional (3D) anatomy of trilobites fossilized through rapid ash burial from a pyroclastic flow entering a shallow marine environment. Cambrian ellipsocephaloid trilobites from Morocco...

Understanding the age of geological formations is essential to reconstruct Earth's history. Nevertheless, dating Proterozoic formations is a real challenge because they are often impacted by tectonic, magmatic or metamorphic phenomena. The sedimentary sequences of the Francevillian Basin are well preserved and have been dated previously using many...

Understanding the age of geological formations is essential to reconstruct Earth's history. Nevertheless, dating Proterozoic formations is a real challenge because they are often impacted by tectonic, magmatic or metamorphic phenomena. The sedimentary sequences of the Francevillian Basin are well preserved and have been dated previously using many...

It is thought that the global predominance of small-size unicellular prokaryotic life in the oceans until the emergence of large-size multicellular organisms to ecological dominance in the Ediacaran Ocean after 635 million years ago (Ma), was partly constrained by paleo-dynamic nutrient limitation, with phosphorus (P) being the principal limiting r...

The formation of chondrite materials represents one of the earliest mineralogical processes in the solar system. Phyllosilicates are encountered at various stages of the chondrule formation, from the initial stages (IDP agglomerates) to the final steps (chondrule internal alteration). While typically linked to aqueous alteration, recent studies rev...

Simple and horizontal trace fossils from the Ediacaran Period (635–538.8 Ma) compose some of the oldest ev- idence for the presence of metazoans in the Proterozoic fossil record. Unfortunately, various abiotic processes may produce similar structures on sedimentary beds. One of the oldest records of the Ediacaran biota from Western Gondwana is pres...

Marine sedimentary rocks deposited across the Neoproterozoic Cryogenian Snowball interval, ~720-635 million years ago, suggest that post-Snowball fertilization of shallow continental margin seawater with phosphorus accelerated marine primary productivity, ocean-atmosphere oxygenation, and ultimately the rise of animals. However, the mechanisms that...

The Anti-Atlas Mountains of Morocco preserve one of the most complete latest Neoproterozoic to Cambrian stratigraphic successions worldwide, with high-resolution chemostratigraphic δ13Ccarb coverage. However, the exact stratigraphic position of the Ediacaran–Cambrian boundary remains unresolved. Until now, no trace fossils or body fossils have been...

Recently, two independent studies suggest that the emergence of putative fossilized macro-eukaryotes in the Paleoproterozoic Francevillian Basin, ~2.1 billion years ago, may be related to a rise in seawater Zn bioavailability. This explanation is reliant on their extraordinary high Zn content and association with light Zn isotopes characteristic of...

Biogenic signatures in Precambrian rocks are often difficult to confirm and debatable. We present some unusual features associated with microbial-mat related structures (MRS) from the freshly-exposed rippled bed surface of 1.6 Ga old Chorhat Sandstone, Vindhyan Supergroup, India. The features discussed here, are present within intertidal to suprati...

The taphonomy of early soft-bodied organisms in Palaeoproterozoic sediments is not yet clearly understood, even though some locations where these fossils are found present all the conditions for exceptional fossil preservation. Indeed, the degree of fossil preservation has received attention, but better knowledge of the environmental conditions and...

Ancient aquatic sediments are critical archives for studying early microbial life and the types of environments in which they thrived. The recently characterized Amane Tazgart microbialites in the Anti-Atlas, Morocco, are a rare and well-preserved non-marine deposit that evolved in an alkaline volcanic lake setting during the Ediacaran Period. A mu...

Sediments from the 2.1- to 1.9-billion-year-old Francevillian Group in southeastern Gabon include centimeter-sized pyritized structures suggestive of colonial organisms (El Albani et al., 2010), some of which may have been motile (El Albani et al., 2019). However, these interpretations were largely based on morphological and geochemical characteris...

Biogenicity and taphonomy of the early life fossil records are debated as most of the previous studies focussed mainly on isotopes geochemistry. The non-metamorphosed Paleoproterozoic (~2.1 Ga) sedimentary succession of the Francevillian Basin (Gabon) contains the oldest complex multicellular organisms embedded in black shale facies. Several studie...

The sedimentary basin of Podillya (Volyno-Podillya-Moldavia) is situated in the southwest of the Ukrainian crystalline shield and belongs to the middle part of the Upper Neoproterozoic section of the Moguiliv-Podilska Group. By analyzing the primary oxide, trace, and rare-earth element compositions of the phosphate nodules in the area, this study s...

The Mesoproterozoic era is a crucial period in Earth history characterized by muted oxygen levels in the atmosphere-ocean system. This period is well represented in the non-metamorphosed sedimentary rocks from the Taoudeni Basin, Mauritania. Few studies have been carried out to trace the sources of these sedimentary archives. Here, we examined the...

The Igoudine and Amouslek formations (Terreneuvian-Cambrian Series 2 boundary) in the western Anti-Atlas of Morocco recorded the first replacement of microbial consortia (stromatolite dominated) by thrombolite-metazoans consortia. Carbonate and calcareous shales of both Formations have been analysed for major, trace, and rare earth elements to find...

The Igoudine and Amouslek formations (Terreneuvian-Cambrian Epoch 2 boundary) in the western Anti-Atlas of Morocco record the replacement of stromatolite-dominated microbial consortia by thrombolite-metazoan consortia. Carbonate and calcareous shales of both formations have been analyzed for major, trace, and rare earth elements to study their geoc...

Thrombolite reefs with archaeocyaths are common in the subtidal limestones of the lower Cambrian in the western Anti-Atlas of Morocco. The Igoudine Formation of the Tata Group recorded the first replacement of the microbial consortium (stromatolite-dominated) by thrombolite reefs with archaeocyaths and shelly metazoans. In order to better understan...

The Moroccan Anti-Atlas belt preserves an exceptional record of an Ediacaran microbial biosphere. TheAmane Tazgart Formation of the Ouarzazate Group corresponds to an Ediacaran volcanic alkaline lakedepositional system (ca. 571 Ma) where microbial buildups accreted in an extreme environment. Thesemicrobial accumulations are exceptional not only for...

Understanding paleoenvironmental dynamics linked to biological evolution in Earth history is a major goal within the geological community. The difficulty of achieving this goal, at least in part, lies with the secondary transformations experienced by a majority of ancient rocks, especially through metamorphism and hydrothermal activity. The Mesopro...

Thrombolite reefs with archaeocyaths are common in the subtidal limestones of the early Cambrian in the western Anti-Atlas of Morocco. The Igoudine Formation of Tata Group recorded the first replacement of the microbial consortium (stromatolite-dominated) by thrombolite reefs with archaeocyaths and shelly metazoans. Their growth took place under fa...

Taphonomy and mineralization of carbonated wood from the Purbeckian facies of l’Usine, Cherves-Richemont (Charente).

Water pollution is an increasing global concern affecting millions of people around the world, especially in arid to semi-arid areas. Management of water resources has become a crucial requirement for present times and specifically for future decades due to its detrimental impact on populations. The eastern High Atlas represents a demonstrative sit...

Understanding and reconstruction of the paleo-condition dynamics linked to biological evolution in Earth history remain a big challenge because a majority of the ancient rocks have been affected by secondary modification processes, including tectonic, metamorphic, and hydrothermal activities. This study examines the influence of magmatic intrusion...

The Anti-Atlas belt of Morocco preserves exceptional record of an Ediacaran microbial biosphere. The Amane Tazgart Formation of the Ouarzazate Group consist of an Ediacaran volcanic alkaline lake depositional system (ca. 571 Ma) were microbial buildups accreted in an extreme environment. These microbial accumulations are exceptional not only for th...

Although rare, sedimentary deposits containing exceptionally preserved fossils (i.e., Lagerstätten) have shaped our view on the history of life at particular intervals, such as those recording the Cambrian radiation of animals. Therefore, understanding the processes that lead to the fossilization of unmineralized tissues is crucial to better interp...

Biomineralized and organic metazoan tubular skeletons are by far the most common in the fossil record. However, several groups of organisms are also able to agglutinate particles to construct more rigid structures. Here we present a novel type of agglutinated tube from the austral and endemic palaeobiota of the Malvinokaffric realm (Devonian, Brazi...

The mineral paragenetic sequence of the 2.1-billion-year-old (Ga) Francevillian basin is important for understanding the diagenetic fluid history that allowed the preservation of the oldest ecosystem, including bacterial and more advanced forms of life in the $\mathrm{FB}_{2}$ Member. However, a full characterization of the clay mineralogy of the $...

Bakakas Mayika et al. (2020) inferred d13C heterogeneity in Paleopro-terozoic oceans based on the chemostratigraphic and sedimentologic study of a single drillcore of the Francevillian Group (FG) of Gabon, considered to record the end of the ca. 2.22-2.06 Ga Lomagundi carbon isotope excursion (LCIE). The authors concluded that while the shallow-mar...

A well preserved evidence for seepage and associated worm tubes has been found in a Miocene carbonate succession of the Anti-Atlas Mountain (Morocco). The succession up to 30m thick consists of variety of micritic carbonate deposits with interbeds of carbonate breccias, and clastic conglomerates with carbonate cements. The authigenic micritic carbo...

The Berda Formation corresponds to an inner-shelf stratigraphic equivalent of the Campanian-Maastrichtian outer-shelf Abiod Formation of Tunisia. The present work aims to carry out a sedimentological study of the lower unit (Upper Campanian) of Berda Formation limestones in order to interpret the limestone depositional environment and the origin of...

Emerging evidence suggests widespread ferruginous marine conditions promoted global seawater phosphate depletion and the maintenance of a low oxygen world at the start of the Neoproterozoic Era. However, the large-scale deposition of marine sedimentary Fe formations, as observed in the Paleoproterozoic, is rare in the early Neoproterozoic Era. We s...

The coexistence of motile macroorganisms and mat-building cyanobacteria in the Paleoproterozoic FB 2 Member of the Franceville sub-basin, Gabon, points to the possible emergence of multi-trophic-level biological interaction by 2.1 billion years (Ga) ago. However, it is uncertain how these shallow-marine communities acquired and cycled nitrogen, a k...

The early evolution of metazoans has been reconstructed by studies on exceptionally preserved molds in siliciclastic rocks from the Ediacaran Period. However, there remains considerable controversy regarding the formation mechanisms of this unusual ‘Ediacaran-style’ preservation. Proposed hypotheses usually include early authigenesis of minerals, b...

Precambrian filamentous microfossils are common and diverse. Nevertheless, their taxonomic assignment can be difficult owing to their overall simple shapes typically lacking in diagnostic features. Here, we report in situ communities of well-preserved, large filamentous impressions from the Ediacaran Itajaí Basin (ca 563 Ma) of Brazil. The filament...

Data from: In situ filamentous communities from the Ediacaran (~563 Ma) of Brazil. This data repository contains: Supplementary Material; Supplementary Table 1 - Database with the compiled size ranges of modern unbranched filamentous organisms; Supplementary Table 2 - Database with all the measurements from the IB filaments; Adobe illustrator fil...

The Ediacaran period coincides with the emergence of ancestral animal lineages and cyanobacteria capable of thriving in nutrient deficient oceans which together with photosynthetic eukaryotic dominance, culminated in the rapid oxygenation of the Ediacaran atmosphere. However, ecological evidence for the colonization of the Ediacaran terrestrial bio...

The eastern part of Morocco, surrounded by the High Atlas chain close to Errachidia, represents a very sensitive area in a semi-arid context. Average annual rainfall does not exceed 300 mm/year. Most of the regional water resources are linked to the aquifer systems in the Atlas area. The study site coincides with the Eastern Upper Guir Basin, one o...

The Avalon biota (Ediacaran Period, 570–559 Ma) marks the first appearance of macroscopic and complex benthic communities in the fossil record. This assemblage is known from a few localities worldwide, mainly in Canada and England. Here, we report for the first time the presence of Ediacaran macrofossils in deposits of similar age from Gondwana (It...

The sedimentary fabrics of Precambrian mat-related structures (MRS) represent some of the oldest convincing evidence for early life on Earth. The ca. 2.1 billion-year (Ga) old MRS in the FB2 Member of the Francevillian basin in Gabon has received considerable attention not only because they contain remnants of microbial mats that colonized large ar...

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Interactions and coordination between conspecific individuals have produced a remarkable variety of collective behaviours. This co-operation occurs in vertebrate and invertebrate animals and is well expressed in the group flight of birds, fish shoals and highly organized activities of social insects. How individuals interact and why they co-operate...

The Neoproterozoic Podillya sedimentary Basin is well known to the imprints of the Ediacaran soft-bodied fauna which were previously described by many ukrainian and foreign authors. At this period, fossil-rich siliciclastic sediments recognized as traces of early metazoans also contain evidence of significant microbiological activity. In these edia...

Palaeontological collections housing material from the Fezouata Shale Lagerstätte (Lower Ordovician, Morocco) are of a high scientific interest as they testify to the existence of Burgess Shale-type taxa in one of the most critical Palaeozoic period: the Cambrian–Ordovician transition. The preservation of this unique patrimony can benefit from the...

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Illitisation requires potassium incorporation into a smectite precursor, a process akin to reverse weathering. However, it remains unclear whether microbes facilitate K + uptake to the sediments and whether illitisation was important in the geological past. The 2.1 billion-year-old Francevillian Series of Gabon has been shown to host mat-related st...

La série du Francevillien datée de 2,1 milliards d'années au Gabon a reçu une attention considérable puisqu'elle héberge les plus vieux macro-organismes coloniaux de forme et de taille variées. Les échantillons ont été prélevés dans un intervalle de 20 mètres d'épaisseur. Les faciès les plus représentatifs correspondent à des grès et des black shal...

Significance The 2.1 billion-year-old sedimentary strata contain exquisitely preserved fossils that provide an ecologic snapshot of the biota inhabiting an oxygenated shallow-marine environment. Most striking are the pyritized string-shaped structures, which suggest that the producer have been a multicellular or syncytial organism able to migrate l...

The Neoproterozoic Era was characterized by rapidly changing paleogeography, global climate changes and especially by the rise and fall of the Ediacaran macro-biota. The correlation between disparate Ediacaran fossil-bearing localities and the tentative reconstruction of their paleoenvironmental and paleogeographic contexts are usually complicated...

The Great Oxidation Event (GOE) at 2.45 Ga facilitated the global expansion of oxidized compounds in seawater. Here, we demonstrate that the GOE coincided with a sharp increase in arsenate and arsenic sulfides in marine shales. The dramatic rise of these oxygen-sensitive tracers overlaps with the expansion of key arsenic oxidants, including oxygen,...

Les plus anciens fossiles connus datent du début du Précambrien il y a 3,5 Ga. Il s'agit d'organismes unicellulaires du groupe des procaryotes analogues aux bactéries actuelles, uni ou pluricellulaires, les Cyanobactéries, qui subsistent encore de nos jours. Ces cyanobactéries sont à l'origine de structures appelées stromatolithes. Ces derniers son...

La série Francevillienne datée de 2,1 milliards d'années au Gabon héberge les plus vieux macro-organismes coloniaux en association avec une grande diversité structurelle de voiles bactériens. Les échantillons ont été prélevés dans un intervalle de 20 mètres d'épaisseur. Les faciès les plus représentatifs correspondent à des grès et des black shales...

Abstract The field study and the petrographic observations of the limestone samples particularly from the Boukehil section allowthe identificationof four carbonate facies: (1) calcisphere-rich mudstone-wackestone, (2) Conglomeratic limestone, (3) bioclastic wackestone-packstone, and (4) siliceous dolostones. According to the vertical change of the...

Results of the nvestigation of crystal pseudomorphs and crystal casts found in a carbonate-chert facies from the 3.48 Ga-old Dresser Formation (Pilbara Craton, Australia), considered to host some of the oldest remnants of life. A combination of X-ray microtomography, energy-dispersive X-ray spectroscopy and crystallographic methods has been used to...

Crystallography has a long history of providing knowledge and methods for applications in other disciplines. The identification of minerals using X-ray diffraction is one of the most important contributions of crystallography to earth sciences. However, when the crystal itself has been dissolved, replaced or deeply modified during the geological hi...

Computed microtomography (XR-μCT) was used to study the three-dimensional morphology of Palaeoscolex cf. tenensis, a palaeoscolecid worm from the Lower Ordovician Fezouata Lagerstätte (Central Anti-Atlas, Morocco). This method revealed important aspects of its internal anatomy such as a pharynx bearing longitudinal rows of tiny teeth. Tubular struc...

The 2.1‐billion‐year‐old (Ga) Francevillian series in Gabon hosts some of the oldest reported macroscopic fossils of various sizes and shapes, stimulating new debates on the origin, evolution and organization of early complex life. Here, we document ten representative types of exceptionally well‐preserved mat‐related structures, comprising “elephan...

In his discussion, Pratt argues that a number of features characterizing the described facies can be interpreted as seismites. We thank him for highlighting this point and of course we agree that seismites in the FB unit of the Franceville Basin are highly probable, because deposition was contemporaneous to the activity of major faults in the vicin...

Bentonites are the alteration product of volcanic tephra typically preserved in low-energy, sedimentary environments below baseline. Although volcanic tuffs occur throughout the Earth's history, bentonites older than ca. 1.5 Ga have not been described. We present the mineralogy, geochemistry, and age data for K-bentonite beds within the FB Formatio...

Body fossils are described for the first time from the Upper Brioverian (Ediacaran-Fortunian) deposits of Central Brittany (NW France). The material consists of a dozen of specimens preserved on two slates, recently collected in a quarry in Saint-Gonlay. The fossils, centimetric in size, have an elliptical and acuminated outline, with a peripheral...

Microbial structures are ubiquitous in the fossil record for 3.7 billion years, but they have been inadequately described in studies of Paleoproterozoic rocks. The Francevillian Series (2.2 – 2.0 Ga, Gabon) has been intensively studied because of economic interests due to uranium or manganese ore deposits but also due to the large colonial macroorg...

A potential target setting for Europe to secure sustainable access to precious and modern technology metal resources is modern sea-floor massive sulfides (SMS) located on submarine arc-volcanoes. EPMA and LA-ICP-MS analyses of SMS from Kolumbo, the only known SMS deposits associated with thinned continental margin volcanism [1], show that pyrite, g...

The FC Formation of the Francevillian of Gabon displays the oldest Gunflint-type assemblage of microfossils that is hosted in shallow-water stromatolites. The FC Formation was deposited between 2.14 and 2.08 billion years ago (Ga), after the Great Oxygenation Event (∼2.4–2.3 Ga) and near the end of the Lomagundi event (∼2.3–2.06 Ga). Although they...

The depositional setting of the 2.1 Ga fill to the Franceville Basin of Gabon is important for understanding the habitat (energy and availability of light and oxygen) and taphonomy of recently discovered early macro-organisms buried in black shales in Unit FB. The available data bearing on the stratigraphy and sedimentology of Unit FB provide new i...

The depositional setting of the 2�1 Ga fill of the Franceville Basin of Gabon is important for understanding the habitat (energy and availability of light and oxygen) and taphonomy of recently discovered early macro-organisms buried in black shales in Unit FB. The available data bearing on the stratigraphy and sedimentology of Unit FB provide new i...

Purpose. It is based on investigation of regularities of distribution patterns of black shales in space and time in sections of the Late Proterozoic of the Transdniestria for further investigating by lithological, mineralogical, petrographical and geochemical analysis. Methodology. It consists of field working in outcrops of the Vendian section and...

80th Annual Meeting of the Meteoritical-Society, Santa Fe, NM, JUL 23-28, 2017

Red beds are extensively used as evidence for an oxygenated atmosphere in the Paleoproterozoic. Red beds in the unmetamorphosed, ca. 2.15 Ga FA Formation of the Franceville Basin, Gabon were geochemically, petrographically, and mineralogically characterized to constrain the process of their formation and their relationship to atmospheric oxygenatio...

The Eburnean orogeny in Africa results from the continental collision between the San Francisco and Congolian cratons. The different stages of this orogeny in Gabon are described from the initial rifting of the Archean continent with the crustal melting producing pre-Eburnean migmatites at 2450 Ma, the opening of an ocean. The eastward subduction o...

Dolomite concretions from Paleoproterozoic organic-rich sediments of the Franceville Basin (Francevillian) in southeastern Gabon are studied. These concretions, belonging to one of the rare well-preserved Proterozoic sediments in the world, are mainly observed in the shaly levels of the Francevillian B1 Formation. The concretions often show a centr...

Subaerial exposure and oxidation of organic carbon (Corg)-rich rocks is believed to be a key mechanism for the recycling of buried C and S back to Earth’s surface. Importantly, processes coupled to microbial Corg oxidation are expected to shift new biomass δ13Corg composition towards more negative values relative to source. However, there is scarci...

Inexpensive and easily available Moroccan natural clays were investigated for the removal availability of textile dyes from aqueous solution. For this purpose, the adsorption of methylene blue (MB) as reference molecule, malachite green (MG) representative of cationic dyes and methyl orange (MO) representative of anionic dyes, was studied in batch...

Significance Redox-sensitive transition metals and their isotopes provide some of the best lines of evidence for reconstructing early Earth’s oxygenation history, including permanent atmospheric oxygenation following the Great Oxidation Event (GOE), ∼2.45−2.32 Ga. We show a shift from dominantly negative to permanently positive copper isotope compo...