Iron-framboids in the hydrocarbon-related Middle Devonian Hollard Mound of the Anti-Atlas mountain range in Morocco: Evidence of potential microbial biosignatures

Cavalazzi, Barbara; Barbieri, Roberto; Cady, Sherry L.; George, Annette D.; Gennaro, S.; Westall, Francès; Lui, A.; Canteri, R.; Rossi, Angelo Pio; Ori, G. G.; Taj-Eddine, Kamal

doi:10.1016/j.sedgeo.2011.09.007

Cited by 53 publications

(40 citation statements)

References 54 publications

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“…2B). Degraded diatoms present in close proximity to iron (oxyhydr)oxide spheroids lend support for the hypothesis that spheroids may be a biomediated mineral habit (Cavalazzi et al, 2012; Table 1, Fig. 3D).…”

Section: Interpretation Of Modern and Ancient Tufas And Brushy Basin supporting

confidence: 56%

“…These are spatially associated with framboidal structures that are hypothesized biomediated iron (oxyhydr)oxide habits [and likely iron (oxyhydr)oxide pseudomorphs after pyrite precipitated by sulfur-reducing bacteria; Table 1, Fig. 3C; e.g., Popa et al, 2004;Cavalazzi et al, 2012]. Diatoms are present in the unlithified sample from the spring vent (Table 1, Fig.…”

Section: Interpretation Of Modern and Ancient Tufas And Brushy Basin mentioning

confidence: 99%

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Textural and Mineralogical Characteristics of Microbial Fossils Associated with Modern and Ancient Iron (Oxyhydr)Oxides: Terrestrial Analogue for Sediments in Gale Crater

2014

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Iron (oxyhydr)oxide microbial mats in modern to *100 ka tufa terraces are present in a cold spring system along Ten Mile Graben, southeastern Utah, USA. Mats exhibit morphological, chemical, and textural biosignatures and show diagenetic changes that occur over millennial scales. The Jurassic Brushy Basin Member of the Morrison Formation in the Four Corners region of the USA also exhibits comparable microbial fossils and iron (oxyhydr)oxide biosignatures in the lacustrine unit.Both the modern spring system and Brushy Basin Member represent alkaline, saline, groundwater-fed systems and preserve diatoms and other similar algal forms with cellular elaboration. Two distinct suites of elements (1. C, Fe, As and 2. C, S, Se, P) are associated with microbial fossils in modern and ancient iron (oxyhydr)oxides and may be potential markers for biosignatures. The presence of ferrihydrite in *100 ka fossil microbial mats and Jurassic rocks suggests that this thermodynamically unstable mineral may also be a potential biomarker.One of the most extensive sedimentary records on Mars is exposed in Gale Crater and consists of non-acidic clays and sulfates possibly of lacustrine origin. These terrestrial iron (oxyhydr)oxide examples are a valuable analogue because of similar iron-and clay-rich host rock compositions and will help (1) understand diagenetic processes in a non-acidic, saline lacustrine environment such as the sedimentary rocks in Gale Crater, (2) document specific biomediated textures, (3) demonstrate how biomediated textures might persist or respond to diagenesis over time, and (4) provide a ground truth library of textures to explore and compare in extraterrestrial iron (oxyhydr)oxides, where future explorations hope to detect past evidence of life.

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Section: Interpretation Of Modern and Ancient Tufas And Brushy Basin supporting

confidence: 56%

Section: Interpretation Of Modern and Ancient Tufas And Brushy Basin mentioning

confidence: 99%

Textural and Mineralogical Characteristics of Microbial Fossils Associated with Modern and Ancient Iron (Oxyhydr)Oxides: Terrestrial Analogue for Sediments in Gale Crater

2014

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“…The occurrences of numerous pyrite framboids with diameters less than 10 μm (Figures 3(b),(e) and 4(a)-(c)) suggest the vital function of microbial activities in depositional process of seep carbonates. Previous studies found that the microbial pyrite frambiods have complex inner fabrics [20,[49][50][51]. Pyrite frambiods with sunflower-like fabric composed of elongated crystals as the outer part and granular crystals as the central part were observed in Xigaze seep carbonates ( Figure 4(c)).…”

Section: Formation Conditions Of Xigaze Seep Carbonatesmentioning

confidence: 84%

“…The diagnostic features of ancient seep carbonates commonly include low  13 C values of early diagenetic carbonate phases, special sedimentary fabrics such as clotted micrites, peloids and framboid pyrites, the occurrence of low diversity but high abundance faunal assemblage fossils and distinct 13 C-depleted biomarkers [10,13,14,[16][17][18][19][20][21]. Since the "seep-search strategy" was proposed by Campbell and Bottjer [22], more and more ancient seep deposits were discovered and studied.…”

Section: Hcomentioning

confidence: 99%

“…Since the "seep-search strategy" was proposed by Campbell and Bottjer [22], more and more ancient seep deposits were discovered and studied. Today, ancient hydrocarbon seeps have already been recognized from Devonian to Quaternary strata in almost all continents based on occurrences of seep carbonates and/or fossil chemosynthetic assemblages [10,13,14,[16][17][18][19][20][23][24][25][26][27][28]. However, seep carbonates are rarely found from ancient strata in the mainland China.…”

Section: Hcomentioning

confidence: 99%

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First discovery and characterizations of late Cretaceous seep carbonates from Xigaze in Tibet, China

Tong

Chen

2012

Chin. Sci. Bull.

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Hydrocarbon seeps, widely occurring in continental margins, have become increasingly focused owing to their close relationships with gas hydrates, strong greenhouse gas methane, and biological resources in extreme environments. Ancient hydrocarbon seeps have already been recognized from Devonian to Quaternary strata worldwide based on seep carbonates or seep-related fossil chemosynthetic assemblages. However, seep-related deposits are rarely found from ancient strata in the mainland China. Here, we report the first discovery of an ancient seep deposit, specifically late Cretaceous seep carbonates from Xigaze in Tibet, China. Xigaze seep carbonates, occurring as nodules, are enclosed in upper Cretaceous turbidite strata in Xigaze forearc basin. These carbonates are composed of authigenic carbonate (56.2% on average), clastic quartz and feldspar (27.3% on average), and clay minerals (chlorite, illite and smectite, 16.5% on average). Clotted micrites, peloids and framboid pyrites are frequently observed, all of which are common in modern seep carbonates. The carbonates have negative  13 C values varying from 27.7‰ to 4.0‰ (V-PDB), suggesting that thermogenic methane is the primary carbon source. Ce/Ce* values revised by eliminating La effects show no real Ce anomaly, indicating the carbonates were primarily precipitated in a weak reducing environment. Overall, these features provide unequivocal evidences that the seafloor of Xigaze forearc basin developed hydrocarbon seeps in late Cretaceous. seep carbonate, carbon isotope, sedimentary fabric, Xigaze, late Cretaceous Citation:Tong H P, Chen D F. First discovery and characterizations of late Cretaceous seep carbonates

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Early post‐embryonic trilobite stages and possible eggs from the ‘Túnel Ordovícico del Fabar’ (Middle Ordovician, northwestern Spain)

Bernárdez¹,

Esteve²,

Laibl³

et al. 2019

Fossils and Strata

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The sub-surface section of the Middle Ordovician Sueve Formation of the Cantabrian Zone, studied during the construction of a tunnel in the A-8 free highway of northern Spain, provided abundant fossiliferous horizons rich in trilobites of Darriwilian age. Fine-grained mudstones of the Cofiño Member delicately preserves a number of early stages of the calymenacean trilobite Prionocheilus mendax (Vaněk), from protaspides to meraspid degree 2, including in situ exuviae with disarticulated librigenae. From the upper part of the Bayo Member small clusters of pyrite spheres of ca. 0.5 mm in diameter are recorded, and may represent eggs of trilobites, being associated to the pliomerid Placoparia (Coplacoparia) tournemini (Rouault) in the same beds. The sphaeroids may represent the pyrite infilling of the internal cavity of possible eggs, and the covering is replaced by phyllosilicates. Differences in shape and size with presumed olenid eggs may be caused by the particular environmental adaptations of the latter group. The relatively large size of both the calymenid larvae and the pyritised ?eggs suggest a lecithothrophy development related with higher latitudes and/or with scarce or stationed organic matter.

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Iron-framboids in the hydrocarbon-related Middle Devonian Hollard Mound of the Anti-Atlas mountain range in Morocco: Evidence of potential microbial biosignatures

Cited by 53 publications

References 54 publications

Textural and Mineralogical Characteristics of Microbial Fossils Associated with Modern and Ancient Iron (Oxyhydr)Oxides: Terrestrial Analogue for Sediments in Gale Crater

Textural and Mineralogical Characteristics of Microbial Fossils Associated with Modern and Ancient Iron (Oxyhydr)Oxides: Terrestrial Analogue for Sediments in Gale Crater

First discovery and characterizations of late Cretaceous seep carbonates from Xigaze in Tibet, China

Early post‐embryonic trilobite stages and possible eggs from the ‘Túnel Ordovícico del Fabar’ (Middle Ordovician, northwestern Spain)

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