The Record of Environmental and Microbial Signatures in Ancient Microbialites: The Terminal Carbonate Complex from the Neogene Basins of Southeastern Spain

Bourillot, Raphaël; Vennin, Emmanuelle; Dupraz, Christophe; Pace, Aurélie; Foubert, Anneleen; Rouchy, Jean-Marie; Patrier, Patricia; Blanc, Philippe; Bernard, Dominique; Lesseur, Julien; Visscher, Pieter T.

doi:10.3390/min10030276

Cited by 18 publications

(14 citation statements)

References 103 publications

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“…Conventionally, such structures are understood to form via the entrapment of gas bubbles, anhydrite precipitation and desiccation frequently in combination with dissolution and subsequent compaction in peritidal to intertidal (microbial) environments (Shinn, 1968). More recently, Bourillot et al . (2020) provided more details and a number of distinguishing parameters indicating how these porous microbialites/stromatolites may form their laminated-micritic, laminated-peloidal microfabrics.…”

Section: Resultsmentioning

confidence: 98%

Keratose sponges in ancient carbonates – a problem of interpretation

Neuweiler

Kershaw

Boulvain

et al. 2022

Preprint

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Increasing current interest in sponge fossils includes numerous reports of diverse vermicular and peloidal structures interpreted as keratose sponges in Neoproterozoic to Mesozoic carbonates and in various open marine to peritidal and restricted settings. Reports of their occurrence are fundamental and far-reaching for understanding microfacies and diagenesis where they occur; and fossil biotic assemblages, as well as wider aspects of origins of animals, sponge evolution/ecology and the systemic recovery from mass extinctions. Keratose sponges: 1) have elaborate spongin skeletons but no spicules, thus lack mineral parts and therefore have poor preservation potential so that determining their presence in rocks requires interpretation; and 2) are presented in publications as interpreted fossil structures almost entirely in two-dimensional (thin section) studies, where structures claimed as sponges comprise diverse layered, network, particulate and amalgamated fabrics involving calcite sparite in a micritic groundmass. There is no verification of sponges in these cases and almost all of them can be otherwise explained; some are certainly not correctly identified. The diversity of structures seen in thin sections may be reinterpreted to include: a) meiofaunal activity; b) layered, possibly microbial (spongiostromate) accretion; c) sedimentary peloidal to clotted micrites; d) fluid escape and capture resulting in birdseye to vuggy porosities; and e) molds of siliceous sponge spicules. Without confirmation of keratose sponges in ancient carbonates, interpretations of their role in ancient carbonate systems, including facies directly after mass extinctions, are unsafe, and alternative explanations for such structures should be considered. This study calls for greater critical appraisal of evidence, to seek confirmation or not, of keratose sponge presence.

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Section: Resultsmentioning

confidence: 98%

Keratose sponges in ancient carbonates – a problem of interpretation

Neuweiler

Kershaw

Boulvain

et al. 2022

Preprint

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“…More recently, Bourillot et al . (2020) provided more details and a number of distinguishing parameters indicating that these porous microbialites/stromatolites may form laminated–micritic to laminated–peloidal microfabrics.…”

Section: Resultsmentioning

confidence: 99%

“…Conventionally, such structures are understood to form via the entrapment of gas bubbles, anhydrite precipitation and desiccation, frequently in combination with dissolution and subsequent compaction in supratidal to intertidal (microbial) environments (Shinn, 1968). More recently, Bourillot et al (2020) provided more details and a number of distinguishing parameters indicating that these porous microbialites/stromatolites may form laminatedmicritic to laminated-peloidal microfabrics.…”

Section: Layered Fabricsmentioning

confidence: 99%

Keratose sponges in ancient carbonates – A problem of interpretation

et al. 2022

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Reports of diverse vermiform and peloidal structures in Neoproterozoic to Mesozoic open marine to peritidal carbonates include cases interpreted to be keratose sponges. However, living keratose sponges have elaborate, highly elastic skeletons of spongin (a mesoscopic end‐member of a hierarchical assemblage of collagenous structures) lacking spicules, thus have poor preservation potential in contrast to the more easily fossilized spicule‐bearing sponges. Such interpreted fossil keratose sponges comprise diverse layered, network, amalgamated, granular and variegated microfabrics of narrow curved, branching, vesicular–cellular to irregular areas of calcite cement, thought to represent former spongin, embedded in microcrystalline to peloidal carbonate. Interpreted keratose sponges are presented in publications almost entirely in two‐dimensional (thin section) studies, usually displayed normal to bedding, lacking mesoscopic three‐dimensional views in support of a sponge body fossil. For these structures to be keratose sponges critically requires conversion of the spongin skeleton into the calcite cement component, under shallow‐burial conditions and this must have occurred prior to compaction. However, there is no robust petrographic–geochemical evidence that the fine‐grained carbonate component originated from sponge mummification (automicritic body fossils via calcification of structural tissue components) because in the majority of cases the fine‐grained component is homogenous and thus likely to be deposited sediment. Thus, despite numerous studies, verification of fossil keratose sponges is lacking. Although some may be sponges, all can be otherwise explained. Alternatives include: (i) meiofaunal activity; (ii) layered microbial (spongiostromate) accretion; (iii) sedimentary peloidal to clotted micrites; (iv) fluid escape and capture resulting in bird's eye to vuggy porosities; and (v) moulds of siliceous sponge spicules. Uncertainty of keratose sponge identification is fundamental and far‐reaching for understanding: (i) microfacies and diagenesis where they occur; (ii) fossil assemblages; and (iii) wider aspects of origins of animal clades, sponge ecology, evolution and the systemic recovery from mass extinctions. Thus, alternative explanations must be considered.

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“…In this regard, recent studies are starting to show that epifaunal and infaunal bioturbators are more active during microbialite development than previously thought, and in different modern settings including continental (Garc ıa-Pichel et al, 2004), coastal (Rishworth et al, 2016(Rishworth et al, , 2019 and marine environments (Andres & Reid, 2006;Planavsky & Ginsburg, 2009;Jahnert & Collins, 2011;Jahnert & Collins, 2013;Tarhan et al, 2013). Similarly, in most of the few fossil examples of bioturbated microbialites, bioturbation is interpreted as simultaneous with microbial accretion (Wright & Mayall, 1981;Ekdale et al, 1989;Akpan, 1991;Lamond & Tapanila, 2003;Druschke et al, 2009;C onsole-Gonella & Marquillas, 2014;Bourillot et al, 2020), which proves that the relationships between benthic microbial communities and their bioturbators are not limited to destruction and exclusive competition. Moreover, in some cases, bioturbation may have had a significant, although cryptic, role in the development and fossilization of microbialite structures (Wright & Mayall, 1981;Ibarra et al, 2014;Suarez-Gonzalez et al, 2019c;Quijada et al, 2020).…”

Section: Morphogenesis Of Columnar Microbialites: Constructive Destru...mentioning

confidence: 99%

“…However, the recent advances and discussions in that field (e.g. Andres & Reid, 2006; Bosak et al., 2013; Jahnert & Collins, 2013; Ibarra et al., 2014; Vennin et al., 2015; Hickman‐Lewis et al., 2019; Martin‐Bello et al., 2019; Bourillot et al., 2020) are evidence that the complex combination of microbial and environmental factors that shape microbialites are not fully understood yet.…”

Section: Introductionmentioning

confidence: 99%

Columnar microbialites of the upper Miocene of Mallorca (Spain): A new morphogenetic model based on concurrent accretion and bioturbation – uncommon or overlooked?

et al. 2021

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Bioturbation has long been considered an antagonist of microbialite development and preservation, because metazoan grazing and burrowing destroy benthic microbial communities. However, metazoan bioturbation, in conjunction with microbial accretion, may have had a significant role in the morphogenesis of some columnar microbialites, as suggested by the case study presented and by some Phanerozoic and Upper Proterozoic analogues discussed here. Late Miocene in age, the studied microbial biostrome developed in a western Mediterranean restricted shallow‐water platform dominated by grainy sediments and with a notable influence of bioturbation. This study is focused on the complex accretionary history of the columnar microbialite biostrome and on its striking dark grey colour, which is attributed to Mn‐oxyhydroxides precipitated during meteoric diagenesis linked to subaerial exposure. The characteristic columnar structure of the microbialite biostrome has features consistent with an accretionary origin of the columns, but also has features suggesting metazoan disruption. Therefore, a new morphogenetic model for columnar microbialites is presented, highlighting the concomitant roles of microbial accretion, bioturbation and grainy sediment infill of the intercolumn space. Whether this model is an exception or a rule, should be tested on other examples of Phanerozoic and Upper Proterozoic columnar microbialites. Nevertheless, this model is a step forward in understanding the complex microbe–metazoan interactions as constructive coexistence rather than just as destructive competition.

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The Record of Environmental and Microbial Signatures in Ancient Microbialites: The Terminal Carbonate Complex from the Neogene Basins of Southeastern Spain

Cited by 18 publications

References 103 publications

Keratose sponges in ancient carbonates – a problem of interpretation

Keratose sponges in ancient carbonates – a problem of interpretation

Keratose sponges in ancient carbonates – A problem of interpretation

Columnar microbialites of the upper Miocene of Mallorca (Spain): A new morphogenetic model based on concurrent accretion and bioturbation – uncommon or overlooked?

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