Temporal evolution of shallow marine diagenetic environments: Insights from carbonate concretions

Loyd, S. J.; Meister, Patrick; Liu, Bo; Nichols, Kevin P.; Corsetti, Frank A.; Raiswell, R.; Berelson, William M.; Shields, Graham; Hounslow, Mark W.; Waldron, John W.F.; Westrick-Snapp, Bayne; Hoffman, Jamie

doi:10.1016/j.gca.2023.04.022

Cited by 7 publications

(2 citation statements)

References 136 publications

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“…The nodules have been proposed as a favorable taphonomic window for biosignature preservation due to the early lithification of concretionary structure (Stack et al, 2014;Grice et al, 2019). Previous studies have reported organic matter, fossils, biominerals, and isotopic biosignatures preserved within nodules formed in marine settings or terrestrial freshwater systems (e.g., Marshall and Pirrie, 2013;Plet et al, 2020;Loyd et al, 2023). As for playa nodules, biomass could be low in saline diagenetic fluids considering low productivity and buried biomass in evaporitic lacustrine environments (Kong et al, 2014;Shkolyar and Farmer, 2018;Chen et al, 2022;Azua-Bustos et al, 2023).…”

Section: Introductionmentioning

confidence: 99%

Taphonomy of biosignatures in carbonate nodules from the Mars-analog Qaidam Basin: constraints from microscopic, spectroscopic, and geochemical analyses

Chen,

Yin,

Lin

2024

Front. Astron. Space Sci.

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Early diagenetic nodules with low permeable and weather-resistant structures are considered to be favorable for biosignature preservation. Numerous nodular structures forming in neutral-to-alkaline and saline diagenetic fluids were previously identified at Gale Crater on Mars, yet their astrobiological significance remains poorly understood. In the Mars-like western Qaidam Basin, China, there are a multitude of carbonate nodules which can be analogous to those found at Gale Crater on Mars in terms of their formation backgrounds and post-depositional processes. In this study, we combine microscopic, spectroscopic, and geochemical methods to characterize the biosignature preservation of the Qaidam nodules. Carbonaceous materials, including an organic annulus inferred to be a fossil spore or algal filament microfossil, are observed in the Qaidam nodules. The total organic carbon contents of the Qaidam nodules are slightly higher than those of the surrounding fluvio-lacustrine deposits, suggesting that early diagenesis of the Qaidam nodules might facilitate the rapid entombment of biomass within magnesium carbonate or aragonite matrixes before complete degradation. The carbonate matrix showing alternating micritic and sparry layers as well as enrichment of 13C could have a physicochemical origin though the possibilities of biomineralization and organomineralization cannot be entirely ruled out. The I-1350/1,600 distribution of carbonaceous materials implies the existence of carbon precursors of various subcellular components or coexisting organisms in pore waters. Organic carbon isotopes indicate the carbon fixation pathways such as the Calvin cycle or the Wood-Ljungdahl pathway utilized by organisms in pore waters. The findings of this study shed light into the taphonomy and detection of biosignatures in terrestrial playa nodules, with potential applications for biosignature exploration on Mars.

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Section: Introductionmentioning

confidence: 99%

Taphonomy of biosignatures in carbonate nodules from the Mars-analog Qaidam Basin: constraints from microscopic, spectroscopic, and geochemical analyses

Chen,

Yin,

Lin

2024

Front. Astron. Space Sci.

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“…However, such proportions should be constrained for more continental margin sites to improve the existing quantification. Furthermore, more approaches for quantifying the extent of authigenic carbonate formation are required, which can also be applied to ancient oceans (Loyd et al., 2023).…”

Section: Introductionmentioning

confidence: 99%

Quantifying the Extent of Authigenic Carbonate Formation in Shallow Marine Sediments Through a Correlation Between Carbonate Precipitation Rate and Sulfate Flux

Hu,

Luo,

Peckmann

et al. 2023

Geophysical Research Letters

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The accumulation of authigenic carbonate in marine sediments has been regarded as a significant contributor to the carbon cycle over Earth's history. However, accurate quantification of the extent of authigenic carbonate formation in both modern and ancient oceans has been challenging due to limited approaches. Here, we analyzed calcium, magnesium, dissolved inorganic carbon, and alkalinity pore‐water profiles of 153 sites influenced by methane diffusion from the northern South China Sea. By combining these data with published data of diffusive sulfate flux, we found a significant positive correlation between carbonate precipitation rate and sulfate flux in the subseafloor. This correlation can be used to quantify the regional extent of authigenic carbonate formation, representing an advantage over a spatial interpolation approach. We therefore propose that the observed correlation can serve as a new approach for quantifying authigenic carbonate formation in shallow sediments along continental margins for both modern and ancient oceans.

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Barite septarian concretions in the Albian (Cretaceous) of the Subbetic (Southern Spain)

Molina,

Reolid

2024

J Iber Geol

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This works analyses the Albian barite septarian concretions of the Fardes Formation located in the Geopark of Granada within the Subbetic (Betic Cordillera, SE Spain) from a stratigraphic, textural, mineralogical and geochemical point of view. The early diagenetic conditions that favoured the development of the concretions and their septaria are interpreted, taking into account the importance of the organic-rich clay facies (black shales) in which they are found as well as the interruptions in the sedimentation rate. The barite concretions formed in different stages: (1) Sedimentation of black shales containing Ba of organic origin and deposited in low oxygen environments; (2) diffusion of seawater interstitial solutions containing Ba2+ mainly from organic matter and sulfate originating from the decomposition of organic matter by bacterial reduction; (3) crystallization of barite on nucleation sites and rapid growth of concretion at the water–sediment interface when the depth of the barite front stabilized at a few meters depth due to a very low or no sedimentation rate; (4) rapid growth of the concretions and sediment load favoured the formation of septarian cracks that were filled first with Sr-rich barite crystals and finally by calcite. The association of barite concretions and stratigraphic discontinuities can be very useful for the recognition of depositional hiatuses in thick monotonous clayey or marly sequences.

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Temporal evolution of shallow marine diagenetic environments: Insights from carbonate concretions

Cited by 7 publications

References 136 publications

Taphonomy of biosignatures in carbonate nodules from the Mars-analog Qaidam Basin: constraints from microscopic, spectroscopic, and geochemical analyses

Taphonomy of biosignatures in carbonate nodules from the Mars-analog Qaidam Basin: constraints from microscopic, spectroscopic, and geochemical analyses

Quantifying the Extent of Authigenic Carbonate Formation in Shallow Marine Sediments Through a Correlation Between Carbonate Precipitation Rate and Sulfate Flux

Barite septarian concretions in the Albian (Cretaceous) of the Subbetic (Southern Spain)

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