Variation in the diagenetic response of aragonite archives to hydrothermal alteration

Pederson, Chelsea L.; Mavromatis, Vasileios; Dietzel, Martin; Rollion‐Bard, Claire; Breitenbach, Sebastian F. M.; Yu, Dai; Nehrke, Gernot; Immenhauser, Adrian

doi:10.1016/j.sedgeo.2020.105716

Cited by 28 publications

(31 citation statements)

References 129 publications

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“…Because of this metastability, aragonite is more susceptible to chemical alteration, and thus its preservation is considered an indicator of pristine geochemistry (Stahl & Jordan, 1969). There is considerable variability in the response of different aragonite materials to alteration processes, which are related to differences in chemical composition and porosity (Pederson et al., 2020). The alteration typically involves the dissolution of aragonite and reprecipitation of the more stable polymorph calcite (Bischoff & Fyfe, 1968), a process termed neomorphism (Folk, 1965).…”

Section: Introductionmentioning

confidence: 99%

“…The exchange of isotopes between carbonate and ambient fluids during the aragonite to calcite transition commonly results in an isotopic shift toward the equilibrium δ 18 O values of the newly formed calcite. In the presence of an experimental “diagenetic fluid,” it was shown that calcite formation is accelerated and initiates at 160°C–200°C on experimental timescales (Casella et al., 2017; Milano et al., 2016; Pederson, Mavromatis, et al., 2019; Pederson, Weiss, et al., 2019; Pederson et al., 2020). This reaction rate is considerably accelerated and occurs at lower temperatures if a powdered aragonite is used in the alteration experiment (Guo et al., 2019).…”

Section: Introductionmentioning

confidence: 99%

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Internal Water Facilitates Thermal Resetting of Clumped Isotopes in Biogenic Aragonite

Nooitgedacht

Lubbe

Ziegler

et al. 2021

Geochem Geophys Geosyst

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Primary marine and terrestrial carbonates consist predominantly of two polymorphs of calcium carbonate: calcite and aragonite. The relative abundance of these minerals has varied over 100 myr timescales (Sandberg, 1983;Zhang et al., 2020) due to changes in water chemistry and surface temperature (Adabi, 2004; Balthasar & Cusack, 2014). Despite being a common mineral at the Earth's surface, aragonite is metastable at surface temperatures and pressures and only becomes the more stable crystalline arrangement with significant substitution of ions (Carlson, 1980) and/or at elevated pressure at burial depths (Hacker, 2005). Because of this metastability, aragonite is more susceptible to chemical alteration, and thus its preservation is considered an indicator of pristine geochemistry (Stahl & Jordan, 1969). There is considerable variability in the response of different aragonite materials to alteration processes, which are related to differences in chemical composition and porosity (Pederson et al., 2020). The alteration typically involves the dissolution of aragonite and reprecipitation of the more stable polymorph calcite (Bischoff & Fyfe, 1968), a process termed neomorphism (Folk, 1965).

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Internal Water Facilitates Thermal Resetting of Clumped Isotopes in Biogenic Aragonite

Nooitgedacht

Lubbe

Ziegler

et al. 2021

Geochem Geophys Geosyst

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“…The used fluid composition (100 mM NaCl + 10 mM MgCl2) simulates the fluid present at a burial diagenetic realm. The composition of the fluid was identical to that previously used by Casella et al, (2017Casella et al, ( , 2018 and Pederson et al, (2019a;2019b;2020) in their hydrothermal alteration experiments.…”

Section: Hydrothermal Alteration Experimentsmentioning

confidence: 91%

Long-term experimental diagenesis of aragonitic biocarbonates: from organic matter loss to abiogenic calcite formation

Forjanes

Roda

Greiner

et al. 2021

Preprint

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Abstract. Carbonate biological hard tissues are valuable archives of environmental information. However, this information can be blurred or even completely lost as hard tissues undergo diagenetic alteration. This is more likely to occur in aragonitic skeletons because bioaragonite commonly transforms into calcite during diagenesis. For reliably using aragonitic skeletons as geochemical proxies, it is necessary to understand in depth the diagenetic alteration processes that they undergo. Several works have recently investigated the hydrothermal alteration of aragonitic hard tissues during short term experiments at high temperatures (T > 160 °C). In this study, we conduct long term (4 and 6 months) hydrothermal alteration experiments at 80 °C using burial-like fluids. We document and evaluate the changes undergone by the outer and inner layers of Arctica islandica shell, the prismatic and nacreous layers of Haliotis ovina shell, and the skeleton of Porites sp. combining a variety of analytical tools (X-ray diffraction, thermogravimetry analysis, laser confocal microscopy, scanning electron microscopy, electron backscatter diffraction and atomic force microscopy). We demonstrate that this approach is the most adequate to trace subtle, diagenetic alteration-related changes in aragonitic biocarbonates. Furthermore, we unveil that the diagenetic alteration of aragonitic hard tissues is a complex multi-step process where major changes occur even at the low temperature used in this study and well before any aragonite into calcite transformation takes place. Alteration starts with biopolymer decomposition and concomitant generation of secondary porosity. These processes are followed by abiogenic aragonite precipitation that partially or totally obliterates the secondary porosity. Only afterwards any transformation of aragonite into calcite takes place. The kinetics of the alteration is highly dependent on primary microstructural features of the aragonitic biomineral. While the skeleton of Porites sp. remains virtually unaltered within the time spam of the experiments, Haliotis ovina nacre undergoes extensive abiogenic aragonite precipitation, the outer and inner layers of Arctica islandica shell are significantly affected by aragonite transformation into calcite and this transformations extensive in the case of the prismatic layer of Haliotis ovina shell. Our results suggest that most aragonitic fossil archives may be overprinted, even those free of clear diagenetic alteration signs. This finding may have major implications for the use of these archives as geochemical proxies.

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“…This is remarkable due to the inherently higher porosity and permeability and resultant higher surface area available for colonisation by microbes in coral aragonite compared to the bivalve shell. A possible reason for this might be the initially lower organic content in the coral skeleton ultrastructure compared to the bivalve shell as suggested by a weaker fluorescence (Figures 1 and 9; Pederson et al, 2020;Wanamaker et al, 2009) and by different C org values that are 0.35% for the bivalve bulk aragonite and 0.04% for the coral (Lange, 2017). This observation is consistent with results from Glover and Kidwell (1993) who reported more intense microbial degradation in organic-rich shells compared to organic-lean ones.…”

Section: Comparison Of the Alteration Patterns Between A Islandica Shell And Porites Sp Skeleton And Implications For Biogenic Carbonatesmentioning

confidence: 99%

“…were used to demonstrate the impact of microbial metabolic activity on sulphur in biogenic carbonates. Both samples consist of biogenic aragonite but differ significantly in their microstructure, organic content and porosity (Pederson et al, 2020). Arctica islandica is a marine bivalve from the Northern Atlantic with an endobenthic lifestyle (Schöne, 2013).…”

Section: Introductionmentioning

confidence: 99%

Microbial activity affects sulphur in biogenic aragonite

Fichtner

Lange

Krause

et al. 2021

The Depositional Record

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Carbonates that exhibit obvious diagenetic alteration are usually excluded as archives in palaeoenvironmental studies. However, the potential impact of microbial alteration during early diagenesis is still poorly explored. To investigate the sensitivity of sulphur concentration, distribution, oxidation state and isotopic composition in marine aragonite to microbial alteration, Arctica islandica bivalves and Porites sp. corals were experimentally exposed to anaerobic microbial activity. The anoxic incubation media included a benthic bacterial strain Shewanella sediminis and a natural anoxic sediment slurry with a natural microbial community of unknown species. Combined fluorescence microscopy and synchrotron‐based analysis of the sulphur distribution and oxidation state enabled a comparison of organic matter and sulphur content in the two materials. Results revealed a higher proportion of reduced sulphur species and locally stronger fluorescence within the pristine bivalve shell compared to the pristine coral skeleton. Within the pristine bivalve specimen, reduced sulphur was enriched in layers along the inner shell margin. After incubation in the anoxic sediment slurry, this region revealed rust‐brown staining and a patchy S2‐ distribution pattern rather than S2‐‐layers. Another effect on sulphur distribution was rust‐brown coloured fibres along one growth line, revealing a locally higher proportion of sulphur. The δ34S value of carbonate‐associated sulphate remained largely unaffected by both incubation media, but a lower δ34S value of water‐soluble sulphate reflected the degradation of insoluble organic matter by microbes in both experiments. No significant alteration was detected in the coral samples exposed to microbial alteration. The data clearly identified a distinct sensitivity of organically bound sulphur in biogenic aragonite to microbial alteration even when ‘traditional’ geochemical proxies such as δ18OCARB or δ13CCARB in the carbonate did not show any effect. Differences in the intensity of microbial alteration documented are probably due to inherent variations in the concentration and nature of original organic compositions in the samples.

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Variation in the diagenetic response of aragonite archives to hydrothermal alteration

Cited by 28 publications

References 129 publications

Internal Water Facilitates Thermal Resetting of Clumped Isotopes in Biogenic Aragonite

Internal Water Facilitates Thermal Resetting of Clumped Isotopes in Biogenic Aragonite

Long-term experimental diagenesis of aragonitic biocarbonates: from organic matter loss to abiogenic calcite formation

Microbial activity affects sulphur in biogenic aragonite

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