Magnesite formation in playa environments near Atlin, British Columbia, Canada

Power, Ian M.; Harrison, Anna L.; Dipple, Gregory M.; Wilson, Siobhan A.; Barker, Shaun L.L.; Fallon, Stewart

doi:10.1016/j.gca.2019.04.008

Cited by 37 publications

(81 citation statements)

References 98 publications

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“…However, until now, it has been impossible to disentangle the relative roles of water column precipitation and diagenetic growth of sepiolite versus silica and Mg-bearing carbonates (e.g., dolomite, (hydro-)magnesite) during sedimentation and early diagenesis. Our derived rate parameters permit, for the first time, quantification of the evolution of Mg-silicate growth during sediment burial, which, when combined with literature data for the behavior of silica and Mg-bearing carbonates (e.g., Kent and Kastner, 1985;Power et al, 2019), can aid the development of fully coupled models for these systems. At the most basic level, the dramatic increase in the growth rate with increasing saturation state and pH helps to explain the observation that many natural waters, including seawater, are persistently and metastably supersaturated with respect to sepiolite while pore waters in their underlying sediments tend to approach equilibrium with this mineral.…”

Section: Implications For Early Diagenesis In Alkaline Lakesmentioning

confidence: 99%

A rate law for sepiolite growth at ambient temperatures and its implications for early lacustrine diagenesis

Arizaleta

Nightingale

Tutolo

2020

Geochimica et Cosmochimica Acta

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Section: Implications For Early Diagenesis In Alkaline Lakesmentioning

confidence: 99%

A rate law for sepiolite growth at ambient temperatures and its implications for early lacustrine diagenesis

Arizaleta

Nightingale

Tutolo

2020

Geochimica et Cosmochimica Acta

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“…Any such comparisons have to consider the substantive mineralogical differences between Earth and Mars, terrestrial instead of marine depositional settings and the respective potentials of calcium and magnesium carbonates to preserve biosignatures. For example, terrestrial non-marine carbonates are dominated by calcite and aragonite (calcium carbonate minerals) and only occasionally include Mg carbonates, such as the anhydrous magnesite and dolomite, or hydrated magnesium carbonates, such as hydromagnesite, nesquehonite, huntite, dypingite, lansfordite and others [202][203][204] . The abiotic precipitation of dolomite and magnesite appears to be kinetically inhibited at temperatures below ~60-80 °C, which is attributed to the strong hydration of magnesium cation and the energy barrier necessary to establish long-range order 205 .…”

Section: Analogues Of Martian Hydrated Magnesium Carbonatesmentioning

confidence: 99%

Searching for biosignatures in sedimentary rocks from early Earth and Mars

Bosak

Moore

Gong

et al. 2021

Nat Rev Earth Environ

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The recognition of past habitable environments on Mars has increased the urgency to understand biosignature preservation in and characterize analogues of these environments on Earth. In this Review, we examine the detection and interpretation of potential biosignatures preserved in deposits rich in carbonates, silica and clay. Many of the earliest chemical, textural and morphological evidence of life on Earth are found in carbonates and carbonate-hosted phases. Early diagenetic chert within carbonate deposits can exceptionally preserve microbial body fossils, and clay minerals that form in ultramafic terrains can protect organic matter. On Mars, similar deposits older than 3.5 billion years could contain biosignatures or remnants of prebiotic processes that have long been erased from Earth. Terrestrial analogues for the deposition of magnesium carbonate minerals in Jezero crater, Mars, present patterns that can guide the collection of samples with the highest astrobiological potential by the Perseverance rover. Continued characterization of terrestrial analogue sites and rigorous examination of the processes that impact the preservation of isotopic signals, organic compounds, and microbial textures and fossils will advance the interpretation of Martian deposits.

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“…In magnesite synthesis experiments at a temperature below 60 • C, nesquehonite generally forms [5], then dypingite and transformation to hydromagnesite, and sometimes also brucite is formed [27]. Studies of natural, playa environments indicate that hydromagnesite probably forms by the transformation of more hydrated phases, such as lansfordite and nesquehonite, and that magnesite forms separately from pore fluids at depth and not at the expense of hydro-magnesite [28]. The latter study suggests magnesite is not formed by transformation of hydromagnesite at near-surface conditions in playa environments and that magnesite formation at these conditions is very slow with a rate of about 10 −16 to 10 −17 mol m −2 s −1 [28].…”

Section: Magnesium Carbonate Formationmentioning

confidence: 99%

Effect of pH Cycling and Zinc Ions on Calcium and Magnesium Carbonate Formation in Saline Fluids at Low Temperature

Vandeginste

2021

Minerals

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The formation of dolomite is very challenging in the laboratory under ambient conditions due to kinetic inhibition. The goal of this study was to test the impact of pH cycling and zinc ions on the formation of magnesium-rich carbonates in saline fluids at a low temperature. Batch reactor experiments were conducted in two series of pH cycling experiments, one without and one with zinc ions, at 43 °C. The results after 36 diel pH cycles indicate a reaction product assemblage of hydromagnesite, aragonite and magnesite in the experiments without zinc ions, and of magnesite and minor aragonite in the experiments with zinc ions. The presence of zinc ions leads to a decrease in the pH in the acid phase of the cycling experiments, which likely plays a role in the reaction product assemblage. Moreover, the hydration enthalpy and other specific ion effects could be additional factors in the formation of magnesium-rich carbonate. The results show a clear evolution towards increasing incorporation of magnesium in the carbonate phase with cycle number, especially in the experiments with zinc ions, reflecting a ripening process that is enhanced by pH cycling. Hence, repeated pH cycling did not lead to more ordered dolomite (from protodolomite), but rather to the formation of magnesite with 92 mol% MgCO3 after 36 cycles, even though geochemical models indicate a higher saturation index for dolomite than for magnesite.

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Magnesite formation in playa environments near Atlin, British Columbia, Canada

Cited by 37 publications

References 98 publications

A rate law for sepiolite growth at ambient temperatures and its implications for early lacustrine diagenesis

A rate law for sepiolite growth at ambient temperatures and its implications for early lacustrine diagenesis

Searching for biosignatures in sedimentary rocks from early Earth and Mars

Effect of pH Cycling and Zinc Ions on Calcium and Magnesium Carbonate Formation in Saline Fluids at Low Temperature

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