Acid Fluid Inclusions in Bedded Halite of the Triassic Mercia Mudstone, Northern Ireland

Eichenlaub, Lynnette A.; Benison, Kathleen C.; Andeskie, Anna Sofia

doi:10.1130/abs/2016am-282533

Cited by 4 publications

(5 citation statements)

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“…Laser Raman spectroscopy identified aluminum sulfate compounds and bisulfate, suggesting a low pH (, 3). These Raman spectroscopic data, along with sedimentology and mineralogy of the Mercia Mudstone, indicate that the Mercia Mudstone Group was deposited as an acid-salinelake system (Eichenlaub 2016;Eichenlaub et al 2016).…”

Section: Interpreting Lake and Groundwater Geochemistrymentioning

confidence: 83%

“…Recently, the acidity of the Triassic lake waters was quantitatively determined by laser Raman spectroscopy of primary fluid inclusions in Mercia Mudstone Group bedded halite (Eichenlaub 2016;Eichenlaub et al 2016). Laser Raman spectroscopy identified aluminum sulfate compounds and bisulfate, suggesting a low pH (, 3).…”

Section: Interpreting Lake and Groundwater Geochemistrymentioning

confidence: 99%

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Acid-saline-lake Systems of the Triassic Mercia Mudstone Group, County Antrim, Northern Ireland

Andeskie

Benison

Eichenlaub

et al. 2018

Journal of Sedimentary Research

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The Triassic Mercia Mudstone Group of County Antrim, Northern Ireland, is dominated by red beds and evaporites. After only limited study, both marine and continental environments have been proposed previously. Here, we describe these rocks for the first time from core and petrographic observations to interpret depositional environments and conditions, such as water depth, salinity, and aridity. Bedded halite, bedded gypsum, displacive halite, and red siliciclastic mudstone lithologies comprise most (~80%) of the 591.6-m-thick Mercia Mudstone Group in the Gaelectric Carnduff-2 core. Bedded halite consists of chevron and cornet crystals, indicating bottom-growth from shallow surface brines. Bedded-gypsum lithology is composed of halite-replaced pseudomorphs after swallowtail, bottom-growth gypsum crystals. Both bedded halite and bedded gypsum contain dissolution features and are commonly overlain by mud drapes. Bedded-halite and bedded-gypsum lithologies are interpreted to have formed in shallow saline lakes influenced by flooding and evapoconcentration. The displacive-halite lithology is composed of subcubic halite crystals, randomly oriented in mudstone, and represents deposition in a saline mudflat. Some mudstones contain ripple cross-lamination, dewatering structures, mudcracks, and rip-up clasts, suggesting shallow surface water and desiccation. Other mudstones are massive (structureless) and may have been deposited by wind. Both of these mudstone units were likely deposited in dry mudflats. Other red mudstones contain soil slickensides, blocky peds, and circumgranular cracks and are interpreted as paleosols. Our observations indicate that the Triassic Mercia Mudstone Group was formed by shallow perennial saline lakes and associated continental environments in an arid climate. Furthermore, lack of carbonates, lack of fossils, and paucity of organic matter suggest acid saline lakes and groundwaters. The Triassic Mercia Mudstone Group is similar to some other Pangean red beds and evaporites. Therefore, we hypothesize that the supercontinent was an arid barren landscape hosting acid-saline lakes.

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Section: Interpreting Lake and Groundwater Geochemistrymentioning

confidence: 83%

Section: Interpreting Lake and Groundwater Geochemistrymentioning

confidence: 99%

Acid-saline-lake Systems of the Triassic Mercia Mudstone Group, County Antrim, Northern Ireland

Andeskie

Benison

Eichenlaub

et al. 2018

Journal of Sedimentary Research

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“…Primary fluid inclusions in the Larne Halite Member are wellpreserved remnants of these Triassic acid (pH values $1-3), brine lake waters. In addition to acid brines, these inclusions also preserve Triassic air bubbles, sulphate minerals, and suspect microorganisms, including Dunaliella algae (Eichenlaub, 2016;Eichenlaub et al, 2016). The salticles of this current study are a product of partial dissolution and reprecipitation of the bedded halite of the Larne Halite.…”

Section: Site Descriptionmentioning

confidence: 66%

Microbiology of a NaCl stalactite ‘salticle’ in Triassic halite

Thompson

Kelly

Skvortsov

et al. 2021

Environmental Microbiology

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Large regions of Earth's surface are underlain by salt deposits that evaporated from ancient oceans and are populated by extreme halophilic microbes. Some of these halophiles may have been preserved over geological timescales within hypersaline fluid inclusions, but ingresses of water and/or anthropogenic activities can lead to the formation of alternative habitats, including NaCl stalactites or other speleothems. While the microbiology of ancient evaporites has been well studied, the ecology of these recently formed structures is less-well understood. Here, the microbiology of a NaCl stalactite ('salticle') in a Triassic halite mine is characterized. The specific aims were to determine the presence of fluid inclusions, determine the microbial structure of the salticle compared with a nearby brine-pool and surficial soil, and characterize the ecophysiological capabilities of this unique ecosystem. The salticle contained fluid inclusions, and their microbiome was composed of Euryarchaetota, Proteobacteria, and Actinobacteria, with Haloarchaea in greater abundance than brinepool or soil microbiomes. The salticle metagenome exhibited a greater abundance of genes involved in osmoregulation, anaerobic respiration, UV resistance, oxidative stress, and stress-protein synthesis relative to the soil microbiome. We discuss the potential astrobiological implications of salticles as enclosed salt-saturated habitats that are protected from ionizing radiation and have a stable water activity.

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“…5.2.2 | Were lakes and groundwaters of the Red Peak Formation acidic? Late Permian and early Triassic red beds and bedded evaporites were probably formed in acid lake and groundwater systems (Benison et al, 1998;Benison & Goldstein, 2002;Eichenlaub, 2016;Eichenlaub et al, 2016;Andeskie et al, 2018). Raman spectroscopy of fluid inclusions in halite in the Permian Nippewalla Group shows single bisulphate peaks, indicating a pH less than 2.…”

Section: Permo-red Beds and Bedded Evaporitesmentioning

confidence: 99%

Gypsum lakes, sandflats and soils revealed from the Triassic Red Peak Formation of the Chugwater Group, north‐central Wyoming

Bradford,

Benison

2024

The Depositional Record

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Bedded gypsum is relatively common in bedded evaporites associated with red bed siliciclastics of Permo‐Triassic Pangea. However, little attention has been paid to the textures of ancient gypsum, which can be used to refine interpretations of depositional environment and diagenetic history. This project describes the textures of bedded gypsum from an outcrop of the Triassic Red Peak Formation (Chugwater Group) near Greybull, Wyoming. Fieldwork, petrography and X‐ray diffraction reveal three distinct lithologies of bedded gypsum: bottom‐growth gypsum, laminated gypsum and clastic gypsum. Bottom‐growth gypsum precipitated at the bottom of shallow saline surface water bodies. Laminated gypsum probably formed in shallow saline lakes and mudflats. Clastic gypsum units are composed of aeolian‐reworked bottom‐growth gypsum crystals deposited in sandflats. Red siliciclastic mudstones are characterised by their massive nature and abundant blocky peds. Detailed study of this outcrop of the Red Peak Formation shows that it formed in shallow saline lakes and associated mudflats, sandflats and desert soils.

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Acid Fluid Inclusions in Bedded Halite of the Triassic Mercia Mudstone, Northern Ireland

Cited by 4 publications

References 0 publications

Acid-saline-lake Systems of the Triassic Mercia Mudstone Group, County Antrim, Northern Ireland

Acid-saline-lake Systems of the Triassic Mercia Mudstone Group, County Antrim, Northern Ireland

Microbiology of a NaCl stalactite ‘salticle’ in Triassic halite

Gypsum lakes, sandflats and soils revealed from the Triassic Red Peak Formation of the Chugwater Group, north‐central Wyoming

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