The evolution of end-member continental waters: The origin of acidity in southern Western Australia

Benison, Kathleen C.; Bowen, Brenda B.

doi:10.1130/gsatg231a.1

Cited by 38 publications

(39 citation statements)

References 34 publications

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“…Natural acid brines are rare on Earth, and their sedimentary and geochemical processes and products are complex and dynamic (e.g., Benison et al . ,b; Benison & Bowen , ). Little is known of the evolution of acid saline waters in volcanic basins.…”

Section: Introductionmentioning

confidence: 99%

A fluid inclusion record of magmatic/hydrothermal pulses in acid Salar Ignorado gypsum, northern Chile

Karmanocky

Benison

2016

Geofluids

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Salar Ignorado is a shallow acid saline lake hosted by a small intervolcanic basin high in the Andes Mountains of northern Chile. Modern surface waters have 3.3–4.1 pH, 0.5–3% total dissolved solids (TDS) and are actively precipitating gypsum crystals. The gypsum crystals trap the acid saline water as fluid inclusions, providing a record of recent surface water characteristics. Salar Ignorado gypsum contains three distinct types of primary fluid inclusions, which result from growth of the gypsum from surface waters. Petrography and microthermometry were performed on 27 gypsum crystals from Salar Ignorado to gain an understanding of recent water chemistry of the salar. One 18.3‐cm‐long gypsum crystal, hosting primary fluid inclusions along 28 successive growth bands, was the focus for fluid inclusion studies and allowed a record of high‐resolution chemical trends. This crystal showed a change in parent fluids during growth, from low salinity, to high salinity, back to low salinity. At the bottom of the crystal, the lowest six fluid inclusion assemblages have salinities of 1.7–5.1 eq. wt. % NaCl. The next nine fluid inclusion assemblages have significantly higher salinity (18.6–27.4 eq. wt. % NaCl) inclusions. The twelve fluid inclusion assemblages near the top of the crystal have low salinity (0.9–8.3 eq. wt. % NaCl) like those at the bottom of the crystal. The high‐salinity fluid inclusions in the middle of this gypsum crystal are interpreted to have formed during a pulse of magmatic/hydrothermal fluids to the surface, perhaps during local active volcanism. Secondary evidence of a magmatic influence on surface waters includes hydrogen sulfide and high molecular weight solid hydrocarbons within some fluid inclusions. This study is among the first detailed fluid inclusion studies of gypsum and suggests that fluid inclusions in gypsum can be paleo‐hydrogeologic proxies.

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Section: Introductionmentioning

confidence: 99%

A fluid inclusion record of magmatic/hydrothermal pulses in acid Salar Ignorado gypsum, northern Chile

Karmanocky

Benison

2016

Geofluids

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“…Most research assumes evaporite deposits are neutral or alkaline. Acid-saline deposits only form as a result of specific climactic, geographic, and geologic conditions (Long and Lyons, 1992;Benison and Bowen, 2015). This study is the first investigation of the pH of Browne Formation parent waters.…”

Section: Scientific Implicationsmentioning

confidence: 86%

Fluid inclusion analyses of Bedded Halite from the Neoproterozoic Browne Formation of Central Australia to Determine Parent Water Origin and pH

Bernau¹

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Fluid inclusion analyses of bedded halite from the Neoproterozoic Browne Formation of central Australia to determine parent water origin and pH Jeremiah Bernau The depositional origin of the Neoproterozoic Browne Formation of Australia is unclear. The Browne Formation consists of red-siliciclastic mudstone and siltstone (red beds), bedded and displacive halite and gypsum, and dolomitized stromatolites. Environmental interpretations of the Browne Formation range from a marginal marine lagoon to a playa lake deposit (Grey

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“…Located on the Yilgarn Craton, a tectonically stable and low relief setting, these ephemeral saline lakes range from acidic to alkaline, though most are acidic (Benison et al, 2007). Salinities as high as 32% total dissolved solids and pH values as low as 1.4 have been observed within these lakes (Benison and Bowen, 2015). Some lakes are halite-dominated while others, comparable to the ephemeral saline lake lithofacies observed in the Day Creek Dolomite, are gypsumdominated.…”

Section: Does the Quartermaster Represent Acid Saline Environments?mentioning

confidence: 92%

Improving Seeding and Mulching Specifications In West Virginia and Creating a Materials Estimate Tool

Pritt¹

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Permo-Triassic red beds and evaporites can be found in a variety of locations around the world. Largely deposited once the supercontinent Pangea formed, many of these units have historically been interpreted as marine to marginal marine deposits due to their association with evaporites. Evaporites, however, can also form in continental settings. Recent studies of red beds and evaporites within the Leonardian-Guadalupian Nippewalla Group of Kansas suggest some red beds and evaporites were deposited in acid saline lakes and associated environments. The middle to late Permian Quartermaster Group, which overlies the Nippewalla Group, has not been as extensively studied. The main goal of this thesis was to determine the depositional and diagenetic history of the Quartermaster Group of Kansas. This research focused on the Whitehorse Sandstone, Day Creek Dolomite, and Big Basin Formation of the Quartermaster Group as observed in the Amoco Rebecca K. Bounds core no. 1 from Greeley County, west-central Kansas. Petrography and mineralogical identification were used to characterize the depositional and diagenetic features of these rocks. Field observations from south-central Kansas (Clark and Barber Counties) provided supplementary data. Sedimentary features observed in the Quartermaster Group suggest the Whitehorse Sandstone, Day Creek Dolomite, and Big Basin Formation were deposited in continental settings. The Whitehorse Sandstone consists of red sandstone, siltstone, and mudstone with observable ped structures, root features, ripple cross-stratification, mud drapes, mudcracks, and soil slickensides. These features suggest deposition in mudflats and fluctuating water tables in adjacent soils. The Day Creek Dolomite consists of bedded gypsum/anhydrite and finely laminated red siltstones. Ripple cross-stratification, mudcracks, and planar laminae observed in bedded gypsum/anhydrite indicate deposition in ephemeral saline lake environments while ripple cross-stratification, mud drapes, soil slickensides, and root features in red siltstones indicate mudflats and soils. The Big Basin Formation consists of dark red sandstone, siltstone, and mudstone characterized by soft sediment deformation, ripple cross-stratification, mudcracks, and soil slickensides. These features suggest deposition in mudflats and the development of paleosols. In general, early and late diagenetic features observed within the Quartermaster Group suggest substantial influence from wetting and drying processes at or near the surface. Evidence for acidity in the Quartermaster Group is based on suspect to problematic criteria. Acid saline lake deposition is postulated from indirect criteria such as unusual yellow hues observed in halite and other evaporites within bedded gypsum/anhydrite layers of the Day Creek Dolomite. Additionally, the absence of carbonates, abundance of red beds, and similarities to the underlying Nippewalla Group, a known acid system, suggest that units within the Quartermaster Group were likely influenced by acid lake waters and ground...

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The evolution of end-member continental waters: The origin of acidity in southern Western Australia

Cited by 38 publications

References 34 publications

A fluid inclusion record of magmatic/hydrothermal pulses in acid Salar Ignorado gypsum, northern Chile

A fluid inclusion record of magmatic/hydrothermal pulses in acid Salar Ignorado gypsum, northern Chile

Fluid inclusion analyses of Bedded Halite from the Neoproterozoic Browne Formation of Central Australia to Determine Parent Water Origin and pH

Improving Seeding and Mulching Specifications In West Virginia and Creating a Materials Estimate Tool

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