Geotechnical implications of diagenetic iron sulfide formation in Champlain Sea sediments

1979 ◽  
Vol 16 (3) ◽  
pp. 575-584 ◽  
Author(s):  
Joseph J. Donovan ◽  
Ginette Lajoie
Keyword(s):  
Iron Sulfide ◽  
Ferric Hydroxide ◽  
Geochemical Data ◽  
Stable Phase ◽  
Iron Hydroxides ◽  
Reducing Conditions ◽  
Decomposition Of Organic Matter ◽  
Bacterial Decomposition ◽  
The Stability ◽  
High Sulfide

It has been proposed that iron hydroxides act as cementing agents in Champlain Sea clays, causing brittle behaviour and high sensitivities. Study of interbedded turbiditic sandy and clayey strata of the Champlain Sea disputes this contention. Ground waters flowing through these sandy interbeds have high pH and are sodium bicarbonate dominant and strongly reduced, with a calculated Eh of −276 to −343 mV, using the sulfate–sulfide redox couple. During movement from recharge to discharge, sulfate is reduced by bacterial decomposition of organic matter in the clays, producing high sulfide and bicarbonate activities. In terms of Eh and pH, these waters fall within the stability fields of Fe2+ and FeS2.No pyrite was detected in the sediments, but in borehole samples and very fresh exposures of both clay and sand lithologies a very finely-disseminated black mineral phase, interpreted as iron monosulfides, was observed which is highly unstable in an aerobic environment, oxidizing rapidly to red-brown ferric hydroxide. The presence of these monosulfides, along with the aqueous geochemical data, indicate strongly reducing conditions in the clay strata, in which iron hydroxides are not a stable phase. Ferric hydroxides can therefore not be called upon as cementing agents; past studies which identified these ferric compounds as such cementing agents based their conclusions on samples out of equilibrium with their natural environment and are not directly relevant to the behaviour of the clay under natural conditions. The effects of these iron monosulfides and associated organic material on clay behaviour have not yet been studied.

scholarly journals Greigite (Fe3S4) is thermodynamically stable: Implications for its terrestrial and planetary occurrence

2020 ◽  
Vol 117 (46) ◽  
pp. 28645-28648
Author(s):  
Tamilarasan Subramani ◽  
Kristina Lilova ◽  
Mykola Abramchuk ◽  
Kurt D. Leinenweber ◽  
Alexandra Navrotsky
Keyword(s):  
High Pressure ◽  
Monoclinic Phase ◽  
Iron Sulfide ◽  
Enthalpies Of Formation ◽  
Stable Phase ◽  
Fine Grained ◽  
Low Surface Energy ◽  
Iron Sulfide Minerals ◽  
The Common ◽  
The Stability

Iron sulfide minerals are widespread on Earth and likely in planetary bodies in and beyond our solar system. Using measured enthalpies of formation for three magnetic iron sulfide phases: bulk and nanophase Fe3S4spinel (greigite), and its high-pressure monoclinic phase, we show that greigite is a stable phase in the Fe–S phase diagram at ambient temperature. The thermodynamic stability and low surface energy of greigite supports the common occurrence of fine-grained Fe3S4in many anoxic terrestrial settings. The high-pressure monoclinic phase, thermodynamically metastable below about 3 GPa, shows a calculated negative P-T slope for its formation from the spinel. The stability of these three phases suggests their potential existence on Mercury and their magnetism may contribute to its present magnetic field.

scholarly journals Geology and Genesis of the Giant Gorevskoe Pb-Zn-Ag Deposit, Krasnoyarsk Territory, Russia

2020 ◽  
Author(s):  
Georgii Belokonov ◽  
Max Frenzel ◽  
Nadezhda S. Priyatkina ◽  
Axel D. Renno ◽  
Vladimir Makarov ◽  
...  
Keyword(s):  
Sulfur Isotope ◽  
Iron Sulfide ◽  
Massive Sulfide ◽  
Passive Margin ◽  
Yenisei Ridge ◽  
Geochemical Data ◽  
Isotope Signature ◽  
Margin Setting ◽  
Reducing Conditions ◽  
Host Rocks

Abstract The Gorevskoe Pb-Zn-Ag mine is currently the largest producer of Pb and Zn in Russia, exploiting one of the largest sediment-hosted Pb-Zn deposits worldwide. Despite its size and economic importance, the Gorevskoe deposit remains poorly understood. It is located on the western margin of the Siberian craton within the Yenisei Ridge, a Neoproterozoic orogenic belt. Mineralization consists of three tabular orebodies that are in turn composed of multiple stacked stratiform to strata-bound lenses of galena-pyrrhotite-sphalerite-rich massive sulfide ore, hosted in organic-rich marine metalimestones and calcareous slates of Stenian to Tonian age (1,020 ± 70 Ma). Extensive Fe-Mg-Mn-carbonate alteration haloes surround the ore lenses. The Pb isotope signature of the deposit is consistent with derivation of Pb, and probably all associated metals, from an evolved crustal source at the time of formation of the host rocks. The sulfur isotope compositions of pyrrhotite, sphalerite, galena, arsenopyrite, and pyrite (δ34S = 16.0–20.4‰) do not vary considerably across the deposit and are within the range reported for contemporaneous seawater, indicating complete reduction of marine sulfate as the main source of sulfur. The available geologic and geochemical data indicate that the Gorevskoe deposit belongs to the sediment-hosted massive sulfide (SHMS) class of Zn-Pb deposits, with an affinity to Selwyn-type deposits. Hydrothermal mineralization appears to be temporally related to rifting and distal mafic volcanism in a passive margin setting. Geologic relationships suggest that the orebodies formed in a diagenetic environment. Furthermore, the predominance of primary pyrrhotite over pyrite as the major iron sulfide, the presence of abundant siderite, and the relatively homogeneous sulfur isotope signature of the ores indicate highly reducing conditions during ore formation. They also constrain the character of the metal-bearing fluid to be similarly reducing, and of moderate temperature (200°–300°C). Gorevskoe may thus be regarded as one of the world’s largest Selwyn-type SHMS deposits.

The stability of onoratoite, Sb8O11Cl2, in the supergene environment

2014 ◽  
Vol 78 (7) ◽  
pp. 1671-1675 ◽  
Author(s):  
Adam J. Roper ◽  
Peter Leverett ◽  
Timothy D. Murphy ◽  
Peter A. Williams
Keyword(s):  
Significant Influence ◽  
Secondary Phase ◽  
Low Ph ◽  
Stable Phase ◽  
Supergene Zone ◽  
A Value ◽  
Solubility Studies ◽  
The Stability ◽  
Very High

AbstractSynthesis and solubility studies of onoratoite have been undertaken to determine the role of this rare secondary phase in the immobilization of Sb and the conditions responsible for its formation in the supergene zone. Solubility studies were undertaken at 298.15 K. A value of ΔGfθ (Sb8O11Cl2, s, 298.15 K) = –2576 ±12 kJ mol–1 was derived. Calculations involving sénarmontite, Sb2O3, klebelsbergite, Sb4O4SO4(OH)2 and schafarzikite, FeSb2O4, show that onoratoite is a thermodynamically stable phase only at negligible activities of SO42–(aq) and low activities of Fe2+(aq), at low pH and very high activities of Cl–(aq). This explains why onoratoite is such a rare secondary phase and why it cannot exert any significant influence on the dispersion of Sb in the supergene environment.

scholarly journals Mineralogy and Geochemistry of Fluvial-Lacustrine Pisolith Micronodules from the Roztoka Odrzańska, Odra River, NW Poland

Geosciences ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 3 ◽  
Author(s):  
Łukasz Maciąg ◽  
Urszula Rydzewska ◽  
Artur Skowronek ◽  
Sylwester Salwa
Keyword(s):  
Significant Contribution ◽  
Manganese Content ◽  
River Mouth ◽  
Geochemical Data ◽  
Iron Hydroxides ◽  
Szczecin Lagoon ◽  
Different Types ◽  
Odra River ◽  
Moderate Climate ◽  
Nw Poland

Small-sized ferruginous micronodules or pisolith nodules, frequently occurring in inland freshwater systems in moderate climate zones, are important indicators of groundwater level changes and early diagenetic processes, especially within the Pleistocene post-glacial sedimentary systems, including swamps, peatbogs, rivers, or lakes. Compared to the other geochemical environments, pisolith nodules are usually dominated by iron hydroxides and oxides. In most cases, described micronodules indicate high phosphatization, significant contribution of allogenic detrital components, and low manganese content. The major aim of the article is to present textural, geochemical, and mineralogical variability of pisolith nodules recovered from the Roztoka Odrzańska, Odra river mouth area, NW Poland. We describe genetical relations between different types of pisoliths and try to interpret the possible formation phenomena. Analyzed loose ferruginous micronodules were separated from the lacustrine silty-clayey sapropel muds and gyttja, later analyzed using optical microscopy, SEM-energy dispersive x-ray (EDX), and XRD methods. As a reference material, we use archival iron bog ores and geochemical data of different types of nodules. Additionally, we describe previously unknown siderite-rich nodules found in neighboring sites of the Dąbie Lake and the Szczecin Lagoon.

Role of Iron Sulfide Phases in the Stability of Noncrystalline Tetravalent Uranium in Sediments

2020 ◽  
Vol 54 (8) ◽  
pp. 4840-4846 ◽  
Author(s):  
Luca Loreggian ◽  
Julian Sorwat ◽  
James M. Byrne ◽  
Andreas Kappler ◽  
Rizlan Bernier-Latmani
Keyword(s):  
Iron Sulfide ◽  
Tetravalent Uranium ◽  
The Stability

Complexation, Stability and Behavior of L-Cysteine and L-Lysine with Different Iron Sources

1984 ◽  
Vol 47 (1) ◽  
pp. 36-40 ◽  
Author(s):  
S. M. FLYNN ◽  
F. M. CLYDESDALE ◽  
O. T. ZAJICEK
Keyword(s):  
Ferric Chloride ◽  
Ferrous Sulfate ◽  
Mixed Valence ◽  
Qualitative Evaluation ◽  
Low Ph ◽  
Iron Hydroxides ◽  
The Stability ◽  
Ph Range ◽  
Effective Stability ◽  
And Behavior

Effective stability constants for cysteine and lysine with five different iron sources were evaluated along with their behavior in solution. The values obtained for ferric chloride-cysteine, ferrous sulfate-cysteine, ferric chloride-lysine, ferrous sulfate-lysine, hydrogen-reduced lysine, and electrolytic-reduced lysine were 6.81 × 102 to 2.78 × 103, 1.33 × 105 to 1.36 × 105, 6.00 × 10−4 to 7.64 × 10−3, 6.37 ×10−4 to 4.82× 10−3, 9.34 × 10−2 to 1.38 × 10−1, and 4.18 × 10−4 to 7.27 × 10−4, respectively. No measurable complexation occurred with hydrogen- and electrolytic-reduced iron with cysteine nor with ferric orthophosphate and cysteine or lysine. The stability of soluble ferric cysteine over the pH range 2.0 to 7.4 indicates that this complex has the potential to be used as an iron additive in food. Approximately half of the hydrogen and electrolytic reduced iron and only 0.11% of ferric orthophosphate were soluble in acid, whereas ferric chloride and ferrous sulfate were completely soluble. Qualitative evaluation of the iron-amino acid systems over a range of pH from 2.0 to 12.0 indicated that there was a mixed valence state of free iron in most cases with low pH favoring reduction and high pH oxidation, until precipitation of iron hydroxides occurred.

Distributions of Ferrous Iron and Sulfide in an Anoxic Hypolimnion

1984 ◽  
Vol 41 (2) ◽  
pp. 286-293 ◽  
Author(s):  
Robert B. Cook
Keyword(s):  
Pore Water ◽  
Solubility Product ◽  
Iron Sulfide ◽  
Water Flux ◽  
Sediment Pore Water ◽  
Experimental Lakes Area ◽  
Northwestern Ontario ◽  
Anoxic Hypolimnion ◽  
Decomposition Of Organic Matter

In the anoxic hypolimnion of Lake 227, Experimental Lakes Area, northwestern Ontario, ΣH2S exhibits a mid-depth maximum, while Fe2+ increases with depth. At the mid-depth ΣH2S maximum and below, saturation with respect to amorphous FeS is reached, and the concentration of ΣH2S is limited by the high Fe2+ concentrations, in accord with the FeS solubility product. Values for pKsp[Formula: see text] for FeS determined from the ΣH2S maximum and below averaged 3.16 in 1979 and agree well with other in situ and laboratory measurements. In the top 10 cm of sediment, pore water ΣH2S and Fe2+ are in equilibrium with amorphous FeS. Analyses of cores confirms the existence of an iron sulfide phase. Fe2+, which is produced in the pore water from the decomposition of organic matter, increases to concentrations at which siderite may form, although the presence of siderite has not been verified. Comparison of calculated pore water fluxes of Fe2+ with the observed increase of Fe2+ in the anoxic hypolimnion reveals that about 90% of the observed flux originates at the sediment–water interface, while the remainder is derived from pore water flux.

The Effect of Non-Electrolytes on the Stability of Colloids. II. Ferric Hydroxide Sol

1928 ◽  
Vol 32 (12) ◽  
pp. 1872-1874 ◽  
Author(s):  
S. G. Chaudhury ◽  
Ashutosh Ganguli
Keyword(s):  
Ferric Hydroxide ◽  
The Stability

The geochemical environment of nuclear fuel waste disposal

1996 ◽  
Vol 42 (4) ◽  
pp. 401-409 ◽  
Author(s):  
M. Gascoyne
Keyword(s):  
Nuclear Fuel ◽  
Waste Disposal ◽  
Canadian Shield ◽  
Geochemical Environment ◽  
Research Areas ◽  
Reducing Conditions ◽  
Backfill Materials ◽  
The Stability ◽  
Underground Research Laboratory ◽  
Nuclear Fuel Waste

The concept for disposal of Canada's nuclear fuel waste in a geologic environment on the Canadian Shield has recently been presented by Atomic Energy of Canada Limited (AECL) to governments, scientists, and the public, for review. An important part of this concept concerns the geochemical environment of a disposal vault and includes consideration of rock and groundwater compositions, geochemical interactions between rocks, groundwaters, and emplaced vault materials, and the influences and significance of anthropogenic and microbiological effects following closure of the vault. This paper summarizes the disposal concept and examines aspects of the geochemical environment. The presence of saline groundwaters and reducing conditions at proposed vault depths (500–1000 m) in the Canadian Shield has an important bearing on the stability of the used nuclear fuel, its container, and buffer and backfill materials. The potential for introduction of anthropogenic contaminants and microbes during site investigations and vault excavation, operation, and sealing is described with examples from AECL's research areas on the Shield and in their underground research laboratory in southeastern Manitoba. Keywords: nuclear waste disposal, geochemistry, Canadian Shield, groundwater chemistry.

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