Journal articles on the topic 'Ferruginous sediments'
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Vuillemin, Aurèle, André Friese, Richard Wirth, Jan A. Schuessler, Anja M. Schleicher, Helga Kemnitz, Andreas Lücke, et al. "Vivianite formation in ferruginous sediments from Lake Towuti, Indonesia." Biogeosciences 17, no. 7 (April 14, 2020): 1955–73. http://dx.doi.org/10.5194/bg-17-1955-2020.
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Abstract. Ferruginous lacustrine systems, such as Lake Towuti, Indonesia, are characterized by a specific type of phosphorus cycling in which hydrous ferric iron (oxyhydr)oxides trap and precipitate phosphorus to the sediment, which reduces its bioavailability in the water column and thereby restricts primary production. The oceans were also ferruginous during the Archean, thus understanding the dynamics of phosphorus in modern-day ferruginous analogues may shed light on the marine biogeochemical cycling that dominated much of Earth's history. Here we report the presence of large crystals (>5 mm) and nodules (>5 cm) of vivianite – a ferrous iron phosphate – in sediment cores from Lake Towuti and address the processes of vivianite formation, phosphorus retention by iron and the related mineral transformations during early diagenesis in ferruginous sediments. Core scan imaging, together with analyses of bulk sediment and pore water geochemistry, document a 30 m long interval consisting of sideritic and non-sideritic clayey beds and diatomaceous oozes containing vivianites. High-resolution imaging of vivianite revealed continuous growth of crystals from tabular to rosette habits that eventually form large (up to 7 cm) vivianite nodules in the sediment. Mineral inclusions like millerite and siderite reflect diagenetic mineral formation antecedent to the one of vivianite that is related to microbial reduction of iron and sulfate. Together with the pore water profiles, these data suggest that the precipitation of millerite, siderite and vivianite in soft ferruginous sediments stems from the progressive consumption of dissolved terminal electron acceptors and the typical evolution of pore water geochemistry during diagenesis. Based on solute concentrations and modeled mineral saturation indices, we inferred vivianite formation to initiate around 20 m depth in the sediment. Negative δ56Fe values of vivianite indicated incorporation of kinetically fractionated light Fe2+ into the crystals, likely derived from active reduction and dissolution of ferric oxides and transient ferrous phases during early diagenesis. The size and growth history of the nodules indicate that, after formation, continued growth of vivianite crystals constitutes a sink for P during burial, resulting in long-term P sequestration in ferruginous sediment.
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Bauer, Kohen W., Bleuenn Gueguen, Devon B. Cole, Roger Francois, Jens Kallmeyer, Noah Planavsky, and Sean A. Crowe. "Chromium isotope fractionation in ferruginous sediments." Geochimica et Cosmochimica Acta 223 (February 2018): 198–215. http://dx.doi.org/10.1016/j.gca.2017.10.034.
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Strakhovenko, V. D., N. A. Belkina, N. A. Efremenko, M. S. Potakhin, D. A. Subetto, L. A. Frolova, G. R. Nigamatzyanova, A. V. Ludikova, and E. A. Ovdina. "The First Data on the Mineralogy and Geochemistry of the Suspension of Lake Onego." Russian Geology and Geophysics 63, no. 1 (January 1, 2022): 55–71. http://dx.doi.org/10.2113/rgg20204280.
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Abstract —This paper presents the first data on the mineralogy, geochemistry, and quantitative distribution of suspension determined with the use of sedimentation traps installed in Lake Onego (the exposure time was one year (2019)). The obtained data on the mineralogic and geochemical composition of the recent suspension of the Onego water column are compared with the data for the surface layer of the lake bottom sediments (0–10 cm). Data on the sedimentation rates for the substance determined with the sedimentation traps have been obtained for the first time for Lake Onego. The estimates of the sedimentation rates differ slightly from the results of calculation of the sedimentation rates by radioisotope dating based on the distribution of 210Pb activity in the upper layer of bottom sediments in combination with the data on 137Cs. It has been established that the mineral part of the dispersed sedimentary matter that entered the lake reaches the bottom sediment without significant changes. The geochemistry of the sedimentation traps is similar in many respects to the geochemistry of the upper part of the bottom sediments (0–10 cm) in different areas of Lake Onego. The dispersed sedimentary material and the bottom sediment differ in the amount of the biogenic part (in the bottom sediment layer (0–10 cm), the biogenic part loses a significant part of organic matter). The bottom sediments are characterized by a strong predominance of the ferruginous varieties of illite and chlorite, in contrast to the suspension with the prevailing Mg–Fe varieties of these minerals. Degraded mica minerals brought by rivers are regenerated to normal ferruginous illites and chlorites directly in the uppermost part of the bottom sediments. The bottom sediments are characterized by higher manganese and molybdenum contents, and the material from the sedimentation traps, by high mercury contents.
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Anand, Ravi R., Martin A. Wells, Melvyn J. Lintern, Louise Schoneveld, Martin Danišík, Walid Salama, Ryan R. P. Noble, Vasek Metelka, and Nathan Reid. "The (U-Th)/He Chronology and Geochemistry of Ferruginous Nodules and Pisoliths Formed in the Paleochannel Environments at the Garden Well Gold Deposit, Yilgarn Craton of Western Australia: Implications for Landscape Evolution and Geochemical Exploration." Minerals 11, no. 7 (June 25, 2021): 679. http://dx.doi.org/10.3390/min11070679.
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Ferruginous nodules and pisoliths that cap deeply weathered profiles and transported cover are characteristic of the Yilgarn Craton, Western Australia. Here we show how ferruginous nodules and pisoliths formed in the paleochannel sediments during Miocene can be used to locate buried Au mineralization. Three types of ferruginous nodules and pisoliths were identified in paleochannel sediments and saprolite, representing different parent materials and environments covering the Garden Well Au deposit: (i) ferruginous nodules formed in saprolite on the flanks of the paleochannel (NSP), (ii) ferruginous pisoliths formed in the Perkolilli Shale in the middle of the paleochannel (PPS) and (iii) ferruginous nodules formed in the Wollubar Sandstone at the bottom of the paleochannel (NWS). The appearance, mineralogy and geochemistry of ferruginous nodules and pisoliths vary according to their origin. The PPS and NWS are goethite-rich whereas NSP is a mixture of goethite and hematite which make them all suitable for (U–Th)/He dating. The average age of goethite in the NSP is 14.8 Ma, in the NWS is 11.2 Ma and in the PPS is 18.6 and 14 Ma. The goethite ages in ferruginous nodules and pisoliths are thought to be younger than the underlying saprolite (Paleocene-Eocene) and were formed in different environmental conditions than the underlying saprolite. Anomalous concentrations of Au, As, Cu, Sb, In, Se, Bi, and S in the cores and cortices of the NWS and the PPS reflect the underlying Au mineralization, and thus these nodules and pisoliths are useful sample media for geochemical exploration in this area. These elements originating in mineralized saprolite have migrated both upwards and laterally into the NWS and the PPS, to form spatially large targets for mineral exploration.
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Vuillemin, Aurèle, Fabian Horn, André Friese, Matthias Winkel, Mashal Alawi, Dirk Wagner, Cynthia Henny, William D. Orsi, Sean A. Crowe, and Jens Kallmeyer. "Metabolic potential of microbial communities from ferruginous sediments." Environmental Microbiology 20, no. 12 (October 16, 2018): 4297–313. http://dx.doi.org/10.1111/1462-2920.14343.
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Vuillemin, Aurèle, Richard Wirth, Helga Kemnitz, Anja M. Schleicher, André Friese, Kohen W. Bauer, Rachel Simister, et al. "Formation of diagenetic siderite in modern ferruginous sediments." Geology 47, no. 6 (April 16, 2019): 540–44. http://dx.doi.org/10.1130/g46100.1.
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Johnson, Brooke R., Rosalie Tostevin, Philip Gopon, Jon Wells, Stuart A. Robinson, and Nicholas J. Tosca. "Phosphorus burial in ferruginous SiO2-rich Mesoproterozoic sediments." Geology 48, no. 1 (November 13, 2019): 92–96. http://dx.doi.org/10.1130/g46824.1.
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Abstract Persistently low atmospheric oxygen requires that net organic carbon burial was muted through much of Earth’s middle age. In order to achieve global mass balance with respect to O2, recent models have suggested that redox-dependent mechanisms, such as Fe(II)-phosphate precipitation, limited phosphate availability in dominantly anoxic and ferruginous oceans, in turn limiting net primary production, and therefore organic carbon burial. Nevertheless, observational constraints on phosphorus cycling in ferruginous Proterozoic systems are rare, leaving these models largely untested. Here, we present high-resolution petrographic and mineralogical data showing that the 1.3 Ga Sherwin Ironstone (Roper Group, Australia) was dominated by syndepositional precipitation of the Fe(II)-silicate minerals greenalite and berthierine, interlaminated with abundant authigenic calcium fluorapatite (CFA). Set in a quantitative geochemical framework, these data reveal that elevated marine SiO2(aq) concentrations facilitated extensive Fe(II)-silicate production, leaving CFA, rather than Fe(II)-phosphate, as the principal inorganic phosphorous sink in shallow-water Roper Group sediments. More broadly, the physical and chemical factors that triggered Fe(II)-silicate and CFA burial in the Roper Seaway highlight semi-restricted basins as important loci of phosphorus removal from the mid-Proterozoic ocean.
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Juchen, Carlos Roberto, Cristiano Poleto, Marcio Antonio Vilas Boas, and Rodrigo Trevisani Juchen. "MINERALOGICAL AND CHEMICAL CHARACTERIZATION OF SEDIMENTS FROM IMPERVIOUS URBAN STREETS." Journal of Urban and Environmental Engineering 10, no. 2 (April 28, 2017): 194–200. http://dx.doi.org/10.4090/juee.2016.v10n2.194-200.
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This study aimed to determine the granulometric and mineralogical composition and the contents of trace elements Cr, Ni and Pb in sediments collected in impermeable streets located in the urban perimeter of Toledo PR, Brazil. The mineralogical analyses were performed by a diffractometer, the granulometric by integrated sieving methods and laser diffraction, trace elements in sediment quartered fractions by optical emission spectrometry with inductively coupled plasma (ICP-OES). It was concluded that the sediments with an average granulometric greater than 0.09 mm and finer fractions represented by the clay. The mineralogy identified ferruginous substances characteristics of Distroferric Red Latosol - DRL with high presence of quartz and diopside. Statistically it was shown that the concentrations of the trace elements in sediment samples had a significant enrichment for Chromium and Nickel in the central area’s streets and the Lead in lower concentrations in the streets of the periphery areas. The sediments have an average particle size with diameters greater than 0.09 mm, represented by sand, and the fine sediments represent 2 to 6% of samples. The software indicated that the sediments are from different anthropogenic sources. The diffractograms show peaks for quartz and diopside. The enrichment for trace elements was significant for chromium and nickel on the downtown area streets.
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Juchen, Carlos Roberto, Cristiano Poleto, Marcio Antonio Vilas Boas, and Rodrigo Trevisani Juchen. "MINERALOGICAL AND CHEMICAL CHARACTERIZATION OF SEDIMENTS FROM IMPERVIOUS URBAN STREETS." Journal of Urban and Environmental Engineering 10, no. 2 (April 28, 2017): 194–200. http://dx.doi.org/10.4090/juee.2016.v10n2.194200.
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This study aimed to determine the granulometric and mineralogical composition and the contents of trace elements Cr, Ni and Pb in sediments collected in impermeable streets located in the urban perimeter of Toledo PR, Brazil. The mineralogical analyses were performed by a diffractometer, the granulometric by integrated sieving methods and laser diffraction, trace elements in sediment quartered fractions by optical emission spectrometry with inductively coupled plasma (ICP-OES). It was concluded that the sediments with an average granulometric greater than 0.09 mm and finer fractions represented by the clay. The mineralogy identified ferruginous substances characteristics of Distroferric Red Latosol - DRL with high presence of quartz and diopside. Statistically it was shown that the concentrations of the trace elements in sediment samples had a significant enrichment for Chromium and Nickel in the central area’s streets and the Lead in lower concentrations in the streets of the periphery areas. The sediments have an average particle size with diameters greater than 0.09 mm, represented by sand, and the fine sediments represent 2 to 6% of samples. The software indicated that the sediments are from different anthropogenic sources. The diffractograms show peaks for quartz and diopside. The enrichment for trace elements was significant for chromium and nickel on the downtown area streets.
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Petrash, Daniel A., Ingrid M. Steenbergen, Astolfo Valero, Travis B. Meador, Tomáš Pačes, and Christophe Thomazo. "Aqueous system-level processes and prokaryote assemblages in the ferruginous and sulfate-rich bottom waters of a post-mining lake." Biogeosciences 19, no. 6 (March 24, 2022): 1723–51. http://dx.doi.org/10.5194/bg-19-1723-2022.
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Abstract. In the low-nutrient, redox-stratified Lake Medard (Czechia), reductive Fe(III) dissolution outpaces sulfide generation from microbial sulfate reduction (MSR) and ferruginous conditions occur without quantitative sulfate depletion. The lake currently has marked overlapping C, N, S, Mn and Fe cycles occurring in the anoxic portion of the water column. This feature is unusual in stable, natural, redox-stratified lacustrine systems where at least one of these biogeochemical cycles is functionally diminished or undergoes minimal transformations because of the dominance of another component or other components. Therefore, this post-mining lake has scientific value for (i) testing emerging hypotheses on how such interlinked biogeochemical cycles operate during transitional redox states and (ii) acquiring insight into redox proxy signals of ferruginous sediments underlying a sulfatic and ferruginous water column. An isotopically constrained estimate of the rates of sulfate reduction (SRRs) suggests that despite high genetic potential, this respiration pathway may be limited by the rather low amounts of metabolizable organic carbon. This points to substrate competition exerted by iron- and nitrogen-respiring prokaryotes. Yet, the planktonic microbial succession across the nitrogenous and ferruginous zones also indicates genetic potential for chemolithotrophic sulfur oxidation. Therefore, our SRR estimates could rather be portraying high rates of anoxic sulfide oxidation to sulfate, probably accompanied by microbially induced disproportionation of S intermediates. Near and at the anoxic sediment–water interface, vigorous sulfur cycling can be fuelled by ferric and manganic particulate matter and redeposited siderite stocks. Sulfur oxidation and disproportionation then appear to prevent substantial stabilization of iron monosulfides as pyrite but enable the interstitial precipitation of microcrystalline equant gypsum. This latter mineral isotopically recorded sulfur oxidation proceeding at near equilibrium with the ambient anoxic waters, whilst authigenic pyrite sulfur displays a 38 ‰ to 27 ‰ isotopic offset from ambient sulfate, suggestive of incomplete MSR and open sulfur cycling. Pyrite-sulfur fractionation decreases with increased reducible reactive iron in the sediment. In the absence of ferruginous coastal zones today affected by post-depositional sulfate fluxes, the current water column redox stratification in the post-mining Lake Medard is thought relevant for refining interpretations pertaining to the onset of widespread redox-stratified states across ancient nearshore depositional systems.
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Jones, C., S. A. Crowe, A. Sturm, K. L. Leslie, L. C. W. MacLean, S. Katsev, C. Henny, D. A. Fowle, and D. E. Canfield. "Biogeochemistry of manganese in ferruginous Lake Matano, Indonesia." Biogeosciences 8, no. 10 (October 26, 2011): 2977–91. http://dx.doi.org/10.5194/bg-8-2977-2011.
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Abstract. This study explores Mn biogeochemistry in a stratified, ferruginous lake, a modern analogue to ferruginous oceans. Intense Mn cycling occurs in the chemocline where Mn is recycled at least 15 times before sedimentation. The product of biologically catalyzed Mn oxidation in Lake Matano is birnessite. Although there is evidence for abiotic Mn reduction with Fe(II), Mn reduction likely occurs through a variety of pathways. The flux of Fe(II) is insufficient to balance the reduction of Mn at 125 m depth in the water column, and Mn reduction could be a significant contributor to CH4 oxidation. By combining results from synchrotron-based X-ray fluorescence and X-ray spectroscopy, extractions of sinking particles, and reaction transport modeling, we find the kinetics of Mn reduction in the lake's reducing waters are sufficiently rapid to preclude the deposition of Mn oxides from the water column to the sediments underlying ferruginous water. This has strong implications for the interpretation of the sedimentary Mn record.
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Ayupova, N. R., V. V. Maslennikov, and V. V. Shilovskikh. "Authigenic Ti mineralization as an indicator of halmyrolysis of carbonatesulfide-hyaloclastite sediments in Urals massive sulfide deposits." LITHOSPHERE (Russia) 22, no. 6 (January 7, 2023): 847–58. http://dx.doi.org/10.24930/1681-9004-2022-22-6-847-858.
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Research subject. The horizons of ferruginous sedimentary rocks in the massive sulfide deposits of the Urals.Aim. To estimate the Ti behavior upon halmyrolytic transformation and lithogenesis of calcareous hyaloclastites and carbonatesulfide-hyaloclastite sediments.Materials and methods. Microtextures of authigenic aggregates of Ti minerals (anatase, rutile, titanite) in jasperites and gossanites of various Urals massive sulfide deposits were studied. The minerals were identified using microscopic and electron microscopic methods, as well as electron back-scattered diffraction.Results. Upon partial halmyrolysis of calcareous hyaloclastites, Ti was removed with the formation of authigenic anatase rims around hematitized hyaloclasts. The full transformation of hyaloclastites to hematite-quartz jasperites resulted in decomposition of authigenic Ti minerals. Authigenic rutile and titanite formed in gossanites (hematite-quartz and hematite-chlorite products of submarine oxidation of calcareous sulfide-hyaloclastite sediments). The occurrence of abundant bacteriomorphic structures in corroded hyaloclasts indicates a significant role of bacteria in halmyrolysis.Conclusions. Titanium for the formation of Ti minerals in ferruginous sediments was sourced from hyaloclastites. The halmyrolysis of calcareous hyaloclastite sediments and related formation of jasperites occurred under alkaline conditions favorable for the transportation of Ti in the form of hydroxycarbonate complexes. The formation of rutile instead of anatase was associated with lower pH values (<5) due to oxidation of pyrite in sulfide-bearing hyaloclastite sediments. Titanite formed as a result of further alteration of Ti-bearing phases. Our results solve the fundamental problem of Ti mobility during halmyrolysis of hyaloclastites, which contradicts its commonly accepted immobility in hydrothermal processes.
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Li, Qianqian, Rebecca E. Cooper, Carl-Eric Wegner, Martin Taubert, Nico Jehmlich, Martin von Bergen, and Kirsten Küsel. "Insights into Autotrophic Activities and Carbon Flow in Iron-Rich Pelagic Aggregates (Iron Snow)." Microorganisms 9, no. 7 (June 23, 2021): 1368. http://dx.doi.org/10.3390/microorganisms9071368.
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Pelagic aggregates function as biological carbon pumps for transporting fixed organic carbon to sediments. In iron-rich (ferruginous) lakes, photoferrotrophic and chemolithoautotrophic bacteria contribute to CO2 fixation by oxidizing reduced iron, leading to the formation of iron-rich pelagic aggregates (iron snow). The significance of iron oxidizers in carbon fixation, their general role in iron snow functioning and the flow of carbon within iron snow is still unclear. Here, we combined a two-year metatranscriptome analysis of iron snow collected from an acidic lake with protein-based stable isotope probing to determine general metabolic activities and to trace 13CO2 incorporation in iron snow over time under oxic and anoxic conditions. mRNA-derived metatranscriptome of iron snow identified four key players (Leptospirillum, Ferrovum, Acidithrix, Acidiphilium) with relative abundances (59.6–85.7%) encoding ecologically relevant pathways, including carbon fixation and polysaccharide biosynthesis. No transcriptional activity for carbon fixation from archaea or eukaryotes was detected. 13CO2 incorporation studies identified active chemolithoautotroph Ferrovum under both conditions. Only 1.0–5.3% relative 13C abundances were found in heterotrophic Acidiphilium and Acidocella under oxic conditions. These data show that iron oxidizers play an important role in CO2 fixation, but the majority of fixed C will be directly transported to the sediment without feeding heterotrophs in the water column in acidic ferruginous lakes.
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Ayupova, N. R., and V. V. Maslennikov. "Biomineralization in ferruginous-siliceous sediments of massive sulfide deposits of the Urals." Doklady Earth Sciences 442, no. 2 (February 2012): 193–95. http://dx.doi.org/10.1134/s1028334x12020110.
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Holm, Nils G. "Biogenic influences on the geochemistry of certain ferruginous sediments of hydrothermal origin." Chemical Geology 63, no. 1-2 (July 1987): 45–57. http://dx.doi.org/10.1016/0009-2541(87)90073-8.
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Srivastava, S. C., and Neerja Jha. "Status of Kamthi Formation: lithological and palaeobotanical evidences." Journal of Palaeosciences 46, no. (1-2) (December 31, 1997): 88–96. http://dx.doi.org/10.54991/jop.1997.1321.
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On the basis of lithological, palynological and megafloral data the status of Kamthi Formation has been reviewed. Hitherto known Kamthi Formation which was said to be a time-transgressive unit (Permian-Triassic) actually represents a Triassic sequence overlying Permian sediments equivalent to Raniganj Formation. The presence of Permian taxa, viz., Glossopteris, Vertebraria and Phyllotheca in red claystone, ferruginous sandstone/shale unit (=Upper Member, Kamthi Formation) represent only the continuations of Permian taxa into the Triassic.
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Bravo, Andrea G., Sylvain Bouchet, Stéphane Guédron, David Amouroux, Janusz Dominik, and Jakob Zopfi. "High methylmercury production under ferruginous conditions in sediments impacted by sewage treatment plant discharges." Water Research 80 (September 2015): 245–55. http://dx.doi.org/10.1016/j.watres.2015.04.039.
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Brusnitsyn, A. I., E. V. Starikova, M. V. Ignatova, and V. N. Kuleshov. "The Nadeiyakha Ore occurrence (Pai-Khoi, Russia): an example of ferromanganese metasediments in carbonaceous dolomitic shales." Литология и полезные ископаемые, no. 2 (March 28, 2019): 165–92. http://dx.doi.org/10.31857/s0024-497x20192165-192.
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The paper presents the results of study of metalliferous (ferromanganese and manganese) rocks at the Nadeiyakha ore occurrence (Pai-Khoi) discovered in 2010. The metalliferous deposit represents a stratiform body lying conformably in the Upper Devonian carbonaceous siliceous and clayey–carbonate–siliceous shales. The ore bed occurs 180 m below the regional Famennian manganiferous rock association in Pai-Khoi. Discovery of the Nadeiyakha ore occurrence suggests the existence of an additional age interval of Mn accumulation within the Devonian sequence of this region. The studied metalliferous rocks display structures and textures typical of the metasedimentary rocks. In terms of composition, they are divided into two varieties: (i) ferromanganese (quartz–carbonate) rocks composed of quartz, dolomite, kutnahorite, rhodochrosite, siderite, and calcite; (ii) manganiferous (quartz–rhodochrosite–silicate) rocks composed of quartz, rhodochrosite, tephroite, sonolite, and pyroxmangite. The Nadeiyakha ore occurrence is marked by the abundance of dolomite in the ferromanganese rocks and host shales. In terms of the relationship of indicator elements (Al, Ti, Fe, and Mn), ferromanganese and manganese rocks are comparable with the recent metalliferous and ore-bearing sediments. The carbon isotope composition in carbonates (δ13C from –16.4 to –7.8‰ PDB) corresponds to authigenic carbonates related to the involvement of carbon dioxide produced during the microbial decomposition of organic matter at the stage of dia- and/or catagenesis. Geological and petrographic observations show that the ferruginous and manganiferous sediments were deposited synchronously with the terrigenous–carbonate–siliceous sediments. Fe and Mn could be sourced from hydrothermal solutions or interstitial diagenetic waters. The latter version seems to be more probable. Metals were accumulated in a depression-trap characterized by a periodic stagnation of bottom waters. Such sedimentation setting promoted the formation of paragenetic association of ferruginous and manganiferous sediments with the carbonaceous sediments and fostered reductive conditions during the postsedimentary mineral formation. Calcium carbonates contained in the primary rocks were subjected to dolomitization during the dia- or catagenesis. This process was promoted by the mobilization of Mg released during the transformation of clay minerals owing to the montmorillonite–illite transition. Iron and manganese carbonates were formed during the later replacement of oxides of Mn3+, Mn4+, and Fe3+. Crystallization of manganese silicates also started at early stages of lithogenesis and terminated during the regional metamorphism of metalliferous rocks.
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Drabon, Nadja, Christoph E. Heubeck, and Donald R. Lowe. "Evolution of an Archean fan delta and its implications for the initiation of uplift and deformation in the Barberton greenstone belt, South Africa." Journal of Sedimentary Research 89, no. 9 (September 11, 2019): 849–74. http://dx.doi.org/10.2110/jsr.2019.46.
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ABSTRACT The 3.28 to 3.23 Ga Mapepe Formation in the Barberton greenstone belt, South Africa, marks the initiation of widespread tectonic uplift and deformation after nearly 300 million years of predominantly basaltic and komatiitic magmatism under largely anorogenic conditions. This rapid transition is recorded in the eastern Barite Valley area by the buildup of a fan delta. Well-exposed sections there reach about 450 m thick and can be divided (from base to top) into five informal members: Member 1 is dominated by mudstone with subordinate banded ferruginous chert and turbiditic sandstone representing a deep-water basinal environment. Member 2 is composed of siltstone and fine-grained sandstone reworked by currents to form laminated, cross-laminated, and low-angle cross-stratified sediments in an off-shore or possibly subtidal fan-delta-front setting. Member 3 overlies member 2 unconformably; it is composed of predominantly coarse-grained, cross-bedded sandstone interbedded with laminated mudstone deposited on shallow-subtidal to intertidal flats along the fringe of a small fan delta in which putative microbial mats covered low-energy upper tidal flats. Fan-delta sedimentation was subsequently overwhelmed by the influx of dacitic pyroclastic sediments of member 4. Orthochemical sedimentary rocks including barite, jaspilite, and chert deposited on top of this shallow-water bank. Mappable facies changes towards the northeast and southwest document the transition from bank top into major mass-transport deposits of fan-delta slope facies and then into basinal deposits. Subsequent relative sea-level rise resulted in the return to below-wave-base deposition of turbiditic sandstone, mudstone, and banded ferruginous chert of member 5. The lenticular geometry of units in cross section, mineralogical immaturity, and high variability in provenance of the coarse-grained units imply short-distance transport of sediment derived from strata of the underlying Onverwacht Group and from local penecontemporaneous dacitic volcanism. Throughout the greenstone belt, Mapepe rocks in several structural belts display fan deltas developed adjacent to small, local uplifts. While the cause of these uplifts has generally been associated with the initiation of geodynamically driven tectonic activity in the BGB, it is possible that a cluster of large meteorite impacts may have directly or indirectly triggered the crustal deformation.
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Strakhovenko, Vera, Dmitry Subetto, Ekaterina Ovdina, Natalia Belkina, and Natalia Efremenko. "Distribution of Elements in Iron-Manganese Formations in Bottom Sediments of Lake Onego (NW Russia) and Small Lakes (Shotozero and Surgubskoe) of Adjacent Territories." Minerals 10, no. 5 (May 14, 2020): 440. http://dx.doi.org/10.3390/min10050440.
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The morphology and mineralogical and geochemical compositions of the freshwater ferromanganese formations (FMF) of Lake Onego (NW Russia) and small lakes located in its catchment area were studied. The lake waters, bottom sediments and FMF were analyzed by a set of modern methods of geochemistry, mineralogy, and crystal chemistry (powder X-ray diffraction, IR spectroscopy, electron microscopy, ICP–MS analysis, atomic absorption, etc.). A detailed description of the microscopic structure in comparison with the geochemical characteristics of the FMF provides new information on the role of biota in the formation and behavior of individual elements at various stages in the nodule formation process. This study shows the homogeneous composition of microconcretions—only manganese or only ferruginous—in bottom sediments throughout the entire water area of Lake Onego and the rhythmic structures of the nodules, formed by macro- and microlayers with mineralized microbiota. The layers are composed of either crystalline Mn mineral phases (pyrolusite, rhodochrosite) or crystalline Fe mineral phases (siderite, goethite). The separation of Mn and Fe mineral phases in the nodules proceeded during their formation and diagenesis. The examined chemical and mineral compositions, textures, and structures of the nodules are a testament to the hydrogenic source of their ore substance and the formation of FMF is controlled primarily by redox environments at the water–sediment interface.
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Soares de Almeida, Gabriel, Eduardo Duarte Marques, Francisco José da Silva, Claiton Piva Pinto, and Emmanoel Vieira Silva-Filho. "APPLICATION OF pXRF (FIELD PORTABLE X-RAY FLUORESCENCE) TECHNIQUE IN FLUVIAL SEDIMENTS GEOCHEMICAL ANALYSIS – BULE STREAM, MINAS GERAIS STATE, BRAZIL." Journal of Sedimentary Environments 4, no. 2 (June 11, 2019): 143–58. http://dx.doi.org/10.12957/jse.2019.43279.
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A new methodology based on a portable X-ray fluorescence (pXRF) was applied in this work to analyze the geochemical dispersion halo of a sulfide mineralization along the Bule Stream sediments (Ouro Branco, Minas Gerais State, Brazil). The study area, located in the Iron Quadrangle (QF), has an important sulfide occurrence of antimony and zinc, which was explored between 1920s and 1930s. Stream sediment samples were collected along the Bule Stream and from some of its tributaries. Aluminum, Fe, Ca, Mg, Mn and Ti contents were obtained by the pXRF “mining mode” and quantified in percentage (%), while the results for Cu, Zn, Pb, As, Cr, Ag, Sb and Sr were carried out by the pXRF “soil mode”, quantified in parts per million (ppm). The statistical treatment of data by Spearman correlation based on geochemical data and some sediment features were discussed, such as the geochemical affinities between the analyzed elements and supergene processes which control the elemental dispersion. Aluminum, Ca and Mg contents were compared with that of the Upper Continental Crust (UCC), since the composition of the Bule Stream sediments should be related to the composition of the source rocks. The results indicate that the Al contents reflect the surrounding soil maturity. The concentrations of Ca and Mg increase in weathered resistant mineral phases, mainly dolomite. The Fe enrichment is associated with geological units containing this element, such as dolomite/ferruginous itabirites (BIF). The high Mn content is related to the QF unity with larger dolomite occurrence (Gandarela Formation). Secondary environmental characteristics can justify the enrichment of Zn and Cu in the study area. All types of rocks have significant concentration of Cr. The comparison of the elemental concentrations of Bule Stream sediments with the average concentration of the elements in the Earth's upper crust (UCC) reveals intense weathering rate of the parent rocks characterized by high maturity of the geological material, enrichment of Fe and Mn and most of the analyzed trace metals. The results of an enrichment factor with three different normalizers (Al representing clay minerals; Fe + Mn representing oxides/hydroxides and; Ca + Mg representing carbonates) indicate that the carbonate phase is the main conveyor of trace elements. APLICAÇÃO DA TÉCNICA DE pXRF NA ANÁLISE GEOQUÍMICA DE SEDIMENTOS FLUVIAIS – RIBEIRA BULE, ESTADO DE MINAS GERAIS, BRASIL ResumoUma nova metodologia baseada na fluorescência de raios X portátil (pXRF) foi aplicada neste trabalho para analisar o halo de dispersão geoquímica de uma mineralização de sulfeto ao longo dos sedimentos Córrego do Bule (Ouro Branco, Minas Gerais, Brasil). A área de estudo, localizada no Quadrilátero Ferrífero (QF), tem uma importante ocorrência de sulfeto de antimônio e zinco, que foi explorada entre as décadas de 1920 e 1930. Amostras de sedimentos fluviais foram coletadas ao longo do Córrego do Bule e em de alguns dos seus afluentes. Os teores de Al, Fe, Ca, Mg, Mn e Ti foram obtidos por pXRF em “mining mode” e quantificados em porcentagem (%), enquanto os resultados de Cu, Zn, Pb, As, Cr, Ag, Sb e Sr foram obtidos pelo pXRF em “soil mode” e foram quantificados em partes por milhão (ppm). Este trabalho analisa o tratamento estatístico dos dados por correlação de Spearman com base em dados geoquímicos e algumas características do sedimento, assim como as afinidades geoquímicas entre os elementos analisados e os processos supergênicos que controlam a dispersão dos elementos químicos. Os teores de Al, Ca e Mg foram comparados com os da Crosta Continental Superior (UCC), uma vez que a composição dos sedimentos do Córrego do Bule devem estar relacionados à composição das rochas geradoras. Os resultados indicam que o teor de Al reflete a maturidade do solo ao redor. As concentrações de Ca e Mg aumentam nas fases minerais resistentes às intempéries, principalmente dolomita. O enriquecimento de Fe está associado a unidades geológicas que contêm esse elemento, como o itabirito dolomítico e/ou dolomito ferruginoso (BIF). O alto teor de Mn está relacionado à unidade de QF com maior ocorrência de dolomita (Formação Gandarela). Características ambientais secundárias podem justificar o enriquecimento de Zn e Cu na área de estudo. Todos os tipos de rochas possuem concentração significativa de Cr. A comparação das concentrações elementares dos sedimentos da corrente de Bule com as concentrações médias dos elementos da Terra (UCC) revela intensa taxa de intemperismo das rochas-mãe caracterizadas pela alta maturidade do material geológico, enriquecimento de Fe e Mn e a maioria dos metais traço analisados. Os resultados de um fator de enriquecimento com três diferentes normalizadores (Al representando minerais argilosos; Fe + Mn representando óxidos / hidróxidos e; Ca + Mg representando carbonatos) indicam que a fase carbonatada é o principal transportador de elementos químicos.Palavras-chave: Geoquímica. Quadrilátero de Ferro. Sedimentos. Fluorescência Portátil de Raios X. Metais. Fatores de Enriquecimento.
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Rudmin, M. A., A. K. Mazurov, V. I. Sergienko, O. G. Savichev, and I. P. Semiletov. "Sources of paleomagnetic signal in iron-bearing marine sedimentary deposits." Доклады Академии наук 486, no. 1 (May 10, 2019): 53–56. http://dx.doi.org/10.31857/s0869-5652486153-56.
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This paper presents the results of interpreting the change in the magnetic signal of ferruginous marine sedimentary rocks using the example of the Cretaceous-Paleogene Bakchar deposit (Western Siberia). Anomalous magnetic susceptibility (MS) values are determined by two factors: (a) a diagenetic process accompanied by the formation of pyrrhotite, greigite and siderite in ironstones, (b) an increase detrital input with deposition of magnetite and ilmenite in the siltstones on the background of climate moistening and intense weathering. It is shown that increased MS values in iron-bearing marine sedimentary deposits can be associated with the formation of ferrimagnetic sulfides, which indicates to the methane emission through ancient marine bottom sediments.
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Zamana, L. V. "Mineral waters and sediments of the ferruginous spring Ulan-Bulak Urulyunguevsky (South-Eastern Transbaikalia, Russia)." IOP Conference Series: Earth and Environmental Science 962, no. 1 (January 1, 2022): 012063. http://dx.doi.org/10.1088/1755-1315/962/1/012063.
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Abstract The data on the chemical composition and content of balneological components (Fe, H2SiO3, CO2, S2-) for three water samples from the Ulan-Bulak acidic ferruginous spring are presented. For the first time, carbonic water was released in the composition of the spring waters, the origin of which is explained by the ingress of hydrocarbonate water into an acidic medium, followed by dissociation according to the HCO3 - + H+ → H2CO3 → H2O + CO2 scheme. An acidic environment is formed as a result of oxidation of sulfide mineralization, presumably gold-bearing. From secondary minerals at the spring, modern sulfate minerals (gypsum, jarosite), hydromica (illite) were found, ocher sediments are widely developed. Given the uncertain nature of the formation of the spring waters, it is considered worthy of special studies, including an inspection of the presence of sulfide mineralization.
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Stea, Rudolph R., and Susan E. Pullan. "Hidden Cretaceous basins in Nova Scotia." Canadian Journal of Earth Sciences 38, no. 9 (September 1, 2001): 1335–54. http://dx.doi.org/10.1139/e01-023.
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Early Cretaceous unconsolidated quartz sand and kaolinitic clay deposits in the lowlands of Nova Scotia are preserved in narrow half-grabens obscured by glacial drift. The Chaswood Formation sediments can be subdivided into three members; upper and lower members dominated by cyclical sandmud facies of fluvial origin and the middle member with lignitic clay of lacustrine origin. Ferruginous oxisols are common in the fine-grained facies of the upper and lower members. Seismic data indicate that Chaswood Formation strata in the Elmsvale Basin are deformed into steeply dipping faults and fault-related folds (Rutherford Road fault zone). An AptianAlbian age for this tectonic event is inferred from synsedimentary deformation and from the angular unconformity spanning the Late Cretaceous and Tertiary that truncates the Chaswood Formation. Exhumation of a thick cover of Mesozoic sediment (12 km) is needed to account for the preservation of Chaswood Formation outliers after ~80 Ma of erosion. The half-grabens that host the Chaswood Formation were formed in the Mesozoic and were antecedent to the present-day structurally controlled lowlands.
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Kaykun, Armagan. "Sequence stratigraphy of the lower Pierre Shale of the southern Powder River Basin: A ramp margin sequence that terminates Niobrara Formation carbonate deposition." Interpretation 6, no. 1 (February 1, 2018): SA7—SA13. http://dx.doi.org/10.1190/int-2017-0038.1.
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The Upper Cretaceous section of the southern Powder River Basin of the Rocky Mountain region includes the Niobrara Formation, which is one of the most significant source rocks of the Western Interior Cretaceous Seaway, and it is overlain by the lower Pierre Shale interval. The lower Pierre Shale is divided into eight members, which are the progradational highstand deposits of the Gammon Ferruginous Member; lowstand prograding wedge deposits of the Shannon Sandstone, the Unnamed Member, and the Sussex Sandstone; transgressional Ardmore Pedro Bentonite Beds and Sharon Springs members; and highstand deposits of the Mitten Black Shale and Red Bird Silty members. The Shannon and Sussex Sandstone members are known targets for oil production. Based on integrated research of 1490 well logs with two cores, this study demonstrates that the lower Pierre Shale interval is a Type 1 Ramp Margin Sequence. Although previous studies primarily focused on individual sandstone members or parts of the lower Pierre Shale section in relatively limited areas, this study provides an in-depth sequence stratigraphic analysis of the lower Pierre Shale interval. A depositional model was created, which demonstrates that the Shannon Sandstone, Unnamed, and Sussex Sandstone Members were deposited as an encased lowstand prograding wedge between the progradational Gammon Ferruginous Member and the transgressional Ardmore Pedro Bentonite Beds and Sharon Springs members hundreds of miles basinward from the stratigraphically equal Mesaverde lowstand sandstones of the Bighorn Basin. The shift of facies across long distances is explained with a forced regression that has taken place during the deposition of the uppermost Gammon Ferruginous Member and the following deposition of the Shannon and Sussex sandstone members. Rapid eastward progradation of the clastic sediments of the lower Pierre Shale and the following rapid forced regression effectively terminate the deposition of the Niobrara Formation carbonates in the Western Interior Seaway.
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Radoicic, Rajka, Divna Jovanovic, and Milan Sudar. "Stratigraphy of the Krs Gradac section (SW Serbia)." Annales g?ologiques de la Peninsule balkanique, no. 70 (2009): 23–41. http://dx.doi.org/10.2298/gabp0970023r.
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In the Krs Gradac section (near to Sjenica, SW Serbia), a transition of a carbonate platform to basin facies are outcropped: Norian-lower Liassic shallow-water carbonates, middle Liassic-lower Dogger Ammonitico Rosso facies, and upper Bathonian into lowermost Cretaceous deep-water radiolarites in which the carbonate graded bed and mass flow layer are intercalated. The presence of a lower Dogger condensed sequence with the Bajocian protoglobigerinid event was hitherto not evidenced. It is documented that components of a graded bed are of extrabasinal (upper Triassic-lower Tithonian carbonate platform sediments) and intrabasinal (radiolarite, meta-andesite) origin, indicating a tectonic event not older than the early Tithonian. This tectonic event caused the fracturing of the carbonate platform, also partly basinal area. Consequently, the age of the graded bed is not older than the lower Tithonian. In the uppermost radiolaritic sediments in the Krs Gradac section (?middle-upper Tithonian-lowermost Cretaceous), a mass flow layer appears, which contains clasts of intrabasinal origin - different radiolarites, siliceous radiolarian argillites (some of which are unconsolidated with washed radiolarians and sponge spicules in a ferruginous sediment), sandstone grains, etc. The mass flow event is estimated as Berriasian. In the Krs Gradac radiolarite succession, the authors recognized two deep-water formations, an older one, upper Bathonian-lower Tithonian, between hardground (Dogger) and a graded bed, and a younger formation, which started with a graded bed. This formation, according to its stratigraphic position, corresponds to ?middle-upper Tithonian-lowermost Cretaceous.
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Ivanova, Irina. "Geochemistry of strontium in fresh underground waters of the Sredneobskoy basin (Tomsk region, Russia)." E3S Web of Conferences 98 (2019): 01024. http://dx.doi.org/10.1051/e3sconf/20199801024.
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In the central part of Western Siberia a study of the chemical composition of fresh underground waters in the upper 600 m of the Sredneobskoy artesian basin was carried out. It was shown that underground waters generally contain high concentrations of strontium. The minimum concentrations of Sr are typical for Neogene-Quaternary sediments (600 µg/L), maximum values in the waters of the Upper Cretaceous sediments (more than 1300 µg/L). The study of strontium accumulation mechanisms in drinking underground waters is undoubtedly an important issue, as strontium is a biologically active element. Especially dangerous is the consumption of underground waters with a calcium-strontium ratio less than 100, that is the hydrogeochemical precondition for Urov endemic (Kashin-Beck disease). According to the calcium/strontium ratios data waters of the Neogene-Quaternary and Paleogene sediments selected in the south-western part of the Tomsk region are unsuitable for drinking water supply. Underground waters are shown to be in equilibrium with Al and Fe hydroxides; Ca, Mg, Fe carbonates; and clay minerals, including ferruginous. Increased strontium content in aquifers is determined not only by the chemical composition of the water-bearing rocks, but also increasing resident time of water rock interaction.
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Elysee Guede, Kore, Chiaye Larissa Koffi, Yapi Desire Sosthene Ronald Atto, NGa-Yah Rosine Adina Befa-Kandet Messou, Idriss-Zayn Al-Abidine Diarra, Kassi Adjoua Maryline-Audrey Edjeme, and Ngoran Jean-Paul Yao. "LITHOSTRATIGRAPHIE ET SEDIMENTOLOGIE DES FORMATIONS SEDIMENTAIRES DE TIAPOUM, SUD-EST DE LA COTE D IVOIRE : IMPLICATION PALEOENVIRONNEMENTALE." International Journal of Advanced Research 10, no. 10 (October 31, 2022): 1407–25. http://dx.doi.org/10.21474/ijar01/15618.
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Tiapoumdepartment is located in the southeast of the onshore basin of Cote dIvoire. The sedimentological, granulometric and morphoscopic analyzes carried out on 24 samples from two wells made it possible to determine the lithological, granulometric and paleoenvironmental evolution of the sediments of this area. The lithological characterization of the sediments revealed four lithological facies in the department of Tiapoum. We therefore have in the direction of sedimentation, a thick layer of clay-sandy, sands intercalated with ferruginous sandstone absent at Aby crossroads and the land of the bar which thins from upstream to downstream. As for the particle size analysis, it reveals that the sands of the department of Tiapoum were deposited by free accumulation. These are well to very well graded sands with a predominance of medium grains with an asymmetry towards the fine grains. They were deposited in a fluvial-type environment transported mainly by suspension and rolling and sometimes by saltation. Morphoscopy of the quartz grains revealed an abundance of sub-angular to sub-rounded grains with a shiny blunt appearance showing fractures or cracks due to shocks between the grains during transport. The sands of the department of Tiapoum therefore come mainly from distal environments and are transported by water. The environment that prevailed during the deposit of the Tiapoum department sediments is of the oxidized continental type and reworked in places.
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Kaufhold, Stephan, George D. Chryssikos, George Kacandes, Vassilis Gionis, Kristian Ufer, and Reiner Dohrmann. "Geochemical and mineralogical characterization of smectites from the Ventzia basin, western Macedonia, Greece." Clay Minerals 54, no. 1 (February 14, 2019): 95–107. http://dx.doi.org/10.1180/clm.2019.8.
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AbstractThree samples of bulk smectite clay from the Pilori and Velanida bentonite deposits of the Ventzia basin, western Macedonia, Greece, were characterized in detail. Chemical analyses and X-ray diffraction (XRD; Rietveld method) showed that the samples are rich in Fe and Mg (8–13 mass% and 6–10 mass% as oxides, respectively) and contain ~60–65 mass% smectite. The high Fe and Mg content as well as the high Cr (0.3–0.5 mass%) and Ni content (0.1–0.3 mass%) are consistent with the formation of these clays from ultramafic precursor sediments of the Vourinos ophiolite complex. Both XRD and infrared spectroscopy indicate the presence of other clay minerals besides smectite, such as minor amounts of kaolinite, trioctahedral-rich palygorskite, serpentine and talc (depending on the sample). The position of the d060 reflection (1.51–1.52 Å) is compatible with either high Fe content or partial trioctahedral character, or probably both. The predominance of ferruginous smectite or nontronite was confirmed by infrared spectroscopy, but the minor presence of a trioctahedral magnesian smectite in some of the samples cannot be excluded. Layer charge densities, determined by the νO-D (oxygen-deuterium IR-stretching) method calibrated against the structural formula method, are in the 0.48–0.52 eq/FU range. Various methods point to the existence of a significant amount of tetrahedral charge, which is typical of ferruginous smectites. The major exchangeable cation is Mg2+ (73–90%), which represents a special property of these materials compared with other bentonites.
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Itam, Asukwo Essien, Victoria Inyang Emeka, and Chimezie Ndunagum Emeka. "FORAMINIFERAL STUDY OF NKPORO SHALE EXPOSURES, CALABAR FLANK (SE NIGERIA): AGE AND DEPOSITIONAL ENVIRONMENT." Journal of Sedimentary Environments 4, no. 4 (October 25, 2019): 369–78. http://dx.doi.org/10.12957/jse.2019.46129.
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Foraminiferal analysis of the sedimentary deposits of Nkporo shale exposed at PAMOL along Calabar/Odukpani Road, in the Calabar Flank, Southeastern Nigeria, was investigated in order to determine its geological age and paleoenvironmental conditions. The lithology is predominantly composed by shale with traces of siltstone and sandstone. Shale is generally light to dark grey, occasionally light brown, sub-fissile to fissile, moderately hard, carbonaceous, and slightly ferruginous. Results of foraminiferal analysis showed that the samples consist predominantly of arenaceous/agglutinated benthic foraminifera. Calcareous planktic foraminifera are absence and calcareous benthic taxa are almost absence of calcareous. The occurrence of the following foraminifera taxa Ammobaculite sp., Haplophragmoides sahariense, Haplophragmoides talokaense, Trochammina sp., Trochammina dustuna, Ammobaculites amabensis and Bolivina sp. suggest that sediments in the study area were deposited during the Maastrichtian age. The paleo-depositional-environment should occur in transitional marine settings, probably a marsh/lagoon. In the study area, calm hydrodynamic conditions prevailed. They favored the accumulation of fine-grained sediment and organic matter which gave rise to oxygen scarcity. The environment would be stressful for benthic foraminifera not only because of oxygen scarcity but also due to the variability of water salinity (hypo to hypersaline). ESTUDO DE FORAMINÍFEROS DOS FOLHELHOS DE NKORHO, CALABAR FLANK (SE DA NIGERIA): IDADE E AMBIENTE DEPOSICIONAL ResumoA análise de foraminíferos dos depósitos sedimentares do folhelho Nkporo expostos em PAMOL ao longo da estrada de Calabar/Odukpani, em Calabar Flank, sudeste da Nigéria, foi estudada tendo em vista determinar sua idade relativa e condições paleoambientais. A litologia é predominantemente composta por folhelho com camadas de siltito e arenito. O folhelho é, em geral, cinza claro a escuro, ocasionalmente marrom claro, sub-físsil a físsil, moderadamente consolidado, carbonáceo e levemente ferruginoso. Os resultados da análise dos foraminíferos mostraram que as amostras estudadas contêm predominantemente foraminíferos bentónicos arenáceos/aglutinantes. Não foram encontrados foraminíferos planctónicos, estando também quase ausentes táxons bentónicos com carapaça constituída por carbonato de cálcio. A ocorrência dos seguintes taxa Ammobaculites sp., Haplophragmoides sahariense, Haplophragmoides talokaense, Trochammina sp., Trochammina dustuna, Ammobaculites amabensis e Bolivina sp. sugerem que os sedimentos na área de estudo foram depositados durante o Maastrichtiano (Cretaceo superior). A sedimentação deverá ter ocorrido em ambiente marinho de transição, provavelmente em pântanos/lagoas. Na área de estudo, prevaleceram condições hidrodinâmicas calmas que favoreceram o acúmulo de sedimentos finos e matéria orgânica, que originou a escassez de oxigênio. O ambiente seria estressante para os foraminíferos bentónicos, não só devido à escassez de oxigênio, mas também devido à variabilidade da salinidade da água (hipo a hipersalina). Palavras-chave: Bioestratigrafia. Foraminíferos Bentônicos. Aglutinantes. Maastrichtiano. Cretáceo. Ambiente marinho de transição.
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Varentsov, I. M., and V. N. Kuleshov. "Rare elements — setting markers of the formation of the manganese and iron ore deposits of Kalahari and Postmasburg areas (South Africa). Communication 1. Kalahari manganese field." Литология и полезные ископаемые, no. 4 (July 9, 2019): 364–86. http://dx.doi.org/10.31857/s0024-497x20194364-386.
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In manganese ores of the Hotazel Formation (Transvaal supergroup) of the Lower Proterozoic, associated with banded ferrous silicites, high concentrations of a number of rare elements (B, Ge, W, Mo, Cr, Ni, Zn, Cd, Pb, Ag, Bi, As, Sb, Te, Se) were determined. High boron contents in oxide-carbonate ores (manganese lutites) are considered as a consequence of the concentration by chemsorbtion of this element on Mn-carbonates. It is proposed that as a result of hydrothermal transformations, a wide range of ore-forming (mainly Fe, Mn) and rare elements (including REE) was removed from the underlying andesite-basaltic hyaloclastite Ongeluk Formation In manganese ores and ferruginous silicites, typical values of cerium (Ce/Ce* 0.28–1.72) and europium (Eu/Eu* 0.57–16.31) anomalies were established, which may indicate that the initial sediments accumulated in the marginal shallow sea basin with a pronounced oxide surface water layer and close to anoxide conditions near the bottom. Metalliferous (Mn, Fe) sediments of a shallow water basin at different stages of lithogenesis were enriched with europium (positive Eu/Eu*), subjected to metasomatosis (with redistribution of manganese and the formation of manganese carbonates) and, subsequently, regional metamorphism (up to the stage of sericitic green schists).
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Jones, C., S. A. Crowe, A. Sturm, K. L. Leslie, L. C. W. MacLean, S. Katsev, C. Henny, D. A. Fowle, and D. E. Canfield. "Biogeochemistry of manganese in Lake Matano, Indonesia." Biogeosciences Discussions 8, no. 2 (April 26, 2011): 4063–106. http://dx.doi.org/10.5194/bgd-8-4063-2011.
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Abstract. This study explores Mn biogeochemistry in a stratified, ferruginous lake. Intense Mn cycling occurs in the chemocline where Mn is recycled at least 15 times before sedimentation. The kinetics of Mn oxidation in Lake Matano are similar to other studied environments, implying that Mn oxidation is relatively insensitive to environmental parameters and may be controlled by similar mechanisms in diverse settings. The product of biologically catalyzed Mn oxidation in Lake Matano is birnessite. Although there is evidence for abiotic Mn reduction with Fe(II), Mn reduction likely occurs through a variety of pathways. The flux of Fe(II) is insufficient to balance the reduction of Mn at 125 m depth in the water column, and Mn reduction could be a significant contributor to CH4 oxidation. By combining results from synchrotron-based X-ray fluorescence and X-ray spectroscopy, extractions of sinking particles, and reaction transport modeling, we find the kinetics of Mn reduction in the lake's reducing waters are sufficiently rapid to preclude the deposition of Mn oxides from the water column to the sediments underlying anoxic water. Rather, Mn is likely sequestered in these sediments as pseudo kutnahorite. This has strong implications for the interpretation of the sedimentary Mn record.
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Liu, Jiarui, Gareth Izon, Jiasheng Wang, Gilad Antler, Zhou Wang, Jie Zhao, and Matthias Egger. "Vivianite formation in methane-rich deep-sea sediments from the South China Sea." Biogeosciences 15, no. 20 (October 26, 2018): 6329–48. http://dx.doi.org/10.5194/bg-15-6329-2018.
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Abstract. Phosphorus is often invoked as the ultimate limiting nutrient, modulating primary productivity on geological timescales. Consequently, along with nitrogen, phosphorus bioavailability exerts a fundamental control on organic carbon production, linking all the biogeochemical cycles across the Earth system. Unlike nitrogen that can be microbially fixed from an essentially infinite atmospheric reservoir, phosphorus availability is dictated by the interplay between its sources and sinks. While authigenic apatite formation has received considerable attention as the dominant sedimentary phosphorus sink, the quantitative importance of reduced iron-phosphate minerals, such as vivianite, has only recently been acknowledged, and their importance remains underexplored. Combining microscopic and spectroscopic analyses of handpicked mineral aggregates with sediment geochemical profiles, we characterize the distribution and mineralogy of iron-phosphate minerals present in methane-rich sediments recovered from the northern South China Sea. Here, we demonstrate that vivianite authigenesis is pervasive in the iron-oxide-rich sediments below the sulfate–methane transition zone (SMTZ). We hypothesize that the downward migration of the SMTZ concentrated vivianite formation below the current SMTZ. Our observations support recent findings from non-steady-state post-glacial sedimentary successions, suggesting that iron reduction below the SMTZ, probably driven by iron-mediated anaerobic oxidation of methane (Fe-AOM), is coupled to phosphorus cycling on a much greater spatial scale than previously assumed. Calculations reveal that vivianite acts as an important burial phase for both iron and phosphorus below the SMTZ, sequestering approximately half of the total reactive iron pool. By extension, sedimentary vivianite formation could serve as a mineralogical marker of Fe-AOM, signalling low-sulfate availability against methanogenic and ferruginous backdrop. Given that similar conditions were likely present throughout vast swathes of Earth's history, it is possible that Fe-AOM and vivianite authigenesis may have modulated methane and phosphorus availability on the early Earth, as well as during later periods of expanded marine oxygen deficiency. A better understanding of vivianite authigenesis, therefore, is fundamental to test long-standing hypotheses linking climate, atmospheric chemistry and the evolution of the biosphere.
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Dill, Harald G. "An Overview of Younger Kathmandu Lake, Nepal, during the Late Quaternary, with Special Reference to Ferruginous Structures in Carbonaceous Sediments." International Geology Review 48, no. 5 (May 2006): 383–409. http://dx.doi.org/10.2747/0020-6814.48.5.383.
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Simonov, V. A., A. A. Terleev, A. V. Kotlyarov, D. A. Tokarev, and A. V. Kanygin. "Physico-chemical conditions of existence of early Cambrian chemotrophic microbiota in zone of influence of ore-forming hydrothermal solutions." Доклады Академии наук 486, no. 3 (May 30, 2019): 331–35. http://dx.doi.org/10.31857/s0869-56524863331-335.
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Complex researches of the pyrite Early Cambrian Kyzyl-Tashtyg deposit (East Tuva) have allowed to reconstruct paleohydrothermal systems, to find out physical and chemical conditions of hydrothermal processes, and also to establish features of existence of ancient hydrothermal biota in the operating zone of the solutions, participating at all stages of formation of ore-bearing structures, since influence of postmagmatic fluids and finishing low temperature hydrotherms. The representative data on biota has been received at studying of the objects, which were in a zone of influence of rather low temperature hydrothermal systems. In one cases findings of microorganisms are dated for basalt complexes, containing ore body, and in other cases the found fauna is connected with ferruginous-siliceous sediments. It has been found out that microorganisms in the tonsil cavities of basalts evolved at the temperatures nearby 110-140°С under the influence of hydrothermal solutions. Much lower temperatures (to 100 °С) existed at development of micro-fossils in the quartz-hematite hydrothermal constructions of Kyzyl-Tashtyg deposit.
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Hicks, N., D. J. C. Gold, M. Ncume, and L. Hoyer. "A new lithostratigraphic framework for portions of the Pongola Supergroup within the Nkandla sub-basin, southern Kaapvaal Craton, South Africa; insights into Mozaan Group stratigraphy." South African Journal of Geology 124, no. 3 (September 1, 2021): 717–34. http://dx.doi.org/10.25131/sajg.124.0039.
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Abstract A revised lithostratigraphic framework for Mozaan Group-equivalent strata within the Nkandla sub-basin is presented based on new field data, remote sensing and genetic sequence stratigraphic interpretations. Although previous literature has suggested that no Mozaan Group lithologies were deposited within the sub-basin, reinterpretations presented here indicate that 90% of the lithostratigraphy developed within the main basin occurs within the Nkandla and Mhlatuze inliers. Mozaan Group units previously defined as the Vutshini and Ekombe formations are correlated with stratigraphy from the lowermost Sinqeni Formation to the Gabela Formation. Although thinner than units within the type area in the main basin, thicknesses of the Sinqeni Formation are comparable to those observed within the White Mfolozi Inlier. A ~1 000 m composite reference profile is measured within the Mdlelanga Syncline of the Nkandla Inlier. Further profiles were measured for sequences in the Gem-Vuleka Syncline of the Nkandla Inlier, as well as within the Mhlatuze Inlier. These latter profiles, however, host only lower Mozaan Group strata. In all sections the basal portion of the sequence comprises two quartz arenite units, separated by a ferruginous shale, which hosts minor iron formation interbeds. This predominantly coarse-grained lower sequence is overlain by a shale-dominated succession with multiple sandstone interbeds. A prominent coarse-grained quartz arenite unit forms a distinct marker in the middle portion of the sequence. This is overlain by a sequence of shales and sandstones with two prominent igneous units present. Genetic sequence stratigraphic interpretations indicate cyclical deposition of dominantly shallow marine sediments with condensed sections, marked by iron formations or ferruginous shales, denoting periods of marine highstand along the southeastern margin of the Kaapvaal Craton. The evidence of Mozaan Group stratigraphy within the Nkandla sub-basin supports a passive margin tectonic model whereby deposition occurred in an arcuate shallow continental margin which opened to the southeast. The extension of Mozaan Group strata into the Nkandla sub-basin suggests that the Mozaan Basin likely formed a single depository rather than separate sub-basins as previously proposed.
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Pelede, Souleymane, Aboubakar Sako, and Ousmane Bamba. "Ecological Risk Assessment of Heavy Metals in Sediments from the Soubeira Reservoir, a Small-Scale Reservoir in North Central Burkina Faso, West Africa." Environment and Pollution 7, no. 1 (March 30, 2018): 66. http://dx.doi.org/10.5539/ep.v7n1p66.
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Small-scale reservoirs play a central role in socio-economic development of Burkina Faso. In the absence of a best environmental management plan, these reservoirs can be potential factors of water pollution and ecological deterioration. In the present study, we investigated ecological status of sediments from the Soubeira reservoir, using concentrations of a series of heavy metals. Concentrations of the metals ranked as follows: Fe> Mn> Cr> Zn> Cu> Pb> As ~ Co> Hg ~Mo> Cd. Based on the correlation analysis, Fe, with weaker relationships with other metals, may be derived from the local ferruginous soil, whereas Cd, Cu and Cr could be mainly originated from anthropogenic sources and carried by clay minerals into the reservoir. In contrast, Hg and As abundance could be related to artisanal gold mining in the surrounding environment. Negative correlations between heavy metals (except As) with pH were consistent with desorption and mobility of the majority of heavy metals under low pH values. The significant negative correlations were also observed between CEC and As (r = - 0.75) and between clay and As (r = -0.64). This could be an indication of As mobility under the physico-chemical conditions of the reservoir. Both potential ecological risk and adverse effect indices suggested that the reservoir sediments were highly polluted. Five heavy metals (As, Cd, Cu, Cr and Hg) could cause adverse effect to biota, whilst only Hg and Cd appeared to show high and moderate potential ecological risk indices, respectively. The study demonstrated that the Soubeira reservoir requires a heavy metal pollution control program.
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Lipka, Marko, Michael E. Böttcher, Zijun Wu, Jürgen Sültenfuß, Anna-K. Jenner, Julia Westphal, Olaf Dellwig, et al. "Ferruginous groundwaters as a source of P, Fe, and DIC for coastal waters of the southern Baltic Sea: (Isotope) hydrobiogeochemistry and the role of an iron curtain." E3S Web of Conferences 54 (2018): 00019. http://dx.doi.org/10.1051/e3sconf/20185400019.
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We report first results from a study on water and element exchange across the land-ocean boundary at the southern Baltic Sea. The focus is set on ferruginous fresh ground waters escaping at the shore line, flowing in air contact before entering a subterranean mixing zone with brackish Baltic Sea water. The present study combines the results from multiple sampling campaigns that investigated the composition of several springs as well as the surface and subsurface development of fresh waters on the way to the Baltic Sea. This is achieved by a combination of hydroand solid-phase geochemical and stable isotope measurements with ground water dating. Results are compared to the composition of groundwaters recovered from wells in the catchment area and the local isotope meteoric water line developed for Warnemünde. The spring water is shown to be impacted by the dissolution of biogenic carbon dioxide and marine carbonate as well as the oxidation of pyrite in glacial sediments. Dating yields a surprisingly high diversity between some closely associated springs with average ages of about 25 to 32 years, but different mixing proportions with older tritium-free ground-water.
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Mahboubi, Abdessamed, Jean-Jacques Cornée, Raimund Feist, Pierre Camps, and Catherine Girard. "Frasnian (Upper Devonian) integrated facies analysis, magnetic susceptibility and sea-level fluctuations in the NW Algerian Sahara." Geological Magazine 156, no. 08 (October 18, 2018): 1295–310. http://dx.doi.org/10.1017/s0016756818000626.
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AbstractChanges in the palaeoenvironment are investigated in two representative Frasnian sections of the NW Algerian Sahara, integrating sedimentology and magnetic susceptibility (MS). The Ben Zireg section is characterized by condensed and ferruginous calcareous deposits; in the South Marhouma section the sedimentation rate is high, dominated by muddy nodular limestones with several hypoxic shale intervals. In both sections, sediments were mostly emplaced on pelagic outer ramps below the limit of storm wave-base, evolving through time from proximal to distal setting. Investigations of the temporal evolution of facies and MS data permit a first estimate of the local sea-level trends in NW Algeria. These trends match the overall long-term rise of sea level recognized worldwide from Frasnian Zone 5 upwards. Noteable positive excursions of the sea-level curve related to the semichatovae transgression, as well as to the late Frasnian transgression prior to the late Kellwasser event, can be established in this area. Although the sharp regression of sea level at the upper Kellwasser level can be confirmed from our data, no particular trend is depicted at the transition of conodont zones (Frasnian Zones 12–13) where the presence of the lower Kellwasser level has not yet been clearly recognized.
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Wilton, Derek H. C., Gary M. Thompson, and Dawn Evans-Lamswood. "MLA-SEM Characterization of Sulphide Weathering, Erosion, and Transport at the Voisey’s Bay Orthomagmatic Ni-Cu-Co Sulphide Mineralization, Labrador, Canada." Minerals 11, no. 11 (November 4, 2021): 1224. http://dx.doi.org/10.3390/min11111224.
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The Voisey’s Bay nickel-copper-cobalt (Ni-Cu-Co) sulphide deposits constitute a significant resource of orthomagmatic mineralization. The deposits are not exposed at the surface except for in a small ferruginous gossan (Discovery Hill). The subsequent geophysical surveys and diamond drilling led to the discovery of the Ovoid ore body, buried beneath 20 m of till, and other deeper deposits in the bedrock. This study was initiated to characterize the sulphide mineralogy of these deposits through various stages of weathering, erosion, and transport. Because the samples ranged from bedrock through to a variety of surficial sediment types, the automated SEM-based identification provided by the MLA-SEM system was the ideal technique to quantitatively evaluate mineral distributions in the different media. The derived MLA-SEM data indicate that, aside from the Discovery Hill gossan, the surface sulphide mineralization at Voisey’s Bay was weathered in a pre-glaciation regolith at the Mini-Ovoid deposit and, on the surface of the Ovoid deposit, the massive sulphide was unoxidized due to a thin calcite-cemented clay cover. Pentlandite is very preferentially oxidized compared to other sulphides in the Voisey’s Bay ore, to depths of up to 10 m in bedrock. Conversely, within the coarse reject samples of crushed drill cores stored in sealed plastic bags, pyrrhotite was altered, whereas pentlandite and chalcopyrite are stable, presumably due to anaerobic reactions. The MLA-SEM detected trace amounts of minute sulphide grains in surficial sediments, but their contents abruptly decreased with distance from the sulphide mineralization. Microtextures such as troilite and pentlandite exsolution or twinning in pyrrhotite, however, could be observed in the fine sulphide grains from till, suggesting a derivation from orthomagmatic sulphide material, such as the Voisey’s Bay mineralization.
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Al-Wosabi, Mohammed A., and Sa’ad Z. Al-Mashaikie. "Investigation of Facies Types and Associations of Kuhlan Red Bed Formation in NW Yemen: A New Hypothesis for Origin and Depositional Environment." Sultan Qaboos University Journal for Science [SQUJS] 11 (June 1, 2006): 11. http://dx.doi.org/10.24200/squjs.vol11iss0pp11-38.
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Varieties of thirteen facies types were recognized in the Kuhlan Formation represented by red bed siliciclastic sequences of argillaceous sediments. Examination of the Kuhlan stratigraphic column included sequence relationships, lithology, sedimentary characters, structures and petrography of the dominant rock types. These facies types are grouped in three distinct associations of facies. The lower unit A comprises association of facies (Distal turbidites) represented by alternates of turbidity sequences including sandstone, siltstone and thick shale beds. These facies types confirm a regressive depositional environment in deep marine shelf conditions. There are three facies types which are identified as massive sandstone, cross-bedded sandstone and pebbly sandstone facies. The middle unit B association of facies (Proximal turbedites) represents glaciomarine sequences displaying high lateral and vertical facies changes of glacioturbidite sediment alternates with diamictites and tillite beds. The sequences are affected by eustatic and eustatism of the glacial advance and retreat. This unit B includes eight types of facies. These are identified as; tillite, massive diamictites, stratified diamictites, laminated siltstone/shale, deformed siltstone/mudstone, graded rhythmic siltstone, massive conglomerate and cross-stratified sandy conglomerate facies. The upper unit C association of facies is represented by shallow marine shelf sequences displaying very thick massive and locally cross-bedded sand bar sandstone overlying the laminated siltstone/shale interbeds. The upward gradual changes in mineralogical composition and color confirms the start of marine transgression and later deposited platform Amran Group. Mineralogical composition of Kuhlan sandstone displays impure dirty rocks consisting of more than 30% of argillaceous matrix, 50% of cristobalite and quartz grains, more than 10% of ferruginous cement and 10% of detrital iron oxide grains, potash feldspar, igneous rock fragments and carbonate cement. It is classified as quartz greywacke type in the lower and middle parts and as quartz arenite with subarkoses in the upper part.
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Maloney, D., C. Sargent, N. G. Direen, R. W. Hobbs, and D. R. Gröcke. "Re-evaluation of the Mentelle Basin, a polyphase rifted margin basin, offshore south-west Australia: new insights from integrated regional seismic datasets." Solid Earth Discussions 3, no. 1 (February 3, 2011): 65–103. http://dx.doi.org/10.5194/sed-3-65-2011.
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Abstract. Vintage 2-D (two dimensional) seismic reflection surveys from the sparsely explored Mentelle Basin (western Australian margin) have been re-processed and integrated with recent high quality seismic survey, and stratigraphic borehole data. Interpretation of these data sets allows the internal geometry of the Mentelle Basin fill and depositional history to be reanalysed with a greater degree of confidence. Basin stratigraphy can be subdivided into several seismically defined megasequences, separated by major unconformities related to both the Valanginian breakup between India-Madagascar and Australia-Antarctica, and tectonically-driven switches in deposition through the Albian. Resting on the Valanginian unconformity are several kilometre-scale mounded structures that formed during late Jurassic to early Cretaceous extension. These have previously been interpreted as volcanic edifices, although direct evidence of volcanic feeder systems is lacking. An alternative interpretation is that these features may be carbonate build-ups. The latter interpretation carries significant climatic ramifications, since carbonate build-ups would have formed at high palaeolatitude, ~60° S. Soon after breakup, initial subsidence resulted in a shallow marine environment and Barremian-Aptian silty-sandy mudstones were deposited. As subsidence continued, thick Albian ferruginous black clays were deposited. Internally, black clay megasequences show previously unresolved unconformities, onlapping and downlapping packages, which reflect a complex depositional, rifting and subsidence history, at odds with their previous interpretation as open marine sediments. Southwestwards migration of the Kerguelen hotspot led to thermal contraction and subsidence to the present day water depth (~3000 m). This was accompanied by Turonian-Santonian deposition of massive chalk beds, which are unconformably overlain by pelagic Palaeocene-Holocene sediments. This substantial unconformity is related to the diachronous breakup and onset of slow spreading between Australia and Antarctica, which may have led to the reactivation and inversion of basement faults, followed by rapid seafloor spreading from the middle Eocene to the present.
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Fadigas, Francisco Souza, Nelson Moura Brasil do Amaral Sobrinho, Lucia Helena Cunha dos Anjos, and Nelson Mazur. "Background levels of some trace elements in weathered soils from the Brazilian Northern region." Scientia Agricola 67, no. 1 (February 2010): 53–59. http://dx.doi.org/10.1590/s0103-90162010000100008.
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Soils formed from the Barreiras Group sediments, located mainly along the coast of Brazil Northern and Northeastern regions, generally present low concentrations of iron oxides and total organic carbon, high quantities of quartz in the sand fraction, and kaolinitic clay mineralogy. The objective of the present study was to quantify the pseudo total concentrations of Cd, Co, Cu, Cr, Mn, Ni, Zn and Fe in Xhantic Udox and Xhantic Udult soils derived from these sediments. The reference sites were covered by native vegetation and located in the States of Pará and Amapá, Brazil. Multiple linear regression analysis was applied to determine correlations between soil parameters and the levels of these metals. The best correlation was obtained between Fe, Mn, clay, and silt contents, and Cd, Co, Cu, Zn, Cr, Ni. A correlation between pH and these metal levels was not found. Clay and sand contents showed a negative inverse correlation with the metal levels,of same magnitude but with a different sign; this was the reason for excluding one of the parameters in the regression model. In general, the contents of the elements were lower than those found in soils formed from other parent materials. The Mn content was included in the model of multiple linear regression for Cd and Co, due to its association with these last metals. Silt level showed to have a significant influence in the equations for Cr and Co, which is attributed to the presence of clay minerals and Fe and Mn oxides in ferruginous and clay aggregates of silt size. The equations obtained in this paper, are useful to predict, in general terms, the amounts of those heavy metals in an unknown soil sample, if the soil material were not contaminated or affected by land usage. Thus, they may be applied to evaluate soil contamination by the studied heavy metals.
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van Loef, J. J. "Composition and genesis of rattlestones from Dutch soils as shown by Mössbauer spectroscopy, INAA and XRD." Netherlands Journal of Geosciences - Geologie en Mijnbouw 79, no. 1 (March 2000): 59–71. http://dx.doi.org/10.1017/s0016774600021570.
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AbstractThe chemical and mineralogical composition of rattlestones found near the main Dutch rivers has been studied by Mössbauer spectroscopy, INAA and XRD. Rattlestones are concretions of iron, formed in an environment of lateral iron accumulation, under the influence of periodical oxidation, around a fine core of ferruginous sediments, mainly clay and sand. The core has shrunk and detached itself from the mantle around it. 57Fe Mössbauer spectroscopy was applied to identify the iron oxides, among which goethite is predominant. The goethite crystallinity was investigated by measuring its magnetic properties and its crystallinity, which is poorest at the outer side of the stone. The latter is confirmed by the broadening of the different X-ray reflections. In addition, illite and vermiculite were identified by XRD; these clay minerals were found mainly in the core.The elemental composition was determined by INAA. The iron content in the mantle is about 50% by weight and gradually decreases outwards, while the core contains 2–15% Fe by weight. Differences between rattlestones from the Middle Pleistocene East of the Meuse river and those from the Late Pleistocene North of it are the absence of lepidocrocite and a richer mineralogy in the former.It is concluded that the rattlestones are formed around a fine clayey core. Groundwater supplied the iron and other (trace) elements for the genesis. It is unlikely that rattlestones are the result of oxidation of siderite.
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Maloney, D., C. Sargent, N. G. Direen, R. W. Hobbs, and D. R. Gröcke. "Re-evaluation of the Mentelle Basin, a polyphase rifted margin basin, offshore southwest Australia: new insights from integrated regional seismic datasets." Solid Earth 2, no. 2 (July 7, 2011): 107–23. http://dx.doi.org/10.5194/se-2-107-2011.
Full textAbstract:
Abstract. Vintage 2-D (two-dimensional) seismic reflection surveys from the sparsely explored Mentelle Basin (western Australian margin) have been reprocessed and integrated with a recent high-quality 2-D seismic survey and stratigraphic borehole data. Interpretation of these data sets allows the internal geometry of the Mentelle Basin fill and depositional history to be reanalysed and new insights into its formation revealed. Basin stratigraphy can be subdivided into several seismically defined megasequences separated by major unconformities related to both breakup between India-Madagascar and Australia-Antarctica in the Valanginian-Late Hauterivian and tectonically-driven switches in deposition through the Albian. Resting on the Valanginian-Late Hauterivian breakup unconformity are several kilometre-scale mounded structures that formed during Late Jurassic to Early Cretaceous extension. These have previously been interpreted as volcanic edifices although direct evidence of volcanic feeder systems is lacking. An alternative interpretation is that these features may be carbonate build-ups. The latter interpretation carries significant climatic ramifications since carbonate build-ups would have formed at high palaeolatitude, ~60° S. Soon after breakup, initial subsidence resulted in a shallow marine environment and deposition of Barremian-Aptian silty-sandy mudstones. As subsidence continued, thick successions of Albian ferruginous black clays were deposited. Internally, seismic megasequences composed of successions of black clays show previously unresolved unconformities, onlapping and downlapping packages, which reflect a complex depositional, rifting and subsidence history at odds with their previous interpretation as open marine sediments. Southwestwards migration of the Kerguelen hotspot led to thermal contraction and subsidence to the present day water depth (~3000 m). This was accompanied by Turonian-Santonian deposition of massive chalk beds, which are unconformably overlain by pelagic Palaeocene-Holocene sediments. This substantial unconformity is related to the diachronous breakup and onset of slow spreading between Australia and Antarctica, which may have led to the reactivation and inversion of basement faults and was followed by rapid seafloor spreading from the Middle Eocene to the present.
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Sorokhtin, N. O., and N. E. Kozlov. "Geodynamic Evolution of the Western Part of the Russian Arctic and Its Diamond Potential." Oceanology 61, no. 6 (November 2021): 1040–54. http://dx.doi.org/10.1134/s0001437021060138.
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Abstract The study of the geodynamic evolution of the Baltic Shield showed that the melts of diamondiferous kimberlites and related rocks were formed due to the pulling of “heavy” ferruginous sediments of the Early Proterozoic into subduction zones beneath the Archean cratons. Later, during the Neoproterozoic and Paleozoic stages of rifting, melts conserved in the lower crust and subcrustal lithosphere were able to penetrate into the near-surface zones of the crust and form magmatic complexes of alkaline–ultramafic and kimberlite magmatism. The authors showed that diamondiferous kimberlite and lamproite explosion pipes, as well as related carbonatite and alkaline–ultramafic intrusions, are mainly located above the subduction zones of the Svecofennian (Karelian) plates, which functioned about 2.0–1.8 Ga ago. At the same time, alkaline ultramafic intrusions and (sodium) carbonatites are located closest to the front of the subduction zone of Proterozoic plates (from 100 to 200–300 km). Then (at a distance of 200 to 400 km), there is a zone of location of calcite carbonatites and melilitites, and sometimes nondiamondiferous kimberlites. Diamondiferous kimberlite and lamproite diatremes are located farther than other similar formations approximately 300 to 600–650 km from its front. Such a regular spatial arrangement of magmatic complexes of a single series unambiguously indicates a change in depth of their origin. The farther from the surface boundary of the paleosubduction zone the magmatic bodies are located, the deeper the facies representing them.
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GIRARD, CATHERINE, JEAN-JACQUES CORNÉE, CARLO CORRADINI, AURÉLIEN FRAVALO, and RAIMUND FEIST. "Palaeoenvironmental changes at Col des Tribes (Montagne Noire, France), a reference section for the Famennian of north Gondwana-related areas." Geological Magazine 151, no. 5 (November 25, 2013): 864–84. http://dx.doi.org/10.1017/s0016756813000927.
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AbstractWe present detailed biostratigraphy based on conodonts and palaeoenvironmental trends deduced from microfacies and conodont abundance through the Famennian (Late Devonian) at Col des Tribes (Montagne Noire, France). The succession is characterized by micritic limestones deposited in settings oscillating between mid to outer ramp. Facies contain poor fauna, widely dominated by nektonic organisms. This section is complete and one of the most conodont-rich for the Famennian of the north Gondwana-related area. The Upper Kellwasser event (Frasnian–Famennian boundary) and the Hangenberg (Devonian–Carboniferous boundary) have been lithologically identified. They are characterized by decimetre-thick black dysoxic to anoxic argillaceous sediments. The Condroz and annulata events, although not materialized by lithological changes, have been positioned due to the precise stratigraphy. The first event occurred during the deposition of condensed ferruginous facies (griotte limestones) and the second event during the deposition of micrites barren of benthic fauna. The combination of information from both facies and conodont biofacies changes allows a general sea-level curve through the entire Famennian for north Gondwana to be proposed for the first time. At Col des Tribes, the general trend is a slight deepening upwards from triangularis to trachytera zones, then a pronounced shallowing-upwards trend from upper trachytera to praesulcata zones. This curve correlates with the well-known reference curve from Euramerica concerning the late Famennian (trachytera to praesulcata Zones). There are some discrepancies in minor cycles which can be explained by tectonical phenomena at the onset of the edification of the Variscan belt in Europe.
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Zubkov, Mikhail Yu. "Modeling the hydrothermal impact on the Jurassic deposits of the West Siberian sedimentary basin (series with H2O and H2O2)." Georesursy 22, no. 4 (December 2020): 30–40. http://dx.doi.org/10.18599/grs.2020.4.30-40.
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The results of hydrothermal modeling of the formation of epigenetic mineral associations and secondary reservoirs in various types of sedimentary rocks of the Jurassic age in Western Siberia in the H2O-H2O2 system are considered. The experiments were carried out at a temperature of 390°C, a pressure of 70 MPa and H2O2 concentrations varying from 0 to 37.5%. The duration of the experiments was 10 days. In all experiments, a pyrite mixture was added as a buffer. It was found that in experiments in which there was no H2O2, that is, the hydrothermal fluid consisted only of water, there was an intense formation of bitumen and volatile components from the organic matter present in the initial samples. The process of generation of bitumen and volatile components was accompanied by fluid fracturing of rocks and the formation of secondary porosity. Under these conditions, carbonates (calcite, siderite), plagioclases, and kaolinite turned out to be unstable. On the contrary, the formation of hydrothermal ferruginous chlorite was noted. Dissolution of unstable mineral phases by hydrothermal fluid led to the formation of additional secondary porosity. As the concentration of H2O2 and, accordingly, oxygen in the composition of the hydrothermal fluid increased, more and more complete oxidation of the organic matter present in the composition of the sediments was noted until its complete disappearance. With an increase in the oxygen concentration in the composition of the hydrothermal fluid, the appearance of first magnetite and then hematite, native sulfur, and anhydrite was observed. Under hydrothermal conditions with a maximum oxygen concentration, the formation of kaolinite and various sulfates in addition to anhydrite, represented by millosevichite, alum, as well as phases with the participation of elements that make up autoclaves, nickel and chromium sulfates, was noted. Intensive silicification of the sample surface is noted, as well as the constant presence of amorphous silica, which, along with various sulfates, is a quenching phase. These mineral phases are separated from the supersaturated hydrothermal fluid due to its rapid cooling and do not have time to form well-faceted crystals, but are present in the form of loose microporous aggregates. Along with kaolinite, the formation of hydrothermal film illite is noted. The results obtained indicate that the presence of bitumen in the Jurassic sediments is an important exploratory feature, indicating that in this place they were subjected to hydrothermal action, which means, firstly, secondary reservoirs with high filtration and capacity properties were formed, and second, there was an intensive generation of hydrocarbons and, as a consequence, the formation of hydrocarbon deposits.
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Jeans, C. V. "Clay mineralogy of the Cretaceous strata of the British Isles." Clay Minerals 41, no. 1 (March 2006): 47–150. http://dx.doi.org/10.1180/0009855064110196.
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AbstractThe clay mineralogy of the Cretaceous strata of the British Isles is described and discussed within its lithostratigraphical and biostratigraphical framework using published and unpublished sources as well as 1400 new clay mineral analyses. The regional clay mineral variation is described systematically for the following strata:(1)Southern England — Purbeck Limestone Group (Berriasian/Ryazanian; Lulworth and Durlston formations), Wealden Group (Valanginian—Barremian/Aptian; Ashdown, Wadhurst Clay, Tunbridge Wells Sands, Grinstead Clay Member, Wealden Clay, Wessex and Vectis formations), Lower Greensand (Aptian—Lower Albian; Atherfield Clay, Hythe, Sandgate, Folkestone Sands, Ferruginous Sands, Woburn Sands and Faringdon Sponge Gravels formations), Selborne Group (Middle—Upper Albian; Gault Clay and Upper Greensand formations) and the Chalk Group (Cenomanian—Lower Maastrichtian).(2)Eastern England — Cromer Knoll Group (Ryazanian—Upper Albian; Speeton Clay, Spilsby Sandstone, Sandringham Sands, Claxby Ironstone, Tealby, Roach Ironstone, Dersingham, Carstone and Red Chalk (or Hunstanton Red Limestone) formations).(3)Scotland — Inner Hebrides Group (Cenomanian—Campanian; Morvern Greensand, Gribun Chalk, Coire Riabhach Phosphatic Hibernian Greensands formations).(4)Northern Ireland — Hibernian Greensands (Cenomanian—Santonian) and Ulster White Limestone formations (Santonian—Lower Maastrichtian).The stratigraphical patterns of clay mineral variation divide naturally into two types; firstly, the more complex pattern of the Lower Cretaceous strata and secondly, the simple pattern of the Upper Cretaceous. Clay mineral variations in the non-marine and marine Lower Cretaceous strata of England are best explained by the interplay of two main clay mineral assemblages between which all gradations occur. The assemblage which dominates the main clay formations consists of mica, kaolin and poorly defined mixed-layer smectite-mica-vermiculite minerals, and sometimes includes vermiculite and traces of chlorite. It is dominantly of detrital origin and detailed evidence indicates it is derived largely from the reworking of Mesozoic sediments although ultimately from weathered Palaeozoic sediments and metasediments. Although mainly of detrital origin, this assemblage contains a persistent component that formed coevally with the approximate depositional age of its host sediment. Whether this component is of soil origin or was neoformed in the sediment shortly after deposition is unclear. There is little firm evidence indicating the sources of this clay mineral detritus. However, in the strata of the Wealden Group of southern England, mineral trends suggest three sources; one of these was to the west (Cornubian Massif), another must have been the Anglo- Brabant landmass. In the Selborne Group (Middle—Upper Albian) and in the overlying Lower Chalk (Cenomanian) where this assemblage makes its last appearance in the Cretaceous of England, there is good evidence of easterly and south-easterly sources.The second main assemblage tends to be largely monominerallic, and usually dominated by smectite with or without small amounts of mica; less frequently, kaolin, berthierine or glauconite sensu lato is the sole or dominant component. It is considered to be of volcanogenic origin, derived from the argillization of volcanic ash under different conditions of deposition and diagenesis. The source of the ash in Berriasian—Aptian times seems to have been an extensive volcanic field in the southern part of the North Sea and in the Netherlands, whereas in the Albian (and extending into the Cenomanian) a westerly source dominated. The current controversy about the role of climate or pattern of volcanic activity controlling the clay mineral stratigraphy of the Lower Cretaceous is reviewed.In the lower part of the Upper Cretaceous strata of England, Scotland and Ireland, sand-grade glauconite is particularly abundant. Much of it represents the glauconitization of pene- contemporanous volcanic ash, possibly of basaltic origin, associated with continental breakup and the opening up of the Atlantic Ocean and the earliest stages in the development of the Hebridean Tertiary Igneous Province. The Upper Cretaceous Chalk facies of England and Ireland is dominated by a smectite-rich clay assemblage containing mica, and the various hypotheses for its origin (detrital, neoformation, volcanogenic) are reviewed in the light of available mineralogical, chemical and geological data.
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Handley, Kim M., Christopher Boothman, Rachel A. Mills, Richard D. Pancost, and Jonathan R. Lloyd. "Functional diversity of bacteria in a ferruginous hydrothermal sediment." ISME Journal 4, no. 9 (April 22, 2010): 1193–205. http://dx.doi.org/10.1038/ismej.2010.38.
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