Use of variations in unit cell length, reflectance and hardness for determining the origin of Fe disulphides in sedimentary rocks

Dill, Harald G.; Eberhard, E.; Hartmann, Bernhard H.

doi:10.1016/s0037-0738(96)00031-0

Cited by 12 publications

(5 citation statements)

References 45 publications

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“…The difficulty of cutting those slabs is frequently reported by quarry workers of the Talhado do Idemar. Similar situation was reported by Dill et al (1997) in German rocks. A possible hydrothermal origin for the Si observed in the "embombado" ethnostratum can be speculated according to the attributes of Berg & Masters (1994).…”

Section: Geochemical Patternssupporting

confidence: 90%

Petrological Meaning of Ethnostratigraphic Units: Laminated Limestone of the Crato Formation, Araripe Basin, NE Brazil

et al. 2022

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Crato Formation, NE Brazil, consists of laminated limestones deposited in a lacustrine environment during the Early Cretaceous. The Nova Olinda Member, the lowest unit of the Crato Formation, is world-famous for their exceptionally well-preserved fossils. The Nova Olinda limestones have been economically exploited for centuries. Today, this commercial excavation still represents the main economic activity in the region. During the mining process, the quarry workers have developed an informal stratigraphic code to individualize the different beds in the quarries. Upward, the local workers recognize the succession as “lajão dos sete cortes”, “matracão", “lajão branco", “pão de milho”, “veio da paiba”, "veio doidão”, “lajão amarelo” and “veio do besouro”. Here, we used principles of ethnostratigraphy to verify the origin and validity of these informal stratigraphic nomenclatures by classifying them as ethnostra. For this, we applied a detailed petrographical analysis with thin sections and high-resolution X-ray techniques to characterize each ethnostratum. Our results suggest possible linkages between informal and formal stratigraphic nomenclatures in Nova Olinda Member. Finally, this study showed that ethnostratigraphy can be applied as an auxiliary tool in stratigraphic studies, in both, as an initial exploratory approach and as enhancing the relationship between the geologists and the local community.

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Section: Geochemical Patternssupporting

confidence: 90%

Petrological Meaning of Ethnostratigraphic Units: Laminated Limestone of the Crato Formation, Araripe Basin, NE Brazil

et al. 2022

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“…Therefore both base metals may be used to constrain the origin and physico-chemical conditions of pyrite in sediments and ore deposits (Vaughan and Craig, 1978;Dill et al, 1997). An attempt has been made to quantify the concentrations of Ni and Co in framboidal pyrite and Fe hydroxide.…”

Section: Chemical Composition Of Ferruginous Biogenic Structures and mentioning

confidence: 99%

“…The latter is confined to the immediate surroundings of the tubular structures (Dill et al 1997(Dill et al , 2002.…”

Section: Physicochemical Conditions During Formation and Alteration Omentioning

confidence: 99%

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An Overview of Younger Kathmandu Lake, Nepal, during the Late Quaternary, with Special Reference to Ferruginous Structures in Carbonaceous Sediments

Dill

2006

International Geology Review

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The Kathmandu Basin in Central Nepal is located in the Lesser Himalayas. Older Kathmandu Lake evolved during the Pliocene and Early Pleistocene; Younger Kathmandu Lake with its widespread carbonaceous rocks and ferruginous biogenic structures silted up during the Late Quaternary. Sedimentological analyses supplemented with palynological and chemical studies of carbonaceous sediments formed the basis of the present paleogeographic and paleoclimatic studies. The basin was covered by a perennial freshwater lake before 30,000 yr. B.P. It was silted up with alluvial and fluvial sediments. Diatomaceous earths, and carbonaceous mud-and siltstones were deposited in the center of the lake and small relict ponds. Toward the basin edge, lacustrine sediments gave way to deltaic deposits spread across the delta plain. The most proximal parts of this alluvial-fluvial sedimentary wedge also have debris flows interfingering with fine-grained floodplain deposits. Three lake highstands (> 30,000 yr. B.P., 28,000-19,000 yr. B.P., 11,000-4000 yr. B.P.(?)) have been recognized in the sedimentary record of Younger Kathmandu Lake. Second-order waterlevel fluctuations were triggered by damming as a result of tectonically induced landslides. Firstorder water-level fluctuations were due to climatic changes. During the last highstand, favorable conditions occurred for vertical to subvertical tubular ferricretes to develop. The tubular structures are likely to have been created by bottom dwellers. Three different types of mineralization have evolved during diagenesis, each of which is characterized by different Fe-bearing marker minerals. The overall silting-up process in Kathmandu Basin is manifested on a microscopic scale in the textural and mineralogical variations of Fe mineralization in these biogenic sedimentary structures.

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“…Pyrite is the most common sulphide mineral on Earth and acts as a major sink for trace elements (Huerta‐Diaz & Morse, ; Morse & Luther, ; Dellwig et al ., ). While trace element composition of ancient sedimentary pyrite has been used to reconstruct palaeodepositional environments (Dill & Kemper, ; Stüben et al ., ; Cruse & Lyons, ; Abanda & Hannigan, ; Tribovillard et al ., , ), authigenic pyrite in recent sediments has attracted the attention of environmental scientists due to the significant amounts of toxic heavy metals (for example, Ni, Cu, Co and Hg) and metalloids (for example, As and Se) it may contain (Huerta‐Diaz & Morse, ; Dill et al ., ; Diehl et al ., ; Hudson‐Edwards et al ., ; Burgess et al ., ; Bajaj et al ., ; Diener & Neumann, ).…”

Section: Introductionmentioning

confidence: 98%

Arsenic in framboidal pyrite from recent sediments of a shallow water lagoon of the Baltic Sea

et al. 2013

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Arsenic is a redox‐sensitive element of environmental relevance and often enriched in iron sulphides. Because sediments from the Achterwasser lagoon, a part of the estuarine system of the river Oder, south‐west Baltic Sea, show unexpectedly high pyrite concentrations of up to 7·5 wt% they were used to investigate the influence of authigenic pyrite on the mobility and burial of As in the coastal environment. Micro‐X‐ray‐fluorescence measurements of 106 micrometre‐sized pyrite framboids from the anoxic sediments show highly variable As concentrations ranging from 6 to 1142 μg g−1. Even within a 1 cm thick layer, the As concentration of different framboids varies greatly and no clear depth trend is visible throughout the 50 cm long sediment core. Pyrite can account for 9 to 55% (average 22%) of the total As budget of the sediments and the degree of trace metalloid pyritization for As ranges from 26 to 61%, indicating that authigenic pyrite formation is an important process in the geochemical cycling of As in coastal sediments. High‐resolution micro‐X‐ray fluorescence mapping of single pyrite grains shows that As is distributed inhomogeneously within larger framboids, suggesting changing pore water composition during pyrite growth. X‐ray absorption near edge structure spectra indicate that As is usually present as As(‐I) substituting S in the pyrite lattice. However, in samples close to the sediment/water interface a considerable part of As is in higher valence states (+III/+V). This can be explained by frequent re‐suspension of the surficial sediments to the oxic water column due to wave action and subsequent re‐deposition, leading to the adsorption of As oxyanions onto pyrite. Although reduced As(‐I) becomes more important in the deeper samples, reflecting decreasing redox potential and a longer time since deposition, the occurrence of oxidized As species (AsIII/AsV) in pyrite in the anoxic part of the sediment suggests formation under dysoxic conditions.

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Use of variations in unit cell length, reflectance and hardness for determining the origin of Fe disulphides in sedimentary rocks

Cited by 12 publications

References 45 publications

Petrological Meaning of Ethnostratigraphic Units: Laminated Limestone of the Crato Formation, Araripe Basin, NE Brazil

Petrological Meaning of Ethnostratigraphic Units: Laminated Limestone of the Crato Formation, Araripe Basin, NE Brazil

An Overview of Younger Kathmandu Lake, Nepal, during the Late Quaternary, with Special Reference to Ferruginous Structures in Carbonaceous Sediments

Arsenic in framboidal pyrite from recent sediments of a shallow water lagoon of the Baltic Sea

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