Chemistry of the iron-rich sedimentary rocks

James, Harold L.

doi:10.3133/pp440w

Cited by 101 publications

(63 citation statements)

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“…The iron (oxyhydr)oxide control on phosphorus availability may have influenced phosphate availability and primary production well into the distant geological past. We will discuss the evolution of ocean chemistry in more detail in Section 9, but before about 1.9 billion years ago, banded iron formations (BIFs) were relatively common (Holland, 1984a;Isley and Abbott, 1999;James, 1966). Many of these are rich in oxide phases and probably accumulated originally from Fe (oxyhydr)oxide deposition, although subsequent diagenesis has changed this original Fe mineralogy (Beukes and Klein, 1992;Fischer and Knoll, 2009;Holland, 1984a).…”

Section: Present-daymentioning

confidence: 99%

The Iron Biogeochemical Cycle Past and Present

Raiswell¹,

Canfield²

2012

GeochemPersp

585

445

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Section: Present-daymentioning

confidence: 99%

The Iron Biogeochemical Cycle Past and Present

Raiswell¹,

Canfield²

2012

GeochemPersp

585

445

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“…The similarity in structure (Sp and berthierine are both 7-,~, phases) and composition between Sp/Ch and berthierine implies that they form under similar geochemical conditions (Hillier 1994), but differences in particle morphology and host rock suggest they have different origins. Berthierine commonly occurs as concentric ooids in ancient ironstones (Bailey 1988b;Velde 1989) and often originates by reaction of siderite with kaolin (James 1966;Iijima and Matsumoto 1982), whereas Sp/Ch occurs as pore-linings, peloids and infillings in tropical marine sandstones and may originate as odinite (Ehrenberg 1993;Hillier 1994;Ryan and Reynolds 1996), a 7-.~ Fe-rich mineral that forms at the sediment-seawater interface (Bailey 1988a;Odin 1990). It is primarily because of the differences in particle morphology and host rock type that we refer to the 7-~, layers in Sp/Ch as serpentine rather than the more specific mineral name berthierine.…”

Section: Composition Of the Serpentine Layersmentioning

confidence: 99%

The Chemical Composition of Serpentine/Chlorite in the Tuscaloosa Formation, United States Gulf Coast: EDX vs. XRD Determinations, Implications for Mineralogic Reactions and the Origin of Anatase

Ryan

Reynolds

1997

Clays and clay miner.

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Abstract--The chemical composition of mixed-layer serpentine/chlorite (Sp/Ch) in Tuscaloosa Formation sandstone was analyzed by energy dispersive X-ray spectroscopy (EDX) in the scanning electron miscroscope (SEM) and by X-ray diffraction (XRD). EDX results indicate little depth-controlled variation in composition, whereas XRD results suggest distinct decreases in octahedral Fe and tetrahedral A1. XRDdetermined compositions appear to be erroneous and actually reflect progressive changes in Sp/Ch unitcell dimensions caused by polytype transformations of Ibb layers to Iaa layers in a mixed-layer IbblIaa polytype. The relative lack of variation in Sp/Ch composition, especially when compared to other studies of chlorite minerals over similar temperature ranges, is attributed to a reaction mechanism whereby mineralogic transformations (serpentine layers to chlorite layers and Ibb layers to Iaa layers) occur on a layer-by-layer basis within coherent crystallites, rather than by dissolution-precipitation crystal growth.The lack of titanium in chlorite minerals is attributed to high levels of octahedral A13 § that prohibit inclusion of the highly charged Ti 4+ in the octahedral sheet. Anatase (TiO2) in the Tuscaloosa Formation apparently formed when Ti was liberated during crystallization of Sp/Ch following !he breakdown of a Ti-bearing precursor (detrital ultramafic clasts and/or odinite). Odinite, an Fe-rich 7-A phyllosilicate that forms in some shallow marine sands, apparently existed as a short-lived, poorly crystallized intermediary between dissolution of the ultramafic clasts and formation of Sp/Ch.

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“…undet) was collected from an outcrop Table 2, Structural formulae based on 7 oxygens of berthierines from published data. Numbers 1-14 were published in Brindley (1982) and 15-21 were found in James (1966). Analyses 22-48 were analyzed by (and published in) the corresponding reference number listed in Table 1 …”

Section: Chemistrymentioning

confidence: 99%

An Fe-Berthierine From A Cretaceous Laterite: Part I. Characterization

Toth

Fritz

1997

Clays and clay miner.

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Abstract--An Fe-berthierine occurs in a buried laterite from the Late Cretaceous (Cenomanian) in southwestern Minnesota. It formed beneath a lignitic horizon in which reducing solutions percolated through a laterite comprising gibbsite, kaolinite and goethite. Morphologic differences suggest 2 separate conditions of Fe-berthierine formation. Early forms of Fe-berthierine include radial bladed or radial blocky crystallites coating pisoids, along with alteration of kaolinite at crystal boundaries. These morphologies formed in the vadose zone. Later forms precipitated under subaqueous conditions as macroscopic, porefilling cement. The large size of the later-formed Fe-berthierines enabled microprobe characterization. This 1st reported occurrence of Mg-free berthierine has a structural formula close to an idealized Feberthierine: Fe2A12SiO~(OH)4 . Apart from their chemistry, the unique feature of the Minnesota Fe-berthierines is their formation in an exclusive nonmarine depositional environment. They formed in situ as part of a lateritic weathering profile developed on a broad, low relief peneplain. Physical evidence of formation under nonmarine conditions includes the presence of 1) scattered lignitic fragments; 2) concretions forming casts and molds of woody material; and 3) a nonmarine fossil (Unio sp. undet). Chemical evidence includes siderites collected from the berthierine-bearing horizon having stable isotope values indicating freshwater formation.

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Chemistry of the iron-rich sedimentary rocks

Cited by 101 publications

References 0 publications

The Iron Biogeochemical Cycle Past and Present

The Iron Biogeochemical Cycle Past and Present

The Chemical Composition of Serpentine/Chlorite in the Tuscaloosa Formation, United States Gulf Coast: EDX vs. XRD Determinations, Implications for Mineralogic Reactions and the Origin of Anatase

An Fe-Berthierine From A Cretaceous Laterite: Part I. Characterization

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