Synsedimentary formation of ooidal ironstone: An example from the Jurassic deposits of SE central Iran

Rahiminejad, Amir Hossein; Zand-Moghadam, Hamed

doi:10.1016/j.oregeorev.2018.02.028

Cited by 15 publications

(8 citation statements)

References 68 publications

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“…These peculiar sediments are mainly deposited in marine environments (Vanhouten, 1985(Vanhouten, , 1992Young, 1989Young, , 1992, but were locally reported from Jurassic to Neogene non-marine strata (McGregor et al, 2009). Ferruginous ooids are distinguished from more common carbonate ooids by their high iron content and generally concentric fabric (radial fabric has been reported so far only from Jurassic ironstones in Iran; Rahiminejad and Zand-Moghadam, 2018). The main iron-rich minerals include hematite, goethite, and chamosite (Mucke and Farshad, 2005).…”

Section: Introductionmentioning

confidence: 99%

“…The ooidal ironstones record the redox states and chemical conditions of the ocean and atmosphere (Sturesson, 1992(Sturesson, , 2003, and reflect the evolution of tectonic, magmatic, and biological activities (Garzanti et al, 1989;Vancappellen and Berner, 1991;Garzanti, 1993;Follmi, 1996Follmi, , 2016Tang et al, 2017;Rahiminejad and Zand-Moghadam, 2018;Rudmin et al, 2020). Deposition of marine ooidal ironstones took place preferentially during periods of rapid transgression leading to condensed deposition (Vanhouten and Purucker, 1984;Garzanti et al, 1989;Vanhouten, 1992;Donaldson et al, 1999;Sturesson, 2003;Taylor and Macquaker, 2011;Follmi, 2016).…”

Section: Introductionmentioning

confidence: 99%

“…Ooidal ironstones are temporally distributed from the Precambrian to the present day (Young, 1989;Mucke and Farshad, 2005), and were principally reported to occur in the Ordovician to Devonian and in the Jurassic to Paleogene (Rahiminejad and Zand-Moghadam, 2018). Jurassic ooidal ironstones are widely developed in Asia, Europe, and Oceania.…”

Section: Introductionmentioning

confidence: 99%

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Middle Jurassic ooidal ironstones (southern Tibet): Formation processes and implications for the paleoceanography of eastern Neo-Tethys

Han

Han²,

Garzanti³

et al. 2023

Front. Earth Sci.

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The major facies changes documented in shallow-marine sediments of the northern Indian passive margin of Neo-Tethys throughout the Jurassic, from widespread platform carbonates in the Early Jurassic to organic-rich black shales in the Late Jurassic, imply a substantial turnover in oceanic conditions. All along the Tethys (Tibetan) Himalaya, from the Zanskar Range to southern Tibet, a peculiar interval characterized by ooidal ironstones of Dingjie Formation (Ferruginous Oolite Formation, FOF) marks the base of the organic-rich Spiti Shale. This laterally-extensive ooidal ironstone interval is a fundamental testimony of the mechanisms that led to major paleoceanographic changes that occurred in the eastern Neo-Tethys during the Middle Jurassic. In this article, we illustrate in detail the petrology, mineralogy, and geochemistry of ooidal ironstones and the major element contents of the entire Lanongla section. The FOF is characterized by significantly high contents of Fe2O3 (56.80% ± 9.07%, n = 7) and P2O5 (1.72% ± 1.19%, n = 7). In contrast, the Fe2O3 and P2O5 contents average 3.58% and 0.15% in the overlain carbonates of Lanongla Fm., and 5.55% and 0.16% in the overlying Spiti Shale. The ooidal ironstones are mainly composed of iron ooids with a few quartz grains and bioclasts cemented by sparry calcite. The iron ooids consist of concentric dark layers of francolite (carbonate fluorapatite), hence enriched in Ca, P, and F, and bright layers of chamosite, enriched in Fe, Si, Al, and Mg. Precipitation of francolite ensued from oversaturation of phosphorous ascribed to intensified upwelling, high biogenous productivity, and degradation of organic matter, whereas the formation of chamosite reflects enhanced continental weathering and erosion leading to increased Fe input to the ocean during transgressive stages characterized by low sedimentation rate and scarce oxygenation at the seafloor. Modern upwelling zones in outer shelf or slope areas perform similar geochemical characteristics to those as observed in this study. Under the Mesozoic greenhouse background, fluctuating redox conditions induced the alternate growth of francolite under anoxic conditions and of chamosite under suboxic conditions. Ooids were thus formed on the seafloor during continued resuspension and vertical oscillations of the chemocline rather than from interstitial waters after burial. The mineralogy of iron ooids indicates mainly reducing conditions in the water column, suggesting that extensive upwelling along the continental margin of eastern Neo-Tethys contributed significantly to the transition from carbonate deposits to organic-rich black shales during the Jurassic, as testified by the transition from well-oxygenated in Lanongla Fm. To a reduceing condition in Spiti Shale indicated by the Mn/Al ratios compared to PAAS.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Middle Jurassic ooidal ironstones (southern Tibet): Formation processes and implications for the paleoceanography of eastern Neo-Tethys

Han

Han²,

Garzanti³

et al. 2023

Front. Earth Sci.

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“…However, Phanerozoic oolitic ironstones frequently involve chamosite (Sturesson, 1992; Sharma & Dix, 2004; Garcia‐Frank et al ., 2012; Rahiminejad & Zand‐Moghadam, 2018), a chlorite‐group mineral [(Fe 2+ , Mg, Al, Fe 3+ ) 6 (Si 4‐x )O 10 (OH) 8 ], which requires relatively reducing conditions (Young, 1989a; Damyanov & Vassileva, 2001). This fact likely contradicts the more frequently agitated and oxidized shallow‐marine environment during the Phanerozoic (Sturesson & Bauert, 1994; Rahiminejad & Zand‐Moghadam, 2018). Consequently, authigenic chamosite precipitation in shallow‐marine settings has been mainly attributed to: (i) precipitation of Fe 2+ ‐rich volcanic ash in oxidizing seawater (Sturesson et al ., 2000); (ii) deep, hypoxic, Fe 2+ ‐rich seawater upwelling and mixing with oxidizing water (Todd et al ., 2019; Pufahl et al ., 2020); or (iii) fluctuations in the oxygen‐minimum zone (Clement et al ., 2020).…”

Section: Introductionmentioning

confidence: 99%

“…In contrast, marine oolitic ironstones in the Phanerozoic are generally considered to have formed in relatively warm, shallow‐water environments, in which the seawater was commonly in an oxidizing state (Sturesson, 1992), favouring the oxidation of Fe 2+ and precipitation of Fe 3+ . However, Phanerozoic oolitic ironstones frequently involve chamosite (Sturesson, 1992; Sharma & Dix, 2004; Garcia‐Frank et al ., 2012; Rahiminejad & Zand‐Moghadam, 2018), a chlorite‐group mineral [(Fe 2+ , Mg, Al, Fe 3+ ) 6 (Si 4‐x )O 10 (OH) 8 ], which requires relatively reducing conditions (Young, 1989a; Damyanov & Vassileva, 2001). This fact likely contradicts the more frequently agitated and oxidized shallow‐marine environment during the Phanerozoic (Sturesson & Bauert, 1994; Rahiminejad & Zand‐Moghadam, 2018).…”

Section: Introductionmentioning

confidence: 99%

Microbe‐mediated, marine authigenic formation of ooidal chamosite: Insights from upper Ordovician carbonates of the South‐Western Yangtze platform (China)

et al. 2023

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Chamosite is a common marine authigenic mineral and microbial involvement has been often assumed during its formation. However, the fossil record of such microbial activity is ambiguous. Chamosite oolitic ironstones widely occur in the Upper Ordovician of the Yangtze Platform, but their origin remains unclear. In this study, detailed sedimentological and mineralogical investigations on ironstones from the Haima section (south-western Yangtze Platform) helped unravel the critical role of cyanobacterial activity during marine chamosite authigenesis. Stratigraphically, deposition of the Haima oolitic ironstones corresponded with an early Katian transgression, temporally equivalent to many other early Palaeozoic counterparts worldwide. Petrographic observations revealed that different chamosite forms (ooids, peloids and matrix) all developed in close association with calcified cyanobacteria, suggesting that cyanobacteria-involved chamosite formation existed across a wide range of hydrodynamic conditions from above fairweather wave base to below storm wave base. Further mineralogical characterization (backscatter imaging and electron-microprobe analyses) at singlegrain scale revealed clear mineral zonation from the matrix (dispersed iron oxide and microquartz) through the calcified cyanobacterial sheaths (dispersed chamosite) to the ooid (chamosite). This zonation is best explained by cyanobacterial microbial mats that created benthic reducing and high-pH conditions. These conditions drove near-seafloor, dispersed iron oxide and microquartz (primary precipitates formed in oxic seawater) to form chamosite. The authigenic chamosite, originally dispersed within and surrounding the microbial mats, could be reworked to develop other chamositic grains. It is proposed here that the early Katian transgression was responsible for the chamosite-oolitic-ironstone development. The marine transgression submerged earlier-exposed lands and likely supplied Fe-Al-rich colloidal materials to an open marine setting for the chamosite authigenesis. Moreover, transgression likely triggered upwelling, delivered ferruginous deeper water as an extra Fe source and provided nutrients for the cyanobacterial microbial-mat development, which was essential for the widespread chamosite authigenesis across the south-western Yangtze Platform.

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Geochemistry of Callovian Ironstone in Kutch and Its Stratigraphic Implications

Bansal

Banerjee

Chauhan

et al. 2021

Mesozoic Stratigraphy of India

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Synsedimentary formation of ooidal ironstone: An example from the Jurassic deposits of SE central Iran

Cited by 15 publications

References 68 publications

Middle Jurassic ooidal ironstones (southern Tibet): Formation processes and implications for the paleoceanography of eastern Neo-Tethys

Middle Jurassic ooidal ironstones (southern Tibet): Formation processes and implications for the paleoceanography of eastern Neo-Tethys

Microbe‐mediated, marine authigenic formation of ooidal chamosite: Insights from upper Ordovician carbonates of the South‐Western Yangtze platform (China)

Geochemistry of Callovian Ironstone in Kutch and Its Stratigraphic Implications

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