Geochemical and iron isotopic insights into hydrothermal iron oxyhydroxide deposit formation at Loihi Seamount

Rouxel, Olivier; Toner, Brandy M.; Germain, Yoan; Glazer, Brian T.

doi:10.1016/j.gca.2017.09.050

Cited by 58 publications

(55 citation statements)

References 168 publications

(288 reference statements)

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“…7; Kurzweil et al, 2016). A close relationship between lighter 56 Fe values and Mn precipitation has also been shown for modern Loihi Seamount deposits, precipitated from oxic seawater (Rouxel et al, 2018) (Fig.7). This lends further support to oxygenated conditions driving Mn and Fe precipitation, and thus Fe and Mo isotope fractionations, during deposition of the Mozaan Group.…”

Section: Model For Iron Precipitation and Implications For A Mn-oxyhysupporting

confidence: 68%

Aerobic iron and manganese cycling in a redox-stratified Mesoarchean epicontinental sea

Ossa

Hofmann

Wille

et al. 2018

Earth and Planetary Science Letters

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Section: Model For Iron Precipitation and Implications For A Mn-oxyhysupporting

confidence: 68%

Aerobic iron and manganese cycling in a redox-stratified Mesoarchean epicontinental sea

Ossa

Hofmann

Wille

et al. 2018

Earth and Planetary Science Letters

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“…In conclusion, iron isotope compositions of microbial laminae from all the studied ferruginous stromatolites display a range between −0.75‰ and +0.66‰ which indicate that iron isotope compositions of hydrothermal iron (oxyhydr)oxide precipitates are sensitive to local environmental conditions where they form. Rouxel, Toner, Germain, and Glazer () proposed that both positive and negative δ 56 Fe values are likely the result of partial oxidation of iron formation near or below the seafloor during the circulation of low‐temperature hydrothermal source.…”

Section: Discussion and Interpretationmentioning

confidence: 99%

Microaerophilic Fe‐oxidizing micro‐organisms in Middle Jurassic ferruginous stromatolites and the paleoenvironmental context of their formation (Southern Carpathians, Romania)

et al. 2020

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Ferruginous stromatolites occur associated with Middle Jurassic condensed deposits in several Tethyan and peri-Tethyan areas. The studied ferruginous stromatolites occurring in the Middle Jurassic condensed deposits of Southern Carpathians (Romania) preserve morphological, geochemical, and mineralogical data that suggest microbial iron oxidation. Based on their macrofabrics and accretion patterns, we classified stromatolites: (1) Ferruginous microstromatolites associated with hardground surfaces and forming the cortex of the macro-oncoids and (2) Domical ferruginous stromatolites developed within the Ammonitico Rosso-type succession disposed above the ferruginous microstromatolites (type 1). Petrographic and scanning electron microscope (SEM) examinations reveal that different types of filamentous micro-organisms were the significant framework builders of the ferruginous stromatolitic laminae. The studied stromatolites yield a large range of δ 56 Fe values, from −0.75‰ to +0.66‰ with predominantly positive values indicating the prevalence of partial ferrous iron oxidation. The lowest negative δ 56 Fe values (up to −0.75‰) are present only in domical ferruginous stromatolites samples and point to initial iron mobilization where the Fe(II) was produced by dissimilatory Fe(III) reduction of ferric oxides by Fe(III)reducing bacteria. Rare-earth elements and yttrium (REE + Y) are used to decipher the nature of the seawater during the formation of the ferruginous stromatolites. Cerium anomalies display moderate to small negative values for the ferruginous microstromatolites, indicating weakly oxygenated conditions compatible with slowly reducing environments, in contrast to the domical ferruginous stromatolites that show moderate positive Ce anomalies suggesting that they formed in deeper, anoxic-suboxic waters. The positive Eu anomalies from the studied samples suggest a diffuse hydrothermal input on the seawater during the Middle Jurassic on the sites of ferruginous stromatolite accretion. This study presents the first interpretation of REE + Y in the Middle Jurassic ferruginous stromatolites of Southern Carpathians, Romania. K E Y W O R D S ferruginous stromatolites, iron isotopes, Jurassic, microbial signatures, rare-earth elements, Romania | 367 GRĂDINARU et Al. the reviewers Maxwell Lechte and Alain R. Préat and to the editor N. J. Planavsky for their corrections, comments, and suggestions that strongly improved the original manuscript. AUTH O R CO NTR I B UTI O N S M.G. and I.L. conducted the design, field work, prepared samples, thin sections, polished slabs, light micrographs, and acquired ESEM/ EDS data, performed XRF and CL analyses, microfacies analyses and wrote the paper. M.G. and M.N.D. performed REE + Y and iron isotopes measurements. L.P. acquired XRD data. O RCI D Mihaela Grădinaru https://orcid.org/0000-0003-3669-0472 S U PP O RTI N G I N FO R M ATI O N Additional supporting information may be found online in the Supporting Information section. How to cite this article: Grădinaru M, Lazăr I, Ducea MN...

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“…8c shows the Loihi-sourced 3 He profile as estimated by subtracting the average of "background" station profiles between 5 and 10 • N (station 21) and between 30 and 35 • N (stations 14 and 16). The helium isotope profiles nearest Loihi exhibit a significant 3 He signature between 900 and 1300 m depth with a maximum near 1100 m. The large vertical spread may be due in part to the topographic distribution of the many hydrothermal vent sites (Bennett et al, 2011;Clague et al, 2019;Rouxel et al, 2018) at Loihi. In addition, although diapycnal mixing in the open ocean is weak (Ledwell et al, 1998(Ledwell et al, , 1993, seamounts are known sites of enhanced vertical mixing (Lueck and Mudge, 1997;Toole et al, 1997).…”

Section: Estimating the Hydrothermal 3 He Fluxmentioning

confidence: 96%

“…Second, Loihi and the SEPR have vastly different geochemical, geological, hydrothermal, and tectonic characteristics, making it even more unlikely that Fe and 3 He would have similar ratios. The SEPR is a mid-ocean ridge spreading center with a shallow (∼1 km depth) magma chamber, tholeiitic basalts, and high temperature hydrothermal vent fluids, while Loihi is a mid-plate, mantle plume-driven shield-building volcano with a deeper (∼10 km depth) magma chamber, and lower temperature hydrothermal vent fluids (German et al, 2018;Rouxel et al, 2018). Furthermore, SEPR vents have millimolar concentrations of H 2 S (Von Damm et al, 2003), which should minimize dFe concentrations due to precipitation of iron sulfides (Feely et al, 1996(Feely et al, , 1987.…”

Section: The "Distal" Stationsmentioning

confidence: 99%

An intermediate-depth source of hydrothermal 3He and dissolved iron in the North Pacific

Jenkins

Hatta

Fitzsimmons

et al. 2020

Earth and Planetary Science Letters

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We observed large water column anomalies in helium isotopes and trace metal concentrations above the Loihi Seamount. The 3 He/ 4 He of the added helium was 27.3 times the atmospheric ratio, clearly marking its origin to a primitive mantle plume. The dissolved iron to 3 He ratio (dFe: 3 He) exported to surrounding waters was 9.3 ± 0.3 × 10 6. We observed the Loihi 3 He and dFe "signal" at a depth of 1100 m at several stations within ∼100-1000 km of Loihi, which exhibited a distal dFe: 3 He ratio of ∼4 × 10 6 , about half the proximal ratio. These ratios were remarkably similar to those observed over and near the Southern East Pacific Rise (SEPR) despite greatly contrasting geochemical and volcanictectonic origins. In contrast, the proximal and distal dMn: 3 He ratios were both ∼ 1 × 10 6 , less than half of that observed at the SEPR. Dissolved methane was minimally enriched in waters above Loihi Seamount and was distally absent. Using an idealized regional-scale model we replicated the historically observed regional 3 He distribution, requiring a hydrothermal 3 He source from Loihi of 10.4 ± 4.2 mol a −1 , ∼2% of the global abyssal hydrothermal 3 He flux. From this we compute a corresponding dFe flux of ∼40 Mmol a −1. Global circulation model simulations suggest that the Loihi-influenced waters eventually upwell along the west coast of North America, also extending into the shallow northwest Pacific, making it a possibly important determinant of marine primary production in the subpolar North Pacific.

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Geochemical and iron isotopic insights into hydrothermal iron oxyhydroxide deposit formation at Loihi Seamount

Abstract: Please note that this is an author-produced PDF of an article accepted for publication following peer review. The definitive publisher-authenticated version is available on the publisher Web site.

Cited by 58 publications

References 168 publications

Aerobic iron and manganese cycling in a redox-stratified Mesoarchean epicontinental sea

Aerobic iron and manganese cycling in a redox-stratified Mesoarchean epicontinental sea

Microaerophilic Fe‐oxidizing micro‐organisms in Middle Jurassic ferruginous stromatolites and the paleoenvironmental context of their formation (Southern Carpathians, Romania)

An intermediate-depth source of hydrothermal 3He and dissolved iron in the North Pacific

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