Rhenium in seawater: Confirmation of generally conservative behavior

Anbar, Ariel D.; Creaser, Robert A.; Papanastassiou, D. A.; Wasserburg, G. J.

doi:10.1016/0016-7037(92)90021-a

Cited by 129 publications

(70 citation statements)

References 20 publications

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“…However, as Koide et al (1986) pointed out, it can be reduced by hydrogen sulfide to the far less soluble tetravalent state, which led these authors to suggest that Re is a sensitive indicator of reducing conditions. This is, for example, supported by the strong Re enrichment (~40 ppb) in anoxic bottom sediments of the Black Sea (Anbar et al, 1992) compared to low Re concentrations of less than 0.3 ppb in pelagic sediments (Koide et al 1986;Colodner et al, 1993). Ultimately, in reducing sediments, Re seems to be associated with pyrite (Colodner et al, 1993).…”

Section: Redox Conditions Control the Redistribution Within The Hydromentioning

confidence: 89%

Os isotopic composition and Os and Re distribution in the active mound of the TAG hydrothermal system, MidAtlantic Ridge

Brügmann¹,

Birck²,

Herzig³

et al. 1998

Proceedings of the Ocean Drilling Program

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Drilling during ODP Leg 158 took place on the active mound of the TAG hydrothermal field on the Mid-Atlantic Ridge. The dominant mineral precipitating from the hydrothermal fluid is pyrite. Its Re and Os concentration and the Os isotopic composition provide constraints on the nature of the hydrothermal fluid circulating in the TAG mound.The 187 Os/ 186 Os ratios of massive pyrite samples vary from 4.9 to 8.9. The highest ratios have been observed in the upper part of the sulfide mountain (<20 mbsf) and the lowest in the stockwork zone at ~80 mbsf. This range of Os isotopic compositions is likely the result of mixing of seawater with hydrothermal fluid. The Os concentrations are very low, ranging from 0.04 to 4.2 ppt, and the massive pyrite zone at the top of the mound is enriched in Os relative to the interior of the hydrothermal system. A hyperbolic relationship between Os isotopic composition and Os concentration reflects the systematic addition of seawater-derived Os to the hydrothermal Os component at stratigraphically shallower levels. From this relationship it is estimated that pyrite precipitating from the hydrothermal fluid contains 0.02 to 0.04 ppt Os provided the 187 Os/ 186 Os value of the fluid ranges from about 1.3 to 4.7. Because of the great mobility of Os in the high-temperature hydrothermal system, it is assumed that its partition coefficient between pyrite and hydrothermal fluid is <1. This implies that the hydrothermal fluid contains more than 0.02 ppt Os.The occurrence of anhydrite-rich lithologies at ~30-40 mbsf corroborates that seawater is penetrating the hydrothermal system and contaminating the hydrothermal fluid circulating in the upper part of the mound. This partly explains why the Os of sulfides that precipitated above this level has a strong seawater-like isotopic signature. In addition, the massive pyrite zone of the upper part of the TAG mound formed by accumulation of sulfides derived from chimneys and the fall-out material of the hydrothermal plume above the TAG field. Both sulfide components formed during mixing of seawater and hydrothermal fluid and their Os should also have a distinct seawater component.These processes, especially the entrainment of seawater, appear to control the distribution of Os and Re within the hydrothermal system. The Os enrichment in the upper part of the mound can be explained if the element is co-precipitated with sulfides or adsorbed on mineral surface during the accumulation of sulfides on the TAG mound. As a significant amount of Os can be dissolved in the hydrothermal fluid, remobilization of Os within the hydrothermal system could lead to further Os enrichment at the top of the mound but to very low Os concentrations in the stockwork zone.The Re concentrations indicate a distribution opposite to that of Os: the highest concentrations of about 60 ppb have been observed more than 15 mbsf, but the concentrations decrease from 50 to 2 ppb in samples from the top of the sulfide mound (<15 mbsf). The behavior of Re appears to be controlled by...

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Section: Redox Conditions Control the Redistribution Within The Hydromentioning

confidence: 89%

Os isotopic composition and Os and Re distribution in the active mound of the TAG hydrothermal system, MidAtlantic Ridge

Brügmann¹,

Birck²,

Herzig³

et al. 1998

Proceedings of the Ocean Drilling Program

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“…Similar calculations for Re, assuming an ORM abundance of 100 ppb, yield an accumulation rate of 1.25×10 4 kg/a/10 6 km 2 , which is close to the present-day mean annual riverine input of 1.54×10 4 kg [40]. Likewise, the quantity of Re accumulating annually per cm 2 (1.25×10 -9 g), assuming a mean seawater Re concentration of 8 ppt [46], is contained in a water column 1.56 m by 1 cm 2 . The difference in water volume required to provide the hydrogenous Re and Os budgets of ORM reflects differences in their seawater concentrations and uptake rates in the accumulating organic-rich sediments.…”

Section: Accumulation Rates Of Re and Os In Jurassic Ormmentioning

confidence: 94%

“…As noted in previous studies, organic-rich sediments and ORM act as major repositories of Re and Os in the Earth's crust [1,38,40,46,47]. Thus significant proportions of the global marine budgets of these elements may be removed from seawater during times of widespread [48]).…”

Section: Accumulation Rates Of Re and Os In Jurassic Ormmentioning

confidence: 99%

Precise Re–Os ages of organic-rich mudrocks and the Os isotope composition of Jurassic seawater

Cohen

Coe

Bartlett

et al. 1999

Earth and Planetary Science Letters

229

162

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Rhenium and osmium isotope and abundance data have been obtained on precisely-located samples from three suites of immature, organic-rich mudrocks from Jurassic coastal outcrops in England. The data provide precise and accurate whole-rock ages of 207±12 Ma, 181±13 Ma and 155±4.3 Ma for suites of Hettangian, Toarcian (exeratum Subzone) and Kimmeridgian (sensu anglico, wheatleyensis Subzone) samples. These new Re-Os ages are indistinguishable, within the assigned analytical uncertainties, from interpolated depositional ages estimated from published geological timescales, and establish the importance of the ReOs dating technique for chronostratigraphic studies. Early-diagenetic pyrite nodules possess levels of Re and Os which are ~1-2 orders of magnitude lower than in the enclosing organicrich mudrocks, indicating that these elements had already been removed from sediment pore waters at the time of nodule formation. Thus the Re-Os isotope system in these organic-rich mudrocks has been closed since, or from very soon after, the time of sediment deposition.Because most of the Re (98%+) and Os (95-99.8%+) in the mudrocks is shown to be hydrogenous, the 187 Os/ 188 Os (i) of the samples is interpreted to be that of contemporaneous seawater. The data thereby provide the first estimates of the Os isotope composition of Jurassic seawater. During the earliest Jurassic (Hettangian), the seawater 187 Os/ 188 Os ratio was extremely unradiogenic (~0.15); it had increased to ~0.8 at the end of the Early Jurassic (Toarcian) ~20 Ma later, while in the Late Jurassic (Kimmeridgian) the seawater 187 Os/ 188 Os ratio was ~0.59. The most likely explanation for the unradiogenic Os isotope composition of Hettangian seawater is that the contribution of unradiogenic Os to the oceans from the hydrothermal alteration of oceanic crust greatly exceeded the input of radiogenic Os from the continents at that time. This interpretation is in line with observations suggesting that global weathering rates were low in the Hettangian, and that increased hydrothermal and volcanic activity preceded the break-up of Pangea. The Re/Os ratios of Hettangian mudrocks (and by inference, of contemporaneous seawater) are similar to those of mudrocks deposited at later times during the Jurassic, and argues against the unradiogenic Os in Hettangian seawater being derived from extraterrestrial meteoritic sources.

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“…Rhenium exists in seawater primarily as the soluble perrhenate oxyanion ReO 4 -, with a concentration of 40 pmol kg -1 (Anbar et al, 1992;Colodner et al, 1993). In the modern ocean, most of this dissolved reservoir is derived from oxidative weathering of sulfide minerals, based on the good correlation observed globally between Re and sulfate concentrations in rivers, and from weathering of ORM in the upper continental crust (Colodner et al, 1993;Miller et al, 2011;Dubin and Peucker-Ehrenbrink, 2015).…”

Section: Marine Sourcesmentioning

confidence: 99%

A model for the oceanic mass balance of rhenium and implications for the extent of Proterozoic ocean anoxia

Sheen

Kendall

Reinhard

et al. 2018

Geochimica et Cosmochimica Acta

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Emerging geochemical evidence suggests that the atmosphere-ocean system underwent a significant decrease in O 2 content following the Great Oxidation Event (GOE), leading to a mid-Proterozoic ocean (ca. 2.0-0.8 Ga) with oxygenated surface waters and predominantly anoxic deep waters. The extent of mid-Proterozoic seafloor anoxia has been recently estimated using mass-balance models based on molybdenum (Mo), uranium (U), and chromium (Cr) enrichments in organic-rich mudrocks (ORM). Here, we use a temporal compilation of concentrations for the redox-sensitive trace metal rhenium (Re) in ORM to provide an independent constraint on the global extent of mid-Proterozoic ocean anoxia and as a tool for more generally exploring how the marine geochemical cycle of Re has changed through time. The compilation reveals that mid-Proterozoic ORM are dominated by low Re concentrations that overall are only mildly higher than those of Archean ORM and significantly lower than many ORM deposited during the ca. 2.22-2.06 Ga Lomagundi Event and during the Phanerozoic Eon. These temporal trends are consistent with a decrease in the oceanic Re inventory in response to an expansion of anoxia after an interval of increased oxygenation during the Lomagundi Event. Mass-balance modeling of the marine Re geochemical cycle indicates that the mid-Proterozoic ORM with low Re enrichments are consistent with extensive seafloor anoxia. Beyond this agreement, these new data bring added value because Re, like the other metals, responds generally to lowoxygen conditions but has its own distinct sensitivity to the varying environmental controls. Thus, we can broaden our capacity to infer nuanced spatiotemporal patterns in ancient redox landscapes. For example, despite the still small number of data, some mid-Proterozoic ORM units have higher Re enrichments that may reflect a larger oceanic Re inventory during transient episodes of ocean oxygenation. An improved understanding of the modern oceanic Re cycle and a higher temporal resolution for the Re compilation will enable further tests of these hypotheses regarding changes in the surficial Re geochemical cycle in response to variations in atmosphere-ocean oxygenation. Nevertheless, the existing Re compilation and model results are in agreement with previous Cr, Mo, and U evidence for pervasively anoxic and ferruginous conditions in mid-Proterozoic oceans.

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Rhenium in seawater: Confirmation of generally conservative behavior

Cited by 129 publications

References 20 publications

Os isotopic composition and Os and Re distribution in the active mound of the TAG hydrothermal system, MidAtlantic Ridge

Os isotopic composition and Os and Re distribution in the active mound of the TAG hydrothermal system, MidAtlantic Ridge

Precise Re–Os ages of organic-rich mudrocks and the Os isotope composition of Jurassic seawater

A model for the oceanic mass balance of rhenium and implications for the extent of Proterozoic ocean anoxia

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Rhenium in seawater: Confirmation of generally conservative behavior

Cited by 129 publications

References 20 publications

Os isotopic composition and Os and Re distribution in the active mound of the TAG hydrothermal system, MidAtlantic Ridge

Os isotopic composition and Os and Re distribution in the active mound of the TAG hydrothermal system, MidAtlantic Ridge

Precise Re–Os ages of organic-rich mudrocks and the Os isotope composition of Jurassic seawater

A model for the oceanic mass balance of rhenium and implications for the extent of Proterozoic ocean anoxia

Contact Info

Product

Resources

About

Os isotopic composition and Os and Re distribution in the active mound of the TAG hydrothermal system, MidAtlantic Ridge

Os isotopic composition and Os and Re distribution in the active mound of the TAG hydrothermal system, MidAtlantic Ridge