The osmium riverine flux and the oceanic mass balance of osmium

Levasseur, S.; Birck, J. L.; Allègre, Claude J.

doi:10.1016/s0012-821x(99)00259-9

Cited by 168 publications

(187 citation statements)

References 49 publications

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“…2). Levasseur et al, 1999), consistent with a highly radiogenic Os flux dominated by evolved, continentally derived sediment and waters (Xu et al, 2009;Cumming et al, 2012;Cumming et al, 2013;Rooney et al, 2014). These data demonstrate that the Borden Basin had minimal communication with the global ocean during deposition of the sampled black shale units from the middle Arctic Bay (Turner and Kamber, 2012;Hahn et al, 2015) and lower Victor Bay formations and was strongly influenced chemically by runoff from the surrounding highly-evolved Archean to Paleoproterozoic orthogneiss and metasedimentary successions of the Rae Province (Crocker et al, 1993).…”

Section: Therefore Samples From Section Mb1501 Of the Same Maximum Fmentioning

confidence: 61%

Precise age of Bangiomorpha pubescens dates the origin of eukaryotic photosynthesis

Gibson

Shih

Cumming

et al. 2017

Geology

161

128

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Shale samples were collected from outcrops that lack evidence for secondary mineralization from hydrothermal activity and weathered regions that may have experienced alteration were also avoided. Sample sets comprise several 100-200 g samples excavated 10-30 cm from the outcrop surface to target fresh material. Samples were collected along strike from a narrow stratigraphic range (<10 cm), as well as from a vertical profile (up to 5 m). The most organic-rich and least visibly-weathered samples were then chosen for digestion and isotopic

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Section: Therefore Samples From Section Mb1501 Of the Same Maximum Fmentioning

confidence: 61%

Precise age of Bangiomorpha pubescens dates the origin of eukaryotic photosynthesis

Gibson

Shih

Cumming

et al. 2017

Geology

161

128

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“…Measurements of gas condensate from Kudryavy found them to have lower 187 Os/ 188 Os than the unaltered volcanic rocks (26). Because there is no reason for fractionation of Os isotopes between volcanic aerosols and rocks, the average aerosols likely have Os values closer to Ϸ0.53 (25). If so, subaerial volcanism may not be the primary source of Os in precipitation.…”

Section: Discussionmentioning

confidence: 99%

“…E-mail: mukul.sharma@dartmouth.edu. island arcs suggest that the average 187 Os/ 188 Os ratio of the aerosols could be Ϸ0.53 (25), although measurements of Kudryavy volcano show gas condensates to be less radiogenic (0.122-0.152) than the volcanic rocks (0.205-0.588) (26).…”

mentioning

confidence: 99%

Anthropogenic osmium in rain and snow reveals global-scale atmospheric contamination

Chen

Sedwick

Sharma

2009

Proc. Natl. Acad. Sci. U.S.A.

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Osmium is one of the rarer elements in seawater, with typical concentration of Ϸ10 ؋ 10 ؊15 g g ؊1 (5.3 ؋ 10 ؊14 mol kg ؊1 ). The osmium isotope composition ( 187 Os/ 188 Os ratio) of deep oceans is 1.05, reflecting a balance between inputs from continental crust (Ϸ1.3) and mantle/cosmic dust (Ϸ0.13). Here, we show that the 187 Os/ 188 Os ratios measured in rain and snow collected around the world range from 0.16 to 0.48, much lower than expected (>1), but similar to the isotope composition of ores (Ϸ0.2) that are processed to extract platinum and other metals to be used primarily in automobile catalytic converters. Present-day surface seawater has a lower 187 Os/ 188 Os ratio (Ϸ0.95) than deep waters, suggesting that human activities have altered the isotope composition of the world's oceans and impacted the global geochemical cycle of osmium. The contamination of the surface ocean is particularly remarkable given that osmium has few industrial uses. The pollution may increase with growing demand for platinum-based catalysts.pollution ͉ seawater ͉ isotopes ͉ platinum group metals ͉ precipitation

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“…In turn, the history of weathering on land is partly reflected by the Mg evolution of the ocean, recorded by marine carbonates. Given that Mg is critically involved in the long-term carbon cycle, studying Mg isotopes offers advantages over trace elements that are not involved so directly, such as strontium or osmium isotopes (Palmer and Edmond, 1992;Levasseur et al, 1999;Georg et al, 2013). The dominant Mg source to the oceans is thought to be continental weathering, via rivers and groundwater, while the main sinks are removal by hydrothermal fluids (primarily by high-temperature interaction with basalt, which is thought to quantitatively strip Mg from fluids), dolomite formation and low-temperature clay formation during alteration of the oceanic crust (Holland, 2005).…”

Section: Introductionmentioning

confidence: 99%

Modern and Cenozoic records of seawater magnesium from foraminiferal Mg isotopes

2014

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Abstract. Magnesium is an element critically involved in the carbon cycle, because weathering of Ca-Mg silicates removes atmospheric CO 2 into rivers, and formation of Ca-Mg carbonates in the oceans removes carbon from the oceanatmosphere system. Hence the Mg cycle holds the potential to provide valuable insights into Cenozoic climate-system history, and the shift during this time from a greenhouse to icehouse state. We present Mg isotope ratios for the past 40 Myr using planktic foraminifers as an archive. Modern foraminifera, which discriminate against elemental and isotopically heavy Mg during calcification, show no correlation between the Mg isotope composition (δ 26 Mg, relative to DSM-3) and temperature, Mg / Ca or other parameters such as carbonate saturation ( CO 3 ). However, inter-species isotopic differences imply that only well-calibrated single species should be used for reconstruction of past seawater. Seawater δ 26 Mg inferred from the foraminiferal record decreased from ∼ 0 ‰ at 15 Ma, to −0.83 ‰ at the present day, which coincides with increases in seawater lithium and oxygen isotope ratios. It strongly suggests that neither Mg concentrations nor isotope ratios are at steady state in modern oceans, given its ∼ 10 Myr residence time. From these data, we have developed a dynamic box model to understand and constrain changes in Mg sources to the oceans (rivers) and Mg sinks (dolomitisation and hydrothermal alteration). Our estimates of seawater Mg concentrations through time are similar to those independently determined by pore waters and fluid inclusions. Modelling suggests that dolomite formation and the riverine Mg flux are the primary controls on the δ 26 Mg of seawater, while hydrothermal Mg removal and the δ 26 Mg of rivers are more minor controls. Using Mg riverine flux and isotope ratios inferred from the 87 Sr / 86 Sr record, the modelled Mg removal by dolomite formation shows minima in the Oligocene and at the present day (with decreasing trends from 15 Ma), both coinciding with rapid decreases in global temperatures.

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The osmium riverine flux and the oceanic mass balance of osmium

Cited by 168 publications

References 49 publications

Precise age of Bangiomorpha pubescens dates the origin of eukaryotic photosynthesis

Precise age of Bangiomorpha pubescens dates the origin of eukaryotic photosynthesis

Anthropogenic osmium in rain and snow reveals global-scale atmospheric contamination

Modern and Cenozoic records of seawater magnesium from foraminiferal Mg isotopes

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