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30 results on '"Birck, J. L."'

11. Geological respiration of a mountain belt revealed by the trace element rhenium

Author

Hilton, R. G., Gaillardet, J., Calmels, D., and Birck, J.-L.

Subjects
Rhenium, Erosion, Weathering, Carbon cycle, Mountain rivers, Organic carbon
Abstract

Oxidation of rock-derived, petrogenic, organic carbon (OCpetro) during weathering of sedimentary rocks is a major source of carbon dioxide (CO2) to the atmosphere. This geological respiration is thought to be enhanced by physical erosion, suggesting that mountain belts could release large amounts of CO2 to counter the CO2 sequestration achieved by the erosion, riverine transfer and oceanic burial of organic carbon from the terrestrial biosphere. However, OCpetro oxidation rates in mountain belts have not been quantified. Here we use rhenium (Re) as a proxy to track OCpetro oxidation in mountain river catchments of Taiwan, where existing measurements of physical erosion rate allow the controls on OCpetro oxidation to be assessed. Re has been shown to be closely associated with OCpetro in rocks and following oxidation during chemical weathering forms a soluble oxyanion (View the MathML source) which contributes to the dissolved load of rivers. Soils on meta-sedimentary rocks in Taiwan show that Re loss is coupled to OCpetro loss during weathering, confirming previous observations from soil profiles on sedimentary rocks elsewhere. In Taiwan rivers, dissolved Re flux increases with the catchment-average sediment yield, suggesting that physical erosion rate is a major control on OCpetro oxidation. Based on our current understanding of Re mobility during weathering, the dissolved Re flux can be used to quantify an upper bound on the OCpetro oxidation rate and the associated CO2 transfer. The estimated CO2 release from this mountain belt by OCpetro oxidation does not negate estimates of CO2 sequestration by burial of biospheric OC offshore. The findings are compared to OC transfers estimated for the Himalaya, where OCpetro oxidation in the mountain belt remains unconstrained. Together, these cases suggest that mountain building in the tropics can result in a net sink of OC which sequesters atmospheric CO2.

Published
2014

13. Osmium, tungsten and chromium isotopes in sediments and Ni-rich spinel at the K/T boundary: Signature of a chondritic impactor

Author

Quitté, Ghylaine, Robin, Eric, Levasseur, S., Capmas, F., Rocchia, R., Birck, J.-L., Allègre, C. J., Secrétariat, Sylvie, Laboratoire de Sciences de la Terre (LST), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.STU] Sciences of the Universe [physics]/Earth Sciences, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2007

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

Author

Brügmann, G. E., Birck, J. L., Herzig, Peter M., and Hofmann, A. W.

Abstract

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 187Os/186Os 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 (

Published
1998

16. Nickel and chromium isotopes in Allende inclusions

Author

Birck, J. L and Lugmair, G. W

Subjects
Lunar And Planetary Exploration
Abstract

High-precision nickel and chromium isotopic measurements were carried out on nine Allende inclusions. It is found that Ni-62, Ni-64, excesses are present in at least three of the samples. The results suggest that the most likely mechanism for the anomalies is a neutron-rich statistical equilibrium process. An indication of elevated Ni-60 is found in almost every inclusion measured. This effect is thought to be related to the decay of now extinct Fe-60. An upper limit of 1.6 X 10 to the -6th is calculated for the Fe-60/Fe-56 ratio at the time these Allende inclusions crystallized.

Published
1988
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17. Rb-Sr age and content of potassium, rubidium strontium, barium, and rare earths in surface material from the Sea of Fertility

Author

Allegre, C. J, Birck, J. L, Loubet, M, and Provost, A

Subjects
Lunar And Planetary Exploration
Abstract

The Luna 16 automatic station returned from the Sea of Fertility a 35 cm long column of lunar surface material. 1 g of the Luna 16 lunar surface material, taken at a depth of 22 cm, consists of fine material: surface material and fine fragments of rocks from 1 to 4 mm in diameter. Analyses made on 17 mg of the fine lunar surface material are presented. The results obtained for the Luna 16 surface material are plotted on the diagram of the isotopic evolution of strontium and show that this surface material is most depleted of radiogenic Sr-87 of all the known lunar surface materials and that the point characterizing Lunar 16 lies somewhat to the right of the line corresponding to an age of 4.6 billion years.

Published
1974

24. Absolute age of formation of chondrites studied by the 87Rb–87Sr method

Author

Minster, J-F., Birck, J-L., and Allègre, C. J.

Abstract

The 87Rb–87Sr isochrons for H-, E- and LL-, chondrites are undistinguishable from each other. The joint isochron yields an age of 4,498 ± 15 Myr if the rubidium decay constant λ 87Rb = 1.42×10−11yr−1, and a strontium initial ratio 87Rb/87Sr = 0.69885±0.00010. For the age to agree with U–Th–Pb data, λ 87Rb would have to be changed to 1.402±0.008×10−11yr−1

Published
1982
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25. The role of mantle fluid in formation of modern oceanic sulfide ore: Os isotope evidences

Author

Krymsky, R.S., Birck, J.-L., Belyatsky, B.V., Cherkashev, G.A., Stepanova, T.V., Sergeev, S.A., Institut de Physique du Globe de Paris (IPGP), and Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

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