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| Jean Baptiste, P; Fourre, E; Dapoigny, A; Charlou, Jean-luc; Donval, Jean-pierre. |
| As part of a multidisciplinary project aimed at studying mid-ocean ridge processes near the Azores, fifty water column profiles were analyzed for He-3/He-4 ratios in dissolved helium (a well-known hydrothermal tracer) from 36 degrees N to 40 degrees N along the Mid-Atlantic Ridge (MAR) and over the Azores Plateau. As expected, large delta(3) He anomalies could be observed over the Rainbow, Lucky Strike, and Menez Gwen hydrothermal sites. The main finding of the present study is the discovery of a large hydrothermal 3 He plume north of the Acor Fracture Zone (north AFZ site), with a CH4/He-3 ratio indicative of a basaltic-hosted hydrothermal system. Clear He-3 and CH4 anomalies, likely corresponding to unknown venting sites too, were also detected in the... |
| Tipo: Text |
Palavras-chave: Hydrothermal processes; Helium 3; Mid ocean ridges. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-3876.pdf |
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| Jean-baptiste, P; Jenkins, Wj; Dutay, Jc; Fourre, E; Leboucher, V; Fieux, M. |
| Because of the high interannual and seasonal variability, transports from the various methods used to estimate the Indonesian throughflow encompass a large range of values. Here, we estimate a temporally integrated transport for the throughflow from comparison of the tritium water column inventory on both sides of the throughflow. Our approach is based on the simple idea that tritium, with a radioactive decay half-life of 12.32 yr, is well suited to infer the transit time ( and consequently the mass flow) of the waters through the Indonesian archipelago. We show that the tritium budget implies a flow of 8.6 +/- 4 Sv, corresponding to a transit time of 10.5 yr. This result, which represents an average over seasons and several ENSO and non-ENSO periods,... |
| Tipo: Text |
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| Ano: 2004 |
URL: https://archimer.ifremer.fr/doc/00228/33914/32215.pdf |
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| Fourre, E; Jean Baptiste, P; Charlou, Jean-luc; Donval, Jean-pierre; Ishibashi, J. |
| We present isotopic analysis of helium in hydrothermal fluids from the Manus back-arc basin, collected during the French-Japanese Manusflux and Manaute cruises in 1995 and 2000, respectively. The helium isotope composition of the fluids is comparable to that measured elsewhere in similar subduction environments, with He-3/He-4 values (7.4 to 7.9 R-a) slightly lower than typical MORB values, except on the Manus Spreading Center (MSC) where higher values (12 +/- 0.1 R-a) are observed. The causal link between the narrow spatial extent of the He-3/He-4 anomaly at the MSC and a He-3-rich deep mantle component remains elusive, based on available geophysical data. Thus, the Manus Spreading Center results may be an interesting example of small scale upper-mantle... |
| Tipo: Text |
Palavras-chave: Western Pacific; Manus Basin; Back arc basins; Hydrothermal fluids; Helium isotopes. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-4203.pdf |
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| Leboucher, V; Jean-baptiste, P; Fourre, E; Arnold, M; Fieux, M. |
| Results are presented of radiocarbon and tritium measurements along a transect between the Australian continental shelf and the Indonesian coast of Bali. The stations lie in the easternmost part of the Indian Ocean, close to the sills over which the Indonesian through flow (ITF) makes its way to the Indian Ocean. The present data, obtained as part of the JavaAustralia Dynamics Experiment (JADE) in August 1989, complement the WOCE C-14 and tritium data set on both sides of the Indonesian archipelago and give us the opportunity to discuss the origin of the water masses and timescale of the through flow. Both tracers point to a north equatorial Pacific origin of the waters. The comparison of the tritium inventories in the Pacific North Equatorial Current and... |
| Tipo: Text |
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| Ano: 2004 |
URL: https://archimer.ifremer.fr/doc/00228/33931/32312.pdf |
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