Sediments beneath the Rainbow hydrothermal plume (Mid-Atlantic Ridge)
Mid-Atlantic Ridge, Rainbow hydrothermal field (36°14′N, about 2300 m), Océan Atlantique (eaux internationales)
Sediments
- Type
- Sediment
Hydrothermal field on serpentinised peridotites (fluids above 360 °C, rich in Fe, Cu, CH4 and H2). Cave et al. (2003): four cores 2, 5, 10 and 25 km down-plume; mixed-layer 187Os/188Os rises from 1.008 at 2 km to about 1.060 at 25 km, the seawater value, a sign of unradiogenic hydrothermal osmium in the plume. Published coordinates "36°14′N, 33°54′E": the longitude is actually west.
187Os/188Os isotope ratio, no unit Values of the same system
Standard : Rapport absolu, sans standard de référence
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| 1.0078 ± 0.0151 | 0.9821 / 1.0211 | 6 | sediment, mixed layer (0-10 cm), core 343 Mean and standard deviation recalculated from 6 analyses, 0.9821 to 1.0211 (1-2 cm 0.9975; 2-3 cm 1.0152; 2-3 cm (2) 1.0119; 4-5 cm 0.9821; 4-5 cm (2) 1.0211; 4-5 cm (3) 1.0187). Core 2 km from the vent field. Published mean 1.008 ± 0.015 (n = 6); vent-derived Os fraction estimated at 6.2 %; no sign of ultramafic detritus at these levels. | Cave et al. (2003), Deposition of osmium and other platinum-group elements beneath the ul… |
| 0.7384 ± 0.1768 | 0.4191 / 1.0014 | 10 | sediment below the mixed layer (16-40 cm), core 343 Mean and standard deviation recalculated from 10 analyses, 0.4191 to 1.0014 (16-17 cm 1.0014; 23-24 cm 0.5972; 23-24 cm (2) 0.6161; 25-26 cm 0.6036; 29-30 cm 0.4191; 31-32 cm 0.8387; 37-38 cm 0.8542; 37-38 cm (2) 0.8973; 37-38 cm (3) 0.8296; 39-40 cm 0.7263). Core 2 km from the vent field. Levels chosen to include horizons with ultramafic fragments; minimum at 29-30 cm (0.4191, Ir 275 pg/g). | Cave et al. (2003), Deposition of osmium and other platinum-group elements beneath the ul… |
| 0.1255 | 1 | serpentinite fragment, core 343 Single analysis (fragment). Core 2 km from the vent field. Os 1272 pg/g; near-chondritic Pt/Ir. | Cave et al. (2003), Deposition of osmium and other platinum-group elements beneath the ul… | |
| 1.0001 ± 0.043 | 0.9537 / 1.0387 | 3 | sediment, mixed layer (0-10 cm), core 316 Mean and standard deviation recalculated from 3 analyses, 0.9537 to 1.0387 (0-1 cm (2) 1.0387; 2-3 cm 0.9537; 6-7 cm 1.0078). Core 5 km from the vent field. Published mean 1.000 ± 0.043 (n = 3), without the first 0-1 cm analysis (0.5032), loaded with ultramafic detritus. | Cave et al. (2003), Deposition of osmium and other platinum-group elements beneath the ul… |
| 0.5032 | 1 | surface sediment with ultramafic detritus (0-1 cm), core 316 Single analysis (0-1 cm). Core 5 km from the vent field. Ir 439 pg/g and Pt 6543 pg/g; the replicate of the same powder gives 1.0387: the heterogeneity comes from the fragments. | Cave et al. (2003), Deposition of osmium and other platinum-group elements beneath the ul… | |
| 0.5835 ± 0.3535 | 0.2719 / 0.9676 | 3 | sediment below the mixed layer (20-26 cm), core 316 Mean and standard deviation recalculated from 3 analyses, 0.2719 to 0.9676 (20-21 cm 0.5110; 22-23 cm 0.2719; 25-26 cm 0.9676). Core 5 km from the vent field. 20-21 and 22-23 cm rich in Ir (223 and 410 pg/g), 25-26 cm close to seawater. | Cave et al. (2003), Deposition of osmium and other platinum-group elements beneath the ul… |
| 0.2213 ± 0.0817 | 0.1635 / 0.2791 | 2 | serpentinite and sulphide fragments, core 316 Mean and standard deviation recalculated from 2 analyses, 0.1635 to 0.2791 (fragment 0.2791; fragment (2) 0.1635). Core 5 km from the vent field. Os 442 and 1588 pg/g. | Cave et al. (2003), Deposition of osmium and other platinum-group elements beneath the ul… |
| 1.0528 ± 0.0149 | 1.039 / 1.0701 | 5 | sediment (0-17 cm), core 325 Mean and standard deviation recalculated from 5 analyses, 1.0390 to 1.0701 (0-1 cm 1.0450; 2-3 cm 1.0390; 8-9 cm 1.0420; 12-13 cm 1.0678; 16-17 cm 1.0701). Core 10 km from the vent field. Mixed layer (0-9 cm): published mean 1.042 ± 0.003 (n = 3), 2 to 3 % below seawater with no ultramafic detritus, hence a hydrothermal source of unradiogenic osmium; 12-17 cm at 1.068-1.070. | Cave et al. (2003), Deposition of osmium and other platinum-group elements beneath the ul… |
| 1.0612 ± 0.0047 | 1.0576 / 1.069 | 5 | sediment (0-17 cm), core 329 Mean and standard deviation recalculated from 5 analyses, 1.0576 to 1.0690 (0-1 cm 1.0614; 2-3 cm 1.0600; 4-5 cm 1.0576; 12-13 cm 1.0578; 16-17 cm 1.0690). Core 25 km from the vent field. Mixed layer (0-5 cm): published mean 1.060 ± 0.002 (n = 3), equal to seawater; highest Os burial flux of the four cores (0.407 ng/cm²/kyr). | Cave et al. (2003), Deposition of osmium and other platinum-group elements beneath the ul… |
Deposits of the same type
- NE Atlantic background carbonate sediments (core 23#12M) Océan Atlantique (eaux internationales)
- Cajarc reservoir on the Lot France
- Riou Mort downstream of the Viviez plant France
- Riou Mort and Riou Viou upstream of the Viviez plant France
- Marcenac reservoir on the Lot (reference) France
- Present-day Gardon sediments (main stream, November 2011) France
- Gardon mining tributary sediments (November 2011) France
- Natural Qaamarujuk fjord sediments (pre-mining) Greenland
Cite this page
IsoFind Atlas (2026). Sediments beneath the Rainbow hydrothermal plume (Mid-Atlantic Ridge), isotope signatures. https://www.isofind.tech/isotopes/en/sites/sediments-sous-le-panache-hydrothermal-de-rainbow-dorsale-medio-atlantique/ (accessed 2026-10-20).
@misc{isofind2026sedimentsbeneaththerainbowhyd,
title = {Sediments beneath the Rainbow hydrothermal plume (Mid-Atlantic Ridge), isotope signatures},
author = {{IsoFind Atlas}},
year = {2026},
url = {https://www.isofind.tech/isotopes/en/sites/sediments-sous-le-panache-hydrothermal-de-rainbow-dorsale-medio-atlantique/},
note = {Accessed 2026-10-20}
}Updated : 2026-10-20