Fig 1
Sketch map of Pobeda sulfide cluster. A – Position of the Pobeda cluster at the Mid-Atlantic Ridge. B – Bathymetric map showing locations of the three fields on an eastern flank of a rift valley. C – Detailed scheme with the sampling stations locations.
Fig 2
Textural relationships of the major sulfide minerals. A – Porous massive pyrite ores. B – Chalcopyrite and sphalerite intergrowths and late pyrite infilling interstitial space. C – Chalcopyrite replaced by late covellite and early pyrite. D – Abundant non-sulfide minerals in the interstitial space of massive sulfide samples. E – Zonal texture around the conduit: sphalerite-pyrite (Py-1) overgrown by fine-grained pyrite (Py-2) showing close to simultaneous precipitation. Py – pyrite, Po – pyrrhotite, Cpy – chalcopyrite, Sph – sphalerite, Cv – covellite, Chl – chlorite, Tlc – talc.
Table 1
Mineralogical composition of massive sulfides from the Pobeda-1 and -2 hydrothermal fields (XRD analysis).
| № field | № sample | Minerals, (%) |
|---|---|---|
| 195-2 | Pyrite (77.8), marcasite (19.5), aragonite (<1) | |
| 195-3 | Pyrite (91.8), marcasite (5.2), goethite (3.1) | |
| 196-1-1 | Pyrite (>99) | |
| 196-1 | Pyrite (63), marcasite (31), aragonite (<5) | |
| Pobeda-1 | 196-2 | Pyrite (75.7), marcasite (21.2), pyrrhotite (2.6), |
| chalcopyrite (<1) | ||
| 196-3 | Pyrite (95), goethite (5) | |
| 204-2-1 | Pyrite (99) | |
| 204-3 | Pyrite (99.8) | |
| 107-4 | Chalcopyrite (50), sphalerite (25), pyrite (25) | |
| 107-8 | Pyrite (87.9), marcasite (9.5), calcite (<1) | |
| 107-10-1 | Pyrite (99.0), quartz (<1) | |
| Pobeda-2 | ||
| 107-11-1 | Pyrite (81.1), sphalerite (10.3), chalcopyrite (2.8), covellite (2.5), calcite (2.5) | |
| 107-11-2 | Pyrite (>99) | |
| 245-3 | Pyrite (89.9), marcasite (9.6) |
Table 2
Results of the radiochemical analyses and 230Th/U ages (both 1 sigma) of the sulfide samples from the Pobeda hydrothermal cluster.
| 238U | 234U | 230Th | 232Th | ||||
|---|---|---|---|---|---|---|---|
| № sample | 230Th/234U | 234U/238U | Age, kyr | ||||
| dpm/g* | |||||||
| Pobeda-1 | |||||||
| 195-2** | 10.787±0.371 | 12.232±0.412 | 2.266±0.083 | bdl | 0.185±0.009 | 1.134±0.031 | 22.1±1.2 |
| 195-3** | 30.767±0.587 | 35.059±0.663 | 4.436±0.163 | bdl | 0.127±0.005 | 1.140±0.010 | 14.6±0.7 |
| 196-1 | 9.660±0.252 | 10.909±0.279 | 0.033±0.008 | bdl | 0.003±0.001 | 1.129±0.023 | 0.33±0.08 |
| 196-1-1 | 8.113±0.216 | 9.033±0.236 | 0.022±0.011 | bdl | 0.002±0.001 | 1.113±0.024 | 0.27±0.13 |
| 196-2 | 5.511±0.133 | 6.373±0.149 | 0.017±0.006 | bdl | 0.003±0.001 | 1.156±0.025 | 0.28±0.10 |
| 196-3** | 38.093±0.970 | 42.665±1.079 | 2.480±0.075 | bdl | 0.058±0.002 | 1.120±0.014 | 6.5±0.3 |
| 204-2-1 | 3.615±0.124 | 4.099±0.136 | 1.584±0.076 | bdl | 0.387±0.023 | 1.134±0.036 | 52.0±4.0 |
| 204-3** | 3.409±0.153 | 4.419±0.185 | 1.695±0.046 | bdl | 0.384±0.019 | 1.296±0.058 | 51.4±3.4 |
| Pobeda-2 | |||||||
| 107-4 | 0.134±0.011 | 0.175±0.013 | 0.051±0.008 | bdl | 0.294±0.051 | 1.302±0.135 | 37.2±8.1 |
| 107-8 | 4.119±0.186 | 5.085±0.214 | 0.198±0.029 | 0.035±0.015 | 0.039±0.006 | 1.235±0.067 | 4.30±0.68 |
| 107-10-1 | 7.643±0.240 | 8.727±0.269 | 5.562±0.236 | bdl | 0.637±0.033 | 1.142±0.025 | 107.0±10.0 |
| 107-11-1 | 113.800±2.635 | 130.525±3.014 | 5.668±0.138 | bdl | 0.043±0.001 | 1.147±0.007 | 4.81±0.17 |
| 107-11-2 | 79.639±1.710 | 91.650±1.961 | 4.102±0.114 | bdl | 0.045±0.002 | 1.151±0.008 | 4.96±0.18 |
| 245-3 | 10.072±0.248 | 11.585±0.279 | 0.883±0.035 | bdl | 0.076±0.004 | 1.150±0.021 | 8.59±0.41 |
** – radioisotope data and age of massive sulfide samples from Gablina et al. 2018.
** – radioisotope data and age of massive sulfide samples from Gablina et al. 2018.
** – radioisotope data and age of massive sulfide samples from Gablina et al. 2018.
** – radioisotope data and age of massive sulfide samples from Gablina et al. 2018.
Fig 3
230Th/U age vs 234U-specific activity for ore samples of the Pobeda sulfide cluster.
Fig 4
The ages of massive sulfides at Pobeda-1 and Pobeda-2 hydrothermal fields.
Table 3
The age of massive sulfide from Pobeda hydrothermal cluster.
| № sample | Age, kyr | |
|---|---|---|
| Pobeda-1 | ||
| 195-2* | 22.1±1.2 | |
| 195-3* | 14.6±0.7 | |
| 196-1 | 0.33±0.08 | |
| 196-1-1 | 0.27±0.13 | |
| 196-2 | 0.28±0.10 | |
| 196-3* | 6.5±0.3 | |
| 204-2-1 | 52.0±4.0 | |
| 204-3* | 51.4±3.4 | |
| Pobeda-2 | ||
| 107-4 | 37.2±8.1 | |
| 107-8 | 4.3±0,7 | |
| 107-10-1 | 107.0±10.0 | |
| 107-11-1 | 4.81±0.17 | |
| 107-11-2 | 4.96±0.18 | |
| 245-3 | 8.59±0.41 | |
[i] Note: the composition of analyzed sample: italic – bulk composition; bold – monomineral and sulfide intergrowths; (*) – age of massive sulfide samples from Gablina et al. 2018.