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Chronology of seafloor massive sulfides formation within the Pobeda hydrothermal cluster (Mid-Atlantic Ridge)

V. Kuznetsov
V. Kuznetsov
, 
G. Cherkashov
G. Cherkashov
, 
K. Kuksa
K. Kuksa
, 
A. Firstova
A. Firstova
, 
F. Maksimov
F. Maksimov
, 
V. Bel’Tenev
V. Bel’Tenev
, 
L. Lazareva
L. Lazareva
, 
S. Levchenko
S. Levchenko
 y 
N. Baranova
N. Baranova
   | 31 dic 2020
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Article Category: Regular Articles
Publicado en línea: 31 dic 2020
Páginas: 63 - 70
Recibido: 27 dic 2019
Aceptado: 28 ago 2020
DOI: https://doi.org/10.2478/geochr-2020-0019
Palabras clave
© 2020 V. Kuznetsov., published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

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.
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.
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.

Fig 3

230Th/U age vs 234U-specific activity for ore samples of the Pobeda sulfide cluster.
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.
The ages of massive sulfides at Pobeda-1 and Pobeda-2 hydrothermal fields.

Mineralogical composition of massive sulfides from the Pobeda-1 and -2 hydrothermal fields (XRD analysis).

№ field№ sampleMinerals, (%)
195-2Pyrite (77.8), marcasite (19.5), aragonite (<1)
195-3Pyrite (91.8), marcasite (5.2), goethite (3.1)
196-1-1Pyrite (>99)
196-1Pyrite (63), marcasite (31), aragonite (<5)
Pobeda-1196-2Pyrite (75.7), marcasite (21.2), pyrrhotite (2.6),
chalcopyrite (<1)
196-3Pyrite (95), goethite (5)
204-2-1Pyrite (99)
204-3Pyrite (99.8)
107-4Chalcopyrite (50), sphalerite (25), pyrite (25)
107-8Pyrite (87.9), marcasite (9.5), calcite (<1)
107-10-1Pyrite (99.0), quartz (<1)
Pobeda-2
107-11-1Pyrite (81.1), sphalerite (10.3), chalcopyrite (2.8), covellite (2.5), calcite (2.5)
107-11-2Pyrite (>99)
245-3Pyrite (89.9), marcasite (9.6)

The age of massive sulfide from Pobeda hydrothermal cluster.

№ sampleAge, kyr
Pobeda-1
195-2*22.1±1.2
195-3*14.6±0.7
196-10.33±0.08
196-1-10.27±0.13
196-20.28±0.10
196-3*6.5±0.3
204-2-152.0±4.0
204-3*51.4±3.4
Pobeda-2
107-437.2±8.1
107-84.3±0,7
107-10-1107.0±10.0
107-11-14.81±0.17
107-11-24.96±0.18
245-38.59±0.41

Results of the radiochemical analyses and 230Th/U ages (both 1 sigma) of the sulfide samples from the Pobeda hydrothermal cluster.

238U234U230Th232Th
№ sample230Th/234U234U/238UAge, kyr
dpm/g

dpm – decays per minute per gram, bdl – below detection limit

Pobeda-1
195-2

– radioisotope data and age of massive sulfide samples from Gablina et al. 2018.

10.787±0.37112.232±0.4122.266±0.083bdl0.185±0.0091.134±0.03122.1±1.2
195-3

– radioisotope data and age of massive sulfide samples from Gablina et al. 2018.

30.767±0.58735.059±0.6634.436±0.163bdl0.127±0.0051.140±0.01014.6±0.7
196-19.660±0.25210.909±0.2790.033±0.008bdl0.003±0.0011.129±0.0230.33±0.08
196-1-18.113±0.2169.033±0.2360.022±0.011bdl0.002±0.0011.113±0.0240.27±0.13
196-25.511±0.1336.373±0.1490.017±0.006bdl0.003±0.0011.156±0.0250.28±0.10
196-3

– radioisotope data and age of massive sulfide samples from Gablina et al. 2018.

38.093±0.97042.665±1.0792.480±0.075bdl0.058±0.0021.120±0.0146.5±0.3
204-2-13.615±0.1244.099±0.1361.584±0.076bdl0.387±0.0231.134±0.03652.0±4.0
204-3

– radioisotope data and age of massive sulfide samples from Gablina et al. 2018.

3.409±0.1534.419±0.1851.695±0.046bdl0.384±0.0191.296±0.05851.4±3.4
Pobeda-2
107-40.134±0.0110.175±0.0130.051±0.008bdl0.294±0.0511.302±0.13537.2±8.1
107-84.119±0.1865.085±0.2140.198±0.0290.035±0.0150.039±0.0061.235±0.0674.30±0.68
107-10-17.643±0.2408.727±0.2695.562±0.236bdl0.637±0.0331.142±0.025107.0±10.0
107-11-1113.800±2.635130.525±3.0145.668±0.138bdl0.043±0.0011.147±0.0074.81±0.17
107-11-279.639±1.71091.650±1.9614.102±0.114bdl0.045±0.0021.151±0.0084.96±0.18
245-310.072±0.24811.585±0.2790.883±0.035bdl0.076±0.0041.150±0.0218.59±0.41
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