scholarly journals Palladium and platinum in hydrothermal systems: The case of porphyry-Cu systems and sulfides associated with ophiolite complexes.

2016 ◽  
Vol 47 (4) ◽  
pp. 1618
Author(s):  
D.G. Eliopoulos ◽  
M. Economou-Eliopoulos
Keyword(s):  
Precious Metals ◽  
The Philippines ◽  
Hydrothermal Systems ◽  
Ophiolite Complex ◽  
Porphyry Deposits ◽  
Sea Floor ◽  
Porphyry Cu ◽  
Current State ◽  
Pge Mineralization ◽  
Mid Atlantic Ridge

Data on the Pt and Pd contents in sea-floor massive sulfides related to ophiolite complexes indicated elevated Pt contents, up to 1 wt % Pt in sulfides from East Pacific Rise, up to 1000 ppb Pd or Pt in sulfides from mid-Atlantic Ridge and the Pindos ophiolite complex (Greece). Recently, elevated levels of Pd and Pt, have been reported from mineralization associated with alkaline porphyry deposits, such as the Skouries porphyry deposit (Greece), Cordillera of British Columbia, Elatsite (Bulgaria), Santo Tomas II in the Philippines and elsewhere. Current state of knowledge on the solubility of platinum-group elements was applied on hydrothermal systems related to the mineralization in ophiolite complexes and porphyry Cu-Mo-Au±Pd±Pt deposits toward a better understanding of the PGE mineralization in hydrothermal systems and the unknown Pd and Pt potential in porphyry-Cu systems. Ore reserves, mineralogical and geochemical ore data for porphyry-Cu systems are considered to be an encouraging factor for the presence of precious metals. In particular, the occurrence of merenskyite (palladium telluride) associated with chalcopyrite, coupled with the experimental data indicate that porphyry systems are capable to transport significant amounts of Pd and Pt.

scholarly journals Genesis of Precious Metal Mineralization in Intrusions of Ultramafic, Alkaline Rocks and Carbonatites in the North of the Siberian Platform

Minerals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 354
Author(s):  
Anatoly M. Sazonov ◽  
Aleksei E. Romanovsky ◽  
Igor F. Gertner ◽  
Elena A. Zvyagina ◽  
Tatyana S. Krasnova ◽  
...  
Keyword(s):  
High Temperature ◽  
Siberian Platform ◽  
Precious Metal ◽  
Native Gold ◽  
Precious Metals ◽  
Ore Formation ◽  
Central Type ◽  
Alkaline Rocks ◽  
The North ◽  
Pge Mineralization

The gold and platinum-group elements (PGE) mineralization of the Guli and Kresty intrusions was formed in the process of polyphase magmatism of the central type during the Permian and Triassic age. It is suggested that native osmium and iridium crystal nuclei were formed in the mantle at earlier high-temperature events of magma generation of the mantle substratum in the interval of 765–545 Ma and were brought by meimechite melts to the area of development of magmatic bodies. The pulsating magmatism of the later phases assisted in particle enlargement. Native gold was crystallized at a temperature of 415–200 °C at the hydrothermal-metasomatic stages of the meimechite, melilite, foidolite and carbonatite magmatism. The association of minerals of precious metals with oily, resinous and asphaltene bitumen testifies to the genetic relation of the mineralization to carbonaceous metasomatism. Identifying the carbonaceous gold and platinoid ore formation associated genetically with the parental formation of ultramafic, alkaline rocks and carbonatites is suggested.

scholarly journals Mineralogical and Geochemical Constraints on the Origin of Mafic–Ultramafic-Hosted Sulphides: The Pindos Ophiolite Complex

Minerals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 454 ◽  
Author(s):  
Demetrios G. Eliopoulos ◽  
Maria Economou-Eliopoulos ◽  
George Economou ◽  
Vassilis Skounakis
Keyword(s):  
Hydrothermal Alteration ◽  
Hydrothermal Systems ◽  
Ophiolite Complex ◽  
Magmatic Origin ◽  
Magnetite Ore ◽  
Sulphide Ores ◽  
Mineralogical Characteristics ◽  
Tectonic Contact ◽  
Geochemical Constraints ◽  
Complete Transformation

Sulphide ores hosted in deeper parts of ophiolite complexes may be related to either primary magmatic processes or links to hydrothermal alteration and metal remobilization into hydrothermal systems. The Pindos ophiolite complex was selected for the present study because it hosts both Cyprus-type sulphides (Kondro Hill) and Fe–Cu–Co–Zn sulphides associated with magnetite (Perivoli-Tsoumes) within gabbro, close to its tectonic contact with serpentinized harzburgite, and thus offers the opportunity to delineate constraints controlling their origin. Massive Cyprus-type sulphides characterized by relatively high Zn, Se, Au, Mo, Hg, and Sb content are composed of pyrite, chalcopyrite, bornite, and in lesser amounts covellite, siegenite, sphalerite, selenide-clausthalite, telluride-melonite, and occasionally tennantite–tetrahedrite. Massive Fe–Cu–Co–Zn-type sulphides associated with magnetite occur in a matrix of calcite and an unknown (Fe,Mg) silicate, resembling Mg–hisingerite within a deformed/metamorphosed ophiolite zone. The texture and mineralogical characteristics of this sulphide-magnetite ore suggest formation during a multistage evolution of the ophiolite complex. Sulphides (pyrrhotite, chalcopyrite, bornite, and sphalerite) associated with magnetite, at deeper parts of the Pindos (Tsoumes), exhibit relatively high Cu/(Cu + Ni) and Pt/(Pt + Pd), and low Ni/Co ratios, suggesting either no magmatic origin or a complete transformation of a preexisting magmatic assemblages. Differences recorded in the geochemical characteristics, such as higher Zn, Se, Mo, Au, Ag, Hg, and Sb and lower Ni contents in the Pindos compared to the Othrys sulphides, may reflect inheritance of a primary magmatic signature.

Active and relict sea-floor hydrothermal mineralization at the TAG hydrothermal field, Mid-Atlantic Ridge

1993 ◽  
Vol 88 (8) ◽  
pp. 1989-2017 ◽  
Author(s):  
Peter A. Rona ◽  
Mark D. Hannington ◽  
C. V. Raman ◽  
Geoffrey Thompson ◽  
Margaret K. Tivey ◽  
...  
Keyword(s):  
Hydrothermal Field ◽  
Sea Floor ◽  
Hydrothermal Mineralization ◽  
Mid Atlantic Ridge ◽  
Tag Hydrothermal Field

Fluid evolution in submarine magma-hydrothermal systems at the Mid-Atlantic Ridge

1993 ◽  
Vol 98 (B11) ◽  
pp. 19579-19596 ◽  
Author(s):  
Deborah S. Kelley ◽  
Kathryn M. Gillis ◽  
Geoff Thompson
Keyword(s):  
Hydrothermal Systems ◽  
Fluid Evolution ◽  
Mid Atlantic Ridge

Thermohaline multi-phase simulations of vent fluid salinity evolution following a diking event at East Pacific Rise

2020 ◽  
Author(s):  
Falko Vehling ◽  
Jörg Hasenclever ◽  
Lars Rüpke
Keyword(s):  
Phase Separation ◽  
Numerical Model ◽  
Oceanic Crust ◽  
Vapor Phase ◽  
Numerical Models ◽  
East Pacific Rise ◽  
Hydrothermal Systems ◽  
Low Salinity ◽  
East Pacific ◽  
Mid Atlantic Ridge

<p>Submarine hydrothermal systems sustain unique ecosystems, affect global-scale biogeochemical ocean cycles, and mobilize metals from the oceanic crust to form volcanogenic massive sulfide deposits. Quantifying these processes requires linking seafloor observations to physico-chemical processes at depth and this is where numerical models of hydrothermal circulation can be particularly useful. One region where sufficient data is available to establish such a link is the East Pacific Rise (EPR) at 9°N, where vent fluid salinity and temperature have been repeatedly measured over a long time period. Here, large salinity and temperature changes of vents at the axial graben have been correlated with diking events and extrusive lava flows. Salinity changes imply the phase separation of seawater into a high-salinity brine and a low-salinity vapor phase. The intrusion of a new dike is likely to result in a characteristic salinity signal over several years: first the low salinity vapor phase rises and later the brine phase appears along with a decreasing vent temperature. These short-term salinity variations are super-imposed on the background salinity signal, which is modulated by phase separation phenomena on top of the axial magma lens. </p><p>From these variations, numerical models can help to infer sub-surface properties and processes such as permeability, background flow rates, and brine retention as well as mobilization – if the employed model can resolve the complexity of phase separation. We here present a novel numerical model for saltwater hydrothermal systems, which uses the Finite Volume Method on unstructured meshes and the Newton-Raphson Method for solving the coupled equations. We use this new 2-D model to investigate a setup that mimics hydrothermal convection on top of the axial magma lens, which is then perturbed by a dike intrusion. In a comprehensive suite of model runs, we have identified the key controls on the time evolution of vent fluid salinity following the diking event. Based on these insights, we can reproduce time-series data from the EPR at 9°N and infer likely ranges of rock properties for the oceanic crust layer 2B. </p><p>Our work shows how useful data integration into numerical hydrothermal models is. Unfortunately, data collection like mapping of magmatic events, continuous measurements of hydrothermal vent fluids or crustal drilling are very expensive and technically challenging. Here global and transdisciplinary collaboration would be very useful for achieving data with maximal benefit for all disciplines. Compared to the EPR the Mid-Atlantic Ridge shows a higher geological complexity, due to its lower spreading rate, and a higher diversity of vent fluid chemistry, but less continuous data is available, which hampers research using numerical models here for now. Therefore, numerical case studies at EPR serve as important validity checks for our numerical model and indicate where it has to be enhanced for quantifying processes related to hydrothermal systems at Mid-Atlantic Ridge.     </p>

Archaean precious-metal hydrothermal systems, Dome Mine, Abitibi Greenstone Belt. I. Patterns of alteration and metal distribution

1979 ◽  
Vol 16 (3) ◽  
pp. 421-439 ◽  
Author(s):  
B. J. Fryer ◽  
R. Kerrich ◽  
R. W. Hutchinson ◽  
M. G. Peirce ◽  
D. S. Rogers
Keyword(s):  
Greenstone Belt ◽  
Precious Metals ◽  
Hydrothermal Systems ◽  
Tectonic Deformation ◽  
Hydrothermal Quartz ◽  
Abitibi Greenstone Belt ◽  
Two Stages ◽  
Host Rocks ◽  
Chemical Sediments ◽  
Gold Bearing

The Porcupine District, Abitibi Greenstone Belt is one of the most extensive areas of Archaean auriferous mineralization. At least two stages of lode gold emplacement may be recognized. The first involves gold-bearing ferroan dolomite layers with subordinate chert, sulphides, and graphite deposited as laterally extensive chemical sediments at interflow horizons within the mafic volcanic sequence. The second stage is represented by major gold-bearing hydrothermal quartz–albite–dravite veins which transect diverse host rocks including the carbonate chemical sediments. Differences between gold-bearing chemical sediment and auriferous hydrothermal veins, in terms of texture, mineralogy, and nature of inclusions, together with considerations of chemistry are not compatible with local derivation of veins from enveloping chemical sediments or adjacent host rocks. The chemical sediments display slump structures and predate all tectonic deformation. In general, auriferous hydrothermal quartz veins transect bedding and/or schistosity, and are at a low state of internal strain. They appear to have been emplaced late during the second regional fold episode.Au, Ag, and Pd average 10, 2, and 0.1 ppm respectively in ore types at the Dome mine; representing concentration factors of 10 000,40, and 10 times background values in unmineralized metabasalt, and primary igneous rocks worldwide. Au and Ag are inhomogeneously distributed.Mineralized metabasic rocks adjacent to vein stockworks have Ti/Zr and Ti/Al2O3 ratios comparable to tholeiitic basalts, but display variable enrichment or depletion of silica, systematic depletion in Na2O, and where intensely altered significant extraction of calcium. The low Ni and Cr contents of the carbonate layers, together with low Ti/Zr ratios (43–78) of the carbonates and their enveloping mafic schists, are not consistent with the hypothesis that these auriferous rocks are carbonated ultramafics. Massive banded quartz–fuchsite–dravite veins have Cr and Ni abundances averaging 350 ppm, implying hydrothermal transport of these elements. Ti/Zr ratios of 120, together with high Mg, Cr, and Ni abundances in magnesite–dolomite–quartz– chlorite schists which host the banded veins are compatible with a primary komatiitic composition. Mineralized metabasic rocks are reduced (Fe2+/ΣFe = 0.9) relative to rocks with primary background abundances of precious metals (Fe2+/ΣFe = 0.7). This change of oxidation state implies that large volumes of reducing hydrothermal solutions were involved in vein mineralization.

Composition and evolution of PGE mineralization in chromite ores from the Il’chir ophiolite complex (Ospa–Kitoi and Khara-Nur areas, East Sayan)

2014 ◽  
Vol 55 (2) ◽  
pp. 259-272 ◽  
Author(s):  
O.N. Kiseleva ◽  
S.M. Zhmodik ◽  
B.B. Damdinov ◽  
L.V. Agafonov ◽  
D.K. Belyanin
Keyword(s):  
Ophiolite Complex ◽  
Pge Mineralization
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