High PGE contents and extremely abundant PGE-minerals hosted in chromitites from the Veria ophiolite complex, northern Greece

Tsoupas, George; Economou-Eliopoulos, Maria

doi:10.1016/j.oregeorev.2006.10.008

Cited by 63 publications

(64 citation statements)

References 25 publications

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“…The more negative Gibbs free energy values for the RuO 2 compared to those for the RuS 2 , in the range of temperature lower than 500˝C (Table 4, Figure 5), seems to be in good agreement with the common transformation of laurite to oxides/hydroxides in small chromite occurrences [13,48], in placer deposits [49], in the oxidized zone of the Great Dyke of Zimbabwe layered intrusion [50], in laterite deposits [51][52][53] and elsewhere. The equilibrium constant for the transfer of an ion from one phase to another is directly related to Gibbs free energy and the partition coefficient, which are defined by the behavior of the elements.…”

Section: Application Of (∆ F G) Values To the Origin Of Pgmsupporting

confidence: 71%

“…Although the stability relationships between various phases can be studied using the experimental method, thermodynamics may give us an approach to the calculation of the Gibbs free energy and phase diagrams [28]. However, the requirements for the PGM stability and re-deposition remain still unclear, since the activity-composition models and relevant phase diagrams for PGM are very limited, and the PGM forming processes in natural systems are complicated [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]28].…”

Section: Application Of (∆ F G) Values To the Origin Of Pgmmentioning

confidence: 99%

“…Platinum groupelements (PGE) can be classified into two subgroups: the Os-, Ir-, Ru-rich or IPGE (more refractory) and PPGE (low-melting and more soluble) (Ir group), interpreted to reflect compatible behavior (partition or distribution coefficient between solid and magma, D ě 1) during large-degree mantle melting and (Pt, Pd)-rich or PPGE assemblages, reflecting the incompatible behavior (D ď 1) of the PPGE, showing enrichment as a function of the differentiation degree [1]. The behavior of PGE during partial melting and crystal fractionation and which minerals are collectors of PGEs have been investigated and reviewed extensively [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

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Gibbs Free Energy of Formation for Selected Platinum Group Minerals (PGM)

Olivotos

Economou-Eliopoulos

2016

Geosciences

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Thermodynamic data for platinum group (Os, Ir, Ru, Rh, Pd and Pt) minerals are very limited. The present study is focused on the calculation of the Gibbs free energy of formation (∆ f G˝) for selected PGM occurring in layered intrusions and ophiolite complexes worldwide, applying available experimental data on their constituent elements at their standard state (∆G = G (species)´∆ G (elements) ), using the computer program HSC Chemistry software 6.0. The evaluation of the accuracy of the calculation method was made by the calculation of (∆G f ) of rhodium sulfide phases. The calculated values were found to be in good agreement with those measured in the binary system (Rh + S) as a function of temperature by previous authors (Jacob and Gupta (2014). The calculated Gibbs free energy (∆ f G˝) followed the order RuS 2 < (Ir,Os)S 2 < (Pt, Pd)S < (Pd, Pt)Te 2 , increasing from compatible to incompatible noble metals and from sulfides to tellurides.

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Section: Application Of (∆ F G) Values To the Origin Of Pgmsupporting

confidence: 71%

Section: Application Of (∆ F G) Values To the Origin Of Pgmmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Gibbs Free Energy of Formation for Selected Platinum Group Minerals (PGM)

Olivotos

Economou-Eliopoulos

2016

Geosciences

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“…High PGE concentrations, reaching 25 ppm total PGE's (Os = 7400, Ir = 6020, Ru = 9700, Rh = 310, Pt = 760, Pd = 750, all in ppb) were determined in chromitites hosted in the Veria ophiolites, northern Greece [46,47]. These elevated PGE contents are associated with a great number (>100) of different PGM grains, mainly Os-Ru-Ir-Fe alloys, reaching 1 mm in size [47]. They are concentrated along a shear zone of strongly brecciated chromite ore.…”

Section: Platinum Group Elements (Pge)mentioning

confidence: 99%

Geological, Mineralogical and Geochemical Aspects for Critical and Rare Metals in Greece

Melfos

Voudouris

2012

Minerals

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Abstract:The European Union (EU) is highly dependent on critical and rare metals which are very important for a sustainable development. However, European industry is not able to cover its demands from native sources and it imports commodities from third countries. Greece is one of the EU countries with the most potential for supplying these strategic metallic raw materials in the future, since it hosts a large number of ore deposits. The epithermal-and porphyry-type deposits and the reduced intrusion related systems of the Serbomacedonian and the Rhodope metallogenic provinces in Northeastern Greece are promising targets for a future exploitation and exploration in Sb, Te, Mo, Re, Ga, In, REE and PGE. Greece is the leading producer of Ni and Al in the EU from laterites and bauxites of central and northern Greece. These deposits also contain significant amounts of Co or REE which should be considered in the future plans of the processing industries. REE are found in high contents at the placer deposits between Chalkidiki and Kavala (North Greece) and elevated PGE concentrations are associated with the chromitites of northwestern Greece. Therefore, the mineral wealth of Greece can contribute significantly to a sustainable and a competitive economy of Europe.

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“…These rocks extend throughout the area between Veria and Naousa towns and belong to the Almopias subzone of the Axios geotectonic zone, in northern Greece (Figure 1). They represent remnants of oceanic lithosphere which were thrust from one or more ocean basins and have been obducted onto Late Triassic-Jurassic platform carbonates of the Pelagonian Zone during Upper Jurassic to Lower Cretaceous [33][34][35][36][37]. The ophiolite is a dismembered suite and includes, from base to top, serpentinised lherzolite and harzburgite, intruded by a sparse network of pyroxenitic dykes, as well as gabbro, diabase and pillow basalt.…”

Section: Geological Settingmentioning

confidence: 99%

New Occurrence of Pyroxenites in the Veria-Naousa Ophiolite (North Greece): Implications on Their Origin and Petrogenetic Evolution

et al. 2017

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Abstract:The Veria-Naousa ophiolite represents a dismembered unit in north Greece, which includes variably serpentinised lherzolite and harzburgite, locally intruded by a sparse network of dykes or thin layers of websterite and olivine-orthopyroxenite composition. The websterite and the olivine-orthopyroxenite show abundant petrographic and geochemical evidence (relic olivines with mantle affinities, Cr-rich spinels, low Al 2 O 3 , depletions in incompatible elements, and concave upwards rare earth element patterns) that they comprise replacive bodies from refractory subarc mantle precursors. The occurrence of these pyroxenites in dykes implies that channelled percolation of melts account for their replacive character. High CaO/Al 2 O 3 , low Zr and crystallisation of diopside suggest that a melt of ankaramitic/carbonatitic composition percolated in lherzolite replacing porphyroclastic olivine and forming the pyroxenes in the websterite. At a shallower level, harburgites were impregnated by boninitic melts (inferred by U-shape rare earth element patterns and very rich in Cr spinels) triggering the replacement of porphyroclastic olivine by orthopyroxene for the formation of olivine-orthopyroxenite. These peritectic replacements of olivine commonly occur in a mantle wedge regime. The peculiar characteristics of the Veria-Naousa pyroxenites with LREE and compatible elements enrichments resemble the subarc pyroxenites of Cabo Ortegal implying a similar environment of formation. Whole-rock and mineralogical (spinel and clinopyroxene) compositions are also in favour of a backarc to arc environment. It is recommended that the evolution of the Veria-Naousa pyroxenites record the evolution of the subarc region and the opening of a backarc basin in a broad SSZ setting in the Axios Zone of eastern Greece.

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High PGE contents and extremely abundant PGE-minerals hosted in chromitites from the Veria ophiolite complex, northern Greece

Cited by 63 publications

References 25 publications

Gibbs Free Energy of Formation for Selected Platinum Group Minerals (PGM)

Gibbs Free Energy of Formation for Selected Platinum Group Minerals (PGM)

Geological, Mineralogical and Geochemical Aspects for Critical and Rare Metals in Greece

New Occurrence of Pyroxenites in the Veria-Naousa Ophiolite (North Greece): Implications on Their Origin and Petrogenetic Evolution

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