Formation of ferrian chromite in podiform chromitites from the Golyamo Kamenyane serpentinite, Eastern Rhodopes, SE Bulgaria: a two-stage process

Gervilla, Fernando; Padrón‐Navarta, José Alberto; Kerestedjian, Thomas; Sergeeva, Ivanina; Gonzáléz-Jiménez, José María; Fanlo, Isabel

doi:10.1007/s00410-012-0763-3

Cited by 118 publications

(149 citation statements)

References 37 publications

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“…Gervilla et al (2012) [61] showed that between 550 and 700 • C (depending on pressure), the infiltration of water into chromitites might promote the reaction of primary chromite with matricial olivine to produce chlorite in equilibrium with "secondary" chromite residually enriched in Cr and Fe 2+ (ferrous chromite). According to these authors, this reaction produces~43% loss of the mass of chromite that is not compensated by modification of the initial size of the chromite grain, but by the development of a spongy or porous texture in the ferrous chromite.…”

Section: Thermometric Considerations and Oxidation Evaluationmentioning

confidence: 99%

Following the Amphibolite to Greenschist Metamorphic Path through the Structural Parameters of Spinels from Amsaga (Mauritania)

et al. 2018

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Abstract:We investigated the crystal and structural behavior of several Cr-bearing spinels from the Archean chromitites of Amsaga (Mauritania). The chemical and structural data testified a retrograde metamorphism from amphibolite to greenschist facies, witnessed by relative changes in the amount of all the major oxides (Cr, Al, Mg, Fe 2+ , Fe 3+ ), the relative proportion of Fe 3+ /Fe tot as well as the structural parameters, including the cell edge and the oxygen coordinate. The general agreement between electron microprobe and Mössbauer data indicates that the analyzed spinels are stoichiometric. The structural data revealed that the oxygen positional parameter of amphibole-bearing samples is the highest observed among Cr-bearing spinels with similar Cr# and Mg#. Consequently, it is suggested that a structural study of detrital Cr-spinels could be important in discriminating an amphibole-chromitite source from an ophiolite source.

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Section: Thermometric Considerations and Oxidation Evaluationmentioning

confidence: 99%

Following the Amphibolite to Greenschist Metamorphic Path through the Structural Parameters of Spinels from Amsaga (Mauritania)

et al. 2018

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“…The normally zoned Cr-spinels have been reported in ophiolites [10], layered mafic-ultramafic complexes [11], komatiites [12], mantle xenoliths [13,14], and metamorphosed ultramafic massifs [15]. Their formation is generally ascribed to high temperature hydrothermal alteration [16] or metamorphism [15,17], evidenced by the presence of secondary phases such as chlorite and antigorite surrounding the Cr-spinel or relict magnetite [15,18,19].…”

Section: Introductionmentioning

confidence: 99%

Origin of Reverse Zoned Cr-Spinels from the Paleoproterozoic Yanmenguan Mafic–Ultramafic Complex in the North China Craton

Bai

Xiao

et al. 2018

Minerals

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Abstract:We conducted petrological and mineral chemistry investigations of Cr-spinel in ultramafic rocks of the Yanmenguan mafic-ultramafic complex in the North China Craton. The Cr-spinel grains occur as inclusions in enstatite, tschermakite, phlogopite, and olivine, or as interstitial grains among the aforementioned silicate minerals, and show concentric or asymmetrical textures. Back-scattered electron and elemental images and compositional profiles of the spinel grains indicate the presence of Cr-and Fe-rich cores and Al-and Mg-rich rims. The host silicate minerals display a decrease in Al and Mg contents accompanied by an increase in Cr and Fe away from the spinel. These textures and compositional variations suggest that subsolidus elemental exchange more likely gave rise to the compositional zonation, resulting in the transfer of Al and Mg from the silicate minerals to the spinel. The Mn, Ni, and Ti contents in spinel and the major elements of olivine-hosted spinel are relatively stable during subsolidus elemental diffusion and thus are more reliable tracers of primary high-temperature processes. The temperature estimates reveal that the subsolidus diffusion might have occurred at 600-720 • C, which could be linked to the regional metamorphic event.

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“…Mellini et al 2005;Mikuš & Spišiak 2007;Farahat 2008;González-Jiménez et al 2009;Merlini et al 2009;Gervilla et al 2012;Singh & Singh 2013). According to Bach et al (2006) common low-T serpentinization, taking place during ocean-floor metamorphism cannot cause any changes in Cr-spinel composition.…”

Section: Origin Of Zoning In Cr-spinel: Implications For the Postmagmmentioning

confidence: 99%

“…Their slight Fe 3+ enrichment suggests the local passage to relatively more oxidizing alteration conditions. Gervilla et al (2012) formed during the greenschist facies metamorphism (Fig. 6).…”

Section: Geologicamentioning

confidence: 99%

“…More specifically, textural observations and mineral chemistry data indicate that hydrothermal alteration and metamorphism can significantly modify primary Cr-spinel composition (e.g. Bliss & MacLean 1975;Evans & Frost 1975;Wylie et al 1987;Kimball 1990;Suita & Streider 1996;Barnes 2000;Mellini et al 2005;Farahat 2008;Merlini et al 2009;Rollinson et al 2012;Sansone et al 2012 ', Spangenberg 1943;and cited in, among others, Evans & Frost 1975;González-Jiménez et al 2009;Mukherjee et al 2010;Gervilla et al 2012;Derbyshire et al 2013). Various investigations suggest that ferrian chromite forms during low-T hydrothermal alteration (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Composition and alteration of Cr-spinels from Milia and Pefki serpentinized mantle peridotites (Pindos Ophiolite Complex, Greece)

Kapsiotis¹

2014

Geologica Carpathica

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The Pindos Ophiolite rocks include variably serpentinized peridotites derived from a harzburgitic and subordinately dunitic mantle. In the serpentinized matrix of these rocks pseudomorphic (mesh, bastite) and non-pseudomorphic (interpenetrating, type-2 hourglass) textures were recognized. Chromian spinel (Cr-spinel) is anhedral to subhedral and often replaced by a porous opaque phase. Chemistry data show that Cr-spinel cores retain their original composition, having Cr#[Cr/(Cr + Al)] that ranges between 0.45 and 0.73, and Mg#[Mg/(Mg + Fe2+)] that varies between 0.52 and 0.65, accompanied by low content in TiO2 ( < 0.11wt. %). The relatively wide variation of their Cr# values reflects that the studied peridotites were produced by variable degrees of melting. It is likely that the Pindos peridotites represent mantle residues originally formed in a mid-ocean ridge (MOR) environment, which were subsequently entrapped as part of a mantle wedge above a supra-subduction zone (SSZ) regime. Cr-spinel adjacent to clinochlore systematically displays limited compositional and textural zoning along grain boundaries and fractures. However, the degree of peridotite serpentinization does not correlate with the abundance of zoning effects in accessory Cr-spinel. Thus, Cr-spinel zoning is thought to represent a secondary feature obtained during the metamorphic evolution of the host peridotites. Core to rim compositional trends are expressed by MgO and Al2O3 impoverishment, mainly compensated by Cr2O3 and FeO increases. Such chemical trends are produced as a result of Cr-spinel re-equilibration with the surrounding serpentine, and their subsequent replacement by ferrian (Fe3+-rich) chromite and clinochlore, respectively, during a brief, fluid assisted, greenschist facies metamorphism episode (T > 300 °C). The limited occurrence of ferrian chromite with high Fe3+# values suggests that elevated oxidizing conditions were prevalent only on a local scale during Cr-spinel alteration

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Formation of ferrian chromite in podiform chromitites from the Golyamo Kamenyane serpentinite, Eastern Rhodopes, SE Bulgaria: a two-stage process

Cited by 118 publications

References 37 publications

Following the Amphibolite to Greenschist Metamorphic Path through the Structural Parameters of Spinels from Amsaga (Mauritania)

Following the Amphibolite to Greenschist Metamorphic Path through the Structural Parameters of Spinels from Amsaga (Mauritania)

Origin of Reverse Zoned Cr-Spinels from the Paleoproterozoic Yanmenguan Mafic–Ultramafic Complex in the North China Craton

Composition and alteration of Cr-spinels from Milia and Pefki serpentinized mantle peridotites (Pindos Ophiolite Complex, Greece)

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