Platinum group minerals in ophiolitic chromitites from Tehuitzingo (Acatlán complex, southern Mexico): implications for post-magmatic modification

Zaccarini, Federica; Proenza, Joaquín A.; Ortega-Gutiérrez, Fernando; Garuti, Giorgio

doi:10.1007/s00710-005-0075-7

Cited by 78 publications

(64 citation statements)

References 21 publications

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“…Several recent mineralogical studies have shown that the primary PGM assemblages in chromitites can become unstable and modified when they are affected by low-temperature alteration (e.g., Stockman & Hlava 1984, Garuti & Zaccarini 1997, Zaccarini et al 2005, Ahmed & Economou-Eliopoulos 2008. These authors have shown that secondary processes can cryptically modify the composition of primary PGM, which leads to the formation of new PGM phases.…”

Section: Previous Work On the Pgm Of Milia Chromititesmentioning

confidence: 99%

“…If chromite crystallization is delayed, the chemical exchange of Os between laurite and the melt is further promoted, giving rise to the formation of zoned crystals of laurite. However, laurite grains with an Os-rich core and a Os-poor rim (reverse zoning) have been described in the literature (e.g., Barkov et al 2004, Gervilla et al 2005, Zaccarini et al 2005, González-Jiménez et al 2009). Two possible mechanisms have been proposed in the literature to explain the second type of compositional zoning of laurite.…”

Section: Origin Of the Inverse Zoning In Laurite And Conditions Of Almentioning

confidence: 99%

“…As an alternative, Zaccarini et al (2005) proposed that the commonly observed trend of Os increasing from core to rim does not represent the result of growth zoning due to an increase of the Os partition coefficient between silicate melt and laurite with decreasing T (Brenan & Andrews 2001). They suggested that during the postmagmatic stage, primary laurite can adjust its composition in response to the expected decrease of f(S 2 ).…”

Section: Origin Of the Inverse Zoning In Laurite And Conditions Of Almentioning

confidence: 99%

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Chromian Spinel Composition and Platinum-Group Element Mineralogy of Chromitites From the Milia Area, Pindos Ophiolite Complex, Greece

Kapsiotis

Grammatikopoulos

Tsikouras

et al. 2009

The Canadian Mineralogist

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The chromitites of the Milia area in the Pindos ophiolite complex, in Greece, were investigated for their platinum-group mineral (PGM) content. The chromitites are massive, more rarely disseminated in texture and occur as small pods. They are composed of magnesiochromite crystals with Cr# [Cr/(Cr + Al)] between 0.80 and 0.84, and Mg# [Mg/(Mg + Fe 2+ )] between 0.54 and 0.72. The total platinum-group-element (PGE) contents in chromitites are relatively low (≤170 ppb), although they may locally be higher (up to 1059 ppb). The IPGE (Os, Ir and Ru) predominate over the PPGE (Rh, Pt and Pd). The PGM assemblage, consistent with the geochemical data, is dominated by laurite and Os-Ir-Ru alloys that occur both as single and composite grains, generally less than 15 mm in size. Laurite has a wide range of Os-for-Ru substitution [Ru/(Ru + Os): 0.42-0.99], whereas primary alloys are enriched in Ru (up to 73.80 wt.%). Some laurite crystals exhibit an anomalous pattern of zoning. Such zoning requires an inversion of the normal T-f(S 2 ) trend in magmatic systems, and is herein considered to be due to postmagmatic processes. Some Ru-rich alloy grains contain relatively high Rh and Pt abundances, similar to those of residual sulfides in mantle peridotites. This feature suggests that these alloys may represent residual PGM phases from earlier episodes of melt extraction from the severely depleted mantle unit of the Pindos ophiolite complex. Combined compositional data indicate that the Milia chromitites formed from a hydrous boninitic melt in a suprasubduction-zone environment.Keywords: chromitites, platinum-group minerals (PGM), laurite, alloys, ophiolites, Pindos, Greece. Certains grains d'alliages riches en Ru contiennent des teneurs relativement élevées en Rh et Pt, tout comme les sulfures résiduels de péridotites du manteau. Ces grains d'alliage pourraient donc représenter des MGP résiduels après l'extraction antérieure de liquide silicaté, laissant un manteau très stérile dans le complexe ophiolitique de Pinde. Les données combinées sur la composition indiquent que les chromitites de Milia se sont formées à partir d'une magma hydraté boninitique dans un milieu au dessus de la zone de subduction.(Traduit par la Rédaction)

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Section: Previous Work On the Pgm Of Milia Chromititesmentioning

confidence: 99%

Section: Origin Of the Inverse Zoning In Laurite And Conditions Of Almentioning

confidence: 99%

Section: Origin Of the Inverse Zoning In Laurite And Conditions Of Almentioning

confidence: 99%

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Chromian Spinel Composition and Platinum-Group Element Mineralogy of Chromitites From the Milia Area, Pindos Ophiolite Complex, Greece

Kapsiotis

Grammatikopoulos

Tsikouras

et al. 2009

The Canadian Mineralogist

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“…En estas rocas se han reconocido "pods" de magnetita y cromitita de grado refractario (rica en Al) con contenidos en elementos del grupo de platino (Os, Ir, Ru), variando de 102 to 33 ppb (Proenza et al, 2004), así como vetillas y diseminaciones de magnesita y calcita. La asociación de MGP está caracterizada por la presencia de laurita, ironsita y aleaciones Ru-Os (Zaccarini et al, 2005). En Tecomatlán hay diseminaciones de cromita, muscovita cromífera (fuchsita) y epidota cromífera.…”

Section: Tehuitzingo-tecomatlán Pueblaunclassified

Características geológicas y potencial metalogenético de los principales complejos ultramáficos-máficos de México

Ortiz-Hernández

Escamilla-Casas

Flores-Castro

et al. 2006

BSGM

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“…To avoid confusion with osmium as an element, we will refer to the mineral grains as native osmium. Native osmium has been described in situ from ophiolites (Dmitrenko et al 1985;Legendre and Augé 1986;Augé and Johan 1988;Ohnenstetter et al 1991;Ohnenstetter 1992;Melcher et al 1997;Augé et al 1998;Garuti et al 1999;Melcher 2000;Zaccarini et al 2005;Ahmed 2007;Shi et al 2007;El Ghorfi et al 2008;Kapsiotis et al 2009;Uysal et al 2009;Gonzalez-Jimenez et al 2010 and references cited therein) layered intrusions (Cabri and Laflamme 1988;Balabonin et al 1994;Merkle 1998), and predominantly from placer deposits all over the world (Feather 1976;Cabri et al 1996;Malitch 1996;Krstid and Tarkian 1997;Nakagawa and Franko 1997;Gornostayev et al 1999;Weiser and Bachmann 1999;Weiser 2002;Malitch and Merkle 2004;Barkov et al 2005;Tolstykh et al 2005Tolstykh et al , 2009 among many others). For many placers, the location and type of the source rocks (e.g.…”

Section: Introductionmentioning

confidence: 99%

Native osmium from the Guli Massif, Northern Siberia, Russia

et al. 2011

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SummaryNative osmium from two different placer occurrences (i.e., Ingaringda and Burlakovsky) within the Guli Massif, Maimecha-Kotui Province, was evaluated for mineral compositions that show systematic differences between the localities. Grains of native osmium show increases in iridium towards the rim, and nuggets consisting of aggregates define trends of preferential substitution of osmium by iridium. A statistically reliable difference in Os/Ir ratios between the two studied placers can be demonstrated. From textural and compositional characteristics it is concluded that the native osmium of the Burlakovsky placer formed at temperatures higher than can be assumed to be reasonable for crustal conditions. The difference in the Os/Ir ratios between the two placers can be attributed to fractional crystallization of native osmium either in the mantle source, which was tapped in different events to form the Guli Massif, or to decreasing Os/Ir values during crystallization under crustal conditions after intrusion of the silicate melt(s).

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Platinum group minerals in ophiolitic chromitites from Tehuitzingo (Acatlán complex, southern Mexico): implications for post-magmatic modification

Cited by 78 publications

References 21 publications

Chromian Spinel Composition and Platinum-Group Element Mineralogy of Chromitites From the Milia Area, Pindos Ophiolite Complex, Greece

Chromian Spinel Composition and Platinum-Group Element Mineralogy of Chromitites From the Milia Area, Pindos Ophiolite Complex, Greece

Características geológicas y potencial metalogenético de los principales complejos ultramáficos-máficos de México

Native osmium from the Guli Massif, Northern Siberia, Russia

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