Platinum group minerals in podiform chromitites of the Bou Azzer ophiolite, Anti Atlas, Central Morocco

Ghorfi, Mustapha El; Melcher, Frank; Oberthür, Thomas; Boukhari, Abdelmajid El; Maacha, Lhou; Maddi, A.; Mhaili, M.

doi:10.1007/s00710-007-0208-2

Cited by 38 publications

(19 citation statements)

References 39 publications

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“…The PGE abundances are low in all samples, averaging 146.5 ppb in chromitite, 35.6 ppb in harzburgite, and 30.87 ppb in dunite. The total PGE concentrations in the podiform chromitites are within the range of values generally reported for ophiolitic chromitites (<300 ppb; El Ghorfi et al, 2008). The Pd/Ir, Ru/Pt, and IPGE /PPGE (i.e., iridium group, Os, Ir, Ru/palladium group, Rh, Pt, Pd) ratios are 0.029, 44.5, and 11.7 for Cr-rich chromitites and 2.15, 0.83, and 0.90, respectively, for harzburgites and 1.04, 0.98, and 1.29, respectively, for dunites.…”

Section: Pge Elementssupporting

confidence: 49%

Multiple episodes of melting, depletion, and enrichment of the Tethyan mantle: Petrogenesis of the peridotites and chromitites in the Jurassic Skenderbeu massif, Mirdita ophiolite, Albania

Yang

Dilek

et al. 2017

Lithosphere

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The Jurassic Mirdita ophiolite in Albania displays a structural-geochemical transition from a mid-ocean ridge-type (MOR) oceanic lithosphere in the west to a suprasubduction zone (SSZ) type in the east across an ~30-km-wide fossil Tethyan oceanic domain. We investigated the upper mantle peridotites of the Skenderbeu massif, situated at this transition within the ophiolite, to document the geochemical fingerprint of the inferred tectonic switch. The peridotites comprise harzburgites and dunites with podiform chromitite deposits. We present new whole-rock major element, trace element, rare earth element (REE), and platinum group element chemistry to evaluate their mantle melt evolution and petrogenesis. Harzburgites have high average CaO, Al 2 O 3 , and REE contents, and contain Al-rich pyroxene and spinel with lower Cr contents. Dunites have low average CaO, Al 2 O 3 , and REE values, and contain Al-poor clinopyroxene and high-Cr spinel. Modeling of trace element compositions of the harzburgites suggests as much as ~10%-15% melting, whereas the trace element compositions of the dunites indicate ~20%-25% melting. The harzburgites and dunites and chromitites represent, respectively, the products of low-degree partial melting in a MOR setting, and the products of high-degree partial melting and refertilization in a forearc mantle. The harzburgites resulted from rock-melt interactions between ascending melts and residual peridotites beneath a MOR, whereas the dunites and the high-Cr chromitites formed as a result of interactions between boninitic melts and mantle peridotites in a mantle wedge. The Skenderbeu mantle units thus constitute a geochemical-petrological archive of a transition from MOR to SSZ melt evolution in space and time within the same ocean basin.

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Section: Pge Elementssupporting

confidence: 49%

Multiple episodes of melting, depletion, and enrichment of the Tethyan mantle: Petrogenesis of the peridotites and chromitites in the Jurassic Skenderbeu massif, Mirdita ophiolite, Albania

Yang

Dilek

et al. 2017

Lithosphere

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“…Mineralogy and textural relations indicate that most of the PGM in the KLC chromitite have crystallized at high magmatic temperatures, prior to or concomitant with precipitation of chromite. Experimental data [37] supported by a large number of natural observations [38][39][40][41][42][43][44][45]51] indicate that laurite is in equilibrium with Os-Ir-(Ru) alloys at a temperature of 1300 ∘ C and relatively low sulfur fugacity (f S 2 ). Laurite becomes progressively enriched in Os with decreasing temperature and increasing sulfur fugacity, up to the stability field of erlichmanite.…”

Section: Discussionmentioning

confidence: 65%

PGE distribution in the Chromite bearing mafic-ultramafic Kondapalli Layered Complex, Krishna district, Andhra Pradesh, India

Meshram

Nannaware

et al. 2015

Open Geosciences

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Abstract:The Kondapalli Layered Complex (KLC) is a dismembered mafic-ultramafic layered intrusion, mainly composed of gabbroic and anorthositic rocks with subordinate ultramafics and chromitite. Chromitite occurs as lenses, pods, bands and disseminations. Platinum group of minerals (PGMs) occur as inclusions within chromite and silicates. The study indicates an inhomogeneous distribution of PGMs and distinct dominance of IPGEs over the PPGEs. The average ΣPGE content of chromite of KLC varies from 64 ppb to 576 ppb with Pt ranging from 5 to 495 ppb, Pd 5 to 191 ppb, Ir 3 to 106 ppb, Ru 3 to 376 ppb and Rh 3 to 135 ppb. The PGMs identified in the KLC indicate primary deposition of the IPGE, preceding chromite, indicating its orthomagmatic nature. Most of the PGM grains are usually below 10 µm. The identified PGMs are Laurite (RuS 2 ), irarsite (Ir, As, S), iridosmine (Os,Ir), undetermined Os-Ir sulphide and Ru-Os-Ir-Zn alloys. Chromite also contains inclusions of pentlandite, millerite, chalcopyrite and pyrite. Study indicating that the KLC have orthomagmatic origin for PGE which are dominated by IPGE group and formed under surpa-subduction zone peridotite setting.

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“…Chromitite orebodies and associated PGE mineralization are also documented within the Neoproterozoic ultramafic section of the Bou Azzer ophiolitic complex (Leblanc 1981;El Ghorfi et al 2008;Ahmed et al 2005Ahmed et al , 2009). Serpentinized harzburgite with subordinate dunite are the dominant host rocks accounting for about 40 vol% of the total exposed part of the complex (Bodinier et al 1984).…”

Section: Introductionmentioning

confidence: 91%

“…The shape and size of the orebodies are variable, with lenses generally ranging from <1 up to 20 m long and as much as 5 m thick, paralleling the N110°E orientation of the magmatic layering. Locally present are serpentinized harburgite-and dunite-hosted disseminations of euhedral to subhedral chromite grains, locally amounting to 4 vol %, together with massive chromitite that contains 30-80 vol% chromite (Ahmed et al 2005(Ahmed et al , 2009El Ghorfi et al 2008;Maacha et al 2011a).…”

Section: Introductionmentioning

confidence: 96%

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Geologic and Metallogenic Framework of North Africa

Bouabdellah

Slack

2016

Mineral Deposits of North Africa

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North Africa is noteworthy for having a great diversity of geology and mineral resources. Geologically, the region contains numerous terranes that contain rocks ranging in age from Archean to Quaternary, including diverse igneous, sedimentary, and metamorphic lithologies. Major geological features were built during the main phases of Proterozoic and subsequent Phanerozoic orogenies, the break-up of the supercontinents Rodinia, Gondwana, and Pangea, and during the opening and closing of major ocean basins such as the Iapatus, Atlantic, Pacific, and Tethys. Three major tectono-stratigraphic domains are recognized (1) the Precambrian province that includes the African-Nubian Shield (ANS) to the east and the West African Craton (WAC) to the west, and the intervening Tuareg Shield and "Saharan Metacraton"; (2) the Variscan (Paleozoic) fold belt; and (3) the Atlas-Alpine (Mesozoic-Cenozoic) system. Mineral deposits of North Africa formed in a variety of geologic settings at different time periods from Archean to Quaternary. Mineral commodities including gold, silver, cobalt, nickel, chromium, arsenic, copper, lead, zinc, iron, and many other elements. Major deposit types present in the region are (1) orthomagmatic Cr-Ni-platinum group elements (PGE); (2) rare-metal granites and related rare-element pegmatites; (3) volcanic-hosted massive sulphide (VHMS); (4) sedimentaryexhalative (SEDEX); (5) orogenic and intrusion-related gold; (6) iron oxide-copper-gold (IOCG); (7) banded iron formation (BIF); (8) Mississippi Valley-type (MVT) lead-zinc; (9) sediment-hosted stratiform copper;Electronic supplementary material The online version of this chapter

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Platinum group minerals in podiform chromitites of the Bou Azzer ophiolite, Anti Atlas, Central Morocco

Cited by 38 publications

References 39 publications

Multiple episodes of melting, depletion, and enrichment of the Tethyan mantle: Petrogenesis of the peridotites and chromitites in the Jurassic Skenderbeu massif, Mirdita ophiolite, Albania

Multiple episodes of melting, depletion, and enrichment of the Tethyan mantle: Petrogenesis of the peridotites and chromitites in the Jurassic Skenderbeu massif, Mirdita ophiolite, Albania

PGE distribution in the Chromite bearing mafic-ultramafic Kondapalli Layered Complex, Krishna district, Andhra Pradesh, India

Geologic and Metallogenic Framework of North Africa

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