The geochemistry of mantle chromitites from the northern part of the Oman ophiolite: inferred parental melt compositions

Rollinson, Hugh

doi:10.1007/s00410-008-0284-2

Cited by 281 publications

(223 citation statements)

References 37 publications

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“…5) are comparable with those in boninites from the Oman Ophiolite (0.7-1.2: Rollinson 2008). Still, it should be noted that subsolidus re-equilibration may significantly change FeO/MgO ratio in chromian spinels (Augé 1987) and this could explain some of our comparatively high calculated FeO/MgO ratios.…”

Section: Melt/rock Reactionsupporting

confidence: 61%

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Textural records and geochemistry of the Kermanshah mantle peridotites (Iran): implications for the tectonic evolution of southern Neo-Tethys

Moradpour¹,

Sahamieh²,

Khalaji³

et al. 2017

J. Geosci.

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Kermanshah Ophiolite Complex (NW Iran), located along the Main Zagros Thrust Zone, marks the ophiolitic suture between the Arabian and Sanandaj-Sirjan continental blocks. N-MORB-normalized multielement patterns and chondrite--normalized REE patterns in the Kermanshah mantle restites show depletion in incompatible elements concentrations with respect to the depleted MORB mantle (DMM). In the V vs. Yb diagram, Harsin-Sahneh-Norabad and Miyanrahan peridotites (Kermanshah Ophiolite Complex), due to their relatively low V contents, fall close to the QFM buffer. Calculated TiO 2 and Al 2 O 3 compositions in the parental melt that were in equilibrium with chromian spinel are consistent with supra-subduction zone-type compositions. Besides, calculated FeO/MgO ratios in the parental melts are comparable with those in boninites from Oman ophiolites. Olivine from the peridotite restites is highly magnesian (Fo 89-93 ) with NiO contents of 0.2-0.4 wt. %, consistent with formation in a forearc environment. This is also proven by the Cr# and Mg# values as well as TiO 2 , Cr 2 O 3 , and Al 2 O 3 concentrations in chromian spinel of ultramafic rocks. Accordingly, petrogenetic modeling indicates that the Kermanshah ultramafic rocks may represent the residual mantle after extraction of 13-23% of boninitic-type melts. Decompression, melting and melt-rock reaction related textures are widespread in the Kermanshah mantle restites. Field relationships and geochemical evidence reveal that the studied ophiolites were a part of a rifted basin at the ocean-continent transition zone formed in the south Neo-Tethyan Ocean.

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Section: Melt/rock Reactionsupporting

confidence: 61%

“…% Al 2 O 3 , respectively (Dilek and Thy 2009). Rollinson (2008) proposed a formula relating TiO 2 content in chromian spinel and parental melt: TiO 2 (wt. %) melt = 1.0963 × TiO 2 (wt.…”

Section: Melt/rock Reactionmentioning

confidence: 99%

Textural records and geochemistry of the Kermanshah mantle peridotites (Iran): implications for the tectonic evolution of southern Neo-Tethys

Moradpour¹,

Sahamieh²,

Khalaji³

et al. 2017

J. Geosci.

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“…Therefore, chromian spinel compositions have been used by many researchers as a sensitive petrogenetic indicator to constrain the parental melt composition (Dick and Bullen, 1984;Augé, 1987;Kepezhinskas et al, 1993;Arai, 1994;Zhou et al, 1996;Kamenetsky et al, 2001;Rollinson, 2008). Experimental studies have shown that Al 2 O 3 and TiO 2 contents, as well as FeO/MgO ratios in chromian spinel, are directly related to the compositions of parental melt (Maurel and Maurel, 1982;Augé, 1987;Kamenetsky et al, 2001;Rollinson, 2008). The Al 2 O 3 content of chromian spinel is controlled by the parental melt Al 2 O 3 content, which can be calculated using the formula by Maurel and Maurel (1982) …”

Section: Chromitite Genesismentioning

confidence: 99%

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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“…In a previous study Rollinson (2008) argued from a detailed study of a six-km traverse through Wadi Rajmi that the chromitites vary in composition with depth from the Moho. It was suggested that shallow chromitites had low cr# (0.5-0.6) whereas chromitites deeper in the mantle had higher cr#.…”

Section: Chromite Compositionsmentioning

confidence: 99%

“…We concur, for we find similar evidence in the chromitites. Rollinson (2008) used the experimentally determined relationships between Ti and Al in chrome spinels and their host melt to calculate the composition of the melts from Figure 2 which the Wadi Rajmi chromitites had been derived. These compositions were then compared with the composition of melts known in the lava sequence of the ophiolite.…”

Section: Chromite Compositionsmentioning

confidence: 99%

Chromite in the Mantle Section of the Oman Ophiolite: Implications for the Tectonic Evolution of the Oman Ophiolite

Rollinson

Adetunji

2015

Acta Geologica Sinica (Eng)

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The geochemistry of mantle chromitites from the northern part of the Oman ophiolite: inferred parental melt compositions

Cited by 281 publications

References 37 publications

Textural records and geochemistry of the Kermanshah mantle peridotites (Iran): implications for the tectonic evolution of southern Neo-Tethys

Textural records and geochemistry of the Kermanshah mantle peridotites (Iran): implications for the tectonic evolution of southern Neo-Tethys

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

Chromite in the Mantle Section of the Oman Ophiolite: Implications for the Tectonic Evolution of the Oman Ophiolite

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