Widespread arc-related melting in the mantle section of the northern Oman ophiolite as inferred from detrital chromian spinels

Arai, Shoji; Kadoshima, K.; Morishita, Tomoaki

doi:10.1144/0016-76492005-057

Cited by 166 publications

(89 citation statements)

References 69 publications

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“…They provide us with incomparable information for understanding various processes occurring throughout the crust -mantle section of oceanic lithosphere. Ophiolites sometimes show two contrasting types of magmatism, oceanic and arc -like, which produced extrusives to mantle peridotites (e.g., Ishikawa et al, 2002;Arai et al, 2006). This dual character of ophiolites complicates our understanding of their origins (e.g., Nicolas, 1989).…”

Section: Introductionmentioning

confidence: 99%

“…This dual character of ophiolites complicates our understanding of their origins (e.g., Nicolas, 1989). The polygenetic characteristics of the constituent rocks of ophiolite complexes have been discussed for the Oman ophiolite (e.g., Ishikawa et al, 2002;Arai et al, 2006). Ishikawa et al (2002) clarified the distribution of boninites as lavas and dikes crosscutting pre -existing MORB -related extrusives.…”

Section: Introductionmentioning

confidence: 99%

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Formation of discordant chromitite at the initiation of sub-arc mantle processes: Observations from the northern Oman ophiolite

Miura

Arai

Tamura

2014

Journal of Mineralogical and Petrological Sciences

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Discordant chromitite, one of the structural types of ophiolitic chromitite, and surrounding peridotites, were examined in the mantle section of the northern Oman ophiolite along Wadi Hilti, to constrain its origin. Spinels from chromitite and adjacent peridotites show high Cr# (= Cr/(Cr + Al) atomic ratio), around 0.65 to 0.75, indicating an arc -related feature. Clinopyroxenes from adjacent harzburgites show low HREE contents, indicating a highly depleted character. The calculated melt composition in equilibrium with clinopyroxene in the dunite envelope indicates that the chromitite and surrounding peridotites were derived from arc -related magma, such as boninite. The arc -related magma was probably generated by the flux melting of depleted mantle harzburgite on the subducted slab, in terms of incompatible element enrichment in clinopyroxene from dunite and harzburgite. The highly depleted harzburgite surrounding discordant dunite and chromitite shows transitional changes in spinel and REE chemistry toward the surrounding oceanic harzburgites. This feature indicates that pre -existing oceanic harzburgite was partially modified by arc -related magma. Discordant chromitite, dunite, and highly depleted harzburgites are probably formed at the supra -subduction zone environment just before ophiolite obduction. Such arc -related features in mantle peridotite may be produced at a young sub -arc mantle.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Formation of discordant chromitite at the initiation of sub-arc mantle processes: Observations from the northern Oman ophiolite

Miura

Arai

Tamura

2014

Journal of Mineralogical and Petrological Sciences

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“…7. They are chemically similar to detrital chromian spinels from Oman (ODCS) (see also Arai et al 2006a). On the other hand, in Fig.…”

Section: Provenance Implicationsmentioning

confidence: 93%

“…"Podiform" and "stratiform" fields are from Mussallam et al (1981). ODCS = Oman detrital chromian spinels that are representative of mantle-derived rocks of Oman ophiolite (Arai et al 2006a). Symbols as in Fig.…”

Section: Provenance Implicationsmentioning

confidence: 99%

Detrital chromian spinels from Miocene and Holocene sediments of northern Iraq: provenance implications

Al-Juboury¹,

Ghazal²,

McCann³

2012

J. Geosci.

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The study integrates mineralogical and chemical characteristics of the chromian spinels from northern Iraq using standard petrographic and scanning microscope techniques as well as electron microprobe analyses in order to better understand their provenance, and the implications thereof. Detrital chromian spinels are found as one of the predominant accessory heavy minerals within fluviatile Miocene and Holocene sediments. In addition, such spinels are also present in the Palaeogene-Neogene and Cretaceous alluvial, deltaic and turbiditic sandstones. The results indicate that most of the chromian spinels have interrelated ranges of Cr/(Cr+Al) at rather low contents of Fe and Ti suggesting that the sandstones which host the chromian spinels were derived from a source area dominated by ultramafic rocks. Mineralogical and chemical data suggest that Alpine-type peridotites were the main source rocks for the studied chromian spinels. All available evidence supports the idea that the sandstones originated from the ophiolite-radiolarite belt of the Taurus Range in northeastern Turkey, as well as from recycling of the uplifted Cretaceous strata of northern Iraq.

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“…It is characterized, however, by arc -type rocks, e.g., boninites and high -Cr plutonic rocks, that cut or intrude MORB -related rocks (e.g., Ishikawa et al, 2002;Ahmed and Arai, 2002;Tamura and Arai, 2006). Pearce et al (1984) suggested a back -arc basin origin for the Oman ophiolite, whereas Arai et al (2006) suggested multiple origins, namely, initial formation at a mid -ocean ridge followed by modification at a subduction zone immediately before obduction.…”

Section: Geological Backgroundmentioning

confidence: 99%

Petrologic profile of peridotite layers under a possible Moho in the northern Oman ophiolite: an example from Wadi Fizh

Akizawa

Arai

2009

Journal of Mineralogical and Petrological Sciences

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We examined vertical variations of the petrological characteristics of a 33 -m -thick peridotite section under the layered gabbro section along Wadi Fizh of the northern Oman ophiolite to understand the formation mechanism of the Mohorovicic discontinuity (Moho) beneath a spreading center. Here, we refer to the base of the layered gabbro section as "L -Moho" for the sake of simplicity. Network -like gabbro sills in peridotites increase in frequency upward to the L -Moho. The L -Moho is underlain by a 1 -m -thick wehrlite layer, under which exists a 10 -m -thick dunite layer, overlying a harzburgite layer where total pyroxenes slightly increase downward. Wehrlite is also found as screens between gabbro layers above the L -Moho. The mineral chemistry indicates systematic variations toward the L -Moho within the peridotite section; the Fo content (91 to 85) and NiO (0.4 to 0.2 wt%) of olivine decrease; the TiO 2 content of clinopyroxene (0.1 to 0.6 wt%) and spinel (nil to 1.4 wt%) and atomic ratios of Cr/(Cr + Al) (0.5 to 0.6) and Fe 3+ /(Cr + Al + Fe 3+ ) (0.05 to >0.1) in spinel increase upsection from the base (harzburgite) to the around L -Moho wehrlite via dunite. These variations are essentially similar to those observed in harzburgite/MORB reaction products from Hess Deep, East Pacific Rise, and possibly indicate that the lithological and mineral chemical variations within the examined peridotite layer resulted from the reaction between a harzburgite and a melt that produced the layered gabbros.

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Widespread arc-related melting in the mantle section of the northern Oman ophiolite as inferred from detrital chromian spinels

Cited by 166 publications

References 69 publications

Formation of discordant chromitite at the initiation of sub-arc mantle processes: Observations from the northern Oman ophiolite

Formation of discordant chromitite at the initiation of sub-arc mantle processes: Observations from the northern Oman ophiolite

Detrital chromian spinels from Miocene and Holocene sediments of northern Iraq: provenance implications

Petrologic profile of peridotite layers under a possible Moho in the northern Oman ophiolite: an example from Wadi Fizh

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