Geochemistry and tectonic significance of peridotites from the South Sandwich arc-basin system, South Atlantic

Pearce, Julian A.; Barker, Peter F.; Edwards, Susan; Parkinson, I. J.; Leat, P. T.

doi:10.1007/s004100050572

Cited by 628 publications

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“…These minerals and millimetre-size gabbro-noritic aggregates indicate impregnation of harzburgite by melts with the composition of the lowpressure peridotite eutectic (e.g. Piccardo et al 2005;Pearce et al 2000). Depleted lherzolites have minor clinopyroxene and are considered to represent residual MORB mantle (Allahyari et al 2010).…”

Section: A1 Kermanshah Ophiolitementioning

confidence: 99%

“…Short thick arrow shows compositional changes due to re-equilibration of Cpx with percolating melt. Izu-Bonin-Mariana (IBM) and South Sandwich fore-arc harzburgite data are from Parkinson & Pearce (1998) and Pearce et al (2000), respectively; Mariana Trough (back-arc basin peridotite) data are from Ohara et al (2002). For comparison we have also plotted data on the Kermanshah peridotite from Allahyari et al (2010).…”

Section: E Spinel Composition From Inner and Outer Belt Peridotitesmentioning

confidence: 99%

“…Some data show affinity to boninite. IBM and South Sandwich fore-arc harzburgite data are from Parkinson & Pearce (1998) and Pearce et al (2000), respectively; Mariana Trough (back-arc basin) peridotite are from Ohara et al (2002); Oman harzburgite data are from Le Mée, Girardeau & Monnier (2004) and Tamura & Arai (2006). contents ( Fig.…”

Section: A Summary Of Upper Cretaceous Zagros Ophiolite Compositiomentioning

confidence: 99%

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Geodynamic evolution of Upper Cretaceous Zagros ophiolites: formation of oceanic lithosphere above a nascent subduction zone

2011

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-The Zagros fold-and-thrust belt of SW Iran is a young continental convergence zone, extending NW-SE from eastern Turkey through northern Iraq and the length of Iran to the Strait of Hormuz and into northern Oman. This belt reflects the shortening and off-scraping of thick sediments from the northern margin of the Arabian platform, essentially behaving as the accretionary prism for the Iranian convergent margin. Distribution of Upper Cretaceous ophiolites in the Zagros orogenic belt defines the northern limit of the evolving suture between Arabia and Eurasia and comprises two parallel belts: (1) Outer Zagros Ophiolitic Belt (OB) and (2) Inner Zagros Ophiolitic Belt (IB). These belts contain complete (if disrupted) ophiolites with well-preserved mantle and crustal sequences. Mantle sequences include tectonized harzburgite and rare ultramafic-mafic cumulates as well as isotropic gabbro lenses and isolated dykes within the harzburgite. Crustal sequences include rare gabbros (mostly in IB ophiolites), sheeted dyke complexes, pillowed lavas and felsic rocks. All Zagros ophiolites are overlain by Upper Cretaceous pelagic limestone. Limited radiometric dating indicates that the OB and IB formed at the same time during Late Cretaceous time. IB and OB components show strong suprasubduction zone affinities, from mantle harzburgite to lavas. This is shown by low whole-rock Al 2 O 3 and CaO contents and spinel and orthopyroxene compositions of mantle peridotites as well as by the abundance of felsic rocks and the trace element characteristics of the lavas. Similarly ages, suprasubduction zone affinities and fore-arc setting suggest that the IB and OB once defined a single tract of fore-arc lithosphere that was disrupted by exhumation of subducted Sanandaj-Sirjan Zone metamorphic rocks. Our data for the OB and IB along with better-studied ophiolites in Cyprus, Turkey and Oman compel the conclusion that a broad and continuous tract of fore-arc lithosphere was created during Late Cretaceous time as the magmatic expression of a newly formed subduction zone developed along the SW margin of Eurasia.

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Section: A1 Kermanshah Ophiolitementioning

confidence: 99%

Section: E Spinel Composition From Inner and Outer Belt Peridotitesmentioning

confidence: 99%

Section: A Summary Of Upper Cretaceous Zagros Ophiolite Compositiomentioning

confidence: 99%

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Geodynamic evolution of Upper Cretaceous Zagros ophiolites: formation of oceanic lithosphere above a nascent subduction zone

2011

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“…Olivine-spinel mantle array and melting trend (annotated by partial melting %) are from Arai (1994). Data sources: Korean peridotites (Kim et al, 1988;Lee, 1996;Choi et al, 2001Kil and Lee, 2005;Kil, 2006Kil, , 2007Shin et al, 2006;Kil et al, 2008;Yang et al, 2009;Yu et al, 2011); abyssal peridotites (Dick and Bullen, 1984); supra-subduction zone peridotites (Ishii et al, 1992;Parkinson and Pearce, 1998;Pearce et al, 2000). FMM = fertile mid-ocean ridge basalt mantle.…”

Section: 우리나라에서 맨틀 포획암이 산출되는 지역은 백령 도 간성일대 아산-평택지역 보은(조곡리) 및 제주도mentioning

confidence: 99%

Lithospheric Mantle beneath the Korean Peninsula: Implications from Peridotite Xenoliths in Alkali Basalts

Choi¹

2012

The Journal of the Petrological Society of Korea

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Peridotite xenoliths hosted by alkali basalts from South Korea occur in Baengnyeong Island, Jeju Island, Boeun, Asan, Pyeongtaek and Ganseong areas. K-Ar whole-rock ages of the basaltic rocks range from 0.1 to 18.9 Ma. The peridotites are dominantly lherzolites and magnesian harzburgites, and the constituent minerals are Fo-rich olivine (Fo 88.4-92.0 ), En-rich orthopyroxene, Di-rich clinopyroxene, and Crrich spinel (Cr# = 7.8-53.6). Hydrous minerals, such as pargasite and phlogopite, or garnet have not been reported yet. The Korean peridotites are residues after variable degree of partial melting (up to 26%) and melt extraction from fertile MORB mantle. However, some samples (usually refractory harzburgites) exhibit metasomatic enrichment of the highly incompatible elements, such as LREE. Equilibration temperatures estimated using two-pyroxene geothermometry range from ca. 850 to 1050 o C. Sr and Nd isotopic compositions in clinopyroxene separates from the Korean peridotites show trends between depleted MORB-like mantle (DMM) and bulk silicate earth (BSE), which can be explained by secondary metasomatic overprinting of a precursor time-integrated depleted mantle. The Korean peridotite clinopyroxenes define mixing trends between DMM and EM2 end members on Sr-Pb and Nd-Pb isotopic correlation diagrams, without any corresponding changes in the basement. This is contrary to what we

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“…According to Pearce and Norry (1979), the Ti content in clinopyroxenes reflects the degree of depletion of the mantle source, as well as the Ti activity of the parental magma that generated the in- (Deer et al 1992). b-c -Pyroxene quadrilateral diagram (Morimoto 1989) showing the composition of orthopyroxene and clinopyroxene; d -Cation plot of Cr + Fe vs. Al + Mg for chromian spinels; the diagonal line represents a 1:1 replacement; e -Plot of Cr# (spinel) vs. Fo (olivine) after Pearce et al (2000), showing the fields of abyssal peridotite after Dick and Bullen (1984), supra-subduction zone (SSZ) peridotites after Pearce et al (2000). FMM = Fertile MORB Mantle.…”

Section: Clinopyroxenementioning

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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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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Geochemistry and tectonic significance of peridotites from the South Sandwich arc-basin system, South Atlantic

Cited by 628 publications

References 0 publications

Geodynamic evolution of Upper Cretaceous Zagros ophiolites: formation of oceanic lithosphere above a nascent subduction zone

Geodynamic evolution of Upper Cretaceous Zagros ophiolites: formation of oceanic lithosphere above a nascent subduction zone

Lithospheric Mantle beneath the Korean Peninsula: Implications from Peridotite Xenoliths in Alkali Basalts

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

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