Osmium isotopic compositions of mantle xenoliths: a global perspective

Meisel, Thomas; Walker, Richard J.; Irving, A. J.; Lorand, Jean‐Pierre

doi:10.1016/s0016-7037(00)00566-4

Cited by 639 publications

(390 citation statements)

References 52 publications

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“…The chondritic to sub-chondritic Os isotopic composition of most Saint Paul Fracture Zone peridotites contrasts with models of Os isotopic evolution of the primitive upper mantle as constrained by spinel lherzolites from continental environments that support a more chondritic value for the bulk upper mantle (Meisel et al, 1996(Meisel et al, , 2001 …”

Section: Geochemistry Of the Abyssal Peridotitecontrasting

confidence: 60%

Geophysical and geochemical evidence for cold upper mantle beneath the Equatorial Atlantic Ocean

Sichel¹,

Esperança²,

Motoki³

et al. 2008

Rev. Bras. Geof.

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Section: Geochemistry Of the Abyssal Peridotitecontrasting

confidence: 60%

Geophysical and geochemical evidence for cold upper mantle beneath the Equatorial Atlantic Ocean

Sichel¹,

Esperança²,

Motoki³

et al. 2008

Rev. Bras. Geof.

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“…The Os concentrations and isotopic compositions for present-day PM are well constrained and are used for the primitive mantle component present in the plume (Table 4; Meisel et al, 2001;Morgan et al, 2001;Brandon et al, 2006). The DPS component represents a source with a slightly lower long-term Re/Os resulting from melt removal and loss of slightly incompatible Re relative to Os in the convecting mantle, consistent with the outgassing He model of Class and Goldstein (2005).…”

Section: Os Constraintsmentioning

confidence: 69%

“…The 187 Os/ 188 Os isotopic composition of the MORB upper mantle has been postulated to range from the present-day PM composition of 0.1296 (Meisel et al, 2001;Walker et al, 2002) to that having a slightly depleted long-term Re/Os relative to PM with 187 Os/ 188 Os ~0.125 (Snow and Reisberg 1995;Brandon et al, 2000). As such, a MORB mantle encompassing both of these scenarios is considered in the models.…”

Section: Os Constraintsmentioning

confidence: 99%

186Os and 187Os enrichments and high-3He/4He sources in the Earth’s mantle: Evidence from Icelandic picrites

Brandon

Graham

Waight³

et al. 2007

Geochimica et Cosmochimica Acta

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Picrites from the neovolcanic zones in Iceland display a range in 187 Os/ 188 Os from 0.1297 to 0.1381 (γ Os = 0.0 to 6.5) and uniform 186 Os/ 188 Os of 0.1198375±32 (2σ). The value for 186 Os/ 188 Os is within uncertainty of the present-day value for the primitive upper mantle of 0.1198398±16. These Os isotope systematics are best explained by ancient recycled crust or melt enrichment in the mantle source region. If so, then the coupled enrichments displayed in 186 Os/ 188 Os and 187 Os/ 188 Os from lavas of other plume systems must result from an independent process, the most viable candidate at present remains core-mantle interaction. While some plumes with high 3 He/ 4 He, such as Hawaii, appear to have been subjected to detectable addition of Os (and possibly He) from the outer core, others such as Iceland do not.A positive correlation between 187 Os/ 188 Os and 3 He/ 4 He from 9.6 to 19 R A in Iceland picrites is best modeled as mixtures of 500 Ma or older ancient recycled crust mixed with primitive mantle, creating a hybrid source region that subsequently mixes with the convecting MORB mantle during ascent and melting. This multistage mechanism to explain these isotope systematics is consistent with ancient recycled crust juxtaposed with more primitive, relatively He-rich mantle, in convective isolation from the upper mantle, most likely in the lowermost mantle. This is inconsistent with models that propose random mixing between heterogeneities in the convecting upper mantle as a mechanism to explain the observed isotopic variation in oceanic lavas or models that produce a high 3 He/ 4 He signature in melt depleted and strongly

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“…In contrast to primitive mantle values [78,79], the Os-isotope characteristics of the mantle source for the magmas in the Nagquo phioliteare slightly lower, which could imply that the source is a slightly depleted asthenospheric mantle. The Nd-Pb isotopic composition and geochemical data of mafic rocks from Tethyan ophiolites also indicate that they are derived from a geochemically depleted asthenospheric source with a clear Indian MORB-type isotopic signature [80].…”

mentioning

confidence: 61%

Os isotopic evidence for a carbonaceous chondritic mantle source for the Nagqu ophiolite from Tibet and its implications

et al. 2012

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Early-crystallizing chromian spinel (Cr-spinel) in the Nagqu ophiolite has high Os and low Re contents, and it is resistant to alteration during serpentinization, weathering and metamorphism. The chemical composition of primitive magma is preserved in Cr-spinel, which makes it suitable for determining the initial Os-isotope composition of the mantle source. This study presents Cr-spinel Os isotopes and zircon U-Pb ages for cumulate dunite and gabbro, respectively, in the same cumulate section of the ophiolite at Nagqu in Tibet. The results shed light on the formation and evolution of lithospheric mantle. The Nagqu ophiolite is located in the central part of the Bangong-Nujiang suture zone. It is a remnant of the Neotethyan oceanic crust, and contains cumulate dunite and gabbro. Zircon from the gabbro yielded a weighted mean 206 Pb/ 238 U age of 183.7±1 Ma. Cr-spinel exhibits  Os values of 0.2 to 0.3, suggesting that the mantle source for the dunite is similar to that of carbonaceous chondrites. Thus, the Tibetan lithosphere is primarily a relic of Tethyan oceanic lithosphere, which has formed by the transformation of the normal asthenospheric mantle in the Mesozoic. This is the first study to combine the spinel Os isotopes with accurate zircon U-Pb ages to constrain the geochemical characteristics of the mantle source for the ophiolite.Re-Os isotopes, spinel, ophiolite, Nagqu, Tibet Citation:Huang Q S, Shi R D, Liu D L, et al. Os isotopic evidence for a carbonaceous chondritic mantle source for the Nagqu ophiolite from Tibet and its implications. Chin Sci Bull, 2013, 58: 9298,

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Osmium isotopic compositions of mantle xenoliths: a global perspective

Cited by 639 publications

References 52 publications

Geophysical and geochemical evidence for cold upper mantle beneath the Equatorial Atlantic Ocean

Geophysical and geochemical evidence for cold upper mantle beneath the Equatorial Atlantic Ocean

186Os and 187Os enrichments and high-3He/4He sources in the Earth’s mantle: Evidence from Icelandic picrites

Os isotopic evidence for a carbonaceous chondritic mantle source for the Nagqu ophiolite from Tibet and its implications

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