Os isotopes and highly siderophile elements (HSE) in the Ligurian ophiolites, Italy

Snow, J. E.; Schmidt, Gerhard; Rampone, Elisabetta

doi:10.1016/s0012-821x(99)00280-0

Cited by 60 publications

(33 citation statements)

References 43 publications

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“…During the process of magma formation at spreading centers, relatively primitive convecting upper mantle will preferentially melt. Conversely, refractory, previously depleted lithospheric mantle will not participate in partial melting without water [6,20]. Although about 4% eclogite may be subducted into the asthenospheric mantle [66,67], its contribution to the 187 Os/…”

Section: Spinel Recording Mantle Sourcementioning

confidence: 99%

“…Many studies have suggested that there are significant differences in the Os-isotope composition of mantle peridotites [6][7][8][9][10][11][12][13]. Subsequent to their formation, mantle peridotites may be modified by partial melting processes and interaction with melts percolating through them [14][15][16].…”

mentioning

confidence: 99%

“…Recent studies indicate that refractory subcontinental lithospheric mantle (SCLM) can survive during the opening of ocean basins and become part of the oceanic lithosphere [10,[17][18][19][20][21][22]. Given the such preservation of refractory domains in ophiolitic mantle peridotites [6,8], their Re-Os isotopic characteristics cannot precisely reflect the nature of the convecting mantle at the time of ophiolite formation.…”

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confidence: 99%

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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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Section: Spinel Recording Mantle Sourcementioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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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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“…As the Emeishan picrites are relatively low-degree partial melts , the high Os concentrations in the ELIP picrites cannot be explained by the mechanism proposed by Schaefer et al (2000). An alternative interpretation invokes a small contribution in the mantle source of Os derived from the outer core (e.g., Snow and Schmidt, 1998;Snow et al, 2000), and indeed would be required if core-derived materials were detectable in the lavas through their 186 Os-187 Os characteristics (e.g., Brandon et al, 1998). In addition, high Os concentration also may result from fractional crystallization.…”

Section: Pge Characteristics As Features Of the Emeishan Mantle Sourcementioning

confidence: 97%

Platinum group elements in the Emeishan large igneous province, SW China: Implications for mantle sources

et al. 2005

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We report concentrations of platinum group elements (PGE: Os, Ir, Ru, Rh, Pt and Pd) for picrite-basalt lavas of the Emeishan large igneous province, SW China. The absolute concentrations of Os in most of the Emeishan picrites are higher than in picrites from ocean islands and other continental flood basalt provinces, and in estimated primitive mantle. A roughly positive correlation between MgO and Cr and Ni, and no overall correlation of Os or Ir with MgO, show that no Cu-Ni sulfide fractionated during differentiation but rather that olivine and chromite fractionated, implying that the initial picritic magma was sulfide-undersaturated. In addition, Os/Ir ratios are unusually high, suggesting that the picritic magmas may have been contaminated by black shales. Modeling shows that a 7% partial melt of primitive mantle containing 0.01 wt% of sulfides can account for the observed Os, Ir and Ru concentrations in the most primitive picrite if the melt is contaminated by 10 wt% of black shale en route to the surface.

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“…Almost all of them focus on whole-rock isotopic compositions [41,42]. The studies on oceanfloor rocks demonstrate a range of Os isotopic compositions, from the least radiogenic ones observed in abyssal peridotites ranging from 0.120 to 0.129, with an average of 0.1246, to the more radiogenic ones in MORB ranging from 0.127 to 0.20 [35,36,32,43].…”

Section: Osmium-isotope Studies On Ophiolites: Overviewmentioning

confidence: 99%

Osmium isotope systematics of the Proterozoic and Phanerozoic ophiolitic chromitites: In situ ion probe analysis of primary Os-rich PGM

Ahmed

Hanghøj

Kelemen

et al. 2006

Earth and Planetary Science Letters

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In-situ 187 Os/ 188 Os ratios are determined on Os-rich platinum-group minerals in podiform chromitites both in the Proterozoic ophiolite, Eastern Desert, Egypt, and in the Os/ 188 Os ratios combined with the spinel chemistry and high PGE contents of the PGE-rich chromitite in the Oman ophiolite may give reliable evidence for high degree partial melting at a supra-subduction zone setting.Crustal contamination from the subducted slab, and assimilation of previously altered, lower crustal gabbro, may have contributed to the high Cr# spinel and radiogenic Os characteristics in chromitite formed in the mantle section and along the Moho transition zone, respectively.

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Os isotopes and highly siderophile elements (HSE) in the Ligurian ophiolites, Italy

Cited by 60 publications

References 43 publications

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

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

Platinum group elements in the Emeishan large igneous province, SW China: Implications for mantle sources

Osmium isotope systematics of the Proterozoic and Phanerozoic ophiolitic chromitites: In situ ion probe analysis of primary Os-rich PGM

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