Re‐Os Isotopic Measurements at the Femtomole Level in Natural Samples

Birck, J. L.; Barman, Matthieu Roy; Capmas, Françoise

doi:10.1111/j.1751-908x.1997.tb00528.x

Cited by 671 publications

(353 citation statements)

References 27 publications

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“…Isotopic tracers ( 185 Re and 190 Os) were added to samples prior to dissolution. Os was purified using CCl 4 and HBr, micro-distilled for 3 h [43] and dried to 3 L. Os-isotope measurements were carried out by N-TIMS [44,45] with a Thermo Finnigan Triton.…”

Section: Analytical Methods and Resultsmentioning

confidence: 99%

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: Analytical Methods and Resultsmentioning

confidence: 99%

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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“…Moreover, the bulk of ureilite HSE are hosted in interstitial metal phases (Janssens et al, 1987) and the high-temperature igneous processing of ureilites precludes the occurrence of highly refractory primordial HSEbearing alloys as observed for example in CAIs (Becker et al, 2001), or other refractory phases as observed in unequilibrated bulk chondrites (Brandon et al, 2005b). After digestion, Os was extracted from the reverse aqua regia using carbon tetrachloride solvent, then back extracted into HBr (Cohen and Waters, 1996), and finally purified by microdistillation (Birck et al, 1997). Following Os extraction, the aqua regia solutions were dried down and converted into chloride form, dissolved in 0.15N HCl, and loaded onto cation exchange columns for Re separation and purification (Puchtel and Humayun, 2001).…”

Section: Analytical Techniquesmentioning

confidence: 99%

Osmium isotope systematics of ureilites

Rankenburg

Brandon

Humayun

2007

Geochimica et Cosmochimica Acta

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The 187 Os/ 188 Os for twenty-two ureilite whole rock samples, including monomict, augite-bearing, and polymict lithologies, were examined in order to constrain the provenance and subsequent magmatic processing of the ureilite parent body (or bodies). The Re/Os ratios of most ureilites show evidence for a recent disturbance, probably related to Re mobility during weathering, and no meaningful chronological information can be extracted from the present data set. The ureilite 187 Os/ 188 Os ratios span a range from 0.11739 to 0.13018, with an average of 0.1258 ± 0.0023 (1σ), similar to typical carbonaceous chondrites, and distinct from ordinary or enstatite chondrites. The similar mean of 187 Os/ 188 Os measured for the ureilites and carbonaceous chondrites suggests that the ureilite parent body probably formed within the same region of the solar nebula as carbonaceous chondrites. From the narrow range of the 187 Os/ 188 Os distribution in ureilite meteorites it is further concluded that Re was not significantly fractionated from Os during planetary differentiation and was not lost along with the missing ureilitic melt component. The lack of large Re/Os fractionations requires that Re/Os partitioning was controlled by a metal phase, and thus metal had to be stable throughout the interval of magmatic processing on the ureilite parent body.3

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“…Appropriate amounts of mixed 185 Os and 191 Pt-105 Pd spikes and sample powders (0.09 to 0.26 g for Wudi peridotites and 0.08 to 0.51 g for Fuxin peridotites) were sealed, along with 2 ml of concentrated Teflon-distilled HCl and 3.5 ml of concentrated Teflon-distilled HNO 3 into a pre-cleaned, chilled, thick-walled borosilicate Carius tube, and heated to 270°C for N 72 h. Osmium was extracted immediately from the acid solution after digestion by solvent extraction into CCl 4 , then back extracted into HBr (Cohen and Waters, 1996), and finally purified via microdistillation using a H 2 SO 4 -dichromate solution into 15 μl of concentrated HBr (Birck et al, 1997). Iridium, Ru, Pt, Pd and Re were separated and purified from the remaining acid solution using anion exchange column chromatography (Rehkämper and Halliday, 1997).…”

Section: Whole-rock Re-os Isotope and Pge Abundance Analysesmentioning

confidence: 99%

Big insights from tiny peridotites: Evidence for persistence of Precambrian lithosphere beneath the eastern North China Craton

et al. 2015

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Previous studies have shown that the eastern North China Craton (NCC) lost its ancient lithospheric mantle root during the Phanerozoic. The temporal sequence, spatial extent, and cause of the lithospheric thinning, however, continue to be debated. Here we report olivine compositions, whole-rock Re-Os isotopic systematics, and platinum-group element abundances of small (b 2 cm in maximum dimension) mantle peridotite xenoliths from two basalt localities from the eastern NCC, Wudi (Cenozoic) and Fuxin (Cretaceous). These locations lie far (~150-200 km) from the Tan-Lu fault, which has been linked to lithospheric replacement in the eastern NCC. Peridotites at both locations have fertile to moderately refractory compositions (Fo b 91.5), while highly refractory (Fo N 92) lithospheric mantle is largely absent. Osmium isotopic data suggest the Wudi peridotites experienced melt depletion primarily during the Paleoproterozoic (~1.8 Ga), although an Archean Os model age for one xenolith indicates incorporation of a minor component of Archean lithospheric mantle. These data suggest that a previously unrecognized Paleoproterozoic orogenic event removed and replaced the original Archean lithospheric mantle beneath the sedimentary basin at the southern edge of the Bohai Sea. By contrast, the Fuxin peridotites, entrained in Cretaceous basalts that crop out along the northern edge of the eastern NCC, document the coexistence of both ancient (≥2.3 Ga) and modern lithospheric mantle components. Here, the original Late Archean-Early Paleoproterozoic lithospheric mantle was, at least partially, removed and replaced prior to 100 Ma. Combined with literature data, our results show that removal of the original Archean lithosphere occurred within Proterozoic collisional orogens, and that replacement of Precambrian lithosphere during the Mesozoic may have been spatially associated with the collisional boundaries and the strike-slip Tan-Lu fault, as well as the onset of Paleo-Pacific plate subduction.

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Re‐Os Isotopic Measurements at the Femtomole Level in Natural Samples

Cited by 671 publications

References 27 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

Osmium isotope systematics of ureilites

Big insights from tiny peridotites: Evidence for persistence of Precambrian lithosphere beneath the eastern North China Craton

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