Re-Os isotopic systematics and platinum group element composition of the Tagish Lake carbonaceous chondrite

Brandon, A. D.; Humayun, M.; Puchtel, I. S.; Zolensky, M. E.

doi:10.1016/j.gca.2004.10.005

Cited by 63 publications

(53 citation statements)

References 69 publications

(148 reference statements)

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“…Details of Re-Os analytical procedures have been previously documented (Brandon et al, l999;Brandon et al, 2005a;2005b) and only a brief description is provided here.…”

Section: Analytical Techniquesmentioning

confidence: 99%

“…The remainder of the high-precision Os isotope data were obtained by NTIMS on the Thermo Finnigan Triton ( Puchtel et al, 2004Puchtel et al, , 2005Walker et al, 2005;Brandon et al 2005aBrandon et al , 2005b (Walker et al, l997;Brandon et al, l998;Brandon et al, l999;Brandon et al, 2000;Brandon et al, 2003;Puchtel et al, 2004;2005;Walker et al, 2005;Brandon et al, 2005a;2005b). Accordingly, for direct comparison to earlier data, the Iceland picrite and basalt data in Table 1 For He analyses, details of the procedures are presented elsewhere (Graham et al,l998).…”

Section: Analytical Techniquesmentioning

confidence: 99%

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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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“…Details of Re-Os analytical procedures have been previously documented (Brandon et al, l999;Brandon et al, 2005a;2005b) and only a brief description is provided here.…”

Section: Analytical Techniquesmentioning

confidence: 99%

Section: Analytical Techniquesmentioning

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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“…Within the past 20 years, the 187 Re-187 Os system has established its rank among the radiogenic isotope systems commonly applied to cosmochemical issues (Shirey and Walker, 1998). Because Re and Os are both refractory and siderophile elements, the Re-Os system has proven useful in studies of primitive solar system materials such as the iron meteorites (Shen et al, 1996;Smoliar et al, 1996), but also CAIs and chondrites (Becker et al, 2001;Brandon et al, 2005a;Brandon et al, 2005b;Walker et al, 2002). Because the ureilites contain significant amounts of metal, a Re-Os study seems appropriate to shed some light on their formation history.…”

Section: Introductionmentioning

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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“…4). [Note that external ±2 sigma precision on the 187 Os/ 188 Os ratio is within the size of each individual data point in the histogram (Brandon et al 2005).] Mars primitive upper mantle appears to have an even higher 187 Os/ 188 Os ratio of 0.132 (Brandon et al 2005).…”

Section: Siderophile Elements In Earths Mantlementioning

confidence: 83%

“…[Note that external ±2 sigma precision on the 187 Os/ 188 Os ratio is within the size of each individual data point in the histogram (Brandon et al 2005).] Mars primitive upper mantle appears to have an even higher 187 Os/ 188 Os ratio of 0.132 (Brandon et al 2005). The Earth's mantle 187 Os/ 188 Os ratio overlaps anhydrous ordinary chondrites and is distinctly higher than anhydrous enstatite chondrites, while the Martian mantle is higher than all common meteorite types.…”

Section: Siderophile Elements In Earths Mantlementioning

confidence: 87%

Origin of water on the terrestial planets

Drake

Campins

2005

Proc. IAU

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Abstract. We examine the origin of water in the terrestrial planets. We list various geochemical measurements that may be used to discriminate between different endogenous and exogenous sources of water. Late stage delivery of significant quantities of water from asteroidal and cometary sources appears to be ruled out by isotopic and molecular ratio considerations, unless either comets and asteroids currently sampled spectroscopically and by meteorites are unlike those falling to Earth 4.5 Ga ago or our measurements are not representative of those bodies. The dust in the accretion disk from which terrestrial planets formed was bathed in a gas of H, He and O. The dominant gas phase species were H 2, He, H2O, and CO. Thus grains in the accretion disk must have been exposed to and adsorbed H2 and water. We examine the efficacy of nebular gas adsorption as a mechanism by which the terrestrial planets accreted "wet". A simple model suggests that grains accreted to Earth could have adsorbed 1 -3 Earth oceans of water. The fraction of this water retained during accretion is unknown, but these results suggest that at least some of the water in the terrestrial planets may have originated by adsorption.

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Re-Os isotopic systematics and platinum group element composition of the Tagish Lake carbonaceous chondrite

Cited by 63 publications

References 69 publications

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

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

Osmium isotope systematics of ureilites

Origin of water on the terrestial planets

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