Abyssal peridotite osmium isotopic compositions from cr-spinel
نویسندگان
چکیده
منابع مشابه
Ancient recycled mantle lithosphere in the Hawaiian plume: Osmium–Hafnium isotopic evidence from peridotite mantle xenoliths
The Emperor Seamount-Hawaiian island chain is thought to originate from melting of a heterogeneous mantle plume, but the composition of the plume has always been inferred from the compositions of the erupted lavas. It has been suggested that recycled (i.e. previously subducted) basaltic oceanic crust (with or without sediments) is part of this plume and responsible for the enriched isotopic com...
متن کاملOxygen Isotopic Compositions and Degree of Alteration of Cr Chondrites
Although hydrously altered, CR chondrites are among the most primitive samples of the solar nebula because of no evidence for thermal or shock metamorphism [1], high presolar grain abundances [2], and perhaps because of their solar refrac-tory lithophile/Mg ratios [3]. Previous O-isotope measurements showed that CR chondrites form a mixing line of slope ~ 0.7 with a rather large scatter [4]. We...
متن کاملMagnesium isotopic compositions of olivine, spinel, and hibonite from the Murchison carbonaceous chondrite
The Mg isotopic compositions of olivine, spinel, and hihonite from the Murchison carbonaceous chondrite have been determined by secondary ion mass spectrometry. The olivines exhibit only marginal effects. They have no detectable intrinsic mass fractionation; however, after correcting for mass fractionation, the mean residual 26Mg/24Mg for the five grams is slightly in excess of the terrestrial ...
متن کاملبررسی شیمی اسپینل و الیوین و تعیین محیط زمین ساختی پریدوتیت‌های افیولیت شمال‌غرب پیرانشهر، شمال‌غرب ایران
According to the olivine and spinel chemistry, two types of peridotite were identified from west north Piranshahr ophiolite. Peridotite rocks are classified based on chemistry of spinel and olivine. Average number of Cr in spinels (Cr#[(100*Cr/(Cr+Al))]) and Mg-number (Mg#[100*Mg/(Mg+Fe)]) in dunite are 0.63 and 0.51 respectively. In harzburgite, Cr# is 0.33 and Mg# is 0.67 and in spinel from s...
متن کاملBulk Chemical and Isotopic Compositions of Spinel-, Hibonite-rich Spherules: Clues to Their Origin
Introduction: Melilite-free, spinel-, hibonitebearing spherules, a major type of refractory inclusion in CM2 chondrites, consist of phases that are predicted by thermodynamic calculations to condense from a cooling gas of solar composition but are not predicted to coexist with each other. Throughout updates and additions to the data base over the years, calculations [e.g. 1-3] consistently show...
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ژورنال
عنوان ژورنال: Geochemistry, Geophysics, Geosystems
سال: 2002
ISSN: 1525-2027
DOI: 10.1029/2001gc000161