Strontium mantle geochemistry

U and U, and this is in part responsible for the more complex isotopic relationships displayed by lead isotopes in comparison with the systematics of strontium, neodymium, hafnium, and osmium isotopes. The mantle geochemistry of noble gases, although of course an integral part of mantle geochemistry, is treated in Chapter 2.06. 

In the early days of mantle geochemistry, the composition of the bulk silicate earth, also called primitive mantle (i.e., mantle prior to the formation of any crust see Chapter 2.01) was not known for strontium isotopes because of the obvious depletion of rubidium of the Earth relative to chondritic meteorites (Gast, 1960). 

Menzies M. A. and Murthy V. R. (1978) Strontium isotope geochemistry of alpine tectonite Iherzolites data compatible with a mantle origin. Earth Planet. Sci. Lett. 38, 346-354. 

Hemond C, Condomines M, Fourcade S, Allegre CJ, OskarssonN, Javoy M (1988) Thorinm, strontium and oxygen isotopic geochemistry in recent tholeiites from Iceland crastal influence on mantle-derived magmas. Earth Planet Sci Lett 87 273-285... 

In an extensive review of the geochemistry of volatile-bearing minerals in mantle xenoliths, Ionov et al (1997) have pointed out that although minerals such as mica, amphibole, and apatite are often referred to as hydrous, in many cases they have very low H2O contents (Boettcher and O Neill, 1980). In such cases, these minerals may have significant amounts of fluorine, chlorine and CO2. Mica, amphibole, and apatite, together with the oxide phases, are important hosts for titanium, potassium, rubidium, strontium, barium, and niobium (Table 9). 

Nd/ Nd low 8nneodymium isotopic compositions, the remarkable aspect of the frequency distribution for CLM as a whole is that the pronounced mode is within 58 units of bulk Earth and the mean 8j,jd value is 1.8. On this basis, the dominant neodymium isotopic characteristic of CLM is not enriched but is close to, or slightly more depleted than bulk Earth. Of course, if Depleted Mantle is used as a reference point then the CLM mode is enriched. The strontium isotope frequency distribution has a long tail out to very radiogenic ( enriched ) compositions but the mean Sr/ Sr is 0.7047 very close to estimates of bulk Earth. It is important to bear in mind that this statistical view of CLM geochemistry could... 

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