Geology/geochemistry mantle

REEs are classified as lithophiles and are partitioned into the earth s crust and mantle. The name rare earths originated over a century ago when the elements were first identified in minerals that, at the time, were rare. The elements are actually distributed widely over the earth and relatively accessible on the earth s surface. For a comprehensive description of REE geology, geochemistry, and natural abundances, see Geology, Geochemistry, and Natural Abundances of the Rare Earth Elements. In 2010, the United States Geological Survey (USGS) estimated that there were REE reserves of 110 million metric tons (mt). The static depletion index, the ratio of reserves to present-day production, for REEs is approximately 870 years. Thus, the primary immediate consideration is whether REE production can match demand, and particularly whether it will be possible to increase the use of dysprosium and neodymium in wind turbines and the batteries of electric vehicles. 

Turner S, Hawkesworth C (1998) Using geochemistry to map mantle flow beneath the Lau Basin. Geology 26 1019-1022... 

Lithium isotope geochemistry is characterized by a difference close to 30%c between ocean water (5 Li + 31%c) and bulk silicate earth with a 8 Li-value of 3.2%c (Seitz et al. 2007). In this respect lithium isotope geochemistry is very similar to that of boron (see p. 45). The isotopic difference between the mantle and the ocean can be used as a powerful tracer to constrain water/ rock interactions (Tomaszak 2004). Figure 2.6 gives an overview of Li-isotope variations in major geological reservoirs. 

The major aim of mantle geochemistry has been, from the beginning, to elucidate the structure and evolution of the Earth s interior, and it was clear that this can only be done in concert with observations and ideas derived from conventional field geology and from geophysics. The discussion here will concentrate on the chemical structure of the recent mantle, because the early mantle evolution and dynamics and history of convective mixing are treated in Chapters 2.12 and 2.13. 

Patchett P. J. (2003) Provenance and crust-mantle evolution studies based on radiogenic isotopes in sedimentary rocks. In Geochemistry of Sediments and Sedimentary Rocks Evolutionary Considerations to Mineral Deposit—Forming Environments, Geological Association of Canada GEOtext (ed. D. R. Lentz). St. John s, Nfld, vol. 5, pp. 89-97. 

ViuoEN, M. J. ViuoEN, R. P. 1969. The geology and geochemistry of the lower ultramafic unit of the Onverwacht Group and a proposed new class of igneous rocks. In Upper Mantle Project. Geological Society of South Africa, Special Publication, 2, 55-85. 

One of the fundamental difficulties with the whole mantle convection model is that geochemical heterogeneities cannot be sustained over geological timescales. And yet, observations from trace element and isotope geochemistry show that the mantle is and has... 

Chuan RL, Palais J, Rose WI, Kyle PR (1986) Huxes, sizes, morphology, and compositions of particles in the Mt. Erebus volcanic plume, December 1983. J Atmos Chem 4 467-477 Clague DA, Frey FA (1982) Petrology and trace element geochemistry of the Honolulu Volcanics, Oahu Implications for the oceanic mantle below Hawaii, J. Petrol. 23(3) 447-504 Cole JW, Ewart A (1968) Contributions to the volcanic geology of the Black Island, Brown Peninsula, and Cape Bird areas, McMurdo Sound, Antarctica. New Zealand J Geol Geophys ll(4) 793-828... 

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