Basalts upper mantle

Figure 1.164. Distribution of Cenozoic basalts and active rift systems in the northeast China region. Arrows indicate the horizontal convective current in the upper mantle associated with the upwelling of the asthenosphere beneath the region. A Baikal Rift B Shanxi Graben C Tancheng-Lujiang Fault D Okinawa Trough (Tatsumi et al., 1990).

Edwards R, Sedwick PN, Morgan V, Boutron CF, Hong S (1998) Iron in ice cores from Law Dome, east Antarctica implications for past deposition of aerosol iron. Ann Glaciol 27 365-370 Filer JM (2001) Oxygen isotope variations of basaltic lavas and upper mantle rocks. Rev Mineral Geochem 43 319-364... 

Mantle-derived basalts, on the other hand, have a relatively uniform composition with 8 Li values of 4 2%o (Tomaszak 2004 Elliott et al. 2004). The continental crust generally has a lighter Ei isotope composition than the upper mantle from which it was derived (Teng et al. 2004). Considering the small Li isotope fractionation at high temperature igneous differentiation processes (Tomaszak 2004), pristine... 

Element (Cosmic) (relative to 0=466,000) (ppm) Average Crust (ppm) Oceanic Crust (ppm) Upper Mantle (ppm) Total Earth (ppm) HighTi basalt (ppm) Green glass (ppm) Viking I lander (Chryse) (ppm) SNC meteorite (ppm) Vega 2 lander (ppm)... 

In large part, this ability of anhydrous basaltic eclogites to seismically blend into an ultramafic mantle arises from the behavior of elastic moduli in pyroxenes. In the shallowest upper mantle, orthopyroxene is —6% slow in Vp relative to olivine and about equal in Vj. However, the bulk... 

Schiano P., Birck J.-L., and Allegre C. J. (1997) Osmium-strontium-neodymium-lead isotopic covariations in midocean ridge basalt glasses and the heterogeneity of the upper mantle. Earth Planet. Sci. Lett. 150, 363-379. 

Girod M., Dautria J. M., and Giovanni R. D. (1987) A first insight into the constitution of the upper mantle under the Hoggar area (Southern Algeria) the Iherzolite xenoliths in the alkali-basalts. Mantle Xenoliths 77, 66—73. 

Saal A. E., Hauri E. H., Langmuir C. H., and Perfit M. R. (2002) Vapour undersaturation in primitive mid-ocean-ridge basalt and the volatile content of Earth s upper mantle. Nature 419, 451-455. 

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