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Noble gas state in the mantle
Author(s) -
Ozima Minoru
Publication year - 1994
Publication title -
reviews of geophysics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 8.087
H-Index - 156
eISSN - 1944-9208
pISSN - 8755-1209
DOI - 10.1029/94rg01875
Subject(s) - mantle (geology) , hotspot (geology) , geology , basalt , mantle wedge , geochemistry , radiogenic nuclide , mantle plume , mantle convection , volcanic rock , noble gas , transition zone , volcano , earth science , subduction , geophysics , lithosphere , chemistry , paleontology , organic chemistry , tectonics
Noble gas elemental and isotopic data on mantle‐derived materials such as mid‐ocean ridge basalt (MORB), hotspot volcanics, diamonds, and mantle xenoliths published up to August 1993 are reviewed critically. Characteristic features of the mantle‐derived materials, which are important in evaluating the significance of the data, are discussed. We choose MORB glasses, hotspot volcanics, mantle xenoliths, and diamonds as the sources to infer the noble gas state in the mantle: MORB and hotspot volcanics to represent the modern depleted and the less degassed mantle, and diamonds to represent the ancient mantle. Because of various fractionation processes, the elemental abundance data obtained from the mantle‐derived materials is unlikely to constrain the noble gas composition of the mantle, except for the systematic enrichment of the heavier noble gases relative to air. On the other hand, apart from the secondary addition of radiogenic components such as 4 He, 21 Ne, 40 Ar, 129 Xe, and 131–136 Xe, the noble gas isotopic compositions deduced from the mantle‐derived materials can provide useful information as to the values in the mantle; a best estimate of the mantle noble gas state is presented.