Noble gases in pillow basalt glasses from the northern Mariana Trough back-arc basin
Abstract
Noble gas concentrations and isotopic compositions have been measured in eight samples of pillow basalt glasses collected from seven different localities along 250 km of the Mariana Trough spreading and rifting axis. The samples have uniform and mid-ocean ridge basalt (MORB)-like ^(3)He/^(4)He values of 9–12 × 10^(–6) (6.4–8.6 times atmospheric) despite large variations in 4He. Concentrations of the noble gases Ne, Ar, Kr, and Xe show much smaller variations between samples, but larger variations in isotopic compositions of Ne, Ar, and Xe. Excess radiogenic ^(21)Ne is observed in some samples. ^(40)Ar/^(36)Ar varies widely (atmospheric to 1880). Kr is atmospheric in composition for all samples. Some samples show a clear excess ^(129)Xe, which is a well-known MORB signature. Isotopic compositions of the heavier noble gases (Ar, Kr, and Xe) in some samples, however, show more atmospheric components. These data reflect the interaction of a MORB-like magma with an atmospheric component such as seawater or of a depleted mantle source with a water-rich component that was probably derived from the subducting slab.
Additional Information
© 1998 Wiley. Accepted for publication February 1998. We would like thank Dr Yayoi Miura of Earthquake Research Institute, University of Tokyo for help with analytical work. Thanks also to Dr Jongman Lee for analysing the major element composition of D1009 and D1010. Samples collected during the Tunes 7 expedition were done with the support of the US National Science Foundation.Additional details
- Eprint ID
- 51079
- DOI
- 10.1111/j.1440-1738.1998.00204.x
- Resolver ID
- CaltechAUTHORS:20141030-131816370
- NSF
- Created
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2014-10-30Created from EPrint's datestamp field
- Updated
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2021-11-10Created from EPrint's last_modified field