Abstract
Noble gas elemental and isotopic compositions have been measured as well as the abundance of C and its isotopic ratios in 11 glasses from submarine pillow basalts collected from the Mariana Trough. The 3He/ 4He ratios of 8.22 and 8.51 R atm of samples dredged from the central Mariana Trough (∼18°N) agree well with that of the Mid-Ocean Ridge Basalt (MORB) glasses (8.4±0.3 R atm), whereas a mean ratio of 8.06±0.35 R atm in samples from the northern Mariana Trough (∼20°N) is slightly lower than those of MORB. One sample shows apparent excess of 20Ne and 21Ne relative to atmospheric Ne, suggesting incorporation of solar-type Ne in the magma source. There is a positive correlation between 3He/ 4He and 40Ar/ 36Ar ratios, which may be explained by mixing between MORB-type and atmospheric noble gases. Excess 129Xe is observed in the sample which also shows 20Ne and 21Ne excesses. Observed δ 13C values of ∼20°N samples vary from −3.76‰ to −2.80‰, and appear higher than those of MORB, and the corresponding CO 2/ 3He ratios are higher than those of MARA samples at ∼18°N, suggesting C contribution from the subducted slab.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
