Scarsi, P. and Scarsi, L. (2000) 3He/4He isotopic ratio characterization of the Polynesian region: the society and upper Cook-Austral chains. Il nuovo cimento C, 23 C (6). pp. 621-634. ISSN 1826-9885
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Abstract
We report the result of a systematic survey of the helium isotopic composition for basaltic rocks from the Polynesian region. The database covering the Society chain lists 79 entries deriving from experiments carried out at SIO (Scripps Institution of Oceanography, University of California San Diego, CA, USA) following the procedure of crushing on-line with an 8 minute single step; data for the Cook-Austral islands are taken from the literature. The 3He/4He value distribution shows an intrinsic dispersion s between 1.1 and 1.4 times RA (RA= 3He/4He in Air = 1.3931026) and appears sensibly uniform over the area explored, clearly independent from the variation of age (0 to 20 My) along the dorsal of the Island chains. The difference appearing between the mean value obtained for the Society (R/RA = 6.361) and the Cook-Austral (R/RA = 7.361.4) is not appreciable within the “natural” dispersion. The values obtained are substantially lower than the Pacific MORB (R/RAA8.7 RA). No evident correlation appears in the general picture between the helium data and the other radiogenic isotopes interpreted as tracers for possible heterogeneity in the mantle.
| Item Type: | Article |
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| Uncontrolled Keywords: | Isotopic composition/chemistry ; Atomic masses, mass spectra, abundances and isotopes ; Normal phase of liquid 3He |
| Subjects: | 500 Scienze naturali e Matematica > 550 Scienze della Terra |
| Depositing User: | Marina Spanti |
| Date Deposited: | 09 Mar 2020 16:11 |
| Last Modified: | 09 Mar 2020 16:11 |
| URI: | http://eprints.bice.rm.cnr.it/id/eprint/13988 |
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