Rare gases,water, and carbon in kaersutites |
| |
| Authors: | Robert J Poreda Asish R Basu |
| |
| Institution: | 1. Isotope Laboratory, Scripps Institution of Oceanography, University of California at San Diego, La Jolla, LA 92093 (U.S.A.);2. Department of Geology, University of Rochester, Rochester, NY 14627 (U.S.A.) |
| |
| Abstract: | Kaersutites from Kakanui, New Zealand and from three localities in the southwestern United States have been analyzed for rare gases, water and carbon to investigate the volatile signature of the sub-continental mantle. This study does not confirm the high 3He/4He and 21Ne/22Ne ratios reported by Saito et al. 1] for the Kakanui kaersutite. Instead, a 3He/4He ratio of 6 RA and atmospheric 21Ne/22Ne ratios were measured which are consistent with our current knowledge of the earth's mantle. A low 40Ar/36Ar of 320 and more than 10?8 cm3/g of 36Ar confirms the argon results of Saito et al. and indicates that significant quantities of 36Ar reside in this portion of the mantle. Kaersutites from the southwestern United States (Arizona) have a heterogeneous helium isotope signature, ranging from 8.8 RA at San Carlos to 0.46 at Hoover Dam. All D/H ratios for the water in kaersutites (?56‰ to ?78‰) represent typical mantle values with no apparent correlation with 3He/4He. The correlation of increasing carbon content (140–400 ppm) with increasing δ13C (?24.5‰ to ?16.7‰) may reflect differences in the proportions of oxidized and reduced carbon in these samples. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
