| Инд. авторы: | Sobolev A.V., Hofmann A.W., Jochum K.P., Kuzmin D.V., Stoll B. |
| Заглавие: | A young source for the Hawaiian plume |
| Библ. ссылка: | Sobolev A.V., Hofmann A.W., Jochum K.P., Kuzmin D.V., Stoll B. A young source for the Hawaiian plume // Nature. - 2011. - Vol.476. - Iss. 7361. - P.434-439. - ISSN 0028-0836. - EISSN 1476-4687. |
| Внешние системы: | DOI: 10.1038/nature10321; SCOPUS: 2-s2.0-80052058315; |
| Реферат: | eng: Recycling of oceanic crust through subduction, mantle upwelling, and remelting in mantle plumes is a widely accepted mechanism to explain ocean island volcanism. The timescale of this recycling is important to our understanding of mantle circulation rates. Correlations of uranogenic lead isotopes in lavas from ocean islands such as Hawaii or Iceland, when interpreted as model isochrons, have yielded source differentiation ages between 1 and 2.5 billion years (Gyr). However, if such correlations are produced by mixing of unrelated mantle components they will have no direct age significance. Re-Os decay model ages take into account the mixing of sources with different histories, but they depend on the assumed initial Re/Os ratio of the subducted crust, which is poorly constrained because of the high mobility of rhenium during subduction. Here we report the first data on 87 Sr/86 Sr ratios for 138 melt inclusions in olivine phenocrysts from lavas of Mauna Loa shield volcano, Hawaii, indicating enormous mantle source heterogeneity. We show that highly radiogenic strontium in severely rubidium-depleted melt inclusions matches the isotopic composition of 200-650-Myr-old sea water. We infer that such sea water must have contaminated the Mauna Loa source rock, before subduction, imparting a unique 'time stamp-on this source. Small amounts of seawater-derived strontium in plume sources may be common but can be identified clearly only in ultra-depleted melts originating from generally highly (incompatible-element) depleted source components. The presence of 200-650-Myr-old oceanic crust in the source of Hawaiian lavas implies a timescale of general mantle circulation with an average rate of about 2 (Â ±1) cm yr ĝ̂'1, much faster than previously thought. © 2011 Macmillan Publishers Limited. All Rights Reserved.
|
| Ключевые слова: | strontium; isotopic composition; lava; mantle plume; mantle source; mobility; oceanic crust; olivine; phenocryst; plume; rhenium; seawater; shield volcano; source rock; strontium; sea water; timescale; volcanism; article; controlled study; plume; priority journal; recycling; United States; Iceland; Hawaii [United States]; volcano; United States; sea pollution; sea; subduction; |
| Издано: | 2011 |
| Физ. характеристика: | с.434-439 |