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1. |
Reply [to “On mantle carbon flux calculated”] |
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Eos, Transactions American Geophysical Union,
Volume 70,
Issue 1,
1989,
Page 1-3
David J. Des Marais,
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PDF (276KB)
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摘要:
I will address Marty's concern about priority in the publication of 3He‐based estimates for the flux and isotopic composition of mantle carbon (“Who published what, and when?”). I will also discuss our views on the history of mantle/crust exchange.Our analyses of MORB carbon occurred from 1980 to 1986, in collaboration with H. Sakai, J.G. Moore and J. Delaney, and J. Blank. We reported that a13C‐depleted component, released by combustion below 500°C, had been added to the samples after their eruption [Des Marais et al., 1983; Des Marais and Moore, 1984; Sakai et al., 1984]. Essentially all of the carbon released above 500°C derived from the original magma and was isotopically similar, both to the value measured earlier for CO2in MORB vesicles [Pineau et al., 1976; Moore et al., 1977], and also to the average value for the crust. While isotopic comparisons between mantle and crust have indeed “focused the attention of many workers, starting in the 1950s,” the early estimates of mantle carbon were either based on unusual minerals or rocks (e.g. diamonds or carbonatites) whose isotopic composition could not be proved to represent the average upper mantle value, or they were based on analyses that implied (incorrectly) that basalts contain two major, magma‐derived, isotopically distinct carbon components ( −4 to −9 permil, and −20 to −30 permil). Because midocean ridge (MOR) volcanism provides most of the mantle carbon flux, it offers the most representative sample of the upper mantle. Our work, together with H. Craig's measurements of MOR hydrothermal fluids, first showed that carbon isotope discrimination during eruption was less than a few permil, and that, at several ridge sites, the indigenous carbon (not only in MORB vesicles but also in MORB glass) was isotopically quite similar to that of the c
ISSN:0002-8606
DOI:10.1029/EO070i001p00001-03
年代:1989
数据来源: WILEY
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2. |
NASA graduate student grants |
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Eos, Transactions American Geophysical Union,
Volume 70,
Issue 1,
1989,
Page 4-4
Mary Mellott,
George Parks,
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PDF (135KB)
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摘要:
The National Aeronautics Space Administration will award about 80 grants under its Graduate Student Researchers Program (GSRP). The $12,000 fellowships are given for a year and may be renewed; up to $6000 may be given for tuition and travel costs. Students can apply as undergraduates or graduates and must be U.S. citizens. Application deadline for 1989–1990 is February 1.NASA's Office of Space Science and Applications sponsors about half the fellowships; the other 40 are distributed through NASA field centers. OSSA awards are in astrophysics, Earth science, life sciences, microgravity science, Solar System exploration, and space physics. OSSA fellows work at their home universities. Fellows selected by centers spend some time in residence, to use unique research facilities and work with center staf
ISSN:0002-8606
DOI:10.1029/EO070i001p00004-02
年代:1989
数据来源: WILEY
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3. |
Fiftieth William Bowie Medal presented to Hannes Alfven |
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Eos, Transactions American Geophysical Union,
Volume 70,
Issue 1,
1989,
Page 9-10
A.J. Dessler,
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PDF (290KB)
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摘要:
The oldest and most prestigious award of AGU is its Bowie Medal. We recognize and honor a lifetime of momentous achievements in space physics by Hannes Alfvén by naming him our 1988 Bowie Medalist. But more than that, with this award, we honor the underdog, one who has stood up to a powerful scientific establishment, suffered, persisted, and finally prevailed. By making Hannes Alfven our Bowie Medalist, we do more than recognize a worthy recipient—we make ourselves feel good. Our innate sense of justice is indulged. We bask in the self‐satisfied glow that comes from witnessing truth win over the forces that would lead us as
ISSN:0002-8606
DOI:10.1029/89EO00005
年代:1989
数据来源: WILEY
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4. |
Response of Hannes Alfvén |
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Eos, Transactions American Geophysical Union,
Volume 70,
Issue 1,
1989,
Page 10-10
Hannes Alfvén,
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PDF (139KB)
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摘要:
I wish to thank you very much for awarding me the Bowie Medal. I appreciate the motivation for it, which is much more than I deserve. Alex has tried to provide some balance by pointing out that I have not solved all of the problems but have left to some of you to solve what I myself consider to be the most important of all cosmical problems, namely the question of matter‐antimatter symmetry.When Dirac had proved that there was a general matter‐antimatter symmetry, my teacher Oskar Klein claimed that there should be a general symmetry also between the amount of matter and antimatter in the universe. This is not generally accepted. Instead it is believed that, for example, one of our closest stars, Alpha Centauri, consists of matter; Alex put it as due to some sort of normal‐matter chauvinism. The question remains as to whether there exists any scientific reason for this
ISSN:0002-8606
DOI:10.1029/EO070i001p00010
年代:1989
数据来源: WILEY
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