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ACCRETE: A study of continental growth |
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Eos, Transactions American Geophysical Union,
Volume 72,
Issue 28,
1991,
Page 297-304
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摘要:
The recognition of terranes and terrane accretion has fundamentally changed the way we view the development of continental crust. The terrane concept originated from studies of the western Cordillera of North America, where it was demonstrated in the 1970s that microplates had travelled substantial distances before being amalgamated to cratonic North America. Since these early studies, the terrane concept has been widely applied to older orogenic belts, including the Appalachians and most of the Precambrian shields.Despite the acceptance of the terrane concept, a number of fundamental questions remain regarding the process of terrane accretion and its interaction with transform faulting and igneous and metamorphic events. Still not fully understood are: the coupling processes of mantle with deeper crust, and of deeper crust with upper crust; how pieces of continental crust with different histories respond to juxtaposition; the mechanism of the Mono's formation; and the behavior of fluids (melt and aqueous) with the changing stress field during accretion.
ISSN:0002-8606
DOI:10.1029/EO072i028p00297-01
年代:1991
数据来源: WILEY
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2. |
Boosting the U.S. economy with basic research |
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Eos, Transactions American Geophysical Union,
Volume 72,
Issue 28,
1991,
Page 298-299
Lynn Teo Simarski,
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摘要:
How healthy is U.S. basic research, and how can research improve the country's position in the global marketplace? Such questions were explored at a hearing held on June 20 by the House Science Committtee's subcommittee on science. Much of the outside witnesses' testimony called for better links between government, industry, and universities to improve the research enterprise.Erich Bloch, former director of the National Science Foundation and currently a Council on Competitiveness fellow, testified that the United States is slipping as a technological leader not because it lags in science and basic research, but because “we are trailing badly in our ability to translate basic research results and insights into commercial products
ISSN:0002-8606
DOI:10.1029/90EO00231
年代:1991
数据来源: WILEY
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3. |
Last interglacial in Arctic and Subarctic |
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Eos, Transactions American Geophysical Union,
Volume 72,
Issue 28,
1991,
Page 299-299
John Matthews,
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摘要:
An international group of 30 Quaternary scientists studying the last interglacial in the Arctic met recently to share regional information and to begin the compilation of paleoclimatic information on a hemispheric scale. The NATO Advanced Studies Workshop was held in Hanstholm, Denmark.The last interglacial (s.s.) has been identified at sites across the Arctic, as have other discrete intervals later in stage 5. The development of hemispheric data sets requires international programs that foster the exchange of field‐based paleoclimate data and increased communication between field researchers and the modeling community. Toward that goal, LIGA (The Working Group on the Last Interglacial in the Arctic and Subarctic) was formed to foster the development of a global‐scale data base and to serve as an interface between field‐based Quaternary scientists and ongoing regional programs addressing the field record of the last interglacial (for example, PONAM, CELIA, SOVPEC, PALE), and the climate‐modeling co
ISSN:0002-8606
DOI:10.1029/90EO10231
年代:1991
数据来源: WILEY
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4. |
Toward a standardized definition of geomagnetic sudden impulses and storm sudden commencements |
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Eos, Transactions American Geophysical Union,
Volume 72,
Issue 28,
1991,
Page 300-300
Y. Kamide,
J. A. Joselyn,
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摘要:
In an attempt to resolve some ambiguity in defining geomagnetic sudden impulses (Sis) and storm sudden commencements (SSCs) using the existing phenomenological definition (see, for example,Mayaud and Romana[1977];Mayaud[1980]),Joselyn and Tsurutani[1990] recently constructed a scheme in which SSCs are a subset of Sis, depending on the magnitude of subsequent geomagnetic activity. For quantitative application, they have proposed that an SI be specified as a sharp change (at least 10 nT in 3 minutes or less) observed nearly simultaneously (within a few minutes) in either component of the horizontal magnetic field at globally spaced observatories near 20° geomagnetic latitude. In addition, SSCs are those Sis followed within 24 hours by an hourlyDstindex of at least −50 nT. Because theDstindex is not readily available, the recommended provisional alternative indicators are a 3‐hourly Kp index of 5 or more and a half‐daily a a index of 60 or more.Joselyn and Tsurutani[1990] have recommended these new quantitative definitions of the two terms (Sis and SSCs) for open disc
ISSN:0002-8606
DOI:10.1029/90EO20231
年代:1991
数据来源: WILEY
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