摘要:

The Gulf Coast province provides an array of scientific dilemmas ranging from the origin of the gulf itself to the causes and effects of long‐lasting circulation of hot, deep waters throughout the thick sedimentary section. The nature of the underlying crust and superjacent sediments and their contained waters; the precise timing of rifting; depositional history and diagenesis of the sedimentary sequence; fluid dynamics; geochemistry; hydrocarbon generation and migration; thermal history, including unusually high thermal gradient; and the fluid pressure regime in the deep sedimentary section are too poorly understood to permit quantitative analysis of processes that are of enormous scientific and practical importance. The area centered on DeWitt and Victoria counties, Texas, on the southeastern extension of the San Marcos arch, is probably the best location for a deep borehole to investigate these important phenomena and problems. The arch extends southeastward from exposed Grenville‐age basement rocks of the Llano uplift and separates the deep South Texas and Houston embayment salt basins. Seaward of the Llano uplift, highly deformed and slightly metamorphosed rocks of the Ouachita‐Marathon orogen have been intersected beneath Cretaceous sediments. The inferred edge of continental crust underlies an extensive Lower Cretaceous reef trend southeast of known Ouachita orogen rocks. Rapid thickening of Tertiary and possibly of Cretaceous sediments southeast of the shelf edge, together with geophysical indications of a relatively shallow Moho, suggests that “transitional continental crust” underlies sediments basinward of the inferred edge of continental crust. This transitional crust, the ultimate objective for a proposed deep well, could be rifted Grenville basement, buried rocks of the Ouachita trend, an island arc related to the Ouachita trend, or exotic continental basement related to a proto‐South American continent. To achieve optimum results to guarantee adequate basement penetration, a borehole should be designed to penetrate a relatively thin succession of lower Mesozoic synrift, graben‐fill sediments seaward of the shelf edge. Because of expected high temperatures and pressures, new technologies will need to be developed to successfully drill and

ISSN:0002-8606    

DOI:10.1029/88EO01061

年代:1988

数据来源: WILEY

摘要:

Shortly after the beginning of the “space age” with the launching of the first man made object into terrestrial orbit, geospace assumed a fundamental role as a technological resource for all countries, advanced and developing alike. Today, satellite systems for communications, weather prediction, navigation, and remote sensing of natural resources are supporting, in an essential way, many facets of societal operations. We must expect that this trend will continue; for instance, in perhaps less than 3 decades, transatmospheric transportation will be routine and satellite systems will sustain human colonies in space.The medium in which Earth‐orbiting systems operate is hostile. Far from a perfect vacuum, it is made up of high‐temperature gas and corpuscular radiation of varying densities and intensities; these solar‐activity controlled variations can reach proportions dangerous to orbital stability, to electronic systems performance, to shuttle and spaceplane reentry, and to the life of humans in orbit. Dramatic examples of solar‐activity‐induced satellite failures are the unexpected early degradation of the orbit of Skylab due to unusual upper atmosphere heating and the demise of satellite GOES‐5, most probably caused by a large injection of energetic electrons from the outer magnetoshere. The need to predict “weather and climate” in geospace is becoming as important as the need to predict weather and climate in the inhospitable regions on Earth into which industrial activity has moved during the last decades, such as the Arctic and som

ISSN:0002-8606    

DOI:10.1029/88EO01064

年代:1988

数据来源: WILEY

摘要:

The National Science Foundation and the National Aeronautics and Space Administration are exploring the, possibilities of a joint balloon program in Antarctica. Over the years there have been many successful small balloons launched from Antarctica for research on topics such as meteorology, atmospheric chemistry, magnetospheric physics, and astrophysics. Recently, a large balloon (and payload) was successfully launched from McMurdo.In response to this growing interest, NSF hosted a 1‐day workshop on Scientific Ballooning in Antarctica on March 27. This was well received, as evidenced by the attendance of some 40–50 scientists. At a follow‐up meeting on June 14, 1988, attended by P. Wilkness, Division Director, Polar Programs, NSF, and S. Shawhan, Division Director, Space Physics, NASA, it was decided to solicit community input in the form of brief letters (one or two pages). Therefore if you have aspirations for balloon activities in Antarctica within the next few years, please send a brief description of your plans, including scientific objectives, time frame, launch site(s), logistical requirements, budget estimates (excluding logistics), and special needs, if any. Send this material to J . Lynch, Program Manager, Polar Atmospheric Sciences, Division of Polar Programs, National Science Foundation, 1800 G St., N.W., Washington, DC 20550. Send a copy to S. Shawhan, Director, Space Physics Division, NASA Headquarters, Washington, DC

ISSN:0002-8606    

DOI:10.1029/88EO01065

年代:1988

数据来源: WILEY

摘要:

The Gulf Coast province provides an array of scientific dilemmas ranging from the origin of the gulf itself to the causes and effects of long‐lasting circulation of hot, deep waters throughout the thick sedimentary section. The nature of the underlying crust and superjacent sediments and their contained waters; the precise timing of rifting; depositional history and diagenesis of the sedimentary sequence; fluid dynamics; geochemistry; hydrocarbon generation and migration; thermal history, including unusually high thermal gradient; and the fluid pressure regime in the deep sedimentary section are too poorly understood to permit quantitative analysis of processes that are of enormous scientific and practical importance. The area centered on DeWitt and Victoria counties, Texas, on the southeastern extension of the San Marcos arch, is probably the best location for a deep borehole to investigate these important phenomena and problems. The arch extends southeastward from exposed Grenville‐age basement rocks of the Llano uplift and separates the deep South Texas and Houston embayment salt basins. Seaward of the Llano uplift, highly deformed and slightly metamorphosed rocks of the Ouachita‐Marathon orogen have been intersected beneath Cretaceous sediments. The inferred edge of continental crust underlies an extensive Lower Cretaceous reef trend southeast of known Ouachita orogen rocks. Rapid thickening of Tertiary and possibly of Cretaceous sediments southeast of the shelf edge, together with geophysical indications of a relatively shallow Moho, suggests that “transitional continental crust” underlies sediments basinward of the inferred edge of continental crust. This transitional crust, the ultimate objective for a proposed deep well, could be rifted Grenville basement, buried rocks of the Ouachita trend, an island arc related to the Ouachita trend, or exotic continental basement related to a proto‐South American continent. To achieve optimum results to guarantee adequate basement penetration, a borehole should be designed to penetrate a relatively thin succession of lower Mesozoic synrift, graben‐fill sediments seaward of the shelf edge. Because of expected high temperatures and pressures, new technologies will need to be developed to successfully drill and

ISSN:0002-8606    

DOI:10.1029/EO069i033p00788-02

年代:1988

数据来源: WILEY

摘要:

AGU has announced the recipients of the 1988 Robert E. Horton and Maurice Ewing medals. The recipient of the Robert E. Horton Medal for outstanding contributions to the geophysical aspects of hydrology will be Peter S. Eagleson of the Massachusetts Institute of Technology. Eagleson is the immediate Past‐President of AGU.The recipient of the Maurice Ewing Medal for significant original contributions to understanding physical, geophysical, and geological processes in the ocean; and/or significant original contributions to scientific ocean engineering, technology, and instrumentation; and/or outstanding service to marine sciences is Wolfgang H. Berger of the Scripps Institution of Oceanography. The medal is presented jointly by the U.S Navy and AG

ISSN:0002-8606    

DOI:10.1029/EO069i033p00794

年代:1988

数据来源: WILEY

摘要:

On February 2–5, 1988, 90 space physicists met at Yosemite National Park to discuss theoretical and instrumentation aspects of solar system plasma physics. The participants were divided nearly equally between those involved in the plasma physics of planetary, Earth, and cometary magnetospheres and those involved in the field of solar physics. This dichotomy led to a significant amount of cross fertilization of ideas between the two groups. In retrospect the exchange would have been facilitated by introductory tutorial lectures on the outstanding problems extant in the two subjects. Nonetheless, as the conference progressed, with plenty of time for informal discussion, the two groups found that not only are the Sun and the various planetary magnetospheres inextricably linked, as expected, via the solar wind, but also that they are characterized by a number of the same physical phenomena. For example, one phenomenon, the cyclotron maser resonance, was suggested to be responsible for Type III solar radio bursts. The same phenomenon is generally accepted to cause auroral kilometric radiation in the Earth's magnetosphere. Lively discussions were also held on collisionless shocks, which are important phenomena in the solar atmosphere, the solar wind, and in the interaction of the solar wind with planetary magnetospheres. The analogy of solar flares and magnetospheric substorms and the role of magnetic reconnection in solar and magnetospheric physics were also topics of mutual interest which spawned vigorous discussion as a result of the different perspectives of the two communitie

ISSN:0002-8606    

DOI:10.1029/88EO01068

年代:1988

数据来源: WILEY