摘要:

The October 1991Chronologyexpedition to the Endeavour Segment of the Juan de Fuca Ridge sought to exploit shipboard and land‐based radioisotope analyses based on detailed geological observations and comprehensive sampling to determine the absolute ages of an actively venting ridge‐axis hydrothermal field. Samples collected from a 1988 expedition indicated that some of the hydrothermal deposits in this area are unusually rich in barium (Ba) and radium (Ra) and thus extraordinarily amenable to radioisotopic techniques [Stakes and Moore,1991]. An in situ gamma detector was developed to permit mapping of the distribution of radioactive components in the hydrothermal deposits and selection of subsamples that could easily be dated. To obtain samples that represent progressive mineral growth for the entire age of a chimney, we developed the HSTR drill (Figure 1), a diamond‐bit drill to be operated by the submersible

ISSN:0002-8606    

DOI:10.1029/91EO00220

年代:1992

数据来源: WILEY

摘要:

About 80 citizens concerned with the threat of ozone depletion attended a public meeting on June 9 in Charlottesville, Va., to discuss the issue with a panel of six leading ozone experts. Held in conjunction with the Quadrennial Ozone Symposium, the town meeting was videotaped for airing on public broadcast stations this fall. The meeting was aimed at nonexperts, to “get the word out” to the public, said the moderator, journalist Peter Hackes.The lively, sometimes heated discussion showed the public's high awareness and concern over problems associated with ozone depletion. During the nearly 2‐hour meeting topics ranged from the reparability of the ozone layer, to steps the public can take to help mitigate ozone loss, to reports of increased cases of skin cancer due to more ultraviolet radiation reaching the Earth's surface. There were also some claims that ozone depletion is overexaggerated and is a hoax for scientists to get more research fu

ISSN:0002-8606    

DOI:10.1029/91EO00224

年代:1992

数据来源: WILEY

摘要:

NASA's Crustal Dynamics Project (CDP) spearheaded a major scientific and engineering effort over the last decade to develop and apply space geodetic techniques such as Very Long Baseline Interferometry (VLBI) and Satellite Laser Ranging (SLR) to a wide range of problems in the Earth sciences. Major study areas included plate motion, broad scale crustal deformation, polar motion, and variation in the Earth's rotation rate. Observations were initiated all over the world in collaboration with international scientists and agencies, while university and other scientists in this country received funding for research projects utilizing the new data. Numerous accomplishments over the lifetime of the CDP (to be summarized in an upcoming AGU monograph) include an order of magnitude improvement in the accuracy of space geodetic measurements; monitoring variations in the Earth's pole position and rotation rate with astounding resolution, leading to greatly improved understanding of the underlying physics; and demonstration of a remarkable consistency in plate velocities from geodetic (decadal) to geologic (several‐million‐year) time sca

ISSN:0002-8606    

DOI:10.1029/91EO00226

年代:1992

数据来源: WILEY

摘要:

In the seismological community, much effort has been directed recently toward developing a coordinated plan for rapid response to major earthquakes. This topic was the subject of a special interest group at the recent annual meeting of the Incorporated Research Institutions in Seismology (IRIS). Several new and some old ideas concerning a rapid array mobilization plan (RAMP) emerged. IRIS has agreed to set aside initial funding and equipment to deploy five seismic stations in support of approved RAMP initiatives. Although five stations are not sufficient to ensure a successful aftershock deployment, the present high demand for IRIS portable equipment in planned experiments precludes reserving any additional instruments for aftershock studies.

ISSN:0002-8606    

DOI:10.1029/91EO00228

年代:1992

数据来源: WILEY

摘要:

Paleoclimates of Arctic Lakes and Estuaries (PALE) is one of two paleoenvironmental research programs in the overall structure of Arctic System Science (ARCSS), a global change program centered in the Division of Polar Programs of the National Science Foundation. The objectives of PALE are to describe circumarctic patterns of paleoclimatic variations for three time periods (150,000 BP‐present, 20,000 BP‐present, and 2000 BP‐present), based on proxy indicators preserved in circumpolar lake and estuarine sediments; and to identify regional and global processes controlling the observed paleoclimatic changes. A discussion of PALE was published inEos(July 1991), and NSF issued a call for proposals that same month, with six new proposals now funded. Several of these studies will investigate new ways of determining climatic signals in arctic lake sediments or developing methods for improving chronol

ISSN:0002-8606    

DOI:10.1029/91EO00229

年代:1992

数据来源: WILEY

摘要:

The reviewers whose photographs appear below have been cited by editors of AGU's journals for excellence in refereeing. The time and diligence contributed by these reviewers enhance the quality of AGU's journals. The editor's citation recognizes this special service to the Union, and the individuals who are listed below are to be commended for consistantly providing constructive and thoughtful reviews.

ISSN:0002-8606    

DOI:10.1029/91EO10229

年代:1992

数据来源: WILEY

摘要:

The 1992 Spring Meeting was held in Montreal May 12–16 as a joint meeting of AGU, the Canadian Geophysical Union, and the Mineralogical Society of America. This was the largest AGU Spring Meeting ever held with just over 2,900 members in attendance. The increased size of the program was partly a result of a conscious effort by the program committee to build up the Spring Meeting and provide a better balance between the Spring and Fall meetings. The venue of Montreal and activity of the CGU were also factors that helped make this meeting a succes

ISSN:0002-8606    

DOI:10.1029/91EO20229

年代:1992

数据来源: WILEY