摘要:

The D/H ratios and the13C/12C ratios of acid‐insoluble organic matter of 4 meteorites, Ochansk (H4), Plainview (H5), Gladstone (H6) and Odessa (IA), were measured, δD values for hydrogen extracted by stepwise combustion were negative, down to −280‰. δ13C values were also negative except in the case of the carbon coming off at the highest temperature steps for Plainview and Odessa meteorites. The concentrations of13C‐rich carbon were 3‐5 orders of magnitude smaller than those found in Murchison meteorite, suggesting that relic grains of stellar condensates were mostly destroyed in the meteorit

ISSN:0094-8276    

DOI:10.1029/GL012i002p00073

年代:1985

数据来源: WILEY

摘要:

We have calculated the regional stress field in the Indian plate, implementing dependence of slab pull and ridge push on the age of the oceanic lithosphere in the finite element procedure. The high level of the calculated stress field (order of a few kbar) and the dominance of compression in the plate are consequences of the unique dynamic situation of the present‐day Indian plate. The calculated stress field explains the concentration of intraplate deformation in the region of the Ninetyeast Ridge and yields insight into the variations in stress directions in the Australian continen

ISSN:0094-8276    

DOI:10.1029/GL012i002p00077

年代:1985

数据来源: WILEY

摘要:

It has long been argued, on the basis of paleomagnetic data derived from Devonian, Carboniferous and Permian lithological units from eastern North America that a sinistral megashear of Carboniferous age parallels and lies within the faults delimiting the Appalachian‐Caledonian chains. Recent paleomagnetic studies in the northern Appalachians have cast doubt on the models of a Carboniferous offset. The geologic evidence suggests that only a small amount of dextral (and not sinistral) strike slip has occurred on faults which are parallel with pre‐Acadian paleogeographic realms. The purpose of this paleomagnetic study is to test the validity of the proposed left‐lateral motion at one of the sites of its presumed passage in central New Brunswick. Six sites (80 oriented specimens) in Carboniferous red beds and volcanics were collected on both sides of the Fredericton Fault and other parallel faults. After AF and thermal cleaning, the mean direction of magnetization is 158° + 38°; the fold test is indecisive. The corresponding paleopole is 135°E, 21°N and the paleolatitude 20°S. The paleopole positions and paleolatitudes are not significantly different on either side of the Fredericton fault and no left‐lateral motion was detected by paleomagnetic means. As no such motion was detected in south‐central New Brunswick and Newfoundland, it is possible but unlikely that it took place in northern New Brunswick and in the western Gaspé Peninsula. This contribution is useful in discussing possible mo

ISSN:0094-8276    

DOI:10.1029/GL012i002p00081

年代:1985

数据来源: WILEY

摘要:

Longitudinal and shear wave velocities have been measured at 2 kHz and 200 kHz. The measurements were made in a granite as a continuous function of partial water saturation and effective pressure. The pore space of the granite consists of micro‐cracks. The low frequency results compare favorably to the low frequency limit of poroelastic theory. Poroelastic theory assumes that the pore space is connected. On the other hand, the ultrasonic results are better described by effective medium scattering theories: the self‐consistent and the average T‐matrix approximations. Each of these theories assume that the microcracks are not conn

ISSN:0094-8276    

DOI:10.1029/GL012i002p00085

年代:1985

数据来源: WILEY

摘要:

The vapor pressure of ozone has been measured at liquid argon temperatures. At the normal boiling point of argon (−185.9°C) an ozone pressure of 4.05 × 10−2Torr was obtained with an accuracy of ±1.5%. Increases and decreases in liquid argon temperatures raised and lowered the ozone vapor pressure, respectively. During the vapor pressure measurements the purity of ozone was monitored with a mass spectrometer. The proposed ozone standard will considerably improve the calibration of experiments for atmospheric research, the determination of absorption cross sections and other laboratory ozone s

ISSN:0094-8276    

DOI:10.1029/GL012i002p00089

年代:1985

数据来源: WILEY

摘要:

The surface chemistries of three particulate samples collected from the lower stratosphere have been determined using a Scanning Auger Microprobe (SAM). These samples are typical of the most abundant natural and anthropogenic particles observed within the stratosphere in the>2µm diameter size fraction. Successive sputtering and analysis below the first few adsorbed monolayers of all particles shows the presence of a thin (<150A) sulfur layer. These sulfur regions probably formed by surface reaction of sulfur‐rich aerosols with each particle within the stratosphere. Settling rate calculations show that a typical sphere (10µm diameter) may reside within the aerosol layer for ∼20 days and thus, provide a qualitative guide to surface sulfur reaction

ISSN:0094-8276    

DOI:10.1029/GL012i002p00093

年代:1985

数据来源: WILEY

摘要:

An experiment was operated on several space shuttle missions to provide spatial and spectral distributions of a ram glow associated with the orbiter. The most recent data featured resolved spectrum and imagery of the glow with spectroscopic resolution of 34 Å FWHM between 4000 and 8000 Å. The spectrum of the glow on the shuttle tail pod could be clearly separated from spectrum of the reflected light from the orbiter. Analysis and comparison have been performed which strongly suggest the emission originates from recombination continuum of NO2. Both fast recombination (high temperature) and the spectral dependence in lifetime can describe the spectral difference. If the recombined NO2retains 25% of the kinetic energy of the ram OI, the thickness of the glow layer can be explained by the lifetime of NO2(²B1) recombination emissi

ISSN:0094-8276    

DOI:10.1029/GL012i002p00097

年代:1985

数据来源: WILEY

摘要:

The neutral wind pattern over the summer polar cap can be driven by plasma convection to resemble the convection pattern. For a north‐south component of the interplanetary magnetic field Bzdirected southward, the wind speeds in the conducting E‐region can become ∼ 25% of the electric field drift speeds. If convection ceases, this neutral wind distribution can drive a significant polar cap current system for ∼ 6 hours. The currents are reversed from those driven by the electric fields for southward Bz, and the Hall and field‐aligned components of the current system resemble those observed during periods of northward Bz. The current magnitudes are similar to those observed during periods of small, northward Bz; however observations indicate that electric fields often contribute to the currents as much as, or more than, the neut

ISSN:0094-8276    

DOI:10.1029/GL012i002p00101

年代:1985

数据来源: WILEY

摘要:

It is suggested that the flux transfer events (FTE's) observed by ISEE satellites can be the result of multiple X‐line reconnection at the dayside magnetopause, which may be caused by the development of a tearing instability. In the presence of the y‐component of the magnetic field (By) in the transition region of the magnetopause, the tearing instability leads to the interconnection of the geomagnetic field lines and the interplanetary field lines, and hence to the occurrence of FTE's. Twisted field lines and field‐aligned currents are formed as a consequence of the tearing instability. The flow direction of the field‐aligned currents depends on Byand the results are found to be consistent with satellite obser

ISSN:0094-8276    

DOI:10.1029/GL012i002p00105

年代:1985

数据来源: WILEY

摘要:

Recurrent low energy ( ≳0.5 MeV) proton flux enhancements, reliable indicators of corotating plasma interaction regions in interplanetary space, have been observed on the Voyager 1 and 2 and Pioneer 11 spacecraft in the heliographic latitude range 2°S to 23°N and the heliocentric radial range 11 to 20 AU. After a period of rather high correlation between fluxes at different latitudes in early 1983, distinct differences develop. The evolution of the fluxes appears to be related to the temporal and latitudinal dynamics of solar coronal holes, suggesting that information about the latitudinal structure of solar wind stream sources propagates to these distan

ISSN:0094-8276    

DOI:10.1029/GL012i002p00109

年代:1985

数据来源: WILEY