摘要:

The electrostatic field in the altitude range 10 to 30 km was measured. In a field radiosonde which is based on the collector principle large disks were used in place of the usual radioactive probes, and many of the disadvantages of probes were eliminated. Results of three balloon releases made from Melbourne, Australia, showed that the potential gradient decreased from about 4 v/m at 10‐km altitude to about 0.5 v/m at 25 km. The transient behavior of the apparatus provides a means also of measuring the conductivity of the air, though no results on conductivity have been obtained so fa

ISSN:0148-0227    

DOI:10.1029/JZ069i010p01947

年代:1964

数据来源: WILEY

摘要:

Experimental measurements at 5‐cm wavelength show that the backscattering cross sections of ice spheres approximately 2 cm in diameter which are coated with a mixture of water and ice (‘spongy’ coating) are 3 to 4 db above that of the equivalent all‐water spheres and at least 10 db above that of the equivalent solid ice spheres. Thus it is shown that the extremely large reflectivity factor at 3‐cm wavelength (Ze= 107mm6m−3) observed for hailstones can be accounted for with concentrations of only about 3 g m−3of 1‐cm‐diameter hailstones which have a spongy coating. Both the falling away of the spongy coating upon melting and its freezing upon being lifted in the updraft will cause reductions in reflectivity, thereby producing the maximum reflectivity observed at an intermediate level of the storm. The existence of spongy ice allows the surface and radar observations of hailstorms to be explained without any of the physically implausible assumptions of pr

ISSN:0148-0227    

DOI:10.1029/JZ069i010p01955

年代:1964

数据来源: WILEY

摘要:

An automatic standard magnetic observatory (ASMO) has been built and operated with excellent results. The observatory uses a rubidium total field‐intensity detector. The detector is placed at the center of two mutually perpendicular pairs of coils which control bias fields in a plane perpendicular to the mean magnetic field vector. Use of the bias fields permits a determination of the magnetic components. A preliminary calibration procedure involving reversals of the bias fields and a mechanical rotation of the coil system eliminates uncertainties in coil geometry. Measurements are automatically recorded in digital form so that the precise value of each magnetic component and all of the usual statistical analyses can be computed automatically. Tests made so far indicate that the statistical results from the new observatory are at least as accurate as those from normal observatories. Having the data in digital form simplifies subsequent analysis of the data for research purpose

ISSN:0148-0227    

DOI:10.1029/JZ069i010p01963

年代:1964

数据来源: WILEY

摘要:

Although sea water is a relatively concentrated aqueous solution, Walden's rule still appears to be applicable to the variation of its electrical conductance with temperature. The variation of conductance with pressure, however, depends on the second power of viscosity rather than the first power as given by Walden's rule. The reduction of the sizes of hydrated ions is believed to be responsible. A fit of the observed pressure dependence of the electrical conductance of 35 per mil salinity sea water at 25°C is obtained if the value is corrected at 1 atmosphere for (a) the increased dissociation of MgSO4, (b) the decrease in the solution volume, and (c) the changes in viscosity. The last correction appears in the form of the second power of the reciprocal of the relative viscosity

ISSN:0148-0227    

DOI:10.1029/JZ069i010p01971

年代:1964

数据来源: WILEY

摘要:

Simultaneous determinations of U and Th abundances are obtained in the Orgueil (type I) carbonaceous chondrite, the Mokoia and Karoonda olivine‐pigeonite chondrites, and the Hvittis enstatite chondrite by neutron activation methods. The olivinepigeonite chondrite abundances are similar to ordinary (i.e. hypersthene and bronzite) chondrite values reported by other workers, but the Hvittis enstatite chondrite is depleted in both U and Th. The Orgueil carbonaceous chondrite is enriched in U relative to the ordinary chondrites but agrees with new calculations by Hoyle and Fowler of U abundances in primitive solar material. The Th abundance in Orgueil is also enriched but is not as high as the calculated values. Th/U ratios increase and U abundances decrease from type I carbonaceous chondrites through olivine‐pigeonite and ordinary chondrites to the Hvittis enstatite chondrite. If the chondrites are related in a similar sequence by way of increasing temperatures and states of reduction, U is apparently lost more readily than Th as a result of these processes. The bearing of these new data on the radioactive heat production in earth models based on the various chondrite types is also discus

ISSN:0148-0227    

DOI:10.1029/JZ069i010p01979

年代:1964

数据来源: WILEY

摘要:

Neutron activation determinations of U and Th abundances in two diogenites (Ellemeet, Johnstown), a howardite (Binda), a eucrite (Moore County), a nakhlite (Nakhla), and an angrite (Angra dos Reis) are in agreement with the hypothesis that these achondrites have formed as a result of differentiation of an ordinary chondrite magma. The Bishopville enstatite achondrite (aubrite) has U and Th abundances consistent with an origin directly from an enstatite chondrite of the Hvittis type by simple melting and gravity separation of metal and sulfide phases.

ISSN:0148-0227    

DOI:10.1029/JZ069i010p01989

年代:1964

数据来源: WILEY

摘要:

Solutions in contact with solid amorphous silica at room temperature tend to become supersaturated. Experiments carried out over long periods of time show that steady states of supersaturation, 120 to 170 ppm, may persist for months. Eventually, however, the colorimetrically detectable dissolved silica in contact with silica gel decreases to about 115 ppm. Dissolved silica in waters collected from hot springs (p;H range 6.0 to 8.5) also slowly polymerizes and approaches 115 ppm. Extrapolation to 25°C of solubility data taken at high temperatures also yields a value of about 115 ppm for the solubility of amorphous silica. It is concluded that in nearly neutral solutions 115 ppm is the solubility of amorphous silica at 25°C, the differential heat of solution, ΔH, is 3.35 kcal/mole, and the standard free energy of solution, ΔF°25°C, is approximately 3.7 kcal

ISSN:0148-0227    

DOI:10.1029/JZ069i010p01995

年代:1964

数据来源: WILEY

摘要:

Continuous seismic profile measurements made over several thousand kilometers of traverse in the Argentine basin reveal a greater accumulation of sediments than has been found in any other ocean basin. Horizontally layered sediments attain a thickness of more than 2500 meters and overlie a typically rough basement. The basement, which has an average topographic amplitude of 400 m and a wavelength of 15 km, was traced from the base of the continental rise to exposures on the mid‐Atlantic ridge. A unique sub‐bottom reflector, designated reflector A, was observed to be the most prominent and continuous of the sedimentary reflecting horizons. The coherent bubble pulse pattern of the reflections from reflector A and especially from the ocean floor are in marked contrast to the highly reverberant and noncoherent echoes produced by the basement. Reflector A is generally conformable to the topography of the ocean floor and is unaffected by topographic expression in the basement. One region contains a crater‐like sedimentary structure about 350 km in diameter but too shallow to affect the basement relief. It is concluded that most of the basin sediments were derived from the continent and transported to the deep ocean floor by some process which deposited them as smooth, nearly horizontal layers. The structure of the sediments suggests that the basin has been exceptionally free from deformation, excluding broad crustal warping, throughout the period of deposition of the sedi

ISSN:0148-0227    

DOI:10.1029/JZ069i010p02003

年代:1964

数据来源: WILEY

摘要:

On December 7–9, 1962, a small flank eruption occurred on the upper part of the east rift zone of Kilauea volcano. The six eruptive fissures, which show a right‐offset en echelon pattern, extend more than 2 miles from Aloi crater eastward to the west slope of Kane Nui o Hamo. The total volume of erupted lava was small (426,000 cubic yards) and much of it, which ponded temporarily in Aloi crater, drained back into the eruptive fissure on the floor of the pit crater. Tilt measurements show that a collapse of the summit of Kilauea occurred during the eruption, and precise leveling of the rift zone indicates that absolute uplift of the ground near the eruptive region exceeded 2.5 feet. The changes in elevation presumably resulted from a transfer of magma from the reservoir beneath the summit to the upper east rift zone. Mapping of the upper rift zone indicates that fissure vents and cinder cones are generally north of pit craters, and this suggests that the rift zone dips southward. Apparent tensional opening of the rift zone, which allows magma to drain from the summit reservoir, probably results from a combination of (1) southward movement of the flank of the volcano south of the rift zone under the influence of gravity and (2) inflation of the dipping rift zone by magma from the summit reserv

ISSN:0148-0227    

DOI:10.1029/JZ069i010p02033

年代:1964

数据来源: WILEY

摘要:

The subglacial geology and crustal structure in Ellsworth Land and the southern Antarctic Peninsula are discussed on the basis of gravity and magnetic anomalies and physiographic, geologic, and limited seismic refraction data. High‐amplitude magnetic anomalies with sources close to the base of the ice were found in the southern Antarctic Peninsula. The Jones Mountains area also has many magnetic anomalies whose origin near the base of the ice is consistent with the shallow ‘magnetic basement’ measured in Marie Byrd Land to the southwest. The few magnetic anomalies in a central area of Ellsworth Land suggests a deeper basement, and possibly a thick metasedimentary section associated with that of the Ellsworth Mountains. Several lines of evidence indicate that in spite of some structural similarities the Antarctandean geology of the southern Antarctic Peninsula is not continuous with the Ellsworth Mountains. At one location on the mountainous Antarctic Peninsula where good subglacial topographic control exists from seismic soundings, a detailed study of the terrain effect shows that it is not possible to obtain quantitative information from the gravity data about density variations associated with local lithologie changes. The mean free‐air anomaly in Ellsworth Land is +11 mgal, indicating that the area is approximately in isostatic equilibrium. Although high free‐air anomalies were observed on several crossings, the southern Antarctic Peninsula is shown to be regionally compensated. Bouguer anomalies suggest that the crust of the Antarctic Peninsula extends several kilometers deeper than that of Ellsw

ISSN:0148-0227    

DOI:10.1029/JZ069i010p02047

年代:1964

数据来源: WILEY