摘要:

A study was made of the mineral composition of individual rainfalls at Prince William National Forest Park, Virginia. Data are presented showing variations in the composition of rainfall during the course of six separate storms. The data support the theory that much of the SO4−−in rainfall is formed from the oxidation of SO2in cloud droplets. It is suggested that atmospheric NO2, acting as a catalyst, is very important in this reaction. The data indicate that SO4−−, NO3−, and NH4+in rainfall are derived primarily from gaseous constituents of the atmosphere. The origin of NO3−in thunderstorm rainfall is discussed and evidence is given to show that the role of lightning is almost certainly

ISSN:0148-0227    

DOI:10.1029/JZ069i020p04203

年代:1964

数据来源: WILEY

摘要:

In a previous paper, the present authors developed an expression for evaluating the quantity of air flowing into a partly cased rectangular porous trench of constant permeability. The flow was assumed to be isothermal, steady, and two‐dimensional. The formula isQ= 2(K1′/2K1) (k/μ) 〈ρ〉 (ps‐pw), whereQis the mass flow rate per unit length of the trench,K1′/2K1is a configuration factor, 〈ρ〉 is the average density at mean pressure, andpsandpware the air pressures at the trench top and the uncased trench walls, respectively. The configuration factor in this earlier work was determined by considering the effects of depth to the impermeable layerdι, depth of the trenchdt, and depth of the trench casingdc. In the present study, however, values ofK11/2K1were determined which included the effect of trench width as well asdι,dt, anddc. New values of the configuration factor are shown graphically for various geometrical arrangements. It is found that in any practical analysis, the effect of trench width is not negligible and

ISSN:0148-0227    

DOI:10.1029/JZ069i020p04211

年代:1964

数据来源: WILEY

摘要:

The discharge of an uncontrolled pumping well generally decreases with time. Eventually the discharge may attain a constant rate. Frequently, the observed discharge‐time variation can be represented empirically by an algebraic equation of simple form. In this paper, drawdown formulas are obtained for wells operating in leaky or nonleaky effectively infinite aquifers, having three types of probable discharge‐time variation. These formulas are expressed either in terms of already known and extensively tabulated functions or in terms of functions that can easily be tabulated for practical ranges of the parameters involved. Use of these formulas in the analysis of pumping‐test data is also disc

ISSN:0148-0227    

DOI:10.1029/JZ069i020p04221

年代:1964

数据来源: WILEY

摘要:

Because the rate of water movement in argillaceous rocks depends considerably on the conditions of measurement, the only permeability measurements of practical field significance for these rocks are those obtained while the sample was held at temperatures and pressures that duplicated natural subsurface conditions as closely as possible. In laboratory measurements described in this report, the permeabilities of argillaceous rocks from the lower Cretaceous of western Canada ranged from 10−7to 10−4millidarcy decreasing as the rocks became more clayey. Since argillaceous rocks tend to be compressible, flow rates through these rocks were dependent upon the difference between confining and average fluid pressures. Furthermore, the flow rates changed more with temperature than would be expected from the normal changes of water viscosity with temperature. This anomalous flow behavior suggests that the water in clayey rocks has a structure that is different from the structure of bulk wa

ISSN:0148-0227    

DOI:10.1029/JZ069i020p04237

年代:1964

数据来源: WILEY

摘要:

The total γ‐ray intensity and the amounts of the principal radioisotopes have been measured between 2 and 100 hours after the end of a short activation of some natural sands and clays. The dominant radioactivity of alluvial sands of the Linth‐Limmat river system (Switzerland) between 2 and 20 hours is from Mn56and between 20 and 99+ hours it is from Na24. The atomic densities of Na and Mn in these sands, as determined by neutron activation, average 4.2×1020and 0.043×1020cm−3respectively. The residual radioactivity 40 days after the end of a 15‐min activation is about 0.001 that at 30 hours. Certain of the mineral grains in the sands were studied separately. The atomic densities of Na and Mn are reported for dolomite, quartz, sernifite, and serpentine grains, and of sodium alone for sodium bentonite and opalinus clays. There is a variation by a factor of 40 or more in the induced Na24radioactivity of equal‐sized grains of the same mineral fraction. The induced radioactivity decreases by a factor of 0.5 when the grain size is increased from 0 to 6 mm and by a factor of 0.8 when the sample size is increased from 0 to 6 grams. Activation factors for a 15‐min activation of certain chemical elements at pile factor 30 are given. These factors are used in computing the expected radioactivity induced by such an activation in igneous rock, sedimentary rock,

ISSN:0148-0227    

DOI:10.1029/JZ069i020p04247

年代:1964

数据来源: WILEY

摘要:

‘Consolidation’ in the geologic sense is the hardening, or lithification, of a sediment; in the field of soil mechanics consolidation refers to the reduction of volume of a sediment under imposed loads. Consolidation tests were run on eleven samples from the Guadalupe Mohole site, including surface samples from gravity cores (taken in the usual manner by lowering a weighted tube from the ship) and cored samples to a depth of 136 m (from the drilling operation). Interpretation of the test curves of these seriously disturbed samples indicates that these deep‐sea sediments are stronger than might have been anticipated. They appear capable of supporting overburden pressures without significant reduction of porosity in the depth range studied. Porosities at the sediment surface were about 80%; in situ porosities for the deepest samples were estimated to be about 72%; reduction of no more than 5% owing to overburden pressure is estimated for the deepest sample (168 m). It is concluded that these effects are due to low rates of deposition, great age, and materials which induce interparticle bonds having the nature of chemical cement

ISSN:0148-0227    

DOI:10.1029/JZ069i020p04257

年代:1964

数据来源: WILEY

摘要:

In studying the strength properties of preliminary Mohole samples, primary consideration was given to testing samples under conditions as similar as possible to those in situ. For shear strength tests, the triaxial cylindrical compression apparatus and the consolidated undrained test were selected as most suitable. Shear strength was found to vary from 0.07 bar in the upper meter to 2.66 bars at a burial depth of 136 meters. Comparison of test results with previous work on normally consolidated marine clays suggests the Mohole sediments to be similar in most respects to other clays, but having a higher ratio of strength to overburden pressure than do clays from environments of shallower water and more rapid deposition. Comparison of shear strength values with burial depth to values of porosity, particle size, total carbonate content, and content of clay minerals indicates a positive correlation between strength and carbonate and montmorillonite content, but a negative correlation between strength and porosity, per cent clay‐sized particles, and illite and chlorite content. The common cause of these correlations is believed to be original rate of deposition of detrital sediments. The section from 85 to 135 meters is believed to have accumulated at a greater rate than the older and younger sediments, thereby lessening the effect of incipient cementation near the water‐sediment interf

ISSN:0148-0227    

DOI:10.1029/JZ069i020p04271

年代:1964

数据来源: WILEY

摘要:

Rates of sedimentation of pelagic sediments in the South Atlantic have been determined using the ionium/thorium methodology. Values of the order of several millimeters per thousand years for sediments were found in the deposits in the valleys of the mid‐Atlantic ridge. The equatorial deposits showed higher rates of accumulation than the corresponding deposits at higher latitudes, probably reflecting the added influx of materials to the sea floor from tropical rivers through the equatorial current systems. The deposits in the ridge valleys showed marked changes in sedimentation rates at about 115,000 years ago, at which time the present rates changed from higher to lower values. The ridge sediments were composed primarily of continentally derived materials, and there were no indications of solid phases being derived from the weathering of the ridge itself or from volcanic activity. The equatorial samples have mineral assemblages which are distinctly different from those in deposits at higher latitudes and which probably are indicative of contributions of materials from tropical weathering processe

ISSN:0148-0227    

DOI:10.1029/JZ069i020p04293

年代:1964

数据来源: WILEY

摘要:

Electric currents generated by the circular motion of seawater in the earth's magnetic field give rise to small alternating magnetic fields. These minute fields have the frequency of the ocean waves whipped up by winds. For a 100‐m wave with 5‐m height, a period of 8 seconds, sea state 6, the field varies from about 3 γ at the surface of the sea wave to the order of 0.1 γ at a depth of 95 m. This is a less rapid decay than the magnetic field has above the surface due to the same induced currents in the seawater. The component of the field in the direction of propagation reverses direction at a depth of approximately 8 m and reaches a negative maximum at about 24 m. The net effect is a rotating magnetic field in a vertical plane having a cyclic varying amplitude and angular velocity, with forward rotation below the reversal level and reverse rotation above that depth. For a more usual wave (36‐m length, 4.8 seconds period, and 0.82‐m amplitude, a moderately rough wave in the lower edge of state 4) the field varies from about 0.6 γ at the surface to 0.1 γ at a depth of 22 m. The reversal of the field component in the direction of propagation of the sea wave in this case occurs

ISSN:0148-0227    

DOI:10.1029/JZ069i020p04311

年代:1964

数据来源: WILEY

摘要:

A comparison of aeromagnetic profiles with bedrock geology in the McMurdo Sound area indicates high‐amplitude anomalies associated with the McMurdo volcanics and no significant anomalies associated with rocks in the crystalline basement complex. The McMurdo volcanics are the only rocks yet identified in the Transantarctic Mountains capable of causing the anomalies (greater than 200 γ in amplitude) that are observed in the icecovered areas adjacent to the mountain syst

ISSN:0148-0227    

DOI:10.1029/JZ069i020p04319

年代:1964

数据来源: WILEY