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The author has identified the following significant results. A land use map was prepared of Dacca-Narayanganj-Demra area on a scale of 1:50,000. LANDSAT imageries of Dinajpur and Rangpur districts were studied. The difference between the exposed Pleistocene red clay, this clay under alluvial cover, and recent alluvium were noted. Different types of soils, crops, etc. were delineated on the ERTS imagery.
Converging lines of evidence suggest that a significant portion of the Martian surface fines may consist of salts and smectite clays. Salts can form stoichiometric hydrates as well as eutectic solutions with depressed freezing points; clays contain bound water of constitution and adsorb significant quantities of water from the vapor phase. The formation of ice may be suppressed by these minerals in some regions on Mars, and their presence in abundance would imply important consequences for atmospheric and geologic processes and the prospects for exobiology.
Early time two dimensional finite difference calculations of laboratory scale hypervelocity impact of 0.3 g spherical 2024 aluminum projectiles into homogeneous plasticene clay targets were performed. Analysis of resulting material motions showed that energy and momentum were coupled quickly from the aluminum projectile to the target material. In the process of coupling, some of the plasticene clay target was vaporized while the projectile become severely deformed. The velocity flow field developed within the target was shown to have features similar to those found in calculations of near surface explosion cratering. Specific application of Maxwell's analytic Z-Model showed that this model can be used to describe the early time flow fields resulting from the impact cratering calculations as well, provided the flow field centers are located beneath the target surface and most of the projectile momentum is dissipated before the model is applied.
Direct physical evidence is presented for an unusual event at exactly the time of extinctions in the planktonic realm. Deep-sea limestones exposed in Italy, Denmark, and New Zealand indicate iridium increases of about 30, 160, and 20 times, respectively, above the background level at precisely the time of the Cretaceous-Tertiary extinctions, 65 million years ago. Reasons are given that this iridium is of extraterrestrial origin, but did not come from a nearby supernova. A hypothesis is set forth which accounts for the extinctions and the iridium observations. One prediction of this hypothesis is verified, that the chemical composition of the boundary clay, which is thought to come from the stratospheric dust, is markedly different from that of clay mixed with the chemically similar Cretaceous and Tertiary limestones.
A unique set of radiometer measurements is presented, recorded during a 1000-h day and night monitoring of irrigated fields from fully saturated to completely dry. Radiometer measurements were recorded at 2.8-cm (X-band) and 21.4-cm (L-band) wavelengths for a range of incident angles from nadir to 50 deg. Soil moisture and soil temperature profile measurements were recorded to a depth of 15 cm. The test site was located in east-central Texas on a clay soil (Miller clay). Three bare-surface plots were used, each having a distinctly different surface roughness. Vegetated plots were also measured. The data quantify the sensitivity of microwave radiometer measurements to soil moisture variations, the effect of surface roughness on the measurement, and the influence of surface vegetation.
X-ray diffraction and spectroscopy were used to investigate the mineralogical and chemical properties of the Calvert, Ball Old Mine, Ball Martin, and Jordan Sediments. The particle size distribution and index of refraction of each sample were determined. The samples are composed primarily of quartz, kaolinite, and illite. The clay minerals are most abundant in the finer particle size fractions. The chemical properties of the four samples are similar. The Calvert sample is most notably different in that it contains a relatively high amount of iron. The dominant particle size fraction in each sample is silt, with lesser amounts of clay and sand. The indices of refraction of the sediments are the same with the exception of the Calvert sample which has a slightly higher value.
Serine guanylate was prepared and its polymerization studied in the presence of montmorillonite and in its absence. In water, without clay, serine guanylate polymerizes in the same way as does serine adenylate. In the presence of montmorillonite, serine guanylate polymerizes to a lesser extent and produces also lower degrees of polymerization than does serine adenylate. It is postulated that the reason for this difference in behavior might lie in the fact that guanylic acid is much more acidic than adenylic acid; hence would bind much more strongly to the edges of montmorillonite and thus, by blocking these sites, would inhibit the catalytic activity of the clay.
Alkalic basalt samples from Ross Island, Antarctica, are evaluated as terrestrial analogs to weathered surface materials on Mars. Secondary alteration in the rocks is limited to pneumatolytic oxidation of igneous minerals and glass, rare groundmass clay and zeolite mineralization, and hydrothermal minerals coating fractures and vesicle surfaces. Hydrothermal mineral assemblages consist mainly of K-feldspar, zeolites (phillipsite and chabazite), calcite, and anhydrite. Low alteration rates are attributed to cold and dry environmental factors common to both Antarctica and Mars. It is noted that mechanical weathering (aeolian abrasion) of Martian equivalents to present Antarctic basalts would yield minor hydrothermal minerals and local surface fines composed of primary igneous minerals and glass but would produce few hydrous products, such as palagonite, clay or micas. It is thought that leaching of hydrothermal vein minerals by migrating fluids and redeposition in duricrust deposits may represent an alternate process for incorporating secondary minerals of volcanic origin into Martian surface fines.
Thematic mapper scenes for Washington, D.C. and Macon, Georgia were examined to determine their radiometry and geometric accuracy. Specific band ratios were used to determine their effectiveness in defining vegetation and rock mineralogy. the TM 3/4 band ratio was used to define vegetation and the 5/2 band ratio was used to define limonitic rocks. The 5/7 band ratio was evaluated to test the effectiveness of the 1.6 and 2.2 mm bands in detecting clay and carbonate bearing rocks. Preliminary results show that clay minerals containing absorption bands at 2.2 mm, which are centered in the TM band 7, can be readily detected when the band ratio images are suitably contrast stretched. Bright rocks, such as marbles, which contain absorption bands in the 2.33 mm region, near the wavelength of TM band 7, are only evident upon harsher contrast stretching of the 5/7 band ratio. Geobotanical studies of Washington, D.C. show that monospecific forest canopies can be differentiated.
Some LANDSAT thematic mapper data collected over the eastern United States were analyzed for their whole scene geometric accuracy, band to band registration and radiometric accuracy. Band ratio images were created for a part of one scene in order to assess the capability of mapping geologic units with contrasting spectral properties. Systematic errors were found in the geometric accuracy of whole scenes, part of which were attributable to the film writing device used to record the images to film. Band to band registration showed that bands 1 through 4 were registered to within one pixel. Likewise, bands 5 and 7 also were registered to within one pixel. However, bands 5 and 7 were misregistered with bands 1 through 4 by 1 to 2 pixels. Band 6 was misregistered by 4 pixels to bands 1 through 4. Radiometric analysis indicated two kinds of banding, a modulo-16 stripping and an alternate light dark group of 16 scanlines. A color ratio composite image consisting of TM band ratios 3/4, 5/2, and 5/7 showed limonitic clay rich soils, limonitic clay poor soils, and nonlimonitic materials as distinctly different colors on the image.
An examination is made of samples of melt rock and breccia from 12 terrestrial impact craters to identify alteration minerals and their conditions of formation. It is found that in most cases the dominant assemblage is clay-silica-K feldspar-zeolite, suggesting hydrothermal alteration at low pressures and temperatures of 100-300 C. The clays are in the main Fe-chlorites and smectites, in most cases depleted in Al and enriched in Fe and Mg relative to their source rocks. The alteration of impact glass is found often to be complete, whereas the alteration of crystalline melt rock is limited to a few percent of the rock volume. Impact breccia is altered to only a slight extent compared with the alteration of glass. It is believed that impact-induced hydrothermal alteration is to be expected at Martian impact sites if significant quantities of ground ice and/or water are present.
The results of isotopic and trace-element-abundance analyses of Ir-enriched Cretaceous-Tertiary-boundary clay sediments from Caravaca, Spain, and of adjacent carbonate and marl layers, are presented. Acetic-acid and HCl leachates and residues were analyzed by isotope dilution to determine K, Rb, Sr, Sm, and Nd concentrations and Sr-87/Sr-86 and Nd-143/Nd-144 ratios. The stable isotope ratios delta-D, delta-(C-13), and delta-(0-18) were also determined. The results are presented in tables and graphs and compared with published data on the Caravaca sediments and on samples from other locations. The boundary clay is found to be distinguished from the adjacent layers by its isotopic ratios and to be of mainly terrestrial, lithospheric (deeper than 3-km) origin. Although submarine-weathering effects are evident and difficult to quantify, the degree of variation in Ni, Ir, Sr, and REE concentrations is considered too large to be attributed to postdepositional processes alone. These findings are seen as evidence for the ocean impact of a large single asteroid producing a worldwide blanket of ejecta, a large injection of water vapor into the atmosphere, and perhaps a gigantic tsunami, at the end of the Cretaceous period.
The principles of the method are explained and the working of the CILAS 715 laser granulometer is described. The particle size distributions of milled glazes, quartz, feldspar and china clay were determined by this instrument and by Andreasen sedimentation. The agreement was good for isometric particles, but the china clay appears finer by sedimentation, because the platelets arrange themselves horizontally during sedimentation, while in the laser granulometer preferred orientation is prevented by circulation between the sample holder and the vibrated and stirred reservoir of the slip.
The properties of freeze-dried dilute dispersions of dust in water ice are of considerable interest in studies of comet nucleus mantles. The formation of a rind residue produced by the sublimation of water ice containing various amounts of fine clay particles may be an important process. A simulation of the development of the dry dust rind on the surface of comets is presented. This rind is the result of preferential ice sublimation. The development and disruption of this rind and its subsequent levitation by water vapor flow is studied. The most interesting rind simulant is produced by dispersing 0.1 micron particles of montmorillonite in water in concentrations of 10%, 1%, and 0.1%. These dispersions are then sprayed into liquid nitrogen in the form of 100 micron droplets. The frozen droplets are then freeze-dried in a vacuum which prevents the ice temperature from rising above -30 C. Sublimation of the nitrogen and the water produced dry rinds. The most striking result was the development of large cohesive matrices of individual clay particles, and in some cases a continuous cohesive crust. Scanning electron microscope (SEM) observations reveal that the material formed by freeze-drying the 0.1% dispersion does not retain the original spherical shape of the sprayed 100 micron droplets; instead it consists of a continuous filamentary network, as shown in the SEM stereo micrographs.
Analysis of Thematic Mapper data acquired November 15, 1982, over a vegetated site located in the East Texas Timberlands and Claypan area of Texas has indicated that montmorillonitic clay textured soils can be separated from soils with different textures. The difference of TM band 4 (0.76-0.90 micron) and band 7 (2.08-2.35 microns) had an agreement of 55.8 percent with the USDA soil survey for upland clay soils. This compared to 55.9-percent agreement when all six bands (excluding the thermal) were used. The disagreement occurred at the boundary lines as defined by the USDA soil survey and the spectral data. This result is considered to be fairly good, considering the difficulty in placement of soil boundaries by the soil scientist in the field. While the exact influence on the vegetation, and thus the spectral response observed by TM, is not understood at this time, it appears that TM band 7 is responding to the type of mineralogy of the soil and that soil properties important to the plant can be detected using TM.
A ball-on-cylinder machine (BOCM) was used to measure the lubricity of fuels. The fuels tested were well-characterized fuels available from other programs at the NASA Lewis Research Center plus some in-house mildly hydroprocessed shale fuels from other programs included Jet-A, ERBS fuel, ERBS blends, and blend stock. The BOCM tests were made before and after clay treatment of some of these fuels with both humidified air and dry nitrogen as the preconditioning and cover gas. As expected, clay treatment always reduced fuel lubricity. Using nitrogen preconditioning and cover gas always resulted in a smaller wear scar diameter than when humidified air was used. Also observed was an indication of lower lubricity with lower boiling range fuels and lower aromatic fuels. Gas chromatographic analysis indicted changes in BOCM-stressed fuels.
The design and operation of a salt-gradient solar pond power plant at the Salton Sea presents problems not encountered at small research ponds that were built in the United States. The specific characteristics of the Salton Sea site and the desire to construct the pond using the local clay as a sealant represent major deviations from previous solar pond experience. The site-specific research in support of the plant design is described. The research activity included validation of the spectrophotometric light transmission measurement technique, a search for options for clarifying the turbid and colored water of the Salton Sea, development of water clarification specifications in terms common to industry practice, quantification of gas production from microbiological reactions in the ground, a determination of the combined effects of temperature and salinity on the permeation of the local clays, and a preliminary evaluation of material corrosion.
Some LANDSAT thematic mapper data collected over the eastern United States were analyzed for their whole scene geometric accuracy, band to band registration and radiometric accuracy. Band ratio images were created for a part of one scene in order to assess the capability of mapping geologic units with contrasting spectral properties. Systematic errors were found in the geometric accuracy of whole scenes, part of which were attributable to the film writing device used to record the images of film. Band to band registration showed that bands 1 through 4 were registered to within one pixel. Likewise, bands 5 and 7 also were registered to within one pixel. However, bands 5 and 7 were misregistered with bands 1 through 4 by 1 to 2 pixels. Band 6 was misregistered by 4 pixels to bands 1 through 4. Radiometric analysis indicated two kinds of banding, a modulo-16 stripping and an alternate light dark group of 16 scanlines. A color ratio composite image consisting of TM band ratios 3/4, 5/2, and 5/7 showed limonitic clay rich soils, limonitic clay poor soils, and nonlimonitic materials as distinctly different colors on the image.