List of Forthcoming Papers

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List of Forthcoming Papers     

Characterization and quantification of inorganic constituents of tropical peats and organic-rich deposits from Tasek Bera (Peninsular Malaysia): implications for coals

Since the Carboniferous, tropical latitudes have been the site of formation of many economic coal deposits, most of which have a restricted range of mineralogical composition as a result of their depositional environment, climatic conditions, and diagenesis. Mineralogical and microscopic investigations of tropical peats from Tasek Bera, Peninsular Malaysia, were performed in order to better understand some of these factors controlling the nature, distribution and association of inorganic matter in peat-forming environments. Distribution and nature of the inorganic fraction of peat deposits give insight into the weathering conditions and detrital input into the mire system. Because the inorganic composition of peat deposits is determined by plant communities, height of water table, and climate, the results of the quantitative and qualitative analysis can be used to reconstruct palaeoclimatic conditions.Tasek Bera is a peat-accumulating basin in humid tropical Malaysia with organic deposits of low- to high-ash yield and thus representative of many ancient peat-forming environments. Clay minerals dominate the mineralogical composition of the peat and organic-rich sediments, while quartz and clays dominate the underlying siliciclastic deposits. Kaolinite is the most abundant clay mineral in the organic deposits with minor amounts of illite and vermiculite. Particle size analyses indicate that >50% of the inorganic detrital fraction is <2 μm. Most detrital quartz grains range in size from fine silt to fine sand. The fine sand fraction accounts for a maximum of 5 wt.% of the inorganic constituents. In addition, abundant biogenic and non-biogenic, Al- and Si-rich amorphous matter occur. In the ombrotrophic (low-nutrient) environment, biogenic inorganic material contributes up to >75% of the ash constituents. As a consequence, the vegetational communities make an important contribution to the inorganic and overall ash composition of peats and coals. The ash content of the often inundated peat consists on average of 10% opaline silica from diatoms and sponge spicules, while the ash of the top deposits may have up to 50% biogenic silica. Hence, Al- and Si-hydroxides and the opaline silica from diatoms and sponges represent a large repository of Al and Si, which may form the basis of mineral transformation, neoformation and alteration processes during coalification of the peat deposits. As a result, most coal deposits from paleotropical environments are anticipated to have little to no biogenic inorganic material but high amounts of secondary clays, such as kaolinite (detrital kaolinite, resilisified kaolinite, or desilisified gibbsite) or illite, and various amounts of detrital and authigenetic quartz.     

Upscaling unsaturated hydraulic parameters for flow through heterogeneous anisotropic sediments

We compare two methods for determining the upscaled water characteristics and saturation-dependent anisotropy in unsaturated hydraulic conductivity from a field-scale injection test. In both approaches an effective medium approximation is used to reduce a porous medium of M textures to an equivalent homogenous medium. The first approach is a phenomenological approach based on homogenization and assumes that moisture-based Richards’ equation can be treated like the convective–dispersive equation (CDE). The gravity term, dK_z(θ)/d(θ), analogous to the vertical convective velocity in the CDE, is determined from the temporal evolution of the plume centroid along the vertical coordinate allowing calculation of an upscaled K_z(θ). As with the dispersion tensor in the CDE, the rate of change of the second spatial moment in 3D space is used to calculate the water diffusivity tensor, D(θ), from which an upscaled K(θ) is calculated. The second approach uses the combined parameter scale inverse technique (CPSIT). Parameter scaling is used first to reduce the number of parameters to be estimated by a factor M. Upscaled parameters are then optimized by inverse modeling to produce an upscaled K(θ) characterized by a pore tortuosity–connectivity tensor, L. Parameters for individual textures are finally determined from the optimized parameters by inverse scaling using scale factors determined a priori. Both methods produced upscaled K(θ) that showed evidence of saturation dependent anisotropy. Flow predictions with the STOMP simulator, parameterized with upscaled parameters, were compared with field observations. Predictions based on the homogenization method were able to capture the mean plume behavior but could not reproduce the asymmetry caused by heterogeneity and lateral spreading. The CPSIT method captured the effects of heterogeneity and anisotropy and reduced the mean squared residual by nearly 90% compared to local-scale and upscaled parameters from the homogenization method. The Pacific Northwest National Laboratory is operated for the US Department of Energy by Battelle under Contract DE-AC05-76RL01830.     

Deep seated magmas and their mantle roots: Introduction

<正>In the last decade there has been a considerable effort to better understand the joint evolution of mafic and ultramafic magmatic systems and their deep mantle roots,through integrated petrological and thermo-barometric studies.Magma generation is regarded as the result of complex processes including melting,creation of channels for melt transfer,and interaction with the wall-rocks.Complexities in magmatic systems involve metasomatism and the creation of metasomatic fronts,branching and splitting of magma volumes during their evolution,and vat-     

Controlled source electrical methods for deep exploration

Application of controlled source electrical methods (CSEM) is impeded by natural field, electrification, geological, cultural, and topographic noise. Lateral resolution of parameters of adjacent steeply dipping bodies and vertical resolution of parameters of adjacent beds in a flatly dipping sequence are concerns with any CSEM method. Current channeling into a localized good conductor from a surrounding, overlying, or underlying conductor poses problems for the interpreter. A summary of the results of several recent experiments with CSEM techniques illustrates that with care and difficulty they can be used to depths on the order of 20 km. If measurements are made on a relatively uniform resistive surface, as can be found in glaciated Precambrian terranes, then either a grounded bipole or a loop source is acceptable. Most of the recent CSEM experiments were made over resistive Precambrian rocks and all were directed toward detecting a conductive layer near 20 km depth. For exploration beyond this depth, however, the MT/AMT method would seem to be preferred. The rationale behind this conclusion is largely contained in consideration of the ratio of signal to natural field noise. Where thick irregular surficial overburden of low resistivity occurs, two- and three-dimensional modeling is necessary to stripp off the effects of the shallow layers. This may not be possible for CSEM and then MT/AMT becomes the only alternative.     

General circulation of the solar atmosphere from observational evidence

Summary One of the main results of the rotating cylinder experiments ofFultz andHide is that the general flow regime in them is essentially determined by the ratio of the angular velocity of the fluid motions (relative to the cylinder) to that of the cylinder itself. Extending these results to the atmosphere of the sun, leads to the hypothesis that the layer in which spots are imbedded should exhibit a non-axially symmetric pattern, of theRossby type.The fluid motions, characteristic of such a general circulation pattern, are mainly along spherical surfaces, and have a wavelike (eddy) appearance similar to the planetary waves in the upper troposphere of the terrestrial atmosphere. These eddies transport momentum along these spherical surfaces from regions of relatively lower angular velocity to regions of higher velocity. Tracers (e.g., sunspots) imbedded is such a flow would show a correlation between their proper motions in latitude and longitude, such that spots moving equatorward will tend to have larger longitudinal motions (toward the west limb), and vice versa.Analysis of ten years (1935 to 1944) of Greenwich spot data shows a consistent, and (statistically) very significant correlation of spot group proper motions, in the proper sense. These results provide strong support for the existence of large-scale waves which are some modest fraction of the solar circumference, but larger than the sunspot groups. Moreover, these waves transport angular momentum (up the gradient of angular velocity) toward the equatorial regions from higher latitudes across at least the entire sunspot zone. It is not known, however, whether these eddies are the primary (or only) source of momentum to maintain the equatorial acceleration of the sun. However, if this source were shut off, and all other processes continued unabated, this layer of the sun between latitudes ±20° would reach solid rotation in about 51/2 rotations.Because this eddy transport of momentum is counter to the gradient of angular velocity, there is an implied transformation of the kinetic energy of the eddies into the kinetic energy of the mean east-west flow. Of possibly even more interest, however, might be the possibility of transfers of kinetic energy between eddies of all different scale sizes extending down the entire spectrum to include sunspot groups and the spots themselves. Moreover, some eddy size(s) in this layer is likely to be primarily responsible for a conversion of potential to kinetic energy.A result of subsidiary interest is the systematically higher value of solar rotation (at all latitudes) derivable from this data, which includes all spots which survive for at least two days. In contrast to the work of previous authors who used only long-lived spots, the result obtained when many small spots are used, indicates perhaps a variation of the rotation rate with height in the solar atmosphere.The results provide no evidence to indicate the existence of significant meridional circulations (latitudinal driffs).     

Shell repair and drilling in some gastropods from the Ripley Formation (Upper Cretaceous) of the south-eastern U.S.A.

Breakage-induced shell repair and drilling were studied in 548 shells belonging to 24 species of gastropod from the Ripley Formation (latest Campanian-Maastrichtian) of the south-eastern U.S.A. Frequencies of repair are high even by Recent standards. These is no relationship between the frequency of shell repair and shell architecture. Repair increases in frequency with increasing shell length. Drilling, which is less common in Ripley gastropods than in most warm-water Tertiary species, decreases in frequency with increasing shell length.     

Systematics of crack controlled mechanical properties for a suite of Conway granites from the White Mountains, New Hampshire

The Conway granite of New Hampshire is a highly radioactive intrusive into which a 1-km deep borehole was drilled and continuously cored. The formation is composed of two major granitic units, the Osceola and the Conway; and it is cut by three lamprophyre dikes. The suite of rocks used in this paper contained eight granitic and two lamprophyre samples on which acoustic and strain measurements were performed over the pressure range of 1 atm. to 0.4 GPa. The V_p data were subjected to cluster analyses to determine what, if any, similarities in pressure-dependence existed among the samples. Three distinct similarity groupings were found: the lamprophyre dike rocks and two groups each of which contains samples from both granitic units. These groupings by V_p behavior were also found to correlate exactly with sample similarity groupings formed by dynamic and static moduli data, crack spectra, and rock texture. Such sample similarities in the functional forms of the pressure-dependence were found not to correlate with mineral modes nor with original in situ depth, but rather with grain size and the degree to which the mineral phases were homogeneously mixed. A consideration of the results suggests that for these rocks, grain size and mineral phase homogeneity exerted a dominant influence on crack population formation. Further, it appears that the exhumation and coring of these samples may have intensified the amount of cracking over that in situ but it did not necessarily introduce any individual distinct crack populations.     

Laser fluorometric analysis of plants for uranium exploration

A preliminary test of biogeochemical exploration for locating uranium occurrences in the Marfa Basin, Texas, was conducted in 1978. Only 6 of 74 plant samples (mostly catclaw mimosa, Mimosa biuncifera) contained uranium in amounts above the detection limit (0.4 ppm in the ash) of the conventional fluorometric method. The samples were then analyzed using a Scintrex UA-3 uranium analyzer^* - an instrument designed for direct analysis of uranium in water, and which can be conveniently used in a mobile field laboratory. The detection limit for uranium in plant ash (0.05 ppm) by this method is almost an order of magnitude lower than with the fluorometric conventional method. Only 1 of the 74 samples contained uranium below the detection limit of the new method. Accuracy and precision were determined to be satisfactory. Samples of plants growing on mineralized soils and nonmineralized soils show a 15-fold difference in uranium content; whereas the soils themselves (analyzed by delayed neutron activation analysis) show only a 4-fold difference. The method involves acid digestion of ashed tissue, extraction of uranium into ethyl acetate, destruction of the ethyl acetate, dissolution of the residue in 0.005% nitric acid, and measurement.