Geochemical exploration models for sedimentary uranium deposits

Decrease in rubisco activation at high CO2 concentration was caused by decrease in carbamylation of rubisco (Rohet al., 1996). However, it is unclear whether decrease in carbamylation rate at high CO2 concentration is due to decrease in activity itself or content of rubisco activase. To clarify this ambiguity, investigation was performed to determine effects of CO2 concentration on rubisco activase with kidney bean (Phaseolus vulgaris L.) leaves grown at normal CO2 (350 ppm) and high CO2 (650 ppm) concentration. The analysis of Western blotting showed that the 50 and 14.5 kl) polypeptides were identified immunochemically as the large and small subunits of rubisco in the preparation, respectively. For the 14.5 kD small subunit, the degree of intensity at high CO2 concentration was similar to that at normal CO2 concentration. For the 50 kD large sububit, however, the intensity of a band at high CO, concentration was significantly higher than that at normal CO2 concentration, indicating that only the large subunit is affected by high CO2 concentration. The analysis of Western immunoblotting showed two major polypeptides at 46 and 42 kD which were identified as rubisco activase subunits. The intensities of two bands were shown to be higher at normal CO2 than high CO2 concentration. These data indicate that decrease of carbamylation resulting from increase of CO2 concentration was caused by rubisco activase. Finally, by employing ATP hydrolysis assay and ELISA, we also observed a significant decrease in both activity and content of rubisco activase as CO2 concentration was raised from normal to high CO2 concentration. These results suggest that decrease in rubisco carbamylation at high CO2 concentration is caused by activity itself and/or content of rubisco activase.

Goal, Scope and Backgound Historically, landfills have been the simplest form of eliminating urban solid waste with the minimum cost. They have been the most usual method for discarding solid waste. However, landfills are considered authentic biochemical reactors that introduce large amounts of contaminants into the environment in the form of gas and leachates. The dynamics of generation and the movement of gas in landfills depend on the input and output parameters, as well as on the structure of the landfill and the kind of waste. The input parameters include water introduced through natural or artificial processes, the characteristics of the urban solid waste, and the input of atmospheric air. The main output parameters for these biochemical reactors include the gases and the leachates that are potentially pollutants for the environment. Control systems are designed and installed to minimize the impact on the environment. However, these systems are not perfect and a significant amount of landfill gas could be released to the atmosphere through the surface in a diffuse form, also known as Non-controlled emission. In this paper, the results of the Non-controlled biogenic gas emissions from the Lazareto landfill in Tenerife, Canary Islands, are presented. The purpose of this study was to evaluate the concentration of CH4 and CO2 in the soil gas of the landfill cover, the CH4 and CO2 efflux from the surface of the landfill and, finally, to compare these parameters with other similar landfills. In this way, a better understanding of the process that controls biogenic gas emissions in landfills is expected.

The weathered layer has been shown to contain some of the greatest values of shear wave velocity anisotropy in the earth (Lynn, 1991, Crampin, 1990). The cause of the shear wave velocity anisotropy is most often either due to particle layering in unconsolidated sediments and sedimentary rocks or due to aligned weaknesses commonly manifest as aligned open fractures. The aligned open fractures can be vertical and cross cut bedding in sedimentary rocks or can be horizontal to sub-horizontal and are aligned with bedding. The purpose of this study was to measure the variation in properties associated with the vertical or sub-vertical fractures as these fractures often provide preferential pathways to fluid migration and can also influence recording of deeper seismic shear wave reflection data for oil and gas exploration.

Silver veins of Proterozoic age in the Cobalt area, Ontario, are associated with the thick Nipissing diabase sheet, and those at Great Bear Lake, N.W.T., are also, in part, associated with a diabase sheet. Host rocks in the Cobalt area are flat-lying Aphebian sedimentary rocks, steeply dipping Archean volcanic and associated sedimentary rocks, and diabase, while host rocks in the Great Bear Lake area are intermediate and felsic volcanic rocks and tuffs of the Echo Bay group.Model-lead ages for ordinary galenas are about 1,630 and 2,280 m.y. for the Great Bear Lake and Cobalt veins, respectively, whereas the pitchblende U-Pb age for the Great Bear Lake veins is about 1,445 m.y., and the apparent Rb-Sr age for the Cobalt veins is about 2,160 m.y. An Rb-Sr isochron age of 1,425 + or - 48 m.y. has been obtained for the diabase sill in the Port Radium area, Great Bear Lake.In the Cobalt area essentially identical lead isotope compositions were obtained for interflow base metal mineralization in Archean volcanic rocks, galena along bedding in sedimentary rocks of the Cobalt group, and some late-stage sulfide veins. One interflow sample with a more primitive composition has a model age of at least 2,805 m.y. Mineralization, including deposition of most of the lead in Archean interflow beds, is interpreted to have taken place at about 2,160 m.y. and to be genetically related to the Nipissing diabase. In addition, two anomalous lead lines are defined, one of which suggests an age of 3,260 + or - 100 m.y. for Archean volcanic rocks. A shallow line, represented in only late-stage sulfide veins, is difficult to interpret but could be due to the late addition of a radiogenic component during Paleozoic or younger events not normally considered as causing mineralization, or even from ground water.Leads from the Great Bear Lake area could represent a single anomalous lead line with a slope of 0.1085 + or - 0.0070, and thus have a maximum possible age of 1,130 m.y. Geological events younger than this are known in the Bear Province, but not in the vicinity of the veins, and the same problems of interpretation exist as for the Cobalt area.The source of lead is not defined in either area. However, a source with homogeneous lead is required and the lack of extensive wall-rock alteration suggests that the lead was not leached from the country rocks. The diabase is tentatively favored as the source, but a connate brine or other source is possible.

Sandstone-type uranium deposits are the most important uranium producers among various types of uranium deposits. Geologic setting and diagenetic alteration mineralogy of this type of deposits have been well documented. The genesis of sandstone-type uranium deposits have been argued based on geologic and mineralogic studies (Nash et al., 1981). However, it is essentially important to estimate chemical features (Eh, pH) and isotopic compositions of fluids responsible for uranium mineralization and associated diagenetic alteration in order to elucidate genesis of the uranium deposits and diagenetic alteration mechanism. A few such geochemical studies on the sandstone-type deposits have been carried out. In this study, the geochemical features of the diagenetic alteration in the Tone mine area are used to provide constraints on the relationship between uranium mineralization and diagenetic alteration process and the estimation of chemical environments responsible for uranium mineralization.

Uranium is so intimately associated with carbonaceous matter in marine black shales and some sands tone-type uranium deposits that it is said to be “fixed” by organic matter. But different kinds of organic matter are not of equal importance in the geochemistry of uranium. The nature and origin of organic matter in uranium deposits and its role in the transport and concentration of uranium are different from place to place. The reason why uranium is closely associated with certain types of organic matter (for example, humus or bitumen) is described in this paper from geochemical viewpoint.Many uranium deposits and uranium occurrences have been found both at home and abroad. The distribution and existing forms of uranium in these deposits, and the concentration of uranium and element association in the ore are directly or indirectly related to organic matter. This paper is intended to discuss the types of natural organic matter and the mechanism of uranium transport and enrichment by organic matter, on the basis of author’s research work in conjunction with previous data.

Hummocky cross-stratification is a type of bedding in sedimentary rocks caused by the draping of sand around low-steepness three-dimensional bedforms. This distinctive form of stratification has been thought to be diagnostic of the former action of storm waves and hence its occurrence has been used to reconstruct ancient palaeogeographies and marine processes. Here I examine theoretical and empirical aspects of hummocky cross-stratification pertaining to its origin and argue that the notion that it was produced purely under progressive storm waves is incompatible with observed hummock spacings and possible values of the ratio a/λ under waves (a is the amplitude of oscillation near the bed and λ is the bedform spacing). My view is supported by recent observations on naturally-occurring hummocky megaripples from the sea floor of the inner Atlantic Shelf of North America.

Mapping of rock types, structural geology, and hydrothermal alteration, supported by geochronology and thermochronology, sheds light on the original spatial relationships of hydrothermal systems to intrusions in the northern Shoshone Range in north-central Nevada. Rocks in the Hilltop district are tilted ~35–40°E, as indicated by orientations of flattened pumice fiamme and bedding in sedimentary rocks along a single set of presently low-angle normal faults that initiated at 60–70°W dips. New U-Pb zircon geochronology from two sets of dikes in the Lewis district could suggest late Eocene–early Oligocene extension, but definitive crosscutting relations are lacking to demonstrably support this potential earlier period of normal faulting. Reinterpretation of previously reported apatite fission-track cooling ages with a new palinspastic restoration in the Lewis mining district concurs with middle Miocene extension as documented to the south at the Caetano caldera; however, the depth of burial of the Lewis district—and thus the significance of the apatite fission-track cooling ages—is uncertain. The comparable orientations and tilting history, supported by fault scaling relations, suggest that the temporally coincident extension in the Caetano caldera to the south represents the along-strike continuation of the same system of normal faults as in the Hilltop and Lewis districts, with changes in observed offset, percent extension, and fault spacing attributed to the gradual tipping out of the fault system northward.

Colloidal clay of the montmorillonite-beidellite group extracted from the Putnam soil of Missouri was studied under the petrographic microscope while undergoing flocculation. The floccules were relatively coarse aggregates so well oriented as to resemble crystals. They were platy in shape, resembling in that respect the mineral in a bedded clay shale. It is suggested that bedding in shale may originate in part in the colloids contributed to it, that clay may be carried far seaward as a colloid and be flocculated and deposited in coarser floccules, and that clay partings and films in limestone may originate from flocculated clay colloids. The texture of fire clays is contrasted with that of shale.

Layering in rapakivi granite occurs locally in the islet Soderoren, Aland, SW Finland. The layering consists of 3—5 cm thick, rhythmically repeated layers with high concentrations of biotite, hornblende, allanite and olivine. Almost all layers are asymmetric with sharp lower contacts but gradually pass-ng into the overlying light layers. Many layers show cross-cutting structures resembling current bedding in sedimentary rocks. It is concluded that the layering is a gravity stratification probably due to convective magmatic currents in the roof zone of a granitic magma.

Sphalerite from the sediment-hosted Dolostone Ore Formation (DOF) Cu-Co-Zn deposit, in northwestern Namibia, has previously been shown to contain extremely high concentrations of the critical metal Co (up to 1 wt%). These concentrations are the highest reported in sphalerite to date, and the how and why of sphalerite being able to incorporate such high concentrations of Co are poorly understood. We use correlative electron probe microanalysis, electron backscattered diffraction, and atom probe to reconstruct the likely incorporation mechanisms and modes of occurrence of such high Co concentrations in natural sphalerite. While over twenty samples were studied, the comprehensive analytical workflow was executed on one representative sample to gain a detailed understanding of Co enrichment. The sulfides of the studied sample are Co-rich pyrite, chalcopyrite, Co-rich sphalerite, linnaeite, cobaltpentlandite, and cobaltite, mentioned in order of abundance. Detailed petrography of these sulfides indicates that they formed through three stages during the main Cu-Co-Zn ore stage of the DOF. Cobalt was initially contained in pyrite that grew during Ore Stage 1 and was later affected by oxidizing fluids (Ore Stage two). This led to remobilization and growth of linnaeite (Co2+Co3+2S4). A later change in fO2 (Ore Stage three) led to the breakdown of linnaeite and the further growth of accessory cobaltite along with the Co-rich sphalerite and chalcopyrite. The hyper-enriched Co-sphalerite then is the last major sink for Co in the DOF deposit. A low Fe and Co and high Zn sub-grain boundary network within the Co-rich sphalerite was identified by EPMA and EBSD. This sub-grain network is believed to have formed during a later, secondary metamorphic stage (Cu-Zn (-Pb) Ore Stage 4), which developed during ductile deformational mineralization styles such as pressure shadows and veins. Our APT data reconstructions show no evidence for Co-inclusions within the Co-sphalerite, and spatial ion correlation analyses of the data suggest that Co occurs in the sphalerite through simple substitution of Zn. This study demonstrates that sphalerite may contain significant concentrations of the Co through simple substitution, potentially representing an important non-traditional Co source in future critical metal exploration.

The effects of elevated CO 2 concentration on the growth and development of the funnel‐web weaving spider A gelena labyrinthica ( C lerck) ( A raneae: A gelenidae) were studied in climate chambers with low (370 μl l −1 ) or high (750 μl l −1 ) CO 2 concentration. Seventh‐instar A . labyrinthica cultured under each of these CO 2 concentrations were randomly selected to determine nutrient composition (total protein, total amino acid, and free fatty acid) and digestive or detoxification enzymes activity (peroxidase, amylase, and superoxide dismutase) using test kits. When reared under high CO 2 concentration, total development of A . labyrinthica was significantly faster. Carapace length and width and body weight did not differ between CO 2 concentrations, nor the levels of protein and total amino acids in seventh‐instar A . labyrinthica . However, free fatty acid levels were significantly lower under high CO 2 concentration. Specific activities of peroxidase and superoxide dismutase in seventh‐instar A . labyrinthica did not differ between CO 2 concentrations. The specific activity of amylase under high CO 2 concentration was higher than that of the low CO 2 group. The effects of elevated CO 2 on A . labyrinthica varied from those on the wandering spider P ardosa astrigera L Koch, as found in an earlier study. Apparently, elevated CO 2 has a species‐specific impact on spiders.

The roles of organic matter in the formation of uranium deposits in sedimentary rocks

Genesis of uranium deposits in Neogene sedimentary rocks overlying the Menderes metamorphic massif, Turkey

A procedure and apparatus have been developed for rapid source-rock characterization. Based on the paralysis of small rock samples, it makes possible the determination of :various types of source rockstheir degree of evolution (immature, oil zone, gas zone)their petroleum potential The method can be performed on cores or cuttings either in the laboratory or at a well site (especially aboard offshore drilling vessels), and in this case it can be used to detect oil shows. Generally the procedure uses ground rock, but it is also possible to operate directly with small cuttings without any prior treatment. Aboard the GLOMAR CHALLENGER (LEGS 48 and 50) the apparatus was especially used as a safety tool to reveal rapidly the presence of oil shows. INTRODUCTION In the field of petroleum exploration, one of the most important aspects is to be able to recognize the various types of source rocks in a geological series which, under the effect of increasing temperature during burial, produce petroleum compounds. As a matter of fact, the quantity and character of the hydrocarbons which have been produced depend on the character of the organic matter originally deposited in these source rocks as well as on subsequent thermal evolution, i.e. temperature and geological time. Recent research 1,, on kerosene (insoluble organic matter) from sediments sampled in various basins has shown that the physical chemical analysis of these kerosene makes it possible to classify the various types of organic matter and to estimate their oil and gas potential together with their degree of evolution. Do not fulfill the requirements of petroleum exploration which requires the analysis of a large number of sediment samples by simple, cheap and rapid methods. The basic knowledge acquired from the study of various types of kerosene has been used to develop a rapid method applied to characterize the different qualities (types) of organic matter directly on sedimentary rocks and to estimate their oil potential and their degree of evolution. This method is based on the selective detection of hydrocarbon compounds and of one of the principal oxygenated compound (C02) produced by paralysis under normalized conditions of organic matter contained in sediments. The paralysis technique has already been used by various authors (4, 5,6,7,8) for studying organic matter in sedimentary rocks. CHARACTERIZATION OF VARIOUS TYPES OF KEROGEN Elementary analysis of kerosene shows that the major atomic constituents are carbon, hydrogen and oxygen. The H/C and O/C atomic ratios utilized in a diagram of the type established by Van Reveled for coal shows that the samples corresponding to the same quality of organic deposits are situated on a curve called "evolution path". (fig. 1)