Effective utilization of seismic reflection technique with moderate cost in uranium exploration

In participation with numerous industrial partners, the Seismic Laboratory of the University of Saskatchewan has conducted a variety of active seismic reflection experiments; both on the west and east sides of the Athabasca Basin. Results of the investigations at Shea Creek, McArthur River and Keefe Lake illustrate that the seismic investigations deliver effective, highly relevant primary structural images of the subsurface, with resolution that no other geophysical technique can match. Correlation of similar seismic signatures, on several distant but inter-related seismic sections, allowed spatial extension of promising exploration target zones previously unrecognized. Within the three-dimensional seismic volume, comparable reflectivity patterns defined the complex areal distribution of mineralization-related fault systems. Beyond these novel contributions, extended analysis of seismic signal attributes (amplitude and frequency), optical televiewer, and full-wave sonic data offer detailed lithological characterization, including alteration zones, clay content, as well as porosity and fracture density information. Although these structural and geologically relevant anomalies are primary indicators of mineralization, presenting novel exploration advantages, the seismic method is still not a standard component of the Athabasca Basin exploration approach, due to the negative perception that ‘it is very expensive’. Comparing the costs of all geophysical techniques to the cost of a single logged drill hole illustrates that the results of a properly designed seismic data acquisition program not only leads to more effective planning of a drilling program, but also would lead to a much quicker recognition of the major mineralized zone(s), and a reduction in the number of required exploration boreholes. This integrated approach to exploration would then translate into a significant reduction of the total exploration expenditures. Unquestionably, the drilling of boreholes provides the most explicit, reliable information to a certain depth, but only within a very small area. Directly connecting the borehole information to seismic results extends the local reliable data; permitting reduction of the number of boreholes to create accurate two-dimensional or three-dimensional subsurface images and reduction of the expenditures of the total exploration program.     

Radioastronomical observations of comets IRAS-Araki-Alcock (1983d) and Sugano-Saigusa-Fujikawa (1983e)

Detections and upper limits to the continuum emission (1 ≤ λ ≤6 cm) and spectral line emission (OH, CO, CS, HCN, HCO⁺, CN, CH₃CN, CH₃C₂H, NH₃, H₂O, HC₃N, CH₃CH₂CN) are reported from radio observations of Comets 1983d and 1983e. Comparison is made with observations of CN at optical wavelengths. These results may be useful in planning future cometary observations.     

Metabolic activity throughout early development of dusky kob Argyrosomus japonicus (Sciaenidae)

The physiology of fishes in the early stages of development remains poorly assessed despite the importance of identifying energy bottlenecks in organisms faced with changing environmental conditions. This study describes the metabolic activity of dusky kob Argyrosomus japonicus throughout its early development, from hatchling to settlement stage. Standard, routine and active metabolic rates (SMR, RMR and AMR, respectively) were assessed to determine the species’ metabolic scope and identify how metabolism changes with growth and development. Distinct metabolic changes occurred in association with developmental changes during the early life stages, with flexion-stage larvae showing significantly reduced metabolic scope (approx. 0.30 µmol O₂ ind.^–1 h^–1), representing an energy bottleneck. Based on these findings, it is likely that larvae of A. japonicus are most susceptible to environmental perturbations during flexion. The variability of metabolic rates during the diel cycle was also assessed and revealed that the early-stage larvae showed no preference for daylight, although settlement-stage juveniles were more active during daylight hours (RMR = 12.78 µmol O₂ ind.^–1 h^–1) than at night (RMR = 5.87 µmol O₂ ind.^–1 h^–1). These results suggest that metabolic measurements of the SMR of A. japonicus larvae can be taken at any time of the diel cycle until the settlement phase, when readings should take place at night.     

The detection of interstellar methylcyanoacetylene

A new interstellar molecule, methylcyanoacetylene (CH3C3N), has been detected in the molecular cloud TMC-1. The J = 8 --> 7, J = 7 --> 6, J = 6 --> 5, and J = 5 --> 4 transitions have been observed. For the first three of these, both the K = 0 and K = 1 components are present, while for J = 5 --> 4, only the K = 0 line has been detected. The observed frequencies were calculated by assuming a value of radial velocity VLSR = 5.8 km s-1 for TMC-1, typical of other molecules in the cloud. All observed frequencies are within 10 kHz of the calculated frequencies, which are based on the 1982 laboratory constants of Moises et al., so the identification is secure. The lines are broadened by hyperfine splitting, and the J = 5 --> 4, K = 0 transition shows incipient resolution into three hyperfine components. The rotational temperature determined for these observations is quite low, with 2.7 K < or = Trot < or = 4 K. the total column density is approximately 5 x 10(12) cm-2.     

A new interstellar polyatomic molecule: detection of propynal in the cold cloud TMC-1

We report the detection of the acetylene derivative propynal (HC triple bond CCHO) in the cold cloud TMC-1, with an abundance that is very close to that for the related species tricarbon monoxide (C3O). Propadienone, an isomer of propynal with the formula H2C=C=C=O, was not detected and is hence less abundant than either C3O or HC2CHO.     

Detections of 13C-substituted C3H2 in astronomical sources

We report observations of the 2(12)-1(01) rotational transition of the 13C isotopic species of cyclopropenylidene (C3H2) toward TMC-1, Sgr B2, and IRC +10216 using the laboratory rest frequencies which have recently become available. Our detections allow estimates to be made of the fractional abundance of the unsubstituted similar species in these sources. The fractional abundance relative to H2, f(C3H2), is 1-2 x 10(-8) in TMC-1, and this is similar to the abundance of HCN, one of the more abundant organic molecules in the interstellar medium. In IRC +10216 f(C3H2) is one order of magnitude greater than in TMC-1. The 12C species in Sgr B2 shows a self-absorbed profile and the relative abundance of C3H2 estimated to be about an order of magnitude less than in TMC-1.     

Granulite-Facies Metamorphism, Granite Falls-Montevideo Area, Minnesota

In the Granite Falls-Montevideo area, Minnesota, granulite faciesmineral assemblages were collected from three major lithologicunits—hornblende-pyroxene gneiss, garnet-biotite gneiss,and granitic gneiss. Mineral assemblages most commonly observedare: plagioclase-hornblende-orthopyroxene-clinopyroxene-magnetite-ilmenite-(biotite-quartz);quartz-plagioclase-biotite-garnet-orthopyroxene-(orthoclase);quartz-plagioclase-biotite-garnet-(orthoclase); quartz-plagioclase-microcline-(garnet-hematite);and quartz-plagio-clase-microcline-biotite-(garnet-hematite-rutile).Partial analyses of isomorphous phases from the hornblende-pyroxenegneiss and the garnet-biotite gneiss were determined with anelectron microprobe. Negligible compositional variation within single grains andof a particular mineral within a given specimen, regular distributionof Fe and Mg between coexisting hornblende, ortho-pyroxene,and clinopyroxene, obedience of the mineral assemblages to theGibbs Phase Rule, and lack of empirically determined incompatiblephases indicate a close approach to chemical equilibrium duringmetamorphism. Plots of coexisting biotite, garnet, and orthopyroxeneon an appropriate phase diagram result in some crossing tielines which cannot be adequately explained by temperature orpressure differences, but suggest that H₂O and/or O₂ were notperfectly mobile components during metamorphism. This is alsoindicated by interlayering of hornblende assemblages with pyroxeneassemblages and by different iron oxide phases in essentiallythe same mineral assemblage. Textural and chemical relationships of retrograde metamorphicassemblages suggest that some retrograde reactions are a resultof cooling following the granulite-facies metamorphism, butthat others may have resulted from recrystallization duringa stage of thermal metamorphism that is reflected in the potassium-argonand rubidium-strontium biotite ages of the metamorphic rocks.     

Detection of interstellar ethylene oxide (c-C2H4O)

We report the identification of 10 transitions that support the detection of the small cyclic molecule ethylene oxide (c-C2H4O) in Sgr B2N. Although one of these transitions is severely blended, so that an accurate intensity and line width could not be determined, and two other lines are only marginally detected, we have done Gaussian fits to the remaining seven lines and have performed a rotation diagram analysis. Our results indicate a rotation temperature T(rot) = 18 K and a molecular column density N(c-C2H4O) = 3.3 x 10(14) cm-2, corresponding to a fractional abundance relative to molecular hydrogen of order 6 x 10(-11). This is a factor of more than 200 higher than the abundance for this molecule suggested by the "new standard" chemistry model of Lee, Bettens, & Herbst. This result suggests that grain chemistry might play an effective role in the production of c-C2H4O. No transitions of this molecule were detected in either Sgr B2M or Sgr B2NW.     

An upper limit to the acetylene abundance toward BN in the Orion molecular cloud

We report a search for the acetylene (C2H2) nu 3 infrared vibration-rotation absorption near 3 micrometers toward the Becklin-Neugebauer source in the Orion molecular cloud. The relative abundance of C2H2/CO in the quiescent gas (9 km s-1 component) is less than 3 x 10(-3) (5 sigma).