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  • 1
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    Book reviews (1979)
    Springer
    Details
    Publication Date: 1979-01-01
    Print ISSN: 0343-2521
    Electronic ISSN: 1572-9893
    Topics: Geography
    Published by Springer
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    PAPER CURRENT
  • 2
    Electronic Resource
    Electronic Resource
    The sliding characteristics of sandstone on quartz fault-gouge (1975)
    Springer
    Pure and applied geophysics 113 (1975), S. 69-86 
    Details
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary Three types of triaxial compression experiments are used to characterize the frictional processes during sliding on quartz gouge. They are: 1) pre-cut Tennessee Sandstone sliding on an artificial layer of quartz gouge; 2) fractured Coconino Sandstone sliding along experimentally produced shear fractures; and 3) a fine-grained quartz aggregate deformed in compression. The specimens were deformed to 2.0 kb confining pressure at room temperature and displacement rates from 10−2 to 10−5 cm/sec dry and with water. There is a transition in sliding mode from stick-slip at confining pressures〈0.7 kb to stable sliding at〉0.7 kb. This transition is accompanied by a change from sliding at the sandstone-gouge contact (stick-slip) to riding on a layer of cataclastically flowing gouge (stable sliding). Quartz gouge between the pre-cut surfaces of Tennessee Sandstone lowers both the kinetic coefficient of friction and the magnitude of the stick-slip stress drops compared to those for a pre-cut surface alone. Stick-slip stress drops are preceded by stable sliding at displacements of 10−5 cm/sec. For a decrease in displacement rate between 10−3 and 10−5 cm/sec, stress-drops magnitudes increase from 25 to 50 bars. Tests on saturated quartz gouge show sufficient permeability to permit fluidpressure equilibrium within compacted gouge in 10 to 30 seconds; thus the principle of effective stress should hold for the fault zone with quartz gouge. Our results suggest that at effective confining pressures of less than 2.0 kb, if a fault zone contains quartz gouge, laboratory-type stick-slip can be an earthquake-source mechanism only if a planar sliding-surface develops, and then only when the effective confining pressure is less than 0.7 kb.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01592900
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  • 3
    Electronic Resource
    Electronic Resource
    Implications for mechanical properties of brittle faults from observations of the Punchbowl fault zone, California (1986)
    Springer
    Pure and applied geophysics 124 (1986), S. 79-106 
    Details
    ISSN: 1420-9136
    Keywords: Deformation ; faults ; cataclasis ; gouge ; rock mechanics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Field observations of the Punchbowl fault zone, an inactive trace of the San Andreas, are integrated with results from experimental deformation of naturally deformed Punchbowl fault rocks for a qualitative description of the mechanical properties of the fault and additional information for conceptual models of crustal faulting. The Punchbowl fault zone consists of a single, continuous gouge layer bounded by zones of extensively damaged host rock. Fault displacements were not only localized to the gouge layer, but also to discrete shear surfaces within the gouge. Deformation in the exposure studied probably occurred at depths of 2 to 4 km and was dominated by cataclastic mechanisms. Textural data also suggest that significant amounts of pore fluids were present during faulting, and that fluid-assisted mechanisms, such as dissolution, diffusion, and precipitation, were operative. The experimental data on specimens collected from the fault zone suggest that there is a gradual decrease in strength and elastic modulus and an increase in relative ductility and permeability toward the main gouge zone. The gouge layer has fairly uniform mechanical properites, and it has significantly lower strength, elastic modulus, and permeability than both the damaged and the undeformed host rock. For the Punchbowl fault and possibly other brittle faults, the variations in loading of the gouge zone with time are primarily governed by the morphology of the fault and the mechanical properties of the damaged host rock. In addition, the damaged zone acts as the permeable unit of the fault zone and surrounding rock. It appears that the gouge primarily governs whether displacements are localized, and it therefore may have a significant influence on the mode of slip.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00875720
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  • 4
    Electronic Resource
    Electronic Resource
    The effect of normal stress on the real area of contact during frictional sliding in rocks (1986)
    Springer
    Pure and applied geophysics 124 (1986), S. 471-485 
    Details
    ISSN: 1420-9136
    Keywords: Frictional sliding ; real area of contact ; normal stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The real area of contact during frictional sliding has been determined as a function of changing normal stress in triaxial experiments through the use of thermodyes. Utilizing the technique, described by Teufel and Logan in 1978, with saw-cut surfaces inclined 35° to the load axis, determinations were made for monolithologic sliding of Tennessee sandstone and Indiana limestone and dilithologic sliding of the same rocks. Confining pressures to 200 MPa were investigated at a constant shortening rate of 10−2 mm/sec and at room temperature. Direct measurements were made of single-asperity areas and the asperity density. The product of these measurements gives the percent area of real contact across the sliding surface. Single-asperity area and density are found to remain relatively constant during the displacement. Single-asperity areas are in the ranges of 0.4 to 6×10−2 mm2 for sandstone, 0.8 to 2×10−2 mm2 for limestone, and 0.2 to 24×10−2 mm2 for sandstone sliding against limestone. These values are smaller than the grain size of either rock. The values increase with increasing normal stress for both monolithologic and dilithologic sliding. In sandstone the asperity density increases from about 0.8 to 2.75 contacts per square millimeter in a logarithmic fashion. Monolithologic limestone has values of about 0.9 contacts per square millimeter and does not show significant change with increasing normal stress. The percent area of real contact increases in all cases, with average maximum values of 16% of the apparent area at a normal stress of 374 MPa in sandstone, 18% at 25 MPa in limestone, and 22% at 123 MPa in the dilithologic specimens. The normal stress recalculated for the real area of contact approaches the unconfined compressive strength for sandstone and limestone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00877212
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of displacement rate on the real area of contact and temperatures generated during frictional sliding of Tennessee sandstone (1978)
    Springer
    Pure and applied geophysics 116 (1978), S. 840-865 
    Details
    ISSN: 1420-9136
    Keywords: Frictional sliding ; Stick-up ; Temperature measurements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary The real area of contact has been determined, and measurements of the maximum and average surface temperatures generated during frictional sliding along precut surfaces in Tennessee sand-stone have been made, through the use of thermodyes. Triaxial tests have been made at 50 MPa confining pressure and constant displacement rates of 10−2 to 10−6 cm/sec, and displacements up to 0.4 om. At 0.2 cm of stable sliding, the maximum temperature decreases with decreasing nominal displacement rate from between 1150° to 1175°C at 10−2 cm/sec to between 75° to 115°C at 10−3 cm/sec. The average temperature of the surface is between 75 and 115°C at 10−2 cm/sec, but shows no rise from room temperature at 10−3 cm/sec. At 0.4 cm displacement, and in the stick-slip mode, as the nominal displacement rate decreases from 10−3 to 10−6 cm/sec, the maximum temperature decreases from between 1120° to 1150°C to between 1040° to 1065°C. The average surface temperature is 115° to 135°C at displacement rates from 2.6×10−3 to 10−4 cm/sec. With a decrease in the displacement rate from 10−2 to 10−6 cm/sec, the real area of contact increases from about 5 to 14 percent of the apparent area; the avergge area of asperity contact increases from 2.5 to 7.5×10−4 cm2. Although fracture is the dominate mechanism during stick-up thermal softening and creep may also contribute to the unstable sliding process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00876541
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  • 6
    Electronic Resource
    Electronic Resource
    Creep, stable sliding, and premonitory slip (1978)
    Springer
    Pure and applied geophysics 116 (1978), S. 773-789 
    Details
    ISSN: 1420-9136
    Keywords: Creep ; Stable sliding ; Premonitory slip ; Gouge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary The current status of laboratory investigations into creep, stable sliding and premonitory slip is reviewed and some new material is presented. It is postulated that pre-cut rocks and those with simulated gouge layers undergo a transition with increasing confining pressure from (1) stable sliding to stick-slip, to (2) sliding along the pre-cut with deformation of the country rock, to (3) homogeneous flow of the specimen without slip along the pre-cut. Stick-slip behavior is not always present. Decreasing displacement rates are found to enhance stick-slip. Mixtures of gouge are found to be significant in controlling the behavior of sliding with 10–20 percent of anhydrite mixed with quartz or clays mixed with anhydrite shifting the sliding mode from stable stick-slip or stick-slip to stable sliding, respectively. Premonitory slip may be one of the most significant short term precursors of earthquakes. Although widely recognized in the laboratory, little systematic work has been completed. Variations in pore pressure, resistivity and seismic velocities have been investigated. Clearly much work needs to be done into these topics before a clear understanding is achieved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00876538
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  • 7
    Electronic Resource
    Electronic Resource
    Potential for increased nutrient uptake by flocculating diatoms (1989)
    Springer
    Marine biology 101 (1989), S. 443-450 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Blooms of chain-forming diatoms commonly flocculate into centimeter-sized aggregates of living, vegetative cells following nutrient depletion in surface waters off southern California. We examined the hypothesis that diatom cells within aggregates experience increased nutrient uptake relative to unattached cells. We measured in situ settling velocities of 49 to 190 m d−1 and calculated porosities of 0.99931 to 0.99984 (±〉0.03%) for 12, newly-formed diatom flocs ranging from 0.19 to 4.2 cm3 in volume and 7 to 22 mm in equivalent spherical diameter. Using permeability-porosity relationships, we calculated intra-aggregate flow velocities of 20 to 160 μm s−1. Although subject to considerable uncertainty, a Relative Uptake Factor analysis based on mass transfer equqtions suggests that diatoms fixed within aggregates undergoing gravitational settling can take up nutrients up to 2.1±0.4 times faster than unattached diatoms experiencing laminar shear. Increased nutrient uptake by aggregated diatoms may be importan in understanding the reasons for diatom floc formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00541645
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  • 8
    Electronic Resource
    Electronic Resource
    A laboratory energy balance for the larvae and juveniles of the American lobster Homarus americanus (1978)
    Springer
    Marine biology 47 (1978), S. 381-389 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A laboratory energy budget was constructed for the larvae and juveniles of the American lobster Homarus americanus Milne-Edwards fed brine shrimp, Artemia saline L. Measured energy flows included ingestion, egestion, excretion of ammonia, routine and fed metabolism, growth, and production of exuvia. Digestion and assimilation were calculated and minimum ration of protein necessary to sustain larval lobsters was estimated. No change associated with metamorphosis was observed in rates of excretion, fed metabolism, and production of exuvia. Routine metabolism is not significantly higher for larvae than for juveniles. Growth changes from exponential in larvae to a slower increase in post-larvae. Consumption reflects changes in other variables. Changes in energy partitioning and energetic efficiencies associated with metamorphosis are largely due to change in rate of growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00388930
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  • 9
    Electronic Resource
    Electronic Resource
    Uptake of dissolved organics by marine bacteria as a function of fluid motion (1991)
    Springer
    Marine biology 111 (1991), S. 175-181 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A mass transfer analysis predicts that fluid motion can increase the assimilation of dissolved organics by attached compared to free-living microorganisms under certain conditions. To test this we examined the effect of advective flow and fluid shear on the uptake of model compounds (leucine and glucose) by natural assemblages of heterotrophic bacteria, collected from Roosevelt Inlet, Delaware Bay (USA), in 1989. We found that [3H]leucine uptake by cells held in fluid moving at 20 to 70 m d−1 was eight times larger than uptake by cells at a velocity of 3 m d−1. This effect was only observed at low leucine concentrations (ca. 1 nM), when uptake was likely not saturated. When we added leucine at concentrations expected to saturate leucine uptake (ca. 11 nM), fluid motion past cells did not affect uptake. Fluid flow past bacteria did not increase [3H]glucose uptake, and laminar shear rates of 0.5 to 2.1 s−1 did not increase either glucose or leucine uptake by suspended bacteria. These results indicate that fluid motion increases bacterial uptake of certain lowmolecular-weight dissolved organics only when the microorganism exists in an advective flow field. As predicted from a mass transfer model, fluid shear rates in natural systems are too low to affect bacterial uptake of such compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01986359
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  • 10
    Electronic Resource
    Electronic Resource
    Humid tropical leguminous tree and pasture grass responsiveness to vesicular-arbuscular mycorrhizal infection (1994)
    Springer
    Mycorrhiza 4 (1994), S. 233-239 
    Details
    ISSN: 1432-1890
    Keywords: Silvopastoral system ; Costa Rica ; Erythrina berteroana Urban ; Paspalum conjugatum Berg ; Homolepsis aturensis Chase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phosphorus is the major nutrient limiting plant growth in a Costa Rican silvopastoral system located on an acid, high P-retaining, volcanic soil. We investigated plant responsiveness to vesicular-arbuscular mycorrhizal (VAM) inoculation using the leguminous tree species Erythrina berteroana Urban, and the two dominant grass species Paspalum conjugatum Berg and Homolepsis aturensis Chase of this silvopastoral system. We grew grass seedlings in the greenhouse for 15 weeks in a methyl bromide-sterilized study soil to which either mixed-species VAM inoculum (Theobroma cacao feeder roots) or autoclave-sterilized cacao roots (non-inoculated control) were added. E. berteroana was grown from both seedlings and vegetative stakes (40 cm long) for 30 and 19 weeks, respectively. Upon harvest, we measured above and below ground biomass, N and P content, root∶shoot ratio, legume nodulation, and VAM infection levels. The total above-ground and root biomass of mycorrhizae-inoculated P. conjugatum seedlings were 2.5 and 2.8 times greater than those of noninoculated seedlings. In contrast, VAM-inoculated seedlings of H. aturensis produced 8.4 and 5.9 times more total above-ground and root mass than noninoculated seedlings. Mycorrhizae-inoculated E. berteroana seedlings produced 10.6 times greater shoot biomass for inoculated versus noninoculated seedlings, while E. berteroana vegetative stakes exhibited a negative growth response to VAM inoculation (an approximately 16% decrease in shoot biomass for VAM-inoculated cuttings). The difference in responsiveness between Erythrina growth forms is hypothesized to reflect the cost-benefit relationship between plant host and fungal symbiont for energy and nutrient reserves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00206785
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