The Nootka Fault Zone — a new plate boundary off western Canada

Summary. Relative motion across a boundary between the main Juan de Fuca plate and its northern extension, the Explorer plate, had earlier been suggested from sea-floor magnetic anomaly analysis and from earthquakes recorded on the western Canada land seismic network. The location of the boundary, called the Nootka fault zone, and the motion across it have been examined through seismic reflection profiles, accurate location of earthquakes with an array of ocean bottom seismometers and through analysis of magnetic, gravity and bathymetric data. The fault zone extends from a ridge-fault—fault triple point at the northern end of the Juan de Fuca ridge to a fault—trench—trench triple junction at the margin off north-central Vancouver Island. The active portion of the fault zone is about 20 km wide, and has produced extensive disturbance in the 0.5 to 1 km of overlying sediments. Magnetic anomaly analysis suggests present left-lateral strike slip motion of about 3 cm/yr, with convergence at the margin being more rapid to the south than to the north of the fault zone. Because of rapidly changing spreading parameters on the Explorer and Juan de Fuca ridges over the past 5 Myr the Nootka fault zone has had a very complex history.     

Local Lorentz transformation and exact solution in f(T) gravity theories

A general tetrad fields, with an arbitrary function of radial coordinate, preserving spherical symmetry, is provided. Such tetrad is split into two matrices: The first matrix represents a Local Lorentz Transformation (LLT), which contains an arbitrary function. The second matrix represents a proper tetrad fields which satisfy the field equations of f(T) gravitational theory. This general tetrad is applied to the field equations of f(T). We derive a solution with one constant of integration to the resulting field equations of f(T). This solution gives a vanishing value of the scalar torsion. We calculate the energy associated with this solution to investigate what is the nature of the constant of integration.     

Survival of organic phases in porous IDPs during atmospheric entry: A pulse‐heating study

Abstract— In this study, we have performed pulse‐heating experiments at different temperatures for three organic molecules (a polycyclic aromatic hydrocarbon [PAH], a ketone, and an amino acid) absorbed into microporous aluminum oxide (Al₂O₃) in order to imitate the heating of the organic molecules in interplanetary dust particles (IDPs) and micrometeorites (MMs) during atmospheric entry and to investigate their survival. We have shown that modest amounts (a few percent) of these organic molecules survive pulse‐heating at temperatures in the 700 to 900 °C range. This suggests that the porosity in IDPs and MMs, combined with a sublimable phase (organic material, water), produces an ablative cooling effect, which permits the survival of organic molecules that would otherwise be lost either by thermal degradation or evaporation during atmospheric entry.     

Microfossils from the Lower Kundelungu (Late Precambrian) of Zambia

Lower Kundelungu black argillites and silty dolomicrites from the Ndola area contain a rich microfossil assemblage, of which several forms can be attributed to the form-genus Fibularix Pflug, 1965. The same assemblage has also been found in fine-grained, mildly metamorphosed sedimentary rocks from Kalengwa and Karibarembi (North-Western Province). These findings support the Kundelungu correlation of the Kalengwa and Karibarembi successions.Three new species of Fibularix are described and illustrated. Seven types of sphaeromorphs are described and illustrated, though treated informally. Some sphaeromorphs are detached parts of Fibularix chains.The Lower Kundelungu microfossils resemble very closely some palynomorphs that occur in the Brioverian (Late Precambrian) of France, in the Libby Formation (Belt) of the northwestern United States, and in other formations of Late Precambrian age.     

Hanford tank residual waste – Contaminant source terms and release models

Residual waste is expected to be left in 177 underground storage tanks after closure at the US Department of Energy’s Hanford Site in Washington State, USA. In the long term, the residual wastes may represent a potential source of contamination to the subsurface environment. Residual materials that cannot be completely removed during the tank closure process are being studied to identify and characterize the solid phases and estimate the release of contaminants from these solids to water that might enter the closed tanks in the future. As of the end of 2009, residual waste from five tanks has been evaluated. Residual wastes from adjacent tanks C-202 and C-203 have high U concentrations of 24 and 59 wt.%, respectively, while residual wastes from nearby tanks C-103 and C-106 have low U concentrations of 0.4 and 0.03 wt.%, respectively. Aluminum concentrations are high (8.2–29.1 wt.%) in some tanks (C-103, C-106, and S-112) and relatively low (<1.5 wt.%) in other tanks (C-202 and C-203). Gibbsite is a common mineral in tanks with high Al concentrations, while non-crystalline U–Na–C–O–P ± H phases are common in the U-rich residual wastes from tanks C-202 and C-203. Iron oxides/hydroxides have been identified in all residual waste samples studied to date. Contaminant release from the residual wastes was studied by conducting batch leach tests using distilled deionized water, a Ca(OH)₂-saturated solution, or a CaCO₃-saturated water. Uranium release concentrations are highly dependent on waste and leachant compositions with dissolved U concentrations one or two orders of magnitude higher in the tests with high U residual wastes, and also higher when leached with the CaCO₃-saturated solution than with the Ca(OH)₂-saturated solution. Technetium leachability is not as strongly dependent on the concentration of Tc in the waste, and it appears to be slightly more leachable by the Ca(OH)₂-saturated solution than by the CaCO₃-saturated solution. In general, Tc is much less leachable (<10 wt.% of the available mass in the waste) than previously predicted. This may be due to the coprecipitation of trace concentrations of Tc in relatively insoluble phases such as Fe oxide/hydroxide solids.     

Residual deformations and seismic hazard of fault zones in underground workings

The results of long-term measurements of residual deformations in the area of the Severomuiskii tunnel during its construction are given. Comparison of spatial and temporal distributions between deformations and earthquakes shows that they are interrelated. The nonlinear behavior of disintegrated and waterlogged rocks within tectonic fault zones should be taken into account even for moderate intensity earthquakes, since they are accompanied by ground subsidence. Underground workings within such sites are subjected to loads that are greater than expected according to current hypotheses, which are the basis for calculations of rock pressure. It is established that the most probable mechanism of ground subsidence and residual deformation in underground workings could be the gravity load of the overlying strata of disintegrated and waterlogged rocks within a fault zone, which leads to instability of the rocks. Approximate stress estimations are made on the basis of the results of measurements of residual deformations of roof supports (linings).     

Improved Resolution of Ambient Flow through Fractured Rock with Temperature Logs

In contaminant hydrogeology, investigations at fractured rock sites are typically undertaken to improve understanding of the fracture networks and associated groundwater flow that govern past and/or future contaminant transport. Conventional hydrogeologic, geophysical, and hydrophysical techniques used to develop a conceptual model are often implemented in open boreholes under conditions of cross-connected flow. A new approach using high-resolution temperature (±0.001°C) profiles measured within static water columns of boreholes sealed using continuous, water-inflated, flexible liners (FLUTe™) identifies hydraulically active fractures under ambient (natural) groundwater flow conditions. The value of this approach is assessed by comparisons of temperature profiles from holes (100 to 200 m deep) with and without liners at four contaminated sites with distinctly different hydrogeologic conditions. The results from the lined holes consistently show many more hydraulically active fractures than the open-hole profiles, in which the influence of vertical flow through the borehole between a few fractures masks important intermediary flow zones. Temperature measurements in temporarily sealed boreholes not only improve the sensitivity and accuracy of identifying hydraulically active fractures under ambient conditions but also offer new insights regarding previously unresolvable flow distributions in fractured rock systems, while leaving the borehole available for other forms of testing and monitoring device installation.