(Table T1) Density, porosity, void ratio, diffusivity and permeability of ODP Site 185-1149 sediments

The subduction of oceanic plates regulates crustal growth, influences arc volcanism, and refertilizes the mantle. Continental growth occurs by subduction of crustal material (seawater components, marine sediments, and basaltic crust). The geochemical and physical evolution of the Earth's crust depends, in large part, on the fate of subducted material at convergent margins (Armstrong, 1968, doi:10.1029/RG006i002p00175; Karig and Kay, 1981, 10.1098/rsta.1981.0108). The crustal material on the downgoing plate is recycled to various levels in the subduction zone. The recycling process that takes place in the "Subduction Factory" is difficult to observe directly but is clearly illuminated using chemical tracers. Von Huene and Scholl (1991, doi:10.1029/91RG00969) and Plank and Langmuir (1993, doi:10.1038/362739a0) preliminarily calculated a large flux of subducted materials. By mass balancing the chemical tracers and measuring the fractionations that occur between them, the Subduction Factory work and the effect on the Earth's evolution can be estimated. In order to elucidate this mass balance, Ocean Drilling Program Leg 185 drilled two deepwater shales into the oceanic crust situated in the Mariana-Izu Trenches and recovered core samples of incoming oceanic crust. The calculations of mass circulation in the subduction zone, however, did not take into account the mass transfer properties within subducted oceanic crust, although the dewatering fluid and diffused ions may play an important role in various activities such as seismogeneity, serpentine diapiring, and arc volcanism. Thus, this paper focuses on the quantitative measurements of the physical and mass transfer properties of subducted oceanic crust.

A Modeling Approach to Quantify the Effects of Stomatal Behavior and Mesophyll Conductance on Leaf Water Use Efficiency

Water use efficiency (WUE) is considered as a determinant of yield under stress and a component of crop drought resistance. Stomatal behavior regulates both transpiration rate and net assimilation and has been suggested to be crucial for improving crop WUE. In this work, a dynamic model was used to examine the impact of dynamic properties of stomata on WUE. The model includes sub-models of stomatal conductance dynamics, solute accumulation in the mesophyll, mesophyll water content, and water flow to the mesophyll. Using the instantaneous value of stomatal conductance, photosynthesis, and transpiration rate were simulated using a biochemical model and Penman-Monteith equation, respectively. The model was parameterized for a cucumber leaf and model outputs were evaluated using climatic data. Our simulations revealed that WUE was higher on a cloudy than a sunny day. Fast stomatal reaction to light decreased WUE during the period of increasing light (e.g., in the morning) by up to 10.2% and increased WUE during the period of decreasing light (afternoon) by up to 6.25%. Sensitivity of daily WUE to stomatal parameters and mesophyll conductance to CO2 was tested for sunny and cloudy days. Increasing mesophyll conductance to CO2 was more likely to increase WUE for all climatic conditions (up to 5.5% on the sunny day) than modifications of stomatal reaction speed to light and maximum stomatal conductance.

Analyses of permeability and porosity of sedimentary rocks in terms of unconventional geothermal resource explorations in Poland

Petrophysical investigations are fundamental to natural resource exploration. In order to recognise the geothermal potential of sedimentary rocks in central Poland, 259 samples were collected from prospective deep-lying geothermal reservoirs. Parameters measured include bulk density, skeletal density, effective porosity, permeability, average pore diameter and specific surface. Results indicate that at great depths (mostly > 3,000 m below surface) sedimentary rocks show low values of porosity (mainly less than 5%) and permeability (only sporadically in excess of 1 md). These values call for a petrothermal use of reservoirs, for which an Enhanced Geothermal System (EGS) was developed. Reser- voirs suited for the EGS are Carboniferous and Lower Triassic sandstones in the central part of Poland (Mogilno-Łódź Trough region and a small part of the Kujawy Swell and Fore-Sudetic regions). In addition, Carboniferous limestones in this area are potentially prospective.

Porosity in ion-exchanged and acid activated clays evaluated using n-nonane pre-adsorption

The applicability of the n-nonane pre-adsorption method for characterising the porosity in clays is presented. Na-SD, a Na+-exchanged purified bentonite, and materials obtained by Al3+-exchange and acid treatments of Na-SD and SAz-1 were used. Nitrogen adsorption isotherms, at -196 ºC, were determined before and after n-nonane pre-adsorption on each of the samples. In all materials, n-nonane remained adsorbed in ultramicropores after outgassing at 25 ºC. Outgassing at higher temperatures (50, 75 and 200 ºC) removed nonane and ultramicropores became available for nitrogen adsorption. All treatments on Na-SD led to increase in micropore volume. Larger ultramicropore and supermicropore volumes were obtained for Na-SD acid activated with HCl at 95 ºC than for treatments at 25 ºC with HCl or following Al3+-exchange (Al-SD), and increased with increasing acid concentration to 3 M. Activation with 4 M HCl led to the largest pore volume with contribution from mesopores. However, the specific external surface area was the same as that obtained for Na-SD, Al-SD and for most of the other acid activated samples. Treatments at 95 ºC with 1 M and 6 M HCl promoted increase in specific external surface area. The micropore volumes and specific external surface area for SAz-1 treated with 1 M HCl at 95 ºC were larger than those of Al-SAz-1, but lower than those obtained for corresponding materials derived from Na-SD. The n-nonane pre-adsorption method enabled micropore volumes and specific external surface areas to be obtained for all samples.

Investigating the mesh dependency and upscaling of 3D grain-based models for the simulation of brittle fracture processes in low-porosity crystalline rock

The application of 3D grain-based modelling techniques is investigated in both small and large scale 3DEC models, in order to simulate brittle fracture processes in low-porosity crystalline rock. Mesh dependency in 3D grain-based models (GBMs) is examined through a number of cases to compare Voronoi and tetrahedral grain assemblages. Various methods are used in the generation of tessellations, each with a number of issues and advantages. A number of comparative UCS test simulations capture the distinct failure mechanisms, strength profiles, and progressive damage development using various Voronoi and tetrahedral GBMs. Relative calibration requirements are outlined to generate similar macro-strength and damage profiles for all the models. The results confirmed a number of inherent model behaviors that arise due to mesh dependency. In Voronoi models, inherent tensile failure mechanisms are produced by internal wedging and rotation of Voronoi grains. This results in a combined dependence on frictional and cohesive strength. In tetrahedral models, increased kinematic freedom of grains and an abundance of straight, connected failure pathways causes a preference for shear failure. This results in an inability to develop significant normal stresses causing cohesional strength dependence. In general, Voronoi models require high relative contact tensile strength values, with lower contact stiffness and contact cohesional strength compared to tetrahedral tessellations. Upscaling of 3D GBMs is investigated for both Voronoi and tetrahedral tessellations using a case study from the AECL’s Mine-by-Experiment at the Underground Research Laboratory. An upscaled tetrahedral model was able to reasonably simulate damage development in the roof forming a notch geometry by adjusting the cohesive strength. An upscaled Voronoi model underestimated the damage development in the roof and floor, and overestimated the damage in the side-walls. This was attributed to the discretization resolution limitations.