scholarly journals Water loss during dynamic recrystallization of Moine thrust quartzites, northwest Scotland

Geology ◽  
2020 ◽  
Vol 48 (6) ◽  
pp. 557-561
Author(s):  
Andreas K. Kronenberg ◽  
Kyle T. Ashley ◽  
Matthew K. Francsis ◽  
Caleb W. Holyoke III ◽  
Lynna Jezek ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Water Content ◽  
Water Concentration ◽  
Inverse Correlation ◽  
High Water ◽  
Dislocation Creep ◽  
Molecular Water ◽  
Reduced Water ◽  
Water Contents ◽  
Absorption Measurements

Abstract Infrared absorption measurements of molecular water in sheared Cambrian quartzites in the footwall to the Moine thrust reveal a decrease in water content from 4080 to 1570 ppm with increasing recrystallization traced toward the overlying thrust at the Stack of Glencoul in northwest Scotland. These results are contrary to the expected correlation between shear strain and water content for quartz deformed by dislocation creep and water-weakening processes. The observed inverse correlation indicates that fluid inclusions and hydrous defects within grains were lost by mobile grain boundary sweeping and grain boundary diffusion. Although reduced water contents might lead to hardening as chemical weakening is diminished, quartz mylonites in the immediate footwall (5 mm) to the thrust are characterized by intense strain localization and contain the least water, and there is little evidence of shear zone widening. Water weakening appears to have been important throughout the quartz mylonites, controlled by the presence of water, not by water concentration. Fluids present within relict inclusions and at grain boundaries may have governed the high water fugacities critical for water weakening.

scholarly journals Synchrotron FTIR imaging of OH in quartz mylonites

Solid Earth ◽  
2017 ◽  
Vol 8 (5) ◽  
pp. 1025-1045 ◽  
Author(s):  
Andreas K. Kronenberg ◽  
Hasnor F. B. Hasnan ◽  
Caleb W. Holyoke III ◽  
Richard D. Law ◽  
Zhenxian Liu ◽  
...  
Keyword(s):  
Water Content ◽  
Point Defects ◽  
Fluid Inclusions ◽  
Hanging Wall ◽  
Molecular Water ◽  
Main Central Thrust ◽  
Absorption Bands ◽  
Uniform Equilibrium ◽  
Quartz Grains ◽  
Water Contents

Abstract. Previous measurements of water in deformed quartzites using conventional Fourier transform infrared spectroscopy (FTIR) instruments have shown that water contents of larger grains vary from one grain to another. However, the non-equilibrium variations in water content between neighboring grains and within quartz grains cannot be interrogated further without greater measurement resolution, nor can water contents be measured in finely recrystallized grains without including absorption bands due to fluid inclusions, films, and secondary minerals at grain boundaries.Synchrotron infrared (IR) radiation coupled to a FTIR spectrometer has allowed us to distinguish and measure OH bands due to fluid inclusions, hydrogen point defects, and secondary hydrous mineral inclusions through an aperture of 10 µm for specimens > 40 µm thick. Doubly polished infrared (IR) plates can be prepared with thicknesses down to 4–8 µm, but measurement of small OH bands is currently limited by strong interference fringes for samples < 25 µm thick, precluding measurements of water within individual, finely recrystallized grains. By translating specimens under the 10 µm IR beam by steps of 10 to 50 µm, using a software-controlled x − y stage, spectra have been collected over specimen areas of nearly 4.5 mm2. This technique allowed us to separate and quantify broad OH bands due to fluid inclusions in quartz and OH bands due to micas and map their distributions in quartzites from the Moine Thrust (Scotland) and Main Central Thrust (Himalayas).Mylonitic quartzites deformed under greenschist facies conditions in the footwall to the Moine Thrust (MT) exhibit a large and variable 3400 cm−1 OH absorption band due to molecular water, and maps of water content corresponding to fluid inclusions show that inclusion densities correlate with deformation and recrystallization microstructures. Quartz grains of mylonitic orthogneisses and paragneisses deformed under amphibolite conditions in the hanging wall to the Main Central Thrust (MCT) exhibit smaller broad OH bands, and spectra are dominated by sharp bands at 3595 to 3379 cm−1 due to hydrogen point defects that appear to have uniform, equilibrium concentrations in the driest samples. The broad OH band at 3400 cm−1 in these rocks is much less common. The variable water concentrations of MT quartzites and lack of detectable water in highly sheared MCT mylonites challenge our understanding of quartz rheology. However, where water absorption bands can be detected and compared with deformation microstructures, OH concentration maps provide information on the histories of deformation and recovery, evidence for the introduction and loss of fluid inclusions, and water weakening processes.

An Equilibrium Model of Leaf Water Potentials Which Separates Intra- and Extracellular Potentials

1975 ◽  
Vol 2 (3) ◽  
pp. 253 ◽  
Author(s):  
B Acock
Keyword(s):  
Water Content ◽  
Turgor Pressure ◽  
Bound Water ◽  
Leaf Tissue ◽  
High Water ◽  
Leaf Water ◽  
High Water Content ◽  
Pressure Potential ◽  
Matrix Bound ◽  
Water Contents

A model is proposed which makes it possible to estimate the intracellular turgor pressure potential, intracellular osmotic plus matric potential, and intra- and extracellular soIution fractions of water in leaf tissue at any water content. The model requires only the data normally collected with a thermocouple psychrometer: total water potential of live and dead (cells ruptured) tissue at various known water contents. The major assumptions are that (1) the total potential of water in the solution fraction in any part of the tissue multiplied by the volume of water is constant; (2) extracellular water experiences no pressure potential; (3) matrix-bound water is held only by matric forces and contains no solute; (4) the solution fraction of the intracellular water is constant at high water content; and (5) matrix-bound water content is constant over the range of leaf water contents normally examined. The models developed to deal with pressure bomb data are examined critically and doubts are cast on the validity of some of their assumptions.

scholarly journals Capillary Mats Alter the Water Content in Medium during Mist Propagation of Dendranthema

HortScience ◽  
2004 ◽  
Vol 39 (3) ◽  
pp. 584-587 ◽  
Author(s):  
R.L. Geneve ◽  
S.T. Kester ◽  
J.W. Buxton
Keyword(s):  
Water Content ◽  
Water Table ◽  
Relative Water Content ◽  
Water Status ◽  
Internal Water ◽  
Relative Water ◽  
Reduced Water ◽  
Water Contents

A capillary mat-mist system was developed to provide near constant media water contents at differing quantities of mist. Media water contents were reduced by increasing the capillary mat height above a constant water table maintained at bench level. Increased tensions from 0 to 10 cm above the water table reduced water content in Oasis, rockwool, and peat-perlite by 35.4%, 27.6%, and 17.4%, respectively. There was no difference in water content for each medium when the mist quantity ranged between 600 and 1800 mL·m-2·h-1, except when the capillary mat was at 9 cm above the water table and mist volume was 300 mL·m-2·h-1. Chrysanthemum cuttings rooted best when water content was highest regardless of media. Using the peat-perlite medium, water content had the greatest impact on rooting when the mist volume was low (600 mL·m-2·h-1). Relative water content of cuttings was lowest during the first 5 days of sticking and both reduced media water content and mist quantity resulted in the lowest internal water status for the cuttings.

STUDIES IN TREE PHYSIOLOGY: I. GENERAL INTRODUCTION. WATER CONTENTS OF CERTAIN CANADIAN TREES

1939 ◽  
Vol 17c (12) ◽  
pp. 460-482 ◽  
Author(s):  
R. Darnley Gibbs
Keyword(s):  
Water Content ◽  
Populus Tremuloides ◽  
Weather Conditions ◽  
High Water ◽  
High Water Content ◽  
White Pine ◽  
General Introduction ◽  
Very High ◽  
Considerable Loss ◽  
Water Contents

Previous work by the author on the water contents of Canadian trees is reviewed and followed by a brief discussion of questions yet to be answered.In Betula alba v. papyrifera, in at least the young parts of B. alba v. pendula laciniata, in B. populifolia, and in several sizes of Populus tremuloides, there is a marked seasonal rhythm in water content. The maximum is at leaf opening, the minimum at leaf fall. In poplar but not in birch there is a very high water content in December. During winter a considerable loss of water may occur. A winter loss is shown also by the wood of hemlock and larch and by twigs and leaves of white pine and hemlock. Losses from leaves are surprisingly small.The behaviour of B. populifolia has been studied for more than three years, and differences have been correlated with observations on weather conditions. Experimental work on movement of water in this species during winter is inconclusive. This work continues.

Influence of clod size and water content on gas permeability of a compacted loess

2014 ◽  
Vol 51 (12) ◽  
pp. 1468-1474 ◽  
Author(s):  
T.L.T. Zhan ◽  
Y.B. Yang ◽  
R. Chen ◽  
C.W.W. Ng ◽  
Y.M. Chen
Keyword(s):  
Water Content ◽  
Power Function ◽  
Soil Structure ◽  
Gas Permeability ◽  
High Water ◽  
Degree Of Saturation ◽  
Northwestern Region ◽  
Water Contents ◽  
Compacted Loess ◽  
Compaction Degree

The northwestern region of China is mainly semi-arid to arid and loess is ubiquitous. This natural resource has considerable potential to be transformed into earthen final covers for local landfills, but first its suitability must be ascertained through extensive tests. In this study, a device was developed to measure the gas permeability of unsaturated compacted loess specimens. Experiments were carried out to investigate the influence of clod size, compaction water content, and post-compaction water content on the gas permeability of the compacted loess. To maintain an identical soil structure, the post-compaction water content was changed using the osmotic technique. It was found that the compaction water content and resultant soil clod size exerted a combined effect on the gas permeability such that, at low water contents, the gas permeability remained fairly constant, but at high water contents the clods became relatively large, and the effect of the clod size dominated the water blockage effect from increasing water content. For specimens with identical soil structure, the gas permeability decreased with the increasing post-compaction degree of saturation at an accelerated rate. A power function is proposed to predict the relationship between the gas permeability normalized by the porosity function of the Kozeny–Carmen model and the post-compaction degree of saturation. Analysis of the experimental data indicates that the parameters for the power function still depend on the porosity of the compacted loess, particularly at high degrees of saturation.

Isothermal micro-calorimetry: a tool to predict seed longevity?

2006 ◽  
Vol 16 (2) ◽  
pp. 89-96 ◽  
Author(s):  
Fiona R. Hay ◽  
Michael A.A. O'Neill ◽  
Anthony E. Beezer ◽  
Simon Gaisford
Keyword(s):  
Heat Flow ◽  
Water Content ◽  
High Water ◽  
Seed Longevity ◽  
Total Heat ◽  
Short Term ◽  
Seed Ageing ◽  
Rate Kinetics ◽  
Residual Power ◽  
Water Contents

This paper describes the exploratory use of isothermal micro-calorimetry (IMC) to measure directly the heat flow produced as seeds age. Heat flow was recorded in primed and non-primed (control) seeds of Ranunculus sceleratus L., aged in a micro-calorimeter at 35°C at three different seed water contents [c. 0.12, 0.075 and 0.045 g H2O (g dw)−1]. The rate of heat flow and total heat generated (an indicator of extent of reaction) were generally greater in control seeds, which aged at a faster rate, than in primed seeds. Total heat generated over a given period also increased with increasing water content. The power–time curves did not indicate first- or second-order rate kinetics, consistent with the probability that seed ageing is complex and involves a number of reactions. Even after the capacity to germinate had ceased, there was a residual power signal. As a method, IMC gave consistent results using independent samples at different times. Therefore, short-term experiments at relatively high water contents and/or temperatures may have the potential to predict the relative longevity of seed-lots, at least within a species.

Aqueous Diffusion in Repository and Backfill Environments

1992 ◽  
Vol 294 ◽  
Author(s):  
James L. Conca ◽  
Mick Apted ◽  
Randy Arthur
Keyword(s):  
Diffusion Coefficient ◽  
Water Content ◽  
Surface Diffusion ◽  
High Water ◽  
Double Layers ◽  
Point Contacts ◽  
Simple Diffusion ◽  
Time Period ◽  
Engineered Systems ◽  
Water Contents

ABSTRACTAqueous diffusion coefficients have been experimentally determined in a variety of porous/fractured geologic and engineered media. For performance assessment applications, the purely diffusive flux must be separated from retardation effects. The simple diffusion coefficient, D, does not include any transient chemical effects, e.g., sorption, which lower the diffusion coefficient for some finite time period until equilibrium is reached. D is primarily a function of volumetric water content, θ, and not material characteristics. At high water contents, D gradually declines as water content decreases, from 10−5 cm2/sec at θ ∼ 50% to 10−7 cm2/sec at θ ∼ 5%, followed by a sharp decline to 10−10 cm2/sec at θ ∼ 0.5%. Although surface diffusion has a strong experimental basis in the transport of gases along metal surfaces, experimental evidence for aqueous geologic/backfill/engineered systems strongly indicates that surface diffusion is not important, even in bentonite, because of the extremely poor connectivity among electric double-layers and the extremely low diffusivities and high ∂C/∂x at small area/point contacts which more than negate the increased flux along intragrain surfaces.

scholarly journals Viability and germination of Scots pine seeds after freezing of harvested cones in vitro

2016 ◽  
Vol 46 (8) ◽  
pp. 1035-1041
Author(s):  
Markku Nygren ◽  
Katri Himanen ◽  
Hanna Ruhanen
Keyword(s):  
Water Content ◽  
Scots Pine ◽  
Seed Viability ◽  
High Water ◽  
Logistic Function ◽  
High Water Content ◽  
Maturation Stage ◽  
Freezing Treatment ◽  
Water Contents

Scots pine (Pinus silvestris L.) cone and seed water contents were analyzed in two consecutive seasons during maturation stage in the autumn and in January and March before seed dispersal. Cones with different water contents were subjected to 2 h of freezing at −30 °C, and seed viability and laboratory germination of seeds from individual cones after treatment were analyzed. Seed water content could be well predicted with the measurement of the cone water content, and the general relationship between these two could be described with a generalized logistic function. On average, the water content of cones was 5%–10% units higher than the seeds inside them. The higher the cone water content at the onset of freezing treatment, the higher the proportion of seeds with apparent damage (based on visual inspection of seeds using X-ray images) in that particular cone. High water content in cones also resulted in decreased germination after freezing treatment. The critical cone water content for 50% germination after freezing at −30 °C was approximately 31.3% (fresh mass basis). This corresponds to 21.6% water content in seeds.

scholarly journals Experimental Study on Dynamic Tensile Failure of Sandstone Specimens with Different Water Contents

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Ming Li ◽  
Gang Lin ◽  
Wei Zhou ◽  
Xianbiao Mao ◽  
Lianying Zhang ◽  
...  
Keyword(s):  
Crack Propagation ◽  
Water Content ◽  
Water Saturation ◽  
Water Injection ◽  
High Water ◽  
Tensile Failure ◽  
High Water Content ◽  
Dynamic Tensile Strength ◽  
Macroscopic Crack ◽  
Water Contents

Understanding the effect of water saturation on dynamic failure of rocks is of great importance to tunnel excavation at water-rich coal mines and prevention of rock bursts by water injection. Dynamic Brazilian disc tests are performed to study mechanical behaviour of sandstones in this paper. The results indicate that water saturation significantly weakens the dynamic tensile strength of sandstones and increases the specimen strain at which the specimen fails. The damage degree of sandstones reduces gradually with increasing water contents. Failure of the sandstone specimen includes the crack initiation at the center of the specimen, macroscopic crack propagation, and stretch of the macroscopic crack through the specimen. In addition, parallel macroscopic crack propagation is found in the specimen with a low water content. From the observation of fracture sections, microstructures are compact in the specimen with high water contents. This is due to the swell of the kaolinite in the specimen after water saturation. The failure mechanism of microstructures is typical brittle failure in the specimen with a high water content, whereas ductile fracture is found in the specimen with a low water content. Different failure processes of microstructures lead to the differences between mechanical properties and macroscopic failure characteristics of the specimens with various water contents.

Thermodynamic Limitations of Ice Accretion Instruments

1953 ◽  
Vol 34 (4) ◽  
pp. 146-154 ◽  
Author(s):  
D. Fraser ◽  
C. K. Rush ◽  
D. Baxter
Keyword(s):  
Water Content ◽  
Water Concentration ◽  
Supercooled Water ◽  
Rotating Cylinder ◽  
Thermal Method ◽  
Ice Accretion ◽  
Rotating Disc ◽  
Limited Usefulness ◽  
Water Contents ◽  
Detector Head

A number of instruments used for determining the supercooled water content of an icing cloud depend on measuring the rate of accretion of ice on an unheated body. It has been shown by Ludlam that, since only part of the supercooled water freezes on impact, and the rest cannot always be frozen by the limited convective and evaporative heat losses which are available, there are limiting water contents beyond which such methods of measurement are unreliable. These limits have been calculated for a rotating cylinder at normal and high flight speeds, and the results show that rotating cylinder measurements are of limited usefulness and may, in fact, prove entirely misleading as regards both water content and droplet size. Experimental results show agreement with the calculated values. The limits for a conventional rotating-disc rate-of-icing meter and for an NAE-Smith ice detector head have also been obtained experimentally. It is concluded that apart from the possibility of using refrigerated ice-accretion instruments, it is necessary to use a thermal method of measuring high values of water concentration, but that an ice-accretion method must also be employed to distinguish between warm water, supercooled water and ice crystals.

Sign in / Sign up

Export Citation Format

Share Document