experimental investigation of morphological characteristics of rill evolution on loess slope abstract the development of rill is the result of a complex interaction of soil properties with high spatial and temporal variability the rill morphology may act as a determinant as well as a stochastically driven process the description of their complex morphology requires geostatistics and nonlinear theories a study of the morphological characteristics of rill evolution was performed via indoor soil pan rainfall simulations experiments were run with loessial soil bulk density of 1 25 g cm 3 under a rainfall intensity of 90 mm h with a 20 slope gradient a detailed scan of the slope topographic analysis and statistical analyses were the main methods utilized in the study statistical analyses showed that characteristic parameters exhibited differences in the expression of the dynamic change of soil loss according to the comparison of quantitative methods we found that the fractal dimension can reflect the complexity of rill network but it is not able to reflect the dynamic changes of the erosion process perfectly in contrast geomorphologic comentropy is sensitive to the dynamic changes of soil erosion intensity and its variation can reflect the dynamic changes of erosion perfectly the topological parameters can reflect the degree of stability in the rill network structure but it is not suitable for reflecting the dynamic changes of erosion intensity the geomorphologic comentropy was evaluated as the most appropriate characterization parameter for the rill morphology description

experimental evidence for a relationship between liquid immiscibility and ore formation in felsic magmas abstract geological studies demonstrate that liquid immiscibility in felsic magma closely associates with the ore forming process in order to obtain experimental evidence demonstrating the relationship between the ore forming process and liquid immiscibility in felsic magma we carried out a series of experiments at high temperature and atmospheric pressure the experimental results show that the granite kbf 4 na 2 moo 4 system is a homogeneous melt at high temperature with decrease in temperature however the melt decomposes into two immiscible melts silicate melt and ore forming melt the ore forming melt exists as globules in the silicate phase molybdenm ca na mg p mn f b and oh are concentrated in these globules the ore forming melt is characterized with very low sio 2 and al 2 o 3 concentrations but the concentration of moo 3 and cao is very high in contrast the silicate melts are significantly enriched in sio 2 and al 2 o 3 and depleted in moo 3 and cao in the silicate melt the concentrations of network modifying elements e g mo ca na p mg and volatiles f oh are very low the differences between the two immiscible melts exist not only in chemical composition but also in structure the ore forming melt structurally consists of moo 4 moof 4 b oh 4 and oh while the silicate melt is si0 4 because of the difference in composition and structure the two immiscible melts possess different physical properties compared to silicate melt the ore forming melt has a lower density and viscosity which permits the globules to behave as bubbles in granite magma and to move and concentrate in the upper part of magma chamber this process is probably responsible for the concentration of ore forming elements in the upper part of granite bodies and their immediate aureoles the present experimental results suggest that liquation in felsic magma can be the first step in the ore forming process during granitoid evolution

laboratory characterization and discrete element modeling of shrinkage and cracking in clay layer the performance of a variety of geostructures such as compacted clay liners earth dams and pavement embankments is compromised by soil cracking experiments are set up to monitor the drying pro

desiccation of a sensitive clay field experimental observations an excavation with three different levels was exposed to continuous evaporation during 35 days in order to observe and document the formation of shrinkage cracks in an intact and weathered sensitive marine clay desiccation of the intact saint alban clay under restrained conditions at an average evaporation rate of 0 018 cm h and an initial moisture content of 103 produced visible primary cracks after 17 h with an average spacing of 20 to 24 cm secondary cracks within each original polygon appeared after about 70 h of evaporation subhorizontal cracks at a depth of 6 to 8 cm were also created owing to differential strains induced by differential shrinkage of the soil polygons further evaporation resulted in the formation of a new set of vertical cracks after about 150 h of evaporation in the soil below the subhorizontal shear plane the shrinkage induced volume change associated with these different sets of cracks produced polygons with a protuberance at their bottom part indicating that the depth of crack propagation below the subhorizontal shear plane was about 3 to 4 cm in weathered clay at an initial moisture content of about 50 the average spacing was 10 to 12 cm indicating that spacing between primary cracks is related to soil type in the cohesionless topsoil no cracks were observed

syneresis cracks subaqueous shrinkage in argillaceous sediments caused by earthquake induced dewatering abstract syneresis cracks often confused with subaerial desiccation phenomena are traditionally ascribed to subaqueous shrinkage whereby salinity changes caused deflocculation of clay this and other previously proposed mechanisms fail to account for their occurrence in low energy typically non evaporitic facies stratigraphically sporadic distribution intrastratal formation under shallow burial depths variation in morphology degree of contraction generation of sedimentary dikelets as crack fills and deformation of dikelets and enclosing layers instead it is suggested that ground motion from strong synsedimentary earthquakes caused argillaceous sediments to dewater interbedded sands and silts to be almost simultaneously liquefied and injected into the resulting fissures and then these dikelets to be distorted comparative rarity of syneresis cracks in phanerozoic versus precambrian marine strata is considered to be primarily an evolutionary consequence of theological changes caused by increased organic binding of clay flocs in the water column greater input of organic matter into the sediment and the diversification of sediment dwelling bacteria and meiofauna in phanerozoic deposits

image analysis and fractal geometry to characterize soil desiccation cracks the rapid transport of water and solute through desiccation soil cracks can lead to crop water and nutrient stress as well as ground and surface water contamination the objectives of this research were to determine 1 soil surface crack area 2 fractal dimension of crack edges d1 and 3 mass fractal dimension d2 and lacunarity of soil surface cracks photographs were used to record in situ soil cracking in a mexico silt loam fine smectitic mesic vertic epiaqualf at two locations for three sampling dates photographs of the cracks were digitized and an algorithm was developed to determine crack area and the fractal dimension and lacunarity of the digitized images location 1 produced 7 crack area a mass fractal dimension d2 of 1 44 and a crack edge fractal dimension d1 of 1 08 location 2 produced 25 crack area a mass fractal dimension d2 of 1 64 and a crack edge fractal dimension of 1 08 d1 lacunarity curves as a function of box size for crack boundary fractal dimension were more variable at location 2 soil profile moisture content and texture analysis indicated the presence of an argillic horizon at the 20 cm depth at location 1 while at location 2 the argillic horizon was exposed to the soil surface photographic image analysis techniques and fractal analysis appear to distinguish differences in crack area and patterns which may be useful in characterizing soil cracking

mechanical behavior and fracture spatial propagation of coal injected with liquid nitrogen under triaxial stress applied for coalbed methane recovery abstract fracturing technology through liquid nitrogen ln2 injection alters the physical properties of coal and rock masses because of the thermal and pressure effects in order to investigate heat transfer and fracture propagation behaviors under in situ geological condition with ln2 injections experimental work was conducted to study the ln2 induced rock coal failures under true triaxial stress conditions during the experiments the temperature ultrasonic waves and acoustic emission location detection were monitored to determine the intensity and complexity of specimen failure under singular or cyclic ln2 injections the results show that a single ln2 injection mainly transfers heat through the solid skeleton and only damages areas adjacent to the injection tube however cyclic injections formed a propagated fracture network and the heat can sequentially transfer further along the induced fractures moreover plastic deformation occurred in the entire volume of the sample and the main fractures coalesced until the sample failed based on the spatial locations of the acoustic emission sources the dynamic fracturing within the sample progressed after ln2 injection was clarified the experimental results can provide evidences for the proposed crack propagation model for the coal masses the research revealed that high pressure nitrogen gas transferring liquid water to the tips of new fractures is essential for cyclic ln2 injection to form effective frost heaving forces and fracturing therefore the fracturing efficiency of the cyclic ln2 injection is far higher than that of singular ln2 injections

aluminum coordination in metaaluminous and peralkaline silicate melts incremental amounts of na2o and k2o added to immiscible melts in the mgo cao tio2 al2o3 sio2 system cause a decrease in critical temperature phase separation and change in the pattern of al2o3 partitioning al2o3 which is concentrated in the low sio2 immiscible melts in the alkali free system is increasingly partitioned into the high sio2 immiscible melt as the alkali aluminium ratio is increased however k2o is more effective than na2o in stabilizing al2o2 in the sio2 rich melt the coordination changes occurring in the aluminosilicate melts upon the addition of the alkali oxides are described by caal2o4 2siok 2kalo2 siocaosi where k or na displaces ca as the charge balancing cation for the networkforming alo4 tetrahedra the increased stability of the alo4 species in the highly polymerized sio2 rich melt and the consequent shrinkage of the miscibility gap is ascribed to positive configurational entropy and negative enthalpy changes associated with the formation of k na alo4 species element partition systematics indicate that na k alo2 species favor the more polymerized caal2o4 and tio2 species the less polymerized silicate structure in the melt

fractal analysis of temperature induced cracking in clays and rocks because of their low hydraulic conductivity clays have been used as a hydraulic barrier to the flow of rainwater into landfills similarly rocks have been used as depository sites for nuclear waste high temperatures resulting from climatic fluctuations for clays or from heat generated by nuclear waste for rocks can have detrimental effects on their hydro mechanical properties causing cracking in clays this is the result of desiccation in rocks it is the result of varying expansion between mineral grains the present study deals with the evolution and interconnectivity of cracks in clays and rocks as a result of high temperatures evaluated using the fractal dimension concept

resurfacing time of terrestrial surfaces by the formation and maturation of polygonal patterned ground 1 to help interpret the polygonal patterned ground on mars we present recent findings about a similar form of patterned ground in a particularly cold and arid region on earth the dry valleys of antarctica in this region distinct arrays of interconnected polygons which we refer to herein simply as patterned ground characterize many surfaces reflecting a subsurface network of interconnected subvertical wedges of sand that grow incrementally as sand progressively fills soil fractures the fractures form initially as thermoelastic stresses arise during periods of rapid cooling of frozen ground and they continue to open and close in response to thermal cycles we describe the initiation and maturation of the patterned ground using data for the growth of sand wedges and for the evolution of crack patterns and microrelief over time scales ranging up to 106 years

cracking and vertical preferential flow through landfill clay liners abstract cracking is a major concern in the long term performance of landfill clay liners cracking of clay liners is affected by the roots of the vegetation planted to control erosion while vegetation roots may restrict cracking they may introduce preferential flow through the liners the impact of vegetation roots on the hydraulic properties of clay liners remains unclear this study investigates the effect of vegetation roots on crack formation and preferential flow through clay liners three experimental soil columns were used to observe crack formation by exposure to the weather and to measure the flow through them caused by artificial rainfall the clay in each column was compacted to 90 relative compaction the first column was not vegetated and no crack developed in it the second column was vegetated and underwent drying wetting cycles outdoor the third column did not have vegetation but underwent drying wetting cycles outdoor cracks developed in the second and third columns due to the exposure to the weather image analysis in the experimental soil columns revealed that vegetation roots restricted crack formation especially in the early stages of drying wetting cycles infiltration tests performed on the experimental soil columns showed that the unsaturated hydraulic conductivity of the vegetated soil in the second column was respectively about two orders and one order of magnitude larger than those of the soils in the first and third columns the experimental results imply that the effect of vegetation roots on the preferential flow through landfill clay liners should be considered in practical designs

flux of volatiles and ore forming metals from the magmatic hydrothermal system of satsuma iwojima volcano the satsuma iwojima volcano southwest japan degasses 5 x 10 6 t yr h 2 o 9 x 10 4 t yr s and 6 x 10 4 t yr cl from high temperature 880 c fumaroles atop a now altered rhyolite dome that erupted 1200 yr ago acidic hot springs ph 1 1 1 8 discharge 20 x 10 6 t yr h 2 o to the sea this water is composed of 1 part magmatic vapor absorbed by 6 parts meteoric ground water the cl and so 4 in solution originate from the vapor whereas cation components are derived largely by dissolution of the rhyolite the flux of pb zn cu and mo in the vapor and acidic springs ranges from 0 1 to 10 t yr each whereas the au flux is 10 5 and 10 3 t yr respectively the low concentrations of nacl and metals in the vapor are due to the condensation of a hypersaline liquid from the vapor during ascent and depressurization meaning that the atmospheric pressure vapor does not reflect the composition of the fluid exsolving from the magma neither this low pressure vapor nor the acidic waters can account for high sulfidation cu au ore deposits deduced to have formed in this environment such mineralization requires the subsequent ascent of a metal rich fluid

separation and fracturing in overlying strata disturbed by longwall mining in a mineral deposit seam abstract mining induced fractures influence the stability of overburden and may provide pathways for transferring heat and mass in underground environment a novel approach was proposed to quantify the separation and fracture evolution in the undermined overburden consisting of 1 theoretical distribution models of the void ratios of fractures vrfs based on analytical evaluation of key strata subsidence and 2 numerical modeling using the universal distinct element code and a sequence of image post processing procedures for a longwall mining panel both theoretical calculations and numerical simulations indicated that vrf first increased rapidly then gradually decreased and finally stabilized to a minimum from the surrounding edges of disturbed strata to their centers and gradually decreased from deep to shallow strata the fractures exhibited a fracture rich arch distribution type along a vertical section numerous fractures occurred around the arch feet near the perimeters of mined out area and or arch crown near the center of disturbed strata the distributions of vrfs show the heights shapes and damage intensities of fractured zones and can also be used as porosity parameters to determine the permeabilities of mining disturbed overburdens therefore the vrf models can be used as a quantitative parameter to assess the extent of possible risk zones e g for water inflow into the mine or escape of hazardous fluids to the surface

mapping mine wastes and analyzing areas affected by selenium rich water runoff in southeast idaho using aviris imagery and digital elevation data abstract remotely sensed hyperspectral and digital elevation data from southeastern idaho are combined in a new method to assess mine waste contamination waste rock from phosphorite mining in the area contains selenium cadmium vanadium and other metals toxic concentrations of selenium have been found in plants and soils near some mine waste dumps eighteen mine waste dumps and five vegetation cover types in the southeast idaho phosphate district were mapped by using airborne visible infrared imaging spectrometer aviris imagery and field data the interaction of surface water runoff with mine waste was assessed by registering the aviris results to digital elevation data enabling determinations of 1 mine dump morphologies 2 catchment watershed areas above each mine dump 3 flow directions from the dumps 4 stream gradients and 5 the extent of downstream wetlands available for selenium absorption watersheds with the most severe selenium contamination such as the south maybe canyon watershed are associated with mine dumps that have large catchment watershed areas high stream gradients a paucity of downstream wetlands and dump forms that tend to obstruct stream flow watersheds associated with low concentrations of dissolved selenium such as angus creek have mine dumps with small catchment watershed areas low stream gradients abundant wetlands vegetation and less obstructing dump morphologies

evidence for a copper bearing fluid in magma erupted at the valley of ten thousand smokes alaska several lines of evidence point to the existence of a pre eruptive fluid phase in the magmas erupted in 1912 at the valley of ten thousand smokes alaska the discovery of rare cu rich bubbles in some melt inclusions is best explained by the random entrapment of a low density fluid phase within growing phenocrysts the h2o s and cl concentrations of the high silica rhyolite are also consistent with fluid saturation in the rhyolite water contents as determined by infrared spectroscopy on doubly polished melt inclusions cluster between 3 5 and 4 5 wt h2o without any apparent differences between magmas vented explosively and effusively these concentrations would be sufficient for h2o saturation at a pressure of 100 mpa though the presence of other volatiles such as co2 and so2 could allow saturation with respect to a fluid phase at higher pressures the s cu and cl contents of the phenocryst assemblages as determined by xrf analyses are too low to account for the decrease in the concentrations of s and cu in the melt and only modest increase in cl with differentiation therefore the behavior of these volatile elements was controlled either by eryptic fractionation if phenocryst phasese or more likely by partitioning into a coexisting fluid phase the presence of this low density phase apparently provided metals such as cu with a volatile phase into which they could partition the concentration of cu in this fluid reached tens to hundreds of times that of the coexisting silicate melt and may have been as rich as 0 05 wt cu the distribution of cu in the magma was also controlled by sulfides such as intermediate solid solution and pyrrhotite which cyrstallized directly from the silicate melt

pyrite mine waste and water mapping using hymap and hyperion hyperspectral data hyperspectral low spatial resolution hyperion data are used to map mine waste from massive sulphide ore deposits mostly abandoned on the iberian pyrite belt hymap high spatial resolution data are used for crossed interpretation mine dams mill tailings and mine dumps in a variable state of pyrite oxidation are recognizable ponds of acid water in the mine sites are spectrally outstanding and with simple image processing procedures mappable in addition acid water with different chemical composition is mappable with hyperspectral data whether of high or low spatial resolution a sequence of hyperspectral image processing algorithms used to produce the maps is suggested therefore hyperspectral data are invaluable in giving quick hints on the quality of the rapidly changing state of the contamination generated by sulphide mine waste enabling the authorities to activate mitigation procedures

hyperspectral remote sensing monitoring of pyrite mine wastes a record of climate variability pyrite belt spain monitoring of mine waste on sulphide deposits through hyperspectral remote sensing data contributes to predicting surface water quality quantitatively estimating acid drainage and metal contamination on a yearly basis the mineralogy of surface crusts loaded with highly soluble salts is a record of available humidity and temperature along the year a temporal monitoring of salt efflorescence on mine wastes at a mine site in the iberian pyrite belt spain has been mapped in this work using hyperspectral airborne hymap data climate change estimations are made based on oxidation stages derived from well known sequences of minerals tracing sulphides oxidation intensity using archive spectral libraries therefore mine waste weathering products of sulphide mapped from airborne hyperspectral remote sensing data can be used as a short term record of climate change providing a useful tool for assessing environmental geoindicators in semi arid areas

mineralogical and geochemical investigation of clay rich mine tailings from a closed phosphate mine bartow florida usa clay rich mine tailings from phosphate mine operations in florida are a major environmental and economic problem options for reclamation and restoration for these tailings are very limited and are fundamentally restricted by poor physical properties such as low mechanical strength low hydraulic conductivity and heavy metal content the major control on these bulk physical properties is the mineralogy of the materials eight continuous push borings were obtained to investigate stratigraphy mineralogy aspects of geochemistry and bulk properties of a deposit of clay rich mine tailings from a phosphate mine near bartow florida that ceased operations in the early 1970s stratigraphy is dominated by laminated clay rich sediment with minor units of silt and sand an intact kaolinite liner occurs near the impoundment walls and the impoundment floor has approximately 4 m of relief moisture content varies from 4 35 to 57 40 wt and organic content varies from 0 41 to 9 53 wt bulk xrf investigation indicates that the p2o5 concentrations vary from approximately 4 to 21 wt a very strong correlation r2 0 92 between cao and p2o5 indicates that apatite is a major control on the phosphate the strong correlation r2 0 77 of al2o3 and tio2 suggests that the source materials for this deposit are comparatively uniform a number of heavy metal elements and trace elements occur cr v ni cu are interpreted to be in phosphate minerals largely apatite sr and pb are interpreted to be in both phyllosilicates and phosphate minerals two populations of apatite were observed in the clay sized fraction one that was fe and si bearing and another that was only si bearing fe bearing apatite had fe2o3 contents that varied from 0 38 to 5 32 wt and sio2 contents that varied from 0 90 to 3 32 wt the other apatite population had a wider range of sio2 contents that varied from 0 77 to 8 80 wt tem imaging shows that apatite grains are dominantly single crystals with lesser amounts of aggregates wavellite commonly occurs as individual or clusters of lath like crystals and the chemical composition differs from the pure aluminium phosphate end member with average concentrations of components being that of cao 1 57 wt fe2o3 1 98 wt sio2 5 94 wt in the clay sized phosphate minerals investigated no fluorine was found above detection limit approximately 0 15 wt nor was any uranium radium heavy metal or ree element detected the phyllosilicate mineralogy of the deposit is dominated by smectite montmorillonite with lesser amounts of nontronite palygorskite illite and kaolinite no systematic variation in the relative proportions of phyllosilicates was observed in the clay deposit energy dispersive spectroscopy eds analysis indicates that chemical compositions of phyllosilicates are somewhat typical but overall are enriched with respect to fe compared to theoretical end members the relative enrichment of fe is interpreted to be a primary sedimentary feature ca content in smectite minerals is high and may inhibit stabilization using lime or similar methods the high percentages of montmorillonite and palygorskite explain the high bulk water contents observed this investigation provides fundamentally new details regarding clay tailing deposits from closed phosphate mines in central florida which can be used in restoration and reclamation efforts

structure and porosity of smectitic mudrocks as affected by experimental wetting drying cycles and freezing thawing cycles abstract the erosion rates in the vallcebre basin pyrenees are controlled predominantly by the physical weathering rate of bare regolith i e mudrocks to obtain information on the influence of thermic and moisture regimes on the weathering dynamics laboratory experiments were carried out to investigate how freezing thawing or wetting drying cycles under controlled conditions affect structure and porosity three different clayey mudrocks were selected to represent materials more susceptible to erosion in the studied area the three lithologies identified as ca1r ca2r carr differed mainly in mineral constituents type and quantity of the clay minerals and cation exchange capacity an automated non contact laser profile meter was used to analyse surface microtopography in order to monitor random roughness variations and to calculate bulk density porosity and pore size distribution were carried out with image analysis freezing thawing cycles were the most active in modifying soil surface and bulk structure roughness of ca1r and ca2r was more than doubled at the end of freezing thawing cycles this variation was mostly associated with the whole surface elevation related to the bulk volume increase roughness variations in carr were less pronounced and related to a modification of the microtopography micromorphological observations revealed a platy structure formation induced by repeated ice lensing also porosity was increased by freezing thawing cycles with the formation of a large number of irregular and rounded pores wetting drying cycles did not affect surface roughness and modified bulk density very little in all samples they increased porosity by the formation of large cracks and fissures overall data from wetting drying cycles showed that changes in water content alone did not produce deep structural modifications a mechanism of alteration of soil structure during freezing thawing cycles is proposed

cracks bifurcation and shear bands propagation in saturated clays discontinuities in the form of cracks or fissures and inclusions are often present in natural clays they serve as stress concentrators when loads are applied to the material such concentrations result in cracks advancing often surrounded by and preceded by a propagating damage zone as cracks propagate the damage may be in the form of one or more shear bands which may play the part of new stress concentrators and blunt the action of the original crack this paper examines some of the phenomena associated with cracks in over consolidated clays and normally consolidated clays differences between isotropic and anisotropic materials and the level at which serious modifications take place in the fabric of the material are noted the influence of the cracks and the shear bands on the kinematics and strength of the test specimens is discussed des discontinuites sont souvent presentes sous forme de fractures fissures et inclusions dans les argiles naturelles elles jouent le role de concentrateurs de c

fractal analysis of cracking in a clayey soil under freeze thaw cycles abstract under extreme climate conditions clayey soils experience not only seasonal drying and wetting but also frequent freezing and thawing cracking would also occur in clayey soils under freeze thaw cycles but now less academic attention has been paid on this issue in this study a series of laboratory tests were conducted on a clayey soil to investigate the cracking behaviors under freeze thaw cycles water loss surface crack initiation and propagation processes were monitored after each freeze thaw cycle by using the image processing technique the crack patterns were described and then quantitatively analyzed on the basis of the fractal dimension concept it was found that for the tested clayey soil subjected to freeze thaw cycles the surface crack pattern slowly evolves from an irregularly rectilinear pattern towards a polygonal or quasi hexagonal one and the water loss closely related to the sample thickness plays a significant role in the process of the clay cracking upon cyclic freezing thawing the fractal dimension is well correlated to the surface crack ratio in a logarithmic equation fractal dimension concept can offer a new perspective on the quantitative understanding of cracking initiation and propagation in clayey soils under freeze thaw cycles