continuous saltating process of multiple sediment particles the purpose of this study is to investigate the interacting mechanism between the saltating particles near the channel bed a real time flow visualization technique was developed to measure the interparticle collision behaviors during the saltating process a two dimensional continuous saltation model was also developed this model was calibrated and verified with the experimental data collected with satisfactory results the model is able to simulate the continuous saltating trajectories of several particles the simulated maximum saltation height is about 2 2 5 times the values calculated by a single particle saltation model due to the effects of particle collision the simulated saltation velocities of the multiple particles model are less than those derived from a single particle model regression equations for the saltating height and velocity were obtained

experiments on saltation of sand in water a high speed video system was used to study saltation of sand in an open channel flow high rates of image acquisition provided the information needed to resolve details of the lagrangian properties of particle motion saltation of sand is described in terms of statistical properties of particle trajectories such as mean values and standard deviations of saltation length height and streamwise particle velocity results are compared with available empirical data saltation height seems to be independent of particle size when made dimensionless with the particle diameter however the dimensionless saltation length appears to increase as the particle size decreases particle collision with the bed is also analyzed observations of this process indicate that most of the interactions between saltating particles and the bed are of the collision rebound type which contradicts previous discussions on the subject the estimated value of the dynamic friction coefficient is about half that proposed by bagnold i

investigations of continuous bed load saltating process particle saltating motions during bed load transport are dominated by the forces acting upon particles and the random process of the particles impacting on and rebounding from the channel bed a real time flow visualization technique is developed in this study to measure particle saltating trajectories corresponding velocities and impacting and rebounding angles based on the experimental data regression equations for the dimensionless saltating length height and velocity were obtained a numerical model that is able to simulate the continuous saltating process of a single particle was developed the model was calibrated and verified with the experimental data and the results were satisfactory the model was also used to generate a series of synthetic data based on these data and the flume data collected by previous investigators a bed load equation was derived

effects of lifting force on bed topography and bed surface sediment size in channel bend in bed load sediment transport the lifting force plays an important role in reducing the friction between sediment particles and the bed surface and it makes particle transportation by the shear force easier because the lifting force is related to vorticity a three dimensional 3d numerical model incorporating large eddy simulations was applied to simulate the vorticity field in a channel bend the results show that the distribution of vorticity is highly nonuniform and it can lead to significant variations in lifting force and bed load sediment transport per unit width in a channel bend relevant theories are modified on the basis of physical reasoning and then incorporated into numerical models to investigate the lifting force effects on the bed topography and bed surface sediment size gradation in a channel bend with the lifting force effects considered it is shown that the errors in simulated bed topography can be reduced by approximately 40 and in bed surface sediment size by 50

determination of amphibole fracture strength for quantitative palaeostress analysis using microboudinage structures abstract the fracture strength of amphibole is estimated with the aim of extending the applicability of the microboudin method to palaeostress analysis before estimating the fracture strength of amphibole it is necessary to evaluate the influence of the size effect on fracturing among the three models of size effect effective length effective area and effective volume the effective length model is found to be the most suitable in our microboudinage analysis of a metachert from turkey that contains numerous microboudinaged amphibole grains of variable width embedded within a quartz matrix taking into account the influence of the size effect on fracturing we undertook a comparative microboudinage analysis of the metachert sample which also contains coexisting microboudinage structures of tourmaline and epidote the analysis revealed an instantaneous fracture strength for amphibole of 80 mpa for a 1 mm cube the far field differential stress 0 calculated based on amphibole microboudinage structures and considering the effect of the fatigue limit is 0 8 1 w 1 2 where is the dimensionless stress parameter determined by microboudinage analysis and w is the mean width of amphibole grains

saltation in water dynamics an evaluation of the fluid forces exerted on a bed load particle is presented the study used strobe photography to measure the kinematics of a sphere moving via saltation along the bed of an open channel flow the experiment showed that the forces of bouyancy added mass and drag could predict the particle motion the added mass force included an unusual component due to the mean shear of the open channel flow

further studies on the use of quartz grains from fault gouges to establish the age of faulting abstract quartz grains were selected from samples of intrafauit material at two outcrop sites of the atotsugawa fault in central japan surface textures of the grains observed by scanning electron microscope were classified into texture groups i iv in the order from a simple feature through increasing undulations to a texture with cavities the defects in the quartz measured by electron spin resonance gave absolute ages using the grains the relative ages by surface texture groups were tentatively correlated to the absolute ages as determined by the electron spin resonance it was disclosed that subgroups ia and ib were stable during the period of 0 9 ma and changed through intermediate subgroup ic in a period ranging from 0 9 to 1 2 ma and then to group ii after 1 2 ma therefore the surface texture groups can change from subgroups ia and ib through intermediate subgroup ic to group ii with increasing age this indicates that the surface texture groups of quartz grains in the fault are effective for dating fault activity concisely

revisiting the linear theory of sand dune formation a linear stability theory for dune and antidune formation is presented that implements a rotational two dimensional flow model as in previous linear theories the phase lag between sediment transport and bed elevation remains the main mechanism driving instability however it is shown that this phase lag varies significantly in a neighbourhood of the bed moreover since the layer in which sediments are moving has a finite though small thickness it is assumed that the perturbations of the fluid stress driving bedload transport should be evaluated at the top of the layer itself it is shown that such an apparently minor modification of the classical approach alters remarkably the balance between stabilizing and destabilizing effects that drives the instability process this also allows a clarification of the debated role of bedslope on the formation of dunes and antidunes following the above ideas antidunes are shown to form in the absence of suspended sediment load and without any effect associated with sediment inertia the present analysis ultimately allows a successful unification of the theories of dune and antidune formation

direct determination of europium valence state by xanes in extraterrestrial merrillite implications for ree crystal chemistry and martian magmatism the relative proportion of divalent and trivalent eu has proven to be a useful tool for estimating f sub o sub 2 in various magmatic systems however in most cases direct determination of the eu valence state has not been made in this study direct determination of eu valence by xanes and ree abundance in merrillite provide insights into the crystal chemistry of these phosphates and their ability to record conditions of magmatism merrillite strongly prefers eu sup 3 to eu sup 2 with the average valence state of eu ranging between 2 9 and 3 over approximately six orders of magnitude in f sub o sub 2 the dramatic shift in the ree patterns of merrillite in martian basaltic magmas from highly lree depleted to lree enriched parallels many other trace element and isotopic variations and reflects the sources for these magmas the behavior of ree in the merrillite directly reflects the relationship between the eightfold coordinated ca1 site and adjacent sixfold na and tetrahedral p sites that enables charge balancing through coupled substitutions

crystal chemistry of lunar merrillite and comparison to other meteoritic and planetary suites of whitlockite and merrillite merrillite also known as whitlockite is one of the main phosphate minerals along with apatite that occur in lunar rocks martian meteorites and in many other groups of meteorites signi cant structural differences between terrestrial whitlockite and lunar and meteoritic varieties warrant the use of merrillite for the h free extraterrestrial material and the systematic enrichment of ree in lunar merrillite warrants the use of re merrillite laser raman spectroscopy of extraterrestrial merrillite and terrestrial whitlockite con rms the absence of h in the former and presence of h in the latter lunar merrillite ideally mg fe 2 mn 2 2 ca18 x y ree x na2 x p si 14o56 contains high concentrations of y ree reaching just over 3 atoms per 56 o atoms or up to 18 wt as y re 2o3 in the absence of extensive si p substitution the availability of the na site limits y ree substitution to 2 atoms per 56 o atoms higher concentrations of y ree with coupled substitution of si for p to balance charge are possible but rare in lunar material intrinsically low na concentrations in lunar rocks combined with the typical formation of merrillite in late stage basaltic mesostasis or residual intercumulus melt pockets produce these high ree concentrations lunar merrillite typically contains 0 1 0 4 na atoms per 56 o atoms for comparison martian merrillite contains signi cantly higher na concentrations up to 1 7 na atoms per 56 o atoms and much lower ree concentrations meteoritic merrillite has relatively low ree contents but exists in both ca rich and na rich varieties concentrations of fe and mg in all varieties sum to near 2 atoms per 56 o atoms merrillite in lunar crustal lithologies typically has mg fe however fe rich mare basalts contain up to 1 8 fe 2

petrogenetic linkages among martian basalts implications based on trace element chemistry of olivine the shergottites exhibit a range of major and trace element compositions crystallization ages and initial sr nd hf and pb isotopic compositions to constrain the physical mechanisms by which shergottites obtain their compositional characteristics we examined the major and trace element record preserved in olivine in the more primitive shergottites based on such characteristics as the mg v zoning calculated dni co the olivine in y 980459 are most likely phenocrysts many of these same characteristics indicate that the olivines in other shergottites are not in equilibrium with the adjacent melt however in most cases they are not xenocrystic but additions of olivine from the same basaltic system elephant moraine eet a79001 may be an exception with the olivine data suggesting that it is xenocrystic in this case the olivine crystallized from a reduced and lreedepleted melt and was incorporated into an oxidized and enriched basalt vanadium and cao in olivine appear to record the appearance of spinel and pyroxene on the liquidus of most of the shergottites most of the olivine shergottites represent basalts produced by melting of reduced iw to iw 1 depleted mantle sources olivine data indicate that many of the primary melts derived from this source had similar ni co and mn shergottites such as northwest africa nwa 1110 1068 and perhaps roberts massif rbt 04261 that appear to be derived from more enriched sources have distinctly different olivine in the case of nwa 1110 1068 the olivine data suggests that the enriched component was added to system prior to olivine crystallization

space time distribution patterns of destructive earthquakes in the inner belt of central japan activity intervals and locations of earthquakes abstract based on a block structure model of the inner belt of central japan an examination was conducted of the space time distribution patterns of destructiv magnitudes m 6 4 or greater m japan meteorological agency scale the distribution patterns revealed a periodicity in earthquake activit seismic gaps major nw se trending left lateral active faults divide the inner belt of central japan into four blocks 20 80 km wide the occurrenc a d with m 6 4 which have caused significant damage were documented in the inner belt of central japan the epicenters of these earthquakes close to the block boundaries using the relationship between the magnitude of earthquakes which occurred in the japanese islands and the active length of faults that generated them movement is calculated for each historical earthquake space time distributions of earthquakes were obtained from the calculated lengths the latitud of generation when an active period begins a portion or segment of the block boundary creates an earthquake which in turn appears on the ground surf active period ends when the block boundary generates earthquakes over the entire length of the block boundary without overlapping five seismic gaps with fault lengths of 20 km or longer can be found in the inner belt of central japan it is predicted that the gaps will generate ea magnitudes of 7 0 these data are of significance for estimating a regional earthquake risk over central japan in the design of large earthquake resist the time sequences of earthquakes on the block boundaries reveal a similar tendency with alternating active periods with seismic activity and quiet pe activity the inner belt of central japan is now in the last stage of an active period the next active period is predicted to occur around 2500 a d

a review of meteorite evidence for the timing of magmatism and of surface or near surface liquid water on mars 1 there is widespread photogeological evidence for ubiquitous water flowing on the surface of mars however the age of surface and near surface water cannot be deduced with high precision from photogeology while there is clear evidence for old and young fluvial features in the photogeologic record the uncertainty in the absolute calibration of the martian crater flux results in uncertainties of 1 5 gyr in the middle period of martian geologic history aqueous alteration of primary igneous minerals produces secondary minerals in martian meteorites here we use the ages of secondary alteration minerals in martian meteorites to obtain absolute ages when liquid water was at or near the surface of mars aqueous alteration events in martian meteorites occurred at 3929 37 ma carbonates in alh84001 633 23 ma iddingsite in nakhlites and 0 170 ma salts in shergottites furthermore these events appear to be of short duration suggesting episodic rather than continuous aqueous alteration of the meteorites the martian meteorites appear to be contaminated by martian surface pb characterized by a 207pb 206pb ratio near 1 lead of this composition could be produced by water based alteration on the martian surface the high 129xe 132xe ratio in the martian atmosphere compared to martian meteorites indicates fractionation of i from xe within 100 myr after nucleosynthesis of 129i such fractionation is difficult to achieve through magmatic processes however water very efficiently fractionates i from xe raising the intriguing possibility that mars had a liquid water ocean within its first 100 myr 1

amorphous material formed by the mechanochemical effect in natural pseudotachylyte of crushing origin a case study of the iida matsukawa fault nagano prefecture central japan abstract pseudotachylytes from the iida matsukawa fault central japan iida pseudotachylytes are described down to the nanometer scale using high resolution electron microscopy scanning electron microscopy analyses of chemical compositions and mercury intrusion porosimetry the pseudotachylyte matrix chiefly consists of nanoscale particles and elongated submicron fragments with biotite composition amorphous material of several tens of nanometers in size is also observed despite the absence of melt textures lattice fringe images reveal that the amorphous phase coexists with lattice distortion in deformed biotite fragments that are several hundreds of nanometers in size the presence of these submicrostructures indicates that the amorphous material formed by mechanical stress during the comminution process that is via the mechanochemical effect we conclude that amorphous material does not always provide evidence of the rapid cooling of melt in pseudotachylyte the amorphous materials present in the iida pseudotachylyte resulted from the mechanochemical effect due to both shear stress and normal stress during the comminution process that accompanied fault motion

gravel saltation 2 modeling a lagrangian model for the motion of a sediment particle in a water flow is proposed the particle motion equation is averaged over flow turbulence specialized to the case of coarse sediment particles saltating in water and coupled with a stochastic model for particle collision with the bed model predictions of statistics of gravel saltation generally agree well with experimental observations as an application of the saltation model bed load transport rates are estimated from modeled mean saltation streamwise velocity and a dynamic friction coefficient the results obtained compare favorably with typical bed load equations but they overestimate experimental measurements of gravel transport which would suggest that a bagnoldean formulation for bed load transport of coarse material by saltating particles may not be valid

microscopic features of quartz and clay particles from fault gouges and infilled fractures in granite discriminating between active and inactive faulting abstract to assist in identifying faults that have a significant potential for displacement at or near the ground surface we carried out in depth investigations on fault gouges and a fracture infilled with clay clay vein in the kojaku granite on the tsuruga peninsula central japan we sampled several fault gouges at different stages of evolutions and clay rich infilling of a fracture with no evidence of offset based on our field observations gouge in an active fault is characterized by 1 stacked layers of different colors made up of comminuted fragments and clays and 2 injection of the fragments and clays from the gouge into the surrounding rocks indicating an accumulation of seismic induced shearing our thin section observations and x ray diffraction analyses show that all our samples are similar in the degree of fragmentation and mineral composition and because of this our study became focused mainly on microscopic features using laser diffraction particle size analysis scanning electron microscopy sem and transmission electron microscopy tem we identified the mineralogical and textural characteristics of the samples in order to improve our ability to discriminate between active and inactive faulting particle size distribution analysis showed that the gouge in the active fault contains the greatest abundance of finer particles due to multiple slip events which contrasts with the clay rich infilling of a fracture sem examination of the quartz particles showed that the gouge in the active fault contains more particles that have retained sharp and smooth crystal surfaces formed by fracturing than do either the gouges in minor faults that show no evidence of recent shear or the clay rich infilling of a fracture in contrast tem observations of very fine clay minerals approximately

roundness of clasts in pseudotachylytes and cataclastic rocks as an indicator of frictional melting abstract we examine the roundness rd of clasts derived from fault rocks and discuss its possible application as an indicator for fracturing and chipping or frictional melting the roundness of quartz and feldspathic clasts derived from four frictional melting originated pseudotachylytes and one crushing without melting originated pseudotachylyte as well as three cataclastic rocks was measured between 230 and 270 clasts 10 m in size were measured for each sample the analyses show that rd is lower than 0 4 in all the clasts included in the cataclastic rocks and crushing originated pseudotachylyte whereas it varies from 0 1 to 1 0 and 35 90 of clasts have a roundness 0 4 in the melting originated pseudotachylyte it is suggested that the clasts having a roundness 0 4 were rounded by frictional melting rather than by fracturing or chipping in pseudotachylytes and that the roundness of clasts may be used as a special index of disintegration attributed to attrition and melting

surface textures of intrafault quartz grains as an indicator of fault movement summary quartz grains obtained from gouges which accompany faults are observed by means of a scanning electron microscope it is assumed that quartz grains in the gouge are formed from the breakage of quartz in the parent rock due to fault movement with corrosion by groundwater occurring on grain surfaces after the movement therefore surface textures or morphology of the grains can become a good indicator in examining the mode of fracture at the time of faulting or the length of time elapsed since the fault moved

stochastic modeling of the cover effect and bedrock erosion 1 several important fluvial bedrock erosion processes are driven by the impact of bed load particles bed load transport rates fluctuate strongly in both nature and experiment and stochastic models of the transport processes have been put forward to describe this behavior in this paper i adapt a model based on a markov chain formulation to derive probability distributions for bed load transport rate over a rock bed only partly covered by sediment i propose a way to calculate the probability distribution of bed cover for given sediment supply using a combinatoric model and combine the two curves to calculate probability distributions for bed cover and erosion rate at constant hydraulics in the proposed model mean bed cover is an exponentially declining function of the number of particles in the control volume the model describes recently published experimental data well but at the moment it is not possible to finally discriminate between the exponential and the previously proposed linear model formulation distributions of erosion rate are fairly broad functions slightly skewed toward high erosion rates

model for calculating bed load transport of sediment a bed load transport model based on the mechanics of sediment moving by saltation yields predicted values of bed load flux as a function of boundary shear stress grain diameter and density the parameters required to calculate bed load transport particle velocity bed load sediment concentration and the height of the bed load layer can all be determined from our model which computes sequences of trajectories of individual saltating grains as well as the concentration of moving grains that the flow can support the latter is related to the momentum the accelerating grains extract from the flow predicted curves of bed load transport vs boundary shear stress agree well with transport data collected by gilbert meyer peter iet al n and the waterways experimental station measured shear stress was corrected for pressure drag when bed forms were present comparison of predicted bed load transport with common bed load equations reveals considerable similarity among the relationships the best agreement with the data is produced by relationships in which the transport rate vanishes as the shear stress approaches the critical shields number as in our model and yalin s equation

a simple method to classify diamicts by scanning electron microscope from surface microtextures interpretation of quartz sand grain surface microtextures with scanning electron microscopy has been riddled with inconsistencies invalid assumptions and much subjectivity therefore a novel classification for analysing grain surface microtextures is presented based on the origin of complete grain surfaces this novel method has solved most of the earlier problems of interpretation of surface microtextures and it is easy to use and to quickly find evident genetic interpretations of diamicts the data are plotted graphically in 2 history diagrams or 3 history diagrams for quick visual inspection and statistical evaluation source rocks and quaternary glacial deposits from scandinavia and southern ontario representing different ice substrate dynamics are analysed to define surface microtextures from typical glacigenic grains bedrock and fluvially transported grains typical glacially crushed grains display large scale fractures and abrasion shield bedrock grains display large or small scale fractures and solution precipitation microtextures fluvially transported grains exhibit abrasion and solution precipitation microtextures

sediment transport part i bed load transport a method is presented which enables the computation of the bed load transport as the product of the saltation height the particle velocity and the bed load concentration the equations of motions for a solitary particle are solved numerically to determine the saltation height and particle velocity experiments with gravel particles transported as bed load are selected to calibrate the mathematical model using the lift coefficient as a free parameter the model is used to compute the saltation heights and lengths for a range of flow conditions the computational results are used to determine simple relationships for the saltation characteristics measured transport rates of the bed load are used to compute the sediment concentration in the bed load layer a simple expression specifying the bed load concentration as a function of the flow and sediment conditions is proposed a verification analysis using about 600 alternative data shows that about 77 of the predicted bed load transport rates are within 0 5 and 2 times the observed values

a sem cathodoluminescence study on weathering of quartz grains in faults central japan summary cathodoluminescence cl of quartz grains or particles was observed using a scanning electron microscope the quartz grains were collected from fault gouge and fault breccia within the atotsugawa fault central japan and the quartz particles were obtained by crushing parent rocks of the fault such as granite and gneiss in an iron bowl in comparison with particles from the parent rocks those from the fault showed the following differences cl inherited from the parent rock cl caused by faulting and cl modified by weathering or alterations of the fault these differences are attributed to the faulting and subsequent weathering the cl observations were in general agreement with secondary electron observations and it is recommended that both methods should be used in parallel

transition between two bed load transport regimes saltation and sheet flow in the saltation regime where bed shear stress is low bed load moves by sliding rolling and saltating along the bed while in the sheet flow regime where bed shear stress is high it travels by a combination of saltation and sheet flow in this paper a theoretical model is developed for predicting the onset of the sheet flow regime as shear stress increases this model is based on a new variable pb representing the proportion of grains on the bed that are entrained as bed load the model yields the equation pb 2 56g 3 in which g 1 c dimensionless bed shear stress and c critical value of at which grains begin to move the equation shows that t which is the value of at the onset of the sheet flow regime and is assumed to occur when pb 1 is around 0 5 with the exact value controlled by c for example when c 0 045 t 0 52 the theoretical model is verified by performing a nonlinear regression analysis on data from 285 flume experiments additional flume experiments with a high speed video hsv system result in consistent values of for the onset of the sheet flow regime which support the theoretical model the hsv images further reveal that 1 the sheet flow regime is characterized by granular sheets or laminations and 2 a zone of mixed saltation and rolling grains exists not only in the saltation regime but also in the sheet flow regime

fracturing mode analysis and relative age dating of faults by surface textures of quartz grains from fault gouges abstract surface textures of quartz grains taken from about 250 samples of fault gouges in faults ranging in length from several metres to several tens of metres with the faults extending several tens to several hundreds of kilometres in length are examined by means of the scanning electron microscope and are categorized into four groups from i to iv based on the smoothness of the surface degree of undulation and development of cavities as mentioned in a previous paper based on surface features of quartz grains from faults the geological age of movement of which is known the groups i to iv are tentatively related to the age of formation of quartz grains and the period of formation of surface textures this correlation makes it clear that quartz grain surface textures are an important clue to dating a relative age of faulting river patterns striations granular fracture surfaces and dimple like textures are observed to appear on less corroded surfaces of quartz grains from fault gouges fractographic analysis of these surfaces of quartz grains should be a clue to revealing the mode of fracture of the fault movement which released the quartz grains into the fault gouge

partitioning of eu between augite and a highly spiked martian basalt composition as a function of oxygen fugacity iw 1 to qfm determination of eu2 eu3 ratios by xanes we have determined d sub eu between augite and melt in samples that crystallized from a highly spiked martian basalt composition at four f sub o sub 2 conditions d sub eu augite melt shows a steady increase with f sub o sub 2 from 0 086 at iw 1 to 0 274 at iw 3 5 this increase is because eu sup 3 is more compatible than eu sup 2 in the pyroxene structure thus increasing f sub o sub 2 leads to greater eu sup 3 eu sup 2 in the melt and more eu total can partition into the crystallizing pyroxene this interpretation is supported by direct determinations of eu valence state by xanes which show a steady increase of eu sup 3 eu sup 2 with increasing f sub o sub 2 in both pyroxene 0 38 to 14 6 and glass 0 20 to 12 6 in the samples also pyroxene eu sup 3 eu sup 2 is higher than that of adjacent glass in all the samples which verifies that eu sup 3 is more compatible than eu sup 2 in the pyroxene structure combining partitioning data with xanes data allows for the calculation of specific valence state d values for augite melt where d sub eu sup 3 0 28 and d sub eu sup 2 0 07

microfractures within the fault damage zone record the history of fault activity 1 for faults without sedimentary covers there is no robust method to obtain paleoseismic data that is crucial for the prediction of future damaging earthquake events sudden failure along faults during earthquakes induces off fault damage surrounding such basement faults we showed that the quaternary active fault has the damage zone characterized by a fracture density that decays exponentially with distance from the fault for both healed and open microfractures in contrast quaternary inactive faults contain only healed microfracture damage zone cross cutting relationships between microfractures and a minimum healing temperature of 100 c suggest that healed microfractures formed before and at deeper levels than did unhealed microfractures the damage zone defined by open microfractures reflects the recent fault movement during exhumation associated with erosion and regional uplift from the maximum depth at which microfractures may remain unhealed microfracture analysis can therefore be used to examine the history of basement fault activity