automated mineralogical methodology to study carbonate grain microstructure an example from oncoids oncoids collected from an arid intertidal embayment of the gulf of aqaba saudi arabia were examined for their morphology and mineralogical composition this study tested a methodological approach for studying oncoid microstructure and chemical mineralogical composition in detail the method was applied to more than 30 oncoid samples and examined internal morphology and composition via automated mineralogy and petrographic methods deploying quantitative evaluation of minerals by scanning electron microscopy qemscan the qemscan analysis system gathers x ray and backscattered electron data from predefined points on a sample and interprets it in mineralogical terms by comparisons with a spectral library volumetric modal analysis a function of the cumulative data obtained is then used to quantify the mineral species present in the sample the most abundant minerals in this study consist of calcium carbonate 60 70 quartz dominates the detrital trapped grains 19 5 potassium feldspar and albite constitute 5 6 and 3 4 respectively minerals such as illite chlorite biotite muscovite smectite kaolinite apatite and ilmenite and siderite individually make up less than 1 of the overall oncoid composition unlike traditional light microscope petrography x ray fluorescence and x ray diffraction methods the proposed technique has several advantages including but not limited to preservation of the oncoid microstructure porosity and pore size estimation elemental distribution of major minerals determination of the chemical composition of grains as well as the cement and relatively high accuracy of elemental compositional data taken from polished sections this study shows that qemscan can provide an effective and robust tool in analyzing different components of oncoids and other carbonate grains

joint sensing of bedload flux and water depth by seismic data inversion rivers are the fluvial conveyor belts routing sediment across the landscape while there are proper techniques for continuous estimates of the flux of suspended solids constraining bedload flux is much more challenging typically involving extensive measurement infrastructure or labour intensive manual measurements seismometers are potentially valuable alternatives to in stream devices delivering continuous data with high temporal resolution on the average behaviour of a reach two models exist to predict the seismic spectra generated by river turbulence and bedload flux however these models require estimating a large number of parameters and the spectra usually overlap significantly which hinders straightforward inversion we provide three functions contained in the r package eseis that allow generic modelling of hydraulic and bedload transport dynamics from seismic data using these models the underlying monte carlo approach creates lookup tables of potential spectra which are compared against the empirical spectra to identify the best fitting solutions the method is validated against synthetic data sets and independently measured metrics from the nahal eshtemoa israel a flash flood dominated ephemeral gravel bed river our approach reproduces the synthetic time series with average absolute deviations of 0 01 0 04 m water depth ranging between 0 1 m and 0 00 0 04 kg sm bedload flux ranging between 0 4 kg sm the example flash flood water depths and bedload fluxes are reproduced with respective average deviations of 0 10 m and 0 02 kg sm our approach thus provides generic testable and reproducible routines for a quantitative description of key metrics hard to collect by other techniques in a continuous and representative manner

correlation between the depth to the lower crustal high conductive layer and heat flow in the canadian cordillera abstract in much of the southern canadian cordillera the top of the lower crustal electrical conductor coexists with the 450 c isotherm a statistical correlation between the depth to the top of the lower crustal electrical conductor heat flow and 450 c isotherm are shown based on mt and heat flow results in southern british columbia canada the depth to the lower crustal conductor and the depth to the 450 c isotherm vary from 20 35 km in western b c insular belt coast plutonic complex intermontane belt to less than 10 km in the eastern part of the canadian cordillera omineca belt the largest depths are in the insular belt 35 km the coexistence of the top of the lower crustal electrical conductor top of the zone of lower crustal seismic reflectors and 450 c isotherm supports the hypothesis that the 450 c isotherm defines the top of the zone over which interconnected fluid can exist in the lower crust

the dominance of dispersion in the evolution of bed material waves in gravel bed rivers bed material waves are temporary zones of sediment accumulation created by large sediment inputs recent theoretical experimental and field studies examine factors influencing dispersion and translation of bed material waves in quasi uniform gravel bed channels exchanges of sediment between a channel and its floodplain are neglected within these constraints two factors influence relative rates of dispersion and translation 1 interactions between wave topography flow and bed load transport and 2 particle size differences between wave material and original bed material our results indicate that dispersion dominates the evolution of bed material waves in gravel bed channels significant translation requires a low froude number which is uncharacteristic of gravel bed channels and low wave amplitude which for a large wave can be achieved only after substantial dispersion wave material of small particle size can promote translation but it primarily increases bed load transport rate and thereby accelerates wave evolution copyright 2001 john wiley sons ltd

a physical model for seismic noise generation by turbulent flow in rivers previous studies suggest that the seismic noise induced by rivers may be used to infer river transport properties and previous theoretical work showed that bedload sediment flux can be inverted from seismic data however the lack of a theoretical framework relating water flow to seismic noise prevents these studies from providing accurate bedload fluxes and quantitative information on flow processes here we propose a forward model of seismic noise caused by turbulent flow in agreement with previous observations modeled turbulent flow induced noise operates at lower frequencies than bedload induced noise moreover the differences in the spectral signatures of turbulent flow induced and bedload induced forces at the riverbed are significant enough that these two processes can be characterized independently using seismic records acquired at various distances from the river in cases with isolated turbulent flow noise we suggest that riverbed stress can be inverted finally we validate our model by comparing predictions to previously reported observations we show that our model captures the spectral peak located around 6 7 hz and previously attributed to water flow at hance rapids in the colorado river united states we also show that turbulent flow causes a significant part of the seismic noise recorded at the trisuli river in nepal which reveals that the hysteresis curve previously reported there does not solely include bedload but is also largely influenced by turbulent flow induced noise we expect the framework presented here to be useful to invert realistic bedload fluxes by enabling the removal of the turbulent flow contribution from seismic data

variations in architecture and cyclicity in fault bounded carbonate platforms early miocene red sea rift nw saudi arabia abstract the early miocene was a period of active rifting and carbonate platform development in the midyan peninsula nw saudi arabia however there is no published literature available dealing with the detailed characterization of the different carbonate platforms in this study area therefore this study aims to present new stratigraphic architectural models that illustrate the formation of different carbonate platforms in the region and the forcing mechanisms that likely drove their formation this study identified the following features formed during active rifting a a late aquitanian n4 fault block hangingwall dipslope carbonate ramp b a late burdigalian n7 n8 isolated normal fault controlled carbonate platform with associated slope deposits and c a late burdigalian n7 n8 attached fault bounded platform with reef buildups rimmed shelf developed on a footwall fault tip within a basin margin structural relay zone that formed coinciding with the second stage of rifting variations in cyclicity have been observed within the internal stratigraphic architecture of each platform and also between platforms high resolution sequence stratigraphic analysis shows to be parasequences the smallest depositional packages metre scale cycles within the platforms the hangingwall dipslope carbonate ramp and the attached platform demonstrate aggradational progradational parasequence stacking patterns these locations appear to have been more sensitive to eustatic cyclicities despite the active tectonic setting the isolated fault controlled carbonate platform reveals disorganized stratal geometries in both platform top and slope facies suggesting a more complex interplay of rates of tectonic uplift and subsidence variation in carbonate productivity and resedimentation of carbonates such that any sea level cyclicity is obscure this study explores the interplay between different forcing mechanisms in the evolution of carbonate platforms in active extensional tectonic regions characterization of detailed parasequence scale internal architecture allows the spatial variation in syn depositional relative base level changes to be inferred and is critical for understanding the development of rift basin carbonate platforms such concepts may be useful for the prediction of subsurface facies relationships beyond interwell areas in hydrocarbon exploration and reservoir modeling activities

factors controlling elastic properties in carbonate sediments and rocks carbonate sediments are prone to rapid and pervasive diagenetic alterations that change the mineralogy and pore structure within carbonate rocks in particular cementation and dissolution processes continuously modify the pore structure to create or destroy porosity in extreme cases these modifications can completely change the mineralogy from aragonite calcite to dolomite or reverse the pore distribution whereby original grains are dissolved to produce pores as the original pore space is filled with cement to form the rock figure 1 all these modifications alter the elastic properties of the rock and therefore the sonic velocity the result is a dynamic relationship among diagenesis porosity pore type and sonic velocity the result is a wide range of sonic velocity in carbonates in which compressional wave velocity vp ranges from 1700 to 6600 m s and shear wave velocity vs from 600 to 3500 m s

passive acoustic monitoring of bed load discharge in a large gravel bed river surrogate technologies to monitor bed load discharge have been developed to supplement and ultimately take over traditional direct methods our research deals with passive acoustic monitoring of bed load flux using a hydrophone continuously deployed near a river bed this passive acoustic technology senses any acoustic waves propagated in the river environment and particularly the sound due to interparticle collisions emitted during bed load movement a data set has been acquired in the large alpine gravel bedded drau river analysis of the short term frequency response of acoustic signals allows us to determine the origin of recorded noises and to consider their frequency variations results are compared with ancillary field data of water depth and bed load transport inferred from the signals of a geophone array hydrophone and geophone signals are well correlated thanks to the large network of deployed geophones analysis of the spatial resolution of hydrophone measurements shows that the sensor is sensitive to bed load motion not only locally but over distances of 5 10 m 10 20 of river width our results are promising in terms of the potential use of hydrophones for monitoring bed load transport in large gravel bed rivers acoustic signals represent a large river bed area rather than being local hydrophones can be installed in large floods they can be deployed at a low cost and provide continuous monitoring at high temporal resolution

temporal variations in bedload transport rates associated with the migration of bedforms temporal variations in bedload transport rates that occur at a variety of timescales even under steady flow conditions are accepted as an inherent component of the bedload transport process rarely however has the cause of such variations been explained clearly we consider three data sets obtained from laboratory experiments that refer to measurements of bedload transport made with continuously recording bedload traps each data set is characterized by a predominant low frequency oscillation on which additional higher frequency oscillations generally are superimposed the period of these oscillations as isolated through the use of spectral analysts ranged between 0 47 and 168 minutes and was associated unequivocally with the migration of bedforms such as ripples dunes and bars the extent to which such oscillatory behaviour may be recognized in a data set depends on the duration of sampling and the length of the sampling time with respect to the period of a given bedform several theoretical probability distribution functions have been developed to describe the frequency distributions of relative bedload transport rates that are associated with the migration of bedforms einstein 1937b hamamori 1962 carey and hubbell 1986 these distribution functions were derived without reference to a sampling interval we present a modification of hamamori s 1962 probability distribution function generated by monte carlo simulation which permits one to specify the sampling interval in relation to the length of a bedform comparisons between the simulated and observed frequency distributions that were undertaken on the basis of the data described herein are good significant at the 90 per cent confidence level finally the implications that temporal variability which is associated with the migration of bedforms have for the accurate determination of bedload transport rates are considered

period and amplitude of bedload pulses in a macro rough channel it is known that bedload fluctuates over time in steep rivers with wide grain size distributions even under conditions of constant sediment feed and water discharge bedload fluctuations which are a consequence of grain sorting are periodic and are related to fluctuations in the flow velocity and channel bed morphology the presence of large relatively immobile boulders such as erratic blocks that are often present inmountain streams has a strong impact on flow conditions and sediment transport however their influence on bedload fluctuations has not been studied sediment transport fluctuations were investigated in this study in a set of 38 laboratory experiments carried out on a steep tilting flume under several conditions of constant sediment andwater discharge for three different slopes s 6 7 9 9 and 13 sediment transport bulkmean flowvelocities and variables describing the channel bed morphologywere measured regularly during the experiments periodic bedload pulses were clearly visible in all of the experiments alongwith flowvelocity and channel bed morphology fluctuations correlation analysis showed that the durations of these cycleswere similar although theywere not necessarily in phase the pulses were characterized by their amplitude and period as a function of various boulder spatial densities and diameters we could showthat for higher streampower the fluctuations decrease in cycle duration and in amplitude the presence of boulders increases the stream power needed to transport a given amount of sediment thus decreasing the bedload fluctuations

the causes of bedload pulses in a gravel channel the implications of bedload grain size distributions unsteady bedload transport was measured in two c 5 m wide anabranches of a gravel bed braided stream draining the haut glacier d arolla switzerland during the 1998 and 1999 melt seasons bedload was directly sampled using 152 mm square helley smith type samplers deployed from a portable measuring bridge and independent transport rate estimates for the coarser size fractions were obtained from the dispersion of magnetically tagged tracer pebbles bedload transport time series show pulsing behaviour under both marginal 1998 and partial 1999 transport regimes there are generally weak correlations between transport rates and shear stresses determined from velocity data recorded at the measuring bridge characteristic parameters of the bedload grain size distributions d50 d84 are weakly correlated with transport rates analysis of full bedload grain size distributions reveals greater structure with a tendency for transport to become less size selective at higher transport rates the bedload time series show autoregressive behaviour but are dif cult to distinguish by this method state space plots and associated measures of time series separation reveal the structure of the time series more clearly the measured pulses have distinctly different time series characteristics from those modelled using a one dimensional sediment routing model in which bed shear stress and grain size are varied randomly these results suggest a mechanism of pulse generation based on irregular low amplitude bedforms that may be generated in channel or may represent the advection of material supplied by bank erosion events copyright 2003 john wiley sons ltd

simplicity and complexity of bed load response during flash floods in a gravel bed ephemeral river a 10 year field study 1 a decade of data for the nahal eshtemoa an unarmored gravel bed ephemeral river reveals that bed load flux during rain fed flash floods is a simple function of channel average boundary shear stress however the relation is inadequately described by a power function of the type commonly used in predictive bed load equations and a linear function gives a much better fit the success of a linear function is related to the unarmored nature of the bed material typical of ephemeral gravel bed rivers and the ready availability of sediment at all levels of transport stage bed load response to changing shear stress is largely undifferentiated as flash floods wax or wane however while most data conform to a simple relation between bed load and hydraulic stress some for individual floods or flood segments do not reflecting variability in sediment supply and texture three type behaviors are identified that assist in explaining both the general simple pattern and the limited scatter of the bed load shear stress plot type 1 provides the majority of the data giving the general linear relation between bed load flux and boundary shear stress type 2 is rare given the flashy nature of the hydrograph but represents comparatively steady flows well above the entrainment threshold during which bed load sheets or the breakup of grain clusters lead to spasmodic changes in bed load flux type 3 shows a weak relation between shear stress and bed load flux representing flow conditions just above the entrainment threshold

integrated automatic and continuous bedload monitoring in gravel bed rivers bedload monitoring techniques have been developed and applied for many years in rivers ranging from steep mountain torrents to the large gravel bed danube river in austria most monitoring stations use a combination of direct mobile bag samplers slot samplers and indirect geophones hydrophones measurement methods each individual technique is adequate yet features particular boundary conditions and limitations related to hydraulic and sampling efficiency functionality during floods sampling duration or grain size we show the capabilities and limitations of the different monitoring devices with respect to technical operational and economic criteria evaluating their suitability for determining bedload transport parameters bedload monitoring results of a measuring site at the drau river in carinthia austria are used to illustrate the specific range of the device application we present an integrated automatic and continuous bedload monitoring system it complements the specific limitations of single monitoring methods by additional measurement devices enabling comprehensive monitoring of the bedload transport process we then derive the bedload discharge integrated calculation approach and the bedload rating curve approach and discuss their application for determining bedload discharge qb and total bedload mass vb whereas the integrated approach combines data from direct monitoring methods with indirect techniques the rating curve approach uses only data from direct bedload monitoring devices we demonstrate that applying an integrated automatic and continuous bedload monitoring system and combining the bedload discharge integrated calculation approach and bedload rating curve approach yields accurate bedload discharge results

bed load transport and boundary roughness changes as competing causes of hysteresis in the relationship between river discharge and seismic amplitude recorded near a steep mountain stream hysteresis in the relationship between bedload transport and river stage is a well documented phenomenon with multiple known causes consequently numerous studies have interpreted hysteresis in the relationship between seismic ground motion near rivers and some measure of flow strength i e discharge or stage as the signature of bedload transport here we test this hypothesis in the erlenbach stream swiss prealps using a metric to quantitatively compare hysteresis in seismic data with hysteresis recorded by geophones attached beneath steel plates within the streambed a well calibrated proxy for direct sediment transport measurements we find that while both the geophones and seismometers demonstrate hysteresis the magnitude and direction of hysteresis are not significantly correlated between these data indicating that the seismic signal at this site is primarily reflecting hysteresis in processes other than sediment transport seismic hysteresis also does not correlate significantly with the magnitude of sediment transport recorded by the geophones contrary to previous studies assumptions we suggest that hydrologic sources and changes in water turbulence for instance due to evolving boundary conditions at the bed rather than changes in sediment transport rates may sometimes contribute to or even dominate the hysteresis observed in seismic amplitudes near steep mountain rivers

modal and thermal analysis of les arches unstable rock column vercors massif french alps a potentially unstable limestone column 1000 m3 vercors french alps delineated by an open rear fracture was continuously instrumented with two three component seismic sensors from mid may 2009 to mid october 2011 spectral analysis of seismic noise allowed several resonance frequencies to be determined ranging from 6 to 21 hz the frequency domain decomposition fdd technique was applied to the ambient vibrations recorded on the top of the rock column three vibration modes were identified at 6 7 5 and 9 hz describing the upper part of corresponding modal shapes finite element numerical modelling of the column dynamic response confirmed that the first two modes are bending modes perpendicular and parallel to the fracture respectively while the third one corresponds to torsion seismic noise monitoring also pointed out that resonance frequencies fluctuate with time under thermomechanical control for seasonal cycles changes in frequency are due to the variations of the bulk elastic properties with temperature at daily scale increase in fundamental frequency with temperature has been interpreted as resulting from the rock expansion inducing a closure of the rear fracture rock bridges hence stiffening the contact between the column and the rock mass conversely the rock contraction induces a fracture opening and a decrease in resonance frequency in winter when the temperature drops below 0 c a dramatic increase in fundamental frequency is observed from 6 hz to more than 25 hz resulting from ice formation in the fracture during spring the resonance frequency gradually diminishes with ice melting to reach the value measured before winter

a physical model for seismic noise generation from sediment transport in rivers measuring sediment flux in rivers remains a significant problem in studies of landscape evolution recent studies suggest that observations of seismic noise near rivers can help provide such measurements but the lack of models linking observed seismic quantities to sediment flux has prevented the method from being used here we develop a forward model to describe the seismic noise induced by the transport of sediment in rivers the model provides an expression for the power spectral density psd of the rayleigh waves generated by impulsive impacts from saltating particles which scales linearly with the number of particles of a given size and the square of the linear momentum after incorporating expressions for the impact velocity and rate of impacts for fluvially transported sediment we observe that the seismic noise psd is strongly dependent on the sediment size such that good constraints on grain size distribution are needed for reliable estimates of sediment flux based on seismic noise observations the model predictions for the psd are consistent with recent measurements and based on these data a first attempt at inverting seismic noise for the sediment flux is provided

seismic array constraints on reach scale bedload transport measurements and mechanical models of heterogeneous bedload transport in rivers remain basic challenges for studies of landscape evolution and watershed management a 700 m reach of the trinity river northern california usa a large gravel bed river was instrumented with an array of 76 seismographs during a dam controlled ood and gravel augmentation to investigate the potential for out of stream monitoring the temporal response to gravel augmentation during constant discharge provides strong evidence of seismic sensitivity to bedload transport and aids in identification of the seismic frequencies most sensitive to bedload in the study area following gravel augmentations the seismic array reveals a period of enhanced transport that spans most or all of the reach for 7 10 h neither the duration nor the downstream extent of enhanced transport would have been constrained without the seismic array sensitivity to along stream transport variations is further demonstrated by seismic amplitudes that decrease between the upper and lower halves of the reach consistent with decreased bedload ux constrained by time lapse bathymetry insight into the magnitude of impact energy that reaches the bed is also gained from the seismic array observed peak seismic power is 1 5 of that predicted by a model of saltation over exposed bedrock our results suggest that dissipation of impact energy due to cover effects needs to be considered to seismically constrain bedload transport rates and that noninvasive constraints from seismology can be used to test and refine mechanical models of bedload transport

bed load transport monitoring using seismic observations in a low gradient rural gravel bed stream the characterization of bed load transport in rivers is critical for the fundamental understanding and management of fluvial systems bed load monitoring based on seismological observations has recently emerged as a viable noninvasive measurement technique however applications of this new approach have been hitherto restricted to the case of sediment transport in steep mountain rivers here we further develop and evaluate the approach for a lower gradient gravel bed stream in a rural catchment using seismic observations in situ hydroacoustic measurements of bed load motion impact plate type device and 3 d hydromorphodynamic modeling the results of this joint analysis of seismic measurements hydroacoustic records and sediment transport simulations show that the seismic monitoring technique for bed load transport characterization is applicable for a broader range of river systems than previously investigated

spectral analysis of seismic noise induced by rivers a new tool to monitor spatiotemporal changes in stream hydrodynamics to 20 db relative to m s 2 hz for all the stations located along a steep 30 km long narrow and deeply incised channel of the trisuli river a major trans himalayan river the early summer increase in high frequency energy is modulated by a 24 h periodicity where the minimum of seismic noise level is reached around noon and the maximum is reached late in the evening a detailed study of seismic noise amplitude reveals a clear correlation with both regional meteorological and hydrological data along the trisuli river seasonal increase in ambient noise coincides with the strong monsoon rainfall and a period of rapid melting of snow and ice in the high elevations the observed 24 h cyclicity is consistent with the daily fluctuation of the precipitation and river discharge in the region river induced seismic noise is partly generated by stream turbulence but this mechanism fails to explain the observed clockwise hysteresis of seismic noise amplitude versus water level this pattern is better explained if a significant part of the observed seismic noise is caused by ground vibrations generated by bed load transport this points out the potential of using background seismic noise to quantify in continuous river bed load and monitor its spatial variations which remain difficult with classical approaches

glacial lake outburst floods as drivers of fluvial erosion in the himalaya himalayan rivers are frequently hit by catastrophic floods that are caused by the failure of glacial lake and landslide dams however the dynamics and long term impacts of such floods remain poorly understood we present a comprehensive set of observations that capture the july 2016 glacial lake outburst flood glof in the bhotekoshi sunkoshi river of nepal seismic records of the flood provide new insights into glof mechanics and their ability to mobilize large boulders that otherwise prevent channel erosion because of this boulder mobilization glof impacts far exceed those of the annual summer monsoon and glofs may dominate fluvial erosion and channel hillslope coupling many tens of kilometers downstream of glaciated areas long term valley evolution in these regions may therefore be driven by glof frequency and magnitude rather than by precipitation

fully automated carbonate petrography using deep convolutional neural networks abstract carbonate rocks are important archives of past ocean conditions as well as hosts of economic resources such as hydrocarbons water and minerals geologists typically perform compositional analysis of grain matrix cement and pore types in order to interpret depositional environments diagenetic modification and reservoir quality of carbonate strata such information can be obtained primarily from petrographic analysis a task that is costly labor intensive and requires in depth knowledge of carbonate petrology and micropaleontology recent studies have leveraged machine learning based image analysis including deep convolutional neural networks dcnn to automate description classification and interpretation of thin sections subsurface core images and seismic facies which would accelerate data acquisition and reproducibility for these tasks in carbonate rocks this approach has been applied primarily to recognize carbonate lithofacies and no attempt has been made to individually identify and quantify various types of carbonate grains matrix and cement in this study the applicability and performance of dcnn based object detection and image classification approaches are assessed with respect to carbonate compositional analysis the training data comprised of more than 13 000 individually labelled objects from nearly 4000 carbonate petrographic images the dataset is grouped into six and nine different classes for the image classification and object detection tasks respectively even with a small and relatively imbalanced training set the dcnn was able to achieve an f1 score of 92 for image classification and 84 mean precision for object detection by combining one cycle policy class weight and label mixup smoothing methods this study highlights the inefficiency of image classification as an approach to replicating human description and classification of carbonate petrography by contrast dcnn based object detection appears capable of approaching human speed and accuracy in the area of carbonate petrography because it is able to individually locate and identify different carbonate components with greater cost efficiency speed and reproducibility than conventional human petrographic analysis