sources sinks and storage of river sediment in the atlantic drainage of the united states the history of sediment and its movement in the atlantic drainage demonstrate some of the difficulties of modeling sediment on a river basin scale soil erosion was accelerated by a factor of at least 10 when european settlers cleared forests and planted crops although increasing soil conservation practice and decreasing crop farming have since reduced the rates of erosion large quantities of eroded material are still stored on hillslopes and in stream valleys where they continue to augment the sediment loads of the rivers the sediment from this episode of erosion that is largely past can be expected to emerge from storage for many decades and perhaps even several centuries to come the reservoirs that have been built on many of the major rivers trap significant portions of the moving sediment which in some places may be remobilized by large floods essentially all the river sediment that reaches the atlantic coastal zone is trapped in estuaries and coastal marshlands probably less than 5 is deposi

delineating alteration footprints from field and aster swir spectra geochemistry and gamma ray spectrometry above regolith covered base metal deposits an example from abra western australia

landsliding and the evolution of normal fault bounded mountains much of the tectonic and climatic history in high relief regions such as the mountains of the western u s basin and range province is contained in the morphology of hillslopes drainage networks and other landforms that range in scale from 10 1 to 101km to understand how these landforms evolve we have developed a numerical landscape evolution model that combines a detailed tectonic displacement field with a set of physically based geomorphic rules bedrock landsliding long recognized as a significant geomorphic process in mountainous topography is for the first time explicitly included in the rule set in a series of numerical experiments we generate synthetic landscapes that closely resemble mountainous topography observed in the basin and range the production of realistic landscapes depends critically on the presence of bedrock landslides and landsliding yields rates of long term erosion that are comparable in magnitude to those of fluvial erosion the erosive efficiency of bedrock landsliding implies that hillslopes may respond very quickly to changes in local base level and that fluvial erosion is the rate limiting process in steady state experimental landscapes our experiments generate power law distributions of landslide sizes somewhat similar to both field and laboratory observations thus even a simple model of bedrock landsliding is capable of quantitatively reproducing mountainous topography and landslide distributions and represents a significant step forward in our understanding of the evolution of normal fault bounded ranges

detectability of minerals on desert alluvial fans using reflectance spectra we analyzed the visible and near infrared reflectance spectra of soil samples collected from desert alluvial and colluvial surfaces in the cuprite mining district nevada these surfaces are downslope from hydrothermally altered volcanic rocks that contain spectrally characteristic minerals such as alunite and kaolinite coarse fractions of the soils on the alluvial fans are mineralogically variable and express the upslope lithologies fine fractions are remarkably similar mineralogically and spectrally in all samples because of dilution of local mineral components by regionally derived windblown dust theoretical models for spectral mixing and for particle size effects were used to model the observed spectral variations diagnostic mineral absorption bands in the spectra of fan materials were enhanced by computationally removing the spectrum of the homogenous fine soil component detection limits for minerals were found to be controlled by the sensitivity of the instrument the spectral contrast between the mineral and the background and the relative brightnesses of the mineral and the background these results show that spectral mixing models are useful for analyzing data with high spectral resolution obtained by field and aircraft spectrometers

application of the crosta technique for porphyry copper alteration mapping using etm data in the southern part of the iranian volcanic sedimentary belt abstract many of the known porphyry copper deposits in iran are situated in the central iranian volcanic belt the area under study is located in the southern part of this belt and covers an area of about 6600 km2 the climate in the area is semi arid given the poor soil development and poor vegetation cover but abundant outcrops the arid semi arid part of the belt is most suitable for remote sensing study enhanced thematic mapper plus etm images have been used for alteration mapping crosta method was found useful for enhancing the areas in which the regolith contains a high proportion of hydroxyl and iron oxide minerals the crosta method has been used on selected 4 and 6 bands areas with iron oxide and hydroxyl minerals have been enhanced by using six bands of etm data

spatial and temporal variations in rockfall determined from tls measurements in a deglaciated valley switzerland steep u shaped valleys produced by glaciation are commonly eroded by rockfall in this study we investigate modern and long term power law predicted rates of rock wall retreat in a deglaciated valley our emphasis is on the 5 2 km2 calcareous cliffs covering in the lauterbrunnen valley switzerland terrestrial laser scans were collected during nine field campaigns over 18 months to provide a continuous coverage of most of the valley walls results indicate a total of 122 rockfalls with volumes ranging between 0 06 0 01 and 119 34 1 07 m3 different size groups of rockfall events were correlated with environmental factors e g freeze thaw cycles temperature precipitation and seismicity using a linear regression with variable lag times of 0 6 months the highest correlation factor r 0 6 p 0 08 90 significance level is observed for freeze thaw cycles and rockfall events smaller than 1 m3 with a 2 month delay between temperature extremes and rockfall frequency magnitude relationships for rockfall events were calculated to predict less frequent larger rockfall events that did not occur during the observation period a monte carlo analysis was applied to the frequency magnitude relationship to evaluate the sensitivity of results to their stochastic nature an average power law exponent of 1 71 0 09 was calculated using linear regression the calculated exponents are similar to other studies in calcareous rock settings conducted over different observation durations finally we determine an average total eroded volume of 2 0 0 01 0 6 103 m3 yr and a corresponding long term power law predicted cliff retreat rate of 0 39 0 02 0 12mm yr

assessing the utility of visible to shortwave infrared reflectance spectroscopy for analysis of soil weathering intensity and paleoclimate reconstruction abstract visible to shortwave infrared reflectance vswir spectroscopy is a fast and efficient approach for estimation of soil properties in order to test whether soil weathering intensity can be predicted using reflectance spectra in the vswir range 350 2500 nm and to examine the efficacy of this methodology to supplement or substitute for traditional mineralogical and geochemical techniques of paleoclimate reconstruction we investigated a quaternary soil sequence at shengli in the sichuan basin of southwestern china vswir absorption bands can be characterized by geometrical parameters including position p depth d width w asymmetry as and full width at half maximum f our results indicate that spectral features in the visible to near infrared vnir 350 1000 nm range can be interpreted in terms of the presence and or concentration of individual fe oxide phases spectrally detected water is mostly bound in clay minerals and this single dominant water source facilitates interpretation of shortwave infrared swir 1000 2500 nm parameters soil spectral parameters were compared with the fe oxide mineralogy major element composition and clay mineralogy of soil samples obtained from conventional laboratory analyses strong correlations are found between vnir parameters and fe oxide mineralogy with d 900 serving as the best proxy for total ferric iron concentration p 900 and d 700 d 500 exhibit similar variation trends and relationships to the hematite hematite goethite h h g ratio of soil samples confirming their value as monsoonal weathering intensity proxies lower values of p 900 and d 700 d 500 indicate warmer and seasonally drier pedoenvironments reflecting a stronger east asian summer monsoon the utility of some swir parameters for assessment of weathering intensity declines in inhomogeneous soils e g those having vermiform structure thus spectral evaluation of weathering intensity is most effective in soils that are relatively homogeneous for which weathering degree is highly correlated to as 2200 d 2200 d 1900 and as 1400 the utility of these spectral proxies depends mainly on the mineral composition of soils and the application type i e laboratory versus field studies the application of vswir in the field e g imaging spectroscopy or is shows promise for rapid in situ mapping of weathering intensity thus providing a convenient approach to paleoclimate reconstruction in remote and inaccessible regions

regional analysis of tertiary volcanic calderas western u s using landsat thematic mapper imagery abstract the basin and range province of southern nevada is an excellent setting to study landsat imagery over volcanic rock assemblages the area is semiarid sparsely vegetated and contains relatively youtful 6 14 ma volcanic calderas with compositionally diverse volcanic rock assemblages investigation of rock spectra whole rock geochemistry desert varnish and landsat imagery indicates that the longer wavelength visible and near infrared thematic mapper tm bands 3 5 and 7 provide more effective lithologic discimination than the shorter wavelength bands due partly to deeper penetration of lower frequency energy and greater primary rock compositional response spectral contamination of vegetation degrades lithologic information in tm band 4 thus ratios color composites and intensity saturation hue images using tm bands 3 5 and 7 generally lead to superior lithologic contrast shorter wavelength tm bands 1 and 2 are affected more by surficial weathering products including desert varnish which may or may not provide an indirect link to lithologic identity these relationships lead to a rock varnish albedo difference that aids identification of desert varnish on leucocratic rocks using tm band 2 5 and 5 2 ratio images principles component color composites provide best overall lithologic contrast but not specific lithologic identification pc2 tends to contain lithologically dominant variance and combines favorably with other images influenced strongly by lithology late magmatic differentiates that are evolved with respect to alkalies and the incompatible elements exhibit steep spectral curves throughout the tm bands 5 7 interval leading generally to low 5 7 ratios and dark contrast on 5 7 ratio images guidelines for lithologic analysis of volcanic terrain using landsat tm imagery are outlined

origins of marslike spectral and magnetic properties of a hawaiian palagonitic soil a palagonitic soil hwmk1 from mauna kea hawaii has marslike spectral and magnetic properties reflectivity spectra of 20 m size separates resemble spectra for martian bright regions and reflectivity spectra of coarser size separates have some spectral characteristics in common with spectra for martian dark regions the bulk soil is magnetic with a saturation magnetization of 0 98 a m2 kg of sample 10 a m2 kg of fe at 296 k petrographic observations show that the soil contains separate populations of black and orange tephra particles which are relatively unaltered fragments of tachylite merocrystalline basalt and extensively weathered palagonitized fragments of sideromelane clear brown basalt glass respectively although both types of particles contain plagioclase and olivine microphenocrysts their iron oxide mineralogies are substantially different as documented by mossbauer and static magnetic measurements a strongly magnetic opaque iron oxide titanomagnetite is associated with black particles and is responsible for the magnetic nature of the soil a relatively weakly magnetic superparamagnetic ferric oxide and minor hematite are associated with orange particles and are responsible for the color the more highly weathered state higher state of oxidation of orange particles is a consequence of the faster weathering palagonitization rate for their sideromelane precursors than for tachylite increasing state of oxidation decreasing saturation magnetization and increasing near ir reflectivity with decreasing particle diameter of bulk soil are manifestations of the increasing proportions of palagonitic material as particle diameter decreases

sub pixel mapping of alunite and jarosite using aster data a case study from north of semnan north central iran abstract a widespread series of volcanic rocks and younger intrusive bodies are exposed in the north and northeastern semnan north central iran they show an intermediate to felsic composition which have undergone various types of alteration including alunite and jarosite in this research aster data were used for sub pixel mapping of these typical minerals using the mixtured tuned matched filtering mtmf algorithm the spectral properties of field samples were measured by an asd spectroradiometer and their spectra were analyzed through a visual comparison to the usgs spectral library however the z profile method was used for extraction of target spectra from pixels in which the occurrence of desired minerals were verified by other methods the mtmf output results revealed pixels with the highest fractions of alunite and jarosite dominantly near the altered rhyolitic and andesitic tuffs as well as in adamelites it is suggested that an integration of mtmf method and the aster data is a powerful approach for sub pixel mapping of alunite and jarosite which could be applicable in mineral exploration projects

geomorphic responses of lower bega river to catchment disturbance 1851 1926 abstract prior to significant european settlement of the area in the 1850s lower bega river on the south coast of nsw had a narrow relatively deep channel lined by river oaks the river had a suspended or mixed load with platypus habitat available in pools banks were fine grained and relatively cohesive silts and clays as was the floodplain which graded to a series of valley marginal swamps and lakes extensive evidence from maps and portion plans archival photographs bridge surveys and anecdotal sources complemented by field analysis of floodplain sedimentology including radiocarbon dated samples and vegetation remnants are used to document the dramatic metamorphosis in the character and behaviour of lower bega river in the latter half of the nineteenth century by 1926 the channel had widened extensively up to 340 and shallowed in association with bed aggradation by coarse sandy bedload floodplain accretion was dominated by fine to medium sands with some coarse sand splays in contrast with most other studies of channel metamorphosis in australia which have emphasised river responses to climatically induced flood histories relegating human impacts to a secondary role the profound changes to the geomorphic condition and behaviour of bega river reflect indirect human disturbance of bega catchment and direct but non point source disturbance to the channel extensive clearance of catchment floodplain and channel marginal vegetation occurred within a few decades of european settlement altering the hydrologic and sediment regime of the river and transforming the geomorphic effectiveness of floods although this study is situated in a relatively sensitive granitic catchment catchment clearance is likely to have induced equally significant responses in many other river systems in eastern australia in some instances the diffuse aspects of human disturbance on landscapes induce impacts on river character that are just as profound as major direct disturbances of river channels this may have profound implications in understanding and hence managing the geomorphic consequences of river behaviour in australia and elsewhere

topography based modeling of large rockfalls and application to hazard assessment 1 rockfalls are among the most important natural hazards in mountainous regions similarly to earthquakes and wildfires their sizes follow a power law distribution covering an enormous range of sizes in this paper the presumably first modeling approach that explains this power law distribution quantitatively is presented applied to the european alps the himalayas and the rocky mountains the model suggests that a power law exponent of 1 35 with respect to the detached volume is a universal property of rockfalls beyond reproducing and explaining existing statistical data the model allows an estimate on size and frequency of the largest possible rockfalls in a region which cannot be derived from available rockfall inventories so far

earthquake induced chains of geologic hazards patterns mechanisms and impacts large earthquakes initiate chains of surface processes that last much longer than the brief moments of strong shaking most moderate and large magnitude earthquakes trigger landslides ranging from small failures in the soil cover to massive devastating rock avalanches some landslides dam rivers and impound lakes which can collapse days to centuries later and flood mountain valleys for hundreds of kilometers downstream landslide deposits on slopes can remobilize during heavy rainfall and evolve into debris flows cracks and fractures can form and widen on mountain crests and flanks promoting increased frequency of landslides that lasts for decades more gradual impacts involve the flushing of excess debris downstream by rivers which can generate bank erosion and floodplain accretion as well as channel avulsions that affect flooding frequency settlements ecosystems and infrastructure ultimately earthquake sequences and their geomorphic consequences alter mountain landscapes over both human and geologic time scales two recent events have attracted intense research into earthquake induced landslides and their consequences the magnitude m 7 6 chi chi taiwan earthquake of 1999 and the m 7 9 wenchuan china earthquake of 2008 using data and insights from these and several other earthquakes we analyze how such events initiate processes that change mountain landscapes highlight research gaps and suggest pathways toward a more complete understanding of the seismic effects on the earth s surface

landslides in vibrating sand box what controls types of slope failure and frequency magnitude relations abstract although landslides are a worldwide significant natural hazard their physics is not well understood here landslides were induced in a vibrated box filled with wet practically cohesive sand simulating natural slope failure the questions addressed were a what controls the type of slope failure and b what controls frequency magnitude relations of landslides in the experiments two end member slope failure types were obtained during application of only horizontal acceleration a failure plane rapidly developed followed by a box sized slump in contrast under application of only vertical acceleration mode i fractures formed slowly dissecting the slope into blocks the fractures caused a strength heterogeneity and were followed by block sliding in the vertical shaking experiments a power law size distribution of slide blocks was measured controlled by the fracture distribution the experiments suggest that heterogeneity may be a major control on the size distribution of natural landslide inventories in a homogeneous environment the landslide will have a characteristic size of the whole system in a heterogeneous slope sizes of landslides will reflect the heterogeneity following the above experimental observations our hypothesis is that natural landslides may be divided into two groups small and large the processes controlling their formation are different i the smaller natural landslides occur as slumps within the unconsolidated rather homogeneous sediments typical of the upper few meters close to the surface the size of these slumps is determined by the dependence between failure depth constrained to be the depth of the unconsolidated sediments and area ii in contrast to the homogeneous upper layer rock mass below the unconsolidated sediment is always heterogeneous due to fractures layers and bedding this preexisting heterogeneity is the source of the power law decay observed for the large landslide portion in natural landslide distributions finally in light of these insights in hazard evaluation it is advised to fit a regression line to the power law decay of the large landslide inventory only and consider the characteristic landslide separately

the character and age structure of valley fills in upper wolumla creek catchment south coast new south wales australia extensive valley fills at the base of the escarpment in upper wolumla creek on the south coast of new south wales australia have formed from a combination of cut and fill processes the valley fills comprise series of alternating horizontally bedded sand and mud units reflecting reworking of detritus from deeply weathered granites of the bega batholith sand units are deposited as sand sheets or splays on floodplain surfaces or in floodouts that form atop intact valley fill surfaces downstream of discontinuous gullies alternatively sands are deposited from bedload and form bars or part of the valley floor within channel fills organic rich mud units are deposited from suspension in swamps or in seepage zones at the distal margin of floodouts within 5 km of the escarpment valley deposits grade downstream from sand sheet and splay deposition in floodouts to mud deposition in swamp and seepage zones radiocarbon dates indicate that virtually the entire valley fill of upper wolumla creek was excavated prior to 6000 years bp remnant terraces are evident at valley margins the valley subsequently filled between 6000 years bp and 1000 years bp producing valley fills around 12 m deep but no greater than 300 m wide reincision into the valley fill on a scale smaller than the present incision phase is indicated at around 1000 years bp following which the channel refilled portion plans dated from 1865 refer to the study area as wolumla big flat and show large areas of swampy terrain suggesting that the valley fill had re established by this time within a few decades of european settlement the valley fill incised once more upper wolumla creek now has a channel over 10 m deep and 100 m wide in places draining a catchment area of less than 20 km2 1998 john wiley sons ltd

estimation of surface iron oxide abundance with suppression of grain size and topography effects abstract mineral forms of iron oxide such as hematite goethite and jarosite are important because they are widely distributed at the earth s surface and because they are used as indicators for mineral exploration iron oxide abundance in rocks containing these minerals can be estimated from the absorption depth at wavelengths of around 900 nm in a reflectance spectrum but this depth is also affected by extraneous factors such as grain size and topography this paper investigated the effect of grain size on reflectance spectra and proposed a method for estimating iron oxide abundance in surface rocks by using remotely sensed data with suppression of the effects of grain size and topography reflectance spectra were measured in a laboratory from rock powder samples of different grain sizes containing iron oxide minerals while the reflectance increased with decreasing grain size the presence of ferric iron caused the absorption depth to be almost constant at around 900 nm irrespective of the chemical composition of the sample in addition the difference between the reflectance at 550 nm and 760 nm slope was a function of grain size iron oxide abundance can be estimated accurately by mcr 900d which is the maximum absorption depth at the absorption center after the effect of grain size and topography was suppressed by slope and the continuum removal method which takes the ratio between the original spectrum and its continuum respectively correlation of mcr 900d results with datasets of actual spectral and chemical iron oxide laboratory measurements revealed that the mineral forms also need to be considered mcr 900d results were significantly correlated with rock samples classified as containing different forms of iron oxide minerals hematite goethite and jarosite finally mcr 900d was applied to an aviris dataset for the cuprite site in nevada usa the results represented the enrichment zones of iron oxide within hydrothermally altered areas

abundance and distribution of ultramafic microbreccia in moses rock dike quantitative application of mapping spectroscopy moses rock dike is a tertiary diatreme containing serpentinized ultramafic microbreccia sum located on the colorado plateau in utah field evidence indicates that sum was emplaced first followed by breccias derived from the permian strata exposed in the walls of the diatreme and finally by complex breccias containing basement and mantle derived rocks sum is primarily found dispersed throughout the matrix of the diatreme we examined the nature of sum abundance and spatial distribution using data collected remotely by the airborne imaging spectometer ais the minerals serpentine gypsum and illite as well as desert varnish and the lithologies sum and various sandstones were identified from the ais data six end members sum two types of sandstone gypsiferous soil clay rich soil desert varnish were chosen to represent the dominant lithologies of the surface in moses rock dike region spectra of these end members were used in an intimate mixing model to deconvolve the ais spectral data into surface abundance coefficients for each component using a nonnegative least squares inverse algorithm the results of this calculation of surface composition are consistent with field observations and investigations sum distribution and abundance in the matrix of the diatreme were examined in detail and two distinct styles of sum dispersion were observed one style is characterized by high to moderate sum abundance surrounded by halos of lesser sum abundance the dispersion halos grade steeply into regions of the matrix with little to no sum the second style is characterized by moderate sum abundances and broad dispersion halos with sum distributed across the entire width of the diatreme these dispersion styles are consistent with emplacement of the dike as a fluidized solid volatile system where sum which is emplaced early becomes reincorporated into the turbulent flow of the diatreme by abrasion and comminution by paniculate matter carried along in the eruption this eroded material is then dispersed throughout the matrix by eddy diffusion the first style represents an early arrested phase of the eruption sequence while the second style represents a more mature phase distributions of the second style probably indicate the location of channels where flow was concentrated during later stages of eruption since both styles are observed at the same level of erosion this indicates that the duration of eruption varied along strike at moses rock dike

statistical analysis of rockfall volume distributions implications for rockfall dynamics we analyze the volume distribution of natural rockfalls on different geological settings i e calcareous cliffs in the french alps grenoble area and granite yosemite cliffs california sierra and different volume ranges i e regional and worldwide catalogs contrary to previous studies that included several types of landslides we restrict our analysis to rockfall sources which originated on subvertical cliffs for the three data sets we find that the rockfall volumes follow a power law distribution with a similar exponent value within error bars this power law distribution was also proposed for rockfall volumes that occurred along road cuts all these results argue for a recurrent power law distribution of rockfall volumes on subvertical cliffs for a large range of rockfall sizes 102 1010 m3 regardless of the geological settings and of the preexisting geometry of fracture patterns that are drastically different on the three studied areas the power law distribution for rockfall volumes could emerge from two types of processes first the observed power law distribution of rockfall volumes is similar to the one reported for both fragmentation experiments and fragmentation models this argues for the geometry of rock mass fragment sizes to possibly control the rockfall volumes this way neither cascade nor avalanche processes would influence the rockfall volume distribution second without any requirement of scale invariant quenched heterogeneity patterns the rock mass dynamics can arise from avalanche processes driven by fluctuations of the rock mass properties e g cohesion or friction angle this model may also explain the power law distribution reported for landslides involving unconsolidated materials we find that the exponent values of rockfall volume on subvertical cliffs 0 5 0 2 is significantly smaller than the 1 2 0 3 value reported for mixed landslide types this change of exponents can be driven by the material strength which controls the in situ topographic slope values as simulated in numerical models of landslides densmore et al 1998 champel et al 2002 index terms 5104 physical properties of rocks fracture and flow 1815 hydrology erosion and sedimentation 8122 tectonophysics dynamics gravity and tectonics

discrimination of iron alteration minerals in visible and near infrared reflectance data field and laboratory studies were conducted to relate the mineralogy of rock and soil samples containing hematite fe2o3 goethite feooh and jarosite kfe3 so4 2 oh 6 to their reflectance properties in visible and near infrared wavelengths field reflectance measurements of regolith containing one or more of these minerals were made in the goldfield nevada mining district with a four channel radiometer the mineralogy and reflectance properties of regolith samples collected from these field measurement sites were then determined by laboratory studies mossbauer spectroscopy was used to identify the iron minerals present and their relative proportions the reflectance spectra of samples containing hematite and goethite were characterized by a reflectance minimum near 900 nm the location of this minimum could be accounted for by the relative proportions of hematite and goethite present in the samples under certain conditions it may be feasible to estimate the relative proportions of hematite and goethite on the earth s surface by determining the location of this near infrared reflectance minimum in high spectral resolution remote sensing data in addition the field measurements suggest that the ratio of band passes at 852 and 982 nm may be used to distinguish qualitatively among hematite goethite and jarosite thus maps of the distribution of these minerals may be derived from scanner images acquired in those band passes

characterization of microseepage induced diagenetic changes in the upper red formation qom region iran part ii a new insight using reflectance spectroscopic analysis abstract the classic microseepage model supports the notion that hydrocarbon pools leak to the surface over time and trigger an array of diagenetic physicochemical and mineralogical changes in the overlying sediments mapping the induced alteration mineralogy for microseepage targeting has been an appealing yet ambiguous practice mostly because of our incomplete understanding of the diversity of changes occurring in the environment to close this gap an integrated spectroscopic approach is adopted here to investigate the variability quantity and physicochemistry of diagenetic minerals induced by active microseepage systems over the alborz oil reservoir in the qom region iran the area includes an effectively sealed carbonate reservoir overlain by thick oligocene sediments of the upper red formation a large suite of samples collected from microseepage affected zones was spectrally characterized in the 350 2500 nm wavelength region and then statistically contrasted against unaffected samples gathered from a nearby control area the analysis reveals a novel array of mineralogic indicators for microseepage systems it indicates that smectites montmorillonite nontronite al rich mixed layer illite smectite fe rich chlorite and traces of palygorskite constitute the clay alterations this array is associated with the enrichment of k2o and loss of na2o and mgo from the system as indicated by x ray fluorescence measurements in the arid climate of the region the iron rich red beds fe2o3 6 are only moderately bleached and thus the subsequent chemical weathering of the relict irons has triggered goethite al poor and likely ferrihydrite and maghemite precipitation consequently besides the typical ferric iron bleaching the modification in the mineralogy of iron oxides oxyhydroxides marked by a shift in the absorption minimum at 900 nm is suggested as an additional indicator of microseepage systems fe chlorites constitute the dominant ferrous mineral present in the environment the affected strata are also associated with prevalent calcite and gypsum cements and occasionally jarosite occurrences based on the silica contents of the host rock the microseepage induced alterations are classified into two categories namely felsic and mafic wherein the latter is typified by the assemblages described here this study provides new insights into microseepage induced alterations and highlights the significance of reflectance spectroscopic techniques in facies determination and the alteration footprints mapping of onshore microseepage systems

dark materials in valles marineris indications of the style of volcanism and magmatism on mars rifting on the equatorial canyon system of valles marineris provides a unique view of the interior of the martian crust to depths reaching 7 km exposing several in situ bedrock units which testify to past volcanic and magmatic processes on mars a thick regionally extensive deposit observed in coprates and juventae chasmata is interpreted on the basis of spectral reflectance erosional morphology and tendency for eolian mobilization to be composed of mafic glass possibly an ancient martian analogue of the lunar terra mantling deposits spectral mapping suggests that the dark floor covering materials in the lower canyons are derived from this unit a series of cliffs in the ophir chasma wall rock is interpreted to be exposures of resistant bedrock the spectral signature of this massive and uniform unit most closely resembles that of terrestrial mafic rocks altered to or coated by crystalline hematite application of computer mapping techniques to probable young volcanic materials in the central troughs yields an inferred distribution of volcanic activity consistent with the interpretation of extrusion along faults near the margins of the canyon floors this result supports the hypothesis that the valles originated through tectonic extension

mineralogical characterization of rock surfaces formed by hydrothermal alteration and weathering application to remote sensing the value of 50 mu m was used as an approximate maximum penetration depth to include all mineral species which may contribute to a reflectance signal jarosite and alunite occur only in altered areas whereas hematite and goethite occur in both altered and unaltered areas incorporation of aluminum into hematite occurs only in unaltered areas the spectral shift to longer wavelengths which accompanies aluminum substitution should be useful in delineating mineralized zones modified journal abstract

sediment flux from a mountain belt derived by landslide mapping in humid uplands landsliding is the dominant mass wasting process in the western southern alps of new zealand landslides are scale invariant and have a power law magnitude frequency distribution independent studies from other regions suggest that this is a general property of landsliding this observation is of critical importance to the evaluation of the impact of events of different length scales over different time intervals on landscape evolution it is particularly useful when estimating regional geomorphic rates because it constrains the frequency and overall significance of extreme events which cannot otherwise be evaluated by integrating the complete response of the system we estimate the regional denudation rate due to landsliding to be 9 4 mm yr 1 sediment discharge from the western southern alps is dominated by landslide derived material

scaling properties of rainfall induced landslides predicted by a physically based model abstract natural landslides exhibit scaling properties revealed by power law relationships these relationships include the frequency of the size e g area volume of the landslides and the rainfall conditions responsible for slope failures in a region reasons for the scaling behavior of landslides are poorly known we investigate the possibility of using the transient rainfall infiltration and grid based regional slope stability analysis code trigrs a consolidated physically based numerical model that describes the stability instability conditions of natural slopes forced by rainfall to determine the frequency statistics of the area of the unstable slopes and the rainfall intensity i duration d conditions that result in landslides in a region we apply trigrs in a portion of the upper tiber river basin central italy the spatially distributed model predicts the stability instability conditions of individual grid cells given the local terrain and rainfall conditions we run trigrs using multiple synthetic rainfall histories and we compare the modeling results with empirical evidences of the area of landslides and of the rainfall conditions that have caused landslides in the study area our findings revealed that trigrs is capable of reproducing the frequency of the size of the patches of terrain predicted as unstable by the model which match the frequency size statistics of landslides in the study area and the mean rainfall d i conditions that result in unstable slopes in the study area which match rainfall i d thresholds for possible landslide occurrence our results are a step towards understanding the mechanisms that give rise to landslide scaling properties

quantitative mineralogy from infrared spectroscopic data i validation of mineral abundance and composition scripts at the rocklea channel iron deposit in western australia visible near to shortwave infrared reflectance spectra vnir swir 400 2 500 nm wavelength region provide quantitative measurements of mineral abundances and mineral physicochemistries from drill core samples of channel iron ore the infrared spectral reflectance measurements of drill core samples from the rocklea channel iron deposit located in the hamersley basin of western australia were validated against x ray flouresence xrf and x ray diffraction xrd the reflectance data were collected using a csiro hy logging system from 180 reverse circulation and 14 diamond drill cores spanning a depth from surface to 55 m below surface intersecting the rocklea deposit the mineralogy of this channel iron deposit comprises chiefly goethite both vitreous and ochreous forms with lesser amounts of hematite and variable amounts of quartz kaolinite smectite both dioctahedral and trioctahedral varieties and carbonate both dolomite and calcite iron ore and waste rock mineralogy were extracted from the infrared spectroscopic reflectance data using the geometry depth wavelength of continuum removed reflectance spectra with depths of absorption features proportional to mineral abundance and wavelength positions proportional to chemical composition for any one mineral a number of its diagnostic spectral features are used to determine its mineral abundance and composition in order to avoid complications with minerals that spectrally overlap with part of the diagnostic spectral features of the mineral of interest this method that combines multiple spectral features to identify and quantify minerals is transferable to all types of infrared reflectance spectroscopic data collected from drill core to satellites final products include iron oxyhydr oxide content root mean square error rmse 9 1 wt fe al clay content rmse 3 9 wt al 2 o 3 hematite goethite ratio rmse 9 0 wt goethite vitreous versus ochreous goethite not easily measured using other analytical techniques clay mineral type kaolinite montmorillonite and nontronite and carbonate composition dolomite vs calcite the rocklea infrared reflectance spectroscopy based mineral abundance and composition results have been used in an associated study to characterize the architecture of the rocklea channel iron deposit with implications for exploration mining and ore genesis

development of a coupled hydrological geotechnical framework for rainfall induced landslides prediction abstract in this paper we propose a new coupled hydrological geotechnical model called creslide c oupled r outing and e xcess storage and sl ope i nfiltration d istributed e quilibrium which can alleviate the chronic flaws of landslides simulation and prediction creslide is designed to improve the original landslides model slide through the coupling of hydrological model crest and to deliver an integrated system for predicting storm triggered landslides this coupled system is implemented and evaluated in macon county north carolina where hurricane ivan triggered widespread landslides in september 2004 during the hurricane season model simulations from creslide show its reliability to predict landslides occurrence location and timing receiver operating characteristic roc analysis demonstrates that the coupled system creslide has higher specificity 94 10 and higher sensitivity 11 36 compared to the original slide model specificity 93 32 sensitivity 10 23 and a well known landslide model trigrs whose sensitivity is 6 98 this improved predictive performance demonstrates the advantage of coupling hydrological and geotechnical models with a more realistic representation of infiltration it warrants a better depiction of the spatial and temporal dependence of hydrological and geotechnical processes in the course of the rainfall triggered landslide event this kind of model integration is useful for landslides prediction and early warning

factors controlling landslide frequency area distributions a power law relation for the frequency area distribution fad of medium and large landslides e g tens to millions of square meters has been observed by numerous authors but the fad of small landslides diverges from the power law distribution with a rollover point below which frequencies decrease for smaller landslides some studies conclude that this divergence is an artifact of unmapped small landslides due to lack of spatial or temporal resolution others posit that it is caused by the change in the underlying failure process an explanation for this dilemma is essential both to evaluate the factors controlling fads of landslides and power law scaling which is a crucial factor regarding both landscape evolution and landslide hazard assessment this study examines the fads of 45 earthquake induced landslide inventories from around the world in the context of the proposed explanations we show that each inventory probably involves some combination of the proposed explanations though not all explanations contribute to each case we propose an alternative explanation to understand the reason for the divergence from a power law we suggest that the geometry of a landslide at the time of mapping reflects not just one single movement but many including the propagation of numerous smaller landslides before and after the main failure because only the resulting combination of these landslides can be observed due to a lack of temporal resolution many smaller landslides are not taken into account in the inventory this reveals that the divergence from the power law is not necessarily attributed to the incompleteness of an inventory this conceptual model will need to be validated by ongoing observation and analysis also we show that because of the subjectivity of mapping procedures the total number of landslides and total landslide areas in inventories differ significantly and therefore the shapes of fads also differ considerably

relationship between rock physical properties and spectral mineralogy applied to exploration for an unconformity related uranium deposit saskatchewan canada infrared spectroscopy ir has been used to characterize clay and clay size minerals present in drill cores that are associated with unconformity related uranium deposits physical properties have

european impacts on downstream sediment transfer and bank erosion in cobargo catchment new south wales australia abstract upland valley fills in cobargo catchment on the south coast of new south wales represent substantial sediment source zones contemporary channels within these fills are up to 8 m deep and 50 m wide for catchment areas 2 virtually all banks are eroding downstream of this sediment source zone sediment transfer zones are characterised by sinuous channels that are partially choked by sands released from upland valley fills coarse sands stored in point bars deflect flow to outer banks where colluvial footslopes are eroded approximately 50 of banks are eroding in this section of the catchment other than the 10 km river reach upstream of the river mouth the remainder of the catchment is a bedrock confined sediment throughput zone characterised by fluctuations in channel bed elevation the downstream 10 km of the catchment is a sediment accumulation zone in which erosion is restricted to occasional concave banks prior to european settlement of cobargo catchment upland valley fills were largely unincised and middle transfer reaches of the catchment comprised swamps vegetation clearance along with disturbance and drainage of swamps transformed discontinuous water courses into continuous channels working from a base point of intact upland valley fills almost 50 of available material has been removed from the upper catchment sediment source zone contributing 2 9 10 6 m 3 of material to the lower catchment of this roughly 65 has been stored along the channel bed and floodplain this gives a total sediment contribution to the delta of 1 0 10 6 m 3 sufficient materials are stored in transient storage units along transfer zones to maintain current rates of sediment throughput to the delta for several decades cobargo catchment experienced dramatic acceleration of channel incision and bank erosion processes within a few decades following european settlement of the catchment i e around 1830 transition in landscape form and associated sediment delivery were rapid with a negligible lag interval i e within a few decades of disturbance however given the extensive volume of sediment released from upland valley fills landscape recovery i e refilling of upland valleys will likely take thousands of years

mineralogy composition and alteration of mars pathfinder rocks and soils evidence from multispectral elemental and magnetic data on terrestrial analogue snc meteorite and pathfinder samples major element multispectral and magnetic properties data were obtained at ares vallis during the mars pathfinder mission to understand the compositional mineralogical and process implications of these data we obtained major element mineralogical and magnetic data for well crystalline and nanophase ferric minerals terrestrial analogue samples with known geologic context and snc meteorites analogue samples include unaltered palagonitic and sulfatetic tephra from mauna kea volcano hydrolytic and acid sulfate alteration steam vent material from kilauea volcano hydrolytic alteration and impactites from meteor crater relithification salient results for mars pathfinder include 1 band depths bd530b and bd600 and the reflectivity ratio r800 r750 are consistent with the dominant ferric mineral being nanophase ferric oxide associated with an unknown amount of h2o and occurring in composite particles along with subordinate amounts of other ferric minerals hematite and hematite plus nanophase goethite are most consistent with the data but maghemite akaganeite schwertmannite and nanophase lepidocrocite are also possible interpretations ferric oxides that are consistently not favored by the data as sole alteration products are jarosites and well crystalline goethite and lepidocrocite 2 the strength of the ferric adsorption edge r750 r445 implies the fe3 fe2 values for pathfinder rock and soil are within the ranges 0 7 3 and 3 20 respectively 3 ferrous silicates are indicated for subsets of pathfinder rocks and soils one subset has a band minimum near 930 nm that can attributed to low ca pyroxene alternatively the band could be a second manifestation of certain ferric oxides including nanophase goethite maghemite akaganeite and schwertmannite another subset has a negative spectral slope from 800 to 1005 nm which could result from the high energy wing of a high ca pyroxene and or olivine band a mixture of bright and dark materials and for rocks thin coatings of bright dust on dark rocks 4 chemical data on pathfinder rocks and soils are consistent with two component mixtures between an andesitic rock with low mgo and so3 concentrations soil free rock and a global basaltic soil with high mgo and so3 concentrations rock free soil pathfinder rock free soil can be modeled as a chemical mixture of snc meteorites and the pathfinder soil free rock 5 pathfinder soil cannot be obtained by chemical alteration of pathfinder rocks by any of the hydrolytic and acid sulfate alteration processes we studied presumably global mixing has obscured and possibly erased the elemental signatures of chemical alteration 6 the strongly magnetic phase in palagonitic and sulfatetic tephra is titanomagnetite and possibly its oxidation product titanomaghemite fe ti spinels the saturation magnetization of the tephra samples 0 5 2 0 am2 kg is at or below the low end of the range inferred for martian dust 4 2 am2 kg implying that lithogenic fe ti spinels are a possible candidate for the martian strongly magnetic phase 7 the predominantly palagonitic spectral signature and magnetic nature of martian soil and dust are consistent with glassy precursors with imbedded fe ti spinel particles comparison with lunar glass production rates suggests that production of sufficient quantities of glassy materials on mars by volcanic and impact processes is sufficient to account for these observations

regional scale demarcation of alteration zone using aster imageries in south purulia shear zone east india implication for mineral exploration in vegetated regions abstract regional scale demarcation of alterations is an important preliminary step in mineral exploration advanced spaceborne thermal emission and reflection radiometer aster imageries here have been used for alteration mapping and iron rich e g gossans area demarcation in a highly vegetated and relatively unexplored part of eastern india namely south purulia shear zone spsz the area is surrounded by mineral rich singhbhum shear zone ssz but the mineral potentiality of spsz has not yet been proven alteration mineral assemblages are comprise of iron rich alteration gossan clay alteration with varying amounts of iron content sericitization ferruginization and chloritization in this paper we discuss a few advantages and limitations of commonly used satellite image processing techniques for mineral mapping we integrate the outputs of band ratio principal component analysis pca pca loading and thresholding termed as directed pca dpca for delineating mineral potential areas our approach mapped the alteration zones with overall 74 accuracy our study leads to demarcation of 28 alteration area within a 10 km wide and 60 km long stretch of spsz two areas namely lawa 23 1 39 31 n 86 4 2 55 e and sindurpur 23 4 38 30 n 86 5 3 99 e were identified as mineral potential zone samples from those areas were studied using xrf microscope and sem with the conclusive presence of mineralization lawa is potential for hydrothermal polymetallic sulfides along with gold mineralization sindurpur is potential for secondary iron and manganese mineralization the study shows that dpca is a useful tool for aster data processing for narrowing target area in preliminary stages of exploration in vegetated zones

disequilibrium of holocene sediment yield in glaciated british columbia it is generally supposed that specific sediment yield the quantity of sediment passing a monitored river cross section per unit area drained upstream of that section declines as the area drained increases1 3 part of the sediment mobilized from the land surface is supposed to go back into storage at field edges and on footslopes and floodplains in contrast we show here that data from british columbian rivers reveal a pattern of increasing specific sediment yield at all spatial scales up to 3 104 km2 this results from the dominance of secondary remobilization of quaternary sediments along river valleys over primary denudation of the land surface the result controverts the conventional model which has been derived from studies of small highly disturbed agricultural catch ments the rivers are still responding to the last glaciation giving a landscape relaxation time greater than 10 kyr this holds pro found implications for geomorphological theory and for studies of erosion

investigations of the cerro colorado pluton northern chile using enhanced landsat thematic mapper images digitally enhanced landsat thematic mapper tm images of the cerro colorado pluton northern chile were studied the bulk of the intrusion is magnetic rich and laboratory spectra of the fresh surfaces of field samples are severely quenched weathering and oxidation of the magnetite has reduced the quenching effects allowing features due to the primary mineralogy of the rock to be resolved in the spectra of the weathered surfaces and consequently on the enhanced imagery in most cases the weathering alters the overall albedo of the rock and it may introduce additional features into the rock spectra due to iron hydroxides and clay minerals as yet it does not seem to the author that tm data alone could be used for lithological mapping some control is necessary in the form of fieldwork or pre existing maps