stratigraphy and graptolites of the upper ordovician point leamington formation central newfoundland the point leamington formation as redefined herein comprises a thick sequence of siliciclastic turbidites containing occasional upper ordovician graptolites and lies with the exploits subzone of the dunnage zone in central newfoundland the base of the unit is marked by the first coarse to medium grained sandstone at a level that varies from the dicranograptus clingani zone to the pleurograptus linearis zone several intervals of interbedded black shales and siltstones higher in the formation yield assemblages characteristic of the p linearis dicellograptus complanatus and dicellograptus anceps zones debris flow breccias occur at several levels within the point leamington formation some contain graptolitic black shale clasts derived from the underlying lawrence harbour formation and range in age from nemagraptus gracilis zone to d clingani zone both the graptolite assemblages and lithostratigraphic succession of the point leamington formation are similar to those of coeval rocks in southern scot

carbon isotope excursions and sea level change implications for the frasnian famennian biotic crisis new carbon and oxygen isotope data from carbonates spanning the frasnian famennian f f boundary in the guilin area south china show a broad positive 13 c rise and fall with sharp short lived negative 13 c events this pattern is comparable to that in europe and north america the integration of the isotope stratigraphy with high resolution sequence stratigraphy corroborates the onset of the positive 13 c excursion during a third order sea level fall in the latest frasnian this can best be explained through increased burial of c org during the sea level fall brought about by increased organic productivity caused by increased continent derived nutrient flux to the ocean due to enhanced weathering through the proliferation of land plants in the devonian this scenario would have resulted in anoxic and eutrophic conditions over epicontinental seas and blooms of cyanobacteria creating a highly stressful and fragile ecosystem for oligotrophic normal marine benthic organisms and leading to their massive decline the global third order sea level fall near the end of the frasnian may have led to gas hydrate dissociation giving the negative 13 c events and caused wild climatic fluctuations the subsequent short term events of sea level rise anoxia and eutrophication in the latest part of the f f transition would have placed additional environmental stresses on the already weakened biota leading to their further demise

lower ordovician arenig llanvirn graptolites from the notre dame subzone central newfoundland many lower paleozoic rocks in the notre dame subzone of central newfoundland are of unknown or imprecise age several new lower ordovician graptolite occurrences are here reported and earlier records revised new graptolite localities in the balsam bud cove formation at snooks arm on the baie verte peninsula previously recorded as early ordovician arenig have yielded an assemblage identical to that found in the middle part of bed 11 of the cow head group western newfoundland indicating a probable lower didymograptus bifidus zone age at corner pond southeast of corner brook an abundant diverse fauna from the corner pond formation indicates a marginally older age for the black shales than those at snooks arm pendeograptus fruticosus zone equivalent to lower bed 11 black shales associated with felsic volcanics and limestone breccia belonging to the cutwell group at lushes bight on long island western notre dame bay which were previously assigned to the widespread black shales of the lawrenc

silurian deformation in eastern notre dame bay newfoundland eastern notre dame bay newfoundland is divided into five fault bounded terranes they are from north to south the twillingate terrane the chanceport terrane the new world island terrane the dildo run terrane and the port albert terrane the new world island terrane is characterized by fault repeated sequences of middle ordovician to early silurian turbiditic sandstones sansom formation and conglomerates goldson formation the chanceport terrane has a lower volcanic unit and an upper sedimentary unit consisting of red and green siltstones shales overlain by turdiditic sandstones this sequence is structurally overlain by a mafic and felsic volcanic unit the clastic sedimentary rocks of the chanceport new world island and port albert terranes best record the silurian deformation in the area silurian deformation is divided into two deformation events an early silurian d1 thrusting event and a late silurian d2 dextral ductile faulting event the early silurian joey s cove melange constrains th

post glacial loess deposition in a montane environment south thompson river valley british columbia canada in the late wisconsinan the south thompson river valley british columbia was occupied by an ice dammed lake after the lake drained the exposed lacustrine silt became the source material for a holocene loess the purpose of this paper is to establish the stratigraphic depositional and geomorphic framework of loess occurring along the south thompson river valley immediately east of kamloops british columbia this montane environment of loess deposition was characterised by active slope and fluvial processes depositing sediments contemporaneously with the accumulation of loess the loess reaches an average of 4 m in thickness in the central part of the valley and thins towards the valley sides two tephras mount st helens y 3 4 ka and mount mazama 6 8 ka occur in the loess and are invaluable stratigraphic markers most of the loess was probably deposited between 8 2 ka and 3 4 ka a period coinciding with mid holocene increased summer temperatures and decreased precipitation in south central british columbia debris flows and small streams originating on the valley sides flowed out on to the loess depositing sand and gravel beds these deposits form a definite proximal distal relation across valley with the slope derived sediments decreasing and the loess increasing in thickness towards the centre of the valley the lactustrine silt particles were mobilised by diurnal mountain and valley gravity and canalised winds flowing within the south thompson valley an analysis of contemporary wind flow data was undertaken to provide a possible analogue for valley wind flows in the mid holocene

a review of the western part of the altaids a key to understanding the architecture of accretionary orogens abstract the altaids is one of the largest accretionary collages in the world and the tectonic styles of the accretionary processes have been interpreted in several ways including as an amalgamation of multiple terranes as a result of oroclinal bending of a long single arc or as a caledonian continental collision based on recent tectonostratigraphic analyses together with paleomagnetic data the tectonic styles of the neoproterozoic to paleozoic accretionary processes of the altaids are discussed the western altaids is the main focus of the study which was mainly composed of several independent linear components such as arcs and microcontinents with proterozoic basement and cover rocks various kinds of arcs existed in the paleo asian ocean including a complicated type of arc alaskan type which is a combination of the japan and mariana type intra oceanic arcs and the cordillera type continental arcs these linear components rotated and collided with each other with multiple subduction polarities which could have been an important result of multiple linear element amalgamation and which has contributed greatly to the architecture of the eurasian continent the basic tectonic styles of the altaids can be summarized as arc arc collision oroclinal bending and large scale rotation and multiple subductions with a complicated archipelago paleogeography these basic features of accretionary orogens in general can be attributed to the amalgamation of complicated multiple linear elements some mesozoic to cenozoic accretionary orogens in the world are also characterized by processes of multiple linear element amalgamation more attention should be paid to the multiple linear element amalgamation of ancient accretionary orogens which will shed light on lateral and vertical continental growth

mechanisms of shallow landslides on soil mantled hillslopes with permeable and impermeable bedrocks in the boso peninsula japan abstract rainfall induced shallow landslides play a vital role in hillslope denudation processes in humid temperate regions this study demonstrates the contrasting mechanisms of landslides in adjoining hills with permeable sandstone and impermeable mudstone bedrock in the boso peninsula japan the characteristics of slope hydrology were inferred from pressure head monitoring and rainfall runoff observations an analysis of slope stability provided critical conditions for several previously occurring landslides the results are as follows 1 in slopes with the permeable sandstone infiltrated rainwater percolates through the bedrock as an unsaturated gravitational flow the wetting front migration results in a decrease of soil cohesion and causes landsliding at the steep lower part of the hillslopes 2 in contrast the impermeable mudstone beneath a thin soil layer causes a transient positive pressure head that generates a saturated subsurface storm flow the reduction in effective normal stress triggers shallow soil slipping at the uppermost part of a hollow

shear wave velocity imaging of the avignonet landslide france using ambient noise cross correlation 1 the avignonet landslide affects a 2 by 2 km area covered by clayey deposits this paper presents the use of the seismic ambient noise cross correlation technique to retrieve a 3 d model of the shear wave velocity of the area seismic ambient noise was recorded during 15 days at 13 stations located on the landslide cross correlations computed between the vertical components of all station pairs allow the retrieval of the rayleigh wave green s functions and the estimation of their group velocity dispersion curves in the 1 7 5 hz frequency range at frequencies lower than 1 5 hz the anisotropy of the wavefield strongly influences the apparent rayleigh wave velocities moreover the analysis of the convergence of the cross correlations shows that at frequencies higher than 5 hz the recording time length was not sufficient for the cross correlation to be stable these 1 7 5 hz passive group dispersion curves are complementary to the ones computed from shot signals in the 3 7 hz frequency range a tomographic inversion of the resulting 1 7 7 hz rayleigh wave group dispersion curves provides local group dispersion curves at each cell of the tomographic grid these are inverted with a neighborhood algorithm to retrieve the 3 d model of the landslide despite the complex wave propagation in the eastern part of the landslide and the sparse ray coverage estimated velocities and first order features are in good agreement with previous investigations

carbon isotope geochemistry of the frasnian famennian transition abstract carbon isotope records for inorganic and total organic carbon toc as well as for individual organic biomarkers show two positive excursions in the late frasnian with comparable shape and amplitude in 13c the positive shifts in 13c can be correlated with the deposition of the kellwasser horizons the inorganic carbon isotope excursions are explained by an enhanced organic carbon burial that is expected to lower the concentration of oceanic dissolved co2 toc 13c values do not exhibit a larger shift than that recorded by inorganic carbon 13c values this is unexpected since a decrease in the dissolved co2 concentration should result in lower carbon isotope fractionation during photosynthesis ep 13c values of presumed algal biomarkers low molecular weight n alkanes pristane phytane although offset by 2 5 exhibit essentially identical records as toc and confirm this unexpected result it is proposed that high atmospheric and oceanic co2 concentrations during the devonian resulted in maximum photosynthetic fractionation any change in the co2 concentration would thus not affect ep as such 13c of primary organic carbon and 13ccarb will exhibit parallel excursions the data imply that carbon isotopes and the relationship between ep and co2 will not be effective to study changes in pco2 levels during the devonian since co2 concentrations were too high

a combined hillslope hydrology stability model for low gradient clay slopes in the italian dolomites abstract the temporal trend of displacement of a landslide on a low gradient clay slope in the italian dolomites as a function of precipitation was simulated with a combined hydrological slope stability model based on groundwater and surficial displacement observations piezometric records and lithological profiles from boreholes suggest the occurrence of preferential groundwater flow through a very permeable top layer of about 1 m thickness which overlies a less permeable compact clay layer penetrated by dead end cracks to simulate groundwater levels in this system a linear reservoir model with two outlets was applied where the upper outlet drains the permeable top layer and the lower outlet drains the dead end cracks in the clay layer the reservoir was assigned a bottom boundary level varying in time this was done to represent an inferred yearly fluctuation of a matric groundwater level due to regional flow which controls the thickness of the unsaturated part of the clay layer absorbing water from the cracks groundwater output from the model was used in a visco plastic stability model to simulate the velocity of landslide movement taking into account a phenomenon of strength regain that occurs in the clays along the slip surfaces calibration and validation on 3 years of groundwater and displacement data showed that both models yield good results thus good estimates of cumulative landslide displacement were obtained as a function of precipitation the general concepts underlying the models offer possibilities for regionalization because from a geological point of view this landslide is typical of many others in the dolomites

triggering mechanism and reactivation probability of loess mudstone landslides induced by rainfall infiltration a case study in qinghai province northwestern china rainfall especially rainstorm is a major factor in inducing loess mudstone landslides and plays an essential role in landslide reactivation the aim of the paper is to study the triggering mechanism and reactivation probability of a loess mudstone landslide induced by rainfall infiltration in qinghai province northwestern china according to the numerical model of elastic plastic mechanics the triggering mechanism of loess mudstone landslides was revealed then the reactivation probability of the potential landslide was evaluated by the combination of the limit equilibrium and monte carlo methods for one thing the relationship between water content and shear strength of media was analyzed based on the mechanical test of materials for another the effects of rainfall conditions were analyzed on the distribution of water content in the aerated zone with the two dimensional coupling model of unsaturated saturated seepage the results show that the shear strength of media is very sensitive to water content because of water rock interaction including hydration and dissolution besides the water content significantly increases at the interface between the loess and mudstone after the rainstorm occurring owing to the permeability heterogeneous of media and topographic feature which leads to the strength deterioration although the whole landslide is stable in the rainstorm conditions its middle part can be reactivated along the original sliding zone with high probability by a geomechanical model of sliding tension therefore the landslide reactivation is controlled by the water sensitivity of media the permeability heterogeneous of media the topographic feature and the original sliding zone especially the original sliding zone this research provides a valuable reference for the occurrence and reactivation of similar landslides

the frasnian famennian boundary interval in the south polish moravian shelf basins integrated event stratigraphical approach abstract the late devonian mass extinction event near the frasnian famennian f f boundary has been analysed using conodont biostratigraphy and biofacies sedimentology magnetic susceptibility and geochemistry in reference sections of the south polish moravian shelf holy cross mountains cracow and brno areas high resolution biostratigraphic study revealed difficulties in the precise recognition of this natural stage boundary but confirmed the occurrence of a major third order sequence boundary in the f f transition in an active synsedimentary tectonic setting marked by erosional discontinuities hardgrounds and brecciation or omission surfaces conclusive evidence of an extraterrestrial impact has not been found among earth bound factors the main devastating role in the shelf habitats is ascribed to fluctuating anoxia and or nutrient dynamics in a disturbed greenhouse climatic setting the long term facies changes were determined by a conspicuous break in carbonate production accompanied by replacement of mature stromatoporoid coral reefs by pioneer shelly crinoid banks microbial mounds and localised oolitic bars the key f f passage interval was marked by intermittent but generally accelerated periplatform ooze debris input and severe storm events as well as by probably highly fluctuating oxygenation and biological overproduction best manifested in radiolarian silicisponge and cephalopod acmes eutrophication phenomena at least partly stimulated by various hydrothermal and volcanic processes were one of the major biogeochemical processes during this climax of the late devonian biotic crisis however significant oceanographic perturbations were also linked with the onset of the transgressive hypoxic upper kellwasser event still within the latest frasnian linguiformis zone i e well before the f f conodont collapse implied variations in the redox state of seawater through the kellwasser timespan probably in regionally highly variable temporal scales are in agreement with recent palaeoecological and biogeochemical inferences in particular suggesting recovering oxygenation just prior to the f f boundary in the other laurussian intrashelf basins all the data support a long time multicausal earth bound crisis instead a worldwide cosmic catastrophe

observation guided constitutive modelling for creeping landslides creeping landslides are common in mountainous areas causing significant damage to buildings and infrastructure the major difficulty in modelling of these landslides is the inability of laboratory tests to reproduce adequately the macro behaviour in the creeping soil masses the proposed approach of observation guided constitutive modelling addresses this issue by considering a creeping landslide as a series of macro elements where monitoring of displacements and pore water pressures allows the derivation of suitable constitutive models and their parameters the paper proposes three generalised models describing the behaviour of pore water pressures sliding layer and slip surface which can be adapted to fit the observational data the three models are integrated into the boundary value problem the solution of which helps to explain the evolution of the landslide and to predict its future behaviour using probabilistic approaches when applied to the st moritz brattas landslide in switzerland the calibrated landslide models proved to be successful in describing the complex behaviour of all three distinctive regions of the landslide the paper also explores possible ways for predicting the landslide reaction to extreme rains and forecasting the long term displacement evolution in the vicinity of the leaning tower of st moritz which will be critical for planning its future stabilisation

wet sediment deformation in the upper ordovician point leamington formation an active thrust imbricate system during sedimentation notre dame bay north central newfoundland

magnetite dissolution diachronous greigite formation and secondary magnetizations from pyrite oxidation unravelling complex magnetizations in neogene marine sediments from new zealand detailed rock magnetic and electron microscope analyses indicate that the magnetic signature of neogene marine sediments from the east coast of new zealand is dominated by the authigenic iron sulphide greigite the greigite is present as a mixed population of stable single domain and superparamagnetic grains which is consistent with authigenic growth from solution this growth can result from pyritization reactions soon after deposition which also leads to dissolution of most detrital magnetite however where constrained by field tests our data suggest that remanence acquisition can occur 1 myr after deposition and can vary in timing at the outcrop scale strong viscous overprints result from oxidation of the iron sulphides probably during percolation of oxic ground water this process can sometimes destroy any ancient remanent magnetization this complex magnetic behaviour particularly the presence of late forming magnetizations carried by greigite means that the remanence in new zealand cenozoic sediments and in similar sediments elsewhere cannot be assumed to be primary without confirmation by field tests the reversals test should be employed with caution in such sediments as patchy remagnetizations can lead to false polarity stratigraphies

geophysical investigation of a large landslide in glaciolacustrine clays in the trieves area french alps abstract slope movements in clay deposits are spread all over the world and result from complex deformation processes including internal strains in the landslide body and slipping along rupture surfaces such mass movements are likely to generate changes in the geophysical parameters characterizing the ground which can be used to map the landslide body in the last decade geophysical techniques have been increasingly used for landslide investigation purposes however the success of any geophysical technique is overall controlled by the existence of a geophysical contrast differentiating the body to be mapped for landslides affecting thick clay materials from soft clay to shale or marl electrical and seismic techniques have been mainly applied in the past in this study we attempt to physically characterize the deformation within a large slide avignonet affecting laminated clays which were deposited in a glacially dammed lake during the wurm period clay deposits which cover an area of 300 km2 south of grenoble french alps and have a maximum thickness of 200 m overlay compact alluvial layers and marly limestone of mesozoic age piezometric data at avignonet show that the water table is very shallow implying that the slide developed in saturated clay several seismic and electrical profiles were performed in order to tentatively correlate the variations of p wave vp velocity s wave velocity vs and electrical resistivity with geotechnical data and morphological observations in such saturated and fine material it turned out that only the s wave velocity exhibits significant variations with the displacement rates and the morphological features vs values at shallow depth were found to be inversely correlated with displacement rates measured by gps with a division by at least a factor of 2 between the zones unaffected and strongly deformed by the landslide these results suggest that vs mapping could provide valuable information on the deformation state of the clay material and that the evolution of vs with time could be used as an indicator for characterizing the landslide activity in the subsurface including the evolution into a flow

a view on some hydrological triggering systems in landslides abstract in this paper different types of hydrological triggering systems for debris flows shallow and deeper landslides are described the generation of surface run off and high peak discharges in first order alpine catchments is an important triggering mechanism for debris flows failure conditions in shallow landslides can occur when at a critical depth which is determined by the cohesion of the soil and the slope angle the moisture content in the soil becomes close to saturation resulting in a considerable reduction of soil strength deeper landslides 5 20 m depth are in most cases triggered by positive pore pressures on the slip plane induced by a rising ground water level the assessment of meteorological threshold conditions for shallow landslides 1 2 m needs more detailed meteorological information than for deeper landslides in the analyses of the hydrological triggering systems of deeper landslides the presence of a permeable top layer and fissures has to be taken into consideration

hydrological triggering conditions of landslides in varved clays in the french alps abstract in this paper the meteorological and hydrological conditions are analyzed which trigger shallow and deeper landslides in glacio lacustrine deposits varved or laminated clays in the french alps the hydrological system of these landslides consists of a colluvial cover which supplies water into the fissures of the underlying varved clays from these fissures water can infiltrate more or less horizontally into the silt layers of the varved clays a combined reservoirs model was used to simulate the water fluctuations in the colluvial cover and the fissures both the water level in the fissures and the residence time of water in the fissures are mainly controlled by the amount of water storage in the colluvial cover simulations over the last 25 years show that almost each year the fissures are completely filled with water for several months a year infiltration experiments in the field show that infiltration into the varved clays occurs mainly by horizontal infiltration into the silt laminae calculated infiltration rates from these fissures into the silt layers show that the mean yearly residence time of water in the fissures is not sufficient to fully saturate the clay mass each year it is therefore concluded that the triggering of the landslide movements is mainly controlled by the development of positive pore water pressures in the fissure system and that the rise of pore water pressures induced by the matrix system of the varved clays only plays a minor role the calculations also show that drainage of the colluvial cover is a very efficient measure to stabilize the deeper landslides

on the reactivation of a large landslide induced by rainfall in highly fissured clays abstract the paper discusses the field investigations geotechnical characterization and time evolution of horizontal displacements in a wide landslide the latter triggered by an earthquake occurring in september 2002 is located in sicily and involves a thick body of stiff and highly fissured clays belonging to a varicoloured clay formation in order to characterise the reactivation of landslide mechanisms induced by rainfall a three year monitoring programme 2008 2011 was implemented to measure rain pore water pressures and deep and superficial displacements the monitoring data made it possible to recognize three distinct landslides which evolve at variable rates in different directions within the overall landslide area the landslides were reactivated by the increase in pore water pressures in the period autumn 2009 spring 2010 the data clearly show the mechanical role of pore water pressures in the stability of the slope and point out the dependence of the time evolution of the horizontal displacement on the pore water pressure variation induced by rainfall back analysis carried out on the single landslides confirmed that they are reactivated ones since the residual shear strength is mobilised on the pre existing sliding surfaces the pore water pressure variation and the landslide body displacement rates can be effectively related to 5 month cumulative rainfall by simple models characterised by three parameters these models calibrated on the period october 2009 september 2010 made it possible to predict the horizontal displacement rates in the ensuing time period the displacements forecasted by the model in the period september 2010 may 2011 agree very well with the measured ones

mo total organic carbon covariation in modern anoxic marine environments implications for analysis of paleoredox and paleohydrographic conditions 1 sedimentary molybdenum mo s has been widely used as a proxy for benthic redox potential owing to its generally strong enrichment in organic rich marine facies deposited under oxygen depleted conditions a detailed analysis of mo s total organic carbon toc covariation in modern anoxic marine environments and its relationship to ambient water chemistry suggests that 1 mo s while useful in distinguishing oxic from anoxic facies is not related in a simple manner to dissolved sulfide concentrations within euxinic environments and 2 patterns of mo s toc covariation can provide information about paleohydrographic conditions especially the degree of restriction of the subchemoclinal water mass and temporal changes thereof related to deepwater renewal these inferences are based on data from four anoxic silled basins the black sea framvaren fjord cariaco basin and saanich inlet and one upwelling zone the namibian shelf representing a spectrum of aqueous chemical conditions related to water mass restriction in the silled basin environments increasing restriction is correlated with a systematic decrease in mo s toc ratios from 45 5 for saanich inlet to 4 5 1 for the black sea this variation reflects control of mo s by mo aq which becomes depleted in stagnant basins through removal to the sediment without adequate resupply by deepwater renewal the basin reservoir effect the temporal dynamics of this process are revealed by high resolution chemostratigraphic data from framvaren fjord and cariaco basin sediment cores which exhibit long term trends toward lower mo s toc ratios following development of water column stratification and deepwater anoxia mo burial fluxes peak in weakly sulfidic environments such as saanich inlet owing to a combination of greater mo aq availability and enhanced mo transport to the sediment water interface via fe mn redox cycling and are lower in strongly sulfidic environments such as the black sea and framvaren fjord these observations demonstrate that at timescales associated with deepwater renewal in anoxic silled basins decreased sedimentary mo concentrations and burial fluxes are associated with lower benthic redox potentials i e more sulfidic conditions these conclusions apply only to anoxic marine environments exhibiting some degree of water mass restriction e g silled basins and are not valid for low oxygen facies in open marine settings such as continent margin upwelling systems

paleoredox variations in ancient oceans recorded by rare earth elements in fossil apatite abstract rare earth element concentrations in biogenic apatite of conodonts fish debris and inarticulate brachiopods were determined in over 200 samples from cambrian to modern sediments tests for experimental bias caused by the chemicals used to separate fossils from the rock matrix and for interlaboratory interexperiment or interspecies related variations clearly show that no resolvable fractionation of ree occurs incorporation of ree in biogenic apatite of recent fish debris occurs near the sediment water interface soon after deposition and reflects characteristics of seawater the original ree signature apparently survives subsequent burial and diagenesis cerium variations in fish debris from modern environments are controlled by redox potential ce is fractionated by co precipitation with metallic oxides under oxidizing conditions this fractionation produces a negative ce anomaly ce anom in seawater that is reflected in the sedimented fish debris conversely no fractionation of ce occurs under reducing conditions resulting in ce concentrations that are normal to enriched in anoxic seawater and fish debris deposited under local or basinwide anoxic conditions extrapolation of observations of the redox control of ce anom in modern oceans to fossil apatite indicates that anoxic conditions were prevalent in lower paleozoic and lower triassic oceans whereas in the upper paleozoic the world ocean was generally oxidizing

space time landslide predictive modelling abstract landslides are nearly ubiquitous phenomena and pose severe threats to people properties and the environment in many areas investigators have for long attempted to estimate landslide hazard in an effort to determine where when or how frequently and how large or how destructive landslides are expected to be in an area this information may prove useful to design landslide mitigation strategies and to reduce landslide risk and societal and economic losses in the geomorphology literature most of the attempts at predicting the occurrence of populations of landslides by adopting statistical approaches are based on the empirical observation that landslides occur as a result of multiple interacting conditioning and triggering factors based on this observation and under the assumption that at the spatial and temporal scales of our investigation individual landslides are discrete point events in the landscape we propose a bayesian modelling framework for the prediction of the spatio temporal occurrence of landslides of the slide type caused by weather triggers we build our modelling effort on a log gaussian cox process lgcp by assuming that individual landslides in an area are the result of a point process described by an unknown intensity function the modelling framework has two stochastic components i a poisson component which models the observed random landslide count in each terrain subdivision for a given landslide intensity i e the expected number of landslides per terrain subdivision which may be transformed into a corresponding landslide susceptibility and ii a gaussian component used to account for the spatial distribution of the local environmental conditions that influence landslide occurrence and for the spatio temporal distribution of unobserved latent environmental controls on landslide occurrence we tested our prediction framework in the collazzone area umbria central italy for which a detailed multi temporal landslide inventory covering the period from before 1941 to 2014 is available together with lithological and bedding data we subdivided the 79 km2 area into 889 slope units sus in each su we computed the mean and standard deviation of 16 morphometric covariates derived from a 10 m 10 m digital elevation model for 13 lithological and bedding attitude covariates obtained from a 1 10 000 scale geological map we computed the proportion of each thematic class intersecting the given su we further counted how many of the 3 379 landslides in the multi temporal inventory affect each su and grouped them into six periods we used this complex space time information to prepare five models of increasing complexity our baseline model mod1 carries the spatial information only through the covariates mentioned above it does not include any additional information about the spatial and temporal structure of the data and it is therefore equivalent to the predominantly used landslide susceptibility model in the literature the second model mod2 is analogous but it allows for time interval specific regression constants our next two models are more complex in particular our third model mod3 also accounts for latent spatial dependencies among neighboring sus these are inferred for each of the six time intervals to explain variations in the landslide intensity and susceptibility not explained by the thematic covariates by contrast our fourth model mod4 accounts for the latent temporal dependence separately for each su disregarding neighboring influences ultimately our most complex model mod5 contextually features all these relations it contains the information carried by morphometric and thematic covariates six time interval specific regression constants and it also accounts for the latent temporal effects between consecutive slope instabilities at specific sus as well as the latent spatial effects between adjacent sus we also show that the intensity is strongly related to the aggregated landslide area per su because of this our most complex model largely fulfills the definition of landslide hazard commonly accepted in the literature at least for this study area we quantified the spatial predictive performance of each of the five models using a 10 fold cross validation procedure and the temporal predictive performance using a leave one out cross validation procedure we found that mod5 performed better than the others we then used it to test a novel strategy to classify the model results in terms of both landslide intensity and susceptibility which provides more information than traditional susceptibility zonations for land planning and management hereafter we use the term traditional simply to refer to the majority of modelling procedures in the literature we discuss the advantages and limitations of the new modelling framework and its potential application in other areas making specific and general hazard and geomorphological considerations we also give a perspective on possible developments in landslide prediction modelling and zoning we expect our novel approach to the spatio temporal prediction of landslides to enhance the currently limited ability to evaluate landslide hazard and its temporal and spatial variations we further expect it to lead to better projections of future landslides and to improve our collective understanding of the evolution of complex landscapes dominated by mass wasting processes under multiple geophysical and weather triggers

mechanism and failure process of qianjiangping landslide in the three gorges reservoir china the qianjiangping landslide is a large planar rock slide which occurred in july 14 2003 shortly after the water level reached 135 m in the three gorges reservoir china the landslide destroyed 4 factories and 129 houses took 24 lives and made 1 200 people homeless field investigation shows that the contributing factors for the landslide are the geological structure of the slope the previous surface of rupture the water level rise and continuous rainfall in order to reveal the mechanism and failure process of the landslide numerical simulation was conducted on qianjiangping slope before sliding based on the characteristics and the engineering conditions of the landslide the topography and the geological profiles of qianjiangping slope before sliding is reconstructed the seepage field of qianjiangping slope before sliding was simulated with the geostudio software the results show that ground water table rises and bends to the slope during the rise of water level and the slope surface becomes partially saturated within the period of continuous rainfall using the ground water table obtained above the failure process of qianjiangping slope is simulated with the flac3d software the results demonstrate that the shear strain increment displacement and shear failure area of the slope increased greatly after the water level rose and continuous rained and the landslide was triggered by the combined effect both of water level rise and continuous rainfall the development of shear strain increment displacement and shear failure area of the slope shows that the landslide was retrogressive in the lower part of the slope and progressive in the upper part of the slope

diagenetic origin of quartz silt in mudstones and implications for silica cycling mudstone the most abundant sedimentary rock type1 composed primarily of clay or silt sized particles contains most of the quartz found in sedimentary rocks2 these quartz grains which are chemically and mechanically resistant and therefore preserve their characteristics well have long been considered to be derived from the continental crust1 here we analyse quartz silt from black shales in the eastern usa dating back to the late devonian period about 370 million years ago using backscattered electron and cathodoluminescence imaging and measure oxygen isotopes with an ion probe our results indicate that up to 100 of the quartz silt in our samples does not originate from the continental crust instead it appears to have precipitated early in diagenesis in algal cysts and other pore spaces3 with silica derived from the dissolution of opaline skeletons of planktonic organisms such as radiolaria and diatoms transformation of early diatoms into in situ quartz silt might explain the time gap between the earliest fossil occurrences of diatoms about 120 myr ago4 and molecular evidence for a much earlier appearance between 266 or even 500 myr ago5 6 moreover if many other mudstone successions show similarly high proportions of in situ precipitated rather than detrital quartz silt the sedimentary record in mudstones may have been misinterpreted in the past with consequences for our estimates of palaeoproductivity as well as our perceptions of the dynamics and magnitude of global biogeochemical cycling of silica

application of geophysical measurements for assessing the role of fissures in water infiltration within a clay landslide trieves area french alps rainfall and its consequences are usually considered as the major factor triggering slope instabilities within clay deposits the link between rainfall water infiltration and landslide activity may be complex and comprehensive sets of data are still necessary to understand how water infiltrates in cohesive material on unstable slopes made of fine grained sediments gravitational deformation generates superficial shear ruptures and tension fissures whose continuous opening could be amplified by shrinkage during dry periods this fissure network at the surface can be very dense and strongly controls the water infiltration process however it remains difficult to assess the fissure evolution at depth and its eventual relationship with shallow slip surfaces this work presents the results of a geophysical study which aimed to characterize the fissures that are observed along the unstable clay slopes of the trieves area french alps the site was first investigated combining geomorphological analysis drilling borehole logging geotechnical tests and geophysical experiments this investigation evidenced the presence of at least three rupture surfaces at 5 10 15 and 42 m with a water flow at the second one in a second step permanent instruments were installed piezometers and soil water content probes results indicate high water infiltration velocities down to the water table located at 2 5 m depth that are likely to be linked with sub vertical preferential paths such as fissures geophysical parameters electrical resistivity s wave velocities and rayleigh waves attenuation were monitored geophysical results suggest that fissures are permanently open that they serve as preferential infiltration paths and that they can reach at least a depth of 2 m the methods employed in this research put forward that the system of imbricated fissures drains water from the surface down to the shallow slip surfaces at 5 and 10 15 m this work highlights the role of fissures network in water infiltration in the numerous clay landslides of the trieves area copyright 2011 john wiley sons ltd

phreatic line calculation and stability analysis of slopes under the combined effect of reservoir water level fluctuations and rainfall rainfall and reservoir water level fluctuations are the main external factors of landslides in the three gorges reservoir area to improve the analysis of slope stability under the combined effect

a new model for the kellwasser anoxia events late devonian shallow water anoxia in an open oceanic setting in the central asian orogenic belt the frasnian famennian mass extinction event devastated tropical marine ecosystems and ranks in the top six in taxonomic and ecological severity the close stratigraphic association between the extinction and the kellwasser anoxia events support a link between oceanographic anoxia and extinction the upper and lower kellwasser horizons have been identified in epicontinental and basinal settings in laurussia gondwana siberia and south china the hongguleleng formation late devonian in northwestern xinjiang china contains both the frasnian famennian boundary and the rebound from the frasnian famennian extinction event in a highly fossiliferous shallow marine setting associated with a devonian oceanic island arc complex part of the central asian orogenic belt or caob here we show that the hongguleleng formation also records the upper kellwasser anoxia event through analysis of multiple geochemical proxies in contrast to previous studies asserting that the kellwasser events were restricted to epicontinental seaways and basins our results indicate that it occurred not only along the shallow continental margins of the closing rheic ocean but also in shallow water in the open oceanic part of paleotethys previous explanations for the kellwasser events from epicontinental margins and basins call for the migration of deep anoxic bottom water into shallow water environments as a kill mechanism for shallow marine ecosystems or attribute it to sea level rise and subsequent stagnation there is no evidence that the devonian oceans completely overturned during the kellwasser events similarly many transgressive events in the devonian are not associated with black shales we therefore suggest an alternative mechanism for the kellwasser events based on new evidence from the caob where anoxia is driven by episodic eutrophication of surface waters

detrital modes of the riding island graywacke north central newfoundland evidence for deposition in a collisional successor basin in the dunnage zone the riding island graywacke late caradoc ashgill crops out in notre dame bay north central newfoundland previous tectonic interpretations suggest that this succession of turbidites and hemipelagic mudstone accumulated in a basin adjacent to an active volcanic arc the varied framework mineralogy of 29 riding island samples studied however records derivation from a complex source terrane composed of mafic and silicic volcanic rocks sedimentary and metamorphic successions and plutonic rocks assessment of the tectonic environment of deposition of the riding island graywacke by use of popular sandstone provenance ternary diagrams yields ambiguous results the mineralogy of the riding island samples reveals a change in tectonic scenario from one dominated by island arc volcanism in pre caradoc time to a setting marked by tectonic shortening transcurrent faulting and terrane accretion near the end of the ordovician the complex composition of these sandstones and the fact that they accumulated afte

middle to upper ordovician graptolite biostratigraphy of peel river and other areas of the northern canadian cordillera middle to upper ordovician darriwilian to bolindian graptolite zones of the northern canadian cordillera comprise the following glyptograptus euglyphus zone of late darriwilian llandeilo age nemagraptus gracilis zone of early gisbornian late llandeilo and earliest caradoc age climacograptus bicornis and dicranograptus clingani zones of early to mid gisbornian early to mid caradoc age orthograptus quadrimucronatus zone of eastonian late caradoc age and dicellograptus ornatus zone of bolindian ashgill age a prominent biostratigraphic break equivalent to the spiniferus to hians kirki zones eastonian is shown to exist between the clingani zone and the overlying quadrimucronatus zone thirty eight common and or important species are illustrated of which one new species orthograptus expansus n sp is described and figured

application of a two step cluster analysis and the apriori algorithm to classify the deformation states of two typical colluvial landslides in the three gorges china several extensive landslides have occurred in the vicinity of the three gorges reservoir since its initial impoundment in june 2003 a reduction of the landslide risk is essential for the safety and security of lives and property in the region this study analyses the deformation states of two typical colluvial landslides the baijiabao and laoshewo landslides using 6 years of monitoring data a two step cluster analysis and the apriori algorithm the landslide displacement versus time curves exhibit step like patterns and the landslide deformation is highly correlated with fluctuations in the reservoir level and seasonal precipitation to determine different types of landslide deformation the monthly displacement curves of the colluvial landslides are classified into three types using a two step cluster analysis initial deformation constant deformation and rapid deformation five driving factors were selected as the antecedents for the apriori algorithm to obtain rules that describe the relationships between the landslide deformation and the influential parameters these factors include the cumulative precipitation over the previous month the maximum daily precipitation during the current month changes in the reservoir level over the previous month cumulative increases in the reservoir level and the average reservoir level during the current month the analytical results were validated by comparing them with observed landslide deformation characteristics using three measurement standards support confidence and lift the results show that the combined method of a two step cluster analysis with the apriori algorithm can effectively model the landslide deformation states that are associated with the baijiabao and laoshewo landslides moreover this method may serve as a potential reference for deformation analyses of colluvial landslides in the three gorges

an engineering site investigation using non invasive geophysical approach subsurface geological formation is essential to validate design assumptions for the construction of deep engineering structures especially in the weathered terrains the geological formation can be delineated using resistivity values through an electrical survey however the subsurface resistivity alone is ambiguous to interpret the subsurface geological units as part of an ongoing investigation to select the key methods towards this end an integrated geophysical survey through a combination of electrical resistivity tomography ert induced polarization ip magnetic method and joint profile method jpm was carried out in a weathered terrain of south huizhou china resistivity ip and magnetic data were obtained using a variety of survey parameters subsurface resistivity was calibrated with upfront boreholes lithology to constrain geological formation into four discrete layers such as topsoil cover with resistivity 2 3257 m highly weathered layer having resistivity 2 636 m partly weathered layer with resistivity range 448 1204 m and unweathered bedrock having resistivity 791 116 497 m the integration of ert with ip magnetic and jpm delineated four faults namely f1 f2 f3 and f4 and several localized fractures the weathered layer fractures and faults were marked as the weakest zones for engineering projects whereas the unweathered fresh bedrocks were identified as the most appropriate locations for the construction of deep structures in the study area the weakest zones unsuitable for engineering structures were delineated as the most appropriate places of groundwater occurrence in the studied area revealed by low resistivity ranging from 2 to 1204 m and overlapped by low chargeability less than 14 8 ms this non invasive geophysical approach suggests the most suitable locations highly significant not only for the future construction of engineering structures but also the exploitation of groundwater resources in the investigated area

stratigraphy and facies development of the marine late devonian near the boulongour reservoir northwest xinjiang china late devonian to early carboniferous stratigraphic units within the zhulumute formation honggulelengformation stratotype hebukehe formation and the heishantou formation near the boulongourreservoir in northwestern xinjiang are fossil rich the hongguleleng and hebukehe formations are biostratigraphicallywell constrained by microfossils from the latest frasnian linguiformis to mid famenniantrachytera conodont biozones the hongguleleng formation 96 8 m is characterized by bioclastic argillaceouslimestones and marls the dominant facies intercalated with green spiculitic calcareous shales ityields abundant and highly diverse faunas of bryozoans brachiopods and crinoids with subordinatesolitary rugose corals ostracods trilobites conodonts and other fish teeth the succeeding hebukehe formation 95 7 m consists of siltstones mudstones arenites and intervals of bioclastic limestone e g blastoid hill and cherts with radiolarians a diverse ichnofauna phacopid trilobites echinoderms crinoids and blastoids together with brachiopods ostracods bryozoans and rare cephalopods have beencollected from this interval analysis of geochemical data microfacies and especially the distribution ofmarine organisms which are not described in detail here but used for facies analysis indicate a deepeningof the depositional environment at the boulongour reservoir section results presented here concernmainly the sedimentological and stratigraphical context of the investigated section additionally onelate devonian palaeo oceanic and biotic event the upper kellwasser event is recognized near the sectionbase

silurian llandovery graptolites from the bay of exploits north central newfoundland and their geological significance only one specimen of a silurian graptolite has ever been recorded from newfoundland and it was not identifiable below generic level the graptolite assemblage discussed and figured here from a sequence of turbidites on upper black island north central newfoundland includes the first positively identified silurian taxa from the province and provides the first unequivocal evidence of silurian oceanic sedimentation in the dunnage zone the graptolite taxa include rastrites peregrinus barrande coronograptus sp cf c gregarius lapworth monograptus austerus sequens hutt orthograptus insectiformis nicholson monograptus spp indet climacograptus sp and glyptograptus sp this assemblage demonstrates that the strata previously assigned to the middle ordovician lawrence harbour formation are actually aeronian middle llandovery in age and that the turbidites considerably postdate both the lawrence harbour and point leamington formations of the exploits subzone furthermore the graptoli