evidence for proterozoic and late cretaceous early tertiary ore forming events in the coeur d alene district idaho and montana discussion

impacts of age dependent tree sensitivity and dating approaches on dendrogeomorphic time series of landslides different approaches and thresholds have been utilized in the past to date landslides with growth ring series of disturbed trees past work was mostly based on conifer species because of their well defined ring boundaries and the easy identification of compression wood after stem tilting more recently work has been expanded to include broad leaved trees which are thought to produce less and less evident reactions after landsliding this contribution reviews recent progress made in dendrogeomorphic landslide analysis and introduces a new approach in which landslides are dated via ring eccentricity formed after tilting we compare results of this new and the more conventional approaches in addition the paper also addresses tree sensitivity to landslide disturbance as a function of tree age and trunk diameter using 119 common beech fagus sylvatica l and 39 crimean pine pinus nigra ssp pallasiana trees growing on two landslide bodies the landslide events reconstructed with the classical approach reaction wood also appear as events in the eccentricity analysis but the inclusion of eccentricity clearly allowed for more 162 landslides to be detected in the tree ring series with respect to tree sensitivity conifers and broad leaved trees show the strongest reactions to landslides at ages comprised between 40 and 60 years with a second phase of increased sensitivity in p nigra at ages of ca 120 130 years these phases of highest sensitivities correspond with trunk diameters at breast height of 6 8 and 18 22 cm respectively p nigra this study thus calls for the inclusion of eccentricity analyses in future landslide reconstructions as well as for the selection of trees belonging to different age and diameter classes to allow for a well balanced and more complete reconstruction of past events

rare earth element geochemistry of fluorite carbonate deposits in western montana u s a abstract the fluorite carbonate quartz deposits of mineral missoula and ravalli counties in western montana u s a at one time described as carbonatitic have recently been shown to be hydrothermal in origin based on chemical o and sr isotope and field studies we report the results for rare earth elements ree in the fluorite and carbonate minerals and discuss the implications for their origin fluorite from lime gulch white cloud swallow spar wilson gulch and snowbird deposits exhibits ree chondrite patterns with a pronounced enrichment in the middle ree mree highly depleted light ree lree and slightly depleted lu often accompanied by a similar small depletion in yb la is depleted relative to sm by an order of magnitude calcite is also mree enriched although la is not as depleted relative to sm as in the associated fluorite dolomite does not show la depletion relative to sm calcite and dolomite have negative eu anomalies whereas some of the fluorite does not ree patterns for the fluorite and carbonates are typical of those from other hydrothermal deposits reported in literature chemical zonation caused by complexation of mree and hree with carbonate and fluoride ions and a high degree of ree fractionation apparently produced the ree distribution patterns observed for these deposits

landslides triggered by the 22 july 2013 minxian zhangxian china mw 5 9 earthquake inventory compiling and spatial distribution analysis abstract on july 22 2013 an earthquake of ms 6 6 occurred at the junction area of minxian and zhangxian counties gansu province china this earthquake triggered many landslides of various types dominated by small scale soil falls slides and topples on loess scarps there were also a few deep seated landslides large scale soil avalanches and fissure developing slopes in this paper an inventory of landslides triggered by this event is prepared based on field investigations and visual interpretation of high resolution satellite images the spatial distribution of the landslides is then analyzed the inventory indicates that at least 2330 landslides were triggered by the earthquake a correlation statistics of the landslides with topographic geologic and earthquake factors is performed based on the gis platform the results show that the largest number of landslides and the highest landslide density are at 2400 m 2600 m of absolute elevation and 200 m 300 m of relative elevation respectively the landslide density does not always increase with slope gradient as previously suggested the slopes most prone to landslides are in s sw w and nw directions concave slopes register higher landslide density and larger number of landslides than convex slopes the largest number of landslides occurs on topographic position with middle slopes whereas the highest landslide density corresponds to valleys and lower slopes the underlying bedrocks consisting of conglomerate and sandstone of lower paleogene eb register both the largest number and area of landslides and the highest landslide number and area density values correlations of landslide number and landslide density with perpendicular and along strike distance from the epicenter show an obvious spatial intensifying character of the co seismic landslides the spatial pattern of the co seismic landslides is strongly controlled by a branch of the lintan dangchang fault which indicates the effect of seismogenic fault on co seismic landslides in addition the area affected by landslides related to the earthquake is compared to the relationship of area affected by landslides vs earthquake magnitude constructed based on earthquakes worldwide and it is shown that the area affected by landslides triggered by the minxian zhangxian earthquake is larger than that of almost all other events with similar magnitudes

tree ring dated landslide movements and their relationship to seismic events in southwestern montana usa abstract to determine periods of incremental landslide movement and their possible relationship to regional seismic events the tree ring records of 32 tilted and damaged conifers at three sites on landslides in the gravelly range of southwestern montana were examined several signs of disturbance in the tree ring record indicating landslide movement were observed commonly the tree ring record displayed a marked reduction in annual ring width and or the reaction wood formation the tree ring records from the three landslide sites indicate multiple periods of movement during the 20th century many of the periods of movement indicated by the strongest signals most trees at the sites occurred the year following significant earthquakes in the region those seismic events for which evidence in the tree ring record was found at one or more of the three sites are the 1983 borah peak 1959 hebgen lake 1935 helena 1925 clarkson and 1908 virginia city earthquakes this study suggests that many of the landslide movements were triggered by or are coincident with earthquakes as much as 200 km from the study area

why so few landslides triggered by the 2002 denali earthquake alaska abstract the 2002 m w 7 9 denali fault earthquake alaska provides an unparalleled opportunity to investigate in quantitative detail the regional hillslope mass wasting response to strong seismic shaking in glacierized terrain we present the first detailed inventory of 1580 coseismic slope failures out of which some 20 occurred above large valley glaciers based on mapping from multi temporal remote sensing data we find that the denali earthquake produced at least one order of magnitude fewer landslides in a much narrower corridor along the fault ruptures than empirical predictions for an m 8 earthquake would suggest despite the availability of sufficiently steep and dissected mountainous topography prone to frequent slope failure in order to explore potential controls on the reduced extent of regional coseismic landsliding we compare our data with inventories that we compiled for two recent earthquakes in periglacial and formerly glaciated terrain i e at yushu tibet m w 6 9 2010 and aysen fjord chile 2007 m w 6 2 fault movement during these events was similarly to that of the denali earthquake dominated by strike slip offsets along near vertical faults our comparison returns very similar coseismic landslide patterns that are consistent with the idea that fault type geometry and dynamic rupture process rather than widespread glacier cover were among the first order controls on regional hillslope erosional response in these earthquakes we conclude that estimating the amount of coseismic hillslope sediment input to the sediment cascade from earthquake magnitude alone remains highly problematic particularly if glacierized terrain is involved

reconstructing recent landslide activity in relation to rainfall in the llobregat river basin eastern pyrenees spain abstract a chronology of recent landslides in the upper basin of the llobregat river eastern pyrenees has been reconstructed from technical reports field reconnaissance and dendrogeomorphological analysis the precipitation conditions responsible for triggering and reactivating landslides have been deduced by analysis of rainfall records from two rain gauges located in the area two different rainfall patterns relate to landslide occurrence i without antecedent rainfall high intensity and short duration rains trigger mostly debris flows and shallow slides developed in colluvium and weathered rocks a rainfall threshold of around 190 mm in 24 h initiates failures whereas more than 300 mm in 24 48 h are needed to cause widespread shallow landsliding ii with antecedent rain moderate intensity precipitation of at least 40 mm in 24 h reactivates mudslides and both rotational and translational slides affecting clayey and silty clayey formations in this case several weeks and 200 mm of precipitation are needed to cause landslide reactivation dendrochronological analysis shows that landslide activity in the eastern pyrenees was relatively low between 1926 and 1959 but has since increased significantly with reactivation now occurring about every 3 years

geomorphological pedological and dendrochronological signatures of a relict landslide terrain mt garbatka kamienne mts sw poland abstract in the kamienne mountains the largest concentration of apparently relict landslides in the sudetes range occurs on the northern slopes of mt garbatka mass movements re shaped two adjacent slope hollows and a wide depositional area is located down the valley the main landslide body is nearly 1 km long and 200 300 m wide its flattened surface morphology and the occurrence of large dispersed allochtonous boulders in the distal part suggests a flow like movement initiated by shallow translational slides in the upper slopes the thickness of colluvium determined by an ert survey may reach 10 m geomorphic signatures of mass movement are subdued suggesting that considerable time has elapsed since the origin of the landslide and that large scale mass movements are likely pre holocene in age this is consistent with the results of an extensive soil survey within the landslide body and on the surrounding slopes similarity of soil properties and well developed horizonation of profiles both within the landslide and outside it shows that no major disturbance has taken place during the soil formation period dendrogeomorphological research in turn yielded evidence of numerous growth disturbances recorded in tree rings of norway spruce growing on the landslide body these signals are interpreted that the slope surface is not entirely stable under current environmental conditions flow or creep of landslide material is not very likely given the characteristics of cover materials and it is hypothesized that dendrochronological signals develop in response to ground deformation through piping and throughflow landslide hazard in the valley below mt garbatka appears low at present but to claim complete stability would be premature

earthquake driven acceleration of slow moving landslides in the colca valley peru detected from pleiades images abstract major earthquakes in mountainous areas often trigger rapid landslides some observations also suggest that earthquakes can damage landslide prone areas or cause slow moving landslides to accelerate with a risk of evolution to rapid landslides in the following months after the earthquake here we use optical images from the pleiades satellites to detect slow moving landslides and quantify the effect of earthquakes on the landslide motion we process multi temporal pleiades images acquired in march april and july 2013 over an area of 210 km2 in the colca valley south peru to obtain two digital elevation models dem and three displacement fields of the area the processed dems have an uncertainty of 0 6 m 1 an order of magnitude better than two global and freely available dems gdem v2 and srtm whereas the displacement fields have an uncertainty of between 0 11 and 0 18 m 1 in both horizontal directions using these data we detect 9 slow moving landslides and compare their velocities during the march april and april july periods we find that landslide velocities are highest during the wet season which suggests a strong groundwater control and we also highlight a landslide acceleration caused by a regional mw 6 0 earthquake the major parameters controlling the acceleration of the slow moving landslides are the rock type and the distance to the source suggesting that friction at the basal interface in the weeks after the earthquake is dependent on the shaking intensity

geochemistry and metallogeny of ag pb zn veins in the purcell basin british columbia the mesoproterozoic purcell basin in canada contains three different types of veins 1 type 1 pb zn ag veins are composed of fe rich sphalerite pyrrhotite galena freibergite and pyrite with minor quartz gangue 2 type 2 pb ag cu au veins are characterized by galena pyrite freibergite and gold in a quartz gangue and 3 type 3 ag pb zn vein and replacement deposits contain fe poor sphalerite galena pyrite and freibergite in a quartz dolomite gangue that locally replaces host dolostone the sulfur isotope composition of type 1 2 and 3 vein and replacement deposits closely reflects their respective stratigraphic positions type 1 and 2 veins hosted in lower purcell sedimentary rocks have light sulfur isotope compositions 4 8 to 2 5 similar to diagenic pyrite disseminated in clastic sedimentary host rocks type 3 veins and the replacement deposits hosted in upper purcell supergroup rocks have heavy sulfur isotope compositions 8 3 17 2 indicative of thermo chemical reduction of marine sulfate in carbonate host rocks quartz from type 1 pb zn ag veins has 18 o smow values ranging from 7 to 17 whereas type 2 and 3 vein and replacement deposits have 18 o values ranging from 9 to 20 the range of 18 o values for type 1 2 and 3 veins is the result of mixing of metamorphic fluids with a 18 o value higher than 11 5 and an upper crustal fluid with a 18 o lower than 1 2 in equilibrium with the host rocks during proterozoic type 1 and mesozoic cenozoic type 2 and 3 hydrothermal events galena and freibergite lead isotope compositions plot in two groups consistent with previous studies type 1 pb zn ag veins have a nonradiogenic lead signature 206 pb 204 pb 16 322 16 435 and are considered proterozoic in age type 2 pb ag au cu veins and type 3 ag pb zn vein and replacement deposits have a radiogenic lead signature 206 pb 204 pb 17 842 19 347 and are interpreted to be mesozoic cenozoic in age hydrothermal sericite from the type 3 ptarmigan replacement deposit yields a 40 ar 39 ar age of 133 1 0 7 ma indicating a cretaceous age for type 3 deposits type 1 veins are interpreted to be the result of hydrothermal fluids generated during the proterozoic east kootenay orogeny whereas type 2 and 3 veins and replacement deposits are interpreted to be the result of late cretaceous paleocene tectonism

extraordinary distance limits of landslides triggered by the 2011 mineral virginia earthquake the 23 august 2011 mineral virginia earthquake m w 5 8 was the largest to strike the eastern u s since 1897 and was felt over an extraordinarily large area although no large landslides occurred the shaking did trigger many rock and soil falls from steep river banks and natural cliffs in the epicentral area and from steep road cuts along and northwest of the blue ridge parkway we mapped the occurrence of rock falls to determine distance limits that could be compared with those from other documented earthquakes studies of previous earthquakes indicated a maximum epicentral distance limit for landsliding of 60 km for an m 5 8 earthquake the maximum distance limit for the 2011 earthquake was 245 km the largest exceedance of the historical limit ever recorded likewise the previous maximum area affected by landslides for this magnitude was 1500 km2 the area affected by landslides in the 2011 earthquake was 33 400 km2 these observations provide physical evidence that attenuation of strong shaking for eastern u s earthquakes is significantly lower than for plate boundary earthquakes also distance limits parallel to the regional structural trend are greater than those that transect the structure which suggests anisotropic attenuation related to the regional geologic structure peak ground acceleration pga at the landslide distance limits is estimated to have been about 0 02 0 04 g

landslides induced by the wenchuan earthquake and the subsequent strong rainfall event a case study in the beichuan area of china abstract the wenchuan earthquake on may 12 2008 triggered massive landslides and a subsequent strong rainfall prompted the development of new landslides as well as the reactivation of some pre existing landslides the highest seismic intensity zone of the wenchuan earthquake in beichuan china was selected as a case study to analyze the influence of the earthquake and the subsequent heavy rains on landslide evolution we selected this study area 414 km 2 since it was close to the coseismic surface rupture and because it suffered strong ground motion based on the interpretation of high resolution aerial photographs and remote sensing imagery combined with field investigation 40 pre earthquake landslides and 2221 coseismic landslides were identified with total landslide areas of 2 68 km 2 and 30 81 km 2 respectively there were 134 large over 50 000 m 2 co seismic landslides that covered a surface area of 15 54 km 2 and represented approximately 50 4 of the total area of the co seismic landslides the coseismic landslides were mainly located on the hanging wall of the causative fault and on the steep valley sides of the jian river and its tributaries a strong rainfall event occurred four months after the wenchuan earthquake and induced 969 new landslides which covered a 6 90 km 2 area and enlarged 169 existing landslides 2 48 km 2 the landslides were identified in spot5 images ultimately we found that earthquake tremors and the subsequent rainstorm severely disturbed the surface strata resulting in a large number of landslides

the effectiveness of dendrogeomorphic methods for reconstruction of past spatio temporal landslide behaviour abstract dendrogeomorphic methods are in fact frequently used for spatio temporal landslide behaviour reconstruction however their real accuracies have not yet been deeply evaluated the purpose of this study is to evaluate the effectiveness and accuracy of tree ring based methods by comparing them with field monitoring data on landslide behaviours a total of 876 increment cores have been extracted from 219 p sylvestris individuals to reconstruct the past spatio temporal activity of the ubietova landslide 1977 the landslide re activation events recorded within the tree ring series of each tree have been spatially interpolated those data have been compared with the long term field monitoring based on the measured changes in the stabilized geodetic point positions in general the tree ring based spatio temporal landslide evolution revealed a higher landslide activity than the monitoring based one particularly in the lower part of the landslide however higher activity was recorded from the monitoring in the northern part of the upper half of the landslide while approximately 30 of the studied landslide area revealed highly similar normalized values based on both approaches the best fit between the results 80 was in areas with mean cumulative surface displacements of approximately 200 mm monitoring based results and mean event recurrence time of 14 5 years tree ring based results the potential sources of uncertainties that should be considered in future dendrogeomorphic research are the irregular spatial positions and spatial density of trees the physiology of the tree species the inertia of tree growth responses within tree ring sequences and the type of studied landslide

prolonged impact of earthquake induced landslides on sediment yield in a mountain watershed the tanzawa region japan abstract to determine for how long a landslide affects sediment discharge the sediment yields of 15 check dam basins were compared with the time series of landslide distributions in a mountain basin in the tanzawa region central japan the distribution of sediment yield was quantitatively estimated from deposition in the sediment pools of check dams the relationship between the landslide history and sediment discharge in the nakagawa river basin was examined for an approximately 80 year period two major landslide events occurred during this period the 1923 kanto earthquake and the 1972 disaster caused by heavy rainfall the resulting trend in sediment discharge of the whole basin estimated using reservoir sedimentation in the miho dam at its base was nearly constant with high sediment discharge 2897 m 3 km 2 yr 1 in the intervening quarter century despite the recovery of vegetation on landslide areas in this period comparisons of the landslide distributions resulting from the two disasters the sediment yields of check dam basins and the sediment discharge of the whole basin indicate that recent sediment discharge contains landslide debris that was originated by the kanto earthquake that occurred over 80 years ago thus to understand high sediment discharge it is essential to investigate not only the current basin condition and recent events but also the landslide history of the basin for at least the previous 100 years

epithermal gold mineralization in a fossil hot spring system red butte oregon the red butte gold prospect is a well preserved sediment hosted fossil hot spring system located within the lake owyhee volcanic field of eastern oregon 10 km west of the owyhee reservoir its features include siliceous hot spring sinter a blanket of intense argillic alteration produced by surficial steam heated waters and a 50 m wide hydrothermal eruption crater filled with bedded breccia deposits mineralization is hosted by north and northwest striking faults in volcaniclastic sediments of the miocene deer butte formation red butte is capped by 10 m of syngenetic fluvial sedimentary rocks consisting of a basal silicified mudstone overlain by arkosic sandstones and conglomerates interbedded with siliceous hot spring sinter the sediments at this paleosurface horizon have been cemented by hydrothermal quartz and adularia and form the resistant cap of the butte a blanketlike zone of pervasive argillic alteration occurs at the base of the fluvial sediments numerous hydrothermal veins and breccias located within the lacustrine sedimentary rocks beneath the argillic blanket contain a telescoped mineral assemblage related spatially to the paleosurface quartz and adularia are the most abundant hydrothermal minerals in this zone along with minor pyrite marcasite electrum bladed calcite stellerite ca 4 al 8 si 28 o 72 28h 2 o illite smectite and smectite clays the veins and argillic blanket are cut by a 50 m wide hydrothermal eruption crater filled with bedded breccia deposits the delta 18 o smow values for hydrothermal quartz and adularia range from 5 3 to 8 3 and 0 1 to 2 4 per mil respectively the delta 18 o smow and delta 13 c pdb values for calcite range from 3 6 to 8 9 and 8 9 to 5 2 per mil respectively these values are consistent with those of minerals from meteoric hydrothermal systems a plot of delta 18 o versus delta 13 c values for calcite shows that hco super 3 was the dominant aqueous carbon species inaa analyses of altered sedimentary rocks and hydrothermal vein and breccia samples reveal the presence of anomalous concentrations of au ag as sb hg and mo q mode factor analysis indicates that much of the variation in the geochemical data set can be explained in terms of five end member components factors which reflect the composition and evolution of the hydrothermal fluid and the initial composition of the host rock elemental associations for these factors are 1 au k 2 o ag feo hg 2 cao mo hg as 3 feo na 2 o hg sb 4 k 2 o zn na 2 o as and 5 as mo sb ag the abundance of adularia and stability of stellerite at red butte suggests that fluids reaching the surface had experienced a high degree of vapor separation due to boiling au mineralization occurred at the peak of hydrothermal activity in response both to boiling and mixing of the boiling hydrothermal fluid with surficial steam heated waters

spatio temporal analysis of a complex landslide in the northern apennines italy by means of dendrochronology dendrochronology is used to determine the spatial and temporal development of movements in a complex landslide located in the northern apennines the analysis of trees growing on the landslide body enabled us to date their colonisation pattern which starts from the 1920s and increases mainly after 1950 since then sampled trees recorded with growth anomalies the movements involving the landslide body in 1956 1957 1982 1983 1990 1995 and 1998 these movements are reactivations of the main landslide that probably occurred in the last decades of the 19th century in 1980 trees on the upper landslide body were involved in a rock fall due to the expansion of the main scarp microsections cut out from selected tree ring sequences allowed seasonal dating of the highlighted movements which mostly occurred in early spring meteorological and seismic time series were analyzed in order to relate them with reactivations and to search for correlations and triggering events the seismic activity although characterized by low magnitudes could be able either to trigger the movements 1990 or to destabilize the ground where rainfalls could have been playing the first role in triggering the reactivation probably in 1982 1983 and 1995 the other reactivations seem to be linked either to long lasting rainfalls or to monthly rainfall peaks mostly following dry periods

earthquake induced ground failures in italy abstract the national catalog of ground failures induced by strong earthquakes in italy cedit is described the catalog holds data on ground failures triggered by the earthquakes that occurred in italy in the last millennium and which had a nominal epicentral intensity equal to or greater than viii in the mercalli cancani sieberg mcs intensity scale the ground effects reported in the catalog are the following landslides fractures liquefaction surface faulting and topographic changes of the ground level subsidence settlements tilting and so on each effect is described in terms of seismological parameters of the triggering earthquake site coordinates and administrative code lithology and kinematic type of the ground failure the catalog represents a tool to assess the susceptibility of geologic materials to ground shaking and to validate predictive models of seismically induced ground displacements scenarios of earthquake induced geologic risks in the context of this study a simple statistical analysis of the database yielded useful relations between the parameters of the triggering earthquakes and the related effects

spatial and temporal analysis of mass movement using dendrochronology tree growth and inclination on sloping land is affected by mass movement suitable analysis of tree growth and tree form can therefore provide considerable information on mass movement activity this paper reports a new automated method for studying the temporal and spatial aspects of mass movement activity ringwidth data from only a few cores per tree are required the method uses filtering techniques and statistical time series analysis preliminary results for two landslides in the barcelonnette area of the french alps show a relative stability of movement activity over the last hundred years no trend and short periodicity six to seven year periods of mass movement activity the advantages of the method over other mostly visual methods are its clearness flexibility repeatability and rapidity however further testing is needed to examine its reliability

isotope geochemistry of ankerite bearing veins associated with the coeur d alene mining district idaho ankerite bearing veins are common and widespread throughout and adjacent to the coeur d alene mining district oxygen isotope ratios for quartz from the calcite dominant and ankerite dominant veins overlap and range from 12 to 18 per mil and average 16 2 and 15 5 per mil respectively previous studies of quartz from the ag producing veins give average ratios of 14 5 to 14 7 per mil ankerite oxygen and carbon isotope ratios range from 11 0 to 15 8 per mil and from 11 8 to 0 1 per mil respectively all but one of the calcite oxygen and carbon ratios lie in the ranges 13 0 to 16 0 per mil and 6 9 to 2 8 per mil quartz ankerite fractionations lie between 1 1 and 2 9 per mil except for samples from four massive ankerite veins suggesting equilibrium at moderate temperatures perhaps 270 to 320 c quartz calcite oxygen fractionations are scattered as are the quartz ankerite fractionations from the massive ankerite veins and clearly represent disequilibrium the high oxygen ratios suggest that the hydrothermal fluids were strongly buffered prior to entering the veins by isotope exchange with the sedimentary belt supergroup rocks that form the vein walls and perhaps by deeper archean rocks the 40ar 39ar age of fluorphlogopite from a calcite dominant vein is 1014 ma while an ankerite dominant vein yielded a minimum age of 963 ma the latter sample shows partial resetting at 100 to 120 ma these ages fall within the bimodal distribution of hydrothermal ages previously reported for the coeur d alene district one proterozoic age near 1 ga and a younger age in late cretaceous early tertiary time initial 87sr 86sr ratios in the range 0 738 to 0 787 for several of the carbonate minerals require derivation from an old source local belt wall rocks or deeper archean schists and gneisses are likely possibilities

geology and u pb geochronology of archean basement and proterozoic cover in the priest river complex northwestern united states and their implications for cordilleran structure and precambrian continent reconstructions precambrian basement rocks exposed within tectonic windows in the north american cordillera help to define the precambrian crustal structure of western north america and possible reconstructions of the late proterozoic supercontinent rodinia new geologic mapping and u pb dating in the infrastructure of the priest river metamorphic complex northern idaho documents the first archean basement 2651 20 ma north of the snake river plain in the north american cordillera the archean rocks are exposed in the core of an antiform and mantled by a metaquartzite that may represent the nonconformity between basement and the overlying hauser lake gneiss which is correlated with the prichard formation of the belt supergroup a structurally higher sheet of augen gneiss interleaved with the hauser lake gneiss yields a u pb zircon crystallization age somewhat greater than 1577 ma the slivers of augen gneiss were tectonically interleaved with the surrounding hauser lake gneiss near the base of the spokane dome mylo

geology s pb isotopes and 40 ar 39 ar geochronology of the zhaxikang sb pb zn ag deposit in southern tibet implications for multiple mineralization events at zhaxikang several au sb sb au pb zn and sb pb zn ag deposits are present throughout the north himalaya in southern tibet china the largest sb pb zn ag deposit is zhaxikang 18 mt at 0 6 wt sb 2 0 wt pb 3 5 wt zn and 78 g t ag zhaxikang veins are hosted within n s trending faults which crosscut the early middle jurassic ridang formation consisting of shale interbedded with sandstone and limestone deposited on a passive continental margin ore paragenesis indicates that zhaxikang mineralization occurred in two main phases composed of six total stages the initial phase was characterized by assemblages of fine grained mn fe carbonate arsenopyrite pyrite sphalerite stage 1 followed by relatively coarse grained mn fe carbonate fe rich sphalerite galena pyrite stage 2 the second phase was marked by assemblages of quartz pyrite fe poor sphalerite and ag rich galena tetrahedrite sericite stage 3 quartz sb pb sulfosalt minerals mainly composed of boulangerite and jamesonite stage 4 quartz stibnite cinnabar stage 5 and quartz calcite stage 6 sulfides of stage 2 have 34sv cdt of 8 4 12 0 206pb 204pb ratios of 19 648 to 19 659 207pb 204pb ratios of 15 788 to 15 812 and 208pb 204pb ratios of 40 035 to 40 153 sulfides of stage 3 have similar 34sv cdt of 6 1 11 2 and relatively more radiogenic lead isotopes 206pb 204pb 19 683 19 792 stage 4 sb pb sulfosalt minerals have 34sv cdt of 5 0 7 2 and even more radiogenic lead 206pb 204pb 19 811 19 981 by contrast stibnite of stage 5 has 34sv cdt of 4 5 7 8 and less radiogenic lead 206pb 204pb 18 880 18 974 taken together with the geological observations that the pb zn bearing mn fe carbonate veins were crosscut by various types of quartz veins sphalerite and galena of stage 2 underwent dissolution and remobilization and that sb pb fe sulfosalts formed at the expense of pb from stage 2 galena and of fe from stage 2 sphalerite we argue that the early pb zn veins were overprinted by later sb rich fluids stage 2 fluids were likely acidic and oxidized and leached lead from high grade metamorphic rocks of the greater himalayan crystalline complex ghc and sulfur from reduced rocks such as slate of the ridang formation along n s trending faults leading to precipitation of pb zn sulfides and mn fe carbonate and formation of solution collapse breccias later sb rich fluids leached pb from the ghc and the pre existing sulfides and deposited fe poor sphalerite ag rich galena tetrahedrite sb pb sulfosalts and stibnite in quartz veins that cut pre existing pb zn bearing mn fe carbonate veins the sb rich fluids also likely leached pb from early cretaceous gabbro and formed stibnite at shallow levels where early pb zn bearing mn fe carbonate veins are absent a sericite 40ar 39ar plateau age of 17 9 0 5 ma from stage 3 veins represents the timing of the onset of stage 3 mineralization

landslides triggered by the 8 october 2005 kashmir earthquake abstract the 8 october 2005 kashmir earthquake triggered several thousand landslides these were mainly rock falls and debris falls although translational rock and debris slides also occurred in addition a sturzstrom debris avalanche comprising 80 million m3 buried four villages and blocked streams to create two lakes although landsliding occurred throughout the region covering an area of 7500 km2 the failures were highly concentrated associated with six geomorphic geologic anthropogenic settings including natural failures in 1 highly fractured carbonate rocks comprising the lowest beds in the hanging wall of the likely earthquake fault 2 tertiary siliciclastic rocks along antecedent drainages that traverse the hazara kashmir syntaxis 3 steep 50 slopes comprising precambrian and lower paleozoic rocks 4 very steep 50 lower slopes of fluvially undercut quaternary valley fills and 5 ridges and spur crests the sixth setting was associated with road construction extensive fissuring in many of the valley slopes together with the freshly mobilized landslide debris constitutes a potential hazard in the coming snowmelt and monsoon seasons this study supports the view that earthquake triggered landslides are highly concentrated in specific zones associated with the lithology structure geomorphology topography and human presence

impact of bending related faulting on the seismic properties of the incoming oceanic plate offshore of nicaragua impact of bending related faulting on the seismic properties of the incoming oceanic plate offshore of nicaragua

metamorphic origin of the coeur d alene base and precious metal veins in the belt basin idaho and montana fluid inclusions geochronology and field studies show that the world class base and precious metal veins of the coeur d alene district idaho and montana are the product of deformation coupled with regional metamorphism of the belt basin around 850 ma fluid inclusion data show that the mineralizing solutions were complex co2 ch4 cnhm n2 h2o nacl fluids that changed in composition from ch4 cnhm rich fluids in the older zn rich veins to co2 rich fluids in the younger ag rich veins ore deposition occurred at about 250 to 350 c and at pressures in excess of 1 kbar

siderite mineralization of the gemericum superunit western carpathians slovakia review and a revised genetic model abstract the gemericum is a segment of the variscan orogen subsequently deformed by the alpine carpathian orogeny the unit contains abundant siderite sulphide and quartz antimony veins together with stratabound siderite replacement deposits in limestones and stratiform sulphide mineralization in volcano sedimentary sequences the siderite sulphide veins and siderite replacement deposits of the gemericum represent one of the largest accumulations of siderite in the world with about 160 million tonnes of mineable feco 3 more than 1200 steeply dipping hydrothermal veins are arranged in a regional tectonic and compositional pattern reflecting the distribution of regional metamorphic zones siderite sulphide veins are typically contained in low grade chlorite zone sedimentary volcano sedimentary or volcanic lower and upper paleozoic rocks quartz antimony veins are hosted by higher grade units biotite zone siderite sulphide veins are dominated by early siderite followed by a complex set of stages including quartz sulphide chalcopyrite tetrahedrite barite tourmaline quartz and sulphide remobilization stages the temporal evolution of these stages is difficult to study because of the widespread and repeated tectonic processes within vein replacement and recrystallization siderite sulphide veins show considerable vertical up to 1200 m and lateral up to 15 km extent and a thickness typically reaching several metres carbonate replacement siderite deposits of the gemericum are hosted by a silurian limestone belt and are similar to stratabound siderite deposits of the eastern alps e g erzberg austria based on a review of geological petrological and geochronological data for the gemericum and extensive stable and radiogenic isotope data and fluid inclusion data on hydrothermal minerals the siderite sulphide veins and siderite replacement deposits are classified as metamorphogenic in a broad sense the deposits were formed during several stages of regional crustal scale fluid flow isotope s c sr pb fingerprinting identifies the metamorphosed rock complexes of the gemericum as a source of most components of hydrothermal fluids fluid inclusion and stable isotope data evidence the participation of several contrasting fluid types and the existence of contrasting p t conditions during vein evolution a high 1 8 o medium to high salinity h 2 o type fluid is the most important component during siderite deposition whereas h 2 o co 2 type fluid inclusion containing dense liquid co 2 and corresponding to minimal pressures between 1 and 3 kbar were found in a younger tourmaline quartz stage younger quartz ankerite siderite sulphide stages are characterized by high salinity 17 to 35 wt nacl equivalent and low temperature t h 90 to 180 c h 2 o type fluids the vein deposits are interpreted as a result of multistage hydrothermal circulation with variscan and alpine mineralization phases based on available indirect data the most important mineralization phase was related to regional fluid flow during the uplift of a variscan metamorphic core complex producing siderite sulphide barite mineralization while tourmaline quartz stage and sulphide remobilization stages are related to alpine processes two phases of vein evolution are evident from two groups of 87 sr 86 sr isotope ratios of sr rich rb poor hydrothermal minerals 0 71042 0 71541 in older barite and 0 7190 0 7220 in late stage celestine and strontianite

evidence for proterozoic and late cretaceous early tertiary ore forming events in the coeur d alene district idaho and montana new 40 ar 39 ar age spectra on sericite and lead isotope data on tetrahedrite siderite galena bournonite and stibnite together with previously published isotopic geochemical and geologic studies provide evidence for two major vein forming events in the coeur d alene district and surrounding areas of the belt basin the data suggest that the zinc and lead rich veins e g bunker hill and star morning mines formed in the proterozoic 1 0 ga whereas the silver rich veins e g silver belt mines antimony veins e g u s antimony mine and gold bearing quartz veins murry subdistrict formed in late cretaceous to early tetitary time

seismically induced landslides by a low magnitude earthquake the mw 4 7 ossa de montiel event central spain this work has been funded by spanish ministry of economy and competitiveness research project cgl2011 30153 c02 02 and by the research groups rnm 374 junta de andalucia tectac ucm 910368 and vigrob 184 universidad de alicante mr loffredo acknowledges funding of the universita di roma la sapienza post graduate grant concorso a n 480 area cun 04

monitoring of the large slow kahrod landslide in alborz mountain range iran by gps and sar interferometry in this study we quantify and analyze the spatial and temporal evolution of the surface displacement of kahrod landslide located in the center of alborz range iran within the haraz valley this landslide represents a threat for this main drainage axis and its numerous infrastructures we present three sets of displacement vectors based on gps technique an 8 benchmark network has been surveyed four times on a 1 year period basis it provides accurate information on the rate of displacement within the landslide and addresses the problem of the mechanical resistance of a small hillock down slope under the stress imposed by the landslide then this network is densified 57 marks and measured twice in 6 months using a rapidstatic approach this yields to a dense description of surface deformation over the whole landslide finally a 1 year time series of permanent gps recordings is presented and compared to rainfall furthermore we analyze envisat radar differential interferograms dinsar spanning the same period as permanent gps these geodetic data allow to precisely determine the limits of the current sliding zone and to describe the spatial and temporal evolution of surface displacement the combination of geodesy and field observations leads to a precise description of the past and present kinematics behavior of kahrod landslide the chaotic nature of the sliding mass suggests a first catastrophic landslide in a first episode during the period of observation the landslide appears to deform quite steadily and the evidence of short term correlation between rainfall and deformation amplitude needs to be confirmed by future measurements carrying on the acquisition of gps and insar data within the sliding mass but also within adjacent bedrock should give fundamental information with regards to major activation processes river sapping water seeping earthquakes or failure within the frontal hill of bedrock and their potential consequences

coseismic and postseismic motion of a landslide observations modeling and analogy with tectonic faults we document the first time series of a landslide reactivation by an earthquake using continuous gps measurements over the maca landslide peru our survey shows a coseismic response of the landslide of about 2 cm followed by a relaxation period of 5 weeks during which postseismic slip is 3 times greater than the coseismic displacement itself our results confirm the coseismic activation of landslides and provide the first observation of a postseismic displacement these observations are consistent with a mechanical model where slip on the landslide basal interface is governed by rate and state friction analogous to the mechanics of creeping tectonic faults opening new perspectives to study the mechanics of landslides and active faults

alteration of the subducting oceanic lithosphere at the southern central chile trench outer rise hydrothermal circulation and brittle faulting processes affecting the oceanic lithosphere are usually confined to the upper crust for oceanic lithosphere created at intermediate to fast spreading rates lower crust and mantle rocks are therefore relatively dry and undeformed however recent studies at subduction zones suggest that hydration of the oceanic plate is most vigorous at the trench outer rise where extensional bending related faulting affects the hydrogeology of the oceanic crust and mantle to understand the degree of hydration we studied the seismic velocity structure of the incoming nazca plate offshore of southern central chile 43 s here the deep sea trench is heavily filled with up to 2 km of sediments seismic refraction and wide angle data complemented by seismic reflection imaging of sediments are used to derive a two dimensional velocity model using joint refraction and reflection traveltime tomography the seismic profile runs perpendicular to the spreading ridge and trench axes the velocity model derived from the tomography inversion consists of a 5 3 km thick oceanic crust and shows p wave velocities typical for mature fast spreading crust in the seaward section of the profile with uppermost mantle velocities as fast as 8 3 km s approaching the chile trench seismic velocities are significantly reduced however suggesting that the structures of both the oceanic crust and uppermost mantle have been altered possibly due to a certain degree of fracturing and hydration the decrease of the velocities roughly starts at the outer rise 120 km from the deformation front and continues into the trench even though the trench is filled with sediment basement outcrops in the outer rise frequently pierce the sedimentary blanket anomalously low heat flow values near outcropping basement highs indicate an efficient inflow of cold seawater into the oceanic crust hydration and crustal cracks activated by extensional bending related faulting are suggested to govern the reduced velocities in the vicinity of the trench considering typical flow distances of 50 km water might be redistributed over most of the trench outer rise area where trapped in faults seawater may migrate down to mantle depth causing up to 9 of serpentinization in at least the uppermost 2 km of the mantle between the outer rise and the trench axis

multi sensor advanced dinsar monitoring of very slow landslides the tena valley case study central spanish pyrenees abstract in this work it is demonstrated how the combination of multi sensor and multi temporal sar data improves the monitoring capacity of very slow landslides the study area is the upper tena valley central spanish pyrenees where mostly very slow earth flows have caused direct damage estimated at approximately 15 m in the last decade the advanced dinsar processing of ascending orbit alos palsar images 2006 2010 and descending orbit ers envisat 2001 2007 and terrasar x 2008 datasets has provided heterogeneous displacement velocity measurements the projection along the steepest slope of los displacements reduces the geometrical differences introduced by each satellite these results were compared and validated with available d gps measurements in a second step ps displacement data are combined with a landslide inventory increasing the number of monitored landslides with sufficient ps from 4 to 19 obtained from c and x band data to 38 of the total 294 finally the retrieved multi sensor landslides velocities are classified with respect to the magnitude of road damages that occurred in the 2008 2010 period at local scale the combination of multi sensor data was useful to differentiate different landslide displacement directions to measure different velocity patterns within the same moving mass and to distinguish the slower natural and faster human induced landslides the analysis of displacement time series permitted to evaluate the acceleration caused by a destabilising anthropogenic change and the correlation between displacement variability and seasonal precipitation and melting

intensity duration threshold of rainfall triggered debris flows in the wenchuan earthquake affected area china the ms 8 0 wenchuan earthquake has greatly altered the rainfall threshold for debris flows in the affected areas this study explores the local intensity duration i d relationship based on 252 post earthquake debris flows it was found that i 525 d 0 76 accounts for more than 98 of the debris flow occurrences with rainfall duration between 1 and 135 h therefore the curve defines the threshold for debris flows in the study area this gives much lower thresholds than those proposed by the previous studies suggesting that the earthquake has greatly decreased the thresholds in the past years moreover the rainfall thresholds appear to increase annually in the period of 2008 2013 and present a logarithmic increasing tendency indicating that the thresholds will recover in the future decades c 2015 elsevier b v all rights reserved

stratigraphy of the proterozoic revett formation and its control on ag pb zn vein mineralization in the coeur d alene district idaho the proterozoic revett formation hosts most of the mesothermal ag pb zn vein ore in the coeur d alene district of northern idaho although it had long been recognized that stratigraphy plays a fundamental role in determining where veins produce ore the stratigraphy of the revett formation and its relationships to veins remained poorly known for most of the first 100 yr of mining in this district in northern idaho and western montana the revett formation contains informal lower middle and upper members in the coeur d alene district most ore production south of the regionally significant osburn fault came from the upper revett formation and north of the fault most production came from the upper and lower revett formation where vein structures intersect favorable strata the veins contain rich ore where vein structures cross unfavorable strata they are poorly mineralized or barren quartzite is the most favorable host rock for base metal veins and silicified blocky siltite is the most favorable host rock for silver veins both rock types are abundant in the revett formation which accounts for the disproportionately large production from this unit in the western portion of the belt supergroup ore deposit types correlate with regional scale thickness changes in the revett formation sediment hosted stratiform copper mineralization occurs in thin revett formation whereas coeur d alene veins occur in thick revett formation base metal veins in the coeur d alene district occur in relatively thick chemically reduced relatively coarse grained revett formation whereas silver veins occur in or marginal to areas with less thick locally oxidized relatively fine grained revett formation demonstrating that district scale metal zonation correlates with district scale facies and thickness changes the upper middle and lower revett formation thicken considerably southward across the osburn fault with the upper revett showing over an order of magnitude thickness increase changes in thickness of the revett formation across the osburn fault reflect a major down to the south crustal scale fault that was active during sedimentation and was periodically reactivated during the structural and metallogenic history of the district we suggest that this fault and changes in stratigraphic thickness helped control fluid flow within and beyond the coeur d alene district during mineralization events stratigraphic thickness and facies changes in the revett formation are greatest and most abrupt in the coeur d alene district indicating that this area was structurally complex during sedimentation presumably this early structural complexity also enhanced subsequent ag pb zn mesothermal vein formation

the changing ability of norway spruce p abies to record hydro geomorphic processes based on the age and diameter of the tree stem a dendrogeomorphic approach dendrogeomorphic reconstructions of debris flows and related hydro geomorphic processes i e debris floods and flash floods are widely used in territories with incomplete chronologies and potential future hazards in recent years the tree ring analysis of disturbed trees affected by dangerous geomorphic processes has developed into a discipline with sophisticated methodical approaches and with annual up to monthly accuracy of dating field sampling strategies are based on various ranges of sample depth i e different amounts of sampled trees of different age structures the age and diameter of trees influence the ability of trees to respond to geomorphic processes therefore we investigate age dependent and diameter dependent tree sensitivity our study for the first time addresses the sensitivity to hydro geomorphic processes in detail we tested 462 individuals of norway spruce picea abies l karst a very common species used in the dendrogeomorphic reconstructions in the apical part of the medium high mountains where there is widespread occurrence of debris flows and debris floods the tree sensitivity analysis was performed based on the position of growth disturbances within the increment cores of trees original age and original diameter of the tree before the tree was affected p abies shows very high tree sensitivity in the first two decades of the tree lifespan with increasing age and diameter trees are less sensitive recorders of debris flows floods moreover the intensity of growth disturbances significantly decreases with tree age mature trees 51 120 years record the geomorphic events mainly through abrupt growth changes suppression and release and tangential rows of traumatic resin ducts in contrast scars the onset of reaction wood and traumatic resin ducts are dominant growth disturbances in young thin trees 11 30 years diameter 0 15 cm different occurrences of particular growth disturbances as well as the different age and diameter dependent sensitivities emphasize the need for the inclusion of new variable that will take into account the amount of sensitive trees for each year after that adequate mixture of sampled tree i e mixture of age classes which is necessary for the completeness of debris flow flood chronologies could be balanced regarding their sensitivity

complex landslide terrain in the kamienne mountains middle sudetes sw poland dense forest hides a complex landslide terrain in the kamienne mountains a part of the sudetes range in central europe combined geomorphological geophysical and dendrochronological research was carried out in three representative localities in order to decipher patterns of landslide evolution to determine the extent of slope deformations and to assess the contemporary activity of landslide terrain field mapping revealed the very complex nature of slope failures both in space and time deep seated sliding was the principal type of movement and was followed by rock wall retreat by fall in the depletion zone and earthflows in the toe area electric resistivity survey proved useful in constraining geometry of landslide units and suggests an occurrence of underground voids in the lesista landslide area dendrochronological research focused on tree ring reduction reaction wood wound and scar analysis that helped to unravel the pattern of debris supply and movement subsequent to the main events which includes free fall talus creep and sliding over snow cover today landslide complexes are at different stages of evolution whereas in some places the activity has been largely completed in others we have found the evidence for failure surfaces ready to accommodate movement hence although some landslides may be relict it is unjustified to extend this notion to all signs of hillslope instability in the area

tree ring analysis in the reconstruction of slope instabilities associated with earthquakes and precipitation the crimean mountains ukraine the crimean mountains in ukraine constitute a seismically active region that is abundant in various types of mass movement the limestone escarpments that rise above the black sea coast in the vicinity of the town of yalta are particularly subject to considerable rockfall landslide and debris flow processes that often endanger infrastructure and human life one of these very active slopes is the area of the ancient taraktash rockslide characterised by active block type movements lateral spreading toppling and incipient sliding rockfalls ongoing sliding activities and debris flows the aims of this study were i to employ tree ring analysis to reconstruct a record of slope instabilities mainly block type movements rockfalls landslides and debris flows within the taraktash slope deformation over a period of more than two centuries and ii to establish the degree of correlation between periods of enhanced slope activity and both historical earthquakes and climatic data the temporal frequency of significant slope processes was addressed through a tree ring analysis that took 738 increment cores from 255 crimean pine trees pinus nigra ssp pallasiana the tree ring record reveals periods of increased activity of block type movements rockfalls and landslides during the major earthquakes in 1790 1875 1927 and 1986 although the slope processes studied are predominantly driven by seismic activity their intensity and duration are also dependent on climatic factors this is especially true for landslides and debris flows which occurred mainly in years characterised by high precipitation totals

can low magnitude earthquakes act as a triggering factor for landslide activity examples from the western carpathian mts poland abstract there are numerous examples of the impact of strong earthquakes on landslide activity there is however very little information about the ability of low magnitude earthquakes m

residual shear strength variability as a primary control on movement of landslides reactivated by earthquake induced ground motion implications for coastal oregon u s most large seismogenic landslides are reactivations of preexisting landslides with basal shear zones in the residual strength condition residual shear strength often varies during rapid displacement but the response of residual shear zones to seismic loading is largely unknown we used a ring shear apparatus to perform simulated seismic loading tests constant displacement rate tests and tests during which shear stress was gradually varied on specimens from two landslides to improve understanding of coseismic landslide reactivation and to identify shear strength models valid for slow gravitational failure through rapid coseismic failure the landslides we studied represent many along the oregon u s coast seismic loading tests resulted in 1 catastrophic failure involving unbounded displacement when stresses represented those for the existing landslides and 2 limited to unbounded displacement when stresses represented those for hypothetical dormant landslides suggesting that coseismic landslide reactivation may be significant during future great earthquakes occurring near the oregon coast constant displacement rate tests indicated that shear strength decreased exponentially during the first few decimeters of displacement but increased logarithmically with increasing displacement rate when sheared at 0 001 cm s 1 or greater dynamic shear resistance estimated from shear strength models correlated well with stresses observed during seismic loading tests indicating that displacement rate and amount primarily controlled failure characteristics we developed a stress based approach to estimate coseismic landslide displacement that utilizes the variable shear strength model the approach produced results that compared favorably to observations made during seismic loading tests indicating its utility for application to landslides

landslides triggered by the 20 april 2013 lushan earthquake sichuan province china abstract the 20 april 2013 lushan earthquake with a magnitude of m s 7 0 induced widespread landsliding along the southern segment of the longmen shan fault zone this paper presents a preliminary analysis of the characteristics of these co seismic landslides triggered in an area of 13 323 km 2 a total of 3810 individual landslide points were identified through an intensive field investigation and from digital aerial photographs taken after the lushan earthquake to facilitate the more detailed analysis on the areal frequency of co seismic landslides as polygons we selected an area of 732 km 2 around the epicenter that had the highest density of co seismic landslides the sizes of the landslides are in general much smaller than those that were triggered by the 2008 wenchuan earthquake the most common types of landslides in the study area were rock falls and shallow disrupted landslides from steep slopes which typically involved the top few meters of weathered bedrock and colluvium in this study the relation between the landslide distribution and five main factors was analyzed fault proximity epicenter proximity peak ground acceleration pga slope angle and lithology our study results show that the landslide concentration tends to decrease with distance from the seismogenic fault and the highest landslide concentration is located within a distance of 5 km regarding the distance to the epicenter the largest landslide density is found at a distance between 5 and 10 km the landslide concentration also increases with increasing slope angle until a maximum for the slope class 45 55 in addition results show that slopes consisting of deeply weathered and fractured sandstones and mudstones were the most susceptible to co seismic landslides in this study we found that the location of the hanging wall and the footwall of the fault did not seem to have an important effect on the landslide distribution this is in contradiction to what has been reported in other earthquake areas such as the wenchuan area

landslides induced by the 2008 wenchuan earthquake sichuan china the 2008 wenchuan earthquake with a magnitude of mw 7 9 induced numerous slope movements on the hanging walls of fault surface ruptures and on steep inner valleys along the minjiang river landslide moving directions showed preferred orientations normal to the fault ruptures indicating the effect of the directivity of the seismic wave the most common landslides were of carbonate rocks which are easily dissolved and decrease the contact surfaces the largest non volcanic landslide in history was induced in bedded dolomite by the earthquake and was preceded by gravitational deformation with ridge top depressions valley fill materials were mobilized at 36 locations probably by pore water pressure build up

application of eccentric growth of trees as a tool for landslide analyses the example of picea abies karst in the carpathian and sudeten mountains central europe abstract a method based on dendrochronology was developed to analyse the spatial and temporal variability of landslide activity as an alternative and complement to methods such as field monitoring of landslide relief aerial photography and remote sensing the method involves a feature of wood anatomy tree ring eccentricity which is used in the dating procedure the degree of eccentricity is used as an indicator of the intensity of the mechanical stress affecting a tree stem in a certain year the objective was to develop a mathematical indicator of tree ring eccentricity for dating the recent dynamics of landslides a method presented in the paper is also designed for practical application in detecting initial landslide activity and allowing the determination of triggering factors the index developed is dimensionless and for this reason is independent of the absolute ring variations of the single trees analysed using reference results from stable slopes as thresholds in dating an objective method for detecting landslide activity was developed the method was used in the carpathian and sudeten mountains on three landslides with different sizes and geological settings it was found that the values of eccentricity index in trees growing on stable slopes rarely exceed at 100 while in trees growing on landslides they can reach hundreds to thousands per cent a spatial analysis of the eccentricity values conducted for a single landslide has revealed that the method developed allows one to identify areas of landslide activation and to observe the down or upslope propagation of instability a comparison of the results obtained regarding the precipitation record has shown that by using the method that has been developed it is possible to detect past mass movement episodes caused by heavy long term rainfall as well as by single short lasting but torrential downpours

observations and predictions of the behaviour of large slow moving landslides in schist clyde dam reservoir new zealand abstract major remedial works involving toe buttressing pumped drainage gravity drainage and or infiltration protection were undertaken at nine of the seventeen large landslides along the clyde dam reservoir margins prior to lake filling in 1992 1993 all 17 landslides continue to be routinely monitored and inspected as part of the dam safety assurance programme undertaken by contact energy movement of the landslides is monitored by a combination of inclinometers extensometers and survey and is correlated with controlling events including lake filling storms floods prolonged wet periods and earthquakes most monitoring records extend over periods of 15 years with some histories as long as 25 years over 100 years of rainfall records are available for nearby locations very small deformation responses attributable to lake filling occurred at four of the stabilized slides slightly accelerated movement occurred at one slide that had not been stabilized and minor reactivation was detected at three others two landslides have demonstrated movement rate sensitivity to rainfall events neither slide was significantly affected by lake filling monitoring records show that movement of a known active part of the brewery creek landslide is triggered when a key piezometer reaches or exceeds a critical threshold level movement continues until the piezometer drops below that level movement of part of ripponvale landslide increases following prolonged rainfall events the slide was barely affected by lake filling and has not responded to subsequent transient increases in toe inundation levels floods data from zone a of the slide mass which is entirely above the lake shows the slide to be very sensitive to the effects of prolonged wet periods movement rates increase over a period of months and then gradually reduce based on the records to date it can be predicted that the slide will exhibit an increased movement rate when the cumulative rainfall over a period of 3 to 4 months exceeds about 300 mm

immiscible co2 h2o fluids in the shallow crust the significance of a single co2 h2o fluid phase is well known for metamorphic systems and co2 h2o immiscibility is explicit in fluid inclusion literature especially regarding hydrothermal ores complex multiphase co2 h2o behavior exists over wide temperature and pressure ranges overlapping other important geochemical processes the character and physical chemical properties of multiple phases possible for co2 and h2o and the potential impact of these coexisting phases on geochemical processes in the crust are not broadly appreciated we propose that immiscible supercritical co2 fluid and a liquid rich in h2o coexist in the shallow crust to 400 c and 300 mpa and that interactions among the two fluids and host rock are significant processes that produce recognizable geochemical and textural evidence supercritical co2 fluids bring potential complexity to fluid rock systems by influencing aqueous reactions via carbonic acid equilibria penetrating complex geometries inaccessible to aqueous fluid and dissolving and redistributing metals as organometallic compounds the distal margin of a contact metamorphic aureole is one example we discuss in which interaction between two disparate co2 h2o fluids controls h2o activity and the progress and distribution of metamorphic hydration reactions in another example supercritical co2 produces acidity carbonate saturation and silica supersaturation in brine separation and emplacement of this brine into a rock dominated system buffered to neutral ph enhances precipitation of carbonates and quartz chalcedony or amorphous silica in veins other possible examples of co2 h2o fluid immiscibility coupled with multiphase fluid rock interactions are clay desiccation diagenetic and postdiagenetic silicate reactions origin and distribution of carbonate cements in sedimentary basin sandstones fluid mass transfer and anthropogenic co2 sequestration

microbial community signature in lake coeur d alene association of environmental variables and toxic heavy metal phases national science foundation under grant no 0628258 defense university research instrumentation program durip contract number w911nf0510255 msu thermal biology institute from the nasa exobiology program project nag5 8807

complex rupture mechanism and topography control symmetry of mass wasting pattern 2010 haiti earthquake the 12 january 2010 mw 7 0 haiti earthquake occurred in a complex deformation zone at the boundary between the north american and caribbean plates combined geodetic geological and seismological data posited that surface deformation was driven by rupture on the leog ne blind thrust fault while part of the rupture occurred as deep lateral slip on the enriquillo plantain garden fault epgf the earthquake triggered 4490 landslides mainly shallow disrupted rock falls debris soil falls and slides and a few lateral spreads over an area of 2150 km2 the regional distribution of these slope failures defies those of most similar earthquake triggered landslide episodes reported previously most of the coseismic landslides did not proliferate in the hanging wall of the main rupture but clustered instead at the junction of the blind leog ne and epgf ruptures where topographic relief and hillslope steepness are above average also low relief areas subjected to high coseismic uplift were prone to lesser hanging wall slope instability than previous studies would suggest we argue that a combined effect of complex rupture dynamics and topography primarily control this previously rarely documented landslide pattern compared to recent thrust fault earthquakes of similar magnitudes elsewhere we conclude that lower static stress drop mean fault displacement and blind ruptures of the 2010 haiti earthquake resulted in fewer smaller and more symmetrically distributed landslides than previous studies would suggest our findings caution against overly relying on across the board models of slope stability response to seismic ground shaking

oxygen carbon and strontium isotope geochemistry of the sunshine mine coeur d alene mining district idaho the pb ag ores of the sunshine mine located in the coeur d alene mining district of northern idaho occur within steeply dipping tabular west northwest trending veins of siderite gangue that crosscut the overturned northern limb of the big creek anticline the delta 13 c pdb 9 9 to 6 4 and delta 18 o smow 13 1 17 7 values of the siderites vary in a proportion of about 1 2 but siderites with delta 18 o or 16 exhibit a slope close to the 1 4 trend expected for a system with variable temperature whereas no correlation is evident for siderites with delta 18 o 16 the delta 18 o values of crosscutting quartz veins 13 4 15 5 and the surrounding wall rocks 10 7 15 5 are several per mil too low to be in isotopic equilibrium with the siderite at the temperature of approximately 325 degrees c determined from fluid inclusion studies at this temperature the calculated delta 18 o values for the precipitating fluids range from 7 8 to 12 4 for the siderite and 6 9 to 8 9 for the quartz the high delta 18 o values calculated for these fluids reflect their exchange with the high 18 o metasedimentary rocks of the belt supergroup in higher temperature fluid source regions detailed sample traverses across two 1 to 3 m wide siderite veins show that 1 some veins are composite containing materials deposited at different times or in different places which were juxtaposed by subsequent vein parallel faulting 2 siderite in structurally simple veins is most enriched in 13 c and 18 o adjacent to the walls resulting in u shaped spatial trends and 3 the delta 18 o values of metasedimentary wallrocks are substantially lower than those of the siderite in the veins and increase adjacent to them these small scale variations account for the lack of a simple relationship between delta 18 o and depth in the vein systems these data also indicate that the vein fluids were hotter and considerably higher in 18 o than the fluids in equilibrium with adjacent wall rock the progressive 18 o decrease from the margins to the centers of the siderite veins further decreasing into the early crosscutting quartz veins probably represents a progressive increase in the temperature of deposition but could also represent variations in fluid source in an evolving system the dispersion of delta 12 c values for samples with delta 18 o 16 per mil may be the result of late stage explosive pressure release and co 2 effervescence during fluid decompression when fissure filling was nearly complete the structural simplicity of the veins and the primary hydrothermal character of the stable isotope variations argue against postdepositional deformation and metamorphism stable isotope and strontium isotope data support the interpretation that ore deposition occurred during the late cretaceous or early tertiary as the result of metamorphic hydrothermal processes associated with regional compression and the formation of major granitic batholiths

wustite in a hydrothermal silver lead zinc vein lucky friday mine coeur d alene mining district u s a the coeur d alene mining district of northern idaho is one of the major ag pb zn producers in the world it contains ag pb zn replacement veins in clastic burial metamorphic rocks of the middle proterozoic belt supergroup electron microprobe analyses and raman spectroscopy of samples from the gold hunter vein of the lucky friday mine revealed the presence of the rare iron oxide wustite fe1 xo coexisting with stable magnetite an assemblage of galena pyrite and siderite is associated with the two iron oxides although these minerals do not share phase boundaries with wustite and their coexistence is therefore thermodynamically precluded wustite is stable under high temperature conditions above 570 c at 1 bar increasing pressure can lower this temperature significantly however the veins in the coeur d alene district formed well outside the wustite stability field and represent a low temperature 250 350 c low pressure 1 3 kbars and low f o2 environment to form wustite at temperatures around 250 350 c a pressure increase of at least 70 kbars would be required this corresponds to burial of around 250 km which is geologically unrealistic similarly to form wustite the temperature must have exceeded 570 c which exceeds the maximum temperatures of vein formation by at least 200 c a temperature increase of that scale is not reflected in the mineral assemblage of the veins or the host rocks which both contain siderite we conclude that wustite formed as a metastable phase at 250 350 c and pressures below 100 bars because of the low f o2 conditions in the coeur d alene district

earthquake triggered increase in sediment delivery from an active mountain belt in tectonically active mountain belts earthquake triggered landslides deliver large amounts of sediment to rivers we quantify the geomorphic impact of the 1999 mw 7 6 chi chi earthquake in taiwan which triggered 20 000 landslides coseismic weakening of substrate material caused increased landsliding during subsequent typhoons most coseismic landslides remained confined to hillslopes downslope transport of sediment into the channel network occurred during later storms the sequential processes have led to a factor of four increase in unit sediment concentration in rivers draining the epicentral area and increased the magnitude and frequency of hyperpycnal sediment delivery to the ocean four years after the earthquake rates of hillslope mass wasting remain elevated in the epicentral area

probability maps of landslide reactivation derived from tree ring records pra bellon landslide southern french alps probability maps of landslide reactivation are presented for the pra bellon landslide located in the southern french alps based on results obtained with dendrogeomorphic analysis spatiotemporal patterns of past landslide activity was derived from tree ring series of 403 disturbed mountain pine trees growing in the landslide body in total 704 growth disturbances were identified in the samples indicating 22 reactivation phases of the landslide body between 1910 and 2011 the mean return period was 4 5 years given the spatiotemporal completeness of the reconstruction probabilities of landslide reactivation were computed and illustrated using a poisson distribution model and for 5 20 50 and 100 years probability of landslide reactivation is highest in the central part of the landslide body and increases from 0 13 for a 5 year period to 0 94 for a 100 year period conversely probabilities of reactivation are lower at its margins the proposed method differs from conventional approaches based on statistical analyses or physical modeling that have demonstrated to have limitations in the prediction of spatiotemporal reactivation of landslides our approach is in contrast based on extensive data on past landslides and therefore allowed determination of quantitative probability maps of reactivation derived directly from the frequency of past events this approach is considered a valuable tool for land managers in charge of protecting and forecasting people and their assets from the negative effects of landslides as well as for those responsible for land use planning and management it demonstrates the reliability of dendrogeomorphic mapping that should be used systematically in forested shallow landslides

oxygen isotope fractionation in quartz albite anorthite and calcite laboratory measurements of equilibrium oxygen isotope fractionation in quartz albite anorthite and calcite have been carried out by anhydrous exchange between silicates and calcite at temperatures of 600 c and above exchange in these systems is as rapid as exchange between silicates and water fractionation factors can be summarized in the following equations qc 0 38 106t 2 abc 0 57 106t 2 anc 1 59 106t 2 from which the silicate pair fractionations are readily obtained these results are compared with published theoretical estimates as well as data derived from hydrothermal experiments some significant differences are found in particular it is difficult to reconcile all of the hydrothermal data either with theoretical calculations or with the present experimental data the new experiments provide an internally consistent set of fractionation factors suitable for isotopic thermometry and for test of disequilibrium in natural systems

modeling typhoon and earthquake induced landslides in a mountainous watershed using logistic regression landslides can be caused by storms and earthquakes most logistic regression models proposed in recent years have been targeted at rainfall induced landslides in areas such as taiwan where landslides can be triggered by typhoons tropical cyclones and earthquakes a rainfall induced model is insufficient because it provides only a partial explanation of landslide occurrence and overlooks the potential effect of earthquakes on typhoon triggered landslides this study used landslides triggered by a major earthquake and a typhoon prior to the earthquake to develop an earthquake induced model and a typhoon induced model the models were then validated by using landslides triggered by three typhoons after the earthquake according to the results typhoon triggered landslides tended to be near stream channels and earthquake triggered landslides were more likely to be near ridge lines moreover a major earthquake could still affect the locations of typhoon triggered landslides 6 years after the earthquake this study therefore demonstrates that an earthquake induced model both sheds light on the environmental factors for triggering landslides and augments a rainfall induced model in its predictive capability in areas such as taiwan

soil creep the driving factors evidence and significance for biogeomorphic and pedogenic domains and systems a critical literature review abstract soil and regolith creep have been analyzed for at least the last 140 years using many methodological configurations and temporal and spatial scales the general concept of creeping soil and its mechanism first proposed by w m davis and g k gilbert at the end of the 19th century evolved since the 1940s towards theoretical models and precise short and long term field measurements this fruitful epoch continued with results enhanced at the turn of the 20th century by the application of new research methods e g radiometry and a redefinition of the term soil creep to encompass the sum of stochastic shallow subsurface and near surface processes causing net downslope movement of soil or regolith simultaneously another possibility of creep detection was noticed in dendrochronology and since the 1970s in the formally defined discipline of dendrogeomorphology indirect evaluations of creep activity were performed based on tree ring analyses of bent trees this method found many followers but was also heavily criticized as imprecise and lacking in evidence of which kind of tree trunk curvature e g pistol butt like deformation s shape curvature could be ascribed to creep movement from the beginning soil creep was associated with the activity of living organisms on hillslopes however this aspect of creep studies has never been fully developed in spite of the solid foundations and directions of potential studies pointed out by charles darwin at the end of the 19th century in this paper we focus on the historical context of soil creep studies and highlight forest ecosystems as probably the most active environment of biogenic creep mainly due to tree uprooting and other biomechanical effects of living and dead trees root channel infilling tree root mounding etc that are a factors in biotransport in the final sections the position of biogenic creep in the structure of biogeomorphic systems is discussed in relation to such important conceptual frameworks as the biogeomorphic ecosystem biogeomorphic feedback window and ecosystem engineering we also describe several hypotheses that should be carefully tested in the future and propose several research methods that have the ability to further our knowledge about soil creep radiometry laser scanning and soil micromorphology

coupling between landslides and eroding stream channels reconstructed from spruce tree rings examples from the carpathians and sudetes central europe the analysis of the positive feedback between landslides and erosion requires determination of the precise temporal and spatial relations between events of colluvium delivery and fluvial erosion in our study we use decennial datasets on the occurrence of landsliding and erosion achieved through dendrochronological methods four sites covering areas of landslide slopes and adjacent valley floors with stream channels were studied landsliding on slopes was dated from the tree ring eccentricity developed in stems tilted due to bedrock instability erosion in channels was dated using the wood anatomy of roots exposed by erosion of the soil cover analysis of the temporal relations between dated landsliding erosion and precipitation record has revealed that two types of repeating sequences can be observed 1 rainfall landsliding erosion 2 rainfall erosion landsliding these sequences are an indication of the occurrence of slope channel positive feedback in the sites studied in the first type landsliding triggered by rainfall delivers colluvia into the valley floor and causes its narrowing which in turn causes increased erosion in the second type erosion triggered by rainfall disturbs the slope equilibrium and causes landsliding landsliding and erosion once triggered by precipitation can occur alternately in years with average precipitation and reinforce one another bidirectional coupling between landsliding and channel erosion was shown notably through the effects of channel shifting and forced sinuosity and by increased erosion of the slopes opposite the active landslides observations also suggest that the repetition of sequences described over longer periods of time can lead to a general widening of the valley floor at the expense of slopes and to a gradual change of the valley cross profile from narrow v shaped into a wide flat bottomed thus landsliding erosion coupling positive feedback was recognized as an important factor shaping hillslope valley topography of the mid mountain areas studied copyright 2014 john wiley sons ltd

on far field occurrence of seismically induced landslides abstract earthquakes may induce landslides at large distances from the epicentral area in the last two decades there have been many studies of this phenomenon to determine the causes that contribute to the occurrence of landslides at very long distances from earthquake epicenter in this study which is based on previously published works a worldwide database comprising 270 earthquakes including 150 during the instrumental period was compiled to analyse the features of those landslides that occur at much further distances than maximum expected distances from the analysis of the compiled data it was observed that susceptible slopes can be grouped into five broad geological categories jointed rock marly clayey cohesive soils granular alluvial and or colluvial sediments volcanic soils and residual soil slopes these categories were equally likely to be associated with far field disrupted landslides whereas far field coherent landslides were more frequent on cohesive soil slopes other factors along with slope susceptibility may also contribute to far field landslides and increase the size of the area affected among these factors site effects antecedent rain and occurrence of seismic series have been cited the analysis of available data also showed that for events of the same magnitude far field disrupted landslides may occur at greater distances than coherent ones the same database has also been employed to determine for the first time the upper bound curves for the maximum observed epicentral distances of several types of landslides and the maximum area observed to be affected by landslides both based on the epicentral intensity of the events

geology and geochemistry of the snowbird deposit mineral county montana the snowbird deposit is a lenticular rare earth and fluorite rich quartz carbonate body with a pegmatitic texture which intrudes belt supergroup metasediments at the idaho montana state line west of missoula montana the deposit which narrows with depth consists of a peripheral quartz zone surrounding a core containing ferroan calcite ankerite fluorite and quartz with minor parisite xenotime pyrite and gersdorffite two stages of mineralization are recognized each preceded and or accompanied by brecciation isotope geochemistry of the deposit is consistent with a hydrothermal origin the delta 18 o ranges from 5 6 to 16 5 per mil the range of carbonate delta 13 c from 4 5 to 7 6 per mil is permissive evidence of a deep source the 87 sr 86 sr of fluorite and carbonates range from 0 8125 to 0 8970 rb sr approximately 0 with total sr between 5 and 42 ppm suggestive of a highly radiogenic low total sr source region the u th pb parisite ages 71 1 or 1 0 m y indicate emplacement during the late cretaceous probably associated with the intrusion of the nearby idaho batholith and the temperatures of formation based on oxygen isotope geothermometry fluid inclusion studies and other considerations are in the range of 400 degrees to 500 degrees c the snowbird deposit is rich in th and rare earth elements but is impoverished in u hydrothermal fluids probably responsible for the deposit initially contained mainly volatile constituents the cation content was acquired largely by leaching of either belt metasediments or pre belt schists and gneisses snowbird mineralization bears definite resemblances to the th deposits of the lemhi pass area and to late hydrothermal carbonatite dikes associated with the iron hill carbonatite

earthquake induced landslides in central america central america is a region of high seismic activity and the impact of destructive earthquakes is often aggravated by the triggering of landslides data are presented for earthquake triggered landslides in the region and their characteristics are compared with global relationships between the area of landsliding and earthquake magnitude we find that the areas affected by landslides are similar to other parts of the world but in certain parts of central america the numbers of slides are disproportionate for the size of the earthquakes we also find that there are important differences between the characteristics of landslides in different parts of the central american isthmus soil falls and slides in steep slopes in volcanic soils predominate in guatemala and el salvador whereas extensive translational slides in lateritic soils on large slopes are the principal hazard in costa rica and panama methods for assessing landslide hazards considering both rainfall and earthquakes as triggering mechanisms developed in costa rica appear not to be suitable for direct application in the northern countries of the isthmus for which modified approaches are required

age and origin of base and precious metal veins of the coeur d alene mining district idaho ore bearing quartz carbonate veins of the coeur d alene mining district yield 87sr 86sr ratios of 0 74 to 1 60 for low rb sr carbonate gangue minerals similar to current ranges measured in middle proterozoic high rb sr rocks of the belt supergroup stable isotope and fluid inclusion studies establish a genetic relationship between vein formation and metamorphic hydrothermal systems of the region these extraordinary 87sr 86sr ratios require accumulation of radiogenic 87sr in a high rb sr system over an extended period prior to incorporation of sr into the hydrothermal veins evaluation of the age and composition of potential sources of highly radiogenic sr indicates that the ore bearing veins of the coeur d alene district formed during the cretaceous from components scavenged from rocks of the belt supergroup the primary host rocks of the district proterozoic pb isotope ratios observed in galena from many coeur d alene veins were established when pb separated from uranium during deposition or diagenesis of the belt supergroup at 1400 to 1500 ma possibly as disseminated syngenetic deposits k ar and rb sr apparent ages and 18o values of belt supergroup rocks decrease from the coeur d alene district toward the idaho and kaniksu batholiths approximately normal to the trends of metamorphic isograds fold axes foliation and the major reverse faults of the district isoclinal folding thrust faulting high temperature metamorphism granitic plutonism and regional scale metamorphic hydrothermal activity is documented in the region between 140 and 45 ma representing the only such combination of events in the coeur d alene region subsequent to about 1300 ma the sr and oxygen results and geologic evidence favor formation of the ore bearing carbonate veins by fluids related to a complex metamorphic hydrothermal system during the cretaceous pb with proterozoic isotopic compositions was probably mobilized and incorporated like other metals into the hydrothermal veins during this event the ore bearing veins were sheared and displaced during early tertiary northwest trending dextral strike slip faulting along the osburn fault and related structures of the lewis and clark line

oxygen and hydrogen isotope geochemistry of the star morning mine coeur d alene mining district idaho oxygen isotope values of vein quartz from the star morning mine range from 13 2 per thousand to 16 2 per thousand relative to standard mean ocean water calculated isotopic values of water in equilibrium with the vein quartz at 325 degree c range from 7 2 per thousand to 10 2 per thousand the delta sup 18 o sub quartz values decrease with depth in the mine the delta d values of quartz inclusion fluids range from minus 18 per thousand to minus 105 per thousand and do not significantly correlate with depth oxygen isotope values of belt supergroup whole rock samples range from 13 8 per thousand to 16 8 per thousand the data indicate that the fluids were a mix of metamorphic water released from the belt rocks during low grade metamorphism and sup 18 o shifted meteoric water