a mass change model for the estimation of debris flow runout we analyzed the runout potential of debris flows using a simple mathematical model based on the principle of conservation of momentum this model is unique in that it evaluates the effect of a change in mass of a debris flow over the distance the flow travels the model is used to examine the influence of viscous resistance alone the paired influence of a change in mass of the flow with travel and viscous resistance and finally the combined effects of mass change viscosity friction and slope angle on the longitudinal velocity distributions and runout distances of debris flows evaluations of the model with the combined influences of each of the variables indicate that a gain in mass by the flow with travel will result in longer total runout distances and that the flow will maintain lower velocities over the distance traveled a loss of mass with travel will result in shorter total runout distances and the flow will maintain higher velocities over the distance traveled increasing slope angles allo

geochemical and oxygen isotope signature of sea floor alteration associated with a polydeformed and highly metamorphosed massive sulfide deposit ruostesuo central finland massive sulfide deposits in the vihanti pyhasalmi district central finland are hosted by a highly deformed and metamorphosed bimodal volcanic sequence alteration zones that envelop these deposits are composed of cordierite orthoamphibole garnet bearing rocks referred to as cor rocks belonging to upper amphibolite to granulite facies outcrops of mafic and felsic cor rocks mcor and fcor in the vicinity of the ruostesuo zn cu deposit define mappable layers with distinctive metamorphic mineral assemblages orthoamphibole cordierite plagioclase quartz m1cor garnet orthoamphibole cordierite plagioclase quartz m2cor quartz cordierite biotite orthoamphibole cummingtonite garnet plagioclase f1cor and quartz cordierite garnet sillimanite f2cor these rocks are interlayered with or grade into typical amphibolites i e hornblende plagioclase and quartz plagioclase bearing rocks that are interpreted as least altered mafic and felsic metavolcanic rocks respectively whole rock geochemical data for least altered metavolcanic rocks and cor rocks at ruostesuo define three mafic suites primitive basalts basaltic andesites and ferrobasalts and two felsic suites r1 and r2 rhyolites using a combination of high field strength element ratios and rare earth element profiles cor rocks can be assigned to all five volcanic suites calculated mass changes for the majority of exposed cor rocks at ruostesuo are similar to those reported for chlorite quartz assemblages found within the inner core of alteration pipes located below some sea floor massive sulfide deposits relative to least altered precursors mafic cor rocks have gained fe mg s and lost variable amounts of si ca na k rb ba sr and eu which resulted in an average net mass loss of about 10 percent the bulk composition of most altered mafic cor rocks near total loss of ca na k reflects the proportion of chlorite to quartz within the premetamorphic alteration assemblages and the composition of the chlorite mass change results for altered mafic rocks indicate that basalts at ruostesuo were altered by an evolved fe rich hydrothermal fluid at high water rock ratios mass changes for cor rocks of the r2 felsic volcanic suite are similar to those of the mafic rocks enriched in fe mg and depleted in ca na k rb ba sr and eu except for significant additions of si that resulted in net mass gains of 20 to 30 percent felsic cor rocks of the r1 volcanic suite show gains in k rb and ba that are attributed to the formation of premetamorphic sericite during an alteration stage dominated by hydrothermal seawater in comparison to least altered metavolcanic rocks mafic and felsic cor rocks are depleted in 18o with delta 18o values 2 to 5 per mil lower than precursor rocks estimated temperatures of alteration were 270 to 350 c these data indicate that the signature of a high temperature 300 c sea floor hydrothermal upflow zone is preserved within upper amphibolite to granulite facies rocks at ruostesuo the stratigraphic boundary between strongly chloritized mafic volcanic rocks and silicified felsic volcanic rocks marks a transition from net mass losses associated with hydrothermal fluid dominated alteration to net mass gains associated with seawater dominated alteration silicification at or near the boundary between mafic and felsic volcanic rocks may have been the result of conductive cooling or mixing with seawater from above in the absence of textural or crosscutting relationships indicative of a younging direction a stratigraphic model is proposed on the basis of the above geochemical constraints altered basalts at ruostesuo represent the exposed base of a chloritic stockwork zone that passes upsection into altered felsic volcanic rocks that host massive zn cu sulfides this stratigraphic model has significance for the interpretation of other massive sulfide deposits in the vihanti pyhasalmi district and exploration strategies that couple chemostratigraphy with mass change results more significantly the preservation of premetamorphic oxygen isotope values for strongly metamorphosed and locally migmatitic cor rocks indicate that oxygen isotope mapping is a viable exploration tool in the district and in other mineralized upper amphibolite to granulite facies terranes worldwide

quality ranking of twelve columnar basalt occurrences in the northern portion of the parana basin brazil this paper presents results obtained from a study of basal degrading conducted on samples of basaltic rocks found in the northern part of the parana basin in the state of sao paulo brazil to meet the objectives of the study natural and accelerated alteration tests were carried out followed by a comparison of the quantitative analysis of the two alteration processes the combined analysis of the information proved to be very useful tool for rock qualification and the quantification of alterability thus providing a basis for comparative analysis of massive and columnar jointed basalt relative to their use as aggregate for civil construction purposes

alteration characteristics of the archean golden grove formation at the gossan hill deposit western australia induration as a focusing mechanism for mineralizing hydrothermal fluids the archean golden grove formation is a 550 m thick rhyodacitic tuffaceous volcaniclastic succession that hosts the cu zn rich gossan hill volcanic hosted massive sulfide vhms deposit in the yilgarn craton western australia the golden grove formation consists of volcanic quartz and altered pumice and shards which were deposited during successive episodes of subaqueous mass flow coherent volcanics are absent from the golden grove formation at gossan hill but form the main rock type in the hanging wall scuddles formation a massive dacite dome that overlies its volcanic feeder dike is inferred to occupy a synvolcanic structure that focused mineralizing fluids during the formation of the gossan hill deposit the gossan hill deposit consists of two stratigraphically separate ore zones interconnected by stockwork the cu rich lower ore zone and the zn rich upper ore zone occur in the middle and upper parts of the golden grove formation respectively podiform zones of massive magnetite occur in the cu rich ore zone where the formation of magnetite predates massive sulfide the asymmetry of massive sulfide massive magnetite and alteration zones at the gossan hill deposit attest to synvolcanic structural control during mineralization the principal lithofacies of the golden grove formation are sandstone and pebble breccia which have a regionally extensive quartz fe rich chlorite and lesser muscovite alteration at gossan hill this alteration has resulted in near complete replacement of tuffaceous components causing substantial chemical modification of the primary lithologies quartz chlorite muscovite alteration is characterized by severe k2o na2o and cao depletion with rocks consisting principally of sio2 feo al2o3 and mgo along a quartz chlorite mixing trend widespread preservation of pumice and shard volcanic textures within the golden grove formation indicates that quartz chlorite muscovite alteration occurred soon after or possibly during sedimentation the absence of diagenetic compaction textures further suggests induration of the succession during this early alteration stage with the tuffaceous succession largely sealed from the texturally destructive effects of subsequent hydrothermal alteration except where mineralizing fluids were locally channeled along synvolcanic feeder conduits local intense hydrothermal alteration zones surround the gossan hill deposit and overprint earlier quartz chlorite muscovite alteration these local alteration zones have the same extent as the sulfide vein envelope and represent hydrothermal alteration formed during sulfide magnetite mineralization intense fe rich chlorite ankerite siderite alteration occurs as a strata bound envelope around massive magnetite cu rich veins and massive sulfide in the lower ore zone this chlorite rich alteration has strong feo and mgo enrichment with minor chloritoid and andalusite that reflect intense acid leaching during hydrothermal alteration iron chlorite ankerite siderite alteration grades upward into discordant to strata bound intense quartz alteration intense quartz alteration forms an envelope around zn rich veins and massive sulfide in the stockwork and upper ore zone the trend from fe chlorite ankerite siderite to quartz alteration toward the top of the deposit is consistent with the cooling of hydrothermal mineralizing fluids nearing the sea floor rhyodacite and dacite volcanics of the hanging wall scuddles formation have a pervasive muscovite calcite alteration muscovite calcite alteration led to na2o depletion and cao and k2o enrichment associated with burial of the gossan hill mineralizing system we propose that the gossan hill sulfide magnetite vhms deposit formed during an evolving archean hydrothermal system that began as part of a regional scale low temperature seawater convection alteration system initially this system caused extensive replacement of the golden grove formation by quartz and fe chlorite muscovite a process that sealed and indurated the volcaniclastic rocks by infilling of primary porosity and permeability structures due to subsequent impermeability of the host rock succession later and hotter mineralizing fluids that generated alteration and massive magnetite and sulfide at the gossan hill deposit were constrained to and focused upward along a synvolcanic feeder structure

numerical study on the entrainment of bed material into rapid landslides the entrainment of channel path material plays an important role during runout of many rapid landslides such a mechanism is able to change the mobility of a flow significantly through rapid chang

geodynamic setting crustal architecture and vms metallogeny of ca 2720 ma greenstone belt assemblages of the northern wawa subprovince superior province the greenstone belts along the northern margin of the wawa subprovince of the superior province vermilion shebandowan winston lake manitouwadge formed at ca 2720 ma and have been interpreted to be representative of a rifted arc to back arc tectonic setting despite a common inferred tectonic setting and broad similarities these greenstone belts have a significantly different metallogeny as evidenced by different endowments in volcanogenic massive sulphide vms magmatic sulphide and orogenic gold deposits in this paper we examine differences in geodynamic setting and crustal architecture as they pertain to the metallogeny of each greenstone belt by characterizing the regional scale trace element and isotopic nd and pb geochemistry of each belt the trace element geochemistry of the vermilion greenstone belt vgb shows evidence for a transition from arc like to back arc mafic rocks in the soudan belt to plume driven rifted arcs in the ultramafic bearing newton belt the shebandowan greenstone

flow of variably fluidized granular masses across three dimensional terrain 2 numerical predictions and experimental tests numerical solutions of the equations describing flow of variably fluidized coulomb mixtures predict key features of dry granular avalanches and water saturated debris flows measured in physical experiments these features include time dependent speeds depths and widths of flows as well as the geometry of resulting deposits three dimensional 3 d boundary surfaces strongly influence flow dynamics because transverse shearing and cross stream momentum transport occur where topography obstructs or redirects motion consequent energy dissipation can cause local deceleration and deposition even on steep slopes velocities of surge fronts and other discontinuities that develop as flows cross 3 d terrain are predicted accurately by using a riemann solution algorithm the algorithm employs a gravity wave speed that accounts for different intensities of lateral stress transfer in regions of extending and compressing flow and in regions with different degrees of fluidization field observations and experiments indicate that flows in which fluid plays a significant role typically have high friction margins with weaker interiors partly fluidized by pore pressure interaction of the strong perimeter and weak interior produces relatively steep sided flat topped deposits to simulate these effects we compute pore pressure distributions using an advection diffusion model with enhanced diffusivity near flow margins although challenges remain in evaluating pore pressure distributions in diverse geophysical flows riemann solutions of the depth averaged 3 d coulomb mixture equations provide a powerful tool for interpreting and predicting flow behavior they provide a means of modeling debris flows rock avalanches pyroclastic flows and related phenomena without invoking and calibrating rheological parameters that have questionable physical significance

an empirical statistical model for debris flow travel distance an empirical model is presented for analysis of debris flows based on field observations of landslides from clear cuts in the queen charlotte islands british columbia given an initial failure volume changes in event magnitude arising from entrainment and deposition along the path of movement are used to establish the point at which the cumulative flow volume diminishes to zero and therefore the total travel distance hillslope morphology is used to assign three types of flow behaviour unconfined confined and transition flow flow behaviour and slope angle determine the occurrence of entrainment or deposition in the model for every reach of the event path volume change in a reach is calculated from regression analysis of the queen charlotte islands field observations predictor variables are reach length width of entrainment and or deposition and slope angle together with a bend angle function and the incoming flow volume key words slope stability debris flow travel distance runout ris

a model for the analysis of rapid landslide motion across three dimensional terrain a new numerical model for the dynamic analysis of rapid flow slides debris flows and avalanches has been developed the model is an extension of an earlier algorithm and is implemented using a nu

depositional setting and deformation of massive sulfide deposits iron formation and associated alteration in the manitouwadge greenstone belt superior province ontario the base metal deposits of the manitouwadge greenstone belt provide a classic example of the difficulties encountered in petrogenetic studies of mineralization in complex metamorphosed and polydeformed terranes the belt comprises a mafic to felsic volcanic succession in which the felsic rocks are interleaved with iron formation and massive sulfide deposits a synvolcanic trondhjemite was a magma source for felsic volcanism and heat source for hydrothermal activity the belt was affected by four phases of ductile deformation including d 1 faulting that dissected the area of known economic mineralization into two tectonic blocks and repeated part of the mineralized sequence the regional map pattern is determined by d 3 folds including the manitouwadge synform based on cu zn pb proportions style of mineralization and relationships to iron formation and alteration zones the orebodies can be divided into three main types 1 cu rich stockwork disseminated orebodies which are the lowest in the stratigraphy hosted by the orthoamphibole garnet cordierite gneiss and in the geco mine area by sillimanite muscovite quartz schist surrounding the main orebody 2 massive and semimassive zn cu pb orebodies on iron formation horizons at middle stratigraphic levels these include the two largest orebodies of the bolt and 3 massive and semimassive zn pb cu orebodies interpreted as highest in the stratigraphy which are hosted by iron formation type 1 orebodies represent subsurface conduits for mineralizing fluids that supplied deposits higher in the stratigraphy type 2 orebodies are sea floor precipitates or near sea floor replacement deposits formed during the peak of hydrothermal activity and base metal deposition type 3 orebodies formed during waning hydrothermal activity all rocks have been metamorphosed to upper amphibolite facies including two zones of synvolcanic hydrothermal alteration orthoamphibole garnet cordierite gneiss forms a strata bound sheet of regional extent mantling synvolcanic trondhjemite in the stratigraphic footwall structural hanging wall to mineral deposits the second alteration unit sillimanite muscovite quartz schist occurs in close proximity to massive sulfide deposits mostly in the stratigraphic hanging wall structural footwall the precursors of altered units were mafic and felsic volcanic reeks despite the unusual extent and concordance of alteration zones at manitouwadge geochemical trends from least to intensely altered are similar to those recorded in alteration pipes in the abitibi camp extensive orthoamphibole bearing gneiss at manitouwadge may be partly a function of high metamorphic grade allowing orthoamphibole hornblende coexistence in relatively calcic bulk rock compositions bulk rock compositions that produced orthoamphibole bearing assemblages at manitouwadge might at a lower metamorphic grade be considered incipient alteration the strata bound character of alteration suggests that hydrothermal activity was focused on aquifer horizons consisting of permeable poorly consolidated volcaniclastic deposits

numerical modelling of entrainment deposition in rock and debris avalanches abstract rock and debris avalanches as well as debris flows are characterized by peculiar behaviour influenced by geometry of the initial failure surface topography involved materials involved and water content during their motion rock avalanches can entrain large volumes of sediments both in a dry and in a saturated state entrained dry material has generally the consequence to reduce the total landslide runout whereas entrainment of almost saturated material can have more complex consequences we use a finite element code to simulate the motion of a moving landslide mass on materials with different properties and along very sharp topographies erosion and deposition can be modelled as well as interaction with obstacles of different characteristics we present two examples of the modelling problems and capabilities we simulated the runout of a rock avalanche on a ground formed by alluvial material under dry and saturated conditions this material can be entrained and plowed by the impacting and running rock avalanche material sensitivity of the erosion and transport mechanisms has been analysed by performing different analyses the simulated case study is the 6 10 5 m 3 arvel rock avalanche 1922 switzerland for which a reliable set of pre and post failure observations is available final geometry mass redistribution velocities and runup are used to validate the model capabilities and study the effects of different material properties

structural history of the manitouwadge greenstone belt and its volcanogenic cu zn massive sulphide deposits wawa subprovince south central superior province structural analysis of the manitouwadge greenstone belt integrated with detailed mapping and geochronological and petrographic studies reveals a complex early deformation history that significant

geochemistry of metamorphosed volcanic rocks in the neoarchean qingyuan greenstone belt north china craton implications for geodynamic evolution and vms mineralization abstract the qingyuan greenstone belt qgb situated in the northeastern section of the north china craton ncc is considered to be the unique metallogenic province in china that hosts both banded iron formations bifs and volcanogenic massive sulfide vms deposits traditionally the qgb is divided into the hunbei and hunnan terranes separated by the hunhe fault and grouped into the lower shipengzi middle hongtoushan and upper nantianmen formations which have undergone amphibolite to granulite facies metamorphism exposed supracrustal rocks are composed of plagioclase amphibolite and biotite plagioclase gneiss with minor amounts of bif marble and schist in this study detailed field and petrographic observations lithogeochemical u pb geochronological as well as whole rock sm nd isotope analyses were conducted on the metamorphosed mafic and felsic volcanic rocks i e plagioclase amphibolite and biotite plagioclase gneiss respectively in the qgb in order to discuss implications for tectonic evolution and comitant vms mineralization the supracrustal rocks of both hunbei and hunnan regions were formed synchronously from 2 57 to 2 53 ga and then had undergone 2 52 2 48 ga regional metamorphism specifically the lower section of the shipengzi formation is composed dominantly of transitional tholeiitic basalts with negative nb anomalies suggesting that they were likely generated by partial melting of a mantle source that was previously altered by variable amounts of slab derived fluids or melts in contrast the lithologic assemblages grade upward into interlayered bimodal volcanic rocks i e n morb type tholeiitic basalts and fi to fii type dacites of transitional to calc alkalic affinities representing a change in tectonic regime related to subduction from compression to extension among them all the basalts are characterized by consistently positive initial nd compositions end t 2 7 to 3 4 further indicate a depleted mantle source whereas those dacites possess negative to positive initial nd values end t 4 6 to 3 0 suggesting they were formed by partial melting of depleted mafic source likely lower mafic crust and accompanied with variable addition of old crustal material significantly vms deposits are genetically linked to this extensional event and closely associated with the fii type dacites that were generated by higher melting degree at high temperature conditions and shallow crustal level likely 10 15 km in all geochemical features e g negative nb anomalies and end value together with contamination from continental crusts for tholeiitic mafic rocks and inherited zircons from these volcanic rocks imply a continental arc setting where the qgb was evolved

a mass change model for the estimation of debris flow runout a second discussion conditions for the application of the rocket equation a geology colleague dr alan benimoff brought to my attention the article on debris flow in this journal written by cannon and savage 1988 and the subsequent discussion by hungr 1990 and reply by cannon and savage the purpose of this note is to clarify and extend the discussion and also to point out a problem with cannon and savage s viscous force a reader of the journal who is unfamiliar with the problem of systems that gain or lose mass would perhaps have been confused by the discussion and reply both hungr and cannon and savage hereafter abbreviated as cs are using the same rocket equation except unfortunately they use the symbol u to mean two different things hungr uses it to denote relative velocity with respect to the main mass the rocket whereas cs use it to denote absolute velocity with respect to the ground if we denote hungr s a by uh and cs s u by ucs then uh ucs v making this replacement in hungr s eq 1 we find

composite synvolcanic intrusions associated with precambrian vms related hydrothermal systems large subvolcanic intrusions are recognized within most precambrian vms camps of these 80 are quartz diorite tonalite trondhjemite composite intrusions the vms camps spatially associated with composite intrusions account for 90 of the aggregate sulfide tonnage of all the precambrian intrusion related vms camps these low alumina low k and high na composite intrusions contain early phases of quartz diorite and tonalite followed by more voluminous trondhjemite they have a high proportion of high silica 74 sio2 trondhjemite which is compositionally similar to the vms hosting rhyolites within the volcanic host rock successions the quartz diorite and possibly tonalite phases follow tholeiitic fractionation trends whereas the trondhjemites fall within the composition field for primitive crustal melts these transitional m i type primitive intrusive suites are associated with extensional regimes within oceanic arc environments subvolcanic composite intrusions related to the archean sturgeon lake and noranda and paleoproterozoic snow lake vms camps range in volume from 300 to 1 000 km3 three have a sill morphology with strike lengths between 15 and 22 km and an average thickness between 1 500 and 2 000 m the fourth has a gross stock like shape the vms deposits are principally restricted to the volcanic strata above the strike length of the intrusions as are areally extensive thin exhalite units the composite intrusions contain numerous internal phases which are commonly clustered within certain parts of the composite intrusion these clusters underlie eruptive centers surrounded by areas of hydrothermal alteration and which contain most of the vms deposits early quartz diorite and tonalite phases appear to have intruded in rapid succession evidence includes gradational contacts magma mixing and disequilibrium textures they appear to have been emplaced as sill dike swarms these early phases are present as pendants and xenoliths within later trondhjemite phases the trondhjemite phases contain numerous internal contacts indicating emplacement as composite sills common structural features of the composite intrusions include early xenolith phases abundant small comagmatic dikes fractures and veins and in places columnar jointing internal phases may differ greatly in texture from fine to coarse grained aphyric and granophyric through seriate to porphyritic mineralogical and isotopic evidence indicates that early phases of each composite intrusion are affected by pervasive to fracture controlled high temperature 350 450 c alteration reflecting seawater rock interaction trondhjemite phases contain hydrothermal magmatic alteration assemblages within miarolitic cavities hydrothermal breccias and veins this hydrothermal magmatic alteration may in part be inherited from previously altered wall rocks two of the four intrusions are host to cu mo rich intrusive breccias and porphyry type mineralization which formed as much as 14 ma after the main subvolcanic magmatic activity the recognition of these precambrian subvolcanic composite intrusions is important for greenfields vms exploration as they define the location of thermal corridors within extensional oceanic arc regimes which have the greatest potential for significant vms mineralization the vms mineralization may occur for 2 000 m above the intrusions in some cases vms mineralization has been truncated or enveloped by late trondhjemite phases of the composite intrusions evidence that much of the trondhjemitic magmatism postdates the principal vms activity is a critical factor when developing heat and fluid flow models for these subseafloor magmatic hydrothermal systems

numerical analysis of dynamics of debris flow over erodible beds in wenchuan earthquake induced area the basal entrainment of debris flows play a significant role in its amplification and the final volume of deposition could be several to hundred times of its initial volume in this paper the shallow water equations coupled with basal material entrainment applied in debris flows have been given to demonstrate the amplification a new basal entrainment model taking advantage of both coulomb and voellmy frictional laws are proposed providing a unified formula to simulate the stop and go process of debris flows both time and space second order maccormack tvd finite difference method is suggested to solve the coupled equations numerical comparisons with usgs flume experiment and hongchun gully debris flow in wenchuan earthquake induced area are carried out to prove its effectiveness it is established that the momentum exchange term between the flows and the basal materials has a significant influence on the dynamic characteristics and the entrainment effects are essential to model the dynamic process of debris flows in an earthquake induced area c 2014 elsevier b v all rights reserved

mechanism and effect of chemical weathering of sedimentary rocks the mineralogy geochemistry and physical and mechanical properties of rocks from four weathering profiles of miocene to pleistocene mudstones and sandstones in japan showed that chemical weathering of sedimentary rocks is characterized by sequential reaction between percolating groundwater and rock forming minerals pyrite a common mineral contained in sedimentary rocks is especially important in these sequential reactions pyrite is oxidized by oxygen coming from the ground surface and sulfuric acid is generated at the base of the oxidized zone the sulfuric acid in turn dissolves rock forming materials to make a dissolved zone if the fluxes of oxygen and water are in the same direction sulfuric acid generated at the oxidation front migrates farther and forms a dissolved zone if these fluxes are in opposite directions the oxidized and dissolved zones are not differentiated rocks in the dissolved zone are caused to deteriorate by the acid leaching and are acidic if buffering minerals such as calcite and zeolite are absent in the oxidized zone sandstone is strengthened because of cementation by iron oxide or hydroxide while mudstone is weakened because it has greater clay fractions and larger specific surface areas than sandstone

erosional effects on runout of fast landslides debris flows and avalanches a numerical investigation the mechanism of mass changes in debris transportation process is an important topic in the study of fast landslides debris flows and avalanches basal erosion is recognised as a dynamic interaction between the original moving material and the entrained basal topsoil shearing along their non slip contact surface in this paper we propose a new concept of yield rate and establish the erosional relationship to bridge these two systems a pertinent mathematical model and numerical implementation are formulated parametric numerical experiments are conducted to compare the erosional effects the simulated results are consistent with available experimental and field observations the influence of the involvement of the erosive material on runout behaviour and the global mobility of the moving material are elucidated the proposed method is then employed to analyse a recent debris flow event in northern italy the excellent match to the field data gives it a plausible potential application to the analysis of this type of gravity driven flow with significant erosion defined in a dimensionless form the proposed yield rate can be estimated conveniently in general geotechnical practices

numerical simulation of debris flows a key requirement in the assessment of landslide risk in such densely populated urban areas as hong kong consists of the prediction of potential runout distance or the extent of the subsequent debris flow this paper presents a three dimensional dynamic model of unsteady gravity driven debris flow the lagrangian galerkin finite element method is used to determine the nodal velocity and depth of soil column elements within the sliding mass with the momentum and mass conservation mathematically closed within the soil column elements the numerical solution also features a lumped mass matrix and a volume weighted procedure the method of least squares approximation plays a smoothing role which enhances stability and efficiency of the numerical solution scheme the nodal elevation during sliding is obtained via a dynamic bilinear interpolation of the elevation function for the base of the sliding mass furthermore the accuracy robustness and generality of this method are validated by experimental results

erosional and mechanical strengths of deposited cohesive sediments erosion tests were run on soft cohesive sediment beds freshly deposited from a concentrated slurry in a large rotating annular flume a total of seven tests were carried out with the bed age varying between 1 8 days and 18 9 days a surface type erosion was observed for the applied shear stress range 0 1 1 pa following the increase in the water flow the erosion rate increases quickly to a peak value and then drops off to approximately zero the eroded depth was less than 8 mm for all beds but the resistance to erosion at a given depth and for a given bed structure increased with increasing bed age this phenomenon was attributed to thixotropy the erosional strength of a given sediment layer is found to be one order of magnitude lower than its undrained and drained mechanical shear strengths measured with innovative testing methods hypotheses are given to explain that difference however at constant density and soil water chemistry the erosional and mechanical strengths seem to be affected by the same factors such as bed age structure and temperature

field based experimental determination of the weathering rates of the cappadocian tuffs abstract since the last eruption in the cappadocia region that resulted in the formation of irregular hard thick lava layers on top of the cappadocian tuffs atmospheric processes have preferentially sculptured the tuffs the erosion processes have resulted in some beautiful topographical landscape features the so called fairy chimneys however erosion which is an important factor in the formation of fairy chimneys in the early stages has a negative effect on their future over time the number of visitors to this region has also increased and therefore in addition to natural erosion the effects of localized erosion resulting from tourism at the site have increased in the last few decades the physical mineralogical and mechanical properties of the cappadocian tuffs have been widely investigated in previous studies but their weathering characteristics particularly weathering rate were not determined in these studies determination of the weathering rate of these rocks is mandatory especially for conservation projects which should be urgently applied in order to protect this heritage in this study a comprehensive research program was carried out on the weathering properties of the cappadocian tuffs and the weathering rate was determined in field and laboratory investigations to this purpose a detailed field investigation was performed besides field observations the mineralogical physical and mechanical properties of tuffs were also determined in addition to durability evaluation by the slake durability index test wetting drying and freezing thawing tests were also performed for weathering rate assessment of the cappadocian tuffs in order to account for overburden load on some specific parts of pillars these wetting drying and freezing thawing tests were performed under loads the results obtained from field observations of old man made structures and from laboratory studies show that the weathering rate varies between 0 03 and 0 59 mm year for the esbelli tuff and 0 4 and 2 5 mm year for softer part of the kavak member

erosion and mobility in granular collapse over sloping beds 1 we describe laboratory experiments of granular material flowing over an inclined plane covered by an erodible bed designed to mimic erosion processes of natural flows travelling over deposits built up by earlier events two controlling parameters are the inclination of the plane and the thickness of the erodible layer we show that erosion processes can increase the flow mobility i e runout over slopes with inclination close to the repose angle of the grains r by up to 40 even for very thin erodible beds erosion efficiency is shown to strongly depend on the slope of the topography entrainment begins to affect the flow at inclination angles exceeding a critical angle c r 2 runout distance increases almost linearly as a function of the thickness of the erodible bed suggesting that erosion is mainly supply dependent two regimes are observed during granular collapse a first spreading phase with high velocity followed by a slow thin flow provided either the slope or the thickness of the erodible bed is high enough surprisingly erosion affects the flow mostly during the deceleration phase and the slow regime the avalanche excavates the erodible layer immediately at the flow front waves are observed behind the front that help to remove grains from the erodible bed steep frontal surges are seen at high inclination angles over both rigid or erodible bed finally simple scaling laws are proposed making it possible to obtain a first estimate of the deposit and emplacement time of a granular collapse over a rigid or erodible inclined bed

anatomy of a pennine peat slide northern england this paper describes and analyses the structure and deposits of a large uk peat slide located at hart hope in the north pennines northern england this particular failure is unusual in that it occurred in the winter february 1995 and shows excellent preservation of the sedimentary structures and morphology both at the failure scar and downstream the slide was triggered by heavy rain and rapid snowmelt along the line of an active peatland stream flush detailed mapping of the slide area and downstream deposits demonstrate that the slide was initiated as a blocky mass that degenerated into a debris flow the slide pattern was complex with areas of extending and compressive movement a wave like motion may have been set up in the failure within the slide site there was relatively little variability in block size b axis however downstream the block sizes decrease rapidly stability analysis suggests the area at the head of the scar is most susceptible to failure a secondary slide area is thought to have only been initiated once the main failure had occurred estimates of the velocity of the flowing peat mass as it entered the main stream channel indicate a flow velocity of approximately 10 m s 1 which rapidly decreases downstream a sediment budget for the peat slide estimates the failed peat mass to be 30 800 t however sediment delivery to the stream channel was relatively low about 37 of the failed mass entered the stream channel and despite moving initially as debris flow the amount of deposition along the stream course and on the downstream fan is small only about 1 the efficiency of fluvial systems in transporting the eroded peat is therefore high copyright 2003 john wiley sons ltd

3d modelling and sheath folding at the falun pyritic zn pb cu au ag sulphide deposit and implications for exploration in a 1 9 ga ore district fennoscandian shield sweden the falun pyritic zn pb cu au ag deposit situated in the palaeoproterozoic 1 9 1 8 ga bergslagen lithotectonic unit in the south western part of the fennoscandian shield is one of the major b

a dynamic model for rainfall induced landslides on natural slopes assessment of landslide hazard often requires a good knowledge of the landslide characteristics and runout mechanics in this paper a quasi three dimensional model using lagrangian finite element method lfem is formulated to reproduce the dynamic runout process caused by landslides a case study of rainfall induced landslide on a natural slope in 1993 in lantau island hong kong is presented voellmy rheology is adopted to characterize the multi dimensional runout behaviour for engineering applications the selection of appropriate rheology and the determination of relevant key parameters associated with the failure mechanisms and runout mechanics are highlighted details of the mathematical formulation particularly with respect to the stability of the numerical scheme and quality control of the mesh are provided the close correlation between the calculation results and the field observations shows that if an appropriate rheological relationship is selected for the simulation a reasonable description of the runout behaviour can be obtained using the present model implications of the potential hazard from natural terrain landslides to downslope development are also discussed used in conjunction with geographical information system gis database the model can also be applied to the preliminary hazard zoning of terrain and land use management in mountainous areas

evaluation of the viscosity of tropical soils for debris flow analysis a new approach to analyse the debris flow type of landslides it is necessary to know the viscosity of the fast moving soil mass such rheological parameters are important in the evaluation of characteristics of propagation of the movement downhill this paper presents a proposal for the assessment of soil viscosity based on a modified set up of the well known concrete slump test through the definition of shearing rates in the slump tests soil viscosity was determined on a plate plate rheometer four natural soils from rio de janeiro brazil with differing grain size distribution and plasticity were used in the investigation the results obtained are compared with experimental data from the literature and show that care must be taken in defining viscosities based only on data related to grain size correlations between soil moisture and shearing rates defined in the modified slump tests and viscosity defined in the rheometer tests were obtained as a result a fairly good relationship between shearing rate and v

weathering geomorphology texts 2 cliff ollier 1984 longman group ltd essex england 2d ed 270 pp stg 11 50 paperback

momentum transfer and friction in the debris of rock avalanches discussion the authors address an old and stubborn problem unfortunately their 2 assumed from previous work by others leads to incorrect conclusions the kinetic energy k of the slide mass as it enters the runout surface equals 1 2 v i where m is the slide mass and vo is the entry velocity the work energy theorem demands that the change in kinetic energy during the runout from k to zero must equal the total work w done by the external forces it can easily be shown that w equals the first moment of volume of the slide deposits with respect to the starting point of runout times material density times the constant g sin 8 p cos 8 here 8 is the constant slope angle of the runout surface and p is the friction coefficient therefore defining l as the final displacement of the centre of gravity of the deposits i w m l g s i n 0 p c o s 8 k from this

application of high field strength elements to discriminate tectonic settings in vms environments high field strength element ratios in felsic volcanic rocks reflect the tectonomagmatic evolution of a region th ta th hf ta hf th yb and ta yb ratios collectively help to define the tectonic environment of volcanism separating oceanic arcs active continental margins and within plate volcanic zones on the basis of the above empirical observations the tectonic environments of selected archean and post archean volcanogenic massive sulfide deposits were reexamined published data sets plotted on discriminant diagrams represent twelve volcanogenic massive sulfide vms deposits from two distinct tectonic environments the volcanic rocks of the kuroko deposits japan san nicolas mexico and bathurst new brunswick canada plot within the active continental margin field on all diagrams whereas volcanic rocks from archean deposits of the superior province canada kidd creek kamiskotia geco winston lake mattabi lyon lake noranda selbaie and south bay plot in the within plate volcanic zone field the discriminant diagrams demonstrate that although the chemical character of rhyolites has not changed significantly since the archean the range of geotectonic setting of vms deposits probably has it is suggested that archean deposits most likely formed in an ensimatic rift environment whereas post archean deposits formed in subduction related rift zones of arc environments subduction related rhyolites of vms deposits are variably enriched in th and the light rare earth elements with respect to ta nb and the heavy rare earth elements

the effect of slope length on the amount and size distribution of eroded silt loam soils short slope laboratory experiments on interrill erosion abstract the data of rainfall simulation experiments on a sandy loam and a loamy sand were compared to assess the effect of slope length on the soil loss from short slopes between 0 3 and 0 9 m the total soil loss and the aggregate size distribution in the total soil loss were determined after 90 min of rainfall with rainfall intensities between 22 0 and 78 5 m h 1 the experimental results indicated that the slope length effect is different for the two soils although for both soils the total soil loss increased with increasing slope length the soil loss per unit slope length increased with increasing slope length only for the sandy loam soil 1 and decreased with increasing slope length for the loamy sand soil 2 the difference in slope length effect between the two soils was also reflected in the aggregate size distribution in the soil loss the different aggregate sizes displayed different relationships between soil loss and slope length for the loamy sand the slope length effect was less for the large aggregate sizes which contained more sand than the original soil for both soils the slope length effect was most pronounced for the aggregate sizes smaller than 0 05 mm

erosion of fluid mud layers ii experiments and model validation a study on the erosion of soft mud layers caused by entrainment is reported experiments were carried out in an annular flume with suspensions of kaolinite and natural mud the results of these experiments compare favorably with the results of an integral entrainment model described in a companion paper it can be concluded that the initial entrainment process of fluid mud is identical to the entrainment process of two fluid systems that is the upper part of the fluid mud behaves as a viscous fluid during this initial phase the entrainment rate may be affected by the time scale for boundary layer development at a later phase the entrainment process is hindered by the work required to keep the sediment in suspension and by the strength of the bed accounted for by treating the mud as a bingham plastic values for the settling velocity the yield strength and the viscosity used in the model to obtain a fair agreement with the experiments are comparable to those obtained from independent measurements

thermo tectonic evolution of an archean accretionary complex u pb geochronological constraints on granulites from the quetico subprovince ontario canada abstract u pb geochronological data have been obtained for a granulite zone in the quetico subprovince an archean accretionary complex of the superior province north of manitouwadge ontario canada this granulite zone represents the culmination of a low pressure high temperature regional metamorphism in the quetico subprovince and an apparent continuation of a northward increase in metamorphic grade in the wawa subprovince and across the quetico wawa boundary a u pb zircon age of 2666 1 ma from a concordant magnetite bearing granitic pegmatite in the quetico granulite zone is consistent with the inferred timing of regional metamorphism in amphibolite facies zones 2671 2665 ma and indicates that the low pressure high temperature metamorphism in the quetico subprovince commenced during the main compressional deformation titanite in a calc silicate rock from low leucosome fraction layered migmatites that might represent incipient melting gave a 207pb 206pb age of 2658 1 ma the timing of the granulite facies metamorphism is constrained by u pb zircon ages of 2650 2 and 2651 3 ma from mafic granulite and garnet bearing tonalitic leucosome respectively that are similar to reported u pb ages for mafic granulites in the upper levels of the kapuskasing structural zone the present u pb data suggest a diachronous development of peak metamorphic conditions of the regional metamorphism in the quetico and wawa subprovinces this diachronous development and the zonal distribution of the regional metamorphism are probably related to oblique collision at a convergent plate margin and differential rates of erosional uplift away from the quetico wawa boundary

forecasting hazard scenarios and implications for the evaluation of countermeasure efficiency for large debris avalanches abstract the key objective of a slope failure study is to reduce deaths injuries and property damage predictions of slope failures are mandatory to reduce hazard and vulnerability of elements at risk with appropriate warning policy and properly designed countermeasures numerical modelling has been recently used as an approach to back analyse real events but few attempts have been carried out to forecast potential failure scenarios recently a debris avalanche involving about 1 2 million m 3 of debris and a nearby debris slide flow with failure volume of 0 1 million m 3 occurred in the italian prealps from the accumulation of a paleo landslide field surveys and monitoring revealed that the upper part of the slope above the largest recent landslide is unstable with a possible failure volume between 1 and 1 5 million m 3 we conducted comprehensive fieldwork and analyses including geological and geomorphological surveys compilation of a landslide inventory map collection of rainfall records study of triggering mechanisms and geotechnical properties of the failed materials slope stability analyses and back analyses of the runout phase of the landslide events through a series of slope stability analyses the possible failure volume sliding surface and topography are estimated consistent with field monitoring data furthermore with the help of calibration through back analyses of the past landslide events we assign a given degree of danger to slope elements with analogous conditions we then numerically predict the runout patterns and mobility of the potential instabilities the effectiveness of the planned passive countermeasures for potential zoning management is evaluated

cordierite gedrite rocks from the central metasedimentary belt boundary thrust zone grenville province ontario mesoproterozoic metavolcanic rocks with affinities to the composite arc belt cordierite gedrite rocks in the southern grenville province occur near the base of the central metasedimentary belt boundary thrust zone interpreted by some as a crustal suture between the 1 29 1 24 ga composite arc belt and 1 4 ga rocks of laurentia major and trace element compositions of these rocks are consistent with volcanic protoliths that range in composition from basalt to dacite these cordierite gedrite rocks have low cao average 1 2 wt and major element and oxygen isotope ratios suggestive of hydrothermal alteration before metamorphism rare earth element ree compositions also indicate igneous protoliths although some ree patterns have been modified by local melt extraction the trace element compositions of cordierite gedrite rocks and neodymium isotope systematics are similar to those of metavolcanic rocks in the composite arc belt and are consistent with the extension of the composite arc belt to the base of the boundary thrust zone

interplay of rheology and entrainment in debris avalanches a numerical study flow type landslides are a major global hazard they occur worldwide and are responsible for a large number of casualties significant structural damage to property and infrastructure and economic losses the features of debris avalanches are particularly important as they involve open slopes and affect triangular source areas when initial slides turn into avalanches through further failures or eventual soil entrainment in this paper the propagation stage of debris avalanches is numerically modelled to provide information such as the propagation pattern of the mobilized material and its velocity thickness and run out distance the use of a depth integrated model has the following advantages i it adequately accommodates the irregular topography of real slopes which greatly affects the evolution of the propagation stage and ii it is less time consuming than full three dimensional approaches the model is named geoflow sph and has previously been applied to theoretical experimental and re

weathering rates of fine pebbles at the soil surface in karkevagge swedish lapland abstract in 1994 nylon mesh bags containing 6 2 mm diameter fragments of either freshly crushed dolomite or granite were placed on meadow solifluction meadow birch heath and alpine tundra vegetation that cover surfaces within karkevagge a glaciated arctic alpine valley in swedish lapland each vegetation category contained three replicate sites comprising one bag of each rock type in 1995 the study was extended to dryas heath and willow two sites only surfaces percentage annual weight loss was used as a metric of chemical weathering rates one site in each of the 1994 categories was measured in 1995 all sites were measured in 1999 two dolomite and granite standards stored in the laboratory and subjected to identical cleaning and weighing regimes to the field samples exhibited no more than a 0 24 total weight loss after 5 years the percentage weight loss in the subgroup examined after 1 year dolomite 0 54 year granite 0 41 year significantly exceeded the average annual loss for the subsequent 4 years in all cases dolomite 0 40 year granite 0 07 year ten sites with a 5 year record had a mean annual loss of 0 326 0 115 year two standard errors for dolomite and 0 121 0 020 year for granite assuming an exponential decay model a 0 326 year rate of loss produces a half life of approximately 212 years and a 0 121 year loss rate a half life of approximately 570 years kruskal wallis one way anova on rank ordered data determined significant differences in dolomite pebble mass loss between the dryas heath and willow plus meadow microenvironments as well as between the birch forest and the willow plus meadow microenvironments the underpinning factor behind these differences appears to be moisture differences a similar test failed to determine statistically significant differences for the granite pebbles dolomite appears to be a viable medium for determining mass loss rates over quite modest time periods providing that the number of samples is sufficiently large

geological evolution of the manitouwadge greenstone belt and wawa quetico subprovince boundary superior province ontario constrained by u pb zircon dates of supracrustal and plutonic rocks fifty million years of archean evolution is recorded in the manitouwadge greenstone belt and the wawa quetico boundary region from ca 2720 ma volcanism and subvolcanic plutonism associated with m

a model for the runout analysis of rapid flow slides debris flows and avalanches runout analyses are used for risk assessment and design of remedial measures against rapid landslides such as debris flows debris avalanches rockslide avalanches large scale liquefaction failure

moisture content pore water pressure and wetting front in granite residual soil during collapsing erosion with varying slope angle abstract collapsing erosion is very severe in subtropical regions that are covered extensively by granite residual soil however detailed information about hydraulic responses during collapsing erosion especially for different slope angles remains unclear therefore to control collapsing erosion it is important to attain a more comprehensive understanding of the complex hydraulic responses due to rainfall in this study an artificial rainfall simulator and an experimental device were used to evaluate the collapsing erosion process with particular consideration of the influence of slope angle flume experiments using three slope angles 0 10 and 20 were performed under artificial rainfall this study explored the evolutions and hydraulic responses of collapsing erosion of granite residual soil by simultaneously monitoring moisture content pore water pressure and wetting front during heavy rainfall the results showed that collapsing erosion occurred faster with steeper slope angle collapse occurred in an upslope direction when the corresponding moisture content of the soil was between 30 and 40 pore water pressure increased until the development of collapsing erosion but was released when the soil mass collapsed the descending process of the wetting front on a gentle slope and a steep slope can be divided into two stages and three stages respectively this study presents an improved characterization of collapsing erosion and provides valuable evidence for slope angle impacts on infiltration events during collapsing erosion under heavy rainfall

debris flows some physical characteristics and behaviour field observations on 449 debris flows in the queen charlotte islands british columbia are summarized movement of debris is classified according to seven characteristic types designated for the purposes of the study data on the physical characteristics of the events are presented an analysis of the data is made with reference to event initiation yield and deposition using both mechanistic and morphological criteria for those events which initiate on an open slope the infinite slope model is used to establish a relationship between field drainage class and slope angle for assumed frictional and cohesive soil strength parameters the field drainage classes are directly related to the postulated location of the groundwater surface within the depth of the rupture plane deposition of channelized events is found to be influenced by the ratio of channel width to channel gradient with the onset of deposition expected when the ratio exceeds unity five classes of depositional area are proposed the mag

subsea floor replacement in volcanic hosted massive sulfide deposits abstract recent research on volcanic hosted massive sulfide vms deposits indicates that syngenetic subsea floor replacement ores form an important component of many deposits in the context of vms deposits subsea floor replacement can be defined as the syn volcanic formation of sulfide minerals within pre existing volcanic or sedimentary deposits by infiltration and precipitation in open spaces fractures inter and intra granular porosity as well as replacement of solid materials there are five criteria for distinguishing subsea floor replacement in massive sulfide deposits 1 mineralized intervals are enclosed within rapidly emplaced volcanic or sedimentary facies lavas intrusions subaqueous mass flow deposits pyroclastic fallout 2 relics of the host facies occur within the mineral deposit 3 replacement fronts occur between the mineral deposit and the host lithofacies 4 the mineral deposit is discordant to bedding and 5 strong hydrothermal alteration continues into the hanging wall without an abrupt break in intensity criteria 1 3 are diagnostic of replacement whereas criteria 4 and 5 may suggest replacement but are not alone diagnostic because clastic sulfide ores contain accessory rock fragments collected by the parent sediment gravity flow s during transport criteria 2 can only be applied to massive semi massive disseminated or vein style deposits and not clastic ores the spectrum of vms deposit types includes deposits that have accumulated largely subsea floor and others in which sedimentation and volcanism were synchronous with hydrothermal activity and precipitation of sulfides occurred at and below the sea floor over the life of the hydrothermal system deposits that formed largely subsea floor are mainly hosted by syn eruptive or post eruptive volcaniclastic facies gravity flow deposits water settled fall autoclastic breccia however some subsea floor replacement vms deposits are hosted by lavas and syn volcanic intrusions sills domes cryptodomes burial of sea floor massive sulfide by lavas or sediment gravity flow deposits can interrupt sea floor mineralization and promote subsea floor replacement and zone refining the distance below the sea floor at which infiltration and replacement took place is rarely well constrained with published estimates ranging from less than 1 to more than 500 m but mainly in the range 10 200 m the upper few tens to hundreds of metres in the volcano sedimentary pile are the favoured position for replacement as clastic facies are wet porous and poorly consolidated in this zone and at greater depths become progressively more compacted dewatered altered and less amenable to large scale infiltration and replacement by hydrothermal fluids furthermore sustained mixing between the upwelling hydrothermal fluid and cold seawater is regarded as a major cause of sulfide precipitation in vms systems and this mixing process generally becomes less effective with increasing depth in the volcanic pile the relative importance of subsea floor replacement in vms systems is related principally to four factors the permeability and porosity patterns of host lithofacies sedimentation rate the relative ease of replacement of host lithofacies especially glassy materials and early formed alteration minerals during hydrothermal attack and physiochemical characteristics of the hydrothermal fluid

age and tectonic setting of the jingangku besshi type volcanogenic massive sulfide deposit from the northern shanxi north china craton abstract the jingangku volcanogenic massive sulfide deposit is one of the largest archean deposits in china it is located in the wutai greenstone belt in the northern part of the central orogenic belt in the north china craton the deformed deposit is hosted in a suite of neoarchean metamorphosed volcano sedimentary rocks mica quartz schist plagioamphibolite plagioclase schist and bif the orebodies are characterized by massive pyrite and contain varied amounts of chalcopyrite pyrrhotite and sphalerite the country rock of the jingangku vms ores shows intense chloritization silicification sericitization and carbonation the vms hosted pyrite and copper deposit is represented by the jingangku deposit that yielded a la icp ms zircon age of 2500 15 ma mswd 0 87 the other two vms hosted pyrite and copper deposits are represented by the houping and haoditang deposits that formed between 2494 ma and 2507 ma the late neoarchean vms deposits can be interpreted to have formed in a forearc setting and subsequently tectonically transported in melange belts during continental collision quite similar to the younger besshi type deposits in japan analyses of fluid inclusions from ore bearing magnetite quartzite showed the composition of metamorphic fluid to be h2o nacl co2 ch4 n2 h2 the analysis also showed that during the peak of metamorphism the fluid was characterized by medium high temperature 322 473 and low salinity 2 2 6 74 sulfide orebodies are closely associated with the magnetite quartzite and therefore it is proposed that both the sulfide and magnetite quartzite were derived from the same material source and have the same formation age and underwent the same history of deformation and metamorphism consequently the jingangku deposit most likely formed from submarine exhalative sedimentation and later superimposed and transformed by metamorphic fluid

an unusually large debris flow at hummingbird creek mara lake british columbia on 11 july 1997 a very large debris flow occurred at hummingbird creek mara lake british columbia long term antecedent precipitation was record breaking whereas short term precipitation at salm

momentum transfer and friction in the debris of rock avalanches when a mass of loose dry purely frictional material slides down an incline after release at a given velocity the runout the distance the centre of gravity of the displaced mass moves from its initial position depends on momentum transfer within the mass this can be estimated from the profile of the debris accumulation which also allows more accurate calculation of apparent angles of sliding friction in rockfall avalanches the apparent extreme mobility of the elm and frank slides typical rockfall avalanches is explained by momentum transfer in a loose dry purely frictional material with an angle of friction of 30 key words mass wasting momentum transfer landslide accumulation rock avalanche runout distance

measurements of erosion of undisturbed bottom sediments with depth a unique flume that measures the erosion of sediments at high shear stresses and with sediment depth has been designed constructed and used experiments in this flume sedflume can be done either with reconstructed sediments or with relatively undisturbed sediments from the field with either kind of sediment two different types of experiments can be conducted the first type determines the critical stress for erosion of the sediment as a function of depth while the second type determines the erosion rate of the sediment as a function of both shear stress and depth measurements of the erosion rates of sediments from the trenton channel of the detroit river in michigan and the lower fox river in wisconsin were made by use of sedflume at sediment depths up to 2 m representative results of these measurements are presented here these results demonstrate the capabilities of sedflume and also illustrate the large differences in erosion rates at different sites and the large variations in erosion rates with depth and as a function of shear stress

archaean crustal growth processes in southern west greenland and the southern superior province geodynamic and magmatic constraints abstract eo to mesoarchaean greenstone belts e g 3800 3700 ma isua c 3075 ma ivisaartoq 3071 ma qussuk occur within orthogneisses of the southern west greenland craton greenstone belts are composed mainly of metavolcanic rocks with minor ultramafic and sedimentary schists compositionally volcanic rocks are dominantly tholeiitic basalts boninites and picrites with minor intermediate to felsic volcanic rocks these greenstone belts appear to have formed in convergent margin geodynamic settings detailed field observations contrasting ages and metamorphic and structural histories suggest that this craton was assembled in several accretionary tectonothermal events involving accretion of arcs back arcs forearcs and continental fragments by horizontal tectonics the superior province of canada was also built by the amalgamation of oceanic and continental fragments ranging in age from 3700 to 2650 ma during five discrete tectonothermal events over 40 ma between 2720 and 2680 ma the neoarchaean 2750 2670 ma wawa greenstone belts are composed of tectonically juxtaposed fragments of oceanic plateaux oceanic island arcs back arcs and siliciclastic trench turbidites following juxtaposition these diverse lithologies were collectively intruded by syn to post kinematic granitoids with subduction zone geochemical signatures oceanic island arc lavas are easily distinguished from oceanic plateau counterparts because they possess positively fractionated rare earth element la sm cn 1 and gd yb cn 1 and high field strength element depleted nb th pm pm c 1000 km scale subduction accretion complex that formed along an intra oceanic convergent plate margin during trenchward migration of the magmatic arc axis several first order geological observations on archaean greenstone belts of sw greenland and the superior province suggest that phanerozoic style plate tectonic models can provide an elegant explanation for their structural lithological metamorphic and geochemical characteristics

time dependent physicomechanical behavior of ballasts used for railway between sabuncupinar and kutahya in western turkey geomaterials used in engineering projects and man made structures naturally weather as a result of various physicochemical factors due to their long term exposure to environmental conditions geomaterials used for these purposes provide important information for understanding the effect of weathering processes on their time dependent physical mineralogical and mechanical changes since 1920s ballasts have been extracted from a quarry composed of volcanic rocks and located in sabuncupinar town to construct a railway between kutahya and this town in western turkey in present study a research was carried out on leftover and used ballasts and block samples taken from this site to assess their weathering properties in terms of time dependent durability and stability characteristics the weathering process originated mineralogical and chemical variations of collected samples were identified by microscopic studies scanning electron microscopy sem with energy dispersive x ray spectroscopy system eds and x ray diffraction xrd techniques based on sem eds analyses it resulted evident that the fe content increases in weathering rind of ballasts in comparison with their relatively fresh parts although environmental conditions caused weathering rinds of 2 2 5 mm in the outer part of ballasts within 90 5 years the petrographic and xrd analyses reveal a significant similarity between relatively fresh and weathering rinds of ballast in terms of mineralogical composition however despite that mineralogical similarity the effect of time dependent weathering processes was obviously seen from the results of slake durability and los angeles abrasion tests performed on ballasts extracted in 1965 5 and exposed to environmental conditions since that time

causative mechanisms of rainfall induced fill slope failures slope failures in fill slopes formed by loosely compacted completely decomposed granite in hong kong occur commonly during intense tropical rainstorms the stress path greatly influences the shear strength of the soil mass and is therefore crucial to the identification of slope failure mechanisms the soil mass in this case is largely unsaturated in situ hydrologic response to rainstorms indicates that soil suction is reduced by rainfall infiltration which often becomes the triggering factor in initiating slope instability the constant dead load tests on unsaturated loosely compacted completely decomposed granite appropriately simulate the field stress path of rainfall induced fill slope failure by reducing suction the tests indicate that matric suction contributes to the dilative or contractive behavior of the unsaturated soils the anisotropically consolidated undrained triaxial tests demonstrate the consistently contractive behavior of the specimens on this basis we delineate the in situ stress conditions leading to the initiation of rainfall induced fill slope failure and the stress paths of the transformation from local failures to flowage based on a systematic study of fill slope case records in hong kong implications of such mechanisms on fill slope stability are given

quantitative analysis of debris torrent hazards for design of remedial measures debris torrents which are rapid flows of soil and organic debris down steep mountain channels are a major natural hazard in many parts of british columbia a series of recent occurrences along the

evidence of basal erosion and shearing as mechanisms contributing the development of lateral ridges in mudslides flow slides and other flow like gravitational movements abstract the origin of lateral ridges in flow like gravitational movements is controversial four examples of movements showing lateral ridge development are examined bedwellty in south wales u k la coma and gosol in the eastern pyrenees spain and los olivares in the baetic range southern spain several trenches dug in these sites showed that lateral ridges appear related to erosion of the pre existing ground surface and that shear surfaces develop at both lateral and bottom boundaries of the moving masses textural characteristics of the basal debris at bedwellty show that pre existing ground material has been incorporated within the slide material no erosion was found where lateral ridges disappear at the toe of the movements an additional mechanism is proposed to explain the origin of the lateral ridges in relation to these erosional features erosion of the pre existing ground during the downward progression of the sliding or flowing mass contributes to both the generation and isolation of lateral ridges as the outer edges of the flowing mass move more slowly than the main mass they become progressively detached either basal erosion or failure of the ground causes the subsidence of the surface of the moving mass leaving the outer boundary materials as abandoned standing lateral ridges this mechanism of lateral ridge generation may occur simultaneously with other mechanisms in the examples presented here however the amount of basal erosion and the fact that ridges are only present where erosion occurs suggest that subsidence of the whole moving mass due to ground erosion or shearing is a critical factor for the ridge development

geotechnical properties of weak sandstones weak sandstones are here defined as having a saturated uniaxial compression strength of 0 5 20 mpa the mineralogy texture density porosity and saturated moisture content of these materials have

predicting the unconfined compressive strength of the breathitt shale using slake durability shore hardness and rock structural properties abstract compressive strength is the most widely used design parameter in the construction industry and in rock engineering for example bieniawski bieniawski z t estimating the strength of rock materials is j s afr inst min metall 1974 74 312 320 reported that mining engineers request the uniaxial compressive strength ucs more often than any other rock property however standards set for specimen preparation are very demanding therefore it is quite difficult and sometimes impossible to fulfill these requirements using weak rocks and especially shales this paper evaluates the use of the slake durability and shore hardness tests to estimate ucs based on laboratory correlations performed for this study and others and based on analysis of structural and physical material properties affecting both strength and durability

chemical imprint of highly metamorphosed volcanic hosted hydrothermal alterations in the la romaine supracrustal belt eastern grenville province quebec the la romaine supracrustal belt and the southeastern end of the wakeham group in the eastern grenville province canada host a series of pinwarian 1 50 ga felsic dominated volcanic centres metamorphosed at amphibolite to granulite facies during the grenville orogeny the centres are interpreted as being related to the emergence of rhyolitic domes in shallow marine intra arc basins within the active pinwarian continental magmatic arc high grade metamorphosed hydrothermal alteration zones are intimately associated with pyroclastic deposits composing these volcanic centres and an overlying composite amphibolite unit they comprise layers of rhyolitic metatuff bearing networks of aluminous nodules and veins migmatized garnet biotite sillimanite gneiss with well preserved volcanic fragments and mottled quartz cordierite gneiss with textures similar to those of vuggy silica facies alteration zones of ironstone carbonate and calc silicate rocks garnetite diopsidite epidosite and sulphide mineralizati

geodynamic reconstruction of the winston lake greenstone belt and vms deposits new trace element geochemistry and u pb geochronology the ca 2720 ma winston lake greenstone belt of the wawa abitibi terrane superior province is located on the northern margin of the wawa subprovince and has important regional tectonostratigraphic implications for the development of the neoarchean superior province the metallogenic importance of the belt is evident from the presence of the winston lake pick lake and zenith volcanogenic massive sulfide vms deposits however the chemostratigraphic evolution has not been fully examined at the greenstone belt scale nor have the vms deposits been examined from the perspective of the belt scale petrogenesis and volcanic reconstruction this study 1 reviews the geology and vms mineralization in the winston lake greenstone belt and 2 reconstructs its geodynamic setting and its magmatic and metallogenetic history using new geological trace element and nd isotope data constrained by new u pb geochronology the belt is subdivided into two main lithotectonic assemblages the winston lake assemblage composed of tholeiitic to calc alkalic bimodal volcanic lithofacies and the big duck lake assemblage composed of alkalic to tholeiitic mafic flows and sills the contact between the winston lake and big duck lake assemblages is intruded by the differentiated zenith gabbro which hosts the 0 16 mt zenith vms orebody as a series of xenoliths the variably altered felsic lithofacies of the winston lake assemblage host the 3 1 mt winston lake main and 1 3 mt pick lake zn rich vms deposits the felsic volcanic lithofacies of the winston lake assemblage are fiii type rhyolites and have a bimodal distribution of zr ti indicating two distinct magmas formed by different temperatures of partial melting mafic lithofacies of the winston lake assemblage are typically calc alkalic to transitional between calc alkalic and tholeiitic in composition they have arc to back arc trace element contents with distinctive negative nb and ti anomalies enrichment in the light rare earth elements lree and higher th nb ratios than the mafic rocks from the big duck lake assemblage mafic strata from the big duck lake assemblage have trace element characteristics similar to mature back arc tholeiitic basalts and oib like or oceanic plateau alkalic basalts with high nb th and ti v ratios the chemostratigraphy of the winston lake greenstone belt is consistent with a geodynamic model where arc rifting is followed by back arc development nd isotope data indicate that strata from the winston lake and big duck lake assemblages are juvenile and show no evidence of contamination by significantly older crust therefore crustal contamination signatures in the mafic flows from the winston lake assemblage must have formed by contamination from crust that is of similar age and supports a comagmatic relationship between the mafic and felsic strata the mafic flows of the big duck lake assemblage represent a mature back arc setting with evidence for enriched plume generated basalts in the upper mafic unit the winston vms deposit formed during the early rifting of the arc and the timing is tightly constrained by the hydrothermally altered 2721 2 0 9 ma vms hosting felsic strata and younger postmineralization 2719 4 ma zenith gabbro the zn dominated vms mineralization suggests that temperature of the hydrothermal fluid during discharge was relatively cool 300 c and did not maintain sufficiently high temperatures to precipitate significant amounts of copper relative to zinc this is likely due to adiabatic cooling of the fluid because of a low pressure 0 5 kb sea floor environment and or permeable volcaniclastic strata a u pb age of emplacement of 2692 1 0 7 ma from the syndeformation quartz feldspar porphyry in the big duck lake assemblage indicate it is comagmatic with syndeformation magmatic events typical of other greenstone belts along the northern margin of the wawa abitibi terrane this event is interpreted to represent the timing of terrane accretion of the wawa abitibi terrane to the superior province

routing debris flows with particle segregation a computer simulation method is developed to predict the temporal variations of debris flow discharge solids concentration and vertical mean particle size distribution a single finite step in the simulation is divided into two stages in the first stage a sediment bed composed of a well graded mixture is eroded by surface water introduced at the head of a channel thereby generating a debris flow in the second stage larger particles in the debris flow move upward because of dispersive force and are then transported forward faster than smaller particles which remain in the lower part of the flow because the velocity is slower in the lower layer another numerical simulation method is also developed to predict simultaneously the shape of the debris deposit area the distribution of the deposit thicknesses within the area and the three dimensional distribution of the mean diameters of the deposited particles both simulation methods are verified using laboratory experiments