geochemistry of leptyno amphibolite complex from haut allier french massif central abstract mafic metaigneous rocks of the leptyno amphibolite group of the french massif central in the haut allier region include amphibolites granulites and other high grade metamorphic rocks such as eclogites many granulites and eclogites were retromorphosed into amphibolite facies most rocks have basaltic compositions some amphibolites have a cumulate character and resemble oceanic gabbros amphibolites without high grade relics retain most of their original compositions typical of oceanic tholeiites including flat ree patterns zr nb 10 17 la nb 0 6 0 9 ti v 18 38 and ti zr 76 97 and were probably formed in the back arc environments the other rocks including amphibolites with high grade relics are enriched in incompatible elements such as light ree rb and ba at least partially due to secondary processes e g retrograde metamorphism effects of neighbouring granite intrusion

wave induced sediment transport and sandbar migration onshore sediment transport and sandbar migration are important to the morphological evolution of beaches but are not well understood here a model that accounts for fluid accelerations in waves predicts the onshore sandbar migration observed on an ocean beach in both the observations and the model the location of the maximum acceleration induced transport moves shoreward with the sandbar resulting in feedback between waves and morphology that drives the bar shoreward until conditions change a model that combines the effects of transport by waves and mean currents simulated both onshore and offshore bar migration observed over a 45 day period

sedfoam a multi dimensional eulerian two phase model for sediment transport and its application to momentary bed failure abstract a multi dimensional eulerian two phase model for sediment transport called sedfoam is presented the model was developed under the open source framework via the cfd toolbox openfoam with closures of particle stresses and fluid particle interactions the model is able to resolve processes in the concentrated region of sediment transport and hence does not require conventional bedload suspended load assumptions a modified k closure was adopted for the carrier flow turbulence the model was validated for reynolds averaged steady and oscillatory sheet flows and verified with empirical formulae for scour downstream of an apron the model was used to study momentary bed failure or plug flow under sheet flow conditions model results revealed the existence of instabilities of the near bed transport layer when momentary bed failure criteria was exceeded these instabilities evolved into 5 10 cm billows and were responsible for the large transport rate the instabilities were associated with a large erosion depth which was triggered by the combination of large bed shear stresses and large horizontal pressure gradients further numerical experiments confirmed the conjecture by previous studies that a criterion for onset of momentary bed failure in oscillatory sheet flow was a function of both the shields parameter and sleath parameter

petrology of garnet clinopyroxene amphibolites from mont albert gaspe quebec the mont albert mafic ultramafic complex of central gaspe quebec is generally regarded as a partial ophiolite with an underlying metamorphic sole the metamorphic rocks include a number of mineralogical and textural varieties of amphibolite including some migmatite as well as minor metasedimentary and quartzo feldspathic gneisses the most intriguing rocks in the complex are mafic to ultramafic garnet and clinopyroxene bearing amphibolites that are restricted to the vicinity of the peridotite contact these rocks have unusual fe rich si poor bulk compositions and may represent tholeiites chemically modified by interaction with fluid or melt before or during metamorphism these amphibolites are not retrograde eclogites since andesine was present throughout the metamorphic history and the clinopyroxene is not omphacitic coexisting mineral compositions and temperature estimates overlap for core rim and matrix grains of all the major phases in the garnet clinopyroxene amphibolites implying equilib

observations of wave induced pore pressure gradients and bed level response on a surf zone sandbar horizontal and vertical pressure gradients may be important physical mechanisms contributing to onshore sediment transport beneath steep near breaking waves in the surf zone a barred beach was constructed in a large scale laboratory wave flume with a fixed profile containing a mobile sediment layer on the crest of the sandbar horizontal and vertical pore pressure gradients were obtained by finite differences of measurements from an array of pressure transducers buried within the upper several centimeters of the bed co located observations of erosion depth were made during asymmetric wave trials with wave heights between 0 10 m and 0 98 m consistently resulting in onshore sheet flow sediment transport the pore pressure gradient vector within the bed exhibited temporal rotations during each wave cycle directed predominantly upwards under the trough and then rapidly rotating onshore and downwards as the wave front passed the magnitude of the pore pressure gradient during each phase of rotation was correlated with local wave steepness and relative depth momentary bed failures as deep as 20 grain diameters were coincident with sharp increases in the onshore directed pore pressure gradients but occurred at horizontal pressure gradients less than theoretical critical values for initiation of the motion for compact beds an expression combining the effects of both horizontal and vertical pore pressure gradients with bed shear stress and soil stability is used to determine that failure of the bed is initiated at non negligible values of both forces

direct measurements of bed stress under swash in the field 1 utilizing flush mounted hot film anemometry the bed stress under swash was measured directly in a field experiment conducted on barret beach fire island new york the theory development and calibration of the instrument package are discussed and results from the field experiment are presented examples of bed stress time series throughout a swash cycle are presented and an ensemble averaged swash bed stress cycle is calculated strong asymmetry is observed between the uprush and backwash phases of the swash flow the maximum bed shear stress exerted by the uprush is approximately double that of the backwash while the duration of the backwash is 135 greater than that of the uprush friction coefficients in the swash zone are observed to be similar in magnitude to those from steady flow with the mean observed friction coefficient equal to 0 0037 swash friction coefficients derived from the current measurements exhibit a reynolds number dependence similar to that observed for other flows a systematic difference between coefficients for uprush and backwash is suggested

4 d constrained depth conversion for reservoir compaction estimation application to ekofisk field ekofisk field in the norweigian sector of the north sea is a remarkable example of a strongly compacted chalk reservoir since the start of production in 1971 the water bottom has subsided by over 8 m as a result of reservoir compaction hermansen et al the field wide waterflood begun in 1989 was expected to halt pressure depletion and reservoir compaction after a few years of waterflooding ekofisk reservoir pressure began increasing but compaction and subsidence continued laboratory studies on chalk cores indicated that high porosity oil filled chalk compacts strongly when flushed with seawater these studies along with reservoir flow simulation and geomechanic modeling led to a model of a water weakening compaction sylte et al ongoing efforts deployed to monitor the reservoir compaction and seabed subsidence include twice a year compaction logging in a monitoring well daily gps measurements at the platforms and periodic bathymetry surveys nine surveys from 1970 to 1999

petrology of amphibolite facies mafic and ultramafic rocks from the catalina schist southern california metasomatism and migmatization in a subduction zone metamorphic setting the catalina schist of southern california is a subduction zone metamorphic terrane it consists of three tectonic units of amphibolite high p greenschist and blueschist facies rocks that are structurally juxtaposed across faults forming an apparent inverted metamorphic gradient migmatitic and non migmatitic metabasite blocks surrounded by a meta ultramafic matrix comprise the upper part of the catalina amphibolite unit fluid rock interaction at high p high t conditions caused partial melting of migmatitic blocks metasomatic exchange between metabasite blocks and ultramafic rocks infiltration of silica into ultramafic rocks and loss of an albitic component from nonmigmatitic clinopyroxene bearing metabasite blocks partial melting took place at an estimated p 8 11 kbar and t 640 750 c at high h2o activity the melting reaction probably involved plagioclase quartz trondhjemitic melts were produced and are preserved as leucocratic regions in migmatitic blocks and as pegmatitic dikes that cut ultramafic rocks the metasomatic and melting processes reflected in these rocks could be analogous to those proposed for fluid and melt transfer of components from a subducting slab to the mantle wedge aqueous fluids rather than melts seem to have accomplished the bulk of mass transfer within the mafic and ultramafic complex

bed slope effects on turbulent wave boundary layers 2 comparison with skewness asymmetry and other effects 1 a numerical model solving incompressible reynolds averaged navier stokes equations combined with a two equation k model for turbulence closure is used to systematically compare the relative strength of bed shear stress quantities and boundary layer streaming under wave motions from four contributions believed to play a prominent role in cross shore boundary layer and sediment transport processes 1 converging diverging effects from bed slope 2 wave skewness 3 wave asymmetry and 4 waves combined with superposed negative currents intended to loosely represent for example return currents or undertow the effects from each of the four components are isolated and quantified using a standard set of bed shear stress quantities allowing their easy comparison for conditions representing large shallow water waves on steep slopes the results suggest that converging diverging effects from beach slope may make a significant onshore bed load contribution generally however the results suggest wave skewness in addition to conventional steady streaming as the most important onshore contribution outside the surf zone streaming induced within the wave boundary layer is also investigated for each component and skewness and asymmetry are demonstrated to promote largely negative streaming velocities consistent with earlier work for hydraulically smooth cases however a thin region of positive streaming is revealed in the viscous sublayer which is effectively absent in hydraulically rough conditions cross shore boundary layer dynamics are generally acknowledged to be a complicated combination of numerous competing physical processes and this work is among few to systematically compare a number of these it is hoped that the results will be useful in assessing which of the contributions considered will be most prominent for a given set of local wave and beach slope conditions

a 40ar 39ar study of oceanic and continental deformation processes during an oblique collision taconian orogeny in the quebec reentrant of the canadian appalachians received 7 december 2006 revised 9 january 2008 accepted 10 march 2008 published 1 july 2008 1 two phases of penetrative deformation are documented in the taconian hinterland of the appalachian orogen in the gaspepeninsula d1 is associated with the obduction of the mont albert ophiolite onto the paleozoic laurentian margin whereas d2 corresponds to later transport of allochthons across the margin in the metamorphic sole s1 is a se dipping mylonitic fabric with a downdip lineation in underlying metabasalts d1 is characterized by nw overturned and recumbent folds and a subhorizontal s1 schistosity with an ene trending orogen parallel lineation d2 is characterized by a s2 steeply dipping penetrative axial planar crenulation cleavage and ne trending f2 folds the intraoceanic thrusting of ophiolite is dated at 465 ma early d1 whereas emplacement of ophiolite andsubsequentdeformationofthemarginwasrecorded by isotopic signatures between 459 and 456 ma late d1 d2 is dated at 448 ma throughout the hinterland taconian transpressive deformation is related to an oblique collision within the quebec reentrant of the canadian appalachians during the ordovician citation malo m g ruffet a pincivy and a tremblay 2008 a 40 ar 39 ar study of oceanic and continental deformation processes during an oblique collision taconian orogeny in the quebec reentrant of the canadian appalachians tectonics 27 tc4001 doi 10 1029 2006tc002094

effects of turbulence on the transport of individual particles as bedload in a gravel bed river this study investigates the association between mean and turbulent flow variables and the movement of individual particles in a gravel bed river the experimental design implemented in the eaton north river quebec canada is based on the simultaneous observations at a high temporal resolution of both particle movements as bedload using an underwater video camera and of the streamwise and vertical flow velocity components using a vertical array of three electromagnetic current meters ecms the frequency and distance of displacement of particles larger than 20 mm that were sliding or rolling on the bed were measured from a 10 minutes long film mean and turbulent flow properties obtained for periods without sediment transport are compared to those when particles were sliding and rolling when particles are sliding weak differences are present for the mean streamwise velocity and normal vertical stresses instantaneous reynolds shear stresses are significantly lower for sliding events which was not expected but could be explained by the important dominance of quadrant 3 events inward interactions when particles are rolling only the vertical normal stresses show a weak difference from those observed in the absence of transport but they tend to occur when quadrant 2 ejections dominate the flow field for both sliding and rolling particles vertical and or streamwise fluid accelerations show high magnitude values when compared to periods without transport for sliding particles streamwise acceleration is mostly negative and combines most of the time with a positive vertical acceleration for rolling particles streamwise and vertical acceleration are predominantly of opposite sign these results suggest that fluid acceleration or deceleration in the streamwise and vertical directions is affecting the pressure field around particles in this study fluid acceleration seems to play a more important role than reynolds shear stress or normal stresses for bedload movements copyright 2010 john wiley sons ltd

a semianalytical model for sheet flow layer thickness with application to the swash zone a new semianalytical model for the time dependent thickness of the sheet flow layer that includes the effects of pressure gradients bed slope boundary layer growth and bore turbulence is presented the shear stress and boundary layer growth are computed using the boundary layer integral method the model is expressed as two coupled ordinary differential equations that are solved numerically given a prescribed time series of free stream velocity horizontal pressure gradient and bore turbulence which together represent the hydrodynamic forcing the model was validated against two data sets of sheet flow layer thickness collected in oscillatory flow tunnels and one data set collected in the swash zone of a prototype scale laboratory experiment in the oscillatory flow tunnel data sets sheet flow is mostly generated by shear stress with pressure gradients providing an important secondary forcing around flow reversal in the swash zone pressure gradients and shear stresses alone are not sufficient to generate the large sheet flow layer thickness observed at the initial stages of uprush bore turbulence is most likely the dominant generation mechanism for this intense sheet flow

seabed shear stress and bedload transport due to asymmetric and skewed waves abstract a simple conceptual formulation to compute seabed shear stress due to asymmetric and skewed waves is presented this formulation generalizes the sinusoidal wave case and uses a variable friction factor to describe the physics of the boundary layer and to parameterize the effects of wave shape predictions of bed shear stresses agree with numerical computations using a standard boundary layer model with a k e turbulence closure the bed shear stress formulation is combined with a meyer peter and muller type formula to predict sheet flow bedload transport under asymmetric and skewed waves for a horizontal or sloping bed the predictions agree with oscillatory water tunnel measurements from the literature

bed shear stress under skewed and asymmetric oscillatory flows abstract we present a new formulation to predict the bed shear stress under skewed asymmetric oscillatory flows with or without a co linear mean current extending the work of nielsen 1992 the nonlinearity of the oscillatory flow is incorporated through the use of two parameters the index of skewness or nonlinearity and the waveform parameter the new formulation is tested against the bed shear stress estimated from the log fit and momentum integral methods using oscillatory data from oscillating water tunnel experiments the new formulation and the momentum integral method agree well but differ from those with the log fit method possibly because both methodologies lead to different results for the phase lead between the bed shear stress and the free stream velocity the new bed shear stress formulation is incorporated in a quasi steady bedload formula and accurately reproduces net transport rates under non linear nonbreaking waves with and without an opposing current

recent advances in modeling swash zone dynamics influence of surf swash interaction on nearshore hydrodynamics and morphodynamics the role of the swash zone in influencing the whole nearshore dynamics is reviewed with a focus on the interaction between surf and swash zone processes local and global hydromorphodynamic phenomena are discussed in detail and a description of the overall swash zone operation is given the effects of swash zone boundary conditions are highlighted together with the importance of surf zone boundary conditions major emphasis is placed on illustrating the interactions of various hydrodynamic modes which in turn control the swash and surf zone morphology finally methods to account for swash zone processes in coastal models with different temporal and spatial resolutions are proposed

effects of wave shape on sheet flow sediment transport 1 a two phase model is implemented to study the effects of wave shape on the transport of coarse grained sediment in the sheet flow regime the model is based on balance equations for the average mass momentum and fluctuation energy for both the fluid and sediment phases model simulations indicate that the responses of the sheet flow such as the velocity profiles the instantaneous bed shear stress the sediment flux and the total amount of the mobilized sediment cannot be fully parameterized by quasi steady free stream velocity and may be correlated with the magnitude of local horizontal pressure gradient or free stream acceleration a net sediment flux in the direction of wave advance is obtained for both skewed and saw tooth wave shapes typical of shoaled and breaking waves the model further suggests that at critical values of the horizontal pressure gradient there is a failure event within the bed that mobilizes more sediment into the mobile sheet and enhances the sediment flux preliminary attempts to parameterize the total bed shear stress and the total sediment flux appear promising

origin and tectonic significance of the aldrich mountains serpentinite matrix melange northeastern oregon the permian triassic aldrich mountains serpentinite melange consists of a matrix of massive and foliated serpentinite lizardite chrysotile that encases a variety of metamorphic igneous and sedimentary block types serpentinite matrix foliation trends ne sw dips steeply 75 and is parallel to long dimensions of blocks at block matrix contacts the foliation traces block margins the volumetrically most abundant block types are greenstone chert and metagabbro subordinate block types are amphibolite tectonites epiclastic sediments breccia conglomerate sandstone and argillite silicic volcanic rocks silicic plutonic rocks and ultramafic rocks three types of metamorphism are evident from textures and mineral assemblages of blocks and matrix 1 serpentinization and related hydrous alteration confined to matrix ultramafic blocks and margins of mafic blocks 2 lower to middle greenschist and prehnite actinolite facies metamorphism characterized by static non penetrative fabrics of some blocks and 3 dynamothermal epidote amphibolite to upper amphibolite lower granulite metamorphism exhibited by strongly schistose amphibolite tectonites mineral assemblages and mineral chemistry indicate amphibolite tectonites formed at moderate to high temperatures 550 780 c and low to moderate pressures 3 5 kbar most blocks were affected by variable degrees of post metamorphic brittle deformation prior to immersion in serpentinite matrix the melange is interpreted to have formed within a permian to late triassic sediment starved tectonically active forearc fragments of abyssal oceanic crust and early permian ensimatic arc crust were mixed by tectonic and sedimentary processes within the forearc highly mobile serpentinite generated beneath the forearc was protrusively emplaced into the tectonized forearc and mixed with the blocks forming the melange melange generation probably began in the late early permian and ceased by the late triassic

discrete particle model for sheet flow sediment transport in the nearshore fully three dimensional discrete particle computer simulations of high concentration sheet flow transport in oscillatory flows quantify the effect of fluid acceleration on bed load transport in highly unsteady flows typical of nearshore marine environments a simple impulse momentum approach explains simulation results and forms the basis for adding an acceleration related term to widely used energetics sediment transport formulae transport predicted by the acceleration term becomes increasingly significant as wave shape approaches the sawtooth profile characteristic of surf zone bores simulations integrate f ma and a corresponding set of equations for the torques for each sphere normal and tangential forces between contacting particles are linear functions of the distance between sphere centers and the relative tangential displacement at the contact point respectively particle interactions are both inelastic and frictional pressure gradient forces generated by the passage of surface gravity waves drive fluid and particle motion in a stack of thin horizontal fluid layers that exchange momentum and exert fluid drag added mass and buoyancy forces on particles transport properties of the simulated granular fluid assemblage are robust to large variations in material properties of the particles simulated transport rates agree with available experimental data for unsteady transport of coarse sands the mode of bed load motion dispersion of bed load particles and particle segregation by size and density are qualitatively consistent with available particle scale observations of bed load transport of natural particles

observations of sand bar evolution on a natural beach waves currents and the location of the seafloor were measured on a barred beach for about 2 months at nine locations along a cross shore transect extending 255 m from 1 to 4 m water depth the seafloor location was measured nearly continuously even in the surf zone during storms with sonar altimeters mounted on fixed frames the crest of a sand bar initially located about 60 m from the shoreline moved 130 m offshore primarily when the offshore significant wave height exceeded about 2 m with 1 5 m of erosion near the initial location and 1 m of accretion at the final location an energetics type sediment transport model driven by locally measured near bottom currents predicts the observed offshore bar migration but not the slow onshore migration observed during low energy wave conditions the predicted offshore bar migration is driven primarily by cross shore gradients in predicted suspended sediment transport associated with quasi steady near bottom offshore flows these strong 50 cm s currents intensified near the bar crest by wave breaking are predicted to cause erosion on the shoreward slope of the bar and deposition on the seaward side the feedback amoung morphology waves circulation and sediment transport thus forces offshore bar migration during storms

retrograde eclogite from mont albert gaspe quebec retrograde eclogite is found along the northern perimeter of ultramafic rocks in the mont albert complex gaspe quebec garnet clinopyroxene geothermometry gives 840 c as the peak temperature of metamorphism kyanite in associated metapelites requires that at this temperature pressure be a minimum of 12 kbar based on symplectic textures in the eclogitic and associated rocks and clinozoisite white mica quartz plagioclase equilibria a counterwise pressure temperature trajectory that terminates near 500 c and 8 kbar can be traced for the mont albert complex

amphibolite associated with the thetford mines ophiolite complex at belmina ridge quebec amphibolite in the quebec appalachians at belmina ridge 45 58 n 71 28 w constitutes a steeply dipping allochthonous sheet as much as 800 m thick between the obducted thetford mines ophiolite complex to the east and rocks of the allochthonous caldwell group to the west the amphibolite which structurally and chemically is unlike amphibolite in the adjacent caldwell is fresh coarse to fine grained and massive to layered it is composed chiefly of edenitic to pargasitic amphibole pyrope and grossular rich almandine salite and epidote with small amounts of quartz plagioclase and accessory minerals metamorphism ranged from at the base of the sheet to t 780 c at the top near the tectonic contact with rocks of the superjacent ophiolite complex under a barrovian facies series with ptotal between 5 and 7 kbars 500 700 mpa the amphibolite is interpreted to have been derived from ocean floor basalt that was metamorphosed under a 20 km thick westward directed obducted allochthon of oceanic l

boundary layer hydrodynamics and bedload sediment transport in oscillating water tunnels oscillating water tunnels are experimental facilities commonly used in coastal engineering research they are intended to reproduce near bed hydrodynamic and sediment transport phenomena at a realistic scale in an oscillating water tunnel a piston generates an oscillatory motion that propagates almost instantaneously to the whole tunnel consequently flow is uniform along the tunnel unlike the propagating wave motion in the sea or in a wave flume this results in subtle differences between the boundary layer hydrodynamics of an oscillating water tunnel and of a propagating wave which may have a significant effect in the resulting sediment transport in this paper we present a zeroth order analytical model of the turbulent boundary layer hydrodynamics in an oscillating water tunnel by using a time varying eddy viscosity and by accounting for the constraints arising from the tunnel s geometry the model predicts the oscillating water tunnel hydrodynamics and yields analytical expressions to compute bed shear stresses for asymmetric and skewed waves both in the absence or presence of an imposed current these expressions are applied to successfully quantify bedload sediment transport in oscillating water tunnel experiments

estimation of layer thickness and velocity changes using 4d prestack seismic data in some hydrocarbon reservoirs severe compaction of the reservoir rocks is observed this compaction is caused by production and is often associated with stretching and arching of the overburden rocks time lapse seismic data can be used to monitor these processes since compaction and stretching cause changes in layer thickness as well as seismic velocities it is crucial to develop methods to distinguish between the two effects we introduce a new method based on detailed analysis of time lapse prestack seismic data the equations are derived assuming that the entire model consists of only one single layer with no vertical velocity variations the method incorporates lateral variations in relative velocity changes by utilizing zero offset and offset dependent time shifts to test the method we design a 2d synthetic model that undergoes severe reservoir compaction as well as stretching of the overburden rocks finally we utilize the method to analyze a real 2d prestack time lapse seismic line from t

40ar 39ar ages for minerals from the amphibolite dynamothermal aureole mont albert gaspe quebec new 40ar 39ar ages are presented for two hornblendes and one biotite from the dynamothermal aureole that is situated at the base of the mont albeit ophiolite analysis by the incremental release technique reveals a small component of excess 40ar in one hornblende though both exhibit plateau type spectra the biotite was analyzed by the total fusion technique all apparent ages are concordant and average 456 3 ma dynamothermal aureoles form during the obduction process which juxtaposes ophiolites and amphibolite protoliths during a compressional tectonic event at a plate margin in this instance thrusting of the mont albert ophiolite over rocks of the shickshock group the concordance of biotite and hornblende ages indicates rapid postmetamorphic cooling and firmly dates obduction at 456 3 ma ago an age younger than any of the other northern appalachian ophiolites the high pressure metamorphism of the amphibolite is inconsistent with the present high structural level of the composite mont albert

late neoproterozoic to permian tectonic evolution of the quebec appalachians canada abstract due to the unique location of the quebec appalachians in a re entrant of the paleo north american margin and to the fact that the area largely escaped late paleozoic deformation this segment of the orogen preserves evidence of the early orogenic stages that are partly obscured elsewhere despite diachronicity both along and across strike of the orogen five tectonic events of regional significance are recognized 1 the earliest event is mainly recorded by neoproterozoic to early ordovician normal faults associated with extension of the laurentian craton and the establishment of a passive continental margin 2 the second event the ordovician taconian orogeny is marked by foreland directed deformation and corresponds to the principal deformational and metamorphic events recorded by the laurentian margin 3 the third event early salinic is early silurian it is restricted to the southern part of the quebec appalachians and consists of hinterland se directed thrusts folds and retrograde metamorphism 4 the fourth event late salinic is recorded by regional scale late silurian to early devonian normal or transtensional faults and is associated with the formation of the connecticut valley gaspe trough and 5 the last event the devonian acadian orogeny affects with variable intensity all the pre carboniferous lithologies this tectonic synthesis implies that the subdivision of the peri laurentian oceanic tracts proposed in other segments of the appalachians should be applied with caution in quebec and that the structural style the number of oceanic domains and possibly the vergence of subduction change along the strike of the orogen in particular the similarities of the thetford mines and boil mountain ophiolitic complexes and sedimentary covers and the lack of evidence for a major intervening suture are consistent with the maximum allochtony hypothesis i e the assumption that the southern quebec ophiolites are rooted east of the chain lake massif a geodynamic model involving the taconian obduction of a large ophiolitic nappe s the docking of a peri gondwanan gander medial new england terrane in early salinic the formation of large sedimentary basins connecticut valley gaspe and merrimack troughs due to trench rollback and or delamination during the late salinic event and collision at the outer margin of composite laurentia during the acadian orogeny can account for the protracted structural and metamorphic history of the quebec appalachians

the significance of various garnet types in surficial materials in southeastern gaspe peninsula quebec the distribution patterns of four types of garnet in surficial materials of southeastern gaspe peninsula are interpreted in terms of the glacial history of the area the lithostratigraphy of the be

nearshore sandbar migration field observations suggest that onshore sandbar migration observed when breaking wave driven mean flows are weak may be related to the skewed fluid accelerations associated with the orbital velocities of nonlinear surface waves large accelerations both increases and decreases in velocity magnitudes previously suggested to increase sediment suspension occur under the steep wave faces that immediately precede the maximum onshore directed orbital velocities weaker accelerations occur under the gently sloping rear wave faces that precede the maximum offshore directed velocities the timing of strong accelerations relative to onshore flow is hypothesized to produce net onshore sediment transport the observed acceleration skewness a measure of the difference in the magnitudes of accelerations under the front and rear wave faces is maximum near the sandbar crest the corresponding cross shore gradients of an acceleration related onshore sediment transport would cause erosion offshore and accretion onshore of the bar crest consistent with the observed onshore migration of the bar crest furthermore the observations and numerical simulations of nonlinear shallow water waves show that the region of strongly skewed accelerations moves shoreward with the bar suggesting that feedback between waves and evolving morphology can result in continuing onshore bar migration

large scale experimental observations of sheet flow on a sandbar under skewed asymmetric waves a novel large wave flume experiment was conducted on a fixed barred beach with a sediment pit on the sandbar allowing for the isolation of small scale bed response to large scale forcing concurrent measurements of instantaneous sheet layer sediment concentration profiles and near bed velocity profiles were obtained on a sandbar for the first time two sediment distributions were used with median grain diameters d50 of 0 17 mm and 0 27 mm sheet flow occurred primarily under wave crests where sheet thickness increased with increasing wave height a proportionality constant was used to relate maximum shields parameter to maximum sheet thickness normalized by d50 with bed shear stress computed using the quadratic drag law an enhanced sheet layer thickness was apparent for the smaller sediment experiments 18 7 when directly compared to closed conduit oscillatory flow tunnel data 10 6 however varied significantly 5 31 depending on the procedure used to estimate grain roughness ds and wave friction factor fw three models for ks were compared keeping the model for fw fixed constant ks 2 5d50 and two expressions dependent on flow intensity derived from steady and oscillatory sheet flow experiments values of ks d50 varied by two orders of magnitude and exhibited an inverse relationship with where 30 for ks d50 of o 1 while 5 for ks d50 of o 100 two expressions for fw were also tested with the steady flow based model for ks yielding a difference of 69 13 versus 22

cross shore suspended sand and bed load transport on beaches simple formulas are developed to predict the time averaged rates of cross shore suspended sand and bed load transport the net suspended sand transport rate is expressed as the product of the depth averaged current and the suspended sediment volume per unit bottom area with a reduction factor that accounts for the correlation between the time varying fluid velocity and sediment concentration the net bed load transport rate under nonlinear waves is assumed to be onshore and proportional to u3 where u is the standard deviation of the horizontal velocity the probabilities of sediment movement and suspension are introduced to account for the initiation of sediment movement and suspension simple functions are proposed to account for the effects of a steep bottom slope on the bed load and suspended sediment transport rates the proposed formulas are found to be in agreement with three data sets within a factor of about 2 the proposed formulas are shown to be consistent with existing simple formulas the formulas are incorporated into a time averaged wave model and the continuity equation of bottom sediment to predict the beach profile evolution the numerical model is compared with seven small scale tests including berm erosion tests and seven large scale tests including dune erosion tests the numerical model predicts the overall beach profile evolution including the berm and dune erosion but does not always predict the fairly subtle profile changes including bar migration accurately

bar trough generation on a natural beach mechanisms for bar trough generation are examined using velocities measured in the field applied to the bowen 1980 bailard 1981 energetics based sediment transport model measurements consist of a cross shore array of nine electromagnetic current meters spanning the surf zone and daily bathymetric surveys during a 10 day period during which two storms occurred when the bathymetry evolved from a three dimensional terrace to a well developed linear bar the model predicts bed and suspended load transport separately based on various velocity moments the velocities are partitioned into mean currents low frequency infragravity and shear instabilities 0 05 hz to determine the relative importance of various mechanisms to the total transport velocity moments are computed over 90 min intervals to resolve tidal fluctuations tidal signatures were apparent in all modes of transport predicted transport rates are integrated and compared with daily cross shore bathymetric profiles averaged over a 400 m length of beach the suspended load terms were an order of magnitude greater than bed load terms owing to the low fall velocity of the fine grain sand within the surf zone model results for this experiment indicate the dominant mechanism for bar development was sediments mobilized by the strong longshore current and incident short waves within the surf zone and transported offshore by the mean undertow and shoreward transport onshore due to short wave velocity skewness using standard coefficients the model correctly predicted the first order movement of the bar during storms but underpredicted trough development and did not always perform well during mild wave conditions

role of pressure gradients in sheet flow of coarse sediments under sawtooth waves 1 discrete particle model dpm simulations have been performed to directly examine the role of horizontal pressure gradients acting on the wave bottom boundary layer wbbl during the process of sheet flow transport in the surf zone the dpm is a two phase wbbl model that directly couples a one dimensional eddy viscosity fluid flow to a three dimensional particle model newton s third law is enforced at every simulation time step through fluid particle interaction forces of buoyancy drag and added mass simulations are able to reproduce bedload transport rates from a laboratory data set for coarse sediment distributions consequently simulations of a monochromatic sawtooth wave were performed with three coarse grain size distributions to investigate the relative importance of bed shear stresses horizontal pressure forces and fluid particle drag forces on bedload transport processes the simulation results demonstrate that the magnitude of the horizontal pressure force acting directly on sediment embedded in the wbbl is small compared to the magnitude of the particle drag force or particle stress however the phasing of the onshore peak in the horizontal pressure force with respect to the particle drag force is important to sediment mobilization and enhances the observed onshore bias in bed load flux removing the horizontal pressure force on the sediment particles resulted on average in a 30 reduction in net bed load flux in the surf zone free stream fluid accelerations are typically equated to the horizontal pressure gradient thus the simulations may explain why the fluid acceleration can be a successful parameter for aiding in sediment transport predictions in the surf zone

tremolite and h 2 o activity attending metamorphism of hornblende plagioclase garnet assemblages estimation of the activity of tremolite component atr in calcic amphiboles is an important problem in igneous and metamorphic petrology because equilibria involving tremolite are used in the estimation of the activity of h2o attending crystallization of igneous and metamorphic rocks estimated values of atr from hornblende analyses using both ionic and coupled substitution crystalline solution models can be compared to values of atr calculated from vapor absent mineral equilibria in addition these values of atr can be used in calculations of ah2o for rocks for which there is an independent estimate of ah2o the values of atr calculated from vapor absent equilibria are generally consistent with those estimated from the different crystalline solution models but uncertainties in the calculations preclude choosing a preferred solution model from computed mineral equilibria it is clear that mineral assemblages with low values of atr can be in equilibrium with high values of ah2o consequently the low values of ah2o estimated from hornblende bearing high grade rocks with low values of atr may be real rocks from mica creek british columbia probably achieved extremely low values of ah2o by vapor absent metamorphism

diagnostic investigation of impulsive pressures induced by plunging breakers impinging on gravel beaches abstract this paper presents an integrated investigation of physical processes generating impulsive pressures under the action of plunging breakers impinging on gravel beaches this work is an extension of a recent investigation which suggested that wave impacts from plunging breakers acting on gravel beaches may be a key mechanism to enhance sediment mobilisation in particular comparisons of full scale laboratory measurements against model results from a well validated phase depth resolving numerical model based on the reynolds averaged navier stokes rans equations are presented this represents the first attempt at comparison with such a tool against observed hydrodynamics on steep slope 1 8 gravel beaches at prototype scale in order to understand how impulsive pressures are generated under plunging waves the numerical model is used to carry out a detailed investigation to examine the role of each of the acceleration terms in the momentum balance consistent with prior studies numerical results show that under plunging breakers the local acceleration u t alone cannot be used as a proxy for pressure gradients however the contribution of the third term w u z of total acceleration is recognized for the first time and indicates that this term has an important role in both the induced pressure gradient and sediment mobilisation as induced by this particular type of breaking furthermore results suggest that a parameterisation of the pressure gradient in terms of u t u u x may not suffice when dealing with plunging breakers and hence there is a lack of a suitable parameterisation of this process in the present literature thus for different types of breaking it may be necessary to consider a different characterisation of the pressure gradient toward the parameterisation of sediment transport inside the surf zone

sand transport by unbroken water waves under sheet flow conditions a model of wave induced onshore sand transport and resulting topographical changes seaward of the break point on a sloping beach is presented for the specific case in which the waves are random normally incident weakly nonlinear and relatively long the bottom boundary layer is fully turbulent and sand transport occurs as sheet flow the model consists of the following components 1 a new empirical expression for sand transport as sheet flow in which the instantaneous transport rate is directly proportional to the instantaneous bottom shear stress 2 an expresssion for the mean bottom shear stress based on a theoretical analysis of the bottom boundary layer 3 a simple representation of the shoaling wave field in which the local properties are described by linear long wave theory the probability density function of the surface displacement is gaussian and the waves conserve energy flux as they shoal and 4 the equation for conservation of sediment mass computations based on the model compare favorably with recently reported field measurements of the onshore motion of a long offshore bar

direct numerical simulation of bedload transport using a local dynamic boundary condition temporally and spatially averaged models of bedload transport are inadequate to describe the highly variable nature of particle motion at low transport stages the primary sources of this variability are the resisting forces to downstream motion resulting from the geometrical relation pocket friction angle of a bed grain to the grains that it rests upon variability of the near bed turbulent velocity field and the local modification of this velocity field by upstream protruding grains a model of bedload transport is presented that captures these sources of variability by directly integrating the equations of motion of each particle of a simulated mixed grain size sediment bed experimental data from the velocity field downstream and below the tops of upstream protruding grains are presented from these data an empirical relation for the velocity modification resulting from upstream grains is provided to the bedload model the temporal variability of near bed turbulence is provided by a measured near bed time series of velocity over a gravel bed the distribution of pocket friction angles results as a consequence of directly calculating the initiation and cessation of motion of each particle as a result of the combination of fluid forcing and interaction with other particles calculations of bedload flux in a uniform boundary and simulated pocket friction angles agree favourably with previous studies

fluid acceleration effects on suspended sediment transport in the swash zone 1 suspended sediment concentrations and fluid velocities measured in the swash zone of a high energy steep beach were used to investigate the importance of fluid accelerations to suspended sediment transport swash flow acceleration was nearly constant at about one half downslope gravitational acceleration with two important exceptions we observed strong short lived periods of accelerating uprush at the beginning of the swash cycle and decelerating backwash at the end of the swash cycle magnitudes of both approximately twice that of the expected downslope gravitational acceleration interestingly spikes in suspended load followed the anomalies in acceleration in a way that was not apparent from the nearly symmetric in magnitude ensemble averaged velocity time series suspended load values were largest during accelerating uprush associated with the shoreward propagating turbulent bore or swash front during backwash suspended loads were generally not as large correspondingly suspended sediment transport rates obtained from the sediment concentration and velocity measurements showed best comparisons with a modified sediment transport model that includes a physical mechanism for enhancing transport rates due to flow acceleration the modified sediment transport model reduced the overall root mean square prediction error by up to 35 and shifted the predicted peak in uprush sediment transport rate earlier in the swash cycle resulting in a better fit to the observations these findings suggest that the inclusion of the acceleration term may account for physical mechanisms that include bore turbulence and horizontal pressure gradients typically associated with the accelerating portion of uprush

regional metamorphism of the appalachian humber zone of gaspe peninsula 40ar 39ar evidence for crustal thickening during the taconian orogeny geochronological studies on the timing of deformation and metamorphism along the laurentian margin have shown that the ages of metamorphic events change along strike within the newfoundland southern quebec segment of the canadian appalachians the gaspe peninsula is located at mid point of the two extremities of this segment new single grain laser 40ar 39ar plateau ages solely reflect latest middle late ordovician metamorphism samples taken within the internal humber zone in the shickshock group rocks yield 40ar 39ar muscovite and hornblende ages ranging from 457 to 454 ma samples from the amphibolite du diable the metamorphic sole of the mont albert ophiolite yield 40ar 39ar muscovite and hornblende ages ranging from 459 to 457 ma ordovician ages of the internal humber zone are consistent with 40ar 39ar ages from southern quebec and are interpreted as the result of the emplacement onto the margin of both the ophiolite and its metamorphic sole

bedload and suspended load contributions to breaker bar morphodynamics abstract this study presents measurements of sheet flow processes grain sorting and bedload plus suspended load transport rates around a medium sand breaker bar in a large scale wave flume the results offer insights in effects of wave breaking on bedload and grain sorting processes and in the quantitative contributions by bedload and suspended transport to breaker bar morphodynamics sheet flow layer dynamics are highly similar to observations under non breaking waves revealing clear effects by velocity asymmetry but no evident effects by breaking generated turbulence bed slope or the cross shore non uniform flow the sheet flow layer thickness can be predicted using existing empirical formulations based on local hydrodynamic forcing at locations covering the shoaling region up to the bar crest the cross shore variation in bedload transport rates is explained by variations in wave shape i e velocity skewness and asymmetry at locations between bar crest and bar trough bedload transport rate magnitudes correlate positively with bed slope and turbulent kinetic energy bedload and suspended load transport rates are of similar magnitude but of opposite sign bedload transport is onshore directed and dominates in the shoaling zone but after wave breaking the offshore directed suspended sediment transport increases in magnitude and exceeds bedload transport rates in the breaking and inner surf zones bedload and suspended load transport contribute notably differently to bed profile evolution bedload transfers sand grains from the offshore slope to the bar crest and additionally leads to erosion of the shoreward bar slope and deposition at the bar trough while suspended load transport induces an opposite pattern of erosion at the bar trough and accretion at the bar crest grain size analysis of suspended sediment samples reveals size selective entrainment and vertical size segregation in the inner surf zone but suggest size indifferent entrainment and vertical mixing by energetic vortices in the breaking region size selective transport by bedload and suspended load leads to a cross shore coarsening of the bed from shoaling to inner surf zone with local additional sorting mechanisms around the breaker bar due to bed slope effects

nearshore sandbar migration predicted by an eddy diffusive boundary layer model 1 we simulated the erosion and accretion of a natural beach using a wave resolving eddy diffusive model of water and suspended sediment motion in the bottom boundary layer nonlinear advection was included in this one dimensional vertical profile model by assuming that waves propagated almost without change of form flows were forced by fluctuating pressure gradients chosen to reproduce the velocity time series measured during the duck94 field experiment the cross shore flux of suspended sediment beneath each field deployed current meter was estimated and beach erosion accretion was calculated from the divergence convergence of this flux horizontal pressure forces on sediment particles were neglected the model successfully predicted two bar migration events one shoreward bar migration and one seaward but failed to predict a third seaward migration event simulated seaward sediment transport was due to seaward mean currents simulated shoreward sediment transport was due to covariance between wave frequency fluctuations in velocity and sediment concentration and was mostly confined to the wave boundary layer predicted seaward shoreward bar migration was driven by a maximum in the current generated wave generated flux over the sandbar a wave generated downward flux of shoreward momentum into the wave boundary layer contributed to shoreward sediment transport and often had a local maximum over the bar crest second order nonlinear advection of sediment mostly representing shoreward advection by the stokes drift also often had a local maximum over the bar crest together wave generated momentum fluxes and the stokes drift substantially increased shoreward transport and were essential to predictions of shoreward bar migration

p t conditions during emplacement of the bay of islands ophiolite complex a high temperature contact is described between the basal pargasite bearing spinemherzolites of the bay of islands ophiolite complex and underlying garnet granulite facies metagabbros of its dynamothermal aureole three distinct high temperature hydrous assemblages occur in the basal mylonites of the peridotite and spinel and garnet bearing corona textures indicative of increase in pressure under constant or increasing temperature conditions are described for the first time from the uppermost part of the aureole on the basis of garnet clinopyroxene geothermometry and garnet forming reactions in metabasic rocks p t conditions of 7 11 kbar 750 850 c are estimated for rocks on both sides of the contact steep inverted gradients in both temperature and pressure of equilibration occur in the aureole which most likely represents a thinned overturned and metamorphosed section through an ophiolite sequence it is proposed that the aureole formed in a low angle shear zone cutting the oceanic crust and upper mantle age data shows that the bay of islands complex was 30 40 ma old and therefore relatively cold at the time of formation of the aureole prolonged 1 ma shear heating must therefore have occurred at high shear stresses and movement rates 1 kbar 10 cm yr to produce the high contact temperatures the displacement surface probably initiated as a discrete fault evolving into a viscous shear zone with time downward movement of the locus of shearing into weaker lithologies and finally thrusting of the ophiolite aureole complex over cold sediments accounts for the preservation of steep metamorphic gradients in the aureole the observed pressures at the ophiolite aureole contact are 3 7 kbar in excess of the expected load pressure from the present thickness of the ophiolite the cause of the pressure excess was removed before formation of lower grade parts of the aureole possible explanations are tectonic thinning of the ophiolite during displacement or more likely emplacement of nappes on top of the ophiolite before formation of the aureole a model involving detachment of the ophiolite slice from below a subduction zone can account for the high pressures rapid uplift and erosion during displacement and the coincidence of k ar ages of amphiboles from the aureole and the sheeted dyke complex of the ophiolite

application of a linear finite frequency theory to time lapse crosswell tomography in ultrasonic and numerical experiments time lapse seismic monitoring is the geophysical discipline whereby multiple data sets recorded at the same location but at different times are used to locate and quantify temporal changes in the elastic parameters of the subsurface we validate a time lapse monitoring method by crosswell tomography using two types of wavefield modeling experiments 1 a 3d real ultrasonic waveform experiment and 2 2d synthetic finite difference wavefield simulations for both wavefield experiments a time lapse structure simulating a fluid sweep in a reservoir layer is applied the time lapse tomographic monitoring approach is based on the standard ray theory and a finite frequency wavefield theory where the latter takes into account the finite frequency properties of recorded wavefields the inverted time lapse models compiled with either the ray theory or the finite frequency wavefield theory locate and correctly quantify the flooding zone in the simulated fluid sweep model both wavefield theories provide an adequate result because the flooding zone is comparable in size to the fresnel volume

development of inverted metamorphic gradient in the internal domain of the taconian belt gaspe peninsula the mont logan nappe is part of the taconian internal domain of the quebec appalachians and is entirely made up of synrift to passive margin elastics and volcanics of the shickshock group rocks o

an energetics bedload model for a plane sloping beach local transport bagnold s energetics based sediment transport model for streams is used as a basis for the development of a model for the time varying transport of bedload over a plane sloping bed the sediment transport vector is found to consist of two components the velocity induced transport directed parallel to the instantaneous velocity vector and the gravity induced transport vector directed downslope the model is applied to the case of sediment transport within the surf zone for the separate cases of weak and strong longshore currents relative to the wave bore oscillatory water velocity the results suggest the bagnold s oscillatory sediment transport model which forms the basis for a number of longshore sediment transport models is only correct for the special case of weak longshore currents and near normal incident waves for an artibrary strength longshore current v and a local incident wave angle a the longshore transport rate is found to be proportional to sina v 1 sin sup 2 a v sup 3 where u is the wave induced oscillatory water velocity the model also predicts the onshore offshore sediment rate for weak longshore currents and near normal incident waves the predicted equilibrium beach slope is equal to tanf strong longshore currents and or significant local wave angle conditions however cause amore change in this equilibrium beach slope less authors bailard j a inman d l publication date 1981 03 20 osti identifier 6767919 resource type journal article resource relation journal name j geophys res united states journal volume 86 c3 research org scripps institution of oceanography university of california la jolla california 92093 country of publication united states language english subject 58 geosciences shores sedimentation coastal waters gravitation sediments silt velocity water currents currents surface waters 580500 oceanography 1980 1989

incipient motion of surf zone sediments incipient motion of surf zone sediments incipient motion experiments were conducted with natural gravel acetate beads and coarse gravel sized electronic grains called smart sediment grains in a small oscillatory flow tunnel measurements of fluid velocity were made using particle image velocimetry the strength of the fluid shear stresses and the pressure gradients were examined for a range of oscillatory flow conditions at the onset of motion of the sediment particles to determine which mechanism had induced particle motion the three sediment types utilized in these experiments facilitated an assessment of the effects of sediment grain size diameter shape and density on incipient motion results suggested that the onset of sediment motion was dominated by the pressure gradients for flows with small orbital excursion amplitudes by the shear stresses for flows with large orbital excursion amplitudes and by the combined effects for intermediate flows the denser angular gravel required greater free stream accelerations to trigger sediment motion than the spherical less dense acetate beads and smart sediment grains a combined parameter for incipient motion that accounts for the simultaneous effects of both shear stresses and pressure gradients while depending on the static coefficient of friction and the packing concentration of the mobile bed layer was evaluated for accuracy using a range of sediment types the results suggested that the combined parameter may be a better indicator of sediment mobilization under oscillatory flows than the typically assumed shear stress criterion

measurements of sheet flow transport in acceleration skewed oscillatory flow and comparison with practical formulations near bed oscillatory flows with acceleration skewness are characteristic of steep and breaking waves in shallow water in order to isolate the effects of acceleration skewness on sheet flow sand transport new experiments are carried out in the aberdeen oscillatory flow tunnel the experiments have produced a dataset of net transport rates for full scale oscillatory flows with varying degrees of acceleration skewness and three sand sizes the new data confirm previous research that net transport in acceleration skewed flow is non zero is always in the direction of the largest acceleration and increases with increasing acceleration skewness large transport rates for the fine sand conditions suggest that phase lag effects play an important role in augmenting positive net transport a comparison of the new experimental data with a number of practical sand transport formulations that incorporate acceleration skewness shows that none of the formulations performs well in predicting the measured net transport rates for both the fine and the coarser sands the new experimental data can be used to further develop practical sand transport formulations to better account for acceleration skewness

lagrangian measurements of incipient motion in oscillatory flows incipient motion of coarse gravel sized sediment was investigated under a range of oscillatory flows this article examines the relative significance of shear stresses and pressure gradients in triggering motion which was directly measured with electronic smart sediment grains ssgs the data suggest that incipient motion was induced by the pressure gradients in flows with large accelerations by the shear stresses in flows with low accelerations and greater shear and by the combined effects in intermediate flows a modified incipient motion criterion was evaluated accounting for the combined effects of the shear stresses and pressure gradients which may be more widely applicable in the marine environment

onshore sandbar migration in the surf zone new insights into the wave induced sediment transport mechanisms we present a novel process based morphodynamic model which includes transport processes due to both velocity and acceleration skewness and a new formulation for intrawave motions that successfully simulates observations of onshore sandbar migration results confirm findings of previous studies in which each process was considered separately and in which sediment transport was computed from the observed water motion however our results indicate that accounting for the joint action of both velocity and acceleration skewnesses causes major improvement of the modeled onshore bar migration and is essential to accurately model the evolution of the entire cross shore bottom profile when compared with observations we also demonstrate that the morphodynamics in the shoaling zone are dominated by velocity skewness bed shear stresses while sediment transport induced by acceleration skewness pressure gradients controls the morphodynamics in the inner surf zone

calculation and application of clinopyroxene garnet plagioclase quartz geobarometers recently published thermodynamic and experimental data in a variety of chemical systems have been evaluated to derive gibbs free energies for hedenbergite and pyrope these were used to calculate the geobarometric equilibria

eulerian measurements of horizontal accelerations in shoaling gravity waves laboratory and field measurements of suspended sediment in the nearshore suggest that fluid accelerations are an important factor in sediment transport by oscillatory waves here eulerian accelerations of the cross shore velocity are calculated from measurements of velocity obtained by an array of bottom mounted electromagnetic flow meters spanning a natural surf zone large shoreward accelerations of brief duration are associated with the steep front faces of both near breaking and breaking waves weaker offshore accelerations of longer duration occur during passage of the more gently sloped rear faces the acceleration field is thus strongly skewed in the shoreward direction power spectra and bispectra indicate as expected that statistics of the acceleration field are significantly influenced by high frequency motions but are rather insensitive to surf beat

shear stress and sediment transport calculations for swash zone modelling it is shown that the observed difference in sediment transporting efficiency by the swash uprush compared with the downrush could be mainly due to greater bed shear stress for a given velocity in the more abruptly accelerated uprush the bed shear stress generated by an arbitrary free stream velocity time series is modelled in terms of usual wave boundary layer models plus a phase lead phi tau of the bed shear stress compared with the free stream velocity at the peak frequency with this approach the total transport amounts in uprush and downrush can be modelled satisfactorily with the same sediment transport formula without the need for different uprush and downrush coefficients while the adaptation of sediment transport formulae from steady flow can thus lead to the right total amounts of sediment moved by this method the timing of the instantaneous sediment transport rates are probably not accurately modelled due to the highly unsteady nature of the swash and the presence of pre suspended sediment in the uprush nevertheless the proposed method is a useful intermediate step before we have a complete understanding of sediment transport under very rapid accelerations and of the relative contribution of pre suspended sediment to the onshore sediment transport in swash zones c 2002 published by elsevier science b v

taconian and acadian transpression between the internal humber zone and the gaspe belt in the gaspe peninsula tectonic history of the shickshock sud fault zone the shickshock sud fault has a history of ordovician taconian silurian salinic and devonian acadian movements taconian deformation involving ductile dextral oblique slip faulting is recorded in cambrian rocks in the footwall of the shickshock sud fault metabasalt and metaarkose at amphibolite grade are converted into phyllonite and mylonitic schist shear bands asymmetric garnet porphyroclasts c s fabrics and mica fish textures indicate dextral shearing the regional sense of shear is top to west and southwest on generally southeast dipping shear zones hornblende of metabasalt yielded an 40ar 39ar age of 455 9 2 ma and muscovite from the mylonitic schist yielded an 40ar 39ar age of 454 3 0 9 ma which indicate metamorphism and deformation during the taconian orogeny evidence for silurian activity is indicated by the salinic unconformity to the south related to normal block faulting deformation features in the ordovician and silurian devonian rocks in the hanging wall were predominantl

equilibrium shoreline modelling of a high energy meso macrotidal multiple barred beach abstract 8 year time series of incident wave energy and monthly alongshore averaged beach surveys at the high energy meso macrotidal multiple barred truc vert beach are analysed we apply two behaviour oriented equilibrium shoreline models that relate the rate of cross shore shoreline displacement to the wave energy and the wave energy disequilibrium between the wave energy and the equilibrium wave energy that would cause no change to the present shoreline location the two models show similar skill results show that the equilibrium shoreline model concept works on meso macrotidal multiple barred beaches with similar skill when applied to non barred and or micro mesotidal beaches provided that a relevant shoreline proxy is used simulations show that truc vert beach responds predominantly at seasonal timescales rather than at individual storm frequency the first winter storms drive the most pronounced erosion events because both the wave energy disequilibrium and erosion change potential are large the best shoreline proxy at truc vert beach is the mean high water level where the inner bar and berm dynamics have little influence on the shoreline cross shore displacement implications for shoreline monitoring through video imagery on this type of beach are discussed results also reveal that the equilibrium shoreline concept can be extended to an equilibrium beach profile concept pending further improvements