tectonics fluids and ore deposits mobilization and remobilization abstract the mobilization of metals leading to the formation of many known types of metallic resource involves the focussed flow of very large km 3 fluid volumes different types of fluids such as sea water and metamorphic and meteoric fluids with or without biomolecules may be specific for certain metals or suites of metals where large fluid volumes are part of a geologic process there is potential for local metal enrichment examples of such processes within the context of plate tectonics include convective flow of sea water at ocean ridges in relation to ophiolite cu zn mineralization and black smokers subduction of metal enriched sediments and the tectonic recycling of sn w mineralization metamorphic dewatering of subducted oceanic crust in the context of au deposits metamorphic degassing around high level granitic plutons and metamorphic re equilibration of the underthrust plate in relation to continental thrusting in addition during weathering processes short term leaching produces fertile soils whereas long term leaching can result in lateritic ores the large scale remobilization of ore deposits or of mineralization where metal enrichment is currently sub economic is improbable unless large fluid volumes are involved or the crust undergoes major tectonic re arrangement but it is perhaps possible that these situations are more common than we suppose and that such multistage events are indicated by the long term persistence of metallogenic provinces

perturbation solution for dam break floods a solution for the complete and instantaneous collapse of a dam in a prismatic infinitely long sloping channel is found by using the method of matched asymptotic expansions the outer solution is a kinematic wave approximation and an inner solution that includes a depth gradient term in the momentum equation is calculated for the region near the moving kinematic shock front the reservoir is modeled with a point mass source and the solution is believed to become asymptotically valid after the shock front has advanced about four reservoir lengths downstream a comparison with experiment shows good qualitative agreement but more comparisons with experiment should be made in order to assess the qualitative accuracy of the solution

metallogeny of the northern norrbotten ore province northern fennoscandian shield with emphasis on iocg and apatite iron ore deposits the northern norrbotten ore province in northernmost sweden includes the type localities for kiruna type apatite iron deposits and has been the focus for intense exploration and research related to

metallogeny and lead isotopic composition of base metal sulfide deposits in the rappen area northern sweden early proterozoic volcanic and sedimentary rocks of the rappen district in northern sweden were deposited at a destructive plate margin to the south of the archaean craton of the western baltic shield the volcano sedimentary suite was intruded by two generations of early proterozoic granites at ca 1 89 1 85 ga and ca 1 82 1 78 ga respectively and metamorphosed at upper amphibolite facies conditions small stratabound iron copper and zinc deposits occur in felsic to mafic tuffs and arkosic sediments small deposits of molybdenum tungsten and uranium formed during the emplacement of the younger granites the lead isotopic compositions of sulfide trace lead from the various deposits are highly heterogeneous in the 206pb 204pb 207pb 204pb diagram they fall on mixing arrays between little evolved early proterozoic lead and highly radiogenic caledonian lead the least radiogenic lead isotopic compositions from the various deposits have a wide range of 207pb 204pb ratios and thus indicate variable involvement of archaean crustal lead in the proterozoic deposits deposits hosted by siliciclastic rocks have higher 207pb 204pb ratios than deposits hosted in mafic to felsic tuffites the lead isotopic heterogeneity suggests that the lead in the various deposits was locally derived and furthermore that the sedimentary rocks in part originated from the archaean craton to the north lead mixing arrays in the 206pb 204pb 207pb 204pb diagram demonstrate that in paleozoic time radiogenic lead was mobilized and transported in the basement source ages calculated from the mixing arrays ca 1 9 ga and ca 1 8 ga correspond to the age of the early proterozoic volcanism and metamorphism respectively one group of deposits includes lead from at least three sources and illustrates that radiogenic lead was multiply mobilized and transported in the proterozoic basement it occurs in deposits that occur in zones that became permeable during the reactivations of the basement

response of roll wave to suspended load and hydraulics of overland flow on steep slope abstract a roll wave is frequently observed in overland flow and it can accelerate the soil erosion on slopes however the feedback effect of eroded sediment on roll wave has not been studied the aim of this study was to investigate the response of roll wave to sediment concentration and overland flow hydraulics on steep slope the experiment was carried out in a hydraulic flume the unit flow rate varied from 1 0 to 3 0 10 3 m 3 s 1 and sediment concentration from 0 to 400 kg m 3 the sediment transport was dominated by suspension slope gradient was 9 as the sediment concentration increased the critical slope length for roll wave formation increased implying that the suspended sediment in flow could inhibit the formation of a roll wave the roll wave in overland flow is a short water long wave the roll wave length increased with the increasing sediment concentration while the wave frequency and velocity decreased the decreased wave velocity meant a decrease in flow erosion potential caused by a roll wave roll wave frequency and velocity significantly increased with reynolds number froude number and mean flow velocity and decreased with the hydraulic resistance while there were no notable relationships between roll wave length and overland flow hydraulics both roll wave frequency and velocity had the strongest dependency on froude number and could be estimated by the linear equations between them when the sediment concentration was larger than 300 kg m 3 all the roll waves in overland flow disappeared due to the high sediment supply the results indicated that the suspended sediment can ease the acceleration influence of a roll wave on soil erosion and should be considered in the soil erosion models

lead mobilization during tectonic reactivation of the western baltic shield abstract lead isotope data from sulfide deposits of the western part of the baltic shield define mixing lines in the 206 pb 204 pb 207 pb 204 pb diagram lead from two types of sulfide deposits have been investigated 1 1 exhalative and volcanogenic deposits that are syngenetic with their host rocks 2 2 vein deposits the syngenetic deposits locally show a very wide range of lead isotopic compositions that reflect a variable addition of highly radiogenic lead while the vein deposits although they have radiogenic lead isotopic compositions exhibit only limited isotopic variations in different provinces of the shield both types of deposits fall on the same lead mixing array the slope of the lead mixing lines varies as a function of the age of basement rocks and the age of the tectonic event which produced the lead mobilization and therefore relates the source rock age with the age of lead mobilization calculated mixing ages fall into several short time periods that correspond either to orogenic events or to major phases of continental rifting the orogenic events are the ca 360 430 ma caledonian ca 900 1100 ma sveconorwegian and the ca 1800 1900 ma svecofennian orogenic cycles the rifting events correspond to the formation of the ca 280 ma oslo rift and the ordovician ca 450 ma graben system in the area of the present gulf of bothnia each mixing age indicates that lead was mobilized probably as a consequence of mild thermal disturbances and that the crust was permeable to lead migration the data show that the geographic distribution of sulfide deposits with highly radiogenic lead isotopic compositions coincides with old graben systems orogenic belts and orogenic forelands on the baltic shield the ages of vein deposits and their geographic distribution demonstrate multiple tectonic reactivation of the interior of the baltic shield in response to orogenic events at its margin

the use of one and two dimensional hydraulic modelling to reconstruct a glacial outburst flood in a steep alpine valley the hydrologic characteristics of the 1943 outburst flood from the glacier du mont mine switzerland are herein reconstructed using field evidence palaeostage indicators in conjunction with shallow water modelling techniques these techniques rely on accurately characterising the hydraulic roughness of the channel the water height established as boundary conditions and the main flow path during the former flood but the selection of appropriate parameter values can be problematic and hence there is uncertainty in the estimated discharge in this study minimal flow discharge estimates derived from one dimensional modelling were found to vary between 429 and 557 m3 s 1 as the hydraulic roughness ks and water height at the inlet were varied over a realistic range of values 0 8 1 4 m and 3 31 6 m respectively whereas flow rates derived via two dimensional modelling were confined in a narrower lower range of 358 454 m3 s 1 this degree of sensitivity to bed roughness ks boundary conditions and the spatial dimensions of the modelling approach is for the one dimensional modelling higher than reported in previous studies but the precision of flow discharge values reconstructed using the two dimensional modelling approach appears to be acceptable even for floods in the very steep valley 0 1 m m that is subject of this study

chemistry of proterozoic orogenic processes at a continental margin in northern sweden abstract sm nd isotopic major trace and rare earth element data for two separate age groups of plutonic rocks have been used to characterize early proterozoic crust formation mechanisms in the vicinity of the exposed archaean of northern sweden the granitoid rocks of the older 1 89 1 87 ga group show calc alkaline trends diorite quartz monzonite adamellite and have negative nd values ranging from about 8 to 5 they represent variable contamination of isotopically juvenile mantle melts with archaean crustal material the younger 1 80 ga group of plutonic rocks are of true granitic composition they show a restricted range of nd values which is encompassed by those of the older group trace and major element data are consistent with the derivation of the younger group of rocks by remobilization of the earlier formed proterozoic continental crust this is in contrast to the temporally similar but isotopically more juvenile granitoids of the skellefte district to the south

an evaluation of criteria to deduce the sense of movement in sheared rocks some of the most useful criteria for the deduction of the sense of shear are summarized for use in areas where unequivocal field evidence is lacking apparently conflicting evidence from rotated pressure shadow regions around porphyroclasts and porphyroblasts is clarified the use of quartz crystallographic fabric asymmetry to deduce the shear sense in the bulk rock should be treated with caution and used only together with detailed microstructural observations

complex conductivity of tight sandstones induced polarization well logging can be used to characterize sedimentary formations and their petrophysical properties of interest that said nothing is really known regarding the complex conductivity of low porosity sedimentary rocks to fill this gap of knowledge we investigate the complex conductivity of 19 tight sandstones 1 bioclastic turbidite and four sand smectite mixes the sandstones and the bioclastic turbidite are characterized by low to very low porosities in the range 0 8 12 3 and a relatively narrow range of cation exchange capacity 5 15 meq 100 g the sand clay mixtures are prepared with pure smectite na montmorillonite porosity 90 cec 75 meq 100 g and a coarse sand grain size 500 m data quality is assessed by checking that the percentage frequency effect between two frequencies separated by a decade is proportional to the value of the phase lag measured at the geometric frequency we also checked that the normalized chargeability determined between two frequencies is

detachment zones of cordilleran metamorphic core complexes thermal fluid and metasomatic regimes metamorphic core complexes in arizona are characterized by extensional tectonics in which listrically faulted and unmetamorphosed volcanic rocks of an upper plate are tectonically superimposed on high grade rocks of a lower plate along low angle detachment faults the detachment faults are marked by microbreccias and chloritic breccias which developed by hydraulic fracturing and metasomatism that overprinted subjacent amphibolite facies mylonites oxygen and hydrogen isotope data indicate that the mylonites formed at 500 c under conditions of low water rock ratio chloritic breccias developed at 300 350 c during incursion of hydrothermal fluids along the detachment fault hydrothermal alteration involved massive additions of fe mn and mg with concomitant depletions of k and na reflecting the hydrolysis of k feldspar and plagioclase to chlorite

effect of pressure on ore mineral solubilities under hydrothermal conditions experimental studies were conducted at elevated pressures and temperatures on the combined solubilities of iron zinc and lead sulfides in chloride solutions buffered in ph by a silicate assemblage of quartz monzonite composition plus added muscovite and buffered in s2 and o2 by the assemblage pyrite pyrrhotite magnetite major controls on base metal concentration are temperature total chloride and pressure higher temperature and higher chloride concentration favor higher metal solubilities as expected but the pressure effect is opposite to that generally expected and is of considerable importance to the problem of ore mineral transport at 500 c 0 5 kbar and 1 m total chloride fe zn and pb solubilities were 8500 4300 and 8700 ppm respectively whereas at 1 kbar they were 4200 2400 and 2600 ppm and at 2 kbar 1700 800 and 1200 ppm the experimental results thus indicate that the metals could be carried over long distances on a decreasing pressure gradient so long as the temperature decreases were not sufficient to significantly offset the pressure effect such a condition could be approximated by a near adiabatic transport cooling path such a condition is probably common geologically especially for hydrothermal processes involving fairly deep seated sources of heat and mineral components

the dam break problem for viscous fluids in the high capillary number limit experiments were undertaken to investigate dam break flows where a finite volume of highly viscous fluid glucose with viscosity 350 pa s maintained behind a lock gate was released into a horizontal or inclined flume the resulting sequence of flow depth profiles was tracked using a three dimensional visualization system in the low reynolds number and high capillary number limits analytical solutions can be obtained from the navier stokes equations using lubrication theory and matched asymptotic expansions at shallow slopes similarity solutions can also be worked out while the variation in the front position scaled with time as predicted by theory for both horizontal and sloping flumes there was a systematic delay in the front position observed moreover taking a closer look at the experimental flowdepth profiles shows that they were similar but they noticeably deviated from the theoretical similarity form for horizontal planes for sloping beds the flow depth profile is correctly predicted provided that different scalings are used at shallow and large slopes

on the reactivation of extensional fault systems in terranes that have undergone substantial extension three sets of faults dominate a shallow to steep dipping commonly rotational normal faults b a really extensive shallow dipping normal detachment faults and c steep dipping transfer faults that strike at high angles to the normal faults these fault systems may extend through a large fraction of the crust reactivation of these fault systems will depend primarily on the relative strengths of the faults shear zones and their host rock and their orientation in the prevailing stress field it is concluded that reactivation is generally mechanically favoured but that it will probably only take place when the fault shear zones are in near ideal orientations consideration of the tectonic setting of extended terranes and of the limited number of well described examples suggests that reverse thrust reactivation of the normal and detachment faults and wrench reactivation of transfer faults are the most likely styles examples of these styles are described from the bass strait basins of southeastern australia because extended terranes commonly underlie sedimentary basins for example on passive continental margins reactivation of extensional faults may be a key control on the tectonic evolution of such basins i e basin inversion

experimental insights on geomorphological processes within dam break outburst floods summary hydraulic behavior and unsteady sediment transport within dam break outburst floods are inherently inter dependent yet poorly constrained this study experimentally determined how the mobility and clast size of channel bed sediments affected the peak flow depth and flow velocities wave propagation and attenuation sediment entrainment and duration of transport flood power energy transfer and geomorphological impact of outburst floods due to our choice of clast size and of a unimodal size distribution the predominant sediment transport mechanism was bedload we found that frontal wave propagation was slower and attenuated faster for flows over a mobile bed versus those over a fixed bed peak flow depth was greater and was attained earlier for flows over a mobile bed and with increased clast size geomorphological power declined logarithmically with time after an initial period where gravitational forces exceeded frictional forces both peak and time to peak geomorphological power varied inversely with clast size peak deposition rates were greatest with coarser bed sediment but time to peak deposition rate was inversely proportional to clast size volume changes down channel were described by an exponential curve which we suggest indicates that sediment transport proceeded in waves via both translation and dispersion mechanisms peak suspended load occurred coincident with peak flow velocity peak bedload occurred coincident with peak flow depth and peak sediment discharge lagged behind peak water discharge these descriptions of kinematic transformation multi phase flow and of geomorphological work due to outburst floods help to provide data for numerical modelling for mitigating outburst flood hazards and for informing on the immediate and longer term geological legacy of outburst floods

alteration of volcanic rocks a new non intrusive indicator based on induced polarization measurements abstract induced polarization is a geophysical method investigating the ability of rocks to store reversibly electrical charges under a slowly alternating electrical field the material property of interest is a complex valued electrical conductivity with an in phase component associated with conduction and a quadrature component associated with polarization we investigated the relationship between complex conductivity spectra over the frequency range 1 mhz 45 khz and the specific surface area ssa of 28 volcanic core samples extracted from a wellbore drilled for the humu ula groundwater research project in hawaii the specific surface area of these samples was determined through the brunauer emmett and teller bet method subcritical nitrogen adsorption experiments were conducted using two different instruments and the samples were prepared in both pellets and powder forms the bet specific surface area is found to be highly correlated to the cation exchange capacity of the core samples measured by the cobalthexamine method the in phase conductivity itself can be decomposed as the sum of a bulk contribution associated with conduction in the bulk pore water and a surface conductivity associated with conduction in the electrical double layer coating the grains the surface conductivity the quadrature conductivity and the normalized chargeability defined as the difference between the in phase conductivity at high and low frequencies are observed to be linearly correlated to the specific surface area or the surface per volume ratio of the core samples which can be considered as proxy of alteration these trends are consistent with those shown by sedimentary rocks this new data set demonstrates that the induced polarization method can be potentially used to image alteration in volcanic environments

computational dam break hydraulics over erodible sediment bed this paper presents one of the first dedicated studies on mobile bed hydraulics of dam break flow and the induced sediment transport and morphological evolution a theoretical model is built upon the conservative laws of shallow water hydrodynamics and a high resolution numerical solution of the hyperbolic system is achieved using the total variation diminishing version of the second order weighted average flux method in conjunction with the hllc approximate riemann solver and superbee limiter it is found that a heavily concentrated and eroding wavefront first develops and then depresses gradually as it propagates downstream in the early stage of the dam break a hydraulic jump is formed around the dam site due to rapid bed erosion which attenuates progressively as it propagates upstream and eventually disappears while the backward wave appears to migrate at the same speed as over a fixed bed the propagation of the forward wavefront shows a complex picture compared to its fixed bed counterpart as a result of the domination of rapid bed erosion initially the density difference between the wavefront and the downstream ambient water in the intermediate period and the pattern of the deformed bed profile in the long term it is also found that the free surface profiles and hydrographs are greatly modified by bed mobility which has considerable implications for flood prediction the computed wave structure in the intermediate period exhibits great resemblance to available experiments qualitatively and yet the existence of a shear wave is found in lieu of a secondary rarefaction postulated in an existing analysis finally the use of the complete rather than simplified conservation equations is shown to be essential for correct resolution of the wave and bed structures which suggests that previous models need reformulating

isotopic data upb rbsr pbpb and smnd on mafic granulites from finnish lapland abstract a combined approach using several methods pb pb u pb rb sr sm nd on granulitic rocks selected from classic areas in northern finland is presented the results show that the emplacement of igneous rocks and the granulitic metamorphism occurred nearly coevally 1 9 2 0 ga this result which is supported by field observations means that these rocks are not ideal for comparing the response of the various parent daughter pairs to the high grade metamorphism or for checking the special geochronological possibilities of each method nevertheless because of the coherence of results from rocks of different origins a discussion is possible the bulk of the mafic granulite was certainly derived from upper mantle sources or short lived crustal mafic materials granulites of the granulitic belt and anorthosites are thought to have originated from two distinct mantle sources reflecting mantle heterogeneities at that time

experimental study on dam break waves for silted up reservoirs the overall dam break phenomenon is currently well understood for reservoirs filled with water however many dams face serious problems of reservoir sedimentation thus regarding risk management the influence of a large amount of sediment in the reservoir on dam break wave propagation is of great importance experimental investigations were performed to investigate the influence of the silting degree of reservoirs and grain size distribution on wave heights and velocities dam break waves in silted up reservoirs are the result of a two phase flow formed by a layer of water over a layer of saturated sediments in which complex phenomena occur simultaneously sediments flow such as a viscous fluid from the dam breach until complete stoppage and clear water flows over the sediments creating bed load transport the final sediment deposition cone the flow of the positive front and maximum wave heights were studied an empirical formula is proposed to describe the celerity of the positive wave front in the case of silted up reservoirs

experimental study of flash flood surges down a rough sloping channel flood waves resulting from flash floods and natural dam overtopping have been responsible for numerous losses in the present study surging waters down a flat stepped waterway slope 3 4 degrees were investigated in a 24 m long chute wave front propagation data were successfully compared with hunt s 1982 1984 theory visual observations highlighted strong aeration of the leading edge instantaneous distributions of void fractions showed a marked change in shape for t ts g do 1 3 which may be caused by some major differences between the wave leading edge and the flow behind including non hydrostatic pressure distributions plug slug flow regime and different boundary friction regime practically the results quantified the large amount of entrained air i e white waters at the wave front which in turn reduces buoyancy and could affect sediment motion at the leading edge because the sediment relative density is inversely proportional to the entrained air content

lead isotope systematics of strata bound sulfide deposits in the higher nappe complexes of the swedish caledonides 55 galena samples from 18 deposits volcanite hosted deposits have a less radiogenic lead isotope composition than sediment hosted deposits while galena in quartz segregations and crack fillings shows the most pronounced radiogenic lead isotope composition application of the plumbotectonic model to the lead isotope data for the stratiform deposits suggests that the volcanite hosted deposits show the most significant influence of a mantle related source modified journal abstract

interpretation of lead isotope data from the uraniferous cu fe sulfide mineralizations in the proterozoic greenstone belt at kopparasen northern sweden the polymetamorphic early proterozoic basic metavolcanites of the kopparasen greenstone belt northern sweden contain u mineralizations which are confined to cu fe sulfide mineralizations in mylonitized zones within basic metatuffs and graphite bearing mica schists trace lead isotope data from sulfides indicate contamination of the sulfide lead with two different lead components at ca 430 ma one lead component was leached from rocks with a 232th 238u ratio of 3 0 3 2 while the other lead component had evolved in a environment with a lower 232th 238u ratio 0 0 0 05 the source for this latter lead component underwent a u th separation probably in relation to the formation of the u mineralizations if this lead component was leached from the u mineralizations these mineralizations have a 207pb 206pb model age of ca 1 780 ma which is less than the least radiogenic lead model age of the supracrustal belt ca 2 050 ma a possible genetic model for the uranium mineralizations includes the transport of u with an oxidized metamorphic fluid which was channelled into the permeable zones and the local reduction of the fluid by sulfides which caused the precipitation of u

palaeomagnetism of precambrian rocks in northern sweden and its correlation to radiometric data abstract a palaeomagnetic study has been performed on palaeo to mesoproterozoic basic intrusions and volcanic rocks from the fennoscandian shield in northern sweden three possibly four different generations of magnetizations were identified the oldest assigned to a svecofennian age 1 86 1 89 ga a second generation is related to the intrusion of granitoids of 1 80 1 76 ga in this geological event probably also the third group of directions has its origin these different magnetizations may indicate that there are at least two different generations of basic intrusions in northern sweden a fourth group of directions is isolated as overprints this magnetization is interpreted to be a subjotnian magnetization reflecting a previously unrecognized regional subjotnian metamorphic event in the northwestern part of the fennoscandian shield the drift history for the fennoscandian shield during the period 1 88 1 50 ga has been defined based on these new palaeomagnetic data

is hydrology kinematic a wide range of phenomena natural as well as man made in physical chemical and biological hydrology exhibit characteristics similar to those of kinematic waves the question we ask is can these phenomena be described using the theory of kinematic waves since the range of phenomena is wide another question we ask is how prevalent are kinematic waves if they are widely pervasive does that mean hydrology is kinematic or close to it this paper addresses these issues which are perceived to be fundamental to advancing the state of the art of water science and engineering copyright 2002 john wiley sons ltd

asymptotic solution for dam break on sloping channel the kinematic wave approximation is used to obtain a closed form solution for the catastrophic failure of a dam upon a wet sloping channel the solution shows that increasing the initial water depth upon the channel increases both the time and distance required for the resulting shock to approach any given depth downstream it is also shown that the kinematic wave solution becomes valid only after the shock travels a certain distance downstream and that increasing the initial water depth upon the channel increases this distance

an exact solution for ideal dam break floods on steep slopes dam break floods on steep slopes occur in diverse settings they may result from failure of either natural or man made dams and they have been responsible for the loss of thousands of lives costa 1988 recent disasters resulting from dam break floods on steep slopes include those at fonte santa mines portugal in november 2006 and taum sauk missouri usa in december 2005 numerical solutions of the shallow water equations are generally used to predict the behavior of dam break floods but exact analytical solutions suitable for testing these numerical solutions have been available only for floods with infinite volumes horizontal beds or both computational models used to simulate dam break floods commonly produce numerical instabilities and or significant errors close to the moving front when steep slopes and or irregular terrain are present in the flood path in part these problems reflect the complex interaction of phenomena not included in model formulation e g intense sediment transport under timedependent flow conditions but in part they also reflect shortcomings in the numerical solution algorithms themselves therefore it is important to obtain exact analytical solutions of the shallow water equations that can be used to test the robustness of numerical models when they are applied to floods of finite volume on steep slopes this paper presents a new solution for this purpose

crustal scale shear zones and their significance to archaean gold mineralization in western australia many large archaean epigenetic gold deposits show a broad spatial relationship to regional lineaments in greenstone belts although in detail they are sited in subsidiary brittle ductile fault structures fluids originating from a deep source follow a complex path and re equilibrate with different lithologies and with metamorphic fluid during migration to higher crustal levels temperature and pressure conditions at or below the amphibolite greenschist metamorphic boundary where most gold deposits are located favour the establishment of brittle ductile and brittle subsidiary structures the preferred structural setting of gold deposits physical gradients between the regional ductile structures and more brittle subsidiary structures ensure transient strongly localized fluid flow into the latter where lower temperatures and suitable host rocks with high fe fe mg ratios favour gold deposition the multi source origin and continuous re equilibration of the fluid with crustal rock which includes granitoid and greenstone belt lithologies of different ages is reflected in the diverse isotopic and geochemical signature of the gold deposits

unsteady two dimensional paleohydraulic reconstruction of extreme floods over the last 4000 yr in segura river southeast spain summary floods in the almadenes canyon segura river southeast spain have been reconstructed using unsteady two dimensional shallow water modelling slackwater deposits archaeological age dating and hydraulic modelling allowed us to reconstruct some of the oldest extreme floods reported in spain the paleoreconstruction was performed for the first time in three steps retrodicted flood discharges for the most recent flood ad 900 were quantified comparing the simulated shields and froude numbers with respect to characteristic values for the existence of ripples and upper stage plane bed at a cave that served as a shelter for humans ensuing velocity shields and froude maps were then used as a forward predictor allowing the finding of additional paleostage indicators far from the shelter finally new psis were employed to verify the reliability of the reconstruction in doing so better insight into the paleoflood landscape was derived from consideration of the association of bedforms and modelled hydraulic conditions the present study assuming a stable geometry of the bedrock canyon during the late holocene extends the estimation of flow discharge magnitudes to ca 4000 yr bp ranging from 500 m 3 s in the oldest floods 3700 yr bp up to 700 1000 m 3 s in the most recent ad 900

on sediment transport under dam break flow we present exact solutions for suspended sediment transport under one dimensional dam break flow both over a dry bed and into a small depth of tail water we explicitly calculate the suspended sediment concentration including erosion and deposition and investigate the effect of varying the erosional and depositional models employed these solutions order insight into sediment transport processes under floods or sheet flow events and we also discuss their application as test bed solutions for the validation of numerical models

preliminary results of a palaeomagnetic and rock magnetic study of the proterozoic tsuomasvarri intrusions northern fennoscandia abstract preliminary palaeomagnetic results are presented for the proterozoic tsuomasvarri central ultramafic intrusion and surrounding older gabbro diorite intrusion in the northeastern fennoscandian shield in the ultramafic intrusion five remanence components reflecting different geological processes were isolated in the alternating field af and thermal demagnetization of 55 samples from ten sites a reversed polarity remanence component c pole plat 26 n plon 245 e dp 5 dm 9 n 32 samples dominates in the ultramafic intrusion the normal polarity pole a plat 44 n plon 232 e dp 4 dm 6 n 9 samples corresponds to an age of 1 88 ga on the apparent polar wander path apwp and is probably a thermochemical remanence acquired during the svecokarelian orogeny or in the late stages of magma cooling pole b plat 35 n plon 158 e dp 9 dm 15 n 5 samples normal polarity corresponds to the 1 75 ga old post orogenic activity in the area and is also seen in results of k ar whole rock isotopic age determinations from the vicinity the normal polarity pole d pole plat 25 s plon 285 e dp 12 dm 19 n 11 samples has a palaeomagnetic age of 2 44 ga which is in contrast with the isotopic age determination of 1 93 ga u pb age on zircon of the gabbro diorite intrusion pole f plat 3 n plon 212 e dp 10 dm 18 n 5 samples indicates an age of 0 5 0 4 ga on the palaeozoic apwp segment of fennoscandia and probably reflects a weak caledonian overprint in northeastern finland in the gabbro diorite intrusion two remanence components were isolated in 46 samples from eight sites the palaeomagnetic age 1 93 ga of the dominant normal polarity component a pole plat 40 n plon 247 e dp 5 dm 8 n 28 samples is consistent with the isotopic age of 1 93 ga u pb determination on zircon the normal polarity component d pole plat 20 s plon 285 e dp 14 dm 23 n 5 samples which was also isolated in the ultramafic intrusion contradicts the u pb isotopic age determination

newtonian fluid mechanics treatment of debris flows and avalanches calculations are carried out first for steady fully developed laminar flow on a slope application of this result to field data published in a previous paper by another author suggests that many debris flows are laminar then singular perturbation techniques are used to obtain first order solutions for unsteady non uniform flow from a point source on a steep slope solutions are obtained for both laminar and turbulent flows and it is found that the laminar flow model gives the best description of laboratory data obtained by a previous investigator a number of differences are observed in the behavior of the outer kinematic wave solutions for laminar and turbulent flow and it is suggested that it is probably not possible to describe all debris flows and avalanches with laminar flow models it is also suggested that more comparisons need to be made between theoretical results and field data measurements

fault zone reactivation kinematics and mechanisms the kinematics and mechanisms of fault zone reactivation are reviewed reactivation is dependent upon fault zone orientation and the existence of weak mylonites along these zones the recognition of reactivation within mylonite zones and the softening processes that first concentrate deformation into these and secondly provide a weak medium for reactivation are discussed attention is given to the darling mobile zone western australia and the redbank zone see obee white this symposium as examples of reactivated zones

experimental investigations of partial breach dam break flows abstractthis paper presents experimental results on partial breach dam break flows three dimensional 3d flood waves resulting from an instantaneous breach of a dam are experimentally investigated by combining different measurement techniques the dam break flow is initiated by quickly lifting a gate separating a reservoir and a downstream dry basin three different initial upstream water depths are considered the study utilizes the digital particle tracking velocimetry dptv technique for measuring the free surface velocity and water depth stereoscopic configuration of two high definition video cameras recording the movement of hollow plastic balls enabled measurement of the 3d velocity field and the water surface elevation in the near field the pressure head is measured by pressure transducers at various locations ultrasonic velocity profilers uvp are used to obtain velocity profiles in the emptying reservoir a simple nondimensional relationship for the variation of water surface elevation in

the role of fluids in syntectonic mass transport and the localization of metamorphic vein type ore deposists abstract in low to medium grade metamorphic environments the mobilization of species is closely associated with the operation of solution precipitation creep processes during foliation development such deformation processes involve dissolution of material from source sites which are usually discrete dissolution surfaces having orientations controlled by the applied stress and displacement fields mass transfer occurs via solute diffusion in an essentially static fluid network or by transport of dissolved species in a migrating fluid precipitation of material removed from dissolution sites occurs in a variety of sink sites including pore surfaces grain scale microcracks and veins sink sites may be close to or distantly removed from source sites the transport of material during deformation involving solution precipitation creep is largely controlled by the mobility of metamorphic fluids in regions of high fluid mobility significant mass transfer may occur over large distances fluid flow mass transfer paths and the development of sink sites in such cases are constrained by the structurally controlled development of high fluid pressure domains and the consequent mechanical enhancement of permeability by hydraulic fracture processes and the development of grain scale dilatancy these processes may result in focussed fluid flow and precipitation of mobilized species in restricted regions a proportion of syntectonically mobilized material is precipitated to form vein type deposits in hydraulic fracture arrays which develop in high fluid pressure environments the microstructures developed in minerals deposited in these sites reflect the interaction of a range of nucleation and growth processes which usually involve multiple generations of fracture growth and mineral crystallization the formation of syntectonic gold quartz vein deposits in central victoria australia illustrates the importance of structural controls on both the large scale migration of metamorphic fluids and the development of sites suitable for the precipitation of metamorphically mobilized species

granites and early proterozoic crustal evolution in sweden evidence from smnd upb and o isotope systematics abstract u pb zircon and whole rock rb sr sm nd and o isotope results are reported for granitoids from three proterozoic provinces in sweden that represent different crustal environments the radiometric ages span the period 1 89 1 65 ga and record events ranging from original igneous crystallisation to late metamorphic resetting these events occurred at different times in the crustal segments the o isotope ratios identify different crustal source materials for the granitoids the sm nd results indicate that the major crustal source components common to most of the granitoids formed shortly before 1 9 ga close in time to the formation of the earliest granitoids contributions from recycled archaean basement are minimal the geographically widespread occurrence of such crustal sources indicates that the period around 2 ga was of great importance for the growth of new continental crust in sweden

steady inclined flows of granular fluid mixtures we extend a recent theory for steady uniform gravity driven flow of a highly concentrated granular fluid mixture over an erodible bed between frictional sidewalls we first include angles of inclination greater than the angle of repose of the particles then we introduce a boundary condition for flow over a rigid bumpy bed we compare the predictions of the resulting theory with the volume flow rates depths and angles of inclination measured in the experiments on dry and variously saturated flows over rigid and erodible boundaries finally we employ the resulting theory with the assumption that the flow is shallow to solve in an approximate way for the variation of height and average velocities along a steady non uniform inclined flow of a granular fluid mixture that moves over a rigid bumpy bed the solutions exhibit features of the flow seen in the experiments for example a dry bulbous snout in advance of the fluid whose length increases with increasing number of the particles and that disappears with increasing velocity for which satisfactory explanations were lacking

coupled fluid dynamics sediment transport modelling of a crater lake break out lahar mt ruapehu new zealand summary lahars and other sudden onset floods are highly dynamic with temporally and spatially evolving sediment loads numerical models of sudden onset flood behaviour particularly those applied to real world events have tended to neglect sediment transport processes this is a serious though perhaps understandable shortcoming given a lack of field measurements on flow bed interactions the extra computational complexity required and the problem of iteratively updating plastic channel boundaries this paper applies a fluid dynamics model with suspended sediment and bedload transport to calculate flow conditions and rapid landscape change due to an initially dilute lahar from mt ruapehu new zealand we take advantage of an unprecedented dataset of net topographic changes determined from pre and post lahar airborne lidar surveys and time series of hydrological measurements to run and validate the model a sensitivity analysis of key controls on water surface elevation and final sediment thickness illustrates how the flow was supply limited in the upper reaches it was capable of transporting a greater volume and calibre of material than that available modelled patterns of net erosion and deposition can replicate those observed r 2 0 79 and are dominantly controlled by channel gradient and topographic

removal of pb2 from aqueous solutions using two brazilian rocks containing zeolites the removal of pb2 from aqueous solution by two brazilian rocks that contain zeolites amygdaloidal dacite zd and sandstone zs was examined by batch experiments zd contains mordenite and zs stilbite the effects of contact time concentration of metal in solution and capacity of na to recover the adsorbed metals were evaluated at room temperature 20 c the sorption equilibrium was reached in the 30 min of agitation time both materials removed 100 of pb2 from solutions at concentrations up to 50 mg l and at concentrations larger than 100 mg l of pb2 the adsorption capacity of sandstone was more efficient than that of amygdaloidal dacite due to the larger quantities and the type of zeolites stilbite in the cement of this rock all adsorbed pb2 was easily replaced by na in both samples the analysis of the adsorption models using nonlinear regression revealed that the sips and the freundlich isotherms provided the best fit for the zs and zd experimental data respectively indicating the heterogeneous adsorption surfaces of these zeolites

metamorphism in basement rocks and the implications for the tectonic evolution nasafjall window scandinavian caledonides the rocks of the nasafjall window comprise proterozoic granitoids with a metasedimentary cover of late precambrian to ordovician age the mierkenis group the metamorphic grade in the window varies from greenschist facies in the eastern part of the window to amphibolite facies in the western part the metamorphic maximum is syn to post kinematic in relation to the formation of the thrust related pervasive foliation this suggests a rapid basement heating in response to the late silurian to early devonian nappe emplacement the caledonian metamorphism terminated in middle devonian times and the retrograde phase was characterized by decompression this implies that the later stage of the thrusting was not associated with an increase in thickness of the nappe pile above the rocks of the nasafjall window

modelling outburst floods from moraine dammed glacial lakes in response to climatic change the size and number of moraine dammed supraglacial and proglacial lake systems have increased dramatically in recent decades given an appropriate trigger the natural moraine dams that impound these proglacial lakes are breached producing catastrophic glacial lake outburst floods glofs these floods are highly complex phenomena with flood characteristics controlled in the first instance by the style of breach formation downstream glofs typically exhibit transient often non newtonian fluid dynamics as a result of high rates of sediment entrainment from the dam structure and channel boundaries combined these characteristics introduce numerous modelling challenges in this review the historical contemporary and emerging approaches available to model the individual stages or components of a glof event are introduced and discussed a number of methods exist to model the stages of a glof event dam breach models can be categorised as being empirical analytical or numerical in nature with each method having significant advantages and shortcomings empirical relationships that produce estimates of peak discharge and time to peak are straightforward to implement but the applicability of these models is often limited by the nature of the case study data from which they are derived furthermore empirical models neglect the inclusion of basic hydraulic principles that describe the mechanics of breach formation analytical or parametric models simulate breach development using simplified versions of the physically based equations that describe breach enlargement whilst complex physically based codes represent the state of the art in numerical dam breach modelling to date few of the latter have been applied to investigate the moraine dam failure problem despite significant advances in the physical complexity and availability of higher order hydrodynamic solvers the majority of published accounts that have attempted to reconstruct or predict glof characteristics have been limited often by necessity to the use of relatively simplistic models this is in part attributable to the unavailability of terrain models of many high mountain catchments at the fine spatial resolutions required for the effective application of numerically sophisticated codes and their proprietary and often cost prohibitive nature however advanced models are experiencing increasing use in the glacial hazards literature in particular the suitability of emerging mesh free particle based methods for simulating dam breach and glof routing may represent a solution to many of the challenges associated with modelling this complex phenomenon sources of uncertainty in the glof modelling chain have been identified by various workers however to date their significance for the robustness of reconstructive and predictive modelling efforts have been largely unexplored and quantified in detail these sources include the geometric and material characterisation of moraine dam complexes including lake bathymetry and the presence and extent of buried ice initial conditions freeboard precise spillway dimensions spatial discretisation of the down valley domain hydrodynamic model dimensionality and the dynamic coupling of successive components in the glof model cascade

the rhombohedral framework of the scandinavian caledonides and their foreland the baltic shield of northern europe is transsected by approximately n s and nw se striking proterozoic fault and fracture zones that were remobilized during the late precambrian opening of the iapetus ocean and the se directed thrusting of the caledonian nappes in mid paleozoic time remobilizations of these older structures account for a distinct subsidence history and sedimentological evolution over each fault bounded basement segment during opening of the iapetus and for a distinct metamorphic and structural development found within each block during overthrusting of the caledonian nappes and the exhumation of the orogen the two fault sets define basement blocks with rhombus like plan sections which had individual subsidence histories during iapetus rifting as is expressed by their late precambrian riphean and vendian to silurian sedimentary cover of contrasting thickness and facies this contrasting subsidence history of the various basement blocks may have contributed to differences in thrusting level thrust excision nappe size and tectonic style correlative caledonian nappes from adjacent faultbounded basement blocks were thrust diachronously resulting in transport transverse to the general thrusting direction thrusting oblique to the nw se fault zones and orogen parallel extension resulted in lateral ramp folds in the cover and reactivation along the nw se faults imbricated the overlying nappes the extent of basement imbrication and duplex formation is variable in the different segments within single segments the basement imbrication and duplex formation defined basement highs that roughly align in two parallel zones within the orogen the site of the basement duplexes is probably controlled by older n s fracture zones while the pinch and swell structure parallel to the orogen is caused by the individual deformation and thrusting behavior of the basement and cover sequences that are bound by the nw se fault zones thus the caledonian orogen appears to have inherited the precambrian structural grain of the underlying baltic shield

isotopic composition of phanerozoic ore leads from the swedish segment of the fennoscandian shield 95 analyses of ore lead isotope ratios from 23 phanerozoic ore deposits from the swedish segment of the fennoscandian shield form a marked linear trend on a 207pb 204pb versus 206pb 204pb diagram the line may be interpreted in a two stage model the lead being derived from 1 8 0 15 ga old svecokarelian basement and mineralization occurring at 0 4 0 15 ga the initial composition of the svecokarelian rock lead was similar to the lead in early proterozoic volcanogenic sulfide ores in sweden the large spread in the isotope ratios was caused by a combination of selective leaching of different minerals in the source rocks mixing with less radiogenic caledonian lead and local or regional variations in the u th and pb contents of the basement as a consequence conventional methods of identifying source rocks from lead isotopic data e g mu values th u ratios may not be directly applicable phanerozoic ore lead development in the swedish section of the fennoscandian shield was ensialic that is the ore lead was almost entirely derived from the precambrian basement although this basement does not appear to be anomalously enriched in pb no juvenile or mantle lead was apparently contributed to this section of the crust after the precambrian except for that mechanically transported onto the western edge of the shield by the caledonian nappes however some of europe s largest lead deposits are included in these swedish phanerozoic mineralizations suggesting that it was the nature of the processes involved rather than the richness of the source that determined their formation

on fine sediment transport by long waves in the swash zone of a plane beach we calculate suspended sediment transport erosion and deposition under reflected long waves on a plane beach our method employs the shallow water equations and is based on the calculation of the concentration field in lagrangian coordinates this allows results to be obtained readily throughout the whole domain including the often troublesome shoreline region these results suggest that the tendency of wave dominated muddy shores to export sediment and erode over long time scales is not due to wave forcing at infragravity frequencies since the sediment transport under such waves is localized close to the shoreline and is principally directed shorewards they also provide easily reproduced test cases against which to validate the numerical methods used in more detailed studies of coastal sediment transport and morphodynamics

shallow water theory for arbitrary slopes of the bottom a new shallow water theory valid for arbitrary bottom slope due to bouchut et al 2003 is derived systematically by a scaling method the fact that the pressure is hydrostatic and the form of the velocity parallel to the bottom are consequences of the scaling method and need not be assumed

tectonic control of precambrian molybdenite mineralization in northern sweden the major molybdenite occurrences of n sweden are mostly confined to the proterozoic continental domain the molybdenite occurrences are in aplites pegmatites and metamorphosed volcanics located

discussion of computing nonhydrostatic shallow water flow over steep terrain the authors are to be commended for their valuable and unique comparison of experimental data for clear water dam break floods on steep slopes and for their nonhydrostatic shallow water model the dam break experiments down a steep slope at the usgs outdoor laboratory logan and iverson 2007 mimic the behavior of natural flows and shed light on different mechanisms inertia viscous dissipation pressure gradient that control the flow dynamics the discusser has studied roll wave development in dam breaks and similar problems on steep slopes restricted to relatively long timescales for which the kinematic regime is reached and the authors fine results present a great opportunity to consider some interesting features of the dam break wave it is understood that there is a lack of validation of asymptotic solutions for dam break waves on steep slopes based on the kinematic wave approximation lighthill and whitham 1955 with both experimental data and numerical simulations even the earlier solutions by hunt 1982 1984 and weir 1983 for shallow slopes have not yet been validated as discussed by hunt 1984 a comparison with experiment shows good qualitative agreement but more comparisons with experiment should be made in order to assess the qualitative accuracy of the solution this question remains still unresolved e g singh 2002 and references therein to address this point the value of enhanced gravity g must

horizontal viscous dam break flow experiments and theory this paper considers dam break flow occurring in a horizontal smooth channel experiments were carried out with highly viscous newtonian fluids e g glucose syrup water solutions the frontal shape of dam break flow and its evolution as well as the free surface profile were measured using video photographic and ultrasonic equipment respectively new features of viscous dam break flow are pointed out notably indicated are flow regimes and the effect of reservoir length as well as the effect of fluid viscosity on flow development equations describing dam break flow are derived in nondimensional form then compared with the results from experiments

possible controls of base and precious metal mineralization associated with tertiary detachment faults in the lower colorado river trough arizona and california base and precious metal mineral deposits are located along and adjacent to tertiary detachment faults in western arizona and southeastern california mineralization is characterized by early copper and iron sulfides followed by massive specular hematite in turn followed by fracture filling chrysocolla and malachite mineralization occurred during faulting and was associated with unusually high geothermal gradients that were at least partially due to detachment fault movement that brought hot lower plate rocks up from great depth and juxtaposed them with cool near surface upper plate rocks mixing of ascending reduced metal bearing aqueous solutions with higher level oxidized fluids is proposed as an important process leading to oxide mineralization movement of the redox interface down normal fault ramps at the same rate as displacement of hanging wall rocks resulted in continuous mineralization at some upper plate sites over significant periods of geologic time this produced the largest orebodies aqueous solutions that precipitated iron oxides near the detachment fault carried manganese oxides to higher levels where vein and strata bound sedimentary manganese oxides were deposited

transport of suspended sediment under the dam break flow on an inclined plane bed of arbitrary slope the problem of transport of suspended sediment after the break of a dam on an inclined bed is considered to that end we use the shallow water approximation for arbitrary constant slopes of the bottom taking into consideration the effect of friction the numerical technique and the frictional model are validated by comparison with available experimental data and asymptotic analytical solutions with special attention to the numerical solution near the wetting front the transport of suspended sediment down the inclined bed is obtained and discussed as a function of the slope of the bed for different values of the parameters characterizing the sediment and its transport properties for sufficiently large times we always find the formation of roll waves near the water front which affects the transport of sediments significantly these strong oscillations are accurately computed with the numerical method used the relative importance of the bed load to the suspended load sediment transport is also discussed as a function of the size of the sediment particles and the slope of the bed for different models on the initiation of sediment suspension from bed load we also check the dilute sediment approach and characterize the conditions for its failure finally the results of the present simplified model are intended to be used as tests of more complex numerical models

lead mobilization during foreland metamorphism in orogenic belts examples from northern sweden the imbrication of the proterozoic basement during the caledonian orogeny was associated with fluid flow which caused locally low grade retrograde metamorphism of the basement and which introduced externally derived radiogenic lead 206pb 204pb 20 0 into permeable zones this radiogenic lead was leached from the proterozoic basement to the east of the present day caledonian front radiogenic lead is a pertinent geochemical tracer of the caledonian imbrication of the proterozoic basement since lithostratigraphic marker beds are absent and the distribution of the retrograde metamorphism also could reflect a proterozoic event

the genesis and tectonic control on archaean gold deposits of the western australian shield a metamorphic replacement model abstract gold deposits occur in greenstone belts world wide and contribute to anomalously high gold production from archaean terranes as in other cratons archaean gold mineralization of western australia represents a complex array of deposit styles despite this most deposits are clearly epigenetic and large deposits have a number of features in common including their strong structural controls distinctive wallrock alteration fe sulphide k mica albite ca mg fe carbonates consistent metal associations au ag as sb w b low base metals commonly fe rich host rocks great depth extension and lack of appreciable vertical zonation these shared characteristics combined with their ubiquitous occurrence indicate that archaean gold deposits had a common origin related to the tectonic evolution of greenstone belts auriferous hydrothermal systems were broadly synchronous with regional metamorphism and emplacement of synkinematic granitoids and felsic porphyry intrusions although these gold systems involved low salinity lowdensity reduced near neutral h 2 o co 2 fluids carrying gold as reduced sulphur complexes the origin of the fluids is equivocal most timing evidence and stable isotope data cannot distinguish metamorphic from magmatic granitoid or felsic porphyry orggins but the lack of consistent spatial relationships between specific volumetrically significant intrusive phases and large gold deposits in a number of cratons strongly favours metamorphic derivation of fluids the metamorphic replacement model for gold mineralization involves devolatilization of the lower portions of the greenstone pile with high geothermal gradients inhibiting significant melting co 2 possibly formed by the decarbonation of early alteration related to mantle degassing along crustal scale synbasinal fault zones auriferous fluids were channelled along greenstone scale faults in part developed during reactivation of crustal scale faults in a strike slip regime gold deposition occurred largely under greenschist facies conditions about 300 400 c 1 2 kb in response to decreasing gold solubility with declining temperature however a major control on gold deposition was fluid wallrock interaction many large deposits formed by sulphidation of fe rich host rocks with synchronous deposition of fe sulphides and gold however the variable nature of gold depositing reactions including lowering of fo 2 and ph allowed a multitude of small and some large deposits to form wherever that fluid circulation occurred in consequence several of the relatively small deposits currently worked from open pit are hosted by ultramafic and felsic rocks there are few constraints on the source of components au s k co 2 added to gold deposits but even giant deposits such as the golden mile kalgoorlie could have formed from a realistic greenstone source volume ca 8 8 5 km convective circulation of fluids could have contributed to the generation of high fluid rock ratios on the regional scale the markedly heterogeneous distribution of large gold deposits gold productivity and host rocks to deposits can be accommodated by the metamorphic replacement model the most favourable conditions for development of auriferous hydrothermal systems operated in younger ca 2 7 0 1 ga rift phase greenstones where greatest extension and crustal thinning produced high geothermal gradients crustal scale synbasinal faults and rapid extrusion and burial of volcanics including abundant komatiites iron rich tholeiitic basalts and dolerites were preferred host rocks for large gold deposits the least favourable conditions existed in older ca 3 5 3 4 ga platformphase greenstones where gentle sagging on submerged continental crust produced eruption of mainly mafic volcanics with few komatiites commonly in very shallow water environments this allowed intense synvolcanic alteration of both gold source rocks and potential host rocks the generally smaller gold deposits formed mainly in ultramafic or greywacke hosts younger ca 3 0 ga platform phase greenstones appear intermediate in nature but unlike other greenstones have significant epigenetic gold deposits in originally oxide facies bif which were deposited on relatively deep water platforms similar controls appear to exist on a world scale with gold mineralization peaking at ca 2 7 0 1 ga in response to development of major rift zones in thickened relatively mature continental crust interestingly the giant witwatersrand goldfield formed at about the same time

dam break outburst flood propagation and transient hydraulics a geosciences perspective summary dam break outburst floods are sudden short lived and high magnitude discharges of water and sediment propagating over an initially dry terrain both field observations by geoscientists and experimental measurements by engineers have produced understanding of outburst floods but neither approach has satisfactorily supplied data that is directly of use to hazard managers this study draws together those two literature groups and provides new experimental data to test hypotheses concerning the effect of a series of external controls on resultant longitudinal flow propagation and transitory hydraulics these external controls form experimental treatments and are i the height of the lock gate raise as a surrogate for dam breach evolution and initial hydrograph ii bed roughness and iii suspended sediment concentration these control both horizontal and vertical fluid motion the latter of which is a key property for controlling aeration bed shear stress and turbulence intensity the experimental treatments show that outburst floods on horizontal beds can be identified to possess three longitudinal flow regimes firstly there is a short acceleration due to the reservoir pressure level i e the depth of impounded water secondly channel flow quickly converges to an inertial regime the third flow regime is viscous and dominated by channel bed friction flow depth increases in the inertial regime then decreases in the viscous regime experiments herein show that the timing of the peaks at a point down channel of each hydraulic quantity varies most notably peak bed shear stress precedes flow velocity which precedes peak flow depth a point of inflexion occurs with distance down channel that is a manifestation of the transition from accelerating to decelerating flows these external controls and the effects of them on longitudinal and vertical motion are analysed statistically and quantitative relationships are derived to underpin the resultant conceptual model this conceptual model should serve as a platform for future probabilistic and process based modelling of outburst floods

two dimensional analysis of dam break flow in vertical plane this work presents numerical computations for the analysis of dam break flow using two dimensional flow equations in a vertical plane the numerical model uses the general approach of the simplified marker and cell method combined with the volume of fluid approach for the surface tracking the time evolution of flow depth at the dam site and the evolution of the pressure distribution are investigated for both wet and dry bed conditions the effect of the initially nonhydrostatic state on the long term surface profile and wave velocity are studied these long term effects are found to be marginal in the case of wet bed conditions but are significant in dry bed conditions the dry bed tip velocity immediately after the dam break computed numerically compares well with analytical results published previously the time taken to obtain a constant flow depth at the dam site increases with decreasing initial depth ratio the numerical result for this time elapse for dry bed conditions is close to the experime

experimental study and numerical verification of silted up dam break abstract in this study multiphase flood waves caused by failure of silted up dams have been scrutinized experimentally and efficacy of the public domain cfd software openfoam numerical models to represent such phenomenon is evaluated experimental observations are sparse on dam break for reservoirs with high sediment depths called silted up reservoirs sediment layer in this case may behave as a viscous fluid and produce a complex multi layer flow of air and water overtopping a sediment layer massive sediment quantities can have a substantial impact on the wave propagation pattern caused by dam break this study contributes to an experiment based understanding of dam break phenomenon with silted up reservoir and elaborates the propagation of multi layer waves herein different hydraulic conditions were experimentally observed including 8 different upstream sediment depths in the range of 0 0 24 m and 4 downstream initial water levels of 0 0 02 0 04 and 0 05 m which collectively created 32 scenarios the resulted waves were filmed by high speed cameras and data were extracted through image processing an open source cfd software namely openfoam was employed to simulate the experiments using two distinct numerical approaches volume of fluid vof and eulerian results of both numerical approaches were in good agreement with the experimental measurements with mae and rmse error values varying from 0 006 m to 0 031 m and 0 008 m to 0 043 m respectively 2 to 10 and 2 6 to 14 with respect to the reservoir height of 0 3 m the eulerian approach showed marginally superior performance to vof especially in cases with high sediment depths which is likely due to accommodating phase mixing a wide collection of high quality data is made available online in the appendix data and could be utilized in future studies

rupture creep lamellae and crocodiles happenings in the continental crust from the observation of certain seismic reflectivity patterns in phanerozoic continental crusts a relationship is suggested between 1 rupture and seismicity generally restricted to the upper crust 2 crocodile tectonics a kind of vertical indentation observed by diverging plane reflectors preferably in the middle crust 3 creep and the formation of reflecting lamellae in the lower crust based on these observations and on viscosity depth estimates a conceptual model for the above mentioned structures is presented which is also compatible with observations in older crusts boundary conditions are given for rupture as well as for lamellae forming creep

the geological and tectonic evolution of the precambrian of northern sweden a case for basement reactivation abstract this study is the result of a regional mapping programme of the precambrian to the extreme north of sweden by the geological survey of sweden in the years 1976 1981 it takes into account most of the geological geochemical and geophysical data concerning the region a brief description and revision of the stratigraphy is given in the light of recent mapping results and radiometric age determinations an attempt is made to trace the main petrogenetic trends of the volcanic and the plutonic rock series in order to determine which geotectonic model can best be inferred for the region following the archaean consolidation phase two major tectonic episodes have been recognized 1 a tensional episode characterized by incipient rifting which resulted in the extrusion of basic magma and in the deposition of predominantly quartzitic sediments and 2 a complex episode of reactivation of older structures and formations corresponding to the peak of the svecokarelian orogeny and to later consolidation this tectonic evolution is interpreted here as a phase of basement reactivation and shows much resemblance to ensialic mobile belts described in other parts of the world a characteristic feature of the aeromagnetic gravimetric and landsat maps is the profusion of circular and arcuate structures of variable magnitude and distinctiveness the possibility that some of these are due to the process of sequential inheritance of early impact scars is discussed

kinematic wave solutions for dam break floods in non uniform valleys abstract in non uniform valleys dam break flood waves can be significantly affected by downstream variations in river width slope and roughness to model these effects we derive new analytical solutions to the kinematic wave equation applicable to rating curves in the power law form and hydrographs of generic shape as long as they produce a single shock at the wave front new results are first obtained for uniform channels using the gauss green theorem applied to characteristic bounded regions of the x t plane the results are then extended to non uniform valleys using a change of variable that homogenizes river properties by rescaling the distance coordinate the solutions are illustrated and validated for idealized cases then applied to three historical dam failures the 2008 breaching failure of the tangjiashan landslide dam the 1976 piping failure of teton dam and the 1959 sudden failure of malpasset dam in spite of the much reduced computational cost and data requirements the results agree well with the field data and with more elaborate simulations they also clarify how both river and hydrograph properties affect flood propagation and attenuation

hydraulic determination of dam releases to generate warning waves in a mountain stream performance of an analytical kinematic wave model abstractthis study examines the generation of warning waves with prescribed characteristics in a mountain stream the authors determine which dam release will generate the desired warning wave the

the western border of the archaean province of the baltic shield evidence from northern sweden restricted areas of acid to intermediate gneisses in northernmost sweden are known to be archaean and several other gneissic granodioritic to tonalitic massifs have been suggested to be of this age to delimit the western border of the archaean province of the baltic shield and to characterize the swedish archaean we have studied the 2 83 ga old soppero gneiss and 8 of the proposed archaean massifs in northern sweden by sm nd isotopic analyses u pb zircon dating in two cases and geochemistry

origin and deposition of a graphitic schist hosted metamorphogenic au w deposit macraes east otago new zealand the macraes gold tungsten deposit occurs in a low angle thrust system in biotite grade otago schist native gold scheelite pyrite and arsenopyrite are found in and adjacent to quartz veins and silicified schist of lenticular reef zones where the thrust system cuts through graphitic pelitic schist mineralization is confined to a shear zone up to 80 m thick which is closely sub parallel to the regional schistosity chemical alteration is dominated by silicification with some addition of cr and depletion of sr and ba alteration extends only about 5 m from major veins oxygen becomes isotopically heavier away from veins due to temperature decrease as hot fluids penetrated into cooler 250 c rock graphite within the shear zone rocks has reflectance of 6 7 in oil similar to graphite in medium high grade otago schist and is presumed to be metamorphic in origin this graphite has acted as a reducing agent to cause precipitation of gold where the thrust system acting as a conduit for metamorphic fluids intersects the graphitic schist the metals were derived from the underlying schist pile which may include an over thrust oceanic assemblage containing metal enriched horizons

scaling relationships for constant volume snow avalanches we present simple scaling relationships that allow us to predict the main dynamical characteristics height length and velocity of constant volume snow avalanches with minimal input data in particular we show that both avalanche height and length can be expressed as a function only of the avalanche volume and the distance travelled by the front independently of the specific rheological parameters of the snow these scaling relationships are derived from a large time asymptotic solution to the avalanche dynamic equations corresponding to a balance between gravity and voellmy friction the kinematic wave approximation numerical simulations of the complete hydraulic shallow flow equations confirm that this asymptotic solution and the predicted scaling relationships capture the main avalanche characteristics even for relatively small travel distances though derived under restrictive assumptions we argue that the scaling relationships described in this paper may constitute useful tools for avalanche engineering and design of protective structures

a note on groundwater flow along a hillslope 1 particular cases of groundwater flow along a hillslope are studied using the groundwater hydraulic theory e g dupuit approximation described by the boussinesq equation analytical solutions are found as simple transformations of known similarity solutions in particular the expressions for phreatic surface level and volume flux and the corresponding loop rating curve for the flow of a groundwater mound as well as the travelling wave solutions of the boussinesq equation are described in detail

lead isotope composition of caledonian sulfide bearing veins in sweden linear trend in the 207 pb 204 pb vs 206 pb 204 pb diagram extending from a normal caledonian lead composition 206 pb 204 pb nearly equal 17 9 to highly radiogenic values 206 pb 204 pb nearly equal 26 0 early proterozoic svecokarelian basement as source of the radiogenic component selective leaching of different minerals in the svecokarelian rocks and mixing with various proportions of nonradiogenic caledonian magmatic lead modified journal abstract

models of dam break flow in r t space in this study a radial flow version of a characteristics based numerical model reproduced the effects anticipated for dam break flows between convergent and divergent walls four physical models were tested plain x t 2 contracted plain rt xt 3 contracted expanded rt rt and plain expanded xt rt it was found that both surface heights and mean velocities increased in the convergent sections and decreased in divergent ones successive depth profiles intersected the dam location at heights exceeding 4 9 reservoir depth for the convergent case and lower than this value for the divergent cases composite numerical modeling of x t and r t cases provided satisfactory simulation of certain phenomena which were also observed on physical models details of the study are described and the results are discussed

analytical solutions for gradual dam breaching and downstream river flooding 1 an analytical model is proposed to describe lake drainage and downstream flooding due to the gradual breaching of natural and manmade earthen dams erodible triangular dams are considered undergoing gradual incision by a breaching channel of constant effective width adopting a simple stream power law for dam material transport the long profile evolution of the breaching channel is governed by a diffusion equation with variable diffusion rate proportional to the water discharge the resulting flood is routed downstream using the kinematic wave equation moving boundary problems are obtained due to retrogression of the breach crest and to the downstream propagation of the flood wavefront for both the dam breaching and flood routing problems explicit analytical solutions are derived they depict a breaching process that is at first self accelerating then becomes self limiting results include boundary paths long profiles and stage and discharge hydrographs in particular the breaching solution yields a discharge hydrograph of simple analytical shape that turns out to be ideally suited for kinematic wave routing the model is applied to the well documented breaching of the tangjiashan landslide dam sichuan in june 2008 calculated results for this and other cases are in reasonably good agreement with the measured data as the model is simple to apply with minimal computational and data requirements it could prove useful as a tool for rapid risk assessment the proposed analytical approach also complements numerical models by providing more transparent links between solution outcomes and the problem data

bed load sediment transport on steep longitudinal slopes the results of new experiments on bed load transport on steep longitudinal slopes are presented the experiments were carried out in a large tilting duct with a fine sand median grain diameter of 208 micro m covering the range of slope angles beta of angle of repose for the sand phi sub s of 32 deg 0 56 rad measurements included bed shear stress flow discharge and the sediment pickup rate on slopes the results suggest that existing theories for bed load transport on slopes are not adequate for all bed slopes and the new data are used to formulate a semiempirical relation that satisfactorily predicts the transport rate on horizontal as well as mild and steep slopes the following are two important findings correcting the threshold term for slope in the meyer peter and muller formula adequately describes the transport rate on positive slopes elevation increasing in direction of flow and on small negative slopes while on steeper negative slopes an extra correction term is required although the value of beta phi sub s at which this term becomes necessary is a function of shear stress and the influence of slope vanishes at high shear stresses

implications of new upb zircon chronology to early proterozoic crustal accretion in northern sweden abstract u pb ages ranging from 1 89 to 1 78 ga are reported for zircon populations formed during major magmatic events in the proterozoic development of northern sweden the studied area includes parts of the continental and the marine svecokarelian domains of the baltic shield the ages record crustal accretion and reactivation off the margin of an exposed archaean craton and show that magmatism was broadly coeval throughout the entire north swedish portion of the svecokarelian province irrespective of regions involved a detailed chronostratigraphy is presented for the skellefte district of northern sweden and comparisons are made with the evolution in other parts of the svecokarelian province two main magmatic phases commencing at 1 89 and 1 79 ga ago are recognized the first represents large scale volcanism and plutonism which in the skellefte district was characterized by the introduction of mainly mantle derived magmas or by magmas formed from rocks with short crustal residence time in the vicinity of the archaean craton some distance to the north the crust generating processes included the mobilization of archaean sources and appear to have continued until c 1 85 ga ago a relatively long period of consolidation and denudation separates this magmatic phase from the one at c 1 79 ga ago the generation of these later migmatite associated granites in the svecokarelian province coincided in time and was possibly associated with those processes which gave rise to the initial plutonism in the neighbouring transscandinavian granite porphyry belt