subglacial deforming bed conditions recorded by late quaternary sediments exposed in vineland quarry ontario canada abstract there has been considerable interest in recent years in the development of theoretical models of subglacial transport and deposition of sediment but relatively few studies report field documentation of the resultant sediment stratigraphies this paper presents detailed sedimentological description and analysis of a succession of late quaternary deposits interpreted to record subglacial overriding and deformation of previously deposited lacustrine sediments exposed in the vineland quarry that sits close to the crest of the niagara escarpment within the lake ontario basin the predominately fine grained sediments record deposition under glaciolacustrine conditions followed by deformation and deposition by overriding glacial ice laminated silt and clay deposits overlie the striated bedrock surface and were deposited within a lake that formed as the ontario lobe of the laurentide ice sheet advanced during the port huron stadial and ponded water against the niagara escarpment the laminated silt and clay facies show increasing amounts of deformation up section passing from planar through ductile to brittle deformation this succession of deformed facies is overlain by a macroscopically massive clay rich diamict that caps the section this pattern of sediment deposition and deformation is consistent with that proposed by current models of subglacial sediment deformation with the disrupted laminated silts and clays representing glacitectonites resulting from downward penetrating stresses imparted by an overriding ice sheet the uppermost massive diamict unit represents full macroscopic homogenization of the overridden sediment and is classified as a subglacial traction till the gradual transition from undisturbed laminated deposits through increasingly deformed sediment to structureless diamict suggests that these deposits record a single episode of ice advance across the region this ice advance was probably the short lived advance of the ontario lobe of the laurentide ice sheet that occurred at approximately 13 000 ybp

modelling of the evolution of ground waters in a granite system at low temperature the stripa ground waters sweden abstract from chemical data collected by nordstrom and his colleagues on stripa ground waterswe have tried to model the evolution of the chemical composition of a ground water in a granitic system at low temperature the existence of two end member ground water compositions made it possible first to test the conventional model of a geothermal system according to which an overall equilibrium between the waters and a given mineral assemblage can be defined and then to show that such a model could be extended to low temperatures 10 c conversely if we know the mineral assemblage the equilibration temperature and the charge of the mobile ions in this case cl the composition of the solution is entirely fixed in our model of the stripa ground waters the existence of two end member ground water compositions can be explained by an evolution from a kaolinite albite laumontite equilibrium to a prehnite albite laumontite equilibium the latter requiring less al than the former we have also emphasized the importance of the cl ion concentrions ofof the ground waters because they cab be considered as indicators of the degree of reaction progress between rock and water thus determining the degree of equilibration of the system

hydraulic modelling of subglacial tunnel channels south east alberta canada one of the key issues associated with the hypothesis of catastrophic subglacial drainage of the livingstone lake event is whether flows of such large magnitudes are physically feasible to explore this issue a one dimensional hydraulic network flow model was developed to investigate the range of peak discharges and associated flow parameters that may have been carried by a tunnel channel network in south east alberta canada this tunnel channel network has been interpreted elsewhere to carry large discharges associated with subglacial meltwater flows because of the convex longitudinal profiles of individual channels this computational modelling effort draws upon established and verified engineering principles and methods in its application to the hydraulics of this problem consequently it represents a unique and independent approach to investigating the subglacial meltwater hypothesis based on the modelling results it was determined that energy losses resulting from friction limit the maximum peak discharge that can be transported through the tunnel channel network to 10 7 m 3 s 1 which is in reasonable agreement with previous estimates of flood discharges for proposed megafloods results show that flow through channels with convex longitudinal profiles occurs when hydraulic head exceeds 910 m lost river and 950 m sage creek respectively these are considerably below the maximum head capable of driving flow through the system of 1360 m beyond which ice is decoupled from the bed across the pre glacial drainage divide therefore it is concluded that these model results support the hypothesis of catastrophic subglacial drainage during the livingstone lake event

geomorphology of the onset area of a paleo ice stream marguerite bay antarctic peninsula geomorphic features indicate that both glacial and melt water erosion characterize the onset area of the ancestral marguerite ice stream the large size of these features indicates that they formed over repeated glacial cycles most recently during the last glacial maximum ice drainage within the bay and on the inner continental shelf was strongly influenced by tectonic fabric deep isolated basins surrounded by rugged bedrock bathymetry characterize the innermost part of the bay drumlins and other streamlined features occur in the floors of these basins at depths of up to 900 m the outer bay has three large interconnected basins drumlins and megaflutings within these basins indicate ice was grounded at water depths up to 1000 m the orientations of these features show convergence of drainage from the northeast east and south into the marguerite paleo ice stream on the inner continental shelf the ice converged into a single wide trough dominated by mega scale glacial lineations this transition in geomorphic features from drumlins and megaflutings to mega scale glacial lineations occurs at the location on the continental shelf where sedimentary strata blanket bedrock and marks a zone of acceleration of the ice stream the glacially sculptured geomorphic features within marguerite bay co exist with anastomosing radial and relatively straight channels which become increasingly focused in a seaward direction this implies that a well organized subglacial drainage system existed within the bay at some point in the past copyright 2008 john wiley sons ltd

seismic reflection borehole and outcrop geometry of late wisconsin tills at a proposed landfill near toronto ontario the search for new landfill sites in the greater toronto area of southern ontario canada is producing a wealth of data regarding the subsurface stratigraphy and geometry of late wisconsin 25 ka

estimation of deep reservoir temperature of co2 rich springs in kangwon district south korea abstract weakly acid to neutral co 2 rich springs ph 5 5 to 6 7 with high concentrations of dissolved ions tds 419 to 3091 mg l and bicarbonate 249 to 2470 mg l occur in kangwon district south korea they are grouped into three chemical types na hco 3 ca na hco 3 and ca hco 3 the na hco 3 type waters correspond to mature or partially equilibrated waters while the other two types show the hydrochemical characteristics of immature waters in this study we examined the applicability of chemical geothermometers and multiple mineral equilibrium approach to estimate potential deep reservoir temperatures the application of silica na k and na k ca thermometers to a representative na hco 3 type water yielded a reasonable temperature estimate 115 157 c for a deep geothermal reservoir the multiple mineral equilibrium approach yielded a similar temperature estimate about 140 160 c on the other hand the ca hco 3 type waters showed a relatively low and wide range of temperature estimates about 60 130 c which suggests that their disequilibrium state is possibly due to surface water mixing we believe that deep reservoir temperatures of co 2 rich groundwaters in kangwon district can be estimated from the chemistry of na hco 3 type waters and possibly approach 140 160 c

feldspar saturation state in natural waters the saturation state of feldspar minerals in natural waters ranging from 0 c to over 300 c was studied waters above 200 c have closely approached equilibrium with microcline and low albite this is consistent with the occurrence of these minerals as hydrothermal minerals in active geothermal systems with temperature in excess of some 200 c the na k activity ratio of geothermal waters with temperature as low as 50 c closely approaches that predicted from thermodynamic data for the reaction low albite k microcline na suggesting that na and k ion activities in these geothermal waters are controlled by simultaneous equilibrium with these two feldspars geothermal waters are undersaturated with primary disordered plagioclases and alkali feldspars of compositions typically found in volcanic rocks accordingly these feldspars tend to dissolve in such waters simultaneously with precipitation of ordered alkali feldspars surface and non thermal groundwaters are usually undersaturated with respect to igneous and metamorphic feldspars regardless of composition and al si ordering and tend therefore to dissolve under weathering conditions

the 1983 hydraulic jump in crystal rapid implications for river running and geomorphic evolution in the grand canyon for the last 1 000 to 10 000 years dozens of large debris fans have severely constricted the path of the colorado river in the grand canyon arizona at most of these fans the narrowest part of the channel eroded by the river is 0 5 of the upstream width at crystal creek a debris fan was emplaced in 1966 constricting the channel of the colorado river to about 0 25 of its upstream width between 1967 and 1983 forming a major rapid in this paper the hydraulics of crystal creek rapid are described and an analysis is presented to support the hypothesis that the major wave in the rapid was a normal wave one type of hydraulic jump hydraulic jumps rarely occur in natural river channels with erodible beds but one was present at crystal rapid because of the unusually severe constriction of the colorado river by the 1966 debris fan observations on the hydraulics of the river during this time including mid 1983 when progressively higher discharges culminated in excess of 96 000 cubic feet per second h

bedform genesis in bedrock substrates insights into formative processes from a new experimental approach and the importance of suspension dominated abrasion bedrock channels are common in the natural environment and bedrock channel erosion sets the pace of denudation in many river catchments however in comparison to the large number of studies concerning the formation of alluvial bedforms relatively few investigations have concerned bedrock bedform genesis field based analysis of sculptured forms within bedrock channels has been restricted notably by the slow rate of bedform development in such environments furthermore only a limited number of flume scale experiments have been conducted that attempt to simulate the genesis of sculpted bedforms in bedrock channels this study demonstrates that optimisation of clay beds through analysis of clay strength enables the development of features analogous to bedrock river channel bedforms even at a scale that is orders of magnitude smaller than some natural examples three sets of suspended sediment laden experiments were carried out using hard medium and soft clay bed substrates a suite of erosive bedforms including potholes flutes and furrows developed on all experimental beds all observed erosional features have clear equivalents to those observed in natural bedrock rivers bed shear strength was found to be a significant factor for the genesis of different types of simulated bedrock bedforms in our experiments with other factors such as flow velocity bed slope and flow depth held approximately constant importantly in a subset of experiments performed with an absence of suspended sediment fluid flow did not result in the erosion and development of bedforms in the clay bed hence this work illustrates that abrasion by suspended sediments is the key process required for the formation of these simulated bedrock bedforms in our experiments in the absence of bedload abrasion other processes such as plucking cavitation and dissolution will have been negligible

hydrochemistry and geothermometrical modeling of low temperature panticosa geothermal system spain abstract the chemical characteristics of the low temperature geothermal system of panticosa spain were investigated in order to determine the water temperature at the reservoir and to identify the main geochemical processes that affect the water composition during the ascent of the thermal waters in general the studied waters are similar to other geothermal systems in the pyrenees belonging to the group of granite related alkaline thermal waters high ph low total dissolved solids very low magnesium concentration and sodium as the dominant cation according to the alkaline ph of these waters they have a very low co 2 partial pressure bicarbonate is the dominant anion and silica is partially ionized as h 3 sio 4 the unusually active acid base pairs hco 3 co 3 2 and mainly h 4 sio 4 h 3 sio 4 act as homogeneous ph buffers and contribute to the total alkalinity in these alkaline waters on the basis of the study of the conservative elements a mixing process between a hot and a cold end member has been identified additionally in order to determinate the water temperature at the reservoir several geothermometric techniques have been applied including both geothermometrical modeling and classical geothermometrical calculations the geothermometrical modeling seems to indicate that thermal waters re equilibrate with respect to calcite and kaolinite during their ascent to the surface modeling results suggest that these thermal waters would be in equilibrium with respect to albite k feldspar quartz calcite kaolinite and zoisite at a similar temperature of 90 20 c in the reservoir which is in good agreement with the results obtained by applying the classical geothermometers

the deep layers of a paleozoic arc geochemistry of the copley balaklala series northern california abstract ree zr nb concentrations and sr nd isotope compositions have been measured in copley basalts and andesites balaklala rhyolites and mule mountain trondhjemites northern california which represent the deep layers of a well preserved intra oceanic island arc of siluro devonian age 87sr 86sr is shifted towards high values up to 0 707 whereas ce is preferentially removed from rhyolites a large proportion of the analyzed samples including some acidic rocks shows a pronounced depletion in light ree the end t values of most copley balaklala and mule mountain rocks fall in the range 6 to 8 which suggests that they originated from a normal morb type source end t 9 contaminated with either sediments or an oib type component in modern island arcs only the shallow levels are accessible comparison with the copley balaklala mule mountain series suggests that at depth an immature island arc is likely to comprise thick layers of lile depleted tholeiites and rhyolites intensely altered by pervasive circulation of seawater least square solutions of trace element models suggest that rhyolites and trondhjemites represent remelting of mafic volcanics from the arc basement rather than residual melts of basalt andesite differentiation

secondary processes determining the ph of alkaline waters in crystalline rock systems abstract the understanding of the main hydrogeochemical processes controlling the features and behaviour of crystalline rock environments considered for the deep geological storage of spent nuclear fuel is a key issue for the improvement of our knowledge and management of these systems and for a more accurate prediction of their future evolution in this paper some of the most important irreversible processes cooling mixing and co 2 exchange are studied and their effects quantified by combining classical geochemical calculations and geochemical modelling this methodology is applied to an alkaline thermal water system developed in crystalline rocks the caldas de boi groundwater system ne spain analogous to the deep geological environments expected for nuclear waste storage one of the most remarkable results obtained in this study is related to the high ph buffering capacity exhibited by these alkaline thermal waters during the mixing processes with colder and shallower waters taking place during the uprising of the hot waters from the deep reservoir even for high mixing proportions of cold water up to 60 the final ph remains as alkaline as in the thermal and deep end member although the rest of the physicochemical parameters including temperature change consistently with mixing another important secondary ph determining process detected in this study is the conductive cooling of the thermal waters suffered during their rise to surface conditions which is clearly responsible for a ph increase which enhances the typical alkaline character of these waters finally the existence of external inputs of edaphic or biogenic co 2 to the groundwater system producing a ph decrease in some of the springs has been proven to play a key role in their behaviour and evolution

hydrogeochemical and isotopic characteristics of the ilica geothermal system erzurum turkey in this paper the hydrochemical isotopic characteristics of samples collected from geothermal springs in the ilica geothermal field eastern anatolia of turkey are examined and described low temperature geothermal system of ilica erzurum turkey located along the eastern anatolian fault zone was investigated for hydrogeochemical and isotopic characteristics the study of ionic and isotopic contents shows that the thermal water of ilica is mainly locally fed by groundwater which changes chemically and isotopically during its circulation within the major fault zone reaching depths the thermal spring has a temperature of 29 39 c with electrical conductivity ranging from 4 000 to 7 510 s cm and the thermal water is of na hco3 cl water type the chemical geothermometers applied in the ilica geothermal waters yielded a maximum reservoir temperature of 142 c according to the silica geothermometers the thermal waters are undersaturated with respect to gypsum anhydrite and halite and oversaturated with respect to dolomite the dolomite mineral possibly caused scaling when obtaining the thermal waters in the study area according to the enthalpy chloride mixing model cold water to the thermal water mixing ratio is changing between 69 8 and 75 the 18o 2h compositions obviously indicate meteoric origin of the waters thermal water springs derived from continental precipitation falling on to higher elevations in the study area the 13c ratio for dissolved inorganic carbonate in the waters lies between 4 63 and 6 48 in low temperature waters carbon is considered as originating from volcanic mantle co2

geothermometry and circulation depth of groundwater in semnan thermal springs northern iran semnan thermal springs with high tds and moderate temperature are located northwest of semnan the northern part of iran the spatial and temporal variations of physicochemical characteristics of the thermal and cold springs were investigated for the recognition of origin and dominant hydrogeochemical processes results show that the thermal springs have the same origin but due to different ascending flow paths and different conductive cooling mechanism their temperatures vary the chemical composition of thermal waters is controlled by dolomite halite and sulfate minerals dissolution and calcite precipitation and bacterial sulfate reduction the concentration of major and trace elements in the thermal springs does not change in wet and dry seasons notably because they are derived from old groundwater with deep circulation and high temperature seasonal change in the concentration of some trace elements is due to the seasonal variation of ph eh temperature and dilution by shallow waters decreasing so4 and carbonate saturation index and increasing na cl ratios and ca content in the dry season show dilution effect caused by the previous heavy rainfall events the temperature of the heating reservoir based on k mg chalcedony quartz and chemical equilibrium approach was approximately estimated in the range of 60 80 c hydrogeologically a conceptual model was suggested for the thermal springs the general groundwater flow direction is probably from the dolomite lar formation in chenaran anticline toward the adjacent syncline in a confined condition and then a thrust fault acts as a conduit and redirects the thermal water to the emerging springs at the surface

origin of vertical shafts in bedrock along the eramosa river valley near guelph southern ontario numerous vertical to subvertical cylindrical shafts occur in the rugged exposures of the middle silurian amabel formation bedrock along the eramosa river approximately 10 km northeast of guelph these shafts vary from 1 m to 10 m in diameter with depths as great as 12 m they can occur as isolated depressions but more commonly are clustered closely together and many coalesce to form sinuous bedrock walls these depressions may contain soil fine sediment rubble from the surrounding dolomite bedrock and rounded clasts of precambrian basement lithologies till is conspicuously absent these shafts occur in close proximity to cavernous pores that were formed during pre wisconsinan to early wisconsinan time suggesting a possible karstic origin the cylindrical shafts however with their greater midpoint diameters sculpted interiors and inclined axes and their lack of vertical flutes and till are more likely to have originated from glaciofluvial discharge at the end of the late wisconsinan the d

origin and evolution of two contrasting thermal groundwaters co2 rich and alkaline in the jungwon area south korea hydrochemical and isotopic evidence in the jungwon area south korea two contrasting types of deep thermal groundwater around 20 33 c occur together in granite compared to shallow groundwater and surface water thermal groundwaters have significantly lower 18o and d values 1 lower in 18o and negligible tritium content mostly 2 tu suggesting a relatively high age of these waters at least pre thermonuclear period and relatively long subsurface circulation however the hydrochemical evolution yielded two distinct water types co2 rich water pco2 0 1 to 2 atm is characterized by lower ph 5 7 6 4 and higher tds content up to 3300 mg l whereas alkaline water pco2 10 4 1 10 4 6 atm has higher ph 9 1 9 5 and lower tds 254 mg l carbon isotope data indicate that the co2 rich water is influenced by a local supply of deep co2 potentially magmatic which enhanced dissolution of silicate minerals in surrounding rocks and resulted in elevated concentrations of ca2 na mg2 k hco3 and silica under lower ph conditions in contrast the evolution of the alkaline water was characterized by a lesser degree of water rock granite interaction under the negligible inflow of co2 the application of chemical thermometers indicates that the alkaline water represents partially equilibrated waters coming from a geothermal reservoir with a temperature of about 40 c while the immature characteristics of the co2 rich water resulted from the input of co2 in na hco3 waters and subsequent rock leaching

mixing hydrology and chemical equilibria in bakreswar geothermal area eastern india abstract a group of alkaline thermal springs of bakreswar having varying temperatures 45 71 c and identical compositions emerges through a nearly n s trending fault in the gneissic basement the thermal springs are of na cl so 4 type and are rich in sio 2 and f contrary to the local groundwaters which are mostly of ca hco 3 type the springs undergo mild to moderate dilution by local groundwater which does not significantly affect their original compositions agnikund the main spring with the highest temperature mild dilution consistent composition and negligible tritium discharges almost pure deep seated thermal water original thermal water is at equilibrium with quartz in the deep reservoir and attains surface temperature largely by conductive cooling with no significant loss of dissolved sio 2 certain ionic ratios coupled with very low tritium contents in the springs are indicative of prolonged subsurface circulation of the original water xrd results of the spring site sediments and the bore hole rocks fairly corroborate the predicted saturation state of thermal water with respect to quartz feldspar calcite fluorite etc which is believed to control the major chemical compositions of the springs a geothermal reservoir having probable temperature of about 100 5 c and possibly occurring at a depth of 1 km is the source of thermal water for the springs the present study is aimed at understanding the mixing trend between thermal springs and local groundwaters as well as the water rock equilibria

mineralogy textures and relative age relationships of massive sulfide ore in the west shasta district california the devonian massive sulfide orebodies of the west shasta district in northern california are composed primarily of pyrite with lesser amounts of other sulfide and gangue minerals examination of polished thin sections of more than 100 samples from the mammoth shasta king early bird balaklala keystone and iron mountain mines suggests that mineralization may be divided into six paragenetic stages the last five each separated by an episode of deformation 1 precipitation of fine grained locally colloform and framboidal pyrite and sphalerite 2 deposition of fine grained arsenopyrite and coarse grained pyrite the latter enclosing tiny inclusions of pyrrhotite 3 penetration and local replacement of sulfide minerals of stages 1 and 2 along growth zones and fractures by chalcopyrite sphalerite galena ten nantite pyrrhotite bornite and idaite 4 recrystallization and remobilization of existing minerals locally increasing their size and euhedralism and promoting their aggregation 5 deposition of quartz white mica chlorite and calcite and 6 formation of bornite digenite chalcocite and covellite during supergene enrichment of several orebodies at the iron mountain mine despite regional greenschist facies metamorphism and local heating by intrusive bodies enough of the original depositional features of the ore remain to suggest that the deposits in the district formed by processes similar to those that formed kuroko and besshi type massive sulfide deposits mineralogic and textural evidence do not support a second major episode of massive sulfide mineralization during the permian

paleomagnetic study of the eastern klamath terrane california and implications for the tectonic history of the klamath mountains province paleomagnetic study of permian through jurassic volcanic and sedimentary strata of the eastern klamath terrane has shown the remanent magnetization of many of these rocks to be prefolding and most likely primary similarities in magnetic declinations recorded by coeval strata over a broad area are consistent with the hypothesis that the terrane in general has behaved as a single rigid block paleomagnetic data indicate that the volcanic island arc represented by this terrane the nucleus of the province was facing toward the present southwest during late paleozoic time although its orientation during earlier periods is unknown whether the arc was separated from the north american craton by a small marginal basin or originated far offshore cannot be determined from paleomagnetic data the declination anomalies for both permian and triassic strata are similar average 106 12 so we infer that clockwise rotation of the late paleozoic arc did not begin until latest triassic or earliest jurassic time the arc may have completed its initial rotation with respect to stable north america by middle jurassic time after some retrograde motion the arc was again facing west by the late jurassic by which time some of the more westerly terranes of the province had become attached to the eastern klamath terrane the composite klamath mountains terranes continued to rotate until the final 60 of clockwise rotation was nearly complete by the early cretaceous coincidence of the waning stages of rotation at about 136 ma with the beginning of deposition of the basal great valley sequence onto the klamath basement probably represents the completion of accretion of the klamath mountains terranes to the north american continent nearly all the rotation occurred while the klamath mountains terranes were part of a converging oceanic plate with only about 20 of rotation in mid tertiary time during basin and range extension no data currently available show evidence for any significant latitudinal displacement of any klamath mountains terranes relative to cratonic north america

les eaux thermales des granites de galice espagne des eaux carbogazeuses aux eaux alcalines thermal waters from granites of galicia spain from co2 rich to high ph waters abstract thermal waters from galicia spain range from co 2 rich low ph to high ph sulfide rich waters going through intermediate waters in order to explain the variations of their chemical composition we present a discussion of the major factors governing the water composition we eiscuss especially the isochemical recrystallization of a granite it is shown that the equilibrium mineral association of the water alkali granite system is unique for chalco alkaline granites two different associations are possible depending on the chemical composition of the granite the effect of an addition of co 2 is also discussed some criteria allowing a distinction between fully equilibrated and non equilibrated waters are presented finally the composition of galician waters is explained by different initial co 2 contents and by different values of the degree of the granite water reaction progress

diversity of magma types in a lower paleozoic island arc marginal basin system eastern klamath mountains california u s a abstract a trace element investigation has been conducted on ordovician to devonian volcanics of the eastern klamath mountains spatially associated to the siluro ordovician trinity peridotite and gabbros all the studied volcanics low k tholeiites and calc alkaline volcanics present strong island arc geochemical features low tio 2 contents negative nb zr and ti anomalies mild lree enrichment and depletion some volcanics from lovers leap and copley exhibit strong immature island arc geochemical affinities very depleted lree patterns and very low nb contents suggesting that they were formed by high degrees of partial melting 20 of a residual lithosphere diminution of the partial melting degree and addition of sediments to the source will explain the occurrence of less depleted or slightly lree enriched volcanics the grey rocks basaltic pillow lavas thrust onto the trinity peridotitic sheet probably represent the extrusive member of the ophiolitic sequence their strong island arc geochemical affinities suggest that the ophiolite was formed during the first stages of a back arc basin development differentiation took place in the arc by melting of the deeper basaltic layers leading to the formation of abundant rhyolitic and trondhjemitic magmatism representing the first stages of continental accretion

erosion of bedrock by subglacial meltwater cantley quebec several erosional forms on bedrock at cantley quebec differ from well known glacial abrasion forms the forms consist of obstacle marks hollows depressions and channels which are defined by sharp rims smooth inner surfaces divergent flow features and remnant ridges these forms are found on lee lateral and overhung rock surfaces this assemblage of features is best explained by differential erosion produced by separation eddies along lines of reattachment rapid sediment laden turbulent subglacial melt water flows likely produced the forms by corrasion and cavitation erosion sculpted fluvial forms in terrain subject to flooding in australia are identical to some of the cantley forms which confirms their formation by water erosion although glacial abrasion may not be eliminated as an explanation for sculpted forms it is not necessary ice abrasion forms such as striations and such plucked forms as gouges and crescentic fractures are also present at the cantley site pitted forms polishing and carbonate precipitate are also found the occurrence of abrasion pitting polishing and carbonate precipitate with meltwater forms suggests that the meltwater flows were subglacial decoupling of abrading ice from its bed temporarily suspended glacial abrasion whereas reattachment of ice to the bed may have led to the rounding of sharp edges and the production of striations superposed on the glacifluvial forms the association of forms produced both by glacifluvial erosion and ice abrasion suggests that the glacier was alternately lifted from and reattached to the bed during periodic subglacial floods these floods may have affected the dynamics of the ice sheet and depositional sequences related to catastrophic meltwater outbursts probably were laid down in adjacent basins

river incision into bedrock mechanics and relative efficacy of plucking abrasion and cavitation improved formulation of bedrock erosion laws requires knowledge of the actual processes operative at the bed we present qualitative field evidence from a wide range of settings that the relative efficacy of the various processes of fluvial erosion e g plucking abrasion cavitation solution is a strong function of substrate lithology and that joint spacing fractures and bedding planes exert the most direct control the relative importance of the various processes and the nature of the interplay between them are inferred from detailed observations of the morphology of erosional forms on channel bed and banks and their spatial distributions we find that plucking dominates wherever rocks are well jointed on a submeter scale hydraulic wedging of small clasts into cracks bashing and abrasion by bedload and chemical and physical weathering all contribute to the loosening and removal of joint blocks in more massive rocks abrasion by suspended sand appears to be rate limiting in the systems studied here concentration of erosion on downstream sides of obstacles and tight coupling between fluid flow patterns and fine scale morphology of erosion forms testify to the importance of abrasion by suspended load rather than bedload particles mechanical analyses indicate that erosion by suspended load abrasion is considerably more nonlinear in shear stress than erosion by plucking in addition a new analysis indicates that cavitation is more likely to occur in natural systems than previously argued cavitation must be considered a viable process in many actively incising bedrock channels and may contribute to the fluting and potholing of massive unjointed rocks that is otherwise attributed to suspended load abrasion direct field evidence of cavitation erosion is however lacking in terms of the well known shear stress or stream power erosion law erosion by plucking is consistent with a slope exponent n of 2 3 to 1 whereas erosion by suspended load abrasion is more consistent with a slope exponent of 5 3 given that substrate lithology appears to dictate the dominant erosion process this finding has important implications for long term landscape evolution and the models used to study it

fluvially sculpted rock bedforms in twenty mile creek niagara peninsula ontario sculpted rock bedforms s forms on whirlpool sandstone are described from the bed of twenty mile creek the morphologies identified undulating surfaces rises furrows comma forms spindles potholes and transverse troughs are those described for sculpted bedrock forms p forms s forms developed in subglacial environments additional morphologies identified are undercut downsteps and quarried surfaces in the lee of bedrock rises morphological differences between the subglacial and fluvial forms are attributed to the difference between confined conduit flow in the subglacial case and open channel flow in the fluvial examples in fluvial systems the descending bedrock surface presents rock differently to oncoming flows and favours certain s forms quarried lee faces and undulating surfaces in a strong flow fluvial environment s forms develop by wear dominant sediment transport modes are large clasts up to metre dimensions and suspended silt clay with a small 7 hard or heavy mineral compone

regional reconstruction of subglacial hydrology and glaciodynamic behaviour along the southern margin of the cordilleran ice sheet in british columbia canada and northern washington state usa abstract subglacial landsystems in and around okanagan valley british columbia canada are investigated in order to evaluate landscape development subglacial hydrology and cordilleran ice sheet dynamics along its southern margin major landscape elements include drumlin swarms and tunnel valleys drumlins are composed of bedrock diamicton and glaciofluvial sediments their form truncates the substrate tunnel valleys of various scales km to 100s km length incised into bedrock and sediment exhibit convex longitudinal profiles and truncate drumlin swarms okanagan valley is the largest tunnel valley in the area and is eroded 300 m below sea level over 600 m of late wisconsin age sediments consisting of a fining up sequence of cobble gravel sand and silt fill okanagan valley landform substrate relationships landform associations and sedimentary sequences are incompatible with prevailing explanations of landsystem development centred mainly on deforming beds they are best explained by meltwater erosion and deposition during ice sheet underbursts during the late wisconsin glaciation okanagan valley functioned as part of a subglacial lake spanning multiple connected valleys few 100s km of southern british columbia subglacial lake development started either as glaciers advanced over a pre existing sub aerial lake catch lake or by incremental production and storage of basal meltwater high geothermal heat flux geothermal springs and or subglacial volcanic eruptions contributed to ice melt and may have triggered along with priming from supraglacial lakes subglacial lake drainage during the underburst s sheetflows eroded drumlins in corridors and channelized flows eroded tunnel valleys progressive flow channelization focused flows toward major bedrock valleys in okanagan valley most of the pre glacial and early glacial sediment fill was removed a fining up sequence of boulder gravel and sand was deposited during waning stages of the underburst s and bedrock drumlins in okanagan valley were enhanced or wholly formed by this underburst s subglacial lake development and drainage had an impact on ice sheet geometry and ice volumes the prevailing conceptual model for growth and decay of the cis suggests significantly thicker ice in valleys compared to plateaus subglacial lake development created a reversal of this ice sheet geometry where grounded ice on plateaus thickened while floating valley ice remained thinner due to melting and enhanced sliding with significant transfer of ice toward the ice sheet margin subglacial lake drainage may have hastened deglaciation by melting ice lowering ice surface elevations and causing lid fracture this paper highlights the importance of ice sheet hydrology its control on ice flow dynamics distribution and volume in continental ice masses

thin film channelized drainage or sheetfloods beneath a portion of the laurentide ice sheet an examination of glacial erosion forms northern new york state usa abstract morphologic analyses of characteristic bedrock erosion forms found in northern new york state usa were used to reconstruct the subglacial conditions under which they may have been produced observations from sites on wellesley island n y at point salubrious n y and at an open pit mine near balmat n y were combined with regional mapping of a diverse suite of glacial erosion forms in order to establish the areal extent and significance of subglacial drainage in northern new york results of these site specific and regional studies are the basis for discussion of the probable role of subglacial meltwater in the region bedrock erosion forms preserved at various locations in northern new york are interpreted as products of flow separation of localized subglacial meltwater during ice bed decoupling the regional distribution of these forms indicates that they are largely restricted to pre existing subglacially modified bedrock valleys that served as subglacial tunnel channels regionally extensive deep subglacial meltwater flow characterized as sheetfloods is not required to account for the erosional features described from specific sites in northern new york state

rare earth elements geochemistry in springs from taftan geothermal area se iran abstract concentrations of rare earth elements rees were determined in springs and andesitic dacitic rocks of taftan geothermal field hydrochemical results of major ions indicate that thermal springs are na so 4 cl and ca so 4 cl types concentrations of rees are in ranges of 10 4 to 1 2 and 49 to 62 times of chondrite for springwater and rock samples respectively the thermal sts and tts and the cold aps springs with low ph values exhibit a very high ree contents 0 64 to 3 15 mg l saturation index indicates that fe and al phases can control dissolved ree concentration in fts and pf cold springs the speciation of ree complexes indicates dominant presence of lnso 4 and free ion in the taftan thermal springs in aps cold spring with ph 4 fluoride complexes are dominate over the free ion and sulfate species while in pf and fts cold springs with ph 6 4 and 7 respectively carbonate complexes lnco 3 are predominant species chondrite normalized pattern for the low ph waters show very distinctive gull wing patterns characteristic feature of acid sulfate geothermal systems and are similar to those of the host rocks chemical characteristics of rare earth elements in spring and volcanic rock samples indicate that rees are originated from the andesitic dacitic host rocks whole rock normalized ree patterns and petrographic evidences show that rare earth elements leached mainly from marginal alteration of minerals and matrix decomposition in volcanic rocks in chondrite normalized ree patterns significant negative eu anomaly in the cold springs compare to the thermal and acidic springs indicates that alteration of plagioclase is more intense in the later corresponding to increasing in temperature and acidic state of reactant water

a deep geothermal exploration well at eastgate weardale uk a novel exploration concept for low enthalpy resources the first deep geothermal exploration borehole 995 m to be drilled in the uk for over 20 years was completed at eastgate weardale co durham in december 2004 it penetrated 4 m of sandy till quaternary 267 5 m of lower carboniferous strata including the whin sill and 723 5 m of the weardale granite devonian with vein mineralization occurring to 913 m unlike previous geothermal investigations of uk radiothermal granites that focused on the hot dry rock concept the eastgate borehole was designed to intercept deep fracture hosted brines associated with the major geologically ancient hydrothermal vein systems abundant brine 46 c was encountered within natural fracture networks of very high permeability transmissivity c 2000 darcy m within granite evidence for the thermal history of the carboniferous rocks from phytoclast reflectance measurements shows very high values 3 3 indicating maximum temperatures of 130 c prior to intrusion of the whin sill geochemical analysis of cuttings samples from the eastgate borehole suggests radiothermal heat production rates for unaltered weardale granite averaging 4 1 w m 3 with a mean geothermal gradient of 38 c km 1 the eastgate borehole has significant exploitation potential for direct heat uses it demonstrates the potential for seeking hydrothermal vein systems within radiothermal granites as targets for geothermal resources

hydrogeochemistry of sodium bicarbonate type bedrock groundwater in the pocheon spa area south korea water rock interaction and hydrologic mixing the pocheon spa land area south korea occurs in a topographically steep fault bounded basin and is characterized by a hydraulic upwelling flow zone of thermal water up to 44 c in its central part hydrogeochemical and environmental isotope data for groundwater in the study area suggested the occurrence of two distinct water types a ca hco3 type and a na hco3 type the former water type is characterized by relatively high concentrations of ca so4 and no3 which show significant temporal variation indicating a strong influence by surface processes in contrast the na hco3 type waters have high and temporally constant temperature ph tds na cl hco3 and f indicating the attainment of a chemical steady state with respect to the host rocks granite and gneiss oxygen hydrogen and tritium isotope data also indicate the differences in hydrologic conditions between the two groups the relatively lower 18o d and tritium values for na hco3 type waters suggest that they recharged at higher elevations and have comparatively long mean residence times considering the geologic and hydrogeologic conditions of the study area na hco3 type waters possibly have evolved from ca hco3 type waters mass balance modeling revealed that the chemistry of na hco3 type water was regulated by dissolution of silicates and carbonates and concurrent ion exchange particularly low ca concentrations in na hco3 water was mainly caused by cation exchange multivariate mixing and mass balance modeling m3 modeling was performed to evaluate the hydrologic mixing and mass transfer between discrete water masses occurring in the shallow peripheral part of the central spa land area where hydraulic upwelling occurs based on q mode factor analysis and mixing modeling using phreeqc an ideal mixing among three major water masses surface water shallow groundwater of ca hco3 type deep groundwater of na hco3 type was proposed m3 modeling suggests that all the groundwaters in the spa area can be described as mixtures of these end members after mixing the net mole transfer by geochemical reaction was less than that without mixing therefore it is likely that in the hydraulic mixing zone geochemical reactions are of minor importance and therefore that mixing regulates the groundwater geochemistry

bedrock mega grooves in glaciated terrain a review abstract bedrock mega grooves are assemblages of straight and parallel troughs eroded in bedrock typically over 1000 m in length most sites occur within the limits of the last glacial maximum both on and off shore in this paper we review the current understanding of these important yet enigmatic landforms and propose a framework for their future research mega grooves are important to our understanding of ice sheet dynamics ice bedrock interactions and bedrock landscape evolution in glaciated areas the overall straightness of mega grooves across the landscape their parallel alignment to palaeo ice flow direction and occurrence below the general land surface level has led to their unanimous interpretation as landforms of subglacial erosion scenarios proposed for mega groove formation focus on either glacier ice or subglacial meltwater as the principal agent of erosion yet none offers a comprehensive explanation at locations where mega grooves occur along lines of structural geology their location formation and morphology were largely controlled by the bedrock characteristics where no underlying structural control is apparent mega grooves were likely initiated through glacial abrasion and subsequently modified through a range of erosional processes potentially involving multiple morphogenetic agencies and feedbacks operating between bedrock topography and basal ice flow in the absence of absolute dates morphostratigraphic analyses suggest mega groove survival through multiple glacial cycles no specific ice flow characteristics have been identified as a condition for bedrock grooving but it has been suggested that some bedrock mega grooves are related to ice streaming which deserves further study an initial analysis of bedrock grooves with seemingly similar morphology at a range of scales hints at a bedrock groove landform size continuum which could be a useful framework for exploring process landform relationships future research could usefully focus on quantitative analysis of mega groove morphology augmented with detailed field analysis of landform relationships to bedrock structure and lithology and thereby potentially provide further insight into the age and glaciological significance of these landforms

the influence of bedrock geology on knickpoint development and channel bed degradation along downcutting streams in south central indiana geologic controls on knickpoint development and the mechanics of channel bed degradation were eluci dated by comparison of downcutting streams in south central indiana developed in lithologically homoge neous carbonate units and layered siliciclastic strata knickpoints formed in a single lithologic unit are stepped each step consists of a knickpoint face and tread the height of each step is equal to and controlled by bed thickness spatially knickpoints in homogeneous terrain are limited to jointed strata that dip 1 upstream or 2 downstream at angles less than the channel gradient knickpoints observed in lithologically layered strata are characterized by a single step in which resistant jointed rocks overlie and protect weaker units total knickpoint relief is influenced by thickness of the weaker strata knickpoints in layered siliciclastic strata are spatially limited to bedrock reaches produced by differential rates of channel incision knickpoint distribution is also influenced by joint

thresholds of erosion and sediment movement in bedrock channels abstract this study examines the erosive resistance of the discontinuous loose joint blocks of various sizes that comprise the bed material of the etobicoke creek an incised bedrock channel found in an urbanized setting within the city of toronto ontario canada in order to accomplish this both field and laboratory experiments were conducted on the bed material found in this channel the field work involved repeated detailed surveying of the channel bed and estimations of distances of movement of various clasts during many sediment transport events we found that rates of erosion and or deposition can be significant during the snowmelt spring events and that there was a greater loss of bed material over the study reach than was gained in several spots with bed lowering 0 10 m in some locations the field work also showed that the distances moved by the rock clasts scaled directly with shear stresses observed during rain events and that average distances of transport tend to be short the frequency distributions of distance of transport scaled with particle size is log normally distributed flume experiments demonstrated that the clasts offered different levels of resistance to movement depending on their orientation the platy nature of the rock fragments clast orientation and their imbrication significantly affect the threshold of erosion the results have significant implications for the understanding of bedrock rivers from a management perspective especially in the case of those rivers experiencing the effects of urban development in their drainage basins

hydrogeological properties of a complex dinaric karst catchment miljacka spring case study miljacka is a karst spring situated in dalmatia croatia the interpretation of the miljacka spring catchment area boundary has repeatedly changed in the past and the main conclusions of previous studies were that the spring which is located in the krka river canyon receives all of its water from another karst river zrmanja here we review a new hypothesis that the miljacka spring receives some of its water from the krka river it was not possible to verify the hypothesis by solely studying the geological composition structural tectonic relations and tracer test results therefore a hydrochemical study was performed to confirm the hypothesis by studying the geological composition it was found that part of the catchment area of the krka river is built of evaporites gypsum and anhydrite which are different in their mineral composition than carbonates the usual rock mass of the dinaric karst the hydrochemical model was made using the netpath win and phreeqc software packages the mixing model results confirmed the hypothesis that the miljacka spring waters come from both the zrmanja including smaller proportion of precipitation infiltrated directly in the karst aquifer and krka rivers this case study shows the great importance of the application of hydrochemical investigations in karst hydrogeology where research is often difficult due to the complexity of the groundwater system

the chemistry of geothermal waters in iceland iii chemical geothermometry in geothermal investigations abstract new data from geothermal wells in iceland have permitted empirical calibration of the chalcedony and na k geothermometers in the range of 25 180 c and 25 250 c respectively the temperature functions are t c 1112 4 91 log sio 2 273 15 t c 933 0 993 log na k 273 15 concentrations are expressed in ppm these temperature functions correspond well with the chalcedony solubility data of fournier 1973 and the thermodynamic data for low albite microcline solution equilibria of heloeson 1969 a new co2 geothermometer is proposed which is considered to be useful in estimating underground temperatures in fumarolic geothermal fields its application involves analysis of co2 concentrations in the fumarole steam the temperature function which applies in the range 180 300 c is logco2 37 43 73192 t 11829 103 t2 0 18923t 86 187 logt where t is in k and co2 in moles per kg of steam

submerged and unsubmerged natural hydraulic jumps in a bedrock step pool mountain channel high resolution digital elevation models dems for natural submerged and unsubmerged jump regions were tested against the classical hydraulic jump chj and engineering analogues that have dominated previous geomorphic and engineering research dems were compared for two discharge conditions the data showed bed and water surface features of the natural jump regions differ significantly from chj conditions and engineering analogues with respect to boundary conditions roughness elements were highly irregular in frequency spacing size and orientation and were comprised of form obliquity and bed scour in boulder bed and pure bedrock conditions the data also showed bed and water surface features of natural jump regions have similarities and deviations from chj conditions and engineering analogues with respect to hydraulic characteristics several variations were observed in the hydraulic characteristics between the ballistic and sloping jets revised conceptual models based on idealized corollaries were developed for the natural jump regions based on upstream energy head relative to the downstream tailwater depth and step geometry the dems highlight the importance of recognizing the interrelationship between spatial transcritical flow structures and localized topographic heterogeneities in bedrock channels

island arc sedimentation in the middle devonian kennett formation eastern klamath mountains california the kennett formation is a unit of intra arc sediments which was deposited during the final stages of early to middle devonian island arc construction in the eastern klamath mountains california nearshore bioturbated volcaniclastics with a shallow marine fauna also contain rare debris of land plants indicating island source areas these sediments grade to volcaniclastic turbidites of slope origin which in turn grade to thin bedded siliceous mudstone representing a basin floor environment limestone lenses at the top of the kennett are debris deposits with matrix supported intraclasts and overturned colonial skeletons which were derived from shallow carbonate banks sedimentary facies of the kennett indicate a mature arc topography of islands submerged highs and intra arc basins basins were probably developed by tectonic extension of the arc during the early devonian

evaluation of groundwater hydrochemical characteristics and mixing behavior in the daying and qicun geothermal systems xinzhou basin this paper examines groundwater hydrochemical characteristics during mixing between thermal and non thermal groundwater in low to medium temperature geothermal fields a case study is made of daying and qicun geothermal fields in the xinzhou basin of shanxi province china the two geothermal fields have similar flow patterns with recharge sourced from precipitation in mountain areas heated through a deep cycle before flowing into overlying quaternary porous aquifers via fractures hydrochemical features of 60 ground and surface water samples were examined in the context of hydrogeologic information the average temperatures of the deep geothermal reservoirs are estimated to be 125 degrees c in daying field and 159 degrees c in qicun field based on na k mg geothermometry while slightly lower estimates are obtained using silica geothermometers hydrochemical features of thermal water are distinct from cold water thermal groundwater is mainly cl center dot so 4 na type with high tds while non thermal groundwater is mostly hcl 3 ca center dot mg and hco 3 ca type in the daying and qicun regions respectively hydrogeochemical processes are characterized by analyzing ion ratios in various waters higher contents of some minor elements in thermal waters such as f si b and sr are probably derived from extended water rock interaction and these elements can be regarded as indicators of flow paths and residence times mixing ratios between cold and thermal waters were estimated with cl na and b concentrations using a mass balance approach mixing between ascending thermal waters and overlying cold waters is extensive the proportion of water in the quaternary aquifer derived from a deep thermal source is lower in daying geothermal field than in qicun field 5 3 7 3 vs 6 3 49 3 mixing between thermal and non thermal groundwater has been accelerated by groundwater exploitation practices and is enhanced near faults shallow groundwater composition has also been affected by irrigation with low temperature thermal water c 2009 elsevier b v all rights reserved

field mapping and digital elevation modelling of submerged and unsubmerged hydraulic jump regions in a bedrock step pool channel high resolution tacheometric field surveying was integrated with computer assisted drafting to visualize and contrast three dimensional bed and water surface digital elevation models dems for submerged and unsubmerged hydraulic jump regions in a bedrock step pool channel measurements were conducted for two discharge conditions since previous applica tions of three dimensional field mapping and digital elevation modelling of stream channels have been limited to smoothly contiguous gravel bedded systems surveying was optimized by topographic setting and scaled to localized bed and water surface discontinuities traces and visualizations of the jump regions indicated that dichotomous decimetre shifts in water surface topography occurred for both jump regions from lower to higher discharges systematic removal of the survey points and dem differencing indicated that point densities of ten points per square metre in conjunction with a survey structure targeting grade breaks of 0 3 0 5 m were required to capture decimetre form variations of the natural jump regions the dems highlight the importance of recognizing the relationship between transcritical flow structures and localized topographic heterogeneities in bedrock channels copyright 2006 john wiley sons ltd

concordant paleolatitudes for neoproterozoic ophiolitic rocks of the trinity complex klamath mountains california 1 new paleomagnetic results from the eastern klamath mountains of northern california show that neoproterozoic rocks of the trinity ophiolitic complex and overlying middle devonian volcanic rocks are latitudinally concordant with cratonal north america combining paleomagnetic data with regional geologic and faunal evidence suggests that the trinity complex and related terranes of the eastern klamath plate were linked in some fashion to the north american craton throughout that time but that distance between them may have varied considerably a possible model that is consistent with our paleomagnetic results and the geologic evidence is that the trinity complex formed and migrated parallel to paleolatitude in the basin between laurasia and australia east antarctica as the rodinian supercontinent began to break up it then continued to move parallel to paleolatitude at least through middle devonian time although the eastern klamath plate served as a nucleus against which more western components of the klamath mountains province amalgamated the klamath superterrane was not accreted to north america until early cretaceous time index terms 1525 geomagnetism and paleomagnetism paleomagnetism applied to tectonics regional global 5475 planetology solid surface planets tectonics 8149 8157 tectonophysics evolution of the earth plate motions past 3040 9350 information related to geographic region north america 9619 information related to geologic time precambrian

bedrock benches and boulder bars floods in the burdekin gorge of australia the burdekin gorge of northeastern australia lies within the seasonal tropics and is characterized by high discharge variability slackwater sediments and paleostage indicators in the gorge record seven large floods that have occurred during the past 1 200 yrs these floods range in magnitude from 11 000 to 30 000 m 3 s 1 and are characterized by large downstream variations in hydraulics the floods generate high values of velocity boundary shear stress and stream power per unit area downstream fluctuations in these variables help to explain the location of boulder bars high flood levees small scale erosional features in the bedrock and the formation of inner channels boulder bars and flood levees form where shear stress and stream power decrease due to channel widening small scale erosional features such as potholes and troughs are best developed at sites of channel constriction and associated increases in shear stress and stream power the development of the inner channel appears to be controlled by complex interactions between bedrock lithology and structure and by flow hydraulics all of the channel features are related to the hydraulics of large floods which therefore are the dominant controls on many aspects of channel morphology in this bedrock gorge

erosion of bedrock by subglacial meltwater georgian bay ontario a regional view a spectacular series of sculpted erosional forms s forms is mapped and described from a 70 km wide area along the shore of georgian bay ontario which except for a scattered boulder lag has been swept clean of sediment a great variety of sculpted forms is described and illustrated and grouped into three classes transverse longitudinal and nondirectional forms transverse forms comprise transverse troughs muschelbruche sichelwannen and comma forms longitudinal forms comprise spindle flutes cavettos and furrows and nondirectional forms consist of undulating surfaces and potholes transverse forms are preferentially located on stoss slopes and longitudinal forms on lee slopes of rock rises undulating nondirectional forms are found on distal slopes and potholes at major breaks in slope this correlation of form and bed topography suggests that relief exerts considerable control on both form and location form geometry is also inferred to be related to coherent flow structures and their int

geochemical study of the sakalol harralol geothermal field republic of djibouti evidences of a low enthalpy aquifer between manda inakir and asal rift settings abstract eighty six sodium bicarbonate to sodium chloride hot springs and four water wells in the tadjourah region of djibouti were investigated for major minor b br f sr li chemistry and isotope composition of water and dissolved components 87sr 86sr 11b 10b 13c 12c and 14c of dic 34s 32s and 18o 16o of sulfate the deep saline na cl reservoir at 143 c shows affinity with the shallow geothermal water from the active asal rift asal water is a diluted and recycled seawater component with the major cation composition obliterated by equilibration with stratoid basalt locally the deep reservoir is differentiated in term of recharge and re equilibration with rocks and mixing in particular two spring groups reveal contributions from evaporites typical of the passive graben setting of the afar a model on 34s 32s and 18o 16o demonstrates the isotope imprint of magmatic so2 disproportionation on dissolved and solid sulfate whose values probably persists in a sedimentary environment without trace of seawater on the other hand a seawater signature modified by mixing and secondary fractionation effects is partially maintained according to the boron isotope composition up to 27 4 temperature estimation in low enthalpy geothermal reservoirs is notoriously difficult especially where mixing with fluids of differing genesis and or conduction cooling take place from a geothermometric point of view the multi method approach followed in this study up to date theoretical and thermodynamic equations ad hoc silica geothermometers inferred from local rocks checking of the results on a 18o sulfate water vs temperature diagram provides some insights and perspectives on how to tackle the problem

a reconnaissance rb sr sm nd u pb and k ar study of some host rocks and ore minerals in the west shasta cu zn district california the copley greenstone balaklala rhyolite and mule mountain stock in the west shasta cu zn district california have rb sr sm nd u pb and k ar systematics that indicate they are a cogenetic suite of ensimatic island arc rocks about 400 m y pervasive alteration and mineralization of these rocks for the most part was syngenetic and the major component of the mineralizing fluid was devonian seawater k ar ages of quartz sericite concentrates from ore horizons and rb sr systematics of a few rock and ore specimens record a later thermal and mineralizing event in the district of about 260 m y contamination of some rocks with pelagic sediments is indicated by the sm nd data

behaviour of major elements and some trace elements li rb cs sr fe mn w f in deep hot waters from granitic areas abstract analyses of selected hot springs in more than sixty areas in granites from europe are presented concentrations of major elements and of some trace elements li rb cs sr fe mn w f in high ph waters are not significantly affected by processes during uprise from the deep reservoir to the surface re equilibrations mixing with surficial waters normalized to k or na concentrations of all other elements are related to the aquifer temperature the knowledge of aquifer temperature and total electric charge of mobile elements cl s possibly f allows us to predict both major elements within 50 and trace elements within a factor 2 or 3 concentrations in alkaline waters from granites

hydrogeochemistry isotopes and geothermometry of ixtapan de la sal tonatico hot springs mexico the ixtapan de la sal tonatico hot springs are located in the geological setting of the trans mexican volcanic belt on the border of the morelos guerrero basin which is carbonated region with limestone and silicic rocks the temperature electrical conductivity and ph of the thermal waters are 25 7 37 2 c 9520 13 920 s cm and 5 90 6 88 respectively the hydrochemical family is nacl cl mean concentration of 2198 mg l and na mean concentration of 1396 mg l the minor and trace elements that are notable for their high concentrations are b 19 69 23 58 mg l li 6 09 8 06 mg l sr 4 80 6 18 mg l and as 0 30 1 97 mg l isotope data 18o 2h show 18o enrichment of the thermal waters which may be a result of isotopic exchange with the host rock at high temperatures although the value was very small which may be due to mixing with groundwater near the surface the water samples were oversaturated with calcite dolomite and quartz verified in the field by the presence of precipitated rocks travertines the samples were undersaturated with chalcedony silica gel cristobalite celestite and strontianite several chemical geothermometers and the results from multicomponent equilibrium suggest a reservoir temperature between 90 and 130 c meanwhile a temperature of 129 c was estimated with the cl enthalpy mixing model according to the conceptual model of the functioning of this system considering that flow is characterized by the heating of water at deep zones due to the high geothermal gradient caused by recent tectonic activity this water rises to the surface through fractures and faults as it rises thermal water mixes in different proportions with ca hco3 groundwater

temporal changes in subglacial meltwater activity field evidence from the late devensian in the north of ireland abstract temporal changes in meltwater abundance distribution and characteristics controlling subglacial processes and ice sheet dynamics can be inferred from subglacial sediment successions field evidence for changes in subglacial meltwater characteristics over time is presented from two sites doonan drummee near a former late weichselian devensian ice centre in the north of ireland on a macroscale both sites investigated show subglacial diamicton overlying glacially planated bedrock platforms in more detail primary sedimentary structures and facies variability show a complex relationship between depositional processes and meltwater characteristics at the ice bed interface ibi sedimentary evidence suggests sediment transport and deposition took place by low viscosity subglacial slurries mobile sediment meltwater admixtures which are part of a continuum between the processes of subglacial sediment deformation and subglacial meltwater flooding subtle changes in meltwater abundance and distribution at the ibi controlled slurry rheology mechanisms of particle support and detailed sediment depositional processes

discussion inferred subglacial meltwater origin of lakes on the southern border of the canadian shield in their paper the authors r gilbert and j shaw add small finger lakes in narrow valleys incised through an up icefacing cuesta to the lengthening list of landforms large and small that they and their like minded colleagues ascribe to erosion or deposition by high discharge subglacial drainage this list has included previously drumlins erosion marks subglacial erosion s forms rogen moraine fluvial dunes tunnel channels a moraine and regional landform assemblages often in these works the glaciofluvial flooding argument is so convincingly based on the field evidence and counters the glacial argument so effectively that one feels the conceptual ground shift and one s stance upon it changed occasionally however as in shaw and gilbert 1990 and the present paper the argument seems to be based on little more than that other features have been explained by this process so why not this feature too in the present paper the authors give an excellent detailed description of the distribution and form of long narrow lake basins incised into a limestone cuesta facing up ice over the precambrian shield of southeastern ontario they liken them to the new york finger lake valleys and those in the niagara cuesta of ontario which have been viewed previously as of glacial origin thus preferential erosion by fast flowing ice and the presumed absence of subglacial tributaries convincingly account for the valley forms of the finger lakes and other reentrant or through valleys p 1634 however they caution any agent that might have preferentially eroded through valleys could take the place of glaciers in the above discussion p 1634 any agent that is except subaerial fluvial erosion which they discount on grounds going back to playfair s law if large volumes of subglacial meltwater were to be channelized across escarpments p 1634 original emphasis valleys would be cut similar in many respects to glacial troughs thus is the subglacial meltwater hypothesis introduced not solely from evidence but with much supposition tributaries would cut by the same floods anastomose shaw 1988 brennand and shaw 1994 and esker ridges with dendritic patterns and accordant junctions recordonly the most powerful flood events brennand 1994 p 9 the argument continues both through valley and reentrant valley regions finger lakes and niagara cuesta lie astride major flood routes proposed by shaw and gilbert 1990 this would be fine if the latter reconstruction met with wide independent acceptance but it seems unfair to seek such support from it when that paper so summarily dismisses the widely accepted glacial history of for example the western borderlands of lake ontario the present argument has nevertheless gained momentum albeit cheaply leading to we suggest that meltwater floods may well explain the prominent valleys we describe here p 1635 emphasis added this seems strangely shy but may recognize the thinness of the logical ice at this point furthermore flow was across a wide area upstream of the escarpment p 1635 yet tunnel channels and an esker in one of them lie upstream as well as downstream of the escarpment brennand and shaw 1994 p 507 indicating channelled not sheet flow nearly equal spacing p 1635 of the valleys in question suggests to the authors that linearly concentrated escape of sheetfloods over the escarpment was hydrodynamically rather than morphologically or structurally controlled as was the origin of fluting on the tops of escarpment promontories noses p 1635 we are left in the dark however as to how this control works rather we leap ahead to as the flow streamed around the escarpment and noses into the valleys p 1635 given the valleys we can follow the argument into counterrotating vortices a residual medial ridge in one valley and the localization of valley floor basins but it is exasperating to miss how a high discharge high velocity sheetflood becomes patterned into longitudinal counterrotating vortices when it meets an escarpment this is not to say that the phenomenon is incredible but be unlikely p 1635 yettunnel channels said to have been we are entitled t o more by way of explanation than the van dyke reference more accessible than this and charac

petrogenetic evolution of felsic volcanic sequences associated with phanerozoic volcanic hosted massive sulphide systems the role of extensional geodynamics abstract felsic volcanic hosted massive sulphide deposits form in many different geotectonic environments usually associated with episodes of extension however empirical geochemical links between felsic volcanism geotectonic environment and extensional geodynamics have not been adequately documented so as to distill the fundamental relationships between these features and formation of volcanic hosted massive sulphide vhms mineralization which is important considering most vhms deposits are hosted in felsic volcanic bearing sequences using felsic geochemical data from six different vhms mineralized phanerozoic geotectonic settings it seems that the felsic geochemical data are consistent with the overall geotectonic interpretations for these areas which in turn helps in stratigraphic and geotectonic interpretations for detailed vhms exploration in extensional geodynamic settings bimodal volcanism is common compared to the continuum of compositions observed under compressional to neutral high stress regimes in calc alkaline arc building environments the empirical geochemical metallogenic vhms relationships evident in the archean felsic volcanic rocks in particular the low zr y n yb n 2 o conditions in different source areas and geotectonic environments they seem to be the predominant controls on the compositional evolution of felsic magmas in extensional settings because of the limited degree of assimilation and fractional crystallization afc affecting their compositions with rapid intrusion into the uppermost crust to positions were they achieve neutral buoyancy in the volcanic to subvolcanic environment within plate felsic or a type anorogenic type and anomalous ocean ridge or type felsic magmas that have tholeiitic affinities relatively low alkali elements are common within parts of the volcanic sequences hosting massive sulphide deposits reflecting in part a relationship to extension the high contents of high field strength elements zr ga lree hree y nb etc and other lines of evidence indicate they are relatively high temperature relatively reduced magmas probably derived from previously dehydrated granulitic or melted oceanic simatic or continental sialic crust low p granulites or amphibolites but also in some cases possibly mantle rocks such that they are significantly water undersaturated during melting i e a h 2 o 1 reduced viscosities typical of high temperature melts enable rapid intrusion to higher levels diking vs diapirism higher rates of heat advection from mantle mafic magmas into the thickened oceanic and or continental crust during lithospheric extension are needed to facilitate melting of these rock to form a type and or or type partial melts tholeiitic felsic this usually results in bimodal magmatism as magma mixing is not favored in extensional settings especially at high magma production intrusion and extrusion rates i e high heat flow this would inhibit ferromagnesian phase in particular hornblende and magnetite fractionation especially at low f o 2 in the felsic magmas that would deplete the melt in y hree as well as ore related elements particularly zn which is 2 to 3 times higher in a type and or type rocks compared to other magma types therefore the empirical felsic igneous geochemical metallogenic relationships observed by others low zr y n yb n

sedimentary facies relationships in esker ridge esker fan complexes southeastern ontario canada application to the exploration for asphalt blending sand abstract in this paper we examine the viability of using sedimentological facies modelling techniques in the exploration for a specific aggregate mineral resource blending sand blending sand is a naturally occurring medium grained poorly sorted aggregate that is an integral component of asphalt mixes in canada and the northern united states and europe glacial outwash deposits are a common exploration target a glaciogenic complex in southeastern ontario that contains blending sand was examined in order to document the facies organization and origin of the complex as a whole and the blending sand deposits in particular in this study blending sand is located only within the proximal portion of the esker fans and can be characterised as a distinct facies that was formed by sustained high density underflows which deposited cross bedded medium sand periodic fluctuations in flow speed allowed interbeds of rippled fine sand to accumulate giving the facies its overall poor sorting a comparison with similar deposits elsewhere indicates that local facies associations have more widespread applicability therefore the surface morphology and the spatial arrangement of sediment facies within esker ridge esker fan complexes can be used as predictive exploration tools to locate blending sand in these types of deposits different facies models are needed for other deposit types and aggregate products

tdr measurements of hydraulic jump aeration in the south fork of the american river california abstract turbulent pressure and velocity fluctuations associated with hydraulic jump air entrainment likely play an important role in local flow dynamics and morphologic changes of steep bedrock and alluvial rivers previous engineering research indicates that hydraulic jump air entrainment and energy dissipation locally intensify erosion of both bedrock and alluvial elements enhance hydraulic quarrying suppress cavitation and decrease the friction factor of a flow despite studies in artificial settings air content in natural hydraulic jumps remains largely unquantified in this study time domain reflectometry tdr a method commonly used to determine the volumetric water content of porous media for the last two decades was evaluated in the laboratory and then adapted to measure air contents of natural hydraulic jumps laboratory tests were conducted to determine the influence of turbulence temperature and sampling volume on the tdr signal over an air content range of 0 100 based on the results of the laboratory tests an empirical calibration was developed that converts the tdr signal into air content local air contents were then measured in hydraulic jumps occurring along a mixed alluvial and bedrock dominated 8 4 km section of the south fork american river two small jumps had a mean air content of 19 and 23 a coefficient of variation cv of 27 and 28 and a root mean square rms of 19 and 24 respectively a large jump had a mean air content of 42 a cv of 26 and a rms of 44 tdr provides fast accurate repeatable and nondestructive in situ measurements at one tenth the cost of traditional methods and is far more robust for field applications than traditional lab instruments future studies can now expand upon the hydrogeomorphic and ecological significance of jump aeration

glaciofluvial erosional morphology and sediments of the coronation spondin scabland east central alberta spatially discontinuous meltwater channel networks on the canadian prairies are usually interpreted as having formed subaerially in front of the retreating laurentide ice sheet evidence in the coronation spondin scabland east central alberta supports an alternative formation by progressive channelization of a subglacial sheetflow of water the scabland is an integrated channel network with varying degrees of anabranching the channels having highly variable sizes shapes and orientations enhanced scour at some channel confluences reflects contemporaneous channel utilization channels also display convex up concave up and undulatory along channel profiles with some junctions at the same elevations longitudinal grooves in large scale channels are associated with numerous boulder deposits residual hills demarcated by channels display composite and streamlined forms superimposed on residuals are erosional transverse bedforms longitudinal grooves and undulating surfaces that indicate submergence

fluid geochemistry and geothermometry applications of the kangding high temperature geothermal system in eastern himalayas abstract high temperature geothermal systems hold an enormous capacity for generating geothermal energy the kangding area is a typical high temperature geothermal field in the himalayan geothermal belt hydrogeochemical gas geochemical and isotopic investigations were performed to identify and qualify the main hydrogeochemical processes affecting thermal water composition including mixing and degassing and then to estimate a reliable reservoir temperature nine water samples and four geothermal gas samples were collected and analysed for chemical and isotopic components the results demonstrate the alkaline deep geothermal water is the mixtures of approximately 75 snow melt water and 25 magmatic water it is enriched in na k f li and other trace elements indicating the granite reservoir nature the shallow geothermal water is the mixtures of approximately 30 upward flow of deep geothermal water and 70 meteoric cold water high concentrations of ca mg and hco3 indicate the limestone reservoir nature there is no remarkable oxygen isotope shift in the geothermal water since the rapid circulation is difficult to trigger off strong water rock interaction co2 is the predominant geothermal gas accounting for more than 97 of total gases in volume percentage the concentration of co2 degassing ranged from 0 4 mol l 1 to 0 8 mol l 1 via geothermometrical modelling as a result the geothermal water ph increased from 6 0 to 9 0 and approximately 36 of the total sio2 re precipitate the sources of co2 are the metamorphism of limestone and magmatic degassing based on the composition of carbon isotope the appropriate geothermometers of na k and na li yield reservoir temperature of 280 c the geothermometrical modelling developed to eliminate the effects of co2 degassing yields temperature of 250 c the silica enthalpy mixing model yields temperature of 270 c with no steam separation before mixing

saginaw lobe tunnel channels laurentide ice sheet and their significance in south central michigan usa abstract a network of tunnel channels in southern michigan records substantial subglacial meltwater activity beneath the saginaw lobe of the laurentide ice sheet the channels are incompletely filled with outwash contain eskers and in many places crosscut and continue beyond upland ridges previously mapped as recessional moraines the presence of the tunnel channels and drumlins on these upland ridges indicate that the ridges are not recessional moraines instead outwash fans and minor ridges record deglaciation in the area a palimpsest relationship between buried bedrock valleys and tunnel channels records the presence of multiple generations of tunnel channels evidence for a subglacial meltwater sheetflow consists of sheets of boulder gravel in upland 15 km wide with a hummocky upper surface the hummocks transform down flow into erosional remnant drumlins possibly the result of flow acceleration on a negative slope tunnel channels at the distal end of the drumlin swarm suggest collapse of the sheetflow into a channelized flow the tunnel channels then end at the sturgis moraine at the heads of large outwash fans the observed geomorphic relationships between tunnel channels moraines and drumlins in south central michigan are applicable to glacial landform studies elsewhere and indicate the important role of meltwater in landscape evolution

non magmatic fracture controlled hydrothermal systems in the idaho batholith south fork payette geothermal system abstract non magmatic fracture controlled hydrothermal systems located within and near the idaho batholith have been examined and evaluated for potential application as natural analogues to high level nuclear waste repositories detailed geochemical petrologic and structural studies of hot springs along the south fork of the payette river sfpr in central idaho usa have been combined to assess the nature of a hydrothermal aquifer system along a major brittle shear zone geochemical modeling of thermal spring water chemistry with solveq reed m h 1992 solveq users manual unpublished report dept of geological sciences university of oregon eugene or indicates reservoir temperatures of 85 c to 160 c and an alteration assemblage consisting of several clays chlorite serpentinites quartz albite microcline and micas geothermometry calculations coupled with independent estimates of geothermal gradients based on heat flow and regional geology allow estimation of reservoir depths ranging from 2 4 to 6 7 km comparison of trace element rare earth element and solveq alteration assemblages supports the hypothesis that waters equilibrated with granitic rocks at depth and ascended to the surface in a short time span stable isotope data d 138 4 to 148 4 and 18 o 17 5 to 19 4 indicate that thermal waters of meteoric origin have interacted with country rocks at a very high water rock w r ratio systematic variations in d values and the amount of 18 o shift for thermal waters suggest that recharge probably occurs at much higher elevations than discharge fracture orientations petrologic relations and geochemical differences between adjacent springs delineate separate hydrothermal systems along the major structure defining the course of the sfpr hydrothermal systems along the sfpr exist primarily as small circulation cells which are probably influenced by minor changes in geothermal gradients associated with different rock types these subsystems are dependent on periodic seismic or microseismic activity to maintain flowpaths a working model of deep fracture controlled hydrothermal convection systems based on the sfpr geothermal system may be used to evaluate the long term behavior of artificial hydrothermal systems associated with high level nuclear waste repositories

on the formation of large subglacial lakes the role of subglacial water storage beneath continental ice sheets is investigated primarily for a deformable bed subglacial ponding is shown to occur under most regions of warm based ice sheets and large subglacial lakes can become established for example in the hudson bay basin the formation of large lakes depends upon the fact that the ice surface gradient is reduced once subglacial ponding occurs and upon the feedback between the reduced ice surface gradient and increased subglacial ponding subglacial ponding likely played a large role in determining the ice sheet topography during late deglaciation and in speeding up the deglaciation process

theoretical geothermometers andpco2 indicators for aqueous solutions coming from hydrothermal systems of medium low temperature hosted in carbonate evaporite rocks application to the thermal springs of the etruscan swell italy in order to derivet pco2 geoindicators suitable for thermal waters coming from the hydrothermal systems of medium low temperature which are hosted in carbonate evaporite rocks the theoretical concentration of ca mg hco3 so4 f and their complexes in aqueous solutions in equilibrium with a mineral assemblage made up of calcite dolomite anhydrite and fluorite has been calculated at temperatures between 0 and 150 c atpco2 in the 0 1 100 bar interval and for total molality of mobile species na and ci ranging between 0 0001 and 0 3 the results of such calculations indicated that 1 the ca mg s04 and f contents and thes04 f 2 andcamg ratios are potential geothermometers 2 the hc03 2so4 ratio is a pco indicator 3 thehc03f ratio and the hc03 content arc indicators of bothpco2 andt a first geothermometric and geobarometric evaluation of the thermal springs of the etruscan swell generally shows equilibrium temperatures in the interval 50 100 c and pco from about 1 bar to bars these estimations are consistent with the general knowledge of the hydrothermal systems of medium low temperature present in the region

hydrogeochemical outline of thermal waters and geothermometry applications in anatolia turkey abstract the chemical compositions of a total of 120 thermal water samples from four different tectonically distinct regions central north east and west anatolia of turkey are presented and assessed in terms of geothermal energy potential of each region through the use of chemical geothermometers na ca hco3 type waters are the dominant water types in all the regions except that na cl type waters are typical for the coastal areas of west anatolia and for a few inland areas of west and central anatolia where deep water circulation exists the discharge temperature of the springs ranges up to 100 c and the bottom hole temperatures in drilled wells up to 232 c geothermometry applications yield reservoir temperatures of about 125 c for central anatolia 110 c for north anatolia 136 c for east anatolia and 251 c for west anatolia the latter agreeing with some of the bottom hole temperatures measured in drilled wells the results reveal that the highest geothermal energy potential in turkey is associated with the west anatolian extensional tectonics which provides a regional deep seated heat source and a widespread graben system allowing deep circulation of waters the north anatolian region bounded to the south by the dextral north anatolian fault along which most of the geothermal sites are located has the lowest energy potential probably due to the restriction of the heat source to local magmatic activities confined to pull apart basins the east anatolian region undergoing contemporary compression and the central anatolian region where the compressional regime in the east is converted to the extensional regime in the west have moderate energy potential although the recently active volcanoes suggest the presence at depth of still cooling magma chambers that are potential heat sources the lack of well developed fault systems is probably responsible for the comparatively low energy potential of these regions almost all the thermal waters of turkey are saturated with respect to calcite and hence have a significant calcite scaling potential which is particularly high for west anatolian waters

contemporaneous localized basal ice flow variations implications for bedrock erosion and the origin of p forms a detailed study of a proglacial bedrock site and a subglacial cavity of an outlet of oksfjordjokelen norway is presented together with observations from the foreland of konowbreen spitsbergen striation directions and subglacial observations indicate that local ice flow paths were highly variable deviating at angles of approximately 90 from the main ice flow direction stepped bedrock topography appears conducive to the production of highly variable ice flow paths because the high bed roughness creates a locally variable stress regime within the ice including low pressure lee side areas into which ice can flow if ice flow is sustained along a specific path and the ice contains debris then abrasion should produce an erosional bedform models are proposed whereby locally variable ice flow patterns could produce erosional bedforms which would be described as p forms purely through mechanical abrasion

the origin of the western lake erie grooves ohio implications for reconstructing the subglacial hydrology of the great lakes sector of the laurentide ice sheet abstract streamlined grooves and s forms cover the western lake erie islands ohio as well as the channels between the islands and the adjacent mainland although previous interpretations advocate direct glacial ice erosion we offer the alternative interpretation that forms were eroded by meltwater specifically by plucking sediment abrasion and cavitation in high velocity sediment laden flows we base our arguments on detailed descriptions and interpretations of the glacial grooves state memorial site ggsm on kelleys island the site consists of a linear furrow that is adorned by s forms in its base and on its walls these include linear forms cavettos sichelwannen comma forms multi troughed forms and plunging forms all s form sites provide a snapshot of the last phase of erosion after evolution of the local landscape through multiple generations of s form formation as s forms are found on topographic highs and lows we believe they represent a regional flow that overtopped the majority of the islands flow was initially as a sheet that quickly collapsed into channelized flow that was diverged around the islands we also believe that this flow had a major impact on the laurentide ice sheet in this region resulting in rapid glacial advance and extremely low ice sheet profiles

flood geomorphology of the katherine gorge northern territory australia the katherine gorge is a narrow deep canyon system developed in resistant sandstone the tropical monsoonal climate results in rare flood events of very large magnitude these floods flush sand sized sediment as washload through the gorge but local accumulations are preserved as slack water deposits at tributary mouths paleoflood hydrologic analysis of the deposits employing step backwater flow modeling allows quantitative estimates to be made of geomorphically significant flows for an annual exceedence probability of 10 2 the gorge may experience discharges of 6 000 m 3 s mean velocities of 7 5 m s flow depths of 15 to 45 m stream powers per unit area as great as 1 10 4 watts m 2 and bed shear stresses of 1 5 10 3 n m 2 such flows are required to transport boulders 3 m or more in intermediate diameter that occur at large scale riffles at maximum stage pools reach depths of 45 m and are preferentially developed at vertical joint intersections in the rock probably through intense hydraulic action pool and riffle development thus reflects the channel boundary characteristics for extreme flow conditions additional indicators of especially intense flow phenomena include potholes flutes abraded facets on rock bar surfaces and scabland development on upland bedrock surfaces

application of selected geothermometers to exploration of low enthalpy thermal water the sudetic geothermal region in poland the most important intakes of thermal waters within the sudetic geothermal region occur in three separate hydrogeothermal systems 1 l dek 2 duszniki and 3 cieplice all these waters are of meteoric origin and circulate in crystalline rocks to different depths their outflow temperatures are between less than 20 c and to about 87 c to evaluate the geothermal fields in the light of their prospectiveness to further exploration of thermal energy resources we took an effort to apply selected isotopic and chemical geothermometers to assess the maximum possible temperatures which may be found in the reservoirs the only chemical geothermometers which give a reliable range of reservoir temperatures are sio2 chalcedony na ka ca and partly na k ones the oxygen isotopic geothermometer in the so4 h2o system gives a real range of estimated reservoir temperatures only for deeply circulating waters in the cieplice area on the other hand in the case of co2 rich waters in the duszniki area where outflow temperatures do not exceed 30 c application of chemical or isotopic temperature indicators always leads to erroneous results due to the lack of equilibrium in the thermodynamic system of water rock interaction

air concentrations of submerged and unsubmerged hydraulic jumps in a bedrock step pool channel 1 the classical hydraulic jump which is a hydraulic jump formed in a horizontal smooth and prismatic laboratory flume has often been used for estimating hydraulic and morphologic characteristics of mountain river channels however most studies utilizing classical hydraulic jump relationships have neglected the role of aerated flows and jump types prevalent in natural systems by developing a methodology to survey digitize and visualize air concentrations for jumps in bedrock rivers we present new data for submerged jumps and sloping jumps in a bedrock step pool channel as with laboratory research our results indicated peak mean and local air concentrations of natural jumps were skewed by submergence of the jump roller beneath the free surface however unlike laboratory research cross stream variations were significant for both jumps varying up to 20 across the jump width traces through each jump thalweg also indicated the classical hydraulic jump was a poor analogue for estimating surficial air concentrations

channel form and processes in bedrock and alluvial reaches of the raritan river new jersey fluvial geomorphologists have generally considered alluvial and bedrock channels to be fundamentally different in character alluvial channels being shaped by sediment transport processes and bedrock channels being shaped by structural and lithologic controls this study examines a 12 km bedrock floored reach of the raritan river that separates two gravel bed reaches above and below the bedrock channel has a patchy veneer of sandy gravel that covers the bed in areas of low slope but elsewhere consists of lateral bars and discrete two dimensional gravel bed forms perched on bedrock mean b axes of the 25 largest clasts on the crests of these bed forms range from 10 4 to 13 8 cm shear stresses estimated from measured velocity profiles and depth slope calculations indicate that most clasts on the bed forms are entrained by the bankfull discharge 290 m s which is equaled or exceeded about 1 of the time the thalweg of the 80 m wide channel is incised about 0 5 to 0 7 m and it meanders with a wavelength of about 750 m or approximately 10 times channel width this thalweg meander wavelength is consistent with reference to drainage area when compared to channel meander wavelengths in other locations within the basin and is similar to that in other rivers of comparable dimensions and discharge the bedrock alluvial reach is similar to alluvial channels with reference to meander geometry and sediment distribution it occupies an intermediate position on a continuum of channels of varying sediment supply in relation to transport capacity ranging from alluvial channels to those completely formed in bedrock

reply inferred subglacial meltwater origin of lakes on the southern border of the canadian shield paleozoic rocks form an escarpment up to 35 m high at the border with the frontenac axis of the canadian shield in southeastern ontario the escarpment which lies nearly transverse to the flow direction of pleistocene ice and subglacial meltwater in the region is cut by a series of deep channels locally incised into the bedrock at the escarpment a subbottom acoustic survey of two of these channels and mapping of a third partly flooded channel revealed the shape of the bedrock surface beneath the water and glacial and postglacial sediments of lakes now occupying the channels most cross sections show a smooth walled dominant depression eroded up to 100 m below the land surface nearby and flanked by one or more secondary depressions the pattern changes considerably in detail making secondary depressions especially difficult to trace along the length of the lake the pattern is similar to that of subglacial fluvial erosion marks more than three orders of magnitude smaller found in bedrock throughout

indirect velocity measurement from standing waves in rockbed rivers direct measurement of velocities and discharge in turbulent rockbed rivers is dangerous and often impracticable float measurements of surface velocity in sediment free rockbed reaches of rivers are used to test the equation due to kennedy that the mean velocity of a critical wave train is given by v 1 2495 where is the wavelength of the standing waves field data collected for wavelengths between 0 5 m and 7 m estimates surface velocity as about 2 significantly higher than the predicted mean velocity it is concluded that the kennedy equation successfully represents the mean velocity in rockbed rivers which are essentially free from sediment and that measuring the wavelengths of standing wave trains is an accurate and economical method of measuring mean velocity in the field from estimated wave train width and computed critical depth minimum discharge can be estimated for the section

kinematic indicators in fault gouge tectonic analog for soft bedded ice sheets abstract polished slip planes resulting from basin and range detachment faulting of mid tertiary volcaniclastics are well exposed at lake pleasant arizona u s a slip planes show erosional features formed by abrasion below moving sheets of gouge coarse grained diamict during repeated faulting and shearing tectonically generated forms are identical to those found in glaciated terrains slip planes show rat tail ridges and grooves ridge in groove structures nail head striations and wear tracks a prominent morphological element consists of flute ridges up to 30 cm wide and at least 7 m long formed of gouge preserved in the lee of boulders projecting as obstacles above slip surfaces crescentic scours around the stoss side of such boulders record enhanced abrasion by streams of gouge debris clasts are striated and show shapes comparable to flat iron clasts produced by glacial abrasion kinematic indicators at lake pleasant are directly comparable in form to flutes and drumlins in glaciated terrains the data presented here not support a recent hypothesis arguing that glacial striations flutes and drumlins are the product of turbulent subglacial meltwater instead diamict produced along fault planes gouge by low grade shearing is directly comparable to diamict facies deformation till formed by pervasive shear at the base of soft bedded ice sheets both facies are tectonically generated cataclastites produced in low grade shear zones and display genetically related but differently scaled streamlined bedforms

evidence for large scale subglacial meltwater flood events in southern ontario and northern new york state flow line patterns constructed from the orientation of drumlin long axes are used to infer two major subglacial meltwater floods in southern ontario and northern new york state in this interpretation the flood waters of the first event the algonquin surged southward in the later ontarian event powerful floods streamed southwestward along the basins of lakes ontario and erie bedrock fluting upstream pointing noses on escarpments and tunnel channels give supporting evidence for the regional flood hypothesis regional distributions of drift thickness may be explained by this hypothesis