hydraulic geometry change of a large river a case study of the upper yellow river study on hydraulic geometry can reveal the response of river systems to basin attributes and the trends in channel change based on 35 years of data collected at 10 hydrological stations cross sections the hydraulic geometry relations between cross sectional variables and discharge were established and the derived parameters were analyzed the channel behavior of the mountainous bedrock reach from riverhead to xunhua cross section and the alluvial reach from xunhua to toudaoguai cross sections differed significantly over the past decades in response to dramatic water and sediment changes the hydraulic geometry quasi equilibrium was achieved through equally adjusting water depth and flow velocity in the mountainous bedrock reach while primarily through flow velocity in the alluvial reach the change rate of river width with varying discharge was relatively small in the whole upper yellow river compared with the lower yellow river and other rivers in the world both similarity and differences existed indicating the general adjustment direction of hydraulic quasi equilibrium and also the importance of considering other influencing factors in hydraulic geometry studies in addition dams played an important role in affecting the changes of hydraulic geometry exponents

onshore and offshore evidences for four abrupt warming episodes during mis 6 at the westernmost tip of continental europe did they control the migrations of neanderthals the total shell production typical of the pupilla association in the onshore site of nantois brittany france evidenced for the first time four brief abrupt warm and humid episodes during the upper saalian mis 6 loess deposition these warming events were also found in the marine deposits of the celtic sea md03 2692 core comparison with the variations of the sea level show that the warming episodes were not only of regional interest but corresponded to global events ruled by precession and insolation cycles other comparisons with biomarker records mollus s charcoal and rodents of the paris basin villiers adam and jersey island la cotte de saint brolade confirm the existence of these warmer events tentative correlations with the discontinuous neanderthal dwelling phases recorded in brittany suggest that these populations were mainly only present in westernmost europe during the warmer episodes

the downstream gradation of particle sizes in the squamish river british columbia the exponential downstream decline in particle size predicted by sternberg 1875 is examined within a highly active alpine fluvial environment the gravel bed squamish river in southwestern british columbia transect survey procedures for sampling within the coarse alluvial gravels are described in detail downstream trends for various particle size statistics plotted with distance from a major sediment source are considered according to two scenarios evaluation of overall trends indicates that the downstream expression derived by sternberg 1875 is not the most appropriate rather curves are better described by power functions this reflects a very rapid decline in particle size immediately downstream of the major sediment source secondly evaluation of downstream trends in relation to channel planform determines that exponential functions with different coefficients describe adequately relations within individual planform reaches there is insufficient evidence to suggest which of these two scenarios may be appropriate several lines of evidence suggest that the trends found are more the result of selective sediment transport phenomena than of abrasion a condition attributed to channel competence within a system dominated by sediment supply conditions

large flume experiments on the stable straight gravel bed channel a set of experiments is described that obtain the shape of stable straight uniform mobile bed channels with cohesionless banks these experiments were carried out in an outdoor flume at length scales at least twice those used by previous experimenters but otherwise using similar techniques including the use of a half channel against the flume wall in order to suppress meandering eight flume runs are reported including channels farther from threshold conditions than those previously tested the resulting data might prove useful both in validating theories for the stable shape of the straight channel and for advancing models of the adjustment to that shape

the elements and richness of particle diffusion during sediment transport at small timescales the ideas of advection and diffusion of sediment particles are probabilistic constructs that emerge when the master equation a precise probabilistic description of particle conservation is approximated as a fokker planck equation the diffusive term approximates nonlocal transport it looks upstream and downstream for variations in particle activity and velocities whose effects modify the advective term high resolution measurements of bed load particle motions indicate that the mean squared displacement of tracer particles when treated as a virtual plume primarily reflects a nonlinear increase in the variance in hop distances with increasing travel time manifest as apparent anomalous diffusion in contrast an ensemble calculation of the mean squared displacement involving paired coordinate positions independent of starting time indicates a transition from correlated random walks to normal fickian diffusion this normal behavior also is reflected in the particle velocity autocorrelation function spatial variations in particle entrainment produce a flux from sites of high entrainment toward sites of low entrainment in the case of rain splash transport this leads to topographic roughening where differential rain splash beneath the canopy of a desert shrub contributes to the growth of a soil mound beneath the shrub with uniform entrainment rain splash transport often described as a diffusive process actually represents an advective particle flux that is proportional to the land surface slope particle diffusion during both bed load and rain splash transport involves motions that mostly are patchy intermittent and rarefied the probabilistic framework of the master equation reveals that continuous formulations of the flux and its divergence the exner equation represent statistically expected behavior analogous to reynolds averaged conditions key topics meriting clarification include the mechanical basis of particle diffusion effects of rarefied conditions involving patchy intermittent motions and effects of rest times on diffusion of tracer particles and particle borne substances this article is protected by copyright all rights reserved

calabrian eopleistocene micromammal assemblages from the lacustrine and fluvial deposits of the southern trans urals and chronological position of some regional stratigraphic units abstract in the southern trans urals the quaternary deposits dated back to the early pleistocene 2 58 0 77 ma are scarce incomplete and often severely eroded data scarcity is a major challenge for accurate geological correlation and for integration of regional data into continent wide stratigraphic frameworks we provide a review of stratotypes and type localities for regional stratigraphic subdivisions of the eopleistocene the units correlated with the calabrian stage of the western european stratigraphical timescale 1 8 0 77 ma with particular focus on small mammals and their biochronological significance subdivisions of the eopleistocene which have been officially accepted in russia include three regional chronostratigraphic units horizons starting from uvel ka to chumlyak and sarykul we show that the calabrian deposits are characterized in the southern trans urals by sequential changes in the evolutionary level of micromammal assemblages that could be directly correlated with the mammal based biochronological zones mqr of russia vangengeim and tesakov 2008 tesakov and titov 2013 within the interval from mqr 10 to mqr 8 analysis of micromammal assemblages reveals incongruent positioning of the officially accepted uvel ka chumlyak and sarykul horizons in the regional stratigraphic chart the revealed incongruences appear to be a result of the difficulty to delineate chronostratigraphic units using the highly eroded and reworked sediments of fluvial origin the complete cycles of alternating fluvial lacustrine sedimentation and subaerial exposure provide the most reliable sections to establish the chronostratigraphic units of the calabrian stage of the early pleistocene in the southern trans urals the position of chumlyak and sarykul horizons in the regional stratigraphic chart of the southern trans urals is proposed to be changed the validity of the uvel ka formation as a chronostratigraphic unit should be further verified with a particular focus on faunal proxies mollusks ostracods and small mammals

upper paleolithic site tuyana a multi proxy record of sedimentation and environmental history during the late pleistocene and holocene in the tunka rift valley baikal region abstract the complex study of the 3 5 m thick section of the multi genetic sediments of the late paleolithic tuyana site tunka rift valley baikal region resulted in a first detailed record of the change in environment and climate of the ancient humans habitation in the tunka rift valley in late pleistocene and holocene in the interval of 36 ka cal bp until late holocene sedimentation processes in the section are characterized by multiple remobilizations redeposition traces are most strongly expressed in is 3 sediments apparently an intensive transient removal of slope sediments took place here at is 2 the common tendency of the natural environment and habitation conditions of the ancient humans in the tunka valley show domination of the open and relatively dry tundra steppe with areas of forests vegetation in the end of mis 3 mostly dry steppes with limited forest tundra and tundra associations in mis 2 with the spread of boreal taiga in holocene tunka rift valley around 50 ka cal bp had already been settled by humans and was visited by them during the periods of relatively favorable climatic conditions during the mis 3 optimums and in middle holocene the tuyana paleolithic complexes have extensive analogies with the aurignacian industries of eurasia the closest similarities could be drawn with the complexes of kulbulakien culture in middle asia and kazakhstan the tuyana site is currently the most eastern occurrence of the aurignacian culture in eurasia

reassessment of continental growth during the accretionary history of the central asian orogenic belt we argue that the production of mantle derived or juvenile continental crust during the accretionary history of the central asian orogenic belt caob has been grossly overestimated this is because previous assessments only considered the palaeozoic evolution of the belt whereas its accretionary history already began in the latest mesoproterozoic furthermore much of the juvenile growth in central asia occurred in late permian and mesozoic times after completion of caob evolution and perhaps related to major plume activity we demonstrate from zircon ages and nd hf isotopic systematics from selected terranes within the caob that many neoproterozoic to palaeozoic granitoids in the accreted terranes of the belt are derived from melting of heterogeneous precambrian crust or through mixing of old continental crust with juvenile or short lived material most likely in continental arc settings at the same time juvenile growth in the caob occurred during the latest neoproterozoic to palaeozoic in oceanic island arc settings and during accretion of oceanic island arc and precambrian terranes however taking together our data do not support unusually high crust production rates during evolution of the caob significant variations in zircon ehf values at a given magmatic age suggest that granitoid magmas were assembled from small batches of melt that seem to mirror the isotopic characteristics of compositionally and chronologically heterogeneous crustal sources we reiterate that the chemical characteristics of crustally derived granitoids are inherited from their source s and cannot be used to reconstruct tectonic settings and thus many tectonic models solely based on chemical data may need re evaluation crustal evolution in the caob involved both juvenile material and abundant reworking of older crust with varying proportions throughout its accretionary history and we see many similarities with the evolution of the sw pacific and the tasmanides of eastern australia

relation between flow surface layer armoring and sediment transport in gravel bed rivers this study investigates trends in bed surface and substrate grain sizes in relation to reach scale hydraulics using data from more than 100 gravel bed stream reaches in colorado and utah collocated measurements of surface and substrate sediment bankfull channel geometry and channel slope are used to examine relations between reach average shear stress and bed sediment grain size slopes at the study sites range from 0 0003 to 0 07 bankfull depths range from 0 2 to 5 m and bankfull widths range from 2 to 200 m the data show that there is much less variation in the median grain size of the substrate d50s than there is in the median grain size of the surface d50 the ratio of d50 to d50s thus decreases from about four in headwater reaches with high shear stress to less than two in downstream reaches with low shear stress similar trends are observed in an independent data set obtained from measurements in gravel bed streams in idaho a conceptual quantitative model is developed on the basis of these observations to track differences in bed load transport through an idealized stream system the results of the transport model suggest that downstream trends in total bed load flux may vary appreciably depending on the assumed relation between surface and substrate grain sizes copyright 2007 john wiley sons ltd

late middle pleistocene interglacial sediments from buivydžiai site eastern lithuania a problem of chronostratigraphic correlation abstract a number of interglacial sections discovered in the eastern part of lithuania and suggested as snaigup l interglacial were attributed to the saalian complex stage of middle pleistocene however the exact stratigraphical position and correlation of these interglacial sections are still arguable recent investigations were performed to get a clearer insight into the stratigraphy and sedimentation palaeoenvironment of the snaigup l interglacial sediments outcropping in buivyd iai section and included complex proxies pollen plant macrofossils diatoms loss on ignition magnetic susceptibility and optically stimulated luminescence dating interglacial sediments occur at the lowermost part of the exposure and reach more than 7 m thick palaeobotanical investigations confirm deposition of studied sediments during the different climatic stages of the interglacial an attempt at correlation between the buivyd iai section vegetational changes with vegetational succession obtained from north central europe allowed finding out some similarities with the schoningen lublinian interglacial the osl dating results do not contradict such a proposition as the two sand samples lying below the interglacial gyttja show sedimentation of this layer during the 300 5 20 9 ka and 317 3 21 8 ka time or mis 9 however recently obtained data are insufficient for grounding the correlation of studied section certainly additional chronostratigraphic investigations would be valuable and may contribute to the solution of the sediment age and correlation problem

in situ la mc icp ms and id tims u pb geochronology of cassiterite in the giant furong tin deposit hunan province south china new constraints on the timing of tin polymetallic mineralization abstract the furong deposit located in southern hunan province china is a newly discovered giant tin deposit spatially associated with the a type qitianling granite the petrogenetic link between the giant furong tin deposit and the qitianling granite batholith remains controversial because of the lack of precise dating for the tin polymetallic mineralization here we report for the first time in situ u pb data on cassiterite obtained by la mc icp ms and the results are compared to id tims data the in situ la mc icp ms analyses of the cassiterites provide a reliable age constraint for tin polymetallic mineralization in the furong deposit yielding an isochron age of 159 9 1 9 ma at 95 confidence level mswd 18 which is indistinguishable from the id tims 206 pb 238 u weighted mean age of 158 2 0 4 ma the in situ u pb ages corroborate the ar ar dates published for the furong tin deposit which indicate that the mineralization is coeval with the emplacement of the qitianling granite batholith these results provide further evidence of a close temporal link between the pluton s emplacement and tin mineralization in the furong area the data obtained clearly demonstrate that in situ la mc icp ms u pb dating of cassiterite is a robust geochronometer for direct dating of tin polymetallic mineralization

channel widening downstream of valley gorges influenced by flood frequency and floodplain roughness mountain fronts are the locus of significant variations in river width characterized by narrow bedrock gorges opening to wider unconfined alluvial rivers that are often braided the contribution of the abrupt change in river valley confinement in modulating the long term transport capacity and the resulting equilibrium channel width has never been considered here we use a numerical model integrating the full frequency magnitude distribution of streamflow to explore the long term bedload transport capacity of idealized confined and unconfined channels both single thread and braided the model predicts a significant transport capacity loss for a single channel of constant width at the transition between confined gorges and unconfined floodplains that is slightly reduced when floodplain vegetation is present because the total transport capacity of a single thread channel systematically decreases with channel width in a stochastic framework only narrower unconfined channels could compensate for the loss of confinement this prediction contradicts observations of widening ratios ranging from three to eight downstream of gorges in various world rivers we resolve this inconsistency by demonstrating that a braided river made of narrow channels inset in a wide floodplain can maintain the total bedload transport capacity downstream of gorges by increasing the range of competent discharges we also show that riparian vegetation may only enhance bedload transport capacity for highly variable discharge regimes and discuss the relevance of various definitions of representative discharges these results point to the previously unrecognized role of valley confinement in modulating the sediment transport capacity of rivers

formal stratigraphy of the neopleistocene middle and upper late pleistocene in the kola region nw russia abstract this paper presents available litho chrono biostratigraphy data on sediment sequences in the kola region derived from russian publications based on this compilation key sections have been suggested for primary stratigraphic subdivisions or horizons according to the general quaternary stratigraphic chart of russia the regional quaternary scheme is correlated with the international chart summarizing the available data 10 geological sections have been proposed as key sites sections for the middle and upper late neopleistocene horizons in different sections in the southern kola peninsula the most ancient deposits correspond to the chekalinsky early saalian mis 9 horizon which is identified by esr dating and multi proxy data and also to the moskovsky late saalian mis 6 horizon specified according to litostratigraphic data the last interglacial glacial cycle relates to the mikulinsky entire mis 5 podporozhsky mis 4 leningradsky mis 3 and ostashkovsky mis 2 horizons two marine events identified in key sections on the coastal kola peninsula correspond to the last interglacial mikulinsky mis 5 horizon they are referred to as the ponoi and strelna beds in the regional stratigraphic classification the third marine unit is correlated to the interstadial leningradsky mis 3 horizon key sections in the central and western kola region provide the interglacial and interstadial terrestrial sequences there is a high probability that litho biostratigraphy data and a single numerical ir osl dating testify to the glacial podporozhsky mis 4 horizon deposits in coastal natural outcrops and boreholes in the lovozero tundra mountains key sections of the ostashkovsky mis 2 horizon have not been referred to in the formal kola region stratigraphy yet

channel change bankfull and effective discharges on a vertically accreting meandering gravel bed river along the lower reaches of the waipaoa river new zealand cross section survey data indicate there was a 23 per cent decrease in bankfull width and a 22 per cent reduction in channel cross section area between 1948 and 2000 as the channel responded to increased inputs of fine suspended sediment following deforestation of the headwaters in late c19 and early c20 we determined the bankfull discharge within a 39 km long reach by routing known discharges through the one dimensional mike 11 flow model the model runs suggest that the bankfull discharge varies between 800 and 2300 m3 s 1 and that the average recurrence interval is 4 2 years on the annual maximum series by contrast the effective flow 360 m3 s 1 is equaled or exceeded three times a year the variability in bankfull discharge arises because the banks tend to be lower in places where flood flows are constricted than in reaches where overbank flow is dispersed over a wide area and because scour has counteracted aggradation in some locations there is no downstream variation in shields stress or in relative shear stress within the study reach bankfull shear stress is on average five times greater than the shear stress required to initiate motion at the effective discharge it is more than twice the threshold value the effective discharge probably has more relevance than the bankfull discharge to the overall picture of sediment movement in the lower reaches of the waipaoa river but because width is constrained by the stability and resistance of the bank material to erosion during high flows that also scour the bed the overall channel geometry is likely determined by discharges at or near bankfull copyright 2006 john wiley sons ltd

downstream fining in a rapidly aggrading gravel bed river downstream changes in particle size that occur in the waipaoa river a 104 km long gravel bed river in which rapid aggradation in the historic post 1800 period was triggered by the conversion of native forest to pasture are summarized in this paper the textural data presented are unique for a field situation not only because of the spatial resolution and extent of the sampling program but also because they provide information about the pattern of fining at different points in time they are supported by equally comprehensive topographic survey data from which local rates of aggradation can be derived despite variability induced by lateral sediment inputs there is an essentially continuous pattern of fining along the entire length of the river fining occurs in both the fine and coarse size fractions of the bed material the highest rates of fining occur in the larger percentiles of the subsurface bed material and in the surface bed material downstream fining in the waipaoa river appears to be a response to changes in flow hydraulics that are regulated by the concave configuration of the long profile the fining gradient developed rapidly in 45 years it does not appear to be influenced by the rate of aggradation nor the overall rate of sediment supply to the channel system because in the short term aggradation has a negligible impact on the inherited form of the long profile

downstream changes in the channel geometry of a large gravel bed river 1 field data obtained on a nearly contiguous segment of the colorado river in western colorado and eastern utah are used to examine the mechanisms driving downstream changes in channel geometry measurements characterizing the bank full hydraulic geometry bed material grain size and average channel gradient were made at closely spaced intervals in 10 alluvial and quasi alluvial reaches covering 260 km of the river these data indicate that changes in surface and subsurface grain sizes are small in relation to the change in channel slope over the full length of the study area the median grain size of the surface sediment decreases by a factor of a little more than 2 whereas the average channel slope decreases by a factor of about 5 the decreases in slope and median grain size are offset by a large increase in bank full depth relative to width such that the bank full shields stress b is constant downstream for the reach as a whole b averages 0 049 which is roughly 50 higher than the threshold for bed load transport

design for hydraulic geometry of alluvial channels a new solution to the stable channel paradox has been derived based on the contribution of secondary flow to the redistribution of boundary shear stress this new solution was then combined with the entropy based bank profile equations the flow continuity condition an appropriate frictional resistance relation and a sediment transport relation to develop a new geometric model for straight stable alluvial channels furthermore the effect of nonuniform boundary particle sizes was introduced to make the new geometric model applicable to a wide range of both laboratory experiments and natural alluvial rivers a fortran program was developed to compute the design procedure the comparisons between the cross sectional shapes depths and widths calculated by the new geometric model and field and laboratory data show that the proposed geometric model is in reasonable agreement with the data both for well graded and for nonuniform bed materials

the morphology of graded gravel rivers a network perspective analytical hydraulic geometry equations are combined with a watershed model to quantify downstrem trends in equilibrium fluvial morphology in gravel streams the hydraulic geometry equations relaet fluvial morphology to discharge bedload transport rate and grain size these independent variables are in turn determined by routing gravel supplied at zero order basins through a channel network as gravel is routed downstream it decreases in size according to an empirical power law the resulting model specifies the discharge bedload transport rate grain size width depth slope and river bed elevation at every point in the drainage basin when the downstream fining law is calibrated using data from central pennsylvania dowstream hydraulic geometry exponents for the width and depth are accurately reproduced longitudinal profiles calculated from the model fit observed profiles in largerwatersheds but are inaccurate in smaller watersheds the model also reproduces hack s 1957 empirical result relating slope to the 0 6 power of a ds where a is the drainage basin area and ds is the mean grain size unfortunately the model requires an equilibrium time scale which is unreasonably long suggesting that the channels of the study area are best described as systems with multiple time scales and multiple rates of response the model probably is successful because the width and depth have relatively short relaxation times and also because downstream trends in discharge and sediment transport rate are controlled by network topology thus downstream hydraulic geometry equations do not necessarily provide strong evidence for the equilibrium of fluvial landscapes rather they reflect the constancy of network topology and the rapid response times of width and depth

downstream effects of flaming gorge reservoir on the green river colorado and utah the green river is one of the principal tributaries in the colorado river basin and drains 44 700 m 2 in wyoming colorado and utah since october 1962 flows of the green river have been regulated by flaming gorge reservoir which is located 412 river miles upstream from its confluence with the colorado river mean annual runoff has not been affected by the reservoir the duration of the relatively large discharges that transport most of the annual sediment load however has decreased significantly as a result the mean annual sediment discharge has decreased by 54 to 3 21 10 6 tons from 6 92 10 6 tons at the jensen gage located 105 river miles downstream from the reservoir and by 48 to 8 83 10 6 tons from 17 0 10 6 tons at the green river utah gage located 290 river miles downstream from the reservoir sediment supply to i he channel equals the annual transport within a relatively short distance 68 river miles downstream from the reservoir downstream from river mile 166 the supply of sediment from upstream plus tributary inflow exceeds the transport of sediment by 5 4 10 6 tons per year on an average the quasi equilibrium that appears to have existed prior to the reservoir no longer occurs along a majority of the green river in response to the reduced peak discharges the bankfull channel width of the green river has decreased by 10 adjustment of the channel to decreased peak flows and altered sediment loads is nowhere complete at present it appears that a century or more will be required for the green river to adjust to the effects of flaming gorge reservoir

predicting downstream hydraulic geometry a test of rational regime theory 1 the classical equations of hydraulic geometry are purely empirical but the widespread similarity of the scaling downstream form of them suggests that they express some important underlying regularities in the morphology of stream channels through the drainage network a successful physical theory of river regime must be able to reproduce and explain this regularity in this paper we test the regime theory of eaton et al 2004 using selected data of hydraulic geometry we first use data from environments in which bank strength presumably does not vary greatly such as in anabranched channel systems and deltas regime models parameterized by assuming uniform relative bank strength plausibly describe the observed bankfull channel geometries in these systems we then test a modified bank strength formulation for vegetated gravel bed rivers against downstream hydraulic geometry data sets in which relative bank strength is supposed to vary with channel scale assuming a uniform effective cohesion due to riparian vegetation the regime model is again able to reproduce details of the channel geometry both analyses show that the classical hydraulic geometry represents only an approximation of the variation of channel form if we have confidence in the theory we may infer information about bank strength and bed material transport the pattern of variation in these quantities as well as discharge through the drainage system lends approximate regularity to stream channel scaling that is summarized in the empirical relations

re os dating of low level highly radiogenic llhr sulfides the harnas gold deposit southwest sweden records continental scale tectonic events to obtain geologically meaningful and precise results on low level sulfides that are highly radiogenic blank corrections that account for the extreme difference in the os isotope composition of sample and blank are necessary and the resulting data is best plotted in 187 re 187 os space much like the approach used for molybdenites we here introduce the acronym llhr as a means of characterizing low level and highly radiogenic sulfides use of the traditional 187 re 188 os vs 187 os 188 os plot for llhr sulfides leads to large analytical uncertainties and highly correlated errors as 188 os is poorly determined and can generally be accounted for by the blank we now recognize that llhr sulfides such as those encountered at the harnas au deposit are a common occurrence and characteristic of many crustally affiliated ore systems the harnas au deposit in southwest sweden is located in the mjosa vanern mineral belt that transects from northwest to southeast the prominent geologic fabric of the sveconorwegian province including the mylonite zone the deposit is hosted in a strongly sheared and locally brecciated sulfide bearing quartz vein that crosscuts the foliation of orthogneisses belonging to the 1600 maa mal granitoid suite a 187 re 187 os isochron of 973 34 ma 2 for samples of pyrite and chalcopyrite from outcrops of the harnas alma and silvergruvan veins was obtained the harnas and subsidiary alma veins are au bearing whereas the silvergruvan 2 5 km to the southeast is not of the au bearing type four replicate analyses of an additional pyrite sample from the harnas vein yield a model age of 616 40 ma 95 c l in all samples re and 187 os concentrations are extremely low 0 35 to 7 1 and 0 005 to 0 074 ppb respectively and total common os 0 002 0 028 ppb is less than half the calculated radiogenic 187 os two samples of galena from the harnas vein yielded blank level re and os neither the 973 nor 616 ma time of mineralization is related to development of the mylonite zone at 920 ma or intrusion of the anorogenic bohus blomskog granites at 920 to 900 ma previously proposed sources for generating mjosa vanern mineral belt ore fluids an age of 973 ma for harnas alma silvergruvan suggests that sulfide deposition was associated with the waning stages 0 97 0 90 ga of the sveconorwegian grenvillian orogeny 1 15 0 90 ga postdating metamorphism and deformation that produced a regionally overthickened crust in the northern part of the sveconorwegian province the vein systems for these and numerous other small deposits in the mjosa vanern mineral belt could have resulted from regional exhumation in the late sveconorwegian with associated extension and the development of fracture systems at cooler middle to upper crustal levels in the southern part of the sveconorwegian province dominated by granulitic facies rocks no mineralization is present perhaps due only to increased exhumation and erosion that has exposed deeper crustal levels the late sveconorwegian age 973 ma records the main period of sulfide deposition for the harnas alma silvergruvan vein systems and indicates the robustness of the chronometer within tectonically complex terranes the late neoproterozoic age 616 ma records a later time of pyrite deposition probably associated with shearing and reopening of the harnas vein system because the au mineralization at harnas has been described as associated with shearing and occurring in fracture fillings in early pyrite we suggest that part or all of the au mineralization could have been introduced at 616 ma during reactivation of the vein system the 616 ma age for pyrite suggests a previously unrecognized and much younger mineralizing episode in the harnas region most likely reflecting continental scale extension and the late neoproterozoic opening of the iapetus ocean

characterizing the transient geomorphic response to base level fall in the northeastern tibetan plateau analysis of hillslope gradient landscape relief and channel steepness in the daxia river basin provides evidence of a transient geomorphic response to base level fall on the northeastern tibetan plateau low gradient channels and gentle hillslopes of the upper watershed are separated from a steeper high relief landscape by a series of convex knickzones along channel longitudinal profiles downstream projection of the relict portions of the profiles implies 800 850 m of incision consistent with geologic and geomorphic records of post 1 7 ma incision in the lower watershed we combine optically stimulated luminescence dating of fluvial terrace deposits to constrain incision rates downstream of knickpoints with catchment averaged 10be concentrations in modern sediment to estimate erosion rates in tributary basins both above and below knickpoints both sources of data imply landscape lowering rates of 300 m ma 1 below the knickpoint and 50 100 m ma 1 above field measurements of channel width n 48 and calculations of bankfull discharge n 9 allow determination of scaling relations among channel hydraulic geometry discharge and contributing area that we employ to estimate the patterns of basal shear stress unit stream power and bed load transport rate throughout the channel network our results imply a clear downstream increase of incision potential this result would appear to be consistent with a detachment limited response to imposed base level fall in which steepening of channels drives an increase in erosion rates in contrast however we do not observe apparent narrowing of channels across the transition from slowly eroding to rapidly eroding portions of the watershed rather the present day channel morphology as well as its scaling of hydraulic geometry imply that the river is primarily adjusted to transport its sediment load and suggest that channel morphology may not always reflect the presence of knickpoints and differences in landscape relief

morphologically based model of bed load transport capacity in a headwater stream 1 field measurements of channel and bed material properties are used to develop a network based model of bed load transport capacity in halfmoon creek a high gradient stream in the rocky mountains of colorado the formerly glaciated watershed contains self formed reaches that are generally disconnected from hillslopes and major sediment perturbations strung together by a sequence of bedrock and cascade channels measurements of channel geometry slope and bed sediment texture surface and substrate were taken in 27 reaches with gradients ranging from 0 6 to 6 to examine interactions among key variables affecting bed load transport the analysis shows that the grain size distribution of the substrate is relatively uniform throughout the basin however the distinction between surface and substrate texture varies systematically with channel gradient and shear stress reaches with high shear stress are characterized by coarse surface layers with a high threshold for transport limiting the mobility of the sediment supplied in reaches with lower gradient and shear stress the difference between surface and substrate texture is less increasing both the frequency of transport and the mobility of the bed load while it might appear that the steeper reaches of halfmoon creek have a high capacity for carrying fine medium gravel the relative mobility of these sizes is affected by the presence of very coarse sediment on the bed surface as a result modeled estimates of bed load transport rate indicate that average annual bed load sediment yields increase downstream nearly linearly with discharge suggesting a simple scaling of bed load transport capacity with discharge and drainage area

stable width and depth of straight gravel rivers with heterogeneous bed materials mathematical model for defining stable width and depth of straight gravel rivers is presented in which it is revealed that the major agency for maintaining stable channel is lateral diffusion of longitudinal fluid momentum due to turbulence the primary quantities which determine the stable channel geometry are found to be flow discharge longitudinal free surface slope the median size of bed material and gradation of the bed material increasing gradation is found to increase the depth and decrease the width introduction of one loose and the other rigid bank in laboratory experiments provides good examples to test the model in which four kinds of sand were used to test the gradation effect these laboratory data support the mathematical model presented herein the theory also performs well when it is applied to natural gravel rivers

width adjustment in experimental gravel bed channels in response to overbank flows 1 we conducted a series of flume experiments to investigate the response of self formed gravel bed channels to floods of varying magnitude and duration floods were generated by increasing the discharge into a channel created in sand and gravel sized sediment with a median grain size of 2 mm flooding increased the shields stress along the channel perimeter causing bank erosion and rapid channel widening the sediment introduced to the channel by bank erosion was not necessarily deposited on the channel bed but was rather transported downstream a process likely facilitated by transient fining of the bed surface at the end of each experiment bank sediments were no longer in motion partial bed load transport characterized the flat bed portion of the channel and the shields stress approached a constant value of 0 056 about 1 2 times the critical shields stress for incipient motion furthermore the discharge was entirely accommodated by flow within the channel the creation of a stable channel entirely eliminated overbank flows we speculate that similar processes may occur in nature but only where bank sediments are non cohesive and where channel narrowing processes cannot counteract bank erosion during overbank flows we also demonstrate that a simple model of lateral bed load transport can reproduce observed channel widening rates suggesting that simple methods may be appropriate for predicting width increases in channels with non cohesive unvegetated banks even during overbank flows last we present a model for predicting the equilibrium width and depth of a stable gravel bed channel with a known channel forming shields stress

lithologic and hydrologic controls of mixed alluvial bedrock channels in flood prone fluvial systems bankfull and macrochannels in the llano river watershed central texas usa abstract the rural and unregulated llano river watershed located in central texas usa has a highly variable flow regime and a wide range of instantaneous peak flows abrupt transitions in surface lithology exist along the main stem channel course both of these characteristics afford an opportunity to examine hydrologic lithologic and sedimentary controls on downstream changes in channel morphology field surveys of channel topography and boundary composition are coupled with sediment analyses hydraulic computations flood frequency analyses and geographic information system mapping to discern controls on channel geometry profile pattern and shape and dimensions along the mixed alluvial bedrock llano river and key tributaries four categories of channel classification in a downstream direction include i uppermost ephemeral reaches ii straight or sinuous gravel bed channels in cretaceous carbonate sedimentary zones iii straight or sinuous gravel bed or bedrock channels in paleozoic sedimentary zones and iv straight braided or multithread mixed alluvial bedrock channels with sandy beds in precambrian igneous and metamorphic zones principal findings include i a nearly linear channel profile attributed to resistant bedrock incision checkpoints ii statistically significant correlations of both alluvial sinuosity and valley confinement to relatively high f mean depth hydraulic geometry values iii relatively high b width hydraulic geometry values in partly confined settings with sinuous channels upstream from a prominent incision checkpoint iv different functional flow categories including frequently occurring events

riffle pool maintenance and flow convergence routing observed on a large gravel bed river abstract geomorphologists have studied and debated over the processes responsible for natural riffle pool maintenance for decades most studies have focused on small wadable rivers but they lack much description of overbank flood conditions or a spatially explicit characterization of morphodynamics in this study 1 m horizontal resolution digital elevation models were collected from a riffle pool run sequence before and after an overbank flood with a 7 7 year recurrence interval on the relatively large gravel bed lower yuba river california digital elevation model differencing was used to quantify the magnitude and pattern of flood induced morphodynamic change cross section based analysis and two dimensional hydrodynamic modeling of flows ranging from 0 147 to 7 63 times bankful discharge were completed to evaluate the hydraulic mechanisms responsible for the observed topographic changes one key finding was that riffle pool relief increased by 0 42 m confirming the occurrence of natural hydrogeomorphic maintenance spatially complex patterns of scour and deposition exceeding 0 15 m at the scale of subwidth morphological units were reasonably predicted by the two dimensional mechanistic model that accounts for convective acceleration the one dimensional cross section based method underperformed the two dimensional model significantly consequently multiple scales of channel non uniformity and a dynamic flow regime caused the observed maintenance of the pool riffle morphology through the mechanism of flow convergence routing proposed by macwilliams et al macwilliams m l wheaton j m pasternack g b kitanidis p k street r l 2006 the flow convergence routing hypothesis for riffle pool maintenance in alluvial rivers water resources research 42 w10427 doi 10 1029 2005wr004391

deciphering caledonian events timing and geochemistry of the caledonian magmatic arc in the kyrgyz tien shan abstract in the kyrgyz tien shan also known as tian shan in literature the caledonian cambro silurian intrusions comprise an extensive magmatic arc stretching from east to west for more than 1000 km the characteristic feature of the arc is its relatively homogeneous composition of rock types over the whole structure the kichy naryn and djetim intrusions presented in this study are slightly elongated in an east west direction and occupy an area of ca 100 km2 the main rock types are diorite granodiorite and granite geological and geochemical features of the kichy naryn and djetim intrusions demonstrate characteristics of i type granite series rocks of the two intrusions define a continuous high k calc alkaline series diorite and granite of the kichy naryn intrusion yielded early silurian crystallisation ages of 436 2 ma u pb zircon diorite from pebbles in the conglomerate sampled close to the contact of the kichy naryn intrusion yielded a significantly older early ordovician crystallisation age of 466 10 ma the obtained ages of 466 and 436 ma match ages of two major regional magmatic pulses at ca 435 440 and 460 470 ma which took place during continuous subduction from the cambrian to the silurian the amount of granites in the northern tien shan their prolonged history of formation and pronounced i type geochemical characteristics suggest their formation in an andean type active margin environment

influence of the onion creek salt diapir on the late cenozoic history of fisher valley southeastern utah the upper cenozoic deposits in fisher valley utah record a long history of deposition deformation and geomorphic changes related to movement of the onion creek salt diapir apparently several pulses of salt flowed into the diapir between about 2 3 and 0 25 m y ago and the diapir may still be active fisher creek once headed in the igneous rocks of the la sal mountains and flowed along the present course of onion creek to the colorado river the rising salt diapir impeded the flow of ancestral fisher creek causing deposition of more than 125 m of basin fill sediments and eventually diverted the creek down cottonwood graben to the dolores river about 0 25 m y ago onion creek has eroded headward from the colorado river through both the diapir and the basin fill sediments and is about to capture fisher creek restoring the original drainage course

persistence of the surface texture of a gravel bed river during a large flood we present herein clear field evidence for the persistence of a coarse surface layer in a gravel bed river during flows capable of transporting all grain sizes present on the channel bed detailed field measurements of channel topography and bed surface grain size were made in a gravel bed reach of the colorado river prior to a flood in 2003 runoff produced during the 2003 snowmelt was far above average resulting in a sustained period of high flow with a peak discharge of 27 m3 s 170 of normal peak flow all available grain sizes within the study reach were mobilized in this period of time during the 2003 peak flow the river avulsed immediately upstream of the study reach thereby abandoning approximately one half kilometer of the former channel the abandonment was rapid probably within a few hours leaving the bed texture essentially frozen in place at the peak of the flood all locations sampled prior to the flood were resampled following the stream abandonment in response to the high flow the surface median grain size d50s coarsened slightly in the outer part of the bend while remaining nearly constant along the inner part of the bend resulting in an overall increase from 18 to 21 mm for the study reach thus the coarse bed surface texture persisted despite shear stresses throughout the bend that were well above the critical entrainment value this may be explained because the response of the bed texture to increases in flow strength depends primarily upon the continued availability of the various grain size percentiles in the supply which in this case was essentially unlimited for all sizes present in the channel copyright 2007 john wiley sons ltd

geomorphology and endangered fish habitats of the upper colorado river 2 linking sediment transport to habitat maintenance alluvial reaches of the colorado river near grand junction colorado provide important habitat for the endangered colorado squawfish this paper examines recent changes in the geomorphology of the colorado river and addresses the question of what can be done to improve existing fish habitats observations of channel change during periods of above average runoff from 1993 through 1995 indicate minor scour and fill of the main channel but more significant scour and enlargement of side channel and backwater habitats and flushing of fine sediment from the bed modeled relations between discharge and dimensionless shear stress indicate that the threshold of bed load transport 0 03 occurs at about half the bank full discharge these flows are exceeded about 26 days per year on average the bank full discharge produces an average of 0 047 and is exceeded about 8 days per year the width and depth of the channel thus appear to be set by a discharge that produces an average boundary shear stress of 1 5 times greater than the critical shear stress the effective discharge is slightly less than the bank full discharge and approximately 80 of the total sediment load is carried by the highest 10 of all discharges

downstream channel adjustment in a low relief glacially conditioned watershed abstract river management practices are often informed by theoretical expectations of downstream channel adjustment which may not be valid in low relief glacially conditioned watersheds such as those in the lower north american great lakes region downstream trends in channel morphology and bed material size within a low relief glacially conditioned watershed are explored here and compared to a theoretical watershed model where slope and grain size are expected to decline exponentially the observed channel morphology is then tested against a theoretical concept of reach scale channel grade the downstream hydraulic geometry relations w bf q bf 0 51 s 0 02 and d bf q bf 0 32 s 0 21 were found to best describe downstream changes in channel morphology and are consistent with some prior studies bed material size varies irregularly down the channel slope controlled downstream fining trends are evident where inputs from glacial materials and tributaries are negligible but are masked by cobble boulder lag deposits where the channel is cut into these glacial deposits the asynchronous variability in slope and grain size produces downstream variations in graded and nongraded understeepened conditions separated at ex 0 graded reaches exist where ex 0 but an upper boundary with nongraded oversteepened reaches is less clear the results emphasize the geomorphic legacy of inherited slopes and sediment sources in dictating the modern downstream patterns of fluvial characteristics and morphologies in glacially conditioned and similarly complex watersheds

longitudinal profiles in simple alluvial systems theoretical considerations suggest that exponential or quadratic functions are apt for describing the longitudinal profiles of aggrading alluvial systems that are unaffected by significant lateral inputs of water or sediment a new set of field data confirms this for individual sedimentary links along a wandering gravel bed river in british columbia canada each link is viewed as a simple alluvial system without major water or sediment inputs within which grain size typically fines downstream in a relatively systematic manner such homogeneous reaches are suitable for the investigation of simple profile form it is found that quadratic approximations are the most flexible descriptor for link longitudinal profiles overall the river forms an irregularly cuspate long profile structured by these fundamental length scale units both link gradients and link fining rate reflect size selective aggradation associated with the bounding lateral inputs

revision of the late middle pleistocene stratigraphy and palaeoclimate in poland abstract the aim of this paper is a critical verification of the late middle pleistocene stratigraphy in poland in connection with stratigraphical schemes in the neighbouring countries although a terrestrial record of the middle pleistocene is almost complete in western and southern europe it is full of gaps in central and eastern europe eight key sites in poland and one in belarus were selected to compile environmental and palaeoclimate data for a revised stratigraphy from the termination of mis 12 to mis 6 and the chronology was based on correlation with oxygen isotope stratigraphy and osl ages the late middle pleistocene record starts with the holsteinian lake sequences some of which have been initiated already at the end of mis 12 persisted through mis 11 and terminated in mid mis 10 in the examined sites mis 11 is represented also by deposits of meandering rivers in a temperate climate in contrast there is no evidence for deposition in most of mis 10 and in mis 9 a warmer and presumably wet episode at the beginning of mis 8 lead to local erosion followed by development of small lakes modest ice sheet advance into central europe occurred in the second part of mis 8 as reflected by a till glaciofluvial and glaciolacustrine deposits and presumably also by permafrost and ice wedges in western belarus mis 7 seems to have been generally warm and wet when small lakes and meandering rivers could develop such mild conditions were interrupted with cool and probably drier episodes when braided rivers and limited pedogenesis occurred saalian ice sheet cover of central europe in mis 6 was widespread but even more importantly in this stage periglacial environments were dominant as shown by continuous permafrost intensive aeolian activity and development of ice wedges and involutions braided rivers developed during short wetter intervals

assessing the effect of vegetation related bank strength on channel morphology and stability in gravel bed streams using numerical models bank strength due to vegetation dominates the geometry of small stream channels but has virtually no effect on the geometry of larger ones the dependence of bank strength on channel scale affects the form of downstream hydraulic geometry relations and the meandering braiding threshold it is also associated with a lateral migration threshold discharge below which channels do not migrate appreciably across their floodplains a rational regime model is used to explore these scale effects it parameterizes vegetation related bank strength using a dimensionless effective cohesion cr the scale effects are explored primarily using an alluvial state space defined by the dimensionless formative discharge q and channel slope s which is analogous to the q s diagrams originally used to explore meandering braiding thresholds the analyses show that the effect of vegetation on both downstream hydraulic geometry and the meandering braiding threshold is strongest for the smallest streams in a watershed but that the effect disappears for q 106 the analysis of the migration threshold suggests that the critical discharge ranges from about 5 m3 s to 50 m3 s depending on the characteristic rooting depth for the vegetation the analysis also suggests that where fires frequently affect riparian forests channels may alternate between laterally stable gravel plane bed channels and laterally active riffle pool channels these channels likely do not exhibit the classic dynamic equilibrium associated with alluvial streams but instead exhibit a cyclical morphologic evolution oscillating between laterally stable and laterally unstable end members with a frequency determined by the forest fire recurrence interval copyright 2008 john wiley sons ltd

channel narrowing by vertical accretion along the green river near green river utah the green river is the longest tributary of the colorado river near the town of green river utah the green river narrowed in two discrete phases during the twentieth century the first phase of narrowing decreased average width by about 5 and occurred between about 1930 and 1940 when the magnitude of 2 yr flood mean annual discharge and effective discharge decreased by about 30 28 and 37 respectively during this first phase of narrowing saltcedar tamarisk spp an invading non native tree began to establish itself in the study area but botanists of that time did not describe the tree as abundant channel width was stable in the 1940s and 1950s even though saltcedar were becoming already abundant on the river9s banks further narrowing of an additional 14 occurred after 1959 this latest period of narrowing began following three successive years when the magnitude of floods was less than the present 1 5 yr recurrence flood and when saltcedar were already abundant along the river the deposits that comprise the banks of the narrowing green river are composed of the suspended load of the river and these alluvial deposits are characterized by horizontal layers which indicate that they formed by vertical accretion a mechanism is proposed to explain the coarsening upward sequence of beds found in these vertically accreted deposits these changes in the channel of the green river are based on analysis of more than 2600 discharge measurements made by the u s geological survey resurvey of an abandoned measurement site matches of historical ground level photography and analysis of historical aerial photography within a geographic information system we have developed analytical techniques that permit analysis of width data from u s geological survey discharge measurements where gaging cross sections have adjustable beds and banks these techniques allow the spatially rich but temporally poor data from aerial photographs to be supplemented with gaging station data which add great detail about the timing and actual processes of channel narrowing that cannot be determined from aerial photographs alone such an analytical strategy provides a more complete record of historical channel adjustment than can be obtained by other means

re os pyrite and u pb zircon geochronology from the taldybulak levoberezhny gold deposit insight for cambrian metallogeny of the kyrgyz northern tien shan abstract the taldybulak levoberezhny gold deposit located in the eastern part of the kyrgyz northern tien shan is hosted in highly deformed precambrian schist and gneisses that have undergone intense quartz carbonate fuchsite and tourmaline alterations gold mineralization is ultimately subdivided into two stages based on the observation of alteration assemblages orebody geometries and the occurrences of au bearing minerals negative thermal ionization mass spectrometry re os isotopic analyses of five au rich pyrite samples from the early stage yielded an isochron age of 511 18 ma zircon sensitive high resolution ion microprobe u pb dating of a diorite dike sample postdating the late stage mineralization yielded a wide range of ages from 3055 to 291 ma while a weighted mean 206 pb 238 u age of 414 6 6 8 ma is believed to represent the age of dike intrusion and the upper limit on the timing of the late stage quartz tourmaline gold formation the pyrite 187 os 188 os initial ratio of 0 132 0 011 together with os values varying from 0 to 14 indicate a major mantle component for the source of os and by inference ore metals which may be linked to the ophiolite suite of the kopurelisai complex in the taldybulak levoberezhny area considering the geodynamic setting of the kyrgyz northern tien shan during the early paleozoic we suggest that cambrian mineralization of the taldybulak levoberezhny deposit can be attributed to a subduction related setting probably associated with the earliest accretion of the northern tien shan

slope induced changes in channel character along a gravel bed stream the allt dubhaig scotland changes in channel character along a small river in the scottish highlands are described using measurements in seven reaches over a 3 km length with no significant tributaries but a decline in slope from 0 02 to o ooo15 because of local baselevel control this decline in slope is associated with rapid downstream fining of the gravel bed followed by an abrupt transition to a sand bed the channel pattern alters progressively rather than abruptly in the sequence 1 near braided 2 meandering with active point bar chutes 3 meandering with active outer bank talweg 4 stable equiwidth sinuous the changes in channel pattern and hydraulic geometry are predicted better by rational approaches based on critical shear stress or other physical cdncepts than by purely empirical discriminant or trend equations measurements in five reaches confirm a downstream decrease in shear stress and the amount and calibre of bedload it is argued that the downstream changes in channel character in this stream are induced by profile concavity inherited from deglacial conditions are typical of many streams in mountainous areas and can be understood in terms of slope induced changes in hydraulic properties

the nature and controls on downstream fining within sedimentary links abstract at scales of 100 to 102 km grain size change in gravelly alluvial systems is characterized by punctuated downstream fining significant lateral sediment inputs define a sequence of sedimentary links within which fluvial processes produce fining trends using a new set of surface grain size data eighteen such links along two canadian gravel bed rivers are examined negative exponential functions are found to be most appropriate for describing within link grain size changes development of a pragmatic means of predicting grain size is then pursued by searching for a means to relate model diminution coefficients to link attributes consideration of lithologically differentiated fining trends indicates that lithology plays an insignificant role in controlling fining rate examination of within link longitudinal profiles indicates a reasonable relation between fining rate and the rate of change of channel slope the predictive value of this relation is limited by the regional nature of the data upon which it is based and the relative difficulty of obtaining accurate gradient information however as previously noted for alluvial fans although for different reasons channel gradient is correlated with link length and a reasonable predictive tool is apparent in a relation between link length and diminution rate the validity of the derived relation cannot be tested for want of a suitable data set several lines of evidence indicate that abrasion is unimportant as a fining mechanism on these rivers and it is argued that this may be typical of sedimentary links fining rate must then be a function of the efficiency with which sorting processes operate and it is suggested that this efficiency is dependent on aggradation rates associated with the lateral sediment influxes at the head and terminus of individual links

re os dating of sulfides associated with gold mineralization in central victoria australia we report re os isotope ages that are the first for sulfides closely associated with gold mineralization at the bendigo and maldon goldfields in central victoria two arsenopyrite samples from bendigo contain 11 ppb re and 0 08 ppb highly radiogenic os llhr samples stein et al 2000 and have model ages of 444 7 and 447 7 ma with a mean model age of 446 5 ma a five point isochron based on these arsenopyrite analyses plus three pyrite analyses including one replicate gives an age of 438 6 ma molybdenite associated with au te cu and sb mineralization at maldon gives an re os age of 376 2 ma similar to the age of the nearby har court granite these results support previous 40 ar 39 ar data indicating that initial emplacement of gold mineralization in central victoria occurred in the late ordovician during the earliest stages of accretionary development of the southern lachlan fold belt the molybdenite data are also consistent with the mobilization and or introduction of gold during late devonian magmatism

middle upper quaternary stratigraphy in the northeast of european russia inferred from rodent record and lithology of tills abstract we present the revision of materials on quaternary rodent biostratigraphy collared lemming dicrostonyx and narrow headed vole lasiopodomys gregalis in the northeast of european russia testing the biostratigraphic method with lithological and palynological data petrographic composition of clastic material and orientation of clasts in tills are regionally stable lithostratigraphic criteria pechora dnieper moraine is characteristic for clast axes oriented in the sector 340 60 clasts in vychegda moscow till show orientation of 270 360 which in combination with the petrographic composition of erratic material indicates the origin of moraines from different source glacial provinces certain differences were also found in the associations of heavy minerals a specific trait of the upper neopleistocene polar till is the presence of erratic crinoid bryozoan limestones from novaya zemlya connection of this till with the pay khoy novaya zemlya ice center and possibly with the shelves of the barents and kara seas is also confirmed by the orientation of clasts from north northeast to south southwest middle neopleistocene rodent remains are found between the pechora and vychegda moraines by the ratio of m1 and m2 morphotypes all middle neopliestocene assemblages are divided into three groups representing morphs d simplicior morph 2 gavrilovka bolshaya sluda akis laya 4 d simplicior morph 3 sercheyu 1 laya 3 and d ex gr simplicior gulielmi shapkina 4 chuley the lower horizon of kipievo these evolutionary levels respectively correspond to late pechora dnieper mis 8 rodionovo shklov mis 7 and early vychegda moscow mis 6 intervals biochronological criteria for late quaternary based on evolutionary level of teeth of collared lemming and narrow headed vole are suggested it has been revealed that the early valdai mis 5d a 4 is characterized by the morph 2 d gulielmi as well as the high about 50 proportion of the gregaloid morphotype among the first lower molars of l gregalis lemmings of morphs 2 and 3 d gulielmi lived during the middle valdai mis 3 and animal of morphs 3 d gulielmi and d ex gr gulielmi torquatus existed during the last glacial maximum lemmings at the levels of d gulielmi morph 3 d ex gr gulielmi torquatus d torquatus morphs 1 and 2 were typical for lateglacial morphs 1 and 2 d torquatus for the early holocene morph 3 d torquatus for the late holocene and recent times small less than 25 proportion of the gegaloid morphotype is characteristic of m1 of middle and late valdai and modern narrow headed voles

the fossil mammal fauna from the upper depositional unit of the logovo gyieny hyena s den cave northwestern altai russia abstract the paper presents a study of the fossil microfauna from the logovo gieny cave northwestern altai russia the microfauna with 30 identified species comes from six layers of the upper unit of the cave s central hall that was excavated in summer 2008 selected for the morphotype analyses three species alticola strelzowi lasiopodomys stenocranius gregalis and microtus oeconomus showed that their parameters layer 6 2 correspond with those found in the late pleistocene site of altai region new data did not demonstrate any abrupt successions of the mammal communities and contained similar species in all the layers indicative of the steppe environments however the faunal assemblages revealed different climatic conditions which combined with previously known radiocarbon dates were aligned with the gs3 mis 2 and gs 6 7 mis 3 phases of the greenland ice core records

multi stage gold mineralization in the taldybulak levoberezhny deposit tien shan kyrgyzstan reply to comment by boris trifonov on re os pyrite and u pb zircon geochronology from the taldybulak levoberezhny gold deposit insight for cambrian metallogeny of the kyrgyz northern tien shan abstract our recent geochronological study on the taldybulak levoberezhny gold deposit in kyrgyz northern tien shan knts received critical comments by boris trifonov 2016 regarding the age of dikes and its relationship with gold mineralization at the deposit in this contribution based on a re evaluation of our published data together with new geochronological geochemical and sr nd hf isotopic data the age of gold mineralization magmatic and tectonic events and the relationship between dikes and mineralization at the deposit it is proposed that the taldybulak levoberezhny gold deposit is a product of long lived magmatic hydrothermal system with multiple stages of gold mineralization from cambrian to late carboniferous early permian

variation in the reference shields stress for bed load transport in gravel bed streams and rivers 1 the present study examines variations in the reference shear stress for bed load transport r using coupled measurements of flow and bed load transport in 45 gravel bed streams and rivers the study streams encompass a wide range in bank full discharge 1 2600 m3 s average channel gradient 0 0003 0 05 and median surface grain size 0 027 0 21 m a bed load transport relation was formed for each site by plotting individual values of the dimensionless transport rate w versus the reach average dimensionless shear stress the reference dimensionless shear stress r was then estimated by selecting the value of corresponding to a reference transport rate of w 0 002 the results indicate that the discharge corresponding to r averages 67 of the bank full discharge with the variation independent of reach scale morphologic and sediment properties however values of r increase systematically with average channel gradient ranging from 0 025 0 035 at sites with slopes of 0 001 0 006 to values greater than 0 10 at sites with slopes greater than 0 02 a corresponding relation for the bank full dimensionless shear stress bf formulated with data from 159 sites in north america and england mirrors the relation between r and channel gradient suggesting that the bank full channel geometry of gravel and cobble bedded streams is adjusted to a relatively constant excess shear stress bf r across a wide range of slopes