sequence stratigraphy of the neoproterozoic infra krol formation and krol group lesser himalaya india a bstract a sequence stratigraphic study of terrigenous and carbonate rocks of the infra krol formation and krol group in the lesser himalaya fold and thrust belt of northern india was undertaken as part of a broader investigation of the significance of carbon isotope data in neoproterozoic successions eight regional stratigraphic discontinuities were traced over a distance of nearly 300 km and interpretations were anchored in a series of local studies involving the mapping of key beds and the measurement of closely spaced sections three of the regional surfaces are interpreted as sequence boundaries on the basis of 1 locally developed incised valleys 60 m deep 2 paleokarstic depressions with 50 m of mappable relief 3 subaerial dissolution and weathering products breccias and calcrete filling vertical fissures dikes cavities and shallow de pressions in underlying carbonate rocks and 4 small scale evidence for sub aerial exposure at an erosion surface the remaining five discontinuities are regional flooding surfaces identified on the basis of either facies changes with an abrupt upward deepening across the surface or transitions in facies stacking patterns typically from forestepping to backstepping a glacio eustatic origin is permitted although not required for the three sequence boundaries but no evidence has been found for marked lowering of sea level at other horizons a mismatch between the stratigraphic location of sequence boundaries and car bon isotope minima suggests that local diagenetic alteration or oceanographic phenomena unrelated to glaciation may be in part responsible for observed isotopic variation and that small ice sheets may have existed during apparently nonglacial times without producing either cap carbonates or negative carbon isotope excursions

spatially integrated geodetic glacier mass balance and its uncertainty based on geostatistical analysis application to the western svartisen ice cap norway estimates of glacier mass balance using geodetic methods can differ significantly from estimates using direct glaciological field based measurements to determine if such differences are real or methodological there is a need to improve uncertainty estimates in both methods in this paper we focus on the uncertainty of geodetic methods and describe a geostatistical technique that takes into account the spatial correlation of the elevation differences when calculating spatially averaged elevation changes we apply this method to the western svartisen ice cap norway using elevation differences from the surrounding bedrock derived from stereophotogrammetry we show that the uncertainty is not only dependent on the standard error of the individual elevation differences but is also dependent on the size of the averaging area and the scale of the spatial correlation to assess if the geostatistical analysis made over bedrock is applicable to glacier surfaces we use concurrent photogrammetrical and laser scanning data from bedrock and a range of glacier surfaces to evaluate the dependency of the geostatistical analysis on the surface type the estimated geodetic mass balance and its uncertainty is 2 6 0 9 m w e for the period 1968 85 and 2 0 2 2 m w e for 1985 2002

a sedimentary prelude to marinoan glaciation cryogenian middle neoproterozoic keele formation mackenzie mountains northwestern canada abstract continental margin deposition between the sturtian and marinoan aged global glacial periods is represented in nw canada by a siliciclastic to carbonate grand cycle the keele formation a 300 600 m thick carbonate and siliciclastic deposit comprises the upper part of this interglacial cycle sedimentary facies in the lower carbonate dominated member of the keele span a broad spectrum of depositional environments from below storm wave base to peritidal to continental and are disposed across a relatively narrow paleogeographic belt lateral arrangement of facies and the gradual stratigraphic transitions between them suggest deposition in a ramp setting local slump structures and occasional debrites in deep water facies imply that the ramp was distally steepened fluvial facies are concentrated at a single locality indicating that terrigenous clastic sediment was derived from a point source or sources most strata of the carbonates are bahamian in character and similar to phanerozoic warm water carbonates in that they contain abundant calcite ooids of interpreted original aragonitic mineralogy and have well developed muddy peritidal facies nevertheless close juxtaposition of deep and shallow water facies in keele rocks indicates high amplitude sea level change during deposition on the order of 100 m suggesting accumulation in a climatic icehouse period this interpretation implies that although the globe possessed polar and high altitude glaciers at this time sea surface temperature at least at tropical latitudes warmed dramatically between neoproterozoic glacial episodes the onset of marinoan glaciation here is heralded by an abrupt shift to nearshore marine siliciclastic sedimentary rocks these deposits form the upper member of the keele formation informally called the keele clastic wedge and directly underlie ice brook formation diamictites carbonates are rare and are restricted to mudstones and flat pebble conglomerates that lack any indication of tropical conditions

shredding of environmental signals by sediment transport 1 landscapes respond to climate tectonic motions and sea level but this response is mediated by sediment transport understanding transmission of environmental signals is crucial for predicting landscape response to climate change and interpreting paleo climate and tectonics from stratigraphy here we propose that sediment transport can act as a nonlinear filter that completely destroys shreds environmental signals this results from ubiquitous thresholds in sediment transport systems e g landsliding bed load transport and river avulsion this morphodynamic turbulence is analogous to turbulence in fluid flows where energy injected at one frequency is smeared across a range of scales we show with a numerical model that external signals are shredded when their time and amplitude scales fall within the ranges of morphodynamic turbulence as signal frequency increases signal preservation becomes the exception rather than the rule suggesting a critical re examination of purported sedimentary signals of external forcing citation jerolmack d j and c paola 2010 shredding of environmental signals by sediment transport geophys res lett 37 l19401 doi 10 1029 2010gl044638

influence of a large debris flow fan on the late holocene evolution of squamish river southwest british columbia canada cheekye fan is a large paraglacial debris flow fan in southwest british columbia it owes its origin to the collapse of mount garibaldi a volcano that erupted in contact with glacier ice near the end of the pleistocene epoch the fan extended across howe sound isolating a freshwater lake upstream of the fan from a fjord downstream of it squamish river built a delta into this lake during the holocene we use 28 radiocarbon ages to describe the final infilling of the lake and the subsequent evolution of the squamish river floodplain over the past 3300 years these events are recorded in fine grained lacustrine wetland river channel and overbank sediments exposed in the banks of squamish river over a distance of more than 10 km upstream of the fan we link these deposits to construction persistence and eventual degradation of the dam formed by cheekye fan and a smaller inset fan formed by cheakamus river into which cheekye river flows the coupled cheekye fan squamish river floodplain system is si

six decades of glacier mass balance observations a review of the worldwide monitoring network glacier mass balance is the direct and undelayed response to atmospheric conditions and hence is among the essential variables required for climate system monitoring it has been recognized as the largest non steric contributor to the present rise in sea level six decades of annual mass balance data have been compiled and made easily available by the world glacier monitoring service and its predecessor organizations in total there have been 3480 annual mass balance measurements reported from 228 glaciers around the globe however the present dataset is strongly biased towards the northern hemisphere and europe and there are only 30 reference glaciers that have uninterrupted series going back to 1976 the available data from the six decades indicate a strong ice loss as early as the 1940s and 1950s followed by a moderate mass loss until the end of the 1970s and a subsequent acceleration that has lasted until now culminating in a mean overall ice loss of over 20 m w e for the period 1946 2006 in view of the discrepancy between the relevance of glacier mass balance data and the shortcomings of the available dataset it is strongly recommended to 1 continue the long term measurements 2 resume interrupted long term data series 3 replace vanishing glaciers by early starting replacement observations 4 extend the monitoring network to strategically important regions 5 validate calibrate and accordingly flag field measurements with geodetic methods and 6 make systematic use of remote sensing and geo informatics for assessment of the representativeness of the available data series for their entire mountain range and for the extrapolation to regions without in situ observations and 7 make all these data and related meta information available

geomorphometric assessment of spatial sediment connectivity in small alpine catchments abstract complex and rugged topography induces large variations in erosion and sediment delivery in the headwaters of alpine catchments an effective connection of hillslopes with the channel network results in highly efficient sediment transfer processes such as debris flows in contrast morphological conditions producing decoupling of hillslopes from channels e g glacial cirques may exclude large areas of the catchment from sediment delivery to its lower parts moreover an efficient connection between hillslopes and channel network does not always ensure an effective downstream transfer of sediment low slope channel reaches e g in hanging valleys cause sediment deposition which often results in changes of the sediment transport processes typically from debris flow to streamflow with low bedload and suspended load rates the availability of high resolution digital terrain models such as those derived from aerial lidar improves our capability to quantify the topographic controls on sediment connectivity a geomorphometric index based on the approach by borselli et al 2008 was developed and applied to assess spatial sediment connectivity in two small catchments of the italian alps featuring contrasting morphological characteristics the results of the geomorphometric analysis were checked against field evidences showing good performance and thus potential usefulness of the index

variability in sediment delivery and storage along river courses in bega catchment nsw australia implications for geomorphic river recovery in many catchments in southeastern australia alluvial stores have been the dominant source of sediments mobilised in the period since european settlement in bega catchment on the south coast of new south wales nsw this has been reflected by dramatic changes to river morphology extensive volumes of material have been released and efficiently flushed to the lowland plain with a sediment delivery ratio of almost 70 however only 16 of these alluvial sediments have been flushed through to the estuary as antecedent controls on valley width have resulted in the lowland plain acting as a large sediment sink the changing nature of sediment source transfer and accumulation zones has varied markedly from subcatchment to subcatchment the volume of material supplied to the lowland plain from differing subcatchments is not related to subcatchment area rather the pattern of river types dictates the spatial variability in storage and transfer over 67 of sediment released has been sourced from just 25 of the catchment from subcatchments characterised by large valley fills cut and fill river style that previously stored extensive volumes of material at the base of the escarpment these parts of bega catchment were especially sensitive to disturbance sediment exhaustion from these parts of the catchment and from river courses elsewhere has major implications for the geomorphic recovery potential of rivers constraining what can be realistically achieved in terms of river rehabilitation

preliminary mineralogical investigation of leicestershire low rank coal abstract a preliminary mineralogical geochemical investigation of low rank coals from leicestershire england has been carried out with a view to their future beneficiation analytical scanning electron microscopy sem and x ray powder diffraction xrd have been used to identify and assess the distribution of mineral phases likely to give corrosion producing or slag forming materials during combustion and those minerals which would be potentially valuable by products of beneficiation processes differences in the mineral petrography of borehole samples from the vale of belvoir prospect and coal from bagworth colliery are compared samples from both areas contain substantial amounts of epigenetic minerals calcite dolomite kaolinite and fluor apatite are important phases in the bagworth sample whilst gypsum illite quartz kaolinite barytocelestine pyrite chalcopyrite anatase galena and sphalerite occur in the vale of belvoir samples whereas the presence of halides in the bagworth coal would seem to be a possible source of boiler corrosion problems the major undesirable characteristic of the vale of belvoir coal is the presence of significant amounts of metal sulphides however extraction of sulphides from this coal prior to combustion could provide a valuable source of metals as a by product certain trace element concentrations in the vale of belvoir samples have also been determined by instrumental neutron activation analysis inaa and higher levels of lanthanide elements are present in the whole coal relative to mineral veins mainly gypsum trace element signatures may provide a useful distinction between syngenetic and epigenetic mineral formation

precambrian paleosols in canada although at least 38 precambrian paleosols have been reported in canada few have received the attention afforded most other geological phenomena the most intensively studied of these are widely distributed early proterozoic paleosols associated with the sub huronian and matonabbee new name unconformities criteria that have been most useful in identifying precambrian paleosols in canada include macrostructures ascending protolith disruption saprolith and corestones micromorphology sepic texture and peds mineralogical changes dissolution transformation geochemical signatures ascending depletion of some elements characteristic weathering indices and distinctive colour contrast diagenetic mechanical and geochemical overprinting of the paleosols evident in many canadian examples includes paleosol compaction veins cutting pedogenic features and widespread alkali and alkaline earth element metasomatism metamorphism and deformation also tend to mask pedogenic features as attested by th

storage filters upland suspended sediment signals delivered from watersheds climate change tectonics and humans create long and short term temporal variations in the supply of suspended sediment to rivers these signals generated in upland erosional areas are filtered by alluvial storage before reaching the basin outlet we quantified this filter using a random walk model driven by sediment budget data a power law distributed probability density function pdf to determine how long sediment remains stored and a constant downstream drift velocity during transport of 157 km yr for 25 km of transport few particles are stored and the median travel time is 0 2 yr for 1000 km of transport nearly all particles are stored and the median travel time is 2 5 m y both travel time distributions are power laws the 1000 km travel time distribution was then used to filter sinusoidal input signals with periods of 10 yr and 10 4 yr the 10 yr signal is delayed by 12 5 times its input period damped by a factor of 380 and is output as a power law the 10 4 yr signal is delayed by 0 15 times its input period damped by a factor of 3 and the output signal retains its sinusoidal input form but with a power law tail delivery time scales for these two signals are controlled by storage in channel transport time is insignificant and low frequency signals are transmitted with greater fidelity than high frequency signals these signal modifications are essential to consider when evaluating watershed restoration schemes designed to control sediment loading and where source area geomorphic processes are inferred from the geologic record

searching for travertines calcretes and speleothems in deep time processes appearances predictions and the impact of plants common models for modern calcite precipitation in and around caves soils springs and streams involve co 2 supplied by thick high p co 2 biogenic soils which were probably thin or non existent before vascular plants indeed plant influenced chemical weathering might have caused accelerated terrestrial carbonate production from the devonian onwards however terrestrial carbonates have also been documented from the archaean proterozoic cambrian ordovician and silurian mechanisms which could have caused non marine carbonates to precipitate without organic rich soils are described and some geological events likely to have influenced non marine carbonate precipitation up to the origin of vascular plants are highlighted as organisms have evolved so have the petrographic characteristics of non marine carbonates some examples of this are also given here

short term geomorphological evolution of proglacial systems proglacial systems are amongst the most rapidly changing landscapes on earth as glacier mass loss permafrost degradation and more episodes of intense rainfall progress with climate change this review addresses the urgent need to quantitatively define proglacial systems not only in terms of spatial extent but also in terms of functional processes it firstly provides a critical appraisal of prevailing conceptual models of proglacial systems and uses this to justify compiling data on rates of landform change in terms of planform horizontal motion elevation changes and sediment budgets these data permit us to produce novel summary conceptual diagrams that consider proglacial landscape evolution in terms of a balance of longitudinal and lateral water and sediment fluxes throughout we give examples of newly emerging datasets and data processing methods because these have the potential to assist with the issues of i a lack of knowledge of proglacial systems within high mountain arctic and polar regions ii considerable inter and intra catchment variability in the geomorphology and functioning of proglacial systems iii problems with the magnitude of short term geomorphological changes being at the threshold of detection iv separating short term variability from longer term trends and v of the representativeness of plot scale field measurements for regionalisation and for upscaling we consider that understanding of future climate change effects on proglacial systems requires holistic process based modelling to explicitly consider feedbacks and linkages especially between hillslope and valley floor components such modelling must be informed by a new generation of repeated distributed topographic surveys to detect and quantify short term geomorphological changes

the impact of pro glacial lakes on downstream sediment delivery in norway glacier recessions caused by climate change may uncover pro glacial lakes that form important sedimentation basins regulating the downstream sediment delivery the impact of modern pro glacial lakes on fluvial sediment transport from three different norwegian glaciers nigardsbreen engabreen and tunsbergdalsbreen and their long term development has been studied all of these lakes developed in modern times in overdeepened bedrock basins the recession of nigardsbreen uncovered a 1 8 km long and on average 15 m deep pro glacial lake basin during 1937 to 1968 since then the glacier front has been situated entirely on land and the sediment input and output of the lake has been measured the suspended sediment transport into and out of the lake averaged 11 730 t yr 1 and 2340 t yr 1 respectively thus 20 remained in suspension at the outlet the measured mean annual bedload supplied to the lake was 11 800 t yr 1 giving a total transport of 23 530 t yr 1 which corresponds to a specific sediment yield of 561 t km 2 yr 1 a 1 9 km long and up to 90 m deep pro glacial lake basin downstream from engabreen glacier was uncovered during 1890 to 1944 the average suspended sediment load delivered from the glacier during the years 1970 1981 amounted to 12 375 t yr 1and the transport out of the lake was 2021 t yr 1 giving an average of 16 remaining in suspension the mean annual bedload was 8000 t yr 1 thus the total transport was 20 375 t yr 1 giving a specific sediment yield of 566 t km 2 yr 1 for tunsbergdalsbreen glacier measurements in the early 1970s indicated that the suspended sediment transport was on average 44 000 t yr 1 from 1987 to 1993 the recession of the glacier uncovered a small pro glacial lake 0 3 km long and around 9 m deep downstream from this the suspended sediment load measured in 2009 was 28 000 t yr 1 indicating that as much as 64 remained in suspension flow velocity grain size of sediment and morphology of the lake are important factors controlling the sedimentation rate in the pro glacial lakes a survey of the sub glacial morphology of tunsbergdalsbreen revealed that there are several overdeepened basins beneath the glacier the largest is 4 km long and 100 m deep when the glacier melts back they will become lakes and act as sedimentation basins despite an expected increase in sediment yield from the glacier little sediment will pass these lakes and downstream sediment delivery will be reduced markedly beneath nigardsbreen there was only a small depression that may form a lake and the sediment delivery will not be significantly affected 2014 the authors earth surface processes and landforms published by john wiley sons ltd

analysis origin and significance of mineral matter in coal an updated review abstract the material classed as mineral matter in coal embraces crystalline mineral materials as well as a range of inorganic elements that occur in non crystalline form this review outlines the methods that may be used to evaluate the percentage of mineral matter for a coal sample as opposed to the ash yield and to identify the minerals their individual percentages and their modes of occurrence within the coal the principal techniques include low temperature oxygen plasma ashing quantitative evaluation of x ray diffraction data observation using optical microscopy and a combination of observation chemical analysis and in some cases mapping based on scanning electron microscopy and related methods a range of other techniques may also be used to provide additional information on particular mineral matter components processes responsible for mineral matter formation include detrital input biogenic activity and authigenic precipitation at different stages of the coal s depositional and post depositional history differential migration of non mineral inorganic elements may also occur in lower rank coals and expulsion of non mineral inorganics may take place with rank advance knowledge of the mineral matter may be of assistance in understanding the modes of trace element occurrence with implications for assessing possible environmental impacts and also the potential for recovery of economic products from coal the behaviour of different mineral matter components at high temperatures is also discussed as well as methods for mineralogical analysis of ashes and other coal utilization products information from mineral matter studies may provide an improved basis for understanding coal formation and for evaluating the response of particular coals to different combustion gasification and coking processes

reaction and relaxation in a coarse grained fluvial system following catchment wide disturbance abstract the waiapu river catchment drainage area of 1734 km2 is one of the most prolific conveyors of sediment in the world annually delivering roughly 35 mt of fine material to the ocean from eroding gullies hillslopes and reworked sediment on valley floors tectonic and geologic influences in combination with a dynamic climate influenced by tropical cyclones and clearance of vegetation from steep hillslopes predisposes this region to high rates of erosion the bedload sediment regime of the river is strongly influenced by several exceptionally large gullies and gully complexes that produce a coarse grained poorly sorted sediment mixture rapid abrasion and breakdown leads to high rates of suspended sediment yield a wave of bedload material manifesting as elevated bed levels and significant widening of active alluvial fills has been triggered by large inputs of hillslope material from a few key tributary catchments following cyclone bola in 1988 we review the evidence for the relaxation process of the sedimentary system in the subsequent 29 years appraising some of the legacy effects that may endure as associated with reworking of the considerable alluvial stores within the waiapu system we use structure from motion sfm techniques and archival aerial photos to quantify changes in sediment storage at the base of two major gully systems in recent decades a record of over 850 cross section surveys at 62 sites on 10 rivers throughout the catchment 1958 2017 indicates recent transition from a trend of continuous accumulation to downcutting and remobilisation of valley bottom deposits the channel cross sections provide a minimum estimate of sediment flux from source areas to the lower reaches of the river giving a rudimentary but spatially extensive picture of the wave of material cascading through the drainage network the largest impacts occur in the upper steepland rivers closest to the landslide derived sediment supply transport rates here as inferred from cross section change are at a maximum during an aggradational phase following cyclone bola then taper off despite the large sediment accumulations remaining in the system as of 2017 the river is in the process of incising the upper extents of this deposit on a trajectory of recovery toward pre bola conditions the compilation of cross section data provides us with new insights into the sensitivity of particular sites in the landscape as well as the changing relationship between reach sediment storage and transport rates during the response and relaxation phase of a major disturbance in a large catchment

the sediment delivery problem abstract the linking of on site rates of erosion and soil loss within a drainage basin to the sediment yield at the basin outlet and improved knowledge and representation of the associated processes of sediment delivery represent a major research need within the field of erosion and sedimentation and also an important scale problem in drainage basin studies this paper reviews the limitations of the sediment delivery ratio concept by considering the problems of temporal and spatial lumping and its blackbox nature some recent advances in our understanding of the sediment delivery system and its modelling are described and the lack of detailed empirical investigations is highlighted the significance of recent concern for the role of sediments in the transport of nutrients and contaminants to sediment delivery studies is introduced and the need for further work in this field is emphasised

geomorphic impact and system recovery following an extreme flood in an upland stream thinhope burn northern england uk abstract quantitative assessments of the impacts of extreme floods on channel morphology are rare real time kinematic rtk gps surveys of a 500 m reach of the thinhope burn an upland gravel bed stream in the uk taken in 2003 and 2004 permitted an assessment of geomorphic work whilst the channel was at steady state a large flood that occurred on 17 july 2007 resulted in a catastrophic impact to the thinhope burn valley floor the reach was re surveyed after the event in 2007 and again in 2008 and in 2011 digital elevation models were produced from the survey data which allowed the spatial patterns of erosion and deposition and volumetric changes between surveys to be established a total of 5202 m3 of deposition and 2125 m3 of erosion was recorded in the reach following the flood event field walking of the catchment and comparison of aerial photographs for 2003 and 2007 suggested that most of the material mobilised had originated from existing sediment held in terraces and paleoberms on the valley floor although slope failures were evident including peat slides in the headwaters delivery of sediment from coupling zones to the channel was thought to play a secondary role in the geomorphic response shown by the channel similarly large volumes of erosion and deposition were found after resurveys in 2008 and 2011 suggesting that the system was still in its relaxation phase the results obtained in this investigation coupled with historical information on the flood history of thinhope burn dating back to 1766 suggested that rare large floods are the geomorphically effective flows in the catchment

pebble abrasion during fluvial transport experimental results and implications for the evolution of the sediment load along rivers 1 in actively eroding landscapes fluvial abrasion modifies the characteristics of the sediment carried by rivers and consequently has a direct impact on the ability of mountain rivers to erode their bedrock and on the characteristics and volume of the sediment exported from upland catchments in this experimental study we use a novel flume replicating hydrodynamic conditions prevailing in mountain rivers to investigate the role played by different controlling variables on pebble abrasion during fluvial transport lithology controls abrasion rates and processes with differences in abrasion rates exceeding two orders of magnitude attrition as well as breaking and splitting are efficient processes in reducing particle size mass loss by attrition increases with particle velocity but is weakly dependent on particle size fragment production is enhanced by the use of large particles high impact velocities and the presence of joints based on our experimental results we extrapolate a preliminary generic relationship between pebble attrition rate and transport stage c where fluvial shields stress and c critical shields stress for incipient pebble motion this relationship predicts that attrition rates are independent of transport stage for c 3 and increase linearly with transport stage beyond this value we evaluate the extent to which abrasion rates control downstream fining in several different natural settings a simplified model predicts that the most resistant lithologies control bed load flux and fining ratio and that the concavity of transport limited river profiles should rarely exceed 0 25 in the absence of deposition and sorting

clay mineral authigenesis in coal and shale from the anthracite region pennsylvania textural chemical and mineralogical analyses of authigenic clays in anthracite rank coal and associated shale from eastern pennsylvania have allowed a better understanding of the parameters controlling diagenesis and perhaps coalification in this region minerals in anthracite occur in distinct assemblages associated with the following microenvironments coal matrix two orthogonal joint sets termed systematic and nonsystematic cleat and a third joint set mineralogical differences among microenvironments allow inferences about clay mineral origins and the parameters that controlled mineral authigenesis kaolinite occurs in the shale and all microenvironments within the coal seam authigenic minerals that replaced preexisting kaolinite during the latest stage ofcoalification anthracitization at t 200 c include nhu rich illite pyrophyllite and the following minerals which are primarily restricted to the systematic cleat set tosudite rl ordered dioctahedral mixed layer chlorite smectite sudoite di trioctahedral chlorite and rectorite rlordered mixedjayer paragonite smectite alteration of smectite to illite may be responsible for formation of authigenic illite and na bearing illite which are present only in the shale and coal matrix and fe al rich chlorite and quartz in the third joint set the chemical components for authigenesis appear to have multiple sources ai and si from preexisting kaolinite and quartz n from local organic matter mg and na for tosudite sudoite and rectorite largely from metasomatic hydrothermal fluids fe and mg for fe al rich chlorite from smectite illitization minerals in the shale the coal matrix and the nonsystematic cleat set are interpreted to represent authigenesis in a low permeability environment closed system alteration however the assemblage sudoite tosudite rectorite in the systematic cleat set is interpreted to be the result ofone or two stages ofhydrothermal alteration open system alteration we suggest hat differences in minerals between the two nearly perpendicular cleat sets are the result of permeability differences which were maintained by an anisotropic lateral stress field created by plate convergence during the alleghanian orogeny hydrothermal alteration may be related to large scale basinal flow induced by alleghanianage uplift such migrating fluids could also have transported heat from depth and thereby significantly increased the rate and rank ofcoalification in this region

gradients in stream power influence lateral and downstream sediment flux in floods locations of landslides bank failures and floodplain deposition during recent intense flooding in vermont and colorado usa were spatially nonuniform indicating that some reaches are more prone to these types of geologic hazards these three key flood effects signal redistribution of sediment across landscapes reflecting hillslope channel coupling and the sources and or sinks of material we show that spatial gradients in total stream power provide critical additional information beyond at a point magnitudes for predicting which reaches are likely to be susceptible to these hazards during floods field tests in four rivers watershed areas 0 8 180 km 2 indicate that downstream increases in coincide with erosion and mass wasting into channels and downstream decreases in are associated with floodplain deposition our analytical approach supported by field evidence predicts geologic hazards and more broadly sources and sinks of material along rivers these are critical concerns from a practical and theoretical standpoint

mineralogical and geochemical compositions of the pennsylvanian coal in the adaohai mine daqingshan coalfield inner mongolia china modes of occurrence and origin of diaspore gorceixite and ammonian illite abstract aluminum hydroxide boehmite rich pennsylvanian coals of high volatile a bituminous rank were found previously in the jungar coalfield inner mongolia china this paper reports new results on 48 bench samples of the cp2 coal from the adjacent adaohai mine daqingshan coalfield inner mongolia and provides new insights into the origin and modes of occurrence of the minerals and elements present in the cp2 coal compared to the same coal in the adjacent mines the cp2 coal in the adaohai mine has a higher rank ro ran 1 58 which is attributed to igneous intrusions during the late jurassic and early cretaceous epochs the proportion of inertinite 35 3 in the coal is higher than that in other late paleozoic coals in northern china but lower than that in the jungar coals minerals in the cp2 coal include diaspore boehmite gorceixite calcite dolomite siderite clay minerals kaolinite and ammonian illite and trace amounts of anatase fluorapatite quartz and pyrite based on mineral proportions in the coal bench samples the cp2 coal may be divided into four zones i to iv from bottom to top the major mineral in zones i and iv is kaolinite zones ii and iii are mainly composed of ammonian illite diaspore boehmite gorceixite calcite dolomite and siderite diaspore boehmite and gorceixite forming materials were derived from oxidized bauxite in the weathered crust of the benxi formation in the sediment source region during peat accumulation however gorceixite may have formed earlier than diaspore the diaspore was derived from gibbsite that was subjected to dehydration by the heat of the igneous intrusions the ammonian illite may have been formed at a relatively high temperature by interaction of kaolinite with nitrogen released from the organic matter in the coal during metamorphism caused by the igneous intrusion the calcite and dolomite occur as epigenetic cell and fracture fillings and were probably derived from the igneous fluids compared to the common chinese and world coals the cp2 coal is enriched in cao 1 69 mgo 0 32 p2o5 0 214 f 207 g g ga 16 3 g g zr 446 g g ba 276 g g hg 0 33 g g and th 12 4 g g but has a lower sio2 al2o3 ratio due to the higher proportions of diaspore boehmite and gorceixite in the coal the f occurs mainly in gorceixite and fluorapatite the major carriers of ga are diaspore and kaolinite but not gorceixite barium mainly occurs in gorceixite and barite mercury was probably derived from the igneous intrusion and is distributed in both the organic matter and the minerals the elements are classified into five associations by cluster analysis groups a b c d and e group a represents a ree be y se ga ge sc in pb bi nb ta tio2 w hg sb zr hf th u association most of the elements in group a are lithophile elements that occur in aluminosilicate minerals group b sn te zn cd v as cr cu mo ni re is weakly correlated with ash yield and is associated with unidentified trace sulfide minerals elements in group c ad na2o al2o3 sio2 li k2o rb cs tl association probably occur in the clay minerals and diaspore group d consists of p2o5 ba f sr s and cl and with the exception of s they occur in minerals gorceixite and fluorapatite oxides of fe2o3 mno cao mgo make up group e and mainly occur in the carbonate minerals the coals are enriched in light rees and the lrees hrees have been highly fractionated with an average la yb n of 8 71 the heavy rees in the coals have a stronger organic affinity than the lrees

late holocene sediment storage in canyons of the colorado plateau field surveys of ten drainage basins 10 to 1 790 km2 in area in the colorado plateau utah and arizona and repeat photography of 156 fluvial environments providing comparative evidence spanning up to 114 yr reveal that two stratigraphic units characterize the alluvial materials on valley floors an older unit deposited generally between 1250 a d 200 yr and 1880 a d 20 yr was dissected by arroyo development by the early twentieth century a younger unit was deposited generally during the period after approximately 1943 5 yr rates of sedimentation in the 1943 1980 period were almost twice the rates in the 1250 1880 period channel storage rates during the two periods of sedimentation are related to drainage basin area by a power function similar to functions relating slope sediment production and sediment yield to drainage basin area storage rates in the 1943 1980 period were about 50 of the rates of slope sediment production the amount of sediment stored in the two units exhibits a definable spatial pattern source streams with basin areas upstream 10 000 km2 alternatively stored or evacuated moderate amounts of sediment in response to upstream evacuations of sediment from the colorado plateau riparian vegetation change and hydro climatic changes in mountain watersheds outside the plateau region

glacier outburst floods at mount rainier washington state u s a during the twentieth century glacial outburst floods have been the most destructive natural events on mount rainier a stratovolcano in the cascade range in washington state u s a in the period between 1930 and 1980 numerous floods were reported from five glaciers on the mountain most of which flowed from nisqually kautz or south tahoma glaciers on its southern flank such floods threaten lives and property because they occur without warning and quickly mobilize the loose volcanic debris into debris flows a monitoring program was begun in 1987 which was designed to measure the dimensions and timing of outburst floods but this has been unsuccessful because no floods have yet occurred on the monitored streams four floods did burst from south tahoma glacier that was unmonitored but in spite of this they have been useful in providing evidence of flood storage and release mechanisms all flood volumes were found to be of approximately similar orders of magnitude of 1 10 5 m 3 of water indicating that all floods probably had similar mechanisms for storage and release of water hydraulic pressure considerations indicate that such a large volume of flood water would be stored at the bed of the glacier rather than in isolated englacial cavities the stepped bedrock terrain provides an ideal setting for the formation of subglacial cavities capable of storing the volumes of flood water noted

model shows that rivers transmit high frequency climate cycles to the sedimentary record rivers are a major component of sediment routing systems that control the transfer of terrigenous sediments from source to sink although it is widely accepted that rivers are perturbed by millennial scale climatic variability the extent to which these signals are buffered or transferred down river systems to be recorded in sediments at or beyond the river mouth remains debated here we employ a physically based numerical model to address this outstanding issue our model shows that river transport strongly amplifies high frequency sediment flux variations arising from changing water discharge due to positive feedback between discharge and the channel gradient this behavior is distinctly different from short period sediment flux signals with constant water discharge where the output sediment flux is strongly dampened within the river due to negative feedback between the channel gradient and sediment concentration we conclude that marine sedimentary basins may record sediment flux cycles resulting from discharge and ultimately climate variability whereas they may be relatively insensitive to pure sediment flux perturbations such as for example those induced by tectonics

determination of elemental affinities by density fractionation of bulk coal samples from the chongqing coal district southwestern china abstract the occurrence and distribution of major and trace elements have been investigated in two coal bearing units in the chonqing mining district south china the late permian and late triassic coals the late permian coals have higher s contents than the late triassic coals due to the fixation of pyrite in marine influenced coal forming environments the occurrence of pyrite accounts for the association of a large number of elements fe s as cd co cu mn mo ni pb sb se and zn with sulphides as deduced from the analysis of the density fractions the marine influence is probably also responsible for the organic association of b the rees zr nb and hf are enriched by a factor of 2 3 with respect to the highest levels fixed for the usual worldwide concentration ranges in coal for these elements the content of these elements in the late permian coal is higher by a factor of 5 10 with respect to the late triassic coal furthermore other elements such as cu p th u v and y are relatively enriched with respect to the common range values with maximum values higher than the usual range or close to the maximum levels in coal the content of these elements in the late permian coal is higher than the late triassic coal these geochemical enrichments are the consequence of the occurrence in relatively high levels of phosphate minerals such as apatite xenotime and monazite as deduced from the study of the density fractions obtained from the bulk coal the late triassic coal has a low sulphur content with a major organic affinity the trace element contents are low when compared with worldwide ranges for coal in this coal the trace element distribution is governed by clay minerals carbonate minerals and to a lesser extent by organic matter and sulphide minerals major differences found between late permian and triassic coals are probably related to the source rocks given that the main source rock of the late permian epicontinental marine basin is the emeishan basalt formation characterised by a high phosphate content

river piracy and drainage basin reorganization led by climate driven glacier retreat river piracy the diversion of the headwaters of one stream into another one can dramatically change the routing of water and sediment with a profound effect on landscape evolution stream piracy has been investigated in glacial environments but so far it has mainly been studied over quaternary or longer timescales here we document how retreat of kaskawulsh glacier one of canada s largest glaciers abruptly and radically altered the regional drainage pattern in spring 2016 we use a combination of hydrological measurements and drone generated digital elevation models to show that in late may 2016 meltwater from the glacier was re routed from discharge in a northward direction into the bering sea to southward into the pacific ocean based on satellite image analysis and a signal to noise ratio as a metric of glacier retreat we conclude that this instance of river piracy was due to post industrial climate change rapid regional drainage reorganizations of this type can have profound downstream impacts on ecosystems sediment and carbon budgets and downstream communities that rely on a stable and sustained discharge we suggest that the planforms of slims and kaskawulsh rivers will adjust in response to altered flows and the future kaskawulsh watershed will extend into the now abandoned headwaters of slims river and eventually capture the kluane lake drainage river piracy the diversion of one stream s headwaters into another has occurred on long timescales an analysis of streamflow and digital elevation models documents river re routing in response to glacier retreat in yukon canada in may 2016

dolomitized middle proterozoic calcretes bathurst inlet northwest territories canada abstract dolostones within the terrigenous clastic middle proterozoic kanuyak formation are interpreted to be dolomitized calcretes dolocretes which formed on a landscape largely devoid of macroscopic organic life the dolocretes up to 5 m thick form beds or masses which either parallel or cross cut host sedimentary rocks and are composed of five elements 1 curvilinear and rectilinear networks of cracks which are filled with detrital terrigenous clastic and carbonate sediments ooids pisoids and cements sediments and cements are laminated and bedded generally parallel to the margins of cracks 2 micritic fibrous columnar and plumose dolomitic cements that were precipitated as calcareous speleothems ooids and pisoids and masses 3 ooids and pisoids that are concentrically laminat d homogenous or coated grains occurring in reversely graded beds and as isolated particles throughout dolocretes it appears that accretionary particles formed in situ based upon polygonal fitting vadose and grapestone fabrics and gradational contacts between ooids pisoids and host sediments 4 deformation structures that include folded and brecciated detrital sediments within cracks brecciated pisoids and minor teepees and 5 surface karren that locally truncate the dolocretes while missing the features commonly associated with higher plants in post silurian calcretes rhizoconcretions root mouldic porosity etc the presence of an array of other common calcrete fabrics e g cracks cements accretionary grains and deformation structures suggests that physical and chemical processes were probably largely responsible for the carbonate precipitates within kanuyak profiles microbiota most likely also contributed to calcretization however if not significantly altered by dolomitization stable carbon and oxygen isotope values do not indicate any significant influence by organic matter

geologic and physiographic controls on bed material yield transport and channel morphology for alluvial and bedrock rivers western oregon the rivers of western oregon have diverse forms and characteristics with channel substrates ranging from continuous alluvial gravel to bare bedrock analysis of several measurable morphologic attributes of 24 valley reaches on 17 rivers provides a basis for comparing nonalluvial and alluvial channels key differences are that alluvial reaches have greater bar area greater migration rates and show systematic correlation among variables relating grain size to bed material transport capacity we relate these differences between channel types to bed material transport rates as derived from a coupled regional analysis of empirical sediment yield measurements and physical experiments of clast attrition during transport this sediment supply analysis shows that overall bed material transport rates for western oregon are chiefly controlled by 1 lithology and basin slope which are the key factors for bed material supply into the stream network and 2 lithologic control of bed material attrition from in transport abrasion and disintegration this bed material comminution strongly affects bed material transport in the study area reducing transport rates by 50 90 along the length of the larger rivers in the study area a comparison of the bed material transport estimates with the morphologic analyses shows that alluvial gravel bed channels have systematic and bounding relations between bed material transport rate and attributes such as bar area and local transport capacity by contrast few such relations are evident for nonalluvial rivers with bedrock or mixed bed substrates which are apparently more influenced by local controls on channel geometry and sediment supply at the scale of western oregon the physiographic and lithologic controls on the balance between bed material supply and transport capacity exert far reaching influence on the distribution of alluvial and nonalluvial channels and their consequently distinctive morphologies and behaviors differences germane for understanding river response to tectonics and environmental perturbations as well as for implementing effective restoration and monitoring strategies

dolomitized calcrete in the middle devonian winnipegosis carbonate mounds subsurface of south central saskatchewan canada dolomitized calcrete is a widespread diagenetic feature in the uppermost portions of the middle devonian winnipegosis mud mounds in the subsurface of south central saskatchewan individual calcrete profiles are composed of 2 to 5 horizons including in descending order laminar crust massive pisolitic breccia chalky and transitional horizons the calcrete profiles are interpreted to be pedogenic in origin formed by diagenetic alteration of the host carbonate deposits during subaerial exposure of the mud mounds this interpretation is based on the occurrence of an orderly set of well differentiated horizons disconformities vadose pisoids micritic stringers circumgranular cracks linkage coatings and gradational contacts between the calcrete and underlying host carbonate rocks lack of root related structures such as rhizoconcretion and alveolar septal fabric in the winnipegosis calcrete suggests a limited influence of macrophytes on the formation of calcrete the occurrence of up to three discrete pedogenic calcrete profiles in a single winnipegosis calcrete succession indicates the mounds underwent three periods of subaerial exposure that resulted from drops of water level in the elk point basin of saskatchewan during middle devonian time d 2004 elsevier b v all rights reserved

differentiating the effects of logging river engineering and hydropower dams on flooding in the skokomish river washington usa abstract a decades long progressive loss of channel capacity in the skokomish river a 622 km2 basin draining the southeast olympic mountains of washington state has caused increasing flooding with severe consequences to endangered salmon runs infrastructure and private property to differentiate among multiple potential drivers of the capacity loss we analyze the geomorphic evidence for the potential effects of flow regulation by two dams constituting the cushman hydroelectric project which began regulating flow in the river s north fork in 1925 and diverting water out of the basin in 1930 sediment production from mid twentieth century logging in the river s south fork basin and twentieth century river engineering in the mainstem bankfull channel capacity in the mainstem has steadily declined since about 1940 from 370 m3 s 1 to

mineralogical and geochemical responses of coal to igneous intrusion in the pansan coal mine of the huainan coalfield anhui china the huainan coalfield where magma is commonly intruded into the coal measures in the northern section e g the zhuji dingji pansan and panbei mines is the largest energy base in eastern china to investigate the mineralogical and geochemical responses of coal to igneous intrusion minerals major and trace elements in sandstone thermally altered coal igneous rock sandy mudstone and unaltered coal samples were collected from a representative profile of the no 1 coal of the pansan coal mine the samples were analyzed using an optical microscope powder x ray diffraction scanning electron microscopy in conjunction with x ray energy dispersive spectroscopy x ray fluorescence inductively coupled plasma atomic emission spectrometry and mass spectrometry the results indicated that the thick sill transformed from mafic rocks at the bottom via intermediate rocks in the middle to felsic rocks at the top of the profile the moisture total sulfur and carbon contents of the coal increased whereas volatile matter hydrogen and nitrogen decreased during contact metamorphism caused by igneous intrusion epigenetic minerals i e dolomite quartz and pyrite occurred in the thermally altered coals three stages of hydrothermal fluids i e ca mg and fe rich si rich and fe and or h2s rich solutions were identified iron ca s si mg zn cd and pb were transported into the thermally altered coal by hydrothermal fluids the concentrations of co and ni in the thermally altered coal increased in relation to the increase of ash yields that were caused by contact metamorphism whereas the b in the coal was volatilized manganese is directly related to the intrusive magma phosphorus ge and sr might be introduced into the coal by groundwater however k na ga and ba were leached out titanium sc cr v cu zr nb and rare earth elements and yttrium rey in the coals originated from terrigenous input and were not influenced by igneous intrusion

incision and morphologic evolution of an alluvial channel recovering from hydraulic mining sediment hydraulic gold mining in the sierra nevada california produced such a large volume of sediment from 1853 to 1884 that channels could not carry a substantial proportion of the delivered sediment the lower bear river aggraded as much as 5 m and underwent a major avulsion during the 1870s channel morphology continues to respond to these changes more than 100 years after the cessation of most hydraulic mining textures of mine tailings and older alluvium are contrasted and channel incision and channel shape changes from 1930 to 1985 are documented unlike the yuba and sacramento rivers the lower bear river had not returned to pre mining base levels by 1950 as sediment loads decreased nor were incision rates or morphological change governed by reduced sediment loads below dams built in 1928 and in the mid 1960s channel stability was due to resistance of a cohesive stratum on the channel bed an episode of channel down cutting was instigated by a moderately large flood in december 1955 that pierced the cohesive layer and was sustained through the 1970s by moderate magnitude floods the 1955 flood did not directly erode large volumes of sediment but it destabilized the channel allowing smaller floods to erode the channel at an accelerated rate episodic channel bed incision is contrasted to progressive morphologic changes cross section shape narrowed and deepened steadily from 1930 through the mid 1970s as the channel was superimposed onto cohesive older alluvium progressive deepening set up a positive feedback that ensured the ultimate penetration of the paved bed channel morphologic readjustment from the avulsion thus was both progressive and episodic

sediment export transient landscape response and catchment scale connectivity following rapid climate warming and alpine glacier recession abstract in the face of rapid climate warming rapid glacier recession should lead to a marked increase in the spatial extent of the paraglacial zone in glaciated drainage basins the extent of the paraglacial zone has been well established to be transient but there are very few studies of this transient response and what it means for sediment export there is good reason to expect that glacier recession could increase basin scale sediment connectivity as sediment becomes less dependent on glacier surface transport proglacial streams are more able to migrate laterally than subglacial streams and so access sediment for transport and glacier debuttressing may aid the development of gullies that can dissect moraines and so aid hillslope to proglacial zone connectivity by using records of the flushing of hydroelectric power installations we were able to develop a record of coarse sediment sand and gravel export from a basin with a rapidly retreating valley glacier the haut glacier d arolla from 1977 to 2014 modelling suggested that these data could only be partially controlled by transport capacity implying an important role for sediment supply and potentially for the influence of changing sediment connectivity indeed there was evidence of the effects of glacial debuttressing upon gullying processes and hence a possible increase in the ease of connection of upstream basins to the proglacial area more recently we were able to show possible temperature control on sediment export which may only have become apparent because of the progressive development of better sediment connectivity however whilst rapid glacier recession should result in theory in a progressive increase in connectivity of sediment sources to the basin outlet the supply to capacity ratio does not increase continually with glacier recession until maximum capacity is reached we identified two possible examples of why first gullying was also accompanied by the sediment accumulation at the base of moraines that was too coarse to be transported by the proglacial stream maintaining disconnection of the upper basins second the sediment capacity ratio appeared to be elevated during periods of more rapid retreat and we attribute this to the importance of a continued supply of unworked glacial till before fluvial reworking and sorting of freshly exposed sediment increased the resistance of sediment to entrainment and hence export rates thus the transient geomorphic response of glaciated basins to glacier recession may involve negative feedbacks that can reduce the extent to which increases in connectivity elsewhere in the basin lead to increased sediment export

a general model of paraglacial landscape response a unifying attribute of all forms of paraglacial response is that deglaciation results in the exposure of unstable or metastable sediment sources that are subsequently tapped by a wide variety of processes over a wide range of timescales the paraglacial period in different geomorphological contexts is therefore con ditioned by two variables glacially conditioned sediment release and rate of sediment reworking under steady state conditions the latter may be approximated by an exhaustion model in which sediment yield is related to the amount of remaining available sediment by a negative exponential function this model offers an approximation for the behaviour of primary paraglacial systems in which glacigenic sediment sources are not replenished the long term behaviour of secondary primarily uvial paraglacial systems in which sediment inputs include both in situ and reworked glacigenic sediment appears intrinsically more complex but consistent with an exhaustion model if initial sediment avai

polygenetic polyphase karsted hardground omission surfaces in lower silurian neritic limestones anticosti island eastern canada abstract exquisitely preserved and well exposed rocky paleoshoreline omission surfaces in lower silurian chicotte formation limestones on anticosti island quebec are interpreted to be the product of combined marine and meteoric diagenesis the different omission features include 1 planar erosional bedding tops 2 scalloped erosional surfaces 3 knobs ridges and swales at bedding contacts and 4 paleoscarps an interpretation is proposed that relates specific styles of omission surface to different diagenetic depositional processes that acted in separate terrestrial peritidal shallow neritic zones such processes were linked to fluctuations in relative sea level with specific zones of diagenesis such as 1 karst corrosion 2 peritidal shallow subtidal erosion 3 subtidal seawater flushing and cementation and 4 shallow subtidal deposition most surfaces are interpreted to have been the result of initial extensive shallow water synsedimentary lithification forming hardgrounds that were as sea level fell planed by inner neritic abrasion successively altered by exposure and subaerial corrosion only to be buried by sediments as sea level rose again this succession was repeated several times resulting in a suite of recurring polyphase omission surfaces through many meters of stratigraphic section synsedimentary cloudy marine cements are well preserved and are thus interpreted to have been calcitic originally aragonite components are rare and thought to have been dissolved just below the silurian seafloor large mollusks that survived such seafloor removal were nonetheless leached and the resultant megamolds were filled with synsedimentary calcite cement these silurian inner neritic strandline omission surfaces are temporally unique they are part of a suite of marine omission surfaces that are mostly found in early to middle paleozoic neritic carbonate sedimentary rocks these karsted hardgrounds formed during a calcite sea time of elevated marine carbonate saturation and extensive precipitation of marine cement the contemporaneous greenhouse atmosphere was supercharged with co2 leading to profound surface karst under strongly acid rain younger peritidal omission surfaces although potentially formed during aragonite sea or calcite sea times would have been subject to very different terrestrial diagenetic process with lower atmospheric pco2 values but increasingly complex biogenic soils producing dissimilar alteration features

glacial erosion evolution of river long profiles and the organization of process domains in mountain drainage basins of coastal british columbia 1 in glaciated british columbia canada quaternary climate changes are responsible for profound spatial reorganization of earth surface processes these changes have left a landscape characterized by topographic anisotropy associated with a hierarchy of glacial troughs the evolution of glaciated landscapes is examined by analyzing the structure of geomorphic process domains and channel long profiles to identify process domains we use channel surveys and gis analysis to construct slope area transects of the channel network this analysis reveals generalized process form disequilibrium with a mismatch between topographic signatures and currently active geomorphic process domains at the landscape scale of source colluvial channels contributing area 1 km2 the glacial paraglacial signature commonly overrides that produced by contemporary debris flows along the axis of former ice flows relict glacial cirques introduce a hanging fluvial domain at contributing areas as small as 8 10 2 km2 and produce complex channel long profiles similar to those observed for rivers responding to tectonic forcing slope area relations typical of unglaciated equilibrium environments do not apply here the concept of process domains appears to hold however some major glacially forced modifications in the alluvial colluvial transition are observed and the definition of a depositional colluvial subdomain is proposed comparison between field and gis measured slopes reveals that gis associated error is not uniform between process domains and that gis based plots do not successfully discriminate field based process domains the combination of glacial and post glacial fingerprints and the effects of ongoing earth surface processes generate a complex landscape whose glacial signatures may persist until the onset of the next ice age

postglacial adjustment of steep low order drainage basins canadian rocky mountains 1 it is generally argued that pleistocene glaciation results in increased sediment flux in mountain systems an important but not well constrained aspect of pleistocene glacial erosion is the geomorphic decoupling of cirque basins from main river systems this study provides a quantitative link between glacier induced basin morphology postglacial erosion and sediment delivery for mountain headwaters with basin area 28 respectively and ii larger fan sizes at outlets of noncirque basins compared to cirques although small headwater basins represent the steepest part of mountain environments and erode significant postglacial sediment the majority of sediment remains in storage under interglacial climatic conditions and does not affect large scale mountain river systems

development of longitudinal profiles of alluvial channels in response to base level lowering degradation of alluvial channels in cohesive sediments was studied in 15 m and 20 m long flumes with a slope of 0 01 cm cm degradation was initiated by lowering base level to a fixed position and the development of the longitudinal profile of the channel is analysed through a model formulated as a heat diffusion equation it is based on the equation of sediment continuity combined with an assumption regarding sediment transport namely that sediment discharge is linearly proportional to the channel slope in accordance with the boundary and initial conditions imposed by the experimental setup and procedure the basic equation is amenable to an analytical solution which defines bed elevation at any distance and time as a function of the amount of base level lowering and a diffusion coefficient additional problems arising from bank erosion and channel armouring are also treated successfully within the framework of the same model the results show that in homogeneous alluvial sediments not subject to armouring the ultimate result of base level lowering by a certain amount is degradation all along the channel by the same amount the main impact of erosion is felt in the early stages after initiation of the process and mainly near the mouth the rate of degradation at any station along the channel reaches a peak and then slowly decreases with time and the peak rate is attenuated with distance from the outlet the model permits the prediction of intermediate stages of profile development at any distance from the outlet and at different times

the legacy of pleistocene glaciation and the organization of lowland alluvial process domains in the puget sound region article i nfo alluvial rivers of the eastern puget lowland a landscape shaped by scour and fill from the cordilleran ice sheet continue to respond to patterns of deposition and scour by the last glacial age ice sheet 18 000 years after deglaciation topography revealed by valley cross sections created from high resolution lidar digital elevation models shows that rivers are aggrading in valleys eroded by subglacial runoff and degrading in valleys incised by rivers post glaciation slope area analysis of river profiles shows that profile concavity varies systematically between river segments in the two valley contexts concavity indices in mountain headwaters 0 3b b0 9 compare to those of many world rivers 0 2b b1 0 but in the lowlands these indices differ between valleys created by subglacial fluvial erosion 5b b45 and post glacially incised river valleys that grade to base levels set by these relict glacial valleys or by post glacial sea levels 1b b7 dramatic differences in river pattern landforms and dynamics occur in valleys having contrasting aggrading vs degrading and incomplete responses to pleistocene glaciation creating discrete valley scale hetero geneities in fluvial process domains along and between rivers these results point to the importance of valley scale organization of alluvial process domains along and between rivers having profiles remaining in disequilibrium from pleistocene glaciation they also point to the potential usefulness of slope area analysis of longitudinal profiles in distinguishing among different river valley process domains in lowland alluvial landscapes

nature and distribution of phosphorus minerals in cook inlet coals alaska although phosphorus is a very important biogenic element its concentration in coal is generally low phosphorus concentrations typically range from 0 001 to 0 229 in raw coals of the contiguous 48 states of the u s a some alaskan coals in the cook inlet region contain horizons unusually high in phosphorus analyses of coals at 0 3 m intervals from a deep drill core containing 21 3 m of subbituminous c coal from the beluga coalfield alaska showed certain increments with as much as 17 03 p2o5 in the coal ash 1 01 p on a moisture free coal basis crandallite group minerals were identified by electron microprobe analyses as phosphorus rich minerals in these coals crandallite was found as 3 m size colloidal precipitates and as concretions and porous aggregates as large as 100 m calcium barium strontium and phosphorus concentrations in the coal attributable to crandallite group minerals can be quantified using chemical fractionation for exchangeable cations and acid extractable elements because high phosphorus horizons in cook inlet coals are attributed to periodic infusions of phosphorus from volcanic ash as well as the proper chemical environment for the precipitation of the phosphorus minerals it is suggested that the profiles of acid extractable phosphorus concentration may be useful to aid coal seam correlations

stable isotope variations in the neoproterozoic beck spring dolomite and mesoproterozoic mescal limestone paleokarst implications for life on land in the precambrian proterozoic karst events lowered 13c values by as much as 11 for the 800 ma beck spring dolomite california and as much as 8 5 for the 1 1 ga mescal limestone central arizona relative to the originally deposited carbonate the 13c changes are attributed to input of 13c depleted organic co2 derived from photosynthetic organisms that colonized the ancient land surface the large isotopic shift and its presence at two separate localities suggest that proterozoic karst surfaces were colonized by significant photosynthetic communities with phytomasses possibly approaching those of today

natural streams and the legacy of water powered mills gravel bedded streams are thought to have a characteristic meandering form bordered by a self formed fine grained floodplain this ideal guides a multibillion dollar stream restoration industry we have mapped and dated many of the deposits along mid atlantic streams that formed the basis for this widely accepted model these data as well as historical maps and records show instead that before european settlement the streams were small anabranching channels within extensive vegetated wetlands that accumulated little sediment but stored substantial organic carbon subsequently 1 to 5 meters of slackwater sedimentation behind tens of thousands of 17th to 19th century milldams buried the presettlement wetlands with fine sediment these findings show that most floodplains along mid atlantic streams are actually fill terraces and historically incised channels are not natural archetypes for meandering streams

a generalized exner equation for sediment mass balance 1 the advance of morphodynamics research into new areas has led to a proliferation of forms of sediment mass balance equation without a general equation it is often difficult to know what these problem specific versions of sediment mass balance leave out to address this we derive a general form of the standard exner equation for sediment mass balance that includes effects of tectonic uplift and subsidence soil formation and creep compaction and chemical precipitation and dissolution the complete equation 17 allows for independent evolution of two critical interfaces that between bedrock and sediment or soil and that between sediment and flow by eliminating terms from the general equation it is straightforward to derive mass balance equations applicable to a wide range of problems such as short term bed evolution basin evolution bedrock uplift and soil formation and carbonate precipitation and transport dropping terms makes explicit what is not being considered in a given problem and can be done by inspection or by a formal scaling analysis of the terms scaling analysis leads directly to dimensionless numbers that measure the relative importance of terms in the equation for example the relative influence of spatial versus temporal changes in sediment load on bed evolution combining scaling analysis with time averaging shows how the relative importance of terms in the equation can change with timescale for example the term representing bed evolution due to temporal change in sediment load tends to zero as timescale increases

sediment connectivity in the high alpine valley of val muschauns swiss national park linking geomorphic field mapping with geomorphometric modelling abstract the efficiency of sediment routing through mountain sediment cascades is controlled by the connectivity of hillslopes to the main river system a lack of connectivity may cause long term sediment storage and exclude large fractions of a basin from the sediment routing for several thousand years here we studied sediment dynamics in a small formerly glaciated valley in the swiss alps to characterise the sediment connectivity to the stream we calculated a morphometric index using a gis algorithm the modelling results were tested against a field based geomorphic mapping of sediment storages which were evaluated with respect to their state of de coupling in accordance to the field diagnostics the modelling results indicate very well that the present day sediment flux is conditioned by the glacial valley morphometry inherited through pleistocene glaciation especially in the upper hanging valleys the connectivity index is reduced noticeably due to the glacial cirque morphology based on the field mapping 30 of the hillslope sediment cascades are interrupted and 20 of the storage boundaries are currently affected by a lack of material transfer as a consequence 29 of the basin surface is currently disconnected from the main river nevertheless the gis algorithm overestimates the connectivity within the basin because it fails to calculate decoupling between neighbouring pixels in digital terrain models dtms around 35 of the basin surface which has been mapped in the field as being decoupled is related to relative high connectivity our study highlights the potential of morphometric gis modelling for studying sediment connectivity but additionally emphasises the indispensability of geomorphic field mapping for a holistic understanding of mountain cascading systems

coarse sediment dynamics in a large glaciated river system holocene history and storage dynamics dictate contemporary climate sensitivity the gravel bedded white river drains a 1279 km2 basin in washington state with lowlands sculpted by continental glaciation and headwaters on an actively glaciated stratovolcano chronic aggradation along an alluvial fan near the river s mouth has progressively reduced flood conveyance in order to better understand how forecasted climate change may influence coarse sediment delivery and aggradation rates in this lowland depositional setting we assessed the contemporary delivery and routing of coarse sediment through the watershed this assessment was based on a rich set of topographic sedimentologic and hydrologic data from the past century with a focus on repeat high resolution topographic surveys from the past decade we found that most of the lower river s contemporary bed load flux originates from persistent erosion of alluvial deposits in the lower watershed this erosion is a response to a drop in local base level caused by a major avulsion across the fan in 1906 and then augmented by subsequent dredging the 1906 avulsion and modern disequilibrium valley profiles reflect landscape conditioning by continental glaciation and a massive mid holocene lahar in the proglacial headwaters infrequent large sediment pulses have accomplished most of the observed coarse sediment export with exported material blanketing downstream valley floors during typical floods transported bed material is largely sourced from erosion of these valley floor deposits throughout the watershed we observe decadal scale coarse sediment dynamics strongly related to the filling or emptying of valley scale sediment storage over 102 104 yr time scales often in response to major disturbances that either emplace large deposits or influence their redistribution paraglacial responses in large watersheds are suggested to be inherently complicated and punctuated as a result of internal landform interactions and stochastic threshold dependent events we argue in combination that holocene disturbance storage dynamics and human flow modification make coarse sediment fluxes in the lower white river relatively insensitive to decadal climate variability results highlight the degree to which river sensitivity to contemporary disturbance climatic or otherwise may be contingent on local and idiosyncratic watershed histories underscoring the need to unpack those histories while demonstrating the utility of watershed scale high resolution topography toward that end

reconstructing hydro climatic events and glacier fluctuations over the past millennium from annually laminated sediments of cheakamus lake southern coast mountains british columbia canada abstract we recovered sediment cores from cheakamus lake in the southern coast mountains southwest british columbia to reconstruct late holocene environmental conditions in the watershed the cored sediments are inorganic rhythmically laminated clayey silt radiocarbon ages and correlation of lamina thickness with the magnitude of the annual flood recorded at a nearby gauging station indicate that the laminae are varves we discriminate seven types of varves on the basis of couplet thickness and internal structure and compare them to annual hydrographs over the period of record the seven varve types record summer snowmelt floods autumn floods mid season floods years with two major floods years with three major floods years with more than three major floods and periods of sustained glacier runoff varves attributed to autumn storms and glacier runoff are dominant exhibit serial dependence and are most common during six periods ad 1300 1320 1380 1410 1470 1500 1710 1730 1880 1906 and 1916 1945 in contrast varves attributed to summer snowmelt floods are randomly distributed through time thickest varves occur during the decades ad 1090 1110 1120 1170 1210 1250 1310 1330 1390 1450 1720 1780 1860 1900 and 1920 1945 the relation between little ice age glacier activity and lake sedimentation is complex but the thickest varves coincide with times of rapid glacier retreat and periods when air temperatures were warmer than average the results confirm the importance of sediment transfers during the summer and autumn runoff season in the british columbia coast mountains

effects of igneous intrusions on thermal maturity of carbonaceous fluvial sediments a case study of the early cretaceous strzelecki group in west gippsland victoria australia abstract this study has investigated the effect of small igneous intrusions on early cretaceous carbonaceous fluvial sediments of the gippsland basin of south eastern australia based on outcrops in the onshore western part of the basin vitrinite reflectance measurements quantitative mineral phases and clay mineralogy were carried out on twenty two samples of organic rich mudstone up to 25 m east and west of a 1 m wide dyke samples of the dyke allowed classification as an alkali basalt based on its optical characteristics and major and trace element properties background vitrinite reflectance of 0 75 0 80 r max in the sediments is elevated up to 6 67 r max close to the dyke margin with slightly different patterns on each side of the intrusion analysis of seven selected organic rich mudstone samples shows that they all have very similar xrd patterns with the main minerals in all cases being quartz feldspar mainly plagioclase chlorite illite and interstratified illite smectite these observations suggest that the thermal maturity of the organic matter in the sediments was locally elevated by heating due to emplacement of the dyke but no significant changes were observed in host rock mineralogy that could be related to the heat generated by the dyke and the associated vitrinite reflectance variations

carbonate platform growth and cyclicity at a terminal proterozoic passive margin infra krol formation and krol group lesser himalaya india the infra krol formation and overlying krol group constitute a thick 2 km carbonate rich succession of terminal proterozoic age that crops out in a series of doubly plunging synclines in the lesser himalaya of northern india the rocks include 18 carbonate and siliciclastic facies which are grouped into eight facies associations 1 deep subtidal 2 shallow subtidal 3 sand shoal 4 peritidal carbonate complex 5 lagoonal 6 peritidal siliciclastic carbonate 7 incised valley fill and 8 karstic fill the stromatolite rich peritidal complex appears to have occupied a location seaward of a broad lagoon an arrangement reminiscent of many phanerozoic and proterozoic platforms growth of this complex was accretionary to progradational in response to changes in siliciclastic influx from the south eastern side of the lagoon metre scale cycles tend to be laterally discontinuous and are interpreted as mainly autogenic variations in the number of both sets of cycles and component metre scale cycles across the platform may result from differential subsidence of the interpreted passive margin apparently non cyclic intervals with shallow water features may indicate facies migration that was limited compared with the dimensions of facies belts correlation of these facies associations in a sequence stratigraphic framework suggests that the infra krol formation and krol group represent a north to north westfacing platform with a morphology that evolved from a siliciclastic ramp to carbonate ramp to peritidal rimmed shelf and finally to open shelf this interpretation differs significantly from the published scheme of a basin centred on the lesser himalaya with virtually the entire infra krol krol succession representing sedimentation in a persistent tidal flat environment this study provides a detailed neoproterozoic depositional history of northern india from rift basin to passive margin and predicts that genetically related neoproterozoic deposits if they are present in the high himalaya are composed mainly of slope basinal facies characterized by fine grained siliciclastic and detrital carbonate rocks lithologically different from those of the lesser himalaya

laws place history and the interpretation of landforms the state of an earth surface system ess is determined by three sets of factors laws place and history laws l l1 l2 ln are the n general principles applicable to any such system at any time place factors p p1 p2 pm are the m relevant characteristics of the local or regional environment history factors h h1 h2 hq include the previous evolutionary pathway of the ess its stage of development past disturbance and initial conditions geoscience investigation may focus on laws place or history but ultimately all three are necessary to understand and explain ess the lph triad is useful as a pedagogical device illustrated here via application to explaining the world s longest cave mammoth cave ky beyond providing a useful checklist the lph framework provides analytical traction to some difficult research problems for example studies of the avulsions of three southeast texas rivers showed substantial differences in avulsion regimes and resulting alluvial morphology despite the proximity and superficial similarity of the systems avulsions are governed by the same laws in all cases l a l b l c and the three rivers have undergone the same sea level climate and tectonic histories as well as the same general anthropic impacts h a h b h c though regional environmental controls are similar local details such as the location of the modern main channel relative to pleistocene meander channels differ and thus these place factors explain the differences between the rivers the lph framework or similar types of reasoning is implicit in many types of geoscience analysis explicit attention to the triad can help solve or address many specific problems and remind us of the importance of all three sets of factors copyright 2016 john wiley sons ltd

scale variation of post glacial sediment yield in chilliwack valley british columbia the holocene volumetric sediment budget is estimated for coarse textured sediments sand and gravel in a large formerly glaciated valley in southwest british columbia erosion is estimated by compiling volumetric loss estimated in digital elevation models dems of gullied topography and by applying a non linear diffusion model on planar undissected hillslopes estimates of steepland yield are based on estimates of post glacial deposition volumes in fans cones and deltas at the outlets of low order tributary catchments erosion of post glacial fans and tributary valley fills is estimated by reconstructing formerly continuous surfaces results are classed by catchment order and compared across scales of contributing area revealing declining specific sediment yield in m3 km 2 a 1 with catchment area for the smaller tributaries 10 km2 and increasing specific sediment yield for larger tributaries and chilliwack valley itself approximately 60 of mobilized sediment is redeposited in first to third order catchments with lesser proportions stored at the outlets of higher order catchments a simple network routing model emphasizes the significant sediment flux contributions from colluvium drift blankets and gullies in steeper terrain as this material is deposited at junctions within the lower drainage network an increasing proportion of material is derived from remnant valley fills and para glacial fans in the major valleys yield from lower order steepland catchments tends to remain in storage indefinitely sequestered on footslopes these observations have implications for modelling the post glacial sediment balance amongst catchments of varying size after 104 years the system remains in disequilibrium the critical linkage lies between low order hillslope catchments fourth order and the larger valleys with more complex fluvial systems copyright 2010 john wiley sons ltd

sediment continuity through the upland sediment cascade geomorphic response of an upland river to an extreme flood event hillslope erosion and accelerated lake sedimentation are often reported as the source and main stores of sediment in the upland sediment cascade during extreme flood events while upland valley floodplain systems in the transfer zone have the potential to influence sediment continuity during extreme events their geomorphic response is rarely quantified this paper quantifies the sediment continuity through a regulated upland valley fluvial system st john s beck cumbria uk in response to the extreme storm desmond 4 6 december 2015 flood event a sediment budget framework is used to quantify geomorphic response and evaluate sediment transport during the event field measurements show 6500 710 t of sediment was eroded or scoured from the river floodplains banks and bed during the event with 6300 570 t of sediment deposited in the channel or on the surrounding floodplains 6 of sediment eroded during the flood event was transported out of the 8 km channel floodplain sediment storage was seen to be restricted to areas of overbank flow where the channel was unconfined results indicate that rather than upland floodplain valleys functioning as effective transfer reaches they instead comprise significant storage zones that capture coarse flood sediments and disrupt sediment continuity downstream

retreating ice research in pro glacial areas matters glacier forefields are landscapes in transition from glacial to non glacial conditions this implies intense geomorphic hydrological and ecological dynamics with important on and off site effects this special issue collects 13 papers covering recent research in both sub polar and alpine proglacial environments that focus on i proglacial sediment sources ii proglacial rivers iii proglacial lakes iv ground water and ice and v the development of soil and vegetation in its interplay with morphodynamics advances in mapping surveying and geophysical techniques form the basis for research perspectives related to the historical evolution of proglacial areas the understanding of complex interactions of multiple processes and the effects of continued glacier recession

disequilibrium of holocene sediment yield in glaciated british columbia it is generally supposed that specific sediment yield the quantity of sediment passing a monitored river cross section per unit area drained upstream of that section declines as the area drained increases1 3 part of the sediment mobilized from the land surface is supposed to go back into storage at field edges and on footslopes and floodplains in contrast we show here that data from british columbian rivers reveal a pattern of increasing specific sediment yield at all spatial scales up to 3 104 km2 this results from the dominance of secondary remobilization of quaternary sediments along river valleys over primary denudation of the land surface the result controverts the conventional model which has been derived from studies of small highly disturbed agricultural catch ments the rivers are still responding to the last glaciation giving a landscape relaxation time greater than 10 kyr this holds pro found implications for geomorphological theory and for studies of erosion