errors in bathymetric retrievals using linear dispersion in 3 d fft analysis of marine radar ocean wave imagery the phenomenon of ocean wave shoaling and the associated reduction of ocean wave phase speed with decreased water depth provides useful information for inferring water depth d bathymetry in coastal environments one strategy for relating d to phase speed c and wave vector k of long wavelength ocean waves involves using the one dimensional 1 d linear gravity wave dispersion relationship c sup 2 g tanh kd k in principle this approach has limitations because the approach is based on a wkb approximation so it cannot be applied when d varies appreciably over the wavelength of a shoaling wave also the approach is restricted to waves that have small wave height the author uses a set of marine radar image sequences and applies this linear approximation using a 3 d fft analysis of 88 sets of image sequences spaced half an hour apart the author inverts the dispersion relation to solve for d depths between 3 6 and 5 8 m were tested for root mean square rms wave heights offshore between 8 and 3 m the author shows that for low to moderate wave heights the approach does generally retrieve the correct depth in water depths of 5 m and greater for moderate wave rms heights however an increase in the rms wave height from 1 m to 3 5 m produced a much poorer depth estimate proving the need for an application of a nonlinear wave model to the problem the errors also increase with shallower depths as expected as the error dependence on depth and wave height is determined

facies and facies architecture of paleogene floodplain deposits willwood formation bighorn basin wyoming usa abstract paleogene deposits of the willwood formation were analyzed in two areas of the bighorn basin to provide a better understanding of the facies and facies arrangement of floodplain deposits and the various processes that influence floodplain construction and facies variability despite similar facies and facies organization floodplain deposits in the two areas differ in grain size hydromorphy and maturity of the paleosols and scale and organization of ribbon sandstones in the avulsion deposits these differences appear to be controlled by basin position of the study areas and differences in avulsion between the areas two kinds of cumulative floodplain paleosols red and purple paleosols formed on overbank deposits the red paleosols were better drained and formed on less clay rich parent material intense mottling and iron oxide nodules indicate that the purple paleosols which formed on more clay rich parent material were poorly drained the grain size differences reflect basin position in particular distance from a local sediment source avulsion deposits are volumetrically important comprising about half of the floodplain deposits in both areas the avulsion deposits resemble the stage iii splays described by smith et al 1989 smith n d cross ia dufficy j p clough s r 1989 anatomy of an avulsion sedimentology 36 1 24 in terms of characteristics of their ribbon sandstones and the presence of thin sheet sandstones or siltstones paleosols that formed on the fine grained facies show morphologic differences interpreted as developmental differences and attributed to differing rates of avulsion in the two study areas this study shows that avulsion belt paleosols provide a key to understanding avulsion rate in the stratigraphic record other differences between the willwood avulsion deposits in the two areas and between these ancient deposits and the modern avulsion deposits described by smith et al may reflect 1 problems in clearly recognizing ancient avulsion deposits in the field and 2 sampling bias resulting from the areally restricted view provided by the stratigraphic record of an areally extensive modern depositional feature at the same time because exposures are three dimensional the willwood strata reveal aspects of the facies and facies arrangement of avulsion belts not readily observed in the modern ones

static connectivity of fluvial sandstones in a lower coastal plain setting an example from the upper cretaceous lower williams fork formation piceance basin colorado this study addresses the field scale architecture and static connectivity of fluvial sandstones of the lower williams fork formation through analysis and reservoir modeling of analogous outcrop data from coal canyon piceance basin colorado the upper cretaceous lower williams fork formation is a relatively low net to gross ratio commonly 30 succession of fluvial channel sandstones crevasse splays flood plain mudstones and coals that were deposited by meandering river systems within a coastal plain setting the lower williams fork outcrops serve as proximal reservoir analogs because the strata dip gently eastward into the piceance basin where they form natural gas reservoirs three dimensional architectural element models 3 d reservoir models of the lower williams fork formation that are constrained to outcrop derived data e g sandstone body types dimensions stratigraphic position from coal canyon show how static sandstone body connectivity is sensitive to sandstone body width and varies with net to gross ratio and well spacing with a low well density e g 160 ac well spacing connectivity is low for net to gross ratios less than 20 connectivity increases between net to gross ratios of 20 to 30 and levels off above a net to gross ratio of 30 as well density increases static connectivity increases more linearly with an increasing net to gross ratio for a 20 ac well spacing static connectivity can range from approximately 35 to 75 and 45 to 80 for net to gross ratios of 10 and 15 respectively depending on sandstone body width given the lower net to gross ratio and continuity of lower williams fork deposits this underscores the importance of representative sandstone body statistics e g sandstone body type dimensions to aid in subsurface correlation and mapping and to constrain reservoir models

large scale alluvial architecture and correlation in a triassic pebbly braided river system lower wolfville formation fundy basin nova scotia canada abstract determining what the controls are on the large scale 10 km horizontal architecture of coarse grained fluvial deposits is important for understanding subsurface fluid distribution and extraction from these important aquifers and hydrocarbon reservoirs this contribution describes the architecture of coarse grained fluvial sediments from an almost continuous lateral profile 27 km long by 115 m high in the upper triassic wolfville formation fundy basin nova scotia the lateral extent and quality of exposure allows development of a high resolution correlation scheme and definition of architectural elements the lower wolfville formation lithofacies composed of breccias conglomerates sandstones mudstones and paleosols comprises alluvial fan fluvial and ephemeral lake margin facies associations alluvial fan deposits form 15 of the studied section and are developed locally between the overlying fluvial facies and the unconformity with carboniferous strata where they infill remnant topography the succession is dominated 80 by pebbly sandstones deposited as part of a gravelly braided fluvial system and ends abruptly with a thin ephemeral lake margin facies association 5 the large scale architecture and sedimentology of the pebbly sandstone succession is documented with particular attention focussed on bounding surfaces and stacking patterns in the fluvial facies association two scales of development of erosion surface and cycles can be recognized the s surfaces can be correlated across the profile 27 km and show evidence of up to 10 m of erosion a significant facies or grain size change onlap and association with mature calcic paleosols the e surfaces can be correlated between 5 and 17 km display erosion of the regional extent of the e and s surfaces indicate that the gravelly fluvial system has a large scale sheet like geometry which comprises a series of stacked erosion dominated multi story bodies high resolution architectural elements are poorly defined in this coarse fluvial system and make it difficult to constrain the scale of the depositional system an individual high resolution cycle records braid plain development and is interpreted as a multi story channel belt the braid plain width is estimated at 19 km but the width of individual active channels is unknown the sediments were deposited in a proximal fluvial setting disconnected from marine influences we interpret the high resolution cycles and bounding e surfaces to record a progressive decrease in runoff and fluvial transport capacity indicative of a drying upward climatically driven signal the origin of the s surface bounded packages is more difficult to determine a variety of mechanisms are considered including changes in discharge driven by climatic fluctuations changes in stream power related to drainage capture within the source area and tectonic tilting an important aspect of the study is that the s surfaces can be identified and correlated for 27 km and provide an example of a robust high resolution correlation framework in coarse grained braided fluvial deposits that could be applied elsewhere in contrast the e surfaces do not display any significant changes in facies or grain size across them such that many of the smaller scale cycles could potentially be miscorrelated

facies analysis of the kosi megafan deposits abstract the kosi river shows distinct changes in its channel pattern from chatra where the river enters the indogangetic plains to kursela where it joins the ganga river i e gravelly sandy braided zone 1 sandy braided zone 2 and straight zone 3 to meandering zone 4 facies analysis of the kosi channel deposits suggests that in zones 1 and 2 mid channel bars islands side bars 3 d dunes and various types of linguoid dunes are the most common features large linguoid dunes with lengths of up to 1 km and with superimposed smaller 3 d dunes are also common the deeper parts of the channel are probably characterized by longitudinal bars in zone 1 and sandwaves in zone 2 lateral accretion of sandy bars is a significant process in these zones zone 3 is characterized by side bars with deposition by lateral accretion as on point bars linguoid dunes may migrate up a side bar or move across it subparallel to the main channel thalweg the uppermost sedimentary sequence 8 10 m thick of the kosi megafan consists of mainly sands and minor gravels in the proximal northern half and sand and mud 45 vol in the distal southern half of the megafan this downfan trend reflects the change from braided to straight channel pattern numerous spring fed streams rework the surficial sediments of the megafan and produce a fining upward sequence up to 4 7 m thick on top of braided straight channel deposits of the megafan

the distribution of rivers to terrestrial sinks implications for sediment routing systems abstract empirical observations used to constrain controls on large global modern river systems typically use catchment delineations depicting drainage patterns of rivers to oceans a key component in the spatial and temporal discharge of sediment to oceans are terrestrial sinks that act as buffers and sequestrate sediment and nutrients along its route however a global catchment model depicting the drainage patterns of rivers to terrestrial sinks does not currently exist we propose a new global terrestrial sink catchment gtsc database that delineates the distribution of high resolution global river networks in relation to mapped modern terrestrial sinks the results show a distinct set of characteristics defining the morphology climate lithology and sediment discharge of source catchments contributing to terrestrial sinks by tectonic regime foreland intracratonic extensional and strike slip tectonic regimes are characterized by small numerous densely spaced and wide source catchments where the largest source catchment contributes on average 50 43 36 and 36 respectively of the total suspended sediment load forearc and passive margin tectonic regimes are characterized by few large source catchments where the largest source catchment contributes on average 64 and 63 of the total suspended sediment load in contrast to forearc and passive margin settings foreland intracratonic extensional and strike slip settings show source catchments with a range of lithologies and a dominance of seasonal climates which will likely increase along strike variability in sediment discharge to their terrestrial sink the variability of along strike sediment discharge sediment composition and source derived perturbations in sediment discharge to the terrestrial sink will influence the sediments stored and propagation of sediment discharge signals on geological timescales marine sedimentary successions and the sediment routing system likely represents the characteristics of remobilized terrestrial sink sediments during millennial scale perturbations in water discharge the gtsc database provides a valuable resource to further our quantitative understanding on the role of the terrestrial sink on the broader sediment routing system

episodic overbank deposition as a dominant mechanism of floodplain and delta plain aggradation the common view that frequent overbank flooding leads to gradual aggradation of alluvial strata on floodplains and delta plains has been challenged by a variety of studies that suggest that overbank aggradation occurs in a strongly episodic fashion however this remains a largely untested hypothesis due to the difficulty in establishing age models with sufficiently high resolution here we use 39 optically stimulated luminescence osl ages from proximal overbank deposits in the mississippi delta to demonstrate for the first time that alluvial aggradation over centennial to millennial time scales is predominantly episodic with aggradation rates of 1 4 cm yr that can persist for centuries osl ages from three separate study areas produce age clusters that are distinctly different yet complement each other these findings suggest that a substantial portion of the continental stratigraphic record consists of patchworks of relatively discrete centennial to millennial scale sediment bodies assembled by autogenic processes

large scale architecture in non marine basins the response to the interplay between accommodation space and sediment supply sedimentary successions of non marine basins can be considered in terms of accommodation space and sedimentary supply changes changes in accommodation space controlling the large scale architecture of non marine basins are different in areas with high and low sedimentary supplies uplift of intrabasinal monoclines and anticlines reduced the available accommodation space resulting in changes in both the geometry of the depositional sequences and the large scale architecture of fluvial mudflat and shallow carbonate lacustrine deposits main drainage fluvial systems record areas with a high sedimentary supply while mudflats and shallow fluctuating lakes represent areas that received less sediment two end members in the large scale architecture of main drainage fluvial system in the almazan basin spain are i ribbon shaped channel fills with low interconnectivity which pass laterally into mudflats dominated by mudstones and evaporites and into palustrine and shallow carbonate lacustrine deposits mainly in the a2 depositional sequence and ii sheet like channel fills with high interconnectivity laterally correlated with stacked calcretes in the marginal mudflats in the upper part of a3 ribbon shaped channel fills formed in areas of high accommodation space and sheet like channel fills formed in areas of reduced accommodation space

remote sensing of breaking wave phase speeds with application to non linear depth inversions abstract a number of existing models for surface wave phase speeds linear and non linear breaking and non breaking waves are reviewed and tested against phase speed data from a large scale laboratory experiment the results of these tests are utilized in the context of assessing the potential improvement gained by incorporating wave non linearity in phase speed based depth inversions the analysis is focused on the surf zone where depth inversion accuracies are known to degrade significantly the collected data includes very high resolution remote sensing video and surface elevation records from fixed in situ wave gages wave phase speeds are extracted from the remote sensing data using a feature tracking technique and local wave amplitudes are determined from the wave gage records and used for comparisons to non linear phase speed models and for non linear depth inversions a series of five different regular wave conditions with a range of non linearity and dispersion characteristics are analyzed and results show that a composite dispersion relation which includes both non linearity and dispersion effects best matches the observed phase speeds across the domain and hence improves surf zone depth estimation via depth inversions incorporating non linearity into the phase speed model reduces errors to o 10 which is a level previously found for depth inversions with small amplitude waves in intermediate water depths using linear dispersion considering the controlled conditions and extensive ground truth this appears to be a practical limit for phase speed based depth inversions finally a phase speed sensitivity analysis is performed that indicates that typical nearshore sand bars should be resolvable using phase speed depth inversions however increasing wave steepness degrades the sensitivity of this inversion method

unconfined flow deposits in distal sectors of fluvial distributary systems examples from the miocene luna and huesca systems northern spain abstract thin sheet sandstone beds in a continental succession may be the products of unconfined overbank flow or deposition in lacustrine environments in the distal parts of fluvial distributary systems these two settings may be intercalated recording fluctuations in lake level in response to climatic changes field studies of the luna and huesca fluvial distributary systems in the miocene of the ebro basin spain are here used to characterise sheet sandstone deposited in distal fluvial and lake margin environments in this study we document the facies and relationships between 322 individual sandbodies deposited in both alluvial settings as sheetfloods and in lacustrine settings as deltaic lobes the alluvial sandstone sheets were deposited from lateral and frontal sheetflood events when unconfined flow replaced channelised flow as the main transport mechanism the term sheetflood is used here to refer to sub aerial unconfined turbulent flow events that undergo expansion thinning and deceleration with increasing radial distance from source the depositional process is similar to modern floodouts and terminal splays of the channel country and lake eyre central australia such a process was thought to be the dominant depositional mechanism during lake lowstands the sheets formed in the lacustrine setting are interpreted as deltaic sediments deposited in a shallow gradient lake similar to the modern day volga delta caspian sea shallow water friction dominated deltaic processes are thought to have been the primary depositional mechanism in the distal sectors of the fluvial systems during lake highstands

abrupt deep sea warming palaeoceanographic changes and benthic extinctions at the end of the palaeocene a remarkable oxygen and carbon isotope excursion occurred in antarctic waters near the end of the palaeocene 57 33 myr ago indicating rapid global warming and oceanographic changes that caused one of the largest deep sea benthic extinctions of the past 90 million years in contrast the oceanic plankton were largely unaffected implying a decoupling of the deep and shallow ecosystems the data suggest that for a few thousand years ocean circulation underwent fundamental changes producing a transient state that although brief had long term effects on environmental and biotic evolution

lower eocene alluvial paleosols willwood formation northwest wyoming u s a and their significance for paleoecology paleoclimatology and basin analysis abstract the lower eocene willwood formation of northwest wyoming is a 700 m thick accumulation of alluvial floodplain and channel mudstones and sandstones nearly all of which show paleopedogenic modifications pedogenesis of willwood sandstones is indicated by taproot and vertebrate and invertebrate bioturbation early local cementation by calcium carbonate and thin illuviation cutans on clastic grains pedogenesis in willwood mudstones is indicated by plant bioturbation insect and other invertebrate burrow casts and lebensspuren free iron aluminum and manganese mobilization including hydromorphic gleying sesquioxide and calcareous glaebule formation in lower parts of the solum presence of clay rich and organic carbon rich zones and well differentiated epipedons and albic and spodic horizons probable a horizons are also locally well developed occurrence of variegated paleosol units in thick floodplain mudstone deposits and their association with thin lenticular and unconnected fluvial sandstones in the willwood formation of the central and southeast bighorn basin suggest that these soils formed during times of rapid sediment accumulation the tabular geometry and lateral persistence of soil units as well as the absence of catenization indicate that willwood floodplains were broad and essentially featureless all willwood paleosols were developed on alluvial parent materials and are complex in that b horizons of younger paleosols were commonly superimposed upon and mask properties of suspected a and b horizons of the next older paleosols the soils appear to be wet varieties of the spodosol and entisol groups aquods and ferrods and aquents respectively though thick superposed and less mottled red purple and yellow paleosols resemble some ultisols most willwood paleosols resemble warm temperate to subtropical alluvial soils that form today under alternating wet and dry conditions and or fluctuating water tables the up section decrease in frequency of gley mottles increase in numerical proportion and thickness of red versus orange coloration and increase in abundance of calcrete glaebules indicate better drained soils and probably drier climate in late willwood time this drying is believed to be related to creation of rain shadows and spacing of rainfall but not necessarily decrease in absolute rainfall due to progressive tectonic structural elevation of the mountainous margins of the bighorn basin

transient drying during the paleocene eocene thermal maximum petm analysis of paleosols in the bighorn basin wyoming abstract the paleocene eocene thermal maximum petm was a transient episode of global warming that occurred at the paleocene eocene boundary the event is marked by a sharp decline in carbon isotope values that is globally recognized from marine and continental sections the negative isotope excursion has been attributed to the release of methane hydrates from oceanic sediments although studies concur that temperatures rose during the petm changes in precipitation are not well understood alluvial paleosols in the bighorn basin that span the petm interval contain a continuous and highly resolved record of climate including information on precipitation they show a significant but transient decrease in precipitation at the onset of the petm but a gradual return to pre petm levels by the end of the interval the paleosols also show additional although less dramatic wet dry cycles within the petm interval that may correspond to precessional cycles that have been identified in the marine record of the petm this study counters interpretations of increased precipitation for wyoming at this time and shows the importance of detailed case studies of continental strata to test climatic generalizations and models that have been developed for petm precipitation patterns

parabolic megadunes in a subtropical quaternary inland dune field southwestern pampas argentina abstract the utracan paleo dune field la pampa province argentina southern south america was examined by remote sensing morphometric analyses and field surveys as a case study of complex megadunes of inland deserts the paleo dune field is within the utracan argentino valley one of the transverse valleys of la pampa province excavated into a regional structural plain similar paleo dune fields occur within these valleys utracan dunes are mostly stabilized by grasses deeply disturbed by cattle grazing and agriculture the paleo dune field is formed by complex parabolic megadunes with superimposed dunes parabolic megadunes present lengths of trailing arms of 3 3 12 9 km widths between them of 2 2 9 km and heights of 7 38 m the position of the dune noses at the northeastern tip of the bedform and measured sw ne orientation of arms indicate a mean transport direction to azimuth 68 2 above the parabolic arms and isolated in the paleo dune field there are compound blowout dunes clusters of several blowouts forming a larger bedform they show the depositional lobes to the ne with a measured mean transport direction to azimuth 58 1 the sw ne longitudinal length varies between 324 and 1302 m and the nw se transverse length between 114 and 622 m other parabolic arms show low

detection of wave groups in sar images and radar image sequences the properties of individual wave groups in space and time utilizing synthetic aperture radar sar images and nautical radar image sequences are studied this is possible by the quantitative measurement and analysis of wave groups both spatially and spatio temporally the sar with its high spatial resolution and large coverage offers a unique opportunity to study and derive wave groups in addition to sar images nautical radar image sequences allow the investigation of wave groups in space and time and therefore the measurement of parameters such as the group velocity the detection of wave groups is based on the determination of the envelope function which was first adopted for one dimensional 1 d time series by longuet higgins the method is extended from 1 d to spatial and spatio temporal dimensions to derive wave groups in images and image sequences to test the algorithm wave groups are derived from sar images and two radar image sequences recorded at locations in deep and shallow water it is demonstrated that the algorithm can be employed for the determination of both location and size of wave groups from radar images investigating the detected wave groups in radar image sequences additionally allows the measurement of the spatial and temporal development of wave groups and their extension and phase velocities comparison of measured wave group velocities in shallow and deep water gives a deviation of the average value from the group velocities resulting from linear wave theory and shows a clear oscillation of the group velocities in two dimensions

ocean surface determination from x band radar image sequences 1 an empirical inversion method is presented for determination of time series of ocean surface elevation maps from nautical radar image sequences the method is based on the determination of the surface tilt angle in antenna look direction at each pixel of the radar images thereby in situ sensors are not required an external calibration is not necessary a conventional nautical x band radar operating at grazing incidence and horizontal polarization in transmit and receive is used as a sensor radar image sequences with their high spatial resolution and large coverage offer a unique opportunity to derive and study individual waves and wave fields in space and time and therefore allow the measurement of individual wave parameters and wave groups for validation of the inversion scheme the significant wave heights derived from the inverted radar data sets and from colocated wave records are compared it is shown that the accuracy of the radar retrieved significant wave height is within the accuracy of the in situ sensors furthermore a wave elevation time series is directly compared to a buoy record to show the capabilities of the proposed method

shallow water bathymetry derived from an analysis of x band marine radar images of waves image sequences of surface gravity waves are readily produced by standard marine x band radars these image sequences contain a great deal of information regarding wave parameters and their variation over an area by approaching the analysis of such data using image analysis techniques it is possible to map the variations in wave behaviour in a shallow water area wave celerity and direction can be mapped and inversion algorithms based on linear wave theory used to infer the underlying bathymetry knowledge of the period of the waves is necessary for the analysis and this can also be calculated from the radar data although there is some discrepancy between the figures derived from radar data and from an offshore s4dw instrument these discrepancies are investigated and the results presented three days of data from the holderness ii deployment during 1995 have been analysed and estimates of the bathymetry produced the calculated depths show a mean water level comparable to that read off an admiralty chart for the area and a tidal signal is also clearly superimposed on the data giving confidence in the water depths derived using this technique

a relationship between alluvial backswamps and avulsion cycles an example from the willwood formation of the bighorn basin wyoming abstract stratigraphically limited intervals from the lower eocene willwood formation contain laterally extensive carbonaceous shales and ribbon sandstone networks associated with channel avulsion we present data from one such interval that documents the avulsion sequence vertical sections measured along the outcrop of this interval are similar and comprise a basal carbonaceous shale overlain by fine grained deposits on which weakly developed hydromorphic paleosols formed the paleosols enclose and are locally incised by ribbon sandstones some of which cut down to and partly through the carbonaceous shale the ribbons have width thickness ratios between 3 and 13 some ribbons cluster at a particular stratigraphic level which together with paleocurrent trends suggests that they formed channel networks sections are capped by yellow brown paleosols showing moderate pedogenic development we suggest that the carbonaceous shales developed in low lying topogeneous swamps in distal portions of the floodplain far from the trunk channel such a location set limits on the sediment that they received the mudrocks with weakly developed paleosols and associated ribbon sandstones are interpreted as crevasse splay complexes resulting from avulsion of the trunk river the ribbon sandstones represent ancient feeder channels of the avulsion complex the rapid influx of avulsion deposits appears to have been crucial to preserving the organic material and this study reveals an important and as yet uncharacterized link between trunk channel processes and the accumulation of organic rich deposits in distal alluvial swamps similar deposits are found in other stratigraphic units in the rocky mountain region and the development of these and other organic rich deposits should be reassessed in terms of channel avulsion

spatial and temporal evolution of a terminal fluvial fan system the permian organ rock formation south east utah usa the recognition of terminal fluvial systems otherwise termed terminal fans or distributary fluvial fan systems preserved in the ancient rock record is based primarily on the recognition of facies characteristics indicative of a progressive downstream decrease in i fluvial discharge ii channel depth and width iii lateral and vertical connectivity of channel fill elements and iv evidence for channellized flow and a systematic increase in i evidence for sheetflood deposition ii aeolian and or playa deposits and iii channel bifurcation however despite these criteria having been applied previously to a variety of outcrop successions there is still no unifying facies model that adequately accounts for the complex stratigraphic architectural relationships expected for such systems based on the varied styles of fluvial activity and system interaction known from modern examples moreover few previous studies have given significant consideration to the long term temporal evolution of terminal fluvial fans these issues are addressed by this study of the permian leonardian artinskian organ rock formation of the paradox basin south east utah a detailed stratigraphic framework based on 84 sedimentary logs demonstrates proximal to distal variations in sedimentary style integration of these data with high resolution architectural panels depicting the geometry and facies characteristics of individual fluvial elements has enabled the development of a series of depositional models that account for both the spatial and temporal evolution of the system and which are representative of i initial progradation of the fluvial system into the paradox foreland basin ii retreat of the fluvial system and expansion of a distal aeolian dune system iii the final phase of fluvial progradation following aeolian dune deflation and iv the final retrogradation of the fluvial system back towards the hinterland

quantification of a distributive fluvial system the salt wash dfs of the morrison formation sw u s a abstract recent analysis of modern aggradational continental sedimentary basins reveals that sedimentation patterns are dominated by distributive fluvial systems dfss the salt wash member of the late jurassic morrison formation has previously been described as a fan shaped fluvial system this study characterizes facies variations across the salt wash dfs to quantitatively test predicted trends in conceptual dfs models notable proximal to distal trends include a change in total thickness of the fluvial succession from 174 m to 40 m and an average grain size from coarse sand to silt while the percentage of sand decreased from 70 in the proximal region to 8 in the distal region the proportion of amalgamated channel belt deposits decreased from 67 to 0 while floodplain facies and lacustrine deposits increase 38 to 94 and 0 1 to 7 respectively a downstream decrease in average channel belt thickness 15 m to 3 8 m from thickest to thinnest and average story thickness 7 7 m to 2 3 m from thickest to thinnest is also recorded significant downstream changes in deposit architecture were also noted with proximal regions dominated by stacked channel belt deposits with a high degree of amalgamation distal deposits are dominated by floodplain muds and sheet sandstones and sparse ribbon channels with little to no amalgamation of channel deposits this study provides quantified information for an ancient dfss with the aim of providing a dataset that can be used for objective comparison between different dfss as well as providing numerical data to aid resource exploration and modelling efforts

avulsion deposits in lower eocene alluvial rocks bighorn basin wyoming abstract eocene alluvial rocks in the northern bighorn basin can be subdivided into three major kinds fine grained deposits on which cumulative paleosols developed lithologically heterogeneous packages associated with immature paleosols and major sheet sandstone bodies the heterogeneous packages which alternate vertically with the cumulative paleosols are dominated by fine grained deposits and also contain ribbon sandstone bodies and thin 1 m sheet sandstone bodies most ribbon sandstones are less than 3 m thick and are more common in the middle and upper parts of the packages cut and fill deposits with fine grained fills are locally important because the lithologic packages are readily apparent in the field because of the immature or simple paleosols developed on the fine grain d facies they are referred to as simple paleosol packages the major sheet sandstones were deposited by meandering trunk rivers and locally overlie and truncate the other deposits contrary to classical models of meandering streams only a portion of the fine grained rocks in the study area were deposited by overbank flooding of a trunk channel on the basis of their stratigraphic position and few ribbon sandstones the upper parts of some simple paleosol packages are interpreted as ancient levee deposits associated with a trunk channel farther from the trunk channel overbank floods deposited alluvium on which the cumulative paleosols formed the greater parts of the simple paleosol packages including their fine grained deposits were deposited rapidly during channel avulsion ribbon sandstone bodies represent ancient splay channels on the avulsion belt simple paleosol packages in the willwood formation support the contention of smith et al 1989 that n many meandering river systems a significant portion of the fine grained deposits were deposited as the trunk channel avulsed deposits that resemble the simple paleosol packages may provide a means of recognizing avulsion episodes in other alluvial sequences

analysis of fluvial architecture in the blackhawk formation wasatch plateau utah u s a using large 3d photorealistic models abstract there are numerous allocyclic and autocyclic factors which influence fluvial sandbody geometry unraveling the relative importance of such factors is challenging because fluvial systems can migrate and avulse across significant distances on the floodplain so that collecting datasets that cover a large enough area with sufficient detail is difficult this problem has been addressed by acquiring an oblique helicopter mounted lidar survey over 16 km of exposed sections from cretaceous coastal plain deposits cropping out in the wasatch plateau of east central utah the exposures of the blackhawk formation occur in steep cliffs which are continuous for several tens of kilometers and have been previously inaccessible for study the recorded lidar data were used to build detailed photorealistic models virtual outcrops from which quantitative dimensional data on fluvial architectural elements mostly sandstone channel bodies were collected those channelized bodies show significant variation in width and thickness 26 of the sandbodies were identified as being multistory channel bodies with a thickness of 9 1 m 4 67 m 1 and a width of 142 6 m 180 7 m which are significantly larger than the measured single story sandbodies 5 9 m and 96 9 m respectively 50 of all sandbodies have aspect ratios smaller 13 1 and the highest values reach 78 1 the spatial constraint of the 397 fluvial sandbodies enabled the recognition of a series of vertical trends within the dataset these trends include a subtle upward increase in width and thickness of both the mean and maximum values this is coupled with a general upward decrease in the number of sandbodies and results in a broadly constant channel to overbank ratio a clear correlation between wider channels with increased distance to the shoreline could also be documented these observations can be explained by considering the entire blackhawk formation as the deposits of a large distributive fluvial system in this model the key control on channel architecture is the distance to the shoreline contrasting with previous interpretations of the blackhawk depositional system in which the rate of accommodation creation in the coastal plain was thought to be the key control on channel geometry and stacking patterns

ocean wind fields retrieved from radar image sequences 1 the dependency of radar backscatter on the surface wind field is investigated using a nautical x band radar operating at grazing incidence and horizontal polarization in transmit and receive this resulted in development of an algorithm for wind retrieval from nautical radar image sequences the algorithm consists of two parts in the first part wind directions are extracted from wind induced streaks that are in line with the mean surface wind direction these streaks are visible in the temporal integrated radar images at scales between 100 and 500 m the orientation of the streaks is determined from the local gradients which are derived from the radar images smoothed and reduced to the appropriate scales in the second part wind speeds are derived from the backscatter of the temporal integrated radar image sequence and the radar retrieved wind direction the dependency of the radar backscatter on the local surface wind and geometry of the radar is parameterized by training a neural network the algorithm is applied to radar image sequences acquired by a nautical x band radar mounted aboard an offshore platform in the north sea the radar derived winds are validated by comparison to in situ wind data measured at the platform the comparison of wind directions resulted in a correlation of 0 99 with a standard deviation of 14 2 for wind speeds the correlation is 0 97 with a standard deviation of 0 85 m s 1 in contrast to traditional offshore wind sensors the retrieval of the wind field from the backscatter of the ocean surface makes the system independent of the sensors motion and installation height and reduces the effects due to platform induced blockage and turbulence effects

multi scale classification of fluvial architecture an example from the palaeocene eocene bighorn basin wyoming this work was supported by phase 2 of the fluvial systems research group bp bg chevron conocophillips and total mgms thanks the sao paulo research foundation fapesp 2014 13937 3 the authors also wish to thank numerous residents of the bighorn basin for their kind hospitality and access to land we also thank john howell for discussions on fluvial geometries and nomenclature and isobel buchanan and alistair swan for assistance in the field comments from reviewers andrew miall luca colombera and an anonymous reviewer greatly improved this manuscript

astronomical climate control on paleosol stacking patterns in the upper paleocene lower eocene willwood formation bighorn basin wyoming the willwood formation of the bighorn basin wyoming usa is a thick succession of upper paleocene and lower eocene fluvial floodplain sandstones and mudstones reddish paleosols formed on the floodplain mudstones alternate rhythmically on various scales with heterolithic intervals of small channel sandstones and mudstones showing weak pedogenesis spectral analysis of redness in the willwood successions at polecat bench and red butte reveals significant spectral peaks corresponding to cycle thicknesses of 8 and 3 m the 8 m cycle reflects distinct clusters of 3 5 paleosols age constraints show that the period of this cycle closely matches the 21 k y climatic precession cycle the 3 m cycle corresponds to individual paleosols with a period of 7 8 k y this period is similar to millennial scale sub milankovitch cycles found in marine and lacustrine successions of pliocene pleistocene age precession and millennial scale climate variations probably affected paleosol development through cyclic changes from predominantly overbank to predominantly channel avulsion deposition with the latter periodically halting soil formation because of high sediment accumulation a new age model was developed for the paleocene eocene carbon isotope excursion cie at polecat bench based on the precessional origin of paleosol clusters the main body of the cie spans 5 5 precession cycles or 115 k y and the recovery tail of the cie spans 2 precession cycles or 42 k y this outcome is consistent with and independently confirms recent estimates of cie duration based on deep sea cores

alluvial response to the paleocene eocene thermal maximum climatic event polecat bench wyoming u s a abstract the stratigraphic interval spanning the paleocene eocene thermal maximum in the northern bighorn basin wyoming shows changes in the alluvial record that can be tied to a high resolution climate record the complexity and stratigraphic spacing of paleosols change through the study section comparison to the climate record reconstructed from paleosols indicates the changes correspond to paleocene eocene thermal maximum climatic fluctuations in particular the middle of the section contains thick welded paleosols and thin avulsion deposits that link to times of well drained floodplains and lower mean annual precipitation stratigraphic intervals below and above the main part of the paleocene eocene thermal maximum interval correspond to times of less well drained floodplains and higher mean annual precipitation these strata contain thinner paleosols and thick avulsion deposits differences in paleosol complexity and spacing suggest that sediment flux to the depositional site varied in response to precipitation fluctuations associated with the paleocene eocene thermal maximum welded paleosols and thin avulsion deposits indicate reduced floodplain accretion during deposition of the middle of the paleocene eocene thermal maximum intervals with widely spaced paleosols indicate more rapid accretion we hypothesize that drier episodes associated with warming caused reduced vegetation in source areas and promoted erosion and increased sediment yield because precipitation was reduced much of that sediment was stored in upstream reaches of the fluvial system rather than moving to the depositional basin welded paleosols formed because of diminished sediment supply to the basin with a return to wetter conditions during the recovery phase of the paleocene eocene thermal maximum upstream water flux increased stored sediment moved to the basin and vertically spaced thinner paleosols developed the results demonstrate how vertical sections of alluvial paleosols can provide information on how climate fluctuated through time and how the fluvial system responded to climate change

processes facies and architecture of fluvial distributary system deposits abstract there is evidence from the stratigraphic record of examples of fluvial deposits that were the products of deposition from river systems which had decreasing discharge down flow and transitions from proximal channelised to distal unconfined flow these deposits form fan shaped bodies several tens of kilometres in radius and their stratigraphic architecture is aggradational with no evidence of deep incision driven by base level fall the fluvial systems that generated these deposits formed under conditions for which there is no complete analogue today an endorheic basin with a relatively arid climate adjacent to an uplifted area with higher precipitation a conceptual model for fluvial systems of this type has therefore been built on the basis of outcrop examples and a consideration of the controls on sedimentation proximal areas are characterised by amalgamated coarse pebbly and sandy channel deposits with little preservation of overbank facies channel dimensions are generally smaller in the medial areas but sizes are variable deposits are of braided meandering and simple channels which show varying degrees of lateral migration the channel fills may be mud or sand with overbank flow processes playing an important role in filling channels abandoned on the floodplain after avulsion the proportion of overbank deposits increases distally with sheets of sand deposited as lateral and terminal splays by unconfined flow interconnection of sandstone bodies is poor in the distal areas because channel fill bodies are sparse small and are not deeply incised the radial pattern of the sediment body forms by the repeated avulsion of channels active channels build up lobes on the alluvial plain and rivers switch position to follow courses on lower lying areas the term fluvial distributary system is here used to describe a river system which has a downstream decrease in discharge and has a distal zone which is characterised either by terminal splays on to a dry alluvial plain or a lake delta during periods of lake highstand

paleogeographic and paleotectonic setting of laramide sedimentary basins in the central rocky mountain region in the rocky mountain region between central montana and central new mexico sedimentologically isolated nonmarine basins were produced by basement deformation during the laramide orogeny within the area formerly occupied by a broad late cretaceous foreland basin in which laterally continuous marine facies had accumulated previously laramide structures of varying trend and scale reflect heterogeneity of crustal strain caused by shear between the continental lithosphere and an underlying subhorizontal slab of subducted oceanic lithosphere laramide basins include perimeter basins along the cratonic periphery of the arcuate laramide province axial basins along a north south intramontane trend and ponded basins located farther west closer to the overthrust belt twelve specific stratigraphic and sedimentologic criteria for the onset duration and termination of laramide deformation allow the chronology of basin development to be inferred independently for each basin maastrichtian initiation of laramide deformation was approximately synchronous throughout the laramide province but termination of laramide deformation was systematically diachronous from north to south between early and late eocene time widespread eocene erosion surfaces truncate syntectonic laramide sequences and are overlain by largely volcanic and volcaniclastic post laramide strata of eocene age in the north and oligocene age in the south fluvial depositional systems draining toward the great plains were dominant in perimeter and axial basins but ponded basins were occupied at times by large lakes that served as regional sediment traps paleocene drainages from ponded basins also led eastward toward the continental interior but partly interconnected lakes that developed within several ponded basins by mid eocene time were either closed hydrologically or else they drained westward into the tyee paleoriver of the pacific northwest

precession scale cyclicity in the fluvial lower eocene willwood formation of the bighorn basin wyoming usa little is known about controls on river avulsion at geological time scales longer than 104 years primarily because it is difficult to link observed changes in alluvial architecture to well defined allogenic mechanisms and to disentangle allogenic from autogenic processes recognition of milankovitch sale orbital forcing in alluvial stratigraphy would provide unprecedented age control in terrestrial deposits and also exploit models of allogenic forcing enabling more rigorous testing of allocyclic and autocyclic controls the willwood formation of the bighorn basin is a lower eocene fluvial unit distinctive for its thick sequence of laterally extensive lithological cycles on a scale of 4 to 10 m intervals of red palaeosols that formed on overbank mudstones are related to periods of relative channel stability when gradients between channel belts and floodplains were low the intervening drab heterolithic intervals with weak palaeosol development are attributed to episodes of channel avulsion that occurred when channels became super elevated above the floodplain in the deer creek amphitheater section in the mccullough peaks area these overbank and avulsion deposits alternate with a dominant cycle thickness of ca 7 1 m using integrated stratigraphic age constraints this cyclicity has an estimated period of ca 21 6 kyr which is in the range of the period of precession climate cycles in the early eocene previous analyses of three older and younger sections in the bighorn basin showed a similar 7 to 8 m spacing of red palaeosol clusters with an estimated duration close to the precession period intervals of floodplain stability alternating with episodes of large scale reorganization of the fluvial system could be entirely autogenic however the remarkable regularity and the match in time scales documented here indicate that these alternations were probably paced by allogenic astronomically forced climate change

wind retrieval from shipborne nautical x band radar data in this paper we study the retrieval of wind information from nautical x band radar data in contrast to previous studies where data from stationary research platforms were used this study focuses on data from a moving platform encountering a larger variety of conditions than a platform at a fixed location compared to traditional in situ sensors wind data derived from nautical radar images are much less susceptible to air flow distortion by the platform since the images cover a large area around the ship images collected with a standard nautical hh polarized x band radar operating at grazing incidence exhibit a single intensity peak in upwind direction the wind retrieval method developed here uses a harmonic function that is least squares fitted to the radar backscatter intensity as a function of antenna look direction the upwind direction is given by the direction that corresponds to the peak of the fitted function an empirical model function is derived to retrieve the wind speed from the average radar backscatter intensity contrary to wind retrieval methods that have been proposed before this approach is well suited for data acquired from a moving platform as it functions well even if the radar field of view is partially shadowed and does not require ship motion correction here we focus on data that were collected during two storms using the first storm to derive and the second to test the empirical model functions the method is validated using measurements from two ship based anemometers

paleohydrologic response to continental warming during the paleocene eocene thermal maximum bighorn basin wyoming abstract geologically rapid global warming occurred during the paleocene eocene thermal maximum petm 56 ma several studies have argued that important changes occurred in the hydrological cycle during the petm but results have been inconsistent ranging from global increases in humidity to drier conditions changes in paleosols during the petm in the southeastern bighorn basin document major drying during the body of the event paleosol changes also suggest transitional episodes of climate change that both preceded and followed the petm qualitative semi quantitative and fully quantitative analyses of a 70 m thick interval of paleosols provide a high resolution record of changes in soil moisture and precipitation those changes are compared to changes in temperature determined from 18o values of tooth enamel from the mammal coryphodon a distinct shift to drier soils occurred just prior to the petm a conclusion that is consistent with previous observations that warming began before the onset of the negative carbon isotope excursion associated with the petm paleosols show a progressive drying trend into the lower part of the petm and become even drier in the upper part of the body of the petm purple red paleosols that appear during the recovery phase of the petm indicate wetter soils although they are better drained than paleosols below the onset the purple red paleosols continue for 15 m above the recovery and indicate that wetter soil conditions persisted after the recovery it is not clear whether changes in the paleosols that preceded and followed the petm reflect global forcing factors like orbital cycles or release of carbon that lacks an isotopic label however such mechanisms would provide a unifying explanation for shifts seen in continental and marine environments

mudrock dominated fills formed in avulsion splay channels examples from the willwood formation wyoming mudrock dominated channel fills are common features of the fluvial palaeogene willwood formation of wyoming these fills are small on average 30 m wide and 3 m deep and they vary from simple plugs to more lithologically complex fills with internal scour surfaces some fills preserve plant material and others show pedogenic modification all fills are located within metre thick intervals of weakly pedogenically modified mudstones that surround ribbon sandstones the intervals have previously been attributed to channel avulsion the fine grained channel fills are interpreted as crevassesplay feeder channels within these avulsion deposits variation in fill type particularly the presence of pedogenic features appears to be related to floodplain drainage possible factors that influenced drainage were basin position of the fills and palaeogene climate fluctuations although the role of either is not unequivocal in general channel fills with sombre colours and preserved plant detritus indicating poorly drained conditions dominate locations that were proximal to the palaeogene basin axes fills that contain root traces red and yellow brown matrix colours and mottling which indicate pedogenic modification and episodic subaerial exposure of the sediment dominate locations that were more distal to the palaeogene basin axes eocene climate fluctuations particularly episodes of global warming may have been a secondary control on the kind of fill that developed mudrock dominated channel fills have not been described previously from ancient avulsion deposits their common presence in the willwood formation suggests that they are a typical component of avulsion belts and that similar channel fills in other stratigraphic units should be considered with regard to channel avulsion the variety of fills observed in the willwood formation indicates that avulsion belt channels can experience very different fill histories the descriptive details of fills provided here should help in their recognition elsewhere in addition the nature of the channel fill provides important information on ancient drainage conditions in the avulsion belt pedogenically modified channel fills have been recognized only rarely from the stratigraphic record their presence throughout the willwood formation suggests that they should exist in other alluvial successions and may have been overlooked previously they indicate that periods of sediment exposure alternated with episodic influxes of water and sediment in an active avulsion

basin scale predictive models of alluvial architecture constraints from the palaeocene eocene bighorn basin wyoming usa this work was supported by phase 2 of the fluvial systems research group bp bg chevron conocophillips and total ae thanks the university of aberdeen for additional funding and mgms thanks the sao paulo research foundation fapesp 2014 13937 3 the authors also wish to thank numerous residents of the bighorn basin for their kind hospitality and access to land and isobel buchanan and alistair swan for assistance in the field the authors also thank reviewers luca colombera and sian davies vollum and ae christopher fielding for helpful comments on this manuscript

controls on synorogenic alluvial fan architecture beartooth conglomerate palaeocene wyoming and montana late palaeocene uplift of the beartooth range in northwestern wyoming and southwestern montana generated the beartooth conglomerate along the eastern and northeastern flanks of the range systematic unroofing sequences and intraformational unconformities folds and faults in the conglomerate attest to deposition during uplift along the eastern flank at least three ancient alluvial fan systems and a braidplain system can be distinguished on the bases of petrofacies and lithofacies the two southern fans consist of 700 m of sedimentary clast conglomerate and subordinate sandstone dominated by hyperconcentratedflow and stream flow facies the next fan to the north is dominated by plutonic and metamorphic clasts and contains abundant mud matrix supported debris flow facies as well as stream flow facies the northernmost depositional system consists of arkosic channellized fluvial conglomerate and sandstone overbank mudstone and crevasse splay sandstone units palaeocurrent data indicate eastward dispersal away from the beartooth range outstanding exposure of the beartooth conglomerate allows facies to be mapped on lateral photographic mosaics a seven fold hierarchy of bounding surfaces and enclosed lithosomes exists in the beartooth conglomerate first through fourth order surfaces are analogous to first through fourth order surfaces that recently have been documented in sandy fluvial facies with one exception sediment gravity flows are bounded by first order surfaces fifth order surfaces are either erosional e g lateral migration of fanhead trench or accretionary e g aggradation of fan surface during backfilling of trench and construction of lobes on lower fan during entrenchment on upper fan some fifth order surfaces coincide with intraformational angular unconformities and are thus the result of long term fanhead entrenchment following uplift of the upper part of the fan sixth order surfaces bound individual fan packages that are several hundred metres thick and 10 km2 in area the enclosed sixth order lithosomes are distinguishable in terms of petrofacies and lithofacies a single seventh order surface bounds the entire beartooth conglomerate lower order lithosomes are produced by intrinsic processes of fan construction fifth order lithosomes can be attributed to both extrinsic and intrinsic controls sixth and seventh order lithosomes are generated by extrinsic controls

fluvial systems in the siwalik miocene and wyoming paleogene abstract the 3 km thick miocene siwalik group himalayan foredeep in northern pakistan and the 2 km thick paleogene fort union willwood formations bighorn basin in wyoming both preserve long records of fluvial deposition adjacent to rising mountain belts depositional environments and associated habitats change across large basins along with changing physiography and with the location of different river systems that may have varied greatly in patterns of channel deposition and the drainage of adjacent floodplain areas deposits exposed in these two basins provide very different records of shifting paleoenvironments and patterns of basin filling these differences reflect distinct patterns and scales of depositional environments the nature of the exposures and the types of sedimentologic studies that have been carried out in each basin the siwalik group fills a basin that extended at least 1000 km along its axis and 150 250 km away from the mountain front comparison of siwalik deposits and modern drainages in the himalayan foredeep suggests the ancient siwalik basin was filled by large rivers that deposited low gradient sediment fans covering areas on the order of 1000 km 2 and by smaller intrafan rivers with more poorly drained floodplains despite the scale of these river systems relative to siwalik exposures in pakistan transitions between different systems have been recognized deposits of coeval river systems in the siwalik basin show pronounced differences in alluvial architecture the character of overbank deposits and the abundance and taphonomy of organic remains in contrast the bighorn basin in wyoming is a relatively small intermontane foreland basin extending 200 km along its axis and about 80 km across bighorn basin strata were deposited by a river that flowed south to north along the basin axis and by smaller rivers that flowed transverse to the basin axis much of this basin is exposed and thus it is possible to reconstruct changing patterns of deposition and environments through time in more detail than in the siwalik basin these patterns indicate changes in basin wide drainage conditions and environments through time but there are also important differences among coeval strata upsection shifts in environments and vertebrate faunas within both the siwalik and bighorn basins may reflect tectonic or climatic forcing but this comparison emphasizes the importance of recognizing deposits from different contemporaneous river systems before inferring such large scale controls on paleoecological change through time

studies of dual polarized low grazing angle radar sea scatter in nearshore regions reports on experiments featuring horizontally hh and vertically vv polarized x band marine radar sea scatter imagery in the coastal environments of bermuda and la jolla under light to moderate winds and the absence of long gravity waves these conditions allowed the study of fundamental scattering mechanisms from small scale roughness and short waves of a few meters wavelength or less shorter than the radar pulse while a large fraction of radar data collected revealed the presence of slick bands the authors analyze the radar echo of ambient background outside of the slicks sea scatter data were digitally recorded for 360 spl deg azimuthal coverage for grazing angles between 1 3 5 spl deg and were converted to normalized radar cross section nrcs or spl sigma spl deg images the hh and vv polarizations show quite different spatial texture with hh exhibiting a discrete character and vv being more nearly spatially homogeneous grazing angle dependencies are different for hh and vv upwind downwind differences of mean nrcs show ratios of just 4 6 db for vv but are equal or greater than the 16 db noise imposed limit for hh for the low wind conditions hh nrcs grazing angle characteristics are shown to correlate with biological activity indicators of the coastal waters with a fourth power dependence in relatively unproductive waters to a nearly quadratic in productive waters arguments are presented that suggest different scattering mechanisms for the two polarizations evenly distributed bragg scatter patches for vv and scatter from small asymmetric bore features for hh a multipath illumination model for small bore features is outlined and scale sizes for the small scale breakers inferred from the experimental results presented are between 2 and 4 cm in height with crest widths between 24 and 48 cm

braided rivers perspectives and problems progress towards a fuller understanding of the dynamics and deposits of braided rivers demands an interdisciplinary approach to a host of unresolved problems although many advances have been made within recent years in interpreting the mechanics of flow transport of sediment and sedimentary architecture of braided rivers many key issues remain to be addressed in particular several areas demand attention the mechanisms of braid bar initiation confluence diffluence dynamics the nature of sedimentary facies over a range of grain sizes and the influence of flow stage and aggradational regime upon the depositional architecture over a range of channel scales this paper focuses upon these issues and highlights several areas of fruitful future interdisciplinary collaboration 1993 the geological society

reservoir and aquifer characterization of fluvial architectural elements stubensandstein upper triassic southwest germany this paper aims at a quantitative sedimentological and petrophysical characterization of a terminal alluvial plain system exemplified by the stubensandstein south german keuper basin the study follows the outcrop analogue approach where information derived from outcrops is collected in order to enhance interpretation of comparable subsurface successions quantitative data on sandbody geometries porosities and permeabilities are presented in order to constrain modelling of subsurface sandbodies and permeability barriers for sedimentological characterization the method of architectural element analysis miall a d 1996 the geology of fluvial deposits springer berlin was used and modified to include poroperm facies a special photo technique with a precise theodolite survey was developed to create optically corrected photomosaics for outcrop wall maps from up to 20 000 m2 large outcrops nine architectural elements have been classified and quantified bedload mixed load and suspended load channel fills are separated the petrophysical characterization of the architectural elements integrated porosity and permeability measurements of core plugs with gamma ray measurements along representative sections it could be demonstrated that certain architectural elements show a characteristic poroperm facies four scales of sedimentary cycles have been recognized in the stubensandstein cyclic sedimentation causes changing lithofacies patterns within the architectural elements depending on their position in the sedimentary cycle stratigraphic position exerts only some paleogeographic position exerts significant influence on porosity and permeability of the sandbodies the highest poroperm values were found in proximal areas of the alluvial plain and in middle parts within sedimentary macrocycles the strong internal heterogeneity on the alluvial plain system is important for its reservoir and aquifer characteristics compartments of bedload channel sandstones in medial positions of a stratigraphic cycle represent very good reservoirs or aquifers the seals or aquicludes are formed by extensive floodplain claystones lacustrine sediments paleosols and suspended load deposits strongly cemented zones of sandstones represent aquitards

architectural elements and bounding surfaces in fluvial deposits anatomy of the kayenta formation lower jurassic southwest colorado abstract three well exposed outcrops in the kayenta formation lower jurassic near dove creek in southwestern colorado were studied using lateral profiles in order to test recent regarding architectural element analysis and the classification and interpretation of internal bounding surfaces examination of bounding surfaces within and between elements in the kayenta outcrops raises problems in applying the three fold classification of allen 1983 enlarging this classification to a six fold hierarchy permits the discrimination of surfaces intermediate between allen s second and third order types corresponding to the upper bounding surfaces of macroforms and internal erosional reactivation surfaces within the macroforms examples of the first five types of surface occur in the kayenta outcrops at dove creek the new classifications is offered as a general solution to the problem of description of complex three dimensional fluvial sandstone bodies the kayenta formation at dove creek consists of a multistorey sandstone body including the deposits of lateral and downstream accreted macroforms the storeys show no internal cyclicity neither within individual elements nor through the overall vertical thickness of the formation low paleocurrent variance indicates low sinuosity flow whereas macroform geometry and orientation suggest low to moderate sinuosity the many internal minor erosion surfaces draped with mud and followed by intraclast breccias imply frequent rapid stage fluctuation consistent with variable seasonal monsonal ephemmeral flow the results suggest a fluvial architecture similar to that of the south saskatchewan river through with a three dimensional geometry unlike that interpreted from surface studies of that river

an overview and interpretation of autocyclic and allocyclic processes and the accumulation of strata during the pennsylvanian permian transition in the central appalachian basin usa abstract autocyclic and allocyclic processes controlled the lithostratigraphy of strata that accumulated in the central appalachian foreland basin during the pennsylvanian and the transition to the permian the transition strata from bottom to top include the late pennsylvanian pittsburgh and uniontown formations of the monongahela group the waynesburg and washington formations of the dunkard group and the permian greene formation of the dunkard variations in the amount of precipitation were the predominant allocyclic control on stratigraphic variations in terrestrial organic productivity lacustrine base levels basin scale weathering water table and pedogenesis sediment supply and sedimentary geochemistry tectonic subsidence controlled accommodation space and basin configuration eustasy had little or no effect on the stratigraphy of strata deposited in this continental basin during the pennsylvanian permian transition autocyclic processes were the predominant spatial control on architecture of alluvial plain aggradation paleosols delineating regional unconformities show a gradual upward transition from kaolinitic underclay paleosols indicative of a humid climate in the late pennsylvanian monongahela group to petrocalcic paleosols indicative of a dry subhumid to semiarid climate during deposition of dunkard strata as in the monongahela group the dunkard group waynesburg and washington formations contain multi bedded nonmarine lacustrine limestones with subareal exposure features these limestones grade laterally into petrocalcic paleo vertisols in the up dip alluvial plain subareal exposure features are uncommon in centimeter scale micritic limestones in the permian greene formation equivalent up dip paleosols have been lost to erosion coal bed continuity thickness and quality also decrease up section from the very thick m and laterally continuous pittsburgh coal at the base of the monongahela group to thin cm scale and laterally discontinuous coal beds that unconformably overlie the paleosol underclay limestone complexes in the greene formation lacustrine shales and impure wacke fluvio lacustrine sandstones commonly with a weak pedogenic overprint generally overlie coal beds during accumulation of monongahela and dunkard mdg strata within the basin center unconformities at the tops of regional paleosols overlain by lacustrine strata suggest allocyclic induced repeated rise and fall of lacustrine conditions in a lacustrine fan delta complex analogous to the okavango basin and fan in namibia southern africa and or the pantanal in southern brazil during maximum lake levels progradation of fluvio deltaic systems resulted in laminated shale conformably overlain by dark shale and flat bottomed distributary mouth bar siltstones and sandstones prograding distributaries and or fluvial channels subsequently incised the flat bottom mouth bar sands where basin margin strata are preserved south of the basin center depositional environments consist of aggrading alluvial plain sequences with paleosols fluvial channel sands and flood plain deposits anastomosing fluvial systems prograded across a low gradient 1 ft mile 20 cm km alluvial plain into the basin center a weak pedogenic overprint marked by ubiquitous root penetrations occurs throughout most basin centered fluvial deposits the subtle but continuous decline in the repetition of cyclic lithostratigraphy up section in the mdg particularly in the greene formation appears to be the result of a 10 myr climate transition from the humid to dry subhumid climate cycles of the late pennsylvanian to the equable semiarid to arid climate of the middle permian in north america cyclothems common in pennsylvanian strata become less distinct up section in the dunkard because of decreasing development of underclays coal and limestone this 30 myr period of transition from the humid pennsylvanian to the arid permian has been referred to as the dyassic period

significance of different modes of rhizolith preservation to interpreting paleoenvironmental and paleohydrologic settings examples from paleogene paleosols bighorn basin wyoming u s a abstract different modes of preservation of root traces rhizoliths provide information on soil moisture regimes in alluvial paleosols in the paleogene fort union and willwood formations of the bighorn basin wyoming u s a this paper links different styles of rhizolith preservation to paleosols whose other pedogenic attributes provide information on ancient soil drainage consequently the paleodrainage significance of different rhizolith preservation patterns is established more confidently rhizoliths consisting of elongate gray mottles rhizohaloes with red rims are common in relatively well drained red paleosols the gray zones are depleted of iron fe whereas the color of the rims indicates hematite accumulation these features are typical of surface water gley processes that caused fe and manganese mn to move from the root channel outward to the soil matrix calcareous rhizocretions either calcareous tubular concretions or micro accumulations of carbonate within gray rhizotubules are also common in moderately well drained red paleosols more poorly drained purple paleosols also have rhizoliths consisting of fe depletion zones however the rhizohaloes are surrounded by yellow brown goethite rims rather than red hematitic rims in many paleosols the red and yellow brown accumulation rims were partly removed by continued depletion producing abundant irregular shaped mottles the nature of the rhizohalo and the color of the fe oxide rim provide information about the intensity of gleying that a paleosol underwent the poorly drained paleosols also show rhizoliths preserved as goethite accumulations contained within gray depletion zones indicating movement of reduced fe from the matrix towards the root channel probably as a result of groundwater gley processes the goethite accumulations are intermingled locally with lignite representing preservation of the root organic material some rhizoliths are preserved as tube shaped concentrations of small 0 1 0 2 mm diameter black spheres whose color indicates a mix of mn and fe oxides these are most common in paleosols with low chroma gray matrix colors indicating very poor drainage the very poorly drained paleosols also show rhizoliths preserved in jarosite which is an oxidation product of pyrite careful observational and geochemical analysis of rhizoliths which are common in continental deposits can help produce a clearer and more thorough interpretation of ancient drainage conditions information about degree of ancient soil wetness or moisture is important for understanding past climatic conditions and for reconstructing terrestrial paleolandscapes

paleosols in clastic sedimentary rocks their geologic applications interest in pre quaternary paleosols has increased over the past decade in large part because they have proved to be beneficial in solving diverse geological problems the majority of paleosols are described from continental deposits most commonly from alluvial strata criteria for recognizing these paleosols have been extensively described however classifying them has proved more complicated pre quaternary paleosols are generally classified according to one or more modern soil classification systems although one new classification has been proposed exclusively for paleosols to avoid problems using the modern soil classifications in addition to taxonomic classification paleosols can be categorized according to the interplay among deposition erosion and the rate of pedogenesis when they formed paleosols can be solitary if they formed during a period of landscape stability following the development of an unconformity such paleosols are commonly thick and extremely well developed more commonly paleosols are vertically stacked or multistory because they formed in sedimentary systems undergoing net aggradation if erosion was insignificant and sedimentation was rapid and unsteady compound paleosols generally formed if the rate of pedogenesis exceeded the rate of deposition composite paleosols developed thick cumulative paleosols indicate that erosion was insignificant and that sedimentation was relatively steady both autogenic and allogenic processes can influence depositional and erosion patterns and thus affect the kinds of soils that form consequently paleosols can help to interpret the history of sediment deposition and the autogenic and allogenic processes that influenced a sedimentary basin paleosols are also helpful in stratigraphic studies including sequence stratigraphic analyses they are used for stratigraphic correlations at the local and basinal scale and some workers have calculated sediment accumulation rates based on the degree of paleosol development in addition to their stratigraphic applications paleosols can be used to interpret landscapes of the past by analyzing paleosol landscape associations at different spatial scales ranging from local to basin wide in scope at the local scale lateral changes in paleosol properties are largely the result of variations in grain size and topography at the scale of the sedimentary basin paleosols in different locations differ because of basinal variations in topography grain size climate and subsidence rate paleosols are used to reconstruct ancient climates even to estimate ancient mean annual precipitation map and mean annual temperature mat ancient climatic conditions can be interpreted from modern soil analogs or by identifying particular pedogenic properties that modern studies show to have climatic significance stable carbon and oxygen isotopes are also used to interpret ancient climate and some effort has been made to estimate mat from isotopic composition on the basis of

an improved composite surface model for the radar backscattering cross section of the ocean surface 2 model response to surface roughness variations and the radar imaging of underwater bottom topography in the companion paper we have presented an improved composite surface model for the calculation of normalized radar backscattering cross sections nrcs of the ocean surface the proposed model accounts for the impact of the full two dimensional ocean wave spectrum on the radar backscatter and was shown to reproduce measured absolute nrcs values for a variety of radar configurations and wind speeds satisfactorily after some reasonable tuning of the input ocean wave spectrum this paper focuses on the modulation of the nrcs in the presence of spatially varying surface currents first the sensitivity of the nrcs to intensity variations of different ocean wave spectral components is investigated then the hydrodynamic modulation of the wave spectrum over underwater bottom topography in tidal waters is computed in different ways and the resulting radar signatures are discussed the composite surface model yields comparable radar signatures at high 10 ghz x band and low 1 ghz l band radar frequencies which is in much better agreement with experimental results than the predictions of a first order bragg scattering model on the other hand measured variations of the nrcs at high radar frequencies appear to be still underestimated in some cases which may be due to shortcomings of our description of the wave current interaction by conventional weak hydrodynamic interaction theory possible improvements of the theory are discussed and requirements for future experiments are formulated

characterizing avulsion stratigraphy in ancient alluvial deposits guidelines for identifying ancient avulsion deposits were set forth by kraus and wells kraus m j wells t m 1999 recognizing avulsion deposits in the ancient stratigraphical record in smith n d rogers j eds fluvial sedimentology vi special publication of the international association of sedimentologists vol 28 pp 251 268 building on the study by smith et al smith n d cross t a dufficy j p clough s r 1989 anatomy of an avulsion sedimentology 36 1 23 of the modern saskatchewan river system cumberland marshes central canada and serve to characterize avulsion depositional sequences in the ancient willwood and fort union formations paleogene bighorn basin nw wyoming usa we recognize however that the model is not universally applicable to avulsion dominated successions specifically systems which lack defining heterolithic avulsion deposits set forth by kraus and wells kraus m j wells t m 1999 recognizing avulsion deposits in the ancient stratigraphical record in smith n d rogers j eds fluvial sedimentology vi special publication of the international association of sedimentologists vol 28 pp 251 268 observations in several fluvial intervals suggest that the avulsion stratigraphy outlined by kraus and wells kraus m j wells t m 1999 recognizing avulsion deposits in the ancient stratigraphical record in smith n d rogers j eds fluvial sedimentology vi special publication of the international association of sedimentologists vol 28 pp 251 268 represents one category of avulsion stratigraphy found in the rock record but does not capture the nature of avulsion deposits everywhere based on observations using measured sections outcrop photo panels and aerial photographs in the willwood formation eocene wyoming and ferris formation cretaceous paleogene wyoming we present two end member categories of avulsion stratigraphy in ancient deposits stratigraphically abrupt when a main paleochannel is stratigraphically juxtaposed directly atop floodplain overbank deposits and stratigraphically transitional where crevasse splays and other non floodplain overbank deposits stratigraphically precede a main paleochannel this characterization provides a broader more inclusive way to recognize and describe avulsion stratigraphy in ancient deposits and may be an important factor to consider when modeling connectivity in fluvial reservoirs furthermore our observations show that one type of avulsion channel stratigraphy may prevail over another within an ancient basin suggesting that system wide factors such as splay proneness or avulsion style i e aggradational incisional etc slingerland r smith n d 2004 river avulsions and their deposits annual review of earth and planetary sciences 32 257 285 may be primary controls on the type of avulsion stratigraphy deposited and preserved in ancient basin fills