midshelf to surfzone coupled roms swan model data comparison of waves currents and temperature diagnosis of subtidal forcings and response abstracta coupled wave and circulation model that includes tide wind buoyancy and wave processes is necessary to investigate tracer exchange in the shelf region here a coupled regional ocean model system roms simulating waves nearshore swan model resolving midshelf to the surfzone region of the san pedro bay california is compared to observations from the 2006 huntington beach experiment waves are well modeled and surfzone cross and alongshore velocities are reasonably well modeled modeled and observed rotary velocity spectra compare well in subtidal and tidal bands and temperature spectra compare well in the subtidal band observed and modeled mid and inner shelf subtidal velocity ellipses and temperature variability determined from the first vertical complex eof ceof mode have similar vertical structure although the modeled subtidal velocity vertical shear and stratification are weaker than observed the ratio of stratification to shear is similar suggesting model vertical mixing i

lunar fast neutron leakage flux calculation and its elemental abundance dependence a numerical code has been developed to simulate fast neutron leakage flux from planetary surfaces these neutrons are produced in copious number by interactions between galactic cosmic rays and the nuclei of surface material their leakage flux spectrum depends on the composition of the upper layers of planetary bodies measurement of these neutrons allows the mapping of major compositional units this technique is successfully used on lunar prospector data to obtain global geochemical maps of the lunar surface with the help of simulations relations between soil composition and neutron fluxes in the fast energy range 500 kev 10 mev are established the numerical code reproduces correctly the measurements of fast neutrons over the moon variation in the neutron flux between highland and mare soils is calculated a simple formula is suggested to estimate quickly the integrated fast neutron leakage flux for a given soil composition

feo and tio2 concentrations in the south pole aitken basin implications for mantle composition and basin formation we use newly developed spectroscopic methods for determining feo and tio2 abundances to study the huge 2500 km diameter south pole aitken basin the floor of this basin shows iron and titanium values which are weakly correlated and largely range from 7 to 14 wt feo and from 0 5 to 1 5 wt tio2 this composition is consistent with an approximate 1 1 mixture of lower crustal material like that found elsewhere on the moon and mantle rock containing 10 16 wt feo and 0 1 wt tio2 although mantle rock appears to compose about 50 of the floor deposits models of the formation of large impact basins predict that virtually all the floor materials ought to be derived from the mantle

near surface trajectories off central and southern california the near surface circulation in the santa barbara channel and off the coast of central and southern california is described based on 20 releases of drifters drogued 1 m beneath the surface from 12 sites within the channel at bimonthly intervals this description includes small scale features of the circulation which are not part of descriptions based on moored observations or of the statistics of the drifter releases the eventual fate of drifters at long time intervals compared to the residence time in the channel about 7 days is also included in the channel the trajectories document a persistent cyclonic circulation with a typical recirculation period between 3 and 5 days in the spring currents near the mainland are weaker than near the channel islands and the overall flow is toward the southeast trajectories document the possibility for water parcels to leave the channel through the interisland passes in the late fall and winter a poleward flow with velocities often exceeding 0 5 m s 1 is confined within 20 km of the mainland between these two seasons the cyclonic tendency is enhanced although most of the drifters eventually migrate westward the trajectories of drifters released at the same time from sites only 20 km apart can be remarkably different once the drifters migrate out of the channel their trajectories can be grouped into a few patterns in spring and summer drifters tend to remain in the southern california bight their trajectories often remain close over extended periods as if they were caught in convergence zones in fall the drifters often are caught in a poleward current

new results and implications for lunar crustal iron distribution using sensor data fusion techniques remote measurements of the moon have provided iron maps and thus essential constraints for models of lunar crustal formation and mare basalt petrogenesis a bulk crustal iron map was produced for the equatorial region from apollo gamma ray agr spectrometer measurements and a global iron variation map from recent clementine spectral reflectance csr measurements both iron maps show bimodal distribution but have significantly different peak values and variations in this paper csr data have been recalibrated to pyroxene in lunar landing site soils a residual iron map is derived from the difference between agr bulk and recalibrated csr pyroxene iron abundances the most likely interpretation is that the residual represents ferrous iron in olivine this residual iron is anticorrelated to basin age with older basins containing less olivine suggesting segregation of basin basalt sources from a progressively fractionating underlying source region at the time of basin formation results presented here provide a quantitative basis for 1 establishing the relationship between direct geochemical gamma ray x ray and mineralogical near ir remote sensing data sets using sensor data fusion techniques to allow 2 simultaneous determination of elemental and mineralogical component distribution on remote targets and 3 meaningful interpretation of orbital and ground based spectral reflectance measurements when calibrated data from the lunar prospector mission are available mapping of bulk crustal iron and iron bearing soil components will be possible for the entire moon similar analyses for data from the near earth asteroid rendezvous near mission to asteroid 433 eros will constrain models of asteroid formation

objective maps of near surface flow states near point conception california abstract objective streamfunction and velocity potential maps of three commonly observed flow states near point conception california are derived from moored current meter and drifter observations the states are defined using current meter data drifter data are sorted by flow state and averaged within spatial bins to resolve their spatial structures spatial correlations of drifter data show the along shelf and cross shelf decorrelation distances are approximately 45 and 25 km respectively this information is used to make the objective streamfunction and velocity potential maps the total velocity is represented as the sum of the rotational nondivergent streamfunction component and the irrotational divergent velocity potential component the velocity derived from the streamfunction is much stronger than that derived from the velocity potential the streamfunction is sufficiently well resolved to make meaningful vorticity maps the velocity potential indicates a source term in the western santa bar

facies and fluvial architecture of a high energy braided river the upper proterozoic seglodden member varanger peninsula northern norway abstract the seglodden member late proterozoic as studied in two areas of the varanger peninsula northern norway is dominated by sand rich braided river deposits a quantitative summary of described facies emphasises the dominance of structures deposited under high energy conditions and a general absence of fine grained deposits and visible small scale sedimentary structures the sigmoidal and concave up cross stratified planar horizontally stratified and massive sandstone facies represent 80 95 of the total vertical thicknesses of the measured sections architectural elements are defined as sheet sandstone bodies and channel forms and fills and comprise simple bars transitional simple bar dune complexes dune complexes downstream accretion complexes and various types of channel deposits the seglodden fluvial system was operating in a non vegetated setting with well exposed sediment sources probably of a sedimentary origin this situation gave a very erratic discharge system with rapid runoff high denudation rate and very high sediment discharge increased flow within channels was compensated for by a broadening of the channels and it is inferred that the channels were very wide and shallow relative to their depths bounding surfaces of at least six different orders 0th 5th are interpreted within the studied successions with the third order surface as the lowest order surface that bound architectural elements as defined in this study the highest order surface 5th order is probably the result of channel belt switching due to a combination of sedimentary processes and tectonic subsidence of the basin the east and northeasterly palaeocurrent trend in the seglodden area compared to the southeasterly trend in the smellror area indicates that the axis of the depositional system changed significantly in direction basinwards over the 15 20 km distance between the two study areas the controlling mechanisms for this may be autocyclic as well as allocyclic processes although the tectonic influence on sedimentation was probably significant

sixth foray for pristine nonmare rocks and an assessment of the diversity of lunar anorthosites eleven nonmare samples are characterized generally both compositionally and petrographically five are almost certainly pristine ferroan anorthosite 10056c alkali anorthosite 14047c ferroan anorthosite 14312c anorthositic troctolite 14321c3 and granite 14321c4 and four are probably pristine norite 14318c noritic anorthosite 67215 quasi pristine ferroan anorthosite 73217c and norite 78527 five are unique anorthosites extending the diversity of lunar anorthosites considerably alkali anorthosites particularly 14047c are extremely rich in incompatible elements the first anorthosite from apollo 11 with manifestations of pristinity 10056c appears to be a normal member of the ferroan group however the first pristine ferroan anorthosites from apollo 14 and 17 to be studied in detail 14312c and 73217c both have unusually sodic plagioclase by ferroan standards with only 75 plagioclase 67215 is the first large 273 g probably pristine ferroan sample with less than 83 plagioclase the nature of the correlations between longitude and such parameters as eu and sm concentrations and sc sm ti sm and ca na ratios among pristine ant samples has been elucidated because five of the new pristine samples are from a western site apollo 14 interestingly ferroan anorthosite 14312c has ca na sc sm and ti sm ratios close to the normal ferroan values but significantly displaced in the direction of the nonferroan western pristine rocks this suggests that the composition longitude relationships are as old as the late stages of the crystallization of the putative magma ocean

impact glasses from the apollo 14 landing site and implications for regional geology 1 lunar impact glasses possess the unmodified refractory element ratios of the original fused target materials at the sites of impacts these target materials are regolith developed on different terrains and local rock types almost 800 glasses from the apollo 14 landing site have been analyzed by electron microprobe in this study these glasses show significant variation and hint at the existence of multiple terrains of differing compositions near the landing site to test this idea we have used clementine color image data to construct iron and titanium maps from which a petrologic map in an elemental system analogous to the sample database was made this map shows the regional provenance of apollo 14 samples and suggests that the highlands in the fra mauro region of the moon consist of a potassium rare earth element and phosphorus kreep rich basaltic debris layer that overlies a more feldspathic terrain in some areas this mapping effort demonstrates the efficacy of using clementine image data to place lunar sample information into a regional and ultimately global context lunar impact glasses and orbital data can provide geochemical constraints on the local and regional geology of the moon

high resolution measurements of absolute thorium abundances on the lunar surface the lunar prospector lp gamma ray spectrometer grs has been used to map the global abundance of thorium on the lunar surface a global map of absolute thorium abundances on a 2 by 2 equal area pixel scale is presented using new detector modeling results and low altitude lp data because thorium is relatively abundant in kreep rich material these data provide fundamental information regarding the locations and importance of terranes that are rich in kreep bearing materials

compositional variability on the surface of 4 vesta revealed through grand measurements of high energy gamma rays measurements of the high energy gamma ray flux emanating from asteroid 4 vesta by the dawn gamma ray and neutron detector grand have revealed variability in the near surface elemental composition of the vestan surface these observations are consistent with the presence of large 8 104 km2 regions with distinct hed like elemental compositions the results agree broadly with other global measurements such as the macroscopic neutron absorption cross section and spectral reflectance derived mineralogic maps two distinct regions with eucrite like elemental compositions have been identified the first located primarily within the lucaria and marcia quadrangles and the second within oppia quadrangle the former region is collocated with some of the oldest most heavily cratered terrain on vesta the interior of the 500 km diameter rheasilvia impact basin is found to have a composition that is consistent with diogenite like material taken together these observations support the hypothesis that vesta s original crust was composed of basaltic outflows in the form of eucritic like material and that the rheasilvia basin forming impact exposed lower crustal diogenite like material these measurements also constrain the maximum amount of mesosiderite like material to 10 for each 15 15 surface element

sedimentology and ground penetrating radar characteristics of a pleistocene sandur deposit abstract the kronhede sandur forms part of a ca 1500 km2 late pleistocene outwash system located in western jylland denmark a sedimentological study was carried out in the proximal part of the sandur the sediments were deposited during progradation of the glacier as shown by a general coarsening upward lithology terminating with a jokulhlaup episode characterized by large compound dune migration and slack water draping mapping of a more than 200 m long well exposed pitwall and ground penetrating radar measurements in a 50 200 m grid along the pitwall made it possible to outline the three dimensional geometry of the jokulhlaup deposit forming the top part of the succession the paper describes the sedimentology of the sandur deposits and the application of the ground penetrating radar technique to sedimentary architecture studies

using two and three dimensional georadar methods to characterize glaciofluvial architecture abstract the threat of pollution in the shallow subsurface has led to an increasing need to understand how complex heterogeneities in gravel aquifers influence groundwater transport to characterize these heterogeneities we have conducted extensive two dimensional 2 d and three dimensional 3 d ground penetrating radar gpr or georadar surveys in two quarries within the rhine valley of northeastern switzerland the quarries comprised gravel and sand deposited in a proglacial braided river system that followed the maximum wurm stage glaciation after the surveys the terrace walls beneath the two study sites were photographed as they were being excavated by combining information extracted from the 2 and 3 d georadar images with the outcrop photographs it was possible to correlate georadar facies with the various glaciofluvial architectural elements the dominant elements were scour pools formed at or near the confluences of two stream channels and horizontally bedded and massive gravel sheets deposited during moderate to high water flow conditions and exposed during low flow conditions architectural elements were generally elongated parallel to the mean flow directions of the ancient river system variations in the strike of their long axes reflected lateral and vertical changes in the local flow direction time slices showed structural trends not evident on 2 d georadar images and photographs data interpretation was quicker more complete and less ambiguous when georadar facies analyses were based on a combination of georadar vertical profiles and time slices than when based on georadar vertical profiles alone

sedimentary architecture of large scale jokulhlaup generated ice block obstacle marks examples from skeiðararsandur se iceland during glacial outburst floods jokulhlaups large ice blocks are often released from the glacier margin ice blocks ground at points of flow deceleration generating distinctive patterns of scour and deposition scaled to the obstacle size the large scale ice block obstacle marks produced within the proglacial zone are diagnostic of jokulhlaups we use ground penetrating radar gpr to investigate the sedimentary architecture of ice block obstacle marks generated by the november 1996 jokulhlaup at skei ararjokull iceland the gpr data reveal a varied sedimentary architecture interpreted to suggest that ice block obstacle mark sedimentology is controlled by flow conditions sediment supply and whether ice blocks are deposited in isolation or as a cluster following ice block grounding deflection of flow down and away from the obstacle develops horseshoe vortices that maintain a non depositional hollow around the obstacle whilst continued outwash deposition away from the obstacle raises the level of the surrounding sandur where ice blocks ground early during the jokulhlaup hollows are infilled with foreset beds at the up flow end and backset beds antidune distally however where ice blocks ground on the waning stage when sediment flux is reduced antidunes are not preserved and the hollow is infilled with low angle foreset beds in both cases the lee side shadow ridge is composed of pseudo anticlinal beds proximal to the obstacle where shed vortices are strong and plane beds distally where flows converge and the shed vortices weaken where flow parallel ice block clusters develop the grounding of smaller ice blocks in the lee of the initial obstacle results in only limited shadow ridge aggradation these data provide improved insight into the controls on ice block obstacle mark sedimentary architecture and allow identification of high magnitude jokulhlaups in the sedimentary record

obstacle marks produced by flow around stranded ice blocks during a glacier outburst flood jokulhlaup in west greenland the effects of glacier ice block grounding on the morphology and sedimentology of proglacial fluvial outwash were examined during a glacier outburst flood or jokulhlaup near sondre stromfjord west greenland observations made during and after the 1987 jokulhlaup both on the surface of an ice contact delta and within a confined valley sandur plain provided information about the formation of ice block obstacle marks and the significance of these bedforms for sandur morphology and sedimentology flow directions determined from obstacle mark morphology have been used successfully to chart flow direction changes on the falling limb of the jokulhlaup maximum flow depths for scour around stranded ice blocks may be given by 0 5 0 9 times the diameter of the ice block as estimated from the depth of scour the height of the obstacle shadow or the extent of ice block meltout sediments minimum flow depths can be represented by the height of the obstacle shadow above the mean bed level the internal composition of the shadow indicates the ability of the flow to transport various sizes of material into the lee of obstacles ice block obstacle marks within the distal portion of the sandur initiated waning stage channel change proximal and lateral erosion around stranded ice blocks extended downstream from the ice block forming chute channels which then captured waning stage flows resulting in significant bar incision with associated deposition of lobate or deltaic deposits it is suggested that ice block obstacle marks are important in terms of channel morphology channel morphological change and their usefulness as palaeohydrological indicators

coastal water circulation patterns around the northern channel islands and point conception california abstract the northern channel islands in california host multiple marine protected areas containing kelp forest ecosystems little is known about the water circulation onshore of the 20 m isobath we use water velocity recorded at 21 sites near the 15 m isobath at the islands and mainland during 1999 2012 to describe the water circulation on time scales of days to months the mean circulation is eastward or weak at the islands but poleward along the mainland speeds 0 10 cm s 1 the subinertial frequency along shelf flow is surface intensified and reverses direction on time scales of days in summer the flow becomes more poleward throughout the region the mean cross shelf flow profiles are strikingly similar at most sites with flow speeds 1 2 cm s 1 the mean flow near bottom in the vicinity of the kelp forests is offshore the time varying two layered response to wind is stronger up to 6 cm s 1 the flushing time of the shelf onshore of the 15 m isobath is short at most 2 dy at a few sites exposed to the prevailing wind up to 60 of the velocity variance is predictable from wind measured in the santa barbara channel in the lee of point conception or at the islands however regional wind explains little of the velocity variance during weak winds the velocity at some mainland but not island sites responds to pressure gradients measured along the mainland coast these pressure gradients are associated with local wind relaxations at pt conception not with remotely generated coastal trapped waves

a quantitative three dimensional depositional model of gravelly braided rivers a quantitative three dimensional depositional model of gravelly braided rivers has been developed based largely on the deposits of the sagavanirktok river in northern alaska these deposits were described using cores wireline logs trenches and ground penetrating radar profiles the origin of the deposits was inferred from observations of 1 channel and bar formation and migration and channel filling interpreted from aerial photographs 2 water flow during floods and 3 the topography and texture of the river bed at low flow stage this depositional model quantitatively represents the geometry of the different scales of strataset the spatial relationships among them and their sediment texture distribution porosity and permeability in the model are related to sediment texture the geometry of a particular type and scale of strataset is related to the geometry and migration of the bedform type e g ripples dunes bedload sheets bars associated with deposition of the strataset in particular the length to thickness ratio of stratasets is similar to the wavelength to height ratio of associated bedforms furthermore the wavelength and height of bedforms such as dunes and bars are related to channel depth and width therefore the thickness of a particular scale of strataset i e medium scale cross sets and large scale sets of inclined strata will vary with river dimensions these relationships between the dimensions of stratasets bedforms and channels mean that this depositional model can be applied to other gravelly fluvial deposits the depositional model can be used to interpret the origin of ancient gravelly fluvial deposits and to aid in the characterization of gravelly fluvial aquifers and hydrocarbon reservoirs

fluxes of fast and epithermal neutrons from lunar prospector evidence for water ice at the lunar poles maps of epithermal and fast neutron fluxes measured by lunar prospector were used to search for deposits enriched in hydrogen at both lunar poles depressions in epithermal fluxes were observed close to permanently shaded areas at both poles the peak depression at the north pole is 4 6 percent below the average epithermal flux intensity at lower latitudes and that at the south pole is 3 0 percent below the low latitude average no measurable depression in fast neutrons is seen at either pole these data are consistent with deposits of hydrogen in the form of water ice that are covered by as much as 40 centimeters of desiccated regolith within permanently shaded craters near both poles

major compositional units of the moon lunar prospector thermal and fast neutrons global maps of thermal and fast neutron fluxes from the moon suggest three end member compositional units a high thermal and low fast neutron flux unit correlates with the lunar highlands and is consistent with feldspathic rocks the south pole aitken basin and a strip that surrounds the nearside maria have intermediate thermal and fast neutron flux levels consistent with more mafic rocks there appears to be a smooth transition between the most mafic and feldspathic compositions which correspond to low and high surface altitudes respectively the maria show low thermal and high fast neutron fluxes consistent with basaltic rocks

the use and application of gpr in sandy fluvial environments methodological considerations ground penetrating radar gpr is a popular technique for imaging and interpreting sedimentary architecture however current literature shows a wide range in the quality of information provided on the gpr methodology and processing technique it is therefore difficult to judge the validity of the gpr interpretations and this produces inherent difficulties for comparison between surveys this paper describes the key steps required to collect process and interpret gpr surveys in sandy fluvial sediments gpr data from the south saskatchewan river canada are used to illustrate each stage of data collection and processing particular attention is given to the appropriate set up conditions for the gpr software and hardware the selection of data processing techniques and velocity analysis methods for the interpretation of gpr reflectors are also investigated using ground truth control provided by a cut face exposure this paper presents recommendations for a systematic and rigorous methodology for the collection processing and interpretation of gpr data in sandy fluvial environments the paper suggests that all data collection parameters and processing steps should be recorded or tabulated in any gpr publication to facilitate comparisons between surveys

bottomset architecture formed in the troughs of dunes and unit bars abstract bottomsets are formed in the troughs of migrating bedforms the flow and sediment dynamics downstream of bedforms differ and consequently the thickness grain size and internal structure of bottomsets vary greatly a classification of the controls on bottomset formation is proposed related to two and three dimensional processes flow and sediment unsteadiness and pre existing deposits structures and deposits created by flow and sediment unsteadiness as well as pre existing deposits are also considered in relation to changes they can induce in subsequent trough processes the classification is illustrated by observations from laboratory flumes the modern burdekin river australia and the rock record the roaches grit england and hawkesbury sandstone australia in bottomset examples described in this paper internal variability both vertically and laterally was much greater than that within the dominant foreset component complex compound structures were created by the interaction and predominance of different bottomset controls this combined with their high preservation potential makes them a highly useful paleoenvironmental indicator bottomset variation e g changes in the abundance of mud laterally will influence the permeability heterogeneity of fluvial reservoir rocks bottomsets formed under relatively steady conditions are likely to be laterally extensive and have similar characteristics over their entire length they may act as significant barriers to vertical flow conversely bottomsets generated in unsteady regimes tend to be highly variable potentially creating conduits between cross bed sets aiding inter set permeability

variations in fluvial style in the westwater canyon member morrison formation jurassic san juan basin colorado plateau abstract techniques of architectural element analysis and lateral profiling have been applied to the fluvial westwater canyon member of the morrison formation jurassic in southern san juan basin on a large scale the sandstone body architecture consists mainly of a series of tabular sandstone sheets 5 15 m thick and hundreds of meters wide separated by thin fine grained units internally these sheets contain lateral accretion surfaces and are cut by channels 10 20 m deep and at least 250 m wide on a more detailed scale interpretations made from large scale photomosaics show a complex of architectural elements and bounding surfaces typical indicators of moderate to high sinuosity channels lateral accretion deposits coexist in the same outcrop with downstream accreted macroform deposits that are typical of sand flats of low sinuosity multiple channel rivers broad deep channels with gently to steeply dipping margins were mapped in several of the outcrops by carefully tracing major bounding surfaces locally thick accumulations of plane laminated and low angle cross laminated sandstone lithofacies suggest rapid flow probably transitional to upper flow regime conditions such a depositional style is most typical of ephemeral rivers or those periodically undergoing major seasonal or more erratic stage fluctuations an interpretation consistent with independent mineralogical evidence of aridity fining upward sequences are rare in the project area contrary to the descriptions of campbell 1976 the humid alluvial fan model of galloway 1978 cannot be substantiated and similarly the architectural model of campbell 1976 requires major revision comparisons with the depositional architecture of the large indian rivers such as the ganges and brahmaputra still seem reasonable as originally proposed by campbell 1976 although there is now convincing evidence for aridity and for major stage fluctuations which differs both from those modern rivers and campbell s interpretation

ice jam caused fluvial gullies and scour holes on northern river flood plains abstract two anomalous fluvial landforms gullies and scour holes eroded into flood plains bordering meandering and braiding river channels have not been previously reported we observed these features along the milk river in southern alberta canada and northern montana usa which has a history of frequent 50 probability of recurrence and high magnitude 12 probability of recurrence greater than bankfull ice jam floods gullies have palmate and narrow linear shapes with open ends downvalley and measure up to 208 m long 139 m wide 3 5 m deep below bankfull channel ice jams reroute river water across meander lobes and cause headward gully erosion where flow returns to the main channel erosion of the most recent gully was observed during the record 1996 ice breakup flood and ice jams scour holes bowl shaped closed depressions eroded by water vortices beneath and between grounded ice jam blocks measure up to 91 m long 22 m wide 4 5 m deep ice jam caused gullies may be precursors to the formation of u shaped oxbow lakes and multiple channels common in many northern rivers

new lunar meteorites impact melt and regolith breccias and large scale heterogeneities of the upper lunar crust we have analyzed nine highland lunar meteorites lunaites using mainly inaa several of these rocks are difficult to classify dhofar 081 is basically a fragmental breccia but much of its groundmass features a glassy fluidized texture that is indicative of localized shock melting also much of the matrix glass is swirly brown suggesting a possible regolith derivation we interpret dar al gani dag 400 as an extremely immature regolith breccia consisting mainly of impact melt breccia clasts we interpret dhofar 026 as an unusually complex anorthositic impact melt breccia with scattered ovoid globules that formed as clasts of mafic subophitic impact melt the presence of mafic crystalline globules in a lunar material even one so clearly impact heated suggests that it may have originated as a regolith our new data and a synthesis of literature data suggest a contrast in al2o3 incompatible element systematics between impact melts from the central nearside highlands where apollo sampling occurred and those from the general highland surface of the moon impact melts from the general highland surface tend to have systematically lower incompatible element concentration at any given al2o3 concentration than those from apollo 16 in the case of dhofar 026 both the bulk rock and a comparatively al poor composition 14 wt al2o3 7 g g sm extrapolated for the globules manifest incompatible element contents well below the apollo 16 trend impact melts from luna 20 57e distribute more along the general highland trend than along the apollo 16 trend siderophile elements also show a distinctive composition for apollo 16 impact melts ni ir averaging 1 8x chondritic in contrast lunaite impact melt breccias have consistently chondritic ni ir impact melts from luna 20 and other apollo sites show average ni ir almost as high as those from apollo 16 the prevalence of this distinctive ni ir ratio at such widely separated nearside sites suggests that debris from one extraordinarily large impact may dominate the megaregolith siderophile component of a nearside region 2300 km or more across highland polymict breccia lunaites and other kreep poor highland regolith samples manifest a strong anticorrelation between al2o3 and mg the magnesian component probably represents the chemical signature of the mg suite of pristine nonmare rocks in its most pure form unaltered by the major kreep assimilation that is so common among apollo mg suite samples the average composition of the ferroan anorthositic component is now well constrained at al2o3 29 30 wt implying about 17 19 wt modal mafic silicates in good agreement with the composition predicted for flotation crust over a ferroan magma ocean warren 1990

analysis of dynamic sedimentary environments in alluvial fans of some tributaries of the upper yellow river of china based on ground penetrating radar gpr and sediment cores abstract there are ten ephemeral tributaries of the yellow river in the inner mongolia of china as their catchments are covered by loose materials and are dominated by an intense interaction between wind and water erosion these tributaries have had a high sediment yield and alluvial fans have been formed at the confluences of the tributaries with the yellow river however there is a lack of understanding in the deposition model of the alluvial fans and the roles of fluvial and aeolian processes in sediment accumulation in this paper we used ground penetrating radar 100 mhz and sediment cores to investigate the sediments in channels and alluvial fans of four out of the ten tributaries radar reflection profiles of sedimentary strata are dominated by horizontal or sub horizontal layers with a large scale showing that the fluvial deposition on the alluvial fans has been dominated by a vertical accretion pattern the reflection features like reflection free inclined reflections discontinuous undulate chaotic sinuous reflections and channel fill exist to a lesser extent a few gpr profiles send signs of intense erosion and the one near the apex of an alluvial fan reveals that erosion had been active likely during the early holocene and the channel position should be relatively fixed the information extracted from this profile and the widely exposed late pleistocene strata in the upper parts of the alluvial fans according to the geological map of the study area indicates that sediment accumulation has been slow in the upper alluvial fans since the early holocene the sediment cores indicate that sedimentary strata under the alluvial fans are mainly composed by sand and silt deposited in a fluvial environment and rarely reworked by wind actions also according to the core data the sediment deposits in the west fans were coarser than those in the east fans likely suggesting that the hydrodynamic force of the western tributaries was stronger than that of the east ones the hydrodynamic environment of the tributaries was usually unstable historically and hyperconcentrated flows might occur with a higher frequency in one of the tributaries in history

landscape and depositional controls on palaeosols of a distributive fluvial system upper cretaceous brazil abstract the stratigraphic record of distributive fluvial systems is commonly characterised by frequent and complex interstratification of palaeosols among channel and overbank deposits however current models focus primarily on sedimentation and pay only limited attention to palaeopedogenesis thereby failing to incorporate important palaeoenvironmental and stratigraphic information this study proposes a pedosedimentary model for distributive fluvial systems that depicts and accounts for two palaeopedogenetic trends one downdip in relation to distality from the fan apex and one along strike in relation to distance from active channel belts palaeosols are reported in detail from an upper cretaceous succession of the bauru basin southeastern brazil through the application of macro micromorphological and geochemical studies combined with facies and architectural element analyses of sediments in the downdip palaeopedogenetic trend the proximal zone of the depositional system is characterised by a dominance of well drained inceptisols that develop on amalgamated channel fills in the medial zone inceptisols occur interlayered with overbank deposits containing entisols and poorly drained vertisols the distal zone preserves more mature and poorly drained inceptisols developed on deposits of overbank and sporadic distal channel fills these pedotypes show an increase in maturity and hydromorphism moving away from the apex to the fan toe this is likely linked to i the progressive approach of the topographic surface to the water table and ii the average increase in distance to an active channel belt in distal locations the along strike palaeopedogenetic trend culminates in poorly developed palaeosols in floodplain regions that correspond to topographic depressions located between channel belts and which were subject to recurrent floods because palaeopedogenesis in the floodplain region is penecontemporaneous to sedimentation pedotypes show an increase in maturity bioinduced calcification and hydromorphism with distance from the active channels they pass laterally from entisols and inceptisols near active channels to vertisols away from active channels conversely following avulsion abandoned channel belts remain as topographically elevated alluvial ridges located at some distance from the newly active channels and positioned above the water table and this leads to the development of better drained and better developed inceptisols relative to pedotypes of the floodplain region overall both palaeopedogenetic trends demonstrate the overriding controls of topography sedimentation rate and parent material on pedogenesis with only minor climatic influence this work offers a novel pedosedimentary model for distributive fluvial systems and highlights the palaeoenvironmental significance of palaeosol trends providing new constraints for the recognition of distributive fluvial systems in the rock record

revision of platte river alluvial facies model through observations of extant channels and barforms and subsurface alluvial valley fills abstract the platte river of nebraska central usa has been used by sedimentologists as a type example of a sandy braided river system for some forty years despite this designation however the details of the river s subsurface stratigraphy have never been evaluated and so the extant facies model for the platte river remains unvalidated this paper analyzes the holocene stratigraphy of the central and lower platte river it utilizes newly acquired data from wireline logs sediment cores aerial photography and ground penetrating radar gpr traverses to characterize subsurface geology in addition to surface sediment and geomorphic mapping sampling and analysis of serial aerial imagery cores and gpr profiles show that the lithosome of the active platte is 6 8 m in thickness and consists predominantly of medium sand although macroform features are common on the surface of the modern active central and lower platte river in nebraska the shallow subsurface stratigraphy is dominated by mesoform cross bedding and planar stratification overlying channel scour fills this differs markedly from the vertical succession predicted by the platte river facies model of miall 1977 data from inactive portions of the central and lower platte river however show macroform cross bedding indicative of the downstream and cross stream migration of linguoid and transverse bars which would be predicted by the published model the typical architecture of the holocene channel belt sand body in the areas studied thus comprises a lower unit dominated by macroform scale cross bedding overlain by an upper unit dominated by mesoform scale cross bedding and scour fills furthermore time series analysis of aerial photography of the river in the vicinity of grand island nebraska shows that 1 the river has become dominated by aggressively vegetated subaerially exposed channel bed domains termed vegetated channel islands that superficially resemble bars and 2 that this stretch is no longer dominated by downstream accreting macroform bars which were abundant in the 1960s and 1970s contraction of the active channel in this region has accompanied these changes somewhat independently of discharge variation new vertical sequence facies models are presented to account for these differences our data show the futility of seeking to characterize a fluvial system by means of a single vertical sequence model and furthermore indicate that the holocene facies architecture of the sandy braided platte river varies both in space and in time the dominance of mesoform scale structure in the shallow subsurface of the central and lower platte river likely reflects the ongoing process of gradual abandonment of the system it further highlights the need for caution in interpreting subsurface structure from surface geomorphology in fluvial systems

chemical information content of lunar thermal and epithermal neutrons simulations of equilibrium thermal and epithermal neutron flux spectra for the moon have been studied to determine their chemical information content most of this information resides in a single parameter the ratio of macroscopic absorption to energy loss cross sections although this parameter cannot specify the chemistry of lunar soils uniquely it provides an index that can be used to quantitatively separate anorthositic from mafic chemistries hydrogen abundances can best be derived from measurements of the epithermal neutron flux which is strongly related to its macroscopic energy loss cross section the ratio of thermal to epithermal neutron flux measured by lunar prospector is shown to agree quantitatively with simulations this agreement is used to show that the highlands terrane on the farside of the moon is anorthositic containing high percentages of plagioclase and possibly a range of mg suite minerals with a high mg mg fe atomic ratio our best estimate of the abundance of feo is 2 with an upper limit of 5

the magma ocean concept and lunar evolution the model of lunar evolution in which the anorthositic plagioclase rich oldest crust of the moon is formed over a period of 300 myr or less by crystallization as it floats on a global ocean of magma tens or hundreds of km thick is examined in a review of petrological and theoretical studies consideration is given to the classification of lunar rocks the evidence for primordial deep global differentiation constraints on the depth of the molten zone the effects of pressure on mineral stability relationships mainly liquid vs mainly magmifer ocean models and the evidence for multiple ancient differentiation episodes a synthesis of the model of primordial differentiation and its aftereffects is presented and the generalization of the model to the earth and to mars mercury venus and the asteroids is discussed

wind relaxations and poleward flow events in a coastal upwelling system on the central california coast 1 when upwelling favorable winds weaken or relax in coastal upwelling systems prevailing equatorward currents often weaken and then reverse to form propagating poleward currents here the statistics of wind relaxations and poleward flow events along the south central california coast are derived using meteorological and oceanographic times series during 2000 2006 over the 7 year record 169 wind relaxations were observed about 1 every 2 weeks and 127 of these were followed by poleward flow events thermistor moorings and current profilers along the 15 m isobath at alegria point arguello point purisima and point sal recorded the poleward flows the poleward flows propagate northward at 10 30 km d 1 and appear as sequential temperature increases at the moorings wind relaxations occur throughout the year but are most frequent in september and least frequent in april when upwelling winds are strong and persistent poleward flows follow wind relaxations frequently during may through november and rarely in december and january sea level differences between santa monica and port san luis california decreased as winds relaxed consistent with forcing by alongshore pressure gradients temperature distributions at point arguello point purisima and point sal were skewed toward higher values because of the poleward flows the alongshore distance traveled by the poleward flows increased with duration of the wind relaxations and magnitudes of alongshore temperature and sea level differences prior to the relaxations

sub mesoscale coastal eddies observed by high frequency radar a new mechanism for delivering nutrients to kelp forests in the southern california bight 1 sub mesoscale eddies are described along the mainland coast of the santa barbara channel based on observations from a network of high frequency hf current measuring radars and near shore moorings the eddies are 4 15 km in diameter and typically last about 2 days although some last up to 6 days most eddies within the radar coverage area are anti cyclonic with relative vorticities of 0 4 f to 0 8 f where f is the coriolis parameter but cyclonic eddies are also observed moored observations over the inner shelf 12 m water depth of a sequence of two eddies in december 2001 show an increase in nitrate plus nitrite from the background levels of 1 2 m to a maximum of 10 12 m when the eddies are present we speculate that these eddies are an important transport mechanism for nutrients and biogenic particles to inner shelf ecosystems of the southern california bight

three dimensional sedimentary architecture of a large mid channel sand braid bar jamuna river bangladesh the three dimensional subsurface alluvial architecture of a large approximately 3 km long 1 km wide 12 m high mid channel sand braid bar in the jamuna river bangladesh is described evolution of the bar and its depositional characteristics are assessed from a unique combination of ground penetrating radar surveys vibracoring and trenching that are allied to a series of bathymetric surveys taken during growth of the bar over a 29 month period this methodology permits identification of the formative processes of different packages of braid bar sedimentation and provides a facies model for deposition within the entire bar mid channel bar growth occurred in a region of flow expansion and was probably initiated by the stalling and amalgamation of large dunes these dunes created a bar core that grew by i propagation of a downstream accreting slipface ii vertical accretion through stacking of dunes on both bar stoss and top and iii lateral accretion on the bar margins during recession of the flood hydrograph braid bar sedimentation is dominated by four radar facies 1 large scale predominantly planar dipping reflections interpreted as cross stratification up to 8 m in height and greater than 100 m in width that is produced by the cross channel migration of bar margins 2 medium scale trough shaped and planar discontinuous reflections interpreted as cross stratification up to 4 m in height and 300 m wide that is deposited from large sinuous crested sand dunes 3 discontinuous reflections up to 2 m high and 30 m wide interpreted as small scale trough cross stratification that is the product of smaller sinuous crested dunes and 4 high amplitude undulating reflections interpreted as mud drapes deposited in regions of slow flow often in the bar tail region at low stage dune size decreases vertically within the bar in response to the progressively shallower flows on the emerging bar top later evolution of the bar as one anabranch channel became dominant created a 1 5 km extension to the bar tail with an 8 m high angle of repose bar margin slipface formed by flow transverse to the long axis of the bar seven styles of deposition can be defined that constitute the alluvial architecture bar margin slipface vertical accretion in channel bar top vertical accretion upstream accretion lateral accretion downstream accretion and low stage mud drapes a model of braid bar sedimentation is presented that shares many similarities with previous studies of smaller sand bed braid bars with the dominance of dune scale cross stratification the presence of large scale bar margin cross stratification and the occurrence of lateral vertical upstream and downstream accretion however the contribution of the bar margin facies to the preserved stratigraphy highlighted herein may have been underestimated in previous models of braided rivers in which the braid bars were migrating slowly this study suggests a scale invariance in several aspects of mid channel bar sedimentation in sand bed rivers and proposes a model of braid bar sedimentation that may be applied widely within studies of braided alluvial architecture

morphological evolution and dynamics of a large sand braid bar jamuna river bangladesh the initiation and evolution of a kilometre scale sand braid bar was monitored during a 28 month survey period from 1993 to 1996 in one of the world s largest braided rivers the jamuna river bangladesh repeated bathymetric surveys through two monsoon flood seasons combined with bar top surveys during exposure of the bar at low flow provide the most detailed chronology of braid bar growth yet compiled for a large sand bed river during rising and peak flow of the 1994 monsoon flood a 1 5 km long 0 5 km wide 12 m high symmetrical mid channel bar was deposited in the centre of a major channel downstream of a zone of flow convergence and significant bank erosion initial deposition and growth of the bar core were probably caused by amalgamation of dunes that are present in the jamuna channels at all flow stages bar top aggradation continued through downstream migration of an accretionary dune front a 3 m high angle of repose slipface that was composed of amalgamated 0 5 to 1 m high dunes at waning and low flow the mid channel bar widened by up to 1 km through the lateral accretion of dunes onto the margins of the initial bar core a low velocity zone in the sheltered wake region of the bar tail led to the accumulation of substantial volumes of silts and clays during the rising and peak flows of the next monsoon flood the mid channel bar extended its bar tail by up to 1 5 km as one of the anabranches became dominant and flow was deflected across the bar tail accretion at the bar tail generated a lobate transverse bar front with a 10 m high angle of repose avalanche face emergence of several smaller bars along this depositional front produced an overall reach morphology that more closely resembled an alternate bar rather than several mid channel bars the conversion of a mid channel bar to an alternate bar is contrary to many previous descriptions of the braiding process

the combined effect of transient wind driven upwelling and eddies on vertical nutrient fluxes and phytoplankton dynamics along ningaloo reef western australia we investigate the influence of wind stresses stratification and coastal mesoscale eddies on upwelling intensity vertical nutrient fluxes and phytoplankton biomass on the continental shelf off ningaloo reef in northwestern australia during an austral spring summer period a three dimensional 3 d hydrodynamic model roms regional ocean modeling system was coupled with a four component nitrogen based biogeochemical npzd model nitrogen phytoplankton zooplankton detritus to resolve the shelf circulation as well as the coupled nutrient and phytoplankton dynamics within a broad shelf region surrounding ningaloo reef the simulated currents temperatures and chlorophyll a concentrations generally agreed well with both the remotely sensed satellite images and observational data collected during a field experiment from september to november 2010 scenario tests for an individual wind driven upwelling event under a variety of hypothetical physical forcing conditions showed that shelf currents and biogeochemical variables were largely a function of wind stress and stratification however the functional relationships derived from this single wind event could not be extrapolated to other periods of the upwelling season due to the additional influence of 3 d mesoscale processes on the shelf the presence intensification and propagation of a coastal anticyclonic eddy during the study period strongly influenced the spatial and temporal variations in nutrient profiles which in turn caused fluctuations in vertical nutrient fluxes that were largely independent of wind stress these results emphasize that it is necessary to fully capture the 3 d details of the mesoscale and submesoscale coastal dynamics to properly predict upwelling induced coastal phytoplankton dynamics in eddy intensive shelf regions such as ningaloo reef

large scale structure of calamus river deposits nebraska usa revealed using ground penetrating radar the large scale i e bar scale structure of channel deposits of the braided low sinuosity calamus river nebraska is described using ground penetrating radar gpr profiles combined with vibracores basal erosion surfaces are generally overlain by medium scale trough cross stratified sets 3 25 cm thick very coarse to medium sands that are associated with relatively high amplitude discontinuous gpr reflectors overlying deposits are bioturbated small scale cross stratified sets 3 cm thick and vegetation rich fine to very fine sands that are associated with low amplitude discontinuous reflectors near surface peat and turf have no associated gpr reflectors in along stream profiles through braid and point bars most gpr reflectors dip downstream at up to 2 relative to the basal erosion surface but some reflectors in the upstream parts of bars are parallel to the basal erosion surface or dip upstream in cross stream profiles through bars gpr reflectors are either approximately parallel to bar surfaces or have low angle inclinations up to 6 towards cut banks of adjacent curved channels basal erosion surfaces become deeper towards cut banks of curved channels these structures can be explained by lateral and downstream growth of bars combined with vertical accretion convex upwards forms up to 0 5 m high several metres across and tens of metres long represent episodic accretion of unit bars scroll bars and bar heads stratal patterns in channel fills record a complicated history of erosion and deposition during filling including migration of relatively small bars a revised facies model for this type of sandy braided river has been constructed based on this new information on large scale bedding structure

mapping the feo and tio2 content of the lunar surface with multispectral imagery the derivation of quantitative elemental concentrations from multispectral imaging of the moon has long been a goal of lunar remote sensing concentration maps at the spatial resolutions available from the recent clementine mission would provide a revolutionary new tool for understanding the origin and evolution of the lunar crust lucey et al 1995 presented a method for extracting the concentration of fe from multispectral imaging of the moon this paper examines and quantifies important aspects ofthat technique left unexamined by lucey et al which had the potential to severely limit its utility these aspects include the effects of maturity grain size mineralogy shading due to topography and the presence of glass we also present a new algorithm for derivation of tio2 from multispectral imaging of both mare and highland units we find that both techniques are only weakly sensitive to maturity and that they have about 1 wt accuracy based on examination of the spectral properties and compositions of resolved lunar sampling stations presented by blewett et al 1997 we also discuss these findings in the context of two contrasting views of the effect of composition on lunar spectral properties presented by pieters and coworkers and hapke and coworkers we find the view of hapke and coworkers to be more consistent with our observations using a global mosaic of clementine multispectral data and these element derivation algorithms we find that the global modal abundance of feo is 4 5 wt 1 wt and the global modal abundance of tio2 is 0 45 wt 1 wt

characteristic patterns of shelf circulation at the boundary between central and southern california 1 the coastal circulation in the santa barbara channel sbc and the southern central california shelf is described in terms of three characteristic flow patterns the upwelling pattern consists of a prevailing equatorward flow at the surface and at 45 m depth except in the area immediately adjacent to the mainland coast in the sbc where the prevailing cyclonic circulation is strong enough to reverse the equatorward tendency and the flow is toward the west in the surface convergent pattern north of point conception the surface flow is equatorward while the flow at 45 m depth is poleward east of point conception along the mainland coast the flow is westward at all depths and there results a convergence at the surface between point conception and point arguello with offshore transport over a distance on the order of 100 km beneath the surface layer the direction of the flow is consistently poleward the relaxation pattern is almost the reverse of the upwelling pattern with the exception that in the sbc the cyclonic circulation is such that the flow north of the channel islands remains eastward although weak the upwelling pattern is more likely to occur in march and april after the spring transition when the winds first become upwelling favorable and while the surface pressure is uniform the surface convergent pattern tends to occur in summer when the wind is still strong and persistently upwelling favorable and the alongshore variable upwelling has build up alongshore surface pressure gradients the relaxation pattern occurs in late fall and early winter after the end of the period of persistent upwelling favorable winds

global elemental maps of the moon the lunar prospector gamma ray spectrometer lunar prospector gamma ray spectrometer spectra along with counting rate maps of thorium potassium and iron delineate large compositional variations over the lunar surface thorium and potassium are highly concentrated in and around the nearside western maria and less so in the south pole aitken basin counting rate maps of iron gamma rays show a surface iron distribution that is in general agreement with other measurements from clementine and the lunar prospector neutron detectors

sandstone body structures and ephemeral stream processes in the dinosaur canyon member moenave formation lower jurassic utah u s a abstract studies of fluvial sandstone body structures in the lower jurassic dinosaur canyon member suggest a threefold subdivision of the ephemeral stream deposits sandstone sheets with interbedded siltstones are less than 1 m thick and laterally extensive for hundreds of metres they are interpreted as sheetflood deposits simple channel sandstone bodies are a few metres thick and a few tens of metres wide they reflect solitary channel incision episodic migration and plugging multistorey channel sandstone bodies are a few metres thick and laterally extensive for hundreds of metres they are composed of several channel shaped storeys and exhibit only local incision the multistorey sandstone bodies are interpreted as braided ephemeral stream deposits two sandstone sheet subtypes with grooves and mounds respectively are interpreted as intermediate between the sheetflood deposits and solitary incised channel deposits on one hand and between sheetflood deposits and braided stream deposits on the other hand the solitary channels and braided streams are accordingly interpreted to be initiated from sheetfloods through differential erosion and differential deposition respectively this model of channel evolution from sheetfloods is probably applicable to other semiarid and arid fluvial environments dominated by surface runoff

local diurnal wind driven variability and upwelling in a small coastal embayment the oceanic response to high frequency local diurnal wind forcing is examined in a small coastal embayment located along an understudied stretch of the central california coast we show that local diurnal wind forcing is the dominant control on nearshore temperature variability and circulation patterns a complex empirical orthogonal function ceof analysis of velocities in san luis obispo bay reveals that the first mode ceof amplitude time series which accounts for 47 9 of the variance is significantly coherent with the local wind signal at the diurnal frequency and aligns with periods of weak and strong wind forcing the diurnal evolution of the hydrographic structure and circulation in the bay is examined using both individual events and composite day averages during the late afternoon the local wind strengthens and results in a sheared flow with near surface warm waters directed out of the bay and a compensating flow of colder waters into the bay over the bottom portion of the water column this cold water intrusion into the bay causes isotherms to shoal toward the surface and delivers subthermocline waters to shallow reaches of the bay representing a mechanism for small scale upwelling when the local winds relax the warm water mass advects back into the bay in the form of a buoyant plume front local diurnal winds are expected to play an important role in nearshore dynamics and local upwelling in other small coastal embayments with important implications for various biological and ecological processes

lunar fe and ti abundances comparison of lunar prospector and clementine data the lunar prospector neutron spectrometer data correlate well with iron and titanium abundances obtained through analysis of clementine spectral reflectance data with the iron and titanium dependence removed the neutron spectrometer data also reveal regions with enhanced amounts of gadolinium and samarium incompatible rare earth elements that are enriched in the final phases of magma crystallization these regions are found mainly around the ramparts of the imbrium impact basin but not around the other basins including the much larger and deeper south pole aitken basin this result confirms the compositional uniqueness of the surface and interior of the imbrium region

mesoscale to submesoscale transition in the california current system part ii frontal processes this is the second of three papers investigating the regime transition that occurs in numerical simulations for an idealized equilibrium subtropical eastern boundary upwelling current system similar to the california current the emergent upper ocean submesoscale fronts are analyzed from phenomenological and dynamical perspectives using a combination of composite averaging and separation of distinctive subregions of the flow the initiating dynamical process for the transition is near surface frontogenesis the frontal behavior is similar to both observed meteorological surface fronts and solutions of the approximate dynamical model called surface dynamics i e uniform interior potential vorticity q and diagnostic force balance in the intensification of surface density gradients and secondary circulations in response to a mesoscale strain field however there are significant behavioral differences compared to the surface dynamics model wind stress acts on fronts through nonlinear ekman transport and creation and destruction of potential vorticity the strain induced frontogenesis is disrupted by vigorous submesoscale frontal instabilities that in turn lead to secondary frontogenesis events submesoscale vortices and excitation of even smaller scale flows intermittent submesoscale breakdown of geostrophic and gradient wind force balance occurs during the intense frontogenesis and frontal instability events

icelandic jokulhlaup impacts implications for ice sheet hydrology sediment transfer and geomorphology abstract glaciers and ice sheets erode entrain and deposit massive quantities of debris fluxes of subglacial meltwater exert a fundamental control on ice dynamics and sediment transport budgets within many glacial systems outburst floods jokulhlaups constitute high magnitude high frequency fluxes of meltwater relative to normal ablation controlled discharge this paper presents a synthesis of research on recent icelandic jokulhlaups and their geomorphological and sedimentary impact we identify jokulhlaup impacts within subglacial englacial and proglacial settings and discuss their wider significance for ice sheet hydrology sediment transfer and geomorphology because jokulhlaups erode deposit and re work sediment simultaneously they usually cause significant glaciological and sedimentological impacts jokulhlaups that propagate as subglacial flood waves often produce widespread hydromechanical disruption at the glacier base recent icelandic jokulhlaups have been recognised as highly efficient agents of reworking subglacial sediment and glacial sediment entrainment models of jokulhlaup impact therefore need to encompass the sub and englacial environment in addition to the proglacial zone where research has traditionally been focussed most jokulhlaups transport sediment to proglacial sandar and often directly to oceans where preservation potential of the impact is greater proglacial jokulhlaup deposits form distinctive sedimentary assemblages coupled with suites of high energy erosional landforms this study of modern jokulhlaup processes and sedimentary products may be useful for the interpretation of meltwater processes associated with quaternary ice sheets

identifying causes of ground penetrating radar reflections using time domain reflectometry and sedimentological analyses ground penetrating radar gpr is a geophysical technique widely used to study the shallow subsurface and identify various sediment features that reflect electromagnetic waves however little is known about the exact cause of gpr reflections because few studies have coupled wave theory to petrophysical data in this study a 100 and 200 mhz gpr survey was conducted on aeolian deposits in a quarry time domain reflectometry tdr was used to obtain detailed information on the product of relative permittivity er and relative magnetic permeability lr which mainly controls the gpr contrast parameter in the subsurface combining tdr data and lacquer peels from the quarry wall allowed the identification of various relationships between sediment characteristics and erlr synthetic radar traces constructed using the tdr logs and sedimentological data from the lacquer peels were compared with the actual gpr sections numerous peaks in erlr which are superimposed on a baseline value of 4 for dry sand are caused by potential gpr reflectors these increases in erlr coincide with the presence of either organic material having a higher water content and relative permittivity than the surrounding sediment or iron oxide bands enhancing relative magnetic permeability and causing water to stagnate on top of them sedimentary structures as reflected in textural change only result in possible gpr reflections when the volumetric water content exceeds 0ae055 the synthetic radar traces provide an improved insight into the behaviour of radar waves and show that gpr results may be ambiguous because of multiples and interference

inner shelf intrusions of offshore water in an upwelling system affect coastal connectivity 1 poleward warm water flows around point conception are an important transport mechanism linking biogeographic provinces along central california these flows are initiated by relaxation of upwelling winds the intensity and duration of upwelling is an important driver of how far north warm water penetrates against the prevailing surface currents in this paper we present evidence of offshore surface water intrusions to the inner shelf 130 km north of point conception near cambria california satellite observations show that the intrusions originate as eddies generated offshore along the upwelling front these eddies may form as submesoscale instabilities or by interaction of upwelling centers with offshore waters the intrusions move southern waters to the central california inner shelf further northward than is typical for a coastal relaxation plume and therefore inner shelf connectivity and ecology may be governed over timescales and distances longer than those set by the intermittent relaxation of upwelling winds

depositional controls in a bedload dominated fluvial system internal architecture of the lee formation kentucky abstract sandstones of the early pennsylvanian lee formation central appalachian foreland basin were deposited in a low sinuosity bedload dominated fluvial system the internal architecture of the sandstones consists of a six fold hierarchy of bounding surfaces which are evaluated with respect to depositional controls minor first second and third order surfaces generally less than a few hundred meters in extent separate deposits of small to intermediate scale bedforms third order surfaces which dip gently in the downflow direction represent reactivation surfaces of downstream accreting macroforms major surfaces fourth fifth and sixth order are hundreds of meters to kilometers in extent fourth order surfaces separate deposits of individual macroforms fifth order bounding surfaces are erosional boundaries of major system scale channels individual sandstone members of the lee formation are bound by sixth order surfaces erosional at the base and gradational at the top deposits overlying major surfaces contain fining upward sequences the trends are more apparent with increased scale of the deposit these sequences represent responses of the fluvial system to various mechanisms that controlled sedimentation both fourth and fifth order surfaces are interpreted as results of autocyclic controls the nature of the lee formation fluvial system was such that a solitary major channel was relatively stable in one position within the alluvial plain for a significant period of time during this time the channel aggraded with the passage of one or more downstream accreting macroforms creating a fourth order erosional surface the channel eventually diverted its flow to another portion of the alluvial plain by avulsion creating a fifth order surface a gross fining upward trend and upward change in fluvial style for individual sandstone members both characteristic of paleovalley fills indicate that sixth order surfaces were controlled by allocyclic processes these characteristics and the stair step positioning of the sandstone members younger away from the alleghenian mountains to the east suggest that tectonic processes were the ultimate control on the system

lunar rare earth element distribution and ramifications for feo and tio2 lunar prospector neutron spectrometer observations lunar prospector neutron spectrometer data have been used to map the global surface distribution of the incompatible rare earth elements gadolinium and samarium from the low altitude 30 15 km mapping orbit these results afford improved surface resolution and detailed views of the potassium rare earth elements and phosphorus kreep distribution within and around mare imbrium and elsewhere the gd and sm results serve as a complementary and independent check of the distribution of kreep on the moon in contrast with the lunar prospector gamma ray spectrometer results for thorium the neutron spectrometer observations reflect the presence of fe and ti as well as gd and sm the contributions of fe and ti are removed using high spatial resolution clementine spectral reflectance determinations of feo and tio2 abundances overall the resulting gd and sm abundance map agrees with the th abundance map determined using the lunar prospector gamma ray spectrometer in general the detailed features of the procellarum imbrium kreep terrane are found in both for example distinct highs in gd sm and th abundances are resolved over the craters mairan aristarchus kepler reinhold lalande and aristillus over the apennine bench and fra mauro regions and over the montes jura and montes carpatus indicating an enhanced abundance of kreep in these locations the neutron observations also provide constraints on feo and tio2 abundances for some high ti locales there is a significant disagreement with tio2 abundances inferred from clementine spectral reflectance

braided stream and flood plain architecture the rio vero formation spanish pyrenees early to middle miocene fluvial sandstones of the rio vero formation were studied in an area around the town of barbastro south central pyrenees spain the outstanding quality of outcrops in this area allows a three dimensional study of architectural elements six architectural elements are recognised described in detail and interpreted from three key localities seven main lithofacies were identified and sub divided into gravelly sandy and fine grained lithofacies the architectural elements and lithofacies have been combined with a hierarchy of depositional bounding surfaces to fully interpret the evolution of the depositional system at the meso and macro scale not only the different architectural elements and lithofacies of the complete braided fluvial system but also the lateral variation of the architectural elements were emphasised in this study differential tectonic movements seasonal climate change and their effect on vertical and lateral evolution of the area were the main control on basin sedimentation channel interconnection palaeocurrent patterns and consequently the fluvial architecture the presence of lateral ramp anticlines caused the fluvial system to be laterally restricted with the main channel belts being located in the areas of highest subsidence and lowest topography intervening topographic highs acted as both flood plains and lateral barriers between the main channel systems the proposed depositional model comprises broad low sinuosity perennial but seasonal moderate energy streams the sandstone architecture is dominated by channel fill and sheet sands and associated simple and more complex bars adjacent to the main channel belts fine grained sandstones siltstones and immature paleosols occur the along strike relationship between major fluvial systems and their outlets into a foreland basin has important implications for the infill of the basin and the modelling of fluvial systems along mountain belt fronts

abundance and distribution of iron on the moon the abundance and distribution of iron on the moon is derived from a near global data set from clementine the determined iron content of the lunar highlands crust 3 percent iron by weight supports the hypothesis that much of the lunar crust was derived from a magma ocean the iron content of lower crustal material exposed by the south pole aitken impact basin on the lunar farside is higher 7 to 8 percent by weight and consistent with a basaltic composition this composition supports earlier evidence that the lunar crust becomes more mafic with depth the data also suggest that the bulk composition of the moon differs from that of the earth9s mantle this difference excludes models for lunar origin that require the earth and moon to have the same compositions such as fission and coaccretion and favors giant impact and capture

trough cross bedded conglomerate facies abstract gravel bed river deposits contain a range of facies that includes planar cross bedded gravel gp massive gravel gm and trough cross bedded gravel gt of these the gt facies is commonly interpreted to represent deposits of channel fills and or three dimensional 3d gravel dunes and or scours or pools in this study a calcrete conglomerate sheet built up of gt facies is found to consist of trough cross beds of 3d dune origin gtd and of bedload sheet origin gtb whereas gtd occurs as sets gtb is found to occur as isolated large troughs the gtd facies is characterised by high dips low width height ratios and foreset bed thickness of about 100 140 mm in contrast the gtb facies has low dips high width height ratios and foreset bed thickness usually less than 50 mm the bivariate plot of width height of troughs vs maximum dip effectively discriminates between these varieties of troughs a third variety of gt may be recognised by the presence of a scoop or spoon shaped lower bounding surface as seen in the depositional dip direction this facies has been demonstrated in other works to represent filling of scours or pools on the streambed and is designated as gtc for the preservation of 3d gravel dunes in the stratigraphic record special flow conditions are necessitated of prime importance is the rapid recession of flow subsequent to a short duration of peak discharge such discharge patterns are critical to the preservation of gravel dunes in the stratigraphic record and appear to have been met with in the case of glacial outburst floods or floods in the seasonal tropics

quantification of bedform dynamics and bedload sediment flux in sandy braided rivers from airborne and satellite imagery images from specially commissioned aeroplane sorties manned aerial vehicle mav repeat unmanned aerial vehicle uav surveys and planet cubesat satellites are used to quantify dune and bar dynamics in the sandy braided south saskatchewan river canada structure from motion sfm techniques and application of a depth brightness model are used to produce a series of digital surface models dsms at low and near bankfull flows a number of technical and image processing challenges are described that arise from the application of sfm in dry and submerged environments a model for best practice is presented and analysis suggests a depth brightness model approach can represent the different scales of bedforms present in sandy braided rivers with low turbidity and shallow 2 m deep water the aerial imagery is used to quantify the spatial distribution of unit bar and dune migration rate in an 18 km reach and three 1 km long reaches respectively dune and unit bar migration rates are highly variable in response to local variations in planform morphology sediment transport rates for dunes and unit bars obtained by integrating migration rates from uav with the volume of sediment moved from dsms using mav imagery show near equivalence in sediment flux hence reach based sediment transport rate estimates can be derived from unit bar data alone moreover it is shown that reasonable estimates of sediment transport rate can be made using just unit bar migration rates as measured from 2d imagery including from satellite images so long as informed assumptions are made regarding average bar shape and height with recent availability of frequent repeat satellite imagery and the ease of undertaking repeat mav and uav surveys for the first time it may be possible to provide global estimates of bedload sediment flux for large or inaccessible low turbidity rivers that currently have sparse information on bedload sediment transport rates

rapid changes in mixed layer stratification driven by submesoscale instabilities and winds 1 submesoscale eddies generated by baroclinic instability of upper ocean fronts lead to rapid restratification of the mixed layer on a time scale of days this restratification can be opposed by a down front wind stress acting in the direction of the geostrophic velocity that drives a surface ekman flow from the dense side to the light side of the front to arrest the slumping of isopycnals a scaling diagnostic is suggested to determine whether the effect of eddies or wind dominates under different conditions using a numerical model we investigate the juxtaposition of submesoscale eddies and down front winds acting on the mixed layer by estimating the eddy induced overturning stream function in the mixed layer we separate the along and cross isopycnal fluxes of buoyancy associated with submesoscale mixed layer eddies and demonstrate the need for parameterization of the advective along isopycnal flux though the cross front transport of buoyancy induced by the down front component of the wind opposes restratification by mixed layer eddies it becomes diminished as the eddies and growth of the frontal instability disrupt alignment between the wind and frontal axis

the propagating response of coastal circulation due to wind relaxations along the central california coast 1 following relaxations of prevailing upwelling favorable winds warm waters from the santa barbara channel propagate poleward around point conception and along the south central california coast we examined characteristics of these relaxation flows including frontal propagation speed and temperature changes during the warm water arrivals by using multiyear time series of currents and temperatures from four moorings along the 15 m isobath surface current observations from high frequency radars and satellite sea surface temperature images propagation speeds of the warm fronts relative to ambient waters ranged from 0 04 to 0 46 m s 1 as the fronts arrived at the moorings temperature increases ranged from 0 7 c to 4 2 c in ensemble averages over many frontal arrivals alongshore flow speeds increased by 0 1 0 2 m s 1 over the water column during arrivals cross shore flows were onshore near the surface and offshore near the bottom with speeds of 0 02 0 05 m s 1 this cross shore flow structure persisted as temperature increased during arrivals and ceased when temperatures stopped increasing frontal propagation speeds were correlated with temperature increases at the moorings consistent with forcing by baroclinic pressure gradients compared to other buoyant flows such as from the chesapeake bay where density contrasts with ambient waters are 2 3k g m 3 these relaxation flows are less buoyant with density contrasts of 0 1 0 9 kg m 3 consequently the propagation of these flows is more affected by bottom friction and the speeds are closer to the slope controlled or bottom advected limit described in theoretical and laboratory work but not well studied in the ocean

the great lunar hot spot and the composition and origin of the apollo mafic lkfm impact melt breccias thorium rich mafic impact melt breccias from the apollo 14 17 missions that is those breccias identified with the composition known as lkfm are regarded largely as products of basin forming impacts that penetrated the feldspathic crust and sampled underlying mafic material and magma ocean residuum carrying the compositional signature of kreep potassium rare earth elements phosphorous despite considerable compositional variation among such breccias compositions of all of them correspond to mixtures of only four components 1 a norite with composition generally similar to that of apollo 15 basalt mean abundance 58 range 30 95 2 fo 90 dunite mean 13 range 1 27 3 feldspathic upper crust mean 29 range 4 50 and feni metal 0 1 1 7 petrographic evidence has shown that much of the feldspathic component but none of the kreep component is clastic this observation and the high proportion of kreep norite component in the breccias suggest that the melt zone of the impact or impacts forming the breccias contained little feldspathic material but consisted predominantly of material with the average composition of kreep norite the dunite component probably derives ultimately from the upper mantle these conclusions support the hypothesis that the breccias were not formed in typical feldspathic crust but instead by one or more impacts into what is designated here the great lunar hot spot that is the anomalous th rich terrane in the imbrium procellarum area identified by the apollo and lunar prospector gamma ray spectrometers the lkfm composition is a special product of the great lunar hot spot and is not the average composition of the lower crust in typical feldspathic highlands similarly mg suite and alkali suite plutonic rocks of the apollo collection are likely all differentiation products of the hot spot not of plutons that might occur in typical feldspathic crust

radar surveys of the rutford ice stream onset zone west antarctica indications of flow in stability we present 1 and 100 mhz ground based radar data from the onset region of rutford ice stream west antarctica which indicate the form and internal structure of isochrones in the flow parallel lines modelled isochrone patterns reproduce the gross pattern of the imaged near surface layers assuming steady state flow velocity from gps records and the current accumulation rate for the last 200 years we interpret this as indicating overall stability in flow in the onset region of rutford ice stream throughout this period however in the cross flow lines some local variability in accumulation is seen in areas close to the ice stream margin where a number of tributaries converge towards the ice stream onset zone episodic surface lowering events are observed followed by rapid fill episodes the fill events indicate deposition towards the northwest most likely generated by storm winds which blow at an oblique angle to ice flow more problematic is explaining the generation of episodic surface lowering in this area we speculate this may be due to changing ice flow direction in the complex tributary area of the onset zone a change in basal sediments or sedimentary landforms a change in basal melt rates or water supply or episodic lake drainage events in the fjord systems of the ellsworth subglacial highlands the study highlights the difficulty of assessing flow stability in the complex onset regions of west antarctic ice streams

gpr and aerial imageries to identify the recent historical course of the obra river and spatial extent of obrzanskie lake altered by hydro technical works ground penetrating radar gpr measurements have been conducted to retrace the natural course of the obra river and changes of spatial extent of obrzanskie lake western poland the obra river valley was subjected to intensive anthropogenic transformation three artificial canals were constructed here in the beginning of the nineteenth century the gpr surveys were done using a georadar mala proex equipped with 250 mhz antenna the measurement was verified by coring and analyses of historical maps aerial photographs and satellite images the research has shown that there are at least three elongated depressions preserved in the modern land surface near the village of solec situated in the middle course of the valley several structures suggesting functioning of a multi channel pattern in the past have been detected inside and in the vicinity of the depressions filling the channels with silts and peats might have been the effect of flow deceleration caused by the construction of the obra canals moreover situation of two of the retraced depressions suggests that the landforms might be the remains of a river bed disappearing in wetlands further studies including groundwater flux measurements in the area between the depressions are needed to confirm such hypothesis furthermore the study allowed retracing the spatial extent of obrzanskie lake the sediment structures detected by the gpr measurements and calibrated with coring were interpreted to be the traces of the lake shoreline the interpretation was supported by the findings inferred from aerial and satellite images it was shown that obrzanskie lake had had at least three islands and had been directly connected with a network of braided channels before the anthropogenic intervention the spatial extent of the lake was significantly altered by the construction of the north obra canal disconnecting the lake from the canal resulted in more than 50 decrease of the lake surface

numerical simulation of bar and island morphodynamics in anabranching megarivers 1 bar and island morphodynamics in the world s largest anabranching rivers are investigated using a new numerical model of hydrodynamics sediment transport bank erosion and floodplain development operating over periods of several hundred years simulated channel morphology is compared to that of natural rivers and shown to be realistic both in terms of the statistical characteristics of channel width depth and bar shape distributions and mechanisms of unit bar compound bar and island evolution results demonstrate that bar and island stability may be sensitive to hydrologic regime because greater variability in flood magnitude encourages the formation of emergent bars that can be stabilized by vegetation colonization simulations illustrate a range of mechanisms of unit bar generation that are linked to local bed or bank instabilities this link may explain the reduced frequency of unit bars observed in some large anabranching rivers that are characterized by stable vegetated islands and slow rates of channel change model results suggest that the degree to which sand sized bed material is carried in suspension likely represents an important control on bar morphodynamics and channel network evolution because of its influence on sand transport direction consequently differences in the partitioning of the total sand load between bed load and suspension may provide a partial explanation for contrasting styles of anabranching in the world s largest sand bed rivers these results highlight a need for spatially distributed flow and sediment transport data sets from large rivers in order to support improved parameterizations of sand transport mechanics in morphodynamic models

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

ground penetrating radar for high resolution mapping of soil and rock stratigraphy ground penetrating radar is a technique which offers a new way of viewing shallow soil and rock conditions the need to better understanding overburden conditions for activities such as geochemical sampling geotechnical investigations and placer exploration as well as the factors controlling groundwater flow has generated an increasing demand for techniques which can image the subsurface with higher resolution than previously possible the areas of application for ground penetrating radar are diverse the method has been used successfully to map ice thickness water depth in lakes bedrock depth soil stratigraphy and water table depth it is also used to delineate rock fabric detect voids and identify karst features the effective application of the radar for the high resolution definition of soil stratigraphy and fractures in bedrock is highlighted the basic principles and practices involved in acquiring high quality radar data in the field are illustrated by selected case histories one example demonstrates how radar has been used to map the bedrock and delineate soil horizons to a depth of more than 20 m two case histories show how radar has been used to map fractures and changes of rock type to 40 m range from inside a mine another case history demonstrates how radar has also been used to detect and map the extent of groundwater contamination the corroboration of the radar results by borehole investigations demonstrates the power and utility of the high resolution radar method as an aid for interpolation and extrapolation of the information obtained with conventional coring programmes with the advent of new instrumentation and field procedures the routine application of the radar method is becoming economically viable and the method will see expanded use in the future

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

oceanic variability off the central california coast abstract mesoscale variability off the central california coast is strongly influenced by coastal upwelling and related processes off point sur there is significant space time variability in oceanic properties over periods of days and distances of several tens of km however the internal density field averaged over space ca 120km alongshore and time ca 18 days reveals the expected characteristics of a coastal upwelling regime including an equatorward surface jet 25km to 40km offshore and weaker poleward flow below 150m and within 20km of the coast upper ocean circulation is strongly influenced by the bathymetry offshore to water depths of at least 1000m based on repeated horizontal grids of oceanographic stations horizontal correlation scales for temperature are of the order of 30km in the upper 100m hence a horizontal sampling rate of ca 10km is desirable vertical correlation scales for temperature are of the order of 100m hence a vertical sampling rate of ca 10m is desirable similarly there are indications of a temporal correlation scale of a few weeks hence a temporal sampling rate of ca a few days is desirable empirical orthogonal functions eofs in the cross shore vertical plane suggest the influence of coastally trapped motions within 40km of the coast with an intense alongshore near surface transient coastal jet located ca 20km offshore sudden spring transitions to coastal upwelling conditions are often pronounced in coastal temperature records and they may precede the offshore migration of the major upwelling front by at least a month or more the spring transitions occur over a period of about a week in 1980 the spring transition propagated poleward along the california coast at a speed of ca 64km d 1 during spring and summer movement of a coastal upwelling front often located between 15km and 50km offshore is a major contributor to cross shore variability the upwelling front meanders with an alongshore scale of about 80km a time scale of 30 to 40 days and an amplitude scale of 10km rms based on satellite infrared ir imagery the along shore mean position of the major upwelling front migrates offshore during spring and summer offshore displacement of the front may be caused by ekman transport over periods of days to weeks and by rossby wave dispersion over longer periods during summer a time dependent offshore scale based on rossby wave dynamics was more appropriate than the baroclinic rossby radius every three to four years during 1971 through 1984 el nino episodes produced interannual variability in coastal sea surface temperature sst off central california most of the warming occured during fall and winter el nino episodes were often followed by major spring transitions the recent 1982 1983 episode was 2 to 3 c warmer than the three previous episodes over the past 14 years and its influence lasted almost twice as long

deposits of the sandy braided south saskatchewan river implications for the use of modern analogs in reconstructing channel dimensions in reservoir characterization estimation of the dimensions of fluvial geobodies from core data is a notoriously difficult problem in reservoir modeling to try and improve such estimates and hence reduce uncertainty in geomodels data on dunes unit bars cross bar channels and compound bars and their associated deposits are presented herein from the sand bed braided south saskatchewan river canada these data are used to test models that relate the scale of the formative bed forms to the dimensions of the preserved deposits and therefore provide an insight as to how such deposits may be preserved over geologic time the preservation of bed form geometry is quantified by comparing the alluvial architecture above and below the maximum erosion depth of the modern channel deposits this comparison shows that there is no significant difference in the mean set thickness of dune cross strata above and below the basal erosion surface of the contemporary channel thus suggesting that dimensional relationships between dune deposits and the formative bed form dimensions are likely to be valid from both recent and older deposits the data show that estimates of mean bankfull flow depth derived from dune unit bar and cross bar channel deposits are all very similar thus the use of all these metrics together can provide a useful check that all components and scales of the alluvial architecture have been identified correctly when building reservoir models the data also highlight several practical issues with identifying and applying data relating to cross strata for example the deposits of unit bars were found to be severely truncated in length and width with only approximately 10 of the mean bar form length remaining and thus making identification in section difficult for similar reasons the deposits of compound bars were found to be especially difficult to recognize and hence estimates of channel depth based on this method may be problematic where only core data are available i e no outcrop data exist formative flow depths are suggested to be best reconstructed using cross strata formed by dunes however theoretical relationships between the distribution of set thicknesses and formative dune height are found to result in slight overestimates of the latter and hence mean bankfull flow depths derived from these measurements this article illustrates that the preservation of fluvial cross strata and thus the paleohydraulic inferences that can be drawn from them are a function of the ratio of the size and migration rate of bed forms and the time scale of aggradation and channel migration these factors must thus be considered when deciding on appropriate length thickness ratios for the purposes of object based modeling in reservoir characterization

high resolution observations of subsurface fronts and alongshore bottom temperature variability over the inner shelf author posting american geophysical union 2019 this article is posted here by permission of american geophysical union for personal use not for redistribution the definitive version was published in journal of geophysical research oceans 53 3 2019 1639 1649 doi 10 1029 2018jc014454

clementine images of the lunar sample return stations refinement of feo and tio2 mapping techniques clementine uvvis images of the lunar sample return sites have been processed and used to produce refined calibrations for the iron and titanium determination algorithms of lucey et al 1995 1996 the high spatial resolution of the clementine data permits individual sampling stations to be resolved at the apollo 15 16 and 17 landing sites we find an excellent linear correlation between the spectral fe and ti parameters and the average feo and tio 2 contents of soils sampled at each site or station this correlation demonstrates that these techniques can confidently be applied to other areas of the moon the luna 24 site does not fit the ti relation found for other sites suggesting that either its sample is nonrepresentative or the reported landing coordinates are incorrect

statistical analysis of thorium and fast neutron data at the lunar surface 1 a comparison is conducted between the remotely sensed abundances of thorium through gamma ray spectroscopy and major chemical elements through fast neutron spectroscopy on the lunar surface these are key elements in the investigation of lunar evolution correlations of variations of thorium abundance and fast neutron flux are analyzed on a spatial scale of 180 km through the construction of a covariance map this technique is an unbiased mathematical method for developing the borders of major formations such as the procellarum kreep terrane although thorium variations are positively correlated with those of the fast neutron flux over most of the lunar nearside several locations within the procellarum kreep terrane have negative correlations this anticorrelation may denote an emplacement for these materials by transport of impact ejecta furthermore analysis of these data reveals the presence of a distinctive structure in the northwest corner of oceanus procellarum marked by a ring of enhanced thorium this structure may be related to an ancient impact basin the confirmation of such a ring of thorium around the major basins inside procellarum kreep terrane would reinforce the hypothesis of the redistribution of thorium during impact from shallow depth

sediment transport and bed morphology at river channel confluences river channel confluences form important morphological elements of every river system being points at which rapid changes in flow sediment discharge and hydraulic geometry must be accommodated this article presents results of a quantitative investigation of sediment transport at channel confluences accomplished through both scaled laboratory flume simulation and complementary monitoring of a natural channel confluence bed morphology at channel confluences is characterized by three distinct elements avalanche faces at the mouth of each confluent channel a deep central scour and a bar within the separation zone formed at the downstream junction corner these elements are controlled predominantly by the confluence angle and the ratio of discharges between the tributary and mainstream channels as confluence angle and discharge ratio increase the sediment contributions from the confluent channels are progressively segregated in their paths through the junction with sediment being transported around rather than through the centre of the confluence this segregation of sediment loads is accompanied by the retreat of the main channel avalanche face from the confluence an increase in the scour depth a change in the orientation of the scour and an increase in the size of the separation zone bar field measurements closely replicate the flume simulation a model of sediment transport and bed morphology links these features to the fluid dynamics of these sites an understanding of confluence dynamics is important not only in considerations of channel morphology and design criteria but must form the basis for the interpretation of confluence sediments in the ancient record

polar hydrogen deposits on the moon neutron and gamma ray data measured using the lunar prospector spectrometers were analyzed to define the enhanced hydrogen deposits near both poles of the moon combining the new low altitude neutron data 30 15 km with previous high altitude 100 20 km neutron data and the results of several recent radar investigations sharply constrains the characteristics of each of the polar deposits the deposits at the north appear to be in the form of many small pockets or of generally distributed hydrogen that average to a 100 ppm weight fraction enhancement over that which exists in regolith at more equatorial latitudes those deposits in the permanently shaded craters near the south pole are consistent with a thick ferroan anorthosite regolith containing an enhancement of 1670 890 ppm hydrogen which if in the form of water ice amounts to 1 5 0 8 weight fraction of h sub 2 o neutron data alone cannot discriminate between hydrogen implanted in lunar soil from the solar wind hydrated minerals or h sub 2 o these craters appear to be surrounded by regolith that either contains small pockets of enhanced hydrogen or is soil that is uniformly impregnated with hydrogen enhanced on average by about 100 ppm above that contained in soils at more equatorial latitudes c more 2000 american geophysical union less

the origin of oriented lakes evidence from the bolivian amazon the presence of hundreds of rectangular and oriented lakes is one of the most striking characteristics of the llanos de moxos lm landscape in the bolivian amazon oriented lakes also occur in the arctic coastal plains of russia alaska and canada and along the atlantic coastal plain from northeast florida to southeast new jersey and along the coast of northeast brazil many different mechanisms have been proposed for their formation in the lm plafker s 1964 tectonic model in which subsidence results from the propagation of bedrock faults through the foreland sediments is the most accepted however this model has not been verified here we present new results from stratigraphic transects across the borders of three rectangular and oriented lakes in the lm a paleosol buried under mid holocene sediments is used as a stratigraphic marker to assess the vertical displacement of sediments on both sides of the alleged faults our results show that there is no vertical displacement and therefore that plafker s model can be ruled out we suggest that among all the proposed mechanisms behind lake formation the combined action of wind and waves is the most likely the evidence from the lm provides new hints for the formation of oriented lakes worldwide

gradient based edge detection and feature classification of sea surface images of the southern california bight an edge detection algorithm was developed that is capable of objectively detecting significant edges in remotely sensed images of the surface ocean the algorithm utilizes a gradient based edge detector that is less sensitive to noise in the input image than previously used detectors and has the ability to detect edges at different length scales the algorithm was used to provide a statistical view of surface front occurrences in the southern california bight using six years of satellite observations of sea surface temperature avhrr and chlorophyll seawifs regions of high front occurrence probability were identified near capes headlands and islands in onshore direction chlorophyll concentration increased and temperature decreased indicative of coastal upwelling the algorithm was further applied to coincident time series of temperature and chlorophyll to investigate the event scale dynamics of mesoscale features and the spatial relationships between physical and biological processes a simple scheme for identifying and classifying eddies delineated by the edge detection algorithm was developed to yield a census of eddy occurrence in the southern california bight

subtidal inner shelf circulation near point conception california 1 we discuss connections between inner shelf and mid shelf circulation near point conception california as well as the wind forcing of inner shelf circulation point conception marks the southern edge of a major upwelling zone that extends from oregon to central california the coastline makes a sharp eastward turn at point conception and the santa barbara channel to the east is generally assumed to be an upwelling shadow consistent with this regional division inner shelf currents are strongly correlated with wind north of point conception but not in the santa barbara channel one exception to this generalization is a location in the santa barbara channel near a pass that cuts through the coastal mountains where local winds have a dominant cross shore component and directly drive cross shore currents over the inner shelf inner shelf currents in the santa barbara channel when compared with mid shelf currents in that area are weaker but strongly correlated by contrast inner shelf currents north of point conception show a far greater incidence of poleward flow than is seen over the mid shelf in that area poleward flow events lasting 1 5 days transport warm water from the santa barbara channel around point conception to the central california coast these events are associated with relaxation of the generally equatorward wind but not always with mid shelf flow reversals

bar top hollows a new element in the architecture of sandy braided rivers abstract discrete hollows in the bar tops of the south saskatchewan river are described that form a newly recognized morphological element of sandy braided rivers these bar top hollows which are up to 1 7 m deep and may extend for 10 30 m down and across flow have a circular to ovoid planform and are shown through use of ground penetrating radar to be filled by a series of distinct often angle of repose foresets the hollows form by both erosion and bar top deposition and may be generated by bar tail accretion cross bar channel cutoff and subsequent fill or lateral accretion at the bar head bar top hollows occur in the upper part of the bar depositional sequence and may thus prove useful indicators for braid bar reconstruction in ancient sediments and should not be confused with channel scour