integrated stratigraphy and palaeoenvironment of the berriasian peri reefal limestones at stramberk outer western carpathians czech republic abstract a high resolution multidisciplinary study of two profiles in the kotouc quarry at stramberk was carried out to define the age and palaeoenvironmental setting of the peri reefal stramberk limestone calpionellids of the alpina and ferasini subzones of the standard calpionella zone confirm an early berriasian age for both studied sequences the presence of the calcareous nannofossils nannoconus kamptneri minor and speetonia colligata supports this stratigraphic interpretation an ammonite assemblage with pseudosubplanites grandis was found corresponding to the upper part of the lower berriasian grandis subzone foraminiferan assemblages contain several taxa previously reported from the valanginian magnetostratigraphy verifies that the studied sections span the magnetozones m18r to m18n rock magnetic measurements indicate magnetite as the carrier of characteristic remanent magnetization a palaeolatitude suggested location at 36 n microfacies indicate palaeoenvironments of slope fz 4 platform margin reefs sand shoals fz 5 fz 6 and possibly patch reefs in the inner platform fz 7 the presence of calpionellids and the polychaete terebella lapilloides suggests deposition within the deeper parts of the outer ramp of a platform slope with redeposited clasts derived from nearby reef slopes and or talus this research contributes to the berriasian working group s efforts to define the tithonian berriasian boundary

calcareous nannofossil zonation of the jurassic cretaceous boundary interval and correlation with the geomagnetic polarity timescale abstract calcareous nannofossil stratigraphy has been investigated in six european land sections and at two deep sea drilling project sites 391c and 534a ranging from the upper kimmeridgian to the lower valanginian most of the sections contain a continuous record of the jurassic cretaceous boundary interval a time of rapid increase in nannofossil abundance and diversity and allow development of a revised nannofossil zonation scheme for this period numerous nannofossil lineages have been studied in detail and the results help to increase potential stratigraphic resolution in this interval the proposed scheme consists of six zones which are units recognizable in all sections regardless of nannofossil preservation and eleven subzones determinable in all but the most poorly preserved material thirty eight additional biohorizons are proposed based on the stratigraphy of the two dsdp sites these can be accurately established only in moderately well preserved material but spotty occurrences of these taxa in other sections may be stratigraphically useful most of the sections studied have been investigated magnetostratigraphically and the results of this study allow correlation between nannofossil zonation and the geomagnetic polarity time scale magnetostratigraphy indicates that many nannofossil events can be quite precisely determined and are not significantly time transgressive finally the magnetostratigraphic definitions of two stage boundaries are refined the kimmeridgian tithonian and berriasian valanginian boundaries are placed within chrons cm22n and cm15n respectively two new genera faviconus and umbria and seven new species are described umbria granulosa rhagodiscus nebulosus cretarhabdus octofenestratus faviconus multicolumnatus nannoconus infans nannoconus compressus and nannoconus wintereri eight subspecies and three taxonomic emendations are also described

spatial variation in the power of mountain streams in the sangre de cristo mountains new mexico the principle indicator of river energy expenditure stream power has a significant influence on many forms and process attributes of the fluvial system yet few basin wide analyses of stream power variations have ever been conducted recent studies hypothesize a peak in the mean stream power distribution in small 10 km2 to intermediate 100 km2 sized basins to test hypothetical stream power profiles in a high mountain setting 129 cross sections of stream networks within the costilla basin of northern new mexico and southern colorado were measured for channel form local sediment conditions and basin characteristics geomorphic and hydrologic analysis of these river sites throughout the costilla basin yielded evidence of abundant local control over fluvial processes and forms within the basin the spatial deviations of stream power from the hypothetical patterns derived from hydraulic geometry in some cases 200 deviation match areas of specific geologic and hydrogeologic control as an alternative to traditional hydraulic descriptions of downstream channel form a probabilistic process response model can incorporate local and basin scale variables and allow more realistic feedback mechanisms than in traditional regime theory the probabilistic nature of this type of model also allows prediction of multiple modes of channel adjustment an ever present challenge to extremal and physically based simulations

remote measurement of river morphology via fusion of lidar topography and spectrally based bathymetry this study developed and evaluated a hybrid approach to remote measurement of river morphology that combines lidar topography with spectrally based bathymetry comparison of filtered lidar point clouds with surveyed cross sections indicated that subtle features on low relief floodplains were accurately resolved by lidar but that submerged areas could not be detected due to strong absorption of near infrared laser pulses by water the reduced number of returns made the active channel evident in a lidar point density map a second dataset suggested that pulse intensity also could be used to discriminate land from water via a threshold based masking procedure fusion of lidar and optical data required accurate co registration of images to the lidar and we developed an object oriented procedure for achieving this alignment information on flow depths was derived by correlating pixel values with field measurements of depth highly turbid conditions dictated a positive relation between green band radiance and flow depth and contributed to under prediction of pool depths water surface elevations extracted from the lidar along the water s edge were used to produce a continuous water surface that preserved along channel variations in slope subtracting local flow depths from this surface yielded estimates of the bed elevation that were then combined with lidar topography for exposed areas to create a composite representation of the riverine terrain the accuracy of this terrain model was assessed via comparison with detailed field surveys a map of elevation residuals showed that the greatest errors were associated with underestimation of pool depths and failure to capture cross stream differences in water surface elevation nevertheless fusion of lidar and passive optical image data provided an efficient means of characterizing river morphology that would not have been possible if either dataset had been used in isolation copyright 2011 john wiley sons ltd

strontium isotope correlation of the basal maastrichtian stage in antarctica to the european and us biostratigraphic schemes new 87 sr 86 sr dating allows the correlation of a marker horizon within the prolific late cretaceous gunnarites antarcticus faunal assemblage of the cape lamb member snow hill island formation vega island antarctica with reference sections in europe and the usa this horizon is between 81 5 and 96 5 m above the base of the g antarcticus assemblage replicate analysis of six macrofossils from within it yielded a mean value for 87 sr 86 sr of 0 707 735 9 0 000 004 3 2 s e n 17 this ratio in turn yields a numerical age of 71 0 0 2 ma when compared to the standard 87 sr s6 sr reference curve for the latest cretaceous for which the campanian maastrichtian boundary is placed at 71 3 0 5 ma the value of 0 707 735 9 0 000 004 3 correlates to a level in the belemnella lanceolata belemnite zone of the chalk of northwestern germany that is 2 5 5 m beneath the base of the overlying b pseudobtusa zone and 7 5 m above the campanian maastrichtian belemnite boundary and to an interval within the ammonite zonation of the us western interior that spans the early maastrichtian baculites baculus and b eliasi zones but with a most likely level within the b eliasi zone an earliest maastrichtian age is thereby determined for the antarctic horizon and indeed for the entire g antarcticus assemblage gunnarites sensu lato is an important ammonite marker for the base of the maastrichtian throughout the southern high latitude regions and the associated large heteromorph ammonite diplomoceras may comprise a macrofossil link back to the maastrichtian type sections

effects of large floods on sediment transport and reach morphology in the cobble bed sainte marguerite river abstract sediment transport rates were estimated for two flood events on the cobble bed sainte marguerite river in the saguenay region canada morphologic methods were used to derive one set of estimates and a combination of the meyer peter and muller equation with a dimensionless sediment transport ratio after dietrich et al nature 340 1989 215 was used to derive another set of estimates both sets of estimates give consistent results for the first event which had a decade scale return period and for the second event which was the largest flood on record and had a century scale return period the transport occurring during the second event was an order of magnitude greater than that occurring during the first event despite this disparity in the transport intensity of the two events the channel morphology remained qualitatively similar the observed degree of channel stability is attributed to a change of channel pattern and the initiation of bed degradation following channel rectification in the 1960s

volcanism co2 and palaeoclimate a late jurassic early cretaceous carbon and oxygen isotope record a composite tethyan late jurassic early cretaceous carbon and oxygen isotope curve is presented c isotope data provide information on the evolution and perturbation of the global carbon cycle o isotope data are used as a palaeotemperature proxy in combination with palaeontological information the resulting trends in climate and in palaeoceanography are compared with biocalcification trends and oceanographic conditions favouring or inhibiting biocalcification positive c isotope anomalies in the valanginian and aptian correlate with episodes of increased volcanic activity regarded as a source of excess atmospheric carbon dioxide a major warming pulse accompanies the aptian but not the valanginian c isotope event the observed change in early aptian temperatures could have triggered the destabilization of sedimentary gas hydrates and the sudden release of methane to the biosphere as recorded as a distinct negative carbon isotope pulse preceding the positive excursion both c isotope anomalies are accompanied by biocalcification crises that may have been triggered by p co 2 induced changes in climate and in surface water chemistry elevated nutrient levels in river influenced coastal waters and in upwelling regions further weakened marine calcification these conditions contrast with normal trophic conditions prevailing in the latest jurassic and favouring biocalcification the c and o isotope curves record a stable mode of carbon cycling and stable temperatures we conclude that biocalcification is mostly triggered and inhibited by co 2 conditions in the atmosphere ocean system

stream power framework for predicting geomorphic change the 2013 colorado front range flood abstract the colorado front range flood of september 2013 induced a diverse range of geomorphic changes along numerous stream corridors providing an opportunity to assess responses to a large flood in a semiarid landscape we defined six classes of geomorphic change related to peak unit stream power and valley confinement for 531 stream reaches over 226 km spanning a gradient of channel scales and slope geomorphic change was generally driven by erosion of channel margins in confined reaches and by a combination of deposition and erosion in unconfined reaches the magnitude of geomorphic change typically increased with unit stream power with greater responses observed in unconfined channels cumulative logit modeling indicated that total stream power or unit stream power unit stream power gradient and valley confinement are significant predictors of geomorphic response for this flood event based on this dataset thresholds for geomorphic adjustment were defined for channel slopes 230 w m 2 16 lb ft s at least 10 of the investigated sites experienced substantial channel widening and a credible potential for avulsions braiding and loss of adjacent road embankments associated with 480 w m 2 33 lb ft s at least 10 of the investigated sites experienced such geomorphic change infrequent to numerous eroded banks were very likely with 700 w m 2 48 lb ft s with substantial channel widening or major geomorphic change shifting from credible to likely importantly in reaches where there were large reductions in as the valley form shifted from confined to relatively unconfined large amounts of deposition induced reach scale geomorphic change occurred in some locations at relatively low additionally alluvial channels with slopes 3 had greater resistance to geomorphic change likely caused by armoring by larger bed material and increased flow resistance from enhanced bedforms finally we describe how these results can potentially be used by practitioners for assessing the risk of geomorphic change when evaluating current or planned conditions

channel evolution controlled by valley configuration during 70 years in a severely erosive catchment mangaoporo river new zealand abstract we examined the channel evolution process in a 19 5 km course in the mangaoporo river catchment area 72 6 km2 in the east coast region of north island new zealand over 70 years using aerial photographs and cross sectional survey records the catchment experienced expansive deforestation during the late 19th and early 20th centuries which accelerated the growth of the gully complexes the manner of the evolution was controlled largely by the underlying lithology that determined the valley configuration in the upstream confined section where hillslope and channel processes were closely coupled continuous sediment supply from gully complexes gradually converted the channel course from a narrow single thread to wide braided reaches or from sediment transfer to storage zones this change was accompanied by a decrease in unit stream power usp in 1939 the usp was above 200 w m2 in most of the upstream section while 40 of the usp values were near or below 50 w m2 in 2012 2013 because a narrow reach situated at the end of the storage zone limited the amount of sediment travelling further the downstream reaches were gradually disconnected from the upstream section and the channel forms changed more moderately than in the upstream section this reduction in sediment travelling with distance transformed a once braided reach at the end of the course to development of a supply limited condition with time the overall channel evolution was accelerated by major rainfall events including prolonged rainfall in 1956 and cyclone bola in 1988 which activated gully complexes and contributed to subsequent channel widening particularly in the upstream section although reforestation starting in the 1980s contributed to deactivation of gully complexes after 1988 the difficulty in controlling their total remission together with the lower usp values of the river in 2012 2013 compared to those before the previous major wet events indicate that the river has been evolving in an irreversible direction triggered by land use changes of more than a century ago

morphodynamics of an extended bar complex fraser river british columbia we investigate large scale morphologic changes over a 65 year period in a major sedimentation zone within the 50 km long wandering gravel bed reach of lower fraser river british columbia this reach remains in a relatively pristine state compared with many major rivers in populated regions even though various forms of human interference have occurred over the past century to mitigate flooding and erosion concerns a template of channel evolutionary development is identified consisting of extended periods of orderly accretion of unit bars by deposition of gravel sheets controlled by the major riffles in the river when this process constricts channel conveyance an avulsion occurs and the major bar complexes are reorganized the recognition of fairly predictable short term behavior can potentially aid the development of models of sediment transport and channel evolution accordingly results of the detailed descriptive analysis are compared with a gis based probabilistic approach developed from transition state analysis this reveals that the river has a far stronger tendency to retain its existing morphology than to change its form within a roughly decennial time scale regardless of the magnitude of intervening flows but that this tendency gradually declines over time as major bar and island complexes are re worked by sediment exchange the timescale for major bar development appears to be of the order 30 years while complete sediment exchange occurs within a century copyright 2012 john wiley sons ltd

channel instability in a braided sand bed river the gila river of central arizona is representative of braided sand bed rivers in alluvial valleys that have inherent unstable behavior and destructive channel migration the 112 year record of channel conditions along a portion of the gila river provides data for the construction of locational probability maps for main flow channels zones of stability and hazardous instability alternate with each other at 3 2 km 2 mi intervals during the past century the overall sinuosity of the main flow channel has remained close to 1 18 despite numerous changes in actual location spatial and temporal variation of sinuosity have occurred in subreaches as a result of sedimentation behind a dam and fluctuations in the density of phreatophyte growth which both affect the hydraulics of flood flows unstable zones of the channel correspond to the surface of the sediment wedge behind the dam and areas dense phreatophyte growth stable zones correspond to areas controlled by bedrock or man made structures as well as locations determined by these external factors plus the requirement to maintain a consistent sinuosity channels such as that of the gila river do not meet most assumptions of equilibrium and are best understood through probabilistic approaches with an assumption of catastrophic adjustment

understanding the influence of slope on the threshold of coarse grain motion revisiting critical stream power abstract this paper investigates the slope dependent variation in critical mean bed shear stress for coarse grain motion and evaluates stream power per unit bed area as an alternative threshold parameter explanations for observed slope dependency and existing approaches for predicting the critical stream power per unit bed area are reviewed an analysis of secondary bed load transport datasets is used to examine the strength of associations between stream power per unit bed area mean bed shear stress and mean velocity with bed load transport rate data from an original flume study are combined with secondary data from similar flume experiments to investigate the effect of slope on both critical stream power per unit bed area and critical mean bed shear stress results suggest that stream power per unit bed area is most closely correlated with bed load transport rate and also that critical stream power per unit bed area is less variable with slope than critical mean bed shear stress alternative solutions to approximating critical stream power are explored these include 1 modifying existing expressions for critical stream power to account for higher critical mean bed shear stresses at higher slopes and 2 applying a constant dimensionless critical stream power criterion

geomorphic effects flood power and channel competence of a catastrophic flood in confined and unconfined reaches of the upper lockyer valley southeast queensland australia flooding is a persistent natural hazard and even modest changes in future climate are believed to lead to large increases in flood magnitude previous studies of extreme floods have reported a range of geomorphic responses from negligible change to catastrophic channel change this paper provides an assessment of the geomorphic effects of a rare high magnitude event that occurred in the lockyer valley southeast queensland in january 2011 the average return interval of the resulting flood was similar to 2000 years in the upper catchment and decreased to similar to 30 years downstream a multitemporal lidar derived dem of difference dod is used to quantify morphological change in two study reaches with contrasting valley settings confined and unconfined differences in geomorphic response between reaches are examined in the context of changes in flood power channel competence and degree of valley confinement using a combination of one dimensional 1 d and two dimensional 2 d hydraulic modelling flood power peaked at 9800 w m 2 along the confined reach and was 2 3 times lower along the unconfined reach results from the dod confirm that the confined reach was net erosional exporting similar to 287 000 m 3 of sediment whilst the unconfined reach was net depositional gaining similar to 209 000 m 3 of sediment 70 of the amount exported from the upstream confined reach the major sources of eroded sediment in the confined reach were within channel benches and macrochannel banks resulting in a significant increase of channel width in the unconfined reach the benches and floodplains were the major loci for deposition whilst the inner channel exhibited minor width increases the presence of high stream power values and resultant high erosion rates within the confined reach is a function of the higher energy gradient of the steeper channel that is associated with knickpoint development dramatic differences in geomorphic responses were observed between the two adjacent reaches of contrasting valley configuration the confined reach experienced large scale erosion and reorganisation of the channel morphology that resulted in significantly different areal representations of the five geomorphic features classified in this study c 2013 elsevier b v all rights reserved

net local removal of floodplain sediment by river meander migration abstract erosion from the banks of meandering rivers causes a local influx of sediment to the river channel most of the eroded volume is usually replaced in nearby point bars however the typical geometry of river bends precludes the local replacement of all eroded material because i point bars tend to be built to a lower elevation than cutbanks and ii point bars tend to be shorter than the eroding portion of cutbanks because of channel curvature in a floodplain that is in equilibrium i e neither increasing nor decreasing in volume sediment eroded from cut banks must be replaced elsewhere on the floodplain the local imbalance caused by differences in bank height should be balanced primarily by overbank deposition while the local imbalance caused by curvature should be balanced primarily by deposition in abandoned stream courses or oxbow lakes estimates of these local imbalances based on remotely sensed measurements of bank geometry and channel migration have been made on four systems in the united states a 91 km reach of the pearl river in louisiana and mississippi a 62 km reach of the bogue chitto river in louisiana a 35 km reach of the neuse river in north carolina and a 2 7 km reach of the vermillion river in minnesota for these systems the total local imbalance integrated over many bends ranged from 0 36 to 2 27 m 3 yr m of valley length 0 15 to 1 32 m 3 yr m of channel length or 7 to 45 of gross cutbank erosion with a typical value of about 17 when compared with gauged suspended sediment data the measurements provide estimates of the relative importance of floodplains for storing material transported by a river system the data suggest that even if the studied systems are near long term mass balance equilibrium as opposed to undergoing net deposition or erosion almost all of the sand and in some cases much of the silt and clay in transit through these systems is likely to have spent some time stored in an upstream floodplain

mapping spatial patterns of stream power and channel change along a gravel bed river in northern yellowstone abstract stream power represents the rate of energy expenditure along a river and can be calculated using topographic data acquired via remote sensing or field surveys this study sought to quantitatively relate temporal changes in the form of soda butte creek a gravel bed river in northeastern yellowstone national park to stream power gradients along an 8 km reach aerial photographs from 1994 to 2012 and ground based surveys were used to develop a locational probability map and morphologic sediment budget to assess lateral channel mobility and changes in net sediment flux a drainage area to discharge relationship and dem developed from lidar data were used to obtain the discharge and slope values needed to calculate stream power local and lagged relationships between mean stream power gradient at median peak discharge and volumes of erosion deposition and net sediment flux were quantified via spatial cross correlation analyses similarly autocorrelations of locational probabilities and sediment fluxes were used to examine spatial patterns of sediment sources and sinks energy expended above critical stream power was calculated for each time period to relate the magnitude and duration of peak flows to the total volumetric change in each time increment collectively we refer to these methods as the stream power gradient spg framework the results of this study were compromised by methodological limitations of the spg framework and revealed some complications likely to arise when applying this framework to small wandering gravel bed rivers correlations between stream power gradients and sediment flux were generally weak highlighting the inability of relatively simple statistical approaches to link sub budget cell scale sediment dynamics to larger scale driving forces such as stream power gradients improving the moderate spatial resolution techniques used in this study and acquiring very high resolution data from recently developed methods in fluvial remote sensing could help improve understanding of the spatial organization of stream power sediment transport and channel change in dynamic natural rivers

surface mineral mapping at steamboat springs nevada usa with multi wavelength thermal infrared images abstract the purpose of this study was to evaluate the use of airborne multispectral and hyperspectral thermal infrared tir image data for mapping surface minerals characteristic of active geothermal systems tir image data from the master multispectral spectrometer and the sebass hyperspectral spectrometer were acquired over steamboat springs nevada usa in september 1999 spectral emissivity information was extracted from the data and used to generate mineral maps using the master data it was possible to map the extent of the active geothermal area as well as silica rich vs clay rich areas using the sebass data the same areas could be mapped and additionally the presence of several minerals including opal quartz alunite anorthite albite and kaolinite could be identified the sebass data also detected previously unidentified hydrous sulfate minerals tamarugite and alunogen forming around active fumaroles laboratory spectral data and xrd analyses of field samples confirmed the dominant mineral phases identified remotely the airborne field and laboratory data together with temperature anomaly and fumarole location data from other studies were synthesized and linked to the surface geology to determine the diagnostic surface mineral expression that could be mapped with tir remotely sensed data for future exploration for similar geothermal systems opaline sinter deposits are the most diagnostic surface expression of hot spring activity at steamboat springs because they represent areas of the recent geyser activity the differentiation between opal and chalcedony deposits and the identification of hydrous sulfate minerals forming around active fumaroles are also important because chalcedony represents ancient sinter deposits and hydrous sulfate minerals indicate locations of fumaroles that may be venting diffusely with no geyser activity the surface expression of the geothermal system at steamboat springs is small which emphasizes the need for high spatial resolution airborne imagers the 90 m pixels of aster tir data over the same area were only capable of resolving the area of past and recent sinter deposits together master multispectral tir data covered the entire area 12 km 2 at 5 m spatial resolution and were capable of defining the extent of the sinter deposits and zones of hydrothermally altered rocks the sebass image swath was too narrow 256 m to add significant spatial information to the overall map but the high spectral content identified several important minerals related to the local geology and the mineralogic surface expression of the geothermal system

spectral signs of aeolian activity around a sand dune belt in northern algeria abstract dune color has been used to investigate the provenance stabilization and age of the sand here we look for signs of aeolian activity in the colors of a sand dune belt in northern algeria on the one hand visible and near infrared spectral analyses of satellite images and laboratory samples showed reddish yellowish and whitish sands depending on the amount of gypsum particles and fe oxides coating quartz grains specifically the dithionite extractable fe content was related to a redness index calculated from remote sensing data and the abundance of hematite estimated in the second derivative of the kubelka munk function paralleled the cielab hue angle of sand samples on the other hand a spatiotemporal analysis showed that the reddish sand had undergone a continuous remobilization and dispersion throughout the area reaching two large salt flats sabkhas with seasonal water yellowish and whitish sands appeared as patches on the periphery of these sabkhas and along the dune belt exhibiting percussion marks and dissolution pits on the surface of quartz grains taken together the results suggest that the reddish sand partially loses its fe oxide coatings by mechanical abrasion in the entrainment and reductive dissolution in the sabkhas during waterlogging becoming yellowish the periodic reactivation by wind of reddish and yellowish grains together with whitish gypsum particles formed by evaporation as the sabkhas dry up may explain the sorting of grains according to their mineralogy and size along the sand dune belt resulting in striking color changes accordingly color reflects sand movements and chemical processes taking place in this dune system

tethyan carbonate carbon isotope stratigraphy across the jurassic cretaceous boundary an indicator of decelerated global carbon cycling the carbon isotope record in four pelagic carbonate sections from the southern alps northern italy across the jurassic cretaceous boundary has been correlated to biostratigraphy and magnetostratigraphy the carbon isotope curve from bulk carbonates shows a decrease from kimmeridgian to early tithonian cm24 cm22 values of 13c 2 07 0 14 to late tithonian and berriasian cm18 cm14 values of 13c 1 26 0 16 the change in the carbon isotope record coincides with changes in tethyan calcite and silica accumulation rates with a drop in the calcite compensation depth in the atlantic and tethys oceans and with changes in organic carbon burial along the eurasian margin of the tethys reduced surface water productivity due to diminished transfer rates of biolimiting elements into the atlantic and tethys oceans can explain these observations the decreased transfer rates of elements such as silica or phosphorus from continents into the oceans resulted from drier climatic conditions and decreased water runoff on continents bordering the tethys and atlantic oceans the proposed changes in tithonian berriasian ocean chemistry and paleoclimate suggest that variations in the global carbon cycle were coupled with changes in the global hydrological cycle and in associated material cycles

characterization and interpretation of volcanic activity at karymsky volcano kamchatka russia using observations of infrasound volcanic emissions and thermal imagery 2 a multiparameter data set including measurements of infrasound volcanic emissions and thermal imagery is used to characterize and interpret diverse volcanic activity observed during field campaigns in august 2011 and july 2012 at karymsky volcano kamchatka russia four activity types are visually identified and characterized according to so2 emission rate ash mass event duration peak temperature thermal radiation energy infrasound onset and frequency reduced infrasonic pressure and acoustic energy these activity types include 1 ash explosions 2 pulsatory degassing 3 gas jetting and 4 explosive eruption unique infrasound signals are associated with all four activity types suggesting that infrasound can be used to help remotely and continuously detect and characterize volcanic activity at karymsky and other similar volcanoes our observations suggest that so2 is emitted continuously though in varying abundance while ash is emitted discontinuously and is only associated with certain types of activity our data set supports previous models that attribute variations in surface activity to changes in conduit permeability at karymsky volcano evidence for a decrease in conduit permeability as a trigger for ash explosions and explosive eruption activity types is supported by weakened but still detectable so2 emission rates prior to eruption along with the highly impulsive infrasonic onset and large reduced infrasound pressure indicating high pressure at the vent we speculate that changes in conduit permeability at karymsky volcano result from changes in magma supply from the shallow crustal storage region though additional measurements are required to validate this hypothesis

geomorphic context of channel locational probabilities along the lower mississippi river usa channel change is an important aspect of geomorphological evolution and habitat dynamics in large alluvial rivers planimetric maps of channel locations were used to investigate spatio temporal alluvial channel changes in a geomorphic context along the lower mississippi river lmr analyses were conducted with the aid of a time weighted locational probability map the locational probability map was constructed in arcgis and covered a period of 205 years an examination of the pixel data from the probability maps indicates a high occurrence of low probability pixels along the lower mississippi river which is in accordance with the dynamism of alluvial rivers the northern section of the lower mississippi river columbus ky to memphis tn has been much more stable than the southern river segments helena ar to natchez ms areas of high channel probability channel stability were often associated with alluvial channel confinement from a combination of flood plain deposits geologic structures and large stable islands low channel probability locations were found along sections exhibiting the following geomorphic characteristics changes in meander amplitude meander neck and chute cutoffs meander extensional processes and islands lost in channel migrational processes the results provide a strong foundation for understanding channel change on the lower mississippi river and serves as a valuable instrument for future management and restoration schemes

an isotopic appraisal of the late jurassic greenhouse phase in the russian platform abstract oxygen and carbon isotope ratios have been determined from late jurassic callovian volgian belemnites from three locations on the russian platform gorodischi khanskaya gora and marievka all samples were examined by means of trace element geochemistry and petrography in order screen for diagenetic alteration oxygen and carbon isotopes from well preserved belemnites range from 2 24 to 0 09 and 0 57 to 1 77 respectively oxygen isotopes if interpreted in terms of temperature reveal a rise of temperatures during the oxfordian early kimmeridgian and indicate a prolonged episode of warmth during the kimmeridgian volgian the isotope data only equivocally reflect a number of significant changes in boreal tethyan ammonite assemblages a positive carbon isotope excursion is observed within the volgian but not seen within composite carbon isotope stratigraphies of the western tethys hence the jurassic may have been characterised by regional 13 c excursions related to non simultaneous organic matter deposition resulting from localised ponding semi restricted ocean circulation and a lack of tidal mixing

high resolution basin extent observations and implications for understanding river form and process fifty years of fluvial studies have posited a variety of conceptual frameworks for characterizing river forms and processes throughout entire basins including hydraulic geometry the river continuum concept self organized criticality and sediment links this article uses basin extent high resolution observations of fluvial forms in the nueces river basin texas and yellowstone national park to evaluate the ability of these frameworks to characterize system behavior across a multitude of scales the nueces data were collected with remote sensing methods and the yellowstone data were collected through extensive field surveys the data resolution spatial extent and quality of these data sets allow direct comparison between the two areas the hyperscale comparison supports using of each these frameworks at specific scales but also indicates an irreducible amount of variation in both datasets across many different scales that is not captured by the conceptual frameworks moreover the scales and locations where one framework such as hydraulic geometry works well are often not the same scales and locations where another framework such as the river continuum concept works well because the conceptual frameworks appear to operate at scales and locations distinct from one another the measurement approaches necessary to observe them must also be at different scales and locations for example seeing self organized criticality in a river system is difficult without an extensive survey through space whereas the recognition of sediment links requires quite intense sampling in specific river regions we suggest that these separations between measurement scales represent an incommensurability issue in river studies making it very difficult to both communicate among and test between two or more competing theories making simultaneous hyperscale observations of the river is one approach to minimizing the theory ladeness of observation as deviations from different predictions can be plotted at every scale copyright 2010 john wiley sons ltd

analysis of hot springs and associated deposits in yellowstone national park using aster and aviris remote sensing the advanced spaceborne thermal emission and reflection radiometer aster and the airborne visible ir image spectrometer aviris data were used to characterize hot spring deposits in the lower midway and upper geyser basins of yellowstone national park from the visible near infrared vnir to thermal infrared tir wavelengths field observations of these basins provided the critical ground truth for comparison with the remote sensing results fourteen study sites were selected based on diversity in size deposit type and thermal activity field work included detailed site surveys such as land cover analysis photography global positioning system gps data collection radiometric analysis and vnir spectroscopy samples of hot spring deposits geyser deposits and soil were also collected analysis of aster data provided broad scale characteristics of the hot springs and their deposits including the identification of thermal anomalies aviris high spectral resolution short wave infrared swir spectroscopy provided the ability to detect hydrothermally altered minerals as well as a calibration for the multispectral swir aster data from the image analysis differences in these basins were identified including the extent of thermal alteration the location and abundance of alteration minerals and a comparison of active near extinct and extinct geysers we determined the activity level of each region using a combination of the vnir swir tir spectral differences as well as the presence of elevated temperatures detected by the tir subsystem of aster the results of this study are applicable to the exploration of extinct mineralized hydrothermal deposits on both earth and mars

the application of aster remote sensing data to porphyry copper and epithermal gold deposits abstract this paper reviews the performance characteristics of the advanced spaceborne thermal emission and reflection radiometer aster remote sensor the standard data products and applications of the most recently developed image processing methods applied to aster data as a tool for mapping hydrothermal alteration mineral zones associated with porphyry copper and epithermal gold mineralization and related host rock lithology hydrothermal alteration zones associated with porphyry copper deposit such as phyllic argillic and propylitic mineral assemblages can be discriminated from one another by virtue of their spectral absorption features which are detectable by aster swir spectral bands the identification of the phyllic zone is important in the initial stages of porphyry copper exploration as an indicator of high economic potential for copper mineralization two new crosstalk corrected aster swir reflectance products including ast 07xt and refl1b are more reliable than previous aster data products for regional mineral mapping without use of additional spectral data from the site for calibration four types of algorithms were used to extract spectral information of aster data 1 band ratio indices and logical operator based methods 2 principal components and enhancement based methods such as principal component analysis pca and minimum noise fraction mnf 3 shape fitting based algorithms such as spectral angle mapper sam matched filtering mf and mixture tuned matched filtering mtmf and 4 partial unmixing methods such as linear spectral unmixing lsu and constrained energy minimization cem this review emphasizes that the logical operator algorithms can be best suited for hydrothermal alteration mineral mapping including phyllic and argillic zones associated with porphyry copper mineralization in a regional scale shape fitting based and partial unmixing algorithms are robust and reliable for detecting particular mineral and mineral assemblages in hydrothermal alteration zones in a district scale consequently the integration of the results derived from the logical operator shape fitting based and partial unmixing algorithms can produce comprehensive and accurate information for the reconnaissance stages of copper and gold exploration at both regional and district scales all of the methods and applications reviewed in this paper demonstrate the utility of aster data for exploration of the porphyry copper and epithermal gold deposits around the world

strontium isotopic variations in jurassic and cretaceous seawater a high resolution seawater strontium isotope curve has been generated through the analysis of well dated and well preserved belemnites and oysters from the middle and upper jurassic and the lower cretaceous of great britain analysis of fe and mn concentrations in these fossils has yielded criteria for eliminating samples that are diagenetically altered the strontium isotope curve remains relatively flat through the aalenian and early bajocian rapidly descends through the late bajocian and bathonian and reaches a minimum in the callovian and oxfordian it then begins a rapid increase in the kimmeridgian and portlandian that continues through much of the early cretaceous the curve levels off in the barremian suddenly dips downwards in the aptian and recovers gradually through the albian the strontium isotopic variations are sufficiently large and the data are presented with sufficient stratigraphic detail to allow precise correlation to the classic ammonite zones and lithologic sections of great britain using the techniques of strontium isotope stratigraphy model results indicate that much of the variation in seawater 87sr86sr between 120 and 40 ma can be explained by changing the intensity of mid ocean ridge hydrothermal fluxes proportionally to estimated mid ocean ridge crustal generation rates it is also possible that the variations during the rest of the mesozoic and the permian are primarily reflections of changing hydrothermal inputs the model results have several important implications first they provide an example in which the variations in the strontium isotope curve are not necessarily driven by changes in fluvial inputs second they suggest that from at least the aptian through the eocene variations in continental weathering were minimal this heightens the importance of the rapid rise in seawater 87sr86sr beginning 40 ma as a significant transition to an extended period of increasing fluvial 87sr fluxes continuing to the present finally the results suggest that several documented short term excursions towards lower 87sr86sr in the latest triassic pliensbachian toarcian callovian oxfordian aptian albian and cenomanian turonian are interpretable as pulses of seafloor hydrothermal activity if so the strontium isotope record offers a means of constraining the timing duration and magnitude of known or proposed hydrothermal events in the geological record

catchment scale mapping of surface grain size in gravel bed rivers using airborne digital imagery 1 this study develops and assesses two methods for estimating median surface grain sizes using digital image processing from centimeter resolution airborne imagery digital images with ground resolutions of 3 cm and 10 cm were combined with field calibration measurements to establish predictive relationships for grain size as a function of both local image texture and local image semivariance independently acquired grain size data were then used to assess the algorithm performance results showed that for the 3 cm imagery both local image semivariance and texture are highly sensitive to median grain size with semivariance being a better predictor than image texture however in the case of 10 cm imagery sensitivity of image semivariance and texture to grain size was poor and this scale of imagery was found to be unsuitable for grain size estimation this study therefore demonstrates that local image properties in very high resolution digital imagery allow for automated grain size measurement using image processing and remote sensing methods

carbon cycle history through the jurassic cretaceous boundary a new global δ13c stack we present new carbon and oxygen isotope curves from sections in the bakony mts hungary constrained by biostratigraphy and magnetostratigraphy in order to evaluate whether carbon isotopes can provide a tool to help establish and correlate the last system boundary remaining undefined in the phanerozoic as well provide data to better understand the carbon cycle history and environmental drivers during the jurassic cretaceous interval we observe a gentle decrease in carbon isotope values through the late jurassic a pronounced shift to more positive carbon isotope values does not occur until the valanginian corresponding to the weissert event in order to place the newly obtained stable isotope data into a global context we compiled 31 published and stratigraphically constrained carbon isotope records from the pacific tethyan atlantic and boreal realms to produce a new global 13c stack for the late oxfordian through early hauterivian interval our new data from hungary is consistent with the global 13c stack the stack reveals a steady but slow decrease in carbon isotope values until the early valanginian in comparison the late jurassic early cretaceous 13c curve in gts 2012 shows no slope and little variation aside from the well defined valanginian positive excursion chemostratigraphic correlation durschning the jurassic cretaceous boundary interval is difficult due to relatively stable 13c values compounded by a slope which is too slight there is no clear isotopic marker event for the system boundary the long term gradual change towards more negative carbon isotope values through the jurassic cretaceous transition has previously been explained by increasingly oligotrophic condition and lessened primary production however this contradicts the reported increase in 87sr 86sr ratios suggesting intensification of weathering and a decreasing contribution of non radiogenic hydrothermal sr and presumably a concomitant rise in nutrient input into the oceans the concomitant rise of modern phytoplankton groups dinoflagellates and coccolithophores would have also led to increased primary productivity making the negative carbon isotope trend even more notable we suggest that gradual oceanographic changes more effective connections and mixing between the tethys atlantic and pacific oceans would have promoted a shift towards enhanced burial of isotopically heavy carbonate carbon and effective recycling of isotopically light organic matter these processes account for the observed long term trend interrupted only by the weissert event in the valanginian

environmental changes around the jurassic cretaceous transition new nannofossil chemostratigraphic and stable isotope data from the lokut section transdanubian range hungary abstract new biostratigraphical chemical and stable isotope c o data are presented from the lokut section transdanubian range hungary representing a ca 13 m thick continuous succession of lower tithonian lower berriasian pelagic limestones the study is conducted to verify timing of nannofossil events and major palaeoenvironmental changes at the jurassic cretaceous transition including lithogenic input palaeoredox and palaeoproductivity variations nannofossil zones from njt 16b to nkt have been identified in the lokut section and correlated with magnetostratigraphy covering an interval from polarity zone m21r to m18r the nannofossil zone njt 16b spans the interval from the upper part of m21r to lowermost part of m19n2n but its lower limit is poorly defined due to large diachronism in first occurrence fo of nannoconus infans in various tethyan sections fos of n kamptneri minor and n steinmannii minor are situated in the topmost part of the m19n2n and lowermost part of m19n1r magnetozones respectively they are located ca 2 2 5 m above the j k boundary defined as intermedia alpina subzonal boundary which falls within the lower half of magnetozone m19n2n the position of first occurrences of these taxa is similar to that from the puerto escano section southern spain and slightly lower than in italian sections southern alps concentrations of chemical element proxies of terrigenous transport al k rb th decrease towards the top of the lokut section which suggests a decrease in input of terrigenous material and increasing carbonate productivity during the early tithonian and the berriasian slight oxygen depletion at the sea bottom decrease of th u ratio and large increase in concentrations of productive elements p ba ni cu is observed upsection nutrients supply via upwelling seems to be the most likely explanation increase in phosphorus accumulation rate and a microfacies change from saccocoma to calpionellid dominated took place in the polarity chron m19r which apparently coincided with the worldwide nannofossil calcification event related to a bloom of strongly calcified calcareous nannoplankton taxa deposition in the lokut area was probably affected by long term climatic trends aridization and warming decreasing 13c values of bulk carbonates throughout the tithonian and the berriasian are interpreted as a result of a global trend of accelerated carbonate productivity supported by local factors such as increased upwelling intensity and a possible change in the composition of carbonate mud

evidence for a composite organic inorganic fabric of belemnite rostra implications for palaeoceanography and palaeoecology carbonate skeletons of fossil marine organisms are widely used to reconstruct palaeoceanographic parameters specifically the geochemistry of jurassic and cretaceous belemnite rostra is traditionally interpreted to represent near sea surface seawater properties more recently an increasing number of workers have reported significant scatter in geochemical data e g 18o 13c element ca ratio when comparing rostra from the same stratigraphic level or within a single belemnite rostrum this scatter is not explained by differential diagenetic overprint alone here we report petrographic evidence on the primary ultrastructure of rostra of megateuthis middle jurassic and belemnitella and gonioteuthis late cretaceous the biogenic ultrastructure consists of a filigree framework of triaxial branches and tetrahedrons of variable size forming a honeycomb like network data presented here suggest that these rostra yielded as much as 50 to 90 primary pore space on the level of a working hypothesis and in analogy with modern cephalopods we propose that the pore space was formerly filled with body fluid and or organic compounds during the life time of these organisms intra rostral porosity was post mortem occluded by earliest diagenetic isopachous calcite cements of a non biogenic origin these may have been precipitated due to increased alkalinity related to the decay of organic matter if this holds true then the resulting fabric represents a composite biogenic abiogenic structure in order to optically separate the two calcite phases forming a single calcite fibre we employed a wide range of state of the art analytical tools to thin sections and ultra thin sections of well preserved specimens pending a verification of these well supported ultrastructural data by means of high resolution geochemical analyses from biogenic and abiogenic phases we suggest that these findings have significance for those using belemnite rostra as archives of their palaeoenvironment

refining measurements of lateral channel movement from image time series by quantifying spatial variations in registration error abstract remotely sensed data provides information on river morphology useful for examining channel change at yearly to decadal time scales although previous studies have emphasized the need to distinguish true geomorphic change from errors associated with image registration standard metrics for assessing and summarizing these errors such as the root mean square error rmse and 90th percentile of the distribution of ground control point gcp error fail to incorporate the spatial structure of this uncertainty in this study we introduce a framework for evaluating whether observations of lateral channel migration along a meandering channel are statistically significant given the spatial distribution of registration error an iterative leave one out cross validation approach was used to produce local error metrics for an image time series from savery creek wyoming usa and to evaluate various transformation equations interpolation methods and gcp placement strategies interpolated error surfaces then were used to create error ellipses representing spatially variable buffers of detectable change our results show that for all five sequential image pairs we examined spatially distributed estimates of registration error enabled detection of a greater number of statistically significant lateral migration vectors than the spatially uniform rmse or 90th percentile of gcp error conversely spatially distributed error metrics prevented changes from being mistaken as real in areas of greater registration error our results also support the findings of previous studies second order polynomial functions on average yield the lowest rmse and errors are reduced by placing gcps on the floodplain rather than on hillslopes this study highlights the importance of characterizing the spatial distribution of image registration errors in the analysis of channel change

critical specific stream power in gravel bed rivers experiments with marked pebbles were carried out on different sized rivers of the belgian ardenne catchment areas varying from less than 1 km2 to 2700 km2 specific stream power required to cause bedload movement was evaluated and critical values were obtained three types of relationship between critical specific stream power 0 and grain size d were established the values for 0 in the largest river the ourthe were the lowest and were close to the values obtained for mountainous rivers carrying large boulders in medium sized rivers catchment area between 40 and 500 km2 the critical unit stream power was higher it is likely that it is due to the bedform s greater resistance this resistance would use up some of the energy that can cause movement and transport of bedload the amount of resistance of the bedform can be expressed as bedform shear stress determined by the relationship between grain shear stress that determines movement and transport of the bedload and the total shear stress this ratio varies between 0 4 and 0 5 in the medium sized rivers compared to 0 7 in the ourthe in headwater streams less than 20 km2 there is greater loss of energy due to bedform resistance 0 3 critical specific stream power is higher in this third type of river than in the other two

carbon isotope excursions in boreal jurassic cretaceous boundary sections and their correlation potential abstract the jurassic cretaceous j k boundary is one of the most problematic points on the geological timescale the boundary is not defined by a global stratotype section and point gssp because of the absence of well defined by significant faunal turnover widely correlatable biostratigraphic levels to fix the base of the berriasian a distinct earliest berriasian positive carbon isotope excursion is identified in the boreal marine carbonate belemnites carbon records from the maurynya river northern urals and the nordvik peninsula northern east siberia the excursion is found within the top part of the upper volgian craspedites taimyrensis ammonite zone slightly above the j k boundary which was established by palaeomagnetic data because a significant positive 13 c shift was also observed immediately above the j k boundary in the tethyan guppen heuberge pelagic carbonate section switzerland this positive carbon isotope event can be regarded as a useful marker for a panboreal and boreal tethyan correlation of j k boundary beds this 13 c excursion is interpreted as a record of increased rates of organic carbon burial the 13 c data obtained previously for the upper volgian and ryazanian in different boreal regions are also analysed in this paper other well documented carbon isotope excursions with less global significance allow the creation of a composite carbon isotope curve for boreal regions that characterises the upper volgian and ryazanian in detail

high resolution satellite and airborne thermal infrared imaging of precursory unrest and 2009 eruption at redoubt volcano alaska abstract a combination of satellite and airborne high resolution visible and thermal infrared tir image data detected and measured changes at redoubt volcano during the 2008 2009 unrest and eruption the tir sensors detected persistent elevated temperatures at summit ice melt holes as seismicity and gas emissions increased in late 2008 to march 2009 a phreatic explosion on 15 march was followed by more than 19 magmatic explosive events from 23 march to 4 april that produced high altitude ash clouds and large lahars two or three lava domes extruded and were destroyed between 23 march and 4 april after 4 april the eruption extruded a large lava dome that continued to grow until at least early july 2009

predicting grain size in gravel bedded rivers using digital elevation models application to three maine watersheds riverbed grain size controls suitability of spawning habitat for threatened fish species motivated by this relationship we developed a model that uses digital elevation models dems to predict bed grain size we tested the accuracy of our model and two existing models with channel measurements from high resolution airborne light detection and ranging lidar dems all three models assume that bed grain size is a function of reach average high flow channel hydraulics measured by shear stress or stream power our test data are field measurements of median grain size d 50 at 276 stations along four rivers in maine pleistocene continental glaciation strongly influences the longitudinal profiles which have alternating steep and gradual segments we exploit the resulting variations in sediment supply to understand the controls on model success or failure in predicting bed grain size results show that all three models have 70 success in predicting d 50 within a factor of two overall and better where the rivers are coarse gravel bedded 80 success where d 50 16 mm this similarity is unsurprising given that the models primarily rely on channel gradient s and drainage area as inputs measurements of s from lidar dems yield only a modest improvement in model success over those from topographic maps we find that our model works best in sediment starved steep reaches model failures fall into two broad categories 1 relatively fine grained d 50 d 50 we argue that models based on airborne infrared lidar dems may reach a maximum around 80 85 accuracy due to these sub reach scale factors which cannot be easily measured from dems the overall success of the models in predicting grain size indicates that the morphology of these channels has adjusted to the imposed s and sediment load during the 15 k y since deglaciation and through the period of anthropogenic channel change over the past three centuries

mapping of neoproterozoic source rocks of the huqf supergroup in the sultanate of oman using remote sensing abstract in recent years the neoproterozoic huqf supergroup formations of the oman salt basins have been the target for oil exploration the present study maps the surficial exposure of the huqf supergroup in and around khufai dome of the huqf area in the sultanate of oman using low cost multi spectral remotely sensed satellite data and image processing methods such as decorrelation stretching principal component analysis pca and spectral angle mapper sam as alternative to expensive and time consuming tools which have the capability and potential to be used by geoscientists for oil exploration in this research the study of advanced spaceborne thermal emission and reflection radiometer aster spectral bands 8 3 and 1 by decorrelation stretching well discriminated the masirah bay the khufai the shuram and the buah formations of the nafun group the source rocks of huqf supergroup with the quaternary deposits the analysis of visible and near infrared shortwave infrared spectral bands of aster by pca clearly showed the occurrence and spatial distribution of such formations in the rgb principal component images r pc1 g pc2 b pc3 the spatial distributions of such formations are assessed by confusion matrix after using maximum likelihood ml spectral angle mapper sam and spectral information divergence sid algorithms the matrix of ml algorithm has provided the best overall accuracy of 92 93 and kappa coefficient of 0 92 the minerals of the formations were detected by sam further the detection of such mineral groups was confirmed through the aster thermal infrared tir spectral indices image developed using the carbonate index ci quartz index qi and mafic index mi all results of image analyses are evaluated in the field and laboratory studies the study also evaluates the satellite data and image processing methods for the formations of jabal akhdar the equivalent formations of the khufai dome to show the sensor capability and the use of the image processing methods to study the source rocks the results of the study provided similar discriminations comparable to the khufai dome therefore the data and the techniques are recommended to the exploration geologists for use in similar regions of the world

recent large magnitude floods and their impact on valley floor environments of northeastern yellowstone abstract the lamar river watershed of northeastern yellowstone contains some of the most diverse and important habitat in the national park broad glacial valley floors feature grassland winter range for ungulates riparian vegetation that provides food and cover for a variety of species and alluvial channels that are requisite habitat for native fish rapid neogene uplift and quaternary climatic change have created a dynamic modern environment in which catastrophic processes exert a major influence on riverine riparian ecosystems uplift and glacial erosion have generated high local relief and extensive cliffs of friable volcaniclastic bedrock as a result steep tributary basins produce voluminous runoff and sediment during intense precipitation and rapid snowmelt recent major floods on trunk streams deposited extensive overbank gravels that replaced loamy soils on flood plains and allowed conifers to colonize valley floor meadows tree ring dating identifies major floods in 1918 ca 1873 and possibly ca 1790 in 1996 and 1997 discharge during snowmelt runoff on soda butte creek approached the 100 year flood estimated by regional techniques with substantial local bank erosion and channel widening indirect estimates show that peak discharges in 1918 were approximately three times greater than in 1996 with similar duration and much greater flood plain impact nonetheless 1918 peak discharge reconstructions fall well within the range of maximum recorded discharges in relation to basin area in the upper yellowstone region the 1873 and 1918 floods produced lasting impacts on the channel form and flood plain of soda butte creek channels may still be locally enlarged from flood erosion and net downcutting has occurred in some reaches leaving the pre 1790 flood plain abandoned as a terrace gravelly overbank deposits raise flood plain surfaces above levels of frequent inundation and are well drained therefore flood plain soils are drier noncohesive gravels also reduce bank stability and may have persistent effects on channel form overall floods are part of a suite of catastrophic geomorphic processes that exert a very strong influence on landscape patterns and valley floor ecosystems in northeastern yellowstone

strontium isotope stratigraphy potential resolution and event correlation abstract a new generation 87sr 86sr isotope curve for the phanerozoic seawater based on a compilation of 3635 stratigraphically well defined and well preserved skeletal components results in a substantially narrower band with some discrepancies if compared to the curve of burke et al 1982 which is based mostly on whole rock samples the results obtained from low mg calcite shells foraminifers belemnites brachiopods and oysters are mostly superior to those from phosphatic skeletal components such as conodonts even if the latter are exceptionally well preserved cai 1 5 at this stage the phanerozoic data set based on fossils is patchy for the cambrian upper ordovician lower devonian and upper carboniferous triassic intervals the major practical constraint that precludes delineation of an unequivocal sr isotope curve for the phanerozoic seawater is the uncertainty in the assignment of absolute ages to the samples as a result the curve is in reality a band this is a reflection of the limitations of biostratigraphy and geochronology that are inherited by any derivative correlation and dating technique including isotope stratigraphy it is therefore unlikely that in the near future the sr isotope stratigraphy will surpass the resolution capability of biostratigraphy as a global correlation tool on the other hand if complemented by lithostratigraphy it is potentially a valuable tool for correlation of sequences on intrabasinal and regional scales taking into account the above limitations careful consideration must be given to assignment of higher order isotope peaks to specific events within a biozone and to the use of such events as a global correlation tool

thresholds and the spatial variability of flood power during extreme floods abstract analysis of the effects of extreme events on overall landscape form has shifted geomorphic attention away from a focus on the magnitude and frequency relationship of discharge to a focus on flood power this paper analyzes the variation in flood power both at a station and downstream in a basin of differing lithologies and discusses the geologic and geomorphic controls on flood power design floods ranging from the 2 year discharge tothe 500 year discharge are routed trough a drainage basin and channel boundary shear stress and unit stream power are calculated using hec 2 along 21 cross valley transects because of the strong lithologic control on valley width and channel slope an irregular downstream pattern of flood power emerges which reflects primarily the pattern in valley width narrow valleys correspond to a greater percent of channel conveyance during large magnitude floods and increasing rates of depth increases thus maximizing flood power in these zones the opposite occurs in anomalously wide valleys where flood power is minimized a downstream spatial pattern emerges reflecting both local and general controls for a given probability event flood power varies at least threefold within the basin with a maximum occuring in a specific downstream section holding flood power constant produces an extremely wide range in flow probabilities in order to establish a link between critical flood power magnitude and flow frequency minimum flood powers are developed from an analysis of previous work on catastrophic flooding for humid alluvial channels these minimum thresholds tentatively correspond to 100 n m2 or 300 w m2 for shear stress and unit stream power respectively discharges required to attain these critical flood powers vary from events roughly twice the 100 year flood to a maximum of roughly 18 times the discharge of the 100 year flood

a revised classification of limestones abstract the most widely used classifications of limestones are now thirty years old and our appreciation of the diagenetic effects on limestone textures is now much greater a revision of the classifications of dunham 1962 and embry and klovan 1971 is offered and new diagenetic categories are proposed the confusing term lime mudstone is replaced by calcimudstone two categories of diagenetic textures are recognized non obliterative and obliterative the former contains limestones which are almost wholly composed of diagenetic cement cementstones and those whose fabric is the result of intergranular pressure solution condensed and fitted grainstones obliterative categories include limestones and dolomites whose original fabric has been destroyed sub categories include sparstones or dolosparstones crystals 10 m in size and microsparstones dolomicrosparstones crystals 4 10 m in size and dolomicrostones crystals m in size many diagenetic processes can produce fabrics which mimic depositional ones and these are reviewed

paleoceanographic changes across the jurassic cretaceous boundary the calcareous phytoplankton response abstract calcareous nannoplankton experienced rapid diversification at the jurassic cretaceous boundary including the appearance of several highly successful and long ranging cretaceous genera this study examines at high resolution calcareous nannofossil assemblages and bulk rock oxygen and carbon isotopes of lower tithonian to lower berriasian 151 to 142 ma sediments recovered in deep sea drilling project hole 534a central atlantic ocean the results show major changes in assemblage composition and abundance of three genera conusphaera nannoconus and polycostella conusphaera dominates the nannolith assemblage in the late middle tithonian conusphaera world while the nannoconid dominance nannoconus world began in the berriasian the acme peak of the genus polycostella in the late tithonian partially superimposes that of conusphaera although these genera are indicators of warm oligotrophic surface waters stable isotope data suggest that the individual taxa may flourish in slightly different ecological regimes nannoconus flourished under warmer and possibly more nutrient depleted surface waters than polycostella a genus that thrived in relatively cooler waters these findings imply paleoceanographic changes across the j k boundary interval with a cooling in the late tithonian followed by a temperature increase in the berriasian because the transfer of these heavily calcified nannolith taxa to the seafloor is more efficient than that of average coccolithophorids the j k evolutionary event changed carbonate cycling and burial in the oceans

alteration mineralogy at the cerro la mina epithermal prospect patagonia argentina field mapping short wave infrared spectroscopy and aster images the cerro la mina prospect located in the los menucos area argentina is currently being explored for epithermal gold mineralization triassic jurassic hydrothermal activity produced intense alteration of rhyolites andesites ignimbrites and tuffs of the late triassic los menucos group in the somun cura massif a detailed surface map of the principal alteration assemblages at cerro la mina was produced employing field mapping supported by short wave infrared swir field spectroscopy petrography x ray diffraction xrd and scanning electron microscopy sem advanced argillic argillic and silicic alteration zones and their internal mineral assemblage variations were recognized at cerro la mina the silicification consists of massive bodies of fine grained quartz and minor vuggy quartz locally containing disseminated aggregates of pyrite and rutile advanced argillic alteration of magmatic hydrothermal origin occurs adjacent to the silicic alteration zones and can be subdivided into three mineral assemblages 1 stage 1 alunite quartz dickite kaolinite pyrophyllite diaspore rutile pyrite barite 2 dickite kaolinite pyrophyllite diaspore pyrite barite and 3 dickite quartz diaspore the advanced argillic and silicic alteration grades to argillic alteration comprising three mineral assemblages 1 kaolinite dickite quartz illite smectite 2 kaolinite illite smectite ferroan clinochlore and 3 illite quartz muscovite kaolinite supergene alteration which locally overprints the prior alteration zones consists of jarosite hematite goethite stage 2 alunite aluminum phosphate sulfate aps poorly crystalline kaolinite consistent discrimination of the main alteration minerals of this prospect was also achieved by means of satellite multispectral remote sensing the application of image processing techniques specifically designed for mineral mapping to selected spectral bands of the terra aster multispectral sensor resulted in a detailed alteration map for the entire prospect comparison between the results achieved through remote sensing with field data on the cerro la mina confirmed the accuracy of the former the silicification and minor vuggy quartz the abundant dickite and the coarse grained hypogene alunite among other advanced argillic alteration assemblages suggest that cerro la mina corresponds to a volcanic hydrothermal leached environment possibly controlled by permeable lithological units these characteristics led us to interpret this prospect as a possible lithocap similar to those that typically host subsequent high sulfidation mineralization

the missing dimension effects of lateral variation on 1 d calculations of fluvial bedload transport most calculations of bedload transport in rivers including those in numerical models of aggradation and degradation are 1 d all hydraulic and transport rate calculations are averaged over the channel width because bedload transport laws are nonlinear width averaged calculations will underestimate the true bedload flux if there is any local spatial variation in either the bed or the flow this paper analyses the effects on bedload transport capacity of spatial variation in applied and critical c shear stress separately and in combination a simple but versatile statistical model is used to represent variability in with allowance for differences between sand and gravel bed rivers and for below bankfull flow bedload flux is shown to increase greatly with the variance of especially in gravel bed rivers variability in c through bed patchiness may increase reduce or make little difference to bedload flux depending on the correlation between and c simple width averaging leads to severe underestimation of bedload transport in most conditions some alternatives are considered the findings have implications for sediment routing models srms but further research is needed to explore the issue fully

comparison of carbonate c and o stable isotope records across the jurassic cretaceous boundary in the tethyan and boreal realms abstract carbon and oxygen stable isotope records were compared for jurassic cretaceous j k boundary sections located in the tethyan realm brodno western slovakia and puerto escano southern spain bulk limestones and the boreal realm nordvik peninsula northern siberia belemnites since a detailed biostratigraphic correlation of these tethyan and boreal sections is impossible due to different faunal assemblages correlation of the isotope records was based on paleomagnetic data this novel approach can improve our understanding of the synchroneity of individual isotope excursions in sections where detailed biostratigraphic correlation is impossible no significant excursions in either the carbon or oxygen isotope records to be used for future boreal tethyan correlations were found around the j k boundary the upper tithonian and lower berriasian magnetozones m20n to m18n in the studied sections at the nordvik section where a much longer section middle oxfordian basal boreal berriasian was documented the transition from the middle oxfordian to the kimmeridgian and further to the volgian is characterized by a decrease in belemnite 18 o values from 18 o values up to 1 6 vs v pdb in the oxfordian to values between 0 3 and 0 8 in the late volgian and earliest boreal berriasian this trend which has previously been reported from the russian platform and tethyan realm sections corresponds either to gradual warming or a decrease in seawater 18 o supposing that the oxygen isotope compositions of seawater in the arctic boreal and tethyan realms were similar then the differences between oxygen isotope datasets for these records indicate differences in temperature the boreal tethyan temperature difference of 7 9 c in the middle and late oxfordian decreases towards the j k boundary indicating a significant decrease in latitudinal climatic gradients during the late jurassic two positive carbon isotope excursions recorded for the middle oxfordian and upper kimmeridgian in the nordvik section can be correlated with a similar excursion described earlier for the russian platform minor influence of biofractionation at the carbon isotopes and the influence of migration of belemnites to deeper slightly cooler water at the oxygen isotopes cannot be excluded for the obtained belemnite data

comparative assessment of three approaches for deriving stream power plots along long profiles in the upper hunter river catchment new south wales australia abstract the downstream distribution of stream power is derived and analysed for 11 different streams in the upper hunter river catchment australia stream long profiles were produced in a gis environment using dem data and catchment area discharge analysis these profiles were analysed using three approaches namely long profile smoothing curve fitting and a theoretical model the methodology for deriving stream power profiles using these three approaches is discussed the long profile smoothing method provides a good approximation of the subcatchment variability in stream power trends the curve fitting method shows that higher order exponential curves provide a better fit for long profile data for the streams of the upper hunter river catchment second order exponential curves fit well with significantly less error the curve fitting method predicts a bimodal upstream and midstream distribution of stream power which is a deviation from our earlier understanding of a single midstream peak the theoretical approach provides a mathematical expression of the observed bimodal stream power distribution the bimodal distribution emphasises the erosion potential of headwater reaches the resultant stream power distribution provides a catchment scale characterisation of the distribution of available energy in any given system using these approaches the variability of stream power in headwater reaches is explained by discharge variability while variability in midstream and downstream reaches is related to high variability in channel gradient

a fuzzy gis model to determine confluence morphological sensitivity to tributary inputs at the watershed scale abstract confluences are key nodes of river systems that have the potential of disrupting downstream longitudinal trends in the main river through inputs of water sediment wood or ice delivered from tributaries from a geomorphological perspective confluence zones are particularly active and thus susceptible to increased flooding and bed instability which in turn pose serious threats to infrastructure however not all confluences are active despite major advances in our knowledge of confluence dynamics there has been limited progress in the development of low complexity practical tools that use remotely sensed data to predict the spatial distribution of the main river s sensitivity to tributary inputs we have thus developed a novel semi automated gis model that uses a fuzzy approach to integrate key factors unit stream power valley confinement and sediment connectivity potential in order to map the distribution of the confluence morphological sensitivity cms index at the watershed scale the gis model was tested using digital elevation models of high lidar 1 m and coarser 10 m resolution in the coaticook and gaspesie watersheds quebec canada results indicate that the model is useful for detecting geomorphologically active confluences and the resulting sensitivity of the main channel and thus has potential to be used in diverse river management applications e g hazard reduction and freedom space mapping

making riverscapes real abstract the structure and function of rivers have long been characterized either by 1 qualitative models such as the river continuum concept or serial discontinuity concept which paint broad descriptive portraits of how river habitats and communities vary or 2 quantitative models such as downstream hydraulic geometry which rely on a limited number of measurements spread widely throughout a river basin in contrast authors such as fausch et al 2002 and wiens 2002 proposed applying existing quantitative spatially comprehensive ecology and landscape ecology methods to rivers this new framework for river sciences which preserves variability and spatial relationships is called a riverine landscape or a riverscape application of this riverscape concept requires information on the spatial distribution of organism scale habitats throughout entire river systems this article examines the ways in which recent technical and methodological developments can allow us to quantitatively implement and realize the riverscape concept using 3 cm true color aerial photos and 5 m resolution elevation data from the river tromie scotland we apply the newly developed fluvial information system which integrates a suite of cutting edge high resolution remote sensing methods in a spatially explicit framework this new integrated approach allows for the extraction of primary fluvial variables such as width depth particle size and elevation from these first order variables we derive second order geomorphic and hydraulic variables including velocity stream power froude number and shear stress channel slope can be approximated from available topographic data based on these first and second order variables we produce riverscape metrics that begin to explore how geomorphic structures may influence river habitats including connectivity patchiness of habitat and habitat distributions the results show a complex interplay of geomorphic variable and habitat patchiness that is not predicted by existing fluvial theory riverscapes thus challenge the existing understanding of how rivers structure themselves and will force development of new paradigms

a catchment scale assessment of patterns and controls of historic 2d river planform adjustment abstract the supply transfer and deposition of sediment from channel headwaters to lowland sinks is a fundamental process governing upland catchment geomorphology and can begin to be understood by quantifying 2d river planform adjustments over time this paper presents a catchment scale methodology to quantify historic patterns of 2d channel planform adjustment and considers geomorphic controls on 2d river stability the methodology is applied to 18 rivers total length 24 km in the upland headwaters of the previously glaciated wasdale catchment 45 km2 lake district northwest england planform adjustments were mapped from historic maps and air photographs over six contiguous time windows covering the last 150 yr a total of 1048 adjustment and stable reaches were mapped over the full period of analysis 1860 2010 32 8 km of the channels studied were adjusting contrasts were identified between the geomorphic characteristics slope catchment area unit specific stream power channel width and valley bottom width of adjusting and stable reaches the majority of adjustments mapped were observed in third and fourth order channels in the floodplain valley transfer zone where the channels were laterally unconfined mean valley bottom widths of 230 180 m with low sediment continuity in contrast lower order channels were typically confined mean valley bottom widths of 31 43 m and showed relative 2d lateral stability hence valley bottom width was found to be important in determining the available space for rivers to adjust over the full period of analysis 38 of planform adjustments involved combined processes for example as bar and bend adjustments the study demonstrates the importance of stream network hierarchy in determining spatial patterns of historic planform adjustments at the catchment scale the methodology developed provides a quantitative assessment of planform adjustment patterns and geomorphic controls which is needed to support the prioritisation of future river management and restoration

high northern palaeolatitude jurassic cretaceous palaeotemperature variation new data from kong karls land svalbard abstract the traditional view of warm equable global climates in the mesozoic with weakly developed latitudinal temperature gradients has been challenged by several recent studies however reliable high palaeolatitude palaeotemperature data is still rare in this study palaeotemperature data based on oxygen stable isotope palaeothermometry of well preserved mid jurassic to lower cretaceous belemnites from kong karls land svalbard are presented these data show cool high latitude marine isotopic palaeotemperatures for endemic species during the lower to mid valanginian 7 7 c which may be compatible with the formation of high latitude ice middle bathonian to kimmeridgian samples give warmer isotopic palaeotemperatures 9 4 c whilst samples from the aalenian to bajocian give isotopic palaeotemperatures which are warmer still 12 7 c comparison of the callovian temperatures with those from a mid latitude location shows them to be warmer than would be expected if previous latitudinal temperature gradients are correct this may be due to the ameliorating effect of oceanic heat transport pole wards from the panthalassa ocean via the south anyui ocean

downstream variation in stream power abstract stream power has a significant influence on many form and process attributes of the fluvial system using a similar approach to that suggested by d m lawler in 1992 and 1995 a model is developed to explore how stream power might vary in the downstream direction based on the assumption that the longitudinal profile of the river has an exponential form no particular discharge is necessarily specified but near bankfull flows are regarded as significant morphologically and one such discharge is the focus here total stream power per unit channel length qs is predicted to peak at an intermediate location the position of which depends on the ratio b where b and are the downstream rates of change of discharge and slope respectively if b is a relatively conservative quantity then the form of the longitudinal profile and in particular its degree of concavity will have the major influence on the position of maximum stream power specific stream power w is even more sensitive to and is expected to peak closer to the headwaters about half way between source and the location of the stream power maximum although this will depend on how channel width w varies with distance from source the model is tested along three connected streams of different size in the catchment of the river trent taking advantage of a relationship between mean annual flood and link magnitude which enables this near bankfull discharge to be estimated at any point within the network the model is verified in so far as stream power does attain a mid basin maximum but the observed and predicted locations of the maxima do not always correspond largely because of the distinctive variation in discharge and especially slope along individual pathways for example maximum power lies far downstream along the trent because of the large increase in mid basin discharge associated with a series of large closely spaced tributaries the importance of slope is borne out by the near headwater locations for specific power maxima which tend to be further upstream than predicted along all three rivers as a result of the steepness of upper reaches the variety of geomorphic settings produces deviations from expectation which has implications for the movement and storage of material in the fluvial system

primary and diagenetic isotopic signals in fossils and hemipelagic carbonates the lower jurassic of northern spain stable isotope and trace element analyses of 230 jurassic pliensbachian toarcian samples from northern spain have been performed to test the use of geochemical variations in fossils belemnites and brachiopods and whole rock hemipelagic carbonates as palaeoceanographic indicators although the succession analysed reinosa area westernmost basque cantabrian basin has been subject to severe thermal alteration during burial diagenesis the samples appear to be well preserved the degree of diagenetic alteration of the samples has been assessed through the application of integrated petrographic chemical and cathodoluminescence analyses it is demonstrated that brachiopods and whole rock carbonates although widely used for palaeoceanic studies do not retain their primary marine geochemical composition after burial diagenesis in contrast there is strong evidence that belemnite rostra preserve original isotopic values despite pervasive diagenesis of the host rock well preserved belemnite shells non luminescent to slightly luminescent typically show stable isotope values of 4ae3 to 0ae7 d 13 c 0ae7 to 3ae2 d 18 o and trace element contents of 950 l gg 1 sr and sr mn ratios 80 this study suggests that the degree to which diagenesis has affected the preservation of an original isotopic composition may differ for different low mg calcite fossil shells and hemipelagic bulk carbonates behaviour that should be considered when marine isotopic signatures from other ancient carbonate rocks are investigated multiple non luminescent contemporaneous belemnite samples passed the petrographic and geochemical tests to be considered as palaeoceanic recorders yet their d 13 c and d 18 o values exhibited moderate scatter such variability is likely to be related to the palaeoecological behaviour of belemnites and or highfrequency secular variations in sea water chemistry superimposed on the longterm isotopic trend a pronounced positive carbon isotope excursion up to 4ae3 is documented in the early toarcian serpentinus biozone which correlates with the toarcian d 13 c maximum reported in other european and tethyan regions

the natural and human structuring of rivers and other geomorphological systems a tribute to william l graf this special issue honors the contributions of william l graf to geomorphology and river science a hallmark of will s work over the course of his career has been a focus on the natural and human structuring of river systems more broadly will has been an innovator and leader who has shaped the way in which geomorphologists conduct research through his work he has made fundamental contributions to basic fluvial theory to the understanding of human impacts on river systems and to policy relevant science he has demonstrated by example how to pursue policy relevant science and to participate in science based policy formulation his contributions to river science can be classified into several themes 1 the hydrology and geomorphology of suburban drainage systems 2 riparian vegetation and river systems 3 the spatial structure and dynamics of incised channels 4 the dynamics of dryland river systems 5 heavy metals in river systems 6 dams and dam removal and 7 water and public policy the papers in this special issue reflect many aspects of these themes and address topics related to 1 the understanding of rivers and other geomorphic systems in the midst of dynamic physical change 2 human influences on geomorphic processes 3 the intersection of geomorphology and public policy and 4 the fusion of geomorphic analysis and giscience

geological and petrophysical applications of imaging infrared spectroscopy for mineralogical analysis of core and cuttings examples from the north sea norwegian sea and barents sea

thermal infrared remote sensing and kirchhoff s law 1 laboratory measurements by the end of this century the earth observing system eos will provide worldwide thermal infrared multispectral images of the earth presenting geologists with a new kind of remote sensing data for interpretation thus it has become essential to understand the spectral emittance behavior of terrestrial surface materials perhaps the most fundamental question to be answereed is the extent to which such materials follow kirchhoff s law epsilon 1 r under laboratory and field conditions especially when a sample displays a thermal gradient we present the first rigorous quantitative comparison of directional and hemispherical reflectance and directional emittance of rock and soil samples in the laboratory with thermal gradients induced by heating them from below and allowing them to radiate to a colder background the results show that only an extemeley low density sample composed of fine particles sifted into a fairy castle structure displays a thermal gradient steep enough within the infrared skin depth to cause significant 6 departure from kirchhoff s law there is no detectable effect on the more normal terrestrial samples such as soils and rocks measured in the laboratory even when semitransparent coatings are involved thus both emittance and reflectance measurements can be used to calculate sample emissivity for most terrestrial surface materieals however the effect on kirchhoffian behavior of different field environments which may induce a steeper thermal gradient in particulate samples has yet to be determined and some low density surface materials like newly fallen snow frost and efflorescent salts on playas have yet to be measured in emittance

mineral mapping on the chilean bolivian altiplano using co orbital ali aster and hyperion imagery data dimensionality issues and solutions abstract hyperspectral data coverage from the eo 1 hyperion sensor was useful for calibrating advanced land imager ali and advanced spaceborne thermal emission and reflection radiometer aster images of a volcanic terrane area of the chilean bolivian altiplano following calibration the ali and aster datasets were co registered and joined to produce a 13 channel reflectance cube spanning the visible to short wave infrared 0 4 2 4 m eigen analysis and comparison of the hyperion data with the ali aster reflectance data as well as mapping results using various ali aster data subsets provided insights into the information dimensionality of all the data in particular high spectral resolution low signal to noise hyperion data were only marginally better for mineral mapping than the merged 13 channel low spectral resolution high signal to noise ali aster dataset neither the hyperion nor the combined ali aster datasets had sufficient information dimensionality for mapping the diverse range of surface materials exposed on the altiplano however it is possible to optimize the use of the multispectral data for mineral mapping purposes by careful data subsetting and by employing other appropriate image processing strategies

the complexity of the real world in the context of the field tradition in geomorphology abstract among the dominant twentieth century conceptual models of geomorphology that rely on insights resulting from field based research are stanley a schumm s formulations of complex response intrinsic thresholds river metamorphosis and spatial zonation of drainage basins schumm s research focused primarily on finer grained alluvial channels in lower relief environments as a result of his work most investigators now approach river process and form within a framework based on three fundamental assumptions first channel changes are abrupt and driven by crossing external and internal thresholds second channel change is likely to be asynchronous resulting in different portions of a river or a river network behaving in very different manners at a given point in time third different portions of a river network are dominated by distinct disturbance regimes and resulting suites of geomorphic processes and forms more recent research on resistant boundary mountain channels illustrates how field evidence demonstrates that river process and form are inherently nonlinear with spatial and temporal thresholds multithread channels can form within unconfined valley segments in mountainous river networks of the colorado front range but only in the presence of biotic drivers in the form of i old growth forest that facilitates the formation of closely spaced channel spanning logjams or ii beavers that build dams thresholds of channel and valley geometry govern the occurrence and persistence of jams and dams and these channel obstructions initiate specific nonlinear responses in valley and channel form when the biotic drivers are removed river metamorphosis occurs alluvial channels which are typically regarded as being relatively responsive to changes in water and sediment yield and substrate composition and channels with more resistant boundaries that typically respond to external changes over longer timespans exhibit nonlinear complex behavior in both cases the nonlinear behavior of rivers with numerous interdependent variables multiple internal and external thresholds and complex responses would be difficult to conceptualize and quantify in the absence of extensive field data one of the management implications of complex nonlinear behavior is that a one size fits all approach to managing rivers is inadequate field research initially focused on understanding specific examples of river process and form revealed underlying patterns that give rise to conceptual models broadly applicable within fluvial geomorphology

exploration information systems a proposal for the future use of gis in mineral exploration targeting abstract the advent of modern data collection and storage technologies has brought about a huge increase in data volumes with both traditional and machine learning tools struggling to effectively handle manage and analyse the very large data quantities that are now available the mineral exploration industry is by no means immune to this big data issue exploration decision making has become much more complex in the wake of big data in particular with respect to questions about how to best manage and use the data to obtain information generate knowledge and gain insight one of the ways in which the mineral exploration industry works with big data is by using a geographic information system gis for example gis platforms are often used for integration interrogation and interpretation of diverse geoscience and mineral exploration data with the goal of refining and prioritising known and identifying new targets here we i briefly discuss the importance of carefully translating conceptual ore deposit models into effective exploration targeting maps ii propose and describe what we term exploration information systems eis a new idea for an information system designed to better integrate the conceptual mineral deposit model i e the critical and constituent processes of the targeted mineral system with data available to support exploration targeting and iii discuss how best to categorise mineral systems in an eis as scale dependent subsystems to form mineral deposits our vision for the future use of eis in exploration targeting is one whereby the mappable ingredients of a targeted mineral system are translated and combined into a set of weighted evidence or proxy maps automatically resulting in an auto generated mineral prospectivity map and a series of ranked exploration targets we do not envisage the eis replacing human input and ingenuity rather we envisage the eis as an additional tool in the exploration toolbox and as an intelligence amplifying system in which humans are making use of machines to achieve the best possible results

a conceptual model for meander initiation in bedload dominated streams a simple analytic model is presented relating local sediment transport capacity to variance in the transverse shear stress distribution in a stream channel the model is used to develop a physically based conceptual model for the initiation of meandering in straight bedload dominated streams as a result of a feedback mechanism the feedback maximizes the cross sectional shear stress variance and in order to achieve stability ultimately minimizes the energy slope at repeated locations along the channel subject to steady state mass flux and the stability of the channel boundary these locations develop into pools in a fully developed meandering channel they represent attractor states wherein sediment continuity is satisfied using the least possible energy expenditure per unit length of channel however since the cross sectional geometry of a pool and the adjacent bar is asymmetric these attractor states are only conditionally stable requiring strong curvature induced secondary circulation to maintain their asymmetry between two successive pools a stream occupies a metastable higher energy state corresponding to a riffle that requires greater energy expenditure per unit length of channel to transport the same volume of sediment the model we present links processes at the scale of a channel width to adjustments of the channel sinuosity and slope at the scale of a channel reach we argue that the reach scale extremal hypotheses employed by rational regime models are mathematical formalisms that permit a one dimensional theory to describe the three dimensional dynamics producing stream morphology our model is consistent with the results from stream table experiments with respect to both the rate of development of meandering and the characteristics of the equilibrium channel morphology copyright 2006 john wiley sons ltd

climatic and oceanographic isotopic signals from the carbonate rock record and their preservation stable isotopic data from marine limestones and their constituent fossils and marine cements can provide quantitative evidence for changes in global climate and ocean circulation oxygen isotopic data can indicate changes in temperature and ocean composition whereas stratigraphic variation in carbon isotope ratios may reflect changes in the carbon cycle that can be linked to changes in oceanic productivity and atmospheric greenhouse gases terrestrial carbonates meteoric cements calcretes and speleothems similarly offer significant potential for understanding the evolution of terrestrial climates by providing evidence for the composition of rainwater and the nature of vegetative cover primary environmental isotopic signals may be obscured by the effects of post depositional diagenetic alteration cementation and replacement reactions can take place in a wide range of diagenetic environments the diagenetic history of an individual limestone is determined by a combination of its mineralogical diagenetic potential and depositional setting together with subsequent changes in relative sea level and burial history carbon isotopic values are less prone to alteration during diagenesis than oxygen values but shifts can be significant where organogenic carbon is incorporated linear covariation of carbon and oxygen values is not a reliable indicator of diagenetic alteration water rock interaction and fluid mixing may produce non linear distributions attempts to determine long term changes in climatic and oceanographie conditions through isotope stratigraphy of shallow water limestones must include an assessment of the diagenetic history of the materials analysed petrographic examination using conventional microscopy backed up where appropriate by cathodoluminescence and scanning electron microscopy together with elemental and strontium isotopic analysis can help to identify the effects of diagenetic alteration where material with a range of different degrees of alteration is preserved in the same sediment it may be possible to compare patterns of isotopic and elemental variation and to attempt to unravel the effects of diagenesis in order to determine primary environmental isotopic signals recent research has shown that these techniques can be successfully employed in both phanerozoic and precambrian sediments

preservation of delta 18 o and delta 13 c in belemnite rostra from the jurassic early cretaceous successions stratigraphic collection of 263 belemnite rostra guards from jurassic to lower cretaceous sediments in the moscow area of russia northern germany england new zealand and morocco were analyzed to determine temporal variations in their delta 18 o and delta 13 c as a proxy for isotopic composition of surface seawater internal structures of the rostra were studied using cathodoluminescence and sem techniques their trace element fe mn mg and sr and the stable carbon and oxygen isotope compositions the average stratigraphic resolution is about 1 ma these samples represent a broad range of paleolatitudes and paleoceanographic settings ranging from 42 degrees n to 82 degrees s covering boreal to subtropical brackish to open marine shelf paleoenvironments the rostra originally contained domains enriched in organic matter that were later replaced by luminescent diagenetic calcite thereby generating an impression of seasonal growth rings diagenetic calcite accounts for up to 6 8 percent of the rostrum the trace element content of the rostra range from 227 to 3935 ppm for mg 379 to 1514 ppm for sr and up to 305 and 3662 ppm for mn and fe respectively however selective drilling of only primary calcitic domains resulted in 90 percent of all analyzed samples to fall within the range of trace element values typical for modern low mg calcite shells the chemical and textural data suggest that the primary calcite of the rostra is well preserved as is its isotopic signature the delta 13 c and delta 18 o measurements define oscillating temporal bands of about 3 to 4 per mil width around more or less modern marine values of 2 and 1 per mil respectively oxygen isotopes in the well preserved rostra most likely reflect temperature variations within a approximately 14 or 8 degrees c range the observed 3 to 4 per mil spread of values between contemporaneous specimens which is comparable to the scatter of data reported for modern low mg calcitic brachiopod shells probably reflects the diversity of local ecosystems although some of the spread may be due to real short term temporal variations within single biozones the delta 13 c values of the rostra define a band similar to that of the oxygen isotopes and the temporal oscillations of both isotope curves are commonly in phase the above dataset complemented by the results of jones jenkyns and hesselbo 1994 and jones and others 1994 yields a composite delta 18 o and delta 13 c variations in belemnite guards for the entire jurassic early cretaceous interval for delta 18 o the oscillating band indicates that the most negative values occur at times of independently postulated global and or regional anoxic events such as those in the toarcian and kimmeridgian as well as the aptian these oaes appear to be characterized by up to 10 degrees c higher seawater temperatures than the intervening background times the delta 13 c record shows 13 c depletion for the kimmeridgian event but enrichment for the other two suggesting that the delta 13 c temporal oscillations and oaes are not simply a reflection of surficial productivity due to operation of the biological pump but rather of changing oceanic circulation patterns due to variations in latitudinal surface temperature gradients

accuracy assessment of georectified aerial photographs implications for measuring lateral channel movement in a gis aerial photographs are commonly used to measure planform river channel change we investigated the sources and implications of georectification error in the measurement of lateral channel movement by testing how the number 6 30 and type human versus natural landscape features of ground control points gcps and the order of the transformation polynomial first second and third order affected the spatial accuracy of a typical georectified aerial photograph error was assessed using the root mean square error rmse of the gcps as well as error in 31 independent test points the rmse and the mean and median values of test point errors were relatively insensitive to the number of gcps above eight but the upper range of test point errors showed marked improvement i e the number of extreme errors was reduced as more gcps were used for georectification using more gcps thus improved overall georectification accuracy but this improvement was not indicated by the rmse suggesting that independent test points located in key areas of interest should be used in addition to rsme to evaluate georectification error the order of the transformation polynomial also influenced test point accuracy the second order polynomial function yielded the best result for the terrain of the study area gcp type exerted a less consistent influence on test point accuracy suggesting that although hard edged points e g roof corners are favored as gcps some soft edged points e g trees may be used without adding significant error based upon these results we believe that aerial photos of a floodplain landscape similar to that of our study can be consistently georectified to an accuracy of approximately f5 m with 10 chance of greater error the implications of georectification error for measuring lateral channel movement are demonstrated with a multiple buffer analysis which documents the inverse relationship between the size of the buffers applied to two channel centerlines and the magnitude of change detected between them this study demonstrates the importance of using an independent test point analysis in addition to the rsme to evaluate and treat locational error in channel change studies d 2005 published by elsevier b v

characterising chinese loess stratigraphy and past monsoon variation using field spectroscopy abstract the loess record in china constitutes one of the most important archives of past environmental change and specifically the east asian monsoon system changes in summer monsoon driven pedogenesis are commonly inferred from magnetic susceptibility of loess however there is still controversy as to the signal s origin and the uncertain effects of sediment accumulation rates this is linked to a wider problem that is emerging from recent work that of the relative importance on proxy records such as magnetic susceptibility of both regional climate patterns i e the monsoon and local site specific influences particularly modulated through site specific sedimentation rate at present this is poorly constrained and significantly increases the degree of uncertainty over the wider scale applicability of climate reconstructions from individual sites to resolve this issue for sub orbital timescales a rapidly deployable technique is needed that can be used to test multiple sites and differentiate between local and regional signals this research develops the first use of full spectrum reflectance spectroscopy in studying loess in the field at one site on the south of the loess plateau and utilises statistical analyses to compare such data with magnetic susceptibility records establishment of loess reflectance as a proxy for climate variability will potentially allow extension of the technique from point measurements to an imaging system and so enable the compilation of large data sets in order to investigate lateral facies variations in loess profiles this may allow the extraction of a broad scale climate record field spectra were obtained from 350 to 1100 nm with red edge reflectance spectra indicating the presence of iron oxides previously demonstrated to be indicators of pedogenesis through laboratory measurements an off the shelf camera was also tested with visible wavelength spectra being useful for rapid but general profile characterisation in order to mitigate the effects of bidirectional reflectance distribution function a potential problem in field measurements further laboratory measurement was made of powdered samples 400 2400 nm absorption features indicative of montmorillonite and illite muscovite were noted and stepwise regression modelling utilising absolute reflectance first derivative spectra and continuum removed spectra indicated strong predictive relationships with magnetic susceptibility particularly against the presence of montmorillonite the abundance of such clay minerals could be used to infer weathering rates and hence be used as a proxy for pedogensis reconstructions for the studied site are presented and demonstrate the potential power of loess reflectance environmental reconstruction

the use of multi temporal lidar to assess basin scale erosion and deposition following the catastrophic january 2011 lockyer flood se queensland australia advances in remote sensing and digital terrain processing now allow for a sophisticated analysis of spatial and temporal changes in erosion and deposition digital elevation models dems can now be constructed and differenced to produce dems of difference dod which are used to assess net landscape change for morphological budgeting to date this has been most effectively achieved in gravel bed rivers over relatively small spatial scales if the full potential of the technology is to be realised additional studies are required at larger scales and across a wider range of geomorphic features this study presents an assessment of the basin scale spatial patterns of erosion deposition and net morphological change that resulted from a catastrophic flood event in the lockyer creek catchment of se queensland seq in january 2011 multitemporal light detection and ranging lidar dems were used to construct a dod that was then combined with a one dimensional flow hydraulic model hec ras to delineate five major geomorphic landforms including inner channel area within channel benches macrochannel banks and floodplain the lidar uncertainties were quantified and applied together with a probabilistic representation of uncertainty thresholded at a conservative 95 confidence interval the elevation change distribution ecd for the 100 km2 study area indicates a magnitude of elevation change spanning almost 10 m but the mean elevation change of 0 04 m confirms that a large part of the landscape was characterised by relatively low magnitude changes over a large spatial area mean elevation changes varied by geomorphic feature and only two the within channel benches and macrochannel banks were net erosional with an estimated combined loss of 1 815 149 m3 of sediment the floodplain was the zone of major net deposition but mean elevation changes approached the defined critical limit of uncertainty areal and volumetric ecds for this extreme event provide a representative expression of the balance between erosion and deposition and importantly sediment redistribution which is extremely difficult to quantify using more traditional channel planform or cross sectional surveys the ability of lidar to make a rapid and accurate assessment of key geomorphic processes over large spatial scales contributes to our understanding of key processes and as demonstrated here to the assessment of major geomorphological hazards such as extreme flood events

the aster spectral library version 2 0 abstract the advanced spaceborne thermal emission reflection radiometer aster on nasa s terra platform has been widely used in geological and other science studies in support of aster studies a library of natural and man made materials was compiled as the aster spectral library v1 2 and made available from http speclib jpl nasa gov the library is a collection of contributions in a standard format with ancillary data from the jet propulsion laboratory jpl johns hopkins university jhu and the united states geological survey usgs a new version of the library v2 0 is now available online or via cd which includes major additions to the mineral and rock spectra the aster library provides a comprehensive collection of over 2300 spectra of a wide variety of materials covering the wavelength range 0 4 15 4 m

tex86 and stable δ18o paleothermometry of early cretaceous sediments implications for belemnite ecology and paleotemperature proxy application abstract recent studies have cast doubt on the unadjusted usage of jurassic and cretaceous 18 o paleotemperature data derived from belemnites since the latter data often reflect cooler paleotemperature estimates than would be expected in this study we address this problem by analysing rocks of barremian to early aptian age from two outcrops in northern germany using tex 86 paleothermometry along with 142 belemnite guards studied for their stable isotope 13 c 18 o and trace element composition magnesium strontium iron and manganese both tex 86 and 18 o bel indicate very warm water temperatures for a distinctive black shale sequence of late early barremian age hauptblatterton with temperatures of up to 29 c and 23 c respectively we observe a constant offset of tex 86 temperatures versus the 4 to 5 c cooler 18 o belemnite signal for this interval the late barremian sequence shows an increase of the 18 o bel values from 1 to 0 reflecting temperatures around 16 to 12 c while the contemporaneous tex 86 temperatures vary between 26 and 32 c the common occurrence of belemnites in the anoxic sediments of the early barremian implies however clearly a nektonic way of life similar to that of recent teuthids rather than a nektobenthic one like sepia this in turn suggests that the belemnites investigated here genera praeoxyteuthis aulacoteuthis oxyteuthis and neohibolites were active swimmers which inhabited a deeper habitat below the thermocline in an epicontinental sea of perhaps 100 to 250 m water depth the offset of the tex 86 and 18 o bel data is therefore interpreted to reflect temperature signals from two different depth habitats i e the tex 86 is selectively derived from warm sea surface waters and the belemnites likely occupied deeper and cooler waters with relative increasing salinities in the late barremian this study stresses the importance that the taxonomy paleobiology and ecology of the belemnite taxa genera species used for paleotemperature reconstructions must be considered before the 18 o bel signal can be further interpreted the variation of the 18 o signature gained from one belemnite population of 22 specimens by 1 1 suggests that the 18 o data of individual belemnites should be used with caution for reconstructing long termed paleotemperature trends

late jurassic climate and its impact on carbon cycling abstract the climate of the late jurassic has been characterized by high atmospheric co2 levels and by a monsoonal rainfall pattern in this study we traced the evolution of the global carbon cycle through the late jurassic with the help of carbonate carbon isotope stratigraphy the oxfordian tithonian 13c curve is marked by one major positive carbon isotope excursion with an amplitude 13 c 1 0 middle to late oxfordian and a second minor positive excursion with an amplitude 13 c late kimmeridgian the early kimmeridgian and early tithonian 13c values fluctuate around 13 c 2 0 3 and contrast with the less positive 13c values of early oxfordian and late tithonian age 13 c 1 0 5 a comparison of the late jurassic carbonate carbon isotope curve with the occurrence of organic rich sediments suggests that not only fluctuations in organic carbon burial but also in carbonate carbon burial had an impact on the c isotope record the oxfordian c isotope excursion appears to correspond to a time of overall increased organic carbon burial triggered by increased nutrient transfer from continents to oceans during a time of rising global sea level however episodes of enhanced organic carbon burial during the kimmeridgian and early tithonian are not reflected by prominent spikes in the c isotope record favourable conditions for carbonate platform growth at a time of high global sealevel may have resulted in the stabilisation of the c org c carb burial ratio and hence maintained the 13c record at steady but relatively positive values the middle and late tithonian c isotope values drop below 13 c 1 5 a similar shift to less positive c isotope values was recognized in other c isotope records from the tethys and atlantic oceans and reflects a decrease in the c org c carb burial ratio possibly related to a reorganisation of the global climate system globally widespread marine black shale mature quartzose sandstone assemblages suggest that the relative efficiency of the late jurassic carbon pumps was controlled by weathering erosion and runoff causing widespread marine eutrophication eutrophication favoured the organic carbon pump but it diminished the carbonate platform growth potential the monsoonal rainfall distribution pattern may explain why late jurassic carbonate platforms experienced less severe growth crises than early cretaceous carbonate platforms

testing palaeo environmental proxies in jurassic belemnites mg ca sr ca na ca δ18o and δ13c we test the hypothesis that the noise in belemnite records through time results from changing climate we do so by comparing palaeo proxies mg ca sr ca na ca 18o 13c in two species of toarcian belemnites acrocoelites odontobelus vulgaris 14 specimens and acrocoelites acrocoelites subtenuis 10 specimens deposited in a period of time that was short relative to the timescale of climate change the specimens are interpreted to have been regurgitated from the stomach of a marine predator and so were deposited together in a geological instant of early jurassic time in a o vulgaris isotopic and elemental palaeo proxies group tightly suggesting that this belemnite occupied a restricted environmental niche in a a subtenuis elemental and isotopic compositions spread more widely suggesting that this species occupied a greater range of habitats possible sexual dimorphism in a o vulgaris is reflected in bimodal mg ca and differing intra rostral distribution of mg in putative dimorphs concentrations decline by 30 from apical line to rim in specimens with high mg ca but are largely invariant radially in specimens with lower mg ca sexual dimorphism in a a subtenuis yields a bimodality in size mg ca and intra rostral distribution of mg larger specimens have a higher mg ca and mg concentrations that increase along radial traverses from apical line to rim whilst the smaller specimens show a mid rostral minimum in mg concentration radial profiles of concentrations for sr and na vary little in all forms toarcian belemnites of these species thus show strong biofractionation effects on mg ca and little or no observable biofractionation of sr ca or na ca it follows that much of the noise in belemnite records results from biofractionation and from a cosmopolitan life style of some belemnite species rather than climate change for toarcian belemnites we suggest that sr ca is the best indicator of palaeo temperature

phase shifts in shear stress as an explanation for the maintenance of pool riffle sequences the stability of the pool rif e sequence is one of the most fundamental features of alluvial streams for several decades the process of velocity or shear stress reversal has been proposed as an explanation for an increase in the amplitude of pool rif e sequence bars during high ows offsetting gradual scour of rif es and deposition in pools during low ows despite several attempts reversal has rarely been recorded in eld measurements we propose that instead of being reversed maxima and minima in shear stress are phase shifted with respect to the pool rif e sequence bedform pro le so that maximum shear stress occurs upstream of rif e crests at high ow and downstream at low ow such phase shifts produce gradients of shear stress that explain rif e deposition and pool scour at high ow in accord with sediment continuity the proposal is supported by results of a one dimensional hydraulic model applied to the surveyed bathymetry of a pool rif e sequence in a straight reach of a gravel bed river in the sequence studied the upstream phase shift in shear stress at high ow was associated with variations in channel width with width minima occurring upstream of rif e crests approximately coincident with shear stress maxima and width maxima occurring downstream of rif e crests assuming that the width variation is itself the result of ow de ection by rif e crests at low ow and associated bank toe scour downstream low and high ow can be seen to have complementary roles in maintaining alluvial pool rif e sequences copyright 2004 john wiley sons ltd

strontium isotope stratigraphy and oxygen and carbon isotope variation during the middle jurassic early cretaceous of the falkland plateau south atlantic abstract 87sr 86sr data of belemnites are presented from a middle jurassic early cretaceous succession from the falkland plateau deep sea drilling project sites 511 and 330 that was deposited in a periodically anoxic semi enclosed shallow water basin diagenetically screened strontium isotope values of 0 706789 rise to 0 707044 before increasing sharply to 0 707428 in the uppermost part of the sampled succession comparison with published strontium calibration curves suggests that the oldest samples were callovian to oxfordian in age whilst the remainder of the jurassic part of the succession consisted of kimmeridgian and early tithonian age sediments the nannofossil dinoflagellate and molluscan assemblages provide comparable age determinations the strontium isotope analysis of the youngest belemnites points to a hauterivian barremian age whilst age interpretations based upon the fauna provide a wide age range from the barremian to early albian strontium isotope stratigraphy of this succession hence offers increased age resolution providing data regarding the timing of episodes of bottom water anoxia which have been recorded throughout the south atlantic basin well preserved belemnite specimens display an oxygen isotope range between 0 08 and 2 22 pdb peedee belemnite international standard and a carbon isotope range from 2 35 to 1 33 pdb 13c values become increasingly negative through the late jurassic early cretaceous and in concert with the 87sr 86sr data reveal a trend that could be accounted for by increasing levels of weathering and erosion the oxygen isotope data if interpreted in terms of palaeotemperature are consistent with warm palaeotemperatures in the kimmeridgian and slightly cooler temperatures for the tithonian and early cretaceous parts of the succession the proposed relative kimmeridgian warmth based upon strontium isotope age assignments is thus in good agreement with other published palaeotemperature records

paleoceanographic changes during the early cretaceous valanginian hauterivian evidence from oxygen and carbon stable isotopes we investigated valanginian hauterivian bulk rock and belemnite samples from vocontian basin sections in southeastern france for their stable carbon and oxygen isotope signature firstly because these sections permit calibration with high resolution biostratigraphy based on ammonites and secondly because detailed isotope studies for the hauterivian are lacking the results show that 13c values for bulk rock decrease during the late valanginian early hauterivian with 1 and increase again during the late hauterivian with 1 the 18o signal for bulk rock samples is mostly disturbed by diagenesis the belemnites show carbon and oxygen isotope values that are lower and higher than bulk rock samples respectively we explain this as the result of the belemnites recording a deeper water signal with lighter 13c values and heavier 18o values implicating colder water at greater depth the overall preservation of the belemnites is very good and permits the construction of a paleo temperature trend this trend shows warm deeper water temperatures during the late early valanginian 15 c and progressively cooler temperatures during the late valanginian and early hauterivian 11 c during the late hauterivian temperatures increase again 13 c we relate this cooling trend for deeper water to a second order sea level rise which allowed for the exchange of cold boreal and warm tethyan water masses the influx of cold nutrient rich water had a profound effect on carbonate producing biota along the northern margin of the tethys during the hauterivian leading to prolonged phases of condensation and platform destruction during the early hauterivian the carbonate system along the northern tethyan margin shifted into a green water mode of carbonate production high rates of carbonate production under mesotrophic conditions also observed in other parts of the world meant that the global carbon cycle became buffered shown by the stable trends in carbon isotopes

elemental and oxygen isotope composition of early jurassic belemnites salinity vs temperature signals well preserved calcitic belemnite samples from the basque cantabrian basin of northern spain have been analyzed to improve our current understanding of the chemistry of seawater as an index of paleoceanographic changes during the early jurassic a period punctuated by times of oceanic anoxia and global mass extinctions because the oxygen isotope composition of calcite depends not only on temperature but also on salinity we present here a combination of sr ca mg ca and 18o analyses that helped us to evaluate both effects separately comparison between the temporal records and cross plots of these geochemical parameters shows a good correlation of mg ca with 18o and a weak correlation of sr ca with 18o comparison of our belemnite 18o record with coeval o isotope profiles from other paleogeographic domains suggests the existence despite differences in the absolute isotopic values of a major negative shift during the serpentinus zone that is regionally reproducible this event is linked to the early toarcian ocean anoxic event oae and suggests the existence of global changes in paleoclimatic and paleoceanographic conditions that are reflected largely in the geochemical composition of seawater compared to our results however other early toarcian 18o data reported from northern european basins are generally depleted 1 3 1 6 in contrast mg ca ratios display similar values these differences in 18o data suggest a salinity component for the northern european data and provide evidence for a north to south salinity gradient within the north european interior boreal seaway during the early jurassic this study suggests that the secular variation of mg ca is a useful proxy for discriminating between temperature and salinity effects on the oxygen isotope composition of fossil shells and highlights the prospect of using the mg ca ratios of belemnite calcite to calculate paleotemperatures independently of salinity the findings of our study may help to calibrate 18o curves in other basins by removing the salinity component of their 18o records which may help to calculate water density gradients between the jurassic seas of northern and southern europe

mid infrared spectroscopy of impactites from the nordlinger ries impact crater abstract this study is part of an effort to build a mid infrared database 7 14 m of spectra for mertis mercury radiometer and thermal infrared spectrometer an instrument onboard of the esa jaxa bepicolombo space probe to be launched to mercury in 2017 mercury was exposed to abundant impacts throughout its history this study of terrestrial impactites can provide estimates of the effects of shock metamorphism on the mid infrared spectral properties of planetary materials in this study we focus on the nordlinger ries crater in southern germany a well preserved and easily accessible impact crater with abundant suevite impactites suevite and melt glass bulk samples from otting and aumuhle as well as red suevite from polsingen were characterized and their reflectance spectra in mid infrared range obtained in addition in situ mid infrared spectra were made from glasses and matrix areas in thin sections the results show similar but distinguishable spectra for both bulk suevite and melt glass samples as well as in situ measurements impact melt glass from aumuhle and otting have spectra dominated by a reststrahlen band at 9 3 9 6 m bulk melt rock from polsingen and bulk suevite and fine grained matrix have their strongest band between 9 4 and 9 6 m there are also features between 8 5 and 9 m and 12 5 12 8 m associated with crystalline phases there is evidence of weathering products in the fine grained matrix such as smectites mercury endured many impacts with impactors of all sizes over its history so spectral characteristics observed for impactites formed only in a single impact like in the ries impact event can be expected to be very common on planetary bodies exposed to many more impacts in their past we conclude that in mid infrared remote sensing data the surface of mercury can be expected to be dominated by features of amorphous materials

geochemical evidence for sediment provenance in mudstones and fossil poor wackestones upper jurassic majorca island terra nova 24 437 445 2012 abstract the notion that diagenetic imprint on ancient carbonates significantly compromises palaeoenvironmental interpretations is revealed as an oversimplification the enigmatic case at the core of this research is an extended homogeneous macrofossil poor deposit showing distinctive dark brown colour and very fine grain size aumedra fm majorca island this markedly contrasts with standard ammonitico rosso ar facies known from jurassic epioceanic swells geochemical analysis of matrix micrite carbonate cements and belemnite rostra are used to interpret the aumedra carbonates stable carbon and oxygen isotopes and elemental abundance are compared with data from under and overlying deposits and coeval sections conspicuously higher than expected c and o isotope signature together with strontium enrichment and a typically low iron and manganese concentrations favour a distant shallower probably aragonitic sedimentary supply modern and ancient examples of carbonate deposition are integrated with possible hydrodynamic conditions justifying transport over the studied area a potential ne source is envisaged terra nova 00 1 9 2012

estimating critical stream power for bedload transport calculations in gravel bed rivers the physical basis of bagnold s equation for critical stream power is examined although the general approach is well founded the original equation can be criticised for 1 failing to distinguish between the grain size in transport and the grain size that represents bed roughness 2 requiring a knowledge of critical flow depth in addition to gross channel properties 3 failing to allow for hiding and protrusion effects on the mobility of mixed size stream beds more general equations are presented which overcome these limitations they require a knowledge of channel slope but not depth the analysis suggests that the presence of form resistance in addition to grain roughness does not affect the calculation of critical power critical power is expected to depend more sensitively on grain size between reaches than within reaches

dimensionless morphological ratios versus stream power variations at bankfull stage in an ephemeral channel abstract dimensionless morphological ratios dmr generally are used in systemic proposals for stream classification and river restoration projects often such morphometric parameters including field data from channel cross sections develop into a template for a given geomorphic reference site in this study high resolution digital terrain models hrdtms combined with orthophotographs from 2018 and ground based surveys were used to analyze the spatial variability of dmr in a semi arid ephemeral stream subject to changes in stream power under bankfull conditions in particular a channel reach of 2 7 km in length along the upper mula stream in southeastern spain was chosen to test the relationships between the two types of variables rosgen s dmr width to depth ratio entrenchment ratio bank height ratio and hydraulic data at bankfull stage flow velocity froude number shear stress mean stream power and energy gradient among others were calculated by 1d hydrodynamic modeling and hrdtms prior entry of field information the resulting maps allowed comparison of stream power with dmr in relation to the channel stretch class and bed stability the results showed similar spatial patterns for the width to depth ratio and the bank height ratio the average values estimated in bend stretches were lower than along straight and slightly sinuous stretches and very similar to those of sub reaches from the inflection point to the meander bend apex however the entrenchment ratio followed a different pattern according to which the straight and slightly sinuous stretches were the most entrenched and the bend stretches presented a more moderate average entrenchment ratio in addition the energy balance and power gradient also experienced spatial variations in relation to the bed stability and dmr only in highly incised sub reaches were such relationships not significant the lack of a significant correlation between excess energy and bank height ratio or width to depth ratio over short lag distances was also verified regardless of the affected bedforms an anova showed important differences between the straight and slightly sinuous stretches and bend stretches which were strongly influenced by the incision and entrenchment ratios and the maximum bankfull depth

paleotemperature variations of early jurassic seawater recorded in geochemical trends of belemnites from the basque cantabrian basin northern spain abstract here we present new o isotope mg ca and sr ca data of early jurassic belemnites from the basque cantabrian basin of northern spain a succession deposited in a periodically anoxic restricted hemipelagic basin nearly 200 pliensbachian lower toarcian belemnites were collected and examined using optical cathodoluminescence and chemical techniques to constrain the effects of potential diagenetic alteration after a precise diagenetic screening of samples 176 belemnites were selected to provide records of changes in seawater geochemistry and temperature the records show a fairly good correlation of 18o with mg ca ratios r 0 65 and a weak correlation of 18o with sr ca ratios r 0 34 the oxygen isotope data if interpreted in terms of paleotemperature have revealed a period of relatively uniform and warm seawater temperatures during the early pliensbachian followed by a sharp temperature drop during the late pliensbachian earliest toarcian the onset of this cooler period occurred within the protogrammoceras celebratum subzone and the coolest seawater temperatures were reached at the end pliensbachian pleuroceras spinatum zone this was followed by a rapid seawater warming during the harpoceras serpentinus zone of the early toarcian in addition the data set provides new information regarding paleoceanographic conditions for anoxic events in a critical region of connection between the boreal and tethys realms it is the background to relatively high 18o values that prevailed during the anoxic episodes concerning the impact of the early toarcian anoxic event in northern spain the detected 18o and mg ca excursions reached their minimum and maximum respectively during the lower h serpentinus zone while the anoxic black shale interval developed earlier during the upper dactylioceras tenuicostatum lowermost h serpentinus zones