styles of failure in late holocene highstand prodelta wedges on the adriatic shelf on the continental shelves of the northern mediterranean basin the late holocene highstand systems tract hst prograded un der the influence of major rivers after the attainment of the present sea level highstand about 5 5 cal kyr bp on the adriatic shelf the thickness distribution of the late holocene hst reflects the location of major deltas on the western side of the basin and the geostrophic cir culation which prevents a more uniform sediment dispersal toward the center of the basin very high sediment accumulation rates 1 to 10 cm year resulted in the construction of a hst depocenter up to 35 m thick this shore parallel depocenter is affected by failure of limited displacement over as much as 40 of its extent gas impregnation is common in the topset region and occurs at very shallow levels a few meters below the sea floor five areas are characterized by a variety of sea floor and subsurface crenulations although locally some of these crenulations have an intriguingly regular geometry sediment failure is the most plausible mechanism for their formation sediment failure better explains the large variety of geometries that characterizes the coastal mud prism of the late holocene hst furthermore we observe that these crenulations occur only where the downlap surface at the base of the hst is disrupted and affected by geometries that are con sistent with fluid escape processes this relationship suggests that the basal surface acts as a weak layer for sediment failure failure occurred in variable water depths from the northern slope of the modern po prodelta 10 20 m water depth to the narrow shelf offshore bari 40 110 m water depth in all these areas the proximal part of the hst prodelta wedge is intensely gas charged the thickness and age of the sediment sections affected by failure are slightly differ ent from place to place but appear everywhere younger than 5 5 cal kyr bp where failure affects the entire hst the detachment occurs on the downlap surface at its base failure geometries characterize the head region whereas compressional features such as pressure ridges and mud diapirs dominate in the toe region ranging in depth between 70 and 110 m where failure is limited to the upper few meters of the hst there is a clear lithologic change decrease in carbonate fraction and grain size across the basal surface this lithological change reflects a switch in sediment supply from local apennine rivers below to po derived mud this change occurred at the onset of the little ice age documenting the indirect control of short term climate change and hu man impact on sediment architecture the deformations affecting the late holocene hst in the various areas show differences in internal geometry but appear everywhere to be characterized by limited downward displacement and can be attri buted to shear dominated retrogressive failure it is suggested that some degree of consolidation occurred immediately after mobilization possibly induced by the escape of fluids nowhere has failure evolved into disintegration and flow likely because the type of cyclic loading that triggered it was not prolonged over a long enough interval short lived radionuclides in the uppermost stratigraphic layers which postdate the failure in the area offshore ortona allowed us to quantify systematic changes in sediment accumulation rates as a func tion of the underlying deformed sea floor in areas of wavy sea floor troughs show sediment accumulation rates of greater than 16 mm yr a figure that is fourfold the rate measured on the flanks of the troughs

three dimensional quantitative modeling of clinoform development abstract clinoform geometry pervades stratigraphic sequences across a variety of scales it is a composite surface which records the complex interplay between accommodation sediment supply physiography and hydrodynamics much of the sequence stratigraphic technique employs clinoform geometry to discriminate between the various systems tracts that constitute depositional sequences however many sequence stratigraphic models treat the generation of accommodation and the input of sediment supply as a two dimensional problem by assuming a line source of sediment entering a system impacted by relative sea level fluctuations one common attribute of clinoforms regardless of size and or shape is that their formation is inherently three dimensional therefore the clinoform geometry varies spatially and temporally throughout a region depending on the proximity to the sediment source and the character of the hydrodynamic regime we present a three dimensional stratigraphic model that combines both diffusion and advection to simulate across and along margin sediment transport and deposition this model allows us to examine how the morphology and internal clinoform geometry of deltas vary away from the sediment source in this application we simulate the development of a delta in a low energy environment to understand the importance of along shelf diffusion on clinoform geometry and the morphology of the delta we predict the three dimensional geometry and how it varies throughout a relative sea level cycle our model indicates that when the clinoform rollover is spatially coincident with the shoreline position the clinoform geometry changes dramatically along strike away from the sediment source region throughout a relative sea level cycle for example oblique clinoforms develop near the source region and evolve into an onlapping sequence along strike on the basis of stratal geometry and the technique of sequence stratigraphy this deposit would be interpreted as two different sequences with very different connotations for their formation we surmise that when the clinoform rollover and the shoreline position are separated e g a subaqueous delta the along strike variability of the clinoform geometry diminishes because of the hydrodynamic forces operative across the shelf consequently it is important to determine how clinoforms develop in three dimensions and to ensure that our window of observation is sufficient to discern between local and regional variability

clinoforms and clinoform systems review and dynamic classification scheme for shorelines subaqueous deltas shelf edges and continental margins abstract clinoforms are inclined and normally basinward dipping horizons developed over a range of spatial and temporal scales in both siliciclastic and carbonatic systems the study of clinoform successions underpins sequence stratigraphy and all efforts to reconstruct the relative partitioning of reservoir seal and source rocks along shoreline to basin floor profiles here we review clinoform research and propose a more systematic description and classification of clinoforms this is a crucial step to improve predictions of facies and lithology distribution within shoreline to continental shelf and abyssal plain successions together with the genesis drivers and dynamics of their constituent sedimentary units four basic clinoform types are here distinguished in delta shorelines lacustrine and marine environments on the basis of their overall spatial and temporal scale morphology outbuilding dynamic and geodynamic and depositional setting 1 2 delta scale clinoforms which in turns are sub divided into shoreline and delta scale subaqueous clinoforms 3 shelf edge clinoforms and 4 continental margin clinoforms delta scale clinoform sets are tens of metres high and typically represent 1 103 kyr with progradation rates ranging from 1 000 100 000 m kyr for shorelines and subaerial deltas to 100 20 000 m kyr for subaqueous deltas shelf edge clinoform sets are hundreds of metres high and are nucleated and accreted in 0 1 20 myr usual progradation rates of 1 100 m kyr by successive cross shelf transits of delta scale clinoforms continental margin clinoform sets are thousands of metres high hallmark key geodynamic crustal boundaries e g continent ocean transition and slowly prograde basinwards in ca 5 100 myr with typical rates of 0 1 10 m kyr as a consequence of the very different progradation rates and of the difficulty of large scale clinothems to backstep during transgressions shorelines are the most dynamic clinoforms with regards to position continental margins the least and shelf edges are intermediate shortly after a transgression therefore the four clinoform types may prograde synchronously along shoreline to abyssal plain transects forming compound clinoform systems during the subsequent regressive cycle however due to the dissimilarity in progradation rates different clinoform types will normally merge progressively with each other giving rise to hybrid clinoforms e g shelf edge deltas and fewer depositional breaks in slope are distinguished along a single shoreline to abyssal plain transect overall all clinoform systems are the result of the dynamic evolution of compound and hybrid clinoforms along a temporal and spatial continuum regulated by the cyclical backstepping of the smaller scale system within natural progradational retrogradational cycles of larger scale clinothem outbuilding all clinothem types may show either an accretionary active or draping passive style depending on the proximity to the sediment source draping clinothems are nearly always composed of condensed fine grained sediments while actively accreting clinothems can be composed of predominantly coarse grained i e reservoir forming or predominantly fine grained i e non reservoir lithotypes a novel hierarchical classification scheme for both recent and ancient clinoforms is here proposed consisting of 12 classes the four basic clinoform types delta scale shoreline delta scale subaqueous shelf edge and continental margin are sub divided into eight accretionary active and draping passive sub types 8 division each accretionary sub type is then sub divided into a sandstone prone and mudstone prone variant 12 division which can be at least tentatively predicted on the basis of the clinoform morphology even in the absence of direct stratigraphic logs

the effect of wind stress over the eastern mediterranean on deep water formation in the adriatic sea abstract we investigate the effect of interannual variability of the wind stress over the eastern mediterranean on adriatic deep water adw formation using an oceanic general circulation model of the mediterranean sea driven by monthly era interim wind stress of the years 1979 2014 this is done by using climatological annual cycle of the surface temperature and freshwater flux but interannually varying wind stress a connection between the wind stress magnitude over the rhodes gyre region and adw outflow is found in association with the formation of levantine intermediate water liw 720 years artificially generated wind stress fields were constructed based on the first 50 empirical orthogonal functions eofs of the wind stress monthly anomalies this simulation strengthen the connection that was found and also reveal a centennial internal variability of both the liw and the adw outflow it is also found that the intensity of the rhodes gyre is almost linearly related to the wind stress amplitude however the adw outflow is non monotonically related to the wind stress amplitude there is an optimal wind stress amplitude for which the adw formation is maximal when the wind stress amplitude is more than 50 the climatological mean wind stress amplitude the adw outflow is weakened this implies a different balance between the saline liw and the fresh atlantic water entering the eastern mediterranean from sicily strait under stronger than present wind stress amplitude

subaqueous delta of the ganges brahmaputra river system abstract the ganges brahmaputra is among the world s three largest river systems in terms of sediment load but until now no high resolution seismic data have been obtained to document the nature of the sediment deposit seaward of the rivers mouths the other two amazon huanghe discharge into energetic coastal environments and form subaqueous deltas with characteristic clinoform stratigraphy high resolution seismic reflection profiles of the bengal shelf reveal similar stratigraphy topset beds dip gently 0 036 and diverge offshore more steeply dipping foreset beds 0 190 converge farther seaward and relatively thin gently dipping bottomset beds 0 022 extend across the outer shelf overlying an erosional surface presumed to be of late pleistocene age sediment accumulation rates are highest in the foreset region 5 cm year and reduced in the bottomset region

methane derived authigenic carbonates mdac in northern central adriatic sea relationships between reservoir and methane seepages abstract in the adriatic basin gas venting characterized by pockmarks gas bubbling and other fluid escape related features is diffused and has been linked or to shallow gases trapped in the late pleistocene and below the holocene maximum flooding surface or to leakage from more deeply buried pliocene to pleistocene foredeep succession some seepages are associated with carbonate crusts but a possible correlation between methane leakage and carbonate precipitation in this basin never reached a clear definition carbonate concretions recovered by different areas of the adriatic sea northern central and southern at different depths from ca 30 to ca 300 m have been analysed different fabrics petrography and mineralogy can be evidenced for the different sets of samples all of them show a carbonate content mainly represented by high mg calcite up to 66 in weight of total carbonates for the samples from central adriatic close to bonaccia gas field offshore ancona and 79 to 96 of the total carbonate weight for the other samples that are mainly biogenic these differences are also reflected by the 13 c values ranging between 19 and 29 vpdb for the samples collected in the bonaccia area and moderately positive values for all the other samples bonaccia samples contain carbonate cements that record the contribution of methane derived carbon and have been interpreted as formed below the sea floor in correspondence of the sulphate methane transition zone carbonates recovered from the southern and northern adriatic basin do not show clear evidence of methane derived carbon and are mainly made up by organisms typically recovered in the adriatic coralligenous assemblage nonetheless micro morphological evidences suggest influence of bacterial sulphate reduction and methanogenesis in precipitation of some of these carbonates

the submarine delta of the ganges brahmaputra cyclone dominated sedimentation patterns the ganges brahmaputra belongs to the world s largest rivers in terms of sediment discharge but little is known yet about the processes controlling sediment distribution on the shelf and the documentation of these processes in large and small scale sedimentary structures for this study the submarine delta of the river system was investigated by high resolution seismic reflection profiles and piston and gravity coring logged physical properties of the cores were combined with visual core description grain size analysis and radiography sedimentation rates were estimated by 210pb and 137cs gamma spectrometry and cross checked with evaluation of seismic profiles the data reveal that the broad delta topset 20 m waterdepth is formed by a thick layer of sand silt highest sedimentation rates about 10 cm a 1 occur at the centre of clinoform delta foreset beds where about 20 of the total riverine sediment load is deposited and thus cause an annual progradation of the subaqueous delta front by about 15 m the foreset beds consist of graded sand silt layers which are thought to be deposited by sediment laden flows generated during the surge of tropical cyclones tempestites interbedded with silty clay layers the head of a canyon the swatch of no ground that deeply incises into the shelf forms a sediment trap along the westward cyclonic transport path where sedimentation rate increases to about 50 cm a 1 episodically earthquakes or storms destabilize especially the rapidly accumulated foreset beds in the eastern delta creating up to 8 m thick mass flows on the outer shelf in water depth beyond 80 m no holocene sediment is deposited

the late holocene gargano subaqueous delta adriatic shelf sediment pathways and supply fluctuations the gargano subaqueous delta formed on the eastern and southeastern sides of the gargano promontory in the western adriatic this subaqueous deposit represents the southernmost portion of the late holocene highstand systems tract hst growing along the western side of the adriatic as an extensive wedge of deltaic and shallow marine mud the late holocene hst rests above a regional downlap surface that marks the time of maximum landward shift of the shoreline attained around 5 5 cal kyr bp at the end of the late pleistocene holocene sea level rise high resolution seismic stratigraphic and tephra correlation indicate the presence of a thin basal unit recording condensed deposition between 5 5 and 3 7 cal kyr bp over much of the basin above this unit sediment accumulation rates increased to high values as much as 1 5 cm yr 1 reflecting the stabilisation of relative sea level and the forcing from high frequency climatic or anthropogenic changes affecting river dynamics the late holocene mud wedge of which the gargano subaqueous delta is a significant component reaches up to 35 m in thickness and has a volume of ca 180 km3 the shore parallel thickness distribution of the mud wedge reflects the dominant oceanographic regime of the basin and the asymmetric location of the mostly western sediment sources with a combined modern delivery of 51 7 106 t yr 1 of mean suspended load in sections perpendicular to the coast the late holocene mud wedge appears composed of forestepping clinoforms with gently dipping foresets typically 0 5 the gargano subaqueous delta is characterised by a submarine topset in water depths shallower than 25 28 m and accounts for about 1 7th of the total volume of the late holocene mud wedge despite the absence of direct river supply to the gargano area in the area of maximum interaction between shore parallel currents and basin morphology progradation occurs onto a flat and barren bedrock outcrop in about 50 80 m water depth the rapid transition from a thickness of 30 m of late holocene mud to nil is a good indication of the role of southward flowing bottom hugging shelf currents in causing the redistribution of sediment along the adriatic inner shelf additional evidence of this regime comes from 1 the most recent sigmoid defined at seismic stratigraphic scale deposited since the onset of the little ice age showing a shore parallel thickness distribution and a main depocentre to the southeast of the gargano promontory 2 the maximum values of sediment accumulation rates over the last century documented by 210pb measurements defining a narrow shore parallel belt immediately seaward of the depocentre of the most recent sigmoid the gargano subaqueous delta grows from the outbuilding of progressively younger progradational sigmoids that tend to parallel the previous ones the gargano subaqueous delta differs from other documented late holocene subaqueous deltas because its growth reflects 1 sediment transport dominated by bottom currents sub parallel to the strike of the composing clinoforms 2 a complex supply regime including the po delta 350 km to the north and several coalescing apennine rivers acting as line source 3 several alternating intervals of enhanced outbuilding and condensed deposition and 4 an in phase growth of the most recent sigmoid with the major progradation of the po delta during the little ice age

shore platform downwearing in eastern canada the mega tidal bay of fundy abstract laboratory and field work was conducted to determine rates of surface downwearing on shore platforms at two sites in the bay of fundy canada these data are needed to assess and model the effect of downwearing mechanisms on platform evolution sandstone and basalt samples 900 were exposed to semidiurnal tidal cycles over 3 years using de ionized water or artificial sea water they were immersed for 1 6 or 11 h over each 12 h tidal cycle representing the lowest high lht mid and highest low hlt tidal levels respectively a further 600 samples were immersed in de ionized water or artificial sea water for 90 min every 1 2 or 3 weeks representing increasingly higher elevations above the lht level or exposed for 90 min every 1 2 or 3 weeks representing increasingly lower elevations below the hlt level these experiments ran for 12 months in the field surface downwearing was measured at 108 transverse micro erosion meter tmem stations over 2 to 6 year periods in the laboratory mean downwearing rates between the lht and hlt levels were 0 61 1 80 mm yr 1 in sandstones and 0 01 0 18 mm yr 1 in basalts rates were highest at the lht level rates decreased with elevation above the lht level and were uniformly low below the hlt level salt weathering was dominant above the lht level salt weathering and wetting and drying were important in sandstones between the lht and hlt levels but salts inhibited rock breakdown in basalts in the field the mean downwearing rate was 1 254 mm yr 1 in sandstones which was similar to the experimental data and 0 722 mm yr 1 in basalts which was much higher than in the experiments with artificial sea water but similar to the experiments with de ionized water there was no relationship in the field between downwearing rate and rock hardness or tmem station elevation

mapping turbidity patterns in the po river prodelta using multi temporal landsat 8 imagery abstract thirty meters resolution turbidity maps derived from landsat 8 l8 images were used to investigate spatial and temporal variations of suspended matter patterns and distribution in the area of po river prodelta italy in the period from april 2013 to october 2015 the main focus of the work was the study of small and sub mesoscale structures linking them to the main forcings that control the fate of suspended sediments in the northern adriatic sea a number of hydrologic and meteorological events of different extent and duration was captured by l8 data quantifying how river discharge and meteo marine conditions modulate the distribution of turbidity on and off shore at sub mesoscale peculiar patterns and smaller structures as multiple plumes and sand bars were identified thanks to the unprecedented spatial and radiometric resolution of l8 sensor the use of these satellite derived products provides interesting information particularly on turbidity distribution among the different delta distributaries in specific fluvial regimes that fills the knowledge gap of traditional studies based only on in situ data a novel approach using satellite data within model implementation is then suggested

weathering by wetting and drying some experimental results a series of experiments on sandstone and dolerite was undertaken in an attempt to better understand the wetting and drying weathering process as rock samples are frequently subjected to wet dry cycles within the simulation of other weathering mechanisms e g freeze thaw three common methods of moisture application were used and the influences of these evaluated it was found that the method of moisture application could affect the nature of the weathering products resulting from wetting and drying it was also observed that there were changes in the internal properties of the rock e g porosity microporosity and that these could influence the synergistic operation of other weathering processes although not all of the observations could be explained it is apparent that wetting and drying has both a direct and an indirect effect on the weathering of rock that has not been taken into account in simulations greater cognizance needs to be given to the role of this process both in the field and in laboratory simulations

human impact in the holocene fluvial and coastal evolution of the marche region central italy abstract today the coasts of the marche region are represented by almost continuous rectilinea sand beaches except in the north at the border with the romagna region and in the central part around the conero ridge where there are active rock cliffs the sandy coasts are protected almost everywhere by artificial barriers built up as a protection against the general tendency to retreat along some tracts the coastal erosion started at the beginning of this century but became generalized after 1940 1950 this was mainly due first to the reduction in sediment supply following the improvement in agricultural techniques after the italian unification and later to the widespread extraction of gravels from the thalwegs related to the rapid increase in urban population in the 1950s however in the same period along the rivers there was a widespread creation of artificial levees to prevent lateral erosion or flooding and to extend areas suitable for agriculture following these practices the lower middle tracts of the rivers underwent a strong vertical downcutting which increased as a result of the creation of checkdams downvalley of many bridges which contributed to the store of the sediments in the upper part of the valleys at present most of the rivers have an irregular course and are deeply entrenched in the bedrock or inside their own sediments up to the beginning of the century most of the lower tracts of the valleys were characterized by strong aggradation in a braidplain system this aggradation started as early as the middle ages 1100 ad but increased after the renaissance as a consequence of a generalized deforestation of the periadriatic basin and the following severe soil erosion in the mean time the coast underwent a very fast progradation in some places more than 500 m small deltas were created at the mouths of the rivers and longshore bars and sandy beaches began to occupy the base of the active cliffs which previously extended between one river and another however in the mountain parts of the river basins a meander course existed and in many cases still exists expecially where the human interventions were of limited extent before 1000 1100 ad all the rivers had a meander pattern and at the junction with the sea entered lagoons and swamps in most cases protected by littoral barrier beaches these conditions were established earlier than the third century bc and have been attributed to the first systematic land clearance and the following soil erosion during the bronze and iron ages at that time the regional coastline became almost rectilinear but with many active cliffs between one river and another before being affected by a major human impact earlier than 4000 years bp the natural coastal environment was represented by active rock cliffs which alternated with pocket beaches corresponding to a river mouth in some rivers embayments and beaches were located up to 4 5 km inland from the present day position after the flandrian transgression the evidence presented reveals major changes that can be attributed to human impact

shore platform downwearing in eastern canada a 9 14 year micro erosion meter record abstract downwearing rates erosion in the vertical plane were measured with a micro erosion meter mem in eastern canada on an argillacious sub horizontal shore platform at mont louis in eastern quebec and on two sloping basaltic and sandstone platforms at respectively scots bay and burntcoat head in the bay of fundy nova scotia the original data covered a period from 2002 to 2009 this dataset was extended by measurements repeated at surviving mem stations in 2017 producing records ranging over 9 14 years depending on when each station was installed because of rapid surface downwearing many of the original mem stations were inoperable in 2017 especially at burntcoat head nevertheless data were obtained from 19 stations at burntcoat 35 of the 2009 original 25 at mont louis 83 of the original and 38 at scots bay 75 of the original for the stations at mont louis and scots bay that were still functioning in 2017 there were no significant differences in rates of downwearing over the shorter from station installation up to 2009 and extended periods from installation to 2017 mean rates of downwearing calculated from all the stations in each area declined through time however due to the loss of the more rapidly eroding stations a simple procedure which was proposed to compensate for this decrease produced mean downwearing rates that were broadly similar to those reported over the original measurement period there were significant relationships between downwearing rates and elevation r2 0 32 and downwearing rates and rock hardness r2 0 41 in the extended record at scots bay and a small but significant relationship between downwearing rates and rock hardness at mont louis r2 0 17 differences in downwearing rates across the platforms suggest that salt weathering and wetting and drying are dominant weathering mechanisms at scots bay and mont louis chemical weathering of the sandstone cementing agent and the premature removal of weathered grains by wave generated bottom currents may however be more important at burntcoat head

world wide delivery of river sediment to the oceans new data and new estimates from old data show that rivers with large sediment loads annual discharges greater than about 15 times 10 6 tons contribute about 7 times 10 9 tons of suspended sediment to the ocean yearly extrapolating available data for all drainage basins the total suspended sediment delivered by all rivers to the oceans is about 13 5 times 10 9 tons annually bedload and flood discharges may account for an additional 1 2 times 10 9 tons about 70 of this total is derived from southern asia and the larger islands in the pacific and indian oceans where sediment yields are much greater than for other drainage basins

micro erosion meter measurements of rock wear on the otway coast of southeast australia abstract the use of the micro erosion meter mem has been refined by providing 1 a base plate on which to check the relationship of legs and probe and 2 a micrometer level to check the relationships of the three studs countersunk in the rock at each site along 50 km of the otway coast lines of mem stations were installed across shore platforms normal to the shore and surveyed to mean low water readings were made bimonthly from 1978 to 1980 average site downwear ranged from 0 02 to 1 8 mm yr 1 according to rock type and the amount of exposure to the almost continuous swell waves the results of this study combined with other information available are used to discuss the origin and evolution of otway coastal morphologies

geochemistry and deposition of 7be in river estuarine and coastal waters the atmospheric flux of cosmogenic 7be 53 3 day half life and the mode of 7be deposition in river estuarine and coastal environments have been examined the atmospheric flux of 7be commonly supports inventories ranging from 1 0 to 2 0 pci cm2 1 pci 0 037 bq beryllium 7 concentrations in water phase samples collected across salinity gradients in several estuaries along the eastern coastline of the united states range from 0 03 to 0 53 pci l and primarily reflect variations in 7be supply and sorption kinetics the major process controlling the concentration of 7be on estuarine suspended particles appears to be the length of time that these particles remain in the water column field particle to water distribution coefficients for 7be have a median value of about 4 104 but range over an order of magnitude reflecting short term variations in 7be input particle dynamics and particulate iron content rather than equilibrium sorption desorption responses to changes in water salinity or particle type residence times of 7be in the water column range from a few days in estuarine areas of rapid fine particle deposition to several weeks in high energy environments where pronounced sediment resuspension reintroduces deposited 7be back into the water column inventories of 7be in sediments range from nondetectable to 3 3 pci cm2 with the highest inventories in areas where fine particles are accumulating rapidly such sites are also major repositories for other particle reactive substances a 7be budget for the james estuary indicates that less than 5 of the expected 7be input is in the water column and that the short term estuarine trapping efficiency for atmospherically derived 7be is somewhere between 50 and 100

development of shore platforms on kaikoura peninsula south island new zealand ii the role of subaerial weathering the role of subaerial weathering in the development of shore platforms on kaikoura peninsula is investigated evidence for weathering came from a number of distinctive surface morphologies on platforms salt crystal growth water layer weathering and slaking schmidt hammer test data showed that weathering had occurred and that rock strength was reduced through weathering by as much as 50 weathering processes on shore platforms rely on repeated wetting and drying and for this reason the number of wetting and drying cycles was estimated it was found that the number of wetting and drying cycles depend not only on the pattern of tidal water levels but also on algae growth and desiccation the number of cycles ranged from 104 to 379 per year at elevations low in the tide range fewer cycles occurred the greatest number occurring between the peaks of spring and neap tides and where rainfall adds to the number the zone of most cycles was estimated to occur between 0 6 and 0 9 m above mean sea level on the more landward margins of platforms it is at these elevations that the highest rates of erosion occur based on these results it is argued that the development of shore platforms at kaikoura results from subaerial weathering caused by repeated wetting and drying this is contrary to the view that shore platforms result from marine erosion

long term shore platform surface lowering rates revisiting gill and lang after 32 years abstract in 1978 e d gill and j g lang installed 53 micro erosion meter mem sites on shore platforms along the otway coast in south eastern australia surface lowering rates were originally determined from 2 yr of measurements 1979 and 1980 and showed that the mean annual rate of lowering from all sites was 0 37 mm yr 1 we re measured these mem sites 32 yr after the first set of readings were taken in february 1979 we relocated 49 of the original 53 bolt sites and were able to measure 45 of them from the sites we measured the mean annual rate of shore platform lowering was 0 31 mm yr 1 rates of surface lowering on shore platforms are commonly reported from studies of only two or three years and only one other record exceeds 30 yr kaikoura peninsula nz 1 09 mm yr 1 in that case fewer than half of the original bolt sites were functioning because erosion had removed bolts along the otway coast rates of erosion are much slower hence the greater number of still readable sites after 32 yr compared to other micro erosion meter studies the rates reported here are at the lower end of the range of values from around the world but nevertheless consistent with rates from the otway coast and others in similar lithology we found no statistical difference between erosion rates calculated over 2 yr 1979 to 1980 and 32 1979 to 2011 years supporting the view that shore platform lowering rates measured over 2 yr are representative of decadal scales

short term rock surface expansion and contraction in the intertidal zone transverse micro erosion meter tmem stations were installed in rock slabs from shore platforms in eastern canada the slabs were put into artificial sea water for 1 6 or 11 hours representing high mid and low tidal areas respectively the tmems were used to record changes in surface elevation as the rocks dried during the remainder of the 12 h of a semi diurnal tidal cycle a similar technique was used on the same rock types at intertidal tmem stations in the field as the rocks dried during low tide argillite and basalt surface contraction was from 0 to 0 04 mm there was little surface expansion sandstones contracted by up to 0 03 mm in the field but there was almost no contraction in the laboratory argillite and basalt contraction tended to be greatest in the upper intertidal zone and to increase with rates of longer term surface downwearing but there was little relationship with rock hardness or air temperature and humidity changes in elevation at the same points at tmem stations in the laboratory and field were quite consistent from one tidal cycle to the next but there were considerable variations within single tidal cycles between different points within each station the data suggest that contraction within the elevational zone that is normally submerged twice a day by the tides is by alternate wetting and drying short term changes in elevation are generally low compared with annual rates of downwearing owing to erosion but they may generate stresses that contribute to rock breakdown copyright 2007 john wiley sons ltd

modern accumulation rates and a sediment budget for the eel shelf a flood dominated depositional environment the northern california continental margin is periodically impacted by geologically significant storms which have a marked influence on terrigenous sediment supply flood deposition and long term accumulation of fine grained sediment on the eel shelf accumulation of eel river muds on the adjacent shelf was investigated using 210pb and 137cs geochronologies in order to understand the fate of sediment discharged by the eel river and to relate patterns of net sediment accumulation 100 yr time scale to sediment dynamics 210pb data demonstrate that modern accumulation of river mud occurs from the 50 m isobath seaward across shelf accumulation rates decrease from maximum mid shelf values of 0 6 1 7 g cm 2 yr 1 to values of 0 2 0 4 g cm 2 yr 1 at the shelf break with a spatially weighted mean of 0 5 g cm 2 yr 1 0 4 cm yr for the entire shelf 210pbxs sediment depth profiles from the region of highest accumulation rate are characterized by subsurface intervals of low and uniform activity which are produced by flood deposition in some cores particular 210pbxs activity intervals may be associated with major eel river floods of 1955 1964 and 1974 it is postulated that because of the coincidence of high river flow events and southerly winds during cyclonic winter storms net northward transport allows for preferential deposition of fine grained sediment north of the river mouth over the past 100 years fluvial sediment input combined with marine dispersal processes have produced a mid shelf depocenter evident by both the spatial distribution of 210pb accumulation rates and by clay rich flood layers partially preserved in shelf deposits a fine grained sediment budget for the dispersal system based on hydrological data and 210pb geochronologies demonstrates that a maximum of 20 3 109 kg yr of the mean annual supply of fluvial mud 14 109 kg yr is trapped on the shelf the results of this study demonstrate that 1 short term sedimentation processes associated with floods can influence sediment accumulation on longer time scales and 2 a major fraction of fine grained sediment supplied to tectonically active margins by flood prone mountainous rivers bypasses narrow continental shelves

new insights on the relative contributions of coastal processes and tectonics to shore platform development following the kaikōura earthquake we describe the immediate impact of the 14 november 2016 kaikoura magnitude 7 8 mw earthquake on shore platforms and cliffs around kaikoura peninsula the earthquake caused an instantaneous uplift of 1 01 m of the peninsula we resurveyed 7 profiles previously used for erosion monitoring and observed changes in the configuration of the shoreline the coseismic uplift has fundamentally changed the process regime operating on the platforms and altered the future trajectory of shore platform and cliff development our observations highlight the interplay of waves weathering biology and tectonics at this location tectonism strongly modulates the process regime driving instantaneous changes in morphology and altering rates and patterns of erosion finally the uplift of the kaikoura coast has implications for changing resilience to climate change and sea level rise

source diagenesis and fluxes of particulate organic carbon along the western adriatic sea mediterranean sea article i nfo in this study we investigated the modern organic carbon oc cycling along the clinoform shaped deposit that developed after the attainment of the modern sea level in the adriatic sea 5 5 kyr cal bp newly acquired data were combined with published results to characterize the i origin ii diagenesis and iii fluxes of oc along the adriatic clinoform 13 c 14 c and lignin phenols were used to constrain the composition of oc accumulating in surface sediments sediment cores collected at different water depths were used to describe the early diagenesis during burial in different regions in addition on the basis of an extensive number of accumulation rates and oc data we assessed the flux of oc to the seabed and its burial our results showed that terrigenous oc is the dominant oc source in the po prodelta mainly in the form of pre aged soil derived oc and vascular plant fragments along the clinoform both 14c and the concentration of lignin derived phenols decreased with increasing distance from the po prodelta indicating the influence of an additional pool of aged oc that gradually becomes more important because of its selective preservation during the sediment transport as a result degradation rates k decreased along the clinoform as a function of the sediment oxidative history the calculated half life of reactive oc t1 2 was 14 6 yrs in the po prodelta whereas topset forest deposits south of this region exhibited higher values 100 yrs indicating the presence of refractory material in the distal bottomset region the t1 2 was particularly high ranging from 255 to 912 yrs because of the significant southward component of the sediment transport the oc deposition in the southern surface sediments exceeded the local oc input via rivers ratio deposition input 1 2 conversely the northern adriatic was characterized by a marked imbalance ratio deposition input 0 3 0 5 according to our calculations the oc flux to the seabed along the clinoform was 309 gg of c per year whereas the oc burial was 180 gg of c per year corresponding to an overall burial efficiency of 59

geomorphic tectonic control of sediment discharge to the ocean the importance of small mountainous rivers analysis of data from 280 rivers discharging to the ocean indicates that sediment loads yields are a log linear function of basin area and maximum elevation of the river basin other factors controlling sediment discharge e g climate runoff appear to have secondary importance a notable exception is the influence of human activity climate and geology on the rivers draining southern asia and oceania sediment fluxes from small mountainous rivers many of which discharge directly onto active margins e g western south and north america and most high standing oceanic islands have been greatly underestimated in previous global sediment budgets perhaps by as much as a factor of three in contrast sediment fluxes to the ocean from large rivers nearly all of which discharge onto passive margins or marginal seas have been overestimated as some of the sediment load is subaerially sequestered in subsiding deltas before the proliferation of dam construction in the latter half of this century rivers

measuring erosion with the micro erosion meter contributions to understanding landform evolution abstract we review the contribution made to understanding landform evolution through the use of the micro erosion meter mem and the variant the traversing micro erosion meter tmem the mem has allowed the direct measurement of bedrock erosion in terrestrial and coastal settings as well as of building stone as recorded in mem measurements world wide the average rate of surface lowering on shore platforms is 1 486 mm a 1 and on terrestrial rock surfaces measured lowering rates are on average 0 903 mm a 1 reported means obscure significant variation in rates from a range of environmental settings and lithologies the mem has in a number of examples allowed the identification of the contribution of individual processes in polygenetic settings particularly in shore platform studies the dynamic nature of rock weathering has been highlighted where the tmem has revealed rock surfaces swelling and contracting at time scales ranging from hours to years the mem will continue to provide useful data on erosion rates and processes but the most fruitful investigations will be those that combine the t mem with other techniques that transcend time and space scale issues in erosion and process measurement

fine sediment mass balance in the western adriatic continental shelf over a century time scale abstract to obtain a quantitative estimate of the sediment accumulating on the muddy belt extending along the western adriatic continental shelf a budget was calculated based on the mass accumulation rates measured from more than one hundred activity depth profiles of 210 pb 137 cs depth distributions were used when possible to support 210 pb results 210 pb profiles show quasi monotonic declines in the foreset region of the central adriatic clinoform in the prodelta of the rivers po and isonzo 210 pb profiles are characterized by intervals of low and uniform activity which are thought to be produced by flood deposition since the north adriatic is shallow and occasionally affected by storms from bora wind sediments are not in steady state and their accumulation is the net result of recurring deposition resuspension and winnowing events in the western adriatic mass accumulation rates range between 0 04 and 6 6 g cm 2 yr 1 peak values were recorded in the po and isonzo prodeltas and along a narrow belt between pescara and the gargano promontory furthermore the latter depocentre is located immediately seaward of the offlap break 40 50 m water depth and parallels that of the most recent sigmoid of the hst the integration of mass accumulation rates throughout the mud wedge of the north and central adriatic gave a value of 42 0 tg yr 1 of sediment accumulating along the italian coast the balance between sediment accumulation and riverine sediment supply 46 6 tg yr 1 suggests an export of 4 6 tg yr 1 to the south adriatic basin and or the mediterranean sea the along shore sediment transport is very effective and in particular 16 2 tg yr 1 of sedimentary material 35 of the riverine supply is transferred from north to central adriatic through the ancona section

manganese distribution in the carbonate fraction of shallow and deep marine lithofacies middle ordovician eastern tennessee abstract a marked increase in manganese content from shallow to deep marine lithofacies can be observed within the carbonate fraction of the middle ordovician sequence in eastern tennessee the distribution of manganese is controlled by 1 the original aragonite and calcite mineralogy of shallow and deep marine environments respectively 2 preferential substitution of manganese for calcium in the rhombohedral structure of calcite 3 anoxic depositional and diagenetic environments and 4 possibly volcanism

pre and synorogenic burial metamorphism in the ardenne and neighbouring areas rhenohercynian zone central european variscides abstract the rhenohercynian zone of the central european variscides contains in the central ardenne eifel brabant campine region of belgium france germany and luxemburg an omnipresent thermal overprint which reaches in places uppermost epizonal conditions because of its distribution and structural relationships this metamorphism cannot be explained by a singular tectonometamorphic event field and microstructural observations new illite crystallinity and other data relating to this metamorphism are presented together with a review of existing petrological illite crystallinity vitrinite reflectance conodont alteration index and fluid inclusion data and their relationship to small and regional scale geological structures three distinct geotectonic situations can be described which overlap and alternate in space and time 1 the oldest metamorphism which reached epizonal conditions can be localized in the pre devonian basement rocks of the brabant massif and with minor evidence of the stavelot massif further south it is clearly related to a pre variscan caledonian deformation event and could be of burial origin 2 the main regional metamorphism affected all devonian and carboniferous rocks and the lower palaeozoic basement highs of the ardenne eifel area it does not exceed diagenetic conditions in some areas but reaches maximal values of 500 c and 400 mpa in the serpont and rocroi massif areas theye and fransolet 1993 robion et al 1995 it is pre to synkinematic to the main variscan contractional penetrative deformation and correlates well with the age and thickness of the sedimentary cover rocks the metamorphism is associated with the pre carboniferous preorogenic rifting stage of the rhenohercynian basin and documents the peak of subsidence and sediment accumulation we interpret it as diastathermal metamorphism it reaches its maximum in the low grade metamorphic zones of the ardenne area which are inverted synsedimentary structures 3 the diastathermal metamorphism is overprinted in the central part of the ardenne eifel area middle devonian to carboniferous rocks of the dinant synclinorium by an anchizonal beginning epizonal metamorphism in the foreland basins north of the midi fault zone it reaches diagenetic to lowermost anchizonal conditions it is the expression of the burial by thick synorogenic mid to upper carboniferous cover rocks which were deposited in piggyback and foreland basins this clastic wedge relates to the carboniferous contraction of the rhenohercynian basin whose metamorphosed rocks were themselves affected by the deformation of the advancing orogenic front

progressive folding and foliation development in a sheared coticule bearing phyllite abstract an evolutionary sequence of fold and foliation development interpreted to be the result of a single progressive deformation is seen in exposures of strongly sheared phyllite and coticule 10 km south of the e w trending chedabucto fault in the meguma terrane of nova scotia canada transposition sensu sander at mesoscopic and microscopic scales is fundamental to this development as are fold hinge rotation and migration the transposition process is cyclic with folds of layering and foliation developing rotating and being refolded fold hinges and axial surfaces repeatedly tend towards stable end orientations but do not reach them due to the cyclic transposition process the foliation is a steady state feature continually reconstituted by microscale transposition and dynamic recrystallization several important consequences of these contemporaneous processes are 1 geometrical relationships between folds and foliation are variable in the same outcrop even though both developed synchronously and many folds have the geometrical relationships of cleavage transected folds 2 the foliation is transient in orientation and therefore cannot track the xy principal plane of total finite strain and 3 fold hinge migration may be a common process especially in deformations involving a large component of simple shearing the observed relationships may be applicable to study of fold and foliation development in orogenic belts in general

the multidecadal spatial pattern of erosion on sandstone shore platforms in south eastern australia abstract knowledge of the spatial pattern of erosion on shore platforms is needed to better understand their evolution the long term spatial and temporal variation of downwearing remains difficult to interpret from erosion data commonly collected over 1 3 years of monitoring we report erosion data recorded with a micro erosion meter mem over 40 years 1979 2019 on sandstone shore platforms in a micro tidal environment along the otway coast victoria australia this well preserved monitoring network 43 out of 44 original mem sites allowed a detailed investigation over a multidecadal timescale not previously considered over 40 years the mean erosion rate was 0 25 mm yr this value was statistically similar to erosion rates calculated over 2 year 0 32 mm yr and 32 year 0 26 mm yr periods in the vertical plane two significant but opposite relationships between elevation and erosion rates were displayed in the central intertidal zone there was also a peak in the erosion rate near mean higher high water level this spatial pattern was strongly associated with wetting and drying controlled by tides and waves at elevations lower than mean higher low water downwearing rates were one or two orders of magnitude lower than the average rate of the entire platform the low erosion rates may be caused by the longer wetting condition of surfaces at lower elevation fast erosion rates were recorded in the upper intertidal zone where the bedrock was only inundated by spring high tides or storm waves salt weathering may be the primary mechanism but the effect of thermal weathering cannot be neglected at higher elevation based on the experience from the near complete mem network in the study area suggestions were provided to extend the longevity of monitoring network for future long term erosion records on shore platforms

short term microscale topographic changes of coastal bedrock on shore platforms we report a series of short term diurnal rock surface monitoring studies on inter and supra tidal shore platforms using a traversing micro erosion meter at two sites kaikoura peninsula new zealand and apollo bay victoria australia statistically signi cant day to day changes were measured surface rise and lowering occurred at rates above instrument error with a maximum range of 3 378 mm between 1 697 mm lowering and 1 681 mm rise individual measurements showed rises greater than 2 mm these daily variations reveal that surface lowering and rise occur at a much shorter time scale than previously reported from other studies the patterns observed suggest wetting and drying is the most likely process causing surface changes at these temporal scales we argue that traversing micro erosion meter studies operating at a short term time scale of day to day provide meaningful results that open new opportunities for studying rock weathering and erosion in a coastal environment copyright 2004 john wiley sons ltd

beach etching and shore platforms etch forms are widely recognised in continental landscapes but little attention has been given to the etch factor in the coastal context evidence mainly from south australia and the iberian peninsula is cited of weathering fronts fortuitously located within the tidal zone and exposed by the stripping of a regolith by waves in addition the possible effects of beach etching or weathering by waters retained by beach sediments are discussed such weathering is difficult to prove in detail but circumstantial evidence from south australian sites suggests it contributes to the development of shore platforms as well as to cliff foot depressions and an assemblage of minor forms such as basins rock doughnuts and fonts the zonation of basins and gutters noted on some coasts may also and in part reflect beach etching

coastal mixing in multiple mouth deltas a case study in the po delta italy abstract satellite imagery provides evidence of complex mixing dynamics in the coastal zone in front of multiple mouth deltas one peculiar feature identified in front of the po delta italy consists in warmer water bulges present in some periods in the coastal zone between the river mouths such features are evident during both high and low river discharge through an integrated approach based on the analysis of satellite imagery in situ field data and a high resolution oceanographic model representing the whole river delta sea system we investigated the relative contribution of the different forcing in controlling coastal mixing of riverine waters the results evidence that the occurrence of these warmer saltier water bulges is due to upwelling induced by the combined action of tides and wind regimes aligned along coastline winds from the land and along the coast drive the upwelling through the well known mechanism described by ekman the presence of river discharge enhance the water column stratification creating the conditions in which tidal action follows the tidal straining theory both processes are identified in modelling results the occurrence of these localized coastal waters with peculiar thermohaline characteristics detectable on satellite imagery of the area can be relevant in the definition of the freshwater areas of influence and the mechanisms of riverine water mixing in the near coastal zone this can shed some light eventually on characterizing the sediment dynamics as well as the thermohaline properties of waters in the area and also to identify eventual impacts on the local ecosystems and fishery

the role of saltwater and waves in continental shelf formation with seaward migrating clinoform continental shelves have generally been interpreted as drowned coastal plains associated with the allogenic effect of sea level variation here without disputing this mechanism we describe an alternative autogenic mechanism for subaqueous shelf formation driven by the presence of dissolved salt in seawater and surface waves we use a numerical model describing flow hydrodynamics sediment transport and morphodynamics in order to do this more specifically we focus on two major aspects 1 the role of saltwater in the subaqueous construction of continental shelves and 2 the transformation of these shelves into seaward migrating clinoforms under the condition of repeated pulses of water and sediment input and steady wave effects but no allogenic forcing such as sea level change in the case for which the receiving basin contains fresh water of the same density as the sediment laden river water the hyperpycnal river water plunges to form a turbidity current that can run out to deep water in the case for which the receiving basin contains sea water but the river contains sediment laden fresh water the hypopycnal river water forms a surface plume that deposits sediment proximally this proximate proto shelf can then grow to wave base after which wave supported turbidity currents can extend it seaward the feature we refer to is synonymous with near shore mud belts

decadal scale micro erosion rates on shore platforms abstract knowledge of the long term rates of erosion of shore platforms are needed to assist modeling platform development understand rates and modes of development and decipher issues of inheritance from former sea level few studies report rates from more than 2 years of monitoring we report decadal scale erosion rates using both a micro erosion meter and a traversing micro erosion meter with measurements from 30 years and 10 years respectively gross mean surface lowering rates measured over 10 years with a traversing micro erosion meter were 0 901 s e 0 116 mm yr compared with 1 130 s e 0 217 mm yr over two years over thirty years 1973 2003 12 micro erosion meter sites provide a mean surface lowering rate of 1 09 s e 0 126 mm yr compared to 1 43 s e 0 128 mm yr calculated over twenty years 1973 1993 from 15 bolt sites and 1 53 s d 1 45 mm yr from 31 bolt sites rates calculated over longer time periods are reduced compared to short term rates as a result of faster eroding bolt sites being removed from the data set comparison of means between short and long time periods for existing bolts show no significant difference that is short term measurements over two years are representative of decadal scale erosion rates in fact decadal scale rates may under represent rates of platform development because of the loss of faster eroding bolt sites the loss of such bolts means that obtaining long term erosion rates is problematic future modeling of shore platform development can use mem rates with more certainty but we recommend using higher rates from shorter term studies unless longer records are complete

surface swelling of coastal bedrock on inter tidal shore platforms kaikoura peninsula south island new zealand this paper reports the occurrence of swelling of coastal bedrock measured with a traversing micro erosion meter tmem on inter tidal mudstone and limestone shore platforms while numerous micro erosion meter mem studies have been made only a small number have reported surface swelling during this study 24 055 measurements were made with a tmem of those 4047 indicated swelling or 17 of the total number of measurements vertical swelling of up to 8 9 mm was measured and values of 3 and 4 mm were common swelling displayed a complex pattern with minor swelling being superimposed on longer period episodes duration of swelling events in excess of 697 days were recorded while other events were commonly in the order of 3 to 4 months there is a distinct seasonal variation with greater and more frequent swelling occurring during summer months compared with winter explanation for swelling includes the growth of salt crystals in rock lattices and expansion from wetting and drying warm summer temperatures provide the best conditions for both processes swelling appears to be an important precursor to erosion of material from shore platform surfaces the conclusion drawn is that subaerial weathering makes an important contribution to the lowering of the shore platforms on the kaikoura peninsula

shore platform downwearing in eastern canada micro tidal gaspe quebec abstract work has been conducted in the laboratory and field on a micro tidal subhorizontal shore platform in argillaceous rocks at mont louis in gaspe quebec surface downwearing rates for 450 rock samples were measured over 3 years in the laboratory at the neap low mid and high tidal levels under semi diurnal tidal conditions de ionized water was used to determine the role of wetting and drying and artificial sea water for the additional effect of salt and possibly chemical weathering another 300 samples were immersed in de ionized water or artificial sea water for 90 min every 1 2 or 3 weeks representing conditions between the neap and spring high tidal levels and exposed in air for 90 min every 1 2 or 3 weeks to represent conditions between the neap and spring low tidal levels surface downwearing was recorded in the field at 34 transverse micro erosion meter tmem stations most of which were installed along 4 shore normal profiles in 2004 and 2005 mean downwearing rates in the laboratory ranged from 1 25 mm yr 1 at the neap high tidal level to 0 63 mm yr 1 at the neap low tidal level downwearing was much slower between the neap and spring tidal levels and it was uniformly slow below the neap low tidal level the presence of salts inhibited downwearing within the neap tidal range where wetting and drying was dominant and promoted it between the neap and spring high and low tidal levels surface swelling was fairly common in the field and the mean downwearing rate 0 242 mm yr 1 was much lower than in the laboratory possibly because the tmem stations were installed in harder rocks modeling supports the contention that the mont louis platform was cut initially by waves at a higher elevation and then lowered by weathering in the last few thousand years as relative sea level fell to its present elevation

transition from turbidite to shallow water sedimentation in the lower salmian tremadocian lower ordovician of the stavelot massif belgium abstract the lower salmian tremadocian lower ordovician in the caledonian stavelot massif belgium consists of a sedimentary rock sequence which is thought to represent a transition from turbidite to shallow water sedimentation the succession starts with graptolitic mudstones and low density turbidites this is considered to be a relatively deep basin plain association the intermediate part is composed of finely laminated mudstones and siltstones with minor turbidites and is interpreted as a depositional slope sequence the upper part consists of siltstones which sometimes show wave influence and thick continuous sandstone bodies which are interpreted as offshore sand bars on a shelf this sequence is thought to represent the filling of a cambro ordovician epicontinental basin by a northward prograding clastic wedge characterized by high sedimentation rates

the formation of sedimentary strata in an allochthonous shelf environment the washington continental shelf nittrouer c a and sternberg r w 1981 the formation of sedimentary strata in an allochthonous shelf environment the washington continental shelf mar geol 42 201 232 models of fine scale 120 m shelf regions the inner shelf sand and mid shelf sandy silt are the predominant accretionary deposits on the shelf important sedimento logical observations obtained by boxcoring the upper 1 2 m of these deposits are a progressive decrease in grain size with distance from the columbia b downward coarsening within the seabed c loss of distinct sedimentary structure homogenization of sediment with distance from the columbia non dimensional parameters based on sediment transport and benthic biological studies can be used to relate rates of sediment mixing re working to rates of accumulation these parameters have the potential for quantitative prediction of strata formation from measurements of active processes physical and biological mixing can be assumed to remain relatively constant in an alongshelf direction on the washington shelf and accumulation rate is known from pb 210 geochronology to decrease away from the columbia together these factors tend to increase the ratio of mixing to accumulation with distance from the columbia and predict the sedimentological observations listed above

forty three years of micro erosion meter monitoring of erosion rates on shore platforms at kaikōura peninsula south island new zealand abstract using micro erosion meters mem and traversing micro erosion meters tmem surface lowering rates of shore platforms on kaik ura peninsula south island new zealand have been measured over a total of 43 years this record is the longest monitored network of this type since 1973 erosion rates have been calculated over two two year periods 1973 1975 n 31 and 1993 1996 n 55 and at decadal scales 1973 1993 n 15 1973 2004 n 12 1993 2004 n 46 1993 2008 n 34 1993 2016 n 18 1973 2016 n 6 after 43 years surface lowering rates remain similar to previously published rates at an average of 0 525 to 1 181 mm a 1 statistical analysis shows that erosion rates over all measurement periods are derived from the same population thus short term rates derived from two years of monitoring remain indicative of decadal rates of erosion variations between measurement periods are best explained by the loss of the more rapidly eroding bolt sites these losses point to the difficulty of maintaining monitoring over longer time scales a means of statistical manipulation previously published allows for these losses to be accounted for in determining long term rates of platform lowering in november 2016 a mw 7 8 earthquake raised the kaik ura peninsula approximately 0 8 1 m elevating much of the shore platforms above the tide range this earthquake has reset the mem record ending this long running erosion monitoring site of shore platform surface lowering however the mem network is now being used to monitor post earthquake response of the uplift shore platforms and new marine terraces

deposition and flux of sediment from the po river italy an idealized and wintertime numerical modeling study abstract recent studies of sediment dynamics and clinoform development in the northern adriatic sea focused on winter 2002 2003 and provided the data and motivation for development of a detailed sediment transport model for the area near the po river delta we used both idealized test cases and more realistic simulations to improve our understanding of seasonal sediment dynamics there we also investigated the relationship between physical processes and the observed depositional products e g the accumulation of sediment very near the po river distributary mouths sediment transport near the po river was evaluated using a three dimensional ocean model coupled to sediment transport calculations that included wave and current induced resuspension suspended sediment transport multiple grain classes and fluvial input from the po river high resolution estimates from available meteorological and wave models were used to specify wind wave and meteorological forcing model results indicated that more than half of the discharged sediment remained within 15 km of the po river distributary mouths even after two months of intensive reworking by winter storms during floods of the po river transport in the middle to upper water column dominated sediment fluxes otherwise sediment fluxes from the subaqueous portion of the delta were confined to the bottom few meters of the water column and correlated with increases in current speed and wave energy spatial and temporal variation in wind velocities determined depositional patterns and the directions of sediment transport northeasterly bora winds produced relatively more eastward transport while southwesterly sirocco winds generated fluxes towards both the north and the south eastward transport accounted for the majority of the sediment exported from the subaqueous delta most likely due to the frequent occurrence of bora conditions progradation of the po river delta into the adriatic sea may restrict the formation of the western adriatic coastal current increasing sediment retention at the po delta and reducing the supply of sediment to the apennine margin a positive morphodynamic feedback may therefore be present whereby the extension of the delta into the adriatic increases sediment accumulation at the delta and facilitates further progradation

paleozoic evolution of the armorica plate on the basis of paleomagnetic data new paleomagnetic data support the contention that armorica and gondwana formed a coherent block until ordovician time however by early devonian time armorica collided with the north american northern european assembly to form the old red continent and the collision itself was responsible for the acadian orogeny not for the earlier taconic orogeny as postulated previously the carboniferous collision of gondwana with the old red continent subsequently formed pangaea and produced the appalachian hercynian orogeny

coticules of the belgian type area stavelot venn massif limy turbidites within the nascent rheic oceanic basin abstract coticule is the name originating in belgium for a fine grained metasedimentary yellowish rock mainly composed of quartz spessartine and mica which is repeatedly interstratified in the hematite rich purple slates of the lower ordovician of the ardenne region it was described for the first time in the nineteenth century in the stavelot venn massif ardenne which is accordingly the type area for this peculiar lithology since then numerous occurrences were described all over the world in metamorphic rocks of various grades and ages the exact nature of the belgian coticule protolith remained hypothetical although intensively discussed for a long time in the literature after an extensive review of all the stratigraphical sedimentological and geochemical results and new field geochemical major and trace elements and nd isotopic investigations we propose a significantly improved and sustained genetic model the thin coticule layers were deposited offshore in a deep oceanic basin as limy mud turbidites during the early floian c 477 ma early ordovician density currents came from the north from the shelf which bordered the emergent brabant massif at that time and flowed down the slope to the deep basin plain the purple shales enclosing the coticule layers represent the normal pelagic sedimentation in the basin these shales are exceptionally rich in fe and mn because of the hydrothermal activity of the nearby and young rheic ocean ridge indeed the rheic ocean opened in the early ordovician c 482 ma during diagenesis the strongly oxidizing depositional environment favoured the mobility of mn 2 as opposed to fe 3 that remained insoluble and immobile this allowed for the migration of divalent manganese from the pelagic shales and for replacing calcium in the turbiditic carbonate fraction to form rhodochrosite later epizonal metamorphism transformed the clay quartz rhodochrosite paragenesis of the protolith into the muscovite quartz spessartine paragenesis of the coticule hence in the type area coticule genesis needed a peculiar environment including a continental shelf with limy mud deposits a continental slope generating periodical turbidites and a nearby oceanic ridge here the nascent rheic ocean delivering hydrothermal iron and manganese

event driven deltaic sedimentation on a low gradient low energy shelf the brazos river subaqueous delta northwestern gulf of mexico abstract the brazos river delta is located in the northwestern gulf of mexico sedimentation on the brazos river subaqueous delta has been largely understudied swath bathymetry data collected across the subaqueous delta reveals a noticeable asymmetry with much deeper water depths and greater cross shelf slopes along the eastern up drift side of the delta than along the western down drift side end member sampling reveals that brazos river derived sediment is red red brown or brown in color exhibits increased bulk density and is enriched in calcium a function of carbonate rich areas of the watershed whereas the gulf of mexico inner shelf muds are gray to black and have a relatively lower calcium content analyses of a series of 33 submersible vibra cores collected across the subaqueous delta reveal alternating beds of brazos river derived sediment and gulf of mexico shelf dominated sediment excess 210pb geochronologies of select cores reveal that sediment accumulation has been a combination of fluvial flood event deposition and deposition of remobilized sediment from the proximal shelf and older portions of the delta rather than steady state accumulation because the brazos river is susceptible to local climatic cycles fluvial flood events that create the event layers are intermittent between prolonged periods where marine processes drive accumulation results also show that the primary depocenter of the subaqueous delta has migrated southwestward over time and the erosion of earlier depocenters and proximal shelf sediment has contributed to accumulation on the delta over the past 50 years the subaqueous delta has reached an equilibrium where flood event beds can be completely remobilized within a year and net accumulation approximates relative sea level rise this study highlights relatively rapid clinoform migration due to natural and anthropogenic changes to the system and demonstrates subaqueous delta growth through a combination of direct fluvial and marine derived sediment input

modern rates of glacial sediment accumulation along a 15 s n transect in fjords from the antarctic peninsula to southern chile 1 rates of glacial erosion in temperate climates rank among the highest worldwide and the sedimentary products of such erosion record climatic and tectonic signals in many glaciated settings as well as temporal changes in glacier behavior glacial sediment yields are expected to decrease with increasing latitude because decreased temperature and meltwater production reduce glacial sliding erosion and sediment transfer however this expectation lacks a solid supportive database herein we present modern 210pb derived sediment accumulation rates on decadal to century time scales for 12 fjords spanning 15 of latitude from the antarctic peninsula to southern chile and interpret the results in light of glacimarine sediment accumulation worldwide 210pb records from the antarctic peninsula show surprisingly steady sediment accumulation throughout the past century at rates of 1 7 mm yr 1 despite rapid warming and glacial retreat cores from the south shetland islands reveal accelerated sediment accumulation over the past few decades likely due to changes in the thermal state of the glaciers in this region which straddles the boundary between subpolar and temperate conditions in patagonia and tierra del fuego sediment accumulates faster 11 24 mm yr 1 and previously collected seismic profiles show that rates reach meters per year close to the glacier termini this increase in sediment accumulation rates with decreasing latitude reflects the gradient from subpolar to temperate climates and is consistent with glacial erosion being much faster in the temperate climate of southern chile than in the polar climate of the antarctic peninsula

clinoform development by advection diffusion of suspended sediment modeling and comparison to natural systems clinoforms are the building blocks of prograding stratigraphic sequences these sig moid shaped surfaces can be found forming today on modem deltas sedimentation rate profiles over the clinoform surface of these deltas show low rates of sediment accumulation on both topset and bottomset regions with a maximum accumulation rate on the upper foreset region we pres ent a model for the formation of clinoforms that relies on the interpretation of modem clinoform sedimentation as a result of the distribution of shear stresses at the mouth of a river model clino form surfaces are generated using an equation for the conservation of suspended sediment concentration together with a conservation of fluid equation for simple time averaged flow velocity fields in the model suspended sediment is advected horizontally into a basin and gravitational settling of sediment particles is counteracted by vertical turbulent diffusion in shallow water shear stresses are too large to allow deposition and sediment bypasses the topset region with increasing water depth near bed shear stresses decrease and sediment is allowed to deposit at the foreset region with gradually decreasing rates toward deeper water this sedimentation pattern leads to progradation of the clinoform surfaces through time the clinoform surfaces produced by the model capture the fundamental morphological characteristics of natural clinoforms these include the gradual slope rollover at the topset and bottomset steeper foreset slopes with increased grain size and an increase in foreset slope through time as clinoforms prograde into deeper water because the parameters controlling the model clinoforms have a direct relation to physical quantities that can be measured in natural systems the model is an important step toward unraveling the physical processes associated with these deposits

the deltaic nature of amazon shelf sedimentation despite the annual discharge of more than a billion tons of sediment by the amazon river the sedimentary environment near the river mouth has little subaerial expression and thus does not meet the classic definition of a delta the river mouth however is not an estuary either these observations raise a major question as to what type of sedimentary environment the amazon river mouth represents seismic stratigraphy has been examined on the continental shelf at the mouth of the amazon river using high frequency 3 5 khz seismic records from about 6 000 km of ship track these records demonstrate three regions 1 the amazon river has built a subaqueous feature which stretches for hundreds of kilometres offshore and alongshore from its mouth the feature is prograding seaward and accreting upward and it contains fine scale stratification typical of classic deltas the feature forming at the mouth of the amazon is a subaqueous delta it differs from classic deltas primarily in its lack of subaerial expression subaqueous deltas such as the amazon represent the general case of a major river entering an energetic oceanic regime

where is the seaward edge a review and definition of shore platform morphology abstract shore platforms are erosional coastal landforms that have attracted scientific attention since the mid 19th century the defining element of a platform is width that is used in many calculations such as determining a platform s evolutionary state or inferring how wave energy is distributed along the shore although a critical variable there are no uniform criteria for defining the seaward edge quantification of platform width has been driven by site specific variables with the seaward edge defined on the basis of tides morphology biology processes and sediment coverage the lack of a uniform definition has meant that comparative studies are difficult and results are possibly spurious as widths derived from very different criteria can vary by an order of magnitude just on the basis of which criteria is used to determine its edge in this review a combination of morphologic and process elements is used to define the seaward edge of a shore platform the development of strict criteria is especially needed in an environment of rising sea levels if measurements of landscape change are to be made in addition the advent of seamless datasets that cross the land sea boundary means that the delineation of platform morphology is no longer limited by physical access this review concludes that the seaward edge of a shore platform will occur at or landward of wave base and should be defined as the point where active erosion of the bedrock ceases characterised by erosional features such as notches and block plucking scars or the deposition of sediment of such a thickness that the underlying bedrock is not exposed during storm events

clinoform sedimentation along the apennine shelf adriatic sea abstract sedimentation along the central adriatic coastline of italy results from a series of small distributed fluvial sources i e a line source draining the apennine mountains these rivers deliver 3 107 t y 1 of sediment contributing to the formation of a shore parallel shelf clinoform that has developed throughout the holocene across shelf sediment accumulation rates calculated from 210pb half life 22 3 years measurements are greatest on the clinoform foreset 1 cm y 1 which is characterized by seafloor crenulations in a few areas however for some cross sections of the clinoform accumulation rates are not significantly higher on the foreset than on the topset and bottomset indicating that the clinoform may not be actively prograding in those areas today accumulation rates increase southward along the shelf and are greatest near the gargano peninsula 1 7 cm y 1 between ravenna and the gargano peninsula 3 1 107 t y 1 of sediment accumulate on the apennine shelf although the amounts of sediment supply and accumulation are about the same additional po river sediment is thought to enter the system from the north and some sediment is transported beyond the gargano peninsula to the south anthropogenic activities particularly dam construction following world war ii have significantly impacted sedimentation in this region changes in 210pb profiles document reduction in sediment accumulation however observations during winter 2002 2003 using the short lived radioisotope 7be half life 53 3 d have indicated that some new sediment is delivered to the shelf during periods of elevated discharge so dam entrapment is not complete

fluvial dynamics in the castel di sangro plain morphological changes and human impact from 1875 to 1992 abstract in recent years morphology and hydrogeology of the castel di sangro plain have undergone significant man made changes the plain is located in a very complex geological area where the latium abruzzi carbonate platform the morrone rotella pizzone carbonate platform and the molise nappe meet hydrology hydrogeology morphology and neotectonics of the area are conditioned by interlocking and overlapping of such palaeogeographic units some of them can be clearly recognised in the upper and middle sangro area after outlining the geological structural and geomorphological features of the area the authors discuss the morphological changes which occurred in the sangro river pattern and its alluvial plain from 1875 to 1992 as a result of construction of major hydraulic structures dams river bed cementation urbanisation of flood plain and spring areas wells elements inferred from comparison of maps and aerial photographs were also considered the study provides a concise description of objective observations on both natural and man induced fluvial processes and groundwater flows

rock warming and drying under simulated intertidal conditions part i experimental procedures and comparisons with field data the wetting drying and warming cooling behaviours of rock and stone are known to influence the nature and rate of weathering the way materials warm up and dry out also influences their suitability as biological substrata while rock thermal behaviours have been measured under controlled laboratory conditions previous experiments have largely been restricted to terrestrial simulations due to practical constraints where efforts have been made to simulate intertidal conditions expansion and contraction of rocks or rates of breakdown i e sediment production and weight loss have been measured while detailed observations of thermal and drying behaviours have rarely been made a simple semi automated procedure is described that enabled measurement of surface temperatures and desorption evaporative water loss for different material types rock and concrete under simulated semidiurnal tide conditions some preliminary results are presented illustrating the types of data that were obtained and comparisons are made with temperature data collected on a rock platform in the uk to assess the ability of the procedure to adequately represent field conditions copyright 2011 john wiley sons ltd

sediment accumulation in a modern epicontinental shelf setting the yellow sea sediment accumulation in the yellow sea epicontinental shelf environment is investigated on 100 yr and 1000 yr time scales using 210pb and 14c geochronologies the distribution of modern 210pb accumulation rates in the yellow sea reveals that the loci of modern huanghe sediment accumulation are the topset 1 2 mm yr foreset 4 9 mm yr and proximal bottomset deposits 2 4 mm yr of the shandong subaqueous delta which extends south from the shandong peninsula 210pb rates in the distal bottomset deposits of the subaqueous delta in the central and southern yellow sea are generally low 0 3 0 9 mm yr a sediment budget demonstrates that between 9 15 of the annual huanghe discharge is accumulating in the yellow sea about two thirds of this sediment is accumulating in the topset foreset and proximal bottomset deposits of the shandong subaqueous delta with the remaining third accumulating as widespread distal bottomset deposits 14c age dates of subaqueous delta sediments indicate that the thick 40m clinoform structure formed predominantly between 6200 and 4060 yrs b p at rates approaching 20 mm yr observations in the yellow sea as well as on the amazon and ganges brahmaputra shelves demonstrate that subaqueous deltaic stratigraphy is the general rule where major rivers enter energetic shelves whether epicontinental or pericontinental the development of extensive bottomset deposits may be restricted to epicontinental shelf environments and may be diagnostic of sedimentation in this type of setting

shore platform erosion and evolution implications for cosmogenic nuclide analysis abstract determining rates and modes of shore platform development and the age of associated elements are among the greatest challenges facing rock coast researchers today these coasts generally lack dateable deposits but cosmogenic nuclide analysis cna can be applied directly to bare rock surfaces to estimate erosion rates or the time that a surface has been exposed over millennial timescales therefore this technique has the potential to revolutionize current theories on rock coast evolution and modes of development because environmental and geomorphological factors affect rates of nuclide accumulation and retention however the results of cna analysis are dependent on the validity of the theoretical models that have to be employed according to the particular application among the important assumptions that may be made are those concerned with shading tidal immersion beach sediment covers and other factors that influence rates of nuclide accumulation and with possible spatial and temporal patterns in shore platform erosion primarily by wave generated backwearing and weathering induced downwearing that reduce nuclide concentrations our lack of understanding of the factors that control these variables and in particular shore platform erosion which is the subject of this review has important implications for modelling rock coast evolution assessing the possible contribution of inheritance and dating especially by cna the occurrence of important formative events

the use of 7be to identify event and seasonal sedimentation near the po river delta adriatic sea in october 2000 a major flood event of the po river occurred the resulting seabed deposit was initially sampled in december 2000 and most sites were reoccupied on subsequent cruises over a 3 yr period using the maximum penetration depth of the short lived radioisotope 7be half life 53 3 d the flood deposit was found to be up to 15 cm thick individual depocenters of thick strata were located immediately adjacent to the distributaries at the river mouth in relatively shallow water 30 m these flood deposit thicknesses are minimum estimates because the depth of 234th half life 24 1 d exceeds that of 7be in physically stratified flood sediment indicating that the first sediment deposited during the flood event likely originated from the river channel 30 55 of the estimated sediment load delivered to the shelf during the flood event can be accounted for using 7be penetration depths seasonal deposition also can be quantified using 7be after removing the effects of biological mixing seasonal deposition rates are a maximum of 6 cm yr 1 near the pila distributary decreasing to 2 cm yr 1 in the southern portions of the dispersal system

adcp observations of the western adriatic slope current during winter of 2001 abstract data from an acoustic doppler current profiler adcp mooring maintained during the winter of 2001 in 57 m of water near senigallia italy are used to describe the winter conditions of the western adriatic current in the northern adriatic sea wind and water temperature measurements from the acqua alta tower in 19 m water depth off venice and winds from a 4 km resolution reanalysis model coamps are used to interpret the adcp data especially with respect to currents generated by bora winds at the adcp site mean depth average current for the winter deployment period was 10 4 cm s toward 140 roughly aligned with local bathymetric contours both mean currents and fluctuations about the means were highly barotropic during the winter southeastward along shore mean currents increased slightly 1 8 cm s with depth between 7 and 47 m following a nearly linear trend offshore cross slope mean currents only increased 2 0 cm s deep in the water column between 35 and 51 m current variability was dominated by four bursts of currents in which flow toward the southeast greatly increased these bursts followed bora winds the timing of which was identified by measured winds at the acqua alta tower depth averaged de tided currents exceeded 30 cm s during all four events and reached 45 cm s during one event correlations between these along shore currents and simulated wind stress from the coamps model were calculated over the whole north adriatic the cross covariance between currents and wind stress had a spatial pattern similar to the bora wind itself reaching maxima along the northern adriatic coast off the southern tip of istria and near ilovik island 14 5 n 44 4 e wind stress in these regions had stronger correlation with currents at the mooring than did wind stress anywhere near the mooring bottom water at the mooring was too warm for it to have been north adriatic dense water except perhaps for a brief pulse of cold water associated with the third current burst on april 1st

sedimentary response to climate and sea level changes during the past 400 ka from borehole prad1 2 adriatic margin 1 borehole prad1 2 was drilled in 186 m water depth on the upper slope of the central adriatic in the frame of profiles across mediterranean sedimentary systems promess1 european union funded project the borehole penetrated 71 2 m through a stratigraphic interval characterized by subparallel seismic reflections and uniform seismic units according to an age depth model based on several independent proxies including foraminifera and nannoplankton stratigraphy 18o curves and magnetostratigraphy the cored interval records marine isotope stages and substages mis from mis1 to the top of mis11 thus encompassing the past 370 ka prad1 2 therefore represents an unprecedented continuous record through the last four glacial interglacial cycles from a proximal continental margin setting where depositional sequences are typically composed of progradational units these progradational units record dominantly interglacial intervals mis5 mis7 and mis9 and appear composed of thicker highstand deposits hst formed during interstadials and thinner forced regression units fsst deposited during stadials above distinctive downward shift surfaces the development of thicker highstand deposits with a distinctively thicker bottomset reflects enhanced shore parallel advection any time sea level rise leads to the drowning of the adriatic shelf triggering the formation of dense water and vigorous cyclonic circulation this advection mechanism persisted in each cycle throughout the early phases of the sea level fall but progressively decreased as sea level fall proceeded approaching the maximum lowstand position when most of the shelf became exposed relative sea level falls punctuating interglacials within each 100 ka cycle were thus accompanied by a dearth in sediment flux on the outer shelf the alternation of hst and fsst progradational wedges with markedly different thickness and downlap geometry of their bottomsets is the most evident stratigraphic signature within each 100 ka depositional cycle of the impact on the shelf of higher frequency 20 ka sea level cycles and concomitant supply fluctuations

sediment dispersal in the northwestern adriatic sea 1 sediment dispersal in the adriatic sea was evaluated using coupled three dimensional circulation and sediment transport models representing conditions from autumn 2002 through spring 2003 the calculations accounted for fluvial sources resuspension by waves and currents and suspended transport sediment fluxes peaked during southwestward bora wind conditions that produced energetic waves and strengthened the western adriatic coastal current transport along the western adriatic continental shelf was nearly always to the south except during brief periods when northward sirocco winds reduced the coastal current much of the modeled fluvial sediment deposition was near river mouths such as the po subaqueous delta nearly all po sediment remained in the northern adriatic material from rivers that drain the apennine mountains traveled farther before deposition than po sediment because it was modeled with a lower settling velocity fluvial sediment delivered to areas with high average bed shear stress was more highly dispersed than material delivered to more quiescent areas modeled depositional patterns were similar to observed patterns that have developed over longer timescales specifically modeled po sediment accumulation was thickest near the river mouth with a very thin deposit extending to the northeast consistent with patterns of modern sediment texture in the northern adriatic sediment resuspended from the bed and delivered by apennine rivers was preferentially deposited on the northern side of the gargano peninsula in the location of thick holocene accumulation deposition here was highest during bora winds when convergences in current velocities and off shelf flux enhanced delivery of material to the midshelf

organic matter origin and distribution in suspended particulate materials and surficial sediments from the western adriatic sea italy abstract in this study organic carbon oc total nitrogen tn stable carbon isotopic 13 c oc and cuo reaction product compositions were used to identify the sources of organic matter om and to quantify the relative importance of allochthonous and autochthonous contributions to the western adriatic sea italy suspended particulate material 195 samples and surficial sediments 0 1 cm 70 samples from shallow cross shelf transects were collected in february and may 2003 respectively vertical water column profiles were acquired along the same transects data include depth potential temperature salinity density and chlorophyll fluorimetry along the western adriatic shelf in the near shore region the phytoplankton growth was influenced by dynamics of the buoyant plumes from the po and appennine rivers a small amount of very fine terrigenous material remained suspended within the coastal current and was exported southward along the shelf to the slope high variability in the bulk composition was detected in the po prodelta surficial sediments whereas the western adriatic shelf although a larger area exhibited a narrower range of values a significant decoupling was observed between suspended particles in the water column and surficial deposits the organic material collected in the water column was compositionally heterogeneous with contributions from marine phytoplankton riverine estuarine phytoplankton and soil derived om frequent physical reworking of surficial sediments likely leads to the efficient oxidation of marine oc resulting in the observed accumulation and preservation of refractory soil derived oc delivered by the po and appennine rivers

paleoenvironmental reconstruction of late quaternary succession by foraminiferal assemblages of three cores from the san benedetto del tronto coast central adriatic sea italy new shelf records based on benthic foraminiferal assemblages allowed reconstruction of the paleoenvironmental evolution of the central adriatic sea during the late quaternary four distinct assemblages related to four different environments were identified based on multivariate analyses cluster analysis and principal component analysis circalittoral shallow water with vegetation deltaic and shallow marine with riverine influence two main phases were recognized by comparing the study area with the northern and southern portion of the adriatic basin the first phase was characterized by the last glacial lowstand or the beginning of the last pleistocene transgression the foraminiferal assemblage distribution was controlled by sea level changes and by the location of the ancient po river delta likely placed at the northern margin of the mid adriatic deep a subsequent deepening from a deltaic to normal marine shallow water environment occurred river supply decreases consistently from the bottom to the top of the cores due to the northern migration of the po delta the second phase which occurred during the holocene was characterized by sea level stabilization and modern water circulation pattern circalittoral foraminiferal assemblage typical of the outer mud belt developed during this second phase

geological setting and genesis of coticules spessartine metapelites in the lower ordovician of the stavelot massif belgium the lower ordovician in the caledonian stavelot massif belgium contains a coticule member probably arenig in age composed of red hematite rich shales alternating with thin yellowish coticule beds these coticules are fine grained highly manganiferous metamorphic rocks mainly composed of spessartine garnet mica and quartz similar rocks of about the same age occur in several localities along the appalachian and caledonian fold belts the belgian coticules are thought to have originated from marly sediments which had been deposited rapidly probably by density currents and in which caco 3 had been diagenetically replaced by mnco 3 during metamorphism spessartine garnets were formed from this mnco 3 and mica manganese and iron are thought to have originated from volcanic exhalative processes

depositional controls on mixed carbonate siliciclastic cycles and sequences on gently inclined shelf profiles the interplay between carbonate production and siliciclastic input produces mixed systems that typically contain a very high degree of lateral and vertical facies heterogeneity this heterogeneity complicates the sequence stratigraphic analysis of mixed systems outcrop studies facilitate the deciphering of controls and understanding of facies distributions within sedimentary successions the picun leufu anticline in the neuquen basin argentina offers the opportunity to integrate large scale depositional architecture with detailed facies descriptions of the shelf to basin successions of the upper jurassic lower cretaceous quintuco picun leufu vaca muerta system the strata in the system are mixed and range in depositional environments from shallow marine sandstones and limestones to deep basinal shales these environments are arranged in metre scale shallowing upward cycles and cycle sets with increasing carbonate proportions in regressive hemicycles increased input of siliciclastic material from the volcanic arc area occurred during phases of relative sea level rise and was controlled by the intensity of along shelf currents the shelf transport was driven by the available accommodation space on the shelf and therefore was a function of the eustatic sea level fluctuations within the studied section a pure carbonate depositional system developed because siliciclastic input was shut down either due to long lived highstand settings or a sudden climatic change to more arid conditions carbonate siliciclastic mixing in this setting is a function of siliciclastic dilution of the carbonate sedimentation and differs from the classical reciprocal sedimentation model which typically includes shut off of carbonate production during lowstand periods in the regional context the subsurface strata of time equivalent reservoirs in the eastern neuquen embayment display strong similarities of architecture indicating that similar mixing processes occurred along most of the neuquen basin

frost weathering and the saturation of coastal rocks measurements were made of the water content in coastal rocks by simulating tidal oscillations in the laboratory and by field measurement in eastern canada if rapid freezing takes place upon exposure to the air saturation levels may be high enough to permit frost weathering in fine grained rocks in the lower portions of the intertidal zone near the high tidal level however it may be dependent upon a supply of water from the ice foot and from melting snow if freezing is slow frost action may be inhibited by desorption of the rocks while they are exposed by the ebb tide there was no evidence of a level of permanent sea water saturation within the intertidal zone ambient temperature and humidity may affect the rate of rock desorption

the effect of sediment mixing on pb 210 accumulation rates for the washington continental shelf abstract nine cores from the washington continental shelf were examined by radiochemical techniques in order to evaluate the effect of mixing on the calculation of sediment accumulation rates from pb 210 profiles th 234 profiles indicate mixing coefficients of 140 cm 2 yr 1 for the seabed offshore from the columbia river and 47 cm 2 yr 1 for the seabed of the mid shelf silt deposit 75 km north of the columbia river these large mixing coefficients demonstrate that particles can penetrate to the base of the intensely mixed surface layer 10 cm within one year after emplacement at the seabed surface observed depths of cs 137 penetration within the seabed are compared with depths predicted from the surface mixed layer thickness and the pb 210 accumulation rate the observed and predicted depths agree well at all but one station at this station a combination of th 234 co 60 pb 210 and cs 137 profiles suggests that active mixing occurs below the intensely mixed surface layer the agreement of pb 210 and cs 137 data at the other stations however indicates a general absence of deep mixing on the washington shelf thus the apparent accumulation rates calculated from pb 210 profiles below the intensely mixed surface layer on the washington shelf generally reflect the true rates of sediment accumulation

direct determination of7be in sediments cosmic ray produced7be 53 days half life is directly measurable in freshly collected samples of river and coastal zone sediments using a lithium drifted germanium detector calibration of the detector is discussed and an assessment of overall accuracy and sensitivity presented the detection limit for a 250 g dry weight sediment sample contained in a marinelli beaker and counted for 200 minutes is approximately 0 4 pci g applications toward locating zones of rapid sedimentation as well as in understanding shallow water sedimentation dynamics are suggested

tidal wetting and drying on shore platforms an experimental assessment abstract rocks were subjected to wetting and drying cycles with de ionized water under real time conditions using tidal simulators one third of the samples experienced 11 h of exposure and 1 h of inundation over a 12 h tidal cycle representing high tidal conditions one third experienced 6 h of exposure and 6 h of inundation representing mid tidal conditions and one third experienced 1 h of exposure and 11 h of inundation representing low tidal conditions we obtained 324 cores from igneous metamorphic and sedimentary rocks from ontario which were exposed to more than 930 wetting and drying cycles over 16 months we obtained 675 cores and cubes from basalts sandstones and argillites from shore platforms in eastern canada which were exposed to about 700 cycles over 12 months many of the cores and cubes experienced very little to no breakdown particularly those from the igneous and metamorphic rocks of ontario sandstones from a sloping platform in the macrotidal bay of fundy and argillites from a horizontal mesotidal platform in gaspe quebec were the most susceptible rock types with equivalent surface downwearing rates ranging from 0 to 4 mm year 1 the results suggest that downwearing rates decrease with elevation within the intertidal zone probably because rocks require much longer to desorb than to absorb water the experiments demonstrated that wetting and drying can be an important process on shore platforms in some types of rock helping to lower the height and reduce the gradient of sloping macrotidal platforms and to reduce the height of horizontal micro and mesotidal platforms

the formation of beaches on shore platforms in microtidal environments beaches are common features of many rocky shorelines and can be considered to be constrained by the underlying geology in mesotidal to macrotidal areas the slope of the substrate and sediment supply are the primary factors in constraining the size and development of beaches on shore platforms in microtidal settings it is not known if these factors are wholly responsible for determining the presence of beaches on shore platforms nor the contribution of other factors such as hydrodynamics the microtidal coast of victoria australia is surveyed in this study in order to quantify the morphological boundary conditions that constrain beach development on semi horizontal shore platforms an ample sediment supply indicates that the underlying geology is controlling the presence and absence of beaches where beaches occur they always overlie a rock ramp which is the steepest part of the platform the two most important morphological constraints were platform width and height both of which significantly correlated with beach volume an elevational threshold exists at just over 1 0 m where beaches cannot accumulate below this threshold platform width appears to be the principle constraining factor in beach accumulation an evolutionary model is inferred which suggests that dissipation of wave energy associated with platform widening plays an important role in allowing beaches to accumulate the model suggests beaches on platforms will be particularly sensitive to sea level rise copyright 2014 john wiley sons ltd

two hourly surface change on supra tidal rock marengo victoria australia a traversing micro erosion meter was used to measure rock surface micro topography over 40 cm2 on a supra tidal cliff face from early morning to late evening in late spring from 06 00 hours to 22 00 hours the relative heights of 188 coordinates were obtained using the meter at 2 hour intervals resulting in a data set of 1607 readings monitoring shows that rock surfaces are dynamic entities with significant rise and fall relative to the first measurement at shorter timescales than previously reported the maximum positive rise between readings was 0 261 mm and lowering was 0 126 mm the pattern of change did not relate as expected to environmental variables such as temperature or insolation rather the surface showed greater surface change in the early morning and late afternoon it is hypothesized that this pattern relates to the expansion and contraction of lichen thalli as moisture is absorbed during higher humidity in the morning and late afternoon the implications of these results for weathering studies are considered copyright 2006 john wiley sons ltd

patterns of surface downwearing on shore platforms in eastern canada downwearing rates were measured on shore platforms at about 200 transverse micro erosion meter tmem stations over periods ranging from 2 to 6 years there were seven study areas in eastern canada the platforms were surveyed and a schmidt rock test hammer was used to measure rock hardness more than 1200 rock samples from three of the study areas were also subjected each day over a 3 year period to two tidal cycles of immersion and exposure which simulated the central intertidal zone a further 840 samples were subjected to longer periods of exposure and immersion over a 1 year period which represented different elevations within the upper and lower intertidal zone respectively these experiments suggested that tidally generated weathering and debris removal is an effective erosional mechanism particularly at the elevation of the lowest high tides in the field mean rates of downwearing for each study area ranged from 0 24 mm yr 1 to more than 1 5 mm yr 1 rates tended to increase with elevation in the field with maxima in the upper intertidal zone this trend in the field cannot be attributed entirely to the tidally induced weathering processes that were simulated in the laboratory and must reflect in part the effect of waves frost ice and other mechanisms it is concluded that there are no strong spatial downwearing patterns on shore platforms and that downwearing rates in the intertidal zone are the result of a number of erosional mechanisms with different elevation efficacy characteristics furthermore even if only one or two mechanisms were dominant in an area any resulting relationship between downwearing rates and elevation would be obscured or eliminated by the effect of variations in the chemical and physical characteristics of the rocks copyright 2010 john wiley sons ltd

po river plume on the adriatic continental shelf dispersion and sedimentation of dissolved and suspended matter during different river discharge rates abstract suspended matter and dissolved nutrients were studied in the prodelta of the po river northern adriatic sea immediately after one of the greatest floods of the last century which occurred in october 2000 and in four successive seasonal conditions hydrology total suspended matter tsm particulate organic carbon poc and particulate nitrogen pn content organic carbon stable isotopes 13 c poc particle grain size spectra phytoplankton and dissolved inorganic nutrients i e nitrate nitrite ammonium phosphate and silicate were measured in different discharge conditions to describe processes occurring in the po river delta the main effect of high river discharge was a large volume of low salinity water at the surface that extended over the entire study area the concentration of most sampled variables decreased along a dilution gradient from the po river distributaries mouths to the offshore for tsm at the surface riverine input and dilution were the main factors affecting its distribution at the bottom however increased tsm in the nearshore was due to rapid sinking of suspended matter at the river mouth while resuspension and advection dominated the transport of near bottom sediments offshore at 15 20 m depth in the offshore where resuspension was active an increase in ammonium and decrease in oxygen supported the presence of regeneration processes occurring at the bottom during the october 2000 flood event high nutrient concentrations promoted new production triggering an algal bloom in the southern region of the study area the origin of particulate organic carbon in the river delta was then estimated from a mixing model based on 13 c poc values and carbon nitrogen c n molar ratios and as the contribution of three distinct sources of organic carbon were determined i e marine riverine and terrestrial the riverine end member accounted for 50 of the surface poc and generally decreased towards the offshore the terrestrial carbon contribution was generally the least abundant 20 28 at the surface and at depth respectively and exhibited peak values 30 40 during the october 2000 flood last the marine contribution was the most abundant at the bottom 40 and generally increased offshore during the october 2000 flood the fluvial contribution of particulate organic carbon that is the terrestrial and riverine fractions represented approximately 80 of the total particulate organic carbon in the po river delta

tourmalinite as a potential host rock for gold in the caledonides of southeast ireland initial investigations designed to test the potential for gold in a series of lithologies associated with tourmalinites and coticules in the neighbourhood of the caledonian leinster granite of southeast ireland are reported the results of geological mapping geochemical analyses and panning of stream sediments indicate that significant levels of gold are associated with some tourmalinite zones the possible exploration implication of this work is that tourmalinites have potential as target indicators although secondary controls on mineralization are also important

the adriatic sea general circulation part ii baroclinic circulation structure abstract in the second part of the paper dedicated to the adriatic sea general circulation the horizontal structure of the hydrographic parameters and dissolved oxygen fields is described on a seasonal timescale maps of temperature and salinity climatological fields reveal the enhanced seasonal variability of the adriatic sea which at the surface is associated with the major dilution effects of river runoff the density and derived dynamic height fields show for the first time the baroclinic geostrophic structure of the general circulation winter is dominated by compensation effects between temperature and salinity fronts along the western coastline the resulting baroclinic circulation is weak and suggests the presence of barotropic current components not accessible by the dataset spring and summer seasons have the smallest spatial scales in the temperature and salinity fields and stronger subbasin scale gyres and current systems which have been classified in a schematic representation of the circu

quartz spessartine metasediments coticules and their protoliths in north wales thin beds and small pods of quartz spessartine metasediments coticules occur in pelites of the gamlan formation cambrian of the harlech dome the original microfabric of these sediments has been largely destroyed by recrystallization under low greenschist facies conditions the quartz spessartine pods occur throughout the pelites and appear to have formed by the metamorphism of diagenetic mn carbonate concretions the thin beds of quartz spessartine rock appear to have formed by the metamorphism of a protolith which was deposited rapidly and repeatedly over a wide area although there is no direct evidence of the nature of this protolith the presence of altered mn carbonate rich tuff beds in anchizonal mudstones of similar age in the st tudwal s peninsula suggests that the bedded quartz spessartine rocks are in fact metamorphosed mn carbonate rich tuff units both the bedded and podiform quartz spessartine metasediments appear to have formed by reaction between clay minerals and mn carbonates of earlier diagenetic origin