depositional facies of a mud shoreface in suriname south america a mud analogue to sandy shallow marine deposits abstract immense volumes of argillaceous muds are being deposited along the world s longest continuous mud coastline which faces the open equatorial atlantic not only are these muds deposited in an environment normally associated with sand deposits but just as in sandstones sedimentary structures within these muds record the dynamic processes that deposited them this study investigates a 100 km long portion of the suriname coast utilizing cores bathymetric surveys and field observations from nearshore and innershelf environments using terminology borrowed from sand coastlines the innershelf nearshore of suriname is divided into transition zone shoreface foreshore and backshore the transition zone consists of a mix of offshore sands and shoreface muds shoreface and foreshore are subdivided into bank and interbank zones these zones are transitory because mud banks which make up the bank zones migrate westwardly mud banks are up to 5 m high 50 to 60 km long 10 to 20 km wide and oriented at oblique angles to the coastline these banks generally consist of fluid muds which are so fluid that they interact with surface waves causing them to be altered and damped banks are attached to the shoreline and commonly produce progradation of the coastline substrate within the interbank zone is more consolidat d than within the mud banks because of lack of wave dampening wave energies are relatively high within the interbank zone producing erosion of the shoreface and shoreline sand beaches are generally formed within the erosional interbank shoreline the vertical sedimentary sequence within the shoreface muds is a record of bank migration and other sedimentary processes present wave and current energies are recorded by scour and fill features discontinuity features micro cross laminations lenticular laminations and parallel to subparallel laminations laminations appear to be created by boundary layer shearing within fluid muds which are above wave base and made mobile by wave generated shore parallel currents large scale evidence for migration of the mud banks is westward dipping acoustical reflectors within the banks these reflectors which are over a kilometer apart mark the boundaries of annual migration events biogenic structures are generally absent within the fluid bank muds but are present within the more consolid ted interbank zone and associated with discontinuity features which are buried interbank surfaces migration and vertical stacking of mud banks are recorded by vertical sequences of massive and laminated muds which were deposited by mud banks and discontinuity features which were formed by interbank zones the coastal deposits of suriname are a mud analogue to nearshore and innershelf sand deposits transition zones of both mud and sand systems reflect a transition from offshore to shoreface processes and sediments both mud and sand shoreface foreshore systems reflect sediment input and wave current and tidal processes that act on them mud banks of suriname resemble linear sand ridges on the continental shelf of the eastern u s a in shape oblique orientation to the coastline and orientation with respect to dominant direction of transport processes the sequence of massive and laminated muds with discontinuity features resembles laminated to burrowed sequences found in ancient and recent nearshore and shallow marine sands

impact of late holocene aridification trend climate variability and geodynamic control on the environment from a coastal area in sw spain a detailed pollen analysis has been carried out on two sediment cores taken from a marsh area located in the donana national park southwestern spain the studied sedimentary sequences contain a si

comment on formation of chenier plain of the donana marshland sw spain observations and geomorphic model by a rodriguez ramirez and c m yanez camacho marine geology 254 2008 187 196 abstract the application of the regional marine 14 c reservoir effect r to obtain an accurate calibration of conventional marine shell 14 c dates requires prior research concerning the oceanographic conditions and the r of that region rodriguez ramirez and yanez camacho a rodriguez ramirez c m yanez camacho formation of chenier plain of the donana marshland sw spain observations and geomorphic model marine geology 254 2008 187 196 and afterwards a rodriguez ramirez j a morales j borrego and e g san miguel in a reply a rodriguez ramirez j a morales j borrego e g san miguel reply to the comment on formation of chenier plain of the donana marshland sw spain observations and geomorphic model by a rodriguez ramirez and c m yanez camacho marine geology 254 2008 187 196 marine geology 263 2009 123 125 to the comment by j rodriguez vidal f ruiz and l m caceres on the paper mentioned above j rodriguez vidal f ruiz l m caceres comment on formation of chenier plain of the donana marshland sw spain observations and geomorphic model by a rodriguez ramirez c m yanez camacho marine geology 254 2008 187 196 marine geology 263 2009 120 122 use in both cases not only incorrect r values for the calibration of 14 c dates obtained from shell samples collected from the east coast of the gulf of cadiz but they also confuse the r concept with that of r t the 14 c reservoir age because the misunderstanding of these concepts by these authors and in the first case also their failure to take into account the r values obtained by us and already published from the east coast of gulf of cadiz all the calibrated dates presented either in the first paper or in the reply cannot be accepted here i present a new calibrated dataset using accurate r values and i recommend that the conclusions obtained by rodriguez ramirez and their collaborators be revised as j rodriguez vidal f ruiz and l m caceres proposed in their comment

sedimentary impacts of anthropogenic alterations on the yeongsan estuary south korea abstract over the last half century coastal zones within the republic of korea s korea have experienced a wide range of engineered coastal modifications including construction of seawalls extensive land reclamation and installation of estuarine dams the yeongsan estuary has experienced all of these modifications and provides an ideal case study on how sedimentation changes within a macrotidal estuary in response to these alterations combined these alterations have considerably modulated the timing and intensity of river discharge prevented natural tidal exchange modified the shoreline profile and altered the transport of sediment and organic matter within the coastal zone these impacts have been investigated using 30 gravity cores analyzed for 210 pb radioisotope geochronology laser diffraction particle size analyses 13 c and 15 n isotope ratio mass spectrometry and x radiography average sediment accumulation rates range from 0 9 0 6 cm yr 1 to 10 0 2 9 cm yr 1 with the highest rates proximal to the downstream side of the dam and some areas determined to be either actively eroding or recently dredged these results are supported by comparison of multiple bathymetric surveys and chirp seismic data suggest an order of magnitude increase from average holocene sediment accumulation rates side scan sonograms collected adjacent to the dam reveal distinctive scouring transitioning to areas accumulating fine grained sediments shifts in the organic matter source inputs are apparent in pre post dam sediments and reflect the occluding of tidal influence above the dam resulting in increasingly terrestrial dominated signatures additionally a time series of cores collected during periods of limited and high discharge analyzed for 7 be indicates sediment deposition occurs episodically corresponding to high discharge dam releases our observations record a shift in depositional environments as a response to an extensive array of anthropogenic alterations ultimately land reclamation and dam construction have severely altered the fate and transport of sediment within the estuarine system as a consequence sedimentation rates have increased dramatically and depositional events are primarily controlled by discharges from the estuarine dam

sedimentary record of recent tsunamis in the huelva estuary southwestern spain abstract the coast of the gulf of cadiz has been repeatedly struck by tsunamis during the late holocene and the historic period historical documents record at least seven catastrophic tsunamis affecting this coast while others have been detected by oceanic instruments nevertheless very few studies have documented the sedimentary record of these tsunamis in the low energy coastal environments of the gulf of cadiz the huelva estuary is located at the central sector of the gulf of cadiz and is a mesotidal estuary fed by the tinto and odiel rivers the mean tidal range of the huelva estuary is ca 2 m and the mean significant wave height is ca 0 5 m the outer part of the estuary is characterized by extensive sand rich sedimentary bodies of marine origin whereas the central and inner parts are infilled by muddy tidally deposited sediment bodies recorded within these estuarine sediment bodies are five laterally continuous shelly units these units display many of the typical characteristics of tsunami deposits each typically comprises an erosional base followed by a fining upwards sequence that begins with the shell accumulation and ends with bioturbated muddy sand the results of 14 c ages and recent radionuclides accumulation rates in this study illustrate that these five tsunami deposits correspond with known events that occurred in ad 1755 1531 949 1033 881 and 395 381 all of which are documented in historical sources

holocene evolution of a barrier island system ria formosa south portugal holocene evolution of the ria formosa barrier island system was studied through the examination of a large subsurface dataset acquired from 191 boreholes and five seismic refraction profiles two b

suspended matter and fluid mud off alleppey southwest coast of india abstract time series measurements on suspended particulate matter spm were made at one non mud bank m1 and two mud bank stations m2 and m3 off alleppey south west coast of india the mean spm was low in surface 6 2 mg l and mid depth 3 7 mg l waters and higher in bottom depth waters 24 6 mg l of these stations during both pre monsoon and monsoon seasons near bed suspended sediment results indicated low spm during july 0 042 g l and september 0 018 g l at m1 but very high spm at m2 9 2 g l and m3 6 2 g l during july that decreased m2 0 033 g l m3 0 1 g l again in september observations based on lisst 25x indicated that optical transmission ot was high 80 100 in surface and mid depth waters but decreased with increasing depth near bed waters at m2 and m3 stations showed 1 m thick fluid layer with 0 ot and with high particle volume concentrations 150 200 l l during monsoon bottom sediments were clayey silts sediments of

holocene estuary development in the algarve region southern portugal a reconstruction of sedimentological and ecological evolution this paper presents a reconstruction of the former coastal estuaries of the quarteira and carcavai estuaries in southern portugal based on sedimentological geochemical and palynological analyses of holocene sediment cores the results show that each estuary developed differently depending on the morphology of the palaeovalley environmental conditions and especially the influence of the sea and the formation of barrier systems both estuaries were flooded between 7000 and 5500 cal bp by sea level rise and were almost completely filled by sediment by the beginning of the roman occupation 226 bc 2176 cal bp a clear change in sedimentological processes is evident in both estuaries between 5500 and 3000 cal bp and is interpreted as an erosion phase or evidence of high energy events such as storms or tsunamis

evidence of high energy events in shelly layers interbedded in coastal holocene sands in cadiz bay south west spain in some present day coastal areas recent inactive deposits now outside the reach of sea agents can be observed these deposits although formed under different climatic and sea level conditions often show similar facies to current littoral deposits they are frequently interpreted as old dunes and beach ridges or as abandoned spit bars representative of previous dynamic stages nevertheless in coastal areas which have been subjected to highly energetic events similar deposits can also be found when a dynamic event acts on several adjacent environments the transported and re deposited sediments can create homogeneous deposits with similar facies that are easily confused in this work shelly layers interbedded in relict littoral sands located in the la algaida pinewood on the edge of the rio san pedro tidal channel in cadiz bay south west spain have been studied the main constituents of the shelly beds are glycimeris valves organisms which are no longer found as live specimens in the present day sea bed of cadiz bay from their appearance the origin of these shelly beds could be related to sea washovers generated by tidal or storm action but their disposition and height over the present sea level implies that even higher energy agents were involved in their formation such as major storms or tsunami waves the most significant process was the mobilization of the sub tidal and littoral sediments and their dispersal and re sedimentation both lengthways and widthways of the coast giving way to homogeneous sandy deposits in all littoral environments some of which are now outside the reach of current sea agents the exception is the present day shore of the san pedro tidal channel where the sediments are being reworked by tidal and small wave action if the proximity of the study zone to the limit of the african and iberian plates is considered where several historical earthquakes and tsunamis have taken place it is possible to think that these deposits could be a consequence of sporadic and successive washovers generated by tsunamis occurring between ad 800 and ad 1200 sedimentological and historical data indicate an increase in seismic and tsunami activity during this period of time while the shelly layers would be the consequence of the most intense pulses occurring during these high energy events copyright 2009 john wiley sons ltd

modelling of estuarine response to sea level rise during the holocene application to the guadiana estuary sw iberia this paper focuses on simulations of the morphological evolution of an estuary during sedimentary infilling that accompanied holocene sea level rise the simulations were conducted using the estuarine sedimentation model which uses a behaviour oriented approach supported by the chronostratigraphy of the estuary s sedimentary sequence behaviour curves were computed to represent the relationship between the estuarine channel depth below maximum high tide and the net accretion at a given location relative to the average sedimentation rate of the estuary during the holocene the model was validated by comparing the observed present day bathymetry of the guadiana river estuary southeastern portugal with the corresponding simulated bathymetries for nine control sections across the estuary the best fit between simulated and actual sediment surface elevations was obtained along the cross sections in the sheltered low energy environments of the estuary the accuracy of the sedimentary stratigraphy of the best fit model was further established using 16 radiocarbon ages obtained from five boreholes in the estuary the present approach is particularly suitable for simulating long term morphological evolution in sheltered estuarine environments where tidally driven vertical aggradation dominates at centennial to millennium timescales however the accuracy of simulated sediment surface elevations and consequently the robustness of behaviour type models based on geographical information system platforms can be enhanced by incorporating i the impacts of nearshore hydrodynamic processes and episodic flood events in highly energetic channels and ii the impacts of cross currents in meandering channel sections

sedimentological evidence of an assumed ancient anchorage in the hinterland of a phoenician settlement guadiana estuary sw spain abstract as bays lagoons and estuaries ensure protection from wind and a hinterland rich in natural resources is most enticing during the early iron age the seafaring phoenician settlers chose such locations all over the mediterranean for their seaports establishing pan mediterranean trade from the late 9th century bce onwards despite the difficult nautical conditions phoenician sailors had conquered the strait of gibraltar by the end of the 9th century bce today many of these sites along the mediterranean and atlantic coasts are located several kilometers inland due to coastal progradation this paper investigates whether the wetlands of the estero de la nao a tidal channel and small tributary within the lower guadiana estuary gulf of cadiz sw iberia were able to serve as a potential natural harbor location and port of trade for the seafaring phoenician population the focus of this study is set on a systematic analysis of sedimentological data the lithostratigraphy of three sediment cores shows that at least 8000 years ago open water conditions existed within a marine embayment characterized by sedimentation under estuarine conditions this situation prevailed for several millennia from the early bronze age silting up processes of the former navigable areas occurred additionally a distinct stratigraphic gap within the sedimentary sequence of one particular sediment core provides strong evidence of ancient dredging activities that attempted to cope with the local siltation processes in the most recent strata badly sorted sediments intercalated with brick and shell fragments provide evidence of a high energy event probably triggered by the great lisbon earthquake in 1755

trace elements in holocene sediments of the southern donana national park sw spain historical pollution and applications the multidisciplinary analysis of core sediments from donana national park south spain permits to delimitate both the paleoenvironmental changes and the geochemical evolution of this area during the holocene in a first phase 10 6 5 kyr cal this area was occupied by freshwater brackish marshes with periodical alternation of dry periods and humid intervals in a second phase these marshes were inundated during the flandrian transgression 6 5 kyr cal with the deposition of bioclastic sands the third phase 6 5 3 6 kyr cal is characterized by the transition to an old lagoon with unpolluted bottom sediments the geochemical concentrations of these clayey sediments can be used as a geochemical background for present day and future environmental evaluations of this area in the following 600 years approximately two tsunamis caused the partial infilling of this area with bioclastic marine sediments in the interval comprised between these two tsunamis this lagoon was polluted with heavy metals derived from historical mining activities this environmental contamination represents one of the oldest evidences of mining pollution in the world 3 kyr cal bp

field observations and modelling of holocene sea level changes in the southern bay of biscay implication for understanding current rates of relative sea level change and vertical land motion along the atlantic coast of sw europe abstract the absence of basal peat in the stratigraphic sequences of the southern bay of biscay has long precluded the development of holocene sea level curves we have approached this problem by combining the indicative depositional meaning derived from the micropalaeontological composition and sand content with radiocarbon ages of 55 borehole samples obtained from three estuarine areas of the southern bay of biscay these new sea level index points have produced the first complete holocene sea level curve from this area we further reviewed all available sea level data from sw europe to provide the regional trend and use these data to calibrate a recently developed isostatic model field data and model reconstructions present a good agreement for the region considered a north south trend is apparent in the data and this is shown to be dominated by the influence of the deglaciation of eurasian ice sheets as suggested by previous studies for this region however some data model discrepancy in the south of the iberian peninsula suggests that local factors tend to dominate during the late holocene on comparing our results to estimates of recent sea level rise obtained from tide gauges and high resolution proxy records it is clear that this region has experienced a significant acceleration in sea level during the past century or so

magnetic tracing of sediment dynamics of mudbanks off southwest coast of india in this study we utilized environmental magnetic in combination with sedimentological and hydrodynamic data to investigate the formative processes of mudbanks along southwest coast of india we document the linkages between enrichment of silt sized magnetic particles and formation processes of mudbanks along alappuzha coast a trend of increasing magnetite concentration and coarsening in magnetic grain size is observed at mudbank stations m2 and m3 while the mud deficient station m1 showed an opposite trend a strong relationship between magnetic and physical grain size for all samples implies that the magnetic particle size and clastic grain size are largely adjunct analysis of rock magnetic and grain size data of surficial and suspended sediments from non mudbank m1 and two mudbank stations m2 m3 reflect the differential sediment partitioning and transport regimes which controlled the formation of mudbanks along alappuzha coast two plausible mechanisms responsible for the formation of mudbanks are identified grain size selective entrainment is the dominant process during pre monsoon weaker hydrodynamics waves and bottom currents favors accumulation of silt sized fine and coarse magnetic and non magnetic fractions resulting in the formation of magnetically low enriched sediment bed of mixed grain sizes at the onset of monsoon wave induced energetic bottom currents enhance the suspension of entire sediment bedload at stations m2 m3 to form fluid mud concurrently mineral density based selective fractionation allows the settling of coarse silt sized magnetic particles while the fine magnetic silt size particles accumulate forming thick fluid mud as a suspension load resulting in the formation of mudbanks an observed increase in magnetic susceptibility and coarsening in magnetic grain size of surficial sediments at mudbank stations m2 m3 during monsoon period supports the interpretation our findings are summarized in a conceptual model which can be very well applied to investigate sediment dynamics associated with mudbank formation in coastal and shelf sedimentary systems

paleoenvironmental evolution of the guadiana estuary portugal during the holocene a modern foraminifera analog approach in this paper we reconstruct the holocene paleoenvironmental evolution of the guadiana estuary southwestern iberian peninsula two previously studied boreholes cm3 and cm5 were revisited and an

an insight into subterranean flow proposition around alleppey mudbank coastal sector kerala india inferences from the subsurface profiles of ground penetrating radar the mudbank formation along south western indian coast has been a scintillating phenomenon during monsoon season and the source of mud is a debatable issue till now in the midst of many hypotheses the subterranean passage is considered a possible one but needs to have supportive scientific evidence this present study endeavours to demonstrate the potential use of the ground penetrating radar gpr in generating subsurface information to locate buried paleochannels in coastal zone which could act as the conduit for transport of mud from terrestrial sources to sea the historical maps of the late 1600 s show that the present day vembanad lake was a part of the nearshore area and the coastline was nearly 60 km inside drained by the rivers from the western ghats due to shoreline migration towards the seaside since late holocene the present day landforms came to existence while the earlier channels got buried under recent sand nearly 500 m long gpr subsurface 6 m depth penetration profile was generated and various paleochannels were traced these buried channels were categorised based on the pattern of their occurrences two erosional surfaces at around 1 and 2 m were mapped and their controls on paleochannels were derived during phase i many paleochannels were in active condition and due to heavy deposition during phase ii though these channels managed to maintain themselves but the width of their courses got narrowed and in recent times they got filled up and buried the pre monsoon and monsoon gpr profiles signify the high degree of wetness characteristics of these buried channels during monsoon season and their possibility of being passages for possible transport of water charged with fine clay materials through the unconsolidated in filled material in these buried channels this demonstrative and first hand subsurface information through gpr studies would further support to facilitate in consolidating the subsurface evidence for strengthening the subterranean passage concept in the mudbank area of the south western coast of india

ichnology and sedimentology of a mud dominated deltaic coast upper cretaceous alderson member lea park fm western canada abstract current depositional models largely promote the perception that all open coastal distal sea proximal land gradients are reflected by upward coarsening grain size trends and that shoreline deposits are represented by prominent sand bodies although commonly the case significant departures from this model may occur when the availability of coarser sediment calibers sand sized and larger is limited this is especially true where alongshore sediment transport influenced depositional systems are associated with rivers that supply abundant suspended sediments underestimating the role of grain size segregation may lead to misinterpretations of energy levels and water depths especially in some shale dominated sedimentary units the upper cretaceous alderson member lea park fm is an up to 180 m thick gas charged shale unit that we interpret as an ancient analogue for modern offshore and mud dominated deltaic coasts sedimentological and ichnological data collected from 27 cores indicate that much of the sediment volume of the alderson member was deposited in relatively shallow water under the influence of tidal and wave processes in a deltaic coastal setting characteristic features reflecting these depositional affinities include 1 increased proportions of terrestrially derived organic matter 2 indications of thixotropic to soupy substrates e g fluid mud coupled with rapid depositional rates 3 an impoverished ichnological signal planolites dominated suites 4 micro laminated shale 5 shale on shale erosional contacts 6 scour and fill structures and 7 intervals of low angle cross stratification the interpretation of relatively shallow water settings is also supported by recurring root bearing horizons glossifungites ichnofacies demarcated transgressive surfaces of erosion and conglomeratic surfaces at particular stratigraphic levels the deposits are interpreted to include offshore subaqueous deltas muddy shoreface and or tidal flat and aggradational muddy coastal plain chenier plain sub environments the results of this study improve our knowledge of ichnological and sedimentological characteristics of shallow marine shale units and are potentially useful for recognition of similar nearshore mud prone deposits elsewhere

chronology and tectono sedimentary evolution of the upper pliocene to quaternary deposits of the lower guadalquivir foreland basin sw spain this paper presents new litho chrono and magnetostratigraphic data from cores of 23 exploratory boreholes drilled in the abalario and marshlands areas of the lower guadalquivir basin the western sector of the guadalquivir foreland basin sw of spain the lithologic logs of these boreholes identify four main sedimentary formations namely almonte sand and gravel lebrija clay and gravel marismas clay and abalario sand respectively interpreted as proximal alluvial distal alluvial alluvial estuarine and aeolian from radiocarbon and magnetostratigraphic data these formations were dated as upper pliocene to holocene in the marshlands area three main sedimentary sequences are present an upper pliocene to lower pleistocene sequence of the almonte and lebrija lower unit formations a pleistocene sequence of the lebrija upper unit and the lower marismas formations and a latest pleistocene to present day sequence of the upper marismas formation the three sequences began as a rapid alluvial progradation on a previously eroded surface and a subsequent alluvial retrogradation in the third sequence estuarine and marsh sediments accumulated on top of the alluvial sediments the aeolian sands of the abalario topographic high developed coeval to alluvial and estuarine sedimentation after the first alluvial progradation and continuously until the present correlation with the surrounding areas show that the sequences are the result of the forebulge uplift of the northern margin of the basin sierra morena and the adjacent neogene oldest sediments of their northern fringe both form the main source area of the study formations this uplift occurred simultaneous to the flexural subsidence sse tilting of the southern part of the basin where sedimentary aggradation dominated

the coastal archives of the last 15 ka in the atlantic mediterranean spanish linkage area sea level and climate changes sea level and climate changes archived in various coastal environments during the last part of the last glacial and present interglacial periods are investigated by interpolating available geomorphology sedimentology palaeontology and geochronology data the coastal response to these changes depended on the environment and geographic location changes of sea level during the rising transgressive phase are well recorded in the sedimentary filling of the estuaries whereas during the phase of highstand they are best recorded in beach barrier environments the postglacial rise of sea level took place in two phases a rapid rise until 6500 cal bp and a second phase of near stability with minor oscillations of metric magnitude regarding climate changes there is no record of changing temperatures in the coastal zones of southern spain although there is in precipitation and wind intensity velocity after 7 5 cal ka bp the general climatic trend towards aridity was punctuated by several short lived centennial episodes of increased aridity that occurred with a millennial cycle often coincident with bond cool events and in some cases with decreases of sea surface temperatures the absence of human intervention in vegetation composition until 2000 bp suggests that most environmental coastal shifts were climatically driven

periodic mudflat progradation northeastern coast of south america a hypothesis abstract the guiana coast of northeastern south america backed by mangrove swamps and fronted by migrating mudflats and associated subtidal mudbanks has developed during the holocene as a prograding mud wedge from amazon derived sediment a hypothesis is offered for the periodic stabilization of shifting mudflats a process that has been recognized previously as the mechanism for initiation of new land growth the hypothesis assumes that solar semiannual and 18 6 yr tidal components allow abnormal exposures of coastal mudflats and conditions that are favorable for establishment of avicennia mangroves once colonized mangrove roots displace muds upward thus decreasing the frequency of tidal inundation and increasing the ability of vegetation to trap and hold muds based on estimated ates of root growth and forecasted tide records for the coast of surinam land elevation will increase by 25 cm in 10 yr and frequency of tidal inundation above 2 45 m 8 0 ft will decrease from 106 to 2 per year during the same period

holocene sea level and climate interactions on wet dune slack evolution in sw portugal a model for future scenarios we examine the holocene environmental changes in a wet dune slack of the portuguese coast poco do barbarroxa de baixo lithology organic matter biological proxies and high resolution chronology

onshore offshore correlation of the llobregat deltaic system spain development of deltaic geometries under different relative sea level and growth fault influences abstract groundwater resources in deltaic aquifers are essential in the mediterranean region to sustain the socio economic development of coastal communities and shallow water ecosystems understanding the geological connection between coastal aquifers and the offshore sedimentary record is important to better predict consequences in terms of water management in spite of this most approaches to postglacial and pleistocene deltaic sedimentation focus either on the offshore or the delta plain few studies correlate and integrate the entire system in the llobregat delta south of barcelona spain onshore offshore correlation is achieved by integrating data from sediment cores acquired on the deltaic plain with seismic profiles from offshore data integration enables the reconstruction of the entire deltaic system providing a more well defined picture and a better understanding of the onshore offshore stratigraphic framework in a late quaternary tectonically active narrow shelf in the western mediterranean basin the late quaternary record in the llobregat delta shows an unusual well preserved transgressive regressive cyclic stacking pattern which displays peculiarities compared with most mediterranean quaternary deltaic shelves given that the transgressive and highstand intervals appear to be significantly preserved both onshore and offshore the preservation of these deposits is attributed to the high subsidence rate on the continental margin controlled by quaternary faults and the structure of the basement and by sediment supply fluctuations depositional sequences also reveal contrasting patterns between the northeastern and southwestern llobregat shelves and show significant variability in the dip direction the results are compared with diverse stratigraphic architectures reported elsewhere and provide information to the ancient delta deposits about the distinct types of deltaic geometries generated under different sea level trends helping to improve sequence stratigraphic models where deltaic geometries generated during specific intervals of the sea level curve are poorly constrained and or documented

lunar impact basins stratigraphy sequence and ages from superposed impact crater populations measured from lunar orbiter laser altimeter lola data 1 impact basin formation is a fundamental process in the evolution of the moon and records the history of impactors in the early solar system in order to assess the stratigraphy sequence and ages of impact basins and the impactor population as a function of time we have used topography from the lunar orbiter laser altimeter lola on the lunar reconnaissance orbiter lro to measure the superposed impact crater size frequency distributions for 30 lunar basins d 300 km these data generally support the widely used wilhelms sequence of lunar basins although we find significantly higher densities of superposed craters on many lunar basins than derived by wilhelms 50 higher densities our data also provide new insight into the timing of the transition between distinct crater populations characteristic of ancient and young lunar terrains the transition from a lunar impact flux dominated by population 1 to population 2 occurred before the mid nectarian this is before the end of the period of rapid cratering and potentially before the end of the hypothesized late heavy bombardment lola derived crater densities also suggest that many pre nectarian basins such as south pole aitken have been cratered to saturation equilibrium finally both crater counts and stratigraphic observations based on lola data are applicable to specific basin stratigraphic problems of interest for example using these data we suggest that serenitatis is older than nectaris and humboldtianum is younger than crisium sample return missions to specific basins can anchor these measurements to a pre imbrian absolute chronology

chronology of the sedimentary processes during the postglacial sea level rise in two estuaries of the algarve coast southern portugal abstract four profiles of estuarine sediments obtained from boreholes drilled in the algarve southern portugal were studied in order to reconstruct the process of sediment accumulation driven by the postglacial sea level rise in addition to the sedimentological analysis the foraminifera index of marine influence fimi permitted assessment of the nature and organization of sedimentary facies in the beliche guadiana and gilao almargem estuaries the beliche guadiana cm5 and almargem g2 profiles accumulated in a sheltered environment with the former presenting an almost continuous record of the sea level rise since ca 13 000 cal yr bp the g1 and g3 profiles from the gilao almargem area represent a more discontinuous record of the last 8000 years which accumulated in the more dynamic environment of an outer estuary the integration of all radiocarbon ages of dated levels led to an estimate of sediment accumulation rates assuming a constant position of the sediment surface with respect to the tidal range and a negligible compaction of sediment the sea level rose at the rate of 7 mm yr 1 in the period from 13 000 to 7500 cal yr bp this process slowed down to ca 0 9 mm yr 1 from 7500 cal yr bp until the present the marked historical change in the rate of sediment accumulation in these estuaries also occurred with the accumulation of organic matter and is therefore important data for global biogeochemical models of carbon the main obstacle to obtain higher temporal resolution of the sedimentary processes was the intense anaerobic respiration of organic matter via sulphate reduction which did not allow any accumulation of peat and furthermore led to erasure of the palaeontological record by acid formed from the subsequent oxidation of sulphides

the holocene transgression into the estuarine central basin of the odiel river mouth cadig gulf sw spain lithology and faunal assemblages abstract six estuarine facies were distinguished recording the holocene history of sea level rise relating according to the start and development of the holocene transgression which flooded the coast of huelva facies 2 gravels facies 3 grey clayey silts facies 5 well sorted sands facies 4 silty sands facies 5 black clayey silts and facies 6 red muds this group overlies neogene sediments facies 1 three faunal assemblages open bay ob central estuary ce and wave domination wd including remains of macrofauna foraminifers and ostracods plus depositional features are identified in a sedimentological log constructed from a borehole with a continuous core sunk in the central basin of the odiel river estuary huela coast sw spain the ob assemblage requires shallow and protected zones controlled by low energy tidal currents the ce assemblage is located within an intertidal zone where reworked marine forms of foraminifers ostracods and scattered macrofauna co exist with small estuarine foraminifers and ostracods the wd assemblage comprises tests of marine macrofauna with fractured shells plus large marine foraminifers and estuarine ostracods during the first stage of continuous sea level rise 8720 260 bp to 5390 155 bp estuarine accretion high energy tidal currents and wave action took place successively allowing the development of the ob ce and wd assemblages the second stage 5390 155 bp to present with a stabilized sea level comprised a vertical decrease of energy with tidal currents favouring deposition in shallow tidal channels and marsh zones leading to less energetic ce assemblages within the estuarine central basin high sediment supply resulted in deposition during this stage which shows a regressive nature

comment on formation of chenier plain of the donana marshland sw spain observations and geomorphic model by a rodriguez ramirez and c m yanez camacho marine geology 254 2008 187 196 abstract rodriguez ramirez and yanez camacho 2008 rodriguez vidal et al 2009 and rodriguez ramirez et al 2009 have kept an ongoing discussion about the validity of radiocarbon ages in reconstructing holocene palaeogeographical models in the gulf of cadiz the discussion considered the validity and correctness of the r value to be used in the area to calibrate radiocarbon ages of marine samples these papers suggest that the r value proposed by lario 1996 and dabrio et al 1999 2000 is erroneous and consequently that all the evolutionary models based on radiocarbon ages from marine samples that have been proposed in this area since 1996 must be revised however the papers commented here use erroneously the r regional r and r values after reviewing the published data it is apparent that the most reliable values of r in the gulf of cadiz for middle late holocene samples range between r 35 85 yr and r 95 15 yr this means that the values used in lario 1996 and dabrio et al 1999 2000 fall in this range and also that the calibrated ages used by several authors adopting these values are fully reliable calibrations using r values inside this range do not yield significant differences in terms of geological age owing to the magnitude of errors resulting from the methods employed

pleistocene and holocene geomorphological development in the algarve southern portugal abstract a detailed chronological framework for pleistocene and holocene geomorphology and landscape evolution in the algarve is proposed with regards to the pleistocene attention has focused on the origin dating and stratigraphy of the ludo formation subsuming the classifications of earlier writers it is now proposed that during the pliocene a marine transgression occurred across a tectonically controlled basin that was constrained by the mountains of the algarve interior to the north fluvial sands were then deposited in a regressive phase during the late pliocene early pleistocene while braided streams operating under semi arid conditions subsequently laid down sands and gravels in the middle and upper pleistocene lying unconformably over the ludo formation is an alluvial deposit odiaxere gravels and loule sands of late pleistocene early holocene date that is found within the river valleys of the algarve in the early holocene ca 10 000 ca 7000 bp and early late holocene ca 5000 ca 3000 bp the situation in the algarve was one of climatic amelioration i e warmer and wetter conditions rising sea levels vegetation colonization soil development and towards the end of this period trenching of the odiaxere gravels and loule sands from ca 3000 bp evidence is abundant that humans became important geomorphological agents either acting on their own or in combination with climatic factors from around 5000 bp conditions became dryer and between ca 3000 bp and ca 700 bp clearance of land by pre roman roman and especially islamic agricultural settlers caused widespread erosion and the deposition of extensive spreads of topsoil dominated sediment within river valleys i e the holocene terrace and in coastal estuaries a period followed up to 1900 ce when agricultural practices were less damaging to the soil erosion was reduced and the holocene terrace together with coastal and estuarine deposits was incised in the past century and under increased human pressure renewed erosion is in evidence in the interior valleys and at the coast

evolution of estuarine facies in a tidal channel environment sw spain evidence for a change from tide to wave domination abstract the transition from tide to wave dominated environments is documented in holocene estuaries along the mesotidal coast of huelva southwestern spain this transition is a consequence of the decreasing tidal prism caused by estuarine siltation a process favoured by the inherited morphology of the prior fluvial valleys the domingo rubio tidal channel is a small estuary adjacent to the mouth of two wave dominated estuaries along the coast of huelva coring and vibracoring of both surficial and subsurface sediments allow the distinction of six lithofacies that form five depositional environments 1 salt marsh 2 active channel margin 3 washover fan 4 tidal channel and 5 estuarine channel the facies architecture reveals the infilling process of the tidal channel due to the interaction of both waves and tides wave activity is registered in the elongation of the spit whereas tidal action produces facies associations characteristic of tide dominated estuaries the recent history of this estuary records three successive stages 1 an initial tide dominated open marine environment beginning at 3090 60 years b p with strong tidal currents in very energetic channels displaying a straight meandering straight morphology 2 a wave dominated period during which waves transport sand into the inner estuary and also along the mouth spit at about 2500 years b p and 3 a second tide dominated stage from 300 80 years b p onward during which weaker tidal currents distribute the sediment four factors controlled the transition from tide to wave domination 1 the relief formed during deposition 2 the decreasing tidal prism 3 the inner facies distribution versus those of the outlet and 4 the seaward spit elongation of adjacent estuaries

geological record of an acidic environment driven by iron hydrochemistry the tinto river system 1 the existence of possible hematitic strata on the surface of mars demands a search for terrestrial analogues formed in unusual environments this will help us to recognize and interpret environmental and perhaps biological signatures preserved in mars hematites such an analogue would allow us to establish valid reference systems based on geomicrobial and biogeochemical signatures two different aspects place the tinto river inside the boundaries of a natural extreme system its high level of biological diversity and the presence of fluvial rocks formed in the same acidic conditions as in the modern system which could predate the tertiary study of both the modern system and the ancient system is necessary to understand the formation of biosignatures a chemolithotrophic community that biooxidizes the iberian pyritic belt acidifying water ph between 0 9 and 3 0 and favoring high concentrations of ferric iron in solution up to 20 g l 1 maintains this iron driven system in spite of these extreme conditions high microbial diversity was found its acidic bacteria archaea and eukarya constitute a complex community supported by algal biomass in highly stable hydrochemical conditions which are achieved through iron buffering the ph is maintained at constant low levels even at very high water dilution in these conditions iron minerals as oxyhydroxides hydroxides and sulfates are formed the modern and recent parageneses contrast with the ancient tinto river terrace mineral associations which show dehydrated and desulfated iron oxides if this dehydration process is considered these tinto river ironstones may be a key for knowing some aquatic habitats which may have hosted a part of the early mars biosphere

depositional history of estuarine infill during the last postglacial transgression gulf of cadiz southern spain abstract the late pleistocene and holocene evolution of the estuaries in the gulf of cadiz is interpreted for the first time using drill cores logs trenches and 38 new radiocarbon data and the results compared with the shelf the odiel tinto and guadalete rivers deposited conglomerates during a highstand that did not reach the present sea level dated at ca 25 30 ka isotopic stage is 3 corresponding to a relatively humid period in the area rivers incised these coarse grained deposits during the last main lowstand at ca 18 ka when sea level dropped to 120 m and the coastline lay 14 km seawards from the present the erosional surface is a sequence boundary and the flooding surface of the postglacial eustatic rise overlain by the valley fill deposits of the transgressive and highstand phases of the last fourth and fifth order depositional sequences recognised in the shelf the first marine influence in the estuaries during the transgression occurs at 25 30 m at ca 10 000 years bp according to fossil assemblages the transgressed basins changed from brackish to more open marine as the sea rose until ca 6500 years bp when it reached the maximum flooding and the sandy estuarine barriers ceased to retrograde toward the muddy central basins then the rate of eustatic rise decreased drastically and the estuarine filling followed a two fold pattern governed by the progressive change from vertical accretion to lateral centripetal progradation at ca 4000 years bp the fluvial input surpassed the already negligible rate of rise causing partial emergence of tidal flats and spit barriers in the largely filled estuarine basins prevalence of coastal progradation upon vertical accretion at ca 2400 years bp caused accelerated expansion of tidal flats and rapid growth of the sandy barriers further changes since the 16th century reflect widespread anthropic impacts

environmental isotopes to test hypotheses for fluid mud mud bank generation mechanisms along the southwest coast of india abstract occurrence of fluid mud mud banks in the southwest coast of india is an enigma for the scientific community over the years several multi disciplinary studies were conducted and various hypotheses were postulated on the occurrence and sustenance of fluid mud nevertheless none of them could be proved or disproved with field data in the present study an attempt was made to assess the validity of some of the prevailing hypothesis on its occurrence such as subterranean conduit flow of mud water from a coastal lagoon submarine groundwater discharge river flows etc by integrating field surveys refining the hydrogeological understanding of the area and application of environmental isotopes 222 rn 18 o 2 h and 3 h in the alappuzha mud bank region kerala during its formation in the southwest monsoon period in situ 222 rn monitoring survey in the coastal waters of pallana showed that 222 rn activities in the fluid mud region were negligible compared to the suspected continental end members such as pamba river vembanad lagoon shallow and deep groundwater indicating that there was no freshwater inputs from these sources comparison of the characteristic stable isotopic signatures of 18 o and 2 h in the samples from the fluid mud region and the suspected continental end members implied that there was no mixing of these water sources with the seawater 3 h results indicated that the shallow groundwater is modern and recharged annually from precipitation while deep groundwater in the warkali aquifer within the study area is old 50 years it also indicated that there is no vertical interconnection between the vembanad lagoon and the deep warkali aquifers hence from the study it appears that river flows submarine groundwater discharge or subterranean conduit flow flow from the vembanad lagoon may not be responsible for the occurrence and sustenance of fluid mud in pallana coast alappuzha

initial observations from the lunar orbiter laser altimeter lola as of june 19 2010 the lunar orbiter laser altimeter an instrument on the lunar reconnaissance orbiter has collected over 2 0 10 9 measurements of elevation that collectively represent the highest resolution global model of lunar topography yet produced these altimetric observations have been used to improve the lunar geodetic grid to 10 m radial and 100 m spatial accuracy with respect to the moon s center of mass lola has also provided the highest resolution global maps yet produced of slopes roughness and the 1064 nm reflectance of the lunar surface regional topography of the lunar polar regions allows precise characterization of present and past illumination conditions lola s initial global data sets as well as the first high resolution digital elevation models dems of polar topography are described herein

global assessment of pure crystalline plagioclase across the moon and implications for the evolution of the primary crust recent advancements in visible to near infrared orbital measurements of the lunar surface have allowed the character and extent of the primary anorthositic crust to be studied at unprecedented spatial and spectral resolutions here we assess the lunar primary anorthositic crust in global context using a spectral parameter tool for moon mineralogy mapper data to identify and map fe bearing crystalline plagioclase based on its diagnostic 1 25 m absorption band this allows plagioclase dominated rocks specifically anorthosites to be unambiguously identified as well as distinguished from lithologies with minor to trace amounts of mafic minerals low spatial resolution global mosaics and high spatial resolution individual data strips covering more than 650 targeted craters were analyzed to identify and map the mineralogy of spectrally pure regions as small as 400 m in size spectrally pure plagioclase is identified in approximately 450 targets located across the lunar surface diviner thermal infrared tir data are analyzed for 37 of these nearly monomineralic regions in order to understand the compositional variability of plagioclase an in these areas the average an for each spectrally pure region is estimated using new laboratory measurements of a well characterized anorthite an96 sample diviner tir results suggest that the plagioclase composition across the lunar highlands is relatively uniform high in calcium content and consistent with plagioclase compositions found in the ferroan anorthosites an94 98 our results confirm that spectrally pure anorthosite is widely distributed across the lunar surface and most exposures of the ancient anorthositic crust are concentrated in regions of thicker crust surrounding impact basins on the lunar nearside and farside in addition the scale of the impact basins and the global nature and distribution of pure plagioclase requires a coherent zone of anorthosite of similar composition in the lunar crust supporting its formation from a single differentiation event like a magma ocean our identifications of pure anorthosite combined with the grail crustal thickness model suggest that pure anorthosite is currently observed at a range of crustal thickness values between 9 and 63 km and that the primary anorthositic crust must have been at least 30 km thick

physical processes and fine grained sediment dynamics coast of surinam south america abstract the prograding holocene mud wedge between the amazon and orinoco rivers in the trade wind belt of northeastern south america provides a modern day example of muds accumulating under moderate wave energy conditions gigantic shore attached mudbanks 10 km 20 km composed partly of thixotropic fluid mud gel front this coast every 30 60 km to form a buffer to wave attack and a temporary storage for fine grained sediments this mesotidal coast tide range 2 0 m with gentle offshore slope 0 0006 allows the exposure twice a day of extensive tidal flat deposits which are backed by mangrove swamps on a well developed chenier plain complex field experiments were conducted in surinam du ing 1975 and 1977 to provide new information on process form relationships in this interesting but unusual muddy environment simultaneous measurements of waves currents tide elevation suspended sediment concentration and variations in mud density show that soft intertidal and subtidal muds are suspended at both tide and wave frequency suspended sediment concentrations typically exceed 1 000 mg l at the surface as incoming solitary like waves partially disperse fluid mud into overlying water on a falling or rising tide redeposition of mud may occur near time of high tide the strong attenuation of shallow water waves by these muds provides conditions that are favorable for further sedimentation high concentrations of suspended fluid mud together with solitary like waves from the northeast throughout the year can lead to extraordinarily high net sediment transport rates in the nearshore zone calculations based on solitary wave theory and on data obtained from this study indicate that 15 65 106 m3 of mud can move along shore each year without involving breaking waves the concept of radiation stress and a nearshore circulation cell or bedload transport farther offshore outside the zone of wave dominance wind driven currents and the guiana current combine to transport muds to the northwest consistent with the observed direction of mudflat migration

glycymeris shell accumulations as indicators of recent sea level changes and high energy events in cadiz bay sw spain abstract recent climatic and sea level changes have significantly modified coastal areas and caused the morphological evolution of littoral environments such is the case in cadiz bay sw spain where important changes have taken place from the late holocene to the present day and which have not yet been sufficiently established in this sense some sedimentary indicators such as the glycymeris shell deposits which can be found interstratified in recent coastal sand banks could shed new light on this issue three questions are addressed in this work firstly the age of these shell deposits secondly what is the depositional mechanism responsible for these shelly accumulations and finally what relationship can be established regarding recent sea level changes sample ages indicate that the shells are older than 1000 years bp while the facies indicate high energy flows as depositional mechanisms tides and waves seem insufficient in order to reach the upper shelly deposits for which a more energetic agent would be necessary such as tsunami waves which is feasible given that the zone is located in a tectonically active area where historical tsunamis have been recorded with respect to the relationship with a possible recent sea level rise this could be a better explanation since marine agents would be able to reach the necessary height

mixed energy process interactions read from a compound clinoform delta paleo orinoco delta trinidad preservation of river and tide signals by mud induced wave damping

a multiproxy study distinguishes environmental change from diagenetic alteration in the recent sedimentary record of the inner cadiz bay sw spain in this study we reconstruct the recent environmental evolution of the inner cadiz bay using sedimentary records reaching back as far as ad 1700 we report lithological descriptions of the sedimen

sedimentology of the kerala mud banks fluid muds abstract early workers have used the term mud bank to describe the intermittent appearance of calm patches of highly turbid water along the coastal tracts of kerala india during the southwest monsoon season the term fluid mud is recommended as a more accurate term a total of 32 grab and twelve core samples were collected from an area of 60 km2 off quilandi kozhikode india to evaluate the sedimentological aspects of mud resuspension in nearshore waters information on sediment discharge rainfall salinity gradient suspensate concentration wave wind and current patterns were also analysed to understand the fluid mud formation the topmost unit in the sediment cores is represented by a soft watery clay with a wedge shaped geometry the unit thickens towards the shore and the thin end lies about 9 km offshore this expanse of fine suspended sediment in water results from interactions of suspended material concentrations near bottom current velocity and wave activity in the coastal zone during the southwest monsoon strong swells churn up the bottom clay into a thick suspension the suspended sediment column develops a semicircular periphery in which wave energy is consistently absorbed lateral movement of the mud is controlled by the intensity and direction of littoral currents sem studies show a weakly disoriented platy and highly porous fabric in the upper clay zone as opposed to the relatively stable aligned supportive framework in the lower clay layer this suggests an easy dispersion of the upper clay zone with slight mechanical agitation in less saline coastal water freshwater discharge through river runoff may be an important factor in maintaining the suspension of mud due to deflocculation of clay particles the mud banks of the kerala coast differ from mud banks reported from other muddy coasts of the world in that they do not form regular relief forming features the transient nature of these mud banks their unpredictable periodicity and the calm and turbid nature of the water column suggest that they are episodes of fluid mud formation

does subterranean flow initiate mud banks off the southwest coast of india coastal waters off the southwest coast of india draw special attention because of the occurrence of mud banks at certain locations during southwest monsoon period the present study puts forward a hypothesis of a subterranean flow which could be a plausible mechanism to initiate the mud banks the subterranean flow is believed to be coupled with activated trending faults and originate from the adjacent watershed vembanad lake separated from the sea by a narrow strip of land where submerged porous lime shell beds are present when the lake water injection occurs through the fault the mud clay gets excited by its thixotrophic properties as the overlying water looses its electrolyte and transforms into a flowing fluid the lowering of salinity due to the introduction of fresh water keeps the mud suspension in the water column for longer duration leading to the formation of mud banks the idea of subterranean flow through lime shell beds initiating formation of mud banks may apply globally to any coastal regions hugged by wetlands and of similar geological conditions

nearshore sediment characteristics and formation of mudbanks along the kerala coast southwest india in order to gain insight into the formation dynamics of mudbanks off the kerala coast of india extensive surveying of the nearshore bathymetry along with sediment characterization was undertaken the textural and geotechnical properties of the surficial sediments of a mudbank were determined during pre monsoon monsoon and post monsoon periods the mudbank sediments were clayey silts with high water and organic carbon contents high atterberg limits and low bulk density and therefore very susceptible to entrainment during the monsoon the mudbank regime was characterised by enhanced turbidity and a benthic fluff layer triggered by the increasing swell of the early monsoon period re suspension exposed a more consolidated previously sub bottom layer which exhibited lower water content and greater shear strength than the pre monsoon seabed texturally the monsoon seabed was similar to the pre monsoon seabed with the same modal grain size but the proportions of sand and coarse silt increased nearshore while the proportions of fine and very fine silt increased offshore there was a seaward fining textural gradient at all times but this became pronounced during the monsoon period paradoxically the monsoonal seabed displayed greatly reduced wet bulk density it is hypothesized that this was due to the presence of gas probably methane in the sediments while the pre monsoon sediments were fully saturated the monsoon sediments were only 83 saturated we speculate that the gas was forced into the surficial sediments either by wave pumping at the onset of the monsoon or by seaward flowing subbottom freshwater derived from monsoonal rains with the waning of the monsoon the benthic fluid mud layer rapidly disappeared and the seabed returned to its pre monsoon state as suspended sediments were redeposited the mudbank regime is therefore essentially an in situ phenomenon it is suggested that the mudbanks are palimpsest marshy lagoonal deposits rich in organic matter and derived gas that were submerged after a marine transgression the surficial sediment is annually entrained during the monsoon but erosion is limited by the formation of the benthic fluid mud layer which attenuates wave generated turbulence although some fine sediment disperses alongshore and offshore most is returned to the seabed as the monsoon declines

global and regional factors controlling changes of coastlines in southern iberia spain during the holocene the interaction between global glacio eustatic sea level rise and regional factors oceanographic and tectonic has controlled the evolution of coastline during the holocene in southem iberia at ca 10 000 14c years bp a deceleration of relative sea level rise took place both in the atlantic and mediterranean littorals with a maximum transgression at 6450 14c years bp in subsiding areas present tidal flats estuaries illustrate a clear marine influence recorded both in sediments and the fauna while in uplifting areas prograding spit bar systems developed two phases of major progradation are distinguished in these systems the first one between 6450 and 3000 14c years bp with a sedimentary gap at ca 4000 14c years bp and the second one from 2750 14c years bp up to present with an intervening gap between 1200 and 1050 14c years bp these progradation phases develop during stillstands followed by relative sea level fall while the sedimentary gaps represent relative high sea level in the mediterranean areas with a higher uplift rate marine terraces almost coeval to those gaps occur the most pronounced modifications in littoral dynamics occurred at between 3000 and 2750 14c years bp represented by changes in the direction of longshore drift and prevailing winds and in the predominance of progradation over aggradation processes at ca 1000 14c years bp the estuaries record a greater fluvial than marine influence and at 500 years ago an extraordinary increase in coastal progradation took place in all littoral zones the european medieval warm period is characterized at least during its initial phase by low pressure climate conditions while during the little ice age anticyclonic conditions gave rise to a strong coastal progradation

a record of past ocean atmosphere radiocarbon differences from the northeast pacific a record of the 14c age differences between atmosphere and the mixed layer of the northeast pacific ocean was obtained from 58 radiocarbon measurements on shells and associated wood from coastal sediments in british columbia this series of mixed layer reservoir ages spans the holocene and extends into the period of the younger dryas cold event in the north atlantic and surrounding regions the data reflect the extent of upwelling in the northeast pacific and thus constrain models of carbon cycling and ocean circulation most of the reservoir ages are only slightly less than than the present preindustrial value of about 800 years and may be identical when probable sampling errors are taken into account either the north pacific reached a state close to its present mode of circulation at or before the end of the younger dryas or a different circulation fortuitously produced a similar reservoir age our results support the hypothesis that slow changes in atmospheric radiocarbon concentrations over the holocene arose from 14c production rate changes data corresponding to a radiocarbon age of around 6400 years b p give a reservoir age of 1200 years if this result is confirmed it indicates a much greater variability for the holocene ocean circulation than was previously believed possible

influence of system controls on the late quaternary geomorphic evolution of a rapidly infilled incised valley system the lower manawatu valley north island new zealand abstract the manawatu incised valley estuary was rapidly infilled between 12 000 4700 cal yr bp a combination of empirical measurements of sedimentation rates a reconstruction of relative sea level rsl change and digital elevation models of key surfaces within the holocene sedimentary fill of the valley were integrated to produce a numerical model to investigate the influence of the system controls of sea level change sediment flux and accommodation space on the rapid infilling history of the palaeo estuary the numerical model indicates that sediment flux into the palaeo estuary was greatest during the holocene marine transgression between 12 000 8000 years bp the average rate of sediment deposition in the estuary during this period was 1 0 m m 3 yr 1 this rapid rate of sedimentation was controlled by the rate of accommodation space creation as regulated by the rate of sea level rise and the antecedent configuration of the valley by the time sea levels stabilised c 7500 cal yr bp the palaeo estuary had been substantively infilled limited accommodation space resulted in rapid infilling of the central basin though sediment flux into the estuary between 7100 and 4500 cal yr bp was at a lower rate of 234 000 m 3 yr 1 the limited accommodation space also influenced hydrodynamic conditions in the estuarine central basin driving export of fine grained sediment from the estuary once the accommodation space of the estuarine basin was infilled sediment bypassed the system with a consequent reduction in the sedimentation rate in the valley more accurate partitioning of the sources of sediment driving the infilling is necessary to quantify sediment bypassing post depositional lowering of rsl index points from the valley is driven by neotectonics and sediment compaction

retracing the quaternary history of sea level changes in the spanish mediterranean atlantic coasts geomorphological and sedimentological approach abstract this study analyses coastal geomorphic responses to the various sea level changes that occurred throughout the quaternary period in the mediterranean and atlantic coasts of spain particular emphasis is paid to the geomorphic and stratigraphic record of the changes in amplitude duration and frequency associated with the major gradual climate changes observed in marine cores and ice oxygen isotope records during the early and middle pleistocene ca 2 6 myr ca 1 4 0 8 myr ca 0 4 0 2 myr and also with the rapid and abrupt late pleistocene and holocene climate changes with this aim the best preserved and most complete sedimentary sequences known in the spanish mediterranean and atlantic coasts covering diverse geodynamic and climatic contexts were selected and analyses this study is mainly based on field investigation of geomorphic sedimentologic and stratigraphic features of mapped morphosedimentary units combined with reliable chronological data the analyses include the interpretation of sedimentary environments the 3 d reconstruction of facies and morphosedimentary unit arrangement paying special attention to the lateral geomorphic relationships between marine and terrestrial morphosedimentary units developed during interglacials under sea level highstand scenarios the interglacials occurred during four key quaternary periods might be related with major gradual changes associated with glacial climate cycles reported from marine and ice oxygen isotope records almost coeval changes in geomorphological styles are reported from all studied areas regardless of their specific geodynamic context results from the mediterranean realm suggest that this area is more sensitive to climatic and sea level variability than the spanish atlantic coast particularly in the case of rapid and abrupt changes

short and medium term evolution of a coastal sector in cadiz sw spain abstract the present paper is a combined study on the medium and short term evolution of the littoral between chipiona and rota sw spain the analysis of coastal evolution over a period of 24 years i e medium term was carried out using six well temporally spaced photogrammetric flights cliff top and dune toe were used as shoreline indicators to solve problems related to the use of watermark in tidal environments short term littoral variations were monitored monthly by means of an electronic theodolite over a period of 2 years the width variations of the dry beach were surveyed by always using a constant average value for the mean sea level position derived from the numerous surveys carried out the obtained data was representative of both seasonal and annual variations over medium term most of the littoral recorded erosion while accretion has been recorded over recent years in the southern part coastal erosion was related to the impact of several storms and dune accretion was linked to the action of eastern winds over the short term time frame about the same percentage of coastal erosion and accretion was recorded most of the important accretion trends were observed at the central and southern parts of the littoral the largest amount of erosion being recorded in the southern end of the littoral in a nourished beach all the studied beaches except punta candor dunes showed more short term changes than medium term ones because of different factors essentially the great seasonal variability of the studied beaches the partial discrepancy between the medium and the short term trends was related to the applied methodology which demonstrates the problem of comparing different coastal features dunes and cliffs on one hand and beaches on the other and to the implications of 2 3 years of lasting fair weather conditions that favoured beach and dune accretion within an historical retreat tendency related to storm actions

changes in sedimentation trends in sw iberia holocene estuaries spain abstract an analysis of sedimentation rates during the holocene in estuaries in the southwestern coast of the iberian peninsula using depth age diagrams reveals the existence of two distinct phases the first between ca 10 000 and 6500 cal bp still in the transgressive phase yields values of sedimentation rates of 5 mm yr the second phase extends after the maximum transgressive ca 6500 cal bp until the present with sedimentation rates of 1 5 2 mm yr these results support the idea that marine sedimentation began during the transgressive phase and continued during the highstand phase far beyond the time of the transgressive maximum as postulated in some previous papers

radiative transfer model constraints on the shock state of remotely sensed lunar anorthosites 1 near ir spectra of some lunar basin rings and crater central peaks exhibit no evidence of absorption due to ferrous iron unlike all other spectral measurements of lunar soil in the laboratory or obtained remotely these spectral anomalies have previously been interpreted to indicate the presence of a deposit of essentially pure plagioclase feldspar anorthosite which has been shocked above 250 kb plagioclase possesses a diagnostic absorption feature near 1250 nm caused by trace ferrous iron that is lost when shocked above 250 kb whereas ferrous features of pyroxene are robust against shock however new methods for computing the optical effects of exposure of lunar materials to the space environment show that these optical effects can obscure the spectral features of plagioclase without resorting to shock modification of the plagioclase structure our modeling shows that shock is not necessary to explain the apparent lack of absorption but is not excluded either thus previous reports that some lunar surface features may have experienced high shock levels are not supported

palynological evidence for environmental and climatic change in the lower guadiana valley portugal during the last 13 000 years pollen analysis of a 48 m ams radiocarbon dated sediment sequence from the guadiana estu ary provides the first record of lateglacial and holocene vegetation history in the algarve province of portugal this paper focuses on the record of terrestrial pollen taxa which document a series of forest expansions and declines during the period 13 000 cal bp to 1600 cal bp and provide insights into climate evolution in southwestern iberia the main vegetation phases identified in the guadiana valley are 1 lateglacial interstadial allerod forest with quercus and pinus under a temperate moist continental cli mate 2 a younger dryas forest decline quercus and expansion of pinewoods xeric scrub and open ground habitats with juniperus artemisia ephedra distachya type centaurea scabiosa type under arid and cold conditions 3 an early holocene forest scrub open ground vegetation mosaic developing under a warm dry and continental climate 4 a maximum of quercus forest and thermomediterranean ever green taxa olea phillyrea pistacia reflecting a warm moist oceanic climate between c 9000 cal bp and c 5000 cal bp and 5 the expansion of shrublands with cistaceae and ericaceae under a drier climatic regime and increasing anthropogenic activity since c 5000 cal bp holocene episodes of maximum cli matic aridity are identified in the record of xerophytic taxa juniperus artemisia ephedra distachya type centred around 10 200 cal bp 7800 cal bp 4800 cal bp 3100 cal bp and 1700 cal bp regional com parisons suggest a correlation of arid phases across southern iberia and northwest africa which can be related to abrupt north atlantic coolings bond events

massive layer of pure anorthosite on the moon 1 we present a new global survey of the purest anorthosite pan rock using the spectral profiler onboard kaguya we found that pan rocks are widely distributed over the moon including the feldspathic highland terrain and the south and north polar regions all pan sites are associated with huge impact structures with diameters larger than 100 km based on the global distributions of pan and olivine rich sites we propose the existence of a massive pan layer with a thickness of 50 km below an uppermost mafic rich mixed layer with a thickness of 10 km below the pan layer a lower crustal layer with olivine rich materials may be present on the nearside but not on the far side of the moon the existence of a pan layer with a thickness of 50 km suggests an al2o3 abundance of 33 to 34 wt in the lunar crust which is higher than previous estimates of 32 wt our data indicate the massive production event of pan during the early stage of the formation of the moon supporting the lunar magma ocean scenario

coastal mudflat accretion under energetic conditions louisiana chenier plain coast usa mudflat accretion on the chenier plain coast of louisiana northern gulf of mexico is anomalous in an area that otherwise experiences widespread land loss due to rapid relative sea level rise accretion is shown to be related to energetic events winter cold fronts and occasional tropical depression storms using a 17 year record of meteorological conditions and aerial surveys the results indicate substantial differences between the behavior of sand and mud dominated coastal systems under energetic conditions comparison of the louisiana chenier plain to other mud rich coasts indicates that certain conditions are necessary for mudflat accretion to occur during energetic atmospheric activity these include an abundant supply of fine grained fluvial sediment and resuspension events that maintain an unconsolidated sea floor dominant onshore wind direction during energetic conditions particularly when onshore winds coincide with high fluvial sediment input to the coastal ocean and a low tidal range

landscape evolution and geodynamic controls in the gulf of cadiz huelva coast sw spain during the late quaternary abstract the coastal evolution of the el abalario area huelva southern spain during the late pleistocene and holocene is reinterpreted after a refinement of the available geochronology by means of optically stimulated luminescence osl dating new data come from the analysis of soft sediment deformation palaeosols geomorphological mapping and published seismic surveys on the onshore and offshore gulf of cadiz the present structure of el abalario dome resulted from the complex interaction of littoral catchment processes and sea level changes upon an emergent coastal plain conditioned by the upwarping of the underlying pliocene pleistocene prograding deltaic sequence upwarping is probably related to escape of over pressurized fluids accompanied by dewatering prior to and during ois oxygen isotopic stage 5 continued upwarping produced the large nw se gravitational fault of torre del loro tlf in the southwestern flank of the dome roughly parallel to the present coastline during ois 5 ois 4 the resulting escarpment favoured the accumulation of aeolian sand dunes units u1 u2 and u3 from ois 5 to early ois 1 unit u1 ois 5 ends upwards in a supersurface with a thick weathering profile that suggests moist and temperate climatic conditions unit u2 accumulated mainly during ois 4 and ois 3 with prevailing w e winds the supersurface between u2 and u3 records a part of ois 2 with relative low sea level sedimentation of unit u3 took place during the last deglaciation radiocarbon and osl ages with prevailing w sw winds under a temperate moist climate that became more arid towards the top holocene a major supersurface with an iron crust like layer ssfe developed during the holocene climatic optimum ois 1 under wetter and more temperate conditions than before fossilizing the tlf the supersurface is covered by younger aeolian dunes u4 u5 u6 and u7 transported by w sw winds since the late neolithic chalcolithic cultural period 5 0 ky cal bp

geochemical variations in estuarine sediments provenance and environmental changes southern spain abstract the geochemical characteristics of the sedimentary infilling in the central basin of the odiel river estuary have allowed the determination of the sediment provenance and the environmental conditions during the last 10 000 years thus sediment provenance can be divided into three stages 1 9060 6500 years bp the estuarine valley materials became the main sediment source because of intense erosion and sedimentation under transgressive conditions 2 6500 3200 years bp the stabilization of the sea level and the current dynamic conditions involved an erosion of the neogene and quaternary formations that acted as sediment sources at approximately 5705 cal year bp a high energy marine event took place suggesting that a tsunami could have affected this area 3 3200 years bp to present the high sedimentation rate of the previous stage and the partial closure of the estuary allowing the acid fluvial discharges from the tinto and odiel to reach the estuary and become the present main source of sediments

compositional diversity at theophilus crater understanding the geological context of mg spinel bearing central peaks 1 analysis of high resolution moon mineralogy mapper m3 data reveals the presence of a prominent mg spinel rich lithology in the central peaks of theophilus crater on the lunar nearside other peak associated lithologies are comprised of plagioclase olivine and pyroxene bearing materials a consistent spatial association of mg spinel with mafic free anorthosite is recognized documentation of theophilus central peaks brings the global inventory of mg spinel rich lithology to two widely separated occurrences namely theophilus on the lunar nearside and moscoviense basin on the farside the theophilus crater target region lies on one of the inner rings of the nectaris basin indicating that the mg spinel bearing lithology source was deep in the lunar crust

recent coastal evolution of the donana national park sw spain abstract since the last holocene sea level rise about 6900 bp a series of depositional littoral landforms has been generated at the outlet of the guadalquivir river with progradation along the predominant longshore drift towards the east the first coastal progradation occurred between 6900 and 4500 bp the donana and perhaps la algaida spits both associated with the oldest and highest marshland in the donana national park are assumed to have been developed at an early stage originally the guadalquivir estuary was wider and deeper than now and its environment was mainly marine the oldest littoral formations have been dated as ca 4735 bp they show erosional events and indicate the breaking up of earlier spit barriers to form inlets the marine environment became increasingly dominant with heavy erosion of cliffs and a retreating coastline this period was followed by another sedimentary cycle 4200 2600 bp that surrounded the earlier eroded barriers the size of the estuary decreased due to the increasing marsh deposits and a fluvial environment was born about 2600 years ago progradation gave way to a new period of intense erosion the resulting morphology of littoral strands and erosional surfaces permitted the return to a marine environment the shoreline again retreated from 2300 bp coastal progradation has prevailed with an erosional interruption at 1000 bp the present day outlet of the guadalquivir is an estuarine delta of inactive marshland the donana national park the dominant environment is fluvial

evolution of the pollution in the piedras river natural site gulf of cadiz southern spain during the holocene the piedras river marshland and el rompido spit bar is a natural site in close proximity to two of the most polluted rivers in the world the tinto and odiel rivers the aim of this study is to determine the degree of contamination of this natural site using a variety of pollution indices at this site the holocene infilling sequence is recorded and applied to a study of the pollution history and the possible impacts of human activity the depositional history of the piedras river estuary during the holocene recorded open marine conditions at ca 6500 calbp when sea level was at its holocene maximum to study the pollution of the estuary during the holocene catchment background geochemistry was established using samples that pre date human activity agriculture and mining additionally the sedimentary environment was reconstructed throughout the holocene comparison of pollution levels is interpreted to be more reliable if the sedimentary environment has remained similar throughout the depositional record results show that despite being located nearby very polluted estuaries the piedras river marshland contains unpolluted sediments mainly because of the small catchment area relative to that of neighbouring more polluted rivers and thus has not been affected by human activity such as mining