large scale responses of complex shaped coastlines to local shoreline stabilization and climate change 1 when modeling the large scale km evolution of coastline morphology the influence of natural forces is not the only consideration ongoing direct human manipulations can substantially drive geomorphic change in this paper we couple a human component to a numerical model of large scale coastline evolution incorporating beach nourishment periodically placing sand on the beach also called beach replenishment or beach fill beach nourishment is the most prevalent means humans employ to alter the natural shoreline system in our case study the carolina coastline beach nourishment can cause shorelines adjacent to those that are nourished to shift both seaward and landward when we further consider how changes to storm behaviors could change wave climates the magnitude of morphological change induced by beach nourishment can rival that expected from sea level rise and affect the coast as far as tens of kilometers away from the nourishment site in some instances nonlocal processes governing large scale cuspate cape coastline evolution may transmit the human morphological signal over surprisingly large hundreds of kilometer distances

high angle wave instability and emergent shoreline shapes 2 wave climate analysis and comparisons to nature 1 recent research has revealed that the plan view evolution of a coast due to gradients in alongshore sediment transport is highly dependant upon the angles at which waves approach the shore giving rise to an instability in shoreline shape that can generate different types of naturally occurring coastal landforms including capes flying spits and alongshore sand waves this instability merely requires that alongshore sediment flux is maximized for a given deepwater wave angle a maximum that occurs between 35 and 50 for several common alongshore sediment transport formulae here we introduce metrics that sum over records of wave data to quantify the long term stability of wave climates and to investigate how wave climates change along a coast for long point a flying spit on the north shore of lake erie canada wave climate metrics suggest that unstable waves have shaped the spit and furthermore that smaller scale alongshore sand waves occur along the spit at the same locations where the wave climate becomes unstable a shoreline aligned along the trend of the carolina capes united states would be dominated by high angle waves numerical simulations driven by a comparable wave climate develop a similarly shaped cuspate coast local wave climates along these simulated capes and the carolina capes show similar trends shoreline reorientation and shadowing from neighboring capes causes most of the coast to experience locally stable wave climates despite regional instability

kimmeridgian palaeogeography and basin evolution of northeastern iberia abstract two sedimentary basins were developed during the kimmeridgian in the northeastern part of iberia the basque cantabrian basin to the northwest and the iberian basin to the east these basins were mainly filled by carbonates deposited in a shallow epicontinental sea that was connected to the open marine realms of both the north atlantic and the western tethys respectively during the late jurassic they were temporarily linked by means of the soria seaway the uppermost oxfordian to lowermost tithonian of northeastern iberia consists of two depositional sequences sequence j3 5 spans latest oxfordian to early late kimmeridgian times sequence j3 6 spans the late kimmeridgian and early tithonian during sequence j3 5 coralgal reefs were developed in the sedimentary domains of the basque cantabrian basin and the soria seaway whereas the marginal areas of the iberian basin were dominated by oolitic shoals with variable siliciclastic influence outer ramp areas located in the central and eastern part of the iberian basin were dominated by carbonate muds and marls during the late kimmeridgian earliest tithonian shallow reefal and oolitic facies prograded over the micritic outer ramp facies the sedimentation areas were reduced and sequence j3 6 was only deposited in the iberian basin most of the western margin of the iberian basin and the southern areas of the soria seaway were covered by reefal facies during this sequence major transgressive events in the iberian basin took place in the latest oxfordian early kimmeridgian and in the middle late kimmeridgian whereas eustatic falls in sea level are recognised at the onset of the late kimmeridgian and at the kimmeridgian tithonian transition these events have also been described in other west european basins synsedimentary extensional tectonics is also evident and has been related to the onset of the late jurassic early cretaceous rifting stage synsedimentary normal faulting resulted in the presence of several troughs and highs within the basin the tectonic uplift of the western basin margin explains the progressive basinwards shift of the shorelines as observed in the iberian basin towards the end of the jurassic

formation of coastline features by large scale instabilities induced by high angle waves along shore sediment transport that is driven by waves is generally assumed to smooth a coastline this assumption is valid for small angles between the wave crest lines and the shore as has been demonstrated in shoreline models but when the angle between the waves and the shoreline is sufficiently large small perturbations to a straight shoreline will grow here we use a numerical model to investigate the implications of this instability mechanism for large scale morphology over long timescales our simulations show growth of coastline perturbations that interact with each other to produce large scale features that resemble various kinds of natural landforms including the capes and cuspate forelands observed along the carolina coast of southeastern north america wind and wave data from this area support our hypothesis that such an instability mechanism could be responsible for the formation of shoreline features at spatial scales up to hundreds of kilometres and temporal scales up to millennia

large scale dynamics of sandy coastlines diffusivity and instability 1 the dynamics of small amplitude perturbations of an otherwise rectilinear coastline due to the wave driven alongshore sediment transport is examined at large time and length scales years and kilometers a linear stability analysis is performed by using an extended one line shoreline model with two main improvements 1 the curvature of the coastline features is accounted for and 2 the coastline features are assumed to extend offshore as a bathymetric perturbation up to a finite distance for high incidence angles instability is found in accordance with ashton et al 2001 however it is seen that instability is inhibited by high waves with long periods and gently sloping shorefaces so that in this case the coastline may be stable for any angle similarly there is no instability if the bathymetric perturbation is confined very close to the coast it is found that the traditional linearized one line model larson et al 1987 tends to overpredict the coastline diffusivity the overprediction is small for the conditions leading to a stable coastline and for moderate incidence angles but can be very dramatic for the conditions favoring instability an interesting finding is that high angle waves instability has a dominant wavelength at the linear regime which is in the order of 4 15 km one to two orders of magnitude larger than the length scale of surf zone rhythmic features intriguingly this is roughly the same range of the wavelength of some observed shoreline sand waves and in particular those observed along the dutch coast a model application to this coast is presented

ice age at the middle late jurassic transition a detailed record of sea surface temperatures in the northern hemisphere based on migration of marine invertebrate fauna ammonites and isotopic thermometry 18o values of shark tooth enamel indicates a severe cooling at the middle late jurassic transition mljt about 160 ma ago the magnitude of refrigeration 1 3 c for lower middle latitudes and its coincidence in time with an abrupt global scale fall of sea level documented through sequence stratigraphy are both suggestive of continental ice formation at this time ice sheets may have developed over the high latitude mountainous regions of far east russia the drastic cooling just post dated the middle late callovian widespread deposition of organic rich marine sediments e g northwestern europe central atlantic and arabian peninsula this thermal deterioration can thus be ascribed to a downdraw in atmospheric co2 via enhanced organic carbon burial which acted as a negative feedback effect i e the inverse greenhouse effect the glacial episode of the mljt climaxed in the late callovian lasted about 2 6 myr and had a pronounced asymmetrical pattern composed of an abrupt 0 8 myr temperature fall opposed to a long term 1 8 myr stepwise recovery the glacial conditions at the mljt reveal that atmospheric co2 levels could have dropped temporarily to values lower than 500 ppmv during mesozoic times

sedimentary evolution of the torrecilla reef complex in response to tectonically forced regression early kimmeridgian northern spain the early kimmeridgian torrecilla reef complex in the northern iberian basin of spain consists of a fringing reef composed of eight accretionary units the first four were deposited along a steep margin they display down lapping and off lapping geometries and are characterised by poor reef framework development large volumes of reworked corals and transported sediment and limited growth of micro encrusters in contrast deposition of the fifth and younger accretionary units occurred on a shallow platform without a pronounced slope where coral reefs grew in a shallow protected environment the main features of these reefs are an absence of reef slope facies a high proportion of preserved framework elements relatively low volumes of intrareef sediment high proportions of terrigenous material and abundant micro encrusters and microbialites these reefs were protected from storm waves by long shore sand bars which also protected a very shallow lagoon during the last stage of sedimentation the early kimmeridgian was a period of rising global sea level a trend apparent across other portions of the iberian basin however geometry and sedimentary evolution of the torrecilla reef complex is consistent with those of off lapping reefs that develop during sea level fall thus we conclude that down stepping geometries and evolution to progressively shallower environments within the torrecilla reef complex occurred as a result of a tectonically forced regression d 2005 elsevier b v all rights reserved

descent and modification of the overflow plume in the denmark strait bulk properties of the denmark strait overflow dso plume observed in velocity and hydrography surveys undertaken in 1997 and 1998 are described despite the presence of considerable short term variability it is found that the pathway and evolution of the plume density anomaly are remarkably steady bottom stress measurements show that the pathway of the plume core matches well with a rate of descent controlled by friction the estimated entrainment rate diagnosed from the rate of plume dilution with distance shows a marked increase in entrainment at approximately 125 km from the sill leading to a net dilution consistent with previous reports of a doubling of overflow transport measured by current meter arrays the entrainment rate increase is likely related to the increased topographic slopes in the region compounded by a decrease in interface stratification as the plume is diluted and enters a denser background

the alpine tethys rifted margins reconciling old and new ideas to understand the stratigraphic architecture of magma poor rifted margins this study focuses on the assessment of the stratigraphic architecture of the proximal and distal jurassic alpine tethys rifted margins the aim of the study was to reconcile the major observations performed in the alps through time with what is observed in present day magma poor rifted margins the proximal and distal rifted margins reflect two evolutionary phases of rifting involving different structures and isostatic evolutions leading to different stratigraphic records the proximal rifted margins formed from upper triassic to pliensbachian times and resulted in the formation of classical half graben basins rift evolution changed drastically during pliensbachian to toarcian times when extension started to localize in the future distal rifted margins low angle detachment faults become the new elementary structure controlling final crustal tapering and eventually mantle exhumation to the sea floor new structural elements controlling the stratigraphic architecture of the distal rifted margins include extensional allochthons and breakaway blocks both resulting from the delamination of a keystone block also referred to as hangingwall block during hyper extension processes to define the stratigraphic architecture of the proximal and distal rifted margins three stratigraphic marker horizons are used namely the top of the pre rift sequences the top of the proximal margin syn tectonic sequence and the base of post rift sequences based on the distribution of these stratigraphic marker horizons across the alpine units and a structural re evaluation of the rift structures a synthetic tectono stratigraphic evolution of the alpine tethys domain is proposed that reconciles old and new ideas about how rift systems may evolve in space and time

middle jurassic early cretaceous tectono sedimentary evolution of the southwestern iberian basin central spain major palaeogeographical changes in the geotectonic framework of the western tethys abstract the middle jurassic early cretaceous tectono sedimentary evolution of the southwestern part of the intraplate iberian basin spain was mostly controlled by the alto tajo montes universales atmu and landete teruel lt faults during the middle jurassic the atmu fault separated a western area dominated by shallow marine carbonates and an eastern area with open marine facies during the bathonian callovian the area located to the west of the atmu fault and north of the lt fault cuenca domain was progressively exposed and remained uplifted until the late barremian a widespread unconformity with a variable gap around the callovian to mid oxfordian has been related to the onset of an earlier synrift stage that includes a lower episode middle oxfordian kimmeridgian of carbonate ramp sedimentation and an upper episode latest kimmeridgian early berriasian with intense fault compartmentalization this fault activity involved the eventual uplift of the teruel javalambre and valencia highs separating the maestrazgo and valencia basins after a berriasian early barremian stratigraphic gap the upper synrift stage late barremian aptian marks the onset of the sedimentation in the cuenca basin west of the atmu and lt faults initial continental sedimentation occurred in small grabens bounded by nne ssw and wnw ese trending faults an early aptian transgressive event overcame the lt fault and connected cuenca and valencia basins successive episodes of stretching in the intracratonic iberian basins were not synchronous as shown by the offset of the distribution of the deformation between the cuenca valencia and maestrazgo basins the synrift sequences recorded in the studied intracratonic basins indicate that most of the accommodation created occurred in response to far field extension after the simultaneous evolution of three main rifts in the north and west iberian margins and in the alpine tethys ocean the heterogeneously distributed stretching indicates that the iberian intraplate realm can be interpreted as a constantly thinned domain in which coeval rift related deformation and rift drift transitions migrated significantly along space and time the comparison and the integration of the obtained results in a broader context make of this work a contribution to the knowledge of the jurassic cretaceous paleogeographic evolution of the iberian plate in the geotectonic evolution of the western tethys

high angle wave instability and emergent shoreline shapes 1 modeling of sand waves flying spits and capes 1 contrary to traditional findings the deepwater angle of wave approach strongly affects plan view coastal evolution giving rise to an antidiffusional high wave angle instability for sufficiently oblique deepwater waves with angles between wave crests and the shoreline trend larger than the value that maximizes alongshore sediment transport 45 a one contour line numerical model shows that a predominance of high angle waves can cause a shoreline to self organize into regular quasiperiodic shapes similar to those found along many natural coasts at scales ranging from kilometers to hundreds of kilometers the numerical model has been updated from a previous version to include a formulation for the widening of an overly thin barrier by the process of barrier overwash which is assumed to maintain a minimum barrier width systematic analysis shows that the wave climate determines the form of coastal response for nearly symmetric wave climates small net alongshore sediment transport cuspate coasts develop that exhibit increasing relative cross shore amplitude and pointier tips as the proportion of high angle waves is increased for asymmetrical wave climates shoreline features migrate in the downdrift direction either as subtle alongshore sand waves or as offshore extending flying spits depending on the proportion of high angle waves numerical analyses further show that the rate that the alongshore scale of model features increases through merging follows a diffusional temporal scale over several orders of magnitude a rate that is insensitive to the proportion of high angle waves the proportion of high angle waves determines the offshore versus alongshore aspect ratio of self organized shoreline undulations

constraints imposed by rift inheritance on the compressional reactivation of a hyperextended margin mapping rift domains in the north iberian margin and in the cantabrian mountains the alpine pyrenean cantabrian orogen developed along the plate boundary between iberia and europe involving the inversion of mesozoic hyperextended basins along the southern biscay margin thus this margin represents a natural laboratory to analyze the control of structural rift inheritance on the compressional reactivation of a continental margin with the aim to identify former rift domains and investigate their role during the subsequent compression we performed a structural analysis of the central and western north iberian margin based on the interpretation of seismic reflection profiles and local constraints from drill hole data seismic interpretations and published seismic velocity models enabled the development of crustal thickness maps that helped to constrain further the offshore and onshore segmentation based on all these constraints we present a rift domain map across the central and western north iberian margin as far as the adjacent western cantabrian mountains furthermore we provide a first order description of the margin segmentation resulting from its polyphase tectonic evolution the most striking result is the presence of a hyperthinned domain e g asturian basin along the central continental platform that is bounded to the north by the le danois high interpreted as a rift related continental block separating two distinctive hyperextended domains from the analysis of the rift domain map and the distribution of reactivation structures we conclude that the landward limit of the necking domain and the hyperextended domains respectively guide and localize the compressional overprint the le danois block acted as a local buttress conditioning the inversion of the asturian basin

depositional model for a prograding oolitic wedge upper jurassic iberian basin abstract facies architecture and bedding patterns of the kimmeridgian pozuel formation iberian basin evidence that this 50 70 m thick oolitic grainstone unit conforms to the infralittoral prograding wedge ilpw model instead of the classic models used for interpreting oolitic grainstones sandbodies on carbonate ramps or platforms i e bank margin shoal complexes beaches and beach ridges ten lithofacies have been distinguished in the pozuel formation 5 10 dipping clinobedded oolitic grainstone foresets passing to tabular oolitic packstones grainstones which interfinger the muddy basinal bottomsets landwards the clinobeds pass into subhorizontal topsets composed of trough cross bedded to structureless oolitic grainstones oolitic skeletal grainstones with stromatoporoids and coral stromatoporoid microbial mounds siliciclastic lithofacies and oncolitic peloidal packstones occur at the innermost position these lithofacies stack in strike elongated 5 20 m thick 0 5 2 km dip oriented wide aggradational progradational packages with complex sigmoid oblique geometries lithofacies depositional geometries and stacking pattern permit to summarize the main characteristic of such upper jurassic oolitic infralittoral prograding wedge potentially to be applied in other oolitic sandbodies both in outcrops and subsurface 1 sediment production within the wave action zone 2 grainstone dominated textures 3 prograding basinward onto basinal muds 4 laterally strike extensive paralleling the shoreline 5 variable thickness commonly of few tens of meters 6 broadly sigmoidal to oblique internal architecture with topsets foresets and bottomsets 7 dip of foresets close to the angle of repose 8 topsets deposited in shallow water extending through the shoreface from the shoreline down to the wave base 9 mounds either microbial or skeletal may occur in the topsets the coated grains factory was along the high energy wave dominated outer platform topset beds from where the mud was winnowed and the grains transported both landward to the platform interior and seaward to the platform edge from were the grains cascaded down the slopes as grain flows and mass flows forming clinobeds this genetic model can be applied to other grain dominated lithosomes some of them forming hydrocarbon reservoirs e g the jurassic hanifa formation and some arab d e g qatif field in arabia the smackover formation in northern louisiana and south arkansas the aptian shuaiba formation e g bu hasa field and the cenomanian mishrif formation e g umm adalkh field of the arabian gulf

spatial and temporal evolution of hyperextended rift systems implication for the nature kinematics and timing of the iberian european plate boundary we focus on the iberian european plate boundary iepb whose nature age and evolution are strongly debated in contrast to previous interpretations of the iepb as a major lithospheric scale left lateral strike slip fault we propose a more complex deformation history the mapping of rift domains at the transition between iberia and europe emphasizes the existence of spatially disconnected rift systems based on their restoration we suggest that the deformation was partitioned between a set of distinct left lateral transtensional rift systems from the late jurassic to early cretaceous a plate kinematic reorganization at aptian albian time resulted in the onset of sea floor spreading in the western bay of biscay and extreme crustal and lithosphere thinning in intra continental rift basins to the east the formation and reactivation of the iepb is interpreted as the result of the polyphase evolution of a diffuse transient plate boundary that failed to localize the results of this work may provide new insights on 1 processes preceding breakup and the initiation of segmented and strongly oblique shear margins 2 the deformation history of nascent divergent plate boundaries and 3 the kinematics of the southern north atlantic and alpine domain in western europe

diachronous evolution of late jurassic cretaceous continental rifting in the northeast atlantic west iberian margin 1 regional 2 d seismic reflection profiles outcrop and borehole data are used to characterize the evolution of deep offshore sedimentary basins in southwest iberia alentejo basin the interpreted data indicate the bulk of late jurassic earliest cretaceous subsidence occurred in the present day continental slope area as shown by 1 significant thickening of synrift strata basinward from a slope bounding fault system sfs west of which the total thickness of sediment can reach more than 9 0 km and 2 relatively thin mesozoic strata east of the sfs where thickening of synrift units against principal faults is limited five principal regressive events and their basal unconformities reflect tectonic uplift and relative emersion in proximal basins which were located on the rift shoulder to subsiding tilt blocks west of the sfs these regressive events are correlated with major rift related events occurring on the deeper margin direct comparisons with the peniche basin of northwest iberia reveal that significant portions of the iberian lower plate margin were uplifted and eroded during the last stages of continental rifting this process was repeated at different times and in different areas as the locus of rifting and continental breakup migrated northward as a result two distinct rift axes are recognized in west iberia a first axis extending from the porto basin to the alentejo basin and a second axis located on the outer proximal margin north of 38 30n in addition the sfs delimited 1 prograding deposits of cretaceous paleogene age and 2 late cenozoic deposits draping the modern continental slope these latter facts demonstrate that on lower plate passive margins the relative position of the continental slope is established during the final rifting episode s preceding continental breakup

facies and depositional sequence evolution controlled by high frequency sea level changes in a shallow water carbonate ramp late kimmeridgian ne spain the outcrops of the sierra de albarracin ne spain allow a precise reconstruction of the shallow sedimentary domains of a late kimmeridgian carbonate ramp developed in western marginal areas of the iberian basin the sedimentary record shows a hierarchical sequence stratigraphic organization which implies sea level changes of different frequencies the studied succession is arranged in a long term transgressive regressive sequence which is likely to reflect local variation in the subsidence rates this sequence includes four higher order sequences a to d which have variable thickness from 3 to 21 m the similar sedimentary evolution observed in distant localities suggests the existence of high frequency sea level fluctuations controlling the sequence development the average amplitude of these cycles would range from 5 to 10 m the precise estimation of their duration some few hundreds of kyr and their possible assignment to any of the long term orbital cycles the 100 or the 400 kyr eccentricity cycles is uncertain sequences a and b formed during the long term transgressive interval are relatively thin from 3 to 9 m give up sequences that were never subaerially exposed these sequences are locally formed by five shallowing upward elementary sequences sequences c and d are catch down sequences with evidence of emersion of subtidal facies sequence c formed during the stage of maximum gain of long term accommodation is the thickest sequence from 13 to 21 m and includes coral microbial reefs pinnacles up to 16 m in height the increased production rates were able to fill part of the accommodation created during the early stage of high frequency sea level rise and the shallow platform was eventually exposed to subaereal erosion and meteoric cementation

oblique strain partitioning and transpression on an inverted rift the castilian branch of the iberian chain the iberian chain is a wide intraplate deformation zone formed by the tectonic inversion during the pyrenean orogeny of a permian mesozoic basin developed in the eastern part of the iberian massif the n s convergence between iberia and eurasia from the late cretaceous to the lower miocene times produced significant intraplate deformation the nw se oriented castilian branch of the iberian chain can be considered as a key zone where the proposed models for the cenozoic tectonic evolution of the iberian chain can be tested structural style of basin inversion suggests mainly strike slip displacements along previous nw se normal faults developed mostly during the mesozoic to confirm this hypothesis structural and basin evolution analysis macrostructural bouguer gravity anomaly analysis detailed mapping and paleostress inversions have been used to prove the important role of strike slip deformation in addition we demonstrate that two main folding trends almost perpendicular ne sw to e w and nw se were simultaneously active in a wide transpressive zone the two fold trends were generated by different mechanical behaviour including buckling and bending under constrictive strain conditions we propose that strain partitioning occurred with oblique compression and transpression during the cenozoic 2008 elsevier b v all rights reserved

a comparison of the age and composition of the shelburne dyke nova scotia and the messejana dyke spain new 40ar 39ar age determinations on biotite from the shelburne dyke of nova scotia and from the messejana dyke of spain are identical at 203 2 ma in addition both dykes have similar chemical compositions and probably represent similar magma sources petrogenetic processes and tectonic settings related to an early phase of opening of the north atlantic ocean

transgressive regressive cycles and jurassic palaeogeography of northeast iberia abstract a correlation and sequence stratigraphy study of jurassic successions has been carried out in the main sedimentary basins of northeast iberia i e asturias basque cantabrian and iberian basins based on the identification of transgressive regressive cycles the development and palaeogeographic evolution of the epicontinental carbonate platforms of northeast iberia were largely controlled by major tectonic activity at three main intervals at the beginning of the jurassic in the lower middle jurassic transition and during the uppermost jurassic respectively during early jurassic times northeast iberia was the site of a single and large carbonate ramp opened to the north this carbonate ramp suffered a progressive drowning evolving from an inner to hemipelagic ramp systems with the local development of suboxic environments in the deepest areas located to the north during the middle jurassic different open carbonate platforms were formed including the development of swells in intermediate areas during the upper jurassic the outer ramp areas were progressively moving to the east iberian basin and the ammonite faunas showing a markedly tethyan affinity thereafter three first order t r cycles bounded by major discontinuities associated with significant time gaps are identified they extend respectively from the latest rhaetian to the early aalenian from the middle aalenian to the early oxfordian and from the early oxfordian to the late berriasian major transgressive peaks occurred at the middle toarcian bifrons zone at the late bajocian upper niortense and garantiana zones and at the mid kimmeridgian divisum zone each of the first order cycles includes four second order t r cycles cycles 1 1 1 4 are identified in the northern basins cycles 2 1 2 4 display some differences in age of transgressive peaks from one basin to another cycles 3 1 3 4 are mainly identified in the iberian basin the correlation with other separated boreal and thethysian basins demonstrates that the number and age of t r cycles varies from one basin to another and are mainly controlled by the local or regional tectonic development the transgressive peaks may reflect episodes of eustatic rise during the jurassic however their different age from one basin to another is explained by different subsidence evolution

compressive episodes and faunal isolation during rifting southwest iberia abstract evidence for three short lived compressive episodes of late carixian late callovian early oxfordian and tithonian berriasian ages that lasted 5 m yr and occurred during the process of rifting of the algarve basin is presented these tectonic inversion episodes are described at outcrop and cartographic scales and have been dated with the accuracy provided by the ammonoid scale an uplift event of late toarcian aalenian age of undetermined tectonic origin is also described we show that these four tectonic episodes coincide in time with important ecological events such as the onset of migration and or the segregation of boreal and tethyan ammonite species and the confinement of the algarve basin stratigraphic and paleoecological data from the algarve and lusitanian basins are compared and discussed together with eustatic and tectonic information we propose that the tectonic inversion episodes that caused uplift are the origin of the mesozoic sedimentary gaps and the intermittent opening and

facies architecture of a microbial siliceous sponge dominated carbonate platform the bajocian of moscardon middle jurassic spain extensive facies analysis of the outcrops located near moscardon iberian basin ne spain resultedin a precise reconstruction of thefacies architecture of a bajocian middlejurassic carbonate platform different types of microbialites occurred in the transitional area between the shallow and relatively deep carbonate platform domains located above and below wave base level respectively the most significant volume of the micorbialites is found in the platform slope located below wave base level in a depth range of around 30 50 m in the lower slope during stages of rapid accommodation gain the vertical aggradation of individual stratiform build ing blocks results in the formation of up to 25 m thick microbial siliceous sponge buildups during stages of sea level highstand the individual building blocks are dominated by lateral down slope progradational accretion resulting in flatter lens shaped buildups the transition between the upper slope and the shallow platform area is characterized by microbial encrusted intraclastic bioclastic packstones microbial crust development helped to stabilize the seafloor allowing the eventual accumulation and preservation of the sand sized grains above wave base organicbuildupswithvariableproportionsofmicro bialites grew in shallow to relatively deep domains of the jurassic carbonate platforms that developed

origin of the permian triassic iberian basin central eastern spain abstract the iberian basin was an intracratonic rift basin in central eastern spain developed since early permian times the basin boundary faults were normal listric faults controlling an asymmetric extension propagating northeast with time hercynian or older lineaments controlled the orientation of the iberian basin and extension was accommodated basically in the hanging wall block by the formation of secondary grabens and a central high the basin was related with the coeval ebro catalan and cuenca mancha basins and their connections are discussed subsidence curves show that the early permian early jurassic period of extension can be subdivided into three rifting episodes and a flexural one extension factor increases from 1 17 in the northwest to 1 29 near the mediterranean coast the increasing extension rate was accommodated by transfer faults trending nne ssw more important in the levante area the rift evolution is intermittent and seems to reflect distinct stress fields the collapse of the late hercynian orogen and related increased heat flux extension and rifting is the most probable origin of the iberian basin and related basins the origin of the catalan and the valencia prebetic basins is related to the southwards migration of the hesse burgundy rift along the eastern margin of the iberian microplate

coastline responses to changing storm patterns 1 researchers and coastal managers are pondering how accelerated sea level rise and possibly intensified storms will affect shorelines these issues are most often investigated in a cross shore profile framework fostering the implicit assumption that coastline responses will be approximately uniform in the alongshore direction however experiments with a recently developed numerical model of coastline change on a large spatial domain suggest that the shoreline responses to climate change could be highly variable as storm and wave climates change large scale coastline shapes are likely to shift causing areas of greatly accelerated coastal erosion to alternate with areas of considerable shoreline accretion on complex shaped coastlines including cuspate cape and spit coastlines the alongshore variation in shoreline retreat rates could be an order of magnitude higher than the baseline retreat rate expected from sea level rise alone

extension and inversion structures in the tethys atlantic linkage zone algarve basin portugal the algarve basin is a meso cenozoic sedimentary basin overlying carboniferous basement located in the southwestern margin of the iberian peninsula its structure reveals a protracted tectonic history comprising various pulses of mesozoic extension followed by cenozoic compression this work deals with the structure along the northern margin where the mesozoic extensional structures and cenozoic inversion structures crop out the strike of the extensional structures ranges from e w to n s as controlled by a shift from tethyan dominated extension in the east to atlantic dominated extension in the west contractional structures are inverted extensional structures following their same trends it is argued that the thickness of the hettangian evaporite layer exerts a strong control on the structural style throughout the basin during the extensional and inversion episodes the basin is affected by thick skinned deformation along the northern margin where salt is thin or absent basement involved fault systems and short cut structures basinward as the hettangian salt thickens the margin is affected by thin skinned deformation with listric and down to the basin growth faults diapirism and salt cored detachment folds the aim was to discuss the key tectonic features the relevance of salt and understand the nature timing and significance of all these structures in the regional tectonic evolution

jurassic coastal park a great diversity of palaeoenvironments for the dinosaurs of the villar del arzobispo formation teruel eastern spain abstract the villar del arzobispo formation cropping out in the western penagolosa sub basin late jurassic eastern spain includes abundant dinosaur tracksites and bones which occur in diverse mixed siliciclastic and carbonate facies deposited from shallow marine to coastal and alluvial paleoenvironments the lower part of the unit mainly composed of bioclastic and oolitic limestone was deposited in an inner carbonate platform which underwent episodic subaerial exposure and siliciclastic inputs from the emergent areas and includes scarce dinosaur tracks this environment evolved into a siliciclastic coastal and alluvial plain that was crossed by channels and affected by periodic flooding events producing the deposition of splay lobes upward the siliciclastic coastal and alluvial deposits are interbedded with inter to supratidal limestone beds these tidal and coastal deposits show the highest abundance diversity and best preservation of dinosaur tracks and bones of the unit this setting gradually evolved upward into an inner carbonate platform producing the deposition of shallow marine bioclastic and oolitic limestone which includes very scarce dinosaur tracks the highest abundance diversity and best preservation of theropod sauropod thyreophoran and ornithopod tracks occur at the top of tidal carbonate beds tracks also occur in the siliciclastic coastal and alluvial plain deposits especially in the flood plain deposits preserved mainly as infillings or natural casts additionally very scarce and poorly preserved tracks occur at the top of shallow marine carbonate beds bones may be articulated and or associated in the flood plain deposits whereas they are isolated and dispersed in the splay lobe deposits although this unit has been previously assigned to the tithonian berriasian the analysis of larger benthic foraminifera suggests a kimmeridgian tithonian age for the villar del arzobispo formation this is consistent with the dinosaur assemblages present in the unit which are strongly related to other european late jurassic faunas

influence of nearshore sediment dynamics on the distribution of heavy mineral placer deposits in sri lanka beach sediments in sri lanka contain industrial grade heavy mineral occurrences samples of both offshore and onshore sediments were collected to examine the provenance mineralogy and geochemical compositions of the heavy mineral occurrences coastal morphodynamic changes along the coastline of sri lanka were analyzed using the time series satellite images these coastal morphodynamic changes were used to identify the prominent directions of monsoon influenced longshore currents coastal sediment accretion and depositional trends and their relationships to the provenance of the heavy minerals results show the concentrations of detrital ilmenite zircon garnet monazite and rutile vary in the onshore and offshore sediments the heavy mineral potential of the northeastern coast is high average contents of about 45 50 in the verugal deposit 70 85 in the pulmoddai deposit and 3 5 5 0 in offshore samples stretching from nilaveli to kokkilai compared to sediments in southwest average content about 10 in onshore sediments and 2 in offshore sediments from the mouth of the gin river therefore no economic grade heavy mineral placers were identified in the offshore environments the high concentrations of heavy minerals in beach sediments and low concentrations in offshore sediments suggest operation of a panning system in the surf zone to form enriched placer deposits major and trace element compositions of beach sediments show marked enrichments of tio2 fe2o3 la ce zr cr nb th and v compared to average upper continental crust ucc values analysis of prominent coastal longshore transport patterns identifies bidirectional sediment transport in the northeast coast of sri lanka in the southwestern coast two transport directions occur with anti clockwise transport from galle to hambantota and clockwise transport from hikkaduwa to wadduwa the heavy minerals in the placers were mainly derived from precambrian metamorphic rocks and transported to the coast through the river systems of sri lanka

mesozoic extensional tectonics stratigraphy and crustal evolution during the alpine cycle of the eastern iberian basin abstract sequence stratigraphy subsidence analysis and the integration of the basin fill data allow to the identification of four successive evolutionary stages in the basins of the eastern iberian margin during mesozoic extension 1 triassic rift late permian hettangian 2 early and middle jurassic postrift sinemurian oxfordian 3 late jurassic and early cretaceous rift kimmeridgian middle albian and 4 late cretaceous postrift late albian maastrichtian the present day crustal structure of the eastern iberian range and evidence of its evolution are deduced from the analysis of a new gravity map and other geophysical data a regional gravity low along the iberian range is interpreted in terms of crustal thickening beneath the orogen as a result of the collision between the ebro block and the iberian plate during the paleogene the boundary between these blocks coincides with a magnetic lineament that is interpreted as an inherited signature of the thinning that occurred during mesozoic extension a geodynamic scenario for the crustal evolution of the eastern part of the iberian peninsula based on the evaluation of mesozoic extensional tectonics and an analysis of the available geophysical data includes three main successive evolutionary stages 1 1 mesozoic crustal thinning 2 2 paleogene crustal thickening 3 3 neogene crustal thinning based on new geological and geophysical arguments this study offers an alternative and a more complete geodynamic history of the eastern iberian basins related to the evolution of the iberian plate and the central north atlantic

topographic control of oceanic flows in deep passages and straits saddle points between neighboring deep ocean basins are the sites of unidirectional flow from one basin to the next depending on the source of bottom water flow in these sites appears to be topographically controlled so the interface between the bottom water and the water above adjusts itself to permit bottom water flow from the basin that contains a source of bottom water into the next examples in the atlantic include flow in the romanche fracture zone the vema channel the ceara abyssal plain the anegada jungfern passage and the discovery gap but there are many more theoretical predictions of volume flux using a method that requires only conductivity temperature depth data archives and detailed knowledge of bathymetry near the saddle point are compared with volume flux estimates using current meters and or geostrophic estimates for seven cases the ratio of prediction to volume flux estimate ranges from 1 0 to 2 7 some ocean straits that separate adjacent seas are also found to critically control bidirectional flows between basins theory of the influence of rotation on such critical flows is reviewed predictions of volume flux in eight cases are compared with ocean estimates of volume flux from traditional methods

a phase of transient subsidence sediment bypass and deposition of regressive transgressive cycles during the breakup of iberia and newfoundland abstract seismic outcrop and well data from west iberia and newfoundland are used to investigate sediment stacking patterns during continental breakup as a function of tectonic subsidence in west iberia two breakup sequences are revealed on seismic data by marked strata offlap oceanwards from the present day continental shelf this character is similar to newfoundland where correlative strata comprise lower cretaceous cenomanian coarse grained siliciclastics accumulated around local sediment source areas the interpreted data reveal that the two breakup sequences 1 materialise sediment bypass onto continental slope depocentres that experienced important tectonic subsidence during continental breakup but without showing typical syn rift growth packages 2 generate specific forced regressive stratigraphic intervals that relate to uplift and exhumation of the proximal margin subsidence and sediment stacking patterns in both west iberia and newfoundland reflect similar continental breakup processes as they evolved from the upper lithosphere to their mantle breakup stages on both margins coarse grained siliciclastic units on the proximal margin give rise to thick shaley successions in deep water basins this work also confirms that in a setting dominated by a significant sediment influx yet lacking the burial rates of continental slope basins in newfoundland west iberia comprised accommodation driven basins during continental breakup not necessarily sediment starved as a corollary of our analysis we classify breakup sequences around the world based on the characteristic lithologies of their regressive transgressive depositional cycles

tectonic history of the western tethys since the late triassic the tectonic history of the western tethys since the late triassic is illustrated through a set of computer generated plate reconstructions which are based on a rigorous plate motions model of this region the model is constrained by the atlantic plate kinematics and on land geologic evidence and defines 13 tectonic phases spanning the time interval from the late ladinian 230 ma to the present the kinematics associated with the late triassic western tethyan rifts produced the detachment of a large composite fragment from the northern margin of gondwana it can be considered as the eastern propagation of the central pangea breakup during the early jurassic these rift zones became inactive while new zones of extension formed along the southern margin of eurasia the eastern margin of iberia and within the rifted northern gondwana fragment itself plate motions associated with the first two extensional centers can still be considered as an eastern branch of the central atlantic plate kinematics conversely the kinematic parameters of the latter rift result from the composition of the euler rotation describing the central pangea breakup and the euler pole of closure of the paleo tethys ocean the late triassic early jurassic rifting phases determined the formation of a number of independent microplates at the interface between africa and eurasia starting from the early cretaceous convergence between africa and eurasia triggered further deformation within the dispersed continental fragments and the formation of backarc basins at the active margins ultimately leading to an increase in the number of tectonic elements that were moving independently in the western tethyan region during the late cretaceous and the cenozoic the proposed tectonic evolution of the western tethys area is compatible with both global scale plate kinematics and geological constraints from on land data observed across the present day mosaic of displaced terranes surrounding the mediterranean region

cretaceous slab break off in the pyrenees iberian plate kinematics in paleomagnetic and mantle reference frames the pyrenees at the iberia europe collision zone contain sediments showing albian cenomanian high temperature metamorphism and coeval alkaline magmatic rocks stemming from different views on jurassic cretaceous iberian microplate kinematics two schools of thought exist on the trigger of this thermal pulse one invoking hyperextension of the iberian and eurasian margins the other suggesting slab break off competing scenarios for mesozoic iberian motion compatible with pyrenean geology comprise 1 transtensional eastward motion of iberia versus eurasia or 2 strike slip motion followed by orthogonal extension both favoring hyperextension related heating and 3 scissor style opening of the bay of biscay coupled with subduction in the pyrenean realm favoring the slab break off hypothesis we test these kinematic scenarios for iberia against a newly compiled paleomagnetic dataset and conclude that the scissor type scenario is the only one consistent with a well defined 35 counterclockwise rotation of iberia during the early aptian we proceed to show that when taking absolute plate motions into account aptian oceanic subduction in the pyrenees followed by late aptian early albian slab break off should leave a slab remnant in the present day mid mantle below nw africa mantle tomography shows the reggane anomaly that matches the predicted position and dimension of such a slab remnant between 1900 and 1500 km depth below southern algeria mantle tomography is therefore consistent with the scissor type opening of the bay of biscay coupled with subduction in the pyrenean realm slab break off may thus explain high temperature metamorphism and alkaline magmatism during the albian cenomanian in the pyrenees whereas hyperextension that exhumed pyrenean mantle bodies occurred much earlier in the jurassic

complexities in barrier island response to sea level rise insights from numerical model experiments north carolina outer banks using a morphological behavior model to conduct sensitivity experiments weinvestigate the sea level rise response of a complex coastal environment to changes ina variety of factors experiments reveal that substrate composition followed in rankorder by substrate slope sea level rise rate and sediment supply rate are the mostimportant factors in determining barrier island response to sea level rise we find thatgeomorphic threshold crossing defined as a change in state e g from landward migratingto drowning that is irreversible over decadal to millennial time scales is most likely tooccur in muddy coastal systems where the combination of substrate composition depth dependent limitations on shoreface response rates and substrate erodibility mayprevent sand from being liberated rapidly enough or in sufficient quantity to maintain asubaerial barrier analyses indicate that factors affecting sediment availability such aslow substrate sand proportions and high sediment loss rates cause a barrier to migratelandward along a trajectory having a lower slope than average barrier island slope therebydefining an effective barrier island slope other factors being equal such barrierswill tend to be smaller and associated with a more deeply incised shoreface therebyrequiring less migration per sea level rise increment to liberate sufficient sand to maintainsubaerial exposure than larger less incised barriers as a result the evolution of larger lessincised barriers is more likely to be limited by shoreface erosion rates or substrateerodibility making them more prone to disintegration related to increasing sea level riserates than smaller more incised barriers thus the small deeply incised north carolinabarriers are likely to persist in the near term although their long term fate is less certainbecause of the low substrate slopes that will soon be encountered in aggregate results point to the importance of system history e g previous slopes sediment budgets etc in determining migration trajectories and therefore how a barrier island will respondto sea level rise although simple analytical calculations may predict barrier responsein simplified coastal environments e g constant slope constant sea level rise rate etc our model experiments demonstrate that morphological behavior modeling is necessary toprovide critical insights regarding changes that may occur in environments havingcomplex geometries especially when multiple parameters change simultaneously

high frequency variability in the circulation and hydrography of the denmark strait overflow from a high resolution numerical model abstractinitial results are presented from a yearlong high resolution 2 km numerical simulation covering the east greenland shelf and the iceland and irminger seas the model hydrography and circulation in the vicinity of denmark strait show good agreement with available observational datasets this study focuses on the variability of the denmark strait overflow dso by detecting and characterizing boluses and pulses which are the two dominant mesoscale features in the strait the authors estimate that the yearly mean southward volume flux of the dso is about 30 greater in the presence of boluses and pulses on average boluses pulses are 57 1 27 5 h long occur every 3 2 5 5 days and are more frequent during the summer winter boluses pulses increase decrease the overflow cross sectional area and temperatures around the overflow interface are colder warmer by about 2 6 c 1 8 c the lateral extent of the boluses is much greater than that of the pulses in both cases the along stra

recent acceleration in coastal cliff retreat rates on the south coast of great britain rising sea levels and increased storminess are expected to accelerate the erosion of soft cliff coastlines threatening coastal infrastructure and livelihoods to develop predictive models of future coastal change we need fundamentally to know how rapidly coasts have been eroding in the past and to understand the driving mechanisms of coastal change direct observations of cliff retreat rarely extend beyond 150 y during which humans have significantly modified the coastal system cliff retreat rates are unknown in prior centuries and millennia in this study we derived retreat rates of chalk cliffs on the south coast of great britain over millennial time scales by coupling high precision cosmogenic radionuclide geochronology and rigorous numerical modeling measured 10be concentrations on rocky coastal platforms were compared with simulations of coastal evolution using a monte carlo approach to determine the most likely history of cliff retreat the 10be concentrations are consistent with retreat rates of chalk cliffs that were relatively slow 2 6 cm y 1 until a few hundred years ago historical observations reveal that retreat rates have subsequently accelerated by an order of magnitude 22 32 cm y 1 we suggest that acceleration is the result of thinning of cliff front beaches exacerbated by regional storminess and anthropogenic modification of the coast

an evolving research agenda for human coastal systems within the broad discourses of environmental change sustainability science and anthropogenic earth surface systems a focused body of work involves the coupled economic and physical dynamics of developed shorelines rapid rates of change in coastal environments from wetlands and deltas to inlets and dune systems help researchers recognize observe and investigate coupling in natural non human morphodynamics and biomorphodynamics this same intrinsic quality of fast paced change also makes developed coastal zones exemplars of observable coupling between physical processes and human activities in many coastal communities beach erosion is a natural hazard with economic costs that coastal management counters through a variety of mitigation strategies including beach replenishment groynes revetments and seawalls as cycles of erosion and mitigation iterate coastline change and economically driven interventions become mutually linked emergent dynamics of two way economic physical coupling is a recent research discovery having established a strong theoretical basis research into coupled human coastal systems has passed its early proof of concept phase this paper frames three major challenges that need resolving in order to advance theoretical and empirical treatments of human coastal systems 1 codifying salient individual and social behaviors of decision making in ways that capture societal actions across a range of scales thus engaging economics social science and policy disciplines 2 quantifying anthropogenic effects on alongshore and cross shore sediment pathways and long term landscape evolution in coastal zones through time including direct measurement of cumulative changes to sediment cells resulting from coastal development and management practices e g construction of buildings and artificial dunes bulldozer removal of overwash after major storms and 3 reciprocal knowledge and data exchange between researchers in coastal morphodynamics and practitioners of coastal management future research into human coastal systems can benefit from decades of interdisciplinary work on the complex dynamics of common pool resources from computational efficiency and new techniques in numerical modeling and from the growing catalog of high resolution geospatial data for natural and developed coastlines around the world

facies heterogeneity at interwell scale in a carbonate ramp upper jurassic ne spain abstract the well exposed upper kimmeridgian carbonate ramp near arroyo cerezo iberian basin eastern spain provides an excellent analog to stratigraphically equivalent subsurface reservoirs such as the carbonate ramps of the arab d of the middle east and the smackover of the gulf of mexico critical questions regarding interwell scale heterogeneity and correlation motifs for low angle ramp systems can be addressed using continuous exposures that encompass a full range of inner to outer ramp facies outcrops in this area provide a complete exposure of the ramp succession in depositional dip direction at arroyo cerezo a 40 m thick and 1 3 km long dip oriented continuous outcrop has been studied lithofacies and bounding surfaces have been mapped on a continuous photomosaic to build a detailed 2d cross section complemented by five stratigraphic sections 300 m apart and petrographic analysis the reconstructed section shows the facies transition from relative proximal to distal carbonate ramp settings carbonate facies associations are grouped according to the dominant carbonate types buildup dominated systems and coated grain dominated systems detailed mapping of facies and bounding surfaces documents distinct ramp depositional units with downdip facies changes occurring within the 1 3 km length of the outcrop the arroyo cerezo outcrop indicates that the ramp facies continuity when based on a 5 10 km distance well log correlation is mostly apparent use of detailed spatial and temporal analysis of high quality outcrop analogs promotes more realistic models for understanding the interwell meter scale heterogeneity and the scale of these depositional heterogeneities although being below resolution of subsurface tools governs in fact along with diagenetic modifications the fluid flows within a reservoir the scale of these stratigraphic heterogeneities needs to be considered in order to optimize and enhance hydrocarbon production and last recovery

margin segmentation prior to continental break up a seismic stratigraphic record of multiphased rifting in the north atlantic southwest iberia a dense grid of multichannel 2d seismic profiles tied to borehole dredge and outcrop data are used to analyze the multiphased rifting structural architecture and rift locus migration across the southwest iberian margin in the study area three distinct sectors show different structural evolutions from the late triassic to the late jurassic earliest cretaceous the three structural sectors are distinguished by 1 the presence of incipient tilt blocks on the inner proximal margin which denotes limited syn rift subsidence 2 developed tilt blocks on the outer proximal margin 3 evidence of significant fault related subsidence on the outer proximal margin during the middle jurassic followed by an oxfordian tithonian berriasian rift phase leading to seafloor spreading and 4 marked crustal stretching on the distal margin where highly rotated tilt blocks overlain by thick late triassic to late jurassic units are observed this work demonstrates that significant subsidence occurred in southwest iberia several millions of years prior to the latest jurassic earliest cretaceous extensional episode leading to continental breakup the magnitude of early subsidence episodes approaches that of the last subsidence pulse preceding continental breakup across the southwest iberian margin the observed structural sectors differ from each other in terms of the age of rift climax of syn rift strata we interpret the multiple extensional pulses recorded in southwest iberia as resulting not only from continental rifting between iberia and newfoundland but also between nova scotia and morocco thus it is considered that pre breakup units in the deep offshore basins of iberia comprise multiple rift related sequences whose distribution and relative thickness depends on local subsidence rates on the diachronous northward migration of rifting and on the relative crustal stretching experienced by individual sub basins

modeling large scale shoreline sand waves under oblique wave incidence waves develop with wavelengths between 2 and 5 km they migrate downdrift at about 0 5 km yr and they reach amplitudes up to 120 m within 13 years larger wave obliquity higher waves and shorter wave periods strengthen the shoreline instability cross shore transport is essential for the instability and faster cross shore dynamics leads to a faster growth of the sand waves simulations with variable wave incidence angles alternating between 60 and 30 show that a large proportion of high angle waves is required for spontaneous sand wave formation at least 80 insight is provided into the physical mechanism behind high angle wave instability and the occurrence of a optimal length scale for sand wave growth the generic model results are consistent with existing observations of shoreline sand waves in particular with those along the southwest coast of africa

temporal and spatial variations in tectonic subsidence in the iberian basin eastern spain inferences from automated forward modelling of high resolution stratigraphy permian mesozoic by subsidence analysis on eighteen surface sections and 6 wells which cover large part of the iberian basin e spain and which are marked by high resolution stratigraphy of the permian triassic jurassic and cretaceous we quantify the complex permian and mesozoic tectonic subsidence history of the basin backstripping analysis of the available high resolution and high surface density of the database allows to quantify spatial and temporal patterns of tectonically driven subsidence to a much higher degree than previous studies the sections and wells have also been forward modelled with a new automated modelling technique with unlimited number of stretching phases in order to quantify variations in timing and magnitude of rifting it is demonstrated that the tectonic subsidence history in the iberian basin is characterized by pulsating periods of stretching intermitted by periods of relative tectonic quiescence and thermal subsidence the number of stretching phases appears to be much larger than found by earlier studies showing a close match with stretching phases found in other parts of the iberian peninsula and allowing a clear correlation with discrete phases in the opening of the tethys and atlantic

atlantic water variability on the se greenland continental shelf and its relationship to sst and bathymetry 1 interaction of warm atlantic origin water aw and colder polar origin water pw advecting southward in the east greenland current egc influences the heat content of water entering greenland s outlet glacial fjords here we use depth and temperature data derived from deep diving seals to map out water mass variability across the continental shelf and to augment existing bathymetric products we compare depths derived from the seal dives with the ibcao version 3 bathymetric database over the shelf and find differences up to 300 m near several large submarine canyons in the vertical temperature structure we find two dominant modes a cold mode with the typical aw pw layering observed in the egc and a warm mode where aw is present throughout the water column the prevalence of these modes varies seasonally and spatially across the continental shelf implying distinct aw pathways in addition we find that satellite sea surface temperatures sst correlate significantly with temperatures in the upper 50 m r 0 54 but this correlation decreases with depth r 0 22 at 200 m and becomes insignificant below 250 m thus care must be taken in using sst as a proxy for heat content as aw mainly resides in these deeper layers sample unit level copyright

modes and emergent time scales of embayed beach dynamics in this study we use a simple numerical model the coastline evolution model to explore alongshore transport driven shoreline dynamics within generalized embayed beaches neglecting cross shore effects using principal component analysis pca we identify two primary orthogonal modes of shoreline behavior that describe shoreline variation about its unchanging mean position the rotation mode which has been previously identified and describes changes in the mean shoreline orientation and a newly identified breathing mode which represents changes in shoreline curvature wavelet analysis of the pca mode time series reveals characteristic time scales of these modes typically years to decades that emerge within even a statistically constant white noise wave climate without changes in external forcing suggesting that these time scales can arise from internal system dynamics the time scales of both modes increase linearly with shoreface depth suggesting that the embayed beach sediment transport dynamics exhibit a diffusive scaling

high frequency fluctuations in denmark strait transport 1 denmark strait ocean current transport exhibits quasi regular fluctuations immediately south of the sill with periods of 2 4 days the transport variability is similar to the mean transport itself using a circulation model we explore prospects to monitor the fluctuations the model has realistic transport and shows water leaving denmark strait in equivalent barotropic cyclones that are nearly geostrophic and correlate with sea surface height ssh existing satellite altimeter observations of ssh have adequate space time sampling to reconstruct the transport fluctuations using a regression developed from the model results but measurement error overwhelms the signal from the model results the pending surface water and ocean topography swot wide swath altimeter appears accurate enough and with good enough coverage to allow the transport fluctuations to be reconstructed bottom pressure recorders at the exit of the denmark strait can also reproduce the transport variability

jurassic tectono sedimentary evolution of the northern lusitanian basin offshore portugal abstract the lusitanian basin is one of a series of rift related basins developed during the rifting that led to the break up of iberia and canada the strong influence of halokinesis on the depositional evolution of its northern sector provides an analogue for the development of other evaporite prone rift basins on atlantic type passive margins in this paper the pre valanginian evolution of the northern lusitanian basin is documented based on regional seismic stratigraphy isochron and time structure maps tied with sonic and stratigraphic data from 10 exploration wells the pre salt structure of the study area is marked by two sets of faults i a n s to ne sw striking set active throughout the jurassic period and ii a nw se striking set active during the late jurassic the latter defines five late jurassic sub basins northeast of a basin margin structure the marinha grande fault the development of half graben basins in the northern lusitanian basin during the jurassic was overprinted by halokinesis over the marinha grande fault and other major marginal basement faults halokinesis climaxed during the oxfordian kimmeridgian rifting with the formation of a 10 km long salt ridge over the marinha grande fault the ridge limited the southward progradation of fluvial deltaic units derived from hanging wall drainage systems and restricted the syn rift sediments to a 15 km long 5 km wide bowl shaped depocentre located 10 km west of the present coastline in order to better characterise the jurassic tectono sedimentary evolution of the northern lusitanian basin the interpreted seismic data is compared with physical models for extensional forced folds above active normal faults and with stratigraphic information from well and outcrop

reconciling plate tectonic reconstructions of alpine tethys with the geological geophysical record of spreading and subduction in the alps article a new reconstruction of alpine tethys combines plate kinematic modelling with a wealth of geological data and seismic tomography to shed light on its evolution from sea floor spreading through subduction to collision in the alps unlike previous models which relate the fate of alpine tethys solely to relative motions of africa iberia and europe during opening of the atlantic our reconstruction additionally invokes independent microplates whose motions are constrained primarily by the geological record the motions of these microplates adria iberia alcapia alkapecia and tiszia relative to both africa and europe during late cretaceous to cenozoic time involved the subduction of remnant tethyan basins during the following three stages that are characterized by contrasting plate motions and driving forces 1 131 84 ma intra oceanic subduction of the ligurian part of alpine tethys attached to iberia coincided with eo alpine orogenesis in the alcapia microplate north of africa these events were triggered primarily by foundering of the older 170 131 ma neotethyan subduction slab along the ne margin of the composite african adriatic plate subduction was linked by a sinistral transform system to e w opening of the valais part of alpine tethys 2 84 35 ma subduction of primarily the piemont and valais parts of alpine tethys which were then attached to the european plate beneath the overriding african and later adriatic plates nw translation of adria with respect to africa was accommodated primarily by slow widening of the ionian sea 3 35 ma recent rollback subduction of the ligurian part of alpine tethys coincided with western alpine orogenesis and involved the formation of the gibraltar and calabrian arcs rapid subduction and arc formation were driven primarily by the pull of the gravitationally unstable retreating adriatic and african slabs during slow convergence of africa and europe the upper european iberian plate stretched to accommodate this slab retreat in a very mobile fashion while the continental core of the adriatic microplate acted as a rigid indenter within the alpine collisional zone the subducted lithosphere in this reconstruction can be correlated with slab material imaged by seismic tomography beneath the alps and apennines as well as beneath parts of the pannonian basin the adriatic sea the ligurian sea and the western mediterranean the predicted amount of subducted lithosphere exceeds the estimated volume of slab material residing at depth by some 10 30 indicating that parts of slabs may be superposed within the mantle transition zone and or that some of this subducted lithosphere became seismically transparent

recent shifts in coastline change and shoreline stabilization linked to storm climate change since cuspate coastlines are especially sensitive to changes in wave climate they serve as potential indicators of initial responses to changing wave conditions previous work demonstrates that cape hatteras and cape lookout north carolina which are largely unaffected by shoreline stabilization efforts have become increasingly asymmetric over the past 30 years consistent with model predictions for coastline response to increases in atlantic ocean summer wave heights and resulting changes in the distribution of wave approach angles historic and recent shoreline change observations for cape fear north carolina and model simulations of coastline response to an increasingly asymmetric wave climate in the presence of beach nourishment produce comparable differences in shoreline change rates in response to changes in wave climate results suggest that the effect of beach nourishment is to compensate for and therefore to mask natural responses to wave climate change that might otherwise be discernible in patterns of shoreline change alone therefore this case study suggests that the effects of wave climate change on human modified coastlines may be detectable in the spatial and temporal patterns of shoreline stabilization activities similar analyses of cuspate features in areas where the change in wave climate is less pronounced i e fishing point maryland virginia and where local geology appears to exert control on coastline shape i e cape canaveral florida suggest that changes in shoreline configuration that may be arising from shifting wave climate are currently limited to sandy wave dominated coastlines where the change in wave climate has been most pronounced however if hurricane generated wave heights continue to increase large scale shifts in patterns of erosion and accretion will likely extend beyond sensitive cuspate features as the larger scale coastline shape comes into equilibrium with changing wave conditions copyright 2014 john wiley sons ltd

sedimentary evolution of a shallow carbonate ramp kimmeridgian ne spain unravelling controlling factors for facies heterogeneities at reservoir scale abstract the facies evolution of a late jurassic latest kimmeridgian shallow carbonate ramp was reconstructed after the analysis and correlation of 21 logs in a 20 30 km outcrop area located south of zaragoza northeast spain the studied succession belongs to the higueruelas formation which is of potential use as an analogue for understanding facies heterogeneities in certain hydrocarbon carbonate reservoirs e g the arab formation persian gulf the studied succession is arranged in nine sedimentary units bounded by discontinuity surfaces that can be traced over kilometres facies analysis permitted the reconstruction of two sedimentary models showing the transition from inner ramp subenvironments i e intertidal lagoon backshoal washover shoal sand blanket to the mid ramp foreshoal and offshore domains an oncolitic peloidal oolitic and an oolitic peloidal dominated ramp the oncolitic peloidal oolitic dominated ramp is characterized by peloidal oolitic and oncolitic dominated shoal sand blankets that developed in higher energy inner areas protecting peloidal oolitic backshoal and oncolitic lagoon domains including a mosaic of stromatoporoid carpets peloidal facies with fenestral porosity accumulated in an intertidal belt or as patches on top of the shoal sand blankets and washover deposits offshore from the shoal sand blankets chaetetid stromatoporoid coral rich buildups grew on the more proximal mid ramp surrounded by peloidal and peloidal bioclastic grain to mud supported facies an oolitic peloidal dominated ramp developed in a second stage of the evolution of the platform characterized by the presence of a wide restricted peloidal bioclastic oolitic lagoon on the inner ramp grading into a backshoal area dominated by storm related intraclastic peloidal deposits stromatoporoid carpets disappeared and oncolitic dominated deposits were constrained to the foreshoal and backshoal domains and locally to local ponds that developed in the intertidal belt or the restricted lagoon internal and external factors controlling facies heterogeneity and the sedimentary evolution of the carbonate ramp include resedimentation topographic relief and long to short term sea level fluctuations

a new path for the denmark strait overflow water from the iceland sea to denmark strait 1 denmark strait overflow water dsow is one of the main components of the thermohaline circulation there has been no consensus on where it is formed and by which way it is brought to the denmark strait it is shown here that it is brought to the sill by a hitherto unknown current that is traced from the sill back into the iceland sea north of iceland the transport of this current is sufficient to account for a major part of the transport of dsow as it has been measured at the sill if some entrainment of ambient water is assumed this supports theories suggesting that the iceland sea is the main source for the dsow and this has consequences for the way in which climate change affects the thermohaline circulation

a change from warm humid to cold dry climate conditions recorded in lower barremian clay dominated continental successions from the se iberian chain ne spain abstract a combined facies and clay mineralogy analysis of the continental succession recorded in the lower part of the blesa formation early barremian oliete subbasin ne spain allowed us to specify the palaeoclimatic and palaeoenvironmental conditions under which this sedimentary record originated six outcrops including clays clays marls and dm thick interbedded palustrine lacustrine limestone levels were logged and sampled for x ray diffraction and optical and electron microscopy analysis the lower levels consist of red clays with abundant ferruginous pisoids 1 5 mm in size and macropisoids 5 mm whereas the intermediate and upper levels are ochre and violet clays marls with few or no pisoids the pisoids normally consist of a nucleus and a cortex made up of several layers some pisoids have a fragment of a previous pisoid acting as a nucleus indicating local re working processes both the nucleus and the cortex are formed by hematite goethite variable contents of kaolinite and minor proportions of ilmenite their texture and mineralogy show an in situ growth interbedded limestone beds within the clay and clay marl dominated levels are formed by micrite microsparite and sparite these limestones are cemented by kaolinite and they also have pisoids indicating the occurrence of edaphic processes the red clays have the lowest calcite content and the highest hematite anatase diaspore goethite and kaolinite content by contrast the ochre and violet clays marls have higher illite content smectite is only detected in the ochre clays marls this mineral association is characteristic of lateritic palaeosols formed under warm and humid conditions kaolinite and smectite textures indicate that they are authigenic whereas illite may be of detrital origin the upward decrease in kaolinite hematite anatase diaspore and goethite content along with the increase in quartz content and the presence of smectite and illite reflect a change from warm and humid conditions to drier and colder conditions during the early barremian in the studied area

the iberian middle jurassic carbonate platform system synthesis of the palaeogeographic elements of its eastern margin spain abstract during the middle jurassic the domain of the iberian and catalan coastal ranges of eastern spain was occupied by a system of fault controlled carbonate platforms that flanked the iberian massif to the east this platform system marked the transition between the shelves of the alpine tethys and the central atlantic ocean the palaeogeographic reconstruction of the iberian middle jurassic platform system is based on more than 199 surface sections and 37 wells from southwest to northeast eight main palaeogeographic elements with associated characteristic facies are recognized these represent a system of horsts and grabens in the southwest the internal castilian platform is characterized by the frequently dolomitized oolitic and restricted facies of the yemeda formation to the northeast the nw trending open marine carbonate environments of the external castilian and aragonese platforms were separated by the fault controlled el maestrazgo high that is characterized mainly by the dolomitized rafales formation the external castilian and aragonese platforms consist from bottom to top of the microfilament mudstones to wackestones of the el pedregal formation the bioclastic and oolitic grainstones to packstones of the moscardon formation and the domeno formation that reflects a return to an open marine low energy wackestone to mudstone facies locally containing patches of oolitic grainstones the highly subsiding tortosa platform represented by the sant blai cardo and la tossa formations is bounded by the dolomitic facies deposited on the el maestrazgo and the tarragona highs and by the catalan massif where no middle jurassic deposits have been recorded the open marine facies and condensed sections of the beceite strait separated the aragonese and tortosa platforms a regional stratigraphical gap spanning the upper callovian lamberti zone to the lower oxfordian cordatum zone is evident a system of northwest and northeast trending normal faults controlled thickness and facies distribution data from the iberian carbonate platform system indicate that expanded sections were not necessarily associated with open marine environments condensed and expanded sections are developed in open and restricted marine facies even on such palaeogeographic highs as the el maestrazgo high restricted and shallow marine environments occasionally developed in parts of the external castilian platform

the jurassic evolution of the africa iberia conjugate margin and its implications on the evolution of the atlantic tethys triple junction abstract the central atlantic north atlantic and maghrebian tethys formed a triple junction during the mesozoic break up of pangea plate reconstructions of this triple junction have concentrated on the atlantic branches for which there are abundant geophysical data over their conjugate margins and associated oceanic domains this is not the case for the maghrebian tethys where both the mesozoic iberian and african margins and the intervening ocean are mostly overthrust by the betic rif tell orogenic systems the resulting lack of constraints on the evolution of the africa iberia system has led most authors to treat the evolution of this system as a secondary problem in the more global atlantic and tethys systems in this paper the evolution of the basins of iberia and northwest africa is discussed and geological constraints are used to propose a new late triassic fit of iberia with north america and africa this late triassic fit and its implications for jurassic evolution are compared with the evolution of the sedimentary basins of the atlantic tethys triple junction and in particular those of the africa iberia margins the geological evidence and the resulting plate reconstructions are consistent with a jurassic evolution of the africa iberia system that is dominated by three major events 1 the early to middle jurassic transition in which oblique rifting gives way to transtensional rifting 2 the middle to late jurassic transition marking the termination of most rifting in the system and interpreted to coincide with exhumation of sub continental mantle and formation of oceanic crust in a setting dominated by transcurrence between africa and iberia and 3 the late jurassic to early cretaceous transition in which the rate of relative motion between and iberia and africa decreased significantly as rifting in the north atlantic gained momentum

unravelling the architecture and evolution of the inverted multi stage north iberian bay of biscay rift abstract current rift models propose polyphase rift evolutions that develop with the same kinematic framework and accommodate continuous and sequential extension through the stacking of deformation modes several rifted margins show however evidence for multiple and out of sequence rift events which developed within different kinematic frameworks with a complex spatial and temporal evolution in this work we address the problem of multi stage rifting based on the study of the central north iberian margin located at the southern bay of biscay triangular oceanic domain this magma poor rifted margin recorded three major mesozoic rift events and a subsequent alpine compressional reactivation representing a unique setting to study the architecture of multi stage rift systems and the exerted control on subsequent reactivation relying on a dense set of 2d seismic reflection profiles boreholes and published velocity models we map and describe structural domains and major extensional and compressional structures and we construct depth and thickness maps of syn rift units these new maps display the geometry and spatial distribution of major rift basins and bounding structures distinctive scenarios resulting from this tectono stratigraphic approach led us to define three rift systems a first diffuse and widespread triassic system with classical fault bounded half graben basins a second narrow deep and localised late jurassic to barremian transtensional system including laterally confined pull apart basins and a third widely distributed aptian to cenomanian hyperextended system our results show that each rift system controlled the successive extensional events and the subsequent contractional deformation resulting in a complex 3d template deciphering the tectono stratigraphic architecture of such multi stage systems provide key insights on the spatial temporal and thermal evolution of divergent plate boundaries it is likewise indispensable to propose and test kinematic plate deformable models on conjugate rifted margins and to comprehend the implications for their reactivation

carbonate production and offshore transport on a late jurassic carbonate ramp kimmeridgian iberian basin ne spain evidence from outcrops and computer modelling

long term non local coastline responses to local shoreline stabilization 1 the future of large scale coastline evolution will be strongly coupled to human manipulations designed to prevent erosion we explore the consequences of this coupling using a numerical model for large scale coastline evolution to compare the long term non local effects of two generalized classes of shoreline stabilization 1 beach nourishment the addition of dredged sand to an eroding beach and 2 hard structures e g seawalls groynes etc which fix the position of the shoreline without adding sand in centurial model experiments where localized stabilization is maintained in the context of changing climate forcing both forms of stabilization are found to significantly alter patterns of erosion and accretion at distances up to tens of kilometers on a cuspate cape coastline similar to the north and south carolina coast usa with stabilization applied to the eroding updrift flank of a single cape perturbations to coastline evolution are qualitatively similar within 20 km for each stabilization scenario though they differ in magnitude both updrift and downdrift of the stabilized shoreline the human signal in coastline change can extend as far as a neighboring cape approximately 100 km away but these long range effects differ for each scenario nourishment resulted in seaward growth of the stabilized cape increasing the extent that it blocked sediment flux in downdrift regions of the coast through wave shadowing when stabilized with a hard structure the cape s initial position remain fixed decreasing wave shadowing

instability and finite amplitude self organization of large scale coastline shapes recent research addresses the formation of patterns on sandy coastlines on alongshore scales that are large compared with the cross shore extent of active sediment transport a simple morphodynamic instability arises from the feedback between wave driven alongshore sediment flux and coastline shape coastline segments with different orientations experience different alongshore sediment fluxes so that curvatures in coastline shape drive gradients in sediment flux which can augment the shoreline curvatures in a simple numerical model this instability and subsequent finite amplitude interactions between pattern elements lead to a wide range of different rhythmic shapes and behaviours ranging from symmetric cuspate capes and bays to alongshore migrating flying spits depending on the characteristics of the input wave forcing the scale of the pattern coarsens in some cases because of the merger of migrating coastline features and in other cases because of non local screening interactions between coastline protrusions which affect the waves reaching other parts of the coastline features growing on opposite sides of an enclosed water body mutually affect the waves reaching each other in ways that lead to the segmentation of elongated water bodies initial tests of model predictions and comparison with observations suggest that modes of pattern formation in the model are relevant in nature

coupled economic coastline modeling with suckers and free riders 1 shoreline erosion is a natural trend along most sandy coastlines humans often respond to shoreline erosion with beach nourishment to maintain coastal property values locally extending the shoreline through nourishment alters alongshore sediment transport and changes shoreline dynamics in adjacent coastal regions if left unmanaged sandy coastlines can have spatially complex or simple patterns of erosion due to the relationship of large scale morphology and the local wave climate using a numerical model that simulates spatially decentralized and locally optimal nourishment decisions characteristic of much of u s east coast beach management we find that human erosion intervention does not simply reflect the alongshore erosion pattern spatial interactions generate feedbacks in economic and physical variables that lead to widespread emergence of free riders and suckers with subsequent inequality in the alongshore distribution of property value along cuspate coastlines such as those found along the u s southeast coast these long term property value differences span an order of magnitude results imply that spatially decentralized management of nourishment can lead to property values that are divorced from spatial erosion signals this management approach is unlikely to be optimal