pinch and swell structures at the middle upper muschelkalk boundary triassic evidence of earthquake effects seismites in the germanic basin a limestone bed with synsedimentary deformations is described from the middle upper muschelkalk boundary middle triassic of thuringia germany the deformation structures have an elongated geometry in a preferential n s to nnw sse direction and are several metres across in size they are similar to ball and pillow structures but differ from these by absence of significant loading into underlying beds their development is interpreted as a result of bed internal deformation with bed thickening due to lateral contraction and bed thinning due to stretching this deformation mechanism is comparable to the one producing boudinage structures in particular pinch and swell structures the deformation style and size of these structures and their widespread occurrence together with other synsedimentary deformation structures support their interpretation as earthquake induced structures seismites synsedimentary deformation structures are common features that occur in a narrow stratigraphic unit at the middle upper muschelkalk boundary in different parts of the germanic basin and point to tectonically influenced changes in the depositional regime and basin organization further examples of pinch and swell structures from the lower and upper muschelkalk suggest that tectonics significantly influenced the sedimentation in the germanic basin during middle triassic time

carbonate platform crisis in the carnian late triassic of hanwang sichuan basin south china insights from conodonts and stable isotope data abstract during the carnian the hanwang area in the northwestern sichuan basin south china was characterized by shallow water carbonate sedimentation that underwent an abrupt demise associated to a sudden input of terrigenous sediments this major facies change was considered to be the expression of the onset of the carnian humid episode a most remarkable environmental crisis in late triassic that is well recognized in northwestern tethys margins and coincides with a major global perturbation of the carbon stable isotope record however the lack of detailed biostratigraphic constraints have so far prevented a precise dating of the carbonate platform demise in western sichuan basin in this work the qingyan gou hwq section cropping out in hanwang was investigated for its facies and microfacies carbonate carbon and oxygen isotopes on brachiopods microbial grains and bulk matrix facies analysis shows a marine transgression from inner ramp oolitic shoal to middle ramp siliceous sponge mound then overlain by shale and calcareous siltstone with interbedded silty mudstones refined biostratigraphic data from hwq and guanyin ya hwg sections imply that the demise of sponge mounds occur in the late tuvalian or later a negative carbon isotope perturbation was found in the bulk matrix immediately below the sponge mounds demise but it was not found on the isotope record from brachiopods this suggests that the negative shift in the bulk carbonate was probably related to diagenesis given the late tuvalian last substage of carnian age attributed to the demise of the sponge mounds and the absence of a carbon isotopic excursion we infer that the carbonate platform crisis and strong terrigenous input in hanwang cannot be related to the onset of the carnian humid episode these the demise of the carbonate platform and the facies deepening trend could be rather due to the interplay between accelerating subsidence rates environmental chants and enhanced siliciclastic input related to the formation of a foreland basin during indosinian orogenesis

an oscillating trend in phanerozoic non skeletal carbonate mineralogy textural and compositional data on ancient ooids and cements suggest the existence of an oscillating phanerozoic temporal trend in non skeletal carbonate mineralogy the trend shows good correlation with eustatic climatic oscillations proposed by others the most likely mechanism appears to be plate tectonically influenced oscillations in pco2 the vapour pressure of co2 rather than change in oceanic mg ca ratio

an exhumed palaeozoic underwater scenery the visean mud mounds of the eastern anti atlas morocco about one hundred carbonate mud mounds covering an area of 440 km 2 in the eastern anti atlas of morocco constitute one of the largest mound agglomerations known so far from lower carboniferous settings they occur within a 4000 m thick succession of shales with intercalated bedded limestones sandstones and siltstones according to conodont and goniatite biostratigraphy mound formation started in the early gnathodus texanus zone and terminated during the g bilineatus zone of the visean stage individual mounds are a few metres to 30 m high have base diameters of up to 300 m and are concentrated in several parallel wnw ese running belts from their lithology and facies relationships four types of mounds can be distinguished 1 massive crinoidal wacke or packstones without stromatactis 2 massive crinoidal wacke or packstones with rare stromatactis 3 similar to 2 but allochthonous and 4 biodetrital skeletal grainstone mounds while carbonate deposition in types 1 to 3 was probably triggered by microbial precipitation type 4 is the result of a predominantly mechanical accumulation of skeletal debris biota in the four types comprise a great variety of invertebrates among which crinoids sponges and bryozoans are most common diagenesis of the mound carbonates was dominated by recrystallization of micritic matrix and organic remains and late burial cementation oxygen and carbon isotope data of brachiopod and crinoid ossicles matrix and early marine cements plot in a large field and do not allow definite conclusions about the composition of the ambient seawater microbial activity and the absence or scarcity of green algae colonial corals and coralline sponges suggest deposition of the mounds in moderate water depth close to the lower limit of the photic zone d 2001 elsevier science b v all rights reserved

a mixed solution for a highly protected coast punta marina northern adriatic sea italy abstract spatial data collected over three years are presented to assess the impacts of a mixed intervention carried out in a low sandy microtidal highly protected beach punta marina italy coastal erosion started in the 1980s principally due to reduction of fluvial sediment discharges wave attack and both anthropic and natural subsidence the intervention consisted in a small beach nourishment shallow feeder berm construction and the placement of an artificial reef to retain the sand fill topo bathymetrical surveys with real time kinematic rtk gps multi beam surveys sediment samplings wave data records dive inspections and numerical simulations were undertaken over a 3 year monitoring period to analyse the process response mechanism of this intervention to assess the main factors affecting the performance of the mixed intervention and the possibility of using fine sediments for nourishment practices the results reveal a generally positive impact characterised by short term beach stability that was mostly due to the feeder berm effect the beach nourishment had a short but direct effect on the beach width while the feeder berm dissipated wave energy and successively fed the nearshore with eroded sediment on the other hand the artificial reef did not retain the sand but rather induced rip currents that increased eddy circulation and therefore promoted the loss of offshore sediment settlement and scouring problems were also observed and the structure s failure induced safety problems the results confirm that a feeder berm operation carried out with fine sediment represents a good solution although particular attention must be paid to the relationship between sediment grain sizes volume and location of the nourishment as they are the key factors for good performance finally the cross shore sediment transport represents a critical factor that controls the coastal evolution of beaches bounded by hard structures and assimilated to the littoral cell consequently it should be better integrated within the nourishment design and model setting

depositional facies and stratal geometry of an upper carboniferous prograding and aggrading high relief carbonate platform cantabrian mountains n spain seismic scale continuous exposures of an upper carboniferous bashkirian moscovian carbonate platform n spain provide detailed information about the lithofacies and stratal geometries quantified with differential global positioning system measurements of microbial boundstone dominated steep prograding and aggrading platform margins progradational and aggradational platform to slope transects are characterized by distinct lithological features and stratal patterns that can be applied to the understanding of geometrically comparable high relief depositional systems the bashkirian is characterized by rapid progradation at rates of 415 970 m my 1 characteristic outerplatform facies are high energy grainstones with coated intraclasts ooids and pisoids moderate energy algal skeletal grainstones to packstones and lower energy algal packstone and boundstone units the moscovian aggradational phase is characterized by aggradation rates of 108 m my 1 coated grain shoals are less common whereas crinoidal bars nucleated in well circulated settings below wave base boundstones form a belt 30 300 m wide at the platform break and interfinger inwards with massive algal skeletal wackestones mud rich banks the progradational phase has divergent outer platform strata with basinward dips of 12 to 2 steep clinoforms with dips of 20 28 are 650 750 m in relief and possibly sigmoidal to concave in the lower part the basinward dipping outer platform strata might be depositional for less than 6 consistent with lithofacies deepening seaward the basinward dip is attributed to the downward shift of upperslope boundstone forced by late highstand and relative sea level fall and to compaction induced differential subsidence during progradation the aggradational phase is characterized by horizontally layered platform strata clinoforms steepen to 30 45 reaching heights of 850 m and are planar to concave the evolution from progradation to aggradation at the bashkirian moscovian boundary is attributed to increased foreland basin subsidence and decreased boundstone accumulation rates progradation was primarily controlled by boundstone growth rather than by highstand shedding from the platform top within the major phases aggradational progradational increments are produced by third to fourth order relative sea level

nourishing the shoreface observations and hindcasting of the egmond case the netherlands abstract although beach nourishment policy in the netherlands is generally successful in maintaining the 1990 shoreline the efficiency of nourishments at several locations along the north sea coast is unacceptably low these locations are identified as erosion hotspots egmond aan zee is such a hotspot the bathymetric longshore irregularities make this coastal stretch highly susceptible to rip currents and horizontal circulations which transport large volumes of nourished sand to the sea in 1999 an alternative nourishment design was implemented this consisted of a shoreface nourishment at the outer bar at 7 5 m depth combined with a nourishment of the beach behind it high resolution bathymetric surveys carried out with the wesp revealed that the shoreface nourishment resulted in a significant shoreward migration of the outer bar during 1999 2001 after 2 years the system started to return to its natural dynamic equilibrium and lost the positive influence of the shoreface nourishment area shoreward movement of bars and increase of bar height which forms the first defense line of the mainland against the sea and positive contribution to the sand budget which increased as a result of the nourishment after 3 years may 1999 to april 2002 the sediment volume still had an increase of 477 500 m3 45 of the applied sand relative to may 1999 the shoreface nourishment area did not have a direct effect on the beach the shoreface nourishment area probably will have to be maintained to retain the sediment on the beach in the long run in egmond the shoreface nourishment started to disappear before the sediment could reach the beach the time scale of sediment feed to the beach zone probably is of the order of 5 10 years the shoreface nourishment seems to function as a reef creating a lee side effect that influences both cross shore and longshore sediment transport resulting in two main hypotheses firstly the longshore effect in which large waves break at the shoreface nourishment cause a calmer wave climate shoreward of the shoreface nourishment area and a reduction of the longshore current the shoreface nourishment partially blocks the wave driven longshore current secondly the cross shore effect in which shoaling waves generate onshore transport these hypotheses are supported by generated model results with both a process based profile model unibest tc and a process based coastal area model delft3d mor the unibest tc model was able to predict the detachment of the outer bar from the shoreface nourishment and to some extent the shoreward bar movements in the lee of the shoreface nourishment area the model found an increase in sediment confirming the shielding effect of the shoreface nourishment area the delft3d model found as a result of the shoreface nourishment area a decrease of the flow velocity and the wave height just shoreward of the shoreface nourishment area the model was able to predict the similar trend in sedimentation erosion pattern although the intensities were smaller in the lee of the shoreface nourishment area a clear sedimentation was found erosion was found south and seaward of the shoreface nourishment area the modeled profiles did not follow the measured profile changes the separation of the shoreface nourishment from the outer bar and the shoreward migration of the bars could not be accurately modeled because the cross shore transport caused by wave asymmetry is not taken into account in the standard version of delft3d these results were in line with the expectations

migration of the carbonate ramp and sponge buildup driven by the orogenic wedge advance in the early stage carnian of the longmen shan foreland basin china abstract the marine carnian the maantang fm overlies a flexural forebulge unconformity and records the initial establishment drowning and migration of a carbonate ramp and sponge buildup along the forebulge margin of the longmen shan foreland basin the maantang fm is of wedge shaped geometry and is composed of oolitic and bioclastic limestones siliceous sponge reef and shale in an upward fining succession the formation shows the establishment and drowning of a distal margin carbonate ramp and sponge buildup deepening into offshore marine muds followed by progradation of marginal marine siliciclastics the formation also shows the transition from shale cratonward into carbonate rock southeastward the sponge reefs and shoal were deposited on a carbonate ramp on the distal margin of the early foreland basin the growth rate of sponge reefs is 0 04 mm yr equivalent to the rate of relative sea level rise of 0 01 0 05 mm yr the sponge buildup and oolitic shoal are divided into seven zones southeastward on the carbonate ramp along the basal unconformity their migration rate of 18 mm yr from nw to se coincides with the estimated orogenic wedge advance rate 5 15 mm yr li et al 2003 a clear indication that the advancing wedge controlled the migration rate of foreland oolitic shoal siliceous sponge reef we have inferred that the tectonic load of the longmen shan orogenic wedge led to flexural subsidence and rising relative sea level in the foreland basin located at the western margin of the yangtze craton driving the growth and subsequent drowning of the oolitic shoal sponge buildup in the early stage of the foreland basin we propose that the drowning and migration processes were the sedimentary response to the orogenic wedge advance toward the yangtze craton and to the rapid closure of the carnian songpan ganzi remnant ocean basin

morphological evolution of a submerged artificial nearshore berm along a low wave microtidal coast fort myers beach west central florida usa abstract nourishment in the nearshore is becoming an increasingly utilized method for regional sediment management particularly for dredged material that contains more fine sediment than the native beach a nearshore berm was constructed at fort myers beach florida usa using mixed sized sediment dredged from a nearby channel the nearshore berm which is the shallowest of its kind was placed in water depths between 1 2 and 2 4 m with the berm crest just below the mean lower low water level based on time series profiles surveyed from 2009 to 2013 the nearshore berm migrated onshore while the system was approaching a dynamic equilibrium the distant passage of two tropical storms in the third year generated exceptionally high waves for the study area substantial profile change induced by the energetic conditions contributed to rapid evolution of the berm profiles toward equilibrium near the end of the fourth year the berm profiles had returned to the equilibrium shape characteristic of the study area gaps in the berm allowed water circulation when the berm became emergent and watercraft access to the beach for recreational purposes gaps should be considered as a design parameter for future berm nourishments sediment samples collected and analyzed showed that the fine sediment content in the original placed material was selectively transported and deposited offshore while the coarser component moved onshore the dry beach maintained the same sediment properties throughout the study period and was not influenced by the fine sediment in the initial construction of the berm

the facies properties and depositional environments of nodular limestones and red marly limestones ammonitico rosso in the ankara jurassic sequence central turkey the nodular limestones and red marls of the ankara region deposited during the early to middle jurassic show similar palaeontological and sedimentological characteristics to those of the red nodular limestones form the northern alps adnet limestones and from the southern alps ammonitico rosso the nodular limestones appear to be hardground breccias drowned into the red marly limestones due to the instability of the bottom the association of sponge spicules crinoid fragments small ostracods benthic foraminifers shell debris and common micrite matrix suggests a subtidal environment the subsequent formation of red marly limestones consists of the partial dissolution of the shells this suggests that a low sedimentation rate and or sedimentological breaks took place during the precipitation of the ammonite bearing marls the nodular limestones hardground breccias and the ammonitico rosso type facies of the ankara jurassic succession were formed in a deeper subtidal environment and or deeper shelf extending into the basin the hardground layers drowned into the ammonitico rosso were likely formed on a local carbonate shelf that deepened increasingly through the early to middle jurassic development of a local submarine clastic fan within the carbonate succession of the ankara jurassic basin indicates an irregular bottom topography induced by the syn sedimentary faults

a silurian sphinctozoan sponge from east central cornwallis island canadian arctic the first silurian sphinctozoan ever recorded is reported from the canadian arctic the polysiphonate sphinctozoan rigbyspongia catenula n gen n sp is found associated with numerous anthaspidellid sponges diagnostic features of the new genus are its numerous axial siphons and vertical pillars within each chamber although it is structurally complex for a sphinctozoan of this age and is the only silurian representative of the order this new genus provides few clues to the still enigmatic problem of paleozoic sphinctozoan phylogeny

kinematic significance of sediment filled fissures in the north mountain basalt fundy rift basin nova scotia canada abstract numerous sediment filled fissures are present near the upper surface of the north mountain basalt 202 ma of the fundy basin which formed during triassic jurassic rifting the fissures are infilled with the same clastic material comprising the basal parts of the overlying earliest jurassic age sedimentary formations which accumulated less than 200 k y after the cooling of the basalt nearly all of the 1368 fissures measured in this study are planar to sub planar and are sub vertical after correcting the basalt flows to paleo horizontal the fissures typically formed along preexisting columnar joints within the basalt northeast striking fissures generally define a preferred orientation and commonly are wider than other fissures the sediment filled fissures therefore indicate earliest jurassic age nw se extension this extension direction is consistent with that indicated by the ne striking shelburne diabase dike the attitude of mesoscopic faults and the geometry of the fundy rift basin thus sediment filled fissures by themselves can serve as useful kinematic indicators and place tight constraints on the relative timing of extension

rise and fall of an isolated unstable carbonate platform the cambrian of southwestern sardinia strong effects of tensional tectonics dominate the lower and middle cambrian sequence of southwestern sardinia a thinning of the continental crust and the possible development of a passive margin in the cambrian is indicated by different stages of evolution of a mainly carbonatic platform a clastic carbonatic homoclinal ramp with algal archaeocyathan mounds epiphyton renalcis in the west clastic shallow marine to tidal sequences in the east b carbonatic clastic ramp or rimmed shelf with an ooid shoal complex prograding towards the west the back shoal area contains peloidal mudstones algal archaeocyathan biostromes girvanella and increasingly tidal deposits clastic and carbonatic towards the east c isolated platform aggraded to sea level rimmed by slope deposits with slumps and breccia beds in the southeast and northwest d isolated flooded platform barriers towards the open sea partly broke down e isolated platform with raised rims and deep interior often with thick breccia beds in uppermost parts f break down of the platform late early cambrian marked by nodular limestones and limestoneshale intercalations g terrigenous clastics cover the former platform

late devonian early carboniferous deep water coral assemblages and sedimentation on a devonian seamount iberg reef harz mts germany abstract growth of the middle late devonian iberg reef a small atoll in the variscan geosyncline of central europe ceased towards the end of the frasnian during the famennian and dinantian the reef continuously subsided relative to sea level in the latest dinantian the reef was covered by clastics five deep water organism assemblages colonized the famennian dinantian seamount successively they are well comparable to recent organism communities on deep water coral banks in the famennian abundant crinoids and ancillary rugose corals and brachiopods colonized the reef top during the late tournaisian a coral crinoid assemblage established on the reef it developed into a varied fauna of corals crinoids trilobites brachiopods bivalves gastropods and goniatites in the early and middle visean the late visean assemblage was dominated by goniatites and pseudoplanktonic bivalves in the latest visean a monospecific brachiopod fauna and small microbial buildups thrived in extreme environmental conditions on the reef top the skeletal debris of the organisms was eroded post mortem and only accumulated in current protected depressions of the reef surface along with carbonate mud local depressions include hollows on the reef top neptunian dikes and pore space of a breccia that formed due to intensive shattering of the reef top during nearby volcanic activity during most of the famennian and tournaisian there is a hiatus caused by non deposition only reworked famennian and tournaisian conodonts recovered from upper tournaisian middle visean limestones give evidence of marine conditions on top of the reef the sedimentary environment on the drowned atoll compares well to that on recent guyots including hiatuses slow and patchy sedimentation erosion and redeposition both the aftermath of the frasnian famennian extinction that drastically reduced metazoan reef builders and a trend towards lower temperatures in the famennian and dinantian are believed to have prevented the reestablishment of a shallow water reef on the drowning devonian atoll

shoreline response to multi functional artificial surfing reefs a numerical and physical modelling study the results of a series of 2dh numerical and 3d scaled physical modelling tests indicate that processes governing shoreline response to submerged structures such as artificial surfing reefs are different from those associated with emergent offshore breakwaters unlike the case of emergent offshore breakwaters where shoreline accretion salient development is expected under all structural environmental conditions the principal mode of shoreline response to submerged structures can vary between erosive and accretive depending on the offshore distance to the structure the predominant wave incidence angle and structure crest level also have important implications on the magnitude of shoreline response but not on the mode of shoreline response i e erosion vs accretion based on the results obtained here a predictive empirical relationship is proposed as a preliminary engineering tool to assess shoreline response to submerged structures

four year performance and associated controlling factors of several beach nourishment projects along three adjacent barrier islands west central florida usa abstract to quantify the performance of several beach nourishment projects on three adjacent barrier islands located in west central florida a total of 5200 beach and nearshore profiles spaced at 300 m were surveyed monthly to bi monthly from 2006 to 2010 beach nourishment performance at annual temporal and kilometer spatial scales within the microtidal low wave energy barrier island coast is most significantly influenced by the interruption of longshore sediment transport by complex tidal inlet processes the inlet processes directly influencing adjacent beach nourishment performance include longshore transport interruption resulting from divergence induced by wave refraction over an ebb tidal shoal flood tidal currents along the beach and total littoral blockage by structured inlets secondary factors controlling the nourishment performance include project length and width shoreline orientation and antecedent geology a morphologic indicator of a large longshore transport gradient within the study area is the absence of a nearshore sandbar these non barred beaches are characterized by persistent shoreline erosion the presence of a sandbar indicates the dominance of cross shore processes with bar migration in response to wave condition variations and a relatively stable shoreline the entirety of a barrier island system should be considered when evaluating the performance of a nourishment

middle ordovician chazy group cavity dwelling boring sponges microcavities in lower middle ordovician bryozoan mounds from the laval formation chazy group near montreal quebec contain evidence that endolithic boring sponges were present ramose borings with scalloped walls and swellings resembling endolithic sponge galleries faceted carbonate grains similar to modern sponge chips and siliceous spicules both in situ on the cavity wall or roof and in the sediment all point to the activities of endolithic sponges in the hard substrate of the wall and roof coelobiontic cavity dwelling endolithic sponges therefore infested cavities in skeletal mounds and reefs in the middle ordovician and appear to have exploited the cavity habitat very soon after the appearance of metazoan skeletal reefs in the ordovician

ludlow silurian lithistid and hexactinellid sponges cape phillips formation canadian arctic abundant hexactinellid and lithistid sponges occur in ludlow silurian platform slope strata of the cape phillips formation canadian arctic islands the following are new in the anthaspidellidae miller 1889 rhodesispongia simplex n gen and sp climacospongia snowblindella n sp and climacospongia undulata n sp in the sphaerocladina schrammen 1910 caryospongia tuberosa n sp in the hexactinellida schmidt 1870 malumispongium cornwallisi n sp of the monospecific superfamily malumispongium rigby 1967 other previously described sponges recognized in the study assemblage include hindia sphaeroidalis duncan 1879 and caryospongia juglans rauff 1894 these occur in association with abundant archaeoscyphia sp in thin laterally extensive lithistid sponge biostromes which throve on platform slope sediments during the late silurian based on the dominant dendroclone forms in the skeletons of these and other genera anthaspidellidae can be divided informally into two groups i the polyclonids p

timing and genesis of early marine caymanites in the hydrothermal palaeokarst system of buda hills hungary abstract sedimentological biostratigraphic and magnetostratigraphic studies were carried out on five late eocene early oligocene profiles in the buda hills hungary the szepvolgy limestone formation accumulated on the pre eocene basement basal strata of the limestone consist of a thin conglomerate followed by a coralgal limestone the overlying limestone contains abundant nummulites discocyclina the contact between these two members is sharp the szepvolgy limestone body covering 60 65 km2 is considered a carbonate bank above the limestone the siliciclastic slope deposits of the pelagic and turbiditic buda marl and the euxinic tard clay accumulated a huge multiphase hydrothermal cave system developed in the szepvolgy limestone resulting in a long term composite palaeokarstic evolution lasting from the late eocene to the quaternary the first palaeokarst phase during the late eocene is represented by two generations of early marine cavity filling sediments of caymanite type deposited at sea level the earlier carbonate infilling is conformable while the younger siliciclastic one is disconformable with the bedding of the host rock bio and magnetostratigraphic studies indicate that deposition of the caymanites bearing palaeokarst host sequence started in the late eocene during chron c15r 35 3 ma and terminated in the early oligocene during chron c13n 33 ma two marker horizons are present the first is between the szepvolgy limestone and buda marl at 34 6 ma and the second horizon is between the buda marl and the tard clay at 33 5 ma the szepvolgy limestone deposited on a mobile shelf represents a deepening upward sequence interrupted by two lowstand events they can be correlated with the phd event of keller et al 1987 global distribution of late palaeogene hiatuses geology 15 199 203 and resulted in marine palaeokarstification the carbonate shelf with the infillings drowned at 34 6 ma the caymanites accumulated at about 35 2 35 0 ma and represent short term palaeokarstic events their deposition record was estimated in several thousand years

relations between submarine fissures internal breccias and mass flows during triassic and earlier rifting periods deep fissures in shallow water limestones filled with deep water sediments are described from many places especially in the triassic and jurassic of the tethys and in the middle to upper devonian of the variscian mountains mass flows occur in the same formations and areas on the island of hydra greece it was possible to show that both phenomena are linked by internal breccias of well fitted limestone fragments they are indicative of slope or near slope positions and are very probably caused by flexure like deformations of shallow burial limestones seismic shocks producing overpressure may be instrumental in the disintegration of the semi lithified limestones thus providing the material for mass flows these events are associated with a tectonical subsidence as shown by deep water matrix in the brecciated shallow water limestones they occur in areas and periods of submarine rifting especially in late devonian and triassic time at least four triassic brecciation events can be traced from greece to the alps and correspond presumably to major transgressions in the cratonic basin of middle europe

upper silurian lithistid sponge reefs on somerset island arctic canada the upper ludlow douro formation contains the first reported silurian sponge reefs these relatively small 5 35 m diameter mound shaped structures contain on average 35 lithistid demosponges reefs are surrounded by irregular haloes of crinoid debris abundance and diversity of all fossil groups decreases away from the reefs each reef is underlain by a lens of crinoid wackestone to grainstone rich in crinoid holdfasts trepostomate bryozoans solenoporacean algae and rhynchonellid brachiopods are locally common the bulk of each reef consists of lime mudstone with abundant lithistid sponges this is capped by a thin layer of wackestone with abundant tabulate and rugose corals and fewer lithistid sponges calcareous algae trepostomate bryozoans and stromatoporoids this zonation in which a sponge colonization community was replaced by a coral diversification community is similar to that reported from some middle ordovician upper jurassic and holocene sponge reefs the douro sponge reefs were relatively low structures with about 3 m maximum topographic relief they grew on a broad carbonate platform probably in warm tranquil turbid waters of normal or near normal marine salinity periodic influxes of terrigenous mud adversely affected reef size and caused biotic changes some of the reef lime mud was derived from non reef sources but significant quantities were also produced on the reefs reefs underwent synsedimentary lithification bioerosion and minor storm erosion fabrics and compositions of sparry calcite in cavities record three generations of meteoric cementation originally siliceous spicules of the lithistid sponges were dissolved and the moulds later filled with sparry calcite early dissolution of siliceous spicules is common in reef environments and may have caused fossil sponges to be under represented in ancient reefs

numerical modelling of the morphological response induced by low crested structures in lido di dante italy this paper analyses the morphological response induced by low crested structures on the adjacent seabed with particular interest in the erosion patterns that frequently develop at gaps and roundheads the mechanisms responsible for erosion processes are examined by means of morphodynamic simulations with the numerical suite mike 21 cams developed by dhi water environment the main purpose of the paper is to verify how and how far a commercial code can predict bed evolution in vicinity of defence structures in a real case in order to get information that may be very useful for structure design and possible maintenance of existing works the code is applied to a long term simulation on a study site that is characterized by a composite intervention and suffers from severe erosion lido di dante italy the simulation covers the period one year and a half between two available multi beam surveys in order to have a detailed real bathymetry as starting point and another one as accurate as the first to compare numerical with surveyed results all the other input data for the model as waves tide wind and sediment characteristics are derived from measurements in the area moreover the code is calibrated using wave and current data acquired during a field campaign the bed evolution derived from simulations shows a good agreement with the survey both in the locations and in the intensity of erosive and depositional areas a sensitivity analysis of results to some selected modelling parameters is performed on a shorter simulation period one month showing that accounting for bed slope in sediment transport modelling has greater effects in bathymetry evolution than the use of a complex sediment bathymetry or the representation of wave diffraction

the modern calcifying sponge spheciospongia vesparium lamarck 1815 great bahama bank implications for ancient sponge mud mounds abstract modern calcified siliceous sponges from the great bahama bank living at water depth ranges of 2 to 5 m have been proposed as likely analogues for calcified sponges in upper jurassic sponge reefs e g southern germany or lower jurassic bioherms that consist of reddish spiculiferous limestones e g broccatello formation of the southern alps indeed sponge related calcification or siliceous sponge diagenesis in general is widely considered a key feature for the mechanisms of accretion and textural maturation in phanerozoic sponge mounds or spiculiferous carbonate mud mounds based on a revisit of the original sites on the great bahama bank nw of andros island the biostratonomy of the calcifying sponge spheciospongia vesparium lamarck 1815 was explored using the patterns of fluorescent dissolved organic matter fdom as revealed by the application of three dimensional excitation emission matrix eem fluorescence spectroscopy geochemical sampling distinguished between fdom that was extracted from sponge tissue and fdom that was intimately associated with caco 3 from particles due to sediment agglutination and authigenic caco 3 both obtained from the living sponge at the sediment surface and from the calcified sponge at the shallow subsurface from 5 to 10 cm of depth as expected the sponge tissue shows highest intensities for protein like fluorescence however from the surface to the subsurface there is a loss of such relatively pristine fluorescent material in the range of 70 humic like fluorescence that occurs associated with sponge tissue is relatively mature or aged thus it most probably represents seawater fdom taken up through active filter feeding relative to the sponge tissue material the fdom patterns associated with ca carbonates show much lower total fluorescence intensities by up to two orders of magnitude the agglutinated sedimentary carbonate particles from the surface pellets ooids grapestones exclusively show a relatively mature humic like fluorescence the deeper calcified parts of spheciospongia which represent a mixture of particles and authigenic caco 3 provided a fdom pattern that obviously combines the mature fdom pattern of particles with diagenetically fresh protein like and fulvic acid like fluorescence we conclude that shallow subsurface calcification of s vesparium correlates with the initial stage of sponge biomass humification such a mechanism of biomass transformation i e from biopolymers to geopolymers via degradation and condensation has also been suggested for the large scale development of carbonate sponge mud mounds therefore we consider the modern calcifying siliceous sponge s vesparium lamarck 1815 a potential pardigm to decipher in more detail the geologically important process of biomass induced calcification or organomineralisation with its subsequent effect of pore water fdom preservation and sediment lithification

relationship among submarine instabilities sea level variations and the presence of an ice sheet on the continental shelf an example from the verrill canyon area scotian shelf sea level low stands are associated with the growth of glacial ice sheets during maximum stages of glaciation ice sheets may extend to the outer continental shelf these glacial maxima normally correspond to sea level low stands consequently ice sheets may be supported directly by the seafloor inducing increased pore pressures in the sediment and increasing the overall bearing stresses on the margin these stresses trigger undrained failure in upper slope sediment and bearing capacity failure in the middle to lower slope after complete ice melting and dissipation of excess pore pressure the inter glacial sediments become overconsolidated shear resistance is higher and no gravity or earthquake induced failure occurs the gravity events can only occur in underconsolidated and normally consolidated glacial and postglacial deposits this explains the variation in volume and activity of mass wasting events during low and high sea level periods in areas where a glacial ice exists analyses of maximum ice loading events are presented for the scotian slope in contrast with traditional thought these analyses suggest that ice loading rather than high sedimentation rates is the dominant mechanism for slope instability on glaciated margins

stratabound ore deposits related to synsedimentary tectonics south west sardinia italy and sierra de aracena spain a comparison deposition of stratabound zn pb ba ores in the lower cambrian carbonates in south west sardinia show a distinct relation with the prominent tensional tectonics in the area a part of the mineral deposits are syngenetic sedimentary exhalative other massive sulfides and or barite are early diagenetic other occurrences mvt are from early to late diagenetic they are mostly confined to matrix and cementbreccias which might be dependent on the cambrian tectonics

anatomy of an upper silurian transgressive regressive cycle prince of wales island arctic canada the ludlovian pridolian cape storm douro and somerset island formations on eastern prince of wales island form a transgressive regressive succession that developed on the western flank of the active boothia horst sedimentation took place in a series of fault bounded subbasins that were at different times characterized by abundant microbolites rhodolites brachiopods and organisms that produced a diverse array of ichnofossils integration of paleoecological information from this succession provides a multifaceted paleoecological model which can be applied to similar lithologically monotonous successions throughout the world three main factors controlled the distribution of biota through the transgressive regressive cycle the most obvious factor was ever changing depositional settings caused by progressive rise and fall in sea level superimposed on this general pattern however was the influence of water circulation and the influx of detrital quartz from the boothia horst the microbolites and

the survival recovery and diversification of metazoan reef ecosystems following the end permian mass extinction event abstract the triassic period records important ecological transitions in the aftermath of the end permian mass extinction and is a key interval in the evolution of modern coral reefs there have been several critical developments in our understanding of triassic reef evolution over the past decade the timing of events and duration of stages have changed dramatically the discovery of metazoan reefs in the early triassic details about the environmental perturbations that drove the extinction the relationship between tectonic activity and platform margin reef proliferation and additional proxy evidence for the co evolution of coral reef builders and their photosymbionts here we provide an up to date synthesis of reef collapse and recovery dynamics following the end permian extinction specifically integrating recent discoveries the evolution of reef ecosystems can be divided into five phases based on their composition 1 microbial metazoan reefs represent survival communities that characterize the immediate extinction aftermath 2 the re establishment of reefs built by metazoans small sponge biostromes and bivalve buildups is observed in oxygenated settings in the olenekian early triassic 3 towards the end of the olenekian and into the anisian middle triassic low diversity tubiphytes dominated reefs formed which represent the first triassic platform margin reefs platform margin reefs however are not widespread until the late anisian 4 late anisian reefs also record a composition change and increase in species richness with sponges and tubiphytes as the main reef builders 5 the first scleractinian corals which are the main reef builder in modern marine reef ecosystems evolved during the anisian but are not reported as dominant reef builders until the late triassic the radiation of coral reefs is posited to be coupled to the acquisition of photosymbionts e g zooxanthellae there is clearly a stepwise evolution of reef types during the triassic however once each reef type appears it persists throughout the remainder of the triassic the survival recovery and diversification of reef ecosystems is therefore more complex than previously outlined particularly with respect to the earliest post extinction ecosystems these recent advances highlight the need to thoroughly document the faunal compositions of understudied reef systems as well as to continue the exploration of triassic ecosystems in underrepresented regions

hypothesis combining dilation natural hydraulic fracturing and dolomitization to explain petroleum reservoirs in monterey shale santa maria area california abstract fractured reservoirs in the generally siliceous monterey shale of the santa maria area represent an anomalous lithology and type of fracturing some perhaps all are not fractured chert but parts of the monterey embrittled by dolomitization reservoir fractures unlike ubiquitous monterey fractures are mostly abundant disordered open extension fractures that commonly produce epigenetic dolomitic breccias these dolomite cemented breccias commonly contain open voids many of which are 15 cm across or larger breccias locally have an exploded appearance and contain some matched fragments separated by vein like or dike like matrix which apparently was an injected slurry of water and oil containing fragments of dolomite and dolomitic monterey shale the highly organic monterey also served as the source rock and probably originated as a rich diatomaceous slope sediment beneath an oxygen minimum zone the depositional site was much larger than the santa maria area and unconfined to silled basins local dolomitization may have been due at least in part to rising solutions and injected slurries the reservoirs are explained by a hypothesis involving repeated episodes of rock dilation followed by natural hydraulic fracturing all produced by episodic but continued tectonic compression of the region principal maximum effective stress oriented northeastward increasing fluid pressures enlarged underpressured dilation microfractures into macrofractures and produced breccias by hydraulic fracturing viscous oil expressed from indurated monterey was pumped into voids as part of overpressured slurries whose fragments were propping agents dolomite precipitated from slurries on pressure release by fracturing partly healing the fractures repetition of these events fractured additional rock so that the reservoirs grew outward and somewhat upward end of article last page 977

some aspects of the recent tectonics in the strait of messina italy abstract during pliocene and pleistocene times the strait of messina was subjected to extensional tectonism which was contemporaneous with marine sedimentary processes various tectonic sedimentary features created by this combination of processes are reviewed depocentres synsedimentary truncations and the association of sedimentary dykes related to extensional fissuring and hydraulic fracturing these features are regarded as characteristic accompaniments to extensional block faulting the recent structural evolution of the strait of messina margins provides an illustration of high magnitude vertical movements occurring within a short time interval the subsidence phase is related to fault movements which generate important fault scarps and sedimentary dykes phases of upheaval in contrast correspond to a general uplift of the margins unrelated to the local fault movements

an upper ordovician sponge bearing micritic limestone and implication for early palaeozoic carbonate successions abstract a potentially new type of non reef sponge bearing micritic limestone is reported from the upper ordovician xiazhen formation of south eastern china the sponges are preserved as incomplete skeletons that consist of curved bifurcated and trifurcated spicules embedded in dark micrite and can only be recognized under a petrographic microscope the characteristics of the spicule networks suggest that the sponges are probably belonging to demosponges however based on the absence of features such as desma zygome a distinct dermal layer and a canal system they are not considered to be lithistids the majority of the sponges are found in a lime mudstone facies together with some micritic portions of wackestone to grainstone facies comprising approximately 13 of the 50 m thick micritic limestone successions it is interpreted that the non lithistid demosponges flourished on soft substrates over shallow marine carbonate platform such sponge bearing carbonates are similar to spiculites and spongolites in terms of being a major constituent of the sedimentary rocks and their potential contribution as sediment producers but affinity and modes of preservation of the xiazhen sponges are significantly different to those of the spiculites and spongolites in light of the present finding it is suggested that non lithistid demosponges may have been more widespread in early palaeozoic non reef carbonates than has previously been recognized thus indicating the critical need for further detailed studies if we are to understand their distributions and sedimentological contributions

paleozoic echinoderm hangovers waking up in the triassic echinoderms are among the marine invertebrates that underwent the most severe losses at the end permian extinction the prevailing paradigm claims an extreme bottleneck with only very few if not single holdovers hangovers herein sparking the post paleozoic radiation here we identify previously overlooked triassic echinoids ophiuroids and asteroids as unambiguous members of paleozoic stem groups these echinoderm hangovers occurred almost worldwide and had spread into a wide range of paleoenvironments by the late triassic our discovery challenges fundamentals of echinoderm evolution with respect to end permian survival and sheds new light on the early evolution of the modern clades in particular on triassic ghost lineages i e inferred but undocumented fossil record of the crown group look alikes of the paleozoic hangovers

untangling intricate microbial sponge frameworks the contributions of sponges to early ordovician reefs abstract the early ordovician witnessed an increased influence of skeletal organisms on the construction of microbial dominant reefs which preceded the middle to late ordovician expansion of skeletal dominant reefs skeletal frameworks of early ordovician reefs built by stromatoporoids bryozoans pelmatozoans and calathiids have recently been reported in this study we document the occurrence of localized archaeoscyphia frameworks and additional unidentified non anthaspidellid spiculate sponges that played diverse roles in the construction of microbial siliceous sponge reefs preserved in the early ordovician dumugol formation korea which have not been previously described in coeval reefs elsewhere two types of boundstone textures are recognized microbial dominated boundstone and sponge microbial boundstone microbialites were primarily responsible for reef construction making up about one third of reefs both as framework builders and as encrusters of other reef components the archaeoscyphia and spiculate sponges contributed in various ways to reef development archaeoscyphia constituting about one fourth of the dumugol reefs mainly constructed sponge microbial boundstone together with encrusting microbialites clusters of archaeoscyphia individuals sporadically formed centimeter sized sponge framestone 3 of reefs with primary cryptic spaces spiculate sponges 4 of reefs a previously unknown component of early ordovician reefs also played diverse roles such as encrusting other constituents dwelling in cryptic spaces stabilizing reef flank sediments and even building frameworks such framework building siliceous sponges together with previously reported skeletal frameworks in other early ordovician reefs reflect an early phase of the transition from microbial to skeletal dominated reefs in the early paleozoic

chaotic breccia along the dent fault nw england implosion or collapse of a fault void a body of chaotic breccia along the reverse oblique dent fault zone is ascribed to hanging wall collapse into persistent voids created by geometric mismatch of fault walls although some implosion into transient voids is a possibility the breccia comprises a 20 m wide body of hanging wall lithologies with a chaotic clast supported fabric that contrasts with the fitted fabric breccias typical of the dent fault damage zone the breccia body has crude bedding defined by clast shape and size contrasts the void fill is cut by variscan fault strands which together with its ferroan calcite and barite cement prove its late carboniferous rather than recent age it is shown that any fault void transient or persistent had a smaller aperture than the final width of the breccia body and no more than 5 m a span that can be supported to depths of 2 or 3 km however cement zonation in the breccia fill suggests that the void opened in multiple increments each of an aperture compatible with the maximum displacement in any one event along the dent fault the dent fault example highlights the possible general importance of fault void collapse but also the problems in distinguishing it from implosion processes

deep water hexactinellid sponge mounds from the upper triassic of northern sichuan china a belt of upper triassic carnian sponge mounds was discovered in northern sichuan in the transition zone between a shallow shelf sea in the se chuan dian shelf and a deeper marine trough ganzi aba trough in the nw individual sponge mounds are up to 60 m high and 150 m wide and interfinger laterally with dark shales main frame builders of the mounds are lychniscosa and lyssacinosa accompanied by much rarer hexactinosa lithistida annelid worms occasional crinoids and bryozoa the reef dwelling fauna consists of brachiopods ostracods foraminifera pelecypods gastropods and ammonites typical shallow water reef builders scleractinian corals and calcareous algae are lacking or extremely rare coralline sponges this supports the interpretation of the mounds as buildups in deeper water of several tens up to one hundred meters the sponge mounds of northern sichuan are thus an equivalent of similar buildups of late jurassic age in central and western europe they provide the first well established record of lychniscosa in the triassic and their first reported pre tertiary occurrence outside of europe

morphodynamic response of nearshore bars to a shoreface nourishment abstract the autonomous nearshore bar behaviour along the barrier island of terschelling the netherlands is characterised by the presence of net seaward cyclic migrating sand bars generated near the shoreline in 1993 a perturbation of the cyclic bar system was introduced by the implementation of a 2 mm 3 shoreface nourishment supplied to the nearshore bar zone filling up the trough between the middle and outer bar the morphodynamic response of the nearshore bars to the nourishment perturbation is investigated using a bathymetric data set with an alongshore extent of 12 km and sampled for 10 years bar behaviour is quantified in terms of bar crest position in relation to morphometric parameters such as bar depth height width and volume along with a pronounced development of a three dimensional bar system unseen in the autonomous behaviour the nearshore bars exhibited a 6 7 year arrest in their migrational behaviour during which bar morphology remained stable at immediate pre nourishment morphometric values at the subsequent onset of bar movement bars resumed their migration at a rate predicted by autonomous behaviour in parallel development with morphometric parameters along their predicted trends it is shown that the observed onshore transport of nourished sediment in the 6 7 year arrest results from a gradual deepening of troughs cross shore sediment transport modelling is used to assess the effect of the nourishment on yearly averaged onshore short wave nonlinearity and offshore undertow sediment transport rates the gradual reappearance of the pre nourishment bar trough morphology is shown to engender a normalisation in the cross shore distribution of sediment transport rates to pre nourishment rates

depositional architecture of a rimmed carbonate platform albian gorbea western pyrenees a lower cretaceous carbonate platform depositional system with a rimmed margin and an adjacent oversteepened slope was analysed in order to determine its depositional architecture and major depositional controls the platform is made up of coral rudist orbitolinid and algal limestones and in a 12 km dip transect there is a gradation from lagoon to platform margin slope and basin environments each characterized by distinctive sedimentological features and facies associations the rimmed platform is an aggradational system developed during approximately 4 2 million years of fluctuating relative sea level rise and it is bounded by unconformities at its base and top internal cyclicity in the construction of the system is evident mainly in platform interior and slope settings the seven recognized sequences average 0 6 million years in duration and are related to minor relative sea level changes carbonate deposition occurred in shallow and deep water settings during periods of high relative sea level reduced rates of sea level rise led to the development of shallowing upward sequences and eventually to the exposure of the shallowest parts of the platform during relative sea level falls during low relative sea level erosion surfaces developed on the slope and gravitational resedimentation occurred at the toe of slope basinwards resedimented units pinch out over distances of a few hundred metres active faults controlled sedimentation at the platform margin promoting the development of steep slopes up to 35 and preventing progradation of the shallow water platform despite high sediment production rates the development of sequences is interpreted to be related to tectonic activity

lower cambrian cavity dwelling endolithic boring sponges in the lower cambrian forteau formation middle bonnia olenellus zone of southern labrador cavities in archaeocyath patch reefs contain preserved coelobiontic endolithic sponges scallops and carbonate chips produced by sponge boring spicules and preserved endolithic sponge body fossils all point to the presence of endolithic sponges in lower cambrian reef cavities the oldest previously described endolithic sponges are early ordovician in age and the oldest previously known reef interior bioerosion is middle ordovician in age the presence of endolithic sponges in reef cavities of the forteau formation therefore extends both the record of endolithic sponges and of reef interior bioerosion from the ordovician to the upper lower cambrian

preliminary phanerozoic polar wander paths for the north and south china blocks polar wander paths for the north and south china blocks suggest that 1 both were parts of gondwana in the palaeozoic 2 the north china block accreted to siberia in the late permian and 3 the south china block accreted to the north china block in the middle triassic to the early jurassic comparison of the polar wander path for the south china block with that for northern eurasia suggests that relative motion of over 4 000 km has occurred between them

full scale monitoring study of a submerged breakwater palm beach florida usa abstract in an attempt to reduce beach erosion and wave impact on a protective seawall an experimental proprietary submerged breakwater reef of 1 260 m length was installed in a water depth of approximately 3 m off the town of palm beach florida to provide a basis for evaluating the effects of this installation a comprehensive field monitoring program was carried out and included wave measurements beach and offshore profiles settlement of the units local scour data and information related to the background coastal processes the system consists of 330 units 57 of which were installed in the summer of 1992 and the remainder in the summer of 1993 monitoring surveys available up to june 1995 are presented herein the wave height reduction attributable to the reef ranges from 5 for the lower waves and higher tides to 15 for the higher waves and lower tides the profile data documented erosion in the entire monitored area with the greatest erosion landward of the reef changes in profile data were consistent with and are interpreted as due to water conveyed over the submerged breakwater as mass transport a partial ponding of this water due to its return flow being impeded by the presence of the breakwater resulting in a portion being redirected as longshore currents these longshore currents transport sand from landward of the breakwater with deposition occurring near the south end of the system in the direction of the predominant natural transport although these breakwater induced longshore currents were not documented in the monitoring program the mechanisms are supported by the patterns of erosion and deposition by a model study carried out to evaluate installation of a submerged breakwater at a different location and by previous documentation and discussion of the phenomenon in the available literature results obtained here are interpreted in terms of design implications

wave transmission and reflection at low crested structures design formulae oblique wave attack and spectral change abstract a part of the delos research focused on wave transformation at low crested structures called lcs this paper gives a summary of all results wave transmission on rubble mound structures has been subject for more flume tests in the delos programme and simultaneously an existing database has been increased extensively by receiving data from other researchers in the world this new database consists of more than 2300 tests and has been used to come up with the best 2d wave transmission formula for rubble mound lcs although not necessarily new as existing ones have been evaluated oblique wave attack on lcs was a second objective within delos results were analysed leading to new empirical transmission formulae for smooth lcs and to conclusions on 3d effects for both rubble mound and smooth lcs the spectral shape changes due to wave transmission and this change has been subject of analysis for all new test data described above although analysis has not been finished completely former assumptions on spectral change were more or less confirmed finally some analysis was performed on reflection at lcs and a first formula was derived to take into account the effect that wave overtopping or transmission reduces reflection and must be dependent on the crest height of the structure

cephalopod limestone deposition on a shallow pelagic ridge the tafilalt platform upper devonian eastern anti atlas morocco as a result of early variscan tectonic movements and of differential subsidence a platform and basin topography was created along the northern margin of the sahara craton during the late devonian in the moroccan anti atlas mountains the tafilalt platform is an approximately n s running ridge which developed since the late middle devonian it separated a slowly subsiding shallow basin in the east tafilalt basin from a rapidly subsiding furrow in the west mader basin platform deposits are characterized by highly reduced thicknesses shallow subtidal to supratidal deposits in the late frasnian and by unconformities at the lower upper frasnian and the frasnian famennian boundaries after a local transgression over emergent areas in the north water depth probably never reached more than several tens to about 100 m in the lower famennian cephalopod limestones of this age deposited on the platform represent a very diverse facies pattern comprising quartz rich brachiopod coquinas crinoidal limestones thick bedded cephalopod limestones and nodular limestones sedimentation rates ranged from 1 to 5 mm 1000 yr in the late famennian more uniform marl and nodular limestone facies suggest slightly deeper environments platform margins are characterized by higher rates of subsidence debris flow deposits and slump structures in the relatively shallow tafilalt basin marls with intercalated nodular limestones were deposited in the mader basin sandy and calcareous turbidites suggest deeper water conditions in the late devonian during the strunian tournaisian the whole area was overwhelmed by a thick deltaic sequence the general facies distribution is in agreement with depositional models of other upper devonian and lower carboniferous cephalopod limestones in the european variscan orogenic belts in all these cases condensed cephalopod limestones occupy a distinct palaeogeographic position in predictable facies sequences that reflect pre orogenic phases in the variscan geodynamic cycle moreover close parallels exist with condensed sequences in the triassic and jurassic that occur in a very similar position within the alpine orogenic cycle

middle cambrian siliceous sponge calcimicrobe buildups daegi formation korea metazoan buildup constituents in the aftermath of the early cambrian extinction event abstract numerous decimetre to metre scale carbonate buildups dominated by siliceous sponges and the calcimicrobe epiphyton are reported from the middle cambrian series 3 daegi formation of korea these siliceous sponge epiphyton buildups consist predominantly of grey micritic boundstones with dark clots and or white clumps the boundstones contain sponge spicule networks interpreted as the calcified remains of siliceous sponges the white clumps and dark clots in the boundstones represent variously preserved epiphyton siliceous sponges form constructional pore space and are commonly encrusted by epiphyton the sponges were probably the primary frame builders providing substrates for the attachment and subsequent growth of epiphyton epiphyton is considered to be a binder when covering the surface of siliceous sponges and a subordinate frame builder when filling depositional voids created by siliceous sponges or growing on top of other epiphyton growth bundles the siliceous sponge epiphyton buildups of the daegi formation show similarities to previously described late cambrian furongian anthaspidellid calcimicrobe buildups from iran and the usa together with recently reported examples from the zhangxia formation of eastern china the sponge epiphyton buildups from korea represent some of the oldest metazoan calcimicrobe buildups after the extinction of most archaeocyaths at the end of the early cambrian series 2 this implies that the incorporation of metazoans in middle cambrian series 3 carbonate buildups occurred much earlier than previously known the buildup forming siliceous sponges described in this study demonstrate that their role in early phanerozoic carbonate buildups has been grossly underestimated

cross shore suspended sediment transport in the surf zone a field based parameterization existing cross shore sediment transport models for two dimensional surf zone bathymetries almost invariably predict offshore directed sand transports and bar migrations during storm conditions however onshore directed suspended sediment fluxes and associated nearshore bar migration were observed during recent field experiments on a gently sloping beach on the danish north sea coast field measurements of suspended sediment flux obtained during three experiments on two different beaches are used to parameterize the observed fluxes this parameterization predicts suspended sediment transport due to incident waves and undertow across bars in two dimensional surf zones first a non dimensional sediment flux index is formulated which describes the tendency towards net onshore or offshore transport and the strength of that tendency the non dimensional formulation circumvents the problem of measurement inconsistencies due to varying elevations of sediment concentration sensors relative to the bed the index is found to depend upon the undertow velocity the incident wave skewness and the cross correlation between orbital velocity and sediment concentration however some of these parameters are difficult to predict particularly in barred surf zones and therefore the independent variables are recast in terms of a set of more easily obtainable parameters the sediment flux index depends on a combination of the following non dimensional bed shear stress the shields parameter relative water depth wave orbital velocity relative wave height and bed slope finally a formulation of suspended sediment transport across bars is obtained by linking the flux index with a parameterization of the sediment concentration distribution in the water column these concentrations are found to depend on non dimensional bed shear stress relative wave height and water depth the formulation predicts a tendency for onshore directed sediment transport due to incident waves on gently sloping beaches and or with large bed shear stresses on steeply sloping beaches and or in the inner part of the surf zone there is a tendency towards offshore sediment transports due to the undertow

morphodynamic response of a two barred beach to a shoreface nourishment abstract the response to a shoreface nourishment of the two bar system at noordwijk the netherlands is analyzed based on a daily data set of time exposure video images collected during about 6 years complemented with topographic and bathymetric surveys the 1 7 mm 3 nourishment implemented as a 3 km alongshore bump seaward of the outer bar migrated more than 300 m onshore in 4 years before losing its integrity furthermore the nourishment interrupted the autonomous seaward migration of both bars for the entire duration of the study period and allaying earlier fears did not intensify the three dimensional patterns in the bars such as the crescentic plan shape and rip channels the nourishment did result in clear head effects on both flanks with the bar becoming discontinuous and the flank section decaying or becoming attached to an offshore located bar while the section of bar landward of the nourishment became attached to a landward located bar this sequence of morphologies is known as bar switching each switching episode took almost one year to complete and can therefore not be ascribed to individual wave events we suspect that shoreface nourishments enhance the possibility of bar switching by creating alongshore variability in the position and depth of the outer bar and in its cross shore migration rate and direction the noordwijk nourishment did not influence the shoreline position as its trend did not undergo distinctive variations after 1998 differences in the response of the noordwijk sandbars to the shoreface nourishment compared with other dutch nourishments are attributed to the location and size volume per unit length of the nourishment with respect to the sandbars and to the median grain size of the nourished material

platform slope transition during rifting the mid cretaceous succession of the amasya region northern anatolia turkey abstract the mid cretaceous rocks of the amasya region north central anatolia record the geological processes that occurred during the break up of the eastern pontide carbonate platform which existed from mid jurassic to early cretaceous the mid cretaceous sedimentary rocks consists of benthic foraminiferal packstones grainstones of ferhatkaya formation and limestone breccias turbidites pelagic foraminiferal wackestones packstones and radiolarites of sarilar formation corresponding to platform and slope apron environments respectively the lithological development of these units was controlled mainly by active subsidence due to block faulting affecting the eastern pontide carbonate platform due to the break up of the platform during late barremian early aptian times slope and basin sediments were deposited on the deeper parts of the platform re deposited sediments such as limestone breccias and calciturbidites document the infilling of asymmetric grabens during the mid cretaceous rifting phase re deposited sequences which were formed as a fault slope apron sedimentary prism related to this rifting were deposited during thinning and fining upward megacycles a typical megacycle commences with breccias deposited at the base of a fault scarp association in addition the upper part of the platform carbonates ferhatkaya formation includes neptunian dykes composed of red mudstones with pelagic fossils indicating a period of extension

tectonic controls of phanerozoic sedimentary rock cycling the cyclic nature of the phanerozoic sedimentary rock distribution carbon sulphur coupling and material transfer among sedimentary reservoirs appears to be controlled by tectonic factors the distribution of preserved sedimentary mass in terms of rock mass remaining u geologic age shows a minimum c 300 350 ma ago which separates two subcycles of erosion and deposition of sedimentary rocks the older subcycle was interrupted because of the major continental collisions of the devonian and late carboniferous these collisions resulted in a reduction of outcrop areas of rocks of the older cycle relative to their masses leading to a decline in the probability of destruction and an increase in half life of these older sediments a strong correlation exists between the long term cyclicity in the phanerozoic global sea level curve and the distribution of carbon and sulphur among their major exogenic reservoirs this correlation is related to two principal tectonic modes of the phanerozoic oscillatory and submergent it is postulated that the submergent mode of active plate convergence obduction and subduction of sediments large ridge volume and high sea level gave rise to low erosion and sedimentation rates less restricted environments of carbonate deposition and relatively high atmospheric co 2 levels high temperatures resulting from an increased rate of production of co 2 from diagenetic and metamorphic reactions at subduction zones as sea level rose carbon was transferred from the sedimentary reservoir of reduced organic carbon to that of oxidized inorganic carbon in limestones whereas sulphur moved from the oxidized sulphate reservoir to the reduced sulphide reservoir as sea level fell reservoir transfers were opposite to those above culminating in the oscillatory mode of generally elevated continental interiors these reservoir transfers are consistent with secular changes observed in the distribution of 13 c and 34 s in sedimentary materials during the phanerozoic petrographic examination of phanerozoic oolite formations shows that ooids with preserved calcitic relict textures are characteristic of pre carboniferous carbonate rocks whereas ooids with relict textures indicative of initial aragonite mineralogy are dominant in rocks of younger age these changes in ooid mineralogy may be interpreted as reflecting changes in co 2 levels of the ocean atmosphere system consistent with the above tectonic considerations atmospheric co 2 levels were higher prior to carboniferous time favouring formation of calcitic ooids and skeletal parts after the carboniferous co 2 levels fell and aragonite and mg calcites of greater than 8 mol mg increased in abundance as precipitates

palaeogeographical influence on late eocene biosiliceous sponge rich sedimentation southern western australia late eocene nearshore shallow marine environments within the bremer and western eucla basins of southern western australia were characterized by the thick deposition of spongolite and spiculite deposits epibenthic sponge communities dominated estuaries and topographically complex basin margin embayments archipelagos while cool water carbonates with up to 10 sponges accumulated in open shelf environments the transition from a biosiliceous to calcareous epibenthos was related to the degree of palaeogeographical protection within basement protected embayments there was an offshore gradation from shoreface spongolite and pure spiculite to a muddy spiculite facies towards central embayment areas calcareous fossils are rare throughout embayment facies but rapidly increase in more open outer archipelago areas this depositional relationship occurred along 2000 km of the late eocene southern australian coastline palaeogeographical protection from strong currents acted in concert with 1 a planar low gradient inland topography with sluggish run off supplying fine grained sediment nutrients and abundant dissolved silica and 2 a microtidal setting weak to moderate swells and opposing wind and coriolis surface current forcing which inhibited water exchange between embayments estuaries and the open shelf this situation led to an embayment water chemistry that encouraged prolific sponge growth calcareous spiculites record the mixing front between these embayment waters and normal open shelf waters supporting cool water carbonates

demise of late triassic sponge mounds along the northwestern margin of the yangtze block south china related to the carnian pluvial phase upper triassic carnian marine successions in the northwestern margin of upper yangtze region sichuan basin china show a lithological change from grey oolitic into a sponge mound limestone units 1 and 2 of the lower member of the ma antang formation then overlain by greyish black to dark grey sandy shale and siltstone units 3 and 4 of the upper member of the ma antang formation siliceous sponge mounds were built by hexactinellida and this succession was examined in three localities jushui section in anxian js and guanyinya hwg and qingyangou sections hwq in hanwang mianzhu the conodont quadralella polygnathiformis confirms a carnian age for the biolithite and oolitic limestone of the lower ma antang formation abundant ammonoids identified as belonging to the discotropitid and juvavitid families suggest a tuvalian 1 early late carnian age for the lowermost part of the greyish black sandy shale that overlies the sponge mound at the jushui section field investigations and microfacies analysis suggest that sponge mounds had two stages of growth in relatively deeper water with low energy the first sponge growth mound stage ended in a regional karstified omission surface and was followed by a sudden increase of siliciclastic input greyish black shales containing plant fossils cover a second upper carnian sponge mound stage which is mainly recorded in hwg the onset of these shales may be related to the carnian pluvial phase cpp documented in the western tethys region e g in italy austria and hungary the demise of the sponge mounds at all three sections may have been triggered by the joint effect of climatic changes associated with the fresh water input caused by cpp and with a relative sea level change caused by local tectonic movements in the course of the indosinian orogeny

wave overtopping and induced currents at emergent low crested structures abstract this paper deals with wave overtopping associated to low emergent detached breakwaters it starts presenting the various mechanisms which define the functional behaviour of detached breakwaters which are frequently overtopped the emphasis is on the role played by overtopping and how this contributes to the wave pumping in the area around the structure the paper then reviews the available formulations for predicting overtopping considering the sensitivity of various equations to climatic drivers and their suitability for low crested coastal structures the paper then analyzes nearshore circulation models and how overtopping discharges can be included this is illustrated with a sample q 3d model by analyzing the differences obtained with without overtopping the emphasis is on the implications for the functional design of the structure and its morpho hydrodynamic impact the main conclusion is the sensitivity of the functional design of such structures to the underlying hydrodynamics processes and the importance to explicitly include overtopping for numerical simulations of the morpho hydrodynamic behaviour of low crested breakwaters

connecting large scale coastal behaviour with coastal management of the rhone delta abstract the aim of this paper is to connect the large scale coastal behaviour lscb of the rhone delta shoreface sediment budget river sediment input to the beaches climatic change with the impact and efficiency of hard engineering coastal structures the analysis of the 1895 to 1974 bathymetric maps as well as 2d modelling of the effect of wave blocking on longshore transport allows us to draw up a conceptual model of the lscb of the rhone delta the river sand input settled in the mouth area prodeltaic lobe favours the advance of adjacent beaches there is however a very weak alongshore sand feeding of the non adjacent beaches farther off the mouth after a mouth shift the prodelta is eroded by aggressive waves and the sand is moved alongshore to build spits this conceptual model suggests that there is a timeshift between the input of river sediments to the sea and the build up of a beach nonadjacent to the mouth nowadays as the river channels are controlled by dykes and human interventions a river shift is not possible it thus appears unlikely that the river sediments can supply the beaches of the rhone delta coast under these conditions we must expect that the problems of erosion will continue at saintes maries de la mer and on the faraman shore in areas with chronic erosion where the shoreline retreat has been partially stopped by hard engineering practices in the 1980s therefore these artificially stabilised sectors remain potentially under threat because of profile steepening and downdrift erosion evidenced in this paper by bathymetric profile measurements in the long term 1905 to 2003 the temporal analysis of the storm surges and the sea level show very weak but reliable increasing trends thus these climatic agents will be more aggressive on the beaches and on the coastal structures calling their efficiency into question we also evidence that the hard engineering structures were built in a favourable climatic context during the 1980s meanwhile the storm surges and the sea level rise are stronger since the 1990s regarding to the lscb of the rhone delta and the impact of hard engineering coastal structures we suggest that classical hard coastal protections are not the best option to protect the coast

active fault hazard in southern california ground rupture versus seismic shaking there are exceptions to the common assumption that surface rupture by faulting is always accompanied by a damaging earthquake near ventura california faults of the oak view ojai area and orcutt and timber canyons displace late pleistocene and or holocene alluvial materials and soils by several tens of metres the movement is almost exclusively along bedding planes in response to flexural slip during folding therefore these faults constitute a ground rupture hazard however because they do not extend downward to rocks of high shear strength which could store large amounts of elastic strain energy they do not constitute a seismic shaking hazard in contrast the oak ridge fault near the coast does not cut strata shallower than 1 250 to 1 500 m below the surface although pressure ridges attest to recent activity similarly the newport inglewood fault between long beach and inglewood oil fields in the los angeles basin is expressed at the surface as a line of anticlinal hills rather than a throughgoing fault historical faulting at inglewood and possibly at rosecrans and dominguez oil fields may be related to oil field development rather than earthquake related displacement those portions of the oak ridge and newport inglewood faults pose seismic shaking hazard but not ground rupture potential from earthquakes alone for planning purposes it is necessary to distinguish faults with only ground rupture potential or with only seismic shaking potential from the well known faults with potential for both

preservation of siliceous sponges in the jurassic of southern england and northern france reef forming lithistid sponges in the middle jurassic bathonian of normandy france were lithified on the sea floor by a peloidal cement probably of an original low mg calcite composition precipitated under bacterial influence this early lithification permitted early dissolution of the siliceous skeleton without the collapse or distortion of the resulting moulds these moulds were encrusted and bored this pathway for the fossilization of sponges is shown by other examples of jurassic lithistids and is likely to be widely applicable throughout the fossil record particularly at times during which calcite was the primary marine precipitate

process based modelling of a shoreface nourishment abstract a state of the art process based model is applied to hindcast the morphological development of a shoreface nourishment along the barrier island of terschelling the netherlands the applied morphodynamic model is delft3d for fully three dimensional flow and sediment transport in coastal environments owing to a complex geomorphological setting of the study area the curvi linear model includes adjacent tidal inlets and covers 40 70 km with an increasing grid size resolution towards the nourishment site in the center of the island in 1993 a total of 2 mm3 of sand was supplied to the nearshore bar zone off terschelling filling up the trough between the middle and outer bar by spring 1994 most of the nourished sediment had been redistributed onshore and welded onto the middle bar where it remained in the following years the morphodynamic model is applied to the prediction of this rapid nearshore profile behaviour the calibration of the model against an extensive set of full scale hydrodynamic data at several locations throughout the nearshore bar zone shows a good representation of the measured hydrodynamics morphodynamic results show a dependency on spatial scale on the scale of precise bed level evolution with respect to bar migration and growth model predictions are poor as the nearshore bars are predicted to flatten out resorting to bulk volumes integrated over larger spatial scales the model clearly has skill in predicting the overall effects of the nourishment the lack of phase shift between sediment transport and bathymetry is identified as the key controlling factor for the poor sandbar predictions