hydrological and post depositional impacts on the distribution of holocene archaeological sites the case of the holocene middle rhone river basin france on a landscape scale the location of archaeological sites strongly influences their potential for preservation the recent progress made in the acquired knowledge of the rhone river basin palaeodynamics occurring simultaneously to the development of intensive rescue archaeological surveys on fluvial plains provides information on the burying and post depositional processes of archaeological records for all of the holocene cultural phases even if the lowlands have traditionally been seen as having lower population densities and are dominated by late holocene sediments the systematic exploration of the soil archives has revealed that the archaeological potential was concentrated in the lower alluvial plains and the alpine foothill river fans the taphonomic corrections and correlative predictive model carried out under gis have changed our perception of the settlement history of the northwestern mediterranean region they put in doubt some initial settlement patterns some chronocultural hiatuses based on preconceived models of land use especially for the first neolithic and the protohistoric periods

maturation and bulk chemical properties of a suite of solid hydrocarbons abstract in this paper we present strong correlations of solid hydrocarbon reflectance shro to vitrinite reflectance vro and bulk chemical properties aromaticity tmax h c etc these correlations suggest that like kerogen in coals and sedimentary rocks solid hydrocarbons vary systematically during maturation as a consequence shro is especially useful as a maturity indicator in rocks lacking vitrinite such as pre devonian rocks and many organic rich marine rocks unlike other organic maturationv indicators the utility of solid hydrocarbons is not limited by botanical evolution but rather the generative potential of the petroleum system solid hydrocarbons also known as solid bitumen asphalt dead oil migrabitumen and pyrobitumen are genetically defined as solid phase accumulations of predominantly hydrocarbons produced by petroleum generation in source rocks they may occur over a range of concentrations in outcrop and well samples in all components of petroleum systems although accumulations of solid hydrocarbons from exhumed reservoirs are well reported the extent and utility of disseminated solid hydrocarbons in shales is less understood solid hydrocarbons are found in organic rich to very lean mature rocks as a residual product of generation disseminated solid hydrocarbons exhibit three optical forms anisotropic coked granular and relatively uniform homogenous only the homogenous solid hydrocarbons are recommended for correlation purposes with other thermal indicators

petrology of graptolites and their utility as indices of thermal maturity in lower paleozoic strata in northern yukon canada abstract the optical characteristics and utility of graptolites as a measure of thermal maturity have been evaluated by measuring maximum minimum and random reflectance of specimens from the lower paleozoic road river group in northern yukon the progressive changes in optical properties of graptolites produced by increasing depth of burial are corrected to the optical properties of other organic matter conodonts and bitumen in the same sample measurement of maximum reflectance ro max is the most reliable method of assessing the level of thermal maturity of gratolites because they have biaxial optical properties at high levels of maturation the reflectance of graptolites is greater than that of vitrinite whereas at low levels of maturation the reflectance of vitrinite is greater in the road river group the mean maximum reflectance of graptolites varies laterally from 4 0 to 6 5 ro max rrmomax f graptolites increasing depth of burial and the relationship between reflectance and depth fits a log reflectance linear depth relationship the vertical increase of maximum reflectance of graptolites through an 800 m section ranges from 4 2 ro max at the top to 6 5 ro max at the bottom yielding a maturation gradientof 0 39 log romaxkm 1 a correlation of graptolite reflectance calibrated by color changes of conodonts cai indicates that road river strata are overmature cai 5 4 0 6 5 ro max graptolite reflectance with respect to hydrocarbon generation

petrographic and geochemical composition of kerogen in the furongian u cambrian alum shale central sweden reflections on the petroleum generation potential abstract this paper presents an integrated geochemical and petrological study of the hallekis 1 core from the furongian upper cambrian alum shales in central sweden to characterise organic matter composition depositional environment and potential hydrocarbon generation capability the results show that organic rich alum shale toc 8 9 28 0 wt contains mainly immature predominantly algal derived kerogen with unusually reduced hydrocarbon generation potential as suggested by relatively low hydrogen index hi values hi 251 471 mg hc g toc and high degree of aromaticity in the absence of thermal generation of hydrocarbons in these immature shales the recorded low hi values are explained by an unusual chemistry of the biota during the deposition of the alum shale accentuated by a high degree of sustained bacterially mediated degradation e g sulphate reduction and possibly intense nuclear degradation of labile kerogen by radiation from uranium rich minerals the higher degree of aromaticity in alum shale suggests lower than expected oil proneness the results of this study suggest that the alum shale is a gas prone source producing aromatic hydrocarbon mixtures with an unexpectedly low concentration of n alkanes

carbonate ramp drowning caused by flexural subsidence the south pyrenean middle eocene foreland basin abstract a detailed sedimentological and magnetostratigraphic analysis of three selected sections of the eocene carbonate platforms of the south pyrenean jaca pamplona foreland basin has been carried out in the aragonese external sierras huesca spain the stratigraphic record spans from the middle late lutetian chron 20r sbz15 to the bartonian chron 18r sbz17 the lutetian bartonian transition was characterized by a major paleogeographic change from a turbiditic foredeep with associated peripheral carbonate ramps to deltaic sedimentation in most of the outcrops of the external sierras the peripheral carbonate platforms guara formation are overlained by prodelta and outer ramp marls arguis formation the drowning unconformity between these two formations in the outcrops located in the westernmost tip of the external sierras is documented herein for the first time in this area the guara formation is overlain by glauconitic limestones deposited in a carbonate ramp setting between these units a characteristic unconformity is observed with hard ground formation and local evidence of subaerial exposure in the shallowest domains of the study area the abundant glauconite found on top of this unconformity records a starvation period in the basin followed by the development of a new carbonate ramp system during bartonian times santo domingo member of the arguis formation magnetostratigraphic and sedimentological data show that tectonic tilting occurred in latest lutetian times prior to the drowning process this suggests the influence of the flexural subsidence in the cratonic margin of the foreland as a result of the advance of a basement thrust in the hinterland nevertheless the correlation of the uppermost lutetian drowning unconformity with a basinwide regional sea level rise which may have further been global suggests an interplay between tectonic and eustatic processes in the drowning of the late lutetian south pyrenean carbonate ramps in this work we point out a narrowing of the carbonate ramp together with a relative sea level rise as the processes responsible for the drowning of the upper guara mb carbonate ramp these processes could be responsible for the development of drowning unconformities in cratonic margins of other foreland basins as carbonate ramps have a high sediment production potential the narrowing of the carbonate factory could provide the conditions for the drowning of the carbonate ramp system in a subsequent sea level rise

magnetic susceptibility of soil an evaluation of conflicting theories using a national data set magnetic susceptibility values for topsoils across england arc combined with data for soil type geochemistry and concentrations of magnetotactic bacteria in order to evaluate different theories for explaining soil magnetism strongly magnetic soils in unpolluted areas are found over weakly magnetic substrates and are dominated by ultrafine superparamagnetic grains magnetotactic bacteria are present in insufficient concentrations to account for strongly magnetic soils and crop burning is discounted as a major factor a small number of samples show high values associated with either airborne magnetic particulates from pollution or residual primary ferrimagnetic minerals from igneous substrates the results are used to construct a new mechanism for the formation of secondary ferrimagnetic minerals that links abiological weathering and biological fermentation processes the fundamental driving force in the mechanism is fe supply which may be linked to climate observed causative associations between climate and the magnetic susceptibility of loess palaeosol sequences are supported by the findings

preliminary organic petrography of palaeozoic rocks from the grand banks newfoundland abstract samples of lower palaeozoic bedrock from the grand banks of newfoundland were examined using reflected light microscopy and rock eval pyrolysis these samples contained organic material which included bitumen structureless organic material acritarchs chitinozoa scolecodonts and graptolites the reflectance of the organic material increased from acritarchs towards graptolites with bitumen showing a wide range of reflectance multiple phases of oil migration through one sample were inferred by examination of the bitumens the lowest reflecting being more recent than the highest reflecting bitumen combined reflectance and rock eval analysis indicate that these samples are mature to overmature the two oldest samples arenig llanvirn ordovician are assessed as mature and as having potential for generation of liquid hydrocarbons but must be considered as mainly gas prone

multikilometer sized reefs built by foraminifera solenomeris from the early eocene of the pyrenean domain s france n spain palaeoecologic relations with coral reefs abstract solenomeris foraminifera reefs of the early ypresian pyrenean gulf were previously mistaken for red algal or incertae sedis algal reefs solenomeris has recently been referred to the acervulinid foraminifera these foraminifera buildups are described in detail and their palaeoecology is discussed the distribution of these reefs within the languedoc basin demonstrates their preference for bathymetric highs of external platforms in common with coral reefs to which they locally succeed during the early ypresian transgression all solenomeris reefs examined are located either at the outer periphery of a lagoon with small operculina or on the external margin of a carbonate platform characterized by various miliolida they extend into deeper waters than the associated coral reefs even in turbid environments unfavourable for encrusting coralline algae the reconstruction of the palaeoecology of solenomeris shows many similarities with corals however corals probably require higher light and oxygen levels especially when present near their northern limit the global distribution of solenomeris reefs can not be established until their correct identifications have been made instead of algal reefs

graptolites as indicators of the temperature histories of rocks a pilot study of the optical properties of graptolite skeletal materials shows progressive changes of reflectance bireflectance refractive index and absorptive index produced by temperature changes related to depth of burial samples of lower ordovician to upper silurian graptolites were selected from across canada from locations where the conodont alteration indices of adjacent conodont collections provide a control index of temperature the reaction to temperature of graptolite skeletal material appears to be similar to that of bitumen but somewhat different to that of the vitrinite and liptinite maceral components of coal maximum reflectance in oil and bireflectance appear to be the characteristics most diagnostic of maximum temperature and both show progressively higher rates of increase at higher temperatures these factors show potential for more sensitive discrimination of temperatures at high levels of conodont alteration indices the optical properties of graptolites may perhaps provide a useful tool for unravelling the post depositional histories of lower palaeozoic rocks in deformed belts

high resolution fluvial records of holocene environmental changes in the sahel the yame river at ounjougou mali west africa abstract the yame river in the bandiagara plateau dogon country mali is characterised by extensive alluvial sedimentary records particularly in the 1 km long ounjougou reach where holocene floodplain pockets are inset in the pleistocene formations these alluvial records have been investigated via geomorphologic fieldwork and sedimentologic and micromorphologic analyses and are supported by 79 radiocarbon dates the alluvial deposits of the valley floor correspond to a vertical accretion of 3 10 m the reconstruction of fluvial style changes provides evidence of four main aggradation periods from 11 500 to 8760 cal bp the alluvial architecture and grain size parameters indicate a wandering river this period included phases of pulsed high energy floods and avulsion related to a northward shift of the summer monsoon to around 14 n after 11 500 cal bp from 7800 to 5300 cal bp a swampy floodplain environment with standing water pools within a sudanian savanna woodland mosaic corresponds to the culmination of the holocene humid period from 3800 cal bp onwards rhythmic sedimentation attests to an increase in the duration and or intensity of the dry season giving a precise date for the local termination of the holocene optimum period during the last two millennia and for the first time during the holocene the alluvial formations are progressively restricted whereas the colluvial deposits increase indicating strong soil erosion and redeposition within the watershed related to an increase in human impact four major periods are characterised by incision i1 ante 11 500 i2 8760 7800 i3 6790 6500 cal bp i4 2400 1700 cal bp pointing to dramatic changes in fluvial style they result from high energy flood flows during dry spells and confirm the capacity of the floodplain pocket in the upstream reach of the sahelian belt to record rapid holocene climatic change

post oil solid bitumen network in the woodford shale usa a potential primary migration pathway abstract an important if not predominant component of porosity in many gas shales has been identified in organic matter an organic network in shales has been described in the literature as organic matter generalized term kerogen primary or bitumen secondary recognition of the type and origin of an organic network in shales has relevance in establishing the origin and timing of porosity and fracture development the pervasive nature of the organic network adopting the shape of pores in type ii kerogen rich woodford shale suggests it is the residue of primary oil migration we use the term post oil solid bitumen to distinguish this bitumen occurrence from pre oil solid bitumen defined as a precursor of oil three forms of this post oil solid bitumen network are recognized in reflected white light at 500 magnification and confirmed in backscattered scanning electron microscope images at 2500 magnification namely speckled 1 2 m wispy 2 5 m and connected 5 m the post oil solid bitumen network demonstrates the prior occurrence of oil generation and migration within this hydrocarbon source rock provides porosity for hydrocarbon storage sites and forms hydrocarbon migration pathways

the bisagno stream catchment genoa italy and its major floods geomorphic and land use variations in the last three centuries abstract the city of genoa liguria italy and the bisagno valley are affected by frequent floods often with loss of human lives historically characterised by high flood hazards the bisagno valley was recently affected by a flood event on 9 october 2014 less than three years after the tragic flood event of 4 november 2011 when six people died including two children in the last 50 years four destructive floods occurred in the bisagno valley in addition to some other events that caused significant damage and economic losses this paper examines the three largest flood events in terms of intensity and ground effects which affected the bisagno valley in the last three centuries the flood of 25 october 1822 well documented by contemporary sources the flood of 8 october 1970 undoubtedly the most tragic on record and the very recent event of 9 october 2014 for this purpose scientific and historical geographical methodologies were adopted the latter particularly useful for the reconstruction of the flood event of 1822 and the landscape history of the bisagno valley in the nineteenth century this comparison shows that the bisagno valley is characterised by climatic and landform features that have been making the flood events historically common in the area however recent climate change and land use variations including some major modifications of the catchment basin have progressively determined a decrease of the concentration time and an increase of runoff solid transport and flood hazard consequently in recent decades a growth in the number of flood events occurred to the extent that the bisagno today is a famous case study on an international scale

optical characteristics of graptolite bearing sediments and its implication for thermal maturity assessment abstract graptolite reflectance was thought to be one of the most useful thermal maturity indicators for graptolite bearing sediments however the relationship between graptolite reflectance and vitrinite reflectance is not well established graptolites especially in the wufeng longmaxi formations from the ordovician to silurian of south china have been mistaken for vitrinite like particles or solid bitumen which results in inconsistent data on the thermal maturity in this paper we have employed optical microscope techniques to describe the detailed optical characteristics of graptolites and solid bitumen in the wufeng longmaxi formations laboratory simulation of maturation was used to determine the relationship between graptolite reflectance and vitrinite reflectance the organic constituents in the wufeng longmaxi formations are mainly composed of graptolites and solid bitumen granular and non granular graptolites were observed in the wufeng longmaxi formations with non granular as the most common texture solid bitumen can be distinguished from non granular graptolites by its coarse surface weaker anisotropy and lower random reflectance the combination of non polarized and polarized light is very helpful to distinguish solid bitumen from graptolite for comparison organic material from the early ordovician alum shale formation of sweden and estonia was also studied the macerals of the alum shales are mainly composed of lamalginites mineral bituminous groundmasses graptolites and solid bitumen the major textures of the graptolites in the sweden and estonia sediments are non granular and granular respectively both non granular graptolite and vitrinite reflectances display a systematic increase with the increase of heating temperature and time the granular graptolites in the estonian sample were gradually changed to non granular graptolites following laboratory simulated maturation indicating that granular graptolites can transform into non granular graptolites with maturation solid bitumen in the wufeng longmaxi formations was derived from the solid residue of kerogen and or post oil bitumen the graptolite random reflectance is a better thermal maturity indicator than graptolite maximum reflectance and is more precise due to the smaller standard deviation several equations are proposed to determine the thermal maturity of the graptolite bearing sediments based on graptolite random reflectance graptolite maximum reflectance and solid bitumen random reflectance

paleocene lower eocene carbonate platforms of westernmost tethys abstract the paleocene lower eocene succession is well exposed in sierra espuna mula basin betic cordillera s spain and carbonate platforms are well represented as part of this succession the study of the paleoenvironmental evolution of these platforms has allowed to cover an important gap in the knowledge in the westernmost tethys thirteen microfacies mf1 to mf13 were recognized based mainly on the fossil assemblage principally larger benthic foraminifera texture and fabric of the microfacies the fossiliferous assemblage of the entire succession shows a mixture of photozoan and heterotrophic biogenic elements typical of an inner to outer ramp environment of a warm temperate biogeographic province fragments of hermatypic corals have also been detected in the lower part of the succession paleocene allowing thinking in propitious conditions in this period the succession evolves upwards lower eocene to low energy shallow marine protected environments lagoon in inner ramp settings in addition abundant porcelaneous larger benthic foraminifera such as alveolinids and soritids are indicative of euphotic shallow marine conditions in moderately oligotrophic upper subtidal environments in the upper part of the succession hermatypic corals as displaced fragments and in situ isolated coral phaceloid colonies also appear together with other biogenic components indicating warm shallow and euphotic marine conditions coral maerl environment lenticular larger benthic foraminifera characterizing marine mesophotic and oligotrophic habitats can be found in the upper part of the middle ramp and flattened larger benthic foraminifera forms indicating lowermost mesophotic conditions in a distal middle ramp the obtained results have been compared with other similar tethyan sectors obtaining a broader view the biogenic marine association is characterized by the absence of the lockhartia community of the tethyan domain together with the dominance of alveolinids nummulitids and orthophragminids during most of the paleocene northern mediterranean tethys platforms were located in the middle paleolatitudes and characterized by coral reef and coralgal biofacies the studied platforms located at a latitude close to 25 n show in a ramp like context underdeveloped in situ coral constructions probably of patch reef type in the early eocene the expansion and abundance of the larger benthic foraminifera and the practical disappearance of coral took place in the sedimentary platforms through the entire tethys however in the study area small reef coral build ups have also been observed in the lower cuisian beds indicating that in westernmost tethys coral construction continued at these latitudes

middle eocene seagrass facies from apennine carbonate platforms italy abstract two stratigraphic sections located in the latium abruzzi monte porchio central apennines central italy and in the apulian carbonate platform s cesarea torre tiggiano salento southern italy were measured and sampled to document the sedimentological characteristic and the faunistic assemblages of middle eocene seagrass deposits the faunistic assemblages are dominated by porcellaneous foraminifera orbitolites alveolina idalina spiroloculina quinqueloculina triloculina and abundant hooked shaped gypsinids associated with hooked red algae and green algae halimeda fabiania rotaliids and textulariids as well as nummulitids are subordinated the samples were assigned to lutetian sbz13 16 according to the occurrence of nummulites cf lehneri alveolina ex gr elliptica idalina berthelini orbitolites complanatus slovenites decastroi and medocia blayensis at santa cesarea reticulate nummulites occur in association with alveolina spp and halkyardia minima marking the lower bartonian sbz17 three main facies associations have been recognised i larger porcellaneous foraminiferal grainstones with orbitolitids and alveolinids deposited into high energy shallow water settings influenced by wave processes that reworked the sediments associated with a seagrass ii grainstone to packstone with small porcellaneous foraminifera and abundant permanently attached gypsinids deposited in a more protected e g small embayment in situ vegetated environment iii bioclastic packstone with parautochthonous material reworked from the seagrass by rip currents and accumulated into rip channels in a slightly deeper environment the biotic assemblages suggest that the depositional environment is consistent with tropical to subtropical vegetated environments within oligotrophic conditions

epiphyte communities on thalassia testudinum from grand cayman british west indies their composition structure and contribution to lagoonal sediments abstract thalassia testudinum the most common seagrass found in lagoons around grand cayman influences sedimentation by baffling currents binding sediment on the seafloor and providing substrates for a diverse epiphytic biota about 85 of the epiphytic biota is formed of at least 3 species of coralline algae 72 species of foraminifera and 61 species of diatoms the rest of the biota is formed of sponges gastropods ostracods coccoliths dinoflagellates brown algae and worms the epiphytes are organized in three communities that are part of an organized tripartite community succession the basal diatom community is overlain by the coralline algae community which is then overlain by a community composed of a variety of taxa the coralline algae community which is the most extensive typically covers 75 of the leaf s surface potentially the skeletons of these epiphytes can make a significant contribution to the fine grained sediment budget of these lagoons surprisingly only a few of the epiphytes were found in the lagoonal sediment it appears therefore that the epiphytes are lost through skeletal dissolution or transported out of the lagoon following storms irrespective of the cause the epiphytes do not form a significant part of the lagoon sediment in grand cayman

the value of lichenometry and historical archives in assessing the incision of submediterranean rivers from the little ice age in the ardeche and upper loire france the geomorphologic impact of the little ice age lia was determined on two french mediterranean rivers the upper ardeche and the upper loire in order to evaluate the impact of the lia on the hydrology of these rivers two historical flood chronicles were made from historical sources the lia can be divided in three phases of high activity 1530 1700 1750 1810 1840 1910 a geomorphologic study of the two rivers shows that incision is the principle process at work in the 20th century in order to date the low terraces and bedforms present in both valleys lichenometry was used rhizocarpon geographicum allowed the main features on the bottom of the valley to be dated using two growth curves made for the two studied areas in the ardeche lichenometric dating showed a progressive evacuation of the inherited alluvial stock the oldest lichens found on the foodplain and the outcrops indicate that incision began between the second half of the 17th century and the end of the 18th century in the mid little ice age incision stopped on the bedrock in the second half of the 19th century in the loire the narrowness of the gorge did not allow sediment to be stored during the first half of the lia very old lichens 1000 yr of age are present on the bedrock close to the bed however at a number of locations the valley slightly widens allowing sediment that was transiting through the gorge to be stored the geomorphologic features that characterise these basins clearly show a hydrosedimentary behaviour different before and after the beginning of the 20th century

facies analysis and palaeoenvironmental interpretation of the late oligocene attard member lower coralline limestone formation malta the oligocene represents a key interval during which coralline algae became dominant on carbonate ramps and luxuriant coral reefs emerged on a global scale so far few studies have considered the impact that these early reefs had on ramp development consequently this study aimed at presenting a high resolution analysis of the attard member of the lower coralline limestone formation late oligocene malta in order to decipher the internal and external factors controlling the architecture of a typical late oligocene platform excellent exposures of the lower coralline limestone formation occurring along continuous outcrops adjacent to the victoria lines fault reveal in detail the three dimensional distribution of the reef associated facies a total of four sedimentary facies have been recognized and are grouped into two depositional environments that correspond to the inner and middle carbonate ramp the inner ramp was characterized by a very high energy shallow water setting influenced by tide and wave processes this setting passed downslope into an inner ramp depositional environment which was colonized by seagrass and interfingered with adjacent areas containing scattered corals the middle ramp lithofacies were deposited in the oligophotic zone the sediments being generated from combined in situ production and sediments swept from the shallower inner ramp by currents compositional characteristics and facies distributions of the attard ramp are more similar to the miocene ramps than to those of the eocene an important factor controlling this similarity may be the expansion of the seagrass colonization within the euphotic zone this expansion may have commenced in the late oligocene and was associated with a concomitant reduction in the aerial extent of the larger benthonic foraminifera facies stacking pattern analysis shows that the depositional units parasequences at the study section are arranged into transgressive regressive facies cycles this cyclicity is superimposed on the overall regressive phase recorded by the attard succession furthermore a minor highstand correlated with the ru4 ch1 sequence and subsequent minor lowstand ch2 sequence have been recognized the biota assemblages of the attard member suggest that carbonate sedimentation took place in subtropical waters and oligotrophic to slightly mesotrophic conditions the apparent low capacity of corals to form wave resistant reef structures is considered to have been a significant factor affecting substrate stability at this time the resulting lack of resistant mid ramp reef frameworks left this zone exposed to wave and storm activity thereby encouraging the widespread development of coralline algal associations dominated by rhodoliths

geochemical investigation of a sediment core from the trajan basin at portus the harbor of ancient rome a journal published by elsevier the attached copy is furnished to the author for internal non commercial research and education use including for instruction at the authors institution and sharing with colleagues other uses including reproduction and distribution or selling or licensing copies or posting to personal institutional or third party websites are prohibited in most cases authors are permitted to post their version of the article e g in word or tex form to their personal website or institutional repository authors requiring further information regarding elsevier s archiving and manuscript policies are encouraged to visit a b s t r a c t from the 1st century ad and for the duration of the roman empire the portus complex was the main harbor of rome its location on the tiber delta next to the tyrrhenian sea produced rapid environmental changes that together with historical vicissitudes largely determined the fate of the harbor we have assembled data on the mineralogy sedimentology geochemistry and ostracod populations of a sediment core drilled in the access channel of the hexagonal basin of trajan with the expectation that such a combined data set will shed new light on how the connections of the inland trajan basin with the tiber river the earlier claudius harbor on the nearby shoreline and the sea evolved through the centuries the data define four distinct periods which geochemistry characterizes by different conditions of salinity and oxygenation these in turn can be related to historical periods and events by means of 14

similarities between planktonic and larger foraminiferal evolutionary trends through paleogene paleoceanographic changes abstract the paleogene evolutionary records of planktonic foraminifera and larger benthic foraminifera show parallel patterns in development that may in part reflect changes in nutrient flux to surface waters following the terminal cretaceous extinctions faunas were dominated by a few cosmopolitan opportunistic species more specialized k strategists in both groups diversified during the paleocene dominating into the early eocene consistent with he globally mild climatic regime and probable limited rates of nutrient flux to surface waters high latitude cooling intensified in the middle eocene promoting diversification of less specialized taxa characteristic of cooler and deeper waters higher latitudes meridional upwelling zones and boundary currents geographic ranges of warm water taxa diminished and fragmented yet many species survived thus global diversities during the middle eocene were the highest in the cenozoic as cooling and increased rates of nutrient flux further intensified in the late eocene extinction rates of warm water planktonic and larger benthic species exceeded origination rates of cooler water and less specialized forms so diversity dropped to intermediate levels where it remained through the late eocene and oligocene previous observations that planktonic foraminiferal faunas dominated by warm water taxa are often replaced by cool water faunas even though oxygen isotopes only recorded relatively minor cooling can be reconciled by the explanation that the biotic communities responded to changes in trophic resources and euphotic habitats that accompany the temperature reduction as well as to temperature change itself

characterization and quantification of holocene colluvial and alluvial sediments in the valdaine region southern france this study presents a holocene sediment budget for the valdaine region located at the edge of the southern french pre alps holocene colluvial and alluvial deposition are quantified based on existing and new field data average sediment thickness values were calculated for different landscape units and available chronological data were used to make a time differentiated sediment budget total holocene colluvial deposition in the valdaine 334 km2 amounts 167 106 m3 while alluvial deposition in the roubion and jabron catchments in total 610 km2 including their catchment upstream the valdaine amounts 177 106 m3 especially colluvial deposition is high 0 75 106 g m2 compared with other catchments three major deposition periods 8500 2000 bc 700 bc ad 800 and ad 1200 2000 and two periods of relative hillslope stability with local fluvial incision 2000 700 bc and ad 800 1200 set the framework for a time differentiated sediment budget results show that depositional phases relate to intense

soil erosion in small catchments of the quercy region southwester france during the holocene erosion rates in two small catchments of the quercy region southwestern france calculated from colluvial deposits trapped in karstic depressions show a progressive increase during the holocene rates lower than 0 2 t ha 1 yr 1 have been found for the period that covers the beginning of the holocene to the early iron age the soils buried in the depressions testify to the permanence of a forest cover until the late neolithic and to its replacement by a herbaceous vegetation during protohistorical times probably as a consequence of forest clearance and increased grazing by cattle after the early iron age erosion increased significantly and the mean rate reached 0 8 t ha 1 yr 1 before mediaeval times the associated coarse grained crudely stratified colluvium is thought to reflect ploughing of the surrounding fields erosion rate increased up to c 1 3t ha 1 yr 1 during mediaeval and modem times

carbonate lithofacies as paleolatitude indicators problems and limitations abstract detailed study of miocene carbonates in the mediterranean region and their analogues on modern carbonate shelves in the mediterranean sea brazil and other areas reveals at least three major types of carbonate platform lithofacies in addition to the classic tropical coral reef chlorozoan lithofacies a chloralgal lithofacies similar to the chlorozoan but without hermatypic corals b rhodalgal lithofacies characterized by abundant encrusting coralline algae and c molechfor lithofacies consisting of benthic foraminifers molluscs echinoids bryozoans and barnacles these carbonate lithofacies present complex distribution patterns seemingly related primarily to latitude and depth that control water temperature although other factors e g water circulation river discharge suspended sediment controlling water salinity and temperature nutrient content light penetration etc also play important roles chloralgal and rhodalgal lithofacies can be considered two transitional terms between the two end members the chlorozoan lithofacies which characterizes shallow tropical shelves and the molechfor lithofacies which characterizes colder and or deeper areas detailed textural and sequential analysis are required for satisfactory interpretation of these lithofacies in ancient rocks

carbonate systems along nutrient and temperature gradients some sedimentological and geochemical constraints research over the past several decades has clearly demonstrated that changes in the ocean environment have had major impacts on carbonate systems changes in climate ocean circulation and seafloor spreading rates have influenced temperature and seawater chemistry including carbonate saturation state and nutrient availability and thereby have determined boundary conditions for the biota that form carbonate platforms in turn the biota determine accumulation rates and facies zonations thus controlling platform geometry and facies dynamics in the first section of this paper we examine how nutrient availability influences carbonate facies associations we first discuss the role of temperature and nutrient gradients in the modern ocean and their influence on biotic associations then we discuss how carbonate sedimentation can be characterized along nutrient gradients in the second section we review proxies currently used to reconstruct paleoproductivity in open ocean environments and discuss their applicability to neritic carbonate systems we highlight the variety of existing proxies and their limitations and suggest that multiple lines of evidence are needed for valid interpretations our short review discusses sedimentological biogenic and geochemical proxies that can be used to reconstruct past nutrient fluxes and to constrain paleoceanographic controls over the distribution of carbonate associations however it also reveals that more data and case studies are needed that integrate shallow and deep water carbonate sequences and elucidate the links between temperature vs nutrient supplies changes and facies in ancient carbonate sequences

reflectance cross plot analysis of graptolites from the anchi metamorphic region of northern maine u s a abstract reflectance crossplot analysis a graphical technique plotting apparent reflectance maxima and minima against the apparent bireflectance and previously used primarily for interpretation of biaxial vitrinite data is applied to graptolite reflectance data from the subgreenschist and chlorite zones of northern maine u s a to determine the value of the intermediate reflectance axis rint the shape and change in the graptolite reflecting indicating surface gris with rank and calculate random reflectance from the crossplots gris shapes for this region were found to become rapidly oblate with increasing maturation in addition the random reflectance calculated as the arithmetic mean of the three reflectance axes compares favorably with the measured mean random reflectance

seagrass related carbonate ramp development at the front of a fan delta burdigalian new caledonia insights into mixed carbonate siliciclastic environments abstract past shallow water carbonate environments of the main island of new caledonia nc have been subject to high terrigenous influx derived from the erosion of ultramafic obducted nappes and are therefore a relevant case study for characterizing neritic carbonate production in mixed carbonate siliciclastic systems under a tropical climate more particularly we focused on burdigalian carbonate sedimentary records cropping out on the western coast of nc in the nepoui area based on a comprehensive sedimentological study of cores and outcrops we established a new depositional model of an alluvial fan to carbonate ramp transition shallow water euphotic carbonate production was dominated by seagrass related biota and corals derived from small sized bioconstructions extensional tectonics and associated normal faulting driven by post obduction isostatic rebound favored carbonate ramp aggradation and preservation the carbonate ramp was incised by conglomerate filled terminal distributary channels which indicate that terrigenous inputs remained significant during marine transgression and did not inhibit the development of seagrass and scleractinian carbonate factories phytal substrates induced by seagrass and or macro algae seafloor colonization strongly controlled the nature of carbonate production and promoted the accumulation of foraminiferal coralline algal sediments seagrass development at the front of the fan delta is interpreted to have controlled the preservation of a diverse and significant carbonate production by reducing water turbidity and by limiting the risk of suffocation for filter feeding biota in such a high terrigenous influx setting

the anthropogenic nature of present day low energy rivers in western france and implications for current restoration projects abstract as in other european countries western france has seen an increase in river restoration projects in this paper we examine the restoration goals methods and objectives with respect to the long term trajectory and understanding of the contemporary dynamics of the small low energy rivers typical of the lowlands of western europe the exhaustive geomorphological paleoenvironmental and historical research conducted in the seulles river basin normandy provides very accurate documentation of the nature and place of the different legacies in the fluvial systems we have inherited the sedimentation rate in the seulles valley bottom has multiplied by a factor of 20 since the end of the bronze age and has generated dramatic changes in fluvial forms hydraulic control of the rivers and valley bottoms drainage throughout the last millennium has channelized rivers within these deposits the single meandering channel which characterizes this river today is the legacy of the delayed and complex effects of long term exploitation of the river basin and the fluvial system bring to light that the naturalness of the restored rivers might be questioned our research emphasizes the gap between the poor knowledge of the functioning of these rivers and the concrete objectives of the restoration works undertaken including dam and weir removal account of the long term history of fluvial systems is required not only to produce a pedagogic history of the river degradation but more fundamentally i to situate the current functioning of the fluvial system in a trajectory to try to identify thresholds and anticipate the potential turning points in a context of climate and land use change ii to understand the role of morphosedimentary legacies on the current dynamics iii to open the discussion on reference functioning or expected states and iv to open discussion on the sustainability of ecological restoration to conclude we point out the necessity to take into account the hybrid nature of low energy rivers in rural environments and to develop specific evaluation protocols which would include both biophysical processes and usual human activities which could be a way to share the evaluation and overcome conflicts between socioeconomic needs and environmental issues

combining radiocarbon and single grain optically stimulated luminescence methods to accurately date pre ceramic irrigation canals tucson arizona abstract we present 12 accelerator mass spectrometry ams 14 c and five quartz single grain optically stimulated luminescence osl ages from three early agricultural period irrigation canals recently discovered in the floodplains of the santa cruz river and rillito creek in tucson arizona significant discrepancies in the ams 14 c ages are associated with fluvial redeposition of charcoal producing at times age overestimates of 1000 years single grain osl ages on canal sediments and application of a minimum age model accurately date the final operation of the canals but have relatively large standard errors of several hundred years based on single grain osl one canal dates 730 310 b c and the other two date 560 100 b c this corresponds with a period of predominant floodplain aggradation 500 b c a d 1 conducive to water control and irrigation agriculture stratigraphic evidence of uncontrolled flooding and rapid sedimentation is present in all three canals and marks the abandonment of two canals determining the age of the earliest canals is important for understanding the origins of water management and the transition from foraging to intensive agriculture in the north american southwest due to potential problems with reworked organic material for 14 c dating and partial bleaching resetting of luminescence signals in fluvial settings we recommend a combined ams 14 c and single grain osl approach for dating early canals

the oligocene miocene stratigraphic evolution of the majella carbonate platform central apennines italy abstract the stratigraphic architecture of the bolognano formation documents the evolution of the majella carbonate platform in response to global and local changes that affected the mediterranean area during the oligocene miocene interval the bolognano formation consists of a homoclinal ramp that developed in a warm subtropical environment five different lithofacies associations have been identified lepidocyclina calcarenites cherty marly limestones bryozon calcarenites hemipelagic marls and marly limestones and lithothamnion limestones each association corresponds to a single lithostratigraphic unit except for the lepidocyclina calcarenites that form two distinct lithostratigraphic units lepidocyclina calcarenites 1 and 2 these six units reflect alternation of shallow water carbonate production and drowning specifically two of the three stages of shallow water carbonate production regard the development of wide dune fields within the middle ramp one stage dominated by red algae and a sea grass carbonate factory whereas the two drowning phases are represented by marly cherty limestones and calcareous marls a new biostratigraphic framework for bolognano formation is presented based on high resolution analysis of calcareous nannofossil assemblages which proved to be very useful for biostratigraphic constraints also in shallow water settings using this approach we have linked the first drowning phase late chattian aquitanian p p in age to western mediterranean volcanism and the mi 1 event and the second drowning phase late burdigalian serravallian in age to the closure of the indo pacific passage and the occurrence of the global monterey event these results permit a new deciphering in terms of sequence stratigraphy of the bolognano formation that is interpreted as a 2nd order super sequence that can be subdivided into 3 transgressive regressive sequences

stepwise extinction of larger foraminifers at the cenomanian turonian boundary a shallow water perspective on nutrient fluctuations during oceanic anoxic event 2 bonarelli event a two step pattern in the extinction of larger foraminifers is recorded in the upper cenomanian shallow water carbonates of the southern apennines italy the first step eliminated the alveolinids the most extreme oligotrophs and reduced dramatically the diversity of larger foraminifers the second step wiped out the few survivors seemingly able to tolerate mesotrophic conditions leaving a disaster fauna dominated by small heterotrophs this pattern of extinction parallels the ecological succession of shallow water benthic foraminiferal assemblages along a gradient of increasing nutrient availability high resolution carbon isotope stratigraphy shows that the extinction of alveolinids was contemporaneous with the extinction of rotaliporid planktic foraminifers the drowning of certain tethyan carbonate platforms and an episode of thermal instability recorded in sea surface temperature in the open ocean ocean stratification during the first phase of oceanic anoxic event 2 would have promoted oligotrophic conditions in surface tropical waters and maximum diversity of larger foraminifers following this ocean overturning caused by surface water cooling is credited with delivering to shallow water environments the excess nutrient loads previously stored at depth triggering the environmental changes leading to stepwise extinction of larger foraminifers

demise of a harbor a geochemical chronicle from ephesus a b s t r a c t at the end of the first century bc ephesus became the roman capital of asia minor and the most important commercial religious and cultural center of the region in order to evaluate the status of anthropogenic fluxes in the port of ephesus a 12 m long sediment core drilled in the roman basin was investigated to shed light on the paleo environmental evolution of the harbor using grain size distri bution analysis 14 c ages major and trace element geochemistry and pb isotope compositions with the help of complementary sedimentological data and principal component analysis five distinct units were identified which together reflect the different stages of water history in the harbor among the major disruptive events affecting the port were earthquakes and military events both of which were partic ularly effective at destroying the water distribution system seasonal floods of the cayster river kucuk menderes were the major source of the silt that progres sively infilled the harbor silting in was further enhanced by the westward migration of the river mouth a single major disruptive event located at 550 cm core depth and heralding the development of anoxia in the harbor marks the end of the dynamic regime that otherwise controlled the harbor water throughout the roman empire period this remarkable event may correspond to a major disruption of the aqueduct system or to a brutal avulsion of the cayster river bed it clearly represents a major disturbance in the history of life at ephesus it is poorly dated but probably occurred during the reign of augustus or shortly after lead isotope and trace metal evidence suggest that in the four bottom units pollution was subdued with respect to other pb metal inputs presumably those from aqueducts and natural karstic springs near the top of the core which coincides with harbor abandonment and the more recent period anthropogenic pb contam ination is clearly visible in both pb abundances and isotopic compositions

classic and new dating methods for assessing the temporal occurrence of mass movements abstract establishing landslide chronologies is essential both for understanding causes of mass movements as part of fundamental geomorphological research and for the assessment of landslide hazards as part of applied geomorphology we discuss the applicability of different methods for determining landslide chronologies frequencies and dynamics in relation to the type of material being dated sampling location and type of mass movement the emphasis is on the possibilities and limitations of the different dating methods established methods such as radiocarbon dating lichenometry and dendrochronology are briefly discussed the paper focuses however on 1 new analytical techniques like accelerator mass spectrometry ams thermally ionising mass spectrometry tims and laser fusion which have led to significant improvements of established dating methods and on 2 new dating methods like optically stimulated luminescence osl dating and alpha recoil track art dating

an assessment of sediment transport processes in the lower mekong river based on deposit grain sizes the cm technique and flow energy data abstract the lower mekong river has been an important research topic for at least 15 years notably in the fields of hydrology fluvial geomorphology and the impact of dams recent papers refer mostly to the impact of the lancang chain of hydroelectric dams constructed on the chinese section of the river among the pending scientific questions are 1 the upstream downstream variations in the concentration and yield of suspended sediment and 2 the relative importance of sand in the total yield the general consensus among the scientific community is that the relative importance of sand in suspended load is not the main scientific concern despite its extensive presence in the mekong river channel as noted by geomorphologists and despite its extreme importance for the stability of the delta shoreline in viet nam this paper contradicts the general consensus its objective is to present new information on the processes of sand transport in the lower mekong channel imagery field observations sampling on the river banks and grain size analysis of sand deposits have been carried out between chiang sean downstream of the chinese border and the delta the c m image technique served to discriminate between the various transport processes bedload and different types of suspension this technique helps in understanding the changing processes responsible for downstream sediment transfer in river channels the results of this study are the following 1 discrepancies in the values of annual suspended sediment load detected by different gauging stations have not yet been satisfactorily explained the cm image technique indicates that grain size and the quantity of sand transiting in suspension vs bedload vary from upstream to downstream 2 these upstream downstream differences may be related to the energy of floods energy helps to explain longitudinal variations in the relative importance of the different modes of transport and serves to distinguish between bedload graded and uniform suspension and wash load 3 the mekong is seen as a river carrying mostly silt and clay however the results suggest that sand plays a major role in downstream sediment transfer during floods this result is in line with the large amounts of sand present in the channel its relative importance in the total yield must be reassessed as suggested by walling 2005 2008 as may be expected the role of sand in the stability of the delta shoreline is of prime importance

turnover of larger foraminifera during the paleocene eocene thermal maximum and paleoclimatic control on the evolution of platform ecosystems the larger foraminifera turnover lft during the paleocene eocene transition constitutes an important step in paleogene larger foraminifera evolution involving a rapid increase in species diversity shell size and adult dimorphism a platform to basin transect in egypt provides new data on timing and causal mechanisms through correlation with planktic biozonations and through integration with regional paleoenvironmental data the lft coincides with the boundary between shallow benthic biozones sbz4 and sbz5 and closely correlates with the paleocene eocene thermal maximum petm enhanced oligotrophy from the late paleocene onward favored the diversification of k strategist larger foraminifera we suggest that a short term eutrophication during the petm led to a temporary decline of extreme k strategist larger foraminifera species providing opportunities for new taxa with different ecological strategies to develop during post petm oligotrophic conditions these new taxa were able to evolve rapidly and soon dominated early eocene larger foraminifera assemblages whereas many paleocene taxa gradually disappeared the success of larger foraminifera during the early paleogene appears climatically controlled because of the vulnerability of corals to high surface water temperatures the late paleocene to early eocene global warming may have favored larger foraminifera at the expense of corals as the main carbonate producing component on carbonate platforms at lower latitudes

graptolites as indicators of regional maturity in lower paleozoic sediments selwyn basin yukon and northwest territories canada variations in reflectance and bireflectance of graptolites and bitumen are documented from lower paleozoic rocks of howard s pass xy zn pb deposit and adjacent portions of the selwyn basin two types of graptolite morphologies are recognized in these rocks a nongranular type comprising blocky and lath shaped varieties and a granular type the nongranular graptolites generally display higher reflectance and bireflectance than granular graptolites bitumen epi impsonite to meso impsonite is common in these rocks and displays a wide range of reflectance and bireflectance values at the howard s pass xy property graptolite reflectance values display a slight increase with depth and anomalously high values 7 46 10 25 are documented in the sulphide rich upper active member in surrounding regions of the selwyn basin remote from howard s pass graptolite reflectance values are lower 3 02 6 26 conodont colour alteration index values reported by others show no detectable variation in the same

five hundred years of gridded high resolution precipitation reconstructions over europe and the connection to large scale circulation we present seasonal precipitation reconstructions for european land areas 30 w to 40 e 30 71 n given on a 0 5 0 5 resolved grid covering the period 1500 1900 together with gridded reanalysis from 1901 to 2000 mitchell and jones 2005 principal component regression techniques were applied to develop this dataset a large variety of long instrumental precipitation series precipitation indices based on documentary evidence and natural proxies tree ring chronologies ice cores corals and a speleothem that are sensitive to precipitation signals were used as predictors transfer functions were derived over the 1901 1983 calibration period and applied to 1500 1900 in order to reconstruct the large scale precipitation fields over europe the performance quality estimation based on unresolved variance within the calibration period of the reconstructions varies over centuries seasons and space highest reconstructive skill was found for winter over central europe and the iberian peninsula precipitation variability over the last half millennium reveals both large interannual and decadal fluctuations applying running correlations we found major non stationarities in the relation between large scale circulation and regional precipitation for several periods during the last 500 years we identified key atmospheric modes for southern spain northern morocco and central europe as representations of two precipitation regimes using scaled composite analysis we show that precipitation extremes over central europe and southern spain are linked to distinct pressure patterns due to its high spatial and temporal resolution this dataset allows detailed studies of regional precipitation variability for all seasons impact studies on different time and space scales comparisons with high resolution climate models as well as analysis of connections with regional temperature reconstructions

age and source of colluvial sediments at vaihingen enz germany abstract colluvial sediments accumulated on the lower slopes of a ridge as a result of past and present soil erosion were dated by optical 14 c and archaeological methods this allowed us to reconstruct the depositional history of the colluvium and also to identify temporary sedimentary sinks in its transportational pathway a cascade model of colluvium formation is developed colluvial sediments resulting from early soil erosion in the neolithic to iron age periods were mainly deposited on the upper slopes significant deposition on the lower slope occurred for the first time during the iron age and roman period since then deposition rates have increased because of more intensive land use

fully nonlinear inversion of fundamental mode surface waves for a global crustal model 1 we use neural networks to find 1 dimensional marginal probability density functions pdfs of global crustal parameters the information content of the full posterior and prior pdfs can quantify the extent to which a parameter is constrained by the data we inverted fundamental mode love and rayleigh wave phase and group velocity maps for pdfs of crustal thickness and independently of vertically averaged crustal shear wave velocity using surface wave data with periods t 35 s for phase velocities and t 18 s for group velocities moho depth and vertically averaged shear wave velocity of continental crust are well constrained but vertically averaged shear wave velocity of oceanic crust is not resolvable the latter is a priori constrained by crust2 0 we show that the resulting model allows to compute global crustal corrections for surface wave tomography for periods t 50 s for phase velocities and t 60 s for group velocities

the fluvial record of climate change fluvial landforms and sediments can be used to reconstruct past hydrological conditions over different time scales once allowance has been made for tectonic base level and human complications field stratigraphic evidence is explored here at three time scales the later pleistocene the holocene and the historical and instrumental period new data from a range of field studies demonstrate that croll milankovitch forcing dansgaard oeschger and heinrich events enhanced monsoon circulation millennial to centennial scale climate variability within the holocene probably associated with solar forcing and deep ocean circulation and flood event variability in recent centuries can all be discerned in the fluvial record although very significant advances have been made in river system and climate change research in recent years the potential of fluvial palaeohydrology has yet to be fully realized to the detriment of climatology public health resource management and river engineering

recognition of vitrinite with non uniaxial negative reflectance characteristics non uniaxial negative reflectance characteristics are being reported for coals from around the world with increasing frequency these data have traditionally been collected from oriented sections cut from a block of coal to determine the magnitudes of the principal reflectance axes to make data collection less time consuming a method of determining the principal reflectance axes from a standard crushed coal sample has been developed the method requires measurement of the maximum and minimum apparent reflectances from a series of randomly oriented vitrinite particles the reflectance crossplot displays these two reflectance values against their difference or bireflectance the paper describes the method of interpreting the resultant pattern to determine the values of the three principal reflectance axes analysis of coals from the british columbia rocky mountains and foothills revealed biaxial and uniaxial positive as well as uniaxial negative reflectance characteristics a new measure of maturation rev is proposed which is based purely on the lengths of the three principal reflectance axes rm approximates this value but is influence by any eccentricity of the reflectance indicating surface ris vitrinite with a non uniaxial reflectance characteristics cannot be adequately described by a single measure such as rmaxorrm but requires reference to both the size and shape of the ris a reflectance determination such as rev or rm provides rank astm information whereas the new measures rst and ram describe a reflectance indicating surface shape which is the result of maturation and tectonic histories vitrinites with non uniaxial negative reflectance characteristics are abundant in the coalfields of the rocky mountains and foothills of british columbia rmax does not fully describe the reflectance character of these coals and does not describe the potentially useful ris shape

luminescence dating of the niederweningen mammoth site switzerland abstract luminescence dating is used to further constrain the so far controversial age of the mammoth site at niederweningen switzerland gamma spectrometric analyses reveal the presence of radioactive disequilibria in the uranium decay chain in most of the samples but these cause only minor uncertainties in the age estimates the major uncertainty is actually related to the problem of estimating the average water content for the whole burial time nevertheless even considering these problems involved with dose rate determination the dating results clearly indicate that the peat is significantly younger than early wurmian in contrast to some previous assumptions together with the results of radiocarbon dating and pollen analyses the luminescence ages point to a correlation of the mammoth peat with interstadial conditions during the early part of the middle wurmian at around 45 ka ago

palaeoflood activity and climate change over the last 1400 years recorded by lake sediments in the north west european alps a high resolution sedimentological and geochemical study of a high altitude proglacial lake lake blanc aiguilles rouges 2352m a s l revealed 195 turbidites 190 of which are related to flood events over the last 1400 years we used the coarsest sediment fraction of each turbidite as a proxy for the intensity of each flood event because most flood events at this locality are triggered by localized summer convective precipitation events the reconstructed sedimentary record reveals changes in the frequency and intensity of such events over the last millennium comparisons with other temperature palaeohydrological and glacier reconstructions in the region suggest that the most intense events occurred during the warmest periods i e during the medieval climate anomaly ad 800 1300 and the current period of global warming on a multi decadal time scale almost all the flood frequency peaks seem to correspond to warmer periods whereas multi centennial variations in flood frequency appear to follow the regional precipitation pattern consequently this new alpine flood record provides further evidence of a link between climate warming and an increase in the frequency and intensity of flooding on a multidecadal time scale whereas the centennial variability in flood frequencies is related to regional precipitation patterns

hooked and tubular coralline algae indicate seagrass beds associated to mediterranean messinian reefs poniente basin almeria se spain abstract abundant hooked and tubular crustose coralline algae cca record early messinian late miocene seagrass beds on the northern margin of the poniente basin in southeastern spain hooked and tubular shapes in cca result from their epiphytic growth over seagrass leaves and stems the lower messinian deposits consist of a thin retrograding subunit overlain by sigmoidal bed packages that prograded to the southwest at least 650 m from the basin margin seagrass deposits mainly occur as bivalve cca packstone to rudstone and cca floatstone seawards of a conglomerate facies belt in the retrograding subunit and downslope of coral reefs and serpulid packstone to rudstone in the prograding sigmoidal beds fragments of contorted foliose cca algal flakes some hooked or tubular are common components in the seagrass deposits they mainly belong to an unidentified species of mesophyllum like their present day counterparts the epiphytic cca grew attached to seagrass by the initial parts of their thalli and displayed unattached projections or open frameworks of contorted foliose plants in a few cases hooked cca occur attached to halimeda plates small benthic foraminiferal assemblages are further evidence of macrophyte vegetation hooked contorted foliose cca can be a helpful tool for the identification of ancient seagrass beds especially in mediterranean neogene and quaternary deposits in which foraminiferal taxa fully indicative of seagrass ecosystems are scarce

sediment retention by a mediterranean posidonia oceanica meadow the balance between deposition and resuspension the role of posidonia oceanica in promoting sediment stability and accretion was studied in a 15 m deep meadow at fanals point nw mediterranean spain by comparing particle deposition within the meadow and adjacent bare sediment small sediment traps were used to measure deposition within and above the meadow and over bare sand a model based on measurements of particle deposition at increasing distances from the bottom was used to partition the total depositional flux between primary sediment particles deposited for the first time at the measuring site and resuspended deposition sediment particles that have been previously deposited at the measuring site measurements were conducted monthly over a year to establish the magnitude and seasonality of deposition and to form a balance of particle transport at the annual time scale significant differences in total deposition were found over time ranging from 1 5 to 500 g dw m 2 d 1 including those between bare and vegetated sediments the effect of p oceanica in increasing primary deposition at an annual scale was modest however p oceanica significantly buffered sediment resuspension which was reduced more than three fold compared to the unvegetated bottom the annual flux of deposition was dominated by settling of resuspended materials which represented 85 of the total flux within the meadow but 95 of the total deposition on bare sand thus seagrass meadows reduce resuspension in the nw mediterranean littoral thereby contributing to increased sediment retention and therefore reducing erosion in the coastal zone

reflectance measurements of zooclasts and solid bitumen in lower paleozoic shales southern scandinavia correlation to vitrinite reflectance abstract reflectance measurements have been carried out on zooclasts graptolites chitinozoans and vase shaped microfossils and other organic particles vitrinite like particles porous granular vitrinite like particles and solid bitumen in middle cambrian to upper silurian shales from central and southern sweden and the danish island of bornholm baltic sea the most abundant organic components in all the shales are fragments of graptolites and vitrinite like particles the reflectance distribution of these two types of components is largely identical and it is suggested that the vitrinite like particles are fragments of graptolites without any recognizable morphology reflectance measurements of graptolites and vitrinite like particles yield well defined reflectance populations in samples with average r graptolite and average r vitrinite like of 0 75 r o the reflectance distributions are bimodal because of increasing bireflectance and the average reflectance value of the well defined lower reflecting population is arbitrarily used as maturity indicator our results suggest that with increasing thermal maturity the reflectance of graptolites increases faster than the predicted vitrinite reflectance the relationship between graptolite reflectance and equivalent vitrinite reflectance can be expressed by the equation vr eqv 0 73 r graptolite vitrinite like low 0 16 the gas generation window which normally is considered to begin at a vitrinite reflectance of 1 3 r o in post lower paleozoic rocks containing vitrinite starts accordingly at 1 56 r o graptolite reflectance porous granular vitrinite like particles occur in minor amounts and they may represent graptolite fragments with a non smooth surface they generally yield slightly higher reflectance than non granular vitrinite like particles and graptolite fragments the middle cambrian to furongian upper cambrian shales may contain sparse fragments of vase shaped microfossils vsm that seem to follow the maturation trend of chitinozoans in the present sample set the reflectance of chitinozoans and vsm is comparable to that of graptolites at the same level of maturity reflectance measurements of solid bitumen are a poor maturity indicator probably because bitumen can have various origins and morphologies and it may not be indigenous to the host rock

detailed chronology of mid altitude fluvial system response to changing climate and societies at the end of the little ice age southwestern alps and cevennes france abstract over a historical timescale landscapes have been strongly affected by fluctuations in climate and by the impact of human societies this study examines the historical evolution of mid altitude fluvial systems in the western alps and cevennes se massif central in the context of marked climate and anthropogenic change at the end of the little ice age late 19th century this work contributes to the reconstruction of river paleodynamics by investigating the nature and chronology of geomorphological changes in upper river basins in order to produce a detailed reconstruction of hydromorphological changes we combined two approaches the study of historical archives and the use of bioindicators the dating of terraces using dendrochronology and of silt benches using lichenometry in order to reconstruct the evolution of the river channels the 19th century is a particularly propitious period for the study of surface dynamics because archives have preserved a wealth of qualitative and quantitative data concerning rivers economic statistics meteorological and hydrological observations illustrative documents descriptions by contemporary observers it is also a period for which reliable dating methods are available for detrital deposits in rivers the period provides new information on how the transition between the little ice age and current climate conditions affected the evolution of drainage basins and stream channels by highlighting a succession of phases in the erosive process e g the preparatory role of the drought of 1830 1838 in the erosion crisis of 1855 1870 and refining the chronology of events very early onset of riverbed incision the results highlight the effect of climate small hydroclimatic fluctuations amplified by strong anthropization on the rhythm of landscape change and on the relative stabilization of the landscape at the end of the 19th century in addition the synchronization of phenomena on the two sides of the rhone valley shows that these changes took place on a regional scale

the lower rupelian cluster reefs of majella platform the shallow water record of eocene to oligocene transition abstract the eocene oligocene transition is a key interval in the evolution of the modern climate representing the last greenhouse icehouse transition faced by the earth shallow water carbonate systems hold essential information of the global changes related to the e o transition in this work we focus on the majella mountain carbonate ramp to identify the shallow water sedimentary expression of the oceanographic and sea level changes related to the e o transition and to compare it with the deep marine records and the coeval shallow water successions field observations coupled with the study of thin sections to identify textural characters and of the larger benthic foraminiferal associations for biostratigraphic purposes allowed reconstructing the depositional model and the stratigraphic distribution of the examined ramp the lower rupelian ramp outcropping in the majella mountain is characterized by seagrass meadows in the euphotic inner ramp corals developed in the middle ramp building mounded cluster reefs in the mesophotic zone below wave base in high hydrodynamic conditions produced by rip currents induced by storm events or by the breaker zone of internal waves the outer ramp consists of alternating bioturbated wackestone rich in planktonic foraminifera bioclastic packstone and skeletal rudstone to floatstone the depositional model of the oligocene ramps is the result of the major changes that occurred during the greenhouse icehouse transition in the majella platform the e o transition corresponds to an unconformity developed on the priabonian substrate where the cluster reefs grew and expanded the unconformity results from the sea level drop of tens of meters recorded also in the outer ramp related to the oi 1 event the cluster reefs started to develop when the priabonian ramp was flooded and continued to grow during the following highstands forming an extensive coral unit that prograded basinwards interfingering with the outer ramp deposits

ecological control of sedimentary accommodation evolution from a carbonate ramp to rimmed shelf upper miocene balearic islands abstract stratal patterns and facies architecture develop in response to sediment flux and the available space for sediment accumulation accommodation in siliciclastic systems these two parameters are independent in carbonates however they are highly interdependent 1 sediment input production highly depends on biological systems and consequently on intrabasinal conditions nutrients temperature salinity etc 2 sediment dispersal depends on the production loci and on the interaction between the amount and type of sediment being produced and the hydraulic energy additionally biological processes binding baffling framework construction and even cementation frequently modify it 3 accommodation is not an independent factor with respect to sediment input type efficiency and area of the carbonate factory depend on sea level changes and sea floor morphology the base level for sediment to accumulate accommodation depends on the type and locus of sediment being produced the upper miocene carbonate platforms of the balearic islands illustrate how changes in intrabasinal environmental conditions nutrients and or temperature produce changes in stratal patterns and facies architecture if they affect the biological system during early tortonian carbonate production occurred both in the shallow euphotic zone foramol and in the deeper oligophotic zone rhodalgal originating a distally steepened ramp during late tortonian and early messinian carbonate production mainly occurred in the euphotic zone where framework producing biota coral reefs formed a rimmed platform although deposited under similar conditions of high frequency sea level fluctuations these two types of platforms exhibit different internal facies architecture and distribution of heterogeneities because of differences in base level in carbonates base level for sediment accumulation depends on the type and amount of sediment being produced on the production loci and on the processes controlling sediment dispersal base level for the loose foramol rhodalgal sediment associations of the ramp was controlled by wave and storm base and the associated currents whereas base level for the framework dominated reef complex was sea level furthermore the increase on effective accommodation space to allow the reef rimmed shelf to prograde onto the distally steepened ramp both platforms being depositional sequences resulted from an ecological change rather than significant relative sea level change namely by the shift from grain to framework producing biota the euphotic framework producing biota was able to fill the accommodation space existing between wave and storm base level and sea level that was not previously filled by the loose bioclasts

anthracology and taphonomy from wood gathering to charcoal analysis a review of the taphonomic processes modifying charcoal assemblages in archaeological contexts abstract a discussion on the representativeness of charcoal from archaeological contexts and their potential for palaeoecological reconstruction is presented the charcoal deposits studied are the result of human activities and natural processes difficult to separate on the basis of their effects only this is why taphonomy should not be limited to the study of charcoal after the extinction of fire as a result our questioning has been widened to include the entire succession of processes from past vegetation to the anthracological diagram we propose a review of the taphonomic processes affecting anthracological assemblages in archaeological contexts from wood gathering to the analysis of charcoal results human practices appear clearly as the first filter determining or conditioning the assemblage the combustion process can induce a double filter by limiting the taxonomic information and by falsifying the initial quantity of burned wood post depositional agents represent a third level of filters between the vegetation and the anthracological assemblage finally sampling and quantification methods can also induce a distortion of the assemblage the aim of this paper is to present the state of the discipline today the problems already solved and the questions that remain to be studied

water erosion in the southern french alps climatic and human mechanisms abstract a large number of studies have focused on water erosion in the southern alps because of its intensity and the high erodability affecting numerous outcrops in this region the aim of this paper is to determine the relations between natural and human factors on the one hand geomorphologic behaviour of hillslopes and fluvio torrential dynamics at two time scales geological and historical on the other hand this paper specially focuses on the recent weakening of torrential activity and its linkage with reforestation and rural desertion on the watersheds another objective is to compare these results with a rich mainly french scientific production on this theme experimental data on current erosion measurements and the analysis of its processes on the one hand and geomorphologic background of river beds and slopes are compared and analysed using archives and the present knowledge on historical climate it has been shown that the overexploitation of watersheds leads to an increase in soil loss in the number and intensity of floods in alpine valleys as well as to an enhancement of sediment transport however climatic changes during the holocene and during the past millennium have resulted in changes in morphological behaviour of the hillslopes upstream and of river beds downstream moreover a strong sedimentary deficit can be observed over the last three or four decades in all the alpine massifs the consequences of this sediment deficit are firstly an entrenchment of river beds which threatens bridges and embankments this recent trend is probably due to the excessive extraction of material in gravel pits and the sedimentation in the numerous dams built between 1920 and 1980 in the entire alpine range however the entrenchment appeared recently on non exploited rivers therefore the deficit is also due to the success of the natural and artificial reforestation and torrent correction since the end of 19th century

correlations among the reflectances of vitrinite chitinozoans graptolites and scolecodonts abstract paleozoic marine sequences sampled in outcrops and wells of northeastern gaspe peninsula quebec appalachians yield kerogen composed in part of vitrinite and zooclasts chitinozoans scolecodonts and graptolites on which reflectance measurements were made the comparison between means of random measurements show that reflectance of chitinozoans is similar to that of telinite vitrinite with a cellular texture and that the reflectance of scolecodonts is significantly lower than that of telinite in the lower range of studied values at higher reflectivities differences decrease but at the end of the condensate gas zone reflectancea are not yet identical as shown by previous studies reflectance of graptolites is slightly less than that of telinite pyrobitumen reflectance is related to the lithology of the host rock and no generalized correlation can be established between the reflectance of pyrobitumen and that of vitrinite

dispersed organic matter from silurian shales of the barrandian basin czech republic optical properties chemical composition and thermal maturity abstract samples of lower silurian liten and kopanina formations dark shales from the barrandian basin czech republic were examined using reflected light microscopy fourier transform infrared spectroscopy ft ir and gas chromatography mass spectrometry gc ms the samples contained uniform assemblage of organic material that included dominant graptolites chitinozoa bitumens and minor anthracite to meta anthracite rank particle of unknown origin two types of graptolite morphologies were recognized a nongranular blocky type and a granular type bitumen is also common in these rocks and forms discrete oval bodies resembling droplets or angular particles with granular internal fabrics the thermal maturity of the sediments was examined by measuring random reflectance of organic particles the variations in graptolite reflectance in between three localities in the western part of the basin were relatively minor suggesting a similar level of diagenetic transformation the values range from 0 78 to 1 53 rr the reflectance of graptolites was correlated with the reflectance of chitinozoa and bitumen and also indirectly with illite crystallinity data which indicates thermal maturation levels in the high temperature part of the oil window to the onset of wet gas condensate zone mature petroleum that commonly impregnates veins crosscutting the sequence further supports a maturation level within the oil window graptolite and bitumen reflectance values markedly elevated above the regional diagenetic background were found in several centimeter wide contact zones immediately adjacent to basalt sills that locally penetrate the silurian strata as shown by computer modeling heating in the range of 600 800 c which lasted only several years was sufficient to promote an increase in reflectance up to 2 2 5 rr in the contact samples with increasing thermal stress the graptolite periderm undergoes progressive optical and structural changes being gradually converted into a highly condensed aromatic residuum structurally and chemically similar to highly matured kerogen on a basin wide scale however the overall impact of basalt intrusions on organic maturity of enclosing shales was minimal

ghost of seagrasses past using sirenians as a proxy for historical distribution of seagrasses abstract seagrasses are a notable component of shallow marine habitats especially in tropical and subtropical regions their fossil record extends back to the mesozoic but it is relatively poor and fragmentary with large temporal and geographical gaps as a result very little is known about the paleobiogeography of these plants and how physical drivers such as climatic or oceanic events have affected their distribution one approach is to infer the past distribution of seagrasses using fossils of organisms dependent of seagrasses with more complete records as proxies seagrass consumers such as sirenians seacows manatees and dugongs are much better represented in the fossil record than seagrasses are the characteristically dense bones of sirenians together with the fact that they are usually found in marginal marine environments increases the potential for preservation and recognition of their fossils the long evolutionary history of sirenians extending throughout most of the last 50 ma together with their diet permits the use of their fossils as a proxy for inferring the paleobiogeography of seagrasses here i looked at the fossil record of sirenians and seagrasses from the eocene through the miocene epochs this comparison produced several inferences about seagrass paleobiogeography and how physical drivers such as climate change ocean currents and tectonic events have been influential in their distribution 1 seagrasses were well established in the western atlantic caribbean prior to the middle eocene making possible at least two instances of trans atlantic sirenian dispersal events either with the aid of tethyan currents or along the nearly continuous northern atlantic coastline that was present in the eocene 2 climatic cooling during the early oligocene seemed to have limited the extent of seagrasses and sirenians although these groups recovered and further diversified and expanded their distributions by the late oligocene in tandem with a climatic warming event 3 by the miocene seagrasses and sirenians reached the southern western atlantic and the eastern pacific aided by the presence of the central american seaway achieving a distribution similar to and sometimes surpassing that of today the fossil record of sirenians can provide a broad overview of seagrass paleobiogeography through time however several aspects such as when sirenians and seagrasses arrived to australia and the seemingly late arrival of seagrasses to south america and the eastern pacific still need further investigation

7200 years of rhone river flooding activity in lake le bourget france a high resolution sediment record of nw alps hydrology magnetic susceptibility ms was measured with high resolution 5 mm on a 9 m long 14c dated core from lake le bourget savoie france spanning the last 7200 years the strong correlation r 0 85 of the ms with the silicate borne suite of elements si al fe mg k and anti correlation with the carbonate content r 0 87 allows it to be used as a proxy for the fluctuations of the abundance of riverborne clastic fraction versus authigenic carbonates in sediment as the rhone is the only river bringing a significant amount of silicate minerals to the coring site the ms downstream is interpreted as a proxy of the rhone suspended load discharge in lake le bourget this is confirmed over the last 3000 years by the good match with the evolution of hydrological activity of the rhone as it is known through geomorphological studies of well dated archaeological sites over the last 7200 years the record is consistent with the regional record of lake water level fluctuations while the intensity of the ms

facies patterns and geography of the yangtze region south china through the ordovician and silurian transition abstract lithofacies and biofacies changes through the ordovician and silurian transition on the yangtze platform are coincident with stepwise mass extinctions recovery events global sea level changes and regional palaeogeographic configurations facies patterns through three intervals the late mid ashgill hirnantian and early rhuddanian indicate that black shale occupied most of the yangtze platform region during the late mid ashgill and early rhuddanian while the hirnantian possesses more diverse facies types the black shale was replaced by carbonate facies during the hirnantian coincident with a global sea level low stand biofacies changes from the late mid ashgill graptolitic to the hirnantian shelly facies were apparently signalled by gradual and diachronous existence of a mixed facies the manosia facies in the yangtze region however the biofacies change was abrupt from the hirnantian to the early rhuddanian when graptolitic facies occupied most areas on the yangtze platform leaving only a very narrow limited belt of shelly facies along the southern margin of the platform in northern guizhou the early rhuddanian unified biofacies pattern is a result of a global sea level rise which may be synchronized with a recovery bioevent of graptolites after hirnantian mass extinction

seagrass meadow sedimentary facies in a mixed siliciclastic carbonate temperate system in the tyrrhenian sea pontinian islands western mediterranean abstract the paper presents the characteristics of surface sediments in a seagrass dominated environment of the inner shelf of the pontinian islands tyrrhenian shelf central mediterranean the aims of this work are to characterize the carbonate production and sedimentary processes of a representative high latitude temperate posidonia oceanica dominated area to discuss the role of seagrass in the siliciclastic carbonate mixing processes which provide analogs for interpreting the occurrence and importance of these types of deposits in the rock record the majority of sediments are poorly sorted siliciclastic skeletal sand based on grain type and abundance and carbonate content these deposits include six subfacies the different subfacies reflect environmental changes within the seagrass environment associated with variations in light penetration and hydrodynamic conditions additionally the seagrass facies range from purely carbonate to mixed carbonate siliciclastic depending on the amount of siliciclastic input and on the capacity of seagrasses to trap allochthonous sediments while hosting carbonate producing biota the type of substrate and the erosion and transport processes control the siliciclastic input in these pontinian seagrass meadows sedimentary facies contain abundant siliciclastic grains produced by erosion of the volcanic substrate and trapped by seagrass blades and rhizomes this pontinian example illustrates that in heterozoan dominated seagrass settings mud producing green algae are not present or are not calcifying and consequently seagrass deposits are much more grainy than photozoan counterparts ancient heterozoan tropical seagrass deposits likely will be discriminated from their temperate or subtropical counterparts only by careful taxonomic analysis of skeletal grains

graptolite reflectance in the prehnite pumpellyite zone of northern maine u s a abstract reflectance data has been collected on ordovician lower devonian graptolites from the prehnite pumpellyite metamorphic region in northeast aroostook county maine u s a at the northern end of the appalachian mountain belt the data is reported as the mean maximum reflectance which crossplots maximum and minimum reflectance vs bireflectance demonstrate is similar for samples mounted either perpendicular or parallel to bedding given a moderately sized data set 20 points like the prehnite pumpellyite subfacies graptolite reflectance increases from west 1 5 to east 5 5 and supports a post early devonian acadian age for the regional metamorphism reflectance contours show however that the area of highest metamorphism is to the east rather than the southeast where limited data suggest the level of metamorphism may actually decrease slightly illustrating the advantage of continuously increasing organic maturation indicators for outlining thermal patterns in broad areas of low grade regional metamorphism

recognising macrophyte vegetated environments in the rock record a new criterion using hooked forms of crustose coralline red algae abstract the role of macrophytes such as seagrasses in influencing deposition in shallow marine environments has long been understood they affect sediment textures such that they do not reflect ambient hydrodynamic conditions and so the recognition of ancient vegetated environments is important for accurate palaeoenvironmental analysis however there is little direct fossil evidence of such plants in the rock record and so the presence of former macrophyte cover generally has to be inferred from indirect evidence based on the characteristics of modern macrophyte vegetated environments we present a new criterion for the recognition of vegetated environments in the rock record based upon a distinctive hooked form of crustose coralline red algae that is definitively indicative of growth on seagrasses and also on other macrophytes with similarly flattened blades and has been recognised from both modern inhaca island mozambique and fossil the eocene of oman seagrass beds

headwater valley response to climate and land use changes during the little ice age in the massif central yzeron basin france the geomorphological response of valley bottoms in eastern france to climatic fluctuations of the little ice age lia was investigated using sedimentological analysis together with optically stimulated luminescence osl and radiocarbon dating diachronic mapping of land use since the beginning of the nineteenth century was also carried out since a d 1500 the valley bottoms experienced three cycles of aggradation and subsequent incision each characterized by paired periods of high and low detritic activity while the impact of human activity on the aggradation of the alluvial plain is observed the vertical dynamics of the valley bottom deposits seemingly were also linked to the hydroclimatic fluctuations during the lia the sensitivity to these fluctuations was increased by human activity at the scale of the basin variations of the winter north atlantic oscillation nao and solar activity from the last five centuries correlate with wet and cold phases during which valley bottoms accumulated and dry and warm phases during which the streams incised into the valley floors this fluvial sensitivity to the meteorological conditions induced temporal variations in sedimentary supply originating from either direct input from remnants of periglacial alluvial sheets or local rocky outcrops and or from indirect input from the erosion of alluvial and colluvial deposits these two components combined with the sheet runoff over the ploughlands express the complex coupling between hillslopes and valley bottoms in the headwater catchments this caused a cascade shaped transit of the sediments characterized by alternating phases of storage and removal keywords little ice age headwater valley bottom deposits aggradation incision cycle osl and radiocarbon dating landscape history massif central

epiphytic calcium carbonate production and facies development within sub tropical seagrass beds inhaca island mozambique seagrass beds have been widely recognised as playing an important role in influencing carbonate sediment facies development this reflects their role not only as facilitators of fine sediment settling and stabilisation but also as substrates for epiphytic organisms that after death contribute skeletal carbonate to the sediment substrate in low latitude reef related settings epiphytic carbonate production rates are often high and this in combination with the trapping of carbonate mud produced by a range of associated calcareous algal species typically results in the development of carbonate mud rich facies whilst such environments and their associated sediment substrates have been widely documented studies of seagrass facies in marginal sub tropical warm temperate marine settings have not been conducted from a sedimentological perspective this study determines rates of epiphytic carbonate production on two seagrass species thalassodendron ciliatum and thalassia hemprichii and examines seagrass sediment facies from a sub tropical reef related environment in southern mozambique dense seagrass beds colonise primarily siliciclastic sediment substrates and are characterised by low rates of epiphytic carbonate production mean 43 9 g caco3 m 2 year 1 for t ciliatum and 33 4 g caco3 m 2 year 1 for t hemprichii epiphytic encrusters are dominated by thin monostromatic layers of the crustose coralline red algae hydrolithon farinosum along with rotaliid smaller benthic foraminifera including asterorotalia cf gaimardi and spirillina sp and the soritid peneroplis sp as well as rare encrusting acervulinid foraminifera serpulids and bryozoans epiphytic calcium carbonate production rates are therefore low and this is reflected in the low 15 carbonate content of the seagrass sediments as well as the low 1 sediment fine 63 m size fraction content this study suggests that mud rich sediment facies do not necessarily develop in conjunction with seagrass beds and that mud poor facies may develop in some seagrass colonised environments at these sites sub tropical and siliciclastic sediment dominated this is suggested to reflect both the low levels of epiphytic and benthic algal carbonate mud production as well as a net outflux of fine grained sediment due to tidal current induced sediment resuspension in keeping with carbonate facies generally there are thus likely to be latitude and environment related shifts in the composition and character of seagrass related sediment facies

the middle eocene seeb formation of oman an investigation of acyclicity stratigraphic completeness and accumulation rates in shallow marine carbonate settings abstract the middle eocene seeb formation represents deposition on one of the earliest modern style carbonate platforms i e influenced by seagrasses and mangroves and presents an opportunity to explore controls on the preservation of cenozoic carbonate lithofacies in the study area the seeb fm is dominated by an anomalously thick approximately 250 m and uniform package of shallow marine platform interior sediments these nodular indistinctly bedded shallow subtidal sediments display no evidence for relative sea level change such as subaerial exposure features and lack the shallowing upwards cyclothems that have characterized carbonate sediments deposited in platform interior settings throughout much of the rock record particularly during greenhouse periods we conclude that this is a consequence of thorough bio retexturing of the sediment by burrowing organisms and the roots of marine vegetation which destroyed primary fabrics facies diversity evidence for cyclicity and missing time horizons such as cycle bounding exposure surfaces it seems possible that the remarkable thickness of apparently acyclic seeb fm sediment that built up may reflect increased bio disturbance of the shallow marine environment following the late cretaceous expansion of seagrasses and mangroves a similar lack of peritidal cyclothems may be common to many cenozoic shallow marine carbonate deposits missing time horizons in limestones reflecting erosion or nondeposition have been identified by some authors to explain discrepancies between low calculated accumulation rates of ancient sediments and higher rates measured in comparable modern environments however our studies of the seeb fm suggest that the significance of such missing time horizons in ancient sediments may have been overstated and that apparent differences between modern and ancient accumulation rates are a consequence of the extrapolation of unrepresentative localized high rates of modern sediment production to large platform scale areas our study reinforces the idea that modern sediment production and accumulation rates may be much lower than previously thought because they are typically measured in highly productive areas such as seagrass beds and do not take into account the highly variable nature of carbonate production storage erosion and destruction across platforms therefore far less missing time needs to be inferred for ancient sediments to account for any imbalance between modern and ancient sediment accumulation rates

a geochemical and sedimentological perspective of the life cycle of neapolis harbor naples southern italy since the discovery of the ancient harbor of naples in 2004 during construction work on an underground railway geoarchaeological studies undertaken on the archaeological excavation have revealed the main stratigraphic and paleo environmental levels of the harbor site near the piazza municipio however knowledge of the dynamics and paleoenvironmental changes in the water column of the harbor as well as the processes of transport and deposition of sediments that led to siltation and infilling of the harbor basin has been lacking due to the absence of high resolution data to fill these gaps we have undertaken a threedimensional study longitudinal transverse and vertical of the harbor deposits by carrying out geochemical and sedimentological analyses of four stratigraphic sections of the archaeological excavation the results show that after a phase of relative calm during the first half of the 1st c ad siltation of the harbor progressed exponentially up to the 5th c ad when dredging operations were carried out to obtain a water level sufficient for the development of maritime and harbor activities we attribute this acceleration of siltation to a combination of climatic anthropic and volcanic factors volcanic activity was responsible for a high energy tsunami type event during the eruption of vesuvius in 79 ad from the 5th c ad onwards the harbor basin of neapolis does not appear to have been functional as evidenced by its transformation into a lagoon following coastal progradation the last stage of infilling was the development of a flood dominated fan delta under the combined influences of climatic cooling in the early medieval cool period and agro pastoral activities in the catchment area of the harbor several generations of paleo channels containing flash flood deposits as well as sheet wash from sheet floods are indicative of high environmental instability in this period

maastrichtian to early tertiary stratigraphy and palaeogeography of the central and northern oman mountains abstract maastrichtian to tertiary sedimentary rocks outcrop extensively around the periphery of the oman mountains they form part of a geologically distinct suite of strata deposited after obduction of the semail ophiolite and thrusting of the hawasina and sumeini imbricates onto the eastern edge of the arabian plate the lithostratigraphy of maastrichtian and early tertiary rocks of the central and northern oman mountains is revised and a number of new formations are erected the proto oman mountains were emergent in the early maastrichtian and were subject to subaerial erosion and weathering nw and w of the mountains gradual subsidence followed during the maastrichtian allowing for formation of a transgressive onlapping sequence represented by the qahlah fluviatile to shallow marine terrigenous clastics and simsima shallow shelf carbonate formations more rapid subsidence ne of the mountains produced fan delta and submarine debris flow turbidite apron sequences comprising the al khawd and thaqab formations respectively a low angle unconformity separates tertiary strata from older units during the palaeogene basinal and slope facies with debris flows and turbidite sequences were deposited directly upon the unconformity surface in rapidly subsiding basins nw muthaymimah formation and nne ruwaydah formation of the oman mountains elsewhere shallow carbonate shelf facies were extensively developed in less rapidly subsiding areas during the palaeogene the palaeocene and early eocene is represented by the jafnayn limestone formation this is succeeded and overlapped by a variety of later eocene units ene and e of the mountains early eocene regression is marked by restricted facies of the rusayl formation overlying the rusayl formation are shallow open shelf limestones of the seeb formation which is rich in alveolinid and nummulitic foraminifera on the arabian side of the mountains the rusayl formation is not developed and the jafnayn formation is succeeded either by the seeb formation or fine grained faunally restricted limestones and marls of the fahud beds which represent intra shelf facies

1400 years of extreme precipitation patterns over the mediterranean french alps and possible forcing mechanisms investigation of lake allos sediments revealed 160 graded layers interpreted as flood deposits over the last 1400 yr comparisons with records of historic floods support the interpretation of flood deposits and suggest that most recorded flood events are the result of intense meso scale precipitation events as there is no evidence for any major changes in erosion processes in the catchment since the medieval warm period mwp we interpret the allos record in terms of repeated intense precipitation events over the last millennium with a low flood frequency during the mwp and more frequent and more intense events during the little ice age this interpretation is consistent with the pattern of increasingly humid conditions in the northwestern mediterranean region this long term trend is superimposed on high frequency oscillations that correlate with solar activity and autumnal north atlantic oscillation nao finally a comparison of flood records across the northwestern mediterranean region showed that intense precipitation events in allos east of the rhone valley were out of phase with events in the cevennes west of the rhone but in phase with events in eastern spain supported by meteorological analyses this suggests an oscillation in atmospheric circulation patterns over the northwestern mediterranean

evidence for seagrass meadows and their response to paleoenvironmental changes in the early eocene jafnayn formation wadi bani khalid n oman the recognition and understanding of vegetated habitats in the fossil record are of crucial importance in order to investigate paleoecological responses and indirectly infer climate and sea level changes however the low preservation potential of plants and macroalgae hampers a direct identification of these environments in the geological past here we present sedimentological and paleontological evidences as tool to identify the presence of different seagrass vegetated environments in the shallow marine settings of the lower eocene jafnayn platform of oman and their responses to paleoenvironmental changes the studied lower eocene deposits consist of well bedded nodular packstones dominated by encrusting acervulinid and alveolinid foraminifera passing upward to an alternance of packstones with echinoids and quartz grains and grainstones rich in orbitolites smaller miliolid foraminifera and quartz grains the presence of seagrass is inferred by the occurrence of encrusting acervulinids and soritid orbitolites as well as by their test morphologies together with further sedimentological criteria the clear shift observed in the faunal assemblages and sedimentary features may be related to a major reorganization of the carbonate system passing from a carbonate platform to a ramp like platform with increased terrigenous sedimentation heterotroph tubular acervulinids and oligotroph alveolinids of the carbonate platform were replaced upward by more heterotroph organisms such as large discoidal orbitolites and smaller miliolids most likely due to enhanced nutrient levels which would have led to a change of phytal substrate from cylindrical leaf dominated grasses into flat leafed ones

natural streams and the legacy of water powered mills gravel bedded streams are thought to have a characteristic meandering form bordered by a self formed fine grained floodplain this ideal guides a multibillion dollar stream restoration industry we have mapped and dated many of the deposits along mid atlantic streams that formed the basis for this widely accepted model these data as well as historical maps and records show instead that before european settlement the streams were small anabranching channels within extensive vegetated wetlands that accumulated little sediment but stored substantial organic carbon subsequently 1 to 5 meters of slackwater sedimentation behind tens of thousands of 17th to 19th century milldams buried the presettlement wetlands with fine sediment these findings show that most floodplains along mid atlantic streams are actually fill terraces and historically incised channels are not natural archetypes for meandering streams

palaeogeographical and palaeoenvironmental reconstruction of the medjerda delta tunisia during the holocene abstract the progradation of the medjerda delta has been the subject of many studies since the 19th century the scale and the rapidity of this phenomenon interested researchers in various fields early on such as geomorphology geology palaeogeography history archaeology or geoarchaeology indeed the delta prograded by around 10 km over 3 millennia at the time of its foundation supposedly at the end of the 12th century bc the phoenician city of utica was located on a promontory bathed by the sea but the sediments carried by the medjerda progressively sealed the bay leaving the tip of the utica promontory now 10 km inland this area is therefore an exception to the general pattern along the tunisian coast since as over the same period everywhere else there is a regression of the coastline owing to a sea level rise of several decimeters based on multi proxy analyses of two coring transects this paper aims to reconstruct the palaeoenvironments and the palaeogeography of the medjerda delta s progradation since the mid holocene some aspects of which are described in ancient sources the results highlight in particular an episode of high intensity flooding around the 4th century ad which is consistent with episodes of high floods and an increase in sedimentation rates recorded in the watershed at the end of the roman period the gradual abandonment of the city of utica can certainly be related to the activity of the medjerda river but our results show that it is because of an increase of fluvial sediment contribution in connection with an erosive crisis in the headwaters and not because of the change of course of the river which had occurred long before

optical properties of scolecodonts and their use as indicators of thermal maturity abstract dispersion of reflectances in air and oil between 400 and 700 nm of a suiteof scolecodont concentrates with known conodont alteration index was determined using a reflected light microscope refractive and absorptive indices of these scolecodonts were calculated using their determined reflectances morphologically scolecodonts in carbonate show similar granular morphology to that of graptolites fine structural details of scolecodonts can be observed under reflected light reflectances refractive and absorptive indices of scolecodonts at 546 nm increase with increase of the conodont alteration index indicating that these properties of scolecodonts can be used to determine the maturity of sediments dispersion of the optical properties of scolecodonts follows similar trends to those for vitrinite natural bitumen and graptolites indicating similar molecular structural changes with increasing maturity

reflectance of vitrinite like macerals as a thermal maturity index for cambrian ordovician alum shale southern scandinavia the middle cambrian to lower ordovician alum shale in southern scandinavia contains kerogen macerals resembling vitrinite the age of this rock unit excludes terrestrially derived vitrinite as an origin for these macerals nevertheless the vitrinite like macerals respond to heating in a way similar to that of suppressed vitrinite in younger shales this similarity is demonstrated both for the natural system where alum shale maturity ranges from immature to low grade metamorphic conditions and for hydrous pyrolysis experiments where an immature sample of alum shale was isothermally heated at temperatures ranging from 280 to 360 degrees c for 72 hr reflectance values from the naturally matured alum shale show an increase in standard deviations i e anisotropy with i creasing maturity and a negative relationship with atomic h c ratios of the total kerogen these relationships are similar to those observed in post ordovician vitrinites comparisons with other vitrinites subjected to hydrous pyrolysis indicate the vitrinite like macerals in the alum shale follow the suppressed vitrinite pathway rather than the coal vitrinite pathway the occurrence of vitrinite like macerals in the alum shale indicates that traditional vitrinite reflectance measurements are useful in evaluating thermal maturity of pre silurian rocks

luminescence dating of hillslope deposits a review abstract luminescence dating determines the last exposure to light of quartz and feldspar mineral grains and thus the time a sediment was laid down prerequisite is that the sediment grains were sufficiently exposed to light prior to deposition for eolian deposits this seems a fair assumption although exceptions may well exist for other depositional environments light exposure prior to burial is often restricted in duration intensity and spectral composition and may result in an age overestimation recent developments now allow dating of sediments that were exposed to only little light prior to deposition the main developments are single aliquot techniques and statistical tests that allow extraction of valid age estimates even from deposits in which bleached and unbleached grains are mixed these developments in combination with the fact that the great majority of sediments near the earth s surface are not of eolian origin have resulted in the large interest in the luminescence dating of non eolian deposits here we review possibilities and challenges of luminescence dating of colluvial deposits we summarize techniques for the detection and handling of insufficiently bleached sediments a common condition in colluvial deposits we give an overview how luminescence dating has been applied on hillslope sediments for reconstructing landscape response to climate change to analyze past fault activity and unravel human induced soil erosion we discuss sampling strategies and give guidelines as to which techniques are best suited to establish luminescence chronologies for colluvium

organic petrography of graptolite fragments from turkey abstract the reflectance and bireflectance of graptolite fragments silurian ordovician from southeast turkey were examined and the morphology was described using reflected light microscopy the dispersion of maximum and minimum reflectance of graptolites sectioned parallel and perpendicular to the bedding was also determined the graptolites were anisotropic and the anisotropy was stronger for sections perpendicular to the bedding the graptolite fragments show two types of surface morphology granular and non granular the granular type had a rough surface and granular anisotropy the non granular fragments showed a smooth surface and basic anisotropy the fine internal structure of graptolite was evident under crossed polars the reflectance of graptolite increased with depth and was higher than other organic material e g bitumen found in the same sediment the present study indicates that the reflectance of graptolite in sediment can be used to determine the maturity of the dediment

investigation of thermal maturity of lower palaeozoic hydrocarbon source rocks by means of vitrinite like maceral reflectance a tarim basin case study evaluation of the maturity of chinese lower palaeozoic sediments has not been satisfactorily accomplished because of the absence of vitrinite and the relatively high level of maturity of the organic matter in the tarim basin one of the largest petroliferous basins in china important lower palaeozoic marine sediments contain a widely distributed type of maceral resembling vitrinite especially characterised by syndepositional occurrence elongate shape homogenous texture and weak anisotropy the term vitrinite like maceral is used to describe the maceral in this paper because of insufficient evidence for its origin thirty five lower palaeozoic source rocks mainly from five boreholes in the tarim basin have been investigated by organic petrologic methods and a positive correlation between the vitrinite like maceral reflectance and sample depth has been recognized this correlation is better than that between bitumen reflectance and depth artificial maturation data show that the maturation pathway of vitrinite like macerals is quite different from that of vitrinite there is a distinct step in the development of reflectance of vitrinite like macerals with increasing maturation by combining the reflectance data from naturally and artificially matured samples the relationship between vitrinite like maceral reflectance and vitrinite reflectance can be divided into three stages which are well represented by three linear regression equations the equations provide a convenient method to evaluate the maturity of lower palaeozoic sediments by allowing an equivalent vitrinite reflectance to be derived from the measured vitrinite like maceral reflectance

thermal maturity and burial history of paleozoic rocks in western newfoundland palynomorphs and graptolites from paleozoic strata in western newfoundland are examined and correlated with previously published data to identify fossils which are characteristic of proven and suspected source rocks measurements of colour alteration of acritarchs and spores acritarch alteration index and thermal alteration index random graptolite reflectance and vitrinite reflectance are applied to determine regional thermal maturation and burial history general trends of increasing maturity from south to north along the northen peninsula and from west to east across the port au port peninsula are observed within these general trends a more detailed distribution of thermal maturities can be recognized in the south upper ordovician rocks of the long point group western port au port peninsula exhibit the lowest maturity values found in western newfoundland and are considered immature or marginally mature middle ordovician rocks of the goose tickle and table head groups and the lower ordovician

holocene floodplain deposition and scale effects in a typical european upland catchment a case study from the ambleve catchment ardennes belgium this study quantifies holocene alluvial sediment deposition in the belgian ambleve catchment 1080 km2 situated in the ardennes uplands an extended coring data set is used for a quantitative description and a quantification of the alluvial depositions the floodplains fall into three main types the upper and lower floodplains and the steep reaches total holocene alluvial sediment deposition amounts to 32 tg or 0 029 tg km2 dating of sediments using iron slag as tracer shows that on average 42 of contemporary storage was accumulated during the last 600 years radiocarbon dating of fluvial deposits at eight sites in the catchment confirms that the majority of the sediment is relatively recent the increased sedimentation rates for this period are related to anthropogenic land use possibly enhanced by climatic variations a fluvial sediment budget was constructed for this 600 yr time period and shows that export from the catchment has about the same importance as storage in the floodplains while la

the eocene rusayl formation oman carbonaceous rocks in calcareous shelf sediments environment of deposition alteration and hydrocarbon potential paralic carbonaceous series intercalated among calcareous shelf sediments have seldom been investigated during the early eocene calcareous and siliciclastic sediments were deposited on a wide shelf in front of low reliefed hinterland in the al khawd region in ne oman the siliciclastic calcareous sediments originated from strongly reworked debris of the arabic shield the underlying semail ophiolite did not act as a direct source of debris but provided some heat to increase the maturity of carbonaceous rocks and modify the isotope signal of the calcareous minerals in the rusayl formation a multidisciplinary approach involving sedimentology mineralogy chemistry coal petrography and paleontology resulted in the establishment of nine stratigraphic lithofacies units and provides the reader with a full picture from deposition of the mixed carbonaceous calcareous siliciclastic rocks to the most recent stages of post depositional alteration of the paleogene formations the calcareous jafnayn formation lithofacies unit 1 developed in a subtidal to intertidal regime influenced episodically by storms deepening of the calcareous shelf towards younger series was ground to a halt by paleosols developing on a disconformity lithofacies unit 11 and heralding the onset of the rusayl formation the stratigraphic lithofacies units iii and iv reflect mangrove swamps which from time to time were flooded through washover fans from the open sea the presence of spinozonocolpites and the taxon avicennia which today belong to a coastal marsh vegetational community furnish palynological evidence to the idea of extensive mangrove swamps in the rusayl formation el beialy s y 1998 stratigraphic and palaeonenvironmental significance of eocene palynomorphs from the rusayl shale formation al khawd northern oman review of palaeobotany and palynology 102 249 258 during the upper rusayl formation lithofacies units v through vii algal mats episodically flooded by marine incursions make up a greater deal of the sedimentary record than mangrove swamps terra rossa paleosols mark the end of accumulation of organic material om and herald supratidal conditions at the passage of rusayl formation into the overlying seeb formation in the subtidal supratidal cycles of lithofacies unit viii the terra rossa horizons are thining upwards and become gradually substituted for by deep water middle ramp sediments of lithofacies unit ix framboidal pyrite ferroan dolomite with very little siderite are indicative of an early diagenetic alteration stage i under rather moderate temperatures of formation

the campo section pyrenees spain revisited implications for changing benthic carbonate assemblages across the paleocene eocene boundary abstract the campo section is a parastratotype section for the shallow water ilerdian and cuisian stages although a lot of work has been concentrated during the last years on biostratigraphy sequence stratigraphy magnetostratigraphy and geochemistry surprisingly little work has been published on the facies development here we evaluate the facies evolution with particular emphasis on the biogenic assemblages of the latest paleocene shallow benthic zonation 4 to the earliest eocene shallow benthic zonations 5 and 6 of the campo and the nearby serraduy section overall the facies show a deepening in the paleocene and the eocene interrupted by a terrestrial interval across the newly defined paleocene eocene boundary in the late paleocene altogether seven microfacies types were distinguished these are dominated by various algal taxa and subordinate corals and larger foraminifera the lower eocene carbonate platform is characterised by twelve microfacies types which are dominated by larger foraminifera such as alveolinids orbitolitids and nummulitids and subordinate corals this facies dichotomy recognized in the campo and serraduy sections can be extrapolated to the whole pyrenean region in the early paleogene and is even found in egypt the comparison of the two regions shows that the facies dichotomy is less pronounced in the pyrenean region this is interpreted to reflect a latitudinal trend where corals are absent in the low latitudes while in the middle latitudes they occur subordinately this gradient within the facies distribution can be explained by latitudinal temperature changes and by the long time warming in the early paleogene and the short time warming of the paleocene eocene thermal maximum hot temperatures in the low latitudes hamper the growth of temperature sensitive corals while in the middle latitudes the temperatures were still in a favourable temperature range