from greenhouse to icehouse organic walled dinoflagellate cysts as paleoenvironmental indicators in the paleogene abstract dinoflagellates are an important component of the extant eukaryotic plankton their organic walled hypnozygotic cysts dinocysts provide a rich albeit incomplete history of the group in ancient sediments building on pioneering studies of the late 1970s and 1980s recent drilling in the southern ocean has provided a wealth of new dinocyst data spanning the entire paleogene such multidisciplinary studies have been instrumental in refining existing and furnishing new concepts of paleogene paleoenvironmental and paleoclimatic reconstructions by means of dinocysts because dinocysts notably exhibit high abundances in neritic settings dinocyst based environmental and paleoclimatic information is important and complementary to the data derived from typically more offshore groups as planktonic foraminifera coccolithophorids diatoms and radiolaria by presenting case studies from around the globe this contribution provides a concise review of our present understanding of the paleoenvironmental significance of dinocysts in the paleogene 65 25 ma representing earth s greenhouse icehouse transition this episode holds the key to the understanding of extreme transient climatic change we discuss the potential of dinocysts for the reconstruction of paleogene sea surface productivity temperature salinity stratification and paleo oxygenation along with their application in sequence stratigraphy oceanic circulation and general watermass reconstructions

new insights into salt tectonics in the northern dutch offshore a framework for hydrocarbon exploration the northern dutch offshore is an area that has seen less hydrocarbon exploration activity than other areas of the netherlands acquisition of a new regional 3d seismic dataset allowed further testing and re evaluation of established geological concepts in this area it is recognized that the presence and movement of upper permian zechstein evaporites had a major impact on depositional patterns in mesozoic sediments structural development and hydrocarbon migration as such this study looks specifically at the role of salt tectonics in tectonosedimentary development to assess this salt tectonic evolution within its structural context a restoration of the step graben and dutch central graben was performed it follows that depositional patterns are closely linked to the nature of salt structure movement and the timing of regional tectonism for example during late triassic rifting salt pillows developed and sedimentation focused away from salt structures into depocentres along regional fault trends restoration results show that this interplay between salt movement and tectonism is needed to accommodate the sedimentation patterns associated with the formation of the step graben and central graben during the triassic and jurassic and later during late cretaceous and cenozoic inversion tectonics 2018 the author s

new insights on subsurface energy resources in the southern north sea barrin area the southern north sea basin area stretching from the uk to the netherlands has a rich hydrocarbon exploration and production history the past present and expected future hydrocarbon and geothermal exploration trends in this area are discussed for eight key lithostratigraphic intervals ranging from the lower carboniferous to cenozoic in the period between 2007 and 2017 a total of 95 new hydrocarbon fields were discovered particularly in upper carboniferous rotliegend and triassic reservoirs nineteen geothermal systems were discovered in the netherlands onshore mainly targeting aquifers in the rotliegend and upper jurassic lower cretaceous formations although the southern north sea basin area is mature in terms of hydrocarbon exploration it is shown that with existing and new geological insights additional energy resources are still being proven in new plays such as the basal upper rotliegend ruby discovery for natural gas and a new chalk play for oil it is predicted that hydrocarbon exploration in the southern north sea basin area will probably experience a slight growth in the coming decade before slowing down as the energy transition further matures geothermal exploration is expected to continue growing in the netherlands onshore as well as gain more momentum in the uk

chemostratigraphy of upper jurassic reservoir sandstones danish central graben north sea abstract a chemostratigraphic study of upper jurassic sandstones in the northern danish central graben has been undertaken within the framework of a well defined stratigraphic sedimentological model based particularly on cored well sections two reservoir sandstone units are recognised the transgressive marginal marine to shoreface sandstone of the gert member and the regressive to transgressive shoreface sandstone of the ravn member both members belong to the heno formation which is equivalent to the fulmar formation uk and the ula formation norway multivariate analysis of geochemical data from 264 core samples from 8 wells reveals the distinction between the two reservoir sandstones gert and ravn members and the two offshore claystones farsund and lola formations specific elements have proven to be important for this separation and these elements demonstrate differences even in 2 dimensional cross plots the farsund formation is characterised by higher v u and p 2 o 5 and lower mgo and k 2 o when compared with the lola formation the gert member typically has higher maximum amounts of cr and tio 2 than the ravn member the high cr and tio 2 content probably from chrome spinel and ti minerals might be related to a source of exposed carboniferous sediments in the gert ridge area the ravn member is characterised by higher na 2 o p 2 o 5 and th contents than the gert member which may reflect a higher content of plagioclase na 2 o and a changed heavy mineral assemblage the mid north sea high is a likely source for the heavy mineral suite that characterises the ravn member the rita 1 well situated closest to the mid north sea high seems to have been more influenced by this source than the other wells in the hejre area a volcanic source supplying k feldspar may be responsible for the relatively high k 2 o al 2 o 3 observed in both the gert and ravn members hence in addition to differentiation between the two reservoir sands and between the two offshore claystones this study also illustrates the use of geochemical data for evaluation of source characteristics and dominance of different sediment source areas

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

topological characterization of pore space in soil sample preparation and digital image processing the connectivity of pore space is an important topological property of soil together with the porosity and the pore size distribution it governs the transport of water solutes and gases this paper describes the euler poincare characteristic epc as an index of connectivity of soil pore space in three dimensions and shows how the epc can be estimated by analysing pairs of parallel images so called disectors automatically we investigated the connectivity of pores 50 m within two horizons of a terra fusca from serial surfaces through undisturbed soil impregnated with resin a method is proposed for the segmentation of the grey level images into solid and void which is especially suitable for the detection of the pore edges this results in identification of topologically distinct features the 3d epc was estimated from pairs of adjacent surfaces the disector using an algorithm to count the topological features by digital image processing the epc from 10 adjacent disectors within the two horizons are significantly different and confirm qualitative observations of more intensely connected pore space in the upper ah horizon additional results from 100 adjacent disectors in the lower ahbv horizon show the continuous evolution of the epc estimates over a distance of 5 mm where two different scales of variation can be distinguished clearly a small scale variation which is attributed to methodological errors and a large scale variation reflecting the variability of the structure

the impact of wallachian settlement on relief and alluvia composition in small valleys of the carpathian mts czech republic abstract the impact of the wallachian settlement on small mountain catchments has been studied at the example of skor ansk and hartisov streams moravskoslezske beskydy mts western outer carpathians between the 16th and the 19th centuries the wallachian people introduced pastoral management originating from the woodless balkans to the forested mid altitude mountain area under study this area was subjected to rapid settlement intense grazing in forests and slash and burn deforestation to assess the geomorphic effects of wallachian activity in the catchments studied grain size structure organic matter content and the plant macrofossil composition of the alluvia forming terrace levels in the mouths of the skor ansk and hartisov streams were analysed radiocarbon dating 137 cs and 210 pb analyses and dendrochronological dating were also applied to determine the age of the alluvia studied the results were compared with land use and land cover changes recorded on archival maps and pictures and with population changes in the study area it was found that the two successive trends of catchment settlement and later depopulation have led to the development of inset terraces on the outlet fans of the skor ansk and hartisov streams in the study catchments both settlement deforestation and depopulation land abandonment occurred very rapidly which also caused abrupt geomorphic changes before human disturbance fluvial erosion and the redeposition of older pleistocene deposits predominated as a result coarse gravel alluvia were deposited within stream channels the stage of massive overbank accumulation of fine grained alluvia was a reflection of intensified delivery of slope material into valley floors from catchments deforested by the wallachians the later stage of vertical incision of channels resulted from the decrease of sediment supply from hillslopes to river channels during catchment depopulation and afforestation

the co evolution of black sea level and composition through the last deglaciation and its paleoclimatic significance abstract the black sea was an inland lake during the last ice age and its sediments are an excellent potential source of information on eurasian climate change showing linkages between regionally and globally recognized millennial scale climate events of the last deglaciation here we detail changes from the last glacial maximum lgm through the transition to an anoxic marginal sea using isotopic strontium and oxygen and trace element sr ca ratios in carbonate shells which record changing input sources and hydrologic conditions in the basin and surrounding region sr isotope records show two prominent peaks between 18 and 16 ka bp cal reflecting anomalous sedimentation associated with meltwater from disintegrating eurasian ice sheets that brought black sea level to its spill point following a sharp drop in sr isotope ratios back toward glacial values two stages of inorganic calcite precipitation accompanied increasing oxygen isotope ratios and steady sr isotope ratios these calcite peaks are separated by an interval in which the geochemical proxies trend back toward glacial values the observed changes reflect negative water balance and lake level decline during relatively warm periods bolling allerod and preboreal and increasing river input less evaporation resulting in higher lake levels during the intervening cold period the younger dryas a final shift to marine values in sr and oxygen isotope ratios at 9 4 ka bp cal corresponds to connection with the global ocean and marks the onset of sedimentation on the black sea continental shelf this date for the marine incursion is earlier than previously suggested based on the appearance of euryhaline fauna and the onset of sapropel formation in the deep basin

durations of soil formation and soil development indices in a holocene mediterranean floodplain abstract holocene and late pleistocene alluvial sequences of the mid medjerda floodplain northern tunisia reveal three types of soils with gradual transitions fluvisols calcaric cambisols calcaric and calcic luvisols chromic stratigraphic cross correlations palaeomagnetic secular variation and 14 c and irsl dating enable detailed information about ages and durations of soil formation in the floodplain weakly developed fluvisols calcaric commonly reveal late holocene ages with soil formation durations lasting between 100 and 300 years hence holocene soil formation is detectable in the exposures from durations of around 100 years onwards cambisols show predominantly mid holocene ages the durations of soil formation are between 800 and 5000 years calcic luvisols chromic feature late pleistocene ages with durations of soil formation between 10 000 and 40 000 years profile development indices were computed from simple field parameters like soil structure soil colour horizon thickness and leaching features the derived development indices show good correlation r 2 0 804 with the calculated durations of soil formation field parameters are well suited for a quantitative development index of holocene soil formation even if very weak developed soils are predominant the study shows that maturity stages of holocene alluvial soils in a homogeneous mediterranean environment are predominantly driven by soil formation duration

climatic ups and downs in a disturbed jurassic world the tropical warm and equable climate of the jurassic world is regularly challenged by geoscientists especially since oxygen isotopes 18 o of fossil hardparts have been used to reconstruct the paleotemperature history of seawater by applying the innovative sizer sig nifi cant zero crossings of the derivatives statistical approach to a newly compiled 18 o data base for the jurassic we demonstrate the occurrence of major and multiscale 18 o changes mainly related to climate disturbances for the fi rst time two long term anomalies in 18 o are identifi ed during the toarcian and the late jurassic in conjunction with intensive volcanism in large igneous provinces these results support a strong infl uence of repeated volcanic pulses on the modulation of pco 2 temperatures and polar ice cap volumes over protracted periods at shorter time scales 13 relatively rapid 0 5 1 m y and signifi cant warming and cooling events are identifi ed the causes of which include transient fl uctuations in greenhouse gas con centrations related to still debated mechanisms

spatial interaction of methylene blue stained soil pores in this paper we compare different types of patterns that emerge when applying methylene blue dye as a tracer on soils to detect preferential flow paths as a result of large cracks patterns on channels vughs and cracks are analyzed with the j function and with indicator variograms by means of a combined analysis we obtained a better understanding of the patterns as well as some clear indications for precision agriculture management the study is illustrated with methylene blue patterns obtained at two locations at four succeeding depths in the netherlands

chemostratigraphy of the jurassic system applications limitations and implications for palaeoceanography current chemostratigraphical studies of the jurassic system primarily involve the use of one sedimentary component marine organic carbon one divalent transition metal substituted in carbonate manganese and two isotopic tracers strontium isotope ratios 87 sr 86 sr and carbon isotope ratios 13 c carb and 13 c org in carbonate and in organic matter other parameters such as mg ca and sr ca ratios in calcite oxygen isotope ratios 18 o in carbonate sulphur isotope ratios 34 s in carbonate hosted sulphate nitrogen isotope ratios 15 n org in organic matter osmium isotope ratios 187 os 188 os in black shales and neodymium isotope ratios 143 nd 144 nd in various mineral phases are also useful but at present give poor resolution because the database is incomplete or compromised by various factors stratigraphical patterns in total organic carbon toc can be of either local or regional significance depending on the lateral extent of the former nutrient rich and productive water mass divalent manganese follows a similar pattern being concentrated most probably as a very early diagenetic phase only in oxygen depleted waters that typically underlie zones of elevated organic productivity shifts in mg ca and sr ca ratios on the time scale of ammonite subzones seem largely to reflect temperature changes strontium isotope ratios from pristine skeletal calcite provide a global signal 13 c values from carbonates with minimal diagenetic overprint potentially do the same although small spatial differences in palaeo water mass composition may have been locally significant oxygen isotope determinations on carbonate rocks and fossils generally yield values that are too scattered to be stratigraphically useful because they reflect palaeotemperature the evaporation precipitation balance in sea water and the impact of any diagenesis involving an aqueous phase nitrogen isotope ratios in organic matter reflect the chemistry of ancient water masses as affected by nitrate utilization and denitrification and the stratigraphical pattern of this parameter is more likely to correlate only on a regional basis neodymium isotope ratios in sea water are also water mass dependent and greatly affected by regional sources and oceanic current systems preliminary data on sulphur isotope ratios in carbonates and osmium isotope ratios in organic rich shales both potentially offering global correlation indicate that these tracers may be valuable although the records at present are not sufficiently well established to allow high resolution regional correlation in all cases biostratigraphically well dated reference sections against which the relevant geochemical data have been calibrated are required in the first instance to date studies on the stratigraphical distribution of organic carbon have been principally carried out in both northern boreal and southern tethyan europe carbon isotope stratigraphy has been undertaken primarily but not exclusively on bulk pelagic sediments from the alpine mediterranean or tethyan domain and strontium isotope stratigraphy has been undertaken largely on calcitic skeletal material belemnites and oysters from northern and southern europe in many sections including those containing ammonites multi parameter chemostratigraphy can give resolution that exceeds that attainable by classic biostratigraphical means strontium isotope ratios in skeletal calcite are a particularly powerful tool for illustrating changes in sedimentary rate and revealing gaps in the stratigraphical record

holocene palaeoenvironmental change and the impact of prehistoric salt production in the seille valley eastern france the seille valley in eastern france was home to one of europe s largest iron age salt industries sedimentology palynology and geochronology have been integrated within ongoing archaeological investigations to reconstruct the holocene palaeoenvironmental history of the seille valley and to elucidate the human environment relationship of salt production a sedimentary model of the valley has been constructed from a borehole survey of the floodplain and pollen analyses have been undertaken to reconstruct the vegetation history alluvial records have been successfully dated using optically stimulated luminescence and radiocarbon techniques thereby providing a robust chronological framework the results have provided an insight into the development of favourable conditions for salt production and there is evidence in the sedimentary record to suggest that salt production may have taken place during the mid to late bronze age the latter has yet to be identified in the archaeological record and targeted excavation is therefore underway to test this finding the development of the iron age industry had a major impact on the hydrological regime of the valley and its sedimentological history with evidence for accelerated alluviation arising from floodplain erosion at salt production sites and modification of the local fluvial regime due to briquetage accumulation on the floodplain this research provides an important insight into the environmental implications of early industrial activities in addition to advancing knowledge about the holocene palaeoenvironmental and social history of this previously poorly studied region of france

mesozoic resource potential in the southern permian basin area the geological key to exploiting remaining hydrocarbons whilst unlocking geothermal potential it is generally accepted that hydrocarbon exploration in northern europe has reached a mature stage a basin s maturity is defined by the underlying number of new discoveries and the declining production rate of mature fields spe 2015 for geoscientists a mature basin has well defined characteristics in terms of for example reservoir presence or trap formation e g byrne 2012 it is interesting therefore to note how much is still unknown about certain stratigraphic intervals in northern europe the mesozoic overburden of the southern permian basin sensu maystrenko et al 2008 doornenbal stevenson 2010 continues to provide fresh insights into the geological history of an area where as the name suggests historical hydrocarbon exploration has focused on the paleozoic the aim of this special publication is to increase knowledge of the mesozoic overburden as a driver for further hydrocarbon exploration production and the development of new geothermal energy sources the succeeding chapters are introduced by tectonic framework overviews that give a context for the papers that follow the remaining articles are organized in approximate stratigraphic order from old to young and include a variety of examples from semi regional to localized field or sub basin studies an overview of the study area for all the following chapters is given in figure 1 it is recognized that the overprinting mesozoic systems have different naming conventions across the study area e g the central european basin system sensu littke et al 2008 maystrenko et al 2008 here we use the title southern permian basin area to emphasize the resource opportunities associated with a region that has at least in large part been associated with hydrocarbon exploration and very large gas fields in the permian rotliegend for our purposes this includes part of the polish trough the highs surrounding the basin e g the ringkobing fyn high and analogous elements of the danish and norwegian offshore in this introduction an overview of the geological history and resource base of the area is presented as a framework for the chapters that follow a description of further prospective resources is then offered oil and gas plus geothermal potential

holocene paleoenvironments in southeastern minnesota chasing the prairie forest ecotone this paper uses a multi proxy approach involving pollen plant macrofossils speleothem isotopes and alluvial history of streams to reconstruct the history of prairie expansion and contraction along the prairie forest border of southeastern minnesota usa early holocene forests were replaced by prairie along this border but eastward expansion of prairie stalled for 2000 yr when the prairie forest ecotone stabilized prairie invaded the area from the west 8000 9000 yr b p but mesic forest remained less than 100 km to the east until about 6000 yr b p changes in n 13 c values in speleothem calcite that reflect the rise of c4 grasses correlate well with the presence of c4 grass species identified in the plant macrofossil record periods of large floods correlate with speleothem evidence of dry summers increased cool season precipitation both resulting in less plant cover to absorb moisture and change to prairie vegetation fl 2002 elsevier science b v all rights reserved

late holocene evolution of the becva river floodplain outer western carpathians czech republic abstract to reconstruct the geomorphic imprint of the anthropogenic and natural environmental changes in the late holocene we studied the alluvial record of the becva river floodplain outer western carpathians czech republic coring geophysical sounding and lithological analysis of floodplain deposits supported by ams accelerator mass spectrometry dating enabled the establishment of the primary evolutionary stages of late holocene floodplain evolution during the late atlantic and early subboreal periods gravel aggradation and braided environments occurred in the studied floodplain the late subboreal and early subatlantic are characterised by overbank sedimentation and the middle subatlantic is marked by the recurrence of gravel aggradation a major incision phase took place during the mediaeval warm period the onset of overbank sedimentation in the 15th century correlated with ongoing deforestation of the lower parts of catchment and colonisation of the mountain ridges during the 16th 17th centuries further accelerated this process during the 20th century reforestation of mountains and river channel training resulted in a significant incision phase our data suggest that climate fluctuations were major driving factors for the morpho sedimentary evolution of the floodplain approximately up to the 12th century whereas in the latter evolution period anthropogenic activity superseded natural factors this transition occurred more than one millennium later than in other central and western european catchments

tethyan carbonate carbon isotope stratigraphy across the jurassic cretaceous boundary an indicator of decelerated global carbon cycling the carbon isotope record in four pelagic carbonate sections from the southern alps northern italy across the jurassic cretaceous boundary has been correlated to biostratigraphy and magnetostratigraphy the carbon isotope curve from bulk carbonates shows a decrease from kimmeridgian to early tithonian cm24 cm22 values of 13c 2 07 0 14 to late tithonian and berriasian cm18 cm14 values of 13c 1 26 0 16 the change in the carbon isotope record coincides with changes in tethyan calcite and silica accumulation rates with a drop in the calcite compensation depth in the atlantic and tethys oceans and with changes in organic carbon burial along the eurasian margin of the tethys reduced surface water productivity due to diminished transfer rates of biolimiting elements into the atlantic and tethys oceans can explain these observations the decreased transfer rates of elements such as silica or phosphorus from continents into the oceans resulted from drier climatic conditions and decreased water runoff on continents bordering the tethys and atlantic oceans the proposed changes in tithonian berriasian ocean chemistry and paleoclimate suggest that variations in the global carbon cycle were coupled with changes in the global hydrological cycle and in associated material cycles

calcareous nannofossils from late jurassic sediments of the volga basin russian platform evidence for productivity controlled black shale deposition the jurassic cretaceous boundary interval in the northern hemisphere is characterized by the widespread occurrence of black shales about 60 of all petroleum source rocks comprise sediments of late jurassic and early cretaceous age with the origin of such black shales still under discussion in order to better understand the factors that controlled black shale sedimentation 78 samples were analyzed for calcareous nannofossils from two sections gorodische kashpir of the volga basin ne russia calcareous nannofossils are ideal proxies for deciphering nutrient temperature and salinity fluctuations additionally 58 samples from both sections were also analyzed for clay mineralogy 13corg toc and caco3 composition both sections contain calcareous claystones and intercalated organic rich shales overlain by phosphorite beds the presence of the calcareous nannofossil species stephanolithion atmetros throughout both successions allows a biostratigraphic assignment to the s atmetros nannofossil biozone nj 17 which corresponds to the dorsoplanites panderi ammonite biozone of the middle volgian the marlstones of the kashpir section yield a well preserved rich and diverse nannoflora whereas all black shale beds are essentially barren of calcareous nannofossils only the uppermost black shale layers yield an impoverished assemblage of low diversity and abundance geochemical data suggest an early diagenetic nannofossil dissolution in the black shales of the kashpir section this is supported by the occurrence of coccoliths in black shale horizons of the gorodische section the assemblages in both sections are dominated by coccoliths of the watznaueriaceae group watznaueria barnesae watznaueria fossacincta watznaueria britannica watznaueria communis biscutum constans and zeugrhabdotus erectus in kashpir rare specimens of crucibiscutum salebrosum occur in the higher part of the section these taxa indicate boreal affinities b constans and z erectus are considered to be taxa indicative of a higher productive environment while c salebrosum is a cool water species from base to top of the kashpir section consecutive mass occurrences of different taxa groups were observed w barnesae w fossacincta acme w britannica w communis acme z erectus acme b constans acme including sparse occurrences of c salebrosum

an isotopic appraisal of the late jurassic greenhouse phase in the russian platform abstract oxygen and carbon isotope ratios have been determined from late jurassic callovian volgian belemnites from three locations on the russian platform gorodischi khanskaya gora and marievka all samples were examined by means of trace element geochemistry and petrography in order screen for diagenetic alteration oxygen and carbon isotopes from well preserved belemnites range from 2 24 to 0 09 and 0 57 to 1 77 respectively oxygen isotopes if interpreted in terms of temperature reveal a rise of temperatures during the oxfordian early kimmeridgian and indicate a prolonged episode of warmth during the kimmeridgian volgian the isotope data only equivocally reflect a number of significant changes in boreal tethyan ammonite assemblages a positive carbon isotope excursion is observed within the volgian but not seen within composite carbon isotope stratigraphies of the western tethys hence the jurassic may have been characterised by regional 13 c excursions related to non simultaneous organic matter deposition resulting from localised ponding semi restricted ocean circulation and a lack of tidal mixing

tectonostratigraphy of a rift basin affected by salt tectonics synrift middle jurassic lower cretaceous dutch central graben terschelling basin and neighbouring platforms dutch offshore the middle jurassic lower cretaceous in the eastern dutch offshore provides excellent examples of sand rich sediments that locally accumulated in the vicinity of rift basin margins affected by salt tectonics these types of deposits are often geographically restricted and difficult to identify but can be valuable targets for hydrocarbon exploration the distribution thickness and preservation potential of fluvio lacustrine shallow and deep marine sediments is discussed to provide new insights into the regional and local tectonostratigraphy of the dutch central graben the terschelling basin and their neighbouring platforms new sedimentological geochemical biostratigraphic stratigraphic and structural information have been analysed and integrated into a new tectonostratigraphic model for the callovian lower graben formation oxfordian middle and upper graben formations early middle volgian terschelling sandstone and noordvaarder members and the late volgian early ryazanian scruff greensand formation it is demonstrated that salt withdrawal at the basin axis was the primary control on the generation of high accommodation during the callovian early kimmeridgian incised valleys developed on the platforms providing lateral sediment input during the late kimmeridgian ryazanian salt migration shifted laterally towards the basin margins providing accommodation adjacent to active salt bodies and deposition of overthickened sandy strata

sensitivity of west and central european river systems to environmental changes during the holocene a review abstract sediment deposition in floodplains is an essential part of the sediment dynamics of a catchment these sediment dynamics can vary largely on a holocene time scale under the influence of driving forces such as land use and climatic variations in this paper we review the holocene floodplain sediment deposition history of rivers in west and central europe with special attention to the influence of climate and land use variability during the early holocene preboreal to atlantic period most floodplains were rather stable with limited floodplain aggradation after this initial phase of relative stability sedimentation rates increase during the middle and late holocene with often the most important deposition phase during the last 1000 to 2000 a the start of the increase in sedimentation varies spatially with an earlier start in the west france germany then in the east poland belarus ukraine while there are also local differences between regions which are settled early e g loess regions compared to later settled regions the sedimentation history of most floodplains can be linked to the local land use history while influence of climatic variations on floodplain aggradation is often reported to be of minor importance processes related to bedload are often reported to be more influenced by climatic events relationships between the driving forces and the sediment history are mainly based on synchronicity and there is seldom proof for a direct causal relationship future research should focus on a system based approach integrating the floodplain deposition in the entire sediment dynamics which includes also erosion colluvial deposition and export main research questions that need further attention include integration of system based concepts like landscape connectivity and buffering effects and also the assessment of the individual contribution of land use changes and climatologic variations on the sediment dynamics detailed sediment budget studies combined with modeling studies can make an important contribution to the understanding of floodplain sediment dynamics

responses of the upriver valley sediment to holocene environmental changes in the paju area of korea abstract multidisciplinary paleoproxy data from five sedimentary cores uj 03 06 07 10 and 12 recovered from the broad flat upriver valley in the paju area of korea are presented twelve ams radiocarbon dates from cores uj 03 and 12 provided a high resolution holocene record for the sedimentary sequence ranging from about 8000 ybp to the present from 6400 to 4400 14 c ybp 7100 5000 cal ybp the sediments were dominantly poorly sorted medium to coarse sands containing angular to subangular pebbles suggesting that the materials were locally derived the increased abundance of coarse grained sediment was attributed to intensified rainfall during the mid holocene despite the dense regional vegetational cover this period probably corresponded to the holocene climate optimum in the korean peninsula total organic carbon toc values showed a marked increase from 4400 to 2100 14 c ybp 5000 2200 cal ybp which coincided with an observed decrease in particle size i e a decrease in sand content these changes indicated the onset of paludification on the silty or sandy valley bottom contemporaneously relative abundances of pinus and herbaceous pollen increased and the east asian summer monsoon became weakened several intermittent depositional layers were observed ranging from 2100 14 c ybp 2200 cal ybp to the present which contained a high concentration of rootlets sand or clay particles these types of recurring sedimentation events are attributable to climatic shifts and or human impacts such as timber harvest and land clearing the upriver valley catchment was probably sensitive to flash floods due to poorly vegetated slopes accelerating rates of erosion as a consequence of land use change this research indicates that the response of a valley system such as that in paju to climate or human induced environmental changes can vary greatly on local and regional scales

influence of oceanic anoxic events on the evolution of mid cretaceous radiolaria in the north atlantic and western tethys abstract mid cretaceous aptian turonian extinction radiation events of radiolaria from the north atlantic and western tethys are summarized in relation to oceanic anoxic events oae from investigations of radiolarian faunas black shales and stable carbon isotopes extinction and radiation events of radiolaria can be observed from the late early aptian the earliest albian the latest albian and the cenomanian turonian boundary these events correlate well with organic carbon rich sediments that contain type ii kerogen and show positive 13c excursions they correspond to the oceanic anoxic events oae in the early aptian oae 1a selli level early albian oae 1b late albian oae 1d and latest cenomanian oae 2 bonarelli level detailed investigations of the two most significant events the selli and the bonarelli level in the umbria marche basin of central italy show that extinctions coincide with the first occurrence of marine black shales type ii kerogen and the most prominent rise of 13corg values stepwise extinctions and continuous radiations precede and follow the events similar patterns are evident for the oae 1b and 1d black shales dominated by terrestrial organic matter type iii kerogen e g oae 1c are not characterized by isotopic excursions or by radiolarian extinction radiation events contemporaneous drowning events documented from carbonate platforms around the investigated basins provide a link to a model where flooding of lowlands and leaching of nutrients during a relative rise of sea level lead to an increased productivity and an expansion of the oxygen minimum zone omz because of the loss of deep habitats deeper dwelling forms become extinct shallower dwelling radiolarians survive a narrowing of the omz during highstands and relative sea level falls together with a coupled decrease of the nutrient supply leads to the development of new niches and therefore to radiation

medieval accumulation in the upper dniester river valley the role of human impact and climate change in the carpathian foreland research in the valleys of upper dniester strvja and stryj rivers in the eastern carpathian foreland documents the occurrence of 3 4 holocene floodplain terraces and several alluvial fills dating back to the late vistulian and the atlantic as well as the periods 3500 3000 bp 1850 1250 cal bc 2200 1700 bp 360 cal bc 390 cal ad 5th 6th 10th 12th and 14th 16th centuries ad flood phases distinguished in the upper dniester drainage basin correlate well with previously established phases of enhanced fluvial activity in the valleys of upper vistula the wisloka and the san in the western carpathian foreland an episode of tree fall during the 5th 6th century floods is the most conspicuous and is linked to the beginning of a wet climate phase 1500 1350 cal bp subsequent phases of greater fluvial activity from the 10th to the 12th and from the 14th to the 16th centuries record increasing human activity as well as correlation with wet and cool climate phases the first half of the 11th century and the beginning of the little ice age fluvial accumulation processes along the longitudinal profile of the upper dniester valley were affected not only by human activity and more humid climate phases but also by diverse neotectonic movements

stepwise basin evolution of the middle jurassic early cretaceous rift phase in the central graben area of denmark germany and the netherlands this paper presents the results of a cross border study of the middle jurassic early cretaceous rift phase in the danish german dutch central graben area based on long distance correlations of palynologically interpreted wells a stepwise basin evolution pattern was determined four phases are defined and described as tectonostratigraphic mega sequences tms the tms are governed by changes in the tectonic regime tms 1 reflects the onset of rifting triggered by regional east west extension rift climax was reached during tms 1 reflected by thick mudstone accumulations tms 2 reflects a change in the tectonic regime from east west to ne swextension nw se trending normal faults became active during this phase switching the depocentres from the graben axis into adjacent basins tms 3 displays divergent basin development in the dutch central graben area it is characterized by a basal unconformity and widespread sandstone deposition indicating continued salt and fault activity organic rich mudstone deposition prevails in the danish and german central graben area indicating sediment starvation and water mass stratification with tms 4 the rift phase ended reflected by regionally uniform mudstone deposition the basin evolution model presented here coherently places the lithostratigraphic units occurring in a stratigraphic framework and provides a valuable basis for hydrocarbon exploration activities in the region

a high resolution late holocene landscape ecological history inferred from an intramontane basin in the western taurus mountains turkey abstract late holocene vegetation and geomorphological history is reconstructed from a 800 cm long high resolution palynological and sedimentological record sampled from bereket a 6 3 km 2 semi arid to sub humid intramontane basin in the western taurus mountains southwest turkey the well dated bereket record provides from cal 360 bc to cal ad 400 a unique record of biennial to decadal landscape changes caused primarily by intensive human impacts against a background of global climate variations during this period land clearance with multiple fire episodes intensive agricultural practices and grazing pressure profoundly altered the pre existing warm mixed forest increasing moisture availability since cal 280 bc has acted as a trigger to crop cultivation and mountain adapted arboriculture starting with juglans regia during the beysehir occupation phase pollen from olive groves have been recorded above 1400 m a s l only at cal 23 bc and have disappeared definitively at cal ad 294 during this phase the sediment accumulation rate was extremely high reflecting landscape instability from cal ad 450 to recent times the area has mainly recorded pasture and minor cultivation activities reflected in stable soils and thin colluvial depths

depositional conditions and organic matter preservation pathways in an epicontinental environment the upper jurassic kashpir oil shales volga basin russia abstract the middle volgian kashpir oil shales formation located on the russian platform is a lateral equivalent of the north sea and west siberian petroleum source rocks in the volga basin this formation is 6 m thick and shows alternations of marls and black shales the organic carbon content is often higher than 1 although bioturbation and benthos are abundant even in the black shales in the marls highly degraded organic matter om dominates while aliphatic sulphur rich om is dominant in the black shales the combination of sedimentological and geochemical studies allowed to determine that the redox conditions of the sediment regularly fluctuated from oxic to anoxic under relatively productive waters while climatic conditions were increasingly arid it is proposed that om deposition occurred in relation to the increasing aridity through the combination of recurrent disruption of salinity stratification and aeolian supply of iron which both promoted phytoplankton productivity

carbon and oxygen isotope composition of oxfordian early kimmeridgian belemnite rostra palaeoenvironmental implications for late jurassic seas abstract stable isotope analyses have been undertaken on oxfordian early kimmeridgian belemnite rostra derived from three palaeogeographic provinces of europe 1 the boreal subboreal province isle of skye in scotland 2 the submediterranean province central poland and southern germany and 3 the mediterranean province pieniny klippen belt in the western carpathians the samples have been screened for possible diagenetic alteration by using cathodoluminescence and trace element analyses and have been found to be largely well preserved calculated palaeotemperatures 10 15 c and analyses of belemnite habitats suggest that the boreal subboreal belemnites were living in a relatively shallow sea not deeper than 100 150 m while the other belemnites possibly inhabited deeper neritic environments despite the influence of a vital effect the 13c values of belemnite rostra are interpreted to reflect primary variations in the oceanic carbon isotope signal the fairly uniform submediterranean 13c values indicate a similar isotope composition of dissolved inorganic carbon dic in the area of sedimentation of sponge megafacies in the deep tethyan shelves the slightly lowered 13c values of some mediterranean belemnites might occur due to upwelling providing 12c enriched bottom waters onto the area of the czorsztyn ridge in the oxfordian the discernibly more positive 1 2 5 13c values of boreal subboreal belemnites are related to a high biologic productivity and a high organic matter burial in the partly isolated boreal sea the stated differentiation in carbonate 13c values distinctly exceeds present day differences in isotope composition of seawater dic

stratigraphy of alluvia and phases of the holocene floods in the valleys of the eastern carpathians foreland abstract the studied sequences of alluvia in the catchments of the upper dniester seret and prut rivers record the occurrence of the late vistulian terrace and 3 4 levels of the holocene terraces as well as several series of the alluvial fills and paleochannel systems dated at 11 800 10 700 bp 13 470 85 12 600 40 cal bp 10 500 9800 bp 12 740 60 11 220 15 cal bp 8700 7500 bp 9625 65 8350 20 cal bp 5500 5100 bp 6295 10 5845 75 cal bp 3100 2700 bp 3310 30 2800 40 cal bp 2100 1700 bp 2060 55 1590 30 cal bp middle ages little ice age and the last 150 200 years the distinguished alluvial fills and flood phases in the valleys of the eastern carpathian foreland record similarly to the valleys of the upper vistula river catchment in the western carpathian foreland rhythmic changes in the precipitation climate humidity and hydrological regime as well as an increasing human impact deforestation and cultivation during the last two thousand years these changes are recorded in the sequences of floodplains by an increase in number and deposition rate of the overbank sand silt series simultaneously these changes are visible in pollen diagrams recording deforestation phases in floodplains neolithic period roman period and middle ages

effect of structure and texture on infiltration flow pattern during flood irrigation understanding the flow pattern of water and solute in subsurface soils is critically important in the fields of agricultural and environmental sciences dye tracer tests using a flood irrigation of brilliant blue fcf solution 5 g l 1 and excavation method was performed to investigate the effect of texture and structure on the infiltration pattern at three different field soils developed from granite gr gneiss gn and limestone ls the gr soil showed a homogeneous matrix flow in the surface soil with weak medium granular structure and a macropore flow along pegmatitic vein and plant root in c horizon the surface horizon a1 of gn soil with moderate medium granular structure and many fine roots had matrix flow the fingering occurred at the interfaces of sandy loam a horizon and loamy sand c horizon in gr soil and loam a1 horizon and sandy loam a2 horizon in gn soil the ls soil with strong coarse prismatic structure and the finest texture showed a macropore flow along cracks and had the deepest penetration of the dye tracer the macropore crack and vein layer interface and plant root induced the preferential flow in the studied soils

sequence stratigraphy of upper jurassic reservoir sandstones in the northern part of the danish central trough north sea abstract the jurassic succession of the northern part of the danish central trough is subdivided into six depositional sequences based on a multi disciplinary study including sedimentology biostratigraphy seismic interpretation structural interpretation log correlation geochemistry and palynofacies analysis three of these sequences include significant sandstone deposits that represent potential reservoirs the lowermost sequence 1 contains upper kimmeridgian backbarrier and shoreface sandstones of the basal sandstone unit and the heno formation deposited within a transgressive and a highstand systems tract respectively sequence 2 includes upper kimmeridgian middle shoreface sandstones of the heno formation deposited within a transgressive systems tract within sequence 6 middle upper volgian distal turbidite sandstones have been recognized these are interpreted as having been deposited within a lowstand and transgressive systems tract and may constitute a reservoir elsewhere in the basin the sequence stratigraphic boundaries of this study do not match those proposed by the exxon group in this rift setting sequence development was probably controlled predominately by tectonism eustasy was of subordinate importance

late pleistocene environments of the central ukraine the vyazivok loess sequence from the dnieper plain ukraine documents regional environmental changes during the late pleistocene and holocene pedological and palynological analyses and low field magnetic susceptibility document changes from dense temperate forest during the last interglacial maximum to open harsh loess steppe during the latest pleistocene the vyazivok section overlies hillwash derived from a lower pleistocene terrace and consists of two stratified soil complexes kaydaky and pryluky marine isotope stage mis 5 equivalent separated by a layer of eolian dust tyasmyn silt the lower soils in both complexes formed within forest these soils are overlain by the uday mis4 and bug mis2 loess units which are separated by boreal soils of the vytachiv mis3 complex the coldest conditions within the record occurred in the youngest loess holocene soils cap the bug loess the vyazivok section shows remarkable similarities with other classical loess sequences in western europe the czech republic and austria the kaydaky pryluky and vytachiv deposits correlate with the pkiii pkii and pki soil complexes respectively of the czech republic the tyasmyn and prylyky silt layers correspond to marker horizons from central europe c 2001 university of washington

low productivity and slow deep water circulation in mid cretaceous oceans paleofertility estimates are derived from organic carbon accumulation rates determined in nonbioturbated mid cretaceous deep sea deposits using organic carbon preservation factors observed in laminated sediments from anoxic holocene environments the estimated mid cretaceous primary production rates are as much as an order of magnitude lower than those measured in today s oceans an evaluation of dissolved oxygen budgets using a simple oceanic circulation model indicates very low deep water renewal rates in mid cretaceous oceans 28 references 2 tables 4 figures

preservation of delta 18 o and delta 13 c in belemnite rostra from the jurassic early cretaceous successions stratigraphic collection of 263 belemnite rostra guards from jurassic to lower cretaceous sediments in the moscow area of russia northern germany england new zealand and morocco were analyzed to determine temporal variations in their delta 18 o and delta 13 c as a proxy for isotopic composition of surface seawater internal structures of the rostra were studied using cathodoluminescence and sem techniques their trace element fe mn mg and sr and the stable carbon and oxygen isotope compositions the average stratigraphic resolution is about 1 ma these samples represent a broad range of paleolatitudes and paleoceanographic settings ranging from 42 degrees n to 82 degrees s covering boreal to subtropical brackish to open marine shelf paleoenvironments the rostra originally contained domains enriched in organic matter that were later replaced by luminescent diagenetic calcite thereby generating an impression of seasonal growth rings diagenetic calcite accounts for up to 6 8 percent of the rostrum the trace element content of the rostra range from 227 to 3935 ppm for mg 379 to 1514 ppm for sr and up to 305 and 3662 ppm for mn and fe respectively however selective drilling of only primary calcitic domains resulted in 90 percent of all analyzed samples to fall within the range of trace element values typical for modern low mg calcite shells the chemical and textural data suggest that the primary calcite of the rostra is well preserved as is its isotopic signature the delta 13 c and delta 18 o measurements define oscillating temporal bands of about 3 to 4 per mil width around more or less modern marine values of 2 and 1 per mil respectively oxygen isotopes in the well preserved rostra most likely reflect temperature variations within a approximately 14 or 8 degrees c range the observed 3 to 4 per mil spread of values between contemporaneous specimens which is comparable to the scatter of data reported for modern low mg calcitic brachiopod shells probably reflects the diversity of local ecosystems although some of the spread may be due to real short term temporal variations within single biozones the delta 13 c values of the rostra define a band similar to that of the oxygen isotopes and the temporal oscillations of both isotope curves are commonly in phase the above dataset complemented by the results of jones jenkyns and hesselbo 1994 and jones and others 1994 yields a composite delta 18 o and delta 13 c variations in belemnite guards for the entire jurassic early cretaceous interval for delta 18 o the oscillating band indicates that the most negative values occur at times of independently postulated global and or regional anoxic events such as those in the toarcian and kimmeridgian as well as the aptian these oaes appear to be characterized by up to 10 degrees c higher seawater temperatures than the intervening background times the delta 13 c record shows 13 c depletion for the kimmeridgian event but enrichment for the other two suggesting that the delta 13 c temporal oscillations and oaes are not simply a reflection of surficial productivity due to operation of the biological pump but rather of changing oceanic circulation patterns due to variations in latitudinal surface temperature gradients

stable isotope records from sepia officinalis a key to understanding the ecology of belemnites abstract the stable isotope ratios 1 8 o 1 3 c of the aragonite of cuttlebones of sepia officinalis were measured on a high resolution scale where every septum was measured our studies aim at understanding whether variations of the isotope signature are controlled by ontogenetic and or ecological factors five specimens were reared from eggs under known water temperatures a sixth specimen was caught in the german part of the north sea the data suggest that the oxygen isotope composition is in isotopic equilibrium with the surrounding seawater and reflects ambient temperature migration and seasonal temperature changes are visible in the acquired data set the carbon isotope signature shows signs of biofractionation and no direct correlation to the oxygen signature as far as ontogeny and ecology are concerned

late quaternary landscape evolution of the upper dnister valley western ukraine abstract the broad and flat valley of the upper dnister in western ukraine is characterized by a complex setting of ecotopes and a relatively natural state of floodplain dynamics excellent geo archives extended peat bogs and postglacial river terraces document late quaternary landscape evolution with special regard to changes in fluvial morphodynamics vegetation and human impact the terraces were studied by detailed geomorphological mapping as well as sedimentological and pedological analyses in connection with information from historical maps vegetation history was studied by palynological methods in combination with radiocarbon dating two late pleistocene nt1 and nt2 and seven holocene h1 h7 river terraces are evident the ecological transformation during the period of climatic warming at the end of the last glacial maximum lgm caused the most significant change in runoff and sediment load as well as in the vegetation cover the dnister changed from a braided to a meandering river system it was soon after the spreading of postglacial forests with an increasing dominance of broadleaved trees that the pollen diagrams reflected the first signs of anthropogene influence intensified agricultural land use since the iron age is mirrored in the increasing amount of herbaceous pollen as well as the rise of fluvial sediment redeposition modern hydraulic engineering on the dnister has caused visible transformations because of these impacts the stability of the upper dnister ecosystem has decreased significantly and is now highly sensitive to environmental change

late jurassic climate and its impact on carbon cycling abstract the climate of the late jurassic has been characterized by high atmospheric co2 levels and by a monsoonal rainfall pattern in this study we traced the evolution of the global carbon cycle through the late jurassic with the help of carbonate carbon isotope stratigraphy the oxfordian tithonian 13c curve is marked by one major positive carbon isotope excursion with an amplitude 13 c 1 0 middle to late oxfordian and a second minor positive excursion with an amplitude 13 c late kimmeridgian the early kimmeridgian and early tithonian 13c values fluctuate around 13 c 2 0 3 and contrast with the less positive 13c values of early oxfordian and late tithonian age 13 c 1 0 5 a comparison of the late jurassic carbonate carbon isotope curve with the occurrence of organic rich sediments suggests that not only fluctuations in organic carbon burial but also in carbonate carbon burial had an impact on the c isotope record the oxfordian c isotope excursion appears to correspond to a time of overall increased organic carbon burial triggered by increased nutrient transfer from continents to oceans during a time of rising global sea level however episodes of enhanced organic carbon burial during the kimmeridgian and early tithonian are not reflected by prominent spikes in the c isotope record favourable conditions for carbonate platform growth at a time of high global sealevel may have resulted in the stabilisation of the c org c carb burial ratio and hence maintained the 13c record at steady but relatively positive values the middle and late tithonian c isotope values drop below 13 c 1 5 a similar shift to less positive c isotope values was recognized in other c isotope records from the tethys and atlantic oceans and reflects a decrease in the c org c carb burial ratio possibly related to a reorganisation of the global climate system globally widespread marine black shale mature quartzose sandstone assemblages suggest that the relative efficiency of the late jurassic carbon pumps was controlled by weathering erosion and runoff causing widespread marine eutrophication eutrophication favoured the organic carbon pump but it diminished the carbonate platform growth potential the monsoonal rainfall distribution pattern may explain why late jurassic carbonate platforms experienced less severe growth crises than early cretaceous carbonate platforms

strontium isotope stratigraphy and oxygen and carbon isotope variation during the middle jurassic early cretaceous of the falkland plateau south atlantic abstract 87sr 86sr data of belemnites are presented from a middle jurassic early cretaceous succession from the falkland plateau deep sea drilling project sites 511 and 330 that was deposited in a periodically anoxic semi enclosed shallow water basin diagenetically screened strontium isotope values of 0 706789 rise to 0 707044 before increasing sharply to 0 707428 in the uppermost part of the sampled succession comparison with published strontium calibration curves suggests that the oldest samples were callovian to oxfordian in age whilst the remainder of the jurassic part of the succession consisted of kimmeridgian and early tithonian age sediments the nannofossil dinoflagellate and molluscan assemblages provide comparable age determinations the strontium isotope analysis of the youngest belemnites points to a hauterivian barremian age whilst age interpretations based upon the fauna provide a wide age range from the barremian to early albian strontium isotope stratigraphy of this succession hence offers increased age resolution providing data regarding the timing of episodes of bottom water anoxia which have been recorded throughout the south atlantic basin well preserved belemnite specimens display an oxygen isotope range between 0 08 and 2 22 pdb peedee belemnite international standard and a carbon isotope range from 2 35 to 1 33 pdb 13c values become increasingly negative through the late jurassic early cretaceous and in concert with the 87sr 86sr data reveal a trend that could be accounted for by increasing levels of weathering and erosion the oxygen isotope data if interpreted in terms of palaeotemperature are consistent with warm palaeotemperatures in the kimmeridgian and slightly cooler temperatures for the tithonian and early cretaceous parts of the succession the proposed relative kimmeridgian warmth based upon strontium isotope age assignments is thus in good agreement with other published palaeotemperature records

floodplain environmental change during the younger dryas and holocene in northwest europe insights from the lower kennet valley south central england abstract many lowland rivers across northwest europe exhibit broadly similar behavioural responses to glacial interglacial transitions and landscape development difficulties exist in assessing these largely because the evidence from many rivers remains limited and fragmentary here we address this issue in the context of the river kennet a tributary of the thames since c 13 000 cal bp some similarities with other rivers are present suggesting that regional climatic shifts are important controls the kennet differs from the regional pattern in a number of ways the rate of response to sudden climatic change particularly at the start of the holocene and also mid holocene forest clearance appears very high this may reflect abrupt shifts between two catchment scale hydrological states arising from contemporary climates land use change and geology stadial hydrology is dominated by nival regimes with limited winter infiltration and high spring and summer runoff under an interglacial climate infiltration is more significant the probable absence of permafrost in the catchment means that a lag between the two states due to its gradual decay is unlikely palaeoecology supported by radiocarbon dates suggests that at the very start of the holocene a dramatic episode of fine sediment deposition across most of the valley floor occurred lasting 500 1000 years a phase of peat accumulation followed as mineral sediment supply declined a further shift led to tufa deposition initially in small pools then across the whole floodplain area with the river flowing through channels cut in tufa and experiencing repeated avulsion major floods leaving large gravel bars that still form positive relief features on the floodplain followed mid holocene floodplain stability prehistoric deforestation is likely to be the cause of this flooding inducing a major environmental shift with significantly increased surface runoff since the bronze age predominantly fine sediments were deposited along the valley with apparently stable channels and vertical floodplain accretion associated with soil erosion and less catastrophic flooding the kennet demonstrates that while a general pattern of river behaviour over time within a region may be identifiable individual rivers are likely to diverge from this consequently it is essential to understand catchment controls particularly the relative significance of surface and subsurface hydrology

relative sea level change and carbon isotopes data from the upper jurassic oxfordian of central and southern europe studies on cretaceous pelagic limestones have shown a close correspondence between putative sea level curves and the carbon isotope profile suggesting a possible relationship between the two phenomena such a relationship could relate to shelf sea area governing the global burial rate of organic carbon which in turn controls the 13c 12c ratio of dissolved inorganic carbon in the oceanic reservoir in order to see whether or not this relationship might be of more general applicability the major mid oxfordian jurassic transgression is documented to zonal level and appropriate carbon isotope data are presented although the applicability of ammonite zonation to the mid oxfordian is problematic on a regional scale a clear 13c excursion is present in the trunsversariurn zone which is coincident with regional overstep and or evidence of shoreline retreat and or evidence of bathymetric deepening in europe and elsewhere the use of the carbon isotope curve as a proxy for shelf sea area or relative sea level is worthy of further exploration

detailed oxygen and carbon isotope stratigraphy of the oxfordian in central poland a collection of 73 belemnites and brachiopods from detailed stratigraphically documented sections in the polish jura chain of central poland representing almost the whole oxfordian stage was studied for oxygen and carbon isotopes the 18o and 13c v pdb values range from 3 6 to 0 5 and from 1 6 to 2 for belemnite rostra and from 2 5 to 0 4 and from 1 6 to 4 3 for brachiopod shells respectively the 13c temporal trends of belemnite rostra and brachiopod shells show a constant isotopic difference ca 2 5 3 which is interpreted as a vital effect of belemnites or as a result of different life environments 18o values are similar in both groups of fossils the 18o values in the lower and middle oxfordian oscillate around 0 and decrease in the upper oxfordian this decrease results mainly from diagenetic overprint as proved by the cathodoluminescence studies the lower and middle oxfordian 18o derived temperatures were constant in consequence of significant ocean depth for this reason there are no established links with distribution of ammonite faunas the 13c temporal trend displays a gentle slope through the oxfordian and reaches maximum values at the turn of the plicatilis transversarium zones of the middle oxfordian which is commonly considered as a global event it can be related to the sea level highstand and growth crisis of carbonate platforms the decrease in 13c values starting in the upper middle oxfordian is interpreted to be due to the acceleration of carbonate sedimentation rate during this time period

late jurassic kimmeridgian tithonian stable isotopes δ18o δ13c and mg ca ratios new palaeoclimate data from helmsdale northeast scotland abstract the data presented here provide the first detailed stable isotope 18 o 13 c and geochemical mg ca investigation of kimmeridgian tithonian belemnites from the helmsdale coast scotland uk oxygen and carbon stable isotope values from well preserved specimens range from 2 8 to 0 3 and from 2 3 to 2 8 respectively the oxygen isotope data are consistent with palaeotemperatures of up to 24 c in the early kimmeridgian cymodoce zone and down to 11 c in the mid tithonian rotunda fittoni zones these estimates are strongly supported by the mg ca data which also indicate a cooling episode and very similar palaeotemperatures 11 22 c at this time the cooling event is associated with an approximately 5 decline in 13 c ratios this shift towards more negative 13 c values has also been recorded in the tethys and on the russian platform confirming that this event was of global origin such globally synchronous records can provide a valuable tool for stratigraphic correlation the helmsdale 13 c data are therefore combined here with other published belemnite isotope data from the jurassic of scotland from the callovian kimmeridgian of the isle of skye and the toarcian aalenian of raasay the resultant belemnite 13 c curve provides a detailed record of the toarcian tithonian british boreal realm that can be compared with coeval records to investigate regional differences in jurassic carbon isotope stratigraphy

evidence for late jurassic release of methane from gas hydrate four late jurassic carbonate successions deposited in the tethys atlantic ocean record a negative carbon isotope excursion of at least 2 the excursion is present in both organic and carbonate carbon records and is comparable in magnitude and duration to isotopic changes during the late paleocene thermal maximum our results indicate that during the late jurassic long considered a warm greenhouse time additional greenhouse gas was input to the atmosphere by a sudden release of methane from buried gas hydrate a potential triggering mechanism may have been the opening of an oceanic gateway through the early atlantic between the ancient tethys and pacific oceans

late holocene fire impact and post fire regeneration from the bereket basin taurus mountains southwest turkey abstract the 800 cm long sequence from the bereket provides the first detailed fire history in the western taurus mountains for the last three millennia the main disturbances occurred during the beysehir occupation phase bo phase a period of intensive polyculture and dated at bereket from ca 2230 to 1550 cal yr bp four phases of local and extra local fire periods have been recorded at 2320 2240 1985 1970 1865 1820 cal yr bp and post ad 1950 the fire history established for the bo phase is complex with fire periods alternating with periods without local fires as is the case for the late bo phase from 1820 until 1550 cal yr bp it is suggested that the past agricultural practices including fires cause a higher soil erodibility than agricultural practices without fires a climatic shift towards aridity during roman times may have triggered the observed change in fire regime but local processes mainly human disturbances appear to be the proximal cause of all recorded changes in the bereket surroundings fires led to a simplification of the vegetation structure favouring soil erosion pastures and intensive cultivation