spatial and temporal variability of 234u 238u activity ratios in the shu river central asia this study presents the temporal and spatial variability of 234u 238u activity ratios in the shu river and provides interpretation to explain the downstream changes of uranium and the 234u 238u activity ratios in the study area the positive linear correlation r 2 0 98 p 0 001 between uranium concentration and specific electrical conductance is consistent with rock weathering and leaching as the major contributor of dissolved uranium in the studied area of the river the 234u 238u activity ratio ranged between 1 6 in the upper reaches of the river to 1 15 furthest downstream activity ratios at specific sampling points do not show significant seasonal variability

physical and chemical weathering rates and co2 consumption in a tropical lateritic environment the upper niger basin the chemical composition of niger river water measured bimonthly at bamako mali during the period 1990 1992 provides an estimate of present weathering rates in the upper niger basin the dominant weathering process is kaolinite formation monosiallitization however seasonal variations promote gibbsite formation in the rainy season september and smectite development in the dry season may the results show that lateritic profiles continue to develop even during very dry episodes the rate of profile development calculated as the difference between the chemical weathering rate at the base of the soil profile and mechanical erosion rate at the soil surface is about 1 3 to 3 7 m myr a comparison between 43 river basins of the world shows that for similar runoff the co2 flux consumed by silicate weathering is about two times lower in lateritic areas than in nonlateritic zones

weathering rates as a function of flow through an alpine soil the effect of flow on release rates of solutes from soil in a 39 m2 alpine catchment in the colorado rockies was measured during the summers of 1990 1994 flow rates through the soil were varied by augmenting natural rainfall with deionized irrigation water daily water inputs averaged between 96 and 2161 day during the five field seasons and mean discharge inputs minus evapotranspiration varied from 35 to 175 1 day 1 volume weighted mean concentrations of base cations and silica decreased only moderately in response to the increased water inputs input fluxes of solutes in precipitation were similar in each of the study seasons but output fluxes of base cations and silica in surface outflow increased substantially in conjunction with the average water input rate for the season weathering rates calculated from the chemical fluxes increased substantially in response to increases in water input rates the increases appear to be largely attributable to enhanced transport of solutes from the soil matrix under high flow conditions at high flow physical flushing of micropores presumably occurs to a greater extent than during low flow periods because of greater soil wetness and higher hydrologic head increased flushing would also cause an increased rate of diffusion of solutes from microcracks in mineral surfaces and constricted pore spaces in response to an increased concentration gradient between those regions and adjacent areas in the soil matrix another consequence of the increased flushing that occurs during periods of high flow is that concentrations throughout the soil matrix tend to be lower which might increase chemical weathering rates of some silicate minerals such as microcline which are relatively close to saturation decreased si concentrations under high flow conditions appear to promote dissolution of amorphous aluminosilicates or desorption of si from mineral surfaces buffering si concentrations in the soil solutions thus both physical transport of solutes and subsequent chemical effects appear to be responsible for the positive relation observed between fluxes of weathering products and water input rates

mechanisms of sediment transport and deposition sediment sequences and accumulation during the holocene on the thermaikos plateau the continental slope and basin sporadhes basin northwestern aegean sea greece abstract detailed 3 5 khz seismic reflection profiling carried out on the thermaikos plateau the slope and the basin sporadhes basin northwestern aegean has shown that during the holocene the area received fine grained sediments discharged mainly by the rivers axios aliakmon and pinios a well developed oblique sigmoid progradation pattern has been observed on the seismic profiles taken across the deltaic holocene sequences of these rivers three seismic facies have been identified within the oblique sigmoid pattern 1 dark homogeneous facies that represent fine sand deposits along the delta front topsets 2 stratified facies that represent alternating muddier or sandier horizons foresets and 3 transparent facies in which the muddy sediments predominate bottomsets the base of the holocene reflector c has been found beneath the oblique sigmoid pattern the thin homogeneous and transparent seismic facies throughout the slope and the basin has been interpreted as the holocene muddy sediment sequence in the area bottom samples from the outer thermaikos plateau have shown that it is floored by relict terrigenous sand at depths of 90 110 m the sediment and clay mineral distribution and the presence of relict sand confirm that during the holocene period the fine grained sediment dispersion and deposition was effected by the water mass circulation the majority 80 90 of the sediments dispersed from the rivers during the holocene has been captured by the extensive shelf thermaikos plateau having deposited from the near bottom nepheloid layer minor amounts 10 20 of very fine grained material have escaped and deposited from suspension hemipelagic settling in the slope and basin of the studied area

chemical weathering rate denudation rate and atmospheric and soil co2 consumption of parana flood basalts in sao paulo state brazil abstract the chemical weathering rate and atmospheric soil co 2 consumption of parana flood basalts in the preto stream basin sao paulo state brazil were evaluated using major elements as natural tracers surface and rain water samples were collected in 2006 and analyses were performed to assess ph temperature dissolved oxygen do electrical conductivity ec and total dissolved solids tds including so 4 2 no 3 po 4 3 hco 3 cl sio 2 ca 2 mg 2 na and k fresh rocks and c horizon samples were also collected taking into account their geological context abundance and spatial distribution to analyze major elements and mineralogy the preto stream downstream from the city of ribeirao preto receives several elements compounds as a result of anthropogenic activities with only sulfate yielding negative flux values the negative flux of so 4 2 can be attributed to atmospheric loading that is mainly related to anthropogenic inputs after corrections were made for atmospheric inputs the riverine transport of dissolved material was found to be 30 t km 2 y 1 with the majority of the dissolved material transported during the summer wet months the chemical weathering rate and atmospheric soil co 2 consumption were 6 m ma and 0 4 10 6 mol km 2 y 1 respectively the chemical weathering rate falls within the lower range of parana flood basalt denudation rates between 135 and 35 ma previously inferred from chronological studies this comparison suggests that rates of basalt weathering in brazil s present day tropical climate differ by at most one order of magnitude from those prevalent at the time of hothouse earth the main weathering process is the monosiallitization of anorthoclase augite anorthite and microcline magnetite is not weathered and thus remains in the soil profile

determining weathering rates of soils in china abstract as an important parameter for critical load calculation and soil acidification simulation weathering rates of soils in china were studied using different methods of calculation the approaches used were the mass balance approach the soil mineralogical classification the total analysis correlation the profile model the magic model and a simulated leaching experiment since chemical weathering of secondary minerals usually plays a much more important role in neutralizing the long term acidification of soils in china than that of parent material soil mineralogy rather than parent rock material type which is regarded as the most suitable factor representing weathering rates in europe should be adopted as the basis for soil classification the weathering rate assigned to each soil should also be corrected when the effect of temperature is considered due to the variation in experimental conditions the weathering rates of soils from laboratory experiment may be difficult to compare with field determined rates and should be adjusted by ph and percolation rate the comparison of various methods in this study shows that the weathering rates of soils estimated by the profile model coincide well with those from other independent methods such as the dynamic modeling by magic and the modified leaching experiment the weathering rates were very low usually lower than 1 0 keq ha 1 year 1 for allites including latosol lateritic red earth red earth yellow earth and yellow brown earth in south china and silalsols consisting of dark brown forest soil black soil and podzolic soil in northeast china and very high for alpine soils desert soils and pedocals in west china the content of weatherable minerals in soil is the most important factor in determining the spatial distribution of weathering rate in china while the difference in temperature may be the reason why the weathering rate of soil in northeast china was lower than that in southeast china

sediment yield studies of headwater catchments in sussex s e england the transport of sediment from six small 0 2 to 17 6 km2 headwater catchments is described the catchments under investigation were located in relation to predominant lithological deposits within the cretaceous rock succession two of the areas were underlain by weald clay two by sandstone ashdown sand and tunbridge wells sand and two by chalk the climate of the region under investigation is temperate with an average annual precipitation 850 mm in excess of potential evapotranspiration 450 mm the transport of suspended material from within the catchments was examined by collecting samples of the water sediment mixture draining the areas using hand held depth integrating and permanently installed stage sampling systems the results of the regularly maintained sampling programme over a two year period are described attempts were made to both measure and compute bed load transport suspended sediment concentrations are compared between catchments and related to hydrological characteristics the nature of the material in transit is examined sediment rating curves are derived for each of the headwater catchments defining the relationship in the form y axb where y suspended sediment concentration mg 1 and x water discharge m3 s annual rating curves are used to derive annual suspended sediment loads by combination with water discharge data using a log incremental computerized approach multiple regression techniques have been used to examine annual loads in terms of hydrological and morphological characteristics of the headwater catchments based on the field information available a generalized model for the relationship between suspended sediment concentration and water discharge is described finally the derived annual loads from the headwater catchments are combined with both limited observations from the larger sussex rivers and data available for other catchment investigations in the british isles to produce a series of prediction equations for catchment yield under temperate climatic conditions

gas charged sediments in the aegean and ionian seas greece abstract during the last fifteen years marine seismic surveys in the aegean and ionian seas have revealed numerous acoustic anomalies i e acoustic turbid zones gas pockets gas plumes enhanced reflectors columnar disturbances wipe outs and meso to micro morphological features such as pockmarks domes mud volcanoes and elongated depressions these are attributed to the presence of gas in sediment interstices the gas charged sediments are found in pleistocene and present day fjord like environments pleistocene and present day deltaic environments lakes and open sea environments the gas found in the quaternary fjord like and deltaic depositional environments is assumed to be of biogenic origin the gas found in the pre quaternary open sea environments is associated with faulting and salt doming and may therefore be of thermogenic origin although the sediment grain size is favourable for the formation of pockmarks the lack of them is probably due to the high seismicity which characterises these regions

geochemical and sedimentological patterns in the thermaikos gulf north west aegean sea formed from a multisource of elements surface sediment samples from thermaikos gulf were analysed for organic carbon cd pb cr cu zn mn ni co and fe and were subjected to grain size analysis the results showed that pb cu and zn had the same source of pollution in the following order of importance the sewage outfall the industrial zone and the axios river the concentration of these metals increased with decreasing mean grain size suggesting their association with the fine fraction of the sediments the clays and the organic matter cadmium was more loosely correlated with the metals of the previous group being derived from the community activities and also from the weathering of land based ophiolitic rocks iron cr ni co and mn are of natural origin the weathering of mafic and ultramafic rocks being responsible for their enrichment this was more apparent in the case of ni which was more enriched in the coarser and better sorted sediments near the delta of the river aliakmon

modern sedimentation in the n w aegean sea abstract the area under investigation is located within 22 45 to 23 45 e and from 39 15 to 40 15 n sedimentological bathymetric and shallow geophysical data were collected from here during the 7 78 cruise of r r s shackleton twenty seven sea bed surface samples were collected using a day grab from different environments these were analysed for grain size distribution carbonate content and clay mineralogy on the basis of the bathymetric and shallow geophysical data the area has been classified into five major physiographic environments according to their bathymetry and topography 1 shelf thermaicon plateau 2 slope 3 marginal plateau 4 the canyon system and valleys and 5 sporades basin based on the sedimentological analyses the surface sediments have been classified into four major provinces as follows 1 province 1 shelf muds 2 province 2 muddy sands 3 province 3 outer margin muds and 4 province 4 outer shelf shelf break it is concluded that modern sedimentation in the n w aegean sea is dominated by the terrigenous river inputs and by the circulation of both high and low salinity masses

a new giant ground bird from the upper cretaceous of southern france new discoveries afford a much better knowledge of the large birds previously reported from the upper cretaceous of southern france on the basis of a single synsacrum fragment an incomplete pelvis consisting of the synsacrum with part of the ilia is used to define a new taxon of bird gargantuavis philoinos to which a femur is also referred this bird is characterized by its very large size comparable to that of an ostrich a broad pelvis with an anteriorly placed acetabulum and a short robust femur the occurrence of this very large flightless bird in the late cretaceous shows that contrary to widespread opinion the evolution of large terrestrial birds was not simply the result of adaptation during the cenozoic to ecological niches left empty by the extinction of the dinosaurs it also strongly suggests that some of the large fossil eggs from the upper cretaceous of southern france were laid by large ground birds rather than dinosaurs

water masses in thermaicos gulf north western aegean sea physical oceanographic data were collected during september 1975 at stations in the shallow water max depth 45 m embayments of salonica bay and thermaicos gulf and comparisons are made with data collected during other seasons the distribution of temperature and salinity in the water column indicated the following features fresh surface water predominantly related to river discharge an intermediate water mass apparently formed by mixing between the fresh and open sea waters a thermocline and deep bottom water open sea characteristics the summer distribution of density in the surface and bottom waters and the seasonal variation in the pattern of surface salinity suggested an anti clockwise water circulation throughout the embayments

origin of late glacial holocene hemipelagic sediments in the aegean sea clay mineralogy and carbonate cementation abstract four hemipelagic lithological units are identified in the late glacial to holocene sediments in the aegean sea these lithologies are silty clay and clay in texture and include a varying mixture of loose terrigenous sediments supplied from the adjacent landmass gravel to sand sized cemented carbonate clasts and nodules sand to silt sized air born volcanic debris and biogenic remains sediment dispersal during the past 14 000 years was controlled mainly by the fluvial discharge rate by sea level variations which determined the proximity of basins to river mouths and by oceanographic conditions in the aegean sea cemented carbonate clasts and nodules occur in all sediments except unit c sapropel s1 they are well to friably cemented mottled to peloidal micrite or microcrystalline inter granular cement between terrigenous and bioclastic debris and the carbonate is 10 11 mole magnesium calcite during the deposition of sapropel s1 unit c the aegean sea was strongly stratified with colder more saline water masses occupying the deep basins which prevented the development of cemented carbonate nodules and clasts aragonite as pteropods and microcrystalline aragonite is present throughout the cores and together with the cemented carbonate clasts and nodules show that shallow pore waters in the aegean sea have been saturated to supersaturated with respect to both aragonite and magnesium calcite for at least the past 14 000 years results of xrd studies show that unit c sapropel s1 is characterized by lower smectite and kaolinite and higher illite and chlorite than the other units lower smectite illite and kaolinite chlorite ratios in unit c may reflect increased supply of illite and chlorite from european lowland rivers flowing into the black sea from rivers discharging directly into the northern and eastern aegean sea and decreased supply of kaolinite which is mainly of north african origin

delta progradation and sediment fluxes since the last glacial in the thermaikos gulf and the sporades basin nw aegean sea greece abstract late quaternary sedimentary cover in the thermaikos gulf consists of three seismic units i the uppermost unit a that represents delta progradation during the last 6000 yr when the sea surface almost reached the present level highstand systems tract hst ii unit b that includes relatively coarse grained sediments deposited in a shallow high energy estuarine environment during the post glacial transgression transgressive systems tract tst and iii the lowest unit c which may represent late glacial prodeltaic deposits and slope to basin turbidites lowstand systems tract lst seismic units a and b overlay a well defined unconformity which resulted from sub aerial erosion during the late glacial sea level fall subtracting the thickness of unit a from the present bathymetry the paleo relief of the late holocene times ca 6000 yr bp sea level up to 20 m was assessed similarly the paleo relief 24 000 yr bp sea level 100 to 120 m was estimated the main morphological feature is the incised valley of a major river that resulted from the confluence of the axios aliakmon loudias gallikos and possibly pinios rivers sediment fluxes in the nw aegean sea were estimated for three time spans of the late quaternary interval i 6000 yr bp present interval ii 18 000 6000 yr bp and interval iii 24 000 18 000 yr bp the terrestrial sediment load supplied by the axios aliakmon pinios and smaller rivers was estimated at 35 4 10 9 t for interval i 93 of this material was deposited on the continental shelf whereas the remaining 7 was transported to the adjacent basin the mean annual terrestrial flux was estimated at 5 5 10 6 t yr 1 during interval ii more than 79 10 9 t of terrestrial sediment were discharged into the area terrestrial flux 6 6 10 6 t yr 1 of which 86 was deposited on the shelf during interval iii the terrestrial load was 40 6 10 9 t terrestrial flux 6 8 10 6 t yr 1 and sediments were predominantly deposited on the slope and basin based on the sediment s carbonate content the biogenic loads and fluxes were also determined the biogenic flux during intervals ii and iii was found to be 2 5 times higher than during interval i

weathering rates and anthropogenic influences in a sedimentary basin sao paulo state brazil abstract the weathering rate of rocks and chemical dynamics of the corumbatai river basin sao paulo state brazil were evaluated using major elements as natural tracers this basin has serious environmental problems in terms of quality of surface and rainwater which affect the determination of weathering rate the corumbatai river downstream from rio claro city receives several elements compounds through anthropogenic activities with only k so42 and alkalinity yielding positive flux values the negative flux of some anions cations can be attributed to atmospheric loading mainly related to anthropogenic inputs providing k a value of 16 7 ton km 2a 1 for the material removed by weathering in the corumbatai river basin this is equivalent to 26 106 kg of rock being removed each year by the corumbatai river the instantaneous flux was found to be a function of discharge with the majority of dry residue dissolved load being transported during the summer wet months the removed material in corumbatai river basin derives mainly from two sub basins cabecas river and passa cinco river where the sandstones weather more easily than siltstones and claystones in the basin

origin and distribution of clay minerals in the alexandroupolis gulf aegean sea greece the mechanisms of clay mineral distribution in alexandroupolis gulf are studied the annual solid supply of the evros river flowing into the gulf amounts to at least 1 000 000 m3 the surficial bottom sediments are commonly fine grained and are distributed along zones almost parallel to the coastline in the central part of the gulf clay silt size sediments predominate the main clay minerals in the size fractions 2 1 1 0 25 and 0 25 m are illite smectite kaolinite and in small amounts interstratified illite smectite quartz feldspars amphiboles and chlorite occur in traces in the coarser fraction 2 1 m of some samples all the above minerals are the weathering products of the evros river drainage basin as well as of the neogene and quaternary unconsolidated sediments of the coast the hydrodynamic regime and physical grain size are the main mechanisms which control the distribution of the clay minerals in the gulf the low content of kaolinite in all samples and the presence in traces of chlorite and amphiboles in some coarse clay fractions may be due to the unfavourable climatic and physicochemical conditions as well as to the rapid transport and deposition of freshly weathered material

the diversity of sauropod dinosaurs and their first taxonomic succession from the latest cretaceous of southwestern europe clues to demise and extinction article i nfo southwestern europe is a key setting to evaluate the diversity of non avian dinosaurs before the end of the cretaceous below the k pg boundary the ancient ibero armorican island encompassing the current regions of north east iberia and south france provides a substantial record of sauropod fossils the study of multiple sauropod femora from localities where upper campanian to uppermost maastrichtian successions are both exposed together with the integration of the information gathered from previously known localities has allowed the biodiversity of sauropods to be reassessed within a precise and clear chronostratigraphic framework from the studied sample several titanosaur forms have been distin guished including a gracile and small sized titanosaur lirainosaurus astibiae a robust medium sized titanosaur ampelosaurus atacis a gracile medium sized titanosaur atsinganosaurus velauciensis and five other indeterminate but distinct titanosaurs which span the late campanian through the entire maastrichtian the youngest of these occurs in the uppermost part of palaeomagnetic chron c30n in the latest maastrichtian 0 4 1m a before the k pg boundary representing the youngest sauropod yet doc umented in eurasia the pattern of diversity on the ibero armorican island rules out a decline in sauropod diversity at the very end of the cretaceous as with other regions during the late cretaceous the abundance and quality of the sauropod fossil record is probably influenced by multiple biases sampling ecological and environmental

the paleoclimatic interpretation of clay minerals in sediments a review abstract the application of paleoclimatic interpretation to clay minerals from continental and marine sediments is reviewed and the advantages of this method are indicated levels relatively rich in chlorite illite palygorskite and quartz are interpreted as corresponding to relatively dry periods while more humid periods lead to more intensive weathering and consequently to the dominance of clay minerals more advanced in the relative stability scale such as kaolinite smectite is taken to indicate a climate with contrasting seasons and a pronounced dry season using this and similar schemes the paleoclimates of areas adjoining the mediterranean basin north sea north atlantic southern arctic equatorial and north west pacific and north phillipine sea are reconstructed clay minerals in sediments particularly marine sediments can be useful indicators of paleoclimatic conditions while they do not produce direct indications of climatic parameters they provide integrated records of overall climatic impact occasionally they may be superior to the more conventional paleoclimatic methods such as pollen or oxygen isotope analysis the limitations imposed on the paleoclimatic interpretation of clay minerals in sediments are discussed on the basis of examples the distinction between authigenic and detrital clay minerals is shown to be problematic particularly with regard to smectite the relationship between climatic parameters and clay mineral formation is complicated by the intervention of extra climatic factors such as topography geomorphology lithology and time post depositional diagenetic changes may not be recognized differentiation during transport due to size sorting or differential flocculation may overlap climate induced differentiation the association of clay mineral assemblages with specific source areas presents difficulties due to dispersal pathways that are affected by type of transport agency i e water ice or wind transport agencies are not constant with time by an interdisciplinary approach with the paleoclimatic information derived from clay minerals being correlated with that obtained from the analysis of microfossils and oxygen isotope data many of these limitations can be overcome

late quaternary sedimentation on the north aegean continental margin greece the late quaternary seismic stratigraphy of the north aegean continental shelf and adjacent basins has been interpreted from boomer and 3 5 khz seismic profiles ages derived from shallow cores and offshore wells and relative offsets on small synsedimentary faults provide chronological control sea level history inferred from seismic stratigraphy correlates with the global eustatic sea level record based on oxygen isotopic curves outer shelf progradation correlates with lowstands of sea level in isotopic stages 2 3 and 6 whereas shelf wide transgression surfaces correspond to the stage 6 5 and 2 1 transitions when rapid deglaciation occurred the present depth of the delta plain formed on the outer shelf during the late stage 6 lowstand provides a dated and originally horizontal marker for estimating rates of tectonic subsidence gross distribution of sediment facies is similar in both tectonically stable and active areas the shelf break formed by delta progradation but is marked by faults in most places because of the accommodation provided by graben subsidence rates of 0 3 1 5 mm yr standard sequence stratigraphic analysis can be applied to these sediments deposited during high amplitude quaternary sea level oscillations high rates of subsidence result in the preservation of an unusually complete record of sea level change major lowstand progradation is dependent on the duration rather than the magnitude of sea level lowstand the long glaciations in isotopic stages 6 12 16 and 22 resulted in the most prominent seaward progradation on the margin sandy lowstand turbidite deposits formed only when there was rapid fall in sea level otherwise sand was trapped on delta tops and silty muds were deposited in deep water

a basal ceratopsid centrosaurinae nasutoceratopsini from the oldman formation campanian of alberta canada a partial skull cmn 8804 of a ceratopsid from the upper unit of the campanian oldman formation of alberta is the first canadian example of the newly established nasutoceratopsini a new subclade of centrosaurinae defined as the stem based clade of centrosaurine ceratopsids more closely related to nasutoceratops titusi than to centrosaurus apertus the new clade is diagnosed in part by having a parietosquamosal frill lacking modified epimarginals a small nasal horncore large rostrolaterally directed postorbital horncores and a relatively short deep face although the cmn 8804 taxon closely resembles nasutoceratops its phylogenetic position within nasutoceratopsini is unresolved the cmn 8804 taxon would have been contemporaneous with dinosaurs from the lower portion of the dinosaur park formation 200 km to the northwest in dinosaur provincial park the presence of the cmn 8804 taxon in alberta and the approximately contemporaneous nasutoceratops in utah indicates that the nasutoceratopsins pers

the influence of mineralogy on weathering rates and processes in an acid sensitive granitic catchment abstract weathering in an upland catchment on granitic parent material has been studied by chemical and mineralogical analyses of soils long term weathering rates for base cations calculated from chemical analyses of the mineral horizons from soil profiles using zr as an internal immobile index element are among the smallest recorded for scottish soils 1 7 3 1 meq m 2 a 1 indicating that these soils are susceptible to acid deposition sodium is the base cation lost to the greatest extent from the soils due to weathering of plagioclase feldspar mainly in the coarse size fractions calcium is lost not only from plagioclase feldspar but also from hornblende grains of which show dissolution etch pits and denticulate surface features when examined by scanning electron microscopy weathering of hornblende present in basic inclusions in the granite is a significant weathering process in these soils a range of values for 87sr 86sr ratios in stream waters confirms the spatial variability of the material supplying ca to the streams the current weathering rate calculated from input output budgets to be 28 9 meq m 2 a 1 is much greater than the long term weathering rate but small compared to other catchments on similar parent material

temporal variations in sedimentation patterns nw aegean sea abstract cores are examined from the northern continental slope environment of the sporadhes basin the western part of the north aegean sea trough three distinct lithofacies have been identified which correspond with similar environments identified elsewhere in the western and southeastern mediterranean these layers turbiditic mud hemipelagic mud calcareous ooze represent late quaternary climatic and eustatic sea level changes and tectonic activity based on benthic foraminiferal evidence from the eastern part of the north aegean sea trough it is suggested that contemporary sediment supply and physical oceanographic conditions in the area under investigation might be conducive to sapropel formation also that the depositional sequence in the cores represents a gradual recovery in the mediterranean sea since its last stagnation and sapropel formation some 8000 years ago

the fossil vertebrates from lano basque country spain new evidence on the composition and affinities of the late cretaceous continental faunas of europe a newly discovered fossil locality at lano basque country has yielded a vertebrate assemblage of probably maastrichtian age comprising fishes amphibians reptiles and mammals it considerably enlarges our knowledge of the late cretaceous continental faunas of europe hitherto based on a much less complete record some taxa are recorded for the first time in europe and the fauna also contains the oldest known representatives of some groups amphisbaenians salamandrids the lan assemblage reveals an original fauna comprising both forms related to asian and north american groups and elements with gondwanan affinities

taphonomy of jack s birthday site a diverse dinosaur bonebed from the upper cretaceous two medicine formation of montana jack s birthday site is a diverse vertebrate assemblage from the upper two medicine formation of western montana age is roughly 74 ma the site covers roughly 3000 m2 and excavations over 140 m2 a large bone sample 1600 skeletal elements allowed statistical evaluation of the preservational and compositional variation within the site evidence including sedimentary facies plant and invertebrate fossils and bone orientation and condition indicates jack s birthday site represents part of a small shallow floodplain lake lithologies and fossil preservation vary from northwest to southeast over a distance of 50 m this variation represents a transition from lake through shoreline to marginal shoreline floodplain environments containing ten dinosaur taxa and a variety of non dinosaurs jack s birthday site provides one of the best single faunal samples of the region the vertebrate assemblage includes two taphonomic fractions the first consisting of attritional predominantly isolated and allochthonous elements represents a time averaged assemblage the other consists of associated parautochthonous remains restricted to a single horizon taxa represented by associated remains include three iguanodontoids hypacrosaurus prosaurolophus and gryposaurus and the theropod troodon associated individuals of these taxa have non random distributions within the site fisher s exact test p 0 01 and observed taxonomic clustering may reflect group behavior and or event mortality the four or more troodon represent the first described multi individual troodontid occurrence the diversity and spatial complexity of the parautochthonous fraction of the birthday site assemblage is difficult to explain discussion of possible event mortality mechanisms focuses on three drought botulism and cyanobacterial toxicosis these share an ability to act over an ecologically significant period of time affect a variety of species and concentrate mortality along water sources aspects that may have been important in generating the birthday site assemblage evidence at the site favors drought or perhaps a drought botulism hypothesis however taxonomic clusters could represent completely separate events with a variety of causes

salinity and weathering rate of rocks in a semi arid region abstract rain and river water samples were collected for one year in the salgado river basin a semi arid region in bahia state brazil total dissolved solids tds concentrations and na ca k mg and u contents were measured in these samples and also in rock and soil samples of the basin a geochemical balance and the chemical weathering rate of rocks were determined from these results the water of salgado river showed high concentrations of tds 1 42 g l 1 and cations thus it was impossible to determine the chemical weathering rate of rocks by using these major cations as indicator elements a rate of 36 t km 2 yr 1 was obtained by using uranium as a natural tracer salgado river water belongs to the most abundant group of surface waters found in northeastern brazil that is salty waters with high nacl concentrations

archosaurian reptiles with gondwanan affinities in the upper cretaceous of europe the late cretaceous mainly campanian and maastrichtian non marine vertebrate faunas of europe contain archosaurian reptiles which belong to groups otherwise known mainly or only from the southern gondwanan continents they include titanosaurid sauropods abelisaurid theropods and trematochampsid crocodilians the occurrence of these forms together with others of asiamerican affinities gives the late cretaceous vertebrate faunas of europe a peculiar composition which makes them clearly different from the well known faunas from western north america and central asia the gondwanan dinosaurs and crocodilians from europe provide evidence of faunal interchange across the tethys sea during the cretaceous possibly via the alboran plate or the apulian plate which may have functioned as stepping stones especially during periods of low sea level

marine transgressions and the evolution of cretaceous dinosaurs fluctuations transgressions and regressions of intercon tinental sea ways during the mesozoic era affected the habitat area of coastal plains by alternately restricting the space during transgressive phases and expanding the space during regressive phases in western north america a coastal plain stretched along the eastern front of the young rocky mountains during most of the late cretaceous here we report results of a six year field study of the sediments and dinosaur remains from this coastal plain in montana that provide evidence that anagenesis characterized dinosaur evolution at this time and that the evolutionary pulse coincided with a marine transgression

weathering rates at alto sorocaba basin brazil using u isotopes and major cations the aim of this paper was to evaluate the chemical weathering rate at alto sorocaba basin sao paulo state brazil as it is an important parameter on geomorphological characterization of continents several tools may be used for such evaluation and this work compares the results obtained from analytical data involving the uranium concentration the 234u 238u activity ratio and the major cation concentration for samples of waters soils and rocks from that basin the use of the natural uranium as a tracer in weathering rate rocks studies is advantageous since this element is virtually absent in rainwater and also allows obtaining the dissolution rocks coefficient by the 234u 238u activity ratio the alto sorocaba basin has serious environmental problems in terms of the quality of the rainwater and river waters and consequently the geochemical balance using the main cations presented some difficulties however measuring of the weathering rate utilizing the u isotopes method corresponded to 14 m year that allows estimating a time of 72 000 years to weather 1 m of rock at sorocaba river upstream from itupararanga reservoir under the present climatic conditions

dinosaur biostratigraphy of the edmonton group upper cretaceous alberta canada evidence for climate influence a high resolution biostratigraphic analysis of 287 dinosaurian macrofossils and 138 bonebeds in the edmonton group upper cretaceous of southern alberta provides evidence for at least three dinosa

late quaternary sea level change sedimentation and neotectonics of the gulf of gokova southeastern aegean sea abstract the sedimentary and tectonic late quaternary evolution of the gulf of gokova located at the southwest anatolia southeastern aegean sea region has been interpreted from 800 line km of 3 5 khz and single channel airgun seismic reflection profiles the older part of the gokova basin is formed by mainly e w trending faults and filled by the latest miocene pliocene quaternary hemipelagic sediments with thickness up to 2 5 km the lycian nappes which primarily cover extreme southwestern anatolia represent the basement rocks for the gokova region younger active faulting so called gokova transfer fault gtf which has not been previously discussed in the literature trends ne in the central part of the gulf of gokova basin and records sinistral strike slip motion broadly parallel to the convergence direction of the aegean anatolian and african plates the continental shelf of the northeastern gulf of gokova is mostly formed by numerous superimposed deltaic successions depositional sequences separated by major erosional unconformities during times of lowered sea level associated with late quaternary glaciations deltas prograded more than 40 km seaward from their present positions foreset progradation terminated with the rise of sea level in interglacial and post glacial times and deltas were relocated far inland these major transgressions resulted in unconformities that are correlated with the beginning of oxygen isotope stages 9 7 5 and 1 and provide chronostratigraphic markers for a detailed analysis of sedimentation patterns in the late quaternary all seismic lines show that the topset to foreset transition of the youngest pleistocene delta system developed around 145 150 ms below present sea level thus the maximum pleistocene sea level lowering 18 000 years bp was about 110 m the positions of maximum regression for isotopic stages 6 8 and 10 were found as 160 190 and 215 m below present sea level respectively paleo shoreline positions during isotopic stages 2 6 and 8 suggest an overall gradual subsidence of gokova basin during the last 0 5 ma in the southeastern aegean sea the seismic sedimentary chronology suggests that the gokova basin is subsiding at 0 3 0 4 mm year three bathymetric low and e w wnw ese directed two main ridges in the gulf area are noticeable from the bathymetric data and are well correlated to the seismic data while the main orientation of the gulf is e w more recent ene wsw and wnw ese structures are remarkable in the western and the mid eastern part of the gulf respectively subsidence rates are greatest in the southern center of the basin and decrease northward so that the northern area is being tilted southward

late pleistocene holocene sedimentation in the nw aegean sea a palaeoclimatic palaeoceanographic reconstruction sedimentological particle size organic carbon calcium carbonate clay mineralogy and radiocarbon dating and micropalaeontological investigation of 9 cores from the nw aegean sea eastern mediterranean have enabled five main lithological units to be identified the units cover a period from the late pleistocene to the present day on the basis of these results and reference to other studies a palaeo reconstruction is presented for the area the reconstruction takes into account the increase in sea level during the period the decrease in fluvial inputs issuing to the area from the north mediterranean coastline and the possible influence of water issuing from the black sea it is concluded that the sedimentological and oceanographic regimes of the area were strongly influenced by a fluvial component during the late pleistocene and early holocene whereas today the sedimentary record is more indicative of an open oceanic environment

the end cretaceous dinosaur succession in europe the tremp basin record spain abstract the succession of maastrichtian deposits in the tremp basin south pyrenean area spain has provided long sections with numerous dinosaur sites found in the aren and tremp formations the dinosaur record consists on titanosaur sauropods dromaeosaurid theropods hadrosaur ornithopods including lambeosaurines and nodosaurid ankylosaurians correlation of the sections enabled a clear succession of dinosaur localities to be established and thereby the succession of dinosaur faunas titanosaur remains are present throughout the series but are particularly abundant in the basal strata theropods and hadrosaur ornithopods are found all through the series lambeosaurine hadrosaur remains are restricted to sandstone channel beds close to the k t boundary the palaeoenvironmental conditions in each site were deduced from the sedimentological study which allows establishing a relationship between environments and dinosaur taxa and thus the over or under representation of taxa in the vertical succession to be unravelled titanosaurs and ornithopods are common in but not exclusive to marine to continental transitional and continental environments respectively ankylosaurians are so far restricted to marine to continental transitional environments but the sample is scarce the fossil richness and the possibility of correlations among the different local sections make the tremp basin one of the best places in europe to understand the final history on non avian dinosaurs the fossil record from the tremp basin suggests that they were well diversified during the whole maastrichtian until their extinction as observed in north america and asia sauropods were still present at the end of the maastrichtian and lambeosaurines occurred at least in the upper part of the maastrichtian

chronostratigraphic synthesis of the latest cretaceous dinosaur turnover in south western europe abstract in south western europe the uppermost cretaceous continental deposits in the different sedimentary basins of iberia portugal and north and central spain the pyrenees spain and france as well as languedoc and provence southern france provide one of the few terrestrial records that allow a comprehensive study of the campanian maastrichtian dinosaur assemblages for the last years the southern pyrenees has been the target of intense geological palaeontological and geochronological research hundreds of fossil localities are now framed in high resolution lithological sections the succession of these sites most of them located in the tremp syncline is based on the physical correlation of rock bodies as permitted by the general outcropping conditions outside this syncline correlation is supported by geochronologic and biostratigraphic data mainly magnetostratigraphy and planktic foraminifera biostratigraphy the integration of the entire dataset sheds new light on the maastrichtian dinosaur turnover characterized by a shift from a sauropod dominated to a hadrosauroid dominated faunal assemblage this turnover was progressive and involved immigrants from north america eurasia and gondwana which probably reached the study area after a sea level drop this faunal change was mainly triggered by the arrival of lambeosaurine hadrosauroids a group that rapidly displaced the rest of the herbivorous clades of the region some of the extinction events suffered by the pre turnover faunas during the maastrichtian coincide with marine isotopic and sea level drop events suggesting that faunal competition was not the only cause of the observed changes in dinosaur composition despite this faunal replacement the resulting ecosystem after the turnover shows no major loss of biodiversity before the cretaceous paleogene extinction event

distribution of clay minerals in surface sediments of the aegean sea a compilation extensive published data sets and some new data on the clay mineral composition of surface sediments in the aegean sea northeastern mediterranean sea have been compiled in order to map the distribution patterns of clay mineral assemblages and to decipher source areas and transport paths we distinguished six provinces a northwest aegean province a marmara dardanelles province a west turkey province a southeast aegean province a kithira province and a central aegean province the clay mineral assemblages in the coastal and shelf areas carry the signature of the riverine sediment discharge from southeast europe and turkey respectively the southern aegean sea is probably influenced by the river nile discharge and transport of clay minerals by surface currents the clay minerals in the central aegean sea form a mixed assemblage comprising components of the other assemblages a dispersion and dilution of clay minerals by surface currents is obvious

geochemistry and mineralogy of the nw aegean sea surface sediments implications for river runoff and anthropogenic impact abstract surface sediments of the nw aegean sea were analyzed for clay mineral composition 94 samples organic c and carbonate content and major and minor elements 112 samples illite is the most abundant clay mineral followed by smectite chlorite and kaolinite clay minerals are preferentially deposited within the continental shelf and slope environment due to the prevailing cyclonic circulation and the formation of flocs in the rivers pro delta areas the spatial distribution of major lithogenic elements si al ti fe is substantially biased by the presence of relict sands located in the central eastern part of the thermaikos gulf continental shelf biogenic elements ca sr are noticeably pronounced on the northern flank of the north sporades islands organic c content and minor elements cu zn as and pb are enriched markedly over the thessaloniki bay and gulf suggesting substantial human impact deriving largely from untreated or partly treated domestic and industrial effluents the terrigenous component of the elements is preferentially contributed from the axios river zn and pb the aliakmon river cr co ni cu and as and to a lesser extent from the pinios river v co ni and cu a considerable part of the metals originates in ultra mafic and volcanic formations which are abundant in the rivers catchment basins carbonate content exhibits great variability with the highest values observed in biogenic sediments of the sporades basin in the latter area mn and fe oxides and hydroxides were found as coatings on calcite the coatings were enriched in cr co ni zn as mo and pb due to adsorption or ion exchange during early diagenesis the combined influence of the river systems the thessaloniki metropolis and the diverse sedimentological background generates great patchiness in the distribution of major and minor elements

recent evolution of a mediterranean deltaic coastal zone human impacts on the inner thermaikos gulf nw aegean sea the inner thermaikos gulf is located in the northwestern aegean sea receiving water and sediment fluxes from the axios aliakmon gallikos and loudias rivers the geomorphological and sedimentological evolution of the system is reconstructed for the last 150 years 1850 2000 on the basis of detailed analysis of historical bathymetric charts late holocene history is considered within the context of changing riverine sediment supply and human activities three evolutionary stages are identified stage i 1850 1916 corresponds to a natural phase of rapid deltaic progradation and sea floor deposition with an average sediment accumulation rate of 6 5 10 6 m 3 a 1 during stage ii 1916 1956 human interference e g artificial changes in river delta plains realignment of channels and land reclamation schemes to the deltaic system increased sediment delivery to the coastal waters by a factor of three this in turn enhanced the progradation of the active river mouth areas in contrast stage iii 1956 2000 is characterized by significant coastline deltaic retreat and erosion of the adjacent sea floor net loss of 2 5 10 6 m 3 a 1 this was as a result of extensive river damming which trapped a significant part of the sediment moving seaward furthermore these human impacts have affected the character of the surficial sea bed sediments of the gulf by reducing the proportion of mud the response of the deltaic margin of the inner thermaikos gulf to various anthropogenic interventions seems to be analogous to that of other deltas in the mediterranean region where large drainage projects the development of irrigation networks and dam construction have taken place within their river basins

the first radiometric ages from the judith river formation upper cretaceous hill county montana a new isotopic age of ca 78 ma was obtained by the conventional k ar method and by laser fusion 40ar 39ar analysis of biotite and sanidine crystals from two bentonites in the judith river formation of kennedy coulee hill county montana the 40ar 39ar analyses yielded weighted mean ages of 78 2 0 2 ma biotite and 78 2 0 2 ma sanidine for sample 84mg8 3 4 and 79 5 0 2 ma biotite and 78 5 0 2 ma sanidine for sample 85mg7 16 1 these are the first isotopic age determinations from the judith river formation the dated bentonites in kennedy coulee bracket two significant judithian age mammal localities ucmp v77083 and v81234 the radioisotopic age of ca 78 ma for the hill county local faunas and correlations of other judithian local faunas with marine units suggest that the duration of the judithian was at least 5 ma judithian local faunas are probably correlative with the late campanian of the western interior similarities in the principal judithian mammalian faunas from alberta monta

chemical dynamics and weathering rates of a carbonate basin bow river southern alberta discharge is the dominant control on the tds load of the bow river tds varies inversely with discharge although discharge is the dominant control on concentration the sources of ions in the river are atmospheric deposition and water rock interaction atmospheric loading can be a significant source of some ions in the pristine headwaters of the river e g 50 of k 17 of so4 16 of cl in terms of water rock interaction the input of ions to the river is largely controlled by dissolution of carbonate and evaporite minerals the chemical denudation rate for the bow river at banff is 678 kg ha a or 1 50 108 kg of rock that is removed as dissolved load each year in the low range for an alpine carbonate basin an additional 11 kg ha a are removed as suspended load a rock volume of 5 45 104 m3 is carried by the bow river from banff national park each year

impact of nitrogen fertilizers on the natural weathering erosion processes and fluvial transport in the garonne basin knowledge of the impact of n fertilizers on the weathering erosion processes of soils in intensively cultivated regions is of prime importance nitrification of nh4 fertilizers produces hno3 in the basin of the garonne river enhancing soil degradation their influence on the weathering rates was determined by calculating the consumption rate of atmospheric soil co2 by soil weathering and erosion and its contribution to the total dissolved riverine hco3 this contribution was found to be less than 50 which corresponds normally to a complete carbonate dissolution by carbonic acid suggesting that part of the alkalinity in the river waters is due to carbonate dissolution by an acid other than carbonic acid probably hno3

holocene evolution in weathering and erosion patterns in the pearl river delta sediments in the pearl river delta have the potential to record the weathering response of this river basin to climate change since 9 5 ka most notably weakening of the asian monsoon since the early holocene approximate to 8 ka cores from the pearl river delta show a clear temporal evolution of weathering intensity as measured by k al k rb and clay mineralogy that shows deposition of less weathered sediment at a time of weakening monsoon rainfall in the early mid holocene 6 0 2 5 ka this may reflect an immediate response to a less humid climate or more likely reduced reworking of older deposits from river terraces as the monsoon weakened human settlement of the pearl river basin may have had a major impact on landscape and erosion as a result of the establishment of widespread agriculture after around 2 5 ka weathering intensity sharply increased despite limited change in the monsoon but at a time when anthropogenic pollutants e g cu zn and pb increased and when the flora of the basin changed sr 87 sr 86 covaries with these other proxies but is also partly influenced by the presence of carbonate the sediments in the modern pearl river are even more weathered than the youngest material from the delta cores we infer that the spread of farming into the pearl river basin around 2 7 ka was followed by a widespread reworking of old weathered soils after 2 5 ka and large scale disruption of the river system that was advanced by 2 0 ka

late quaternary tectonic and sedimentary history of outer izmir and candarli bays western turkey abstract air gun and 3 5 khz seismic profiles from the eastern aegean sea off turkey show that the continental shelf of outer izmir and candarli bays is formed by several superimposed deltaic sequences during times of lowered sea level associated with late quaternary glaciations deltas prograded seaward more than 60 km from their present positions foreset progradation ceased with the rise of sea level in interglacial and post glacial times and deltas were reestablished far inland in drowned river valleys these major transgressions resulted in unconformities within the superimposed prograded delta sequences the most recent three unconformities are correlated with the beginning of oxygen isotope stages 5 3 and 1 and provide chronostratigraphic markers for a detailed analysis of sedimentation patterns in the late quaternary the coastal shelf and basins are subsiding at an average rate of about 1 m per 1000 years this tectonic subsidence manifests itself as widespread normal block faulting which can be related to the pre miocene structural framework of the region

the chronostratigraphic framework of the south pyrenean maastrichtian succession reappraised implications for basin development and end cretaceous dinosaur faunal turnover abstract the evolution of the end cretaceous terrestrial ecosystems and faunas outside of north america is largely restricted to the european archipelago the information scattered in this last area can only be integrated in a chronostratigraphic framework on the basis of robust age constraints and stratigraphy therefore we have revisited the puzzling age calibration of the sedimentary infilling from the isona sector in the tremp syncline south central pyrenees an area renowned for its rich maastrichtian dinosaur fossil record aiming to shed light to existing controversial age determinations we carried out a new magnetostratigraphic study along the 420 m long orcau and nerets sections of that area our results reveal that most of the succession correlates to the early maastrichtian mostly chron c31r in accordance to ages proposed by recent planktonic foraminifera biostratigraphy the resulting chronostratigraphic framework of the entire maastrichtian basin recorded in the tremp syncline shows that a significant sedimentary hiatus of about 3 my characterizes most of the late maastrichtian in the study area this hiatus related to an abrupt migration of the basin depocenter is temporally close to similar hiatuses decreases in sedimentary rates and facies shifts recorded in other southwestern european areas the present chronologic framework sets the basis for a thorough assessment of end cretaceous terrestrial faunal turnover and extinction patterns and the establishment of a more rigorous pyrenean basin evolution analysis

clay mineral distribution in last glacial holocene sediment cores from the eastern marmara sea cinarcik basin izmit gulf transition nw turkey multisources and transport paths in a two way flow system abstract the regional variations in grain size xrd bulk and clay mineral distribution in 97 sediment samples from 6 gravity cores obtained from 20 to 300 m water depths have been investigated to reveal source and transportation patterns as well as the effects of climatic and sea level changes during the last 25 000 14 c bp in the eastern marmara sea ems nw turkey the major proportions of sediments in the ems consist of silt 20 83 and clay 17 90 whereas sand and gravel abundances rarely exceed 10 of the bulk minerals 10 a micas 23 55 and feldspars 17 55 dominate over quartz 10 21 and calcite 10 26 smectites 23 62 illite 18 36 chlorites 6 21 kaolinite 2 20 and 14s 14c mixed layer minerals 0 27 constitute the principal clay mineral assemblages both bulk and clay mineral assemblages in the ems are similar to those found in the izmit gulf on the southern marmara shelf at the marmara aegean approaches and the southern black sea this would suggest that there is no distinct source for mineral assemblages of the study area outside the marmara basin the concentrations of clay fractions and clay mineral assemblages tend to increase or decrease with depth in the cores but this is limited to some intervals and not to entire sections in the cores this distribution pattern therefore represents rather local sources of provenance and surrounding fluvial drainage basins together with dilution and distribution effects by current transport processes rather than the expected paleoclimatic features and sedimentary input by inflowing black sea and aegean sea water masses throughout the last glacial to holocene