chemical and physical denudation in the amazon river basin we present major and trace element data on the suspended and dissolved phases of the amazon river and its main tributaries the sr isotopic composition of the dissolved load is also reported special attention is paid to the abundances of ree and to their fractionation between the dissolved and suspended phase the rivers of the amazon basin are among the richest in dissolved ree and are similar to the rivers of the congo system however a greater range of fractionation between lree and hree is reported here at a global scale the rivers have intermediate patterns between those of the congo system and those of high ph rivers such as the indus and mississippi rivers only few elements rb u ba k na sr and ca are mobilized by silicate weathering these elements are strongly depleted in the suspended phase with respect to upper continental crust in the dissolved load these elements are controlled by atmospheric inputs and the weathering of the main lithologies we propose a model based on mass budget equations that allow the proportions derived from the different sources to be calculated as a consequence silicate carbonate and evaporite weathering rates can be estimated as well as the consumption of co2 by weathering of each of these lithologies physical weathering rates can be estimated by two complementary approaches on the one hand the multi year average of suspended sediments yields can be used to estimate physical denudation on the other hand we have developed a steady state model of erosion that allows us to calculate physical erosion rates on the basis of the dissolved load of rivers a mean crustal composition is assumed in this model for the rock sources of the drainage basins comparison of the rates predicted by the model to the observed rates shows good agreement for the lowland rivers but a strong discrepancy for the rivers derived from the andes andean rivers solimoes madeira and amazon have observed sediment yields much greater than those predicted according to the steady state model of chemical and physical weathering two interpretations can account for this inconsistency the first is that these rivers are not in steady state and hence that the soils are being destroyed the second requires that the local continental crust is different from the average continental crust of taylor and mclennan and contains a large proportion of sedimentary rocks using the measured sediment yields and assuming a steady state we can estimate the amount of sediment recycling for each drainage basin for the amazon at santarem we find that at least 25 of the mass of the upper continental crust of the amazon drainage basin is constituted of recycled material

a conceptual model for glaciogenic reservoirs from landsystems to reservoir architecture abstract glaciogenic sediments are present in many hydrocarbon producing basins across the globe but their complex nature makes it difficult to characterise the reservoir quality sedimentary units despite this ordovician glacial deposits in north africa and carboniferous permian glaciogenic sequences in the middle east have been proven to host significant economical hydrocarbon accumulations additionally discoveries have been made in the shallow

integrated computer aided basin modeling applied to analysis of hydrocarbon generation history in a northern italian oil field abstract the application of reaction kinetics to the analysis of hydrocarbon hc generation processes requires a detailed temperature history of potential source rocks in order to obtain optimum results the necessary accuracy can be obtained by employing integrated computer aided basin modeling techniques to simulate the depositional history resulting in a continuous record of temperatures throughout the study area the technique has been applied to the analysis of an on off structure hc generation problem in a northern italian oil field the simulation of the geologic processes shows that low sedimentation rates and more importantly the high thermal conductivities of the carbonate rocks resulted in low temperatures throughout most of the geologic history of the study area which were followed by a sudden rapid temperature increase in the off structure area during the last 6 5 ma the calculated temperature history enables an accurate determination of the hc generation history using a kinetic approach which shows how hc generation is closely controlled by the sedimentation history and structural development and which also describes its relation to trap formation it also shows why hcs are generated at very low vitrinite reflectance levels i e peak oil generation at approximately 0 6 r o determination of the hc generation rate gives additional critical information as even source rocks located in apparently good potential zones at present i e in the on structure area can be of minor importance for a trap due to slow generation rates and consequent low expulsion efficiencies

middle and late quaternary glacial lake outburst floods drainage diversions and reorganization of fluvial systems in northwestern eurasia abstract the middle and late pleistocene glaciations of northern eurasia had a great impact on the evolution of the modern drainage system this paper presents a review and synthesis on the palaeogeography of glacial lakes their drainage and impact on the re organization of the drainage systems during the last two glacial interglacial cycles we will focus on four regions 1 northern central europe and fennoscandia 2 the central part of the east european plain 3 the west siberian plain and 4 the aral caspian black sea area the main findings of the last decade s include the improved chronology of some major river system formation and of meltwater overflows across the continental drainage divides major drainage systems of the north central and west central part of the east european plain upper volga upper dnieper formed due to overspill of glacial lakes in late mis 6 with a partial re organization upper dnieper in mis 2 the aral caspian black sea cascade acted as a sink for glacial meltwater from the north the major meltwater yield to the aral and caspian seas occurred in mis 6 and late mis 5 in mis 2 the meltwater delivery via the volga valley into the caspian sea was low and therefore had only a minor influence on the sea level considerable meltwater discharge to the black sea through the dnieper river system occurred around the maximal stage of the mis 2 glaciation and ceased very quickly after the onset of deglaciation

tectonostratigraphy of the north alpine foreland basin correlation of tertiary depositional cycles and orogenic phases abstract tectonostratigraphic analysis of the depositional history of the north alpine foreland basin indicates that temporal relationships exist between short term events in the foredeep and the adjacent alpine orogen the foredeep can be divided stratigraphically into an alpine foredeep thanetian bartonian pre molasse basin latest bartonian earliest rupelian and molasse basin rupelian tortonian their general and tectonostratigraphic development includes time significant cycle sets and so called cenozoic rift and foredeep crf sequences which are apparently correlative to both foreland and orogen deformation events as well as to changes in global sea level individual basin fill sequences and consequently general stratigraphic and palaeogeographical aspects of the evolving basin system are thus found to be frequently defined by contemporaneous widely distributed tectonics and eustasy successive dominant depositional states underfilled steady state and overfilled episodes and facies flysch molasse are correlated with different concurrently progressing phases of the convergence and subduction history of the european and apulian plates

the baltic ice lake in south finland and its outlets abstract in finland the earliest stages of the ancient baltic have traditionally been divided into the pre baltic ice lake s the baltic ice lake and the yoldia phase the pre baltic ice lake stage has also been called the late glacial yoldia sea and karelian ice lake there are certain indications of a low water level during the allerod in southern finland before the earlier phase of the baltic ice lake two drainages of the baltic into the atlantic ocean seem to have occurred the first through the oresund strait in denmark from about 12 7 to 10 2 ka bp bolling allerod younger dryas and the second last one at the end of the baltic ice lake period through the area of billingen central sweden at about 10 2 ka bp younger dryas the possible connection of the baltic with the white sea arctic ocean has also been under discussion for a long time recently finnish geologists have been studying this problem in north and south russian karelia but no evidence of a connection between the white sea and the baltic has been found the last drainage of the baltic ice lake is not clearly proved by the finnish varve chronology morphologically the drainage can be seen as a lowering by about 25 26 m of the highest baltic coast line in the zone between the 2nd and 3rd salpausselka in western finland the subsequent rapid yoldia regression took place before the beginning of the ancylus transgression some sediment series demonstrate a brief marine influence from the ocean along the finnish coast during the yoldia phase

the estuarine geochemical reactivity of zn isotopes and its relevance for the biomonitoring of anthropogenic zn and cd contaminations from metallurgical activities example of the gironde fluvial estuarine system france abstract zinc stable isotopes measurements by mc icp ms validated by laboratory intercalibrations were performed on wild oysters suspended particles and filtered river estuarine water samples to provide new constraints for the use of zn isotopes as environmental tracers the samples selected were representative of the long range 400 km transport of metal zn cd etc contamination from former zn refining activities at decazeville i e 66 zn 1 and its phasing out recorded during 30 years in wild oysters from the gironde estuary mouth rno rocch sample bank the study also addresses additional anthropogenic sources urban and viticulture and focuses on geochemical reactivity of zn in the turbidity gradient and the maximum turbidity zone mtz of the fluvial gironde estuary in this area dissolved zn showed a strong removal onto suspended particulate matter spm and progressive enrichment in heavy isotopes with increasing spm concentrations varying from 66 zn 0 02 at 2 mg l to 0 90 at 1310 mg l these signatures were attributed to kinetically driven adsorption due to strongly increasing sorption sites in the turbidity gradient and mtz of the estuary oysters from the estuary mouth contaminated sediments from the lot river and spm entering the estuary showed parallel historical evolutions 1979 2010 for zn cd ratios but not for 66 zn values oysters had signatures varying from 66 zn 1 43 in 1983 to 1 18 in 2010 and were offset by 66 zn 0 6 0 7 compared to past 1988 and present spm from the salinity gradient isotopic signatures in river borne particles entering the gironde estuary under contrasting freshwater discharge regimes during 2003 2011 showed similar values 66 zn 0 35 0 03 1sd n 15 i e they were neither related to former metal refining activities at least for the past decade nor clearly affected by other anthropogenic sources therefore the zn isotopic signatures in gironde oysters reflect the geochemical reactivity of zn in the estuary rather than signatures of past metallurgical contaminations in the watershed as recorded in contaminated river sediments the study also shows that the isotopic composition of zn is strongly fractionated by its geochemical reactivity in the gironde estuary representative of meso macrotidal estuarine systems

a role for scavenging in the marine biogeochemical cycling of zinc and zinc isotopes zinc zn and cadmium cd are important biologically active trace metals in the ocean to date the marine distributions of these elements have been understood primarily in terms of biological assimilation by growing phytoplankton and regeneration of sinking biological material initial studies of zn and cd concentrations and stable isotope ratios 66zn and 114cd have therefore focused on their use as simple tracers of assimilation and regeneration in the oceans however these two processes are insufficient to explain new data on the marine distribution of zn and 66zn here using the first high resolution paired marine depth profiles of zn cd 66zn and 114cd we suggest that scavenging of zn onto organic matter plays a major yet largely unconsidered role in the marine cycling of zn this hypothesis is supported by culture experiments which show that zn released from degrading phytoplankton is rapidly scavenged back onto organic matter and that adsorbed zn is isotopically heavier than the dissolved phase by 0 58 in contrast very little cd or phosphate was scavenged and cd isotopes were not significantly fractionated during degradation our hypothesis is further supported by one dimensional modeling which reproduces observed marine 66zn profiles with 1 of zn adsorbed to particles understanding how zn cycling in the oceans is a balance between assimilation scavenging and regeneration is necessary in order to investigate 66zn as a tracer of marine productivity we anticipate that paired analyses of 66zn and 114cd will prove to be valuable new tools in constraining patterns of global primary productivity providing key information for the marine carbon cycle during periods of past and present global climate change

a vitrinite reflectance kinetic model incorporating overpressure retardation abstract the models currently used to predict maturation and hydrocarbon generation in petroleum basins use time and temperature as controlling parameters a small number of studies have indicated that overpressure can retard maturation although some of the published information from experimental investigations appears to be conflicting careful examination of the experimental conditions shows that both vitrinite reflectance and hydrocarbon generation are retarded by overpressures overpressure appears to result in the retention of volatiles within the molecular structure which prevents the molecular reorganisation necessary to produce higher reflectance values using a database containing vitrinite reflectance from both overpressured and normally pressured wells a kinetic model presro has been developed in which overpressure modifies the arrhenius a factor the model has been tested on two different basins south china sea and sable exhibiting a range of time temperature overpressure characteristics the results suggest that the maturity and timing of the onset of hydrocarbon generation differ significantly from those predicted by current models

grain size control of river suspended sediment geochemistry clues from amazon river depth profiles residual solid products of erosion display a wide range of size density shape mineralogy and chemical composition and are hydrodynamically sorted in large river channels during their transport we characterize the chemical and isotopic variability of river sediments of the amazon basin collected at different water depths as a function of grain size absolute chemical concentrations and sr and nd isotopic ratios greatly varies along channel depth the al si ratio tightly linked to grain size distribution systematically decreases with depth mostly reflecting dilution by quartz minerals a double normalization diagram is proposed to correct from dilution effects elements define fan shaped patterns and can be classified in three different groups with respect to hydrodynamic sorting during transport in the amazon 1 poorly sorted insoluble elements like al fe th and rees 2 well sorted insoluble elements like zr and ti mainly carried by heavy minerals and 3 alkali na to cs and alkali earth elements mg to ba for which a large variety of patterns is observed related for alkali to their variable affinity for phyllosilicates sr isotopes show that the amazon river at the mouth is stratified the madeira and solimoes derived sediments being preferentially transported near the channel surface and at depth respectively the comparison between the solimoes and madeira rivers shows how the interplay between grain sorting weathering and crustal composition controls the composition of the suspended river sediments

relationship between rank and composition of aromatic hydrocarbons for coals of different origins distributions of di and tricyclic aromatics were determined for upper carboniferous to oligocene coals of various origins in addition to upper carboniferous ruhr coals wealden lower creataceous coals from north west germany lower cretaceous coals from western canada and tertiary coals from japan and colombia were studied the coals ranged from sub bituminous to anthracite in rank and showed vitrinite reflectance from 0 4 to 4 9 rm the previously established relationship between the rank of coal in terms of vitrinite reflectance and the distribution patterns of individual aromatic hydrocarbon isomers has been verified and refined it is demonstrated how the above relationships can be used to calculate vitrinite reflectance from the methylphenanthrene index mpi 1 the chemical rank levels of coals can now be defined in terms of the calculated vitrinite reflectance rc

the copper isotope geochemistry of rivers and the oceans abstract we present the first extensive dataset for copper cu isotopes in rivers as well as preliminary data for estuaries and seawater rivers exhibit a range in dissolved 65 cu relative to nist srm 976 of 0 02 to 1 45 per mil the discharge weighted average dissolved 65 cu and cu concentration for the studied rivers representing around 25 of the global riverine water discharge are 0 68 and 18 8 nmol kg 1 respectively isotopic data for the dissolved phase in two small estuaries in se england exhibit relatively minor variation through the salinity gradient 0 42 to 0 94 and are close to both the data for the rivers upstream from the estuaries and a measurement of the coastal sea at their mouths analyses of the particulate phase in the estuaries reveal a complementary light pool 0 24 to 1 02 the isotopic composition of the total cu inventory is however close to that of the crustal source these data along with published constraints suggest that the isotopically heavy dissolved phase of all the rivers originates in an isotopic partitioning of the weathered pool of cu between a light fraction adsorbed to particulates and a heavy dissolved fraction dominated by cu bound to strong organic complexes open ocean seawater samples generally exhibit even heavier dissolved cu isotopic compositions than the riverine input 65 cu 0 9 to 1 5 the heavy isotopic composition of seawater is inferred to originate from intra oceanic processes the small dataset presented here is most consistent with further isotopic partitioning between an isotopically light pool adsorbed to particulates and a heavy dissolved pool strongly bound to organic ligands scavenging appears to have greatest impact in the surface ocean and least in both the oxygen minimum zone and the ocean bottom perhaps reflecting the relative importance of scavenging and thus the sequestration of light cu to particulate material at different depths

anthropogenic sources and biogeochemical reactivity of particulate and dissolved cu isotopes in the turbidity gradient of the garonne river france abstract high precision mc icp ms cu isotope measurements were performed on suspended particulate matter spm and filtered water sampled along the turbidity gradient of the fluvial gironde estuary garonne branch following a summer lasting period of low freshwater discharge high cu concentrations up to 200 g g in particulate organic carbon poc rich up to 14 particles upstream from the maximum turbidity zone mtz coincide with the most negative 65 cu values down to 0 39 this suggests the preferential uptake of light cu isotopes by phytoplankton or anthropogenic contamination from cuso 4 fungicides related to intensive wine farming in the area 65 cu 0 37 for vineyard soils suspended particulate matter samples in the mtz exhibit lower cu concentrations 35 g g and heavier isotopic compositions 65 cu 0 20 in average as recorded by other samples from the gironde watershed along the fluvial estuary dissolved cu is mostly enriched in heavy isotopes up to 65 cu 0 21 but negative signatures down to 65 cu 0 66 occur near the city of bordeaux release of dissolved cu was attributed to the mineralization of organic matter with a total addition of 600 ng l in the fluvial estuary continuously decreasing amounts of dissolved cu added with distance suggest that the observed cu release evolved towards completion in the mtz and contributed to negative values for dissolved cu isotopes as modeled by a rayleigh process urban wastewater effluents probably also contribute to both i the dissolved cu addition 10 20 in the mtz and ii negative cu isotope signatures further work is necessary to assess the respective roles of anthropogenic sources and biogeochemical fractionation processes accordingly the present study provides new insights into the potential of cu isotopes for fingerprinting sources and mechanisms involved in the biogeochemical cycle of cu in temperate aquatic environments impacted by anthropogenic activities

iron isotope composition of the bulk waters and sediments from the amazon river basin abstract the present study provides iron concentrations and isotopic compositions determined by multi collector inductively coupled plasma mass spectrometry mc icp ms along with key chemical mineralogical and physical properties of 35 representative bulk unfiltered waters and bulk sediments from the amazon river basin these samples from the amazon river five of its main tributaries the solimoes negro madeira tapajos and trombetas rivers and four sub tributaries the purus jau ucayali and napo rivers were essentially collected during seven field missions conducted for over two years these encompassed the centennial flood of may 2009 and the exceptional low water stage of september october 2010 thereby providing the most extreme hydrological situations that have been recorded over the last hundred years while the data confirmed massive losses of iron up to 19 000 tons day ca 50 of the amazon river bulk water budget in the solimoes and negro rivers mixing zone the fe isotope signatures of these bulk waters behaved conservatively this property allows the use of bulk water fe isotope signature to track iron sources and explain such isotopic signature in terms of simple mixing unfiltered samples from the organic rich black water rivers present light 57 fe relative to the average continental crust composition this contrasts with the composition of the bulk white waters carrying a high mineral suspended load that have 57 fe values undistinguishable from the crustal isotopic signature 0 1 relative to irmm 14 this observation indicates that the fe isotopic composition represents a reliable direct tracer of the iron speciation and therefore of the host phases of iron in its sources specifically the white water 57 fe most likely trace the signatures of igneous and sedimentary sources as well as of their lateritic soil minerals while the bulk black water 57 fe track a preferential release of fe that has gone through a reduction step in the organic rich horizons of tropical podzols as a result of the biological activity this study shows that the total iron transferred by the amazon river represents between 5 and 30 of the world s ocean fe input by rivers and this amazon bulk water iron displays an isotopic composition indistinguishable from that of the average continental crust

copper and iron isotope fractionation during weathering and pedogenesis insights from saprolite profiles abstract iron and copper isotopes are useful tools to track redox transformation and biogeochemical cycling in natural environment to study the relationships of stable fe and cu isotopic variations with redox regime and biological processes during weathering and pedogenesis we carried out fe and cu isotope analyses for two sets of basalt weathering profiles south carolina usa and hainan island china which formed under different climatic conditions subtropical vs tropical unaltered parent rocks from both profiles have uniform 56 fe and 65 cu values close to the average of global basalts in the south carolina profile 56 fe values of saprolites vary from 0 01 to 0 92 in the lower reduced part and positively correlate with fe 3 fe r 2 0 90 whereas 65 cu values are almost constant by contrast 56 fe values are less variable and negatively correlate with fe 3 fe r 2 0 88 in the upper oxidized part where large 4 85 65 cu variation is observed with most samples enriched in heavy isotopes in the hainan profile formed by extreme weathering under oxidized condition 56 fe values vary little 0 05 0 14 whereas 65 cu values successively decrease from 0 32 to 0 12 with depth below 3 m and increase from 0 17 to 0 02 with depth above 3 m throughout the whole profile 65 cu positively correlate with cu concentration and negatively correlate with the content of total organic carbon toc overall the contrasting fe isotopic patterns under different redox conditions suggest redox states play the key controls on fe mobility and isotope fractionation the negative correlation between 56 fe and fe 3 fe in the oxidized part of the south carolina profile may reflect addition of isotopically light fe this is demonstrated by leaching experiments which show that fe mineral pools extracted by 0 5 n hcl representing poorly crystalline fe hydr oxides are enriched in light fe isotopes the systematic cu isotopic variation in the hainan profile reflects desorption and downward transport of isotopically heavy cu leaving the organically bound cu enriched in light isotope as supported by the negative correlation of 65 cu with toc r 2 0 88 the contrasting mostly positive vs negative cu isotopic signatures in the upper parts of these two profiles can be attributed to the different climatic conditions e g high rainfall at a tropical climate in hainan favors desorption and the development of organism whereas relatively dry climate in south carolina favors cu re precipitation from soil solutions and adsorption onto fe hydr oxides our results highlight the potential applications of fe and cu isotopes as great tracers of redox condition ancient climate and biological cycling during chemical weathering and pedogenic translocation

phosphorus forms and reactive iron in lateglacial postglacial and brackish water sediments of the archipelago sea northern baltic sea abstract glacial transport is an important agent of p and reactive fe delivery to the ocean margins however whereas p may travel through salinity gradients reactive fe is substantially trapped in estuaries studies of glaciolacustrine to brackish water depositional successions elucidate processes associated with the glacial p and reactive fe flux into the oceans the sedimentary p species reactive fe oxide associated fe and al and mn c n and s geochemistry for sediment cores from three sites in the archipelago sea northern baltic sea were determined in order to understand the distribution and coupling of these geochemical components in the glaciolacustrine to post glacial lacustrine to brackish water depositional succession the up to 6 m long cores record deposition after 11 350 cal bp previous studies suggest that the studied depositional succession records development common for the deglaciation phase of large low relief epicontinental basins all the studied geochemical components are strongly coupled in the basal glaciolacustrine rhythmites which reflect their rapid deposition by glacial meltwaters low corg preac ratios suggest that a part of the rhythmite material is reworked from pre glacial deposits delivery rates are drastically lower in the successive post glacial lacustrine setting due to the decrease of sedimentation rate by an order of magnitude decoupling of reactive fe and associated components in the post glacial lacustrine clays reflect increasing contribution of sediment from the emerging shoreline and rivers but also post depositional overprinting by sulphidization the onset of brackish water conditions soon after 7600 cal bp led to 1 decoupling of reactive fe from the detrital flux due to the establishment of salinity gradients at the river mouths and 2 increased nutrient availability and production in water as the intensified accumulation and burial of reactive p species organic c and n indicate the higher organic deposition led to deteriorated seafloor oxygen conditions alternating thinly laminated to strongly bioturbated lithofacies characterise the brackish water muds and record temporal changes in the seafloor oxygenation the temporal changes in the seafloor oxygen conditions appear to be broadly linked to the holocene climate variability brackish water muds at the northern end of paimionlahti bay record anoxia during the medieval warm period 1250 450 cal bp oxic conditions during the little ice age 450 300 cal bp and anoxia until the present day on a finer scale the redox histories in adjacent sub basins differ considerably due to patchy topography sluggish bottom water exchange and high organic deposition in the area terrestrial organic influx can temporally overprint marine organic deposition in areas close to river mouths

floodplains of large rivers weathering reactors or simple silos abstract large river sediments are mostly derived from tectonically active mountain belts but then undergo a series of sedimentation temporary storage and reworking episodes on their journey to the ocean the long transfer time of these sediments through active floodplains might result in a significant chemical maturation via weathering reactions which is of critical importance for biogeochemical cycles at the earth surface this study reports the chemical composition of river sediments from different locations throughout the courses of the main tributaries of the amazon basin sampling along river depth profiles yields access to the whole grain size and chemical composition range of river sediment here weathering intensities i e losses of na k mg and ca associated with chemical weathering in floodplains are 1 examined as a function of grain size and 2 integrated over the whole grain size range for three selected long river reaches flowing through the foreland and the lowland of the amazon basin the upper maranon the beni and the lower madeira rivers a relatively small na loss through plagioclase dissolution is observed in the madeira reach while an important ca loss due to carbonate dissolution occurs in the two foreland reaches maranon and beni no significant loss of k and mg is observed in any of the reaches showing the low alterability of primary k and mg bearing minerals and suggesting retention of k and mg in the particulate phase by secondary minerals the combination of these findings with previously reported data on the downstream change of dissolved na k mg and ca fluxes suggests that chemical weathering of stable alluvial deposits could also significantly contribute to theweathering flux generated in foreland and lowland areas the comparison between the three amazon reaches and the gangetic plain tends to show that the features observed in the amazon are valid on a global scale finally we show that although resulting in a relatively small change in the chemical composition of the river sediment silicate weathering in the lower madeira floodplain can lead to a co2 drawdown equivalent to ca 10 of the total co2 consumption flux of the whole madeira basin

chemical weathering and atmospheric soil co2 uptake in the andean and foreland amazon basins abstract this study is a geochemical investigation of the andean and foreland basins of the amazon river at high spatial and time resolution carried out within the framework of the hybam research program hydro geodynamics of the amazon basin monthly sampling was carried out at 27 gauging stations located in the upper tributaries of the amazon basin from north to south the napo maranon ucayali madre de dios beni and mamore rivers the aim of this paper is to estimate the present day chemical weathering rate cwr as well as the flux of co 2 consumption from total and silicate weathering in the andes and foreland amazon basins and to discuss their distribution as a function of geomorphic and structural parameters based on the forward method the napo and other ecuadorian basins present high silicate weathering rates in comparison with the other basins we confirm that the maranon and ucayali rivers control the amazon hydrochemistry due to the presence of salt rocks and carbonates in these basins the madre de dios beni and mamore basins do not contribute much to the amazon dissolved load this north to south cwr gradient can be explained by the combination of decreasing weatherable lithology surface and decreasing runoff rates from the north to the south the foreland part of the basins or mountain lowland transition accounts for nearly the same proportion of the amazon silicate chemical weathering and carbonate chemical weathering fluxes as the andean part this result demonstrates the importance of the sediment accumulation areas in the amazon basin weathering budget and can be explained by the occurrence of a higher temperature the deposition of fresh sediments from andean erosion and a higher sediment residence time than in the upper part of the basin with a total co 2 consumption rate of 744 10 3 moles km year 1 and a silicate co 2 consumption rate of 300 10 3 moles km year 1 the upper amazon river andes foreland part is the most intense part of the amazon basin in terms of atmospheric co 2 consumption by weathering processes it is an important co 2 sink by weathering processes but accounts for only somewhat more than half of the co 2 consumption by silicate weathering of the amazon basin this result points out the importance of the lowland part of the basin in the inorganic c silicate budget the upper amazon accounts for 2 4 of the world s silicate co 2 consumption which is the same proportion as for the southern and southern east himalaya and tibetan plateau

geochemistry of large river suspended sediments silicate weathering or recycling tracer this study focuses on the major and trace element composition of suspended sediments transported by the world s largest rivers its main purpose is to answer the following question is the degree of weathering of modern river borne particles consistent with the estimated river dissolved loads derived from silicate weathering in agreement with the well known mobility of elements during weathering of continental rocks we confirm that river sediments are systematically depleted in na k ba with respect to the upper continental crust for each of these mobile elements a systematics of weathering indexes of river borne solids is attempted a global consistency is found between all these indexes important variations in weathering intensities exist a clear dependence of weathering intensities with climate is observed for the rivers draining mostly lowlands however no global correlation exists between weathering intensities and climatic or relief parameters because the trend observed for lowlands is obscured by rivers draining orogenic zones an inverse correlation between weathering intensities and suspended sediment concentrations is observed showing that the regions having the highest rates of physical denudation produce the least weathered sediments finally chemical and physical weathering are compared through the use of a simple steady state model we show that the weathering intensities of large river suspended sediments can only be reconciled with the silicate derived dissolved load of rivers by admitting that most of the continental rocks submitted to weathering in large river basins have already suffered previous weathering cycles a simple graphical method is proposed for calculating the proportion of sedimentary recycling in large river basins finally even if orogenic zones produce weakly weathered sediments we emphasize the fact that silicate chemical weathering rates and hence co2 consumption rates by silicate weathering are greatly enhanced in mountains simply because the sediment yields in orogenic drainage basins are higher hence the parameters that control chemical weathering rates would be those that control physical denudation rates

evaluation of hydrocarbon generation and migration in the molasse fold and thrust belt central eastern alps austria using structural and thermal basin models the molasse basin represents the northern foreland basin of the alps after decades of exploration it is considered to be mature in terms of hydrocarbon exploration however geological evolution and hydrocarbon potential of its imbricated southernmost part molasse fold and thrust belt are still poorly understood in this study structural and petroleum systems models are integrated to explore the hydrocarbon potential of the perwang imbricates in the western part of the austrian molasse basin the structural model shows that total tectonic shortening in the modeled north south section is at least 32 3 km 20 1 mi and provides a realistic input for the petroleum systems model formation temperatures show present day heat flows decreasing toward the south from 60 to 41 mw m2 maturity data indicate very low paleoheat flows decreasing southward from 43 to 28 mw m2 the higher present day heat flow probably indicates an increase in heat flow during the pliocene and pleistocene apart from oil generated below the imbricated zone and captured in autochthonous molasse rocks in the foreland area oil stains in the perwang imbricates and oil source rock correlations argue for a second migration system based on hydrocarbon generation inside the imbricates this assumption is supported by the models presented in this study however the model derived low transformation ratios 20 indicate a charge risk in addition the success for future exploration strongly depends on the existence of migration conduits along the thrust planes during charge and on potential traps retaining their integrity during recent basin uplift

varve microfabric record of seasonal sedimentation and bottom flow modulated mud deposition in the coastal northern baltic sea abstract eutrophication induced hypoxia has resulted in preservation of laminated sedimentary fabric in coastal areas of the northern baltic sea these laminites offer a potential technique for dating recently deposited organic rich muds but their formation mechanisms have been inadequately understood in this study microfabric of the modern laminated sediments in the coastal gulf of finland and archipelago sea was investigated through x radiography and scanning electron microscopy of samples embedded in epoxy resin the sedimentary fabric comprises rhythmic biogenic and lithogenic lamina successions reflecting seasonal changes in the composition of accumulating material the diatom rich biogenic lamina succession is formed during the vernal phytoplankton bloom through rapid sedimentation of aggregates composed of intact diatom frustules and minor proportions of clay rich lithic material that are enclosed in a sticky matrix of amorphous phytodetritus analogous to the formation of the marine snow accumulation of the lithogenic lamina succession results from decline in primary production towards late summer enhanced recycling of organic carbon due to grazing by zooplankton and intensified resuspension of lithic rich terrigenous material concomitantly with increased cyclonic activity towards late autumn and winter the inclusion of silt grains and isolated diatoms and faecal pellets in the lithogenic laminae attests to lateral transport and deposition from near bottom flows contradicting the generally accepted view that laminated sediments accumulate by suspension settling under quiescent conditions only accumulation rates inferred from 137 cs dating are consistent with the biogenic lithogenic lamina succession couplet thickness supporting the interpretation that the couplets reflect an annual cycle of deposition the results indicate that these modern laminated sediments provide a high resolution archive for assessing recent human induced environmental changes as well as a robust tool for evaluating the lateral expansion of seafloor oxygen deficiency due to anthropogenic eutrophication in the area during the past decades

a rouse based method to integrate the chemical composition of river sediments application to the ganga basin 1 the ganga river is one of the main conveyors of sediments produced by himalayan erosion determining the flux of elements transported through the system is essential to understand the dynamics of the basin this is hampered by the chemical heterogeneity of sediments observed both in the water column and under variable hydrodynamic conditions using acoustic doppler current profiler adcp acquisitions with sediment depth profile sampling of the ganga in bangladesh we build a simple model to derive the annual flux and grain size distributions of the sediments the model shows that ca 390 30 mt of sediments are transported on average each year through the ganga at haring bridge bangladesh modeled average sediment grain size parameters d 50 and d 84 are 27 4 and 123 9 mm respectively grain size parameters are used to infer average chemical compositions of the sediments owing to a strong grain size chemical composition relation the integrated sediment flux is characterized by low al si and fe si ratios that are close to those inferred for the himalayan crust this implies that only limited sequestration occurs in the gangetic floodplain the stored sediment flux is estimated to c a 10 of the initial himalayan sediment flux by geochemical mass balance the associated globally averaged sedimentation rates in the floodplain are found to be ca 0 08 mm yr and yield average himalayan erosion rate of ca 0 9 mm yr this study stresses the need to carefully address the average composition of river sediments before solving large scale geochemical budgets citation lupker m c france lanord j lave j bouchez v galy f metivier j gaillardet b lartiges and j l mugnier 2011 a rouse based method to integrate the chemical composition of river sediments application to the ganga basin

estimates of virgin rock temperature derived from bht measurements bias and error virgin rock temperatures are important to hydrocarbon exploration as these temperatures are necessary for the computation of source rock temperatures and for hydrocarbon generation computations several methods have been developed for determination of virgin rock temperatures from maximum temperatures recorded during logging in the past decades this paper describes an investigation where the calculated virgin rock temperatures from several different methods were examined for bias and accuracy using 18 different measurement series at the oseberg field the temperatures were corrected for different depths of burial and then compared with each other and with drill stem test dst measurements to investigate the inaccuracy of the methods the most advanced methods gave values close to the dst temperatures on average but with standard deviations as high as 9 degrees c the less advanced models like the horner plot method have systematically too low virgin rock temperatures by about 8 degrees c for the oseberg field with standard deviations of 8 degrees c the errors in calculated virgin rock temperatures are large enough to completely alter predictions of hydrocarbon generation in an area the large errors are attributed to poor quality data and to physical effects that are not properly taken into account in the temperature calculations improved sampling of temperature data can probably reduce the errors to some extent

basin modelling a new comprehensive method in petroleum geology abstract integrated basin modelling is used to understand and reconstruct the geological and thermal evolution of a sedimentary basin to quantify this information and hence to derive among other results the history of generation migration and accumulation of petroleum this new methodical approach is rapidly gaining world wide recognition throughout the geo scientific community because it offers two distinct advantages when addressing geological problems firstly it enables a logical quantitative treatment of very complex interrelated geological processes and secondly it permits these processes to be examined on the basis of an absolute geological time scale the prerequisites for basin modelling are 1 the translation of logical and consistent geological concepts into numerical form and then into suitable computer programs and 2 the application of these programs using high speed computers with large memories using such an approach is an important part of modern petroleum exploration because 1 1 provision is made for total coverage of the basin by allowing extrapolation to non drilled often deeper parts of the basin accessible only by using seismic data 2 2 a three dimensional view of the basin can be constructed and followed through geological time 3 3 an internal logic is utilised which is consistent with physical and chemical laws 4 4 geological geophysical and geochemical data are integrated and modelled iteratively and therefore control each other this paper shows the rapidly widening scope of basin modelling and points out some of the present day limitations and necessary research directions for the future it describes concepts for modelling of tectonic processes and for simulating expulsion of liquid petroleum

mixing processes in the amazon river at the confluences of the negro and solimoes rivers encontro das aguas manaus brazil the confluence of the rivers negro and solimoes gives birth to the amazon river near manaus brazil at their confluence these two rivers with their very different physical and geochemical characteristics provide an interesting example of the mixing of waters along a reach of approximately one hundred kilometres the purpose of this article is to describe and explain the spatial configuration of the solimoes negro rivers mixing zone based on a systematic sampling survey carried out in september 1997 using a special sampler and an acoustic doppler current profiler acoustic doppler current profiler the waters of the negro river differ from those of the solimoes river in their lower velocity 0 3 vs 1 m s 1 conductivity 8 vs 80 s cm 1 at 25 c turbidity 5 vs 80 ntu ph 5 5 vs 7 0 and higher temperatures by 1 c due to their higher density the waters of the solimoes river slide under those of the negro river and consequently negro river waters are located at the surface close to the left bank and solimoes river waters are located at the bottom close to the right bank the contact between the waters of the two rivers changes from a clearly defined vertical boundary to a diffuse horizontal boundary as they move downstream the complete mixing process takes more than 30 h and 100 km copyright 2009 john wiley sons ltd

bacterial methane in the atzbach schwanenstadt gas field upper austrian molasse basin part i geology abstract bacterial methane gas accumulations occur in upper oligocene to early miocene clastic deepwater sediments in the austrian molasse basin methane gas is produced from the upper puchkirchen fm aquitanian in the atzbach schwanenstadt gas field which is one of the largest gas fields in this basin the bacterial gas is composed of 97 vol methane 13 c 62 d 200 connate pore water below the gas water contact is characterized by low salinity ccl ca 0 25 mol kgw or 8900 mg kgw the top of the main reservoir zone a4 is approximately 1600 m subsurface thickness of reservoir intervals in the a4 sands the main reservoir is variable and ranges from 8 to 30 m with decreasing thickness to the north the porosity of the sand ranges from 13 to 20 permeability from 6 md to 70 md the reservoir temperature is 63 c reservoir rocks of this field wedge out to the north and represent dam break through splay sediment this reservoir architecture enabled early gas accumulation in a stratigraphic trap the source rocks and reservoir rocks are intimately connected claystone layers intercalate and seal the reservoir sediments these fine grained sediments with potential source rock characteristics contain immature organic matter of kerogen types ii iii the toc contents of these fine grained sediments vary from 0 34 to 0 94 wt the cement inventory of the source and reservoir rocks is characteristic for diagenetic pathways of organic rich sediments pyrite is preserved in the sediments as the first precipitation product due to rapidly developing anoxic pore water conditions a following dolomite precipitation dissolution phase was replaced by precipitation of calcite ankerite and siderite a last cement phase is chlorite the about 700 m thick upper puchkirchen fm was deposited during a time interval of about 2 6 ma aquitanian in a deep sea fan environment water depth 1000 m bottom water temperature of about 4 c free gas phases may have been trapped as gas hydrate due to basin subsidence and high sedimentation rates hydrates have been decomposed below the base of the gas hydrate stability zone 200 40 mbsf still during the aquitanian and thus still during or shortly after deposition of the upper puchkirchen fm

isotopic composition of zinc copper and iron in lunar samples abstract we determined by icp ms the concentrations and isotopic ratios of fe cu and zn in the ti rich lunar basalt 74275 in the lunar orange glass 74220 and in up to 10 lunar soils namely 14163 15231 64501 66041 68841 69941 70011 72501 75081 and 76501 two analyses of zinc in lunar basalt 74275 give 66 zn 0 17 and 0 75 values within the range of those measured in terrestrial basalts copper in lunar basalt 74275 has 65 cu 1 4 which is isotopically heavier than values observed in terrestrial basalts in the orange glass we measured 56 fe 0 24 65 cu 0 42 and 66 zn 3 6 these values of are more negative than those obtained for 74275 and for typical lunar basalts but for cu comparable to those observed in terrestrial sulfides and meteorites in lunar soils we found 0 11 56 fe 0 51 2 6 65 cu 4 5 and 2 2 66 zn 6 4 insofar as we can generalize from a small sample set s fe cu zn and cd show similar trends in isotopic fractionation on the moon lunar basalts have nearly terrestrial isotopic ratios relative to the lunar basalt 74275 the pyroclastic glass 74220 is enriched in the lighter isotopes of fe cu and zn and the soils are enriched in the heavier isotopes of fe cu and zn the patterns in the basalts are likely inherited from the source material the light isotope enrichments seen in the orange glass originated during lava fountaining or less probably during partial condensation of vapor and the heavy isotope enrichments in the lunar soils were likely created by a combination of processes that included micrometeorite vaporization and sputtering in the orange glass the light isotope enrichments relative to lunar basalts of zn are larger than those of cu if these enrichments reflect accurately the isotopic composition of the gas they suggest that cu is more volatile than zn in the liquid from which the gas derived a simple model built on the known flux of micrometeorites to the lunar surface and a published estimate that micrometeorites generate 10 times their own mass of vapor predicts heavy isotope enrichments comparable to those observed in soils but only if the regolith gardening rate is set at about one twentieth of the generally accepted value of 1 cm my this discrepancy may reflect the difference in the time constants for micrometeorite milling and decimeter scale gardening or the importance of sputtering

the geochemical filter of large river confluences abstract this study reports the behaviour and fate of major and trace elements in solid and solution in the encontro das aguas mixing zone in the amazonian basin this area results from the confluence of acidic organic rich rio negro and andean sediment rich rio solimoes the differences existing between these two water masses are likely to modify the partitioning of elements between solid and solution or to induce losses by physical or chemical removal to account for lateral and vertical heterogeneities in the river sections the fluxes of elements in dissolved and solid loads were estimated as accurately as possible using an interpolation technique a general loss of suspended particulate matter spm of 23 is measured 80 km after the confluence but the various elements and their associated hosted minerals are not affected in a similar way sispm caspm naspm or srspm mostly associated with coarse phases quartz and ca na feldspars are preferentially lost refractory elements cospm crspm tispm alspm nispm other alkali a and alkali earth ae elements kspm mgspm baspm fespm or organic carbon oc are lost to a lesser extent due to their occurrence in finer fractions such as clays smectite illite or kaolinite oxides and particulate organic matter pom in solution a ae and cudiss mostly originating from the rio solimoes behave conservatively by contrast refractory elements coming mostly from the rio negro exhibit important losses from 10 for doc to 60 for codiss changes in ph and ionic strength during the mixing may induce a sorption of these elements to particles supplied by the rio solimoes a clustering and or a settling of nanokaolinites phases or a sorption of aldiss fediss codiss mndiss or zndiss by dissolved organic matter dom the differential elemental settling at a river confluence could thus induce a phase shift between element supply and export out of a watershed the physical and chemical processes reported here for a river confluence could be applied in other mixing zones such as estuaries or mining exhausts

zinc and copper behaviour at the soil river interface new insights by zn and cu isotopes in the organic rich rio negro basin abstract the complex behaviour of zn and cu at the soil river interface was investigated in soil and riverine water samples from the rio negro basin a secondary tributary of the rio amazonas using their stable isotope compositions this acidic and organic river drains two types of intensely weathered terrains podzols in its upstream part and lateritic soils downstream bulk soil particles suspended particulate matter spm as well as colloidal fractions were sampled across the whole basin during low and high water stages in the basin zn and cu are mostly exported from lateritic soils and transported by organic colloids where significant losses are observed in the downstream part of the river the use of 66zn and 65cu measurements reveals distinct stories for these two metals in suspended sediments and colloids in the colloids the constant 66zncoll across the basin is induced by the same weak association mode between zn and organic ligands regardless of the origin of the water by contrast in spm the speciation of zn and thus 66znspm differ according to the type of drained soils zn is associated with organic complexes in particles exported with water draining podzol whereas zn2 is incorporated in the structure of the remaining kaolinite clays in lateritic output the stronger reactivity of cu than zn with organic ligands induces its complete complexation copper is controlled by refractory particulate organic matter pom and by reactive colloidal organic matter the latter being enriched in 65cu due to stronger binding interactions than in pom while the cu content remains constant in the upstream part of the rio negro downstream the decrease of spm and colloidal cu fluxes is associated with a constant 65cuspm and with an increase of 65cucoll at the rio negro outlet geochemical mass balance modelling based on spm cu and zn fluxes in spm and their associated isotopic signatures confirms distinct host phases for zn and cu and identifies the most probable places where losses of these two metals occur in colloids the observed cu isotope fractionation from 0 24 to 0 45 superimposed on the significant cucoll loss is assumed to result from a new isotopic equilibrium in a low velocity and high productivity zone cu rich colloids enriched in 63cu aggregate and settle down whereas the remaining heavy cu is partially complexed on strong organic ligands secreted by phytoplankton forming new cu colloids

the ratios of dibenzothiophene to phenanthrene and pristane to phytane as indicators of depositional environment and lithology of petroleum source rocks abstract the ratio of dibenzothiophene to phenanthrene and the ratio of pristane to phytane when coupled together provide a novel and convenient way to infer crude oil source rock depositional environments and lithologies such knowledge can significantly assist in identifying the source formation s in a basin thereby providing valuable guidance for further exploration the ability to infer this information from analysis of a crude oil is especially valuable as frequently the earliest samples in a new area may be shows and or drill stem test samples from exploratory wells which are characteristically drilled on structural highs stratigraphically remote from the source formation s a cross plot of dibenzothiophene phenanthrene versus the pristane phytane ratios measured on seventy five crude oils from forty one known source rocks ranging in age from ordovician to miocene consistently classified the oils into the following environment lithology groups marine carbonate marine carbonate mixed and lacustrine sulfate rich lacustrine sulfate poor marine and lacustrine shale and fluvial deltaic carbonaceous shale and coal the dibenzothiophene phenanthrene ratio alone is an excellent indicator of source rock lithology with carbonates having ratios 1 and shales having ratios the dibenzothiophene to phenanthrene and the pristane to phytane ratios can also be used to classify source rock paleodepositional environments the classification scheme is based on the premise that these ratios reflect the different eh ph regimes resulting from the significant microbiological and chemical processes occurring during deposition and early diagenesis of sediments the dibenzothiophene phenanthrene ratio assesses the availability of reduced sulfur for incorporation into organic matter and the pristane phytane ratio assesses the redox conditions within the depositional environment interpretation of these ratios has been aided by quantitative biomarker analysis and by carbon isotope data for pristane and phytane obtained by gas chromatography isotope ratio mass spectrometry

trace fossils as indicators of environmental change in holocene sediments of the archipelago sea northern baltic sea abstract biogenic structures in holocene sediments from the archipelago sea northern baltic sea were characterized through the analysis of x ray images of four cores collected from water depths between 32 and 66 m in the area initial colonization of endobenthic invertebrates occurred at 7800 80 calendar years bp the trace assemblage at this level is low diversity small diameter shallowly tiered and palaeophycus dominated rare arenicolites are also observed early colonization coincides with increasing marine influence in the post glacial lacustrine setting just before the dramatic onset of brackish water conditions established after 7600 bp the post incursion brackish water assemblage possesses a higher diversity of traces planolites arenicolites lockeia teichichnus which is taken to reflect the enhanced salinity and trophic state of the basin the shift from palaeophycus mottling to a planolites dominated fabric represents changed behavioural patterns in the endobenthic community due to changed substrate properties the ethology of the succeeding trace assemblage also represents a switch from domicile based activities such as predation scavenging and interface dominated deposit feeding to shallow tier deposit feeding finally traces are excluded from thinly laminated intervals demonstrating that seafloor oxygen deficiency commonly reached levels that were detrimental to colonization of the sediment substrate

the oceanic mass balance of copper and zinc isotopes investigated by analysis of their inputs and outputs to ferromanganese oxide sediments abstract the oceanic biogeochemical cycles of the transition metals have been eliciting considerable attention for some time many of them have isotope systems that are fractionated by key biological and chemical processes so that significant information about such processes may be gleaned from them however for many of these nascent isotopic systems we currently know too little of their modern oceanic mass balance making the application of such systems to the past speculative at best here we investigate the biogeochemical cycling of copper cu and zinc zn isotopes in the ocean we present estimates for the isotopic composition of cu and zn inputs to the oceans based on new data presented here and published data the bulk isotopic composition of dissolved cu and zn in the oceans 65cu 0 9 66zn 0 5 is in both cases heavier than their respective inputs at around 65cu 0 6 and 66zn 0 3 respectively implying a marine process that fractionates them and a resulting isotopically light sedimentary output for the better known molybdenum isotope system this is achieved by sorption to fe mn oxides and this light isotopic composition is recorded in fe mn crusts hence we present isotopic data for cu and zn in three fe mn crusts from the major ocean basins which yield 65cu 0 44 0 23 mean and 2sd and 66zn 1 04 0 21 thus for cu isotopes output to particulate fe mn oxides can explain the heavy isotopic composition of the oceans while for zn it cannot the heavy zn in fe mn crusts and in all other authigenic marine sediments measured so far implies that a missing light sink is still to be located these observations are some of the first to place constraints on the modern oceanic mass balance of cu and zn isotopes

liquefaction and varve deformation as evidence of paleoseismic events and tsunamis the autumn 10 430 bp case in sweden coastal seismic events generate instantaneous changes in relative sea level i e land level vs sea level tsunamis may cause disastrous damage to coasts and coastal habitation liquefaction and deformations of annually varved sediments provide information on paleoseismic events the evidence for a major earthquake and associated tsunami waves in sweden are explored thanks to the varve chronology liquefaction structures and varve deformations caused by this event can be dated at the autumn 10 430 varve years bp the magnitude is estimated at 8 or more on the richter scale the tsunami washed the previously blocked outlet of the baltic free of icebergs and pack ice so that marine water could suddenly invade the entire baltic forming the yoldia sea

acoustic evidence of a baltic ice lake drainage debrite in the northern baltic sea abstract the sudden drainage of the baltic ice lake bil at the end of the younger dryas chron was one of the major events within the pleistocene holocene boundary in scandinavia thus far the effects it might have had on sedimentary environments have been inadequately recorded outside of central and southern sweden in the present study high quality acoustic sounding data was used to examine and describe possible traces of the event from the north eastern baltic proper and gulf of finland sediments five acoustic facies were identified two of them bearing frequent indications of sediment deformation slumping sliding and homogenization the lower deformation zone is in the glacial clay deposited in the ice proximal environment the middle zone in the ice distal glacial clay and the upper zone in late glacial clay we suggest that the middle deformation unit may have basin wide significance because it represents a debrite system originating from sediment instability due to the sudden water level drop associated with the bil drainage at the transition of the younger dryas preboreal chrons

clay mineral composition of river sediments in the amazon basin abstract clay minerals are important in evaluating the maturity of suspended sediments weathering intensity and source area however there are processes that can change the mineral assemblage such as river transportation deposition remobilization and tributary inputs in terms of water discharge and sediment yield the amazon is one of the largest rivers in the world most of the suspended sediments come from the andes crossing the lowlands before reaching the ocean this study measures the spatial distribution of clay mineral assemblages over the entire amazon basin the results obtained show the main features of the amazon river main stem and larger tributaries from their sources to their confluence clay mineral composition highlights the evolution of the madeira and maranon solimoes river which start in the andes with high illite chlorite content downstream smectite contents increase moreover all shield tributaries show high kaolinite content the lower amazon river is characterized by relative high smectite content different from the andean sources the clay mineral results show that suspended sediments of the amazon river have three main sources 1 the andes mountains 2 the amazon shields and 3 the piedmont basins especially the pastaza alluvial megafan and the fitzcarrald arch basin lateral bank erosion plays also a significant role by the introduction of more mature sediments into the river enriched in smectite

new terrestrial heat flow map of europe after regional paleoclimatic correction application heat flow variations with depth in europe can be explained by a model of surface temperature changes 10 c new heat flow map of europe is based on updated database of uncorrected heat flow values to which paleoclimatic correction is applied across the continent correction is depth dependent due to a diffusive thermal transfer of the surface temperature forcing of which glacial interglacial history has the largest impact it is obvious that large part of the uncorrected heat flow values in the existing heat flow databases from wells as shallow as few hundreds of meters is underestimated this explains some very low uncorrected heat flow values 20 30 mw m2 in the shields and shallow basin areas of the craton also heat flow values in other areas including orogenic belts are likely underestimated based on the uncorrected and corrected heat flow maps using 5 km 5 km grid we have calculated average heat flow values uncorrected heat flow 56 0 mw m2 sd 20 3 mw m2 vs corrected heat flow 63 2 mw m2 sd 19 6 m wm2 and heat loss for the continental part total heat loss is 928 e09 w for the uncorrected values versus corrected 1050 e09 w

overpressure retardation of organic matter maturation a kinetic model and its application abstract a kinetic model t p ro has been developed to address the issue that overpressure increases the activation energies during organic matter maturation and that the retardation of organic matter maturation by overpressure is due to the fact that organic matter is hindered from progressive molecular ordering under overpressured conditions the mean effective stress i e mean stress minus pore pressure is much lower and the pore pressure is usually higher than under hydrostatic pressure conditions as a result the progressive molecular ordering of the vitrinite such as the aromatization is retarded and the vitrinite reflectance can hardly be increased the reflectance values predicted by t p ro model as it has been applied to the well ld3011 at yinggehai basin in south china sea are similar to the measured ones the kinetic model predicts that overpressure can cause the oil window floor and the peak oil generation to shift to greater burial depth in the case of yinggehai basin the local geological conditions are prone to generate light hydrocarbons and natural gas instead of oil hence they constitute the predominant products in this high temperature heating rate basin

multi element chemistry of some amazonian waters and soils abstract the rivers flowing through the amazon basin are both physically and chemically heterogeneous through detailed geochemical analyses variability is shown to be primarily controlled by both substrate lithology in the source region and soil geochemistry in the erosional regime the solute rich waters of the rio solimoes reflect the drainage from the andes mountains and the fertility of the varzea in contrast the solute deficient waters of the rio negro reflect the infertility of the lateritic and podsolitic terrains of the central amazon rivers flowing through the precambrian shield have an intermediate composition such observations suggest that it is possible to classify the chemical composition of amazonian rivers according to the soil types in their catchment regions and vice versa these findings have profound implications for using water chemistry as an indicator of the agricultural and mineral potential of a region results from this study also confirm that precipitation is a significant source of major cations and trace metals to solute deficient river systems such as the rio negro

the behaviour of cu and zn isotopes during soil development controls on the dissolved load of rivers abstract the stable isotopes of copper cu and zinc zn are finding increasing applications in surface earth geochemistry an important early observation is that aqueous pools of cu rivers and oceans are isotopically heavier than rocks of the continental crust for zn the global average 66 zn for rivers is identical to estimates of the upper continental crust but the oceans are slightly heavier here we study cu and zn abundances and isotopes in soils to assess how processes in the weathering environment control isotopic values of rivers and ultimately the oceans we investigated a range of soils developed on granitoid scotland and basaltic hawaiian islands rock substrates representing soil development times from 0 1 to 400 kyr mean annual temperatures of 6 16 c and mean annual precipitation map of 1060 5050 mm soils developed on the island of maui over 400 kyr and under high rainfall show the clearest chemical weathering signatures here in oxic soils cu and zn are both depleted by 50 90 with preferential loss of heavy cu 65 cu up to 1 2 lower than parent material and small shifts in 66 zn we attribute this to equilibrium fractionation between aqueous organic species that are removed from the soil versus sorption to residual fe oxyhydroxides in soils that are 0 1 150 kyr old in scotland and hawaii this same pattern is overprinted by biological cycling and the addition of mineral aerosol cu and zn with heavier isotope compositions in reducing soils on maui developed under the highest rainfall cu and zn are almost completely stripped from the soil leaving a very small residual pool with 65 cu and 66 zn values that range from those for the oxic soils back to and beyond parent material this removal of the light sorbed cu seen in oxic soils is attributed to the dissolution of fe oxides under anaerobic conditions perhaps microbially mediated leaving a very small residual isotopically heavier pool overall these data suggest that processes in soils create significant variability in cu isotopes with the heavy isotope exported from oxic soils in contrast small isotope fractionations of zn are generated in the soil environment these observations are consistent with those made previously for cu and zn isotopes in rivers but the maximum amount of cu and zn stored by world soils equates to only 30 130 years of the dissolved riverine flux soils cannot be the ultimate repository of the residual cu and zn required balancing the riverine flux and this must ultimately reside in the erosive products of soil formation in continental and ocean margin sediments

early burdigalian infill of the puchkirchen trough north alpine foreland basin central paratethys facies development and sequence stratigraphy abstract to improve the prediction of gas and oil in strata along the tectonically imbricated southern margin of the puchkirchen trough north alpine foreland basin central paratethys a better understanding of facies distribution and stratigraphic control of the basin is essential the present study provides bio and chemofacies analyses and a biostratigraphic evaluation for the pelitic hall formation from the borehole hochburg 1 in the central part of the puchkirchen trough a statistical evaluation of benthic foraminiferal assemblages together with geochemical proxy records toc sulphur hydrogen index 13 c toc 15 n tn reveals a succession of early burdigalian depositional environments following a major subaqueous erosional hiatus conglomeratic sands at the base of the section which contain reworked chattian and aquitanian foraminiferal assemblages record the reactivation of a basin axial channel system during the early burdigalian eustatic sea level rise the channel was cut off from its sediment sources on the shelf and a deepening bathyal environment was established agglutinated foraminiferal assemblages with abundant bathysiphon filiformis developed that were adapted to an unstable environment with frequent deposition of turbidites the middle part of the hall formation is characterized by prograding high relief clinoforms which are fed by the wachtberg delta of the paleo inn river high sedimentation rates are interpreted and increased input of terrestrial derived organic matter is documented with a strong correlation of toc and toc s and low hi values as well as frequent occurrences of ammodiscus spp and other opportunistic agglutinating foraminifers a renewed transgression reestablished a eutrophic and suboxic bathyal environment followed by the development of an oxygenated outer middle neritic shelf environment heralding the ultimate infill of the deep water basin based on a comparison of the revealed development to existing sequence stratigraphic models for the puchkirchen trough three sequences and their corresponding systems tracts can be identified for the lower middle and upper hall formation biostratigraphic evidence from benthic foraminifers and calcareous nannoplankton indicates that they correspond to the regional substages of the middle and upper eggenburgian and lower ottnangian and to global 3rd order sequences bur 1 3 the observations suggest a primary control of eustatic sea level on the puchkirchen trough rather than alpine tectonics during the burdigalian

oil oil and oil source rock correlations in the alpine foreland basin of austria insights from biomarker and stable carbon isotope studies abstract the alpine foreland basin is a minor oil and moderate gas province in central europe in the austrian part of the alpine foreland basin oil and minor thermal gas are thought to be predominantly sourced from lower oligocene horizons schoneck and eggerding formations the source rocks are immature where the oil fields are located and enter the oil window at ca 4 km depth beneath the alpine nappes indicating long distance lateral migration most important reservoirs are upper cretaceous and eocene basal sandstones stable carbon isotope and biomarker ratios of oils from different reservoirs indicate compositional trends in w e direction which reflect differences in source depositional environment facies and maturity of potential source rocks thermal maturity parameters from oils of different fields are only in the western part consistent with northward displacement of immature oils by subsequently generated oils in the eastern part of the basin different migration pathways must be assumed the trend in s s r isomerisation of c29 steranes versus the 20r 20r c29 steranes ratio from oil samples can be explained by differences in thermal maturation without involving long distance migration the results argue for hydrocarbon migration through highly permeable carrier beds or open faults rather than relatively short migration distances from the source the lateral distance of oil fields to the position of mature source rocks beneath the alpine nappes in the south suggests minimum migration distances between less than 20 km and more than 50 km biomarker compositions of the oils suggest oligocene shaly to marly successions i e schoeneck dynow and eggerding formations as potential source rocks taking into account their immature character best matches are obtained between the oils and units a b marly shale and c black shale of the normal schoneck formation as well as with the so called oberhofen facies results from open system pyrolysis gas chromatography of potential source rocks indicate slightly higher sulphur content of the resulting pyrolysate from unit b the enhanced dibenzothiophene phenanthrene ratios of oils from the western part of the basin would be consistent with a higher contribution of unit b to hydrocarbon expulsion in this area differences in the relative contribution of sedimentary units to oil generation are inherited from thickness variations of respective units in the overthrusted sediments the observed trend towards lighter 13c values of hydrocarbon fractions from oil fields in a w e direction are consistent with lower 13c values of organic matter in unit c

lithium isotopes in large rivers reveal the cannibalistic nature of modern continental weathering and erosion abstract the erosion of major mountain ranges is thought to be largely cannibalistic recycling sediments that were deposited in the ocean or on the continents prior to mountain uplift despite this recognition it has not yet been possible to quantify the amount of recycled material that is presently transported by rivers to the ocean here we have analyzed the li content and isotope composition li 7 of suspended sediments sampled along river depth profiles and bed sands in three of the largest earth s river systems amazon mackenzie and ganga brahmaputra rivers the li 7 values of river sediments transported by these rivers range from 5 3 to 3 6 and decrease with sediment grain size we interpret these variations as reflecting a mixture of unweathered rock fragments preferentially transported at depth in the coarse fraction and present day weathering products preferentially transported at the surface in the finest fraction only the finest surface sediments contain the complementary reservoir of li solubilized by water rock interactions within the watersheds li isotopes also show that river bed sands can be interpreted as a mixture between unweathered fragments of igneous and sedimentary rocks a mass budget approach based on li isotopes li al and na al ratios solved by an inverse method allows us to estimate that for the large rivers analyzed here the part of solid weathering products formed by present day weathering reactions and transported to the ocean do not exceed 35 li isotopes also show that the sediments transported by the amazon mackenzie and ganga brahmaputra river systems are mostly sourced from sedimentary rocks 60 rather than igneous rocks this study shows that li isotopes in the river particulate load are a good proxy for quantifying both the erosional rock sources and the fingerprint of present day weathering processes overall li isotopes in river sediments confirm the cannibalistic nature of erosion and weathering

the dachstein paleosurface and the augenstein formation in the northern calcareous alps a mosaic stone in the geomorphological evolution of the eastern alps the central and eastern areas of the northern calcareous alps nca are characterized by remnants of the dachstein paleosurface which formed in late eocene to early oligocene time and is preserved with limited modification on elevated karst plateaus in oligocene time the dachstein paleosurface subsided and was sealed by the augenstein formation a terrestrial succession of conglomerates and sandstones which are only preserved in small remnants on the plateaus some in an autochthonous position thermochronological data suggest a maximum thickness of the augenstein formation of 1 3 km possibly 2 km the age of the augenstein formation is constrained by the overall geological situation as early oligocene to earliest miocene fission track age data support an early oligocene age of the basal parts of the formation the source area of the augenstein formation consisted predominantly of weakly metamorphic paleozoic terrains greywacke zone and equivalents as well as the late carboniferous to scythian siliciclastic base of the nca to the south of the depositional area to the west the augenstein formation interfingered with the tertiary deposits of the inntal sedimentation of the augenstein formation was terminated in early miocene time in the course of the orogenic collapse of the eastern alps the augenstein sediments were eroded and redeposited in the foreland molasse zone from pannonian times 10 ma on the nca and the denuded dachstein surface experienced uplift in several pulses the dachstein paleosurface has been preserved in areas in which thick limestone sequences allowed subsurface erosion by cave formation and thus prevented major surface erosion

how important is it to integrate riverine suspended sediment chemical composition with depth clues from amazon river depth profiles abstract the vertical variability in mineralogical chemical and isotopic compositions observed in large river suspended sediments calls for a depth integration of this variability to accurately determine riverine geochemical fluxes in this paper we present a method to determine depth integrated chemical particulate fluxes of large rivers based on river sampling along depth profiles and applied to the amazon basin lowland tributaries the suspended particulate matter spm concentration data from depth profiles is modeled for a number of individual grain size fractions using the rouse model which allows to predict the grain size distribution of suspended sediment throughout the whole river cross section then using 1 the relationship between grain size distribution and the al si ratio 2 relationships between the al si ratio and the chemical concentrations the chemical composition of river sediment is predicted throughout the river cross section and integrated to yield the depth integrated chemical particulate flux for a number of chemical elements e g si al fe na rees for elements such as al fe rees th the depth integrated flux is around twice as high as the one calculated from river surface sample characteristics for na and si the depth integrated flux is three times higher than the surface estimate due to the enrichment of albite and quartz at the bottom of the river depth integrated 87sr 86sr composition of suspended sediment also predictable using this method differs by more than 10 3 from the surface sample composition finally potential implications of depth integrated estimates of amazon sediment chemistry are explored depth integration of particulate 87sr 86sr isotopic ratios is necessary for a reliable use of sr isotopes as a provenance tracer the concept of steady state weathering of a large river basin is revisited using depth integrated sediment composition this analysis shows that in the amazon basin river the previously observed discrepancy between 1 weathering intensities of channel surface sediment and 2 silicate derived dissolved fluxes is only slightly accounted for by the vertical variability of suspended sediment weathering intensities this observation confirms that most large rivers basins are not eroding at steady state

sediment transport and bed morphology at river channel confluences river channel confluences form important morphological elements of every river system being points at which rapid changes in flow sediment discharge and hydraulic geometry must be accommodated this article presents results of a quantitative investigation of sediment transport at channel confluences accomplished through both scaled laboratory flume simulation and complementary monitoring of a natural channel confluence bed morphology at channel confluences is characterized by three distinct elements avalanche faces at the mouth of each confluent channel a deep central scour and a bar within the separation zone formed at the downstream junction corner these elements are controlled predominantly by the confluence angle and the ratio of discharges between the tributary and mainstream channels as confluence angle and discharge ratio increase the sediment contributions from the confluent channels are progressively segregated in their paths through the junction with sediment being transported around rather than through the centre of the confluence this segregation of sediment loads is accompanied by the retreat of the main channel avalanche face from the confluence an increase in the scour depth a change in the orientation of the scour and an increase in the size of the separation zone bar field measurements closely replicate the flume simulation a model of sediment transport and bed morphology links these features to the fluid dynamics of these sites an understanding of confluence dynamics is important not only in considerations of channel morphology and design criteria but must form the basis for the interpretation of confluence sediments in the ancient record

insights into iron sources and pathways in the amazon river provided by isotopic and spectroscopic studies abstract the present study investigated the weathering and transport mechanisms of fe in the amazon river a particular emphasis was placed on fe partitioning speciation and isotopic fractionation in the contrasting waters of the solimoes and negro rivers and their mixing zone at the beginning of the amazon river samples collected in the end member rivers and thirteen sites distributed throughout the mixing zone were processed through frontal vacuum filtration and tangential flow ultrafiltration to separate the different suspended solid fractions i e particulate p 0 45 m and p 0 22 m colloidal 0 22 m c 5 kda and truly dissolved elements td 57 fe values relative to irmm 14 while the particulate fractions yielded light isotopic compositions of 0 344 for p 0 22 m and 0 104 for p 0 45 m fractions the mineral particulate rich waters of the solimoes river had dissolved and colloidal fractions with light isotopic composition 0 532 and 0 176 respectively whereas the particulate fractions yielded 57 fe values close to those of the continental crust i e 0 029 for p 0 22 m and 0 028 for p 0 45 m ten kilometers downstream from the negro and solimoes junction the concentrations of colloidal and dissolved fe species deviate markedly from conservative mixing a maximum fe loss of 43 g l i e 50 of the dissolved and colloidal fe is observed 110 km downstream from the rivers junction the contrasting negro and solimoes rivers isotopic compositions along the pore sized water fractions is attributable to the biogeochemical processes involving different types of upland soils and parental materials for instance the isotopic composition of colloidal and dissolved fe from the negro river are consistent with fe oxidation and complexation mechanisms at the interface between waterlogged podzols and river networks as supported by strong organo fe complexes signals observed by epr conversely the particulate and colloidal fractions from the solimoes river have 57 fe consistent with strong mechanical erosion in the andean cordillera and upland soils as evidenced by high concentrations of fe 3 oxides sensu lato measured by epr the massive dissolved and colloidal fe removal is associated with the evolution of the physical and chemical composition of the waters i e ionic strength during mixing which influences organo fe 3 and fe 3 oxyhydroxides stability several models are discussed to explain fe non conservative behavior including dissociation of organo fe complexes and the subsequent formation of solid fe 3 oxyhydroxides and semiquinone free radicals as evidenced by epr spectra demonstrating that organo fe signals decrease as fe 3 oxyhydroxides and free radicals signals increase as in estuarine regions the mechanisms involving fe transfer and loss in the mixing zone has a negligible effect on the bulk water fe isotopic composition this result suggests that a tropical basin similar to the amazon river basin delivers to the ocean waters with an fe isotopic composition similar to that of the earth s continental crust

lateglacial of lake onega contribution to the history of the eastern baltic basin abstract new stratigraphy data especially diatom analyses are presented from the area north of lake onega relevant to the discussion on possible lateglacial connection between the baltic sea and white sea following the deglaciation 12 000 11 000 years ago lake onega basin was occupied by a system of ice dammed lakes which drained to the lake ladoga basin when the ice retreated from the threshold leading to the white sea 11 000 years ago the water level dropped and since that the lake was controlled by its thresholds to the white sea and the baltic basin lake onega has remained distinctly above the sea level and no late weichselian sea connection existed between the white sea and baltic basins the marine diatoms frequently found in sediments are reworked older fossils as also suggested by some earlier workers lake onega drained to the white sea basin over the maselga threshold and also to lake ladoga between 11 000 and 10 000 radiocarbon years ago and to the white sea alone between 10 000 and 9500 years ago and the present outlet of lake onega river svir originated 9500 years ago

syn and post collisional heat flow in the cenozoic eastern alps the heat flow evolution of a continental collisional zone is exemplified by the eastern alps heat flow maps for the syn collision oligocene syn extrusion early middle miocene and post extrusion late miocene recent stages are presented and are discussed in relation to the orogenic evolution continental collision during paleogene time was characterized by extremely low heat flow 150 mw m2 a few hundred kilometers south of it the former was a result of crustal thickening and of thermal blanketing due to rapid sedimentation and nappe stacking the latter was caused by slab break off and magmatic activity the early middle miocene syn extrusion stage was characterized by rapid exhumation of metamorphic core complexes tauern and rechnitz windows and by magmatic activity styrian basin both mechanisms caused extremely high heat flow 200 mw m2 in contrast the orogenetic front remained cold thereafter magmatic activity ended and uplift rates decreased thus late miocene heat flow is characterized by low to moderately high values heat flow values 75 mw m2 were restricted to the transition zone of the pannonian basin characterized by thinned crust and to the tauern window area recent temperature data indicate a subtle post miocene increase in heat flow

fate of particulate copper and zinc isotopes at the solimoes negro river confluence amazon basin brazil abstract the behaviour and fate of copper cu and zinc zn at river confluences is poorly understood although chemical and physical processes during mixing of compositionally different tributaries might condition metal availability and fluxes to the ocean to identify and quantify the effect of such processes in river mixing zones particulate cu and zn isotope signatures 65cuspm and 66znspm were measured along cross sections and vertical profiles at the largest river confluence in the world the encontro das aguas mixing zone of the amazon river where the organic rich negro river meets the sediment rich solimoes river the negro river suspended sediments with highly variable cu and zn concentrations as well as 65cuspm and 66znspm are mostly influenced by organic matter and by the lateritic cover of the watershed the solimoes river suspended sediments more homogeneous in cu and zn concentration and isotope composition across the river section reflect the signature of weathered silicate rich sediments derived from the andes the solimoes river supplies the majority of the suspended cu and zn to the amazon river and despite important flux losses across the confluence 35 for cu and 27 for zn 65cuspm and 66znspm show a conservative behaviour during the mixing in the dissolved load cu concentrations and 65cudiss mostly supplied by the solimoes river behave conservatively whereas zn derived mainly from the negro river suffers an important loss 58 that can be attributed to zn adsorption onto the suspended sediments from the solimoes river this transfer does not induce a significant 66znspm shift in the amazon river suspended sediments therefore cu and zn isotope ratios in the suspended sediments behave conservatively through this confluence which mixes two very chemically contrasted rivers our findings thus suggest that the riverine isotopic information on the sources of particulate cu and zn is preserved during tributary mixing

late glacial and post glacial deposition in a large low relief epicontinental basin the northern baltic sea this paper presents a model of late glacial and post glacial deposition for the late neogene sedimentary succession of the archipelago sea in the northern baltic sea four genetically related facies associations are described i an ice proximal acoustically stratified draped unit of glaciolacustrine rhythmites ii an onlapping basin fill unit of rotated rhythmite clasts in an acoustically transparent to chaotic matrix interpreted as debris flow deposits iii an ice distal acoustically stratified to transparent draped unit of post glacial lacustrine weakly laminated to homogeneous deposits and iv an acoustically stratified to transparent unit of brackish water organic rich sediment drifts the debris flow deposits of the unit 2 pass laterally into slide scars that truncate the unit 1 they are interpreted to result from a time interval of intense seismic activity due to bedrock stress release shortly after deglaciation of the area ice berg scouring and gravitational failure of oversteepened depositional slopes may also have contributed to the debris flow deposition comparisons to other late neogene glaciated basins such as the hudson bay or glacial lakes formed along the laurentide ice sheet suggest that the archipelago sea succession may record development typical for the deglaciation phase of large low relief epicontinental basins the carboniferous permian glacigenic dwyka formation in south africa may provide an ancient analogue for the studied succession chronological control for the studied sediments is provided by the independent palaeomagnetic and ams 14c dating methods in order to facilitate dating of the organic poor early post glacial deposits of the northern baltic sea the 10 000 year long lake nautajarvi palaeomagnetic reference chronology ojala saarinen 2002 is extended by 1200 years