phosphate adsorption in oxidized marine sediments the oxidized surface layer of marine sediments can act as a trap for phosphate diffusing upwards from deeper layers thus influencing the flux of phosphate to the overlying water under oxic conditions adsorption of phosphate on metal hydr oxides is the major process responsible for binding of phosphate at short time scales quantitative insight in this process is essential for the understanding of phosphorus diagenesis in sediments numerous studies on the interaction of phosphate with natural and synthetic feand ai hydr oxides parfitt 1989 torrent et al 1992 soils parfitt 1977 lake sediments jensen et al 1992 and marine sediments krom and berner 1980 sundby et al 1992 have been performed under varying experimental conditions in most cases however the initial concentrations used during the sorption experiments are much higher than the prevailing pore water concentrations in oxidized sediments or the results at these low concentrations are not reliable due to experimental difficulties and or a limited number of data points the aim of this study was to quantify the adsorption of phosphate on oxidized surface sediments with different sediment properties at concentrations comparable to natural levels found in the pore waters at 8 locations in the north sea inp bels program february 1992 sediment from two box cores d 31 cm was subsampled with 20 acrylic liners d 5 6 cm all subsequent procedures took place at in situ temperature 6 c the upper 05 mm of the sediment from all cores was pooled and experiments started within a few hours characteristics of the sediments are given in table 1 sediment was incubated in 50 ml centrifuge tubes with filtered 0 2 lm north atlantic surface water containing low nutrient concentrations po4 0 05 tmol 1 1 spiked with varying amounts of dissolved phosphate all tubes were immediately shaken vigorously and then periodically every 15 min during the first hour subsequently every few hours until sampling after 48 hr isotherms or shorter periods kinetics after centrifugation 1700 g 15 min the supernatant was removed filtered 0 45 pm and analyzed for si and po4 strickland and parsons 1972 sediment pore water prior to incubation was obtained by the method of saager et al 1990 the amount of phosphate adsorbed on or desorbed from the sediment was calculated from the change in dissolved phosphate during the experiment results from the kinetics experiments at varying initial po4 concentrations and at two solid solution ratios as shown for station 5 in fig 1 indicate that phosphate is both adsorbed and desorbed rapidly by the sediments approximately 80 of the total amount adsorbed after 48 hr is adsorbed within 15 min when poa initial 7 05 tmol 1 1 and sediment solut ion 1 1 fig 1a at all initial

historical earthquakes and variable kinematic behaviour of the 2009 l aquila seismic event central italy causative fault revealed by paleoseismological investigations abstract paleoseismological investigations has been carried out along the causative fault of the mw 6 1 2009 l aquila earthquake we dug three trenches in two different sites on the paganica fault to understand its holocene kinematic behavior paleoseismological results show a minimum of three faulting events preceding the 2009 earthquake the most recent recognized event occurred after 1420 1610 a d tentatively attributed to the 1703 february 2 seismic shock a previous event happened between 1st 2nd century a d and 7th 9th century a d probably in the interval 4th 6th century a d while another identified previous event occurred prior to 1st 2nd century a d the observed minimum displacement per event varies from 0 25 m to 0 50 m consistent with a fault length of about 22 27 km from which we infer a maximum expected mw 6 6 6 7 this implies that the paganica fault may occasionally rupture during 2009 like seismic events as well as during larger earthquakes activating contemporaneously to nearby active faults kinematically and structurally linked to the paganica fault more specifically on the basis of our data and of recent paleoseismologic studies we hypothesize a linkage of the investigated fault with the upper aterno valley fault system in this perspective the paganica fault can rupture as an independent fault segment with recurrence interval of about 3 hundreds of years and together with the upper aterno valley fault system with recurrence interval that varies between 1000 and 1500 years

quaternary rock avalanches in the apennines new data and interpretation of the huge clastic deposit of the l aquila basin central italy abstract in this paper we inferred the origin of a huge clastic deposit i e l aquila breccia which widely crops out within the l aquila intermontane basin a tectonic depression in central apennines that is bounded by seismogenic active faults as demonstrated by the earthquake occurred on april 6 2009 mw 6 1 the genesis of this deposit is still debated in the literature for this reason a number of methods have been applied mainly aimed at evidencing its geomorphological and sedimentological features as well as at defining its geometry and volume through cross sections constrained by borehole data and field observations on the basis of the obtained results we identified such deposit as resulting from a quaternary rock avalanche event in particular the rock avalanche would have detached during the cold climate phases of late middle pleistocene from the southern slope of the gran sasso range a sector characterized by the presence of numerous dgsd related landforms we performed morphometric analyses of the gran sasso slope in order to define the potential source area of the inferred rock avalanche and according to the results the volume estimated from this area about 108 m3 is coherent with the volume calculated for the preserved rock avalanche deposit furthermore we analyzed the main features of the deposit i e age and morphometric parameters also in the light of similar rock avalanche events occurred in the same region during the quaternary with the aim of discussing potential analogues and better understanding the role of gravity induced processes in the quaternary morpho evolution of the apennine chain

the seismic response at high frequency in central l aquila a comparison between spectral ratios of 2d modeling and observations of the 2009 aftershocks abstract the city of l aquila is built on a deep intramontane basin filled by silty clay of lacustrine origin with average s wave velocity of about 725 m s topped by a calcareous breccias unit with a higher speed of about 900 m s new geologic and geophysical investigations following the 6 april 2009 m w 6 3 l aquila italy earthquake have allowed us to develop a new velocity model for the basin deposits that coupled with the inversion of velocity includes lateral velocity variations in the top breccia layer and a newly found red silts unit the limi rossi del colle dell aquila lrca the city area where the lrca unit outcrops is correlated with clusters of reinforced concrete buildings that collapsed in the normal faulting earthquake we simulate the 2d seismic response of this new velocity model along two orthogonal cross sections and compare the synthetic spectral ratios to the experimental ones evaluated using aftershock recordings as a result taking into account the full scatter about the mean of the observed spectral ratios we are able to predict not only the main features of the primary observed low frequency resonance peak but also the level of amplification at high frequency at most of the sites investigated

organic geochemical proxies of paleoceanographic paleolimnologic and paleoclimatic processes abstract organic matter constitutes a minor fraction of marine and freshwater sediments yet its important contribution to the sedimentary record can be used to reconstruct marine and continental paleoenvironments the organic matter content of sediments is the residue of past biota the amounts and types of organic matter present in sediments consequently reflect environmental conditions that impacted ecosystems at different past times general sources of the organic matter are inferred from bulk properties such as elemental compositions carbon and nitrogen stable isotope ratios rock eval pyrolysis data and organic petrography details of organic matter origins are refined by analyses of biomarker molecular compositions source changes are proxies for fluctuations in sea level oceanic surface currents and continental climates algal paleoproductivity rates are indicated by organic carbon mass accumulation rates and carbon and nitrogen stable isotopic compositions these parameters record past availability of nutrients and therefore are proxies of surface mixing in the oceans and amount of land runoff to lakes sea surface paleotemperatures are recorded by the number of carbon carbon double bonds in lipid biomarkers produced by marine algae larger proportions of the double bonds are proxies for the cooler surface waters that accompanied periods of global glaciation and intervals of enhanced upwelling the 13c and d values of plant organic matter record past concentrations of carbon dioxide in the atmosphere and changes in delivery of atmospheric moisture respectively diagenesis which causes the concentration and composition of organic matter in sedimentary settings to differ from those of the original biologically synthesized materials can bias organic geochemical paleoenvironmental records the magnitude of this potential source of misinformation must always be considered and evaluated comparison of multiple organic geochemical proxies of past conditions helps to compensate for the effects of diagenetic alterations and thereby to improve interpretations of paleoenvironmental change

origin of the northern atlantic s heinrich events as first noted by heinrich 1988 glacial age sediments in the eastern part of the northern atlantic contain layers with unusually high ratios of ice rafted lithic fragments to foraminifera shells he estimated that these layers are spaced at intervals of roughly 10 000 years in this paper we present detailed information documenting the existence of the upper five of these layers in odp core 609 from 50 n and 24 w their ages are respectively 15 000 radiocarbon years 20 000 radiocarbon years 27 000 radiocarbon years about 40 000 years and about 50 000 years we also note that the high lithic fragment to foram ratio is the result of a near absence of shells in these layers although we are not of one mind regarding the origin of these layers we lean toward an explanation that the heinrich layers are debris released during the melting of massive influxes of icebergs into the northern atlantic these sudden inputs may be the result of surges along the eastern margin of the laurentide ice sheet

phosphorus in foraminiferal sediments from north atlantic ridge cores and in pure limestones samples of foraminiferal ooze from two north atlantic cores were cleaned and progressively dissolved most of the p fe and mn was released during the first of two reductive cleaning steps most of the remainder of these elements and most of the ca were released during the final acid dissolution step the p in these samples is present largely in fe and mn rich coatings not as a constituent of the foraminiferal shells themselves our results are consistent with those of earlier studies the concentration of p in carbonate oozes in which it is clearly associated with coatings is similar to that of modern calcareous sediments in general and with that of reasonably pure limestones of all ages phosphorus is apparently associated with fe mn oxide coatings in many carbonate sediments the rate of removal of p from the oceans as a constituent of such sediments depends on the rate of formation of fe mn coatings not on the rate of incorporation of p into calcium carbonate

ancient shelf ridges a potentially significant component of the transgressive systems tract case study from offshore northwest java detailed stratigraphic evaluation of three dimensional 3 d seis mic volumes calibrated with well log and core data from the mio cene section of the offshore northwest java shelf reveals the exten sive presence of preserved shelf ridge deposits these features are long linear bodies ranging from 0 3 to 2 0 km wide more than 20 km long and up to 17 m high on close inspection these features appear to be asymmetric characteristically sharp edged and thicker on one side and gradually thinning with an irregular edge on the other side possible sand waves smaller in scale are observed super imposed on these ridges and oriented oblique to the long axes of the ridges the observed shelf ridge deposits tend to be sand prone and overlie ravinement surfaces the ridges appear to be oriented parallel with the axes of broad paleoembayments associated with the structural fabric of the basin in addition to shelf ridges shelf ribbons possibly less than 5 m thick and less than 100 m wide are also imaged sand ridges are common on modern shelves but significantly less commonly recognized in the subsurface or in outcrop the features observed here represent examples of preserved ancient shelf ridges these ridges are thought to have formed as a result of erosion and subsequent reworking of sand prone deltaic and or coastal plain deposits by shelf tidal currents which became active immediately after shoreline transgression these deposits appear to have migrated across the ancient sea floor and represent an important component of the transgressive systems tract these transgressive systems tract deposits have significant exploration potential because they are commonly sand prone and tend to be encased in shelf mudstone seal facies depending on the degree to which sand is present in interridge locations these linear sand bodies can comprise potential stratigraphic traps begin page 76

multiple origins of the paleogene natural gases and effects of secondary alteration in liaohe basin northeast china insights from the molecular and stable isotopic compositions abstract the molecular and isotopic c and h compositions of paleogene shahejie formation e 2 3 s and dongying formation e 3 d natural gases from 11 new gas samples as well as the data of 71 gases published from previous studies in the liaohe basin were analyzed and the results were considered in combination with geochemical and distribution characteristics of the source rocks the genetic type gas source correlation and secondary alteration of the natural gases were studied in detail and the source rock maturities of the gases were estimated the following conclusions were reached 1 with the exception of dry gases in the major part of the third member of the shahejie fm e 2 s 3 reservoirs the gases in other reservoirs are mainly wet 2 variable carbon and hydrogen isotopes of the alkane gases are observed in different reservoirs of the basin with 13 c 1 values ranging from 60 7 to 34 2 13 c 2 from 47 3 to 22 3 2 h ch 4 from 261 to 188 and 2 h c 2 h 6 from 269 to 148 3 the natural gases of the basin are of multiple origins and mixing of thermogenic and microbial is observed the mixing ratio in the first member of the shahejie fm e 3 s 1 is the highest among all the reservoirs 4 gases of different reservoirs suffered varying extents of biodegradation which caused partial reversal of the carbon isotope series of methane and its homologues 13 c 1 13 c 2 13 c 3 13 c 4 the reversal of the gases in the shallow reservoirs e 3 s 1 and e 3 d is greater while those in the deep reservoir e 2 s 3 is less 5 humic natural gases of the ed were mainly generated by source rocks at early maturity while the sapropelic ones of the ed and wd were generated during the mature and high mature stages 6 both the source rocks of e 2 s 3 and e 2 s 4 strata could contribute to the gas reservoirs of e 2 s 3 and e 2 s 1 in the west depression sapropelic gases in east depression were generated by e 2 s 3 source rocks while the other gases reservoired in the e 2 s 3 e 3 s 1 and e 3 d strata are probably sourced from the source rock strata of e 2 s 3 and e 3 s 1 2

primary production in the glacial north atlantic and north pacific oceans the conditions controlling primary production are very different in the modern north atlantic and north pacific oceans1 a difference that is reflected in the composition of diatom fossils in surface sediments by contrast i report here evidence that during the last glacial interval the diatom assemblage and by extrapolation the primary production was very similar in the two regions the modern analogues of these assemblages occur in sediments of baffin bay and the sea of okhotsk both highly productive seas where ice is present i infer that during the last glacial interval plankton biomass was at least as high as it is today in the north atlantic and was as much as an order of magnitude higher in the north pacific the glacial assemblage occurs in lithologies dominated by ice rafted detritus which is generally believed to indicate the presence of icebergs2 6 i hypothesize that the presence of numerous icebergs possibly associated with sea ice supported high production by physical mechanisms such as turbulent mixing and enhanced density stratification and or biogeochemical ones such as supply of major or trace nutrients

hvnsr survey in historical downtown l aquila central italy site resonance properties vs subsoil model abstract this paper presents and discusses the results of a detailed seismic noise survey carried out in historical downtown l aquila after the earthquake of 6 apr 2009 m w 6 3 seismic noise data were interpreted through numerical simulations with the support of a subsoil model characterised by four main units from the top to the bottom i soft soils anthropogenic filling material and terra rossa ii l aquila breccia iii l aquila pelite and sand and iv the meso cenozoic carbonate bedrock the hvnsr analysis permitted the identification of two peaks f0 and f1 nearly everywhere f0 0 4 0 7 hz is due to the superposition of l aquila pelite and sand on the carbonate bedrock at 200 300 m below ground level f1 3 15 hz is caused by shallower impedance contrasts due to 3 20 m thick soft sediments overlying l aquila breccia and by the weathering profile of l aquila breccia a numerical simulation was carried out for three different models characterised by i lithology lateral variation in the first 100 m of thickness due to the substitution from north to south of l aquila breccia with l aquila pelite and sand ii the thickness variation of soft top soil onto l aquila breccia and iii the presence of a weathered layer in the upper part of the l aquila breccia the numerical simulation results fit the experimental seismic noise data a spatial correlation between areal distributions of severe damages with that of f1 resonance frequency is found so it follows that the severe damage during the l aquila earthquake of 6 apr 2009 could have been caused by the seismic local effect of the soft top soil and the weathering profile of l aquila breccia

origin and consequences of cyclic ice rafting in the northeast atlantic ocean during the past 130 000 years deep sea sediment cores recovered from the northeast atlantic ocean were examined in order to elucidate the influence of the earth s orbital parameters on major ice rafting analyses of coarse grained ice rafted debris and planktonic foraminifers revealed a strong reaction to the precession signal since 130 000 yr b p dropstone layers have been deposited each half period of a precessional cycle 11 000 1000 yr ice rafting occurs during times of winter minimum summer maximum insolation and summer minimum winter maximum insolation in the first case high summer insolation forces meltwater discharge from the ice sheets into the polar seas which subsequently enhances formation of sea ice during the winter in the second case growth of continental ice enhances iceberg production which also leads to a salinity reduction of surface seawater both situations result in a southward penetration of polar water thus the marine record of dropstones documents ice rafting not only during weichselian stades but also during cold events within interstades the regularity of ice rafting yields a useful framework to calibrate and elucidate climatic changes not only in the region of the north atlantic ocean but also in remote areas such as the pacific ocean and the antarctic

surface water temperature salinity and density changes in the northeast atlantic during the last 45 000 years heinrich events deep water formation and climatic rebounds we developed a new method to calculate sea surface salinities sss and densities ssd from planktonic foraminiferal 18o and sea surface temperatures sst as determined from planktonic foraminiferal species abundances sst sss and ssd records were calculated for the last 45 000 years for biogeochemical oceanic flux study bofs cores 5k and 8k recovered from the northeast atlantic the strongest feature is the dramatic drop in all three parameters during the heinrich ice rafting events we modelled the possibility of deepwater formation in die northeast atlantic from the ssd records by assuming that the surface waters at our sites cooled as they flowed further north comparison with modelled north atlantic deepwater densities indicates that there could have been periods of deepwater formation between 45 000 and 30 000 14c years b p interrupted by iceberg meltwater input of heinrich event 3 and 4 at 27 000 and 38 000 14c years b p and during the holocene no amount of cooling in the northeast atlantic between 30 000 and 13 000 years could cause deep water to form because of the low salinities resulting from the high meltwater inputs from icebergs our records indicate that after each heinrich event there were periods of climatic rebound with milder conditions persisting for up to 2000 years as indicated by the presence of warmer and more saline water masses after these warm periods conditions returned to average glacial levels these short term cold and warm episodes in the northeast atlantic are superimposed on the general trend towards colder conditions of the last glacial maximum lgm heinrich event 1 appears to be unique as it occurs as insolation rose and was coeval with the initial melting of the fennoscandian ice sheet we propose that meltwater input of heinrich event 1 significantly reduced north atlantic deep water formation reducing the heat exchange between the low and high latitudes thus delaying deglaciation by about 1500 radiocarbon years 2000 calendar years

coupling basin infill history and mammal biochronology in a pleistocene intramontane basin the case of western l aquila basin central apennines italy the western l aquila basin recorded in quaternary times two well distinguished phases of intramontane basin fill concomitant with uplift of central apennines and characterized by diverse large mammal assemblages the first phase was dominated by alluvial fan and lacustrine palustrine sedimentation respectively gelasian and calabrian in age that took place within an internally drained fault controlled hydrographic system a late villafranchian earliest galerian large mammal assemblage approximately 1 3e1 1 ma pertains to this phase and includes mammuthus meridionalis stephanorhinus etruscus and the large cervid arvernoceros aff a giulii the second phase of filling middle pleistocene to holocene in age is dominated by fluvial sedimentation which is related to a through going fluvial system developed after the emptying of the former lake a middle galerian large mammal assemblage approximately 600 ka comes from the oldest deposits of this phase biochronological data help date steps of geological and morphological evolution in an intramontane setting and permit to temporally constrain the major change in local hydrography and sedimentation at the early middle pleistocene transition this change was likely forced by an increment of uplift rates which is well recorded along the axial range and peripheral belts of the apennines 2011 elsevier ltd and inqua

evidence for changes in the north atlantic deep water linked to meltwater surges during the heinrich events abstract deep sea sediment records from north atlantic cores 40 n 55 n provide evidence of several massive iceberg discharges known as heinrich events during the last glacial period high resolution benthic 18 o and 13 c records from north atlantic sediment cores were used to monitor the impact of heinrich events on thermohaline circulation and to estimate the sensitivity of deep oceanic circulation to changes in freshwater input to the north atlantic surface waters our data indicate that major rearrangements of deep water masses were directly associated with these massive iceberg discharges to trace in detail the deep water conditions in the north atlantic benthic 13 c values in several cores were used to generate time slices before during and after heinrich event 4 dated at 35 ka bp although north atlantic deep water continued to form during the oxygen isotope stage 3 at 37 ka bp deep circulation was characterized by an increased incursion of deep waters of southern origin which reduced the 13 c composition of north atlantic deep waters particularly in the eastern atlantic basin north atlantic deep water production was reduced during heinrich layer 4 hl4 at 35 ka bp synchronously with the changes in the surface water hydrology deep convection processes may have occurred in areas not affected by the salinity decrease soon after hl4 33 ka bp the 13 c distribution was similar to that before the event similarly a rapid return to initial 13 c values was observed at the end of the most clearly defined heinrich events hl5 hl4 and hl1 comparison between deep circulation patterns corresponding to hl4 the last glacial maximum and heinrich event 1 indicates that each of these periods was characterized by a different circulation state associated with changes in convection sites

a 50 000 year record of climate oscillations from florida and its temporal correlation with the heinrich events oscillations of pinus pine pollen in a 50 000 year sequence from lake tulane florida indicate that there were major vegetation shifts during the last glacial cycle episodes of abundant pinus populations indicate a climate that was more wet than intervening phases dominated by quercus oak and ambrosia type ragweed and marsh elder the pinus episodes seem to be temporally correlated with the north atlantic heinrich events which were massive periodic advances of ice streams from the eastern margin of the laurentide ice sheet possible links between the tulane pinus and heinrich events include hemispheric cooling the influences of mississippi meltwater on sea surface temperatures in the gulf of mexico and the effects of north atlantic thermohaline circulation on currents in the gulf

iceberg discharges into the north atlantic on millennial time scales during the last glaciation high resolution studies of north atlantic deep sea cores demonstrate that prominent increases in iceberg calving recurred at intervals of 2000 to 3000 years much more frequently than the 7000 to 10 000 year pacing of massive ice discharges associated with heinrich events the calving cycles correlate with warm cold oscillations called dansgaard oeschger events in greenland ice cores each cycle records synchronous discharges of ice from different sources and the cycles are decoupled from sea surface temperatures these findings point to a mechanism operating within the atmosphere that caused rapid oscillations in air temperatures above greenland and in calving from more than one ice sheet

disseminated phosphorus in oceanic sediments a review abstract the content of disseminated phosphorus in sediments of the world oceans fluctuates between 0 01 and 4 36 terrigenous and hemipelagic sediments contain on average about 0 07 phosphorus higher concentrations are characteristic of sediments enriched in iron and manganese hydroxides or bone detritus and phosphoritic material the general features of the phosphorus distribution in surface sediments depend on the ratio of continental runoff area to basin area which diminishes from the atlantic to the indian and pacific areas the relative extent of the nearshore phosphorus rich zone contracts whereas that of the pelagic phosphorus rich zone widens in the transition from the atlantic through the indian to the pacific areas the distribution of phosphorus in vertical sections of sediments gives some evidence of the diagenetic mobilisation of phosphorus and its partial loss to bottom water the rate of phosphorus accumulation in oceanic sediments is evaluated as between 10 g cm 2 k y 1 the bulk mass of phosphorus is accumulated in marginal zones of the oceans

early diagenesis of organic matter in peru continental margin sediments phosphorite precipitation abstract pore water chemistry total dissolved co 2 nh 4 no 3 no 2 po 4 si oh 4 ca mg fe mn so 4 h 2 s and f and titration alkalinity solid phase chemistry c org p org c tot n tot f si opal and s ii and sediment characteristics porosity dry bulk density and formation factors were determined on a centimeter scale spacing in the upper 20 40 cm of sediments under intense upwelling areas on the peru continental shelf these data demonstrate that carbonate fluorapatite cfa is precipitating from pore waters in the upper few centimeters of a gelatinous mud with high organic carbon content up to 20 c org very high porosity 0 96 ml cm 3 and very low dry bulk density 3 dissolved phosphate concentrations at the sediment water interface range from 20 to 100 m orders of magnitude higher than bottom water concentrations and much higher than predicted from regeneration of organic matter the mechanism of this interfacial phosphate release is unclear but is apparently uncoupled from carbon and nitrogen metabolism and thus may be linked either to dissolution of fish debris or to the presence of a microbial mat in surficial sediments fluoride is incorporated into cfa by diffusion from the overlying seawater and carbonate ions are provided from pore water alkalinity magnesium concentrations in this reaction zone are not significantly different from those of seawater suggesting that magnesium depletion is not a necessary prerequisite for cfa precipitation the environment of precipitation is interface linked rather than driven by organic diagenesis of phosphorus deeper in the sediment most of the cores display a wide range of diagenetic characteristics below the immediate interfacial region but almost all show the precipitation signature near the interface this interface linked early diagenetic porewater environment for the precipitation of cfa explains many of the geochemical characteristics of phosphorites and provides a testable model to compare the modern phosphogenic analog with ancient phosphorite deposits two of the cores display very high solid phase phosphorus and fluoride contents reflecting the presence of apparently modern pelletal apatites

the seismic response of two dimensional sedimentary deposits with large vertical velocity gradients an extension of the aki larner technique to vertically inhomogeneous media is presented so that vertical velocity gradients may be taken into account in two dimensional models only sh waves are considered here but the theory is valid for p and sv waves as well this method is applied to investigate the seismic response of two dimensional sedimentary deposits with large velocity gradients three different cases are considered a shallow high contrast valley a deep high contrast valley and a deep low contrast valley in each case a comparison is performed with the results of a two dimensional model taking into account only homogeneous sediments and a one dimensional model taking into account the vertical inhomogeneity of sediments the presence of a large velocity gradient does not change a lot the qualitative behavior of a two dimensional deposit local surface waves and or two dimensional resonance patterns are observed as in the case of homogeneous sediments nevertheless the surface waves are much more dispersive with lower phase and group velocities and larger amplitudes only very deep valleys give rise to the development of two dimensional resonance on the other hand the amplifications obtained in such deposits may reach much larger values than those predicted with either two dimensional homogeneous models or one dimensional inhomogeneous models since these results have been obtained for realistic values of valley geometrical and mechanical considerations they should find some application in earthquake engineering or seismic microzonation studies

dysaerobic conditions during heinrich events 4 and 5 evidence from phosphorus distribution in a north atlantic deep sea core abstract reactive phosphorus undergoes diagenetic transformation once transferred into marine sediments the degree of regeneration and redistribution of phosphorus depends on early diagenetic and environmental conditions which may be linked to larger scale phenomena such as bottom water circulation water column ventilation and organic carbon flux phosphorus phases of the

oxygen index as an indicator of early organic maturity abstract most maturity indices can be used during catagenesis and metagenesis but there are only a few indicators to show the degree of organic maturation within the diagenesis zone a previous study has already demonstrated that the oxygen index oi measured by rock eval analysis provides reliable information about the early evolution stages of coals and type iii kerogens the main purpose of this study was to investigate the conditions of oi application in both natural and artificial evolution the results of experiments presented here revealed that the accuracy of oi in estimating the evolution level depended on the amount and chemical composition of the organic matter natural series of low rank coals showed oi to be a valuable rank parameter not only during diagenesis but in early catagenesis also oi appeared to be a sensitive indicator during both simulated diagenesis and the entire oil window for gas prone coal having a substantial humic contribution to its precursor material in contrast the oi of oil prone coal and coal with mixed oil and gas potential proved to be a valuable rank parameter only up to the beginning of the oil window though it could be utilized successfully for describing depth profiles in organic rich intervals of early maturity in wells its use in determining natural maturity was restricted by the organic richness of rocks as well as by the effect of the mineral matrix providing humic material is present oi can be used to follow the artificial thermal maturation of type ii kerogen in the absence of mineral matrix

seismic expression of channel outcrops offset stacked versus amalgamated channel systems abstract forward seismic models of two seismic scale outcrops of different style channel systems have been made to investigate their seismic signature these two outcrops illustrate the geometric end members of channel stacking architecture in response to low and high accommodation space the eocene nohut tepe channel system of the elazig basin in eastern turkey was deposited in an area of high accommodation resulting in an aggradational geometrical offset stacking of channels up against a slope the eocene ainsa ii channel system of the tremp pamplona basin in the spanish pyrenees was deposited in an area of low accommodation resulting in a tabular compound sheet geometry with amalgamated channel bodies separated by clay drapes depth models were drawn from outcrop photos and converted to impedance models by assigning acoustic impedance properties to the sand filled channels and surrounding and interbedded mud and clay layers these were the input for the forward seismic models which constructed various frequency synthetic seismic sections of the two outcrops analysis of the outcrop synthetic seismic identified three distinct reflection configurations type i is characterised by a strong black peak and white trough reflection which is due to a discrete channel body type ii is characterised by multiple offset time stepped black peak reflections that are underlain by one continuous strong white trough reflection which is due to offset stacked channel bodies type iii is characterised by strong black peaks which onlap an underlying continuous white trough reflection caused by the lateral amalgamation of channel bodies these three types of reflection configurations observed on the outcrop synthetic seismic can also be found on actual seismic from channelised turbidite systems which aids in interpreting channel stacking architecture accommodation space prediction and depositional styles from the actual seismic data channel stacking architecture is clearly an important aspect which needs to be considered when making channel system interpretations based on seismic data

resolution of ambiguities of seismic refraction traveltime curves ambiguities are inherent in seismic refraction traveltime curves based on first arrivals recorded from a multi layered medium even for reversed profiles inflections of traveltime curves caused by the onset of arrivals from successively deeper horizons frequently cannot be delineated from those caused by lateral geologic changes in addition the secondary arrivals which may represent essential portions of a traveltime curve are not available numerous inversions having different geologic implications are possible ambiguities may be resolved by using multiple shotpoints for each spread and combining their individual first arrival traveltime curves to yield a consistent set of curves for each refracting horizon a set of rules applies for combining individual traveltime curves based on reversed split and offset profile configurations the combined curves lend themselves to a unique inversion

sedimentary and tectonic evolution of plio pleistocene alluvial and lacustrine deposits of fucino basin central italy abstract the fucino basin was the greatest lake of the central italy which was completely drained at the end of 19th century the basin is an intramontane half graben filled by plio quaternary alluvial and lacustrine deposits located in the central part of the apennines chain which was formed in upper pliocene and in quaternary time by the extensional tectonic activity the analysis of the geological surface data allows the definition of several stratigraphic units grouped in lower units and upper units the lower units upper pliocene are exposed along the northern and north eastern basin margins they consist of open to marginal lacustrine deposits breccia deposits and fluvial deposits the upper units lower pliocene holocene consist of interbedded marginal lacustrine deposits and fluvial deposits thick coarse grained fan delta deposits are interfingered at the foot of the main relief with fluvial lacustrine deposits most of the thickness of the lacustrine sequences more than 1000 m thick is buried below the central part of the fucino plain the basin is bounded by e w wsw ene and nw se fault systems velino magnola fault e w and tremonti celano aielli fault wsw ene and s potito celano fault nw se in the north the trasacco fault the pescina celano fault and the serrone fault nw se in the south east the geometry and kinematic indicators of these faults indicate normal or oblique movements the study of industrial seismic profiles across the fucino basin gives a clear picture of the subsurface basin geometry the basin shows triangular shaped basin fill geometry with the maximum deposits thickness toward the main east boundary fault zones that dip south westward serrone fault trasacco fault pescina celano fault on the basis of geological surface data borehole stratigraphy and seismic data analysis it is possible to recognize and to correlate sedimentary and seismic facies the bottom of the basin is well recognized in the seismic lines available from the good and continuous signals of the top of meso cenozoic carbonate rocks the shape of sedimentary bodies indicates that the filling of the basin was mainly controlled by normal slip along the nw se boundary faults in fact the continental deposits are frequently in on lap contact over the carbonate substratum several disconformable contacts occurred during the sedimentary evolution of the basin the main faults with antithetic and synthetic fault planes displace the whole sedimentary sequence up to the surface indicating a recent faults activity 1915 avezzano earthquake ms 7 0 the stratigraphic and tectonic setting of the fucino basin and neighboring areas indicates that the extensional tectonic events have had an important role in driving the structural sedimentary evolution of the plio quaternary deposits the geometry of the depositional bodies of the fault planes and their relationships indicate that the fucino basin was formed as a half graben type structure during plio quaternary extensional events some internal complexities are probably related to the fold and thrust structures of the apenninic orogeny formed in messinian time in this area and to a different activity timing of the e w and wsw ene fault systems and the nw se fault systems we believe based on the similarity of the surface characteristics that the structural setting of the fucino basin can be extrapolated to the other great intramontane basins in central italy e g rieti l aquila sulmona sora isernia basins

the 2009 l aquila central italy mw6 3 earthquake main shock and aftershocks 1 a m w 6 3 earthquake struck on april 6 2009 the abruzzi region central italy producing vast damage in the l aquila town and surroundings in this paper we present the location and geometry of the fault system as obtained by the analysis of main shock and aftershocks recorded by permanent and temporary networks the distribution of aftershocks 712 selected events with m l 2 3 and 20 with m l 4 0 defines a complex 40 km long nw trending extensional structure the main shock fault segment extends for 15 18 km and dips at 45 to the sw between 10 and 2 km depth the extent of aftershocks coincides with the surface trace of the paganica fault a poorly known normal fault that after the event has been quoted to accommodate the extension of the area we observe a migration of seismicity to the north on an echelon fault that can rupture in future large earthquakes

patterns of ice rafted detritus in the glacial north atlantic 40 55 n the observation by heinrich 1988 that during the last glacial period much of the input of ice rafted detritus to the north atlantic sediments may have occurred as a succession of catastrophic events rekindled interest on the history of the northern ice sheets over the last glacial period in this paper we present a rapid method to study the distribution of these events both in space and time using whole core low field magnetic susceptibility we report on approximately 20 cores covering the last 150 to 250 kyr well defined patterns of ice rafted detritus appear during periods of large continental ice sheet extent although these are not always associated within their maxima most of the events may be traced across the north atlantic ocean for the six most recent heinrich layers hl two distinct patterns exist hl1 hl2 hl4 hl5 are distributed along the northern boundary of the glacial polar front over most of the north atlantic between 40 and 50 n hl3 is more restricted to the central and eastern part of the northern atlantic the nd sr isotopic composition of the material constituting different heinrich events indicates the different provenance of the two patterns hl3 has a typical scandinavia arctic icelandic young crust signature and the others have a large component of northern quebec and northern west greenland old crust material these isotopic results obtained on core su 9008 from the north american basin are in agreement with the study by jantschik and huon 1992 who used k ar dating of silt and clay size fractions of an eastern basin core me 68 89 these data confirm the large spatial scale of these events and the enormous amount of ice rafted detritus they represent

biomarker evidence for heinrich events the so called heinrich layers found in north atlantic sediments have been attributed to quasi periodic discharges of armadas of icebergs originating from the laurentide ice sheet using the distribution of biomarkers in a sediment core bofs 5k we have attempted to provide more information about their origin and the effect of the heinrich events on oceanic circulation and the climatic system estimates of sea surface temperature changes via u3k7 measurements show that the surface ocean underwent significant cooling during the events probably as a result of incoming iceberg meltwater the low sea temperatures and the rapid variation in the accumulation of chlorophyll derived pigments suggest that the events provoked a major change in oceanographic conditions which may have affected the thermohaline circulation in the atlantic ocean within the most recent layers we have also found vanadyl alkyl porphyrins and aryl isoprenoid hydrocarbons diagenetic products of photosynthetic pig ments chlorophylls and carotenoids respectively these components are not expected to occur in late quaternary sediments so their presence demonstrates a contribution to the layers of ancient organic rich sedimentary material of continental origin the presence of vanadyl porphyrins and absence of their nickel counterparts and the distributional features of the aryl isoprenoids e g presence of the c40 reduced carotenoid isorenieratane of green sulphur bacterial origin indicate the existence of anoxic conditions in the photic zone of a marine water column in the original depositional setting of the contributed ancient sediment these results suggest that it should be possible using a biomarker correla tion approach to determine the source area of the ancient sediment eroded by the icebergs copyright 1997 elsevier science ltd

effects of topography on seismic wave propagation an example from northern taiwan topography influences ground motion and in general increases the amplitude of shaking at mountain tops and ridges whereas valleys have reduced ground motions as is observed from data recorded during and after real earthquakes and from numerical simulations however recent publications have focused mainly on the implications for ground motion in the mountainous regions themselves whereas the impact on surrounding low lying areas has received less attention here we develop a new spectral element mesh implementation to accommodate realistic topography as well as the complex shape of the taipei sedimentary basin which is located close to the central mountain range in northern taiwan spectral element numerical simulations indicate that high resolution topography can change peak ground velocity pgv values in mountainous areas by 50 compared to a half space response we further demonstrate that large scale topography can affect the propagation of seismic waves in nearby areas for example if a shallow earthquake occurs in the i lan region of taiwan the central mountain range will significantly scatter the surface waves and will in turn reduce the amplitude of ground motion in the taipei basin however as the hypocenter moves deeper topography scatters body waves which subsequently propagate as surface waves into the basin these waves continue to interact with the basin and the surrounding mountains finally resulting in complex amplification patterns in taipei city with an overall pgv increase of more than 50 for realistic subduction zone earthquake scenarios off the northeast coast of taiwan the effects of topography on ground motion in both the mountains and the taipei basin vary and depend on the rupture process the complex interactions that can occur between mountains and surrounding areas especially sedimentary basins illustrate the fact that topography should be taken into account when assessing seismic hazard

global ice volume fluctuations north atlantic ice rafting events and deep ocean circulation changes between 130 and 70 ka multiproxy data from north atlantic deep sea sediment core neap18k provide a detailed record of climate through oxygen isotope stage ois 5 seven distinct large scale episodes of ice rafting c25 c19 were identified between 126 and 70 ka global ice volume reconstructions based on high resolution benthic 18 o records indicate that major ice rafting events were not confined to ice volume maxima at ois 5d and 5b but also occurred during periods of ice sheet growth and disintegration however iceberg discharges were restricted to times when sea levels were 40 65 m below present values ice rafting episode c25 the first large scale cooling of mid atlantic surface waters after the last interglacial occurred during the gradual buildup of continental ice sheets at the ois 5e 5d transition major ice sheet collapses allied to ice rafting events c24 and c21 were associated with rapid sea level increases of 20 and 40 m respectively suborbital climatic fluctuations in the neap18k sedimentary record denoted by prominent 7 5 4 5 and 3 k y cyclicities appear to correlate with both greenland atmospheric temperatures and changes in thermohaline circulation patterns inferred from benthic 13 c values and hence provide clear evidence of a highly interconnected north atlantic climatic regime during ois 5

geometry and evolution of a fault controlled quaternary basin by means of tdem and single station ambient vibration surveys the example of the 2009 l aquila earthquake area central italy we applied a joint survey approach integrating time domain electromagnetic soundings and single station ambient vibration surveys in the middle aterno valley mav an intermontane basin in central italy and the locus of the 2009 l aquila earthquake by imaging the buried interface between the infilling deposits and the top of the pre quaternary bedrock we reveal the 3 d basin geometry and gain insights into the long term basin evolution we reconstruct a complex subsurface architecture characterized by three main depocenters separated by thresholds basin infill thickness varies from 200 300 m in the north to more than 450 m to the southeast our subsurface model suggests a strong structural control on the architecture of the basin and highlights that the mav experienced considerable modifications in its architecture over time the buried shape of the mav suggests a recent and still ongoing predominant tectonic control by the nw se trending paganica san demetrio fault system psdfs which cross cuts older ca ene and nne trending extensional faults furthermore we postulate that the present day arrangement of the psdfs is the result of the linkage of two previously isolated fault segments we provide constraints on the location of the southeastern boundary of the psdfs defining an overall 19 km long fault system this allows for earthquakes larger than m6 5 this study emphasizes the benefit of combining two easily deployable geophysical methods for reconstructing the 3 d geometry of a tectonically controlled basin our joint approach provided us with a consistent match between these two independent estimations of the basin substratum depth within 15

thermohaline instability in the north atlantic during meltwater events stable isotope and ice rafted detritus records from core so75 26kl portuguese margin a benthic isotope record has been measured for core so75 26kl from the upper portuguese margin 1099 m water depth to monitor the response of thermohaline overturn in the north atlantic during heinrich events evaluating benthic 18o in ts diagrams in conjunction with equilibrium c fractionation implies that advection of mediterranean outflow water mow to the upper portuguese margin was significantly reduced during the last glacial 15 compared to 30 today the benthic isotope record along core so75 26kl therefore primarily monitors variability of glacial north atlantic conveyor circulation the 14c accelerator mass spectrometry ages of 13 54 07 and 20 46 12 ka for two ice rafted detritus ird layers in the upper core section and an interpolated age of 36 1 ka for a third ird layer deeper in the core are in the range of published 14c ages for heinrich events h1 h2 and h4 marked depletion of benthic 13c by 0 7 1 1 during the heinrich events suggests reduced thermohaline overturn in the north atlantic during these events close similarity between meltwater patterns inferred from planktonic 18o at site 609 and ventilation patterns inferred from benthic 13c in core so75 26kl implies coupling between thermohaline overturn and surface forcing as is also suggested by ocean circulation models benthic 13c starts to decrease 1 5 2 5 kyr before heinrich events hl and h4 fully increased values are reached 1 5 3 kyr after the events indicating a successive slowdown of thermohaline circulation well before the events and resumption of the conveyor s full strength well after the events benthic 13c changes in the course of the heinrich events show subtle maxima and minima suggesting oscillatory behavior of thermohaline circulation a distinct feature of thermohaline instability in numerical models inferrred gradual spin up of thermohaline circulation after hl and h4 is in contrast to abrupt wanning in the north atlantic region that is indicated by sudden increases in greenland ice core 18o and in marine faunal records from the northern north atlantic from this we infer that thermohaline circulation can explain only in part the rapid climatic oscillations seen in glacial sections of the greenland ice core record

role of the thermohaline circulation in the abrupt warming after heinrich events evidence of rapid climate oscillations during the last glacial period has been identified in climate records from greenland ice cores1 2 and ocean sediments in the north atlantic3 4 these records show that periods of gradual cooling are terminated by abrupt warming events5 with the coldest periods coinciding with the deposition of ice rafted debris so called heinrich events throughout the north atlantic heinrich events are thought to be a signature of massive iceberg discharges owing to collapse of the laurentide ice sheet bond et al 5 have proposed that the decrease in meltwater flux following collapse and retreat of the ice sheet enhanced the ocean s thermohaline circulation6 thereby increasing advection of heat from the tropics and giving rise to abrupt climate warming here we test this idea using a simple ocean model coupled to a model of a periodically surging ice sheet we find that massive discharges of icebergs first stop the thermohaline circulation because of the consequent freshwater influx cooling the north atlantic region this is followed by a rapid restart of the circulation leading to abrupt warming thus our model can reproduce the qualitative features of the climate oscillations seen in the ice core and ocean records

the phosphorus cycle phosphogenesis and marine phosphate rich deposits abstract phosphorus in the form of phosphate is an essential nutrient and energy carrier on many different levels of life and a key element in mediating between living and lifeless parts of the biosphere one of the most important aspects of the phosphorus cycle is its vital role in governing productivity thereby interacting with the exogenic part of the carbon cycle which in turn is important in regulating earth s climate phosphorus is a prime element to be traced in earth s history because it allows for the reconstruction of long term feedback mechanisms between climate environment and ecology and of global change as such marine sedimentary phosphate deposits are particularly suited to study aspects of the phosphorus cycle because in the case of ubiquity their origin may result from a general acceleration of the global phosphorus cycle sources of sedimentary phosphate are microbial breakdown of buried organic matter and redox driven phosphate desorption from iron and manganese oxyhydroxides dissolved sea water phosphate represents an additional source which may become important in the formation of phosphatic hardgrounds the main locus of phosphogenesis is near the sediment water interface but phosphogenesis also occurs at greater sediment depths current induced winnowing and transport processes along the sea floor concentrate phosphate precipitates into deposits which exhibit internal stratification patterns typical for the prevailing hydraulic energy regime in a sequence stratigraphic context phosphate deposits preferentially occur along marine or maximum flooding surfaces consequent sedimentary reworking may result in the transfer of phosphates to highstand or lowstand deposits bio chemical weathering on continents represents the most significant source of bioavailable phosphorus this implies that long term changes in marine phosphorus levels and with these changes in marine ecology productivity rates and ratios of exported carbonate carbon and organic carbon are a response to changes in continental weathering rates a compilation of marine sedimentary phosphorus burial rates for the last 160 myr suggests that natural variations have occurred that span one order of magnitude for the late jurassic cretaceous and most of the paleogene the phosphorus cycle appears to have been accelerated in times of climate warming which was most likely due to the spreading of zones of humid climate and more intense continental weathering in the neogene the phosphorus cycle appears to have responded to changes in glacially induced weathering this suggests that uniform interpretations with respect to the emplacement of major phosphorite deposits should be treated with caution integrated analyses of the sedimentary and biogeochemical context of phosphorite occurrences may help to identify paleoenvironmental conditions as well as to improve our understanding of periods of enhanced phosphate accumulation periods which were usually characterized by steep gradients in the development of climate and environment with regard to the complexity of feedback mechanisms between the phosphorus cycle and the biosphere the present day input rates of phosphate into the world s oceans should be of great concern they are more than doubled by anthropogenic means and affect ecological systems on a rapidly increasing scale

mineralogical kar and 87sr 86sr isotope studies of holocene and late glacial sediments in a deep sea core from the northeast atlantic ocean abstract fine grained silicate fractions m and 2 16 m of holocene and late glacial sediments in a deep sea core from the northeast atlantic ocean 47 30 n 19 30 w have been analysed by x ray diffraction k ar and sr isotopic methods during the holocene the k ar apparent ages and the 87 sr 86 sr ratios of the clay size minerals averaged 436 22 13 ma and 0 72638 0 00051 respectively the k ar values essentially reflect the high 40 ar contribution from the detrital mica in binary smectite mica mixtures where smectite is a low potassium and tertiary quaternary component higher k ar age value up to 569 124 112 ma are determined for the coarser 2 16 m fractions which contain in addition to mica other detrital k bearing phases amphibole k feldspar and plagioclase an important change in the mineralogical composition and the k ar ages is displayed by the silicate fractions of a thin layer of ice rafted detritus located at the termination of the last glaciation their k ar apparent ages increase to 773 933 ma and correspond to an increase of the detrital supply amphibole mica and feldspar from the precambrian terrains of north america or greenland and a dilution or a decrease of the input of basaltic material smectite oligoclase from the region of iceland

sources of fine sized organic matter in north atlantic heinrich layers δ13c and δ15n tracers organic carbon oc and total nitrogen tn concentrations and stable isotope ratios d13c d15n of fine 50 m size fractions of deep sea sediments from the central north atlantic were employed to identify changes in sources of organic matter over the past 50 ka bp ambient glacial sediments are characterised by values that reflect mixtures of marine and terrestrial inputs averages 1s oc tn 7 6 0 8 d13c 22 8 1 0 d15n 5 5 0 6 d13c oc and tn concentrations shift to higher values during the holocene indicating a gradual decrease of fine terrigenous supply to the north atlantic the unchanged d15n record between last glacial and holocene stages indicates that the central north atlantic region remained oligotrophic at least during the past 50 ka bp but additional studies are required to support this result in terms of nitrogen oceanic budget during the phases of enhanced ice rafted detrital supply corresponding to prominent heinrich events hl1 hl2 hl4 and hl5 fine sized sedimentary organic matter has lower oc and tn concentrations contrasting sharply with those of ambient glacial sediments lower d13c down to 28 and d15n down to 1 6 values and high oc tn ratios up to 14 7 1 1 are found for hl1 hl2 and with lesser extent for hl4 these values reflect enhanced detrital supply originating from poorly differentiated soil horizons that characterise periglacial climate conditions and from organic matter bearing rock sources of the underlying geological basement during hl5 only the d13c offset records the input of fine size ice rafted organic matter gradually changing soil development conditions during the time interval covering hl5 to hl1 marine isotope stages 5 to 2 as well as varying erosion levels have been hypothesized on the basis of constant d13c increasing oc tn and decreasing d15n values

the 2009 central italy earthquake seen through 0 5 myr long tectonic history of the l aquila faults system abstract on 6 april 2009 a mw 6 3 earthquake struck l aquila and dozens of neighbouring villages abruzzo central italy causing 308 deaths and with thousands injured within italian seismicity this was the strongest event since 1980 irpinia mw 6 9 and the first located so close to a large city since 1908 messina mw 7 3 consistent data from an integrated approach including stratigraphy geomorphology tephrochronology and paleoseismology have allowed us to identify a 19 km long hitherto poorly known structure as being responsible for this earthquake paganica san demetrio fault system psdfs the fingerprinting of four well dated tephra layers and a detailed outline of the geomorphological and stratigraphic setting have provided the basis for assessing the behaviour of the psdfs since its early activity here dated at least ca 500 ka to the present the slip rate of the structure calculated over different time windows has fluctuated slightly ca 0 5 mm yr paleoseismological analyses revealed the traces of the last surface faulting events thus we unambiguously recognise the offset associated with the mw 6 7 earthquake of 1703 which was previously related to other conterminous structures along with an older comparable strong event speculatively ascribed to an event purely known as the ad 801 central apennine earthquake this study shows that a long term to short term integrated approach is crucial in seismic hazard evaluation especially when dealing with fault systems that are difficult to trace geomorphically despite being capable of generating 2009 like earthquakes or even stronger events when conterminous structures are also involved

authigenic apatite formation and burial in sediments from non upwelling continental margin environments abstract evidence for precipitation of authigenic carbonate fluorapatite cfa in long island sound and mississippi delta sediments suggests that formation of cfa is not restricted to environments of active coastal upwelling we present porewater data suggestive of cfa formation in both these areas application of a sequential leaching procedure designed specifically to separate authigenic carbonate fluorapatite from other phosphorus containing phases including detrital apatite of igneous or metamorphic origin provides strong supporting evidence for authigenic apatite formation in these sediments the size of the authigenic apatite reservoir increases with depth indicating continued formation of cfa during early diagenesis this depth increase is mirrored by a decrease in solid phase organic p at both sites suggesting that cfa is forming at the expense of organic p mass balance considerations application of diagenetic models to interstitial water nutrient data and the saturation state of the interstitial water are consistent with this interpretation diagenetic redistribution of phosphorus among the different solid phase reservoirs is observed at both sites and results in near perfect retention of p by these sediments over the depth intervals sampled formation of cfa in continental margins which do not conform to the classically defined regions of phosphorite formation renders cfa a quantitatively more important sink than has previously been recognized including this reservoir as a newly identified sink for reactive p in the ocean the residence time of p in the modern ocean must be revised downward the implication for ancient oceans of cfa formation in continental margin sediments other than phosphorites is that phosphorite formation may be less a representation of episodicity in removal of reactive p from the oceans than of localized concentration of cfa in phosphatic sediments by secondary physical processes

phosphorus distribution c n p ratios and δ13coc in arctic temperate and tropical coastal sediments tools for characterizing bulk sedimentary organic matter abstract onshore offshore trends in phosphorus p organic carbon oc and total nitrogen tn concentration p distribution elemental organic c n p ratios and stable carbon isotopic composition of oc 13 c oc of surficial sediments are presented from three river dominated coastal regimes the mackenzie river beaufort shelf in the canadian arctic the mississippi delta and louisiana shelf in the temperate gulf of mexico and the tropical amazon shelf these parameters measured in surficial sediments from the three sites are used to assess changes in the importance of terrestrial and marine organic matter sources to sediments as a function of distance from the locus of riverine discharge trends in elemental ratio data from the arctic transect and a portion of the gulf of mexico transects can be explained in terms of a two end member mixture of terrestrial and marine phytodetritus in the arctic transect covariation of organic c p ratios with 13 c oc is consistent with a two end member mixture of terrestrial and marine organic matter a similar relationship between c p ratios and 13 c oc is not evident in gulf of mexico or amazon shelf sediments at these sites the two end member model fails to explain the data adequately the most striking feature of the onshore offshore trends in elemental oc op and oc tn ratios is the occurrence of low ratios in sediments from deep water stations in the gulf of mexico and all stations on the amazon shelf resulting from p and n enrichments exceeding the redfield ratio for marine plankton three explanations are discussed to account for these low ratios 1 the dominance of refractory op and on compounds in the residuum of degraded organic matter 2 differential sorption of op and n compounds regardless of lability on the surfaces of the fine grained sediments characteristic of these sites and 3 a dominance of bacterial biomass or components derived from bacterial biomass elemental ratios and 13 c oc signatures indicate that differential sorption may be most important in the deep water gulf of mexico sites in contrast elemental ratios and 13 c oc on the amazon shelf are most consistent with a sedimentary organic matter pool dominated by bacterial biomass or derivative substances

fault and basin depocentre migration over the last 2 ma in the l aquila 2009 earthquake region central italian apennines abstract morphological stratigraphical and structural investigations integrated with palaeomagnetic and tephrostratigraphic studies and 40 ar 39 ar measurements allowed us to define the quaternary tectonic sedimentary evolution of the epicentral area of the l aquila 2009 earthquake m w 6 3 this area roughly matches the paganica san demetrio castelnuovo psc intermountain basin filled by a fluvio lacustrine succession that is variously deformed by normal faults at its early stage early pleistocene ca 2 ma the basin hosted a lake that was characterised by whitish carbonate silt and mud deposition towards the end of the early pleistocene this was partly filled by a south eastward prograding deltaic system the south easternmost portion of the deltaic system was successively abandoned and eroded while sedimentation of a braided river system developed in a smaller area westwards before 780 ka this fluvio lacustrine system the lower psc syntheme ended and the area underwent erosional and pedogenic processes these processes continued up to 460 ka with the onset of fluvial gravel and volcanic rich silty sand deposition over a narrow area of the south western psc basin an earlier unit of the upper psc syntheme early middle pleistocene around 460 ka when most of this area was again subjected to denudational processes the sedimentation migrated into the previously exposed north western area of the psc basin where fluvial alluvial sediments were deposited between ca 460 ka and ca 350 ka a later unit of the upper psc syntheme between ca 350 ka and the present the sedimentation continued uninterrupted in a slight westwards restricted area of the psc basin upper late psc syntheme the significant contraction of the basin the shifting of its depocentre the variation in its geometry and in the spatial distributions and thicknesses of the units constituting the lower upper and late psc synthemes provide evidence for strong tectonic control this resulted in progressive reduction of the activity of the south easternmost tectonic structures and parallel migration of the fault activity on the westernmost structures in this perspective the fault system responsible for the l aquila 2009 earthquake can be seen as the most recent expression of a long lasting westwards polarised process of tectonic activity transfer

phosphorus in sediments of the amazon river and estuary implications for the global flux of phosphorus to the sea abstract the distribution of various forms of p in suspended and depositional bank sediments of the amazon river and bottom sediments of the mixing and freshwater portions of the amazon estuary and shelf have been determined using a modified sequential extraction method forms of p distinguished are p associated with ferric oxides hydroxides fe p organic p org p p extracted with acetate buffer at ph 4 acet p and detrital apatite detr p results indicate that there is a distinct drop in fe p org p and total p after deposition of suspended sediment on the banks of the river similar results are found for sediment deposited on the freshwater portion river channel bottom of the continental shelf sediment deposited on estuarine portions of the shelf also shows a significant drop in total p due mostly to a drop in org p no appreciable change in acet p was found between river suspended sediments and those of either the river banks or of the estuarine shelf an inverse correlation is found for all sediments between concentrations of fe p and detr p because of the association of detrital apatite with the coarser fractions of the sediments and fe p with the finer fractions these results suggest that considerable amounts of p are added to the oceans by the bacterial decomposition of river transported organic matter and by the desorption of p from iron oxides hydroxides some desorption from al silicates may also occur the organic p is released to interstitial solution during early diagenesis and this p may be adsorbed by fe oxides in the sediment during frequent resuspension events the fe oxides are carried to the overlying water where the p is desorbed and thereby released to solution based on our amazon results the total global p flux to the oceans by rivers may be more than three times that carried only in solution by the rivers further work is needed on other river systems to check these preliminary results

sequential extraction and analysis of phosphorus in marine sediments streamlining of the sedex procedure we streamlined the five step sedex sedimentary extraction procedure for characterizing sedimentary phosphorus to a four step procedure we combined extraction of adsorbed and oxide associated pools into a single step retaining steps for authigenic detrital and organic p in addition we used automated spectrophotometric flow injection analysis fia to determine p concentrations rather than traditional spectrophotometric techniques we decreased our total extraction and analytical time from 12 d for 24 replicate samples to 5 d without sacrificing our geo chemical objectives detection limits or analytical reproducibility

climatic and hydrologic oscillations in the owens lake basin and adjacent sierra nevada california oxygen isotope and total inorganic carbon values of cored sediments from the owens lake basin california indicate that owens lake overflowed most of the time between 52 500 and 12 500 carbon 14 14 c years before present b p owens lake desiccated during or after heinrich event h1 and was hydrologically closed during heinrich event h2 the magnetic susceptibility and organic carbon content of cored sediments indicate that about 19 sierra nevada glaciations occurred between 52 500 and 23 500 14 c years b p most of the glacial advances were accompanied by decreases in the amount of discharge reaching owens lake comparison of the timing of glaciation with the lithic record of north atlantic core v23 81 indicates that the number of mountain glacial cycles and the number of north atlantic lithic events were about equal between 39 000 and 23 500 14 c years b p

high resolution seismic reflection exploration for evaluating the seismic hazard in a plio quaternary intermontane basin l aquila downtown central italy abstract on april 6 2009 a mw 6 1 earthquake struck the plio quaternary intermontane l aquila scoppito basin in central italy causing severe damage to l aquila historical downtown and surroundings which were affected by notable site effects previous work has suggested that different site effects may be related to the complex subsurface geologic architecture given the variable thickness and lithology of l aquila scoppito basin filling deposits on top of which the city was built to improve the 3d geological model of l aquila downtown for seismic site response evaluation and to estimate the seismic hazard of possible buried active normal faults a multitask project was carried out consisting mainly of the integration of surface geology geological subsurface datasets and geophysical surveys data were interpreted with the aim of creating and building a detailed stratigraphic and tectonic model for the plio quaternary cover of the continental basin and the buried morphology of the meso cenozoic bedrock we discuss and interpret the results concerning a 1 km long high resolution seismic reflection profile and refraction tomography integrated with stratigraphy from deep and shallow boreholes the results allowed the reconstruction of the plio quaternary succession below l aquila downtown the plio quaternary basin depocentre is located in a minor nnw sse graben an extensional structure within the main regional graben that borders l aquila scoppito basin finally data interpretation allowed us to define the subsoil geological model of the study area to evidence the recent activity of several faults and to reconstruct the plio quaternary tectono stratigraphic evolution of the basin together the data are useful to evaluate the seismic hazard of cities with great cultural heritage of central italy such as the case study of l aquila downtown

millennial scale iceberg discharges in the irminger basin during the last glacial period relationship with the heinrich events and environmental settings high resolution records of coarse lithic content and oxygen isotope have been obtained in a piston core from the irminger basin the last glacial period is characterized by numerous periods of increased iceberg discharges originating partly from iceland and corresponding to millennial scale instabilities of the coastal ice sheets and ice shelves in the nordic area a comparison with midlatitude sediment cores shows that ice rafted material corresponding to the heinrich events was deposited synchronously from 40 to 60 n there are thus two oscillating systems every 5 10 kyr massive iceberg armadas are released from large continental ice caps whereas more frequent instabilities of the coastal ice sheets in the high latitude regions occur every 1 2 3 8 kyr at the time of the heinrich events the synchroneity of the response from all the northern hemisphere ice sheets attests the existence of strong interactions between the two systems

phosphorus accumulation in marine sediments and the oceanic phosphorus cycle ideas about key factors in the oceanic mass balance of dissolved reactive phosphate have changed substantially i present an integrated overview of these here with an emphasis on evaluating the burial sinks for p and defining areas needing further research the major source of reactive p to the ocean is river input reactive p is delivered to the oceanic sediment water interface primarily in particulate organic matter p scavenged by hydrothermal iron rich oxyhydroxide particles with uptake in proportion to deep water phosphate concentrations represents a substantially smaller flux to the sediment water interface diagenetic transformations are important influences on the form of reactive p burial in marine sediments p burial occurs with organic carbon burial and as p associated with iron rich oxyhydroxide particles and coatings formation of authigenic p rich phases presumably apatite at the expense of organic p and oxide associated p is significant in open ocean marine sediments the authigenic p sink may represent a substantially larger portion of the sedimentary burial than indicated by previous estimates focused on p burial in organic rich continental margin sediments

new insights into the onset and evolution of the central apennine extensional intermontane basins based on the tectonically active l aquila basin central italy study of the tectonically active l aquila basin offers new insights into both the creation of the extensional intermontane basins of the central apennines of italy and their tectono sedimentary evolution through time the combination of large mammal remains ostracods molluscs mousterian tools and 14 c dating allows better definition of the onset and stratigraphic evolution of the l aquila basin interpretation of a seismic reflection profile and well log data allow evaluation of the subsurface setting of this sedimentary basin and its tectono sedimentary evolution the occurrence of a wedge shaped seismic unit at the base of the basin sedimentary succession defines the first phase of basin fill during a late piacenzian gelasian synrift stage activity along the main fault of the extensional fault system responsible for the onset and subsequent development of the western sector of the l aquila basin l aquila scoppito subbasin migrated from southwest to northeast reaching the presently active mount pettino normal fault only in the late pleistocene holocene the onset of sedimentation in the l aquila basin was synchronous with the onset in the tiberino basin and so the idea that these extensional gsa bulletin month month 2017 v 129 no intermontane basins become progressively younger from the tyrrhenian toward the adriatic side of the central apennines is rejected in the northern and central apen nines only two major syndepositional ex tensional domains can be recognized a late miocene rifting area which includes all the late miocene extensional basins in tuscany and a late pliocene to earliest pleistocene rifting area which possibly includes all the intermontane basins from the tiberino basin to the sulmona basin the different time gaps between compressional and exten sional deformation at any given locality in the central apennines could indicate a partial decoupling of processes responsible for the migration of shortening and extension toward the foreland diachroneity between the eastward migration of shortening in the foreland and extension in the inner part of the orogen supports the notion that the central apennines were created as a result of a partially decoupled collision zone study of the onset of the central apennine extensional intermontane basins together with their seismic activity indicates that the central apennine postorogenic extensional domain represents an archive of 3 m y of continued crustal extension these findings help to refine models of the long term extensional rate of the central apennines and they provide a basis for more reliable seismotectonic models for one of the most seismically active sectors of the central mediterranean area

a micromorphological index of soil development for the quaternary geology research abstract profile development indices of harden harden j w 1982 a quantitative index of soil development from field examples from a chronosequence in central california geoderma 285 1 98 and ferrari and magaldi ferrari g magaldi d 1983 significato ed applicazioni della paleopedologia nella stratigrafia del quaternario boll mus civ st nat verona 10 315 340 have shown their utility for comparative dating of some paleosols during geomorphological and geological surveys in italy and other countries pedostratigraphic methods have been commonly applied to soil profiles formed in continental formations unfortunately buried and relict paleosols are very scarce or badly preserved in some areas of italy due to past and recent tectonic activity and to strong human impact dating back to prehistoric times in order to use relict paleosols for correct chronostratigraphic interpretation of relict paleosols and in order to correlate them with old landscape forms for the reconstruction of quaternary sequences a new micromorphological index misodi for assessing soil development and degree of weathering was devised the index was tested in the extensional tectonic basin of l aquila scoppito abruzzi central italy where some chronostratigraphic information is available results demonstrate that there is a good relationship between presumed relative age of paleosols and degree of weathering and pedogenesis in b and b c horizons as assessed by this index the index has the potential to be adapted for application to other paleosol types in other countries

recrystallization of dolomite evidence from the monterey formation miocene california dolomites from the upper calcareous siliceous member of the miocene monterey formation exposed west of santa barbara california were analysed for geochemical isotopic and crystallographic variation the data clearly document the progressive recrystallization of dolomite during burial diagenesis in marine pore fluids recrystallization is recognized by the following compositional and crystallographic variations dolomites have decreasing 18o and 13c compositions decreasing sr contents and increasing mg contents with increasing burial depths and temperatures from east to west in the study area 18o values vary from 5 3 in the east to 5 5 pdb in the west and are interpreted to reflect the greater extent and higher temperature of dolomite recrystallization in the west 13c values correlate with 18o and decrease from 13 6 in the east to 8 7 pdb in the west sr concentrations correlate positively with 18o values and decrease from a mean of 750 ppm in the east to a mean of 250 ppm in the west mol mgco3 values inversely correlate with 18o values and increase from a minimum of 41 0 in the east to a maximum of 51 4 in the west rietveld refinements of powder x ray diffraction data indicate that the more recrystallized dolomites have more contracted unit cells and increased cation ordering the fraction of the ca sites in the dolomites that are occupied by ca atoms increases slightly with the approach to stoichiometry the fraction of the mg sites occupied by mg atoms strongly correlates with mol mgco3 even in early diagenetic non stoichiometric dolomites there is little substitution of mg in ca sites during recrystallization the amount of mg substituting for ca in ca sites decreases even further most of the disorder in the least recrystallized non stoichiometric dolomites is related to substitution of excess ca on mg sites

evidence for massive discharges of icebergs into the north atlantic ocean during the last glacial period sediments in the north atlantic ocean contain a series of layers that are rich in ice rafted debris and unusually poor in foraminifera1 here we present evidence that the most recent six of these heinrich layers deposited between 14 000 and 70 000 years ago record marked decreases in sea surface temperature and salinity decreases in the flux of planktonic foraminifera to the sediments and short lived massive discharges of icebergs originating in eastern canada the path of the icebergs clearly marked by the presence of ice rafted detrital carbonate can be traced for more than 3 000 km a remarkable distance attesting to extreme cooling of surface waters and enormous amounts of drifting ice the cause of these extreme events is puzzling they may reflect repeated rapid advances of the laurentide ice sheet perhaps associated with reductions in air temperatures yet temperature records from greenland ice cores appear to exhibit only a weak corresponding signal moreover the 5 10 000 yr intervals between the events are inconsistent with milankovitch orbital periodicities raising the question of what the ultimate cause of the postulated cooling may have been

benthic phosphorus regeneration net primary production and ocean anoxia a model of the coupled marine biogeochemical cycles of carbon and phosphorus we examine the relationships between ocean ventilation primary production water column anoxia and benthic regeneration of phosphorus using a mass balance model of the coupled marine biogeochemical cycles of carbon c and phosphorus p the elemental cycles are coupled via the redfield c p ratio of marine phytoplankton and the c p ratio of organic matter preserved in marine sediments the model assumes that on geologic timescales net primary production in the oceans is limited by the upwelling of dissolved phosphorus to the photic zone the model incorporates the dependence on bottom water oxygenation of the regeneration of nutrient phosphorus from particulate matter deposited at the water sediment interface evidence from marine and lacustrine settings modern and ancient demonstrates that sedimentary burial of phosphorus associated with organic matter and ferric oxyhydroxides decreases when bottom water anoxia dysoxia expands steady state simulations show that a reduction in the rate of thermohaline circulation or a decrease of the oxygen content of downwelling water masses intensifies water column anoxia dysoxia and at the same time increases surface water productivity the first effect reflects the declining supply of oxygen to the deeper parts of the ocean the second effect is caused by the enhanced benthic regeneration of phosphorus from organic matter and ferric oxyhydroxides sedimentary burial of organic carbon and authigenic calcium phosphate mineral francolite on the other hand is promoted by reduced ocean ventilation according to the model global scale anoxia dysoxia leads to a more efficient recycling of reactive phosphorus within the ocean system consequently higher rates of primary production and organic carbon burial can be achieved even when the continental supply of reactive phosphorus to the oceans remains unchanged

changes in east atlantic deepwater circulation over the last 30 000 years eight time slice reconstructions using 95 epibenthic 13c records eight time slices were reconstructed to trace the distribution of east atlantic deepwater and intermediate water masses over the last 30 000 years our results show that there have been three distinct modes of deepwater circulation near the stage 3 2 boundary the origin of north atlantic deep water nadw was similar to today mode 1 however after late stage 3 the source region of the nadw end member shifted from the norwegian greenland sea to areas south of iceland mode 2 a reduced nadw flow persisted during the last glacial maximum with constant preformed 13c values the nutrient content of nadw increased markedly near the azores fracture zone from north to south probably because of the mixing of upwelled antarctic bottom water aabw from below which then advected with much higher flux rates into the northeast atlantic later the spread of glacial meltwater over the north atlantic led to a marked short term ventilation minimum below 1800 m about 13 500 14c years ago mode 3 the formation of nadw recommenced abruptly north of iceland 12 800 12 500 years ago and reached a volume approaching that of the holocene in the younger dryas 10 800 10 350 years b p another short term shutdown of deepwater formation followed between 10 200 and 9 600 years b p linked to a further major meltwater pulse into the atlantic each renewal of deepwater formation led to a marked release of fossil co2 from the ocean the likely cause of the contemporaneous 14c plateaus over the last 9000 years deepwater circulation varied little from today apart from a slight increase in aabw about 7000 14c years ago it is also shown that the oxygenated mediterranean outflow varied largely independent of the variations in deepwater circulation over the last 30 000 years

sedimentary record of rapid climatic variability in the north atlantic ocean during the last glacial cycle comparisons between a greenland ice core isotopic record and marine sediment grey level records of the north atlantic ocean show that rapid temperature variations witnessed by the ice core dansgaard oeschger events during the last glacial period can also be detected in marine sediments this shows that the resolution obtained in marine cores can be sufficiently high to record rapid climatic fluctuations several spectral analyses of those grey level marine records consistently indicate that significative fluctuations of the climatic response exist with periodicities of 5 to 1 kyr in addition to orbital forcing these high frequencies are close to those predicted by various dynamic ocean models

soft sediment deformation structures interpreted as seismites in lacustrine sediments of the prebetic zone se spain and their potential use as indicators of earthquake magnitudes during the late miocene lacustrine formations of late miocene age in the prebetic area se spain show several types of deformational structures that are interpreted as seismites they are present in both marginal and deep lacustrine facies seismites formed in marginal lake environments comprise sand dikes pillows and intruded and fractured gravels in deep lacustrine facies the seismites are represented by pseudonodules mushroom like silts protruding into laminites mixed layers disturbed varved lamination and loop bedding the measured orientations of these structures are consistent with the orientations of the main faults limiting the basins showing that their origin is clearly related to the tectonic stress field that prevailed in the region during the late miocene the magnitudes of the earthquakes that deformed the sediments have been estimated after published data from both ancient and recent lake deposits accumulated in tectonic active regions elsewhere a rank of earthquake magnitudes with two end members i e the lowest magnitudes recorded by loop bedding in laminites and the highest magnitudes represented by intruded and fractured gravels is proposed

european climatic response to millennial scale changes in the atmosphere ocean system during the last glacial period abstract pollen foraminifer dinocyst and coarse lithic high resolution analyses and 18 o measurements have been carried out for the last glacial section of marine core md95 2042 located near the southwestern margin of the iberian peninsula the pollen data indicate a high frequency of vegetational changes on the adjacent continent during this period suggesting a climatic variability very similar to that of the dansgaard oeschger cycles recorded by the greenland ice cores the detailed direct correlation of the terrestrial and marine proxy data from core md95 2042 indicates a three phase pattern of heinrich events in land and ocean environments the first and last phases of the h5 and h4 events are characterized by a mild and humid climate in southwestern europe probably associated with the european origin of the ice rafted detritus the middle phase exhibits a cold and dry climate in iberia linked with the maximum input of ice rafted detritus this phase seems to correspond with the laurentide ice sheet surges between the heinrich events several cold and dry periods on land are correlated with stades of the dansgaard oeschger cycles the impact of the dansgaard oeschger stades in southwestern europe seems to be preferentially connected to the cold winter air masses reaching this mid latitude region

evidence from southern ocean sediments for the effect of north atlantic deep water flux on climate evidence from southern ocean sediments for the effect of north atlantic deep water flux on climate

evidence for enhanced phosphorus regeneration from marine sediments overlain by oxygen depleted waters phosphorus regeneration and burial fluxes determined from in situ benthic flux chamber and solid phase measurements at sites on the californian continental margin peruvian continental slope north carolina continental slope and from the santa monica basin california are reported comparison of these sites indicates that o2 depleted bottomwaters enhance p regeneration from sediments diminishing overall phosphorus burial efficiency based on these observations a positive feedback linking ocean anoxia enhanced benthic phosphorus regeneration and marine productivity is proposed on shorter timescales these results also suggest that o2 depletion in coastal regions caused by eutrophication may enhance p regeneration from sediments thereby providing additional p necessary for increased biological productivity

zooming in on heinrich layers theories explaining the origin of the abrupt massive discharges of ice rafted detritus ird into the glacial north atlantic the heinrich layers hls generally point to the laurentide ice sheet as the sole source of these events until it was found that the irds also originated from icelandic and european ice sheets bond and lotti 1995 snoeckx et al 1999 grousset et al 2000 this apparent contradiction must be reconciled as it raises fundamental questions about the mechanism s of hl origin we have analyzed two 12 cm thick hls in an ultrahigh resolution mode 1 2 century intervals in a mid atlantic ridge piston core the 18o record n pachyderma left coiling reveals strong excursions induced by the melting of the icebergs these excursions are associated with a strong decrease in the amount of planktic foraminafersand with a 3 c cooling of the surface waters counts of coarse detrital grains reveal that ird are deposited according to a typical sequence 1 volcanic glass 2 quartz and feldspars 3 detrital carbonate that implies a chronology in the melting of the differentpan atlantic ice sheets sr and nd isotopic composition confirm that in both heinrich layers h1 and h2 precursor ird came from first europe iceland followed then by laurentide derived ird an internal cyclicity can be identified during h1 and h2 about four to six major abrupt discharges occurred roughly on a century timescale the 13c and 15n records reveal that dominant inputs of continent derived organic matter are associated with ird within the hls hiding the plankton productivity signal