return of the coral reef hypothesis basin to shelf partitioning of caco3 and its effect on atmospheric co2 differences in the rate of coral reef carbonate deposition from the pleistocene to the holocene may account for the quaternary variation of atmospheric co sub 2 volumes of carbonate associated with holocene reefs require an average deposition rate of 2 0 times 10 sup 13 mol yr for the past 5 ka in light of combined riverine mid ocean ridge and ground water fluxes of calcium to the oceans of 2 3 times 10 sub 13 mol yr the current flux of calcium carbonate to pelagic sediments must be far below the pleistocene average of 1 2 times 10 sub 13 mol yr the authors suggest that sea level change shifts the locus of carbonate deposition from the deep sea to the shelves as the normal glacial interglacial pattern of deposition of quaternary global carbonates to assess the impact of these changes on atmospheric co sub 2 a simple numerical simulation of the global carbon cycle was developed atmospheric co sub 2 as well as calcite saturation depth and sediment responses to these carbonate deposition changes are examined atmospheric co sub 2 changes close to those observed in the vostok ice core approximately 80 ppm co sub 2 for the quaternary are observed as well as the approximate depth changes in percent carbonate of sediments measured in themore pacific ocean over the same time interval less

hydrological characteristics of the drainage system beneath a surging glacier a rare combination of natural circumstances permits assessment of current theories on water flow beneath glaciers outburst floods from the subglacial lake grimsvotn in iceland took place before during and after surging of skei ararjokull the glacier beneath which the outburst floods drain the observable drainage patterns associated with these floods show the different nature of the basal water conduit system of the glacier during surge and non surge phases during surge conditions basal water is dispersed slowly across the bed in a distributed drainage system but when the glacier is not surging water is transported rapidly through a system of tunnels

clastic dykes in east belgium evidence for upper pleistocene strong earthquakes west of the lower rhine rift segment fissures of seismic origin are described from terrace deposits of the meuse river in the liege maastricht area west of the lower rhine roer rift segment though associated with hydroplastic deformation of the sediments they are not injection structures they are interpreted as tension cracks resulting from local deformation of susceptible layers inferred to be due to cyclic loading by seismic waves the fissures have been tilled afterwards from above by vertically laminated sands and silts the distribution of the fissured areas and the special features of some ground cracks suggest that they could be linked to more than one earthquake between 650 and l00 ka bp by comparison with liquefaction phenomena described in relation to actual earthquakes the failure of the meuse terrace deposits could have been produced by seismic events of m l 6 5

hierarchy of high frequency orbital cycles in cretaceous carbonate platform strata abstract lower cretaceous valanginian hauterivian carbonate platform strata which are well exposed in the matese mountains of the southern apennines italy have been analyzed on a microstratigraphic cm scale to exemplify the high frequency cyclic nature of the mesozoic shallow water sedimentation in southern italy based on the vertical organization of lithofacies and their early diagenetic signature 46 metre scale cycles are recognized these elementary cycles are hierarchically organized into groups bundles and superbundles the elementary cycles are prevalently formed by subtidal deposits and show emersion related features at the top suggesting repeated sea level fluctuations the number of elementary cycles compared to time as constrained by biostratigraphy and their grouping into sets implying higher order complexity in the environmental oscillation suggest an orbital control on sedimentation spectral analysis of recurrent thickness in stratal features defines and quantifies the cyclicity which is characterized by lithofacies thickness periodicities of 1271 391 159 124 and 69 cm linear correlation of the relative ratio set rrs of these periodicities with the corresponding rrs of the orbital perturbation periodicities shows that 1271 and 391 cm fit the 404 220 and 94 890 year cycles of early cretaceous orbital eccentricity 159 and 124 cm fit the 49 010 and 38 030 year cycles of the earth s axial obliquity whereas 69 cm corresponds to the precession periodicity thus the san lorenzello section required not less than 1 6 ma to form at an average rate of 26 mm ka each 400 ka cycle can be viewed as a depositional sequence in which sequence boundaries maximum flooding surfaces and system tract equivalents have been recognized the microstratigraphic approach is very promising for understanding the fine structure of climate related environmental fluctuation recorded by the 3000 m thick carbonate platform successions of the southern apennines over a time span of about 150 ma upper triassic upper cretaceous and for deriving a more precise chronostratigraphy for global correlation

deglacial changes in dust flux in the eastern equatorial pacific abstract atmospheric dust levels may play important roles in feedbacks linking continental source areas tropical convection marine productivity and global climate these feedbacks appear to be particularly significant in the tropical pacific where variations in local convection and productivity have been demonstrated to have impacts on climate at higher latitudes modeling of past dust levels and related feedbacks has been limited however by a paucity of observational data in this study we present a temporal and spatial survey of dust fluxes to the eastern equatorial pacific over the past 30 kyr glacial and holocene fluxes of 232th a proxy for continental material were calculated by normalization to 230th from a north south transect of cores along 110 w between 3 s and 7 n odp sites 848 853 fluxes were 30 100 higher during the last glacial suggesting increased dustiness in both hemispheres during the glacial period in both time periods dust fluxes decrease towards the south reflecting scavenging of northern hemisphere dust by precipitation at the itcz the holocene meridional dust flux gradient between 7 n and 3 s is characterized by a steep drop in dust levels at the southern edge of the modern range of the itcz while the gradient is shallower and more nearly linear during the last glacial this change may indicate that the glacial itcz in this region was a less effective barrier to inter hemispheric dust transport most likely due to a decrease in convective intensity and precipitation during the last glacial alternatively the change in gradient may be explained by increased variability in the location of the glacial itcz our data do not appear to require a mean southerly displacement of the glacial itcz as suggested by the results of other studies

activity along the osning thrust in central europe during the lateglacial ice sheet and lithosphere interactions abstract the osning thrust is one of the major fault systems in central europe with a length of approximately 115 km it underwent a polyphase tectonic evolution in the mesozoic that ranged from extensional movements in the jurassic to reverse faulting and thrusting during inversion in the late cretaceous a series of complex metre scale faults and related fold structures are developed within the upper pleistocene alluvial aeolian complex of the upper senne 1 km away from the thrust the faults dip towards the north and show offsets in a range of several decimetres growth strata indicate a two fold evolution of the structures the faults began as normal faults and were later transformed into reverse faults which resulted in the formation of small scale inversion structures with a typical harpoon shape glaciotectonics can be ruled out as the driving mechanism for these structures because new optically stimulated luminescence osl ages imply that the sedimentary succession was deposited during the late pleistocene between 29 3 2 9 ka and 13 1 1 5 ka at which time the ice margin was much further to the northeast we believe the inversion structures were caused by movement on the osning thrust due to generation of a forebulge of the late pleistocene weichselian ice sheet this led to normal faulting as a consequence of extension in the forebulge area during glaciation the osl ages for the normal fault related growth strata are in a range of 16 13 ka later reverse movements occurred during deglaciation due to the n s directed compressional stress field in northern germany numerical simulations of the deglaciation seismicity point to seismic events with a thrust mechanism in the study area between 15 5 and 12 3 ka bp although normal faulting is also possible in this time period numerous soft sediment deformation structures imply that movement on the osning thrust caused earthquakes with a significant magnitude in the autumn of 1612 an earthquake took place in this area it is very likely that this event is related to background seismicity on this fault although movement due to the influence of the ongoing glacial rebound in fennoscandia is also possible

evidence from seismites for glacio isostatically induced crustal faulting in front of an advancing land ice mass rugen island sw baltic sea abstract it is hitherto commonly thought that earthquakes triggered by geologically rapid changes in the pressure caused by the fluctuating extent of thick land ice masses occur exclusively during ice retreat our study of deformed sediment layers within an undeformed glaciolacustrine and glaciofluvial succession exposed in a coastal cliff on rugen island south western baltic sea challenges this widespread idea based on their structural and deformational features the layers under investigation are interpreted as seismites which formed as a result of seismically induced liquefaction the stratigraphic context aided by optically stimulated luminescence osl dating indicate that the documented seismites must have formed shortly before the front of the pleistocene scandinavian ice sheet reached the study area during the last glacial maximum thus during a stage of ice advance this implies that the flexural isostatic response of the earth s crust as a consequence of the ice load during ice advance was accompanied by earthquakes probably due to local re activation of pre existing faults the crustal response to an increasing ice load was consequently less gradual than previous studies about glaciation related tectonics suggest

application of a chemical leach technique for estimating labile particulate aluminum iron and manganese in the columbia river plume and coastal waters off oregon and washington in order to determine the total concentration of bioavailable trace metals in seawater measurement of both the dissolved and labile particulate fractions is necessary comparison of labile particulate metal concentrations from various researchers is limited because of differing definitions of the fraction that is potentially available to phytoplankton on a time frame of generations a comparison experiment was conducted on coastal and riverine suspended particulate matter to determine the difference between several commonly used techniques that operationally define the labile particulate trace metal fraction furthermore we compared two leach techniques for surface transect samples from within the columbia river plume and water offshore of oregon and washington united states the particulate trace metal concentration in the leachate was determined by high resolution inductively coupled plasma mass spectrometry from this comparison one chemical leach was chosen to best define the labile particulate fraction of al fe and mn a weak acid leach 25 acetic acid at ph 2 with a mild reducing agent 0 02 m hydroxylamine hydrochloride and a short heating step 10 min 90 95 c this leach was applied to three surface transects within the columbia river plume these coastal waters were found to be rich in labile particulate trace metals that are directly delivered from the columbia river and indirectly supplied via resuspension from upwelling over a broad continental shelf

progressive proglacial to subglacial deformation and syntectonic sedimentation at the margins of the mid pleistocene british ice sheet evidence from north norfolk uk abstract detailed analysis and interpretation of the stratigraphy and structures developed within polydeformed sediments exposed in the coastal section between west runton and sheringham eastern england has allowed the characterisation of the glacitectonic signature associated with the advance of a major mid pleistocene anglian ice sheet the sequence of pre glacial deposits and glacial sediments laid down during earlier southerly directed ice advances d1 d2 is deformed and disrupted by an ice advance from the west southwest that marks a major change in ice flow dynamics in northern east anglia the simplest interpretation of this deformation event d3 is in terms of a progressive proglacial to subglacial deformation model proglacial deformation occurred in advance of the ice margin and was dominated by thrusting positive topographic features which developed above the propagating thrusts controlled sediment dispersal patterns within outwash sandur leading to the formation of small sub basins between these morainic ridges the accretion of the wedge shaped proglacial thrust moraines to the main push moraine formed at the margin of the advancing glacier may have temporarily stalled forward motion of the ice thrusting and large scale folding associated with ice marginal deformation led to the stacking of material excavated from further up ice onto the stoss side of these accreted thrust related moraines that allowed the glacier to override the obstruction subglacial deformation was highly variable in its style and intensity ranging from heterogeneous folding and thrusting through to more pervasive ductile shearing associated with the formation of a subglacial shear zone the thickness and complexity of this shear zone increases up ice where it is characterised by a thick glacitectonic melange the pore water content of the deforming sediments controlled the pattern of deformation within the shear zone however an increase in the efficiency of the drainage system towards the front of the glacier would have led to a rapid thinning of this water enhanced zone of ductile shear evidence from north norfolk suggests that zones of preferential pore water flow within the glacier bed are a major controlling factor on the location of the subglacial shear zone consequently the bulk of the forward motion of the glacier may not be accommodated by shearing within the sediments immediately below its base but occur at a deeper level within the deforming bed

mineralogical composition and potential sources of dust fallout deposits in kuwait northern arabian gulf abstract detailed mineralogical investigations of dust fallout deposits collected at eleven locations in kuwait during april 1979 march 1980 were carried out the mineralogy of five size fractions medium sand fine sand very fine sand coarse silt and clay was determined occurrence frequency and potential sources of the mineral grains that form the various size fractions are discussed and the gross mineralogical composition of the dust fallout calculated it was found that dust fallout deposited in kuwait is quartzitic calcareous sandy silt and is mostly derived from the dry mesopotamian flood plain in the middle and south of iraq the occurrence of sand size particles is attributed to pick up from local recent surface deposits

palaeobathymetric reconstruction of peritidal carbonates late barremian urgonian sequences of provence se france abstract peritidal platform carbonates of late barremian age early cretaceous cropping out in the marseille region provence se france tend to be arranged stratigraphically in deepening up or shallowing up sequences seven facies types lithofacies were defined in the studied stratigraphic interval ranging from supratidal to shallow subtidal settings there is a good correspondence between the inferred relative water depth of facies and their average bed thickness cumulative thickness of facies types expresses quantitatively their palaeobathymetric range and provides an estimate of their average water depth calculations show that the palaeobathymetry of supratidal intertidal facies types is from 0 to 40 cm i e a pertaining to a palaeotidal microtidal range the average palaeobathymetry of rudist facies ascribed to subtidal settings fluctuates between 40 cm and nearly 160 cm measuring a large number of beds belonging to both shallowing up and deepening up sequences and averaging the results appear relevant to minimise the effect of compaction pressure solution and synsedimentary progressive or abrupt changes in accommodation which are expected to modify bed thickness and its original palaeobathymetric significance the method proposed here has a good potential for palaeobathymetric reconstruction of ancient peritidal carbonates

quaternary geology of eastern germany saxony saxon anhalt south brandenburg thuringia type area of the elsterian and saalian stages in europe abstract the characteristic feature of the quaternary geology of eastern germany location map fig 1 is a sequence of more than 50 horizons and complexes of glacial laminated clays tills glaciofluvial sediments and periglacial river gravels gelifluction sheets alluvium loess facies in the period between the younger tertiary and the first elsterian continental glaciation at least four gravel terraces were built up under cold climate conditions the youngest of these gravel bodies lacks scandinavian rocks and is interbedded with elsterian glaciolacustrine deposits pre elsterian temperate periods have been recorded at a number of places i e zeuchfeld untermassfeld voigtstedt sussenborn two major ice advances with additional minor oscillations have been identified of elsterian and saalian ages complete eemian and holsteinian sequences are represented showing vegetational development through each interglacial cycle cool temperate warm cool the weichselian glacial stage in eastern germany is represented by thick periglacial sedimentation including gravels gelifluction sheets alluvium debris covers and loess within these sediments is a wide variety of glaciotectonic structures and periglacial soil structures including classical involutions and ice wedge casts an outline of the present state of knowledge of the quaternary of eastern germany is given in tables 1 3 while table 4 presents a stratigraphical comparison with the neighbouring regions and countries the palaeogeography of the region during the periods of the european continental glaciation is depicted in fig 2

fine grained carbonates in nearly closed reef environments mataiva and takapoto atolls central pacific ocean abstract the nature origin and mode of accumulation of fine grained carbonate sediments have been investigated in the nearly enclosed lagoons of two french polynesian atolls mataiva and takapoto the fine sized fraction 20 m is substantially higher in amount 70 of the total fine sediments on average than the mud portion and may increase volumetrically 90 99 in some localities aragonite is the predominant mineral present 90 of the total calcium carbonate the fines appear to be mainly skeletally derived the silt fraction includes coral and molluscan detritus sponge chips juvenile benthic foraminiferans and other biogenic debris the mud is chiefly composed of aggregated nanograins ascidian spicules skeletal nanograins coral generated mainly and coccoliths a minor part of the mud is certainly of non skeletal origin some portion of freely deposited fines fill cavities or are attached upon sand grain surfaces they are associated with scattered inorganic precipitates and contribute to the formation of micrite envelopes and aggradation of host grains such a process is highly significant in the total carbonate budget of the reef the fine carbonate sediments result directly from the biological disintegration of nearby buildups mainly through the boring activity of sponges and lithophagid molluscs we suggest that the authigenic mud sized crystallites are controlled in their precipitation both by carbonate supersaturation and anoxic conditions seasonally affecting the interstitial sediment waters enclosed atoll lagoons are relatively self governing environments of deposition which are influenced by long term quiescent water situations rather than by rare catastrophic events

upper cretaceous ramp limestones from the sorrento peninsula southern apennines italy micro and macrofossil associations and their significance in the depositional sequences abstract the upper cretaceous limestones of the sorrento peninsula are primarily characterized by wackestone packstone with benthic foraminifers thaumatoporellaceans and aeolisaccus sp and by rudist floatstones rudists in growth position are rare most of them appear toppled and locally oriented but not reworked in some cases they form small bouquets no more than 30 cm thick the successions analyzed in the sorrento peninsula encompass a variety of facies representative of inner shelf environments in a ramp like depositional setting on the basis of lithologic and sedimentologic characteristics and on a qualitative analysis of the biofacies three major facies associations have been recognized corresponding to a intertidal silty sand flats and shallow lagoons b subtidal mobile foraminiferal sand sheets c subtidal rudist dwelt sand plain in the lower part of the successions periodic more or less prolonged emersions subaqueous with fresh brackish waters or subaerial exposure are documented the upper part of each succession lacks any emersion evidence submarine exposure surfaces are testified by firmground related features the periodic influence of high energy regimes some storm related events is documented by wave and cross laminations hcs and the lack of fine sediments lithofacies are arranged in depositional cycles that may correspond to individual beds the boundaries of the depositional cycles show evidence of subaerial or submarine exposures the nature and position of these discontinuity surfaces in the successions provide an important clue to interpretation in terms of both depositional environment and vertical evolution the increase in thickness of the depositional cycles and the gradual change from peritidal shallow subtidal cycles to dominantly subtidal cycles document an increase in the amount of accommodation space which resulted from a long term rise in relative sea level a detailed study of benthic associations micro and macrofauna has been carried out in order to identify accurately further signs of periodicity contained within the successions as a whole these upper cretaceous limestones are abundantly fossiliferous with only a moderately diverse fauna there are no significant differences in terms of species the assemblages simply reflecting differences in abundance of the same species taphonomic studies of rudist rich beds permit seven major shell bed types to be distinguished six main foraminiferal assemblages have been detected and the distribution and relative abundance of the species have been examined within the environments inferred through facies analysis the taphonomic data and the foraminiferal assemblage abundance and diversity have been compared with lithologic and sedimentologic data in order to elucidate their distribution within depositional cycles and throughout the successions the successions show little up section changes in lithology and in taxonomic composition of the foraminiferal assemblages it is therefore difficult to establish a paleoenvironmental trend independent of the rudist shell concentrations which do change up section we noticed an overall increase in thickness and abundance of the shell beds and a shift in types of shell concentration and in taxonomic composition these characteristics associated with the upward disappearance of emersion surfaces the higher frequency of storm and or wave intercalations the increase in thickness of the depositional sequences and the gradual change from peritidal shallow subtidal cycles to dominantly subtidal cycles document a general deepening upward trend more open water conditions with a depth between fairweather and storm wave base became established as a result of relative sea level rise and to a consequent increase in the available accommodation space

diagenetic patterns and pore space distribution along a platform to outer shelf transect urgonian limestone barremian aptian se france abstract the urgonian limestones of late barremian early aptian from provence se france are characterized by the occurrence of microporous limestones at regional scale alternating with tight carbonates this study based on petrographical sediment texture facies and diagenetical analyses cement stratigraphy porosity and isotope geochemistry of more than 800 limestone samples provides insight into the parameters controlling the genesis preservation or occlusion of microporosity along an inner platform to outer shelf transect the tight and microporous urgonian limestones from provence can be grouped into 5 rock types based on textures associated depositional environments porosity and pore type being 1 tight inner platform tip 2 porous inner platform pip 3 tight outer platform top 4 porous outer platform pop and 5 tight outer shelf tos in tight tip top and tos types limestones intergranular and intragranular pore spaces were entirely occluded by early marine and or early meteoric cementation whereas in microporous pip pop limestones a significant fraction of the intergranular macroporosity was preserved during early and shallow burial diagenesis micrite neomorphism hybrid ostwald ripening process occurred during meteoric shallow burial diagenesis in pip and pop limestones during the regional durancian uplift event albian lower cenomanian this process resulted in microporosity enhancement and preservation circulation of meteoric fluids during exhumation produces intercrystalline microporosity enhancement and moldic porosity development the present study documents the important role that both early diagenetic and depositional cycles and long term tectonic processes have on pore space evolution and distribution in mesozoic platform carbonates

late cretaceous to recent tectonic evolution of the north german basin and the transition zone to the baltic shield southwest baltic sea abstract in this study we investigate the late cretaceous to recent tectonic evolution of the southwestern baltic sea based on a dense grid of seismic reflection profiles this area covers the baltic sea sector of the salt influenced north german basin and its transition to the salt free baltic shield across the tornquist zone the upper cretaceous to recent structural evolution is discussed by means of individual seismic sections and derived high resolution time structure maps of the main horizons i e the upper cretaceous tertiary and pleistocene the upper cretaceous and tertiary layers reveal numerous significant faults throughout the study area several of these faults propagate upwards across the unconsolidated pleistocene sediments and occasionally penetrate the surface the salt influenced north german basin reveals three major fault trends nw se n s and nne ssw several of these faults are located directly above basement sub salt faults and salt pillows the majority of these faults are trending n s to nne ssw and parallel the direction of the gluckstadt graben faults in the salt free tornquist zone we identify two major shallow fault trends which are nw se and ne sw the majority of these faults are located above basement faults following the direction of the tornquist zone we conclude that generally basement tectonics controls activation and trends of shallow faults if salt is present the ductile salt layer causes a lateral shift between the sub and supra salt faults major plate reorganisation related to the africa iberia europe convergence and the subsequent alpine orogeny caused reactivation of pre existing faults and vertical salt movement in the late cretaceous the change of stress orientation from ne sw to a nw se during neogene caused another phase of fault and salt tectonic reactivation we explain that the ice sheet loading and or present day stress field may have acted in combination causing the recent tectonics and upward extension of the faults

rudists as gregarious sediment dwellers not reef builders on cretaceous carbonate platforms abstract it has sometimes been claimed that rudist bivalves competitively displaced corals from reef frameworks during the cretaceous this hypothesis combines two assertions 1 that the autecology of rudists was convergent with that of reef building corals and 2 that rudist formations commonly developed as reefs we dispute both assertions and thus reject the hypothesis of competitive displacement we argue instead that mobile sediments rather than frameworks dominated the margins and tops of most of the extensive carbonate platforms of the period and that it was on these non reefal biotopes that the rudists flourished definitions of reefs tend to combine two major elements 1 a robust biogenic framework with accompanying sedimentary and diagenetic components and 2 topographical relief such definitions are clearly rooted in recent coral reefs in which endosymbiotic zooxanthellae permit the extensive growth of colonial coral frameworks in shallow but relatively nutrient poor waters coralline algae and cementation may contribute significantly to the growth of rigid structures and topography is largely the legacy of pleistocene changes in sea level in rudist formations in contrast individual rudist congregations are volumetrically limited relative to sediment they are often loosely constructed and they evidently showed little if any original relief tabular and small lenticular units predominate these differences in structure and palaeoenvironmental situation between rudist and modern coralgal associations reflect the different autecologies of the constituent organisms the clonal growth of corals predisposes them to the development of frameworks projecting above the sediment surface herein termed superstratal growth by contrast the aclonal development of rudists was better suited to the opportunistic occupation of a variety of temporarily available substrata by large numbers of individuals in particular elevator rudists in which the entire commissure exhibited upward growth evidently grew with their shells largely embedded in and supported by the ambient sediment herein termed constratal growth moreover the tolerances and growth responses of rudists to such factors as water turbidity nutrients and current regime were quite different from those of the majority of reef building corals despite repeated assertions in the literature that rudists possessed zooxanthellae only a few species show any evidence for such a symbiosis and other evidence suggests that most lacked them in view of these differences in their preferred biotopes competition between rudists and corals is doubtful even though members of both groups co occur in many areas the relative decline of coral frameworks in the cretaceous was thus probably independently caused

bulk composition of northern african dust and its source sediments a compilation abstract this paper presents a review of bulk compositional data of northern african dust and its potential source sediments and includes elemental isotope and mineralogical data northern african dust represents about one half of the total global atmospheric mineral dust burden and its uplift transport and deposition have strong impacts on climate and various terrestrial and marine ecosystems the chemical data set shows that an average northern african dust exhibits comparable si fe and mn contents with respect to the average composition of the upper continental crust is slightly depleted in the alkali metals k and na and enriched in ti and p however the complete data set yields clear evidence that northern african dust and its source sediments are compositionally heterogeneous on a regional scale and that this heterogeneity can be used to differentiate between major potential source areas on the basis of so called source markers an evaluation of these compositional fingerprints shows that the following parameters and especially their combination are effective in the discrimination of the most active source areas in northern africa ratio of ca mg fe wt calcite or carbonate content palygorskite occurrence and abundance illite kaolinite ratio nd 0 value and 87sr 86sr ratio for example the data set corroborates previous ideas which assign carbonate illite and palygorskite rich mineral dusts to north west ern source regions because most of the above listed source markers do not change substantially during transport even far traveled dusts may be assigned to specific potential source areas in northern africa some limitations of the presented data set are also discussed our compilation reveals some substantial gaps in the knowledge of the composition of source sediments and mineral dusts from important potential source areas that should be filled in the future the here compiled data set can be used as a reference frame when incorporating the composition of source sediments e g mineralogy into global or regional dust transport models and can be compared with source analysis by remote sensing or back trajectory analysis however source apportionment studies supported by our data set will not only be useful for actual dust samples but will also be helpful for the understanding of paleo wind directions and hence paleo climatological conditions through the investigation of quaternary eolian sediments deposited in and around northern africa

coral reef sedimentation on rodrigues and the western indian ocean and its impact on the carbon cycle coral reefs in the southwest indian ocean cover an area of ca 18530 km2 compared with a global reef area of nearly 300000 km2 these regions are important as fishing grounds tourist attractions and as a significant component of the global carbon cycle the mass of calcium carbonate stored within holocene neritic sediments is a number that we are only now beginning to quantify with any confidence in stark contrast to the mass and sedimentation rates associated with pelagic calcium carbonate which have been relatively well defined for decades we report new data that demonstrate that the reefs at rodrigues like those at reunion and mauritius only reached a mature state reached sea level by 2 3 ka thousands of years later than most of the reefs in the australasian region yet field observations show that the large lagoon at rodrigues is already completely full of carbonate detritus typical lagoon depth less than 1 m at low spring tide the presence of aeolian dunes at rodrigues indicates periodic exposure of past lagoons throughout the pleistocene the absence of elevated pleistocene reef deposits on the island indicates that the island has not been uplifted most holocene reefs are between 15 and 20 m in thickness and those in the southwest indian ocean appear to be consistent with this observation we support the view that the co2 flux associated with coral reef growth acts as a climate change amplifier during deglaciation adding co2 to a warming world southwest indian ocean reefs could have added 7 10 to this global flux during the holocene

extreme eolian delivery of reactive iron to late paleozoic icehouse seas the biogeochemical impacts of iron rich dust to the oceans are known for earth s recent record but unexplored for deep time despite recognition of large ancient dust fluxes particularly during the late paleozoic we report a unique fe relationship for upper pennsylvanian mudrock of eolian origin that records lowstand glacial conditions within a carbonate buildup of western equatorial pangaea western united states well removed from other detrital inputs here reactive fe unambiguously linked to dust is enriched without a corresponding increase in total fe more broadly data from thick coeval loess deposits of western equatorial pangaea show the same marked enrichment in reactive fe this enrichment atypical compared to modern marine fluvial glacial loess and soil sediments suggests an enhancement of the reactivity of the internal fe pool that increased the bioavailability of the fe for marine primary production regardless of the mechanism behind this enhancement our data in combination with other evidence for high dust fluxes imply delivery of extraordinarily large amounts of biogeochemically reactive fe to glacial stage late paleozoic seas and modeling of this indicates major impacts on carbon cycling and attendant climatic feedbacks

carbonate production by rudist bivalves the record of late barremian requieniid communities from provence se france abstract rudist bearing sediments from platform carbonates of late barremian age early cretaceous cropping out in the marseille region provence se france were investigated on a 46 km wide transect after seven stratigraphic sections to quantify the role of rudists in the corresponding stratigraphic system by using various proxies the regional stratigraphic contribution of total thickness of rudist beds is relatively high 43 1 each rudist community type possesses a specific skeletal contribution of skeletal content in the range of 19 2 to 31 5 at a stratigraphic scale including rudist rich and rudist free beds the skeletal contribution drops to 13 8 this value is derived from the standard skeletal contribution obtained for each community type combined with the stratigraphic contribution of rudist beds in vertical successions and horizontal stratigraphic units a closely related value 12 8 is obtained from calculations using specific lateral dimensions of rudist bodies and their spacing i e modules depending on community types each community has a particular potential quantitative contribution to the overall regional stratigraphic system rudist production is deduced from the cyclostratigraphic approach of accumulation rates for each community type estimates of caco 3 net production are in the range of 19 to 50 kg m 2 ka 1 these values are very low when compared with those obtained at a biological scale for modern bivalves late cretaceous rudists and recent coral reefs the geological scale used for our estimates may partly account for this difference whereas low accommodation rates linked to cretaceous greenhouse conditions appear a potential important factor in this respect the low net production of requieniid dominated communities sediment dwellers not framework builders also reflects their limited sedimentogenetic power

size fractionated major particle composition and concentrations from the us geotraces north atlantic zonal transect the concentration and the major phase composition particulate organic matter caco3 opal lithogenic matter and iron and manganese oxyhydroxides of marine particles is thought to determine the scavenging removal of particle reactive teis particles are also the vector for transferring carbon from the atmosphere to the deep ocean via the biological carbon pump and their composition may determine the efficiency and strength of this transfer here we present the first full ocean depth section of size fractionated 1 51 m 51 m suspended particulate matter spm concentration and major phase composition from the us geotraces north atlantic zonal transect between woods hole ma and lisbon portugal conducted in 2010 and 2011 several major particle features are notable in the section intense benthic nepheloid layers were observed in the western north american margin with concentrations of spm of up to 1648 g l two to three orders of magnitude higher than surrounding waters that were dominated by lithogenic material a more moderate benthic nepheloid layer was also observed in the eastern mauritanian margin 44 g l that had a lower lithogenic content and notably significant concentrations of iron and manganese oxyhydroxides 2 5 each an intermediate nepheloid layer reaching 102 g l an order of magnitude above surrounding waters was observed associated with the mediterranean outflow finally there was a factor of two enhancement in spm at the tag hydrothermal plume due almost entirely to the addition of iron oxyhydroxides from the hydrothermal vent we observe correlations between poc and caco3 in large 51 m particles in the upper 2000 m but not deeper than 2000 m and no correlations between poc and caco3 at any depth in small 51 m particles there were also no correlations between poc and lithogenic material in large particles overall there were very large uncertainties associated with all regression coefficients for mineral ballast carrying coefficients suggesting that mineral ballast was not a strong predictor for poc in this section

the cyclic hierarchy of the purbeckian sierra del pozo section lower cretaceous berriasian southern spain the lowermost cretaceous berriasian sierra del pozo formation is divisible into metre scale cycles that are bundled in a four tiered hierarchy of cycles and cyclic sequences at the smallest scale sixth order cycles thought to be the product of precessionally forced sea level fluctuations c 20 ka average less than a metre in thickness shallow upward and are bounded by surfaces where deeper facies abruptly overlie shallower facies bundles of sixth order cycles called fifth order sequences are recognized by two types of asymmetric patterns in facies distribution first more pronounced facies changes occur at sixth order cycle boundaries lower in a sequence whereas smaller facies changes occur at cycle boundaries higher in a sequence secondly subtidal marine limestones i e biomicrites and biosparites are the dominant facies lower in a cyclic sequence whereas more restricted or shallower water facies i e mud cracked microbial laminites dolomites shale and clay are more predominant higher in a cyclic sequence the bundling of sixth order cycles is explained as a product of periodic change 100 ka in the eccentricity of the earth s orbit the degree of orbital eccentricity modulates the magnitude of precessional sea level fluctuations which in turn determine the relative facies contrasts at sixth order cycle boundaries larger scale fourth and third order sequences are defined by similar patterns in facies contrast at successive sequence boundaries and by a change in predominant facies type from bottom to top these patterns are explained as the product of 400 ka and 2 ma periodic variations in the eccentricity of the earth s orbit in summary the strength of the precessional signal varies in consort with periodic changes in orbital eccentricity at three time scales producing a stacked hierarchy of cycles and sequences of cycles change in obliquity of the earth s axis may modulate the effects of the precessional signal and thereby modify patterns of preserved cyclic structure this interpretation of cyclicity in the sierra del pozo section is markedly different from that of

depositional cycles composite sea level changes cycle stacking patterns and the hierarchy of stratigraphic forcing examples from alpine triassic platform carbonates carbonate platform deposits record a complex interplay of numerous geodynamic variables of which eustasy subsidence and sediment accumulation are prime factors in determining both the kilometer scale depositional sequence scale and meter scale depositional cycle scale stratigraphic packaging in this study we looked particularly at composite eustasy that is superimposed sea level fluctuations with different frequencies defined as orders and different amplitudes and the role it plays in the linkage between meter scale cyclic stratigraphy and kilometer scale sequence stratigraphy specifically we have investigated the relationship between low frequency third order 1 10 m y period depositional cycles and their component high frequency fourth 0 1 1 m y and fifth 0 01 0 1 m y order cycles through detailed stratigraphic analyses of alpine triassic platforms complemented by computer modeling on the basis of our results we suggest that in general there exists a hierarchy of stratigraphic forcing driven by composite eustasy that results in organized stacking patterns thickness subfacies character early diagenetic attributes of high frequency typically fourth and fifth order shallow water carbonate cycles dictated by low frequency third order relative sea level effects we suggest that systematic vertical changes in stacking patterns of high frequency cycles across a larger depositional sequence are due to systematic and predictable differences in depositional space available during the rising and falling stages of a relative third order sea level change we also suggest that these systematic variations in cycle stacking patterns will exist regardless of the mechanism responsible for generating the high frequency cycles be it an autocyclic or allocyclic mechanism this approach has major implications for the use of high frequency fourth and fifth order cycle characteristics to identify third order cycles in outcrops and cores of shallow water carbonates where stratigraphic control may be less than desirable this would constitute a valuable bridge between cyclic stratigraphy at the meter scale and sequence stratigraphy at the seismic scale we present two examples from triassic buildups of the alps the ladinian latemar buildup and the norian dolomia principale where a systematic succession of high frequency cycle stacking patterns and early diagenetic features exists within an overriding third order cycle sequence reflecting the interplay of short term high frequency fourth fifth order eustasy and long term low frequency third order eustasy in accordance with the hierarchy of stratigraphic forcing central to the interpretation of these examples is the demonstration that true eustatic rhythms are recorded in the high frequency cyclicity as verified by time series analyses and the use of fischer plots these examples can be modeled by computer under conditions of lag depth constrained sedimentation uniform subsidence and composite eustasy we also present two examples one from the alpine triassic the norian lofer cyclothems and one from the pleistocene of south florida that lack both a systematic succession of high frequency cycle stacking patterns and identifiable composite rhythms in the stratigraphic record despite the existence of composite high frequency eustasy in these examples we call upon 1 local tectonic forcing in the form of short term deviations in subsidence via faulting lofer example and 2 large differences in the relative amplitudes of different orders of high frequency sea level oscillations pleistocene example to explain the lack of composite rhythms and we present computer simulations to illustrate the concepts an understanding of composite relative sea level changes and the potential for a hierarchy of stratigraphic forcing provides the link between cyclostratigraphy and sequence stratigraphy and also has important implications regarding the stratigraphy of early diagenesis

the contemporary physical and chemical flux of aeolian dust a synthesis of direct measurements of dust deposition abstract the deposition of aeolian or windblown dust is widely recognized as an important physical and chemical flux to ecosystems dust deposition adds exogenous mineral and organic material to terrestrial surfaces and can be important for the biogeochemical cycling of nutrients there have been many studies that characterize the physical and chemical composition of dust however few studies have synthesized these observations in order to examine patterns geochemical fluxes we have compiled observations of dust deposition rates particle size distributions psd mineralogy and bulk elemental and organic chemistry the rates of dust deposition observed across the globe vary from almost 0 to greater than 450 g m 2 yr 1 sites receiving dust deposition can be partitioned into broad categories based on there distance from dust source regions when compared to global dust models our results suggest some models may underestimate dust deposition rates at the regional and local scales the distance from the source region that dust is deposited also influences the particle size distributions mineralogy and chemical composition of dust however more consistent dust sampling and geochemical analyses are needed to better constrain these spatial patterns on average the concentrations of most major elements si al fe mg ca k in aeolian dust tend to be similar 20 to the composition of the upper continental crust ucc but there is substantial variability from sample to sample in contrast some elements tend to be depleted na or enriched ti in dust likely as a result of soil weathering processes prior to dust emissions trace elements especially heavy metals are consistently enriched in dust relative to the ucc ecologically important nutrients such as n and p are also present in dust deposition the geochemical flux attributable to dust deposition can be substantial in ecosystems located proximal to dust source regions we calculate estimates of elemental flux rates based on the average chemical composition of aeolian dust and varying rates of deposition these estimated flux rates are useful as a rough gauge of the degree to which dust deposition may influence biogeochemical cycling in terrestrial ecosystems and should be utilized to better constrain deposition estimates of global dust models

subglacial water escape structures and till structures slettjokull iceland beyond slettjokull the north part of the ice cap m rdalsjokull south iceland an undulating till plain is dissected by meltwater streams throughout a transect from the ice margin to the 1900 ice marginal moraine a distance of about 1 2 km finely laminated wedge shaped water escape structures wes are present originating in the till and disappearing down ice into the underlying sands and fine gravels a second set of much smaller and deformed black wes occurring within the till has been produced by upward injection into the till as a response to stiffening of the till after dewatering by the downward developing wes at present the toe of the glacier is frozen to its bed and the frozen bed material is more than 2 m thick during the relatively cold period around the turn of the century and until the late 1920s a similar submarginal body of permafrost must have existed the sequence reveals that subglacial meltwater attributed to drainage following the 1918 katla eruption was blocked by a frozen glacier toe causing the formation of water escape structures subsequently glacier flow deformed the substratum and produced the threefold division of the till bed the study has important implications for theories envisaging subglacial floods because it demonstrates that it is very difficult for temperate glaciers with a temporary frozen bed in the toe region to retain subglacial meltwater copyright 1999 john wiley sons ltd

debris flow and glacioisostatic induced soft sediment deformation structures in a pleistocene glaciolacustrine fan the southern baltic sea coast poland abstract middle pleistocene glaciolacustrine fan sediments are exposed along a cliff at the baltic sea coast where plastic and brittle soft sediment deformation structures ssds commonly occur 1 fold structures various types of folds and flexures 2 load structures load casts pseudonodules and flame structures 3 water escape structures wes and 4 brittle deformation structures such as faults medium and small scale reverse and normal and fragments of broken up laminae the origins of the ssds can be linked to gravitational processes promoted by shear stresses in subaqueous debris flows on the glaciolacustrine fan and by the weight of overlying sediments and or to the glacial rebound of earth s crust during deglaciation because in the pleistocene the baltic sea and surrounding areas were covered by ice sheets many times the question investigated here concerns recognition of the trigger mechanisms responsible for the development of ssds and the criteria needed to recognize those mechanisms based on the lithological and deformational features of the sediments involved some types of ssds can look similar regardless of trigger mechanisms but some occur more often as a result of a specific mechanism is it possible to distinguish ssds of seismic origin in a glaciolacustrine fan succession affected by multiple debris flows and of ssds that evolved as a consequence of slope processes we suggest criteria to recognize ssds triggered by the glacioisostatic rebound as well as those which can develop as a result of the rebound and slope processes

carbonate cycle stacking patterns and hierarchies of orbitally forced eustatic sealevel change ordered stacking of meter scale upward shallowing cycles manifested as repeated thickness hierarchies within cratonic carbonate sequences has been considered primary evidence for causal relations between orbitally forced climate change and eustatic sealevel variation explicit in this argument is the assumption that each individual cycle represents a single sealevel rise sensitivity testing of one dimensional forward models incorporating a depth threshold of carbonate accumulation indicates that multiple upward shallowing cycles may originate during any single rise in sealevel variation in resultant cycle stacking pattern is sensitive to changes in sealevel amplitude sedimentation rate and subsidence rate with highest stacking ratios ratio of number of cyclic units to number of eustatic periods produced by low sealevel amplitudes and high sedimentation and subsidence rates these relations indicate that direct correlation between multiple frequency eustatic sealevel variations and meter scale cycle stacking hierarchies is unwarranted thus prevalent interpretations regarding the stacking record of orbital forcing in ancient carbonate rock sequences should be reevaluated

quantitative stratigraphy of rudist limestones and its bearing on spatial organisation of rudist communities the late barremian urgonian sequences of provence s e france abstract rudist beds in platform carbonates of late barremian age early cretaceous cropping out in the marseille region provence se france possess a substantial lateral continuity 40 km whereas associated rudist bodies tend to be less continuous transition probabilities markov chain analysis are used at a regional scale to test the lateral continuity of rudist bodies and their four associated rudist assemblages each rudist assemblage has a specific probability to be adjacent to itself or to any one at a local scale analysing the variations of transition probabilities as a function of distance using various proxies shows a periodic spatial trend the style of which depends on the type of rudist assemblage i e community type the foregoing documents two groups with different properties group 1 includes two communities characterised by small forms restricted to very shallow and muddy settings organised spatially into small patches c 1000 1500 m with moderate spacing c 1500 2000 m group 2 includes two communities characterised by mixed size or large forms typical of deeper water and more sandy settings organised spatially into large patches c 3000 m with a larger spacing c 3000 4000 m the internal architecture and the dimensions of these rudist bodies argue against a reefal nature quantitative estimates of lateral continuity and spatial variations of rudist bodies have a significant potential for reservoir modelling of hydrocarbon bearing rudist rich platform carbonates

quantitative analysis of rudist assemblages a key for palaeocommunity reconstructions the late barremian record from se france abstract the present paper addresses the question of rudist assemblages and their interpretation in terms of ecological entities i e communities quantitative studies performed on rudist assemblages in the barremian platform carbonates of the marseille region se france were based on biological attributes shell size shell thickness packing density packing index coverage and shell contribution and sedimentological attributes from the associated substrate mud content grain size and skeletal contribution to the sediment and bed thickness the studied samples were originally ascribed to four assemblages defined on the basis of semiquantitative data contrasting results were obtained from multivariate analysis applied to biological then to biological plus sedimentological data the latter documents four groups of samples in correspondence with the former assemblages this grouping refers directly or indirectly to critical attributes of communities biomass and substrate evidence for some taxonomic markers and because the assemblages represent recurrent statistical entities corroborate their interpretation as palaeocommunities the method proposed here for the reconstruction of rudist palaeocommunities has a potential for unravelling biological assemblages with a low taxonomic resolution

major asian aeolian inputs indicated by the mineralogy of aerosols and sediments in the western north pacific recent atmospheric chemistry studies have shown that substantial quantities of soil material are being transported out of asia and across large regions of the north pacific1 2 in the central north pacific the estimated1 6 12 1012 g yr 1 and measured2 20 1012 g yr 1 deposition rate of mineral aerosols could account for a substantial fraction of the non biogenic portion of deep sea sediments in this region where sedimentologists have previously estimated that 75 95 3 4 of the surface sediment is derived from atmospheric dust fallout the quantitative importance of wind transported aeolian material to sedimentation in the north pacific would be more firmly established if it could be shown that the composition of the present day soil aerosol is similar to that of mineral particles in the underlying sediments which have been deposited over a period of thousands of years here we compare the compositions of soil aerosols and sediments collected from the western north pacific and find that their mineralogies are identical except for one mineral this supports the hypothesis that the sediments are heavily impacted by aeolian sources

translating milankovitch climate forcing into eustatic fluctuations via thermal deep water expansion a conceptual link sedimentological evidence indicates metre scale cyclic changes in global sea level during mesozoic greenhouse climates the cyclicity is thought to be due to milankovitch forcing the absence of continental ice caps requires other mechanisms than glacier build up to explain these variations we propose that thermal expansion of the entire oceanic water column may partly explain the observed sea level variations on milankovitch timescales using existing climate model results we show that an increase in deep water temperature of 2 c and a corresponding sea level rise of 1 7 m by thermal expansion can be induced by milankovitch forcing via increased formation of warm deep waters in low latitudes

quantitative study of a hippuritid rudist lithosome in a santonian carbonate platform in the southern central pyrenees abstract the santonian carbonate platform deposits of the sant corneli anticline in the southern central pyrenees contain distinctive lenticular to tabular lithosomes formed by congregations of slender hippuritid rudists here we make a quantitative study of one of the lithosomes in the sant pere de vilanoveta member in the northern side of sant corneli it is exposed over some 4 km along a wnw ese section and shows a remarkably persistent thickness up to a maximum of 5 15 m though for the most part it is less than 3 m thick in the lithosome hippuritid shells are mostly preserved inclined about 30 60 from the perpendicular with respect to bedding the majority of inclined shells lean towards the southwestern to southeastern quadrants the inferred principal downstream direction hippuritids are loosely clustered and supported in a fine bioclastic matrix percentage cover of hippuritids ranges from 19 8 at the base to 31 9 in the middle and top of the lithosome the preliminary data on numerical densities number of individuals per unit area of hippuritids show some clustering around values of about 290 750 individuals per m2 the inclined orientation of hippuritid shells seems original and the result of active growth by the animals the high numerical density of hippuritids at the base of the lithosome may indicate that the hippuritid congregation grew rapidly the congregation appears to have reached an optimal level of density by the middle of the lithosome and to have maintained it through time during the development of the rudist congregation the lithosome lacks relief and has no evidence of any rigid framework

glacio seismotectonics ice sheets crustal deformation and seismicity abstract the last decade has witnessed a significant growth in our understanding of the past and continuing effects of ice sheets and glaciers on contemporary crustal deformation and seismicity this growth has been driven largely by the emergence of postglacial rebound models pgm constrained by new field observations that incorporate increasingly realistic rheological mechanical and glacial parameters in this paper we highlight some of these recent field based investigations and new pgms and examine their implications for understanding crustal deformation and seismicity during glaciation and following deglaciation the emerging glacial rebound models outlined in the paper support the view that both tectonic stresses and glacial rebound stresses are needed to explain the distribution and style of contemporary earthquake activity in former glaciated shields of eastern canada and fennoscandia however many of these models neglect important parameters such as topography lateral variations in lithospheric strength and tectonic strain built up during glaciation in glaciated mountainous terrains glacial erosion may directly modulate tectonic deformation by resetting the orogenic topography and thereby providing an additional compensatory uplift mechanism such effects are likely to be important both in tectonically active orogens and in the mountainous regions of glaciated shields in general the short term response to ice fluctuations is similar to the earth s response to fluctuations in water reservoirs with the subsequent increase or decrease in seismicity which depends on the pre existing stress state when the ice fluctuations occur on the spatial scale and magnitude of the late pleistocene glaciation and deglaciation however the viscoelastic response of the earth especially the mantle causes significant changes in crustal deformation and earthquake activity that is spatially extensive and temporally complex the regions of greatest ice thickness and the regions marginal to the late pleistocene ice sheets indicate the most dramatic evidence of earthquake faulting the mantle response to these large ice mass fluctuations and the change in mass between the oceans and land caused and continues to cause measureable crustal deformation at hundreds of kilometres from the ice margins for both tectonically active and cratonic regions palaeoseismic investigations of late pleistocene and holocene faults are an important tool in evaluating earthquake hazard the predicted response of the earth over this time however is very dependent on the model assumed for most regions far more carefully designed field observations are needed to constrain the existing rheological and ice models

bioevents and palaeoenvironmental changes in carbonate platforms the record of barremian urgonian limestones of se france abstract biostratigraphic studies of barremian platform carbonates from se france and nearby regions indicate the last occurrence lo horizons of some common shallow water taxa firstly two dasycladale algae piriferella paucicalcarea and salpingoporella genevensis which have their first occurrence in the upper hauterivian disappear in the lower barremian at the nicklesia pulchella kotetishvilia compressissima transition secondly a rudist bivalve the genus agriopleura which has its first occurrence in the upper hauterivian has its lo in the lower upper barremian within the gerardhtia sartousiana zone the specific stratigraphic levels of the above bioevents recorded in platform carbonates may be used for dating corresponding ammonite free successions stratigraphic implications are constrained by the biogeographical extent of the key species which is essentially the western and central european margin of the mediterranean tethys the joint lo of p paucicalcarea and s genevensis are inferred to have been linked with oceanographic and climatic changes i e a cooling event platform carbonates were interrupted by a drowning event represented by a maximum flooding surface or transgressive surface shallow water orbitolinidae record significant extinctions and deep water ammonites show a significant turnover similarly modifications in ammonite faunas bottom currents temperature changes i e cooling and a major extinction among the family orbitolinidae coincided with the lo of agriopleura platform perturbations including exposure possibly a sequence boundary and basin margin instability both with a tectonic background were associated with this event the foregoing events and the linkage of palaeobiogeographic changes that is the migration of the key taxa towards southern latitudes in correspondence with the lo bioevents indicate that thermal changes including seasonality appear to have been the prominent controlling factor

facies analysis of an upper cretaceous high energy rudist dominated carbonate ramp matese mountains central southern italy subtidal and peritidal cycles abstract upper cretaceous shallow water limestones rich in rudists have been studied in the matese mountains they show a preponderance of skeletal components molluscs and benthic foraminifers and a lack of non skeletal grains the most prominent sediments of the studied stratigraphic interval are rudist dominated fine to coarse grained lithologies most of the senonian successions are characterized by massive neritic limestones rich in molluscs mostly rudists and subordinate gastropods and a few corals the sediments were generated in situ on shelves where rudist bivalves were the primary sediment producers these sediments were actively moved by storms waves and swells the finer fractions were probably winnowed out and deposited in deeper water well bedded dolomitized mudstones wackestones microbial laminites and benthic foraminifer wackestones characterize some successions where they rhythmically alternate and testify to deposition in tidal flat environments the lithofacies faunal and taphonomic characters and the sedimentary structures are typical of a ramp like open shelf with local peritidal deposition the vertical lithofacies organization consists of numerous decimetre to metre scale shallowing upward subtidal and peritidal cycles a complete transition from peritidal to subtidal cycles has been recognized and documented the peritidal cycles are usually bounded by desiccation surfaces and or dolomitized crusts followed by shallow subtidal to peritidal facies of the next cycle the subtidal cycles are typified by rudist floatstones passing to large scale cross bedded bioclastic packstones grainstones current and storm structures are distinctive features in shallower water environments the effects of submarine erosion prevail hardgrounds commonly developed and the resulting cycles are usually truncated the formation of the peritidal cycles appears to have been controlled by accommodation space in response to fluctuations in relative sea level the formation of the subtidal cycles was determined by sedimentation rates in response to fluctuations in the zones of fair weather and storm wave reworking in turn controlled by relative sea level this indicates that sediment production and supply were important controlling factors in the cycle formation during the early senonian stratigraphic interval the recognition of similar depositional styles in other early senonian successions cropping out in the southern apennines suggests that this type of sedimentation is a recurring attribute of the upper cretaceous open shelves

subglacial decoupling at the sediment bedrock interface a new mechanism for rapid flowing ice abstract in undetermined on millennial or even centennial time scales the activity of rapid flowing ice can affect climate variability and global sea level through release of meltwater into the ocean and positive feedback loops to the climate system at the surge type glacier bruarjokull an outlet of the vatnajokull ice cap eastern iceland extremely rapid ice flow was sustained by overpressurized water causing decoupling beneath a thick sediment sequence that was coupled to the glacier this newly discovered mechanism has far reaching consequences for our understanding of fast flowing ice and its integration with sediment discharge and meltwater release c 2006 elsevier ltd all rights reserved

pitfalls of normalization of marine geochemical data using a common divisor abstract normalization of trace element contents of sediment through division by the content of an immobile element usually aluminum is common practice in marine geochemical studies this might appear to be a simple way of correcting for dilution by sedimentary phases barren of a particular trace element for instance carbonates or silica and for comparison with its content in a standard clay or shale the purpose of this paper is to revive the awareness of the pitfalls of this practice by giving numerical examples of the often unexpected results of normalization taking a statistical perspective it is first shown that uncorrelated variables acquire spurious correlations when normalized but normalization can also increase decrease change sign of or even blur the correlations between unmodified variables next a number of realistic scenarios are worked out to show that the correlations between normalized element contents still suffer from the closure effect only in a few simple cases it is possible to extract from the normalized data realistic estimates of trace element contents in distinct sedimentary phases such as organic matter this is ascertained from data on copper contents in sediment from the black sea and arabian sea when the coefficient of variation i e standard deviation divided by the mean of the aluminum data is relatively low and much lower than for the original values of the trace elements comparisons of correlations can equally well or even better be made on the basis of the unmodified values then the comparison of trace element data with their values for standard shales is discussed the inherent problem is that the composition of the commonly used standard shale and consequently the reference values of normalized elements are not necessarily representative of the local or regional sediments in the study area also this method falls short of identifying the processes responsible for enrichment or diminution in trace element contents finally consideration is given to some aspects of a proper use of al normalization

chemical characterization of ambient aerosol collected during the southwest monsoon and intermonsoon seasons over the arabian sea labile fe ii and other trace metals atmospheric deposition of iron fe to certain regions of the oceans is an important nutrient source of fe to the biota and the ability of the biota to uptake fe is dependent on the speciation of the fe therefore understanding the speciation of fe in the atmosphere is critical to understanding the role of fe as a nutrient source in surface ocean waters labile ferrous iron fe ii concentrations as well as total concentrations for fe and other important trace metals cations and anions were determined over the arabian sea for two nonconsecutive months during 1995 ambient aerosol samples were collected during the indian ocean intermonsoon and southwest monsoon seasons over the arabian sea sampling took place aboard the german research vessel meteor in the months of may leg m32 3 intermonsoon and july august leg m32 5 southwest monsoon both cruise tracks followed the 65th east meridian traveling for 30 days each from north to south during leg m32 3 and from south to north during leg m32 5 a high volume dichotomous virtual impactor with an aerodynamic cutoff size of 3 m was used to collect the fine and coarse aerosol fractions for metal analysis a low volume collector was used to collect aerosol samples for anion and cation analysis the analysis for labile fe ii was done immediately after sample collection to minimize any possible fe redox reactions which might occur during sample storage the analytical procedure involved filter extraction in a formate formic acid buffered solution at ph 4 2 followed by colorimetric quantification of soluble fe ii metals anions and cations were analyzed after the cruise total atmospheric aqueous labile fe ii concentrations during the intermonsoon were between 4 75 and 80 was present in the fine fraction 3 0 m during the southwest monsoon atmospheric aqueous labile fe ii concentrations were consistently below the detection limit 0 34 to 0 089 ng m 3 depending on the volume of air sampled air mass back trajectories 5 day three dimensional showed that air masses sampled during the southwest monsoon had advected over the open indian ocean while air masses sampled during the intermonsoon had advected over northeast africa the saudi arabian peninsula and southern asia these calculations were consistent with the results of the statistical analysis performed on the data set which showed that the variance due to crustal species during the intermonsoon samples was greater than the variance due to crustal species during the southwest monsoon the factor scores for the crustal components were also greater when the back trajectories had advected over the nearby continental masses principal component analysis was also performed with the intermonsoon samples where aqueous labile fe ii was above the detection limit aqueous labile fe ii did not correlate well with other species indicating possible atmospheric processing of the iron during advection

stable isotope sclerochronology of rudist bivalves growth rates and late cretaceous seasonality the almost complete translation of shell accretion to vertical growth was a successful morphogenetic adaptation of rudist bivalves which replaced coral algal hydrozoan communities in most tethyan shallow marine environments during the cretaceous growth rates of rudist shells are therefore important in reconstructions of cretaceous shallow marine benthic communities carbon and oxygen isotopic compositions were analyzed in sclerochronological profiles through the shells of two late cretaceous rudist bivalves from greece and turkey values of 13 c vary between 0 8 and 2 2 in the hippuritid vaccinites ultimus and between 0 8 and 2 6 in the radiolitid gorjanovicia cf costata ranges in 18 o are 5 3 to 2 9 and 4 6 to 2 1 respectively a distinct cyclicity of 13 c and 18 o in both shells reflects late cretaceous seasonality and indicates annual vertical growth increments of 45 mm in v ultimus and 54 mm in gorjanovicia the concentrations of minor elements are similar to those of extant bivalves with low mg calcite shells

the post glacial landscape evolution of the north german basin morphology neotectonics and crustal deformation the recent evolution of the north german basin ngb which is presently a low seismic area was partly affected by glacial loading and unloading of the ice masses major stresses acting within the ngb are induced by the north atlantic ridge push the ongoing alpine collision and the post glacial rebound of fennoscandia present day horizontal stresses within the ngb are directed generally nw se but fan and bend north of 52 n towards nne major basement faults are directed nw se minor faults ne sw and nne ssw and are clearly detectable in geomorphological and satellite lineaments furthermore the drainage pattern and the distribution of lakes in northern germany follow exactly block boundaries and hence mark zones of present day subsidence the understanding of the post glacial morphology and reactivation of faults requires a view into the very heterogeneous crust and upper mantle below the ngb the re adjustment of the individual fault blocks during post glacial relaxation of the lithosphere leads to differential crust dependent uplift and probably to the formation of urstrom valleys the urstrom valleys and terminal moraines in northern germany appear to parallel the major tectonic lineaments and lithospheric block boundaries the lithospheric memory is expressed in the post glacial landscape evolution of the ngb

basal sliding of ice stream b west antarctica a tethered stake apparatus is used to measure basal sliding in a borehole on ice stream b west antarctica about 300 km upstream east from its grounding line near the head of the ross ice shelf a metal stake emplaced at the top of a layer of unfrozen till underlying the ice is connected by a tether line to a metering unit that measures the tether line as it is pulled out from the borehole by the stake as a result of basal sliding the measured sliding motion includes any actual slip across the ice till interface and may include in addition a possible contribution from shear deformation of till within about 3 cm of the interface this 3 cm figure follows from a qualitative model of the movements of the stake in the course of the experiment based on features of the record of apparent sliding alternative but less likely models would increase the figure from 3 cm to 10 cm or 25 cm in any case it is small compared to the seismically inferred till thickness of 9 m measured apparent sliding averages 69 of the total motion of 1 2 m d 1 over 26 days of observation if a 3 5 day period of slow apparent sliding 8 of the total motion is included in the average the occurrence of the slow period raises the possibility that the sliding motion switches back and forth between c 80 and c 8 of the total motion on a time scale of a few days however it is likely that the period of slow apparent sliding represents instead a period when the stake got caught on the ice sole if the slow period is therefore omitted the indicated average basal sliding rate is 83 of the total motion in either case basal sliding predominates as the cause of the rapid ice stream motion in the last 2 days of observation the average apparent sliding rate reached 1 17 m d 1 essentially 100 of the motion of the ice stream if till deformation contributes significantly to the ice stream motion the contribution is concentrated in a shear zone 3 cm to possibly 25 cm thick at the top of the 9 m thick till layer these observations if applicable to the west antarctic ice sheet in general pose complications in modeling the rapid ice streaming motion

improving shallow water carbonate chemostratigraphy by means of rudist bivalve sclerochemistry deep time shallow marine carbonate platforms record distinct biotic responses to climatic and environmental stressors unfortunately precise temporal assignment of these biotic responses is often problematical due to poor biostratigraphic control and or a significant diagenetic overprint of the neritic bulk carbonate chemostratigraphic inventory an accurate stratigraphic framework is essential to better understand the causal relation between biotic events recorded by carbonate platforms and environmental changes that for instance culminated in mass extinction events or prolonged episodes of oceanic anoxia here we provide an integrated carbon and strontium isotope stratigraphy of the early cretaceous subtropical provence carbonate platform in se france that is based solely on pristine low mg calcite from rudist bivalves carbon isotope data of geochemically screened rudist fragments enabled reconstruction of a characteristic barremian pattern including the mid barremian event mbe that allowed for a precise correlation with stratigraphically well constrained tethyan shallow water and hemipelagic reference sections in order to evaluate ontogenetic carbon isotope changes and the overall variability of the shell derived carbon isotope data numerous sclerochronological carbon isotope profiles of individual large rudist shells are presented strontium isotope stratigraphy supports the carbon isotope based age of the studied sections but also provides unequivocal evidence for a major hiatus in the depositional record covering large parts of the late barremian in contrast to biostratigraphic and bulk carbonate chemostratigraphic archives the here established chronostratigraphy of carbonate platform evolution in the southern provence region demonstrates a twofold resurgence of rudist rich carbonate platform production during the early aptian and arguably the latest early aptian

deglaciation seismotectonics a principal influence on intraplate seismogenesis at high latitudes abstract in many high latitude stable continental regions deglaciation dominates the current crustal strain field interference between polarised tectonic and radial deglaciation strain fields affects the deviatoric stress state and fault stability margins and in consequence both the levels and properties of seismicity throughout glacial loading and unloading the most notable present day affects of this strain interference are predicted to include alternating quadrants of enhanced seismicity and aseismicity around rebound domes and former peripheral forebulges such strain interference can explain much of the geography and timing of holocene earthquake occurrence across northern europe and eastern north america

growth history of shallow water carbonates control of accommodation on ecological and depositional processes we explore the role played on the growth of shallow water carbonates by changes in accommodation using case studies from late quaternary to modern carbonate environments i e coral reefs and carbonate platforms and ramps accommodation appears not to influence either primary productivity or community structure k versus r strategists as these are directly governed by nutrient supply but it does control submarine depositional profiles and their stratigraphic expression i e volumetric sedimentary partitioning the growth of communities from incipient to senescent stages is dictated by relative rates of sea level variations although ambient temperatures and trophic conditions may modify the community response a decrease or stabilization of accommodation favours lateral migration thus generating ecological and sedimentary innovations organic carbon production tends to be positively correlated to that of carbonate both declining as accommodation decreases shallow water carbonates develop as a result of the interplay of factors including the types and rates of biological and physical processes applying depositional models of recent shallow water carbonates to the interpretation of ancient carbonate platforms first needs to acknowledge the respective role of the two contrasting phases that operated during the post glacial sea level rise an earlier fast rising phase versus a later slowly rising to stabilizing phase the period of relative sea level stabilization i e the past 6 000 years appears a relevant reference for still stand related carbonate systems furthermore the oligotrophic nutrient model a dominant feature of the modern shallow water tropics can be used as an analogue in reconstructing carbonate growth histories during greenhouse episodes of earth history

seismites an attempt at critical analysis and classification abstract the main types of seismites are reviewed following the proposed classification and are illustrated by our own case studies the large variety of seismites depends on the sedimentologic hydrodynamic and diagenetic characters of the deposits subject to seismic shocks on a given site generally different types of seismites cane be related to the same seismic event these peculiar but widespread sedimentary structures are not always univocal and may often be related to different causes therefore the structures discussed must necessarily be placed in a detailed geological context

soft sediment deformation structures in nw germany caused by late pleistocene seismicity new data on seismically triggered soft sediment deformation structures in pleniglacial to late glacial alluvial fan and aeolian sand sheet deposits of the upper senne area link this soft sediment deformation directly to earthquakes generated along the osning thrust which is one of the major fault systems in central europe soft sediment deformation structures include a complex fault and fold pattern clastic dikes sand volcanoes sills irregular intrusive sedimentary bodies flame structures and ball and pillow structures the style of soft sediment deformation will be discussed with respect to brittle failure liquefaction and fluidization processes and was controlled by 1 the magnitude of the earthquake and 2 the permeability tensile strength and flexural resistance of the alluvial and aeolian sediments it is the first time in northern germany that fluidization and liquefaction features can be directly related to a fault the occurrence of seismicity in the late pleistocene and in the seventeenth century indicates ongoing crustal movements along the osning thrust and sheds new light on the seismic activity of northern germany the late pleistocene earthquake probably occurred between 15 9 1 6 and 13 1 1 5 ka the association of soft sediment deformation structures implies that it had a magnitude of at least 5 5

cycling of lithogenic marine particles in the us geotraces north atlantic transect in this paper we present describe and model the first size fractionated 0 8 51 m 51 m water column particulate trace metal results from the us geotraces north atlantic zonal transect in situ pumping survey with a focus on the lithogenic tracer elements al fe and ti this examination of basin wide full depth distributions of particulate elements elucidates many inputs and processes some for bulk lithogenic material others element specific which are presented via concentration distributions elemental ratios size fractionation dynamics and steady state inventories key lithogenic inputs from african dust north american boundary interactions the mediterranean outflow hydrothermal systems and benthic nepheloid layers are described using the refractory lithogenic tracer ti we develop a 1 d model for lithogenic particle distributions and test the sensitivities of size fractionated open ocean particulate ti profiles to biotically driven aggregation disaggregation rates vertical sinking speeds and dust input rates we discuss applications of this lithogenic model to particle cycling in general and to poc cycling specifically

geochemical composition of aeolian dust and surface deposits from the qatar peninsula abstract the trace metal geochemistry of atmospheric dust and terrestrial surface particles were studied on the qatar peninsula from february 2014 to november 2015 we included samples of the mega dust storm event on 01 02 april 2015 atmospheric dust samples were collected using passive dust traps terrestrial surface deposits of recent dust accumulation and traffic particulate from roads were also sampled all samples were total acid digested and analyzed for major and trace elements using icp oes analyzer the concentration of thirteen elements ca mg ag as cd cr cu mo ni se sn sr zn were enriched in atmospheric dust samples relative to upper continental crust ucc calcium was especially enriched by up to 435 relative to ucc about 33 of the total sample mass was caco3 reflecting the composition of surface rocks and soils in the source areas of the elements typically associated with anthropogenic activity ag ni and zn were most enriched relative to ucc with enrichment factors ef of 182 233 and 209 respectively other metals which normally reflect anthropogenic sources including pb and v were not significantly enriched with enrichment factors of 25 and 3 respectively major elements al mn fe were depleted 58 35 and 5 respectively relative to ucc due to the large dilution effect of the enrichment of caco3 back trajectories were determined at the date of sampling for each sample using the noaa hysplit model these showed that the source of the dust particles was almost equally divided between northerly and southerly sources except one sample which appeared to originate from the west more variability in particle source locations were observed during the winter months october to march samples from the mega dust storm were solubilized using an acetic acid hydroxylamine hydrochloride leach procedure to obtain an upper estimate of the potential contribution of bioactive elements to surface seawater the leach procedure solubilized a significant fraction of almost all elements ca was the element most affected 81 removed because of the carbonate minerals present bioactive elements like fe 25 and p 58 were also significantly solubilized because river input is so small to the arabian gulf this solubilized fraction of dust is likely a major source of nutrients to surface seawater enrichment factors were also calculated with respect to the average composition of terrestrial surface deposits tsd samples are not enriched significantly with respect to major components ef

global environmental controls on cretaceous reefal ecosystems abstract the hypothesis of global environmental control of reefal ecosystems is developed in order to explain the dramatic biotic changes in cretaceous benthic communities during a 30 m y period in the early cretaceous the dominant biota in the reefal ecosystem changed from corals algae and rudists to rudists with minor coral species this change included the reduction of the binder niche which in the early cretaceous was occupied by stromatoporoids and algal cyanobacterial associations the role of bafflers increased during the mid cretaceous as first the radiolitids then the hippuritids diversified and increased in abundance the characteristic encrusters changed from green algae and bryozoans to red algae the orbitolinid foraminifers were replaced by the alveolinids the biotic changes are reflected in the feeding habit substrate niche relationships within the communities and the biotic processes of competition for space and nutrients these changes were closely linked with major though subtle global shifts in oceanographic current systems in water mass chemistry in nutrient levels and in plate positions and oceanic volcanism associated with super plume activity the development of widespread anoxic water masses influenced the composition of the oceans and the atmosphere itself the feedback interactions among these processes may have had an indirect but unalterable affect on the composition and structure of cretaceous reefs particularly the frequency of sea level rise and flooding of the shelf with low oxygen waters increased by two times during the mid cretaceous this increased frequency of stress upon the benthic communities may have crossed the threshold resulting in the biotic changes such as the replacement of corals by rudists as the most abundant reefal group

chemical characterization of ambient aerosol collected during the northeast monsoon season over the arabian sea labile fe ii and other trace metals 1 ambient aerosol samples were collected over the arabian sea during the month of march of 1997 aboard the german r v sonne as part of the german joint global ocean flux study jgofs project this is the third study in a series of analogous measurements taken over the arabian sea during different seasons of the monsoon dichotomous high volume collector samples were analyzed for ferrous iron immediately after collection while trace metals anions and cations were determined upon return to the laboratory the main crustal component was geochemically well represented by the average crustal composition and amounted to 5 94 3 08 m gm 3 an additional crustal constituent of clay like character rich in water soluble ca and mg was seen in the fine fraction in air masses of arabian origin total ferrous iron concentrations varied from 3 9 to 17 2 ng m 3 and averaged 9 8 3 4 ng m 3 with 87 2 of fe ii present in the fine aerosol fraction fe ii concentrations accounted for on average 1 3 0 5 of the total fe while ferrous iron in the coarse fraction appeared to be correlated with the main crustal component the fine fe ii fraction exhibited a more complex behavior the anthropogenic contribution to the aerosol as traced by pb zn and some anions and cations was found to be considerably larger especially during the first 10 days of this cruise than in previously collected samples from the inter monsoon and southwest monsoon of 1995 index terms 0305 atmospheric composition and structure aerosols and particles 0345 4801 0365 atmospheric composition and structure troposphere composition and chemistry 4801 oceanography biological and chemical aerosols 0305 4805 oceanography biological and chemical biogeochemical cycles 1615 4875 oceanography biological and chemical trace elements keywords ferrous iron trace metals aerosol particles indian ocean citation johansen a m and m r hoffmann chemical characterization of ambient aerosol collected during the northeast monsoon season over the arabian sea labile fe ii and other trace metals j geophys res 108 d14 4408 doi 10 1029 2002jd003280 2003

geotechnical properties of dune sands in kuwait abstract extensive dune sands deposits cover specific areas of kuwait and the arabian peninsula dune sands are often an environment hazard during strong winds and sand storms particularly in the summer months the basic geotechnical properties of these deposits are examined by laboratory tests for four sites in kuwait the tests included classification tests compaction characteristics permeability compressibility and shear strength the results are presented and discussed as a first step toward a better utilization or improvement of these soils for local construction purposes

soft sediment deformation of late pleistocene sediments along the southwestern coast of the baltic sea ne germany a 1 460 m long profile of a late glacial subglacial glacio fluvial glacio limnic and glacio deltaic sequence exposed at a cliff section on usedom island sw baltic sea coast is described the sequence is up to 31 m thick and shows sedimentary structures typical of a glacial setting soft sediment deformation is encountered and is associated with changes in lithology these deformations include liquefaction slumping and faulting as the most plausible cause earthquake induced shaking is discussed the associated neotectonic activity is seen as a consequence of the postglacial isostatic crustal rebound as the deglaciation earthquake ratio diminishes with time and as the rebound is phasing out no large earthquakes are anticipated for northern germany although in conclusion the lithosphere of the north german basin has to be regarded as weakened by repeated ice loading and deloading

third order depositional sequences reflecting milankovitch cyclicity the origin of third order depositional sequences remains debatable and in many cases it is not clear whether they were controlled by tectonic activity and or by eustatic sea level changes in oxfordian and berriasian valanginian carbonate dominated sections of switzerland france germany and spain high resolution sequence stratigraphic and cyclostratigraphic analyses show that the sedimentary record reflects milankovitch cyclicity orbitally induced insolation changes translated into sea level fluctuations which in turn controlled accommodation changes beds and bedsets formed in rhythm with the precession and 100 kyr eccentricity cycles whereas the 400 kyr eccentricity cycle contributed to the creation of major depositional sequences biostratigraphical data allow the correlation of many of the 400 kyr sequence boundaries with third order sequence boundaries recognized in european basins this implies that climatically controlled sea level changes contributed to the formation of third order sequences furthermore this cyclostratigraphical approach improves the relative dating of stratigraphic intervals

deformation styles as a key for interpreting glacial depositional environments lithostratigraphical and lithofacies approaches used to interpret glacial sediments often ignore deformation structures that can provide the key to environment of formation we propose a classification of deformation styles based on the geometry of structures rather than inferred environment of formation five styles are recognised pure shear p simple shear s compressional c vertical v and undeformed u these dictate the first letter of the codes the remaining letters conveying the evidence this information can be used to reconstruct palaeostress fields and to infer physical properties of sediments when they deformed individual structures are not diagnostic of particular environments but the suite of structures their relative scale stratigraphical relationships and orientation relative to palaeoslopes and to palaeoice flow directions can be used to infer the environment in which they formed this scheme is applied at five sites in west wales the typical succession is interpreted as subglacial sediments overlain by meltout tills flow tills and sediment flows paraglacial redistribution of glacial sediments is widespread large scale compressional deformation is restricted to sites where glaciers readvanced large scale vertical deformation occurs where water was locally ponded near the ice margin there is no evidence for glaciomarine conditions copyright 2003 john wiley sons ltd

lithofacies variations within sandur deposits the role of runoff regime flow dynamics and sediment supply characteristics abstract the icelandic sandur plains have for long acted as classic sites for models of braided river behaviour and of associated lithofacies assemblages however many of the icelandic sandurs are subject to repeated catastrophic flood events or jokulhlaups which are likely to have played a significant role in sandur construction established lithofacies models based on the icelandic sandurs have failed to take account of the varying runoff regimes which characterise the different sandur environments in addition sediment inputs to sandur channel systems are highly variable fluctuating in response both to varying runoff patterns and to advance and retreat of the source glacier that affect sediment availability within the proglacial zone this paper describes the main lithofacies types and vertical profiles that characterize the sandurs of south iceland and demonstrates that they can largely be attributed to extreme runoff events with few deposits typical of braided river facies occurring within the sedimentary record a preliminary qualitative model is developed that allows interpretation and prediction of vertical lithofacies profiles derived from glacial outwash in terms of i the drainage mechanism which in turn controls the dominant runoff population ii sediment availability and iii the spatial variability in flow dynamics

field occurrences of liquefaction induced features a primer for engineering geologic analysis of paleoseismic shaking discussed in this paper are the factors that control the typical manifestations of liquefaction that are found in continental field settings the factors are given mainly in terms of the local geologic field situation and the geotechnical properties there a meaningful interpretation of liquefaction based data for quantitative analysis of paleoseismic shaking requires understanding of both geologic and geotechnical roles in the mode of ground failure at a specific site recommendations are made for the size of the field area that must be searched for liquefaction effects in order to develop adequate data for engineering geologic geotechnical analyses of paleoseismicity the areal extent must be based on an appreciation that the tectonic situation can cause seismically induced liquefaction effects to form in some locales but not in others nearby even for a strong earthquake in the region our guidelines for the conduct of the field search and preliminary analysis of the data relate to three issues for which liquefaction features are especially useful in answering has there been strong holocene latest pleistocene shaking in the region where was the tectonic source and what was the strength of shaking understanding of the various factors that control the manifestations of liquefaction effects which we present in this paper is essential for developing credible answers to these questions

chemical characterization of atmospheric dust from a weekly time series in the north red sea between 2006 and 2010 abstract atmospheric dust loads and chemical compositions serve as a key link between global climate patterns and marine biogeochemical cycles the primary source of atmospheric dust in the world today is the sahara arabian desert belt although this source was also active during the quaternary the interpretation of paleo dust records and their effects on marine ecosystems is complicated by the scarcely reported atmospheric load patterns of bioavailable phases i e water and acid leachable phases and present day contamination of anthropogenic components this study reports a multi annual time series of atmospheric dust loads 2006 2016 and their chemical compositions 2006 2010 collected in the north gulf of aqaba north red sea at a weekly to bi weekly resolution major and trace element abundances in each sample are reported for three fractions water soluble salts carbonates and oxides weak acid leach and al silicates dust loads vary seasonally from low values in late summer 20 30 g m 3 to higher values in the fall and highest values in late winter and early spring 150 250 g m 3 major and trace element abundances allow to distinguish between the sources and chemical compositions that dominate high and low dust loads in each season the water leachable fraction l0 is relatively enriched in na ca k and mg the acid leachable fraction l1 is enriched in ca as well as na al mg zn cd and pb and the silicate residue l2 in al and fe high dust loads occurring mainly during winter and spring months are characterized by low mg ca l1 l2 low k al and na al l1 and high ca al l1 high mg al l2 and relatively un weathered l2 contents high dust load intervals during winter months are characterized by low passing air masses originating from the sahara while the ambient winter dust low dust load is associated with proximal source regions from the east sahara and arabian peninsula during late winter and spring months high dust loads originate from central and west sahara and to a lesser extent from north sahara low dust loads characterize the summer with limited compositional variability relative to winter spring months summer dust is generally characterized by high k al l1 ratios relative to late winter and spring it is also relatively high in anthropogenic trace elements in the l0 and l1 fractions e g zn al pb al cr al ni al and v al whereby back trajectories indicate the source of these components is primarily from south and east europe the total load ng m 3 of anthropogenic trace elements however remains higher during winter and spring stemming from the overall significantly higher dust loads characterizing this time window the temporal load patterns of important micronutrients such as fe cd zn cu ni and others in the bio available phases l0 l1 are not correlated with major nutrients or chlorophyll a sea surface concentrations suggesting that the atmospheric dust plays a limited role in driving primary productivity in the oligotrophic surface waters of the gulf of aqaba on a wider scale the results provide unique chemical fingerprinting of sahara arabian dust that can be applied to reconstruct past trends in dust loads recorded in deep sea cores and other geological archives from this and other regions

glacier surge mechanism 1982 1983 surge of variegated glacier alaska the hundredfold speedup in glacier motion in a surge of the kind the kind that took place in variegated glacier in 1982 1983 is caused by the buildup of high water pressure in the basal passageway system which is made possible by a fundamental and pervasive change in the geometry and water transport characteristics of this system the behavior of the glacier in surge has many remarkable features which can provide clues to a detailed theory of the surging process the surge mechanism is akin to a proposed mechanism of overthrust faulting

the sedimentary record and rates of quaternary vertical tectonic movements in nw poland abstract analysis based on drilling lithostratigraphic geophysical and geodetic data showed that the spatial differentiation pattern of the pleistocene cover displays a direct connection with the structural pattern of the permo mesozoic complex the main features of the pleistocene cover such as the thickness stratigraphic section facies variability and the shape of the sub quaternary surface are adapted to the distribution of local permo mesozoic tectonic elements salt tectonic folds grabens and singular blocks this is expressed by a reduction in the thickness and stratigraphic section of pleistocene sediments overlying uplifted tectonic elements in relation to those which were lowered facies variability within the pleistocene complex is in many places connected with the location of salt tectonic folds and this connection is manifested by the gradual disappearance of water laid series over salt anticlines the most intensive isostatically driven vertical displacements occurred during the cromerian holsteinian and eemian interglacial periods transformation of repeated levelling data allowed the velocity of recent vertical displacements between examined tectonic elements to be estimated at 0 3 2 0 mm yr and this is comparable to the velocity of pleistocene movements the pleistocene displacements between tectonic elements exerted a decisive influence on the development of their glaciogenic sedimentary cover

the 1890 surge end moraine at eyjabakkajokull iceland a re assessment of a classic glaciotectonic locality abstract the glaciotectonic architecture and sequential evolution of the eyjabakkajokull 1890 surge end moraines in iceland were studied for understanding better the formation and evolution of glaciotectonic end moraines and their relation to glacier dynamics based on morphological geological and geophysical data from terrain cross profiles cross sections and ground penetrating radar profiles we demonstrate that three different qualitative and conceptual models are required to explain the genesis of the eyjabakkajokull moraines firstly a narrow single crested moraine ridge at the distal end of a marginal sediment wedge formed in response to decoupling of the subglacial sediment from the bedrock and associated downglacier sediment transport secondly large lobate end moraine ridges with multiple closely spaced narrow asymmetric crests formed by proglacial piggy back thrusting thirdly a new model shows that moraine ridges with different morphologies may reflect different members of an end moraine continuum this is true for the eastern and western parts of the eyjabakkajokull moraines as they show similar morphological and structural styles which developed to different degrees the former represents an intermediate member with decollement at 4 5 m depth and 27 33 shortening through multiple open anticlines that are reflected as moderately spaced symmetric crests on the surface the latter represents an end member with decollement at about 27 m depth and 39 horizontal shortening through multiple high amplitude overturned and overthrusted anticlines appearing as broadly spaced symmetric crests we propose that the opposite end member would be a moraine of multiple symmetric wide open anticlinal crests of low amplitude our data suggest that the glacier coupled to the foreland to initiate the end moraine formation when it had surged to within 70 190 m of its terminal position this indicates a time frame of 2 6 days for the formation of the end moraines

palaeoseismic structures in quaternary sediments of hamburg nw germany earthquake evidence during the younger weichselian and holocene investigations at a construction site in hamburg nw germany exposed palaeoseismic structures from moderate to strong earthquakes based on the large size of large blowout clastic dykes being up to 2 0 m wide and 2 5 m high as well as the occurrence of infill structures erratics rafts of up to 9 kg in weight seismites s s and decimetre scale folds or seismoslumps the magnitude of the earthquakes could be in the order of up to m 6 this is significantly higher than previously assumed for prehistorical seismic events in nw germany the structures are assigned to earthquakes possibly related to nw se oriented faults that are evident in lidar and sar surface interpretations organic material from blowout related infill bowls assumed to be synchronously formed collapse depressions are analysed for 14c ages the dates reveal ages between 31 500 and 1200 14c cal a bp indicating five prehistoric earthquakes accordingly three of these earthquakes occurred before and after the main weichselian glaciation phase ca 31 350 26 850 and 18 980 14c cal a bp and two occurred during the subatlantic ca 4900 and 1200 14c cal a bp the weichselian events indicate seismic activity in the ice marginal zone during or following interstadials dansgaard oeschger events as well as suggesting that advancing ice sheets foster earthquakes

sedimentological evidence of pleistocene earthquakes in nw poland induced by glacio isostatic rebound abstract soft sediment deformation structures are abundantly present in two levels within warthanian eemian lacustrine sediments at siekierki near the polish german border the two event horizons show intense folding collapse sag and load structures indicative of liquidization and fluidization the structures must have been caused by sudden shocks most probably resulting from earthquakes that were induced by glacio isostatic rebound probably after the warthanian deglaciation such seismites have not been previously recognized in polish quaternary sediments they provide supporting evidence for glacio isostatic movements that were interpreted up till now based on drilling lithostratigraphic geophysical and geodetic data the recognition of seismites in nw poland may help recognize other deformed event horizons in pleistocene sediments as glacio isostatic or neotectonic seismites

chemical oceanography of the persian gulf abstract measurements of basic hydrographic properties nutrient elements alkalinity and total carbon dioxide were made in the persian gulf in february and march 1977 on r v atlantis ii cruise 93 the results show clearly the penetration into the gulf of surface indian ocean water initially of 36 5 salinity which is carried northwards along the iranian coast gradually increasing in salinity to more than 40 the inflowing surface water is high in phosphate 1 0 0 5 moles kg 1 due to upwelling induced by the north east monsoon however nitrate levels are at or below the detection limit and nitrogenous nutrients appear to be limiting the seawater carbonate system is greatly perturbed by the precipitation of large quantities of calcium carbonate the alkalinity salinity relationship shows that the greatest carbonate loss occurs in the shallow waters of the trucial coast where up to 125 moles kg 1 of caco3 have been lost from the water dense saline low specific alkalinity water formed in the shallows appears to migrate down slope to augment the outflowing waters in the deeper part of the gulf the outflow of the tigris euphrates and karun rivers to the north provides an intense but low capacity signal of low salinity high specific alkalinity waters large amounts of co2 are also fixed by photosynthetic processes the classical mediterranean type of circulation is plainly revealed the residence time of water within the persian gulf is approximately 2 5 yr

use of liquefaction induced features for paleoseismic analysis an overview of how seismic liquefaction features can be distinguished from other features and how their regional distribution and properties of source sediment can be used to infer the location and strength of holocene paleo earthquakes abstract liquefaction features can be used in many field settings to estimate the recurrence interval and magnitude of strong earthquakes through much of the holocene these features include dikes craters vented sand sills and laterally spreading landslides the relatively high seismic shaking level required for their formation makes them particularly valuable as records of strong paleo earthquakes this state of the art summary for using liquefaction induced features for paleoseismic interpretation and analysis takes into account both geological and geotechnical engineering perspectives the driving mechanism for formation of the features is primarily the increased pore water pressure associated with liquefaction of sand rich sediment the role of this mechanism is often supplemented greatly by the direct action of seismic shaking at the ground surface which strains and breaks the clay rich cap that lies immediately above the sediment that liquefied discussed in the text are the processes involved in formation of the features as well as their morphology and characteristics in field settings whether liquefaction occurs is controlled mainly by sediment grain size sediment packing depth to the water table and strength and duration of seismic shaking formation of recognizable features in the field generally requires a low permeability cap above the sediment that liquefied field manifestations are controlled largely by the severity of liquefaction and the thickness and properties of the low permeability cap criteria are presented for determining whether observed sediment deformation in the field originated by seismically induced liquefaction these criteria have been developed mainly by observing historic effects of liquefaction in varied field settings the most important criterion is that a seismic liquefaction origin requires widespread regional development of features around a core area where the effects are most severe in addition the features must have a morphology that is consistent with a very sudden application of a large hydraulic force this article discusses case studies in widely separated and different geological settings coastal south carolina the new madrid seismic zone the wabash valley seismic zone and coastal washington state these studies encompass most of the range of settings and the types of liquefaction induced features likely to be encountered anywhere the case studies describe the observed features and the logic for assigning a seismic liquefaction origin to them also discussed are some types of sediment deformations that can be misinterpreted as having a seismic origin two independent methods for estimating prehistoric magnitude are discussed briefly one method is based on determination of the maximum distance from the epicenter over which liquefaction induced effects have formed the other method is based on use of geotechnical engineering techniques at sites of marginal liquefaction in order to bracket the peak accelerations as a function of epicentral distance these accelerations can then be compared with predictions from seismological models

millennial scale variability during the last glacial the ice core record the oxygen isotope records from greenland ice cores show a very strong reproducible pattern of alternation between warm greenland interstadials gi and cold greenland stadials gs at millennial scale during the last glacial period here we summarise what is known about this variability from ice core records the typical cycle has a sawtooth pattern with a very rapid warming event occurring in a few decades a slow cooling trend and then a final fast cooling 25 such events have been numbered in the last glacial the recent gicc05 age scale provides the best available age scale that can be directly applied to this stratigraphy and we summarise the timing of the warming events and the length and strength of each event the greenland stratigraphy can be transferred to other records if we make assumptions about the contemporaneous nature of rapid events in different archives other parameters such as the snow accumulation rate and the concentration of terrestrial dust and sea salt recorded in the greenland cores also show a strong contrasting pattern between gi and gs methane concentrations are generally high during gi and lower during gs with the increase from gs to gi occurring within a century antarctic ice cores show a different pattern each gi has an antarctic counterpart but antarctica appears to warm while greenland is in a gs and cool during gi these changes are consistent with a mechanism involving ocean heat transport but the rapid nature of warmings poses a challenge for modellers while the rapid methane changes pose questions about the pattern of land biosphere emissions during the glacial that are also relevant for understanding glacial interglacial methane variability

time contrasting palaeobiogeographies among hauterivian lower aptian rudist bivalves from the mediterranean tethys their climatic control and palaeoecological implications abstract from the mediterranean tethys the hauterivian barremian rudist genera lovetchenia agriopleura pachytraga and offneria simplex show contrasting palaeobiogeographies through time lovetchenia is a western european form in the hauterivian whereas it is an eastern european and apulian form in the late barremian and early aptian agriopleura is also a western european form in the late hauterivian and barremian p p whereas in the early aptian this genus is only found on the southern tethyan margin pachytraga documented from the hauterivian of both the european and southern tethyan margins disappeared during the barremian and re occupied western europe and some parts of africa during the early aptian offneria simplex a barremian form from the caribbean province is recorded in the uppermost lower barremian of se france the regional disappearance of these taxa is not linked to platform or rudist community demise whereas community changes reflect the resulting modifications in biodiversity there is a good correspondence between the regional disappearance of western european taxa cooling events documented by oxygen isotope studies and biological interchanges between the boreal and tethys realms the regional disappearance of lovetchenia and possibly pachytraga are coeval with the pseudothurmannia ohmi cooling episode whereas that of agriopleura is coeval with the ancyloceras vandenheckii cool episode by contrast the intrusion of offneria simplex in western europe coincides with the coronites darsi warm peak thermal shifts between cool and warm episodes fluctuate from 3 to 5 c and the thermal threshold assumed to control the demise of western european taxa is in the range of 18 to 20 c a value similar to those controlling the geographic distribution of modern coral reefs or the boundary between tropical and subtropical seas the southward displacement of the rudist biomes also accounts for the migration of climatic belts and a decreasing of 3 to 5 c in palaeotemperatures spatial contractions of lovetchenia and agriopleura biomes and the o simplex intrusion suggest that these rudists were more sensitive than others to the thermal regime this observation shows that rather than considering rudists in general as tropical some of them may have been both tropical and subtropical and others tropical for pachytraga other factors than temperature possibly oceanographic changes may have been responsible for the overall mediterranean disappearance of this genus in the barremian

palaeoseismic structures in quaternary sediments related to an assumed fault zone north of the permian peissen gnutz salt structure nw germany neotectonic activity and earthquakes from the saalian to the holocene abstract this study reports on neotectonic deformation represented as faults graben and horst structures which have been found in the uppermost 10 m of quaternary sediments consisting mainly of saalian glaciofluvial and weichselian periglacial material in northern germany that is generally considered as a low seismicity area an area with up to 35 faults in a 60 m wide zone exhibits mainly extensional structures most of those are se nw oriented and in some cases ne sw soft sediment deformation structures include sand blows blowout related infill structures and growth faults small scaled soft sediment deformation structures are also found based on the large size of the sand blows and the widespread occurrence of small scaled soft sediment deformation structures the magnitude of the earthquakes is estimated in the order of m 5 5 single faults exhibit a displacement of a few metres because some faults are overlain by unfaulted sandur sediments the system has been active over at least 200 ka saalian several faults extend through the weichselian periglacial layer to the present ground surface proving ongoing deformation during the weichselian lateglacial and or the holocene this major activity during the saalian and the weichselian points to the activation of old tectonic structures a possible process can be the glacial loading and unloading associated with the isostatic rebound holocene and late holocene seismic events are shown by the penetration of the weichselian lateglacial periglacial layer by faults and sand blows as well as a possible blowout related bowl with organic material and corresponding young 14c dates of

environmental control and dynamics of lower jurassic bivalve build ups in the trento platform southern alps italy abstract bivalve molluscs show a short and peculiar early jurassic evolutionary phase characterized by the lithiotis sensu lato fauna mainly represented by the three monospecific genera lithiotis cochlearites and lithioperna these bivalves with stick like or flattened large shells are mostly restricted to the pliensbachian they have a wide geographical distribution occurring both in tethyan and panthalassian carbonate platforms where considerable biogenic accumulations formed they were common on the trento platform southern alps where they occur in the rotzo formation calcari grigi group this formation was deposited in a tropical lagoon which was closed seawards by oolitic shoals and bars and bordered landwards by marshes the lithiotis s l fauna of the trento platform seems to be restricted to the upper pliensbachian it appeared after a eutrophic phase with recurrent low oxygen and brackish conditions and flourished in meso to oligotrophic waters the stratigraphic and geographic distributions of each genus are compared to the environmental development of the rotzo formation in order to highlight limiting environmental factors and ecological requirements lithioperna occurs throughout the whole formation it is the most eurytopic genus well adapted to dysaerobic habitats and with higher ecomorphic plasticity than the other two genera it frequently occurs in the life position giving rise to densely packed fan like or book like aggregates lithiotis required aerobic and euhaline marine conditions and is common in the middle part of the formation where mesotrophic conditions prevailed this genus is rarely preserved in the theoretical vertical life position probably due to lower shell stability and a less effective attachment modality cochlearites is the most common genus of the rotzo formation this genus inhabited euhaline to slightly hypersaline marine environments occurring in the upper part of the formation prevailing in oligotrophic conditions lithiotis s l fauna gave rise to biogenic accumulations with an elevation of a few decimeters to several meters above the sea bottom and with a lateral extension ranging from ten to several hundred meters therefore these accumulations represent biological build ups which document four developmental phases colonization aggradation progradation and demise the colonization phase is represented by pioneering individuals which were cemented or byssally attached to a bioclastic coarse grained storm layer which constituted the hard substrate for larval attachment the aggradation phase produced the core of the build up and its elevation above the sea bottom the core is mostly represented by individuals which acted as bafflers commonly with an apparently chaotic fabric the lithiotis s s and cochlearites cores are generally mud supported and contain loosely packed to dispersed specimens occasionally preserved in life position the lithiotis s s and cochlearites build ups can be defined as bivalve mounds the cores of the lithioperna build ups are skeletal supported with shells mostly preserved in life position which characterize the bivalve reefs the prograding phase produced lateral additions to the build up flanks of oblique and imbricated articulated individuals the flanks grew centrifugally from the core and represent the most conspicuous part of the build ups ranging from 10 to 20 times the size of the core and occasionally extending over several hundred meters

elemental ratios and enrichment factors in aerosols from the us geotraces north atlantic transects abstract the north atlantic receives the highest aerosol dust input of all the oceanic basins dust deposition provides essential bioactive elements as well as pollution derived elements to the surface ocean the arid regions of north africa are the predominant source of dust to the north atlantic ocean in this study we describe the elemental composition li na mg al p sc ti v cr mn fe co ni cu zn as se rb sr cd sn sb cs ba la ce nd pb th u of the bulk aerosol from samples collected during the us geotraces north atlantic zonal transect 2010 11 in order to highlight the differences between a saharan dust end member and the reported elemental composition of the upper continental crust ucc and the implications this has for identifying trace element enrichment in aerosols across the north atlantic basin as aerosol titanium ti is less soluble than aerosol aluminum al it is a more conservative tracer for lithogenic aerosols and trace element to ti ratios however the presence of ti rich fine aerosols can confound the interpretation of elemental enrichments making al a more robust tracer of aerosol lithogenic material in this region

late quaternary ice sheet extents in northeastern germany inferred from surface exposure dating abstract we determined in situ cosmogenic 10 be ages for 11 boulders on the hoher flaming ice marginal belt and five boulders on the gerswalder moraine a recessional moraine of the pomeranian stage previous time estimations for the deposition of these moraines along the southern margin of the scandinavian ice sheet sis in northeastern germany are mostly based on geomorphology and stratigraphy and on few radiocarbon dates and recently published surface exposure ages in the case of the pomeranian moraine our new exposure ages range from 21 7 1 2 10 be ka to 172 6 6 0 10 be ka for the hoher flaming ice marginal belt the wide range of exposure ages may reflect episodic ice marginal belt modification due to intensified erosion by meltwater channeled in the baruther urstromtal ice marginal valley accompanied by long lasting erosional processes like solifluction and aeolian deflation for the gerswalder moraine our new exposure ages range from 12 3 0 6 10 be ka to 16 6 1 0 10 be ka excluding the youngest sample ber 97 03 we calculated error weighted mean ages ranging from 15 2 0 5 10 be ka to 16 0 0 5 10 be ka n 4 depending on choice of scaling methods surface erosion and snow cover these results firmly establish the position of the southern margin of the sis in northeastern germany during the gerswalder substage a recessional phase of the pomeranian stage

species richness and abundance patterns of tethyan cretaceous rudist bivalves mollusca hippuritacea in the central eastern mediterranean and middle east analysed from a palaeontological database abstract data about the stratigraphical and regional distribution of cretaceous rudist bivalves in the central eastern mediterranean and middle east from the barremian to the maastrichtian have been compiled in a taxonomic databank system the investigated region comprises northern central and southern regions of the cretaceous tethys the regionally different quality of taxonomic data is critically discussed both species richness and abundance number of species records peak in the early aptian late cenomanian and early campanian temporal patterns in species richness are examined in relation to evolutionary innovations of the group crises in species richness and abundance during the early and mid cretaceous were coeval with oceanic anoxia associated with platform drowning also regional emergence affected large parts of the apulian plate and other central tethyan carbonate platforms during the mid cretaceous period of globally high sea level so that these crises can be attributed to regional environmental perturbations induced by either oceanic anoxia or tectonic movements the cenomanian turonian transition marks an important faunal turnover as indicated by the demise of taxonomic groups which are characterised by recumbent ecological morphotypes and predominantly aragonitic shells during the turonian they were replaced by associations dominated by largely calcitic radiolitidae and hippuritidae among which elevator morphotypes dominated the stratigraphy of many post turonian deposits in the studied region is too imprecise for a detailed analysis of late cretaceous distributional patterns and the demise of rudists during the maastrichtian in particular the regional pattern of species richness and abundance is similar throughout most of the investigated region a notable exception is the broad north eastern african shelf from libya to lebanon where rudists were almost completely absent after the coniacian this coincided with shallow water phosphorite and black shale formation on the extended shelf of this region indicating the upwelling of nutrient rich waters and stagnant conditions during this time campanian maastrichtian species rich associations thrived along the north eastern afro arabian margin now exposed in south eastern turkey iran the united arab emirates uae and oman this region forms the single distinct faunal province during the cretaceous in the studied region as indicated by an endemism of 40 at the genus level the low species richness and abundance of hippuritidae on turonian maastrichtian central tethyan carbonate platforms when compared with regions having mixed calcareous siliciclastic sedimentation is interpreted to argue against a widespread photosymbiosis in the group several aspects of this study highlight the importance of regional tectonic and oceanographic controls of distributional and perhaps also evolutionary patterns of rudist bivalves their delineation still suffers from the regionally different quality of stratigraphical and taxonomic data