pre and post collisional depositional history in the upper and middle bengal fan and evaluation of deepwater reservoir potential along the northeast continental margin of india abstract the bengal fan is the largest submarine fan in the world that has formed as a result of high sediment transport from the himalaya by the ganga brahmaputra river system the himalaya was formed as a result of the collision between the eurasian and indian plates the initiation of this collision known as soft collision occurred around 59 ma whereas the major collision known as hard collision took place around 15 ma ago prior to the collision sediments into the bay of bengal were derived from the northwest by relatively smaller river system like mahanadi godavari the switching of river systems with time was not distinct but gradational in the post collision period the sediment input from the nw was masked in most instances because of rapid sediment supply from the himalaya to the north pre collisional sediment dispersal pattern from the nw was largely affected by pre existing basement high known as 85 e ridge this ridge was submerged during the post collisional period post collisional sediments are commonly referred to as the bengal fan sediments and show huge accumulation along the shelf and beyond high resolution 2d seismic data acquired along a corridor covering the upper middle and distal parts of the present day active bengal fan system indicates that the fan has prograded southward with time because of continuously increasing sediment supply and has therefore masked the effect of eustacy the present day geometry of the fan shows a single active canyon and an associated single active fan the active channel shows typical meandering pattern that shifts laterally with time the seismic facies analysis indicates that both the pre and post collision basin has significant hydrocarbon potential the thermogenic model is best suited for modeling source rock maturity in the pre collision basin whereas both biogenic and thermogenic models best explain source rock maturity in the post collision younger bengal fan the wedge out against the 85 e ridge is considered to be one of the important play types for hydrocarbon exploration in the deeper part of the basin on the other hand the channel levee complexes and frontal splay basin floor fan are the possible target areas for petroleum exploration in relatively younger bengal fan deposits

sedimentation of biogenic constituents during the last century in western bransfield and gerlache straits antarctica a relation to currents primary production and sea floor relief abstract as part of the fruela experiment 11 sediment cores were recovered from the bellingshausen sea the western bransfield and gerlache straits antarctic peninsula to determine the spatial distribution of organic carbon oc biogenic silica bsi and nitrogen n in the sediment under regions of known irregular primary production rates pprs oc bsi and n contents ranged from 0 3 to 1 2 from 5 7 to 20 4 and from 0 03 to 0 17 respectively apparent mean sediment accumulation rates sars varied between 0 25 and 3 11 mm year 1 220 and 1750 g m 2 year 1 central gerlache and western bransfield straits the orleans canyon had the highest biogenic constituents contents and sediment accumulation rates whereas the northern coast off snow island bellingshausen sea showed the lowest values central gerlache strait with the highest primary production rates in the study area was the only region where the oc and bsi contents in the sediment corresponded to the photosynthetic activity in the euphotic zone above it at the extremes of gerlache strait as in western bransfield strait sediment focusing by currents enhanced by depressions in the sea floor contributed to develop regions with high biogenic constituent concentrations whereas at the bellingshausen sea and western gerlache strait winnowing by currents may drift away the biogenic material exported from the euphotic zone apparently bottom relief and currents rather than solely depth determined the modern distribution and accumulation rates of biogenic particulate matter in the study area paleoceanographic interpretations of the sedimentary record from antarctic marginal seas such as gerlache and bransfield straits should consider that focusing due to lateral transport and sea floor morphology and the preferential degradation of oc relative to bsi may increase to an important degree the biogenic contents in the sediment especially the opal oc and bsi accumulation in antarctic marginal seas could be as important as the broad continental shelves despite large spatial differences

using pebble lithology and roundness to interpret gravel provenance in piedmont fluvial systems of the rocky mountains usa abstract clast populations in piedmont fluvial systems are products of complex histories that complicate provenance interpretation although pebble counts of lithology are widely used the information provided by a pebble count has been filtered by a potentially large number of processes and circumstances counts of pebble lithology and roundness together offer more power than lithology alone for the interpretation of provenance in this study we analyze pebble counts of lithology and roundness in two contrasting fluvial systems of pleistocene age to see how provenance varies with drainage size the two systems are 1 a group of small high gradient incised streams that formed alluvial fans and terraces and 2 a piedmont river that formed terraces in response to climate driven cycles of aggradation and incision we first analyze the data from these systems within their geographic and geologic context after this is done we employ contingency table analysis to complete the interpretation of pebble provenance small tributary streams that drain rugged mountains on both sides of the santa cruz river southeast arizona deposited gravel in fan and terrace deposits of pleistocene age volcanic plutonic and to a lesser extent sedimentary rocks are the predominant pebble lithologies large contrasts in gravel lithology are evident among adjacent fans subangular to subrounded pebbles predominate contingency table analysis shows that hard volcanic rocks tend to remain angular and even though transport distances have been short soft tuff and sedimentary rocks tend to become rounded the wind river a major piedmont stream in wyoming drains rugged mountains surrounding the northwest part of the wind river basin under the influence of climate change and glaciation during the pleistocene the river deposited an extensive series of terrace gravels in contrast to santa cruz tributary gravel most of the wind river gravel is relatively homogenous in lithology and is rounded to well rounded detailed analysis reveals a multitude of sources in the headwaters and the basin itself but lithologies from these sources are combined downstream well rounded volcanic and recycled quartzite clasts were derived from the headwaters precambrian igneous and metamorphic clasts were brought down tributary valleys to the wind river by glaciers and sandstone was added where the river enters the wind river structural basin

the depositional history of the bavarian allgau area at the turn of the tertiary quaternary northern alpine foreland germany a set of paleogeological maps abstract the northern alpine foreland in southwestern bavaria is characterized by miocene molasse overlain by deposits of glacial and glacifluvial origin one peculiarity of this region is the occurrence of extended fluvial terraces of the upper pliocene lower pleistocene which can be subdivided into several distinct levels from these sediments good information on the stratigraphy palaeogeography and palaeoenvironment of the illerglacier foreland at the plio pleistocene transition as well as the influence of tectonics can be derived sediments of the osm obere suswassermolasse upper freshwater molasse reflect the change of general flow direction from west to east during the pannonien by tectonics causing the development of the easterly flowing danubian river system according to the general dip of the landscape the predecessors of the present day rivers iller lech and ammer flowed northeast initiated by cold climatic conditions at the onset of pleistocene the changes in fluvial accumulation and vertical erosion resulted in a number of gravel deposits terraces of five biber cold stages document the ancient course of the iller running obliquely to the modern valley orientation as the danube iller divide was cut by brooks the iller river shifted to the northwest at the end of donau complex after this nontectonic change of the flow direction a huge area was covered by gravel deposits as the river development can be reconstructed in detail the preserved sediments are considered to document all upper pliocene lower pleistocene fluvial accumulation and erosion phases in the area under discussion nine cold climatic terrace accumulations can be distinguished up to the end of the olduvai event

preservation potential for late quaternary river alluvium valley sequences of late quaternary alluvial units reflect alluvial preservation as well as alluvial production factors effects of lateral channel migration incision aggradation and channel stability on preservation potential are explored and then considered in the light of 14 available data sets cartographically dated and model data based on lateral channel migration well mapped and dated late quaternary valley unit surveys and composite age frequency plots for dated alluvial units and flood sediments despite much expectable variation between sites and the complex effects of river activity combinations a common characteristic of the data sets examined is the significance of preservation factors lateral migration tends to eliminate older units as it creates new alluvial deposits whereas incision may lead to the preferential preservation of older units beyond the incision slot aggradational environments are likely to preserve more complete records although simultaneous lateral migration may eliminate possibly repeatedly the upper parts of alluvial units the common pattern of inset and incised streams within pleistocene and early holocene fills or bedrock gives finite extent to later units within narrowing valleys so that development of new valley floor units is necessarily at the expense of reprocessing earlier ones floods associated with both slack water deposits and berms are also responsible for the removal of accessible earlier materials thus limiting the preserved record of earlier events in light of these censoring effects of river activities the sequence of preserved late quaternary units within uk sequences is reconsidered it is concluded that preservation potential factors have led to spatial and temporal bias in the alluvial record and that both here and elsewhere preservation potential needs to be considered systematically alongside variable sedimentation resulting from allogenic environmental factors when interpreting the alluvial archive copyright 2003 john wiley sons ltd journal of quaternary science

provenance of the miocene slovenj gradec basin sedimentary fill western central paratethys abstract the slovenj gradec basin represents one of the marginal western basins of the neogene pannonian basin system its sedimentary succession is investigated by combination of field petrographic and geochemical methods the succession is at least 540 m thick and characterised by frequent alternation of conglomerate sandstone siltstone and marlstone deposited in terrestrial brackish and shallow marine environments modal composition of the sandstones indicates that they originated from recycled orogen namely from quartzose sedimentary rocks of the eastern alps and show moderate to absent chemical weathering the results indicate two different tectonic settings a collisional which correlates well with the end mesozoic and cenozoic alpine collision resulting in orogeny and thrusting of the austroalpine nappes and a passive margin related to the early neogene lithospheric extension and subsidence as the result of slab retreat in the carpathian subduction zone which was responsible for the formation of the pannonian basin system in this area where the sediments were subjected to various tectonic events discriminant function diagrams of verma and armstrong altrin are found to be a good tool for their identification and differentiation

river terrace systems in north west europe an archive of environmental change uplift and early human occupation abstract staircases of large scale aggradational river terraces are a notable feature of many valleys in the temperate lattitudes particularly in areas beyond the reach of the erosive activities of pleistocene ice sheets it is now recognized that the cyclic fluctuations of climate during the quaternary have driven the generation of terraces through the direct and indirect influence of both temperature and precipitation on fluviatile activity where fossiliferous deposits are preserved within terrace sequences it is often possible to date these and to correlate them with the oceanic record thus providing an important framework for the evidence of environmental change on land middle and late pleistocene terraces in different areas can commonly be seen to have formed in synchrony with glacial interglacial cycles or with longer periodicity megacycles climatic forcing alone is insufficient to cause terraces to form however uplift is also necessary so that terrace sequences can provide a useful record of crustal movement in northwest europe where some of the best known studies of river terrace sequences have been carried out the fluviatile deposits are also an important repository for palaeolithic artefacts from which a record of early human occupation can be reconstructed

the river orontes in syria and turkey downstream variation of fluvial archives in different crustal blocks the geomorphology and quaternary history of the river orontes in western syria and south central turkey have been studied using a combination of methods field survey differential gps satellite imagery analysis of sediments to determine provenance flow direction and fluvial environment incorporation of evidence from fossils for both palaeoenvironments and biostratigraphy uranium series dating of calcrete cement reconciliation of palaeolithic archaeological contents and uplift modelling based on terrace height distribution the results underline the contrasting nature of different reaches of the orontes in part reflecting different crustal blocks with different histories of landscape evolution upstream from homs the orontes has a system of calcreted terraces that form a staircase extending to 200 m above the river new u series dating provides an age constraint within the lower part of the sequence that suggests underestimation of terrace ages in previous reviews this upper valley is separated from another terraced reach in the middle orontes by a gorge cut through the late miocene early pliocene homs basalt the middle orontes terraces have long been recognized as a source of mammalian fossils and palaeolithic artefacts particularly from latamneh near the downstream end of the reach this terraced section of the valley ends at a fault scarp marking the edge of the subsiding ghab basin a segment of the dead sea fault zone which has been filled to a depth of 1 km by dominantly lacustrine sediments of pliocene quaternary age review of the fauna from latamneh suggests that its age is 1 2 0 9 ma significantly older than previously supposed and commensurate with less uplift in this reach than both the upper and lower orontes two localities near the downstream end of the ghab have provided molluscan and ostracod assemblages that record somewhat saline environments perhaps caused by desiccation within the former lacustrine basin although they include fluvial elements the ghab is separated from another subsiding and formerly lacustrine depocentre the amik basin of hatay province turkey by a second gorge implicit of uplift this time cut through palaeogene limestone the ne sw oriented lowermost reach of the orontes is again terraced with a third and most dramatic gorge through the northern edge of the ziyaret dagi mountains which are known to have experienced rapid uplift probably again enhanced by movement on an active fault indeed a conclusion of the research in which these various reaches are compared is that the crust in the hatay region is significantly more dynamic than that further upstream where uplift has been less rapid and less continuous

spatio temporally variable response of fluvial systems to late pleistocene climate change a case study from central germany abstract the change of the earth s climate and anthropogenic forcing challenge catchment management as the deliberate use of the fluvial system s natural resources depends to some extent on the predictability of the system s variable sensitivity to external impacts the alluvial history of the wetter valley in central germany provides an example of the occurrence of a spatio temporally variable catchment sensitivity to the late pleistocene climate change empirical models that are based on sediment flux controls such as sediment supply transport capacity and gradient serve to explain differential floodplain construction during the early younger dryas the large scale basin upland morphology caused localised divergent cooling impacts and vegetation changes which generated reach scale variable sediment transport system states in the wetter valley the spatial arrangement of reach scale variable response is ascribed to the tectonically driven morphological configuration of the wetter catchment the crucial amplification of differential floodplain construction can be assigned to the spatially variable availability of a surplus of laacher see tephra particles in manner of a pulsed sediment input the ubiquitous tephra cover was previously deposited by the laacher see volcano event in the upper allerod thus the reach scale variable response during the early younger dryas can be deemed to have been climatically triggered but superimposed by an internally driven specific upstream catchment response the documented processes of late quaternary alluviation in the wetter valley imply the need for whole catchment approaches the latter are a prerequisite to reveal the occurrence and causalities of variable fluvial response in relation to external impacts that interact with internal morphological controls this is seen to be crucial to achieve an improved predictability of future environmental change in fluvial landscapes

river terraces and alluvial fans the case for an integrated quaternary fluvial archive abstract the fluvial archive literature is dominated by research on river terraces with appropriate mention of adjacent environments such as lakes despite modern sedimentary basins comprising a significant 88 volume of distributive fluvial systems of which alluvial fans 1 km

evolution of the alluvial fans of the luo river in the weihe basin central china controlled by faulting and climate change a reevaluation of the paleogeographical setting of dali man site abstract the luo river is located in the southern part of the chinese loess plateau and the northern part of the weihe basin in central china in the basin it flows proximal to the site of the luyang wetland core which is an important archive of climate change over the past 1 myr in this region in this paper the contribution of the luo river to the sedimentary record is analyzed by reconstructing the evolution of this river during the middle to late pleistocene it is argued that an alluvial fan of the luo river has contributed to the sedimentary archive until approximately 200 240 ka from this moment onwards the fan became incised and terraces began to form the formation of a new alluvial fan further downstream led to the disconnection of the luo river from the luyang wetland core site we propose that this series of events was caused by the displacement of an intra basinal fault and the resultant faulting forced folding which caused increased relative subsidence and thus increased sedimentation rates at the core site therefore a complete sediment record in the luyang wetland was preserved despite the disconnection from the luo river the chronology of the fans and terraces was established using existing age control u series esr osl pirir 290 and magnetic susceptibility correlation and through correlation of the loess paleosol cover to marine isotope stages based on sedimentological characteristics of the fluvial sequence we suggest that incision of the luo river occurred in two steps small incisions took place at transitions to interglacials and the main incision phases occur at the transition from an interglacial to glacial climate due to the incision basal parts of the oldest luo river alluvial fan are exposed and it is in one of these exposures that the famous dali man skull was retrieved this study shows that the dali man did not live on a river terrace as previously thought but on an aggrading alluvial fan during wet glacial conditions

response of the ganges dispersal system to climate change a source to sink view since the last interstade the forcing of sediment dispersal systems by climate is widely accepted but there remains disagreement on the general responses to climate change such as how resulting signals propagate downstream and ultimately how they are preserved in the stratigraphic record towards a better understanding of these issues this paper presents a comprehensive overview of ganges dispersal system behavior since the last interstade which reveals major coeval responses to changes in the south asian monsoon at 3000 km from its mountain headwaters to deep sea fan the ganges dispersal system is immense and yet shows tight coupling between source area catchment basin and coastal and marine depocenters furthermore system wide responses and downstream transfer of the signal appear to occur at least as fast as current temporal resolution of 1 2 ky this tight linkage of source to sink components is considered a function of the southwest summer monsoon s overwhelming control on regional hydrology about 80 of the ganges discharge and 95 of its sediment load are delivered to the margin during only 4 months making the system extremely sensitive to this seasonal forcing in addition the regional scale and distribution of the monsoon weather system means that changes in atmospheric circulation affect the entire drainage basin rather than local subcomponents finally despite its present intensity strength of the summer monsoon has varied significantly over the past 150 ky under orbitally driven changes in insolation and global glacial boundary conditions the resulting changes in precipitation both well above and below modern values have forced system wide responses ranging from glacier advance retreat to sediment fluxes to the margin and deep sea fan the overall conclusions are 1 that this immense dispersal system responds to multimillennial scale 104 years climate change in a system wide and largely contemporaneous manner and 2 that major sedimentary signals can be transferred rapidly from source to sink with little apparent attenuation furthermore these acute responses to climate change have produced sedimentary stratigraphic features that diverge from traditional sequence models in their nature and timing

incised relict landscapes in the eastern alps abstract we investigate landscape evolution in a region of the alps that has escaped glacial erosion during periodic glaciations of the last million years the research is thus suited to investigate landscaping processes on a longer time scale at the eastern end of the alps morphometric analysis reveals the presence of incised relict landscapes in several regions in the koralpe range topographic analysis is interpreted in terms of the relict landscape being present on both sides of the eastward tilted koralpe block this suggests that the relict landscape is younger than the tilting of the range which is inferred to have taken place between 18 and 16 ma in the pohorje region a relict landscape is developed across the contacts of a 19 ma pluton we use apatite u th he thermochronology to constrain the possible age of the koralpe and pohorje relict landscapes the results indicate that the pohorje massif had cooled below 70 c by about 15 ma suggesting that the relict landscape must be younger consistent with the interpretation of the koralpe range these results suggest that many relict landscapes of the eastern alps may have formed after 15 ma in a period of tectonic quiescence and erosion however in both ranges channel profile projections show that about 387 105 m uplift and incision occurred subsequently this incision is likely to have occurred during the last 6 5 ma in response to the uplift of the whole region it testifies to a renewed and ongoing uplift event that is earlier than the glaciation periods but might easily be confused with impact of glacial erosion elsewhere in the eastern alps

climate forcing of fluvial system development an evolution of ideas starting from traditional ideas on the climatic steering of fluvial system dynamics it appears that there are different kinds of climatic influences on system dynamics they vary from direct climatic forcing like peak precipitation to indirect like permafrost and partial forcing like vegetation vegetation or its absence and not directly climate is considered as the main cause of fluvial incision or deposition during temperate or cold periods however other external factors than climate and non climatic factors such as local basin characteristics like subsoil lithology and relief express their effects on the fluvial systems by their role in the energy balance of the river catchment finally internal factors in fluvial system evolution like thresholds and response time should not be neglected

river incision and terrace formation in the late cenozoic of europe abstract late cenozoic environmental changes which affected european rivers are reviewed focusing especially on those of mid pleistocene times c 1 2 0 8 ma or around mis 22 and thereafter these involved dominating but fluctuating cold climate periglacial conditions shorter but major episodes of glaciation and brief interglacials there were also related sea level and tectonic responses the known history of european rivers in this period is individually varied but is predominantly marked by multiple stages of episodic incision the form of which changed in style at around the mid pleistocene transition it is suggested that the nature of climatic oscillations the dating of incision episodes and the processes that achieve this incision are as yet insufficiently understood fluvial process studies suggest that the onset of incision may broadly relate to changes in slope discharge sediment load and calibre and bedrock erodibility and these may all have been transformed as the direct or indirect result of mid pleistocene climatic changes common properties of basal sediments on strath terraces suggest that it was during the extended but variable cold stage episodes that both valley deepening and lateral widening occurred and that climatic change was the principal driver of episodic deep valley incision

environmental signal propagation in sedimentary systems across timescales abstract earth surface processes operate across erosionally dominated landscapes and deliver sediment to depositional systems that can be preserved over a range of timescales the geomorphic and stratigraphic products of this source to sink sediment transfer record signals of external environmental forcings as well as internal or autogenic dynamics of the sedimentary system here we evaluate environmental signal propagation across sediment routing systems with emphasis on sediment supply qs as the carrier of up system forcings we review experimental numerical and natural examples of source to sink sediment routing and signal propagation during three timescales 1 historic which includes measurement and monitoring of events and processes of landscape change and deposition during decades to centuries 2 centuries to several millions of years referred to as intermediate timescale and 3 deep time we discuss issues related to autogenic dynamics of sediment transport transient storage and release that can introduce noise lags and or completely mask signals of external environmental forcings we provide a set of conceptual and practical tools for evaluating sediment supply within a source to sink context which can inform interpretations of signals from the sedimentary record these tools include stratigraphic and sediment routing system characterization sediment budgets geochronology detrital mineral analysis e g thermochronology comparative analog approaches and modeling techniques to measure calculate or estimate the magnitude and frequency of external forcings compared to the characteristic response time of the sediment routing systems

paleogeographic evolution of the late miocene lake pannon in central europe abstract the paleogeographic evolution of lake pannon within the pannonian basin is reconstructed with eight maps ranging from the middle miocene to the early pliocene the maps are based on the distribution of selected biozones and specific fossils and on complementary sedimentological and seismic information our reconstruction shows that the history of lake pannon can be divided into three distinct intervals an initial stage with low water level which resulted in isolation from the sea at about 12 ma and might have led to temporary fragmentation of the lake an interval of gradual transgression lasting until ca 9 5 ma and a long late interval of shrinkage and infilling of sediments that persisted into the early pliocene the deep subbasins of the lake formed during the transgressive interval in more basinward locations than the deep basins of the preceding sarmatian age the southern shoreline running parallel with the sava and danube rivers along the northern foot of the dinarides changed very little during the lifetime of the lake while the northern shoreline underwent profound changes

pebble abrasion during fluvial transport experimental results and implications for the evolution of the sediment load along rivers 1 in actively eroding landscapes fluvial abrasion modifies the characteristics of the sediment carried by rivers and consequently has a direct impact on the ability of mountain rivers to erode their bedrock and on the characteristics and volume of the sediment exported from upland catchments in this experimental study we use a novel flume replicating hydrodynamic conditions prevailing in mountain rivers to investigate the role played by different controlling variables on pebble abrasion during fluvial transport lithology controls abrasion rates and processes with differences in abrasion rates exceeding two orders of magnitude attrition as well as breaking and splitting are efficient processes in reducing particle size mass loss by attrition increases with particle velocity but is weakly dependent on particle size fragment production is enhanced by the use of large particles high impact velocities and the presence of joints based on our experimental results we extrapolate a preliminary generic relationship between pebble attrition rate and transport stage c where fluvial shields stress and c critical shields stress for incipient pebble motion this relationship predicts that attrition rates are independent of transport stage for c 3 and increase linearly with transport stage beyond this value we evaluate the extent to which abrasion rates control downstream fining in several different natural settings a simplified model predicts that the most resistant lithologies control bed load flux and fining ratio and that the concavity of transport limited river profiles should rarely exceed 0 25 in the absence of deposition and sorting

source to sink sedimentary systems and global carbon burial a river runs through it abstract source to sink sedimentary systems are important settings of carbon cycling serving as sites of carbon transfer between terrestrial and marine reservoirs and as the primary locations for organic carbon burial on earth the age and character of the carbon that is buried at the terminal ends of these systems reflects the sources and transformations of the organic carbon oc throughout their linked terrestrial and marine segments profound differences are observed between large passive and small active margin systems large passive margin systems are characterized by large floodplains and relatively broad shelves where oc has protracted exposure to oxidants rapid burial in prograding subaqueous deltaic clinoforms or bypass to submarine fans however leads to high burial efficiency of terrestrial biospheric oc in some passive margin settings the oc in small active margin systems in contrast follows relatively short pathways from headwaters to seabed this rapid transit facilitated by the important role of storm driven transport in such settings can lead to high oc burial efficiencies the study of oc sources and transformations in contemporaneous source to sink sedimentary systems informs interpretations about the systems in which oc was buried in the geologic past their stratigraphic records of environmental change and their potential to produce petroleum resources

morphodynamics in sediment starved inner shelf submarine canyons lower st lawrence estuary eastern canada abstract the contemporaneous activity and sedimentary processes in a series of inner shelf submarine canyons located in the lower st lawrence estuary were examined using high resolution multibeam bathymetry and backscatter data the presence of crescent shaped bedforms csbs displaced upslope at the bottom of the canyons between 2007 and 2012 indicates that they are currently active through the remobilization of sediment by gravity flows however the shelf and shores of the region are characterized by the absence of sediment our results indicate that gravity flows currently eroding the canyon floors do not transport new material downslope coming from the shelf but rather remobilize in situ deglacial sediments within the canyon thalweg we suggest that slope failures and internal tides waves are responsible for sediment remobilization in these canyons although their role in the upslope migrating csbs is unclear this paper provides evidence that sediment supply is not a prerequisite for the modern activity of inner shelf submarine canyons when processes such as slope failures and internal tides waves are frequent enough to remobilize in situ sediments

the heidelberg basin upper rhine graben germany a unique archive of quaternary sediments in central europe abstract the heidelberg basin in the german part of the northern upper rhine graben hosts one of the thickest successions of plio pleistocene sediments in central europe from reflection seismic surveys and new research boreholes it is known that pleistocene sediments amount to more than 500 m thickness the basin sediments originated both from local source areas i e the highlands along the graben shoulders and from regional source areas i e the alps although temporal hiatuses probably exist the deposits are expected to be more or less complete because this part of the upper rhine graben has undergone continuous subsidence in the past currently the heidelberg basin is under investigation by a scientific drilling project new cored boreholes have been realized at three different locations spaced 15 km from each other this concept provides complementing information and enables a detailed characterization of the predominantly fluvial deposits the project aims to develop a stratigraphic reference profile of the quaternary for this region north of the alps to understand how the sedimentation was controlled by tectonics and past climate change and to derive proxy data of environmental changes the new core material demonstrates that the heidelberg basin would be a possible key location for quaternary stratigraphy in central europe information about pleistocene periods of cold and warm climate is found within this one sediment succession in superposition the temporal resolution of the sediment succession is high due to its mid continental location it links northern and southern europe as well as western and eastern europe based on a detailed analysis of the new drill cores a new lithostratigraphy for the northern part of the upper rhine graben is developed in a first step with the mannheim formation the ludwigshafen formation the viernheim formation and the iffezheim formation four new lithostratigraphic units of the northern upper rhine graben are officially introduced furthermore a new debate about identification of basal quaternary arises from the new research boreholes whereas during the last decades petrological markers were used to define basal quaternary i e the first deposition of alpine sediments or carbonate content this definition fails in the depocentre of the basin several rock physical properties e g the natural gamma radiation and the magnetic susceptibilities reveal significant changes at the basal quaternary the driving forces of these changes have to be studied in more detail in the future

holocene and modern sediment budgets for the ganges brahmaputra river system evidence for highstand dispersal to flood plain shelf and deep sea depocenters the partitioning of fluvial sediment load across continental margins is an important control on strata formation and sequence development however few quantitative sediment budgets that encompass entire dispersal systems exist for the ganges brahmaputra river system sediment discharge is estimated to be 10 9 t yr at gauging stations 300 km inland of the coast but little has been known of the downstream fate of this material geochronological geophysical and stratigraphic investigations of the lowland flood plain delta plain and shelf help to delineate the extent of holocene fill and allow calculation of a first order sediment budget results reveal that 1500 10 9 m 3 of sediment fill has been sequestered within the flood plain and delta plain since ca 7000 yr b p or about one third of the annual discharge the remaining load appears to be apportioned between the prograding subaqueous delta 1970 10 9 m 3 and transport to the deep sea bengal fan via a nearshore canyon modern 100 yr budget estimates based on short term accretion rates indicate a similar dispersal pattern and show that contemporaneous deposition continues within these disparate depocenters the roughly equal partitioning of sediment among flood plain shelf and deep sea settings reflects the respective influence of an inland tectonic basin a wide shelf and a deeply incised canyon system the findings also support new sequence stratigraphic models for these settings and indicate the important insight that modern river deltas can provide for ancient margin systems furthermore results affirm that values of riverine sediment flux to the oceans may be considerably overestimated by not accounting for loss to the flood plains downstream of the gauging stations

chronology of fluvial terrace sequences for large atlantic rivers in the iberian peninsula upper tagus and duero drainage basins central spain abstract this work analyses the chronology of fluvial terrace sequences of the two most important fluvial basins from central spain draining to the atlantic ocean upper tagus and duero drainage basins both basins evolved under similar mediterranean climatic conditions throughout the pleistocene and present comparable number of fluvial terraces 16 17 after excluding the higher terrace levels of the tagus t1 t5 entrenched in the rana surface these higher ranizo terraces was formed in response to fan head trenching in this high alluvial piedmont 220 m and therefore not properly controlled by quaternary fluvial downcutting the study accomplishes the implementation of multiple regression analyses for terrace height age relationships to transform relative terrace heights above the present river thalwegs i e 100 m in numerical ages a height age transference function has been developed on the basis of preliminary statistical geochronological approaches proposed for central spain the resultant height age transference function gather 73 published geochronological data for terrace sequences featuring a 3rd order polynomial function r2 0 90 this function describes the overall trend of valley downcutting for the last c 2 3 ma in central spain and is used to assign numerical ages to terrace levels at different relative elevation

cyclones and tides as feeders of a submarine canyon off bangladesh extremely high annual sedimentation rates of about 50 cm yr at the head of the submarine canyon swatch of no ground which connects the submarine delta of the ganges brahmaputra to the bengal deep sea fan were estimated by 210 pb and 137 cs gamma spectrometry the sediment in the canyon at 228 m water depth consists of graded sand and silt layers and laminated mud the sand and silt layers are assumed to have been deposited by tropical cyclones whereas the intercalated laminated mud is thought to have been deposited by daily variations of tidal currents the graded layers correlate well with the historical record of cyclones and allow an annual fine tuning the rapid infill of the canyon head is caused by trapping of suspended sediment that has been mobilized by storms and tides on the delta topset the sediment is stored only temporarily in the canyon head slides slumps and earthquakes occasionally remove and transfer it by turbidity currents to the deep sea fan the focusing effect of the canyon and the subsequent stepwise export of sediment probably combined with erosion of the canyon floor explain the long term regional stability of this canyon and probably other shelf canyons

timing of european fluvial terrace formation and incision rates constrained by cosmogenic nuclide dating abstract age constraints of late cenozoic fluvial terraces are important for addressing surface process questions related to the incision rates of rivers or tectonic and climate controls on denudation and sedimentation unfortunately absolute age constraints of fluvial terraces are not always possible and many previous studies have often dated terraces with relative age constraints that do not allow for robust interpretations of incision rates and timing of terrace formation however in situ produced cosmogenic nuclides allow absolute age determination and hence incision rates of fluvial deposits back to 5 ma here we present cosmogenic depth profile dating and isochron burial dating of four different river systems in europe spanning 12 of latitude we do this to determine river incision rates and spatial variations in the timing of terrace formation isochron burial age constraints of four selected terraces from the vltava river czech republic range between 1 00 0 21 to 1 99 0 45 ma an isochron burial age derived for the allier river central france is 2 00 0 17 ma five terrace levels from the esla river nw spain were dated between 0 08 0 04 0 01 ma and 0 59 0 13 0 20 ma with depth profile dating the latter age agrees with an isochron burial age of 0 52 0 20 ma two terrace levels from the guadalquivir river sw spain were dated by depth profile dating to 0 09 0 03 0 02 ma and 0 09 0 04 0 03 ma the one terrace level from the guadalquivir river dated by isochron burial dating resulted in an age of 1 79 0 18 ma results indicate that the cosmogenic nuclide based ages are generally older than ages derived from previous relative age constraints leading to a factor 2 3 lower incision rates than previous work furthermore the timing of terrace formation over this latitudinal range is somewhat obscured by uncertainties associated with dating older terraces and not clearly synchronous with global climate variations

morphostratigraphy and provenance of plio pleistocene terraces in the south eastern alpine foreland the mislinja and upper savinja valleys northern slovenia

river terrace sequences templates for quaternary geochronology and marine terrestrial correlation fluvial sequences particularly terrace staircases represent archives of quaternary palaeoclimatic fluctuation and can serve as stratigraphical frameworks for geochronology and for correlation with other depositional environments in particular the global marine oxygen isotope record fluvial lithostratigraphical frameworks also provide contexts for records from fossils and artefacts of faunal evolution and human occupation conversely both records can be means of relative dating of riverine sequences three fluvial sequences are examined as case studies first is the severn avon system in the english midlands which has biostratgraphical evidence and an amino acid geochronology together with marker inputs from three different glaciations the somme sequence of northern france famous for its palaeolithic artefact assemblages again has biostratigraphy and an amino acid geochronology and has also been dated with reference to overlying loess palaeosols sequences the fluvial terraces of the river arun the final case study lack dating evidence but are interspersed within the sussex raised beach staircase although various lines of evidence suggest that the rivers discussed have formed terraces in response to climatic fluctuation an intriguing difference is that interglacial sediments occur at the bases of terrace formations in the severn avon whereas in the somme they occur at the tops of sequences beneath loessic overburden

structural controls on drainage development in the canyonlands grabens of southeast utah the canyonlands grabens in southeast utah form an active exten sional fault array covering 200 km2 southeast of the colorado river the fault array formed as a result of gravity gliding above a thick layer of salt growth of this fault array within the last 0 5 m y possibly last 0 1 m y has resulted in major changes in the stream drainages across the area through processes of stream capture and diversion during growth of the fault array relay ramps between overlapping fault segments form topographic lows along the graben margins these commonly act as access points for captured streams to enter a graben system as fault segments continue to propagate laterally linkage leads to breaching of the relay ramp structures this causes changes in the course and gradients of the streams com monly shifting the locus of alluvial sediment deposition away from grabens that were previously infilling this complex evolution of drainage networks in a growing fault array may provide a valuable analog to the early structural and stratigraphic development of larger continental rift systems reservoir distribution is an essential element of many hydrocarbon plays and understanding the rela tionship between active fault growth and drainage evolution may help predict reservoir distribution and quality

fluvial responses to climate and sea level change a review and look forward summary fluvial landforms and deposits provide one of the most readily studied quaternary continental records and alluvial strata represent an important component in most ancient continental interior and continental margin successions moreover studies of the long term dynamics of fluvial systems and their responses to external or allogenic controls can play important roles in research concerning both global change and sequence stratigraphy as well as in studies of the dynamic interactions between tectonic activity and surface processes these themes were energized in the final decades of the twentieth century and may become increasingly important in the first decades of this millennium this review paper provides a historical perspective on the development of ideas in the fields of geomorphology quaternary geology vs sedimentary geology and then summarizes key processes that operate to produce alluvial stratigraphic records over time scales of 103 106 years of particular interest are changes in discharge regimes sediment supply and sediment storage en route from source terrains to sedimentary basins as well as changes in sea level and the concept of accommodation late quaternary stratigraphic records from the loire france mississippi usa colorado texas usa and rhine meuse the netherlands rivers are used to illustrate the influences of climate change on continental interior rivers as well as the influence of interacting climate and sea level change on continental margin systems the paper concludes with a look forward to a bright future for studies of fluvial response to climate and sea level change at present empirical field based research on fluvial response to climate and sea level change lags behind a the global change community s understanding of the magnitude and frequency of climate and sea level change b the sequence stratigraphic community s desire to interpret climate and especially sea level change as forcing mechanisms and c the modelling community s ability to generate numerical and physical models of surface processes and their stratigraphic results a major challenge for the future is to catch up which will require the development of more detailed and sophisticated quaternary stratigraphic sedimentological and geochronological frameworks in a variety of continental interior and continental margin settings there is a particular need for studies that seek to document fluvial responses to allogenic forcing over both shorter 102 103 years and longer 104 106 years time scales than has commonly been the case to date as well as in larger river systems from source to sink studies of quaternary systems in depositional basin settings are especially critical because they can provide realistic analogues for interpretation of the pre quaternary rock record

sediment transport in the shelf canyon swatch of no ground bay of bengal the swatch of no ground is a shelf canyon that deeply incises the bengal shelf near the ganges brahmaputra river mouth cuts the foreset beds of the subaqueous river delta and acts as temporary depocenter between river mouth and bengal fan sedimentation rates in the swatch of no ground are highest near the canyon head at 50 cm a 1 decreasing to 15 cm a 1 in 600 m water depth the canyon deposits consist of intercalated fine silt clay and coarse silt sand grained deposits in seismic profiles small scale sedimentary structures and parallel bedded layers reveal that sediment in the canyon is mainly deposited from suspension during fair weather conditions tidal currents are the dominant mechanism that transports plumes of suspended river load towards the canyon forming fine grained silt clay layers during storm conditions sediment is resuspended on the inner shelf and subaqueous delta east of the canyon storm generated bottom currents transport the resuspended sediment alongshelf to the canyon where the particles are trapped and form graded coarse silt sand layers channels and gullies in the swatch of no ground indicate active gravity driven currents with an erosional character in the upper canyon and non depositional character below 450 m suggesting that persistent or ephemeral currents presently export sediment to the bengal fan numerous slumps and slides observed in the canyon show small scale acoustically transparent layers that indicate sediment liquefaction presumably initiated along the steep canyon margin these mudflows move downslope and halt where the canyon gradient decreases one widespread acoustically transparent layer with an age of approximately 140 160 years bp can be traced throughout much of the canyon and is probably the result of large scale sediment remobilization triggered by a catastrophic event like an earthquake this may represent decennial to centennial scale events that remove large quantities of sediment and prevent the canyon from rapid infilling

controls on dryland mountain landscape development along the nw saharan desert margin insights from quaternary river terrace sequences dades river south central high atlas morocco abstract this study documents river terraces from upstream reaches of the dades river a major fluvial system draining the south central high atlas mountains terraces occur as straths with bedrock bases positioned at 10 m altitudinal intervals up to 40 m t1 t5 above the valley floor becoming less common between 50 and 140 m the rock strength stratigraphy and structure of the mountain belt influences terrace distribution terraces are absent in river gorges of structurally thickened limestone whilst well developed laterally continuous terraces t1 t4 form along wide valleys occupying syncline structures dominated by weaker interbedded limestone mudstone terrace staircases develop in confined canyons associated with weaker lithologies and influence from structural dip and stratigraphic configuration terraces comprise a bedrock erosion surface overlain by fluvial conglomerates rare overbank sands and colluvium this sequence with some osl irsl age control suggests terrace formation over a 100 ka climate cycle with valley floor aggradation during full glacials and incision during glacial interglacial transitions this integrates with other archives e g lakes glaciers dunes appearing typical of landscape development along the nw saharan margin south of the high atlas and similar to patterns in the western southern mediterranean the 100 ka climate cycle relationship suggests that the terrace sequence documents late middle pleistocene landscape development consistent altitudinal spacing of terraces and their distribution throughout the orogen suggests sustained base level lowering linked to uplift exhumation of the high atlas low incision rates 1 and general absence of terrace deformation suggests dominance of isostatically driven base level lowering with relief generation being early pleistocene or older

climatically controlled terraces in uplifting mountain areas abstract terraces in tectonically active mountains and uplands record both tectonic uplift and rhythmic climatic variations the author discusses the question of how to distinguish the role of both tectonic and climatic factors in central europe with quaternary uplift of the order of 50 100 m climatically controlled terraces are well developed cold stage aggradation is recognised through the interfingering of periglacial alluvial slope and loess deposits erosional activity prevailed in transitional periods then follows a discussion of difficulties connected with the construction of timing and rate of tectonic uplift based on the depth of incision in the bedrock and on facies differentiation the examination of changes in longitudinal profiles of river valleys indicates that unrejuvenated upper valley courses cannot be used for the reconstruction of tectonic uplift finally the author presents several types of adaptation of tectonically determined downcutting and aggradation to quaternary climatic cyclicity

the tsunamite problem the genetic term tsunamite is used for a potpourri of deposits formed from a wide range of processes overwash surges backwash flows oscillatory flows combined flows soft sediment deformation slides slumps debris flows and turbidity currents related to tsunamis in lacustrine coastal shallow marine and deep marine environments tsunamites exhibit enormous variability of features e g normally graded sand floating mudstone clasts hummocky cross stratification etc these sedimentary features may also be interpreted as deposits of turbidity currents turbidites debris flows debrites or storms tempestites however sedimentary features play a passive role when these same deposits are reinterpreted as tsunamites on the basis of historical evidence for tsunamis and their triggering mechanisms e g earthquakes volcanic explosions landslides and meteorite impacts this bipartite sedimentological vs historical approach which allows here classification of the same deposit as both turbidite and tsunamite has blurred the distinction between shallow marine and deep marine facies a solution to this problem is to classify deposits solely by a descriptive sedimentological approach the notion that tsunami waves can directly deposit sediment in the deep sea is unrealistic because tsunami waves represent transfer of energy and they are sediment starved during tsunamis and major storms submarine canyons serve as the physical link between shallow water and deep water environments for sediment transport tsunami related deposition involves four progressive steps 1 triggering stage offshore 2 tsunami stage incoming waves 3 transformation stage near the coast and 4 depositional stage outgoing sediment flows in this progression deep water deposition can commence only after the demise of incoming tsunami waves due to their transformation into outgoing sediment flows deposits of these sediment flows already have established names e g debrite and turbidite therefore the term tsunamite for these deposits is obsolete

climatically controlled river terrace staircases a worldwide quaternary phenomenon a comparison of fluvial terrace sequences from around the world based on data collected as part of international geoscience programme igcp project no 449 has revealed significant patterns river terraces provide important records of uplift which is essential for their formation and of landscape evolution their cyclic formation however almost invariably seems to have been a response to climatic fluctuation sequences in the european core area of igcp 449 which has the longest and most extensive research history have been used as templates for worldwide comparison there is evidence for a global acceleration of uplift at the time of and perhaps in response to the mid pleistocene revolution when climatic fluctuation switched to 100 kyr milankovitch cycles terraces formed prior to this generally consist of wide aggradational sheets that probably each represent formation over several 41 kyr cycles subsequently river valleys became more steeply entrenched and terraces formed in response to the stronger 100 kyr climatic forcing in many cases at approximately one per cycle this paper uses the new data resource to explore differences between records in different climate zones between sequences with variable numbers of middle late pleistocene terraces and between systems in which the all important incision event has occurred in different parts of climatic cycles key records discussed include european examples from the rhine thames somme dniester dnieper don volga and aguas from asia the gediz turkey and orontes syria from north america the south platte and colorado from south africa the vaal and sundays from australia the shoalhaven and from south america the amazon paraguay and tributaries of the colorado and negro

uplift driven valley incision and climate controlled river terrace development in the thames valley uk abstract the sequence of terraces of the river thames in southeast england has previously been shown to span the period from the earliest pleistocene to the present this terrace sequence contains biostratigraphical and sedimentary evidence that testifies to the high amplitude climatic changes of the quaternary large scale fluvial incision resulting in basin wide terrace formation appears to have been concentrated at the warming limbs of the major climatic glacial interglacial cycles when sediment supply was greatly reduced this incision and subsequent valley floor widening created the accommodation space for the later aggradation of the terrace sediments during the following warm cold transitions and during the cold stages when high sediment supply conditions prevailed although the timing of terrace aggradation may be controlled by climate change the progressive valley incision recorded by terrace staircases cannot easily be explained in terms of quaternary climatic change alone and recently developed models suggest that long term incision by the thames has been driven by uplift this paper presents an overview of the available terrace data and tabulates incision amounts and rates between key stratigraphic horizons superimposed upon these broad changes revealed by the complex internal sedimentary architecture of many terrace sediments are the geomorphological system responses to both higher frequency climate driven changes and more localized intrinsic fluvial system adjustments

upper cenozoic fluvial history in the bohemian massif abstract two periods of fluvial development are identified in the bohemian massif bm uplands during the upper cenozoic the first lower miocene period is characterised by large unterraced gravel bodies up to 100 m thick filling overdeepened valleys or forming nowadays highly fragmented spreads upon plateaux and interfluves for the second upper pliocene holocene period a diverse style of deposition is typical the sedimentation is discontinuous and all types of continental sediments show repeated breaks in deposition this type of deposition is believed to be driven by the very essence of this time span i e climatically controlled alternation of erosion and accumulation phases because the uplands of the bm remained ice free and higher relief ensured repeated down cutting whenever the environment permitted the river valleys preserve complete records of the entire younger period the progressive series of incisions each of which is followed by an aggradation phase resulted in the formation of stairway like terrace sequences starting some 120 150 m above the rivers the onset of a new style of fluvial deposition together with the origin of a new drainage pattern is dated approximately to the gauss matuyama palaeomagnetic reversal this corresponds in central europe with the start of deposition of loess and formation of complex quaternary type sequences of slope sediments in uplands and can be taken to indicate a new geological era these changes may be therefore taken as support for the lowering of the quaternary tertiary erathem boundary

saalian supercycle mindel riss interglacial and milankovitch s dating abstract there are five pleistocene glacial interglacial cycles recorded in deep sea sediments from the last half million years but only two classic interglacials are recognized on land the dilemma stems from the different understanding and identification of glacials and interglacials in the geologic records on land and in the ocean only those intervals of warm climate that followed a major southward ice sheet advance and were accompanied by a deep penetrating oceanic transgression were recognized in their type areas of northern europe as true interglacials only those ice advances which left moraines farther south than younger ones were recognized as glacials in contrast all intervals reflecting exceptionally low global ice volume high sea level and warm sea surface are taken as interglacials in the deep sea record classic subdivisions are aligned with the glacial interglacial cycles of marine isotope stage stratigraphies by proposed higher order units called supercycles sc bracketed by superterminations st the saalian supercycle sc2 includes glacial cycles c d and e composed of marine isotope stages mis 6 7 8 9 10 and 11 the units mis 7 to mis 11 correspond to the great gross interglacial estimated from the early geologic considerations to be about 240 millennia long penck and bruckner 1909 die alpen im eiszeitalter vols 1 3 christian herman tauchnitz leipzig and determined from astronomic computations to last 235 millennia milankovitch 1941 kanon der erdbestrahlung und seine anwendung auf das eiszeitenproblem academie royale serbe editions speciales section des sciences mathematiques et naturelles tome cxxxiii stamparija mihaila curcica beograd 633pp the current high precision radiometric dating fully confirms the accuracy of milankovitch s determination and the pivotal role of orbital mechanisms in pleistocene climate change