late pleistocene holocene evolution of the northern shelf of the sea of marmara abstract chirp sub bottom profiling multibeam bathymetric mapping and a combination of faunal and isotopic analysis of molluscs and foraminifera in sediment cores on the northern shelf of the sea of marmara som provide evidence of sea level excursions water exchanges between the adjacent mediterranean and black seas and oscillating salinity over the last 160 ka bp during the marine isotope stages mis 2 mis 3 mis 4 and mis 6 the som disconnected from the mediterranean sea and evolved into a lake during mis 1 mis 5 and mis 7 the som reconnected and became salty once again sapropels formed shortly after each invasion of mediterranean saltwater observed in our cores concurrent suboxic dysoxic conditions prevailed over quite shallow substrates on the shelf ancient shorelines are pervasive at 85 m on the northern shelf and in the region of prince islands coincident with the elevation of the modern bedrock sill in the canakkale dardanelles strait at times when global eustatic sea level dropped below this sill the surface of the som stabilized at its outlet and freshened thus this particular shoreline is interpreted as the edge of the most recent som lake that existed from about 75 ka bp to 12 ka bp the freshening is observed in very light 6 values of 18 o measured on freshwater molluscs and the complete absence of foraminifera two brief lacustrine episodes during mis 5 suggest that the level of the canakkale outlet might have been as shallow as 50 m in the past a likelihood supported by submerged terraces along its margins bounding the modern central channel and the presence of an euryhaline biofacies in unit l4 1 corresponding to mis 5b 18 o profiles and carbon 14 dating show that salinification of the som and the blossoming of bioherms evolved rapidly after the latest connection with the mediterranean at 12 ka bp however freshening proceeded more slowly once the connection was severed

time scales of tectonic landscapes and their sediment routing systems abstract in regions undergoing active tectonics the coupling between the tectonic displacement field the overlying landscape and the redistribution of mass at the earth9s surface in the form of sediment routing systems is particularly marked and variable coupling between deformation and surface processes takes place at a range of scales from the whole orogen to individual extensional fault blocks or contractional anticlines at the large scale the attainment of a steady state between the overlying topography and the prevailing tectonic conditions in active contractional orogens requires an efficient erosional system with a time scale dependent on the vigour of the erosional system generally in the range 10 6 10 7 years the catchment fan systems associated with extensional fault blocks and basins of the western usa are valuable natural examples to study the coupling between tectonic deformation landscape and sediment routing systems even relatively simple coupled systems such as an extensional fault block and its associated basin margin fans have a range of time scales in response to a tectonic perturbation these response times originate from the development of uniform steady state relief during the accumulation of displacement on a normal fault c 10 6 years the upstream propagation of a bedrock knickpoint in transverse catchments following a change in tectonic uplift rate c 10 6 years or the relaxation times of the integrated catchment fan system in response to changes in climatic and tectonic boundary conditions 10 5 10 6 years the presence of extensive bedrock or alluvial piedmonts increases response times significantly the sediment efflux of a mountain catchment is a boundary condition for far field fluvial transport but the fluvial system is much more than a simple transmitter of the sediment supply signal to a neighbouring depocentre fluvial systems appear to act as buffers to incoming sediment supply signals with a diffusive time scale c 10 5 10 6 years dependent on the length of the system and the extent of its floodplains stream channels and proximal gravel fans the vocabulary for explaining landscapes would benefit from a greater recognition of the importance of the repeat time and magnitude of perturbations in relation to the response and relaxation times of the landscape and its sediment routing systems landscapes are best differentiated as buffered or reactive depending on the ratio of the response time to the repeat time of the perturbation furthermore landscapes may be regarded as steady or transient depending on the ratio of the response time to the time elapsed since the most recent change in boundary conditions the response of tectonically and climatically perturbed landscapes has profound implications for the interpretation of stratigraphic architecture

textural and rheological evolution of basalt flowing down a lava channel the muliwai a pele lava channel was emplaced during the final stage of mauna ulu s 1969 1974 eruption kilauea hawaii the event was fountain fed and lasted for around 50 h during which time a channelized flow system developed in which a 6 km channel fed a zone of dispersed flow that extended a further 2 6 km the channel was surrounded by initial rubble levees of a a capped by overflow units of limited extent we sampled the uppermost overflow unit every 250 m down the entire channel length collecting and analyzing 27 air quenched samples bulk chemistry density and textural analyses were carried out on the sample interior and glass chemistry and microlite crystallization analyses were completed on the quenched crust thermal and rheological parameters cooling crystallization rate viscosity and yield strength were also calculated results show that all parameters experience a change around 4 5 km from the vent at this point there is a lava surface transition from pahoehoe to a a lava density microlite content viscosity and yield strength all increase down channel but vesicle content and lava temperature decrease cooling rates were 6 7 c km with crystallization rates increasing from 0 03 c km proximally to 0 14 c km distally modeling of the channel was carried out using the flowgo thermo rheological model and allowed fits for temperature microlite content and channel width when run using a three phase viscosity model based on a temperature dependent viscosity relation derived for this lava the down flow velocity profile suggests an initial velocity of 27 m s declining to 1 m s at the end of the channel down channel lava underwent cooling that induced crystallization causing both the lava viscosity and yield strength to increase moreover lava underwent degassing and a subsequent vesicularity decrease this aided in increasing viscosity with the subsequent increase in shearing promoting a transition to a a

use of composite fingerprints to determine the provenance of the contemporary suspended sediment load transported by rivers sediment fingerprinting appears to offer a valuable alternative to direct monitoring for elucidating the provenance of suspended sediment and the relative importance of spatial zones or subcatchments comprising larger 500 km 2 drainage basins against this background a quantitative composite fingerprinting technique incorporating both statistically verified multicomponent signatures and a multivariate sediment mixing model has been employed to determine the spatial origin of contemporary suspended sediment transported from the upper and middle reaches of the river exe 601km 2 and river severn 4325 km 2 basins uk spatial origin is addressed in terms of the relative contribution from three distinct geological subareas constituting each study basin the consistency of the composite fingerprinting approach is examined using the estimates for mean and seasonal variations in source area contributions and also a comparison between the results obtained for individual flood events and alternative lines of evidence provided by flood travel times and the spatial distribution of precipitation it is argued that fingerprinting estimates for sediment provenance are consistent with existing information on suspended sediment yields from different subcatchments within the study basins although in the severn the role of storage and remobilization in producing signature averaging may complicate comparison of the fingerprinting data with typical floodwater routing times validation represents the greatest problem for the cost benefit of fingerprinting and scope still exists for further refinement of the procedures involved 1998 john wiley sons ltd

palaeogeographical evolution of the thrace neogene basin and the tethys paratethys relations at northwestern turkey thrace abstract the thrace neogene basin situated in northwestern turkey was initiated by strike slip faulting that was active from the early miocene until the end of the pliocene during the early miocene it began to form under the control of the thrace eskisehir fault zone initiated by continental collision in northwestern anatolia late oligocene early miocene during the late early miocene the basin was a site of mainly fluviatile and limnic sedimentation to the west and marine sedimentation via the paratethyan transgression in the north with the onset of the middle miocene the thrace block started to rotate in a counterclockwise sense and escaped westward with respect to the strandja istanbul block owing to rejuvenation of fossil fault systems within it in this period warm marine conditions were also established around the gulf of saros through a mediterranean originated transgression during the middle late miocene fluviatile and limnic conditions were created over the western thrace by the westerly propagation of the thrace eskisehir fault zone one of the principal results of the early middle miocene tectonics is the tilting of the strandja istanbul block to the south severing the tethys and the paratethys during the latest miocene early pliocene period the thrace eskisehir fault zone was deactivated because of the evolution of the north anatolian fault zone to the south the resurrected ganos fault zone situated on the dissected fossil suture zone in the sea of marmara also joined the north anatolian fault zone uplifting the gelibolu peninsula and thus severing the connection that existed between the sea of marmara and the paratethys the sea of marmara eventually became an endemic basin by the activity of the north anatolian fault zone

black sea impact on the formation of eastern mediterranean sapropel s1 evidence from the marmara sea abstract water exchange between the black sea and the mediterranean sea has been a major focus of the paleohydrography of the eastern mediterranean glacial melt water released from the black sea is a potential factor in the formation of sapropel s1 an organic rich sediment layer that accumulated during the early holocene a high resolution study done on sediments from the marmara sea the gateway between the mediterranean and the black sea sheds light on the holocene exchange processes past sea surface temperature and sea surface salinity sss were derived from stable oxygen isotope ratios 18o of foraminiferal calcite and alkenone unsaturation ratios uk 37 heavy 18o values and high sss in the marmara sea suggest absence of low salinity water from the black sea during s1 the comparison with data from the levantine basin and southern aegean sea outlines gradients of freshening in the eastern mediterranean sea whereby the major sources of freshwater were closer to the levantine basin it is thus concluded that the black sea was not a major freshwater source contributing to formation of s1 given the absence of a low salinity layer the deposition of organic rich sediments corresponding to s1 in the marmara sea is likely the result of the global transgression and the concomitant re organization of biogeochemical cycles leading to enhanced productivity as shown by globigerina bulloides

freshwater outbursts to the oceans from glacial lake agassiz and their role in climate change during the last deglaciation abstract lake agassiz was the largest lake in north america during the last deglaciation as the laurentide ice sheet lis retreated large volumes of water stored in this proglacial lake were episodically released into the oceans these waters were variably routed to the gulf of mexico arctic ocean north atlantic ocean and hudson bay during this period the three largest cooling events in the northern hemisphere closely followed 4 of the 5 largest outbursts from lake agassiz 1 the younger dryas which was preceded by a release of 9500 km 3 2 the preboreal oscillation preceded by releases of 9300 km 3 and 5900 km 3 and 3 the 8 2 ka cold event preceded by a 163 000 km 3 outburst these are respectively fluxes of 0 30 sv 0 29 sv 0 19 sv and 5 2 sv if released in 1 year because the influx of freshwater reaching the north atlantic ocean can inhibit thermohaline circulation partly depending on whether the ocean was in a glacial interglacial or transitional mode of circulation we believe that at least these large outbursts from lake agassiz may have provided the triggers for changes in ocean circulation and in turn for widespread climate change

hydraulic calculations of postglacial connections between the mediterranean and the black sea a series of simple hydraulic calculations has been performed to examine some of the questions associated with the reconnection of the black sea to the mediterranean through the turkish strait system during the holocene ryan et al s catastrophic flood scenario whereby the erosive power of the marine in fluxes initiated after eustatic sea level reached the sill depth opened up the bosphorus allowing saline water to pour into the black sea and filling it on a short time scale is examined the calculations show that although it might be possible to fill the palaeo black sea within the order of a decade a 1 2 year filling time scale is not physically possible a hydraulic model is also used to examine the more traditional connection hypothesis of near continuous freshwater outflow from the black sea with a slowly increasing saline inflow from the mediterranean beginning around 8 9 kyr bp the model considers two forms for the structure of the bosphorus a shallow sill as seen today and a deep sill associated with no sediments filling the 100 m gorge above the bedrock in the strait sensitivity experiments with the hydraulic model show what possible strait geometric configurations may lead to the black sea reaching its present day salinity of 18 psu salinity transients within the black sea are shown as a function of time providing for values that can be validated against estimates from cores to consider a deep non sediment filled bosphorus 100 m deep the entry of mediterranean water into the sea of marmara after 12 0 kyr bp is examined a rapid entry of marine water into the sea of marmara is only consistent with small freshwater fluxes flowing through the turkish strait system smaller than those of the present day by a factor of at least 4 such a small freshwater flux would lead to the salinification of the black sea being complete by an early date of 10 2 9 6 kyr bp thus the possibility of a deep bosphorus sill should be discounted

structural interpretation of the marmara region nw turkey from aeromagnetic seismic and gravity data abstract the seismically active marmara region located in nw turkey lies on the westward end of the north anatolian fault naf the naf is well defined on land previous investigations of its extension in the marmara sea include marine bathymetry seismological activity and seismic profiles in this study faults and their configurations identified inland are extended into the marmara sea by means of aeromagnetic anomalies as well as seismic and gravity profiles the deep structure was resolved by constructing a map of the tertiary bottom shallow curie isotherm was determined by spectral analysis indicating a thinner crust in the northern marmara depression area with respect to the continental crust a combination of the geophysical data allows us to propose the existence of subsidence and isostatic equilibrium in the northern marmara sea a less active zone identified in the central high zone dividing the marmara sea into two parts may also be deduced from the seismic data this structural arrangement may play a key role in earthquakes that will affect the surrounding regions

the original shapes of quartz silt grains a test of the validity of the use of quartz grain shape analysis to determine the sources of terrigenous silt in marine sedimentary deposits abstract the results of a study of the original shapes of quartz silt grains that are released from plutonic metamorphic and sedimentary rocks of varied age origin and lithology are reported the purpose of the study is to demonstrate the validity of quartz grain shape analysis as a technique for determining the sources of terrigenous silt within marine sedimentary deposits by showing that different sources of terrigenous silt release quartz silt grains with different shapes there are four major types of sources that release quartz silt grains with different and distinctive shapes crystalline rocks release a mixture of crystalline grains with subrounded and subangular outlines crystalline nodes and grain embayments and fractured grains with angular outlines microfractures deformation sheets and fracture faces quartz cemented sedimentary rocks release overgrown grains with subangular to angular outlines and quartz overgrowths and lesser numbers of rounded grains with rounded and subrounded outlines and abraded grain surfaces glacial deposits release fractured grains with angular outlines microfractures deformation sheets fracture faces micro blocks and comminution debris lastly quartzose multicyclic sediments release abundant rounded grains with rounded or subrounded outlines and abraded and weathered surfaces therefore the results indicate that quartz grain shape analysis is generally a valid technique for determining the sources of silt however there are exceptions to this generalization for there are some sediment sources e g first cycle coastal plain sediments that inherit and release grain shape types which are released from other sediment sources e g crystalline rocks thus the application of quartz grain shape analysis to the study of the sources of terrigenous silt for a given study area requires some knowledge about the major sediment sources which are available to that study area for this knowledge will define the limitations of this sourcing technique

constraining the timing of the most recent cataclysmic flood event from ice dammed lakes in the russian altai mountains siberia using cosmogenic in situ 10be ice dammed lakes were repeatedly formed in intermontane basins in the russian altai mountains throughout the pleistocene these cataclysmic outburst floods caused by ice dam failures were documented as earth9s largest flood waves by other geoscientists using in situ 10 be we successfully dated surfaces of flood associated boulders located in a former lake basin and downvalley from a former ice dam our precise surface exposure ages suggest that all boulders were associated with the most recent out of a number of cataclysmic floods that occurred at 15 8 1 8 ka the field location of the boulders implies that they were deposited by the largest late pleistocene flood that drained the chuya katun lake completely following initial dam failure a published reconstruction of the late glacial paleoenvironment in the vicinity of the former ice dam indicates that dam failure was likely a result of climatically induced downwasting of glaciers the failure of the ice dam provides more evidence for the timing of widespread warming during the late glacial in southern russia this flooding event in the headwaters of the ob river coincides with a freshwater peak as recorded in isotopic records of the kara sea and the arctic ocean

modelling the provenance of detritus flushed through the strait of bosphorus turkey during early holocene outflow from the black sea to the world ocean abstract source to sink tracing of very fine sand supplied to a controversial lower holocene deltaic lobe in the northeastern marmara sea was undertaken using sem backscatter mapping and quantitative mineral liberation analysis of very fine sand fractions forty two samples from the kurbagalidere goksu golden horn and riva watersheds and from oligo miocene outcrops along the southwestern black sea coast show that each of these potential sources has a distinct mineralogical fingerprint comparison with 11 samples from the lower holocene delta and 19 samples from the overlying mud drape show that no single source can account for the mineral proportions in the sand fractions of these depositional sinks but a mixed provenance provides good matches for the deltaic lobe quantitative mixing based on 250 000 monte carlo simulations suggests 50 contribution from oligo miocene successions of the southwestern black sea coast and inner shelf 20 contribution from the goksu stream and minor contributions from other sources including the kurbagalidere stream this balance of source contributions continued to supply the holocene mud drape until 6 cal ka after which local sources became more important it is hypothesized that unconsolidated sediment from a number of watersheds was parked along the coast of the neoeuxine lake and in the paleo bosphorus valley during the mis 2 lowstand a rising neoeuxine lake possibly swollen by glacial outburst floods from the altay region of central asia flushed 0 5 km 3 of this sediment through the strait of bosphorus to the deltaic lobe and permitted it to rapidly advance into the marmara sea which at that time was rising 1 m each 100 yr provenance of the lower portion of the holocene mud drape is consistent with continued black sea outflow throughout the deposition of sapropel m1 in the marmara sea

magnetic ilmenite hematite detritus in mesozoic tertiary placer and sandstone hosted uranium deposits of the rocky mountains mesozoic and tertiary sandstones throughout the rocky mountains region of the united states contain a de trital fe ti oxide mineral that is generally regarded as unusual and is preserved wherever these sandstones have escaped destructive diagenesis this mineral a medial ilmenite hematite solid solution is highly magnetic and has sometimes been mistaken for magnetite we have encountered this mineral in paleomagnetic studies and in investigations of sandstone hosted uranium deposits and cretaceous shoreline placer deposits it is known to occur elsewhere in intermediate volcanic rocks consistent with quenching from hypersolvus high temperature conditions the detrital occurrences we describe are of economic importance in uranium deposits where they are among the reductants that precipitate uranium and in cretaceous placer deposits whose exploitation would require a separation procedure tailored to this mineral the distribution of detrital hematite ilmenite sandstones in cretaceous rocks suggests a contemporaneous volcanic source in the northern rocky mountains

oscillating quaternary water levels of the marmara sea and vigorous outflow into the aegean sea from the marmara sea black sea drainage corridor abstract detailed interpretation of single channel air gun and deep tow boomer profiles demonstrates that the marmara sea turkey experienced small amplitude 70 m fluctuations in sea level during the later quaternary limited in magnitude by the sill depth of the strait of dardanelles moderate subsidence along the southern shelf and quaternary glacio eustatic sea level variations created several stacked deltaic successions separated by major shelf crossing unconformities which developed during the transitions from global glacial to interglacial periods near the strait of dardanelles a series of sand prone deposits are identified beneath an uppermost holocene transparent mud drape the sandy deposits thicken into mounds with the morphology and cross sectional geometries of barrier islands sand waves and current generated marine bars all cross stratification indicates unidirectional flow towards the dardanelles prior to the deposition of the transparent drape which began 7000 years bp in strong support of the notion that the marmara sea flowed westwards into the aegean sea through the dardanelles at times of deglaciation in northern europe the global sea level curve shows that at 11 000 and 9500 years bp sea level rose to the sill depths of the straits of dardanelles and bosphorus respectively the effect from 11 000 to 9500 years bp was seawater incursion into the marmara sea drowning and formation of algal serpulid bioherms atop lowstand barrier islands and transgression of shelves and lowstand deltas at 9500 years bp glacial meltwater temporarily stored in the black sea lake developed into a vigorous southward flow toward the aegean sea forming west directed sandy bedforms in the western marmara sea and initiating deposition of sapropel s1 in the aegean sea this strong outflow persisted until 7000 years bp after which a mud drape began to accumulate in the marmara sea and euryhaline mediterranean mollusks successfully migrated into a progressively more saline black sea where sapropel deposition began most eastern mediterranean sapropels from s1 to s11 appear to correlate with periods of rising sea level and breaching or near breaching of the bosphorus sill these events are believed to coincide with times of vigorous outflow of low salinity fresh surface waters transiting the black sea marmara sea corridor and ultimately derived from melting of northern european ice sheets

deltas south of the bosphorus strait record persistent black sea outflow to the marmara sea since 10 ka at the southern exit of the bosphorus strait in the northeastern marmara sea high resolution seismic profiles reveal two lobate progradational delta lobes in modern water depths of v40 65 m the younger delta was active from v10 to 9 ka based on radiocarbon dates of equivalent prodelta deposits and the elevation of its topset to foreset transition the topset to foreset transition climbs in the seaward direction because the delta prograded into a rising sea low abundances of marine fauna and flora in the 10 9 ka interval support a deltaic interpretation there are no rivers in the area that could have fed the delta instead all evidence points to the strait itself as the source of sediment and water when this outflow was strongest v10 6 6 0 ka sapropels accumulated in basinal areas of both the aegean and marmara seas benthic foraminiferal and dinoflagellate cyst data from contemporary deposits elsewhere in the marmara sea point to the continual presence through the holocene of a surface layer of brackish water that we ascribe to this same outflow from the black sea through the bosphorus strait by v9 1 8 5 ka two layer flow developed in the bosphorus strait as global sea level continued to rise and the sediment supply to the younger delta was cut off because the outflowing black sea water ceased to be in contact with the floor of the strait the older delta lobe lies below a prominent lowstand unconformity and is tentatively interpreted to have formed from v29 5 to 23 5 ka oxygen isotopic stage 3 when the marmara sea stood at v355 m and a second sapropel accumulated in deep basinal areas crown copyright 2002 elsevier science b v all rights reserved

impact of periodicity on sediment flux in alluvial systems grain to basin scale periodicity is a common component of many sedimentological processes but seldom is it considered across all scales of fluvial processes in order to understand the complete impact on sediment supply to basins temporal changes in sediment supply within drainage systems and sedimentary basins are a consequence of the inherent instability in transport processes the causes of fluctuations are of 2 main types i changes in factors endemic to the supply of sediment but which are at least partly independent of erosive forces and ii changes in the magnitude of forces available to transport sediment fluctuations at spatial scales from grain through reach to basin scales and at temporal scales from minutes to millennia are discussed and evaluated all fluctuations are reflected in sedimentary deposits in some way for example irregular patterns of bed break up during erosion can generate bedforms that are recorded in deposits the passage of waves of sediment can cause cycles of incision and aggradation in a reach large flood events will flush sediment into coastal regions and will be recorded as an identifiable package in the deposits many models of basin processes and products assume a consistent supply of sediment which is far from the case in nature one of the challenges in the coming decade is to move away from using long term averages of sediment supply and to link models directly into geomorphic processes

hydrology in the sea of marmara during the last 23 ka implications for timing of black sea connections and sapropel deposition 1 sediments deposited under lacustrine and marine conditions in the sea of marmara hold a late quaternary record for water exchange between the black sea and the mediterranean sea here we report a multiproxy data set based on oxygen and strontium isotope results obtained from carbonate shells major and trace elements and specific organic biomarker measurements as well as a micropaleontological study from a 14c dated sediment core retrieved from the sea of marmara pronounced changes occurred in 18o and 87sr 86sr values at the fresh and marine water transition providing additional information in relation to micropaleontological data organic biomarker concentrations documented the marine origin of the sapropelic layer while changes in n alkane concentrations clearly indicated an enhanced contribution for organic matter of terrestrial origin before and after the event when compared with the black sea record the results suggest that the black sea was outflowing to the sea of marmara from the last glacial maximum until the warmer bolling allerod the first marine incursion in the sea of marmara occurred at 14 7 cal ka b p however salinification of the basin was gradual indicating that black sea freshwaters were still contributing to the marmara seawater budget after the younger dryas which is associated with a high input of organic matter of terrestrial origin both basins were disconnected resulting in a salinity increase in the sea of marmara the deposition of organic rich sapropel that followed was mainly related to enhanced primary productivity characterized by a reorganization of the phytoplankton population

on the origin of the bosphorus abstract the palaeozoic upper cretaceous basement palaeomorphology of the bosphorus the strait of istanbul bears the evidence of a valley of a palaeostream running to the black sea in the north a palaeobasin deeper than 160 m opening to the sea of marmara in the south and a barrier between these two features this suggest that the northern part of the bosphorus was formed mainly by fluvial activity whereas the southern part developed as a basin by faulting the recent sediment thickness exceeds 130 m in the basin indicating that the southern part of the bosphorus was once essentially depositional rather than an erosional the present form of the bosphorus was established in holocene time by the connection of the basin in the south with the stream in the north the barrier and the stream valley in the north have been deepened by erosion and faulting to form a strait connecting the black sea and the mediterranean

seismic stratigraphy of late quaternary deposits from the southwestern black sea shelf evidence for non catastrophic variations in sea level during the last 10 000 yr abstract detailed interpretation of single channel seismic reflection and huntec deep tow boomer and sparker profiles demonstrates that the southwestern black sea shelf formed by a protracted shelf edge progradation since the miocene pliocene five seismic stratigraphic units are recognized unit 1 represents the last phase of the progradational history and was deposited during the last glacial lowstand and holocene it is divided into four subunits subunit 1a is interpreted as a lowstand systems tract 1b and 1c are interpreted as a transgressive systems tract and subunit 1d is interpreted as a highstand systems tract the lowstand systems tract deposits consist of overlapping and seaward prograding shelf edge wedges deposited during the lowstand and the subsequent initial rise of sea level these shelf edge wedges are best developed along the westernmost and easternmost segments of the study area off the mouths of rivers the transgressive systems tract deposits consist of a set of shingled shore parallel back stepping parasequences deposited during a phase of relatively rapid sea level rise and include a number of prograded sediment bodies including barrier islands beach deposits and thin veneers of seismically transparent muds showing onlap onto the flanks of older sedimentary features a number of radiocarbon dates from gravity cores show that the sedimentary architecture of unit 1 contain a detailed sedimentary record for the post glacial sea level rise along the southwestern black sea shelf these data do not support the catastrophic refilling of the black sea by waters from the mediterranean sea at 7 1 ka postulated by ryan pitman major shimkus maskalenko jones dimitrov gorur sakinc yuce mar geol 138 1997 119 126 ryan pitman touchstone book 1999 319 pp and ballard coleman rosenberg mar geol 170 2000 253 261

a hydrological model of the black and caspian seas in the late pleistocene and early middle holocene abstract this topic area has been a controversial one since the concept of a catastrophic black sea flood was first proposed and there is still considerable disagreement between experts as to the exact sequence of events this paper describes a numerical model of the caspian and black sea basins together with flows through the manych spillway and the bosphorus strait the model has been calibrated against the deductions made by various researchers concerning past water levels and parameters such as river flow volumes and evaporation rates have been assigned to give reasonable agreement with these deductions the model successfully predicts flow through the manych spillway during the early khvalynian transgression of the caspian sea between 15 2 and 12 3 ky bp and not thereafter the black sea is predicted to reach a lowstand of 163 m in about 11 ky bp and then to fill relatively rapidly due to increased river inflow combined with a breakthrough of mediterranean water across the bosphorus sill in about 10 5 ky bp this is followed by a period of high outflow through the bosphorus and between 9 3 and 8 ky bp by rapidly rising salinity due to marine inflow at depth the model also highlights two significant points of conflict with the physical evidence these concern the lack of apparent reason for the sudden onset of sapropel formation in the black sea in 7 6 ky bp and the significant erosion that has apparently occurred across the manych sill

a laurentide outburst flooding event during the last interglacial period episodes of ice sheet disintegration and meltwater release over glacial interglacial cycles are recorded by discrete layers of detrital sediment in the labrador sea1 2 the most prominent layers reflect the release of iceberg armadas associated with cold heinrich events3 but the detrital sediment carried by glacial outburst floods from the melting laurentide ice sheet is also preserved4 here we report an extensive layer of red detrital material in the labrador sea that was deposited during the early last interglacial period we trace the layer through sediment cores collected along the labrador and greenland margins of the labrador sea biomarker data ca sr ratios and 18o measurements link the carbonate contained in the red layer to the palaeozoic bedrock of the hudson bay we conclude that the debris was carried to the labrador sea during a glacial outburst flood through the hudson strait analogous to the final lake agassiz outburst flood about 8 400 years ago probably around the time of a last interglacial cold event in the north atlantic5 we suggest that outburst floods associated with the final collapse of the laurentide ice sheet may have been pervasive features during the early stages of late quaternary interglacial periods

late quaternary sedimentation in the strait of bosporus high resolution seismic profiling abstract uniboom profiling supported by borehole data in the southern part of the bosporus revealed that close to its banks holocene sediments are underlain by the faulted slopes of a valley cut in many places into the palaeozoic bedrock away from the banks the sediments thicken and their boundary with the underlying pleistocene deposits is defined by an erosional surface at about the 80 ms twt this surface marks the initiation of marine currents in the valley as its deeper parts began to be submerged in the late pleistocene to early holocene marine spillway phase the upward coarsening holocene sequence records the subsequent evolution of the present two way marine strait the sequence is divided into three seismostratigraphic units the lowest one constitutes an onlapping fill deposited under salt wedge estuarine conditions when sediment input and runoff discharge were high and sealevel was still rising but the flow of mediterranean waters into the black sea was not continuous it fills low areas and is well developed under a sill close to the southern entrance of the strait as sealevel rose closer to its present level and the rate of terrigenous input decreased in the middle holocene this unit began to be eroded and reworked by strong bottom currents the second unit records the transitional stage between the estuarine phase and the present two layered current system its seismic facies and sedimentary features indicate deposition under high energy conditions and shifting loci of accumulation the third surficial unit is a thin depositional lag rich in shell fragments blanketing the other two units it records deposition under fully marine conditions and flow of powerful bottom currents during the last few millenia