late quaternary history of the marmara sea and black sea from high resolution seismic and gravity core studies abstract lithologic and multi proxy paleoenvironmental data from 21 dated cores have been used to define three allostratigraphic units allounits within the late quaternary successions of the marmara sea and black sea allounits are bounded by unconformities and their correlative conformities in both regions allounit a extends from the seafloor downward to a 12 11 ka sequence boundary which is a major shelf crossing unconformity in water depths less than 100 110 m in deep basins of the marmara sea the lower part of allounit a designated subunit a2 is a laminated sapropel m1 on the shelf subunit a2 consists of backstepping delta lobes and early transgressive barrier islands and sand sheets allounit b has only been recovered in marmara sea cores collected at water depths greater than 90 m and represents basinal or prodeltaic deposition during the 23 12 ka late pleistocene lowstand during the last glacial maximum the shelves surrounding the marmara sea were subaerially exposed and deltas of allounit b accumulated along the present day shelf edge following the post glacial rise of global sea level to 75 m at 12 ka the marmara sea quickly became inundated and thereafter rose in synchroneity with the mediterranean by 10 ka the black sea rose to start spilling into the marmara sea leading to establishment of a brackish water lid that has persisted to the modern day the strongest black sea outflow began at 10 ka and persisted to 6 ka promoting the accumulation of sapropel m1 in the deep marmara sea and progradation of an overflow delta just south of the exit from the bosphorus strait allounit c is a laminated sapropel m2 in basinal cores dated at 30 23 ka like m1 it is believed that m2 accumulated during a period of increased brackish water input into the marmara sea mainly from the black sea in the black sea wave erosion kept the shelf stripped of unconsolidated sediments during the falling sea level associated with the last glaciation and subsequent early stages of the post glacial holocene transgression this erosion created a major unconformity shelf edge deltas of allounit b received their sediment during the last lowstand from small rivers that likely coalesced into a single system toward the shelf edge at modern water depths of 100 to 110 m these deltas were active until 11 10 5 ka subsequently sea level in the black sea rose to 40 m by 10 ka and a set of backstepping barrier islands developed on the shelf as part of the associated transgressive systems tract once water level reached 40 m continued sea level rise stalled until 9 ka as the black sea began to spill across the bosphorus strait into the marmara sea

architecture of late orogenic quaternary basins in northeastern mediterranean sea abstract in the northeastern mediterranean sea pliocene to quaternary depocentres have formed in extensional basins bounded by splays of the east anatolian transform fault this tectonic regime is superimposed on a miocene and older back arc environment that experienced late miocene compression along the misis kyrenia thrust which now lies in the middle of the extensional zone the thrust zone is now represented by a narrow horst that appears to be bounded by strike slip faults pliocene quaternary extension took place on listric fault fans that are orthogonal to the bounding transform splays and sole at a messinian evaporite horizon and on some deeper soling listric faults parallel to and near the bounding faults the rapid extension has resulted in progressive landward migration of paleoshorelines and low depositional gradients glacio eustatic fluctuations in shoreline positions strongly influenced sediment distribution most sediment dispersion was from deltaic plumes with turbidites of minor significance depocentres landward of the maximum seaward extent of paleoshorelines were formed almost entirely by tectonic subsidence minor deep water depocentres controlled by halokinesis accumulated mud turbidites during extreme low stands of sea level

precambrian paleosols in canada although at least 38 precambrian paleosols have been reported in canada few have received the attention afforded most other geological phenomena the most intensively studied of these are widely distributed early proterozoic paleosols associated with the sub huronian and matonabbee new name unconformities criteria that have been most useful in identifying precambrian paleosols in canada include macrostructures ascending protolith disruption saprolith and corestones micromorphology sepic texture and peds mineralogical changes dissolution transformation geochemical signatures ascending depletion of some elements characteristic weathering indices and distinctive colour contrast diagenetic mechanical and geochemical overprinting of the paleosols evident in many canadian examples includes paleosol compaction veins cutting pedogenic features and widespread alkali and alkaline earth element metasomatism metamorphism and deformation also tend to mask pedogenic features as attested by th

further evidence of abrupt holocene drowning of the black sea shelf a 1999 survey of the black sea continental shelf off the north central turkish seaport of sinop using a side scan sonar small remotely operated vehicles and a series of dredge lowerings located inspected and sampled an exposed high energy paleoshoreline at a depth of 155 m radiocarbon dating of mollusk shells collected from this ancient beach revealed that the marine flooding of the black sea took place between 7460 and 6820 yr b p all ages are reported in radiocarbon years not calendar years without correction for reservoir age or dendro calibration changing it from a lacustrine to marine environment this relic surface remained in contact with the bottom waters of the black sea for a long period of time before being draped by a thin layer of sapropel mud wood samples recovered from this same location were very well preserved and yielded dates as old as 3580 yr b p q 2000 elsevier science b v all rights reserved

architecture of stacked quaternary deltas correlated with global oxygen isotopic curve a distinctive pattern of quaternary stacked prograded deltas and intervening transgressions on a rapidly subsiding continental margin in the eastern mediterranean has been dated from offshore wells simple modeling using the quaternary oxygen isotope record as a proxy sea level curve has demonstrated that this pattern is a consequence of sea level change the progradational pattern is dependent principally on the amount of time that is available between successive highstands to provide accommodation space by subsidence on rapidly subsiding continental margins the standard pattern of stacked deltas can be used as a chronological tool in undated quaternary seismic sequences

searching for travertines calcretes and speleothems in deep time processes appearances predictions and the impact of plants common models for modern calcite precipitation in and around caves soils springs and streams involve co 2 supplied by thick high p co 2 biogenic soils which were probably thin or non existent before vascular plants indeed plant influenced chemical weathering might have caused accelerated terrestrial carbonate production from the devonian onwards however terrestrial carbonates have also been documented from the archaean proterozoic cambrian ordovician and silurian mechanisms which could have caused non marine carbonates to precipitate without organic rich soils are described and some geological events likely to have influenced non marine carbonate precipitation up to the origin of vascular plants are highlighted as organisms have evolved so have the petrographic characteristics of non marine carbonates some examples of this are also given here

columnar concretions in the visakhapatnam red sediments on the east coast of india abstract calcareous and siliceous columnar concretions occur in some of the visakhapatnam red sediments on the east coast of india the carbonate externally derived was rapidly precipitated in the intergranular space of the sediments by displacement of the fine material intense evaporation at the surface in the dry periods and the initial high permeability of the red sediments are considered to have produced the columnar forms the fine grained nature low mg calcite and the negative 13 c and 18 o ratios of the carbonate cement suggest an evaporative precipitation in a fresh water environment late diagenetic changes and compaction of the red sediments caused the modern development of the concretions to cease irregular basement topography largely controlled the localized distribution of the concretions in the red sediments siliceous concretions are confined to a narrow zone along the coast amorphous silica biogenous matter and silica microspheres constitute the cementing material of these concretions the microspheres indicate a precipitation of silica from saturated solutions in a protected environment the siliceous concretions are interpreted to have replaced the carbonate ones during the post pleistocene sea level rise in the visakhapatnam region

proterozoic aeolian quartz arenites from the hornby bay group northwest territories canada implications for precambrian aeolian processes abstract the hornby bay group is a middle proterozoic 2 5 km thick succession of terrestrial siliciclastics overlain by marine siliciclastics and carbonates a sequence of conglomeratic and arenaceous rocks at the base of the group contains more than 500 m of mature hematitic quartz arenite interpreted to have been deposited by migrating aeolian bedforms bedforms and facies patterns of modern aeolian deposits provided a basis for recognizing two sequences of aeolian arenite both sequences interfinger with alluvial wadi fan conglomerates and arenites deposited by braided streams depositional processes facies patterns and paleotopographic position of the arenites are consistent with modern sand sea dynamics distal aeolian facies in both sequences are composed of trough crossbed megasets deposited by climbing sinuous crested transverse dunes megasets comprise a gradational assemblage of tabular to wedge planar cosets formed by deflation reactivation of dune lee slopes and migration of smaller superposed aeolian bedforms small dunes and wind ripples megasets in the proximal facies are thinner display composite internal stratification and have a tabular planar geometry which suggests that they were formed by smaller straight crested transverse dunes most stratification within the crossbeds is inferred to have formed by the downwind climbing of aeolian ripples across the lee slopes of dunes remarkably few precambrian aeolian deposits have been reported previously this seems anomalous because most precambrian fluvial sediments appear to have been deposited by low sinuosity braided streams the emergent parts of which are prime areas for aeolian deflation frequent floods and rapid lateral migration of precambrian humid climate fluvial systems probably restricted aeolianite deposition to arid paleoclimates thus the apparent anomaly may reflect non recognition and or non preservation of aeolianites and or variations in some aspect of sand sea formation and migration unique to the precambrian reconstruction of the hornby bay group aeolianites using recently developed criteria for their recognition suggests that the latter reason did not exert a strong influence

an abrupt drowning of the black sea shelf abstract during latest quaternary glaciation the black sea became a giant freshwater lake the surface of this lake drew down to levels more than 100 m below its outlet when the mediterranean rose to the bosporus sill at 7 150 yr bp 1 saltwater poured through this spillway to refill the lake and submerge catastrophically more than 100 000 km2 of its exposed continental shelf the permanent drowning of a vast terrestrial landscape may possibly have accelerated the dispersal of early neolithic foragers and farmers into the interior of europe at that time

evaluation of cold water carbonates as a possible paleoclimatic indicator abstract the common belief currently shared by many geoscientists concerning the climatic interpretation of limestones is that a warm water environment is essential this concept is not necessarily true because the rate and extent of terrigenous sediment dilution rather than water temperature is the primary factor determining whether or not a limestone forms at nearshore or continental shelf depths because carbonate productivity is lowest in cold climates however caco3 abundance and the thickness of carbonate accumulations tend to be least at high latitudes in this regard present day continental shelves and beaches offer a poor model for comparing cold water and warm water carbonates because of the generally emergent continental tectonic framework recent eustatic sea level changes and the presence of ice caps at the modern poles typically the influence of climate on non reef continental shelf and beach environments cannot be clearly distinguished by the presence or absence of major taxonomic groups faunal diversity and equitability are more sensitive in this regard the absence of shelf depth inorganic carbonate precipitates micrite envelopes and peloids may also point to the cold water origin of a rock skeletal mineralogy and oxygen isotopes of certain unrecrystallized carbonates may be good paleoclimatic indicators however trace elements and physical textural attributes of the carbonate fraction are probably temperature insensitive previous studies of high latitude continental shelves have concentrated merely on the abundance of calcareous material and there is seemingly a disproportionate amount of information with respect to low latitude carbonate studies further research on cold water carbonates may open up new avenues for alternative paleoenvironmental and paleoclimatic interpretations

stratal architecture of western mediterranean margins as the result of the stacking of quaternary lowstand deposits below glacio eustatic fluctuation base level abstract through a comparison of high resolution seismic stratigraphy of seven western mediterranean margins similarities and differences in stratigraphic architecture were highlighted and a hierarchy of controlling factors was established the areas are northwestern alboran ebro and northern catalonia in the spanish margin rho ne in the french margin and tuscany latium and calabria in the italian tyrrhenian margin despite their different tectonic physiographic and depositional setting the seismic facies and growth pattern of the middle late pleistocene deposits are comparable the margins are in fact the result of the stacking of lowstand systems tracts of 4th order depositional sequences bounded by polygenetic unconforniities on the shelf and condensed sections on the upper slope this lowstand nature results from the high frequency 100 ka high amplitude 100 m asymmetry falling 65 of the time and stationariness between 10 and 120 m with respect to the present of the glacio eustatic sea level curve if eustasy directly controls the types of deposits making up the margins tectonism conditions their growth pattern as it is the only factor accounting for similarities and differences in the external geometry stratal pattern and distribution of the middle late pleistocene depositional sequences an evolutionary model for the quaternary growth of young passive continental margins is proposed in this model tectonics determines the degree of preservation of lowstand deposits because it conditions the accommodation space left below the erosional profile produced by each glacio eustatic cycle thus some of the sequence stratigraphy principles widely used to set up the model have been modified and adjusted to take into consideration the peculiar nature of quaternary glacio eustasy

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

steam output from fumaroles of an active volcano tectonic and magmatic hydrothermal controls on the degassing system at vulcano aeolian arc the results from measurements of extensive parameters steam output and exhaling surface area taken at the crater fumarolic field of vulcano island aeolian arc southern italy are reported along with a detailed description of the measuring method the steam emission rate increased by 1 order of magnitude during the observation time 1983 1995 while its concentration in the released gases was only slightly changed during the same period the total exhaling surface expanded from 50 m2 to more than 2400 m2 and evolved following preferential trends that coincide with the main tectonic structures of the island the observed peaks in steam output show a positive correlation with episodes of volcanic activity unrest the temporal increase of steam output and the observed development in the exhaling surface areas are consistent with a volcano tectonic triggering of the exhaling activity particularly the peaks in the steam output are interpreted as a consequence of degassing from an active magma slowly moving toward the surface

the circulation and hydrography of the marmara sea abstract a comprehensive set of data collected during 1986 1992 reveal seasonal and interannual variability in the circulation and hydrography of the marmara sea waters which have contrasting properties and originate from the adjacent basins supply the two layer stratified flows in the sea of marmara turbulent entrainment into the upper layer in the exit region of the bosphorus jet and wind stirring in winter both contribute equally to the basin vertical mixing the upper layer circulation of the marmara sea is determined from adcp measurements and from dynamical calculations based on hydrographic data the mean upper layer circulation is anti cyclonic mainly driven by the southward flowing bosphorus jet in the enclosed domain the bosphorus inflow is well defined except during the periods of low discharge in autumn and winter when the jet becomes weaker and tends to become attached to the west coast near the exit mediterranean water entering from the dardanelles supply the suhalocline layer the negatively buoyant plume of well oxygenated water is the only means of renewal of the deep waters partially compensating for the oxygen consumed by the degradation of organic matter sinking from the upper layer into the lower layer yet the subhalocline waters remain permanently deficient in oxygen as a result of the internal balances of diffusion advection and consumption the depth to which the plume penetrates is a function of the seasonal characteristics of the inflow density modified in the strait and the weak interior stratification

precambrian non marine stromatolites in alluvial fan deposits the copper harbor conglomerate upper michigan laminated cryptalgal carbonates occur in the precambrian copper harbor conglomerate of northern michigan which was deposited in the keweenawan trough an aborted proto oceanic rift this unit is composed of three major facies deposited by braided streams on a large alluvial fan complex coarse clastics were deposited in braided channels predominantly as longitudinal bars whereas cross bedded sandstones were deposited by migrating dunes or linguoid bars fine grained overbank deposits accumulated in abandoned channels gypsum moulds and carbonate filled cracks suggest an arid climate during deposition stromatolites interstratified with these clastic facies occur as laterally linked drapes over cobbles as laterally linked contorted beds in mudstone as oncolites and as poorly developed mats in coarse sandstones stromatolites also are interbedded with oolitic beds and intraclastic conglomerates stromatolitic microstructure consists of alternating detrital and carbonate laminae and open space structures radialfibrous calcite fans are superimposed on the laminae the laminae are interpreted as algal in origin whereas the origin of the radial fibrous calcite is problematic the stromatolites are inferred to have grown in lakes which occupied abandoned channels on the fan surface standing water on a permeable alluvial fan in an arid climate requires a high water table maintained by high precipitation or local elevation of the water table possibly due to the close proximity of a lake occurrence of stromatolites in the upper part of the copper harbor conglomerate near the base of the lacustrine nonesuch shale suggests that these depositional sites may have been near the nonesuch lake

calcrete conglomerate case hardened conglomerate and cornstone a comparative account of pedogenic and non pedogenic carbonates from the continental siwalik group punjab india the occurrence of authigenic carbonates formed in three different environmental situations within the continental siwalik group has been used to compare the lithological and petrographic characters of the contrasted lithofacies the three lithofacies are 1 calcrete conglomerate 2 case hardened conglomerate 3 cornstone pedogenic nodular calcrete the calcrete conglomerate facies laterally intertongues with the channel conglomerates it consists of pisolites which are interpreted to have formed from carbonate rich spring waters emerging on to the gravelly substrate of dry abandoned channels the laminae characteristics of these pisolites are distinctly different from those of marine origin and also from comparable biogenic materials case hardened conglomerate occurs in the youngest part of the siwalik stratigraphic column in boulder conglomerates having limestone as the principal clast component this lithofacies has resulted from cementation of the conglomerate through continued dissolution and re precipitation of calcite by meteoric water downwards from the surface it displays a coarsely crystalline sparry calcite cement with no evidence for displacive growth or replacement by calcite cornstones nodular calcrete occur in several sedimentary cycles of the middle siwalik sub group these are immature and commonly associated with thinly bedded sandstones levee and red shales overbank this lithofacies is a result of concentration of carbonate through capillary action associated with pedogenic activity ooids developed in cornstone are essentially micritic in nature and usually composed of less than five indistinct laminae

paleoclimatic and paleoceanographic conditions leading to development of sapropel layer s1 in the aegean sea abstract sapropel s1 occurs as 25 35 cm thick black weakly laminated muds in aegean sea cores s1 was deposited between 9600 and 6400 yr b p during a period of isotopically depleted and relatively cool surface waters micro faunal and floral data indicate a major reduction in surface waters salinity during the deposition of s1 and oxygen isotopic data show a northerly fresh water source relatively light 13 c org and high pollen spore concentrations in s1 suggest increased influx of terrestrial organic carbon probably supplied by major rivers draining into the northern aegean sea benthic foraminifera indicate high nutrient low oxygen bottom waters for s1 and together with silt sized hematite and manganese coatings suggest that during the deposition of s1 surface sediments were oxic visual and xrd evidence of pyrite in s1 together with enrichments in s cu zn as ni cr and fe suggest that subsurface conditions were sufficiently reducing for so 4 2 reduction to occur probably by diffusion from surface oxic into subsurface anoxic sediments palynomorphs in s1 show large increases in terrestrial pollen and spores with the floral assemblage indicating significant influx from northern european rivers and minor african components associated with increased summer monsoonal rain abundance of dinoflagellates and amorphogen suggests some increase in primary productivity in response to increased influx of humic compounds however there is no evidence of upwelling the clay fraction in s1 shows notable decreases in smectite and kaolinite and reciprocal increases in illite and chlorite the combined data suggested that the evolution of s1 in the aegean sea largely resulted from stagnation of the surface waters during the final disintegration of the continental ice sheets rather than an increase in primary productivity and higher preservation of organic carbon on the sea floor

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

concretions in glacial sediments at seglvatnet norway abstract concretions in pleistocene glacial sediments at seglvatnet norway include a wide variety of forms the simplest of which apparently reflects relatively uniform growth rates in different directions the preferred orientation of others may be associated with water movement through the sediments concretion shape generally is influenced by the grain size and bedding of the enveloping sediments some concretions may have formed during or soon after deposition of the sediments others are forming at present

early holocene marine flooding of the black sea abstract echo sounding data recorded in the black sea in 1969 imaged a chain of hills 5 to 150 m high at a depth of 2000 2200 m that resemble hills on the lower continental rise like those hills the features in the western black sea may have been created by bottom currents the easterly flowing currents inferred to have formed the hills may be related to a catastrophic flood of the black sea from the sea of marmara 7150 yr ago

evaporites marine or non marine division of evaporites into those types that retain information about primary mineralogy textures and structures primary evaporites and those types so extensively altered that few or no primary features remain secondary evaporites only primary evaporites can give unequivocal data bout their marine or non marine origin to help evaluate such primary deposits they have been further divided using the following attributes 1 whether the depositional setting was marine or non marine 2 whether the source water was a seawater b meteoric c hydrothermal d diagenetic e volcanogenic or f mixed specific criteria for making distinctions are 1 kinds of fossils 2 sedimentology of the associated non saline facies 3 kinds of primary saline minerals 4 association of such saline minerals both in qualitative and quantitative terms 5 trace element isotope and fluid inclusion geochemistry of such saline minerals modified journal abstract

mediterranean vegetation lake levels and palaeoclimate at the last glacial maximum the apparent conflict between pollen evidence for widespread artemisia steppe1 6 implying semi arid conditions and geomorphological evidence for high lake levels4 7 11 has produced controversy about the ice age palaeoclimate of the mediterranean region here we use a water balance model12 to predict catchment runoff and a biome model13 to predict vegetation type to reconstruct the palaeoenvironment around lake loannina a type locality for the northern mediterranean region we show that both sets of evidence are compatible with a summer dry winter wet regime with seasonal temperature anomalies similar to those predicted by atmospheric model simulations of the last glacial maximum14 18 the drying effect of the cold north atlantic ocean may have been counteracted in winter by increased storm frequency under a southward shifted jet stream as shown by several atmospheric models16 18

last glacial holocene paleoceanography of the black sea and marmara sea stable isotopic foraminiferal and coccolith evidence multi proxy data and radiocarbon dates from several key cores from the black sea and marmara sea document a complex paleoceanographic history for the last v30 000 yr the marmara sea was isolated from both the black sea and the aegean sea during glacial periods when global sea level lowering subaerially exposed the shallow sills at the straits of bosphorus and dardanelles i e lake stage and reconnected through both straits during interglacial periods when rise of global sea level breached the shallow sills i e gateway stage micropaleontological data show that during the lake stage the surface water masses in both the marmara sea and black sea became notably brackish however during the gateway stages there was a low salinity surface layer and normal marine water mass beneath two sapropel layers are identified in the marmara sea cores sapropels m2 and m1 were deposited between v29 5 and 23 5 ka and v10 5 and 6 0 ka respectively micropaleontological and stable isotopic data show that the surface water salinities were reduced considerably during the deposition of both sapropel layers m2 and m1 and calculation using planktonic foraminiferal transfer functions shows that sea surface temperatures were notably lower during these intervals the presence of fauna and flora with black sea affinities and the absence of mediterranean fauna and flora in sapropels m1 and m2 strongly suggest that communication existed with the black sea during these times a benthic foraminiferal oxygen index shows that the onset of suboxic conditions in the marmara sea rapidly followed the establishment of fully marine conditions at v11 10 5 ka and are attributed to black sea outflow into the marmara sea since 10 5 ka these suboxic conditions have persisted to the present the data discussed in this paper are completely at odds with the flood hypothesis of ryan et al 1997 and ryan and pitman 1999 crown copyright 2002 elsevier science b v all rights reserved

the association of sulphate evaporites stromatolitic carbonates and glacial sediments examples from the proterozoic of australia and the cainozoic of antarctica abstract carbonate sediments are often considered diagnostic of warm water environments and thus the occurrence of dolomite and limestone beds within and immediately overlying many late proterozoic glacial deposits tillites has long been a source of controversy stromatolites are also conventionally thought to be warm water indicators we describe two examples of stromatolitic dolomite occurring together with barite at the top of late proterozoic glacial sequences in the amadeus and ngalia basins of central australia problems of interpretation may be largely resolved after examination of published data on antarctic lakes antarctic lakes of high salinity occupy enclosed glacial basins in both the vestfold hills and the taylor and wright dry valleys lake bonney is the most comprehensively described example carbonate sediments sulphate evaporites and even stromatolites are common components of cold arid climate lakes the stromatolitic mats and their constructing cyanobacteria are similar to those described from warmer climates the tundra plains and lakes and coastal lagoons of northern canada and siberia are better geomorphic analogues for the proterozoic deposits and these too seem to contain analogous sediments but only brief descriptions are available we suggest that environments such as these provide modern analogues of the association of proterozoic glacial sediments with carbonates evaporites and stromatolites

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

paleoclimatology of nonacho basin early proterozoic northwest territories canada abstract numerous features of paleoclimatic significance are preserved in terrestrial strata of nonacho basin early proterozoic minimal chemical weathering is indicated by relic corestones grus and talus and the absence of chemical alteration zones at the basal unconformity humid conditions are indicated by 1 dominance of siliciclastic lacustrine deposits even in lakes that had restricted drainage 2 paucity of caliche in extensive alluvial fan deposits 3 near absence of debris flows in alluvial fan deposits 4 absence of large scale high angle cross stratification in eolian deposits and 5 penecontemporaneous variegated redbeds drab sandstones red mudstones minimal chemical weathering under humid conditions implies a cold climate this is supported by published paleomagnetic data humid conditions implies a cold climate this is supported by published paleomagnetic data which indicate that nonacho basin probably formed at paleolatitudes of 40 55 by talus deposits formed as a result of frost action and by penecontemporaneous stratiform sandstone breccias for which the early cementing agent probably was ice high elevations probably contributed to the low temperatures the nonacho group probably was deposited in a moist continental climate with cold winters characterized by repeated freeze thaw cycles local chemically precipitated lacustrine sediments and caliche indicate brief dry intervals

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

late quaternary sedimentation and high resolution sequence stratigraphy of the east texas shelf the shelf margin deltas of the area show a complex pattern of progradation and aggradation that varies from one delta to the next this complexity is due predominantly to the different response of systems with different sediment supplies to fifth order eustatic fluctuations before we understood these autocyclic effects attempts at relating seismic stratigraphic changes to the oxygen isotope curve our proxy for sea level change were unsuccessful

reconstruction of holocene precipitation patterns in europe using pollen and lake level data abstract lake level data can be used to refine palaeoclimate reconstructions based on pollen data this approach is illustrated for the european holocene estimates of p pet precipitation minus potential evapotranspiration were first inferred from modern pollen analogues the pollen based estimates were then compared with the status of lakes within a 5 radius analogues with p pet anomalies inconsistent with the lake level changes were rejected the constrained sets of analogues were used to estimate continental scale patterns of annual mean temperature and annual precipitation at 3000 yr intervals estimated temperature anomalies differed only slightly from the unconstrained reconstructions estimated precipitation anomalies however showed improved spatial coherence and increased regional contrast and were occasionally reversed in sign the effect of the constraint was to impose a rational selection among almost equally similar modern pollen analogues with similar temperatures but widely varying moisture regimes the resulting maps showed clear spatially coherent patterns of change in precipitation as well as temperature suitable for comparison with climate model results further improvement of these maps will become possible as a more extensive coverage of lake level data is obtained

quaternary sedimentary history of adana cilicia and iskenderun basins northeast mediterranean sea detailed single channel airgun and 3 5 khz profiles from the northeastern mediterranean sea show that the continental shelf is formed by superimposed deltaic successions depositional sequences separated by major erosional unconformities each depositional sequence is composed of a sigmoid prograding package overlain by an oblique prograding package representing respectively delta progradation during high and low sea levels of interglacial and subsequent glacial stages during the glacio eustatic lowstands of sea level deltas prograded seaward the present day shelf break denotes the topset to forest transition at maximum progradation during the last glacial period during post glacial transgressions the deltas initially lost their dynamic equilibrium with the environment and rapidly retreated landward leading to the deposition of a thin veneer of sediments originating from reworking of formerly coastal sediments at the highstand position the deltas were re established in the ancestral adana bay and foreset progradation started chronology suggests that the cilicia and iskenderum basins are subsiding at rates of 0 38 m 1000 yr 1 and 0 33 m 1000 yr 1 respectively seismic reflection profiling shows that delta architecture in the adana cilicia and iskenderun basins is mainly controlled by glacio eustatic sea level fluctuations and continuous basin subsidence

late glacial holocene paleoclimatic and paleoceanographic evolution of the aegean sea micropaleontological and stable isotopic evidence abstract late glacial to holocene paleoclimatic and paleoceanographic changes are examined using records of calcareous and organic walled marine microfossils pollen and terrestrial spores and oxygen isotope data in cores from the aegean sea basins planktic foraminiferal coccolith and dinoflagellate data show that the late glacial holocene transition in the region was associated with a large warming of surface water mediterranean based paleotransfer functions for planktic foraminifera show a 5 10 c increase in surface water temperature from 14 000 to 9600 yr b p estimates of surface water oxygen isotopic composition 18 o w derived from planktic foraminiferal oxygen isotopic and transfer function data indicate that this warming was associated with a 2 0 to 2 5 reduction in 18 o w transfer function results indicate corresponding 1 0 to 1 5 salinity reductions for this tim ca 6400 9600 yr b p throughout the aegean sea pollen dinoflagellate and isotopic data show that the early holocene excess fresh water originated from rapid melting of the northern european and siberian ice sheets supplied primarily from the black sea by the opening of bosphorus and dardanelles channels during the post glacial sea level rise and supplemented by major rivers entering the aegean sea continuous outflow of fresh water into the aegean sea provided a low salinity surface lid preventing the ventilation of the deep water benthic foraminifera shows a major turn over that indicates low dissolved oxygen however bottom waters were not anoxic sapropel level s1 resulted from a combination of stagnant deep water in isolated depressions increased terrigenous organic matter and periods of high primary productivity as indicated by pollen and dinocysts respectively the surface water temperature and salinity reached present day values at 6400 yr b p with little subsequent change despite the major deforestation onshore