rapid stepwise onset of antarctic glaciation and deeper calcite compensation in the pacific ocean the ocean depth at which the rate of calcium carbonate input from surface waters equals the rate of dissolution is termed the calcite compensation depth at present this depth is 4 500 m with some variation between and within ocean basins the calcite compensation depth is linked to ocean acidity which is in turn linked to atmospheric carbon dioxide concentrations and hence global climate1 geological records of changes in the calcite compensation depth show a prominent deepening of more than 1 km near the eocene oligocene boundary 34 million years ago 2 when significant permanent ice sheets first appeared on antarctica3 4 5 6 but the relationship between these two events is poorly understood here we present ocean sediment records of calcium carbonate content as well as carbon and oxygen isotopic compositions from the tropical pacific ocean that cover the eocene oligocene boundary we find that the deepening of the calcite compensation depth was more rapid than previously documented and occurred in two jumps of about 40 000 years each synchronous with the stepwise onset of antarctic ice sheet growth the glaciation was initiated after climatic preconditioning7 by an interval when the earth s orbit of the sun favoured cool summers the changes in oxygen isotope composition across the eocene oligocene boundary are too large to be explained by antarctic ice sheet growth alone and must therefore also indicate contemporaneous global cooling and or northern hemisphere glaciation

late holocene coastline and landscape changes to the west of ephesus turkey abstract palaeogeographical research regarding coastline and landscape changes has been conducted in the kucuk menderes graben and the environs of the ancient city of ephesus in western turkey for a few decades based on geophysical data multi proxy and microfaunal analyses of sediment cores 14 c ams age estimates and diagnostic ceramics this study presents for the first time results of an area close to the present coastline where a byzantine church is located on top of a small hill the results reveal that this mica schist hill turned into an island during the 2nd 1st millennium bce it was reconnected to the mainland via a tombolo during the 5th century ce drill cores and geophysical measurements surrounding the hill show massive stone layers which were deposited intentionally during the 5th 6th century ce when the byzantine church was built geophysical images point to wall structures in the surroundings of the hill the area to the northeast hosts a small harbour site when the coastline continued to shift further to the west this site was still connected to the sea by the kucuk menderes river

quaternary deposits of the buyuk menderes graben in western anatolia turkey implications for river capture and the longest holocene estuary in the aegean sea abstract the buyuk menderes graben is a seismically active depositional basin in the n s extensional tectonic region of western anatolia turkey it extends in an e w direction and is bounded by the aegean sea to the west the infill of this tectonic basin comprises ca 850 m and 245 m thick clastic sequences of neogene and quaternary respectively and the quaternary part of the basin fill is presented here by the help of seismic sections and boreholes results show that the studied succession was made of unconsolidated mostly fine grained clastic sediments of marine and continental sequences interfingered with each other the marine counterpart forms three relatively short approx 30 km and one long approx 100 km from modern coastline sediment wedges representing sea transgressions onto the graben the last one was a rapid incursion that occurred in the middle holocene forming the longest estuary of the aegean sea in western anatolia the filling of this estuary caused the decline of some historical harbours and settlements in the region while marine based events occurred in the west of the graben alluvial and fluvial processes produced marginal and axial deposits in the east of graben respectively in general the continental succession of quaternary is thinner than its marine equivalent probably due to sea level fluctuations in addition the sedimentation rate increased suddenly during deposition of the last marine sequence estuarine deposits in the holocene it is likely that this was the result of enlargement of the drainage area of the river buyuk menderes due to a river capture that occurred in the latest stages of pleistocene

the salinity temperature and δ18o of the glacial deep ocean we use pore fluid measurements of the chloride concentration and the oxygen isotopic composition from ocean drilling program cores to reconstruct salinity and temperature of the deep ocean during the last glacial maximum lgm our data show that the temperatures of the deep pacific southern and atlantic oceans during the lgm were relatively homogeneous and within error of the freezing point of seawater at the ocean s surface our chloride data show that the glacial stratification was dominated by salinity variations in contrast with the modern ocean for which temperature plays a primary role during the lgm the southern ocean contained the saltiest water in the deep ocean this reversal of the modern salinity contrast between the north and south atlantic implies that the freshwater budget at the poles must have been quite different a strict conversion of mean salinity at the lgm to equivalent sea level change yields a value in excess of 140 meters however the storage of fresh water in ice shelves and or groundwater reserves implies that glacial salinity is a poor predictor of mean sea level

late valanginian barremian early cretaceous palaeotemperatures inferred from belemnite stable isotope and mg ca ratios from bersek quarry gerecse mountains transdanubian range hungary abstract a high resolution stable isotope study of upper valanginian barremian early cretaceous belemnites from bersek quarry gerecse mountains transdanubian range hungary is presented over 190 belemnite rostra including hibolithes subfusiformis duvalia dilatata and conohibolites gladiiformis have been analysed for oxygen and carbon isotopes and for trace element geochemistry the obtained carbon isotope curve shows a long term decrease from 1 2 in the upper valanginian to 0 5 in the upper hauterivian followed by more variable values in the early barremian superimposed on this trend are a number of possible shorter term peaks this pattern broadly follows published carbon isotope curves for the same interval and is therefore thought to reflect a global rather than a regional signal the oxygen isotopes show the most positive values in the uppermost valanginian and become increasingly more negative through the hauterivian into the barremian such changes are interpreted as an increase in marine temperatures through the section the mg ca data paralleling the oxygen isotope trend confirms our temperature interpretation the oxygen isotope ratios are generally more negative and therefore allow us to infer warmer temperatures than those derived from belemnites from time equivalent sections in germany and speeton uk consistent with the more southerly latitudinal position of the gerecse mts within the tethys ocean the oxygen isotope and mg ca data also reveal habitat differences for the different belemnite groups analysed vaunagites pistilliformis belemnites pistilliformis and hibolithes typically have more negative oxygen isotope values than pseudobelus and duvalia and are therefore interpreted to have lived in warmer and or shallower parts of the water column consistent with previous interpretations

paleoglacial records from kavron valley ne turkey field and cosmogenic exposure dating evidence abstract kavron valley lies in the kackar mountain range of northeastern anatolia and is a north south oriented typically u shaped glacial valley consisting of a main and three tributary valleys the quaternary units that outcrop in this valley have been mapped and 22 samples have been processed for surface exposure dating using cosmogenic 10 be according to the 10 be ages the advance of the kavron paleoglacier began at least 26 0 1 2 kyr ago with the last glacial maximum lgm advance continuing until 18 3 0 9 kyr after this time the kavron paleoglacier receded although the magnitude of this recession is still unknown subsequent to this retreat the glacier most probably separated into three smaller glaciers that were restricted to the tributary valleys ifrit derebasi and mezovit paleoglaciers the main valley was definitely ice free by 15 5 0 7 kyr ago with the mezovit paleoglacier completing its recession around 15 5 0 6 kyr a late glacial advance took place around 13 0 0 8 to 11 5 0 8 kyr and little ice age moraines appear to be absent our results from the kavron valley system seem to be consistent with the lgm paleoclimate record of anatolia which has been delineated by data gathered from lowlands and lakes the deposition of red clay layers in the northwestern black sea and the deposition of heinrich 1 layers in the north atlantic

reevaluation of the oxygen isotopic composition of planktonic foraminifera experimental results and revised paleotemperature equations cultured planktonic foraminifera orbulina universa symbiotic and globigerina bulloides nonsymbiotic are used to reexamine temperature 18o relationships at 15 25 c relationships for both species can be described by linear equations equations for o universa grown under low light ll and high light hl share a slope of 4 80 0 21 c 1 with a hl ll offset of 0 33 due to symbiont photosynthetic activity the effect of co32 on o universa is 0 002 mol 1 kg 1 and is insensitive to temperature for g bulloides ontogenetic effects produce size related trends in temperature 18o whereby larger shells are enriched in 18o relative to smaller specimens the o universa temperature 18o relationships are more accurate than previously published equations for describing plankton tow data our equations do not explain planktonic core top data with the same precision but provide a good fit to benthic cibicidoides data below 10 c temperature 18o relationships for g bulloides provide good agreement with field data for this species from the northeast pacific

late holocene human environmental interactions in the eastern mediterranean settlement history and paleogeography of an ancient aegean hill top settlement abstract interactions between settlement history and landscape evolution of a hill top settlement on the west anatolian coast near ancient pergamon modern bergama were studied by a combination of archaeological and geographical investigations ceramics ancient literary and epigraphic texts numismatics and architectural remains show that the hill top had been populated since late bronze age times from the sixth century bc until the change of the eras the hill was occupied by a greek polis atarneus and was abandoned afterwards it was newly populated in the second half of the twelfth and the first half of the thirteenth century ad the lithostratigraphy of nine drilling cores arranged in three transects and dated by ams radiocarbon dating shows that during the past 4000 years the sedimentary plains surrounding the settlement hill were aggraded by braided and meandering rivers while colluviation and alluvial fan deposition occurred at the foot slopes sedimentation totaled about 5 7 m in the past 4000 years evidencing a drowning of the landscape in terrestrial sediments although channels shifted repeatedly and alluvial fan deposition fluctuated the depositional system did not change in general during the past 4000 years this striking resistance to the changing settlement and land use intensity is an effect of the distinct modification of the slopes through terracing that countervailed erosion and likewise increased the buffering capacity of the sediment storages on the slopes there is no evidence that landscape deterioration contributed to the abandonment of the settlement hill rather socio economic factors were crucial for the rise and fall of the settlements occupying the hill

geoscience of ancient mediterranean harbours abstract although much has been written on the subject of ancient mediterranean harbours the relatively new area of harbour geoarchaeology remains dispersed in the geoscience and archaeological literature over a decade of research has amassed rich and varied datasets of anthropogenically forced coastal evolution with a remarkable number of between site analogies this new research field also shows the rich potential of geoscience to reconcile important archaeological questions no single publication however has yet drawn on these geological patterns to yield a detailed overview suitable for geoscientists and environmental archaeologists the aim of this review article is to 1 discuss how ancient harbours have come to be preserved in the geological record 2 expound the basic principles and palaeoenvironmental tools underpinning ancient harbour geoarchaeology 3 outline some of the most significant research advances made and 4 discuss a new chrono stratigraphic model applicable to harbour sequences

microstructural and geochemical perspectives on planktic foraminiferal preservation glassy versus frosty in recent years it has become apparent that the cool tropic paradox of paleogene and cretaceous greenhouse climates arises because of the diagenetic alteration of tropical planktic foraminiferal calcite near the seafloor yielding artificially high 18o values because the mg ca compositions of foraminiferal and inorganic calcite are thought to be quite different mg ca measurements should be a sensitive way of monitoring diagenetic alteration here we examine the extent of diagenetic alteration of eocene planktic foraminiferal calcite using scanning electron microscope imaging of foraminiferal test microstructures and geochemical 18o and mg ca analyses we compare microstructural and geochemical characteristics between given species exhibiting two contrasting states of preservation those that appear frosty under reflected light and those that appear glassy microstructural evidence reveals extensive diagenetic alteration of frosty foraminiferal tests at the micron scale while 18o analyses document consistently higher 18o and therefore lower paleotemperatures in this material yet we find that 18o offsets between species in these frosty foraminiferal assemblages appear to be generally preserved suggesting that frosty foraminifera remain valuable for generating relatively short approximately 1 myr paleoceanographic time series that do not demand absolute estimates of paleotemperature we also find that the observed increase in mg ca for planktic foraminifera exhibiting diagenetic alteration compared to glassy taphonomies is far smaller than would be expected from the addition of inorganic calcite based on laboratory derived mg2 partition coefficients our findings imply that a much lower mg2 partition coefficient controls inorganic calcite formation in deep sea sedimentary sections in accordance with the findings of baker et al 1982

human influence and the changing geomorphology of mediterranean deltas and coasts over the last 6000 years from progradation to destruction phase the present geomorphology of the mediterranean s coasts is largely a product of an intricate long term relationship between nature and human societies a cradle of ancient civilisations the mediterranean has seen its shores occupied by humans since prehistory and is therefore a particularly pertinent unit of analysis the morphotectonic context and other forcing agents e g climate shaped out a highly diversified coastal morphology and generated a sediment supply regime potentially favourable to the formation of numerous open coast deltas and bay head deltas in infilled rias as sea level stabilised during the mid holocene this supply of riverine sediment has also been the key agent in mediating human occupation of the mediterranean s clastic coasts expressions of this relationship have been extensively archived in clastic coastal deposits including base level deltaic and estuarine sedimentary sinks which comprise records to explore the interactions between geosystems and the human environment the stratigraphic sequences in these coastal sedimentary archives comprise in many places a clearly identified anthropogenic signature notably in ancient harbours some of which underwent extremely rapid silting up due to massive sediment sourcing generated by new agricultural practices from the neolithic onwards increasing human influence especially over the last 3000 years has been in turn an important driver of changes in sediment supply strongly modulating deltaic development pulses of sediment supply from catchments rendered vulnerable by human perturbations during the roman period resulted in a new cycle of inception of many other deltas and in rapid delta growth e g the ebro the po the arno and the ombrone another progradation dynamic during the little ice age at a time of strong rural population growth river discharge increases technological developments and urbanisation further consolidated delta growth understanding the life cycle of these deltas since their initial formation is in turn key to unravelling the relative role of natural and anthropogenic forcing agents rapid climate changes are deemed to have contributed through both the stripping of landscapes rendered fragile by human activities and active fluvial sediment transport to the coast but disentangling climate change effects from human impacts in the mediterranean remains a challenge the patterns of subsequent deltaic growth and delta morphodynamics reflect adaptations to pulsed sediment supply river discharge variations the microtidal fetch limited context of the mediterranean and direct engineering interventions the progradation dynamic of the roman period and little ice age contrasts markedly with the situation of common coastal destabilisation over the last two centuries particularly well documented for the last 50 years this period has been characterised by reduced sediment flux to base level geosystems due to catchment reforestation retenion within reservoirs fluvial regulation and dredging resulting in the erosion of deltas and barrier lagoon and beach dune systems large stretches of shoreline and narrow coastal plains have been massively engineered for coastal defence and protection against erosion but also for the construction of marinas leisure harbours and artificial beaches resulting in the emergence of veritable artificial seafronts these interventions have collectively and progressively raised societies to a pervasive and overarching position in the geomorphic stability instability of the mediterranean s coasts a situation that will be exacerbated by pressures from sea level rise paving the way for rampant coastal erosion and delta destruction

latest eocene early oligocene climate change and southern ocean fertility inferences from sediment accumulation and stable isotope data abstract the earliest oligocene 33 5 ma is marked by a major step in the long term transition from an ice free to glaciated world the transition characterized by both cooling and ice sheet growth triggered a transient but extreme glacial period designated oi 1 high resolution isotope records suggest that oi 1 lasted for roughly 400 000 yr the duration of magnetochron 13n before partially abating and that it was accompanied by an ocean wide carbon isotope anomaly of 0 75 one hypothesis relates the carbon isotope anomaly to enhanced export production brought about by climate induced intensification of wind stress and upwelling particularly in the southern ocean to understand how this climatic event affected export production in the southern ocean biogenic silica opal and carbonate accumulation rates were computed for the sub polar indian ocean using deep sea cores from odp site 744 kerguelen plateau our findings suggest that net productivity in this region increased by several fold in response to the oi 1 glaciation in addition calcareous primary producers dominant in the late eocene were partially replaced by opaline organisms suggesting a trend toward seasonally greater surface divergence and upwelling in this sector of the southern ocean we attribute these changes to intensification of atmospheric oceanic circulation brought about by high latitude cooling and the appearance of a full scale continental ice sheet on east antarctica higher terrigenous sediment accumulation rates support the idea that wind induced changes in regional productivity were augmented by an increased supply of glacial dust and debris that provided limiting micro nutrients e g iron rich dust particles we speculate that the rapid changes in biogenic sediment accumulation in the southern ocean and other upwelling dominated regions contributed to the ocean wide positive carbon isotope anomaly by temporarily increasing the burial rate of organic carbon relative to carbonate carbon the changes in burial rates in turn may have produced a positive feedback on climate by briefly drawing down atmospheric pco2

upper cretaceous sequences and sea level history new jersey coastal plain we developed a late cretaceous sea level estimate from upper cretaceous sequences at bass river and ancora new jersey odp ocean drilling program leg 174ax we dated 11 14 sequences by integrating sr isotope and biostratigraphy age resolution 0 5 m y and then estimated paleoenvironmental changes within the sequences from lithofacies and biofacies analyses sequences generally shallow up section from middle neritic to inner neritic paleodepths as shown by the transition from thin basal glauconite shelf sands transgressive systems tracts tst to medial prodelta silty clays highstand systems tracts hst and finally to upper delta front quartz sands hst sea level estimates obtained by backstripping accounting for paleodepth variations sediment loading compaction and basin subsidence indicate that large 25 m and rapid 1 m y sea level variations occurred during the late cretaceous greenhouse world the fact that the timing of upper cretaceous sequence boundaries in new jersey is similar to the sea level lowering records of exxon production research company epr northwest european sections and russian platform outcrops points to a global cause because backstripping seismicity seismic stratigraphic data and sediment distribution patterns all indicate minimal tectonic effects on the new jersey coastal plain we interpret that we have isolated a eustatic signature the only known mechanism that can explain such global changes glacio eustasy is consistent with foraminiferal 18 o data either continental ice sheets paced sea level changes during the late cretaceous or our understanding of causal mechanisms for global sea level change is fundamentally flawed comparison of our eustatic history with published ice sheet models and milankovitch predictions suggests that small 5 10 10 6 km 3 ephemeral and areally restricted antarctic ice sheets paced the late cretaceous global sea level change new jersey and russian eustatic estimates are typically one half of the epr amplitudes though this difference varies through time yielding markedly different eustatic curves we conclude that new jersey provides the best available estimate for late cretaceous sea level variations

palaeoceanography broken greenhouse windows large and rapid global sea level changes indicate that polar ice sheets may have ephemerally existed during the cretaceous greenhouse climate two oxygen isotopic studies provide evidence for and against this conclusion

new oxygen isotope evidence for long term cretaceous climatic change in the southern hemisphere a new composite 18 o record generated from calcareous fine fraction and bulk sediments from the exmouth plateau details long term cretaceous climatic change at mid latitudes in the southern hemisphere assessment of new and previously published 18 o data indicates that a mid cretaceous global climatic optimum was achieved sometime between the time of the cenomanian turonian boundary and the middle turonian when surface ocean paleotemperatures were the highest of the past 115 m y periods of cooling and warming that reversed the general patterns were superimposed on long term aptian turonian warming and turonian maastrichtian cooling trends respectively extrapolation of southern hemisphere paleotemperature trends to maastrichtian paleotemperature data from a low latitude pacific guyot implies that maximum mid cretaceous low latitude paleotemperatures could have been in excess of 33 c

reconstructing middle to late holocene palaeogeographies of the lower messenian plain southwestern peloponnese greece coastline migration vegetation history and sea level change abstract the glacio eustatic sea level rise after the last glacial maximum lgm led to a worldwide flooding of shelf areas and the evolution of marine embayments and indentations its significant deceleration in mid holocene times resulted in the overcompensation by sediment yields and shoreline progradation in many areas at the southeastern part of the lower messenian plain southwestern peloponnese greece detailed investigations of the holocene stratigraphy revealed a maximum landward shoreline displacement around 3000 bc subsequently aggradational processes started to form a prominent beach ridge in the late 3rd millennium bc this is the substratum on which the early iron age poseidon sanctuary of akovitika was founded approx 900 850 bc palaeogeographic reconstructions based on 18 corings in the sanctuary and its surroundings revealed the later extension of adjacent marshland and gradual surface levelling due to seasonal inundations these findings represent probable reasons for the abandonment of the ceremonial site around 380 350 bc palynological studies of the vegetational changes provide evidence for early land use and reflect regional settlement activities initial degradation and burning of woodland during late neolithic times c 3500 3100 bc as well as significantly reduced human impact during the protogeometric dark ages c 1060 900 bc are proven additionally local relative mean sea level rsl change since 5000 bc was reconstructed based on 14c dated paralic peats

a multiple proxy and model study of cretaceous upper ocean temperatures and atmospheric co2 concentrations foraminiferal d 18 o and mg ca suggests that the ratio of magnesium to calcium in the turonian coniacian ocean may have been lower than in the albian cenomanian ocean perhaps coincident with an ocean 87 sr 86 sr minimum the carbon isotopic compositions of distinct marine algal biomarkers were measured in the same sediment samples the d 13 c values of phytane combined with foraminiferal d 13 c and inferred temperatures were used to estimate atmospheric carbon dioxide concentrations through this interval estimates of atmospheric co2 concentrations range between 600 and 2400 ppmv within the uncertainty in the various proxies there is only a weak overall correspondence between higher lower tropical temperatures and more less atmospheric co2 the genesis climate model underpredicts tropical atlantic temperatures inferred from odp leg 207 foraminiferal d 18 o and mg ca when we specify approximate co2 concentrations estimated from the biomarker isotopes in the same samples possible errors in the temperature and co2 estimates and possible deficiencies in the model are discussed the potential for and effects of substantially higher atmospheric methane during cretaceous anoxic events perhaps derived from high fluxes from the oxygen minimum zone are considered in light of recent work that shows a quadratic relation between increased methane flux and atmospheric ch4 concentrations with 50 ppm ch4 genesis sea surface temperatures approximate the minimum upper ocean temperatures inferred from proxy data when co2 concentrations specified to the model are near those inferred using the phytane d 13 c proxy however atmospheric co2 concentrations of 3500 ppm or more are still required in the model in order to reproduce inferred maximum temperatures

volcanism and vertical tectonics in the pacific basin related to global cretaceous transgressions abstract the dominance of volcanic processes and the importance of vertical tectonics in the geological evolution of the pacific basin has been recognised since the time of charles darwin data gathered on several legs of the deep sea drilling project dsdp and numerous marine expeditions in the past decade have confirmed menard s postulate that the pacific basin was the scene of volcanism on an enormous scale in mesozoic time widespread mid plate volcanism between 110 and 70 m y b p characterised the area bounded by the line islands the mid pacific mountains and the nauru basin marshall islands heating of the pacific lithospheric plate during this period of volcanism resulted in regional uplift and the bathymetric evolution of the area diverged significantly from a normal parsons sclater subsidence curve the farallon plate now almost entirely subducted was also the scene of mid plate volcanism that produced such features as the nicoya plateau now found as an allochthonous ophiolitic terrain landward of the middle america trench large benthonic reef associated foraminifera comprising a pseudorbitoid fauna hitherto considered to be largely restricted to central america have now been additionally recorded from dsdp sites 165 315 and 316 in the line islands site 462 in the nauru basin and in new guinea the distribution of this fauna of campanian maastrichtian age is interpreted as indicating stepping stone connections aseismic ridges plateaus and seamounts between the caribbean farallon and pacific plates 70 80 m y b p similarities between the geology of the nauru basin and the caribbean ocean crust reinforce the interpretation of the latter as a former part of the farallon plate estimates of the sea level and continental freeboard change caused by the thermally induced uplift of the pacific and farallon plates as well as substantial areas in the atlantic and indian ocean basins indicate that such shallowing of the sea floor could have been the major factor in causing global cretaceous transgressions

the middle cenomanian event in the equatorial atlantic the calcareous nannofossil and benthic foraminiferal response abstract in addition to oceanic anoxic event 2 oae2 other perturbations of the carbon cycle occurred during the cenomanian and turonian of which the middle cenomanian event mce is the most prominent one in palaeoecological publications however this event is strongly underrepresented in contrast to the well studied oae2 in order to fill this gap we have studied early cenomanian to late turonian calcareous nannofossil and benthic foraminiferal assemblages of ocean drilling program site 1260 at demerara rise western equatorial north atlantic in order to decipher biotic changes throughout this interval and especially across the mce our data show distinctive changes in the relative abundance of certain calcareous nannofossil taxa and a drastic decrease in benthic foraminiferal diversities and abundances associated with the mce in the lower part of the studied section and prior to the mce a mixed water column with high nutrient availability in the upper photic zone is suggested based on very high relative abundances of the mesotrophic eutrophic nannofossil species biscutum constans around the mce interval certain nannofossil taxa e g rhagodiscus asper show a distinctive decrease in relative abundance while others become more dominant taxa which increase in relative abundance after the mce e g eprolithus floralis are interpreted as either having favoured less eutrophic surface waters or having inhabited deeper parts of the photic zone in a well stratified water column this interpretation is supported by published oxygen isotope and tex86 data which suggest increased water column stratification starting with the mce and lasting to the end of the cenomanian stage as a result of the implementation of a saline intermediate to deep water mass during this interval our study shows that the mce was a significant biotic event in the cenomanian turonian equatorial atlantic characterised by a lasting change of surface and bottom water ecosystems

testing the cretaceous greenhouse hypothesis using glassy foraminiferal calcite from the core of the turonian tropics on demerara rise glassy turonian foraminifera preserved in clay rich sediments from the western tropical atlantic yield the warmest equivalent 18o sea surface temperatures ssts yet reported for the entire cretaceous cenozoic we estimate turonian ssts that were at least as warm as conservative mean 30 c to significantly warmer warm mean 33 c than those in the region today however if independent evidence for high middle cretaceous pco2 is reliable and resulted in greater isotopic fractionation between seawater and calcite because of lower sea surface ph our conservative and warm sst estimates would be even higher 32 and 36 c respectively our new tropical ssts help reconcile geologic data with the predictions of general circulation models that incorporate high cretaceous pco2 and lend support to the hypothesis of a cretaceous greenhouse our data also strengthen the case for a turonian age for the cretaceous thermal maximum and highlight a 20 40 m y mismatch between peak cretaceous cenozoic global warmth and peak inferred tectonic co2 production we infer that this mismatch is either an artifact of a hidden turonian pulse in global ocean crust cycling or real evidence of the influence of some other factor on atmospheric co2 and or ssts a hidden pulse in crust cycling would explain the timing of peak cretaceous cenozoic sea level also turonian but other factors are needed to explain high frequency 10 100 k y instability in middle cretaceous ssts reported elsewhere

high resolution 104 years deep sea foraminiferal stable isotope records of the eocene oligocene climate transition we have constructed high resolution 104 105 years benthic foraminiferal 13c and 18o records for the upper eocene through lower oligocene of two pelagic sequences deep sea drilling project dsdp site 522 in the angola basin south atlantic ocean and ocean drilling program odp site 744 in the southern indian ocean these records provide improved constraints on both the timing and magnitude of marine oxygen and carbon isotope events from 30 to 35 ma the oxygen isotope records indicate that the ubiquitous 18o increase oi 1 which marks the rapid expansion of continental ice sheets and a minimum of 3 to 4 c of cooling of bottom waters in the earliest oligocene 33 6 ma occurred in 350 kyr more than half the transition occurred over the final 40 50 kyr this period of lower temperatures and widespread continental glaciation persisted for roughly 400 kyr i e the duration of magnetochron c13n these records also indicate that this interval was characterized by at least two 100 kyr waxing and waning cycles oi 1a and oi 1b and possibly several higher frequency events the benthic foraminiferal 13c records show a positive 0 8 excursion that is nearly isochronous with the oi 1 oxygen isotope increase similar magnitude 13c increases at other sites indicate this was a global phenomenon suggestive of an unusually large perturbation to the carbon cycle this excursion was followed by smaller amplitude 13c oscillations with periods of roughly 400 kyr we suspect that the ubiquitous oi 1 13c excursion resulted from a brief but substantial increase in export production and carbon burial

late cretaceous early tertiary palaeoclimates of northern high latitudes a quantitative view analyses of plant community structure vegetational and leaf physiognomy and growth rings and vascular systems in wood provide qualitative and quantitative data that can be combined to define non marine palaeoclimatic parameters with better resolution than is available from other principally sedimentological methods application of these techniques to cenomanian through paleocene floras from high palaeolatitudes 75 85 n indicates a polar light regime similar to that of the present plant data suggests cenomanian sea level mean annual air temperatures mats of 10 c and mats of 13 c 5 c and 6 7 c in the coniacian maastrichtian and paleocene respectively evapotranspirational stresses at sea level were low and precipitation was in most part uniform throughout the growing season in the cenomanian with possible seasonal drying occurring by the maastrichtian maastrichtian winter freezing was likely but periglacial conditions did not exist at sea level permanent ice was likely above 1700 m at 75 n in the cenomanian and above 1000 m at 85 n in the maastrichtian these near polar data provide critical constraints on global models of late cretaceous to early tertiary climates

holocene fluvial development of the upper tigris valley southeastern turkey as documented by archaeological data abstract this study was carried out to elucidate the holocene development of the valley of the tigris river between bismil and batman which will be inundated by the reservoir waters of ilisu dam to be built in upper tigris valley and to collect the geoarchaeological data of the mounds located there in the tigris valley 4 5 and 2 3 m terraces were formed in the holocene according to geoarchaeological data obtained from the mound located on the 4 5 m terrace it was determined that the tigris river has been flowing in the same bed from the neolithic age the floodplains of the 4 5 m terrace occurred as a result of floods which took place in three different cycles the first caused the formation of late pleistocene early holocene channel and floodplain material composed of coarse gravel and sandy silt on this floodplain with a relative altitude of 2 m above river level late neolithic settlements 6000 5500 bc were formed the second cycle is represented by the formation of early chalcolithic 5500 4000 bc floodplain material there were late chalcolithic and early bronze age 4000 2650 bc settlements formed on this floodplain with a relative altitude of 3 3 5 m above river level the third and the final cycle is represented by 1 2 m thick yellowish orange flood deposits which started to form from the end of early bronze age i these cover the early bronze age i cemetery 2800 2650 bc and settlements belonging to earlier periods as in the case of asagi salat mound

middle late cretaceous climate of the southern high latitudes stable isotopic evidence for minimal equator to pole thermal gradients a detailed 18 o and 13 c stratigraphy has been generated from analysis of well preserved albian early maastrichtian foraminifera from deep sea drilling project dsdp sites 511 and 327 falkland plateau 58 s 62 s paleolatitude in the southern south atlantic and cenomanian and coniacian santonian foraminifera from dsdp site 258 naturaliste plateau 58 s paleolatitude in the southern indian ocean these results when combined with previously published maastrichtian stable isotope data from ocean drilling program odp site 690 weddell sea 65 s paleolatitude provide new insight into the climatic and oceanographic history of the southern high latitudes during middle late cretaceous time the planktonic foraminifer 18 o curves reveal a gradual warming of surface waters from the albian through the cenomanian followed by extremely warm surface waters from the turonian through the early campanian long term cooling of surface waters began in the late early campanian and continued through the end of the maastrichtian the benthic foraminifer 18 o record generally parallels changes in the oxygen isotopic curves defined by shallow dwelling planktonic foraminifera the vertical oxygen and carbon isotopic gradients were relatively low during the albian cenomanian high from the turonian early campanian and then low during the late campanian and maastrichtian foraminiferal oxygen isotopic data from published sources and this study are averaged for each site corrected for latitudinal changes in salinity based on modern day surface water values and plotted versus paleolatitude for the late albian coniacian santonian and late maastrichtian differences between lowand high latitude surface water paleotemperatures are estimated at 14 c during the late albian and late maastrichtian but the coniacian santonian reconstruction reveals only a 0 4 c latitudinal temperature gradient uncertainty regarding cretaceous salinity gradients and possible diagenetic alteration of 18 o values introduce error into our estimates of paleolatitudinal thermal gradients however apparent low equator to pole temperature differences could indicate much higher poleward heat transport than at present

high resolution stable isotope records from the upper cretaceous rocks of italy and spain glacial episodes in a greenhouse planet high resolution 13c and 18o records from upper albian to lower santonian pelagic carbonates of the contessa quarry section in italy exhibit large positive oxygen isotopic excursions of 1 in the lower cenomanian and upper turonian coniacian strata within the uncertainties of biostratigraphic correlation these positive excursions appear to correspond to times of large sea level regressions in global sequence stratigraphic sea level curves several lines of evidence suggest that the major 18o excursions in contessa reflect episodes of global cooling and not differential diagenesis numerical models of oxygen isotope exchange during diagenesis show that a high contrast in the degree of alteration would be required to produce these signals as artifacts of diagenesis and lithological data provide no evidence for such large contrasts in the degree of alteration furthermore although precise correlation with a section in the south of spain is hampered by stratigraphic complexities the general sequence of major positive 18o excursions is reproduced it is unlikely that differential diagenesis would produce similar artifacts in multiple sites one explanation for the link between episodes of global cooling and sea level falls is that global cooling events led to polar ice sheet accumulation lowering sea level although ice free conditions have been inferred from evidence for a much warmer climate in late cretaceous time our results suggest that the relationship between continental high latitude ice sheets and overall climatic warmth warrants further examination

lead isotopic record of barremian aptian marine sediments implications for large igneous provinces and the aptian climatic crisis we present initial isotopic ratios of lead for early cretaceous barremian aptian sections from shatsky rise pacific and gorgo a cerbara italy our pb isotopic data track an interval representing oceanic anoxic event oae 1a which is characterized by quasi global deposition of organic carbon rich black shale pb isotopic compositions of sediments from shatsky rise decrease at the end of barremian time from radiogenic continental values to unradiogenic values and subsequently remained less radiogenic until the end of early aptian time we explain the isotopic shift by a significant increase in supply rate of unradiogenic pb most likely due to massive volcanism in contrast the pb isotopic compositions from the italian section which was situated at the western end of tethys are mostly identical to those of upper continental crust showing no significant change in supply rate of unradiogenic pb the discrepancy between two sites is attributed to quiescent deep submarine eruptions of pacific large igneous provinces lips such as the ontong java plateau ojp which severely limited dispersion of pb carrying particles out of the pacific ocean published os isotopic data from the italian section indicate two episodes of massive eruptions of ojp or contemporaneous manihiki and hikurangi plateaus starting from earliest aptian time slightly later than that indicated by the sedimentary pb isotopic record from shatsky rise differences in isotopic variations between pb and os likely reflect differences in their chemical behaviors in the oceans i e pb isotopic compositions would have varied in response to local or regional changes in sediment provenances whereas large scale changes in os inputs are required to explain variations in seawater os isotopic compositions our pb isotopic data together with the published os isotopic record provide new evidence for the eruptive history of ojp together with contemporaneous pacific plateaus and its environmental consequences starting from end barremian time and extending through early aptian time

litho bio and chemostratigraphy across the cenomanian turonian boundary oae 2 in the vocontian basin of southeastern france the oceanic anoxic event 2 oae 2 was one of at least two large oceanic anoxic events during the cretaceous period and it is characterized in the stratigraphic record by double positive peaks in the 13c curves of carbonate and organic carbon since the positive 13c shift is believed to have resulted from massive burial of isotopically depleted organic carbon generated globally in anoxic oceanic environments the positive 13c shift tend to coincide with widespread deposition of organic rich sediments in the case of oae 2 however the organic rich horizons do not accord exactly with the two intervals with positive 13c shifts at many sites such as pueblo tarfaya eastbourne and gubbio e g tsikos h jenkyns h c walsworth bell b petrizzo m r forster a kolonic s erba e premoli silva i baas m wagner t sinninghe dameste j s 2004 carbon isotope stratigraphy recorded by the cenomanian turonian oceanic anoxic event correlation and implications based on three key localities journal of the geological society london 161 711 719 the thomel level of the cenomanian turonian c t boundary in the vocontian basin southeastern france accumulated during the oae 2 and it is marked by frequent intercalations of black shale and organic rich marl detailed litho bio and chemostratigraphy analyses across the c t boundary in the vocontian basin indicate that the 13ccarbonate profile fluctuation across the thomel level corresponds well with changes in lithofacies total organic carbon toc and calcium carbonate caco3 abundance positive 13c excursions within the oae 2 correlate with basal and middle parts of the thomel level that are characterized by high toc low caco3 and predominantly contain organic rich sediments such as black shale and dark gray marl on the other hand negative 13c intervals within the oae 2 correspond with lower and upper parts of the thomel level that consist of marly limestone and limy marl with low toc and high caco3 values since the fluctuation of redox conditions during thomel level deposition in the vocontian basin coincides well with the global carbon burial rate indicated by its 13c profile the thomel level could be an ideal candidate for the reference section of the oae 2

did the red sea mediterranean connection over the dead sea fault zone end in the late pliocene abstract the delta plain of the asi orontes river in hatay turkey is located between two regional major tectonic zones the dead sea fault zone from the red sea to antakya and the east anatolian fault zone from karliova to antakya sediment samples from five cores performed on the asi delta plain to 15 m depth were studied and three fossil groups were identified in 5 samples they mainly consist of 51 foraminiferal species from 42 genera ostracod genera representing marine brackish and fresh water environments and gastropoda and bivalvia taxa the abundance of some benthic foraminifera in the recent sediment samples including euuvigerina reineri bedford siphonina tubulosa cushman and siphonodosaria abyssorum brady which are common in the pacific ocean indian ocean arabian sea and red sea is remarkable in addition euuvigerina reineri bedford individuals about 70 ka have been collected from magaracik village to the north of the drilling area the existence of these species in the quaternary sediments indicates that the water connection via the gulf of aqaba on the dead sea fault zone was still open in the pleistocene

the response of two tethyan carbonate platforms to the early toarcian jurassic oceanic anoxic event environmental change and differential subsidence chemostratigraphic analyses 87 sr 86 sr d 13 ccarb of limestones from two jurassic platform carbonate sequences in italy trento and campania lucania platforms illustrate previously established trends found in pelagic sediments and skeletal carbonates from biostratigraphically well calibrated sections elsewhere in europe chemostratigraphic correlations between the platform carbonate successions and appropriate intervals from well dated reference sections allow the application of high resolution stratigraphy to these shallow water peritidal carbonates and furthermore elucidate the facies response to the early toarcian oceanic anoxic event oae lower jurassic toarcian levels of the western trento platform southern alps northern italy contain spiculitic cherts that appear where rising carbon isotope values characterize the onset of the oae a palaeoceanographic phenomenon interpreted as driven by increased nutrient levels in near surface waters there is a facies change to more clay rich facies at the level of the abrupt negative carbon isotope excursion also characteristic of the oae higher in the section the campania lucania platform southern apennines southern italy records a change to more clay rich facies where carbon isotope values begin to rise at the beginning of the oae but the negative excursion higher in the section occurs within oolitic facies although in both examples the early toarcian oae can be recognized by a change to more clay rich lithologies this facies development is diachronous and in neither case did the platform drown although the trento platform in the south west sector studied here was adversely affected by the oae it did not drown definitively until late aalenian time the campania lucania platform persisted throughout the jurassic and cretaceous differential subsidence rates which can be calculated using comparative chemostratigraphy are identified as a crucial factor in the divergent behaviour of these two carbonate platforms relatively fast in the case of the trento platform relatively slow in the case of the campania lucania platform it is proposed that where water depths remained as shallow as a few metres during the oae campania lucania platform dissolved oxygen levels remained high nutrient levels relatively low and conditions for carbonate secretion and precipitation remained relatively favourable whereas more poorly ventilated and or more nutrient rich waters trento platform adversely

warm tropical ocean surface and global anoxia during the mid cretaceous period the middle of the cretaceous period about 120 to 80 myr ago was a time of unusually warm polar temperatures1 repeated reef drowning in the tropics2 and a series of oceanic anoxic events oaes that promoted both the widespread deposition of organic carbon rich marine sediments and high biological turnover3 4 5 6 7 8 the cause of the warm temperatures is unproven but widely attributed to high levels of atmospheric greenhouse gases such as carbon dioxide7 8 9 10 11 12 in contrast there is no consensus on the climatic causes and effects of the oaes with both high biological productivity and ocean stagnation being invoked as the cause of ocean anoxia3 4 5 6 7 8 here we show using stable isotope records from multiple species of well preserved foraminifera that the thermal structure of surface waters in the western tropical atlantic ocean underwent pronounced variability about 100 myr ago with maximum sea surface temperatures 3 5 c warmer than today this variability culminated in a collapse of upper ocean stratification during oae 1d the breistroffer event a globally significant period of organic carbon burial that we show to have fundamental stratigraphically valuable geochemical similarities to the main oaes of the mesozoic era our records are consistent with greenhouse forcing being responsible for the warm temperatures but are inconsistent both with explanations for oaes based on ocean stagnation and with the traditional view reviewed in ref 12 that past warm periods were more stable than today s climate

alluvial geoarchaeology of a small drainage basin in western anatolia late holocene landscape development and the question of the mouth of the paleo bakircay abstract late holocene landscape evolution in the geyikli basin a sub catchment of the bakircay basin on the west anatolian coast and its implications for the plaeogeography of the environs of ancient pergamon modern bergama were studied by a combination of archaeological and geographical investigations the study aims to investigate whether the dorpfeld scenario of the paleogeographical situation in the lower bakircay valley is true or not the scenario postulates that during the late holocene an alluvial fan fed from the geyikli valley progressively closed a topographical constriction between the aegean sea and a supposed paleo gulf that occupied the lower bakircay valley initially this caused the development of an inland lake and finally the shift of the mouth of the paleo bakircay from a northern position to its modern southern position the lithostratigraphy of four sediment outcrops in the lower geyikli basin and in the topographical constriction between the aegean coastal plain and the bakircay valley shows that during the past ca 1950 years the lower geyikli valley was inhabited by a braided river with a highly dynamic depositional system sedimentation totalled about 4 6 m in the past 1950 years indicating a drowning of the landscape in terrestrial sediments in recent times gravel mining has led to a deformation of the valley floor and the geyikli s fluvial terrace has become inactive the lack of any sediment related to a paleo gulf or a paleo lake inside the bakircay basin as well as the lack of any sediments of a northern paleo bakircay documents that the dorpfeld scenario does not apply for the past 1950 years archaeological findings show that the geyikli basin was intensively settled in historic times but there is no evidence that the geyikli basin was anthropogenically deformed in a way that could have contributed to the dorpfeld scenario

high temperatures in the late cretaceous arctic ocean to understand the climate dynamics of the warm equable greenhouse world of the late cretaceous period it is important to determine polar palaeotemperatures the early palaeoceanographic history of the arctic ocean has however remained largely unknown because the sea floor and underlying deposits are usually inaccessible beneath a cover of floating ice a shallow piston core taken from a drifting ice island in 1970 fortuitously retrieved unconsolidated upper cretaceous organic rich sediment from alpha ridge a submarine elevated feature of probable oceanic origin a lack of carbonate in the sediments from this core has prevented the use of traditional oxygen isotope palaeothermometry here we determine arctic palaeotemperatures from these upper cretaceous deposits using tex86 a new palaeothermometer that is based on the composition of membrane lipids derived from a ubiquitous component of marine plankton crenarchaeota from these analyses we infer an average sea surface temperature of approximately 15 degrees c for the arctic ocean about 70 million years ago this calibration point implies an equator to pole gradient in sea surface temperatures of approximately 15 degrees c during this interval and by extrapolation we suggest that polar waters were generally warmer than 20 degrees c during the middle cretaceous approximately 90 million years ago

holocene valley aggradation driven by river mouth progradation examples from australia since the end of the post glacial sea level rise 6800 years ago progradation of river mouths into estuaries has been a global phenomenon the responses of upstream alluvial river reaches to this progradation have received little attention here the links between river mouth progradation and holocene valley aggradation are examined for the macdonald and tuross rivers in south eastern australia optical and radiocarbon dating of floodplain sediments indicates that since the mid holocene sea level highstand 6800 years ago vertical floodplain aggradation along the two valleys has generally been consistent with the rate at which each river prograded into its estuary this link between river mouth progradation and alluvial aggradation drove floodplain aggradation for many tens of kilometres upstream of the estuarine limits both rivers have abandoned their main holocene floodplains over the last 2000 years and their channels have contracted a regional shift to smaller floods is inferred to be responsible for this change though a greater relative sea level fall experienced by the macdonald river since the mid holocene sea level highstand appears to have been an additional influence upon floodplain evolution in this valley copyright 2006 john wiley sons ltd

field laboratory and modeling investigation of the skin effect at wells with slotted casing boise hydrogeophysical research site understanding and quantification of wellbore skin improves our ability to accurately measure or estimate hydrologic parameters with tests at wells such as pumping tests flowmeter tests and slug tests this paper presents observations and results from a series of field laboratory and modeling tests which together explain the source of wellbore skin at wells at a research wellfield and which support estimation of skin thickness ds and skin hydraulic conductivity ks positive wellbore skin effects were recognized at wells in the shallow unconfined coarse grained fluvial aquifer at the boise hydrogeophysical research site bhrs well development efforts at the bhrs removed residual drilling fines but only marginally reduced the skin effect likely causes for the remaining wellbore skin effect were examined partial clogging of screen slots with sand is consistent with field observations and can account for the magnitude of wellbore skin effect observed we then use the wtaq code barlow and moench 1999 with a redefinition of the term for delayed observation well response to include skin effects at observation wells in addition to pumping wells in order to analyze aquifer tests at the bhrs for average ks values at individual wells systematic differences in ks values are recognized in results at pumping ks q and observation ks obs wells larger values are seen at observation wells average ks obsz0 0023 cm s than pumping wells two possible causes are recognized for the occurrence of higher ks values at observation wells than pumping wells 1 flow diversion between aquifer layers on approach to a pumping well with positive skin and 2 larger portion offlow passing through lower k zones in the heterogeneous aquifer near the pumping well than the observation wells due to strongly radially convergent flow near the pumping well for the wellaquifer system at the bhrs modeling analyses of drawdown vs time at observation wells provide better ks estimates than those from pumping wells q 2005 elsevier b v all rights reserved

testing for ice sheets during the mid cretaceous greenhouse using glassy foraminiferal calcite from the mid cenomanian tropics on demerara rise the mid cretaceous is widely considered the archetypal ice free greenhouse interval in earth history with a thermal maximum around cenomanian turonian boundary time ca 90 ma however contemporaneous glaciations have been hypothesized based on sequence stratigraphic evidence for rapid sea level oscillation and oxygen isotope excursions in records generated from carbonates of questionable preservation and or of low resolution we present new oxygen isotope records for the mid cenomanian demerara rise that are of much higher resolution than previously available taken from both planktic and benthic foraminifers and utilizing only extremely well preserved glassy foraminifers our records show no evidence of glaciation calling into question the hypothesized ice sheets and rendering the origin of inferred rapid sea level oscillations enigmatic simple mass balance calculations demonstrate that this cretaceous sea level paradox is unlikely to be explained by hidden ice sheets existing below the limit of 18 o detection

visions of ice sheets in a greenhouse world abstract backstripped eustatic estimates from new jersey and the russian platform show large 25 m and rapid 18 o record highlights the enigma this was the warmest interval of the past 200 my yet it was bracketed by two inferred eustatic falls of 25 m that were associated with two large 0 75 deep sea 18 o increases 92 93 ma mid turonian and 96 ma mid cenomanian we reconcile records of warm high latitudes with glacioeustasy by proposing that late cretaceous early eocene ice sheets generally reached maximum volumes of 8 12 10 6 km 3 20 30 m glacioeustatic equivalent but did not reach the antarctic coast hence coastal antarctica hence deep water remained relatively warm even though there were significant changes in sea level as the result of glaciation unlike the oligocene and younger icehouse world these ice sheets only existed during short intervals of peak milankovitch insolation leaving antarctica ice free during much of the greenhouse late cretaceous to middle eocene these results highlight the need to re evaluate the paradigm that polar ice sheets did not exist during times of warm high latitude climates

possible atmospheric co2 extremes of the middle cretaceous late albian turonian 1 atmospheric carbon dioxide co2 estimates for the middle cretaceous mk have a range of 4000 ppm which presents considerable uncertainty in understanding the possible causes of warmth for this interval this paper examines the problem of mk greenhouse forcing from an inverse perspective we estimate upper ocean water temperatures from oxygen isotope measurements of well preserved late albian turonian planktonic foraminifera and compare these against temperatures predicted by general circulation model gcm experiments with co2 concentrations of 500 7500 ppm at least 4500 ppm co2 is required to match maximum temperatures inferred from well preserved planktonic foraminifera approximately 900 ppm co2 produces a good match between the model and the minimum temperature estimates for the mk an ocean model forced by these two extremes in surface conditions brackets nearly all available bottom water temperature estimates for this interval the climate model results support nearly the entire range of mk co2 estimates from proxy data the ocean model suggests possible mk oceanographic changes from deep water formation in the high latitude region of one hemisphere to the other hemisphere in response to changes in atmospheric temperatures and hydrologic cycle strength we suggest that rather than contradicting one another the various proxy co2 techniques especially those with high temporal resolution may capture true variability in co2 concentrations and that mk co2 could have varied by several thousand ppm through this interval

global correlation of cenomanian upper cretaceous sequences evidence for milankovitch control on sea level we have investigated the sequence stratigraphy of two widely separated marine cenomanian successions in southeast india and northwest europe and used high resolution ammonite biostratigraphy to demonstrate that sea level changes are globally synchronous and therefore must be eustatically controlled sequence scale sea level changes in the cenomanian were driven by the long eccentricity cycle 400 k y in the milankovitch band we hypothesize that during pre quaternary time the third order sequences of vail and haq are essentially a sediment response to sea level changes driven by the 400 k y cycle construction of a relative sea level curve for the marginal marine succession in india demonstrates that the short term sea level changes are rapid 10 100 m m y and have a magnitude of 2 20 m glacioeustasy is a possible but unproven driving mechanism

carbon and oxygen isotope stratigraphy of the english chalk and italian scaglia and its palaeoclimatic significance a detailed carbon and oxygen isotope stratigraphy has been generated from upper cretaceous coastal chalk sections in southern england east kent culver cliff isle of wight eastbourne and seaford head sussex norfolk coast and the british geological survey bgs trunch borehole norfolk data are also presented from a section through the scaglia facies exposed near gubbio italian apennines wherever possible the sampling interval has been one metre or less both the chalk and scaglia carbon isotopic curves show minor positive excursions in the mid cenomanian mid and high turonian basal coniacian and highest santonian lowest campanian there is a negative excursion high in the campanian in chalk sections that span that interval the well documented cenomanian turonian boundary spike is also well displayed as is a broad positive excursion centred on the upper coniacian a number of these positive excursions correlate with records of organic carbon rich deposition in the atlantic ocean and elsewhere the remarkable similarity in the carbon isotope curves from england and italy enables cross referencing of macrofossil and microfossil zones and pinpoints considerable discrepancy in the relative positions of the turonian coniacian and santonian stages the oxygen isotope values of the various chalk sections although showing different absolute values that are presumably diagenesis dependent show nonetheless a consistent trend the east kent section which is very poorly lithified indicates a warming up to the cenomanian turonian boundary interval then cooling thereafter regional organic carbon burial documented for this period is credited with causing drawdown of co 2 and initiating climatic deterioration inverse greenhouse effect data from other parts of the world are consistent with the hypothesis that the cenomanian turonian temperature optimum was a global phenomenon and that this interval represents a major turning point in the climatic history of the earth

climate induced fluctuations in sea level during non glacial times during periods of time when the earth supports ice caps sea level fluctuates periodically at intervals of 104 105 yr with amplitudes of tens to more than 100 metres these fluctuations result from expansions and contractions of continental ice sheets that occur in phase with the milankovitch periodicities of the earth s orbit1 2 smaller amplitude sea level fluctuations associated with milankovitch periodicities are also evident during warm periods such as the late triassic3 5 which lack strong evidence for continental glaciation6 we argue here that in times of limited ice volume periodic climate induced changes in lake and groundwater storage have the potential to produce small fluctuations in sea level this mechanism could contribute a small component of the sea level change observed in the quaternary period and may dominate the milankovitch eustatic sea level signal during earlier periods with limited ice volume6 we present evidence of contemporaneous milankovitch periodicities in late triassic lake sediments7 and sea level fluctuation3 5 which support the causal link between lake water storage and eustasy

recognizing and modeling variable drawdown due to evapotranspiration in a semiarid riparian zone considering local differences in vegetation and distance from a river source 1 riparian zones in semiarid regions often exhibit high rates of evapotranspiration et in spite of low soil moisture content due to the presence of phreatophytic vegetation that is able to withdraw water from shallow aquifers this work seeks to better define the relationship between et the saturated zone and the river boundary by comparing observed water table drawdown records to analytically modeled drawdown in fully penetrating wells of an unconfined aquifer in response to daily et flux et at the boise hydrogeophysical research site bhrs a riparian zone in a temperate semiarid environment is calculated using a radiation based method to provide et values at four different wells with different vegetation densities analytically modeled drawdown response to et forcing shows that drawdown magnitude increases with increasing distance from the river edge even as the surficial et forcing remains constant this behavior is also observed in well hydrographs and shows the buffering effect that flow from the river has on drawdown in fully penetrating riparian wells in highly permeable unconfined aquifers relative contributions of river water to aquifer storage are calculated for et induced diurnal fluctuations of the water table at increasing distances from the river boundary failure to account for these spatial differences in drawdown related to the river source may explain some errors associated with estimating et from well hydrographs alone

deep sea paleotemperature record of extreme warmth during the cretaceous oxygen isotope analyses of well preserved foraminifera from blake nose 30 n paleolatitude north atlantic and globally distributed deep sea sites provide a long term paleotemperature record for the late albian maastrichtian interval that is difficult to reconcile with the existence of significant cretaceous ice sheets given reasonable assumptions about the isotopic composition of cretaceous seawater our results suggest that middle bathyal water temperatures at blake nose increased from 12 c in the late albian through middle cenomanian to a maximum of 20 c during the latest cenomanian and earliest turonian bottom waters were again 12 c during the middle campanian and cooled to a minimum of 9 c during the maastrichtian correlative middle bathyal foraminifera from other ocean basins yield paleotemperature estimates that are very similar to those from blake nose comparison of global bottom water temperatures and latitudinal thermal gradients suggests that global climate changed from a warm greenhouse state during the late albian through late cenomanian to a hot greenhouse phase during the latest cenomanian through early campanian then to cool greenhouse conditions during the mid campanian through maastrichtian

holocene stratigraphy and geomorphological evolution of the aegean coastal plains of anatolia abstract three main stages can be distinguished in the sedimentary development and geomorphological formation of the present delta plains on the aegean coast of turkey the early holocene is characterized by post glacial transgression and dependent sedimentation the middle holocene was the period when sea level reached the present level and apart from small fluctuations stopped rising alluviation and deltaic progradation were prevalent during this transition period from marine to terrestrial environments as for the late holocene deltaic progradation slowed down and delta plains were covered by floodplain sediments these characteristics can be observed in the same sequence throughout the aegean coast of turkey

early oligocene ice sheet expansion on antarctica stable isotope and sedimentological evidence from kerguelen plateau southern indian ocean sedimentological and stable isotope data from a pelagic sequence recovered from the southern indian ocean provide the most convincing evidence to date for short term expansion of a large ice sheet on antarctica during the earliest oligocene 36 ma terrigenous debris identified as ice rafted in origin on the basis of textural compositional and size criteria is present at the same stratigraphic level as the ubiquitous early oligocene oxygen isotope shift the highest benthic foraminiferal 18o values 3 0 of the paleogene occur in samples from within the ice rafted debris interval these values are similar to those recorded by holocene benthic foraminifera implying that the ice sheet may have attained a volume similar to that of the present day ice sheet on antarctica the stratigraphic distribution of ice rafted debris and high oxygen isotope values indicate that these conditions persisted for roughly 100 ka

a geoarchaeological case study in the chora of pergamon western turkey to reconstruct the late holocene landscape development and settlement history this paper investigates the late holocene landscape development and settlement history of the central bakircay valley the ancient kaikos valley in western turkey which exemplifies a buried archaeological site approximately 12 km sw of pergamon a minimally intrusive geoarchaeological approach was applied by coupling an archaeological survey geophysical exploration geomorphological mapping and sedimentological analysis of drilling cores and pre existing outcrops the geomorphological and lithostratigraphical results imply that in the early and middle holocene the site was situated on a depositional piedmont plain that was protected from the annual bakircay floods over the past two millennia the bakircay flood plain was gradually aggraded and the site became prone to flooding despite the limitations of non intrusive archaeological investigations three scenarios were developed on the function and age of the buried site hence the site was either a sanctuary from the 2nd century ad a luxurious estate from the 4th 8th century ad or a lime kiln from late antique byzantine times

hierarchical geostatistics and multifacies systems boise hydrogeophysical research site boise idaho 1 the geostatistical structure of a heterogeneous coarse fluvial aquifer is investigated with porosity data derived from neutron logs at a research well field boise hydrogeophysical research site or bhrs that was designed in part to support three dimensional geostatistical analysis of hydrologic and geophysical parameters recognizing that the coarse fluvial deposits include subdivisions units between bounding surfaces we adopt a hierarchical approach and examine the porosity geostatistics of the aquifer at three scales at the bhrs the saturated fluvial deposits as a whole maximum interwell spacing 80 m thickness 16 18 m are at hierarchical level 1 five subhorizontal units within these deposits four cobble dominated units and a channel sand can be traced across the central area of the bhrs and are at hierarchical level 2 and subunits patches or lenses in one of the level 2 units unit 4 are at hierarchical level 3 we use variography and porosity statistics to recognize nonstationarity at hierarchical level 1 and in one of the level 2 units unit 4 where the means and variances of porosity differences as a function of lag are not constant between distinct units and subunits respectively the geostatistical structure at level 1 is modeled with different horizontal and vertical structures that have different sills vertical sill greater than horizontal sill the difference in sills can be explained quantitatively by the summing of weighted sills from all individual units and combined units i e a given pair of different units where the weights are the proportions of data pairs contributing to the sills at each lag from the individual and combined units extension of this analysis leads to a weighted multistructure form of the variogram function whereby a global experimental variogram in a hierarchical system can be decomposed quantitatively into weighted component individual and combined unit or facies structures for any number of units or hierarchical levels such decomposition of the global horizontal variogram from the bhrs indicates that short range periodicity in that structure is due to both 1 combined unit structures associated with patches or lenses at hierarchical level 3 in unit 4 and 2 variations in thickness of unit 2 for hierarchical multifacies systems structure models fit to global horizontal and vertical experimental variograms may not be useful for subsequent stochastic modeling if the system on which the structure models are based is nonstationary

low latitude sea surface temperatures for the mid cretaceous and the evolution of planktic foraminifera isotopic data from exceptionally well preserved foraminifera show that the subtropical north atlantic had sea surface temperatures ssts between 30 and 31 c during the late albian and early cenomanian these temperatures were warmer than average modern temperatures in the tropical western atlantic and support previous inferences based on diagenetically suspect material of albian tropical ssts of 30 c this finding is consistent with basic theories of oceanic thermal response in the tropics to the high atmospheric carbon dioxide levels during the middle cretaceous greenhouse however our data do not support the concept of a super tethyan region of hypersaline waters in the western north atlantic during late albian and early cenomanian time because seawater salinities substantially higher than modern ones would require significantly higher ssts than those reported here isotopic analysis of mid cretaceous planktic foraminifera shows that planomalina ticinella and biticinella grew in surface waters and provide isotopic proxies for sst whereas deeper growing species include hedbergella rotalipora and praeglobotruncana none of these taxa display isotopic indications of photosymbiosis suggesting that this ecology did not evolve in planktic foraminifera before the late cretaceous contrary to previous hypotheses none of these species increased their depth habitat during their life cycles unlike many extant planktic foraminifera the rotaliporids may have been preferentially susceptible to extinction during oceanic anoxic events because they lived within or below the thermocline for most of their life cycles

palaeogeographical and palaeoenvironmental reconstruction of the medjerda delta tunisia during the holocene abstract the progradation of the medjerda delta has been the subject of many studies since the 19th century the scale and the rapidity of this phenomenon interested researchers in various fields early on such as geomorphology geology palaeogeography history archaeology or geoarchaeology indeed the delta prograded by around 10 km over 3 millennia at the time of its foundation supposedly at the end of the 12th century bc the phoenician city of utica was located on a promontory bathed by the sea but the sediments carried by the medjerda progressively sealed the bay leaving the tip of the utica promontory now 10 km inland this area is therefore an exception to the general pattern along the tunisian coast since as over the same period everywhere else there is a regression of the coastline owing to a sea level rise of several decimeters based on multi proxy analyses of two coring transects this paper aims to reconstruct the palaeoenvironments and the palaeogeography of the medjerda delta s progradation since the mid holocene some aspects of which are described in ancient sources the results highlight in particular an episode of high intensity flooding around the 4th century ad which is consistent with episodes of high floods and an increase in sedimentation rates recorded in the watershed at the end of the roman period the gradual abandonment of the city of utica can certainly be related to the activity of the medjerda river but our results show that it is because of an increase of fluvial sediment contribution in connection with an erosive crisis in the headwaters and not because of the change of course of the river which had occurred long before

unlocking the ice house oligocene miocene oxygen isotopes eustasy and margin erosion oxygen isotope records and glaciomarine sediments indicate at least an intermittent presence of large continental ice sheets on antarctica since the earliest oligocene circa 35 ma the growth and decay of ice sheets during the oligocene to modern ice house world caused glacioeustatic sea level changes the early eocene was an ice free greenhouse world but it is not clear if ice sheets existed during the middle to late eocene doubt house world benthic foraminiferal 18o records place limits on the history of glaciation suggesting the presence of ice sheets at least intermittently since the earliest oligocene the best indicator of ice growth is a coeval increase in global benthic and western equatorial planktonic 18o records although planktonic isotope records from the western equatorial regions are limited subtropical planktonic foraminifera may also record such ice volume changes it is difficult to apply these established principles to the cenozoic 18o record because of the lack of adequate data and problems in stratigraphic correlations that obscure isotope events we improved oligocene to miocene correlations of 18o records and erected eight oxygen isotope zones oi1 oi2 mi1 mi6 benthic foraminiferal 18o increases which are associated with the bases of zones oil circa 35 8 ma oi2 circa 32 5 ma and mil circa 23 5 ma can be linked with 18o increases in subtropical planktonic foraminifera and with intervals of glacial sedimentation on or near antarctica our new correlations of middle miocene benthic and western equatorial planktonic 18o records show remarkable agreement in timing and amplitude we interpret benthic planktonic covariance to reflect substantial ice volume increases near the bases of zones mi2 circa 16 1 ma mi3 circa 13 6 ma and possibly mi5 circa 11 3 ma possible glacioeustatic lowerings are associated with the 18o increases which culminated with the bases of zone mi4 circa 12 6 ma and mi6 circa 9 6 ma although low latitude planktonic 18o records are required to test this these inferred glacioeustatic lowerings can be linked to seismic and rock disconformities for example we link 12 oligocene early late miocene inferred glacioeustatic lowerings with 12 of the sequence boundaries inferred eustatic lowerings of haq et al 1987

significance of porosity for stratigraphy and textural composition in subsurface coarse fluvial deposits boise hydrogeophysical research site recognition and quantitative characterization of subsurface stratigraphic units in coarse unconsolidated fluvial deposits are difficult because large grain size and the large scale of sedimentary structures make direct interpretation from core difficult or impossible in this paper we use porosity data from well logs and grain size distribution gsd data from core to investigate four pebble and cobble dominated units that have been identified in porosity logs in deposits at a research well field boise hydrogeophysical research site lacking direct observation at an appropriate scale questions about distribution of parameters and textural composition in these units are analyzed with statistical tests the four pebble and cobble dominated porosity stratigraphic units may be grouped into two types 1 units 1 and 3 have low porosity mean 0 17 0 18 and low porosity variance and 2 units 2 and 4 have higher porosity mean 0 23 0 24 and higher porosity variance based on gsd data core samples are subdivided into five lithotypes the five lithotypes occur in different proportions and have different vertical transition probability characteristics in the two types of units 1 units 1 and 3 have only framework gravel dominated lithotypes and have random vertical transition probability between these two lithotypes and 2 units 2 and 4 consist of both framework gravel dominated and sand or matrix dominated lithotypes and have structured vertical transition probability the two framework gravel dominated lithotypes occur in all four stratigraphic units but have distinctly lower porosity in units 1 and 3 i e tighter packing than in units 2 and 4 looser packing considering the repeated stratigraphic occurrence of and the statistical significance of differences between the two types of units both the individual unit distinctions and the two unit groupings appear to be valid it is reasonable to interpret that the observed packing differences associated with units 1 and 3 compared with units 2 and 4 are related to different sedimentary processes that produce different bedforms or grain fabrics perhaps under different bedload transport rates

jiggling the tropical thermostat in the cretaceous hothouse modern open ocean sea surface temperatures rarely exceed 28 29 8c and the same has been thought to represent a rough maximum for past tropical climates however new isotopic estimates from the uppermost cenomanian in the tropical western north atlantic suggest that mixed layer temperatures reached 33 34 8 c 62 8c during the middle cretaceous hothouse uppermost cenomanian tropical sea surface temperatures may have been as much as 4 7 8c warmer than the highest modern mean annual temperatures such extreme conditions suggest that warm tropical oceans could have driven substantially intensified atmospheric heat transport near the cenomanian turonian boundary the tropical thermostat was set higher than today challenging the hypothesis of tropical climate stability

analytical modeling of saturated zone head response to evapotranspiration and river stage fluctuations summary we investigate the response of the saturated zone unconfined aquifer to evapotranspiration et flux at ground surface we neglect fluid flow and storage in the unsaturated zone and treat et as a sinusoidal forcing function at the watertable the linearized kinematic condition is imposed at the watertable analytical solutions are developed for the case of flow in a domain of a semi infinite extent to simulate response in a domain bounded by a river and b infinite lateral extent to simulate the response in a domain with no river boundaries these solutions are fitted to observed groundwater head fluctuations recorded in observation wells at the boise hydrogeophysical research site in idaho and the larned research site in kansas estimates of the amplitude of the et flux aquifer hydraulic conductivity specific storage and specific yield are obtained and these compare well to published results from pumping tests conducted at the site the field exercise is used to explore the potential for using groundwater head fluctuations to estimate et and hydraulic parameters of unconfined aquifers

geoarchaeology and aggradation around kinet hoyuk an archaeological mound in the eastern mediterranean turkey we examined the alluvial history of the plain near kinet hoyuk an archaeological mound or tell with a sequence of six millennia of occupation on the southeast mediterranean coast of turkey through 17 excavations over a 1000 m transect near the mound excavations ranged from 2 to 6 m deep and up to 20 m across this low gradient alluvial plain shows significantly different rates and processes of near mound sedimentation with one unit having nearly 4 m of late bronze age habitation and flood deposits and another having 4 m of hellenistic channel and floodplain deposition this flat alluvial surface turns out to be a rich geoarchaeological landscape that shrouds early and late bronze age settlements hellenistic walls and two epochs of roman roads one widespread phenomenon was a hellenistic or earlier paleosol and occupation level covered by channel gravels and overbank deposits mostly from the hellenistic to the late roman period these channel and floodplain deposits filled in and flattened out the off mound settlements blanketing the pre hellenistic topography and silting in a long active port this glut of alluvium correlates in time with drier conditions and the most intensive land uses in the watershed where roman and hellenistic sites today are severely eroded

late cretaceous chronology of large rapid sea level changes glacioeustasy during the greenhouse world we provide a record of global sea level eustatic variations of the late cretaceous 99 65 ma greenhouse world ocean drilling program leg 174ax provided a record of 11 14 upper cretaceous sequences in the new jersey coastal plain that were dated by in tegrating sr isotopic stratigraphy and biostratigraphy backstripping yielded a late cre taceous eustatic estimate for these sequences taking into account sediment loading com paction paleowater depth and basin subsidence we show that late cretaceous sea level changes were large 25 m and rapid k1 m y suggesting a glacioeustatic control three large d 18 o increases are linked to sequence boundaries others lack sufficient d 18 o data consistent with a glacioeustatic cause and with the development of small 10 6 km 3 ephemeral ice sheets in antarctica our sequence boundaries correlate with sea level falls recorded by exxon production research and sections from northwest europe and russia indicating a global cause although the exxon record differs from backstripped estimates in amplitude and shape

blake nose stable isotopic evidence against the mid cenomanian glaciation hypothesis detailed multitaxon stable isotope 18 o and 13 c data from blake nose western north atlantic argue against a mid cenomanian glaciation event during the mid cretaceous greenhouse results generated are precisely correlated to sea level changes inferred from european sequence stratigraphy using the twin 13 c excursions mid cenomanian event mce ia and mce ib microfossils analyzed surface dwelling to deep dwelling planktonic foraminifera benthic foraminifera coccoliths show remarkably consistent intertaxon 18 o and 13 c offsets comparative scanning electron microscope and sr ca analyses allow some 18 o data to be eliminated because of selective diagenesis across mce ia the proposed interval of major glacioeustatic regression the planktonic 18 o values are constant for each taxon the absence of a mean seawater 18 o shift contradicts predictions for the mid cenomanian glaciation episode the benthic 18 o records show significant fluctuations during mce i implying short term variability in north atlantic intermediate water and deep water circulation patterns and or sources at that time

cenozoic deep sea temperatures and global ice volumes from mg ca in benthic foraminiferal calcite a deep sea temperature record for the past 50 million years has been produced from the magnesium calcium ratio mg ca in benthic foraminiferal calcite the record is strikingly similar in form to the corresponding benthic oxygen isotope 18o record and defines an overall cooling of about 12 c in the deep oceans with four main cooling periods used in conjunction with the benthic 18o record the magnesium temperature record indicates that the first major accumulation of antarctic ice occurred rapidly in the earliest oligocene 34 million years ago and was not accompanied by a decrease in deep sea temperatures

in search of the harbours new evidence of late roman and byzantine harbours of ephesus abstract ephesus greek name ephesos in western turkey was an important harbour city during antiquity the progradation of the kucuk menderes delta has continuously shifted the coastline westwards thus along with the delta progradation new harbour sites had to be established in a western direction historical sources refer to different harbours while much is known about the roman and older ones the exact location of the ports and the coastline in late roman and byzantine times is still an open question this article presents the results of geoarchaeological research in the area located along the southern flank of the kucuk menderes graben near ephesus sediments from cores were examined with geochemical sedimentological and microfaunal analyses these data were combined with the study of ancient maps and satellite images the chronological framework was rendered by ams 14 c ages and diagnostic ceramics the farthermost inland shoreline dates from 5000 bc since then delta progradation has continuously shifted the shoreline westwards canakgol today a little lake to the west of the city of ephesus is identified as the harbour site in late roman and byzantine times this harbour persisted at least until the 16th century ad further a landing site with a pier was discovered west of canakgol presumably dating to the late byzantine ottoman times