integrated stratigraphy and paleoceanography of the messinian latest miocene across the north atlantic ocean the messinian was a time of major climatic and paleoceanographic change during the late cenozoic it is well known around the mediterranean region because of the giant anhydrite gypsum sequence and the suggested desiccation of the mediterranean sea however this interval is less constrained outside the mediterranean region where several paleoceanographic changes could have taken place because of the desiccation hence we present an integrated stratigraphic framework for future messinian paleoceanographic studies determination of the effect of the mediterranean desiccation on deep water paleoceanography and comparison of intra mediterranean paleoceanographic changes with those in the open oceans during the messinian stage four dsdp odp holes 552a 646b 608 and 547a from the north atlantic ocean and one land borehole from morocco have been studied to integrate bio magneto and stable isotope messinian stratigraphy with high resolution sampling our results produce the best assessment of the tortonian messinian boundaries in all holes because they do not rely on any one signal in paleomagnetic subchronozone csan lr in the sale borehole and dsdp site 609 a s d coiling direction change of neogloboquadrina pachyderma acostaensis appears to indicate pmow entering the northeastern atlantic ocean at least reaching 50 n diachrony and synchrony of some important messinian planktic foraminifera from these atlantic dsdp odp holes and the sale borehole such as the lo of gq dehiscens the lo of gt lenguaensis the fo and lo of gt conomiozea the fo of gt margaritae s s the fo of gt puncticulata and the fo of gt crassaformis are discussed for understanding some of the paleoceanographic changes this integrated stratigraphie framework presented here allows much better north atlantic correlations at this critical point in messinian geologic history

deep sea carbonates reading the carbon isotope signal the carbon isotope signal in deep sea sediments reflects a mix of 1 global changes in the rates of exchange of the ocean s carbon reservoir with biosphere soil and sediments 2 global and regional changes in surface water productivity 3 internal shifts in water mass structure and circulation basin basin fractionation oxygen minimum development and 4 organism specific fractionation effects due to changes in micro habitat and or ontogenic fractionation vital effects additional complications arise from differential preservation it is impossible to entirely isolate these various factors as a rule of thumb long period signals that are parallel for planktonic and benthic data reflect external global fractionation patterns whilst short period signals are more likely tied to internal patterns water mass fractionation the various approaches to interpretation are illustrated with three case studies the glacial holocene transition the messinian carbon shift and the miocene monterey excursion

geochemical and geochronological evidence for early triassic calc alkaline magmatism in the menderes massif western turkey pan african basement rocks and a paleozoic cover series which were intruded by the protoliths of leucocratic orthogneisses have been recognized in the menderes massif located in the western part of the alpine orogenic belt of turkey this geochemical and geochronological study focuses on the evolution of the menderes massif at the end of paleozoic time geochemical data suggest that the crustally derived leucocratic orthogneisses have chemical composition typical of calc alkaline and s type granite zircon grains which are euhedral with typical igneous morphologies were dated by the 207pb 206pb evaporation method single zircon dating of three samples yielded mean 207pb 206pb ages of 246 5 241 5 and 235 6 ma these ages are interpreted as the time of protolith emplacement in triassic geological and geochronological data suggest that leucocratic granites were emplaced in a period following a metamorphic event related to the closure of the paleo tethys the leucocratic granites were metamorphosed during the alpine orogenesis and transformed into orthogneisses the similar triassic magmatic event at 233 2 ma was also occurred using single zircon evaporation method from granitic gneisses which rest upon the migmatites with tectonic contacts in naxos cycladic complex this indicates that the menderes massif and cycladic complex had a common pre early triassic magmatic evolution

eclogites within the menderes massif western turkey metagabbros in the core series of the menderes massif for some time considered as post orogenic miocene intrusives revealed a strong poly metamorphic history the metagabbro bodies exhibit a pronounced zonation within their cores igneous minerals are still preserved coronitic textures are interpreted as results of a high temperature possibly granulitic overprint the outer parts of the metagabbro bodies mostly consist of strongly to completely retrograded garnet amphibolites but occasionally contain relics of eclogites petrologic investigations confirmed a high pressure overprint and allowed preliminary p t estimates 650 c 1 3 gpa the intensity of the hp metamorphism seems to rise from south to north within the menderes basement thus pointing to a northward subduction as the cause the age of the high pressure event still awaits clarification however its very existence reanimates the question how close the relationship between menderes and the cyclades evolution might have been

towards a better understanding of riparian zone water table response to precipitation surface water infiltration hillslope contribution or pressure wave processes determining how riparian zone hydrological conditions may change in response to precipitation in various geomorphic settings is critical to determine the occurrence of hot moments of biogeochemical transformations for phosphorus nitrogen sulfate mercury and greenhouse gases in these systems the author investigate water table response to precipitation at a high temporal resolution 15 min in a riparian zone located in a deeply incised glacial till valley 20 m with approximately 2 m of alluvium over a confining layer in indiana usa during storms larger water table fluctuations approximately 100 cm occurred near the stream than near the toe slope 10 25 cm a quick rise in water table near the stream occurred for all storms with partial flow reversals occurring for three of seven storms the quick rise of the water table near the stream was associated with a decrease in hillslope water contributions to the stream during storms and the development of a water table down valley gradient for most storms water table fluctuations groundwater flow velocities and electrical conductivity data indicated that riparian zone water table response to precipitation was primarily regulated by pressure wave processes regardless of the storm high water tables persisted for at least 2 days after the cessation of precipitation although this suggests that high resolution precipitation data may be useful to quantify hot moments of biogeochemical transformation associated with high water tables in riparian zones precipitation data alone are not sufficient to correctly estimate the magnitude of riparian water table level changes during storms copyright 2011 john wiley sons ltd

simulated effect of soil depth and bedrock topography on near surface hydrologic response and slope stability this paper explores the effect of hillslope hydrological behavior on slope stability in the context of transient subsurface saturation development and landslide triggering we perform a series of virtual experiments to address how subsurface topography affects the location and spatial pattern of slip surface development and pore pressure dynamics we use a 3d darcy richards equation solver hydrus 3 d combined with a cellular automata slope stability model to simulate the spatial propagation of the destabilized area our results showed that the soil bedrock interface and in particular bedrock depressions played a key role in pore pressure dynamics acting as an impedance for the downslope drainage of perched water filling and spilling of depressions in the bedrock surface microtopography induced localized zones of increased pressure head such that the development of pore pressure fields not predictable by surface topography lead to rapid landslide propagation our work suggests that landslide models should consider the subsurface topography in order to include a connectivity component in the mathematical description of hydrological processes operating at the hillslope scale copyright 2012 john wiley sons ltd

observation and analysis of near surface pore pressure measurements in clay shales slopes clay shales largely outcrop in the northern apennines of italy where they are associated with frequent and widespread landslide activity the paper presents the results of monitoring activities carried out in two field sites and focused on the hydrology of clay shales prone to landsliding in the monitored slopes the water table is close to the ground surface throughout the year with seasonal fluctuations of tens of centimetres to a couple of metres shallow weathered soils or clay cover and unaltered material exhibit a much different behaviour although responses to single rainfalls are clearly identifiable as pressure pulses in the clay cover they are never observed in the underlying parental clay shales where downward gradients indicate recharge and only long term seasonal fluctuations are recorded short term variations of pressure head in the clay cover are ruled by downward propagation of a pressure wave in saturated conditions more than 400 pore pressure responses collected in the two sites are analysed in terms of lag time rate and amount of pressure increase and timing of pressure peaking it emerges that the linear diffusion theory can satisfactorily explain the observed behaviour in deeper unaltered material the barometric effect influences the measures similarly to what is observed in confined aquifers after its removal the corrected data exhibit regular seasonal fluctuations which are used to estimate the diffusivity of the material based on phase lag and attenuation of the downward propagating long term periodic pulse copyright 2011 john wiley sons ltd

stable isotopic evidence for latest miocene sea level fall in the mediterranean region the discovery of a marked isochronous decrease of carbon isotope ratio values 0 5 0 8 in marine carbonates at about 6 2 myr has stimulated several speculations regarding the origin of this event1 3 here we report stable isotope studies of planktonic and benthic foraminifera from the late miocene carmona dos hermanos section in southwestern spain which suggest that 1 the carbon shift at 6 2 myr is directly associated with a eustatic sea level lowering recorded in the same section 2 the shift in 13c at 6 2 myr and other times may be related to an increased flux of marine and terrigenous organic matter depleted in 13c and eroded from the continental shelves during sea level lowstands and 3 the sea level fall at 6 2 myr triggered the rapid shift towards hypersaline conditions in the mediterranean well before the deposition of the messinian evaporites

on late miocene abyssal hydrography abstract this contribution is a summary of our studies on late miocene isotope stratigraphy we interpret the results using simple models and present additional evidence that the 13 c shift at 6 2 ma was a time stratigraphic event the average deep water metabolic co 2 and nutrient content remained unchanged across the 13 c shift but the net flow of deep waters towards the north pacific was intensified the late miocene deep ocean density structure was similar to that of today s oceans and bottom water temperatures were 1 c warmer if constant ice volume is assumed

the late miocene to early pliocene climate transition in the southern ocean abstract we have constructed a relatively high resolution 5 10 kyr globigerina bulloides stable isotope record from ocean drilling program site 1088 south atlantic sector of the southern ocean together with the two published records from the high latitudes of the southern hemisphere that each span at least a portion of this interval of time we begin to assemble a spatial picture of sea surface hydrography during the late miocene early pliocene climate transition 8 3 ma we hypothesize that meridional movements in the frontal zones polar front and subtropical convergence with their impact on hydrographic gradients would be evident in temporal changes in the planktonic foraminiferal stable isotopic gradients among the sites our results indicate that there were no large changes in 18o gradients during the interval of study relatively small changes such as a gradual warming of about 3 4 c at site 1088 during the late miocene fall well within the realm of modern ocean seasonality in this region the early pliocene 18o records largely parallel the global decrease defined by benthic foraminifera in the deep pacific suggesting no amplified warming of surface waters in the southern ocean the planktic 13c records vary positively with the 18o records both in the long term trend as well as on the scale of individual data points we believe that this association reflects primarily reduced nutrient utilization during warmer intervals although a small component of the signal would also be consistent with reduced carbon isotope fractionation during air sea gas exchange during relatively warmer conditions if correct this argument would have implications for carbon cycling during the early pliocene and would support scenarios of elevated co2 levels

piezometric response in zones of a watershed with lateral preferential flow as a first order control on subsurface flow characterizing zones of a watershed based on the water table is used to understand and predict internal watershed processes in watersheds dominated by lateral preferential flow the water table response typically shows a distinct hydraulically limited pattern this response is characterized by a capping of the rising water table when the lateral preferential flow features are activated and subsurface flow still increases we expected that this response would be related to the contributing area since nearby hillslope excavations showed that the development of preferential flow network was positively correlated with the contributing area the watershed was stratified into three predetermined zones and installed 25 piezometers to measure the water table dynamics the objectives were 1 to characterize the water table runoff relationship 2 to prove preferential flow by observable characteristics and 3 to test the feasibility of identifying areas within a watershed that are dominated by lateral preferential flow watershed zones were not well defined and there was no strong relationship between the hydraulically limited response and observable watershed characteristics although zones might still be useful for grouping the hillslope processes the piezometric response may not be an appropriate indicator for mapping the watershed into areas with runoff dominated by lateral preferential flow copyright 2010 john wiley sons ltd

hydrometeorological controls and erosive response of an extreme alpine debris flow on 29 august 2003 an intense convective storm system affected the fella river basin in the eastern italian alps producing rainfall peaks of approximately 390 mm in 12 h the storm triggered an unusually large debris flow in the ungauged rio cucco basin 0 65 km2 with a volume of approximately 78 000 m3 the analysis of the time evolution of the rainstorm over the basin has been based on rainfall estimates from radar observations and data recorded by a raingauge network detailed geomorphological field surveys carried out both before and after the flood of august 2003 and the application of a distributed hydrological model have enabled assessment of flood response estimation of erosion volumes and sediment supply to the channel network the accounts of two eyewitnesses have provided useful elements for reconstructing the time evolution and the flow processes involved in the event liquid peak discharge estimates cluster around 20 m3 s 1 km 2 placing this event on the flood envelope curve for the eastern italian alps the hydrological analysis has shown that the major controls of the flood response were the exceptional cumulated rainfall amount required to exceed the large initial losses and the large rainfall intensities at hourly temporal scales required to generate high flood response at the considered basin scale observations on the deposits accumulated on the alluvial fan indicate that although the dominant flow process was a debris flow sheetflood also contributed to fan aggradation and fluvial reworking had an important role in winnowing debris flow lobes and redistributing sediment on the fan surface this points out to the large discharge values during the recession phase of the flood implying an important role for subsurface flow on runoff generation of this extreme flash flood event copyright 2009 john wiley sons ltd

pelagic carbonate chemostratigraphy sr mg 18o 13c abstract a synthesis of the elementary sr and mg and isotopic 18 o and 13 c geochemistry of mesozoic to recent bulk pelagic carbonates suggests that the influence of late burial diagenesis is considerably less than was previously thought and that bulk carbonate geochemistry could be important for both paleoceanography and stratigraphy numerous chemical fluctuations in sr ca mg ca and 13 c 12 c ratios have occurred in the ocean during the last 140 ma the main factors responsible are 1 variations in submarine hydrothermal activity and 2 sea level fluctuations the validity of the chemostratigraphic methodology can be demonstrated by the synchroneity and the worldwide occurrence of various geochemical shifts

spatio temporal variability of piezometric response on two steep alpine hillslopes information on the main drivers of subsurface flow generation on hillslopes of alpine headwater catchments is still missing therefore the dominant factors controlling the water table response to precipitation at the hillslope scale in the alpine bridge creek catchment northern italy were investigated two steep hillslopes of similar size soil properties and vegetation cover but contrasting topography were instrumented with 24 piezometric wells sixty three 63 rainfall runoff events were selected over three years in the snow free months to analyse the influence of rainfall depth antecedent moisture conditions hillslope topographic characteristics and soil depth on shallow water table dynamics piezometric response expressed as percentage of well activation and water peak magnitude was strongly correlated with soil moisture status as described by an index combining antecedent soil moisture and rainfall depth hillslope topography was found to be a dominant control only for the convex divergent hillslope and during wet conditions timing of water table response depended primarily on soil depth and topographic position with piezometric peak response occurring later and showing a greater temporal variability at the hillslope bottom characterized by thicker soil the relationship between mean hillslope water table level and standard deviation for all wells reflected the timing of the water table response at the different locations along the hillslopes the outcomes of this research contribute to a better understanding of the controls on piezometric response at the hillslope scale in steep terrain and its role on the hydrological functioning of the study catchment and of other sites with similar physiographic characteristics copyright 2014 john wiley sons ltd

an important current reversal influx in the rifian corridor morocco at the tortonian messinian boundary the end of tethys ocean atlantic psychrospheric and temperate mesopelagic faunas found in the lower messinian marls in morocco indicate that a strong eastward flowing bottom current was present in the rifian corridor before the salinity crisis this influx began just before diatomite deposition in the paleo mediterranean continued during a decrease in species diversity in coral reef formation and diminished with the initial stages of brine concentration in the deep water phase of the crisis the influx is most readily studied in a condensed section of marl in the bou regreg valley near rabat the beginning of this siphon event coincides with the tortonian messinian boundary 6 4 ma subchron 6n1 it is identified by 1 a change in the planktonic foraminifera from dominance of warm tropical epipelagic globorotalia menardii with globigerinoides to the temperate mesopelagic gl miotumida plexus with conomiozea 2 the sudden appearance of an upper psychrospheric ostracode fauna with agrenocythere pliocenica and oblitacythereis ruggierii 3 a change in nannoflora and 4 beginning of the 6 3 ma global carbon shift the initial strong influx stage of the siphon lasted at least 0 7 m y decreasing after the middle of chron 5 ca 5 7 to be lost ca 5 3 ma conditions for the siphon formed when the continental climate created a deficit in the water budget of the paleo mediterranean sea the reversal took place when tectonic movement in the foredeeps of the betic rif orogene changed the thresholds of the twin straits the rifian corridor and the iberian portal inflow increased rapidly in the southern corridor to draw in waters from beneath the rising atlantic pycnocline while paleo mediterranean overflow water pmow continued out of the northern iberian portal the invasion of nappes or olistoliths first into the portal and then into the corridor led to the end of the outflow of the pmow terminating the need for the siphon and then to the isolation of the paleo mediterranean

cainozoic oceanic and climatic events the indo pacific foraminiferal biostratigraphic record abstract datums in the biostratigraphic record are based on phylogeny meaning speciation and extinction and sometimes on coiling changes we can also employ various nonphylogenetic configurationssuch as disjunct distributions extratropical excursions and correlations with isotopic spikes progress in cainozoic geohistory depends on rigorous refined correlations between all environments on the earth in practice that means an opportunistic groping outward from the most secure and refined realm of our chronology tropical oceanic succession based on planktonic skeletonized protists towards the more difficult realms such as larger benthonic foraminifera in neritic sediments extra tropical oceanic and neritic successions continental faunas floras and palynofloral successions and finally and most elusively continental geomorphic successions formal zones are necessary but their proliferation is not a late eocene example of coincidence in time between planktonic foraminiferal marine dinoflagellate and terrestrial pollen zones suggests that heterogeneous oppelzones may be the soundest basis for local and regional stratigraphic systems the overall cainozoic climatic deterioration was reversed substantially in the eocene and in the miocene by shortlived far reaching bipolar events signalled by extratropical excursions by tropical type foraminifera in some cases correlated solidly with isotopic spikes widespread oceanic hiatuses appear to correlate with episodes of global warming and transgression better than with episodes of global cooling marginal hiatus and of intensified oceanic circulation australia s northward drift since the middle eocene notwithstanding wholesale diachronism no longer is a useful paradigm we are better off thinking in terms of virtually isochronous shifts in climate watermass and in planktonic and benthonic assemblages

threshold relations in subsurface stormflow 2 the fill and spill hypothesis analysis of subsurface stormflow from 147 storms at the 20 m long trench in the panola mountain research watershed by tromp van meerveld and mcdonnell 2006a showed that there was a distinct 55 mm precipitation threshold for significant subsurface stormflow production this second paper in the series investigates the processes responsible for this threshold response we installed a dense spatial array of maximum rise crest stage gauges and recording wells on the hillslope and studied the temporal and spatial patterns of transient saturation at the soil bedrock interface and its relation to subsurface stormflow measured at the trench face results show that while transient groundwater developed on parts of the hillslope during events smaller than 55 mm it was not until more than 55 mm of rain fell before bedrock depressions on the hillslope were filled water spilled over microtopographic relief in the bedrock surface and the subsurface saturated areas became connected to the trench when connectivity was achieved the instantaneous subsurface stormflow rate increased more than fivefold compared to before the subsurface saturated areas were connected to the trench face total subsurface stormflow was more than 75 times larger when connectivity was achieved compared to when connectivity was not achieved the fill and spill hypothesis presented in this paper is a process explanation for the observed threshold behavior of tromp van meerveld and mcdonnell 2006a thereby linking patterns and processes

element accumulation rates in and growth histories of manganese nodules from the southwestern pacific basin abstract accretion rates and element accumulation rates of seven manganese nodules collected from the southwestern pacific basin during r v sonne cruise so 14 on a tahiti east pacific rise new zealand transect have been determined the accretion rates of the nodules lie in the range 3 5 6 0 mm 10 6 yr the highest rates correspond to areas with higher biogenic silica contents in the sediment suggesting a higher diagenetic contribution to the nodules in one nodule 143gb dated with 10 be nodule growth began at about 14 5 ma there is a change in structure of the nodule at 6 ma and concentric layers filled with detritus occur at 3 2 ma and 1 3 ma there is also a major change in the flux rates of the elements at the 6 ma time marker with the authigenic elements mn cu and ni showing greater accumulation rates in the outer zone and the detrital fraction al showing a greater accumulation rate in the inner zone the variations in the element accumulation rates probably reflect a change of abyssal circulation pattern at 6 2 ma however the precise nature of this change remains a matter for speculation

topographic controls on shallow groundwater dynamics implications of hydrologic connectivity between hillslopes and riparian zones in a till mantled catchment hydrologic connectivity is regarded as one of the key controls in determining catchment rainfall run off response and has been linked to the export of solutes from uplands to streams we sought to identify the patterns of hydrologic connectivity within a small forested watershed by monitoring the shallow groundwater fluctuations of simple topographically defined landform sequences footslope backslope shoulder a spatially distributed instrument network was employed to continuously measure hydrometric responses of the shallow subsurface during seasonal wet up from summer through winter in a small till mantled research catchment we demonstrate that the spatial patterns of shallow water table extent and duration and therefore hydrologic connectivity had a strong seasonal signature during the low antecedent soil moisture conditions typically associated with the growing season water tables were patchy discontinuous and only the wettest near stream footslope areas were consistently hydrologically connected with the stream network during the dormant season footslopes and backslopes maintained water tables that persisted between storm events and were almost continuously connected with the stream network in the largest storm events the typically driest landforms shoulder slopes established shallow transient water tables suggesting that nearly the entire catchment was temporarily hydrologically connected with the stream network in addition we found significant differences p 0 05 in the magnitude and duration of groundwater responses to rainfall among landform groups both seasonally and during events these results have implications for using a similarity approach in representing characteristic hydrologic responses of topographically defined watershed elements determining hydrologic connectivity between watershed elements as well as for understanding solute transport in catchments copyright 2010 john wiley sons ltd

late miocene paleoclimatology subantarctic water mass southwest pacific abstract the late miocene early pliocene paleoclimatic history has been evaluated for a deep drilled sediment sequence at deep sea drilling project site 281 and a shallow water marine sediment sequence at blind river new ealand both of which lay within the subantarctic water mass during the late miocene a major faunally determined cooling event within the latest miocene at site 281 and blind river coincides with oxygen isotopic changes in benthonic foraminiferal composition at dsdp site 284 considered by shackleton and kennett 1975 to indicate a significant increase in antarctic ice sheet volume however at site 281 benthonic foraminiferal oxygen isotopic changes do not record such a large increase in antarctic ice volume it is possible that the critical interval is within an unsampled section no recovery in the latest miocene two benthonic oxygen isotopic events in the late miocene 0 5 and 1 in the light direction may be useful as time stratigraphic markers a permanent negative carbon isotopic shift at both site 281 and blind river allows precise correlations to be made between the two sections and to other sites in the pacific region close interval sampling below the carbon shift at site 281 revealed dramatic fluctuations in surface water temperatures prior to a latest miocene interval of refrigeration kapitean and a strong pulse of dissolution between 6 6 and 6 2 0 1 m y which may be related to a fundamental geochemical change in the oceans at the time of the carbon shift 6 3 6 2 m y no similar close interval sampling at blind river was possible because of a lack of outcrop over the critical interval paleoclimatic histories from the two sections are very similar surface water temperatures and antarctic ice cap volume appear to have been relatively stable during the late middle early late miocene early late tongaporutuan by 6 4 m y cooler conditions prevailed at site 281 between 6 3 and 6 2 0 1 m y the carbon isotopic shift occurred followed within 100 000 yr by a distinct shallowing of water depths at blind river the earliest pliocene opoitian is marked by increasing surface water temperatures

groundwater dynamics in a till hillslope flow directions gradients and delay knowledge of groundwater dynamics is important for the understanding of hydrological controls on chemical processes along the water flow pathways to increase our knowledge of groundwater dynamics

latest miocene benthic δ 18 o changes global ice volume sea level and the messinian salinity crisis oxygen isotope evidence indicates high but variable 18o values in benthic foraminiferal calcite during the latest miocene and earliest pliocene these high values may represent increases in global ice volume and associated sea level fall the 18o record resembles glacial interglacial cycles but with only one third the amplitude of the late pleistocene signal this variability may reflect instability in the antarctic ice sheet and palaeomagnetic correlation points to an isotopic event coinciding with the isolation and desiccation of the mediterranean basin during the latest messinian

the role of sea surface temperature as a control on carbonate platform development in the western coral sea the derivation of a detailed sea surface paleotemperature curve for the middle miocene holocene 10 0 ma from odp site 811 on the queensland plateau northeast australia has clarified the role of sea surface temperature fluctuations as a control on the initiation and development of the extensive carbonate platforms of this region this curve was derived from isotopic analyses of the planktonic foraminifer globigerinoides ruber and converted to temperature using the surface water paleotemperature equation accounting for variations in global ice volume the accuracy of these data were confirmed by derivation of paleotemperatures using the water column isotopic gradient 13o corrected for salinity and variations in seafloor water mass temperature results indicate that during this period surface water temperatures were on average greater than the minimum required for tropical reef growth 20 c veron 1986 with the exception of the late miocene and earliest early pliocene 10 4 9 ma when there were repeated intervals of temperatures between 18 20 c tropical reef growth on the queensland plateau was extensive from the early to early middle miocene 21 13 ma after which reef development began to decline a lowstand near 11 ma probably exposed shallower portions of the plateau after re immersion near 7 ma the areal extent of reef development was greatly reduced 50 paleotemperature data from site 811 indicate that decreased sea surface temperatures were likely to have been instrumental in reducing the area of active reef growth on the queensland plateau reduced reefal growth rates continued until the late pliocene or quaternary despite the increase of average sea surface paleotemperatures to 22 23 c studies on modern corals show that when sea surface temperatures are below 24 c as they were from the late miocene to the pleistocene off northeast australia corals are stressed and growth rates are greatly reduced consequently when temperatures are in this range corals have difficulty keeping pace with subsidence and changing environmental factors in the late pliocene sedimentation rates increased due to increases in non reefal carbonate production and falling sea levels it was not until the mid quaternary 0 6 0 7 ma that sea surface paleotemperatures increased above 24 c as a result of the formation of a western coral sea warm water pool because of age discrepancies it is unclear exactly when an effective barrier developed on the central great barrier reef the formation of the warm water pool was likely to have either assisted the formation of this barrier and or permitted increased coral growth rates fluctuations in sea surface temperature can account for much of the observed spatial and temporal variations of reef growth and carbonate platform distribution off northeast australia and therefore we conclude that paleotemperature variations are a critical control on the development of carbonate platforms and must be considered an important cause of ancient platform drowning

miocene biochronology and paleoceanography of the north pacific abstract biostratigraphic correlation based on microfossil datum levels directly or indirectly tied to the paleomagnetic time scale provides a high resolution time control for the miocene in the equatorial and middle latitude north pacific faunal changes and abundance fluctuations of planktic foraminiferal species combined with the oxygen pacific faunal changes and abundance fluctuations of planktic foraminiferal species combined with the oxygen isotope record of foraminifers reveal the paleoclimatic and paleoceanographic history the planktic foraminiferal assemblage change in the early miocene extinction of oligocene fauna and rise of a highly diverse neogene fauna appears to be related to increased water mass stratification in the world oceans presumably resulting from the establishment of circum antarctic circulation an increase in the siliceous productivity in the eastern equatorial pacific region between 20 and 18 ma suggests that the vertical and horizontal circulation was intensified at that time climates cooled rapidly during the middle miocene between 14 and 13 ma suggesting the growth of a major east antarctic ice sheet paleoclimatic conditions remained generally cool although oscillating during the late miocene in the late early to middle miocene faunal provincialism developed between low and middle latitudes and by late miocene time a distinct provincialism similar to the present was established

threshold behavior in a fissured granitic catchment in southern china 1 analysis of field monitoring results 1 an experimental granitic catchment in southern china was instrumented to continuously monitor the hydrologic processes within which two plots 5 m 10 m were equipped observed rainfall and corresponding responses of surface water soil water and groundwater were used to examine the hydrological threshold behaviors new hydrological thresholds were determined on the spatial scales of plot and catchment and on the temporal scales of storm event and month namely those between 1 the sum of total event precipitation p and the antecedent soil moisture index asi hereafter p asi and the total event interflow at plots a soil depth 200 250 cm and b soil depth 50 90 cm and between p asi and deep interflow at plot a within which an aquitard exists 2 p asi and event peak flow 3 the normalized maximum well water level nmwwl and event peak flow at the catchment scale and 4 p asi and monthly streamflow depth in addition thresholds between p asi nmwwl and event quick flow depth were identified in accordance with findings of previous studies based on the hydrometric observations we believed that the soil moisture deficit and bedrock depression storage were the main reasons for the threshold behavior in the study catchment below a specific threshold of p asi none or little interflow was generated on hillslopes and contributed to streamflow while interflow generated at the soil bedrock interface on hillslopes started to contribute to streamflow when it was above the threshold and the runoff contributing areas expanded from the near stream zone to hillslopes

middle miocene pliocene stable isotope stratigraphy and paleoceanography of the mediterranean abstract stable isotope analyses of the planktonic foraminifers globigerinoides obliquus and globigerinoides trilobus from a number of sections from sicily italy yielded a rather detailed middle miocene to upper pliocene record a comparison between this record and previously published stable isotope records from the pacific and atlantic oceans suggests that at least during the time span considered the mediterranean had a paleoclimatic and paleoceanographic history that bears a close resemblance to that of the world s oceans four different local mediterranean overprints on the general isotope signal are distinguished 1 the disruption of the tethys sea way and the subsequent installation of a strong salinity stratification 2 short term eustatic sea level changes during the miocene resulting in salinity stratification and sapropel deposition 3 periodic increase of run off and subsequent salinity stratification during the pliocene also resulting in sapropel deposition 4 pliocene trends in the carbon isotope pattern deviating from the oceanic one the reason for which remained obscure

hydrologic connectivity and threshold behavior of hillslopes with fragipans and soil pipe networks many concepts have been proposed to explain hydrologic connectivity of hillslopes with streams hydrologic connectivity is most often defined by qualitative assessment of spatial patterns in perched water tables or soil moisture on hillslopes without a direct linkage to water flow from hillslopes to streams this form of hydrologic connectivity may not explain the hydrologic response of catchments that have network s of preferential flow paths e g soil pipes which can provide intrinsic connectivity between hillslopes and streams duplex soils are known for developing perched water tables on hillslopes and fostering lateral flows but the connectivity of localized perched water tables on hillslopes with soil pipes has not been fully established the objectives of this study were to characterize pipeflow dynamics during storm events the relationships between perched water tables on hillslopes and pipeflows and their threshold behavior two well characterized catchments in loess soil with a fragipan were selected for study because they contain multiple laterally extensive over 100 m soil pipe networks hillslopes were instrumented with shallow wells adjacent to the soil pipes and the wells and pipe collapse features were equipped with pressure transducers perched water tables developed on hillslopes during a wetting up period october december and became well connected spatially across hillslope positions throughout the high flow period january march the water table was not spatially connected on hillslopes during the drying out april june and low flow july september periods even when perched water tables were not well connected water flowing through soil pipes provided hydrologic connectivity between upper hillslopes and catchment outlets correlations between soil pipeflow and perched water tables depended on the size and location of soil pipes the threshold relationship between available soil moisture index plus storm precipitation asi p and pipeflow was dependent on the season and strongest during dry periods and not high flow seasons this study demonstrated that soil pipes serve as a catchment backbone of preferential flow paths that provide intrinsic connectivity between upper hillslopes and streams

coupled productivity and carbon isotope records in the southwest pacific ocean during the late miocene early pliocene biogenic bloom biogenic components of sediment accumulated at high rates beneath frontal zones of the indian and pacific oceans during the late miocene and early pliocene the 13c of bulk and foraminiferal carbonate also decreased during this time interval although the two observations may be causally linked and signify a major perturbation in global biogeochemical cycling no site beneath a frontal zone has independent records of export production and 13c on multiple carbonate phases across the critical interval of interest deep sea drilling project dsdp site 590 lies beneath the tasman front tf an eddy generating jetstream in the southwest pacific ocean to complement previous 13c records of planktic and benthic foraminifera at this location late neogene records of caco3 mass accumulation rate mar ca ti ba ti al ti and of bulk carbonate and foraminiferal 13c were constructed at site 590 the 13c records include bulk sediment bulk sediment fractions 63 m and 5 25 m and the planktic foraminifera globigerina bulloides globigerinoides sacculifer with and without sac and orbulina universa using current time scales caco3 mars ca ti al ti and ba ti ratios are two to three times higher in upper miocene and lower pliocene sediment relative to overlying and underlying units a significant decrease also occurs in all 13c records all evidence indicates that enhanced export production the biogenic bloom extended to the southwest pacific ocean between ca 9 and 3 8 ma and this phenomenon is coupled with changes in 13c the chron c3ar carbon shift however caco3 mars peak ca 5 ma whereas elemental ratios are highest ca 6 5 ma foraminiferal 13c starts to decrease ca 8 ma whereas bulk carbonate 13c begins to drop ca 5 6 ma temporal discrepancies between the records can be explained by changes in the upwelling regime at the tf perhaps signifying a link between changes in ocean atmosphere circulation change and widespread primary productivity

stable isotopes in late middle eocene to oligocene foraminifera oxygen and carbon isotope ratios in eocene and oligocene planktonic and benthic foraminifera have been investigated from atlantic indian and pacific ocean locations the major changes in eocene oligocene benthic foraminiferal oxygen isotopes were enrichment of up to l in 18o associated with the middle late eocene boundary and the eocene oligocene boundary at locations which range from 1 to 4 km paleodepth although the synchronous eocene oligocene 18o enrichment began in the latest eocene most of the change occurred in the earliest oligocene the earliest oligocene enrichment in 18o is always larger in benthic foraminifera than in surface dwelling planktonic foraminifera a condition that indicates a combination of deep water cooling and increased ice volume planktonic foraminiferal 18o does not increase across the middle late eocene boundary at our one site with the most complete record deep sea drilling project site 363 walvis ridge this pattern suggests that benthic foraminiferal 18o increased 40 m y ago because of increased density of deep waters probably as a result of cooling although glaciation cannot be ruled out without more data stable isotope data are averaged for late eocene and earliest oligocene time intervals to evaluate paleoceanographic change average 18o of benthic foraminifera increased by 0 64 from the late eocene to the early oligocene 18o maximum whereas the average increase for planktonic foraminifera was 0 52 this similarity suggests that the eocene oligocene boundary 18o increase was caused primarily by increased continental glaciation coupled with deep sea cooling by as much as 2 c at some sites average 18o of surface dwelling planktonic foraminifera from 14 upper eocene and 17 lower oligocene locations when plotted versus paleo latitude reveals no change in the latitudinal 18o gradient the oligocene data are offset by 0 45 also believed to reflect increased continental glaciation at present there are too few deep sea sequences from high latitude locations to resolve an increase in the oceanic temperature gradient from eocene to oligocene time using oxygen isotopes

carbon and oxygen isotopic disequilibria of recent deep sea benthic foraminifera abstract the carbon and oxygen isotopic compositions of 149 samples of benthic foraminifera from deep sea core tops indicate that none of the nine species studied secrete calcium carbonate in isotopic equilibrium with ambient bottom water uvigerina pyrgo murrhina and oridorsalis tener are the closest to 18o equilibrium with average deviations about 0 4 while planulina wuellerstorfi and p murrhina are the closest to 13c equilibrium with average deviations about 1 p wuellerstorfi shows the most systematic relationship between 13c and bottom water apparent oxygen utilization the intraspecific variabilities in 18o and 13c suggest that estimates of bottom water paleotemperatures can be made to a precision of 0 7 c while estimates of past apparent oxygen utilization aou can be made to 35 mol kg based on intraspecific comparisons of the recent samples with fossils no temporal changes in the degree of either 18o or 13c disequilibrium have been detected for planulina wuellerstorfi uvigerina oridorsalis tener and globocassidulina subglobosa

the vallesian mammal succession in the valles penedes basin northeast spain paleomagnetic calibration and correlation with global events abstract the integrated lithostratigraphic biostratigraphic and magnetostratigraphic study of new and classical alluvial fan sequences in the valles penedes basin northeast spain western mediterranean enabled a considerable refinement of the vallesian mammalian succession in this basin and its correlation with the magnetic polarity time scale up to 12 new sections were logged and sampled in a search of mammal remains and a paleomagnetic analysis was carried out the correlation among these sections was based on the small mammal content and the succession of magnetozones enabling the establishment of four main composite sections les fonts montagut terrassa and viladecavalls as a result the vallesian in the valles penedes basin appears punctuated by four main mammalian events which coincide with the appearance of the genera hipparion cricetulodon progonomys and rotundomys the hipparion event did not coincide with any further change in the associations of small and large mammals the dispersal of the cricetid cricetulodon in its turn involved the first set of extinctions in the vallesian affecting the rodent and carnivore and artiodactyl associations the main break during the vallesian coincided with the dispersal of the murids of the genus progonomys and implied a sudden drop in the diversity of the rodent and artiodactyl species of warm wet forested affinities this phase is characterized by the association of the murid progonomys and the cricetid cricetulodon and includes the last record of hominoids in the basin the replacement of cricetulodon by the sigmodont cricetid rotundomys was associated with the entry of some typical early turolian species according to the correlation established it is concluded that the fad of hipparion in the valles penedes basin is dated at 11 1 ma at the base of chron c5r 1n this data is congruent with other datings in northern africa and eastern europe suggesting the isochrony of this event in the mediterranean regions the cricetulodon fad is dated to 10 4 ma in chron c5n the progonomys dispersal coincident with the late vallesian crisis is dated at 9 7 ma in chron c4ar 3r the rotundomys fad is dated at 9 2 9 3 ma in the upper part of chron c4ar 1n the vallesian mammal bioevents affected the peri mediterranean zones including northern africa and other regions in northern and western eurasia these paleofaunistic changes were caused by temperature descent from subtropical to warm temperate conditions as well as by changes in the aridity balance and seasonality this climatic evolution was the result of the interplay of diverse global events cooling of the high latitude regions growing of the antarctica ice sheet and enhancement of the thermohaline oceanic circulation and of large scale tectonic and paleogeographic processes surface uplift of the himalayas the tibetan plateau and other tectonic reliefs closing of gateways between the mediterranean marine regions and the world ocean the magnetobiochronology resulting from the study of the western valles sequences suggests a close chronological correlation between some of these global and regional processes and the vallesian bioevents recorded

marine planktic diatom correlation of lower messinian deposits in the western mediterranean abstract samples from late neogene mediterranean outcrops were analysed for diatom content the presence of certain species in the tripoli formation caltanissetta basin sicily and in the beida formation cheliff basin nw algeria permits correlation between these sections and the paleomagnetic reversal record the occurrence ofthalassiosira praeconvexa thalassiosira miocenica thalassiosira convexa var aspinosa andasterolampra acutiloba indicates that the tripoli and beida formations were deposited over an interval ranging from the upper half of paleomagnetic epoch 6 into the lower half of epoch 5 5 6 to 5 9 ma previous diatom correlations were too young the occurrence ofnitzschia reinholdii andasterolampra acutiloba in pre evaporitic diatomites from the upper turre formation se spanish sorbas basin is used to place deposits at this site tentatively in paleomagnetic epoch 5 or 6

mid miocene paleoproductivity in the atlantic ocean and implications for the global carbon cycle 1 a prominent middle miocene 17 5 13 5 ma carbon isotope excursion ubiquitously recorded in carbonate sediments has been attributed to enhanced marine productivity and sequestration of 13c depleted organic carbon in marine sediments or enhanced carbon burial in peat lignite deposits on land here we test the hypothesis that the marine 13c record reflects a change in productivity with proxy records from three atlantic ocean sites deep sea drilling program site 608 and ocean drilling program sites 925 and 1265 our multiproxy approach is based on benthic foraminiferal accumulation rates elemental ratios ba al and p al the 13c of bulk sedimentary organic matter and dissolution indices we compare these proxies to benthic foraminiferal 13c values measured on the same samples our results indicate that marine paleoproductivity in the atlantic ocean is not related to the benthic foraminiferal 13c excursion a numerical box model confirms that marine productivity cannot account for the 13c maximum the model shows that sequestration of 1 5 1018 mol c in the terrestrial realm over a period of 3 ma leads to a 0 9 13c increase in the deep ocean which is near the observed records therefore an increase in continental organic carbon sequestration is the most plausible way to enrich the ocean s carbon pool with 13c which is consistent with coeval lignite deposits worldwide the 13c values of bulk sedimentary organic matter parallel the 13c of dissolved inorganic carbon as reflected by benthic foraminiferal 13c values suggesting no significant change in atmospheric pco2 levels over the investigated period

late miocene through early pliocene deep water circulation and climate change viewed from the sub antarctic south atlantic benthic foraminiferal stable isotope records for the past 11 myr from a recently drilled site in the sub antarctic south atlantic site 1088 ocean drilling program leg 177 41 s 15 e 2082 m water depth provide for the first time a continuous long term perspective on deep water distribution patterns and southern ocean climate change from the late miocene through the early pliocene i have compiled published late miocene through pliocene stable isotope records to place the new south atlantic record in a global framework carbon isotope gradients between the north atlantic south atlantic and pacific indicate that a nutrient depleted watermass probably of north atlantic origin reached the sub antarctic south atlantic after 6 6 ma by 6 0 ma the relative proportion of the northernprovenance watermass was similar to today and by the early pliocene it had increased to greater than the modern proportion suggesting that thermohaline overturn in the atlantic was relatively strong prior to the early pliocene interval of inferred climatic warmth site 1088 oxygen isotope values display a two step increase between v7 4 ma and 6 9 ma a trend that parallels a published n 18 o record of a site on the atlantic coast of morocco this is perhaps best explained by a gradual cooling of watermasses that were sinking in the southern ocean i speculate that relatively strong thermohaline overturn at rates comparable to the present day interglacial interval during the latest miocene may have provided the initial conditions for early pliocene climatic warmth the impact of an emerging central american seaway on atlantic pacific ocean upper water exchange may have been felt in the north atlantic beginning in the latest miocene between 6 6 and 6 0 ma which would be v1 5 myr earlier than previously thought 9 2002 elsevier science b v all rights reserved

pan african high pressure metamorphism in the precambrian basement of the menderes massif western anatolia turkey the menderes massif is made up of pan african basement and a paleozoic to early tertiary cover sequence imbricated by late alpine deformation the precambrian basement comprises primarily medium to high grade schists paragneisses migmatites orthogneisses metagranites charnockites and metagabbros high pressure relics in the pan african basement are divided into two groups eclogites and eclogitic metagabbros the mineral assemblage in the eclogites is omphacite jd 44 garnet clinozoisite rutile the eclogites occur as pods and boudinaged layers in the basement schists and paragneisses inclusions found in the cores of the garnets indicate a medium pressure protolith the eclogitic metagabbros are closely related to precambrian gabbroic stocks the igneous texture and relic magmatic phases are preserved in these high pressure rocks which are characterized by the mineral assemblage omphacite jd 25 garnet rutile kyanite the p t conditions of the pan african high pressure metamorphism in the eclogites are estimated to be 644 c with a minimum pressure of approximately 15 kbar the eclogites are partly to completely retrograded to garnet amphibolites by a barrovian type overprint which developed under isothermal decompression conditions for this post eclogitic event the p t estimates are 7 kbar and 623 c the eclogite relics provide strong support for a correlation of the menderes massif with the bitlis massif in terms of common pan african high pressure evolution

late neogene paleoceanography and paleoclimatology of the gulf of aden region based on calcareous nannofossils quantitative study of climatically sensitive nannofossils in the sediments of the gulf of aden has provided a climatic and oceanographic scenario for the northwestern indian ocean during the late neogene the surface water temperature was relatively cold during the latest middle miocene to late miocene 10 7 to 6 32 ma with a probable warm interval in the early late miocene 9 82 to 8 49 ma this cooling is attributed to increased upwelling in the northwestern indian ocean the surface water was relatively warm from the latest late miocene to the middle of the late pliocene 6 32 to 2 59 ma the most intense cooling took place during the late pliocene to early pleistocene 2 59 to 1 69 ma intense upwelling during this interval coincides with worldwide climatic deterioration a probable short warm interval 1 69 to 1 59 ma followed this cold interval in the pleistocene the surface water was cold from 1 59 to 1 00 ma and from 0 61 to 0 24 ma and warm from 1 00 to 0 61 ma and after 0 24 ma

late miocene early pliocene stratigraphy and paleoceanography of the south atlantic and southwest pacific oceans a synthesis the stratigraphy and paleoceanography of the late miocene and early pliocene have been examined at six sites in the south atlantic and southwest pacific oceans deep sea drilling project dsdp sites 284 516a 519 588 and 590 and two piston cores from chain cruise 115 a consistent stratigraphy was developed among sites using graphic correlation which resulted in age models for all sites that are tied to the revised paleomagnetic time scale of berggren et al 1985 applying these chronologies we assessed latitudinal and interocean contrasts in the stratigraphic ranges of late miocene early pliocene planktonic foraminiferal and nanno fossil datums salient stratigraphic results include 1 the last appearance datum lad of globoquadrina dehiscens is a late miocene 6 4 ma event in the subtropics and is not useful for the placement of the miocene pliocene m p boundary in this biogeographic province 2 the first appearance datum fad of globorotalia crassaformis occurred at 5 1 ma in the south atlantic near the m p boundary suggesting that gr crassaformis may have first evolved in the south atlantic and later migrated to other regions 3 in the southwest pacific the fads of gr margaritae 5 97 ma gr puncticulata 5 09 ma and gr crassaformis 4 87 ma are significantly time transgressive between temperate and warm subtropical regions time lags of 1 0 m y were required for these species to adapt to physical and or biotic conditions peripheral to their endemic biogeographic provinces 4 between the subtropics of the south atlantic and southwest pacific many planktonic foraminiferal datums fad of dentogloboquadrina altispira gr cibaoensis gr conomiozea gr margaritae and gq dehiscens and lad of gr cibaoensis markedly depart from the correlation suggested by magnetostratigraphy indicating that these datum levels are unreliable for correlation between these ocean basins 5 in contrast available calcareous nannofossil datum levels fall on or near the paleomagnetic correlation line indicating synchroneity of events within the subtropics 6 biostratigraphic magnetic and 87sr 86sr correlation between sites 588 and 519 and the m p neostratotype at capo rossello sicily suggests that the base of the zanclean stratotype occurs at 5 1 5 0 ma in the lower reversed subchron of the gilbert about 2 3 105 years above the gilbert chron 5 boundary oxygen isotopic results from dsdp sites 284 519 and ch115 piston cores confirm a prolonged benthic 18o increase in the latest miocene between 5 6 and 5 0 ma as originally proposed by shackleton and kennett 1975 at dsdp site 588 the benthic 18o record in the latest miocene is marked by high frequency fluctuations with amplitude variations of 0 5 and a long period wavelength component of 400 000 years maximum 18o values however occurred during the late miocene kapitean stage between 5 5 and 5 1 ma the late miocene 18o changes resulted from mid and high latitude cooling and pulses of ice sheet expansion and contraction glacial events were most intense during the latest miocene kapitean stage and occurred at 5 50 5 35 ma and at 5 10 ma glacial events are estimated to have lowered sea level by 40 to 60 m and contributed to the isolation and desiccation of the mediterranean basin during the late messinian interglacial conditions prevailed at 5 2 ma and between 5 0 and 4 1 ma ihe early pliocene the beginning of the pliocene was marked by changes in many proxy climatic indicators at all sites suggesting a prolonged interval of warm interglacial conditions between 5 0 and 4 1 ma during the earliest pliocene supplementary tables are available with entire article onmicrofiche order from american geophysical union 2000florida avenue n w washington dc 20009 documentp86 001 2 50 payment must accompany order

late pliocene variations in the carbon isotope values of north atlantic benthic foraminifera biotic control of the isotopic record abstract analyses of benthic foraminifera carbon isotope values were made in 172 samples from the late pliocene at dsdp site 548 which is located in the northeast atlantic on the continental slope southwest of ireland 1253 m water depth the carbon isotope record is quite stable from about 3 4 to 2 5 ma and contrasts with the record at site 552a in the north atlantic 2311 m water depth which is much more variable for this time period the carbon record at site 548 is also consistently more negative than that of site 552a after 2 5 ma the benthic carbon isotope record of uvigerina at site 548 becomes extremely variable with large negative deviations these isotopic variations might be associated with paleoceanic circulation changes caused by glaciation between 2 5 and 2 ma however paired analyses of uvigerina and cibicidoides species for 38 samples within the glacial interval yield carbon isotopic records which are quite different from one another the uvigerina record contains larger negative deviations than does the cibicidoides record also the isotopic difference between uvigerina and cibicidoides increases during glaciations and in a long term trend from 2 5 to 2 0 ma the lack of covariance between the uvigerina and cibicidoides carbon isotope records indicates that after 2 5 ma at site 548 biotic factors influenced the benthic isotopic record

late miocene carbon isotope records and marine biological productivity was there a dusty link 1 we examine whether or not a relationship exists between the late miocene carbon isotope shift 7 6 6 6 ma and marine productivity at four sites from the indian and pacific oceans ocean drilling program sites 721 1146 1172 and 846 we use a multiproxy approach based on benthic foraminiferal accumulation rates elemental ratios and dissolution indices and we compare these data to benthic foraminiferal 13c values measured on the same samples although some of these sites have been targeted previously in studies of either the late miocene early pliocene biogenic bloom sites 721 and 846 or the late miocene carbon isotope shift site 1172 our records are the first to establish paired proxy records of carbon isotopes and paleoproductivity allowing a direct assessment of a potential link our results indicate that at all sites productivity increased sometime during the 13c shift at three sites 721 1146 and 846 productivity increased at the beginning of the shift the correlation coefficients derived from linear regression between micropaleontologically derived productivity and foraminiferal 13c values are relatively high during the time interval containing the late miocene 13c shift and statistically significant at three of the sites carbon flux and isotope mass balance considerations illustrate that transfer of organic matter between the terrestrial and marine reservoirs together with enhanced oceanic upwelling best approximates observed changes in carbon isotope records and paleoproductivity we note that long term trend in the site 846 paleoproductivity record can be correlated to the long term trend in the site 848 eolian flux reconstructions of hovan 1995 hinting at a link between strengthened wind regime and productivity during the late miocene

miocene deepwater oceanography a global synthesis of miocene benthic foraminiferal carbon and oxygen isotopic and faunal abundance data indicates that miocene thermohaline circulation evolved through three regimes corresponding approximately to early middle and late miocene times there is evidence for major qualitative differences between the circulation of the modern ocean and the miocene ocean prior to 11 ma the 13c 12c ratios of the benthic foraminifera cibicidoides are interpreted in terms of water mass aging i e the progressive depletion of dissolved o2 and lowering of 13c values as the result of oxidation of organic matter as water flows further from its sources at the surface of the oceans both isotopic and faunal data indicate that the early miocene regime from 22 to 15 ma was the most different from today s during that interval intermediate and deep waters of both the atlantic and the pacific oceans aged in a northward direction and the intermediate waters of the indian the south atlantic and the south pacific oceans were consistently the youngest in the global ocean we speculate that early miocene global thermohaline circulation may have been strongly influenced by the influx of warm saline water tethyan indian saline water from the tethys into the northern indian ocean the isotopic and faunal data suggest that flow from the tethyan region into the indian ocean diminished or terminated at about 14 ma isotopic and faunal data give no evidence for north atlantic deep water nadw formation prior to about 14 5 ma with the exception of a brief episode in the early miocene from 14 5 to 11 ma nadw formation was weak and circumpolar and antarctic water flooded the deep south atlantic and south pacific as the antarctic ice cap grew from about 10 ma to the end of the miocene thermohaline circulation resembled the modern circulation in many ways in latest miocene time 6 to 5 ma circulation patterns were very similar to today s except that nadw formation was greatly diminished the distribution pattern of siliceous oozes in miocene sediments is consistent with our proposed reconstruction of thermohaline circulation major changes which occurred in circulation during the middle miocene were probably related to the closing of the tethys and may have contributed to rapid middle miocene growth of the antarctic ice cap appendices 1 4 6 and 7 are available withentire article on microfiche order fromamerican geophysical union 2000 floridaavenue n w washington dc 20009 document 88p 002 5 00 payment mustaccompany order

stratigraphy of upper cretaceous palaeogene sequences in the southern and eastern menderes massif western turkey the stratigraphy of the uppermost levels of the menderes massif is controversial and within its details lie vital constraints to the tectonic evolution of south western turkey our primary study was carried out in four reference areas along the southern and eastern menderes massif these areas lie in the upper part of the menderes metamorphic cover and have a clear stratigraphic relationship and contain datable fossils the first one in the akbuk milas area is located south east of bafa lake where the milas then kizilagac and kazikli formations are well exposed there the milas formation grades upwards into the kizilagac formation the contact between the kizilagac and the overlying kazikli formation is not clearly seen but is interpreted as an unconformity the milas and kizilagac formations are also found north of mugla in the region of yatagan and kavaklidere in these areas the milas formation consists of schists and conformably overlying platform type emery and rudist bearing marbles rudists form the main palaeontological data from which a santonian campanian age is indicated the kizilagac formation is characterized by reddish greyish pelagic marbles with marly pelitic interlayers and coarsening up debris flow deposits pelagic marbles within the formation contain planktonic foraminifera and nanoplankton of late campanian to late maastrichtian age the kazikli formation is of flysch type and includes carbonate blocks planktonic foraminifera of middle palaeocene age are present in carbonate lenses within the formation in the serinhisar tavas area mesozoic platform type marbles yilanli formation belonging to the cover series of the menderes massif exhibit an imbricated internal structure two rudist levels can be distinguished in the uppermost part of the formation the first indicates a middle late cenomanian age and the upper one is santonian to campanian in age these marbles are unconformably covered by the palaeocene early eocene zeybekolentepe formation with polygenetic breccias in the cal denizli area the menderes massif succession consists of cherty marbles and clastic rocks with metavolcanic lenses the lower middle eocene alvan formation lies unconformably on this sequence and is interpreted as equivalent to the marble horizons at serinhisar but with pelagic facies the alvan formation consists of shale mafic volcanic rock lenses of limestone and blocks of recrystallized limestone the alvan formation is dated here for the first time by early middle eocene foraminifera and nanoplankton from the matrix of the formation an angular unconformity exists between the upper cretaceous and lower tertiary sequences suggesting that a phase of deformation affected the southern and eastern part of the menderes massif at this time this deformation may be caused by initial obduction of the lycian ophiolite onto the passive margin to the north of the menderes carbonate platform during the latest cretaceous drowning of the platform led to termination of carbonate deposition and deposition of deep water flysch like clastic sediments

igneous origin of co2 in ancient and recent hot spring waters and travertines from the northern argentinean andes abstract thermal travertines are an archive of co2 sources and sinks in hydrothermal systems two major regional factors control travertine precipitation water availability and co2 supply thus travertines form a valuable archive of hydrodynamic variability and sources of main contributions to dissolved inorganic carbon dic it is relevant to determine the main dic sources of thermal waters i e organic matter degradation recycled from older carbonates emission of deep seated magmatic co2 as they are key inputs to calculate the lithosphere atmosphere co2 budget the antuco travertine from the central andes represents one of such archives with a 500 ky record of accretionary periods dated as 425 320 260 and 155 ky bp related to high hydrothermal activity of hot springs it consists of two travertine units 1 a lower massive unit displaying large calcite pseudomorphs after aragonite that precipitated in proximal ponds with abundant water and 2 an upper stratified unit showing more distal facies bearing siliciclastics and manganese and iron oxides the replacement of aragonite by calcite in the lower unit was related to the decrease of water salinity in the thermal system through time in the antuco travertine dic 13c values of travertine parental waters of around 9 suggest that co2 was related to igneous processes and volcanic activity and released along deep seated faults relative water rock ratios derived from 18o values and fluid inclusion microthermometric data from travertine carbonates are consistent with an interpretation of greater water availability in the hydrothermal system during the late pleistocene than at present the different petrographic features and isotopic signatures are interpreted to reflect increased water availability during more humid periods in the altiplano which triggered precipitation of travertine bodies travertine growth took place during interglacial humid climate periods between marine isotope stages mis 3 and 9 which correspond to highstand events in large lakes of the andean altiplano results of this study illustrate that volcanic activity furnishing rather constant co2 and heat fluxes were the key controls of thermalism in the altiplane region during the quaternary whilst climatic changes humid vs arid periods in the late pleistocene controlled mineralogy facies and architecture of the travertines the combined use of 13c and 87sr 86sr signatures in carbonate precipitates has been proven to be of major relevance to evaluate the co2 sources along fault zones in this study

geochemical constraints for the origin of thermal waters from western turkey the combined chemical composition b and sr isotopes and the basic geologic setting of geothermal systems from the menderes massif in western turkey have been investigated to evaluate the origin of the dissolved constituents and mechanisms of water rock interaction four types of thermal water are present 1 a na cl of marine origin 2 a na hco3 type with high co2 content that is associated with metamorphic rocks of the menderes massif 3 a na so4 type that is also associated with metamorphic rocks of the menderes massif with h2s addition and 4 a ca mg hco3 so4 type that results from interactions with carbonate rocks at shallow depths the na cl waters are further subdivided based on br cl ratios water from the cumali seferihisar and bodrum karaada systems are deep circulated seawater br cl sea water whereas water from canakkale tuzla br cl sea water are from dissolution of messinian evaporites good correlations between different dissolved salts and temperature indicate that the chemical composition of the thermal waters from non marine geothermal systems is controlled by 1 temperature dependent water rock interactions 2 intensification of reactions due to high dissolved co2 and possibly hcl gasses and 3 mixing with overlying cold groundwater all of the thermal water is enriched in b the b isotopic composition 11b 2 3 to 18 7 n 6 can indicate either leaching of b from the rocks or b oh 3 degassing flux from deep sources the large ranges in b concentrations in different rock types as well as in thermal waters from different systems suggest the water rock mechanism 87sr 86sr ratios of the thermal water are used to differentiate between solutes that have interacted with metamorphic rocks 87sr 86sr ratio as high as 0 719479 and carbonate rocks low 87sr 86sr ratio of 0 707864

miocene benthic foraminiferal isotope records a synthesis abstract 18 o 16 o and 13 c 12 c ratios of miocene benthic foraminifera from a number of atlantic pacific and indian ocean dsdp sites 71 77b 206 208 238 279 289 296 329 357 and 366a have been compiled these provide a rather detailed history of miocene deep water especially in the pacific ocean bottom water temperatures rose during the early miocene and then declined rapidly during the middle miocene this decline was accompanied by an increase in antarctic glaciation late miocene bottom temperatures and antarctic ice volumes are inferred to be similar to today s but exhibited some fluctuation the early miocene ocean was less thermally stratified at intermediate and abyssal depths while the late miocene deep ocean had a thermal structure generally similar to the modern ocean foraminiferal carbon isotope ratios at most of the sites varied quasi sympathetically throughout the miocene these variations must reflect comparable variations in the mean 13 c 12 c of marine hco 3 however the causes of such variations are not yet clear

globorotalia planktic foraminifera at the miocene pliocene boundary in new zealand abstract mid latitude assemblages of globorotalia in the late miocene and early pliocene of new zealand are dominated by the g miozea complex and its derivative taxa most of which appear rather suddenly in the basal pliocene the most uninterrupted sequence present in dsdp site 284 on the challenger plateau is closely matched in the north island mangapoike river section which is correlated by biostratigraphy geomagnetic polarity and a fission track date with blind river in the south island k ar dates of 5 2 m y and 5 3 m y for basalt associated with basal pliocene fossiliferous deposits in the chatham islands support the location of the miocene pliocene boundary at or close to the gilbert chron 5 boundary the isotopic record indicates that there were one or more periods of oceanic instability accompanied by cooling and polar ice accumulation in the late miocene immediately before the marked phase of evolutionary radiation of globorotalia in the early pliocene

hillslope riparian stream connectivity and flow directions at the panola mountain research watershed to obtain a better understanding of water s journey from the hillslope to the stream water level time series from 26 groundwater wells in a hillslope riparian study area in the panola mountain res

isotopic paleoceanography of the caribbean and east pacific role of panama uplift in late neogene time comparisons of carbon isotopic data on benthic foraminifera from deep sea drilling project sites 502 western caribbean and 503 eastern pacific indicate that the difference between the atlantic and the pacific in the per mil enrichment in carbon 13 of total dissolved carbon dioxide increased about 6 million years ago and again 3 million years ago when the difference reached the modern level 1 per mil comparisons of planktonic foraminiferal oxygen isotopic data for the caribbean and the pacific suggest that the salinity of caribbean surface waters began increasing 4 million years ago possibly in response to shoaling of the panama isthmus these results suggest that modern circulation patterns in the caribbean and eastern pacific developed by 3 million years ago in concert with changing tectonic climatic and biogeographic patterns

late miocene globorotaliid event stratigraphy and biogeography in the ne atlantic and mediterranean abstract the quantitative study of keeled and unkeeled globorotallids in several late miocene sites of the ne atlantic the north betic and south rifian gateways and the western mediterranean enabled us to recognize a sequence of planktic foraminiferal pf events useful for a high resolution correlation of the mediterranean with the global ocean for the time interval immediately prior to the salinity crisis pf event 1 6 7 ma end of subchron 7n1 is defined by the sudden disappearance or reduction ofgloborotalia menardii group i sinistral in most of the ne atlantic and mediterranean this is probably due to a southward migration of these forms to more subtropical latitudes pf event 2 6 56 ma subchron 6r2 is defined by the abundant occurrence ofgloborotalia menardii group ii dextral between pf events 1 and 2 the temperate waters of the ne atlantic ocean and mediterranean sea were almost completely lacking in keeled globorotaliids the most prominent change in the assemblages the replacement of thegloborotalia menardii group ii by thegloborotalia miotumida group pf event 3 6 4 ma subchron 6n may be correlated with the tortonian messinian boundary and is related to a widespread second southward migration of northern temperate faunas replacing the subtropical ones as the north atlantic latitudinal thermal gradients increased this event also coincides with the beginning of the mediterranean crisis recorded by isotope fluctuations in surface waters and immediately followed by the development of widespread anoxic conditions in the deep and intermediate waters during the deposition of the tripoli formation pf event 4 first abundant occurrence of dextral specimens in theneogloboquadrina acostaensis group approximately between 5 6 and 5 5 ma subchron 5r1 and pf event 5 reduction or disappearance of thegloborotalia miotumida group approximately between 5 6 and 5 5 ma subchron 5r1 pre date the lower evaporites and pf event 6 first abundant occurrence ofgloborotalia margaritae s s subchron 5n1 is contemporary to their deposition the coiling direction of unkeeled globorotaliids highly variable in the first part of the late tortonian became almost 100 dextral pf event a a short time after pf event 2 this group maintained this pattern until the late messinian with the exception of a short interval with a peak of sinistral forms just at the tortonian messinian boundary on comparing these events with the carbon isotope records of different sites of the atlantic ocean we recognized similar trends between the events maximum 13c values in planktic and benthic foraminifera coincide with pf event 1 they decrease between pf events 1 and 2 and increase again immediately after pf event 2 pf event 3 coincides with the beginning of the global late miocene carbon shift

core top evaluation of benthic foraminiferal isotopic ratios for paleo oceanographic interpretations abstract the benthic foraminifera cibicides wuellerstrofi oridforsalis tener and pyrgo rotalaria from twelve core tops in the norwegian greenland sea and c wuellerstorfi o tener and o umbonatus from four core tops on the rio grande rise were analysed for oxygen and carbon isotopes the norwegian greenland sea data yield statistically discrete means for both 18o and 13c for each species the interregional comparison of our data to published data from the east pacific rise shows that c wuellerstorfi 18o and 13c variations reflect oceanographic differences between sites whereas the data on oridorsalis and pyrgo do not we conclude that c wuellerstorfi is a reliable sensor of bottom water conditions whereas other taxa are of unproven utility supportive biological studies and the lack of positive covariance of 18o to 13c among deep sea benthic taxa lead us to reject models calling for incorporation of metabolic co2 to explain the isotopic variation among deep sea benthic foraminifera we propose a within sediment microhabitat hypothesis to explain the 13c variations among taxa

paleo oceanography global ocean evolution paleoceanography one of the youngest branches of earth sciences is concerned with the development of oceanic circulation through geologic time this is a multifaceted and integrated endeavor since none of the subdisciplines is easily separated from the others the field is holistic in character and includes the history and effects of bottom intermediate and surface circulation patterns planktonic and benthonic biogeographic development and rates of organic evolution the history of biogenic productivity and dissolution and their effect on sediment distribution and the consequences of sea level change paleoceanography was largely born of the deep sea drilling project dsdp and continues to be nourished by it because problems are of global scope the appetite for new sediment core material is large and is being supplied by numerous expeditions of dsdp this article is a brief overview of a number of advances that have occurred in paleoceanography and related fields during the period from 1979 to 1982 because of page limitations all publications cannot be cited which is not meant to indicate any lack of importance

miocene equatorial and southwest pacific paleoceanography from stable isotope evidence abstract stable isotope results from seven miocene deep sea drilling projects in the equatorial and southwest pacific ocean previously correlated using carbon isotope stratigraphy have been examined discussed and interpreted in terms of the development of the miocene pacific ocean the most obvious features of the benthonic foraminiferal stable isotopic records are a major increase in 18o 1 0 during the middle miocene a series of long term oscillations 2 3 my of amplitude 0 5 0 75 and a decrease in 13c values 0 5 1 0 during the latest miocene planktonic foraminiferal 18o records show different trends for high and low latitude regions in the equatorial pacific planktonic 18o values actually decrease during the miocene whereas in the higher southern latitudes planktonic 18o values become more positive in response to cooling surface waters planktonic 13c records show opposite trends to 18o with the high latitude values becoming more negative relative to the tropical regions the development of the miocene pacific ocean in terms of its vertical and horizontal thermal structure and isotopic composition is well illustrated by examining changes in the isotopic difference between planktonic and benthonic foraminifera 18ob p benthonic planktonic is a measure of the thermal structure of the water column 18oph pl high latitude low latitude planktonic values is a measure of the latitudinal temperature gradient 13cb p is an indirect measure of nutrient concentrations in the water column and 13cph pl measures differences in surface water nutrient concentrations between high and low latitude 18ob p increases during the miocene with the greatest increase occurring in the middel miocene at about 14 ma by the latest miocene the isotopic gradient at site 289 in the equatorial pacific approaches the present day isotopic gradient about 4 5 an increase in 18oph pl during the miocene suggests that the latitudinal temperature gradient increased by about 6 c to a value of 12 c in the latest miocene between sites 289 equator and 281 subantarctic 13cb p and 13cph pl values are relatively constant through the early miocene but begin to increase during the middle miocene bottom water 13c values respond similarly at all sites but surface water 13c values exhibit different trends because higher latitude values begin to decrease this decrease perhaps suggests that phosphate concentrations may have increased due to increased upwelling as the circum antarctic circulation system evolved its present day characteristics the isotopic data compiled in this paper suggest that the southwest pacific was responding uniformly to some global or at least pacific wide control during the early miocene in the middle miocene the response became more complex as the low and high latitudes began to show independent trends the changes in the thermal vertical and latitudinal structure probably occurred in respons to the build up of the east antarctic ice sheet intensification of bottom water circulation and an increase in zonal circulation in surface waters in the southern hemisphere the changes in 13c vertical and latitudinal gradients are due to some complex interaction of sea level continental hypsometry climate and biological processes coupled with oceanic circulation changes a strong correlation between estimated sea level changes and 13c values suggests that transgressions and regressions play a critical role in controlling the flux of oxidized organic carbon enriched in12c from the continental shelves and epicontinental seas to the open ocean

pacific miocene carbon isotope stratigraphy using benthic foraminifera abstract seven miocene pacific ocean deep sea drilling project sites from four different water masses planktonic foraminiferal biogeographic regions have been correlated using 18 prominent carbon isotopic events defined in the benthic foraminiferal 13c records in dsdp site 289 the correlations are based on the assumption that there are global or at least pacific wide controls on the 13c of deep water hco3 each of the individual 13c records is correlated to site 289 based on the shape of the curves in a manner analogous to that used to correlate sea floor magnetic anomaly patterns the results of this correlation experiment confirm that planktonic foraminiferal biostratigraphy and carbon isotopic stratigraphy are consistent within the tropical surface water mass and precise to 100 000 years correlations between surface water masses suggest that the precision of foraminiferal biostratigraphy is on the average less than 200 000 years due to the lack of cosmopolitan marker species and diachronism of species occurrences carbon isotope stratigraphy used in conjunction with biostratigraphy has the potential to provide an easily utilized globally applicable correlation tool with an interregional precision of 100 000 years or better as more continuous and undisturbed deep sea sections become available as a result of the hydraulic piston coring program

post miocene disconformities and paleoceanography in the atlantic sector of the southern ocean abstract the magnetostratigraphy and biostratigraphy of 166 islas orcadas piston cores in the atlantic sector of the southern ocean reveal disconformities in the sedimentary record which are attributed to bottom current erosion the hiatus frequency as a function of water depth reveals both shallow erosion by circumpolar deep water cdw and deep erosion by antarctic bottom water aabw the post miocene history of erosion by both bottom currents is delineated by analysis of areal and temporal fluctuations of hiatus frequency erosion by cdw caused disconformities on the maud rise astrid ridge indian antarctic ridge scotia sea and islas orcadas rise the shallow disconformities increased in frequency and size from 4 0 to 1 0 ma with two periods of distinctly widespread disconformities from 5 5 to 4 5 ma and 2 5 to 1 5 ma after 1 0 ma the frequency and extent of the hiatuses decreased erosion by aabw caused disconformities in the weddell abyssal plain argentine basin and through a narrow conduit in the south sandwich basin downstream from the bullard fracture zone the deep disconformities increased in frequency and size from 4 5 to 5 0 ma 3 5 to 4 0 ma and from 1 0 to 2 5 ma after 1 5 ma the frequency and extent of hiatuses decreased fluctuations in hiatus frequency are consistent with results of a similar study in the southeast indian ocean and may be correlated with paleoceanographic events southern ocean cooling and possible re establishment of the west antarctic ice sheet and fringing ice shelves at 4 3 3 5 ma was accompanied by increased aabw and cdw activity the formation expansion of the northern hemisphere ice sheets at 2 5 3 0 ma resulted in a decrease in aabw velocity and was accompanied by increased cdw activity both deep and shallow bottom currents increased in velocity during the late matuyama chron 2 0 1 5 ma as a result of antarctic cooling after 1 0 ma however the frequency and extent of shallow and deep hiatuses was reduced and the modern extent of hiatuses is the lowest within the post miocene

geodetic determination of the kinematics of central greece with respect to europe implications for eastern mediterranean tectonics we use a new satellite laser ranging global positioning system slr gps solution at seven sites in anatolia and aegea to obtain a better definition of the extrusion motion of the anatolian aegean block with respect to europe we show that this motion can be described in a first approximation by a counterclockwise rotation which transfers most of the motion of arabia to anatolia we combine 78 displacement vectors obtained at common points of two triangulation nets measured in central greece in 1895 and 1975 with the slr gps measurements to compute the velocity field over greece with respect to europe these measurements indicate that central greece is a zone of extension between the anatolian aegean counterclockwise rotation to the south and the northern greece clockwise rotation to the north this extension is principally localized within the gulf of corinth to the east but is distributed to the west we then extrapolate this velocity field to the whole aegea and western anatolia using recently published gps results as well as the slr results the narrow dextral north anatolian fault which limits the velocity field to the north progressively gives way to a much wider boundary zone where extension becomes dominant we show that the collision between the mediterranean ridge and africa began 3 6 ma and we describe the modifications that this collision has produced on the kinematic pattern both in aegea and on the mediterranean ridge