validation of lateral fluid flow in an overpressured sand shale sequence during development of azeri chirag gunashli oil field and shah deniz gas field south caspian basin azerbaijan abstract data collected over the past 15 years from exploration appraisal and production in the offshore south caspian sea validates the previously developed model of lateral fluid flow from the overpressured basin center to the basin margins within the sandstone aquifers of the pliocene productive series specifically new data confirm the predictions that 1 although both sandstones and shales are overpressured sandstones are generally less overpressured than shales 2 there is a lateral regional gradient in sandstone overpressure decreasing from the basin center to the basin margin and 3 the impact on the pressure field from local features such as mud volcanoes or local faults is limited additional pressure data combined with regional seismic mapping suggests variations in lateral fluid flow in different stratigraphic intervals these data show that the less continuous sandstones of the upper and lower productive series are closer to the surrounding shale pressures as they are less well connected to the basin margin outlet whereas continuous sandstones in the middle productive series show the highest amount of lateral pressure transfer from the basin center and are therefore at lower pressures than the surrounding shales pressure data from development wells at the azer chirag gunashli oil field and the shah deniz gas condensate field reveal local variations in sandstone and shale overpressure resulting from the lateral pressure transfer affect traugott and heppard 1994 traugott 1996 swarbrick and osborne 1998 yardley and swarbrick 2000 across large high relief structures well connected sandstones transmit fluid pressures from the adjacent deep overpressured synclines into the shallower crest of the structure pressures in sandstones decrease updip along a hydrostatic gradient 0 433 psi ft the pressure gradient in the shales however will change according to the shale overpressure gradient in the south caspian basin the overpressure gradient in the shales varies between 0 6 and 0 9 psi ft therefore the relative overpressure between the sandstones and shales varies along structural dip there are a number of important implications to exploration appraisal and development because of large scale lateral fluid flow lateral fluid flow has consequences for the sealing capacity of sandstone reservoirs and the variable position of hydrocarbon to water contacts around a structural accumulation this requires each sandstone shale couplet be considered separately for pore pressure prediction basin scale 3d models were constructed to better understand the implications of basin scale fluid flow within and between individual reservoirs at each structure

surface circulation in the gulf of cadiz 2 inflow outflow coupling and the gulf of cadiz slope current 1 a study of the upper slope circulation in the gulf of cadiz is presented observations both original and revisited and realistic numerical modeling are used together to describe the structure and variability of the slope current system above the mediterranean outflow it is shown that the mediterranean inflow outflow coupling plays a stronger role than that of the atmospheric forcing in driving the upper slope currents the mediteranean outflow forces a surface open ocean current toward the strait of gibraltar part of it is entrained into the outflow and the remaining flows into the mediterranean this latter component does not suffice for the observed transport of the atlantic inflow into the mediterranean a secondary contribution to the inflow is therefore needed to complement the transport this contribution comes from a persistent equatorward current along the upper slope between cape st vincent and the strait of gibraltar the jet is 20 30 km wide and significant in the upper 200 m attaining subinertial maxima as much as 0 3 0 4 m s and monthly means in the order of 0 1 0 15 m s this current shows a strong variability at time scales in the order of 2 8 days and displays a significant vertical shear the response of the upper slope current to synoptic and seasonal atmospheric variability is analyzed very low correlation was detected at synoptic scales and the response of the system to seasonal forcing is unclear a cycle of intensification in june july and a decrease in winter is apparent in the measurements but is weak in the model results it is speculated that the cycle in the observed currents is associated with variability in the inflow outflow coupling system rather than driven by seasonally changing wind forcing

millennial scale fluctuations of the european ice sheet at the end of the last glacial and their potential impact on global climate abstract reconstructing northern hemisphere ice sheet oscillations and meltwater routing to the ocean is important to better understand the mechanisms behind abrupt climate changes to date research efforts have mainly focused on the north american laurentide ice sheets lis leaving the potential role of the european ice sheet eis and of the scandinavian ice sheet sis in particular largely unexplored using neodymium isotopes in detrital sediments deposited off the channel river we provide a continuous and well dated record for the evolution of the eis southern margin through the end of the last glacial period and during the deglaciation our results reveal that the evolution of eis margins was accompanied with substantial ice recession especially of the sis and simultaneous release of meltwater to the north atlantic these events occurred both in the course of the eis to its lgm position i e during heinrich stadial hs 3 and hs2 31 29 ka and 26 23 ka respectively and during the deglaciation i e at 22 ka 20 19 ka and from 18 2 0 2 to 16 7 0 2 ka that corresponds to the first part of hs1 the deglaciation was discontinuous in character and similar in timing to that of the southern lis margin with moderate ice sheet retreat from 22 5 0 2 ka in the baltic lowlands as soon as the northern summer insolation increase from 23 ka and an acceleration of the margin retreat thereafter from 20 ka importantly our results show that eis retreat events and release of meltwater to the north atlantic during the deglaciation coincide with amoc destabilisation and interhemispheric climate changes they thus suggest that the eis together with the lis could have played a critical role in the climatic reorganization that accompanied the last deglaciation finally our data suggest that meltwater discharges to the north atlantic produced by large scale recession of continental parts of northern hemisphere ice sheets during hs could have been a possible source for the oceanic perturbations i e amoc shutdown responsible for the marine based ice stream purge cycle or so called he s that punctuate the last glacial period

mapping the coal fire at centralia pa using thermal infrared imagery abstract thermal infrared imagery tir is being used to identify the location and intensity of heat released from mine fire vents in centralia pa recent tir images collected from 2007 2009 and 2010 have been combined with previously collected tir airborne images and other data from 1971 1980 1981 1982 1983 and 2002 2003 to produce a map that reveals the thermal history of the region additionally borehole data direct observations false color imagery and aerial photographs were used to locate fire location the compilation of these images into one map provides a history of the progressive coal fire movement since it s ignition in 1962 the fire which is thought to be located in the buck mountain coal bed no 5 at the base of the llewellyn formation middle pennsylvanian can be traced along the limbs of the eastwardly plunging locust mountain anticline it is moving west at a rate of less than 2 m yr which is down from estimates made in previous decades of nearly 20 23 m yr along one of the main fire fronts tir images reveal circular to semicircular patterns that represent zones of subsidence as the fire advances temperature readings from the tir imagery and ground measurements suggest a variable thermal history with a declining overall temperature today temperatures at gas vents generally do not exceed 65 c given the changes in the fire over the years it is suggested that the fire is decreasing in intensity and rate of movement as it moves deeper into the subsurface additionally it may be encountering subsurface chambers where the anthracite coal has been removed preliminary co co2 ratio measurements at gas vents are inconclusive but suggest oxygen is present in the subsurface a decrease in coal perhaps due to the shape of the coal bed or its absence due to mining is the primary limiting factor affecting the rate of movement and temperature of the fire this limited resource may cause the fire to smolder before naturally extinguishing early estimates predicted the fire would burn for a century or longer this study suggests that the fire may extinguish earlier than previously thought

dimensions of the atlantic mediterranean connection that caused the messinian salinity crisis abstract what kind of gateway is needed to cause a salinity crisis although several reconstructions of possible atlantic mediterranean gateways are proposed for the late miocene so far the gateway that must have existed before the desiccation of the mediterranean during the messinian is unknown this study uses the theory of hydraulic control combined with the effect of bottom friction in order to find out to first order the geometrical dimensions of the connection that existed during the primary lower gypsum stage 5 97 5 61 ma of the messinian salinity crisis 5 97 5 33 ma the connecting strait is assumed to behave in a similar way as existing straits such as the strait of gibraltar or the bosphorus a salinity crisis in an enclosed basin results when its connection to the open ocean is highly restricted a strait needs to be relatively shallow narrow and or long in order to result in exchange fluxes that are of around 25 or less of the exchange at the strait of gibraltar today considering the evaporite deposits together with global sea level variations we estimate the cross section of a strait responsible of the msc to have a minimum depth of 30 45 m and a maximum width of 0 7 2 km for lengths in the range up to 500 km these dimensions are consistent with only a few of the miocene corridors identified the calculations are extended to explore the implications for sedimentary structures on the corridor floor

a 550 000 year record of east asian monsoon rainfall from 10be in loess cosmogenic 10 be flux from the atmosphere is a proxy for rainfall using this proxy we derived a 550 000 year long record of east asian summer monsoon easm rainfall from chinese loess this record is forced at orbital precession frequencies with higher rainfall observed during northern hemisphere summer insolation maxima although this response is damped during cold interstadials the 10 be monsoon rainfall proxy is also highly correlated with global ice volume variations which differs from chinese cave 18 o which is only weakly correlated we argue that both easm intensity and chinese cave 18 o are not governed by high northern latitude insolation as suggested by others but rather by low latitude interhemispheric insolation gradients which may also strongly influence global ice volume via monsoon dynamics

palaeoclimatology and palaeohydrography of the glacial stages on celtic and armorican margins over the last 360000 yrs core md03 2692 was retrieved in a water depth of 4064 m on the celtic margin bay of biscay during the sedicar cruise onboard the rv marion dufresne ii it covers the last 360 ka in a total length of 39 m multidisciplinary analyses have been applied to this sequence with the aim of studying the palaeoclimatic and palaeoenvironmental signals of the last few climatic cycles the analyses undertaken include 1 non destructive logging with physical properties magnetic susceptibility sediment colour x ray radiography and measurement of the major elements by x ray fluorescence 2 analyses of planktonic and benthic foraminifera lithic grains and stable isotopic measurements oxygen and carbon we have focused on the longterm evolution of glacial stages with special attention to terminations and heinrich events the results obtained confirm the close correlation between deep sea sedimentation recorded on the celtic margin and changes in the terrestrial environment of the adjacent continent heinrich layers have been identified in mis 2 3 6 and 8 we note the occurrence of laminated facies within deglacial sequences deposited during termination i and mis 6 these facies are closely linked to disintegration phases of the british irish ice sheet bis the laminations contain lower ice rafted detritus ird concentrations than the equivalent heinrich layers and are linked to abrupt changes in sea surface palaeotemperatures we suggest that the laminations are formed by an annual cycle of meltwater and iceberg release from the disintegrating bis generating cascading plumes of dense turbid meltwater coeval with ird release d 2005 elsevier b v all rights reserved

middle to late pleistocene arctic paleoceanographic changes based on sedimentary records from mendeleev ridge and makarov basin abstract three sediment cores from the makarov basin and mendeleev ridge off the siberian margin were analyzed for a number of litho bio and magnetostratigraphic proxies correlation to previously studied arctic records from mendeleev to lomonosov ridges enables paleoceanographic reconstructions for the middle to late pleistocene estimated 0 8 ma on orbital time scales cyclic changes in lithology corroborated by multiple stratigraphic constraints were tuned to global climate variations based on the manganese content that increases during interglacials while calcium and zircon were used as proxies for the laurentide and eurasian ice sheet inputs the combined evaluation of glacial and interglacial proxy variabilities provides a coherent picture of the western arctic ocean development in the pleistocene we suggest that major cyclic changes were driven by summer processes such as sea ice retreat and enhanced biological production vs suppressed ice melt in warmer and colder summers respectively a potential link to low latitudes via atmospheric moisture and heat transport is indicated by similarities in the western arctic ocean and east asian monsoon records long term cooling is signified by biogenic proxies related to sea ice expansion over the western arctic ocean with step changes at mis 11 and 7 0 4 and 0 2 0 3 ma this transition also features better fossil preservation indicating less corrosive oxidative bottom waters probably resulting from a decrease in organic export production and or weakening of bottom water ventilation under perennial sea ice the latter was possibly enhanced by atmospheric cooling and increased meltwater fluxes with the growth of circum arctic ice sheets

a regional modeling study of the entraining mediterranean outflow 1 we have evaluated a regional scale simulation of the mediterranean outflow by comparison with field data obtained in the 1988 gulf of cadiz expedition our ocean model is based upon the hybrid coordinate ocean model hycom and includes the richardson number dependent entrainment parameterization of xu et al 2006 given realistic topography and sufficient resolution the model reproduces naturally the major observed features of the mediterranean outflow in the gulf of cadiz the downstream evolution of temperature salinity and velocity profiles the mean path and the spreading of the outflow plume and most importantly the localized strong entrainment that has been observed to occur just west of the strait of gibraltar as in all numerical solutions there is some sensitivity to horizontal and vertical resolution when the resolution is made coarser the simulated currents are less vigorous and there is consequently less entrainment our richardson number dependent entrainment parameterization is therefore not recommended for direct application in coarse resolution climate models we have used the high resolution regional model to investigate the response of the mediterranean outflow to a change in the freshwater balance over the mediterranean basin the results are found in close agreement with the marginal sea boundary condition msbc a more saline and dense mediterranean deep water generates a significantly greater volume transport of the mediterranean product water having only very slightly greater salinity

centennial scale variability of the british ice sheet implications for climate forcing and atlantic meridional overturning circulation during the last deglaciation evidence from paleoclimatic archives suggests that earth s climate experienced rapid temperature changes associated with pronounced interhemispheric asymmetry during the last glacial period explanations for these climate excursions have converged on nonlinear interactions between ice sheets and the ocean s thermohaline circulation but the driving mechanism remains to be identified here we use multidecadal marine records of faunal oxygen isotope and sediment proxies from the northeast atlantic proximal to the western margins of the last glacial british ice sheet bis to document the coupling between ice sheet dynamics ocean circulation and insolation changes the core data reveal successions of short lived 80 100 years high amplitude ice rafted debris ird events that were initiated up to 2000 years before the deposition of detrital carbonate during heinrich events he 1 and 2 progressive disintegration of the bis 19 16 kyr before present b p occurred in response to abrupt ocean climate warmings that impinged on the northeast atlantic during the early deglaciation peak ird deposition recurs at 180 220 year intervals plausibly involving repeated breakup of glacial tidewater margins and fringing marine ice shelves the early deglaciation culminated in a major meltwater pulse at 16 3 kyr b p followed by another discharge associated with he1 some 300 years after we conclude that temperature changes related to external forcing and marine heat transport caused a rapid response of the bis and possibly other margins of the eurasian ice sheet massive but short lived meltwater surges influenced the atlantic meridional overturning circulation thereby contributing to north atlantic climate variability and bipolar climatic asymmetry

rapid changes of glacial climate simulated in a coupled climate model abrupt changes in climate termed dansgaard oeschger and heinrich events have punctuated the last glacial period approximately 100 10 kyr ago but not the holocene the past 10 kyr here we use an intermediate complexity climate model to investigate the stability of glacial climate and we find that only one mode of atlantic ocean circulation is stable a cold mode with deep water formation in the atlantic ocean south of iceland however a warm circulation mode similar to the present day atlantic ocean is only marginally unstable and temporary transitions to this warm mode can easily be triggered this leads to abrupt warm events in the model which share many characteristics of the observed dansgaard oeschger events for a large freshwater input such as a large release of icebergs the model s deep water formation is temporarily switched off causing no strong cooling in greenland but warming in antarctica as is observed for heinrich events our stability analysis provides an explanation why glacial climate is much more variable than holocene climate

heterogeneities of in and out flows in the mediterranean sea abstract this paper develops a relatively new concept regarding the outflow of mediterranean waters mws through the strait of gibraltar while other papers assume that this outflow is composed of only two mws we previously found evidence from a re analysis of 1980s ctd profiles profiles collected with conductivity temperature depth probes during gibex the gibraltar experiment for two other mws we also analysed 2003 2008 time series from two ctds moored hydrochanges programme at the southern sill of camarinal and on the shelf of morocco and we developed a new concept east of the strait the four mws roughly lay one above the other but while progressing westward the associated isopycnals tilt up southward in the strait the mws are thus juxtaposed and they all mix with one of two atlantic water components the inflow acronym is thus aws and the outflow is horizontally heterogeneous west of the strait the outflow progressively becomes vertically heterogeneous again hence splitting into a series of superimposed veins we compared these ctd time series with one collected at the southern sill of espartel university of malaga ingres projects and hydrochanges programme fortunately the ctds moored at the two sills were generally along the same streamlines so that the mws evolution could be monitored we demonstrated the significance of mixing lines computed from two successive records and the possibility of linking two sets of data such as ctd profiles collected at different locations along the strait the outflow which does not show any clear seasonal variability before the strait strongly mixes with the inflow within the strait this is due mainly to the internal tide and because the inflow is seasonally variable leads to an outflow that displays marked seasonal and fortnightly variabilities both the outflow and the inflow also display marked spatial heterogeneity and both long term yearly and short term daily temporal variabilities before they mix thus accurately predicting the outflow characteristics in the atlantic ocean appears almost impossible herein we first propose a fully objective description of the aws and mws during two gibex campaigns where the aws and the mws do not markedly mix they are defined in terms of density and temperature ranges where a mw mixes with one of the aws down to the bottom the mixing line characteristics allow for that mw to be followed from one section to one downstream and for the validation of our concept while superimposed east of the strait the mws come to be juxtaposed within the strait before becoming superimposed again we also analysed additional ctd time series collected by the university of malaga on the south and north sides of the southern sill of espartel we demonstrate the following a even though the mws at the sill e and on the south side es were roughly the same the densest ones out flowed at es i e at depths shallower than at e b the mws on the north side en were very different from those at e and each mixed with different aws and c using the mixing lines computed from each time series the data recorded at e and es allow for the retrieval with good accuracy of those recorded at camarinal c which is not the case for the data recorded at en finally we emphasise how different the aws heterogeneities are from the mws heterogeneities the inflow is sucked into the mediterranean sea due to the water budget e p deficit there and it can be composed of any type of aw present west of the strait at any time and any specific location the outflow is a product of the mediterranean sea which is like a machine producing a series of mws that first circulate as alongslope density currents before entering the strait in a specific order and at specific locations consequently we attempt to schematise the aws mws mixing processes and our understanding of the outflow dynamics notwithstanding the difficulty of the working conditions within such a narrow strait having up to four mws outflowing side by side and mixing with two aws that have a heterogeneous and variable distribution clearly leads to spatial and temporal heterogeneities that are actually much larger than the ones that have been observed up to now from a relatively low number of ctd profiles and time series

land ocean changes on orbital and millennial time scales and the penultimate glaciation past glacials can be thought of as natural experiments in which variations in boundary conditions influenced the character of climate change however beyond the last glacial an integrated view of orbital and millennial scale changes and their relation to the record of glaciation has been lacking here we present a detailed record of variations in the land ocean system from the portuguese margin during the penultimate glacial and place it within the framework of ice volume changes with particular reference to european ice sheet dynamics the interaction of orbital and millennial scale variability divides the glacial into an early part with warmer and wetter overall conditions and prominent climate oscillations a transitional mid part and a late part with more subdued changes as the system entered a maximum glacial state the most extreme event occurred in the mid part and was associated with melting of the extensive european ice sheet and maximum discharge from the fleuve manche river this led to disruption of the meridional overturning circulation but not a major activation of the bipolar seesaw in addition to stadial duration magnitude of freshwater forcing and background climate the evidence also points to the influence of the location of freshwater discharges on the extent of interhemispheric heat transport

the effect of abundant precipitation on coal fire subsidence and its implications in centralia pa abstract abundant precipitation in 2011 resulted in the formation of nine new sinkholes and many other smaller subsidence features associated with a coal fire in centralia pa additionally fire vent temperatures decreased following prolonged precipitation associated with hurricane irene and tropical storm lee just over 185 cm of precipitation were measured for central pennsylvania which is nearly twice the annual amount and represents the wettest year on record precipitation infiltrated the soil and bedrock and interacted with hot bedrock in the subsurface location of the coal fire steam and other gases moved along the pillar structures through mined out coal areas and escaped at the surface exhaust vents along the fire front surface regolith and bedrock softened and with the increased water weight collapsed producing subsidence features as a result sinkholes up to 1 8 m deep and 26 m wide formed some of these features have coalesced forming even larger ellipse shaped troughs these subsidence features were mapped along the bottom middle and top splits of the buck mountain coal from the llewellyn formation middle to upper pennsylvanian aerial thermal infrared images tir reveal the sinkholes and fractures occur in alignment with three thermal anomalies associated with gas and heat release this may indicate that mined out coal beds act as conduits for heat circulation or that multiple beds of anthracite coal are on fire in the subsurface in centralia

was the younger dryas triggered by a flood draining of a huge lake into the northern atlantic may have triggered a cold period 12 900 years ago the route taken by the flood waters remains unknown

position of the polar front along the western iberian margin during key cold episodes of the last 45 ka 1 this paper documents the migration of the polar front pf over the iberian margin during some of the cold climatic extremes of the last 45 ka it is based on a compilation of robust and coherent paleohydrological proxies obtained from eleven cores distributed between 36 and 42 n planktonic 18o globigerina bulloides ice rafted detritus concentrations and the relative abundance of the polar foraminifera neogloboquadrina pachyderma sinistral were used to track the pf position these three data sets compared from core to core show a consistent evolution of the sea surface paleohydrology along the iberian margin over the last 45 ka we focused on five time slices representative of cold periods under distinct paleoenvironmental forcings the 8 2 ka event and the younger dryas two recent cold events occurring within high values of summer insolation heinrich events 1 and 4 reflecting major episodes of massive iceberg discharges into the north atlantic and the last glacial maximum typifying the highest ice volume accumulated in the northern hemisphere for each event we generated schematic maps mirroring past sea surface hydrological conditions the maps revealed that the polar front presence along the iberian margin was restricted to heinrich events the sea surface conditions during the last glacial maximum were close to those at present day except for the northern sites which briefly experienced subarctic conditions

reservoir compartmentalization get it before it gets you abstract this paper examines the impact of compartmentalization on oil recovery the importance of identifying it during field appraisal and methods to evaluate it using fluid data the impact on recovery factor is highlighted using a global database of oil field recovery factors as a function of reservoir complexity and compartmentalization and emphasized in two case studies the effect of compartmentalization on oil recovery demonstrates the benefit in characterizing compartmentalization correctly during appraisal so that the field can be developed in an optimal manner early characterization of field compartmentalization requires making maximum use of available fluid data during appraisal when interpreting fluid data to identify compartmentalization it is critical to take into account the different time scales for various fluid signals pressure contacts density composition to equilibrate and to be able to extrapolate to field production time scales this is essential to avoid false negatives compartments assumed absent due to homogeneous fluid properties when in fact fluids would have equilibrated even in the presence of compartments false positives where fluid differences are interpreted as evidence of compartments when in fact there has not been sufficient time for equilibration to occur and to resolve apparently conflicting data some fluid indicators are at equilibrium others are not rigorous simulation of fluid equilibration is a complex multiphase multidimensional process and is generally reserved for specialist in depth studies however order of magnitude evaluations can be made using analytical solutions in minutes allowing many what if scenarios to be considered and uncertainty to be assessed analytical solutions for estimating the time required for spatially varying fluid properties to revert to steady state distributions are reviewed all these mixing processes are shown to be diffusive in character an effective diffusion coefficient for each process can be calculated from the reservoir rock and fluid properties for an isothermal system the different time scales and distances for each fluid property variation to attain equilibrium can be compared on a single graph where the time elapsed since fluid perturbation is known analytical solutions can be used to estimate the degree of compartmentalization e g permeability of barriers these solutions lend themselves to the development of simple practical compartment assessment tools for industry practitioners

new insights into upper mow variability over the last 150kyr from iodp 339 site u1386 in the gulf of cadiz the upper mediterranean outflow water mow paleo oceanographic history in the gulf of cadiz is poorly constrained due to the lack of high resolution records that pre date the last glaciation existing proxy records concentrate on mow variability along the middle slope of the gulf of cadiz here we present a continuous high resolution benthic foraminifera 18o record from the upper mow core at iodp expedition 339 site u1386 in the gulf of cadiz of the past 150 000 years based on 18o grain size and zr al variability comparison of our results with existing mediterranean sea md01 2472 md95 2043 open ocean lr04 and gulf of cadiz md99 2339 records we have gathered new insights into the evolution of the upper mow core on glacial interglacial timescales the influence of the upper mow at site u1386 was strongest during mis 5 and mis 1 similar 18o variability can be seen in the levantine intermediate water liw originating from the levantine basin of the eastern mediterranean sea we found clear indication for a vertical shift of the mow from the upper to the middle slope of the gulf of cadiz during sea level lowstands coinciding with mis 4 and mis 2 but also during mis 3 additionally our results indicate an increased upper mow flow correlated with heinrich events 7 to 10 and the younger dryas and also inversely relate to precession forced monsoonal freshwater inputs into the eastern mediterranean in the context of sapropel formation we could not find conclusive evidence of the proposed mow shutdown in our data

timing of massive fleuve manche discharges over the last 350 kyr insights into the european ice sheet oscillations and the european drainage network from mis 10 to 2 continuous high resolution mass accumulation rates mar and x ray fluorescence xrf measurements from marine sediment records in the bay of biscay ne atlantic have allowed the determination of the timing and the amplitude of the fleuve manche channel river discharges during glacial stages mis 10 mis 8 mis 6 and mis 4 2 these results have yielded detailed insight into the middle and late pleistocene glaciations in europe and the drainage network of the western and central european rivers over the last 350 kyr this study provides clear evidence that the fleuve manche connected the southern north sea basin with the bay of biscay during each glacial period and reveals that fleuve manche activity during the glaciations mis 10 and mis 8 was significantly less than during mis 6 and mis 2 we correlate the significant fleuve manche activity detected during mis 6 and mis 2 with the extensive saalian drenthe substage and the weichselian glaciations respectively confirming that the major elsterian glaciation precedes the glacial mis 10 in detail massive fleuve manche discharges occurred at ca 155 ka mid mis 6 and during termination i while no significant discharges are found during termination ii it is assumed that a substantial retreat of the european ice sheet at ca 155 kyr followed by the formation of ice free conditions between the british isles and scandinavia until termination ii allowed meltwater to flow northwards through the north sea basin during the second part of the mis 6 we assume that this glacial pattern corresponds to the warthe substage glacial maximum therefore indicating that the data presented here equates to the drenthe and the warthe glacial advances at ca 175 160 ka and ca 150 140 ka respectively finally the correlation of our records with odp site 980 reveals that massive fleuve manche discharges related to partial or complete melting of the european ice masses were synchronous with strong decreases in both the rate of deep water formation and the strength of the atlantic thermohaline circulation fleuve manche discharges over the last 350 kyr probably participated with other meltwater sources in the collapse of the thermohaline circulation by freshening the northern atlantic surface water

ice sheet variability around the north atlantic ocean during the last deglaciation millennial scale variability in the flux of ice rafted detritus to north atlantic sediments during the last glacial period has been interpreted to reflect a climate forced increase in the discharge of icebergs from ice sheet margins surrounding the northern north atlantic ocean 1 but the relationship between ice sheet variability and climate change is not clear as both the sources of ice rafted detritus and the ice marginal processes are varied and complex 2 4 terrestrial records are helpful in unravelling this complexity because they can demonstrate the scale of ice sheet oscillations and whether the ice sheet or sector was advancing or retreating with respect to climate change here we constrain the age and anatomy of a prominent readvance of the british ice sheet in the northern irish sea region at similar to 14 14 c kyr bp similar to 16 4 calendar kyr bp the analysis indicates that the british ice sheet participated in an iceberg discharge episode known as heinrich event 1 comparison with other terrestrial and marine ice sheet records suggests that the dynamic collapse of the laurentide ice sheet beginning at 14 6 15 0 c 14 kyr bp1 4 similar to 17 2 17 6 calendar kyr bp 5 initiated varied responses from other ice sheet margins around the northern north atlantic region these observations support the argument that the release of icebergs and meltwater during heinrich event 1 disrupted the north atlantic thermohaline circulation 6 8 leading to a delay or reversal of deglaciation of the northern hemisphere and at least as far south as 40 degrees s for two to three thousand years 5 9 10 suggesting a climate forcing and response similar to that of the ensuing younger dryas cold snap 11 12

persistent monsoonal forcing of mediterranean outflow water dynamics during the late pleistocene the mode and vigor of the global oceanic circulation critically depend on the salinity of sub surface water masses advected to the loci of deep water formation within the atlantic meridional overturning circulation amoc an important supplier of high salinity waters is the mediterranean outflow water mow discharging into the north atlantic via the strait of gibraltar despite its importance for the north atlantic salinity budget the long term dynamics of mow production have remained poorly understood here we present high resolution records of bottom current velocity from three drill sites within the gulf of cadiz that document a persistent low latitude forcing of mow flow speed over the past 150 k y we demonstrate that the african monsoon is the predominant driver of orbital scale mow variability via its influence on the freshwater budget of the eastern mediterranean sea consequently mow formation fluctuates in concert with orbital precession overprinted by centennial scale oscillations of high latitude origin we further document that northern hemisphere summer insolation minima stimulate maximal injection of mow derived salt into the north atlantic likely strengthening the intermediate amoc branch the direct coupling of mow dynamics to low latitude climate forcing represents a hitherto neglected process for propagating sub tropical climate signals into the high northern latitudes

mediterranean climate and oceanography and the periodic development of anoxic events sapropels mediterranean sapropels are layers with elevated organic carbon concentrations that contrast with surrounding sediments which are organic poor sapropels occur quasi periodically in sedimentary sequences of the last 13 5 million years and exist both in the eastern and western mediterranean sub basins they have been the subject of extensive study based on records from both short conventional and long ocean drilling program sediment cores and from a wide variety of uplifted marine sediment sequences on the basin margins and islands previous syntheses in the 1990s and 2000s have discussed how the formation of sapropels is commonly ascribed to deep sea anoxia enhanced export productivity or a combination of these effects however a wealth of new evidence and insights has emerged during the past 1 2 decades based on traditional and novel proxy data as well as modelling which has revealed intriguing new aspects and nuances to the reconstructed conditions hence it is timely to present a new synthesis of current understanding of the processes behind the formation of sapropels which have over the past decade also become a matter of commercial interest in sub salt hydrocarbon exploration in this review we present a context of modern mediterranean climate and oceanography followed by an integrated assessment of the growing understanding of climatological and ocean circulation changes that were associated with sapropel deposition we find that sapropels predominantly formed during astronomically timed episodes when climatic and oceanographic conditions and ecological responses broadly preconditioned the basin for sapropel deposition there is strong correspondence with times of monsoon intensification fuelling runoff from north africa into the mediterranean sea while preconditioning due to sea level rise and regional precipitation and runoff may have contributed as well within these broad episodes of surface buoyancy gain and resultant decline in deep water ventilation specific deposition under dysoxic anoxic or even euxinic conditions occurred within a clearly dynamic system that was characterised by complex spatial and depth dependent patterns gradients with distinct temporal variability on at least decadal to centennial millennial timescales in the final section we evaluate the implications of different modes of deep water removal from silled basins to investigate why sapropels are more frequently and often more intensely developed in the eastern mediterranean than in the western mediterranean

millennial to centennial scale climate periodicities and forcing mechanisms in the westernmost mediterranean for the past 20 000 yr abstract cyclostratigraphic analysis conducted on a continuous high resolution marine record from the western most mediterranean reveals well identified paleoclimate cycles for the last 20 000 yr the detrital proxies used si al ti al zr al mg al k al rb al are related to different sediment transport mechanisms including eolian dust and fluvial runoff which involve fluctuations in the atmosphere hydrosphere systems these fluctuations are accompanied by changes in marine productivity supported by ba al and bottom water redox conditions cu al v al zn al fe al mn al u th spectral analysis conducted using the lomb scargle periodogram and the achieved significance level implemented with the permutation test allowed us to establish major periodicities at 1300 1515 2000 and 5000 yr and secondary peaks at 650 1087 and 3000 yr some of these cycles also agree with those previously described in the north atlantic ocean and circum mediterranean records the periodicities obtained at 2000 and 5000 yr support a global connection with records distributed at high mid and low latitudes associated with solar activity monsoonal regime and orbital forcing the 1300 and 1515 yr cycles appear to be linked with north atlantic climate variability and the african monsoon system thus the analyzed record provides evidence of climate cycles and plausible forcing mechanisms coupled with ocean atmosphere fluctuations

northern hemisphere storm tracks during the last glacial maximum in the pmip2 ocean atmosphere coupled models energetic study seasonal cycle precipitation mid latitude eddies are an important component of the climatic system due to their role in transporting heat moisture and momentum from the tropics to the poles and also for the precipitation associated with their fronts especially in winter we study northern hemisphere storm tracks at the last glacial maximum lgm and their influence on precipitation using ocean atmosphere general circulation model oagcm simulations from the second phase of the paleoclimate modelling intercomparison project pmip2 the difference with pmip1 results in terms of sea surface temperature forcing fundamental for storm track dynamics is large especially in the eastern north atlantic where sea ice extends less to the south in oagcms compared to atmospheric only gcms our analyses of the physics of the eddies are based on the equations of eddy energetics all models simulate a consistent southeastward shift of the north pacific storm track in winter related to a similar displacement of the jet stream partly forced by the eddies themselves precipitation anomalies are consistent with storm track changes with a southeastward displacement of the north pacific precipitation pattern the common features of north atlantic changes in the lgm simulations consist of a thinning of the storm track in its western part and an amplification of synoptic activity to the southeast in the region between the azores islands and the iberian peninsula which reflects on precipitation this southeastward extension is related to a similar displacement of the jet partly forced by the eddies in the western north atlantic the synoptic activity anomalies are at first order related to baroclinic generation term anomalies but the mean flow baroclinicity increase due to the presence of the laurentide ice sheet is partly balanced by a loss of eddy efficiency to convert energy from the mean flow moisture availability in this region is greatly reduced due to more advection of dry polar air by stationary waves leading to less synoptic scale latent heat release and hence less precipitation also in terms of seasonality the stormy season is shifted later in the year by a few days to a month depending on the season and the model considered this shift does not directly reflect on the first order seasonal cycle of precipitation which also depends on other mechanisms especially in summer

centennial to millennial scale ice ocean interactions in the subpolar northeast atlantic 18 41 kyr ago in order to monitor the evolution of the british irish ice sheet biis and its influence in surface ocean structure during marine isotopic stages mis 2 and 3 we have analyzed the sediments recovered in core md04 2829cq rosemary bank north rockall trough northeast atlantic dated between 41 and 18 ka b p ice rafted debris flux and composition 40ar 39ar ages of individual hornblende grains multispecies planktonic stable isotope records planktonic foraminifera assemblage data and faunal based sea surface temperatures ssts demonstrate a close interaction between biis dynamics and surface ocean structure and water properties in this region the core location lies beneath the north atlantic current nac and is ideal for monitoring the shifts in the position of its associated oceanic fronts as recorded by faunal changes these data reveal a succession of biis sourced iceberg calving events related to low sst usually synchronous with dramatic changes in the composition of the planktonic foraminifera assemblage and with variations in the stable isotope records of the taxa neogloboquadrina pachyderma sinistral coiling and globigerina bulloides the pacing of the calving events from typically dansgaard oeschger millennial timescales during late mis 3 to multicentennial cyclicity from 28 ka b p represents the build up of the biis and its growing instability toward heinrich event he 2 and the last glacial maximum our data confirm the strong coupling between biis instabilities and the temperature and salinity of surface waters in the adjacent northeast atlantic and demonstrate the biis s ability to modify the nac on its flow toward the nordic seas in contrast subsurface water masses were less affected except during the greenland stadials that contain hes when most intense water column reorganizations occurred simultaneously with the deposition of cream colored carbonate sourced from the laurentide ice sheet

oceanic heat pulses fueling moisture transport towards continental europe across the mid pleistocene transition abstract the mid pleistocene transition mpt approx 1 2 0 7 ma is characterized by growing northern hemisphere ice sheets and the shift from a 41 kyr to a 100 kyr glacial interglacial cyclicity concomitant to the growth of large ice sheets atmospheric and oceanic circulation pattern have changed one key feature of the north atlantic is the wind driven subtropical gyre a major provider of heat and moisture for continental europe here we investigate changes in the strength and spatial configuration of the subtropical gyre during the mpt and its impact on the continental moisture balance to reconstruct subtropical gyre dynamics we conducted paired 18o and mg ca analyses on the deep dwelling foraminifera globorotalia inflata from iberian margin site u1385 yielding thermocline temperature ttherm variability between 1400 and 500 ka at the eastern boundary of the subtropical gyre long term trends of ttherm at site u1385 oppose the north atlantic climatic evolution of progressively intensified glacials during the mpt particularly glacials mis 20 and 18 were marked by warm thermocline waters off iberia we infer that a southward shift of the sub polar front displaced the source region of thermocline waters within the subtropical gyre from high to mid latitudes in addition a strong mediterranean outflow water production during the mpt caused the advection of warm waters to iberia humid conditions during mis 20 and 18 in se europe indicate that atmospheric moisture derived from this warm water might have been advected deep into continental europe and contributed to enhanced growth of alpine glaciers

paleohydrogeology of the san joaquin basin california mass transport can have a significant effect on chemical diagenetic processes in sedimentary basins this paper presents results from the first part of a study that was designed to explore the role of an evolving hydrodynamic system in driving mass transport and chemical diagenesis using the san joaquin basin of california as a field area the authors use coupled hydrogeologic models to establish the paleohydrogeology thermal history and behavior of nonreactive solutes in the basin these models rely on extensive geological information and account for variable density fluid flow heat transport solute transport tectonic uplift sediment compaction and clay dehydration in the numerical simulations tectonic uplift and ocean regression led to large scale changes in fluid flow and composition by strengthening topography driven fluid flow and allowing deep influx of fresh ground water in the san joaquin basin sediment compaction due to rapid deposition created moderate overpressures leading to upward flow from depth the unusual distribution of salinity in the basin reflects influx of fresh ground water to depths of as much as 2 km and dilution of saline fluids by dehydration reactions at depths greater than approximately 2 5 km simulations projecting the future salinity of the basin show marine salinities persisting for moremore than 10 m y after ocean regression results also show a change from topography to compaction driven flow in the stevens sandstone at ca 5 ma that coincides with an observed change in the diagenetic sequence results of this investigation provide a framework for future hydrologic research exploring the link between fluid flow and diagenesis less

hydrographic conditions along the western iberian margin during marine isotope stage 2 the surface water hydrography along the western iberian margin as part of the north atlantic s eastern boundary upwelling system consists of a complex seasonally variable system of equatorward and poleward surface and subsurface currents and seasonal upwelling not much information exists to ascertain if the modern current and productivity patterns subsisted under glacial climate conditions such as during marine isotope stage mis 2 and how north atlantic meltwater events especially heinrich events affected them to help answer these questions we are combining stable isotope records of surface to subsurface dwelling planktonic foraminifer species with sea surface temperature and export productivity data for four cores distributed along the western and southwestern iberian margin md95 2040 md95 2041 md99 2336 and md99 2339 the records reveals that with the exception of the heinrich events and greenland stadial gs 4 hydrographic conditions along the western iberian margin were not much different from the present during the last glacial maximum lgm subtropical surface and subsurface waters penetrated poleward to at least 40 6 n site md95 2040 export productivity was in general high on the western margin during the lgm and low in the central gulf of cadiz in agreement with the modern situation during the heinrich events and gs 4 on the other hand productivity was high in the gulf of cadiz and suppressed in the upwelling regions along the western margin where a strong halocline inhibited upwelling heinrich event 1 had the strongest impact on the hydrography and productivity off iberia and was the only period when subarctic surface waters were recorded in the central gulf of cadiz south of lisbon 39 n the impact of the other heinrich events was diminished and not all of them led to a significant cooling in the surface waters thus climatic impacts of heinrich events highly varied with latitude and the prevailing hydrographic conditions in this region

looking back at the centralia coal fire a synopsis of its present status abstract centralia is in the anthracite region of eastern pennsylvania the town is part of the western middle field a large synclinorium in columbia and schuylkill counties residents of centralia set fire to a garbage dump in 1962 and in the process ignited the buck mountain coal bed fractured and moderately dipping strata at the site permitted air to circulate into the subsurface thereby promoting combustion and making it difficult to extinguish the centralia fire as the fire advanced during the 1960s 1970s and early 1980s it did so along four fronts however the fire appears to be advancing on only two fronts today the pennsylvania department of environmental protection is currently monitoring the fire fire associated with the first or cemetery front is advancing approximately 20 m year although attempts were made to fight the fire they were unsuccessful for logistical and monetary reasons most residents of centralia relocated with the assistance of funds approved by the u s congress and disbursed by the state of pennsylvania the inexperience of community leaders in working with state bureaucracy contributed to the difficulties of fighting the fire

a new radiocarbon chronology of baumkirchen stratotype for the onset of the upper wurmian in the alps the start of the upper wurmian in the alps was marked by massive fluvioglacial aggradation prior to the arrival of the central alpine glaciers in 1984 the subcommission on european quaternary stratigraphy defined the clay pit of baumkirchen in the foreland of the inn valley austria as the stratotype for the middle to upper wurmian boundary in the alps key for the selection of this site was its radiocarbon chronology which still ranks among the most important datasets of this time interval in the alps in this study we re sampled all available original plant specimens and established an accelerator mass spectrometry chronology which supersedes the published 40 year old chronology the new data show a much smaller scatter and yielded slightly older conventional radiocarbon dates clustering at ca 31 14c ka bp when calibrated using intcal13 the new data suggest that the sampled interval of 653 681 m in the clay pit was deposited 34 36 cal ka bp using two new radiocarbon dates of bone fragments found in the fluvioglacial gravel above the banded clays allows us to constrain the timing of the marked change from lacustrine to fluvioglacial sedimentation to ca 32 33 cal ka bp which suggests a possible link to the heinrich 3 event in the north atlantic copyright 2013 john wiley sons ltd

progressive reduction in ne atlantic intermediate water ventilation prior to heinrich events response to nw european ice sheet instabilities we present high resolution benthic 13c records from intermediate water depth core site md01 2461 1153 m water depth from the porcupine seabight ne atlantic spanning 43 to 8 kyr b p at an average proxy time step of 160 56 years this core provides information on the linkage between records from the portuguese margin and high latitude north atlantic basin allowing additional insights into north atlantic thermohaline circulation thc variability during millennial scale climatic events of the last glacial together these records document both discrete and progressive reductions in glacial north atlantic intermediate water gnaiw formation preceding heinrich h events 1 2 and 4 recorded through the apparent interchange of glacial northern and southern sourced intermediate water signatures along the european margin close coupling of nw european ice sheet nweis instability and gnaiw formation is observed through transient advances of scw along the european margin concurrent with pulses of ice rafted debris and meltwater release into the ne atlantic between 27 and 16 kyr b p when the nweis was at maximum extent and proximal to last glacial maximum convection zones in the open north atlantic it is such nweis instability and meltwater forcing that may have triggered reduced north atlantic thc prior to collapse of the laurentide ice sheet at h1 and h2 precursory reduction in gnaiw formation prior to h4 may also be inferred however limited nweis ice volume prior to h4 and convection occurring in the norwegian greenland sea require that if a meltwater trigger is invoked as appears to be the case at h1 and h2 the source of meltwater prior to h4 is elsewhere likely higher latitude ice sheets clarification of the sequencing and likely mechanisms of precursory decrease of the north atlantic thc support theories of h event initiation relating to ice shelf growth during cold periods associated with reduced north atlantic thc and subsequent ablation through subsurface warming and sea level rise associated with further reductions in meridional overturning

african monsoons an immediate climate response to orbital insolation the croll milankovitch astronomical theory of climate1 3 has received strong support from the evidence of a linear climatic forcing by obliquity and precession although nonlinearity had to be assumed for eccentricity4 5 moreover interglacials have appeared to be controlled by the orbital insolation6 although a phase shift of 6 000 5 000 yr is seen between an astronomical climate index and terrestrial climate indicators dominated by the northern ice sheet dynamics climate proxy data of low latitudes are less directly dependent on the ice sheets here it is shown that during the past 464 000 yr african monsoons signalled by the east mediterranean sapropels were heaviest always and only when a northern summer monsoon index computed from the orbital variation of insolation reached maximum values this occurred during all the interglacials but also twice during glacial periods thus tropical aridity is not the single climatic pattern of glacial periods an immediate terrestrial climate response to orbital variations of insolation is established

anatomy of heinrich layer 1 and its role in the last deglaciation this research used data acquired at the xrf core scanner lab at the marum center for marine environmental sciences university of bremen germany this research used samples provided by the international ocean discovery program iodp funding for this research was provided by the uk natural environmental research council nerc to hodell the nerc radiocarbon facility supported two radiocarbon dates and wally broecker generously supported the remainder with funding from the comer family foundation research by rodriguez tovar and dorador was financed by project cgl2015 66835 p b m acknowledges support from the csic ramon y cajal postdoctoral programme ryc 2013 14073 j f e would like to acknowledge funding under erc advanced grant 320750 nanopaleomagnetism

hydrodynamics and hydrocarbon trapping concepts pitfalls and insights from case studies abstract tilted contacts are observed in many oil and gas fields they are generally attributed to the effect of hydrodynamics hydrodynamic flow exists in almost all geological basin types of the wilson cycle from passive margins to foreland basins to mountain chains there are various geological processes driving regional hydrodynamics flow is regulated by permeability variations which are given by the geological framework the role of faults as partial permeability barriers may be a significant regulator for flow hydrodynamics is best recognized by using the principles of hydraulic head however hydraulic data must be carefully interpreted to avoid pitfalls such as transition zones where variable oil saturation may be falsely interpreted as tilted contacts in sedimentary basins we distinguish two different hydrodynamic settings where flow is either mainly gravity driven or centripetal or mainly compaction driven or centrifugal in both cases hydrodynamics can enhance hydrocarbon trapping gravity driven processes are particularly important in the arabian shield and north africa centrifugal and centripetal phenomena can co exist in the same basin e g mahakam delta or douala basin turbidites occur typically in centrifugal settings hydrodynamic concepts applied to petroleum exploration are not frequently used in industry despite being known for a long time they may however become increasingly important in conventional exploration as static plays are rapidly being drilled up and the remaining exploration potential of sedimentary basins is increasingly affected by stratigraphic and hydrodynamic trapping components

pleistocene sea surface temperature evolution early cooling delayed glacial intensification and implications for the mid pleistocene climate transition the mid pleistocene climate transition mpt is defined by the emergence of high amplitude quasi 100 ka glacial interglacial cycles from a prior regime of more subtle 41 ka cycles this change in periodicity and amplitude cannot be explained by a change in external astronomical forcing here we review and integrate published records of sea surface temperatures ssts to assess whether a common global expression of the mpt in the surface ocean can be recognized and examine our findings in light of mechanisms proposed to explain climate system reorganization across the mpt we show that glacial interglacial variability in ssts is superimposed upon a longer term cooling trend in oceanographic systems spanning the low to high latitudes regional variability exists in the timing of the onset and magnitude of cooling but in most cases a long term cooling trend begins or intensifies from 1 2 ma marine isotope stage mis 35 34 the sst cooling accompanies a long term trend towards higher global ice volume as recorded in benthic foraminifera 18o but predates a step like increase in 18o at 0 9 ma mis 24 22 that is argued to reflect expansion of continental ice sheets the strongest expression of pleistocene cooling is found during glacial stages whereas minor or negligible trends in interglacial temperatures are identified however pronounced cooling during both glacial and interglacial maxima is evident at 0 9 ma alongside the long term sst cooling trends quasi 100 ka cycles begin to emerge in both the sst and 18o records at 1 2 ma and become dominant with the expansion of the ice sheets at 0 9 ma we show that the intensified glacial stage cooling is accompanied by evolving pco2 abyssal ocean ventilation atmospheric circulation and or dust inputs to the southern ocean these changes in diverse environmental parameters suggest that glacial climate boundary conditions evolved across the mpt in turn these modified boundary conditions may have altered climate sensitivity to orbital forcing by placing pre existing ice sheets closer to some threshold of climate ice sheet response

drumlinised glaciofluvial and glaciolacustrine sediments on the smaland peneplain south sweden new information on the growth and decay history of the fennoscandian ice sheets during mis 3 abstract dug trenches in sediment cored drumlins on the smaland peneplain southern sweden occurring intermixed with rock cored drumlins revealed sedimentary successions and facies suggesting that the core sediments were primarily deposited proglacially both in glaciolacustrine settings as delta front and more distal deeper water sediments and as glaciofluvial braidplain sediments from the relationship between the drumlin sorted sediment cores and their surficial drape by a till carapace it is concluded that erosion was the main drumlin forming process here reshaping the original sediment morphology into streamlined landforms after which a more or less thick traction till was deposited over the eroded and or deformed ice bed interface drumlin formation probably took place during the last deglaciation over the area the drumlin core sediments in 14 excavated trenches were dated by optically stimulated luminescence osl most retrieved ages fall into two distinct groups both within marine isotope stage 3 c 60 30 ka when plotted as mean osl ages for each site all but two sites fall either into an older age group c 48 56 ka seven sites or into a younger age group c 28 38 ka five sites these age intervals correlate well with the suggested time spans for the ristinge and klintholm ice advances in denmark by ice flowing from the baltic basin westwards terminating in fan shaped patterns these interstadial ice advances in the southwestern sector of the fennoscandian ice sheet give rise to enigmatic questions on the physics and mechanics of ice sheet build up and decay especially as palaeoenvironmental data for northern fennoscandia suggest widespread ice free conditions within roughly the same time fame as the recorded ice advances in the south

late pleistocene loess of the lower rhine abstract from the lower rhine a compiled 25 7 m thick late pleistocene loess paleosol sequence is differentiated into five lithostratigraphic units the rheingau member mis 5 the keldach member weichselian early pleniglacial gs 21 1 18 mis 4 the ahrgau member weichselian middle pleniglacial mis 3 and the hesbaye and brabant members weichselian late pleniglacial mis 2 it correlates well with climate fluctuations known from ice cores and deep sea cores the sequence was continuously sampled by 335 samples it cuts through all essential layers and soils of the late pleistocene upper loess formation a continuous coarse silt index csi curve shows a maximum in the hesbaye member 31 24 ka b2k indicating the strongest wind conditions during the early late pleistocene further csi highs lie in the keldach and early brabant members csi lows are found the early and middle rheingau member gi 25 gi 22 the jackerath spenrath soils within the deeper keldach member gi 20 19 the early ahrgau member gi 17 gi 12 and finally in the elfgen soil gi 2 at the base of the brabant member the organic carbon culminates in the titz humus zone presumably at the end of gi 21 indicating scanty oxidation during the following cold lower weichselian pleniglacial period the garzweiler solcomplex forming a prevailing period of soil formation between 130 and 78 ka bp mis 5e a is considered as interglacial complex rhine interglacial complex continuing the style of the older interglacial complexes of mis 7 9 etc the ahr interstadial complex mis 3 is seen as immature complex of warm phases with fabric of the interglacial complexes author s suggestion the rhine interglacial complex covers mis 5e a and restricts the weichselian glacial to mis 4 through mis 2 this procedure follows the style of the older interglacial complexes

on the reasons for the formation and variability of the azores current abstract recent studies have shown that the formation of the well defined zonally oriented azores current may be the result of water mass transformation associated with the mediterranean outflow in the gulf of cadiz as the denser mediterranean water descends down the continental slope it entrains overlying north atlantic central water it is believed that the azores current then forms as part of the horizontal recirculating gyre generated through the plume mechanism in this study the authors further explore this hypothesis by performing a series of numerical experiments these experiments are based on a high resolution general circulation model that includes the mediterranean sea and that realistically simulates the water mass exchange through the strait of gibraltar and the transport and variability of the azores current the authors show that the divergence of the relative vorticity flux and the planetary vorticity flux associated with planetary waves are the main factors determining the variab

emplacement of giant mud volcanoes in the south caspian basin 3d seismic reflection imaging of their root zones exceptional quality 3d data for the largest mud volcano yet described provide the first detailed imaging of the plumbing architecture that connects a major volcanic edifice to its source layer at depth the volcano is in the south caspian basin and consists of an extruded submarine mud bicone 10 km wide and 1 4 km thick overlying an oval caldera 1 2 1 6 km in width and 0 5 km in depth the caldera narrows downwards into a zone of collapsed country rock forming a downward tapering cone 1 km in height the vertex of which is located close to the top of the mud source layer the imaged structural elements lead to an evolutionary model a narrow steep fluidization pipe fed the oldest pioneer cone we propose that numerous additional fluidization pipes injected the country rock forming a densely intruded cylindrical zone similar to gryphon swarms observed at outcrop onshore wall rock erosion and compaction of the intruded zone led to collapse of the downward tapering cone that linked upwards into ring faults that define the caldera margins later mud flowage focused on the conical sheared margins volumetric contraction of the extruded volcanic cone led to an unusual concentric system of minor outward facing normal faults this model has many similarities to syntheses of igneous maar diatreme caldera systems for which it may be analogous

deciphering bottom current velocity and paleoclimate signals from contourite deposits in the gulf of cadiz during the last 140 kyr an inorganic geochemical approach contourites in the gulf of cadiz gc preserve a unique archive of mediterranean outflow water mow variability over the past 5 3 ma in our study we investigate the potential of geochemical data obtained by xrf scanning to decipher bottom current processes and paleoclimatic evolution at two different sites drilled during iodp expedition 339 through contourites in the northern gc site u1387 which is bathed by the upper mow core and site u1389 located more proximal to the strait of gibraltar the lack of major downslope transport during the pleistocene makes both locations ideally suited for our study the results indicate that the zr al ratio representing the relative enrichment of heavy minerals zircon over less dense alumnosilicates under fast bottom current flow is the most useful indicator for a semiquantitative assessment of current velocity although most elements are biased by current related processes the bromine br record representing organic content preserves the most pristine climate signal rather independent of grain size changes hence br can be used for chronostratigraphy and site to site correlation in addition to stable isotope stratigraphy based on these findings we reconstructed mow variability for marine isotope stages mis 1 5 using the zr al ratio from site u1387 the results reveal abrupt millennial scale variations of mow strength during greenland stadials gs and interstadials gi with strong mow during gs and glacial terminations and a complex behavior during heinrich stadials millennial scale variability persisting during periods of poorly expressed gs gi cyclicities implies a strong internal oscillation of the mediterranean north atlantic climate system

abrupt regime shifts in the north atlantic atmospheric circulation over the last deglaciation we analyze modeling results of the north atlantic atmospheric winter circulation from a transient climate simulation over the last 21 000 years in agreement with previous studies we find that the midlatitude jet stream assumes a strong stable and zonal disposition so long as the north american ice sheets remain in their continent wide last glacial maximum lgm configuration however when the laurentide lis and cordilleran ice sheets separate ca 14 000 years ago the jet stream abruptly changes to a tilted circulation regime similar to modern the proposed explanation is that the dominant stationary wave source in the north atlantic sector changes from the lis to the cordilleran mountain range during the saddle collapse as long as the lis dominates the circulation retains the zonal lgm state characterized by prevalent stationary wave reflection in the subtropical north atlantic when the cordillera takes over the circulation acquires its modern disposition

meltwater and ice rafting in the southern norwegian sea between 20 and 40 calendar kyr b p implications for fennoscandian heinrich events 1 the timing of meltwater release in the southern norwegian sea in relation to millennial scale climate variability is studied from core md99 2283 based on down core analysis of stable oxygen and carbon isotopes calcium carbonate and ice rafted debris ird between 20 and 40 calendar cal kyr b p strong dansgaard oeschger cyclicity is expressed in increased carbonate content and reduced total organic carbon during warm interstadials and ird marking the end of cold stadials the planktonic 18o record of core md99 2283 compared to available isotopic records in the region confirms the existence of multisourced synchronized meltwater anomalies during heinrich h events 2 to 4 it was found that the sudden release of meltwater occurs near major ice streams and that no significant increase in ird was associated with the peaks of the meltwater events in the southern norwegian sea suggesting meltwater discharges from ice dammed lakes significant meltwater events not related to the h events were also observed between 33 and 35 cal kyr b p indicating that the release of meltwater is not necessarily connected with major cooling and enhanced ird delivery the simultaneous release of fresh water during h events in the nordic seas through icebergs and ice dammed lakes is thought to be the result of sea level increase the meltwater input to the nordic seas provides a significant additional contribution to global sea level rise associated with h3 and h4

mixing and spreading of the mediterranean outflow abstract hydrographic and current profiler data taken during the 1988 gulf of cadiz expedition have been analyzed to diagnose the mixing spreading and descent of the mediterranean outflow the s properties and the thickness and width of the outflow were similar to that seen in earlier surveys the transport of pure mediterranean water i e water with s 38 4 psu was estimated to be about 0 4 106 m3 s 1 which is lower than historical estimates most of which were indirect but comparable to other recent estimates made from direct velocity observations the outflow transport estimated at the west end of the strait of gibraltar was about 0 7 106 m3 s 1 of mixed water and the transport increased to about 1 9 106 m3 s 1 within the eastern gulf of cadiz this increase in transport occurred by entrainment of fresher north atlantic central water and the salinity anomaly of the outflow was consequently reduced the velocity weighted salinity decreased to 36 7 psu within 60 km of the strait and decre

paleoceanography of the atlantic mediterranean exchange overview and first quantitative assessment of climatic forcing 1 the mediterranean sea provides a major route for heat and freshwater loss from the north atlantic and thus is an important cause of the high density of atlantic waters in addition to the traditional view that loss of fresh water via the mediterranean enhances the general salinity of the north atlantic and the interior of the eastern north atlantic in particular it should be noted that mediterranean water outflowing at gibraltar is in fact cooler than compensating inflowing water the consequence is that the mediterranean is also a region of heat loss from the atlantic and contributes to its large scale cooling uniquely this system can be understood physically via the constraints placed on it by a single hydraulic structure the gibraltar exchange here we review the existing knowledge about the physical structure of the gibraltar exchange today and the evidential basis for arguments that it has been different in the past using a series of quantitative experiments we then test prevailing concepts regarding the potential causes of these past changes we find that 1 changes in the vertical position of the plume of mediterranean water in the atlantic are controlled by the vertical density structure of the atlantic 2 a prominent early holocene contourite gap within the gulf of cadiz is a response to reduced buoyancy loss in the eastern mediterranean during the time of sapropel 1 deposition 3 changes in buoyancy loss from the mediterranean during mis3 caused changes in the bottom velocity field in the gulf of cadiz but we note that the likely cause is reduced freshwater loss and not enhanced heat loss and 4 strong exchange at gibraltar during atlantic freshening phases implies that the gibraltar exchange provides a strong negative feedback to reduced atlantic meridional overturning given the very counterintuitive way in which the strait of gibraltar system behaves we recommend that without quantitative supporting work qualitative interpretations of how the system has responded to past external forcing are unlikely to be robust

timing of the last glacial maximum from observed sea level minima during the last glacial maximum ice sheets covered large areas in northern latitudes and global temperatures were significantly lower than today but few direct estimates exist of the volume of the ice sheets or the timing and rates of change during their advance and retreat here we analyze four distinct sediment facies in the shallow tectonically stable bonaparte gulf australia each of which is characteristic of a distinct range in sea level to estimate the maximum volume of land based ice during the last glaciation and the timing of the initial melting phase we use faunal assemblages and preservation status of the sediments to distinguish open marine shallow marine marginal marine and brackish conditions and estimate the timing and the mass of the ice sheets using radiocarbon dating and glacio hydroisostatic modelling our results indicate that from at least 22 000 to 19 000 calendar years before present land based ice volume was at its maximum exceeding today s grounded ice sheets by 52 5 x 10 exp 6 cu km a rapid decrease in ice volume by about 10 percent within a few hundred years terminated the last glacial maximum at 19 000 250 years

millennial scale climate oscillations recorded in the lower danube loess over the last glacial period abstract in this study we provide a correlative age model for last glacial loess at the rasova valea cu pietre site in the lower danube region based on the correlation of palaeoenvironmental proxies to independently dated palaeoclimate archives luminescence dating and independent age control provided by the geochemically confirmed presence of the campanian ignimbrite ci tephra the ci tephra originating in the phlegrean fields of southern italy has been dated elsewhere by 40ar 39ar to 39 40 ka bp and is frequently found in the lower danube loess as such the ci tephra represents a valuable temporal and stratigraphic maker across loess deposits in the region our age model facilitates high resolution correlation of palaeoenvironmental features observed at rasova to palaeoclimate archives in greenland and the black sea mediterranean area we observe semi cyclic behaviour of the frequency dependent magnetic susceptibility throughout the profile which we ascribe to millennial scale climate variability also observed elsewhere in the black sea region this is the first study to clearly identify millennial scale climate variability over the holocene and last glacial in the lower danube loess proxy variability in the holocene indicates continuous aeolian sedimentation through this epoch

hydrodynamic behavior of kangan gas capped deep confined aquifer in iran the kangan aquifer ka is located beneath the kangan gas reservoir kgr 2 885 m below the ground surface the gas reservoir formations are classified into nine non gas reservoir units and eight gas reservoir units based on the porosity water and gas saturation lithology and gas production potential using the logs of 36 production wells the gas reservoir units are composed of limestone and dolomite whereas the non gas reservoir units consist of compacted limestone and dolomite gypsum and shale the lithology of ka is the same as kgr with a total dissolved solid of 333 000 mg l the source of aquifer water is evaporated seawater the static pressure on the gas water contact gwc was 244 atm before gas production but it has continuously decreased during 15 years of gas production resulting in a 50 m uprising of the gwc and the expansion of ka water and intergranular water inside the gas reservoir the general flow direction of the ka is toward the northern coast of the persian gulf due to the migration of water to the overlying formations via a trust fault the ka is a gas capped deep confined aquifer gcdca with special characteristics differing from a shallow confined aquifer the main characteristics of a gcdca are unsaturated intergranular water below the confining layers no direct contact of the water table gwc with the confining layers no vertical flow via the cap rock permanent uprising of the gwc during gas production and permanent descend of gwc during water exploitation

response of iberian margin sediments to orbital and suborbital forcing over the past 420 ka here we report 420 kyr long records of sediment geochemical and color variations from the southwestern iberian margin we synchronized the iberian margin sediment record to antarctic ice cores and speleothem records on millennial time scales and investigated the phase responses relative to orbital forcing of multiple proxy records available from these cores iberian margin sediments contain strong precession power sediment redness a and 570 560 nm and the ratio of long chain alcohols to n alkanes c26oh c26oh c29 are highly coherent and in phase with precession redder layers and more oxidizing conditions low alcohol ratio occur near precession minima summer insolation maxima we suggest these proxies respond rapidly to low latitude insolation forcing by wind driven processes e g dust transport upwelling precipitation most iberian margin sediment parameters lag obliquity maxima by 7 8 ka indicating a consistent linear response to insolation forcing at obliquity frequencies driven mainly by high latitude processes although the lengths of the time series are short 420 ka for detecting 100 kyr eccentricity cycles the phase relationships support those obtained by shackleton antarctic temperature and the iberian margin alcohol ratios c26oh c26oh c29 lead eccentricity maxima by 6 kyr with lower ratios increased oxygenation occurring at eccentricity maxima co2 ch4 and iberian sst are nearly in phase with eccentricity and minimum ice volume as inferred from pacific 18oseawater lags eccentricity maxima by 10 kyr the phase relationships derived in this study continue to support a potential role of the earth s carbon cycle in contributing to the 100 kyr cycle

on the role of the azores current in the ventilation of the north atlantic ocean three high resolution ocean circulation models of the north atlantic differing chiefly in their description of the vertical coordinate are used to examine the ventilation of the north atlantic subtropical gyre all the models produce mode waters of realistic densities in the sargasso sea and the european basin but have azores currents of differing strengths which are categorised as strong of realistic transport intermediate and weak these differences have a critical impact upon the ventilation of the gyre most importantly the strong azores current forms an effective barrier to the southward ventilation of eastern north atlantic water from the northern european basin initially driving it southwestwards into the central gyre before turning it back eastwards again in a general cyclonic circulation north of the current the intermediate and weak azores currents instead allow the southward ventilation of this water mass near the european and african coasts the situation in nature appears to be intermediate between these two cases with the azores current acting as a partial block the study also raises the possibility of the azores current forming an advective connection between the sargasso sea mode waters in the western basin and modes of similar densities found in the eastern basin on the southern side of the current although there are high levels of variability in the extent of these lighter modes in the eastern basin in nature this postulate is supported by a number of observational studies in addition the present study also provides some support for the local production of madeira mode water in the eastern basin associated with retroflecting current branches on the southern side of the azores current overall the azores current is therefore likely to have a critical impact upon the ventilation of the subtropical gyre over a large area rather than just locally affecting the potential vorticity and density structure of the upper ocean between subtropical latitudes and the northern european basin the study also contributes to an ongoing community effort to assess the realism of our current generation of ocean models

monsoonal forcing of european ice sheet dynamics during the late quaternary the dynamics of northern hemisphere ice sheets during late quaternary glacials have yet been dominantly examined from a laurentide ice sheet perspective which helped shaping the idea of moisture starved glacials and small scale ice volume variability however the waxing and waning of the european ice sheet eis casts doubt on this perception understanding eis dynamics under glacial boundary conditions is crucial because its meltwater pulses influence global climate by weakening deepwater formation in the north atlantic ocean here we show that the advection of subtropical water toward the continental margin of western europe lead to enhanced moisture availability on the continent and fueled the growth of eis lobes during glacials this warm water pooling was caused by monsoonally paced enhanced mediterranean outflow water mow entrainment that dragged subtropical surface waters toward the european margin this mechanism presents a yet unrecognized marine terrestrial pathway that allows low latitude forcing to shape high latitude glaciations