mineralogical responses of siliciclastic carbonate cemented reservoirs to steamflood enhanced oil recovery abstract rock fluid interactions induced by steamflood enhanced oil recovery were investigated in laboratory simulations to determine the geochemical reactions and the effects of these reactions on reservoir permeability flow through laboratory experiments using mixtures of quartz kaolinite and siderite were performed in a high temperature high pressure permeameter at a confining pressure of 1200 psi and temperatures between 150 250 c fluid compositions used in the experiments simulated the vapor and residual liquid phases encountered in steamflood operations as well as an intermediate fluid composition effects of fluid ph fluid salinity and flow rate were systematically investigated in the experiments the most extensive fluid rock interactions were observed in the vapor phase simulations and high temperature high ph condition simulations smectite chlorite illite mixed layer clays greenalite analcime and k feldspar were all identified as products of rock fluid interaction in the experiments smectite was the dominant authigenic phase to reduce permeability in the experiments the experiments showed that the formation of smectite in fe rich environments does not require a clay precursor smectite is likely the most damaging neoformed mineral to reservoir permeability under different hydrogeochemical conditions for several reasons including 1 its relatively high surface area including microporosity in the honeycomb texture 2 its propensity to migrate and block pore throats during fluid flow in porous media because of its small particle size pore lining texture and electrochemical surface properties and 3 the wide range of stability of smectites in the physical and chemical conditions that exist in reservoirs undergoing steamflood eor the rapid precipitation of authigenic minerals in these experiments suggests that the period required for fluids and rock to reach equilibrium in diagenetic environments are extremely short when considering geologic time scales the armoring of pre existing minerals by grain coating authigenic minerals appears to result in the attainment of local equilibrium conditions prior to when one would predict assuming a continuous supply of reactant minerals was present

salinity change in the subtropical atlantic secular increase and teleconnections to the north atlantic oscillation 1 recent studies comparing shipboard data between the 1950 s and the 1990 s have shown significant heterogeneous adjustments of the temperature salinity structure of the n atlantic ocean here we present proxy records of temperature and salinity from aragonite sclerosponge skeletons extending existing records of the salinity maximum waters smw of the n atlantic back to 1890 these proxy records show secular temperature increases of 1 6 2 0 c higher than published global averages and salinity increases of 0 35 0 5 psu smaller than short term secular trends recently measured salinity reconstructions vary more significantly on the decadal scale showing changes that are related to low frequency variations of the north atlantic oscillation nao on both secular and decadal time scales the records indicate significant thermohaline changes in the smw either via forcing at the surface or increasing depths of density surfaces in the bahamas

interpentadal variability of temperature and salinity at intermediate depths of the north atlantic ocean 1970 1974 versus 1955 1959 we have composited historical hydrographic observations for the world ocean for two pentads 1955 1959 and 1970 1974 and have objectively analyzed these data for the purpose of studying the temporal variability of temperature and salinity in the north atlantic ocean the subtropical gyre 500 1300 m of the north atlantic was colder and fresher during 1970 1974 compared to 1955 1959 the relatively large changes in temperature and salinity on constant depth surfaces in the subtropical gyre were due to upward displacements of isopycnal surfaces at intermediate depths the eastern portion of the subarctic gyre was also colder and fresher during the 1970 1974 pentad in contrast the western portion of the subarctic gyre exhibited higher temperatures and salinities during 1970 1974 compared to 1955 1959 characteristic differences in temperature and salinity for both gyres were 0 5 c and 0 025 respectively analysis of changes in potential vorticity indicates that in the subtropical gyre potential vorticity increased in all density layers above the 26 5 surface suggesting that convection in this region may have been shallower in 1970 1974 compared to 1955 1959 below the 26 5 surface potential vorticity decreased through the 27 3 surface indicating that deeper than normal convection may have formed the water masses in these layers at 250 m depth relatively large changes in temperature and salinity occurred along the line of maximum climatological mixed layer depth that extends northeast to southwest across the north atlantic ocean

apparent changes in the climatic state of the deep north atlantic ocean determination of any long term changes in the large scale characteristics of the deep ocean circulation would be an important clue in understanding the climatic interactions of the ocean and atmosphere in the summer of 1981 the rv atlantis ii reoccupied two transatlantic sections at nominal latitudes of 24 30 n and 36 16 n with a conductivity temperature depth instrument ctd one purpose of the work was to make a comparison with previous surveys conducted during the international geophysical year igy 1 when sections were obtained in october 1957 and april may 1959 we report here that significant warming occurred in an ocean wide band from 700 m to 3 000 m with a maximum temperature difference of 0 2 c these changes are sufficient to expand the water column by several centimetres the historical temperature salinity curve was apparently unchanged interannual changes in local water mass characteristics have been proposed previously2 3 perhaps it would be most surprising if no changes were seen to occur what remains obscure is the significance of these changes and the extent to which they represent long term climate trends or merely the minor and random fluctuations to be expected in any complex fluid system

iceberg trajectory modeling and meltwater injection in the southern ocean this is the first large scale modeling study of iceberg trajectories and melt rates in the southern ocean an iceberg model was seeded with climatological iceberg calving rates based on a calculation of the net surface accumulation from each snow catchment area on the antarctic continent in most areas modeled trajectories show good agreement with observed patterns of iceberg motion though discrepencies in the weddell sea have highlighted problems in the ocean general circulation model output used to force the iceberg model the coriolis force is found to be important in keeping bergs entrained in the coastal current around antarctica and topographic features are important in causing bergs to depart from the coastal regions the modeled geographic distribution of iceberg meltwater joining the ocean has been calculated and is found in many near coastal regions to be comparable in magnitude to the excess of precipitation over evaporation p e

the long term hydrographic record at bermuda abstract a long by oceanographic standards time series of hydrographic observations at bermuda was begun in 1954 and continues to the present analysis of this dataset has shown the temperature and salinity variations on interannual timescales to be largely independent in the surface layer 0 200 dbar where integral timescales for salinity are 50 longer than for temperature and surface salinity changes are correlated with decadal changes in the 18 c water production temperature salinity anomalies are highly correlated in the thermocline where the interannual variability at that level is accountable to either vertical oscillations of the thermocline with amplitudes of 50 m or meridional oscillations of the horizontal gradient set up at the southern edge of the recirculation gyre of 300 kim salinity changes in the deepest layer observed at bermuda station s 1500 2500 dbar are uncorrelated with temperature masked by measurement errors in the early years of the time series inclusion of earlier

using a cfc effective age to estimate propagation and storage of climate anomalies in the deep western north atlantic ocean 1 1990s chlorofluorocarbon cfc observations are used to estimate an effective age of 20 years for north atlantic deep water nadw at the equator the effective age is found by subtracting a relic age from pcfc 11 age the effective age is several to 10 years younger at the equator than other methods from the effective age equatorward effective spreading rates of 1 2 cm s are found which are similar for the nadw components effective spreading rates take into account recirculation gyres along equator flow and mixing which slow spreading of climate anomalies from the north atlantic to the southern hemisphere the difference between direct velocities and tracer effective spreading rates suggests that the buffering effect due to storage in the western north atlantic and equatorial region is about 20 years even so warming and freshening due to greenhouse gases will be first felt in the deep waters of the western north atlantic

identification of surface wind patterns over the ross ice shelf antarctica using self organizing maps abstractthe interaction of synoptic and mesoscale circulations with the steep topography surrounding the ross ice shelf antarctica greatly influences the wind patterns in the region of the ross ice shelf the topography provides forcing for features such as katabatic winds barrier winds and barrier wind corner jets the combination of topographic forcing and synoptic and mesoscale forcing from cyclones that traverse the ross ice shelf sector create a region of strong but varying winds this paper identifies the dominant surface wind patterns over the ross ice shelf using output from the weather research and forecasting model run within the antarctic mesoscale prediction system and the method of self organizing maps som the dataset has 15 km grid spacing and is the first study to identify the dominant surface wind patterns using data at this resolution the analysis shows that the ross ice shelf airstream a dominant stream of air flowing northward from the interior of the continent over the western

large icebergs characteristics from altimeter waveforms analysis large uncertainties exist on the volume of ice transported by the southern ocean large icebergs a key parameter for climate studies because of the paucity of information especially on iceberg thickness using icebergs tracks from the national ice center nic and brigham young university byu databases to select altimeter data over icebergs and a method of analysis of altimeter waveforms a database of 5366 icebergs freeboard elevation length and backscatter covering the 2002 2012 period has been created the database is analyzed in terms of distributions of freeboard length and backscatter showing differences as a function of the iceberg s quadrant of origin the database allows to analyze the temporal evolution of icebergs and to estimate a melt rate of 35 39 m yr 1 neglecting the firn compaction the total daily volume of ice estimated by combining the nic and altimeter sizes and the altimeter freeboards regularly decreases from 2 2 104km3 in 2002 to 0 9 104km3 in 2012 during this decade the total loss of ice 1800 km3 yr 1 is twice as large as than the input 960 km3 yr 1 showing that the system is out of equilibrium after a very large input of ice between 1997 and 2002 breaking into small icebergs represents 80 1500 km3 yr 1 of the total ice loss while basal melting is only 18 320 km3 yr 1 small icebergs are thus the major vector of freshwater input in the southern ocean

interpentadal variability of temperature and salinity in the deep north atlantic 1970 1974 versus 1955 1959 historical hydrographic observations have been composited and objectively analyzed for the north atlantic ocean for two pentads 1955 59 and 1970 74 for the purpose of studying the temporal variability of the thermohaline structure of the deep north atlantic ocean statistically significant differences between the two pentads are found in the deep ocean at 1750 m depth most of the north atlantic increased in temperature approximately 0 1 c and salinity 0 025 from the earlier to the later period an exception to this was a region in the eastern atlantic between 33 n and 50 n where a cooling 0 1 c and freshening 0 025 occurred changes at other depths as evidenced by difference fields of temperature along 24 5 n and 36 5 n are in agreement with differences found by roemmich and wunsch 1984 who described changes at these latitudes between sections taken in the late 1950 s and sections taken in 1981

changes across 66 w the caribbean sea and the western boundaries of the north atlantic subtropical gyre abstract a world ocean circulation experiment hydrographic program along with a global repeat hydrography program occupied sections along 66 w in the north west atlantic ocean in 2003 and 2012 hydrographic variables tracers and ladcp measurements were collected in situ this section together with the north american and south american coasts create a closed volume excluding any flow through the panama canal combining mass silica and ladcp information with constraints in an inverse box model we obtain a strong eastward flow of the gulf stream 100 1 4 6 sv in 2003 and 123 8 4 4 sv in 2012 and westward flows of the caribbean current 24 4 1 0 sv in 2003 and 24 2 1 1 sv in 2012 and deep western boundary current dwbc the dwbc carries the ventilated waters of the labrador sea and the nordic seas comparing the results of 2003 and 2012 an insignificant reduction is observed in the dwbc transport 17 3 2 9 sv and 15 0 2 5 sv for 2003 and 2012 respectively the net heat fluxes do not show major changes through the section during both cruises 0 23 0 08 pw in 2003 and 0 21 0 12 pw in 2012 in contrast freshwater fluxes present positive values in the dry season 0 24 sv in spring 2012 and negative values in the wet season 0 32 sv in fall 2003 the difference between both cruises may be due to seasonal variability in the area

the arrival of a new labrador sea water signal in the tropical atlantic in 1996 1 we describe results inferred from the tracking in the tropical atlantic of cfc signals linked to the intensification of convection processes in the labrador sea since 1988 cfc and hydrology series 1993 1997 off french guiana 7 n have been investigated in order to analyse lsw characteristics and their variability a dramatic increase of the cfc concentrations below 2000 m at the level of the classical lsw has been observed in april 1996 using cfc and salinity data the comparison of the 1993 1997 series at 7 n with a 1989 1999 series at 35 w indicates that the sporadic 1996 event has been followed in the equatorial atlantic in the late 90s by the arrival of a more continuous newly ventilated lsw flow this study evaluates a transit time from the labrador basin to the tropics of less than one decade in agreement with direct current measurements

carbonate equilibria and ph buffering by organic acids response to changes in pco2 abstract organic acid anions such as acetate a natural product of the thermal breakdown of kerogen may buffer the ph of natural formation waters the extent of ph buffering by acetate should determine whether an increase in the partial pressure of carbon dioxide p co 2 will lead to calcite dissolution porosity enhancement or calcite precipitation porosity destruction successful prediction of porosity therefore requires a quantitative understanding of this process this paper presents computer simulations of the response of the acetic acid carbonate system to changes in p co 2 for typical reservoir fluid compositions and temperatures the effects of variations in temperature ionic strength initial ca 2 concentration and the magnitude of the change in p co 2 were investigated natural formation waters from cenozoic reservoirs in the gulf coast basin and california show maximum organic acid concentrations at 100 20 c at 100 c the simulations show that for concentrations of acetic acid up to 0 06 m 3600 mg l 1 increases in the p co 2 of initially calcite saturated solutions will promote calcite undersaturation at higher temperatures equivalent buffering responses occur at lower acetic acid concentrations but acetic acid concentrations in natural formation waters also decrease rapidly with increasing temperature since present day concentrations of acetic acid in formation waters from cenozoic reservoirs rarely exceed 0 06 m increases in p co 2 will generally promote calcite dissolution by these waters in the gulf coast basin variation in organic acid concentrations as a function of reservoir age suggests that reductions in dissolved organic acid concentrations over geologic time have been relatively small it can be concluded therefore that at any point in the histories of these reservoirs an increase in p co 2 would have promoted calcite dissolution despite the effects of ph buffering by acetate since increases in p co 2 will in most cenozoic basins promote calcite dissolution knowledge of the location and timing of co 2 production in the subsurface can more easily be applied to the prediction of calcite cementation and dissolution

decadal changes in water mass characteristics at 24 n in the subtropical north atlantic ocean abstract three transatlantic hydrographic sections across 24 n through the center of the subtropical gyre are analyzed for evidence of decadal changes in water mass characteristics in the main thermocline there has been a steady increase in salinity from 1957 to 1981 to 1992 the salinity at a given potential temperature between 12 c and 17 c has increased at a nearly constant rate of 0 010 per decade at constant potential density salinity and temperature both increased at rates of 0 018 per decade and 0 065 c per decade in the intermediate waters between 800 and 1500 dbar salinity has increased as well on average by as much as 0 025 from 1981 to 1992 either on constant potential temperature or constant density surfaces these changes cannot be due to vertical heaving of a constant water mass structure and they cannot be easily explained in terms of horizontal shifts in the subtropical gyre water mass structure throughout the water column down to 2000 dbar and across the zonal extent of the 24 n

anthropogenic carbon accumulation in the subtropical north atlantic 1 recent data suggest the accumulation of anthropogenic carbon dioxide canth in the subtropical north atlantic is not occurring at a steady rate throughout the water column carbon measurements from three transatlantic cruises along 24 5 n in 1992 1998 and 2004 were investigated for changes in canth using both a back calculation shortcut technique and extended multiple linear regression for three time periods 1992 1998 1998 2004 and 1992 2004 we observed spatial and vertical changes in canth storage along with a general increase in total concentration in the surface layers total dissolved inorganic carbon tco2 and canth concentrations increased in line with atmospheric co2 levels tco2 8 8 0 5 mol kg 1 for 1992 1998 and 8 6 0 5 mol kg 1 for 1998 2004 and canth 8 0 0 2 mol kg 1 for 1992 1998 and 6 8 0 3 mol kg 1 for 1998 2004 in deeper waters canth was significantly different than zero for all depths above 5000 dbar between 1992 and 2004 while on a subdecadal timescale significant variability was observed for canth at a depth range of 800 1000 dbar evidence is presented for the arrival at 24 5 n at depth of freshly ventilated labrador sea water from the subpolar north atlantic between 1992 and 1998 as well as consistent smaller canth signals alongside the mid atlantic ridge this is in addition to low level stable increases identified in the deep eastern basin between 1992 and 2004 the first time that canth has been detected and confirmed by new measurements of carbon tetrachloride and cfc 11 from 2004 these results highlight the importance of the subtropics as a site for long term canth storage away from the surface

climatic warming of atlantic intermediate waters abstract interdecadal temperature variability of the atlantic ocean is investigated by differencing hydrographic sections taken from the 1920s through the 1990s a comprehensive reanalysis of north atlantic sections and the inclusion of south atlantic sections show that warming seen previously in the north atlantic extends to the south atlantic the largest statistically significant changes occur on pressure surfaces between 1000 and 2000 decibars db over this pressure range and for latitudes between 32 s and 36 n temperatures have warmed by 0 5 c century 1 at 48 n a cooling of 3 c century 1 occurred between the 1950s and 1980s these isobaric temperature trends are decomposed into ones along surfaces of constant neutral density and ones due to the vertical movement of neutral surfaces the two components are associated with different processes in the southern north atlantic 8 36 n the subthermocline warming between the 1950s and 1980s appears to be due primarily to downward displacements of n

a simulation of small to giant antarctic iceberg evolution differential impact on climatology estimates we present a simulation of antarctic iceberg drift and melting that includes small medium sized and giant tabular icebergs with a realistic size distribution for the first time an iceberg model is initialized with a set of nearly 7000 observed iceberg positions and sizes around antarctica the study highlights the necessity to account for larger and giant icebergs in order to obtain accurate melt climatologies we simulate drift and lateral melt using iceberg draft averaged ocean currents temperature and salinity a new basal melting scheme originally applied in ice shelf melting studies uses in situ temperature salinity and relative velocities at an iceberg s bottom climatology estimates of antarctic iceberg melting based on simulations of small 2 2 km small to medium sized 10 km and small to giant icebergs including icebergs 10 km exhibit differential characteristics successive inclusion of larger icebergs leads to a reduced seasonality of the iceberg meltwater flux and a shift of the mass input to the area north of 58 s while less meltwater is released into the coastal areas this suggests that estimates of meltwater input solely based on the simulation of small icebergs introduce a systematic meridional bias they underestimate the northward mass transport and are thus closer to the rather crude treatment of iceberg melting as coastal runoff in models without an interactive iceberg model future ocean simulations will benefit from the improved meridional distribution of iceberg melt especially in climate change scenarios where the impact of iceberg melt is likely to increase due to increased calving from the antarctic ice sheet

winter observations of iceberg frequencies and sizes in the south atlantic ocean the numbers and apparent sizes of icebergs in the south atlantic ocean in midwinter were measured by radar and visually from f s polarstern during the 1986 winter weddell sea project cruise results show that in a heavy sea sea state 7 8 icebergs have to be at least 115 m in diameter to be detected at all and that detectability falls off severely for all bergs at ranges exceeding 8 n mi 15 km that most bergs had diameters of less than 1 km with a preferred size of 400 500 m and that a high density of icebergs in the latitude band 53 56 s at longitude 19 30 w contrasted with a virtual absence of bergs in the same latitude band at longitude 1 9 e the latter effect is ascribed to melt and wave induced deterioration causing the disappearance of this iceberg population between the two sets of longitudes

impact of iceberg c 19 on ross sea primary production 1 for the second time in 26 months a large iceberg c 19 calved off the face of the ross ice shelf rather than breaking up as did its predecessor b 15 the iceberg c 19 remained largely intact eventually stopping temporarily near pennell bank before moving out of the southwestern ross sea the presence of c 19 restricted advection of sea ice out of the region resulting in unusually high sea ice cover during the spring and summer consequently phytoplankton blooms in the region were diminished dramatically and primary production was reduced by over 90 relative to normal years calving events over the last two decades indicate that reduced primary productivity may be a typical consequence of large icebergs that drift through the southwestern ross sea during spring and summer

distribution of icebergs in the atlantic and indian ocean sectors of the antarctic region and its possible links with enso 1 the spatial distribution and multiyear variability of iceberg concentration in the atlantic and indian ocean sectors of the antarctic region have been studied using ship borne observations of iceberg occurrence the collected dataset includes more than 40 000 reports predominantly from russian and australian research vessels made over the last 36 years 1970 2005 the analysis of the data has revealed a gradual decrease in the iceberg concentration away from the coast of antarctica and a substantial variation along the coast line large concentration of icebergs was found in the weddell sea and north east of the antarctic peninsula several regions in the atlantic and indian ocean sector of antarctica have been identified where yearly anomalies of the iceberg occurrence exhibit a noticeable correlation with el ni o southern oscillation enso events the strongest enso effect was observed in the region east of drake passage where the iceberg concentration increased by about 50 during years of the negative southern oscillation index soi phase the change in the iceberg amount is explained by an increased iceberg drift into this region from the southern part of weddell sea and from pacific ocean the latter is caused by anomalous surface pressure high and associated anti clockwise circulation around the pressure anomaly developing in the south eastern part of pacific ocean during the negative phase of enso

burial dolomitization and porosity development in a mixed carbonate clastic sequence an example from the bowland basin northern england widespread dolomitization and leaching occur in the asbian to brigantian dinantian sequence of the bowland basin within this mudrock dominated succession dolomite is developed in calcarenites and limestone breccia conglomerates deposited in a carbonate slope environment pendleside limestone and also within graded quartz wackes deposited by density currents in a generally starved basin environment pendleside sandstone the dolomitized intervals range in thickness from less than one metre to several tens of metres and have a stratabound nature all stages of calcite cement pre date dolomitization and calcite veins are dolomitized dolomite crystals replace neomorphic spar and may also contain insoluble residues that were concentrated along stylolites thus dolomitization was a late stage process within the carbonate diagenetic sequence a late stage diagenetic origin is also indicated within the sandstones with dolomite post dating the development of quartz overgrowths six main textural styles of dolomite are observed 1 scattered 2 mosaic 3 subhedral to euhedral rhombic 4 microcrystalline 5 single crystal and 6 saddle the style of dolomite developed is dependent on the host rock mineralogy on whether it is space filling or replacive and also on temperature chemically the dolomite varies from near stoichiometric compositions to ankeritic varieties containing up to 20 mole feco3 generally the dolomites have isotopic compositions depleted in 18o compared to the host limestone with similar or lighter 13c values initial dolomite was of the scattered type but with progressive replacement of the host a mosaic dolostone with a sucrosic texture was produced there was a general increase in the fe and mn content and reduction in 18o ratio of the crystals during dolomitization leaching is restricted to partly dolomitized horizons where calcite feldspars micas clays and to some extent dolomite have been leached this has produced biomouldic and vuggy secondary porosity within the carbonates whereas in the sandstones honeycombed corroded and floating grains associated with oversized pores occur porosity within both carbonates and sandstones is reduced by ferroan dolomite ankerite cements field petrographic and chemical characteristics indicate that dolomitizing solutions were predominantly derived from the enclosing mudrocks bowland shales during intermediate deep burial fluid migration out of the mudrocks would have been sided by dehydration reactions and overpressure the fluids migrating along the most permeable horizons the coarse grained carbonates and sandstones that are now dolomitized and contain secondary porosity

neodymium isotopes and concentrations in caribbean seawater tracing water mass mixing and continental input in a semi enclosed ocean basin we present the first full water column nd isotope end and concentration data for caribbean seawater as well as for stations close to the orinoco river mouth and in the florida straits the surface inflow into the southeastern caribbean via the guyana current is characterized by an endsignature of 10 9 which is a consequence of the mixing of relatively unradiogenic endsignatures 13 6 supplied by the orinoco river with contributions from the amazon river 10 despite the proximity to land sub surface and intermediate waters within the caribbean largely retain the endsignatures of their source water masses in the atlantic in contrast the deep waters of the caribbean show endsignatures at least 3 endunits more radiogenic than the inflowing upper north atlantic deep water unadw a endshift from 13 to 9 7 can be explained by addition of radiogenic nd to the deep caribbean through weathering inputs from land however in order to balance such large shifts in endwith at the same time modest increases in nd concentrations nd must also be removed from seawater within the basin it is suggested that the long residence time of deep waters in the caribbean allows significant interaction of seawater with sinking particles and seafloor sediments resulting in more radiogenic values these findings have implications for the use of endas a proxy for paleocirculation in restricted basins in which the residence times of the deep waters are long

long term hydrographic changes at 52 and 66 w in the north atlantic subtropical gyre caribbean abstract in july september 1997 two hydrographic lines were done in the western n atlantic along longitudes of 52 and 66 w as part of the woce one time hydrographic survey of the oceans each of these two lines approximately repeated earlier ones done during the international geophysical year s igy and the mid 1980s because of this repeated sampling long term hydrographic changes in the water masses can be examined in this report we focus on temperature and salinity changes within the subtropical gyre mainly between latitudes of 20 and 35 n and compare our results to those presented by bryden et al 1996 who examined changes along a zonal line at 24 n most recently occupied in 1992 since this most recent 24 n section in 1992 substantial changes have occurred in the western part of the subtropical gyre at the depths of the labrador sea water lsw in particular we see clear evidence for colder fresher labrador sea water throughout the gyre on our two recent sections that was not yet present in 1992 at similar longitudes along 24 n at shallower depths inhabited by waters that are an admixture of mediterranean mw and antarctic intermediate waters aaiw our recent survey shows an increase in salinity which can only be attributed to changes in water masses on potential temperature or neutral density surfaces furthermore waters above the mw aaiw layer and into the deeper part of the main pycnocline have continued to become saltier and warmer throughout the 40 year period spanned by our sections these latter changes have been dominantly due to a vertical sinking of density surfaces as t s changes in density surfaces are small but depths of individual t s horizons have increased with time the net change since the igy shows a mean temperature increase between 800 and 2500 m depth at a rate of 0 57 c century with a corresponding steric sea level rise of 1 mm yr and a net downward heave with small values near the top and bottom and a maximum rate of 2 7 m yr at 1800 m depth changes in the deep caribbean indicate a warming since the igy due to temperature increases of the inflowing source waters in the subtropical gyre at 1800m depth but no significant change in the deep salinity

zonal circulation in the nw atlantic and caribbean from a meridional world ocean circulation experiment hydrographic section at 66 w a world ocean circulation experiment hydrographic program section along 66 w in the north atlantic was made in 1997 in addition to the usual variables hydrographic and tracer measured in woce onetime sections we made lowered acoustic doppler current profiler ladcp measurements at nearly all of the stations the section closed off a portion of the western north atlantic to the west of the line making a closed volume for constraining the circulation in addition the deep portions of the caribbean do not communicate with the rest of the basin by combining mass silica and ladcp information as constraints an inverse calculation obtained reveals a strong eastward transport in the gulf stream bounded by westward flowing water on either side within these energetic flows we see evidence for recently ventilated classical labrador sea water which has not reached the deep western boundary current north of puerto rico in any significant amounts within the caribbean our major new finding is a deep cyclonic circulation below sill depth in excess of 100 times the inflow of deep atlantic water through the major deep sill the anegada jungfern passage the signature of the deep atlantic source water is most prominent in cfcs and both a bottom and mid depth maximum are present in the caribbean to the south of puerto rico off the coast of venezuela however only the deeper cfc maximum is found for the entire section the net overturning circulation heat flux and freshwater fluxes are all consistent with expectations based on water mass formation and air sea exchanges to the west of our section but the annual mean air sea fluxes of heat and freshwater from comprehensive ocean atmosphere data sets appear somewhat too small in comparison with our single section result

antarctic icebergs distributions 1992 2014 basal melting of floating ice shelves and iceberg calving constitute the two almost equal paths of freshwater flux between the antarctic ice cap and the southern ocean the largest icebergs 100 km2 transport most of the ice volume but their basal melting is small compared to their breaking into smaller icebergs that constitute thus the major vector of freshwater the archives of nine altimeters have been processed to create a database of small icebergs 8 km2 within open water containing the positions sizes and volumes spanning the 1992 2014 period the intercalibrated monthly ice volumes from the different altimeters have been merged in a homogeneous 23 year climatology the iceberg size distribution covering the 0 1 10 000 km2 range estimated by combining small and large icebergs size measurements follows well a power law of slope 1 52 0 32 close to the 3 2 laws observed and modeled for brittle fragmentation the global volume of ice and its distribution between the ocean basins present a very strong interannual variability only partially explained by the number of large icebergs indeed vast zones of the southern ocean free of large icebergs are largely populated by small iceberg drifting over thousands of kilometers the correlation between the global small and large icebergs volumes shows that small icebergs are mainly generated by large ones breaking drifting and trapping by sea ice can transport small icebergs for long period and distances small icebergs act as an ice diffuse process along large icebergs trajectories while sea ice trapping acts as a buffer delaying melting

hydrography of the eastern south pacific ocean results from the sonne 102 cruise may june 1995 abstract full depth conductivity temperature depth hydrographic measurements were taken in may june 1995 along 28 15 35 15 and 43 15 s from the chilean coast to 86 88 w from the r v sonne sections of potential temperature salinity neutral density and oxygen are presented to illustrate the water column structure in this sparsely sampled region a more comprehensive database on all available hydrographic data from the region was compiled these data and available meteorological data are used to help in the interpretation of the sonne results a number of important features found in the sections are discussed including a shallow salinity minimum apparently ventilated from south of 37 s salt fingering as a possible mechanism to transport high salinity subtropical water into the shallow salinity minimum equatorial subsurface water subantarctic mode water and antarctic intermediate water geostrophic calculations of alongshore flow show the poleward peru chile undercurrent at each of the three sections with a poleward descending core and peak velocities of 10 cm s 1 as in earlier works a deep pacific outflow is found near the chilean coast part of a clockwise deep circulation in the chile basin

melting of ice shelves and the mass balance of antarctica we calculate the present ice budget for antarctica from measurements of accumulation minus iceberg calving run off and in situ melting beneath the floating ice shelves the resulting negative mass balance of 469 gt year 1 differs substantially from other recent estimates but some components are subject to high temporal variability and budget uncertainties of 20 50 annual accumulation from an earlier review is adjusted to include the antarctic peninsula for a total of 2144 gt year 1 an iceberg production rate of 2016 gt year 1 is obtained from the volume of large icebergs calculated from satellite images since 1978 and from the results of an international iceberg census project ice shelf melting of 544 gt year 1 is derived from physical and geochemical observations of meltwater outflow glaciological field studies and modeling of the sub ice ocean circulation the highest melt rates occur near ice fronts and deep within sub ice cavities run off from the ice sheet surface and from beneath the grounded ice is taken to be 53 gt year 1 less than half of the negative mass balance need come from the grounded ice to account for the unattributed 0 45 mm year 1 in the ipcc best estimate of the recent global sea level rise

keel depths of modern antarctic icebergs and implications for sea floor scouring in the geological record abstract icebergs affect the geological record through the scouring or ploughing action of their keels reworking sediments where they contact the sea floor satellite radar altimeter measurements of the surface elevation of the marine margins of the antarctic ice sheet are inverted to produce ice thickness values these data are assumed to represent the keel depths of newly calved icebergs there are three peaks in the frequency distribution of antarctic iceberg keel depths a about 140 200 m in thickness associated with smaller ice shelves fringing antarctica e g wilkins george vi and brunt ice shelves b about 250 300 m from large ice shelves e g ross ronne amery and c approximately 500 600 m from fast flowing ice sheet outlet glaciers e g pine island and dibble glaciers together with the filchner ice shelf controls on iceberg keel depth are ice thickness at the grounding line creep thinning and the rate of melting freezing at the floating ice shelf base with distance to the calving margin the distribution of sea floor scours produced by iceberg grounding is dependent on the changing form and flow of the glaciers and ice sheets from which icebergs are derived and on berg drift tracks and melt rates sea floor evidence for icebergs with particularly deep keels has sometimes been interpreted to indicate the presence of extensive former ice shelves however the largest modern antarctic ice shelves do not produce large numbers of icebergs thicker than about 350 m implying that sea floor scours found in deeper water are unlikely to be an indicator of extensive past ice shelf development iceberg scours found at water depths in excess of about 500 m in the geological record are instead probably indicative of either a the former presence of fast flowing ice sheet outlet glaciers b ice shelves fed from major interior basins where lateral spreading is constrained topographically or c a pulse of large icebergs released during major deglaciation or ice sheet collapse

correlation of carbon dioxide abundance with temperature in clastic hydrocarbon reservoirs relationship to inorganic chemical equilibrium the mol co2 of gas reservoired in sandstones tends to increase with increasing temperature along both the us gulf coast and the norwegian continental shelf each of these provinces displays identical linear correlations between temperature and the log of the partial pressure of co2 i e pco2 in the reservoir fluid that is the product of the mol co2 the reservoir pressure this correlation is the same both in gulf coast reservoirs younger than 17 ma and in norwegian reservoirs of jurassic to triassic age 144 245 ma indicating that it is not dependent on reaction kinetics norwegian shelf data indicate that the same correlation also applies for gas condensate and oil reservoirs we suggest that the log pco2versus temperature correlation is the result of inorganic chemical equilibria between feldspar clay and carbonate minerals a trend of decreasing ph with increasing temperature is fixed by equilibria between aluminosilicate minerals feldspar kaolinite at lower temperatures followed by various reactions between kaolinite illite chlorite and feldspar as temperatures exceed 110 140 c responding to the ph set by the aluminosilicate system co2 activity in the formation water and thereby co2 partial pressure in any gas phase present is controlled by equilibrium with carbonate minerals this model predicts that co2 released by organic maturation will in general result in precipitation of carbonate minerals below 100 120 c and that there should be widespread carbonate dissolution at higher temperatures

quantification of co2 generation in sedimentary basins through carbonate clays reactions with uncertain thermodynamic parameters abstract we develop a methodological framework and mathematical formulation which yields estimates of the uncertainty associated with the amounts of co 2 generated by carbonate clays reactions ccr in large scale subsurface systems to assist characterization of the main features of this geochemical process our approach couples a one dimensional compaction model providing the dynamics of the evolution of porosity temperature and pressure along the vertical direction with a chemical model able to quantify the partial pressure of co 2 resulting from minerals and pore water interaction the modeling framework we propose allows i estimating the depth at which the source of gases is located and ii quantifying the amount of co 2 generated based on the mineralogy of the sediments involved in the basin formation process a distinctive objective of the study is the quantification of the way the uncertainty affecting chemical equilibrium constants propagates to model outputs i e the flux of co 2 these parameters are considered as key sources of uncertainty in our modeling approach because temperature and pressure distributions associated with deep burial depths typically fall outside the range of validity of commonly employed geochemical databases and typically used geochemical software we also analyze the impact of the relative abundancy of primary phases in the sediments on the activation of ccr processes as a test bed we consider a computational study where pressure and temperature conditions are representative of those observed in real sedimentary formation our results are conducive to the probabilistic assessment of i the characteristic pressure and temperature at which ccr leads to generation of co 2 in sedimentary systems ii the order of magnitude of the co 2 generation rate that can be associated with ccr processes

calibrating mg ca ratios of multiple planktonic foraminiferal species with δ 18 o calcification temperatures paleothermometry for the upper water column in order to consistently approximate the thermal vertical structure of past upper water columns mg ca ratios of eight planktonic foraminiferal species with different preferential calcification depths selected from 76 tropical atlantic and caribbean sediment surface samples were calibrated with 18o derived calcification temperatures with an overall range of 8 28 c extending the broad number of species specific calibrations which agree well especially with our shallow dweller calibrations this study presents new bulk calcite mg ca vs calcification temperature relationships for shallow dwelling globigerinoides ruber pink thermocline dwelling globorotalia menardii and deep dwelling globorotalia truncatulinoides dextral and globorotalia crassaformis not separately calibrated before the species specific temperature sensitivities are relatively similar 7 11 increase in mg ca per 1 c yet y axis intercepts vary from 0 23 0 65 for the shallow and thermocline dwellers to 0 83 1 32 for the deep dwellers based on these differences we established a warm water calibration for temperatures 19 c mg ca 0 29 exp 0 101 t r 0 90 shallow and thermocline dwellers and a cold water calibration for temperatures 15 c mg ca 0 84 exp 0 083 t r 0 85 deep dwellers these calibrations are offset by 8 c this may be significant for paleotemperature reconstructions which are afflicted with the problem that similar mg ca offsets are probably characteristic of extinct species used to calculate past temperatures

reduced antarctic meridional overturning circulation reaches the north atlantic ocean 1 we analyze abyssal temperature data in the western north atlantic ocean from the 1980s 2000s showing that reductions in antarctic bottom water aabw signatures have reached even that basin trans basin oceanographic sections occupied along 52 w from 1983 2003 and 66 w from 1985 2003 quantify abyssal warming resulting from deepening of the strong thermal boundary between aabw and north atlantic deep water nadw hence a local aabw volume reduction repeat section data taken from 1981 2004 along 24 n also show a reduced zonal gradient in abyssal temperatures consistent with decreased northward transport of aabw the reduction in the antarctic limb of the moc within the north atlantic highlights the global reach of climate variability originating around antarctica

assessing the effect of dissolution on planktonic foraminiferal mg ca ratios evidence from caribbean core tops in order to assess the dissolution effect on foraminiferal mg ca ratios we analyzed mg ca of seven planktonic foraminiferal species and four of their varieties from caribbean core tops from 900 4700 m water depth depending on the foraminiferal species and variety mg ca start to decline linearly below co32 levels of 18 26 mol kg by 0 04 0 11 mmol mol per 1 mol kg co32 similar to decreases of 0 5 0 8 mmol mol per kilometer below 2500 3000 m water depth above these species specific critical levels mg ca remains stable with higher intraspecific mg ca variability than below we developed routines to correct mg ca from below these critical thresholds for dissolution effects which reduce the overall intraspecific variability by 24 64 and provide dissolution corrected mg ca appropriate to calculate holocene paleotemperatures when taking into account only dissolution unaffected mg ca from 2000 m the systematic succession of foraminiferal species according to their mg ca reflects expected calcification depths

carbon dioxide in clastic rocks and silicate hydrolysis the amount of carbon dioxide in clastic rocks in sedimentary basins increases with depth organic matter dissolved organic species and dissolution of carbonate minerals have been suggested as sources of co sub 2 which increases in abundance with depth and temperature isotopic compositions of aqueous hco sub 3 sup minus gaseous co sub 2 and calcite from conventional hydrocarbon wells and steam assisted recovery of heavy oil suggest that calcite or other carbonate minerals are the source of co sub 2 particularly at higher temperatures detailed examination of the stability of diagenetic minerals such as kaolinite smectite and analcime among others relative to the coexisting waters indicates that silicate hydrolysis is the driving force for dissolution of carbonate minerals and the ultimate source of abundant co sub 2 in clastic rocks in diagenetic environments at temperatures over approximately 100 c

multidecadal variability of north atlantic temperature and salinity during the twentieth century abstract substantial changes occurred in the north atlantic during the twentieth century here the authors demonstrate through the analysis of a vast collection of observational data that multidecadal fluctuations on time scales of 50 80 yr are prevalent in the upper 3000 m of the north atlantic ocean spatially averaged temperature and salinity from the 0 300 and 1000 3000 m layers vary in opposition prolonged periods of cooling and freshening warming and salinification in one layer are generally associated with opposite tendencies in the other layer consistent with the notion of thermohaline overturning circulation in the 1990s widespread cooling and freshening was a dominant feature in the 1000 3000 m layer whereas warming and salinification generally dominated in the upper 300 m except for the subpolar north atlantic where complex exchanges with the arctic ocean occur the single signed basin scale pattern of multidecadal variability is evident from decadal 1000 3000 m temperature and salin

near coastal circum antarctic iceberg size distributions determined from synthetic aperture radar images abstract the radarsat 1 antarctic mapping project ramp compiled a mosaic of antarctica and the adjacent ocean zone from more than 3000 high resolution synthetic aperture radar sar images acquired in september and october 1997 the mosaic with a pixel size of 100 m was used to determine iceberg size distributions around antarctica combining an automated detection with a visual control of all icebergs larger than 5 km2 and correction of recognized false detections for icebergs below 5 km2 in size the numbers of false detections and accuracies of size retrievals were analyzed for three test sites nearly 7000 icebergs with horizontal areas between 0 3 and 4717 7 km2 were identified in a near coastal zone of varying width between 20 and 300 km the spatial distributions of icebergs around antarctica were calculated for zonal segments of 20 angular width and related to the types of the calving fronts in the respective section results reveal that regional variations of the size distributions cannot be neglected the highest ice mass accumulations were found at positions of giant icebergs 18 5 km but also in front of ice shelves from which larger numbers of smaller icebergs calve almost continuously although the coastal oceanic zone covered by ramp is too narrow compared to the spatial coverage needed for oceanographic research this study nevertheless demonstrates the usefulness of sar images for iceberg research and the need for repeated data acquisitions extending ocean wards over distances of 500 km and more from the coast to monitor iceberg melt and disintegration and the related freshwater input into the ocean

a twenty year reversal in water mass trends in the subtropical north atlantic temperature and salinity changes have been compared along three repeat sections at 36 n in the north atlantic the principal changes cooling of the upper waters and warming of the intermediate waters observed between 1959 and 1981 were reversed between 1981 and 2005 the controlling mechanisms for the changes over the two time periods differed through the water column neutral density surfaces over the upper 800 m were firstly uplifted and secondly depressed by typically 50 m which is broadly consistent with the changes in thermocline thickness implied by the temporal changes in ekman pumping in contrast the intermediate waters 800 2500 m firstly became warmer and saltier and secondly became cooler and fresher this change in the intermediate waters was controlled by water mass changes along neutral density surfaces suggesting a change in the source waters principally labrador sea water and mediterranean outflow water

bottom water circulation in the western north atlantic abstract antarctic bottom water flows into the western north atlantic across the equator shifting from the western side to the eastern side of the trough between the american continents and the mid atlantic ridge as it continues north this is puzzling because such large scale motion is thought to be controlled by dynamics that disallows an eastern boundary current previous explanations for the transposition involve a necessarily small scale density current that changes sides because of the change in sign of rotation across the equator or a topographic effect that changes the sign of the effective mean vorticity gradient and thus requires an eastern boundary current here an alternative explanation for the overall structure of bottom flow is given a source of mass to a thin bottom layer is assumed to upwell uniformly across its interface into a less dense layer at rest a simple formula for the magnitude of the upwelling and thickness of the layer is derived that depends on the source strength to th

an iceberg drift and decay model to compute the ice rafted debris and iceberg meltwater flux application to the interglacial north atlantic an iceberg drift and decay model that computes the long term ice rafted debris ird and iceberg meltwater flux over an entire ocean basin is presented the model requires atmospheric and oceanic flow fields and has three main operations iceberg drift decay and debris release using present atmospheric and oceanic flow fields in the north atlantic the model is able to reproduce modern iceberg drift paths and seasonal iceberg occurrences using the same flow fields ird and iceberg meltwater flux to the north atlantic are computed core top data do not preserve an adequate record of present day ird distribution on the ocean floor thus modeled ird results are compared with ird results from marine isotopic stage 5e the last interglacial a period most similar to present interglacial conditions similarity between the modeled and observed ird patterns confirms that present ocean surface conditions affecting iceberg drift and decay are similar to those of stage 5e detailed comparison reveals icebergs from stage 5e reaching as far east as 20 w which is not reproduced by the model under existing oceanographic conditions this discordance suggests that the 5e ird data set includes deposits from times colder than today either because of truly colder intervals in 5e or because of dating uncertainties in the data modeled meltwater flux to the north atlantic exhibits large seasonal and spatial variations using results from a recent study of north atlantic deep water nadw circulation sensitivity to freshwater forcing and assuming a steady greenland ice volume iceberg meltwater forcing is insufficient during interglacial conditions to produce even a partial nadw collapse

experimental studies of silicate carbonate reactions i applications to diagenesis abstract the formation of clays and co2 from silicate carbonate reactions and the effect of these products on reservoir quality and fluid chemistry have been well recognized in the study of sediment diagenesis the phase relationships for the reaction of kaolinite dolomite quartz to calcite chlorite smectite co2 reactions were chemographically examined and experimentally evaluated the phase boundary of this reaction on a t xco2 diagram was interpolated between high temperature experimental data and low temperature field data the results can be applied to predict the amounts type and timing of clay and co2 formation during sediment diagenesis the variation of pore fluid composition e g ca2 and mg2 caused by these reactions was also evaluated using a geochemical modeling program the major conclusions and implications are the following 1 the concentration of co2 in the reaction fluid controls the reaction temperature as well as the clay type chlorite vs smectite formed the equilibrium boundary provides a guideline for estimating the co2 contents the sealing integrity and temperatures of a diagenetic system based on the observed mineral assemblages 2 the silicate carbonate reactions can occur in diagenetic environments that are open to co2 and can therefore be an important inorganic source of co2 which can lead to the formation of co2 rich gas fields and secondary porosity the diagenetic reactions however are significantly suppressed in a closed system e g overpressure zone and therefore cannot significantly contribute to overpressure formation nore generate enough pressure to create fractures and 3 the formation of smectite of chlorite which can serve as a sink for mg2 and to a lesser extent for ca2 the pore fluid released from these reactions during shale diagenesis in general contains much less mg2 than ca2 the reactions in shales are likely sources of ca2 for carbonate cements but not of mg2 for dolomitization

zonal circulation across 52 w in the north atlantic 1 in july august 1997 a hydrographic acoustic doppler current profiler adcp tracer section was occupied along 52 w in the north atlantic as part of the world ocean circulation experiment hydrographic program underway and lowered adcp ladcp data have been used to reference geostrophic velocities calculated from the hydrographic data additional small velocity adjustments provided by an inverse model constraining mass and silicate transports in 17 neutral density layers yield the absolute zonal velocity field for 52 w we find a vigorous circulation throughout the entire section with an unusually strong gulf stream 169 sv and southern deep western boundary current dwbc 64 sv at the time of the cruise at the northern boundary on the west side of the grand banks of newfoundland we find the westward flowing labrador current 8 6 sv whose continuity from the labrador sea east of our section has been disputed directly to the south we identify the slopewater current 12 5 sv eastward and northern dwbc 12 5 sv westward strong departures from strictly zonal flow in the interior which are found in the ladcp data make it difficult to diagnose the circulation there isolated deep property extrema in the southern portion associated with alternating bands of eastward and westward flow are consistent with the idea that the rough topography of the mid atlantic ridge directly east of our section causes enhanced mixing of antarctic bottom water properties into overlying waters with distinctly different properties we calculate heat and freshwater fluxes crossing 52 w that exceed estimates based on air sea exchanges by a factor of 1 7

experimental studies of silicate carbonate reactions ii applications to steam flooding of oil sands abstract the reactions between silicates and carbonates were experimentally simulated at conditions similar to thermal recovery of oil from oil sands several important observations are 1 in general smectite forms from silicate carbonate reactions in fresh water or in dilute na bearing fluids for this reaction silicate can be kaolinite feldspar or volvanic glass whereas carbonate can be dolomite calcite ankerite or siderite 2 analcime instead of smectite forms in fluids with higher na or ph 3 illite or mixed layered illite smectites form in the prescnce of k and nh 4 zeolites and nh 4 illite form in the presence of nh 4 4 ca mica margarite forms from calcite and kaolinite with high fluid rock ratio 200 1 5 talc forms from dolomite and silica in fresh water 6 chlorite forms from kaolinite and dolomite in runs with low fluid rock ratio 7 the reaction temperature significantly increases with increasing co 2 h 2 o ratio in the fluid and 8 the reaction rate decreases as the p co 2 in the system increase but increases again to the initial reaction rate as co 2 is released from the reaction vessel the simulations show that mineralogy injection fluid composition and flow rate fluid rock ratio are key factors that control formation damage during steam flooding the phase relatioships and kinetic data suggest that formation damage during steam treatment may be prevented or retarded by maintaining high x co 2 in the reservoir the results are useful for improving the efficiency of thermal recovery

the sizes frequencies and freeboards of east greenland icebergs observed using ship radar and sextant the scoresby sund fjord system east greenland contains the most productive fast flowing outlet glaciers draining east from the greenland ice sheet calving 18 km3 a 1 of icebergs the sizes frequencies and freeboards of 1900 icebergs were measured from f s polarstern using ship x band radar and sextant radar beam spreading exaggerates iceberg width by 60 m per nautical mile of range beyond the first mile data sets on iceberg size e g that collated for antarctic icebergs collected using ship radars which do not take this effect into account will overestimate iceberg dimensions significantly the location and concentration of icebergs within the fjord complex can be explained by 1 the locations of the principal source glaciers and 2 fjord topography and bathymetry iceberg concentration maximum 0 6 icebergs km 2 declines with distance from the major iceberg sources we found that 69 of icebergs within the fjord system are 1 km in length the largest is 2 7 km long icebergs become spread more evenly over the range of size classes in the outer fjord and shelf modal iceberg keel depth calculated from freeboard measurements is 4 500 m in the inner fjords shifting to lower values in the outer fjords reflecting shallower bathymetry radar measurements of iceberg width cannot be used to infer keel depths accurately because width and keel depth are only weakly correlated comparison between freeboards and keel depths for icebergs from east greenland and the barents sea indicates that the iceberg source i e floating or grounded exerts a fundamental control on iceberg dimensions the drift pattern of icebergs is from the head to the mouth of the fjord system although fjord bifurcations bathymetry and currents provide additional complications the trends in observed iceberg size and frequency and in inferred keel depth in the scoresby sund region are likely to be applicable to other fjords and shelves around greenland

contribution of giant icebergs to the southern ocean freshwater flux 1 in the period 1979 2003 the mass of giant icebergs icebergs larger than 18 5 km in length calving from antarctica averaged 1089 300 gt yr 1 of ice under half the snow accumulation over the continent given by the intergovernmental panel on climate change 2246 86 gt yr 1 here we combine a database of iceberg tracks from the national ice center and a model of iceberg thermodynamics in order to estimate the amount and distribution of meltwater attributable to giant icebergs by comparing with published modeled meltwater distribution for smaller bergs we show that giant icebergs have a different melting pattern an estimated 35 of giant icebergs mass is exported north of 63 s versus 3 for smaller bergs although giant bergs spend more of the earlier part of their history nearer to the coast we combine both estimates to produce the first iceberg meltwater map that takes into account giant icebergs the average meltwater input is shown to exceed precipitation minus evaporation p e in certain areas and is a nonnegligible term in the balance of freshwater fluxes in the southern ocean the calving of giant icebergs is however episodic this might have implications for their impact on the freshwater budget of the ocean it is estimated that over the period 1987 2003 the meltwater flux in the weddell and ross seas has varied by at least 15 000 m3 s 1 over a month because of the potential sensitivity of the production of deep waters to abrupt changes in the freshwater budget variations in iceberg melt rates of this magnitude might be climatologically significant

a chlorite solid solution geothermometer the los azufres mexico geothermal system chlorite constitutes a major hydrothermal alteration product of metamorphism of andesites in the active geothermal system of los azufres mexico electron microprobe analyses performed on a set of crystals from each sample show wide variations in composition correlation coefficients among chemical constituents were calculated it is shown that the tetrahedral charge is positively correlated with the octahedral vacancy and negatively with the iron content and there is almost no correlation with the octahedral aluminium and magnesium content a procedure is proposed to select end members and substitution vectors and to give a general formula for these chlorites

geographical distribution and volume of antarctic icebergs derived from ship observation data information on the occurrence spatial distribution and morphometric characteristics of antarctic icebergs is needed in a large number of applications including navigation heat and freshwater balance calculations biochemistry of the ocean and climatology using over 60 000 ship observations of icebergs in the southern ocean collected since the end of the 1940s we have produced a detailed map of the distribution of antarctic icebergs as well as maps of related statistics including the standard deviation minimum and maximum values of the iceberg concentration and the probability of iceberg free observations the study incorporated small and medium sized icebergs with a length of 2 and 16 893 km 3 with uncertainties of 32 33

a model for diagenetic mass transfer between adjacent sandstone and shale abstract there are numerous suggestions that mass transfer between sandstone and shale is an important factor in the diagenesis of sandstone reservoirs however advective transport models for mass transport have not produced results that support these proposals a model is developed that overcomes the problems of advective transport models by assuming that diffusive mass transfer is the principle transport mechanism the process occurs when the rate of dissolution of reactive detrital components exceeds the local rate of diffusive transport at that point in the burial history units with greater amounts of a reactive component will generate more solute per unit time than units with less reactive component the process forms chemical gradients that can rapidly transfer mass equivalent to several vol of rock over distances of at least 5 m the observed transport of potassium and silica between adjacent sandstone and shale in the north sea during late stage illitization was correctly predicted using this conceptual approach the conceptual framework from the illite model can be extended to other diagenetic reactions and suggests that the burial of adjacent sandstone shale units could produce episodic diffusion gradients that transfer mass and form multiple generations of cement in sandstone reservoirs

near cessation of eighteen degree water renewal in the western north atlantic in the warm winter of 2011 2012 1 the winter of 2011 2012 was a particularly weak season for the renewal of eighteen degree water edw the subtropical mode water of the western north atlantic as demonstrated by argo and repeat hydrography weak late winter buoyancy forcing produced shallower than usual winter mixed layers throughout the subtropical gyre failing to thoroughly ventilate the underlying mode water and can likely be attributed to the coinciding high positive phase of the north atlantic oscillation nao the only region where edw was renewed was in the far northeastern sargasso sea where it is understood that the gulf stream plays a central role in formation no edw formed over the large regions of the gyre where deep winter mixed layers driven by surface buoyancy loss normally create edw the present investigation evaluates 2011 2012 winter buoyancy content anomalies surface buoyancy fluxes and advection of buoyancy via the gulf stream and compares them with the previous seven winters that exhibited more vigorous edw formation the weak 2011 2012 formation did not result from increased gulf stream heat advection and was also not driven by preconditioning as the buoyancy content of the region prior to the onset of winter forcing was not unusually high rather the weak formation resulted from climatologically weak surface cooling late in winter the winter of 2007 2008 also experienced particularly weak edw formation under similar conditions including a high nao and weak late winter surface cooling

recirculating components to the deep boundary current of the northern north atlantic abstract the meridional overturning system of the north atlantic is conventionally thought of as transporting warm water 4 c to high latitudes and covd water to low latitudes the northern cold water sources for this system are dense overflow from the nordic seas and less dense water from the labrador sea lsw the overflow components are carried westward by a deep northern boundary current dnbc that is shown here actually to begin southeast of the overflow regions the dnbc lies along the southern side of a system of islands and submarine ridges that divides the nordic seas from the subpolar basins the overflows act to increase the transport of the dnbc and this transport is further increased through the entrainment of warm waters once inside the labrador sea the dnbc is joined by lsw before continuing south to low latitudes as a cold deep western boundary current dwbc however published transport estimates are larger than can be explained by warm water entrainment alone thus indicating entrainment also of recirculating cold components the subject of this paper their sources are shown to be the lsw and cold abyssal waters originating from the southern hemisphere the lsw is entrained downward into the denser part of the dnbc and laterally into the upper part of the dwbc whereas the cold abyssal waters are supplied by an eastern intensified northward flow in the eastern atlantic that serves as the initial source of the dnbc and by a similar northward flow in the western atlantic the meridional overturning system described includes recirculations and poleward transport of cold water in addition tothe components described by the conventional system the cold abyssal waters in both the eastern and western basins have relatively low levels of oxygen and high concentrations of silicate reflecting their southern origin but their influence in the northwestern atlantic is somewhat obscurred by strong recirculating cyclonic gyres in the newfoundland and labrador basins this influence is detected by a deep silicate maximum extending poleward from the mid latitude western atlantic through the two gyres with eastern concentration and recirculating back diluted toward the south in the dwbc within the respective basins such a maximum also extends northward through the irminger basin into the dnbc but there is an ambiguity as to whether this is a direct extension of the signal from the south in the western basin or if it comes from the mid latitude eastern basin by way of westward flow through the charlie gibbs fracture zone it is perhaps consequence of both estimates of the volume transports of the various recirculating cold components indicate that they supply about as much water to the deep boundary currents as do the combined cold water sources in the north

changes in moc and gyre induced atlantic ocean heat transport anthropogenic change of the atlantic meridional ocean heat transport aoht is diagnosed from a large ensemble of climate simulations over the period 1940 2080 as well as its relation to changes in the meridional overturning circulation moc and the gyre circulation in the atlantic internal variability in aoht is closely associated with moc variability the anthropogenic change in aoht however does not follow the forced decrease in the moc thermohaline changes in the intermediate and deep water masses that are formed in the subpolar gyre cause the vertical temperature gradient near the western boundary to increase as a result the heat transport by the baroclinic gyre component largely compensates the decreased heat transport by the moc

intense warming and salinification of intermediate waters of southern origin in the eastern subpolar north atlantic in the 1990s to mid 2000s 1 recent thermohaline changes in the layer of intermediate waters iw advected into the eastern subpolar north atlantic from lower latitudes are quantified using the data from the repeated transatlantic sections positive trends in temperature and salinity in the iw density class at 53 n 0 049 c a and 0 0088 a 1992 2002 and 60 n 0 044 c a and 0 0085 a 1997 2005 are derived the unexpectedly high rates of the iw warming and salinification cannot be explained solely by the long term and recent decadal changes at the intermediate levels in the midlatitude north atlantic and appear to be a consequence of the northward advance of the source water masses caused by the north atlantic oscillation induced contraction of the subpolar gyre

immiscible co2 h2o fluids in the shallow crust the significance of a single co2 h2o fluid phase is well known for metamorphic systems and co2 h2o immiscibility is explicit in fluid inclusion literature especially regarding hydrothermal ores complex multiphase co2 h2o behavior exists over wide temperature and pressure ranges overlapping other important geochemical processes the character and physical chemical properties of multiple phases possible for co2 and h2o and the potential impact of these coexisting phases on geochemical processes in the crust are not broadly appreciated we propose that immiscible supercritical co2 fluid and a liquid rich in h2o coexist in the shallow crust to 400 c and 300 mpa and that interactions among the two fluids and host rock are significant processes that produce recognizable geochemical and textural evidence supercritical co2 fluids bring potential complexity to fluid rock systems by influencing aqueous reactions via carbonic acid equilibria penetrating complex geometries inaccessible to aqueous fluid and dissolving and redistributing metals as organometallic compounds the distal margin of a contact metamorphic aureole is one example we discuss in which interaction between two disparate co2 h2o fluids controls h2o activity and the progress and distribution of metamorphic hydration reactions in another example supercritical co2 produces acidity carbonate saturation and silica supersaturation in brine separation and emplacement of this brine into a rock dominated system buffered to neutral ph enhances precipitation of carbonates and quartz chalcedony or amorphous silica in veins other possible examples of co2 h2o fluid immiscibility coupled with multiphase fluid rock interactions are clay desiccation diagenetic and postdiagenetic silicate reactions origin and distribution of carbonate cements in sedimentary basin sandstones fluid mass transfer and anthropogenic co2 sequestration

north atlantic oscillation induced changes of the upper layer circulation in the northern north atlantic ocean 1 hydrographic data of the 1990s along world ocean circulation experiment sections a1e greenland ireland and a2 newfoundland france indicate a redistribution of cold low saline subarctic waters and warm saline subtropical waters in the upper layer of the northern north atlantic within about 2 years after the north atlantic oscillation had turned from a period with strong westerlies until 1995 to a period with weak westerlies in 1996 and 1997 in the latter period subarctic waters spread preferably southward along the continental slope east of newfoundland rather than eastward with the north atlantic current nac into the irminger iceland and west european basins as a consequence the subarctic front and the associated nac shifted eastward in the newfoundland basin where subarctic waters accumulate and westward in the iceland basin where a large warm and saline anomaly was found in 1996 and 1997 indicating a contraction of the subpolar gyre in the irminger basin the anomaly occurred in 1998 and 1999 whereas the cyclonic circulation in the irminger and iceland basins weakened it intensified in the newfoundland basin where a strengthened labrador current retroflection joined the nac this and the increased anticyclonic recirculation of subtropical waters in the newfoundland and west european basins caused a considerable reduction of the northward heat transport across 47 n in the upper layer in 1997 the anticyclonic circulation occurring in the west european basin suggested a northward expansion of the subtropical gyre

iceberg calving from the amery ice shelf east antarctica we investigate the iceberg calving cycle of the amery ice shelf ais east antarctica using evidence acquired between 1936 and 2000 the most recent major iceberg calving event occurred between late 1963 and early 1964 when a large berg totalling about 10000 km2 in area broke from the ice front the rate of forward advance of the ice front is presently 1300 1400 m a 1 at this rate of advance based on the present ice front position from recent radarsat imagery it would take 20 25 years to attain the 1963 pre calve position suggesting that the ais calving cycle has a period of approximately 60 70 years two longitudinal parallel to flow rifts approximately 25 km apart at the ais front are observed in satellite imagery acquired over the last 14 years these rifts have formed at suture zones in the ice shelf where neighbouring flow bands have separated in association with transverse spreading the rifts were 15 km rift a and 26 km rift b in length in september 2000 and will probably become the sides of a large tabular iceberg 25 km 25 km a transverse perpendicular to flow fracture visible at the upstream end of rift a in 1996 had propagated 6 km towards rift b by september 2000 when it meets rift b the iceberg will calve a satellite image acquired in 1962 shows an embayment of this size in the ais front hence we deduce that this calving pattern also occurred during the last calving cycle and therefore that the calving behaviour of the ais apparently follows a regular pattern

year to year reoutcropping of eighteen degree water in an eddy resolving ocean simulation abstractwinter outcropping of the eighteen degree water edw and its subsequent dispersion are studied using a eddy resolving simulation of the family of linked atlantic modeling experiments flame outcropped edw columns in the model simulations are detected in each winter from 1990 to 1999 and particles are deployed in the center of each outcropped edw column subsequently the trajectories of these particles are calculated for the following 5 yr the particles slowly spread away from the outcropping region into the nonoutcropping subducted edw region south of 30 n and eventually to the non edw region in the greater subtropical gyre approximately 30 of the particles are found in non edw waters 1 yr after deployment after 5 yr only 25 of the particles are found within edw the reoutcropping time is defined as the number of years between when a particle is originally deployed in an outcropping edw column and when that particle is next found in an outcropping edw column of the particles 66 ar

transatlantic temperature and salinity changes at 24 5 n from 1957 to 2004 in 2004 a fifth occupation of a transatlantic section at 24 5 n allows us to examine decadal temperature and salinity changes using high quality full depth hydrographic data since 1957 waters shallower than 1750 dbar have been warming and salinifying at least since 1981 and in 2004 are significantly warmer and saltier than at any time since 1957 while deeper than 3000 dbar there has been continuous cooling and freshening since 1957 temperature and salinity changes at constant pressures are partitioned into changes on isopycnal surfaces and changes due to the vertical movement of the isopycnals warming in the western atlantic thermocline since 1957 at a rate of 0 0111 c yr dominates the transatlantic average while deep water has cooled and freshened at rates of 0 0021 c yr and 0 0003 psu yr respectively we argue that the shallower and deeper changes are consistent with a recently reported increased southward thermocline circulation and reduced southward flux of deep water

experimental kinetic study of the reaction calcite quartz wollastonite carbon dioxide from 1 to 3 kilobars and 500 degrees to 850 degrees c

precipitation sealing and diagenesis 1 experimental results during burial and diagenesis of granular aggregates significant permeability reduction may be induced by the formation of low temperature authigenic minerals to quantitatively assess the importance of this process we have conducted a series of hydrothermal flow through experiments using deionized water and labradorite quartz sand all experiments were conducted in a modified triaxial apparatus configured to allow continuous permeability measurements under most of the conditions tested significant permeability reduction is observed with no concurrent decrease in porosity the overall permeability reduction sometimes exceeds 1 order of magnitude over 4 days and is positively correlated to temperature and deviatoric stress scanning electron microscope observations together with data from additional experiments show that the observed permeability reduction is entirely a result of secondary mineral growth si and al concentrations in the postexperiment fluids are also correlated to temperature and stress confirming the link between the chemical state of the system and permeability behavior in all experiments permeability reduction is fastest early and levels off in the late stages to explain the permeability behavior as a function of time a conceptual model is developed in which precipitation of authigenic minerals is rapid at early times while dissolution of quartz and labradorite is most active as the system approaches equilibrium the components necessary for secondary mineral formation are liberated at a lower rate thereby causing precipitation to slow although authigenic mineral formation does not reduce total pore space in these experiments there is a reduction in effective porosity which results in permeability reduction

weddell sea iceberg drift five years of observations since 1999 52 icebergs have been tagged with gps buoys in the weddell seato enable monitoring of their position the chosen icebergs were of small tomedium size with a few icebergs larger than 10 km associatedwith the calving of icebergs a38 and a43 from the ronne ice shelf the majority of icebergs were tagged off neumayer station 8e 70s it was found that smaller bergs with edges shorter than 200 m had the shortestlife cycle 0 5 yr iceberg and thus freshwater export out of theweddell sea was found to be highly variable in one year the majority of buoysdeployed remained in the weddell sea constituting about 40 of the ncep p efreshwater input whereas in other years all of the tagged icebergs were exported the observed drifts of icebergs and sea ice showed a remarkably coherent motion the analysis of an iceberg sea ice buoy array in the western weddell seaand an iceberg array in the eastern weddell sea showed a coherent sea iceiceberg drift in sea ice concentrations above 86 dynamic kinematic parameter dkp during the course of coherent movement were low and deviations from the meancourse associated with the passage of low pressure system the length scale ofcoherent movement was estimated to be less than 250km about half the value found forthe arctic ocean

water masses and circulation in the surface layers of the caribbean at 66 w a meridional hydrographic section was made in august september 1997 at 66 w from the coast of venezuela to woods hole aboard the r v knorr in this report we concentrate on near surface measurements in the caribbean the data show two distinct water masses with different origins from approximately 14 n to puerto rico caribbean surface water and subtropical under water with their source in the north atlantic are found as previously observed from venezuela to approximately 13 n a less saline water mass with its source in the tropics and south atlantic is found within the southern portion of the section two different velocity patterns are observed namely an eastward flow with a subsurface maximum near the coast of venezuela and a surface intensified westward jet with velocities of 130 cm s 1 in midbasin

climate variability inferred from a continuously stratified model of the ideal fluid thermocline climate variability in the subtropical gyre interior induced by anomalous surface thermal forcing ekman pumping mixed layer depth variability and anomalous subpolar water formation is examined using a continuously stratified model of the ideal fluid thermocline cooling heating induces a negative positive potential vorticity perturbation in the ventilated thermocline and the associated density perturbations propagate downstream in the form of second and higher baroclinic modes the second baroclinic mode resembles the traditional second baroclinic mode because it has a thermal structure with cooling warming in the upper thermocline and warming cooling in the lower thermocline anomalous ekman pumping can also induce density perturbations that propagate westward in the form of the first baroclinic mode in addition if the outcrop lines are nonzonal there are density perturbations that propagate downstream in the form of the second or third baroclinic modes perturbations in the sea surface elevation are mostly confined to the region of anomalous forcing on the other hand when the low potential vorticity anomaly in the subpolar mode water spreads into the subtropical basin both the unventilated and ventilated thermocline move downward consequently temperature at a given depth seems to increase

co2 production in tar sand reservoirs under in situ steam temperatures reactive calcite dissolution abstract recovery of highly viscous oil from some of the deeper oil sand deposits of northern alberta canada is made possible through injection of heat by steam or hot water flooding of the reservoirs the rise in temperature lowers the viscosity of the bitumen allowing it to be produced the increase in temperature accelerates the reactions between the matrix and pore minerals of the formation and can produce reaction products which can significantly alter the permeability of the reservoir if carbonate minerals are present in the reservoir inorganic co 2 may also be a reaction product the grand rapids reservoir consists of relatively clean quartz sand containing 7 wt kaolinite 1 wt calcite and a trace of smectite core floods of this sand by a neutral nacl brine at 265 c 8 2 mpa overburden pressure 6 0 mpa fluid pressure and a flow velocity of 0 4 pore volumes per hour were used to determine the potential for hydrothermal reactions between clays and carbonate minerals in a natural reservoir sand reaction progress was followed by continuous sampling of the production fluids the produced water was analyzed and the phase chemistry was calculated back to the run conditions using the computer code solmneqf mass balance considerations on produced total inorganic carbon tic show that calcite broke down very quickly the maximum in co 2 production occurring after only one pore volume of fluid had passed through the core the ca released from the breakdown of calcite was incorporated in the formation of smectite as was shown by post run clay mineral analysis by the following unbalanced chemical reaction calcite kaolinite h 4 si0 4 ca smectite h 2 0 co 2 silica was supplied by the dissolution of quartz silica concentrations analyzed in the production fluid were depressed from those predicted by previously published quartz rate equations because of the rapid rate of smectite synthesis these observations were used to formulate the following model for the passage of the first pore volume of nacl brine through the core initially calcite is present throughout the core as the brine enters the inlet of the core it equilibrates with calcite the brine remains in equilibrium with calcite throughout the core as quartz and kaolinite react to form smectite this model was tested with the computer code path ubc using co 2 production as a measure of the progress variable a best fit was achieved to the produced fluid chemistry by varying relative dissolution rates of kaolinite and quatz and varying the suppression of precipitation of certain minerals

changing effect of el nino on antarctic iceberg distribution from canonical el nino to el nino modoki earlier studies indicate that during el nino events the iceberg concentration increases in the east of the pacific sector and in the west of the atlantic sector of southern ocean but decreases in the center of the pacific sector during la nina the pattern of the iceberg concentration anomalies in these regions reverses this iceberg redistribution is explained by anomalous winds and currents around an extensive positive atmospheric pressure anomaly that typically develops in the south east pacific during the warm el nino southern oscillation enso phase in this study the results of iceberg observations during two cruises of the r v akademik fedorov in antarctica in january february 2008 la nina and 2010 el nino have been used to examine the consistency of changes in the iceberg distribution in the southern ocean related to el nino events the analysis of these observations has shown that in the pacific sector of antarctica changes in the iceberg distribution between 2008 and 2010 followed the scenario outlined above and thus could be associated with the enso phase change contrary to earlier observations the iceberg concentration in the atlantic sector of antarctica did not increase during 2010 el nino the latter is explained by a noncanonical type of 2010 el nino el nino modoki and associated atmospheric circulation pattern different from the canonical el nino further analysis has shown that a more frequent occurrence of el nino modoki in recent years have resulted in weaker links between el nino events and the antarctic iceberg distribution

mineral reactions in quartzose rocks during thermal recovery of heavy oil lloydminster saskatchewan canada abstract x ray diffraction analysis thin section analysis and scanning electron microscopy were used to compare the mineralogy of pre and post recovery cores from the lower cretaceous sparky interval in aberfeldy steamflood and fireflood pilot projects lloydminster area saskatchewan canada the objectives were to document the potential changes in mineralogy that may occur during recovery of heavy oil and to evaluate the risk of formation damage from mineral reactions these unconsolidated sediments are very quartzose 90 and they also contain feldspars clays mainly kaolinite and carbonate cements siderite and ankerite the formation of new minerals in the burned zone and the plugging of pores by coke in the zones below the burned zones is likely to cause small reductions in porosity and permeability illite formation is observed in the steamflood pilot but is not extensive enough to cause formation damage carbonate scale is observed at the producing wells during steamflooding illite and chlorite are formed the smectite which is observed is due to mud invasion during fireflooding illite forms in the coked zones whereas k feldspar and hematite form in the burned zones thermodynamic calculations of the stability of mineral forming reactions are in agreement with physical conditions during steaming the decomposition of kaolinite in the burned zones indicates combustion temperatures greater than 510 540 c it may be concluded that in a period of a few years only minor detrimental effects related to mineralogy occurred during thermal recovery in the aberfeldy pilot projects

antarctic iceberg distribution and dissolution from ship based observations the australian antarctic program s iceberg dataset from ship based observations including information from the austral summer seasons 1984 85 to 1999 2000 is examined and used to extend earlier studies using snapshots of the iceberg population to provide an idea of the iceberg life cycle the distribution of icebergs between 60 and 1508 e is discussed in terms of calving regions and ocean currents temporal changes are also examined the discussion leads us to the point where we can define an area bounded to the north by the maximum sea ice limit and to the south by the antarctic divergence in which icebergs are confined as they drift eastward this allows estimation of total dissolution in terms of iceberg numbers and volume within 108 longitudinal sectors and with knowledge of drift speeds iceberg movement rates and freshwater input across the sector iceberg dissolution rates are found to be 0 03 0 05 m d 1 and the total mass contribution of fresh water to the ocean as the icebergs traverse our 308 of longitude study sector is 32 gt this amounts to a contribution equivalent to precipitation of 15 5 cm a 1 accounting for 2 of the total iceberg discharge from the antarctic ice sheet

calving fluxes and basal melt rates of antarctic ice shelves iceberg calving has been assumed to be the dominant cause of mass loss for the antarctic ice sheet with previous estimates of the calving flux exceeding 2 000 gigatonnes per year1 2 more recently the importance of melting by the ocean has been demonstrated close to the grounding line and near the calving front3 4 5 so far however no study has reliably quantified the calving flux and the basal mass balance the balance between accretion and ablation at the ice shelf base for the whole of antarctica the distribution of fresh water in the southern ocean and its partitioning between the liquid and solid phases is therefore poorly constrained here we estimate the mass balance components for all ice shelves in antarctica using satellite measurements of calving flux and grounding line flux modelled ice shelf snow accumulation rates6 and a regional scaling that accounts for unsurveyed areas we obtain a total calving flux of 1 321 144 gigatonnes per year and a total basal mass balance of 1 454 174 gigatonnes per year this means that about half of the ice sheet surface mass gain is lost through oceanic erosion before reaching the ice front and the calving flux is about 34 per cent less than previous estimates derived from iceberg tracking1 2 7 in addition the fraction of mass loss due to basal processes varies from about 10 to 90 per cent between ice shelves we find a significant positive correlation between basal mass loss and surface elevation change for ice shelves experiencing surface lowering8 and enhanced discharge9 we suggest that basal mass loss is a valuable metric for predicting future ice shelf vulnerability to oceanic forcing

origin and evolution of formation waters from oil fields on the norwegian shelf abstract stable isotopes of h and o and chemical analyses of formation waters from upper triassic jurassic clastic reservoirs and cretaceous carbonate reservoirs offshore norway are employed to interpret the origin and evolution of these waters in both types of reservoir the formation waters become progressively enriched in total dissolved solids and the heavy isotope of o with increasing depth whereas deuterium varies erratically between 20 and 40 smow bromine analyses and stable isotope data indicate that the formation waters are mixtures of a brine end member formed by evaporation of sea water beyond the point of halite saturation and meteoric water the chemical and isotopic composition of the formation waters and general geological considerations suggest that the brines originated as connate waters in permian evaporites and were later expelled into overlying strata there is a disequilibrium stable isotope distribution between the bulk chalk formations and the formation waters and only minor diagenetic modification of the formation waters appears to have taken place in these reservoirs the formation waters from the clastic reservoirs on the other hand are modified by diagenetic reactions