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

tracing the nd isotope evolution of north pacific intermediate and deep waters through the last deglaciation from south china sea sediments abstract the intermediate and deep waters of the pacific ocean play a crucial role for regulating global climate changes on the millennium timescale however due to poor preservation of carbonate sediments in the deep pacific little attention has been received to better understand deep ocean circulation and its relationship with abrupt climate events here we present the first authigenic nd isotope e nd record extracted from fe mn oxyhydroxides of the south china sea scs sediments so17940 2 1727 m water depth in order to investigate changes of intermediate and deep water circulations in the pacific ocean since the last glacial maximum lgm in general the seawater e nd record extracted from the scs sediments paralleled the existing nd isotopes of fish teeth debris from the eastern north pacific core during the last deglaciation demonstrating that our authigenic e nd can faithfully record the seawater e nd evolution in the deep pacific ocean at the onset of the deglacial period our data exhibit a clear negative shift in e nd towards a gradually increased component of antarctica intermediate water aaiw and reached a maximal influx during the mid heinrich stadial 1 hs1 16 kyr bp between the hs1 and younger dryas deep water circulation gradually shifted back to the modern condition during the bolling allerod warm interval a pronounced negative e nd excursion had occurred during the pre boreal pb suggesting a rapid reorganization of deep water ventilation in the pacific ocean and was predominated by aaiw this is most likely due to poor ventilation in the western north pacific associated with an intensified summer monsoon during the pb early holocene warm period after the pb period the seawater e nd values were once again dominated by pacific deep water at the study site

a study of cleaning procedures used for foraminiferal mg ca paleothermometry the various cleaning steps required for preparation of foraminiferal samples for mg ca and sr ca analysis are evaluated for their relative importance and effects on measured elemental ratios it is shown that the removal of silicate contamination is the most important step for the measurement of mg ca ratios in an example bulk sample mg ca decreases from 10 5 to 2 5 mmol mol 1 during clay removal oxidation of organic material causes a lowering of sample mg ca in the order of 10 or approximately 1 c when converted to temperature use of dilute acid leaching to remove adsorbed contaminants causes partial dissolution of the sample carbonate and a corresponding decrease in mg ca reductive treatment also causes dissolution of the sample and a decrease in the mg ca ratio of up to 10 15 sample preparation for sr ca analysis does not require the same degree of rigor as is necessary for mg ca work the within run reproducibility of the method described here for g ruber in a core top sample from the arabian sea was 1 8 mean sample ratio was 4 72 mmol mol 1 when converted to temperature this becomes 28 0 2 c the equivalent result for sr ca was 0 5 mean ratio 1 44 mmol mol 1

northward intrusion of antarctic intermediate water in the western pacific abstract the northward intrusion of antarctic intermediate water aaiw is examined using historical data combined with synoptic observations from a repeated hydrographic section in the western pacific ocean the results of this analysis suggest that aaiw is traced as a salinity minimum to only about 15 n via the new guinea coastal undercurrent and the mindanao undercurrent there is no northward extension of aaiw farther to the north along the western boundary although relatively high oxygen water does exist in the okinawa trough it is connected with high oxygen water in the south china sea scs through the luzon strait but not from the south as an extension of aaiw local circulation seems to play an essential role in localizing the oxygen maximum in the scs evidence exists to suggest that high oxygen water enters the scs as part of the pacific deep water around the still depth 2000 m of the luzon strait from there part of it upwells and is entrained into shallower isopycnal surfaces by vertica

the cause of carbon isotope minimum events on glacial terminations the occurrence of carbon isotope minima at the beginning of glacial terminations is a common feature of planktic foraminifera carbon isotopic records from the indo pacific sub antarctic and south atlantic we use the 13 c record of a thermocline dwelling foraminifera neogloboquadrina dutertrei and surface temperature estimates from the eastern equatorial pacific to demonstrate that the onset of 13 c minimum events and the initiation of southern ocean warming occurred simultaneously timing agreement between the marine record and the 13 c minimum in an antarctic atmospheric record suggests that the deglacial events were a response to the breakdown of surface water stratification renewed circumpolar deep water upwelling and advection of low 13 c waters to the convergence zone at the sub antarctic front on the basis of age agreement between the absolute 13 c minimum in surface records and the shift from low to high 13 c in the deep south atlantic we suggest that the 13 c rise that marks the end of the carbon isotope minima was due to the resumption of north atlantic deep water influence in the southern ocean

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

variations of east asian summer monsoon since the last deglaciation based on mg ca and oxygen isotope of planktic foraminifera in the northern east china sea 1 variations in mg ca based sea surface temperature and oxygen isotope ratio 18o of the surface water in the northern east china sea ecs were reconstructed with high resolution during the last 18 kyr using planktic foraminifera millennial scale variations between warmer more saline surface water and cooler less saline surface water were recognized during the early deglacial period and the holocene suggesting changes in the mixing ratio between the kuroshio water and the changjiang diluted water stronger east asian summer monsoon easm precipitation events in south china are identified at 10 5 8 8 7 0 5 3 4 7 2 9 1 7 and 0 5 ka based on sea surface salinity sss records of the northern ecs weaker easm precipitation events are also detected at 9 3 8 3 7 3 6 0 3 3 2 3 0 7 and 0 4 ka during the holocene these events agree with the maxima in 18o records of stalagmites from various parts of the changjiang yangtze river drainage this agreement supports that our sss record properly captures the millennial scale dry less easm precipitation events over the drainage basin of the changjiang river during the holocene these dry events are also in good agreement with north atlantic ice rafted events suggesting a teleconnection between north atlantic climate and the easm during the holocene

mid depth circulation in the northwest pacific during the last deglaciation evidence from foraminiferal radiocarbon ages 1 sediment cores mr01 k03 pc4 pc5 1366 m water depth collected from off northern japan were studied using coexisting planktonic and benthic foraminiferal radiocarbon measurements to reconstruct the history of mid depth circulation in the northwest pacific reconstructed ventilation ages indicate that consistent with data from a previous radiocarbon study at a shallower site there was significant variation in mid depth circulation during the last deglaciation especially in the bolling allerod 13 15 ka and younger dryas 11 5 13 ka intervals our record indicates that the ventilation changes in the north pacific were antiphase to those of the north atlantic suggesting that atmospheric moisture transport associated with the asian monsoon might have played a great role in millennium scale ventilation changes in the north pacific during the last deglaciation

accurate estimation of sea surface temperatures using dissolution corrected calibrations for mg ca paleothermometry 1 paired 18o and mg ca measurements on the same foraminiferal shells offer the ability to independently estimate sea surface temperature sst changes and assess their temporal relationship to the growth and decay of continental ice sheets the accuracy of this method is confounded however by the absence of a quantitative method to correct mg ca records for alteration by dissolution here we describe dissolution corrected calibrations for mg ca paleothermometry in which the preexponent constant is a function of size normalized shell weight 1 for g ruber 212 300 m mg ca ruber 0 025 wt 0 11 e0 095t and b for g sacculifer 355 425 m mg ca sacc 0 0032 wt 0 181 e0 095t the new calibrations improve the accuracy of sst estimates and are globally applicable with this correction eastern equatorial atlantic sst during the last glacial maximum is estimated to be 2 9 0 4 c colder than today

vertical thermal structure history in the western subtropical north pacific since the last glacial maximum 1 variations in sea surface temperature sst and vertical thermal structure in the western subtropical north pacific which has the largest air sea heat flux of the world s oceans provide insights into the mechanisms of climate change related to air sea interactions here we present planktonic 18o and mg ca records from the western subtropical gyre of the north pacific spanning the last 30 kyrs the results indicate that subtropical ssts were approximately 3 c lower during the last glacial than in the holocene interglacial indicating that glacial cooling occurred uniformly in the low to mid latitudes of the western north pacific a decrease in intermediate depth temperatures at the late glacial suggests that the formation and or advection of the subtropical mode water was enhanced due to a strong east asian winter monsoon the results suggest that the change in the thermal structure of the subtropical gyre was related to changes in east asian monsoon activity

intermediate water ventilation change in the subarctic northwest pacific during the last deglaciation 1 the laminated sediments suggest significant depletion in dissolved oxygen of intermediate water in the north pacific during the last deglaciation however the cause of depleted oxygen during deglaciation is still a matter of debate here we present foraminiferal mg ca based intermediate and surface temperatures and 18o of seawater 18ow a proxy of salinity in the oyashio region in order to investigate intermediate water circulation through the last deglaciation results indicate that the intermediate water temperature and 18ow increased in association with ventilation age at the bolling allerod period suggesting that the poor ventilation at that time the surface record shows that the decrease of salinity preceded the slowdown of intermediate ventilation the coupled variation of intermediate and surface water suggests that the supply of cold fresh intermediate water diminished because of poor ventilation at the high latitude due to surface freshening

last glacial holocene change in intermediate water ventilation in the northwestern pacific abstract the modern north pacific is the terminus for deep water circulation while no deep water mass is formed today the region is the source of north pacific intermediate water 300 800 m formed primarily in the sea of okhotsk however the source and strength of intermediate water in the glacial north pacific was likely different from the present intermediate water here we present microfossil evidence of late quaternary ventilation changes associated with changes in intermediate water intermediate water ventilation decreased drastically at the glacial termination when it switched to the modern circulation system the ventilation change appears to have been widespread and synchronous in the north pacific glacial microfossil assemblages indicate that there was relatively strong ventilation of intermediate water which seems to have been cold and well oxygenated as if produced by brine rejection during the formation of sea ice on the basis of the glacial distribution of microfossils in the north pacific we suggest that intermediate water was derived from the bering sea during the glacials rather than the sea of okhotsk

glacial age hydrography of the far northwest pacific ocean stable isotope data on benthic foraminifera from more than 30 cores on the northern emperor seamounts and in the okhotsk sea are synthesized in paleohydrographic profiles spanning the depth range 1000 4000 m holocene core top benthic foraminiferal 18o and 13c data are calibrated to modern hydrographic properties through measurements of 13c of co2 and 18o of seawater cibicidoides stable isotope ratios are close to the 13c and equilibrium 18o of seawater whereas uvigerina 18o and 13c are variably offset from cibicidoides glacial maximum 13c of cibicidoides displays a different vertical profile than that of the holocene when results are adjusted by 0 32 to account for the secular change in 13c during the last glacial maximum the data coincide with the modern seawater and foraminiferal curves deeper than 2 km however at shallower depths 13c gradually increases by as much as 1 above the modern value furthermore above 2 km the benthic 18o decreases by 0 5 these results are consistent with a benthic front at 2 km in the north pacific see herguera et al 1992 but they differ from interpretations based on trace metal data which indicate a source of nutrient depleted deep water during glaciation the isotopic data suggest that during glaciation there was a better ventilated watermass at intermediate depths in the far northwestern pacific it was relatively fresher than deep waters there and deep waters were as nutrient rich as today

a late quaternary planktonic foraminifer faunal record of rapid climatic changes from the south china sea abstract a high resolution planktonic foraminifer record from a core recovered from the south china sea scs sonne 17938 2 19 47 2 n 117 32 3e 2840 m t 250 1000 years shows rapid millennial scale changes in the western pacific marginal sea climate during the last 30 000 years the scs is the largest western pacific marginal sea off the southeast asian continent the area today dominated by seasonal monsoon changes quantitative analyses of planktonic foraminifer faunal abundance data from the core indicate large downcore variations in the relative abundances of the dominant taxa since about 30 000 years ago in the isotope stage 3 further analyses indicate that the abundance of g inflata a good indicator species for cold sst 13 19 c and deep mld 100 125 m waters shows abrupt shifts during stages 2 and 3 the abundance record of g inflata tends to be punctuated by quasi periodic short intervals 2000 3000 yrs where its abundance reaches 15 or greater superimposed on generally low 5 10 background values this pattern suggests an instability of surface ocean conditions of the scs during the past 30 000 years the abrupt abundance changes of g inflata correlate well with similar climatic changes observed from a gisp2 ice core 18o and north atlantic core dsdp 609 n pachyderma s and lithic grain abundances during heinrich events these results suggest that the millennial scale variability of climate is not peculiar to the atlantic region apparently the rapid scs climatic changes during heinrich events are driven by effective mechanisms of particularly the effects of shifts in the latitudinal position of the siberia high pressure system

late quaternary changes in intermediate water oxygenation and oxygen minimum zone northern japan a benthic foraminiferal perspective 1 a strong oxygen minimum zone omz currently exists at upper intermediate water depths on the northern japanese margin nw pacific the omz results largely from a combination of high surface water productivity and poor ventilation of upper intermediate waters we investigated late quaternary history last 34 kyr of ocean floor oxygenation and the omz using quantitative changes in benthic foraminiferal assemblages in three sediment cores taken from the continental slope off shimokita peninsula and tokachi northern japan at water depths between 975 and 1363 m these cores are well located within the present day omz a region of high surface water productivity and in close proximity to the source region of north pacific intermediate water late quaternary benthic foraminiferal assemblages experienced major changes in response to changes in dissolved oxygen concentration in ocean floor sediments foraminiferal assemblages are interpreted to represent three main groups representing oxic suboxic and dysoxic conditions assemblage changes in all three cores and hence in bottom water oxygenation coincided with late quaternary climatic episodes similar to that known for the southern california margin these episodes in turn are correlated with orbital and millennial climate episodes in the greenland ice core including the last glacial episode bolling allerod b a younger dryas preboreal earliest holocene early holocene and late holocene the lowest oxygen conditions marked by dysoxic taxa and laminated sediments in one core occurred during the b a and the preboreal intervals suboxic taxa dominated mainly during the last glacial the younger dryas and most of the holocene dysoxic conditions during the b a and preboreal intervals in this region were possibly caused by high surface water productivity at times of reduced intermediate ventilation in the northwestern pacific remarkable similarities are evident in the late quaternary sequence of benthic foraminiferal assemblage change between the two very distant continental margins of northern japan and southern california the oscillations in omz strength reflected by these faunal changes were widespread and apparently synchronous over wide areas of the north pacific reflecting broad changes in intermediate water ventilation and surface ocean productivity closely linked with late quaternary climate change on millennial and orbital timescales

seasonal variations of modern planktonic foraminifera in the south china sea although foraminiferal census and isotope analyses from sediment cores have been widely applied to paleoceanographic reconstructions in the south china sea scs their modern counterparts i e foraminiferal shells from sediment traps and plankton tows have been the subjects of few studies in this region in this investigation relative abundances of the most popular species used to reconstruct late quaternary tropical sea surface conditions have been studied in plankton tows from the scs in order to offer better constraints on the interpretation of downcore records in addition to the seasonal differences the spatial variations in the faunal assemblage are evident from south to north in the scs basin based on contemporary tows for example the species globigerinella aequilateralis is found to be relatively dominant in the southern lower latitude basin but its relative abundance is significantly higher in planktonic tows than in sediments indicating its proneness to burial dissolution pulleniatina obliquiloculata an index taxon for the kuroshio current is only abundant in the northern part of the scs basin the measured oxygen isotope compositions 18o of globigerinoides ruber globigerinoides sacculifer neogloboquadrina dutertrei and p obliquiloculata all show a good relationship with temperature in the mixed layer tmix the carbon isotope compositions 13c also display a positive distribution pattern relative to tmix but with a less significant correlation in winter months than 18o differences of 18o between shallower g sacculifer and g ruber and deep dwellers n dutertrei and p obliquiloculata accurately record the temperature gradient between the surface mixed layer and 100 m water depth supporting application of this proxy to the reconstruction of upper water column stratification

eocene seismicity in the pyrenees from megaturbidites of the south pyrenean basin spain abstract the triggering mechanism for emplacement of nine calcareous megaturbidites mt in the clastic turbidite eocene basin of the pyrenees is examined the thickness of each mt is 10 to 200 m and their volume may reach 200 km 3 their mobilization is thought to result from seismic activity related to thrust faults along the northern border of the basin we attempt to define the seismic characteristics for a volume of 100 km 3 the dimensions of the slope failures are estimated to be 100 5 10 0 1 0 2 km and related to a fault rupture length of about 50 100 km and liquefaction of basal clayey layers given these two constraints superficial earthquakes of m 7 would be required to initiate landslides

radiocarbon age anomaly at intermediate water depth in the pacific ocean during the last deglaciation 1 benthic and planktonic 14c ages are presented for the last glacial termination from marine sediment core vm21 30 from 617 m in the eastern equatorial pacific the benthic planktonic 14c age differences in the core increased to more than 6000 years between heinrich 1 time and the end of the younger dryas period several replicated 14c ages on different benthic and planktonic species from the same samples within the deglacial section of the core indicate a minimal amount of bioturbation scanning electron microscopy reveals no evidence of calcite alteration or contamination the oxygen isotope stratigraphy of planktonic and benthic foraminifera does not indicate anomalously old glacial age values and there is no evidence of a large negative stable carbon isotope excursion in benthic foraminifera that would indicate input of old carbon from dissociated methane it appears therefore that the benthic 14c excursion in this core is not an artifact of diagenesis bioturbation or a pulse of methane a benthic 14c stratigraphy reconstructed from the 14c ages from the deglacial section of vm21 30 appears to match that of baja margin core mv99 mc19 gc31 pc08 705 m but the magnitude of the low 14c excursion is much larger in the vm21 30 record this would seem to imply that the vm21 30 core was closer to the source of 14c depleted waters during the deglaciation but the source of this co2 remains elusive

the origin of the north pacific intermediate water possible source regions of the north pacific intermediate water npiw were investigated with synoptic conductivity temperature depth surveys in the okhotsk sea kuril basin a pycnostad referred to as the okhotsk sea mode water osmw was found in the density range of 26 6 27 the pycnostad is not seen in the western subarctic gyre wsag thus it is an indicative water peculiar to the okhotsk sea the maximum thickness is at 26 7 26 9 centered at 26 8 which coincides with the npiw density range in the north pacific subtropical gyre in the oyashio area east of the southern kuril islands and hokkaido waters that have intermediate temperature salinity and potential vorticity between the osmw and the wsag water were distributed suggesting a following transport route of the npiw source water the thick thus low q q is potential vorticity and low salinity water mass outflowing from the okhotsk sea mixes with the relatively warm saline and high q wsag water to form the oyashio water a coastal part of the oyashio water flows southwestward along the east coast of the southern kuril islands and hokkaido retaining the pycnostad q minimum a large part of the low q oyashio water flows further southward and merges with the kuroshio extension and then flows eastward forming new npiw in this process a salinity minimum develops and the q minimum disappears because of the mixing with a saline kuroshio water old npiw without a pycnostad in the npiw density range these results suggest that the origin of npiw is the water mass in the okhotsk sea osmw and the density of the water mass primarily determines the npiw density centered at around 26 8

the influence of seawater carbonate ion concentration co32 on the stable carbon isotope composition of the planktic foraminifera species globorotalia inflata abstract we sampled the upper water column for living planktic foraminifera along the sw african continental margin the species globorotalia inflata strongly dominates the foraminiferal assemblages with an overall relative abundance of 70 90 the shell 18o and 13c values of g inflata were measured and compared to the predicted oxygen isotope equilibrium values 18oeq and to the carbon isotope composition of the total dissolved inorganic carbon 13cdic of seawater the 18o of g inflata reflects the general gradient observed in the predicted 18oeq profile while the 13c of g inflata shows almost no variation with depth and the reflection of the 13cdic in the foraminiferal shell seems to be covered by other effects we found that offsets between 18oshell and predicted 18oeq in the surface mixed layer do not correlate to changes in seawater co32 to calculate an isotopic mass balance of depth integrated growth we used the oxygen isotope composition of g inflata to estimate the fraction of the total shell mass that is grown within each plankton tow depth interval of the upper 500 m of the water column this approach allows us to calculate the 13cinterval added dic i e the isotopic composition of calcite that was grown within a given depth interval our results consistently show that the 13cia dic correlates negatively with in situ measured co32 of the ambient water using this approach we found 13cia dic co32 slopes for g inflata in the large size fraction 250 355 m of 0 013 to 0 015 mol kg 1 1 and of 0 013 to 0 017 mol kg 1 1 for the smaller specimens 150 250 m these slopes are in the range of those found for other non symbiotic species such as globigerina bulloides from laboratory culture experiments since the 13cia dic co32 slopes from our field data are nearly identical to the slopes established from laboratory culture experiments we assume that the influence of other effects such as temperature are negligibly small if we correct the 13c values of g inflata for a carbonate ion effect the 13cshell and 13cdic are correlated with an average offset of 2 11

large fluctuations of dissolved oxygen in the indian and pacific oceans during dansgaard oeschger oscillations caused by variations of north atlantic deep water subduction a s and s h were supported by the paleoclimate program of the national science foundation as part of the paleovar project atm 0602395

deep water exchanges between the south china sea and the pacific since the last glacial period deep ocean circulation is widely considered as one of the important factors for increasing co2 concentration and decreasing radiocarbon activity 14c of the atmosphere during the last deglaciation the ams 14c ages of benthic and planktonic foraminifers from 18 samples of core md05 2904 water depth of 2066 m in the northern south china sea scs and 15 samples of core md05 2896 water depth of 1657 m in the southern scs were analyzed in this study for reconstructing the intrabasin deep oceanic processes and hence exploring the deep water exchanges between the scs and the pacific since the last glacial period the results show that during the holocene the average apparent ventilation age of deep water was younger in the southern scs 1350 years than in the northern scs 1850 years due to relatively strong vertical mixing and advection consistent with modern observations however during the last glacial period and deglaciation the deep water was older in the southern scs 2050 years and 1800 to 1200 years respectively than in the northern scs 1600 years and 670 years respectively indicating reduced deep mixing and advection moreover the northern scs deep water was significantly younger during the last deglaciation than during the holocene and the last glacial period implying the existence of northern sourced newly formed and relatively young north pacific deep water our records do not support the intrusion of anomalously 14c depleted deep water to the middepth of the low latitude western pacific and the scs during the mystery interval 17 5 14 5 kyr b p

calibration of mg ca thermometry in planktonic foraminifera from a sediment trap time series 1 paired mg ca and 18o measurements on planktonic foraminiferal species g ruber white g ruber pink g sacculifer g conglobatus g aequilateralis o universa n dutertrei p obliquiloculata g inflata g truncatulinoides g hirsuta and g crassaformis from a 6 year sediment trap time series in the sargasso sea were used to define the sensitivity of foraminiferal mg ca to calcification temperature habitat depths and calcification temperatures were estimated from comparison of 18o of foraminifera with equilibrium calcite based on historical temperature and salinity data when considered together mg ca mmol mol of all species except two show a significant r 0 93 relationship with temperature t c of the form mg ca 0 38 0 02 exp 0 090 0 003 t equivalent to a 9 0 0 3 change in mg ca for a 1 c change in temperature small differences exist in calibrations between species and between different size fractions of the same species o universa and g aequilateralis have higher mg ca than other species and in general data can be best described with the same temperature sensitivity for all species and pre exponential constants in the sequence o universa g aequilateralis g bulloides g ruber g sacculifer other species this approach gives an accuracy of 1 2 c in the estimation of calcification temperature the 9 sensitivity to temperature is similar to published studies from culture and core top calibrations but differences exist from some literature values of pre exponential constants different cleaning methodologies and artefacts of core top dissolution are probably implicated and perhaps environmental factors yet understood planktonic foraminiferal mg ca temperature estimates can be used for reconstructing surface temperatures and mixed and thermocline temperatures using g ruber pink g ruber white g sacculifer n dutertrei p obliquiloculata etc the existence of a single mg thermometry equation is valuable for extinct species although use of species specific equations will where statistically significant provide more accurate evaluation of mg ca paleotemperature

changes in intermediate water conditions in the northern south china sea using globorotalia inflata over the last 20 ka intermediate circulation is one of the crucial controls of thermohaline changes in seawater due to the lack of data for some of the more significant indicators there has been little research into past intermediate waters in the south china sea scs in particular little is known of the thermohaline properties of intermediate water here we present paired mg ca and 18o data for the planktonic foraminifera globorotalia inflata from core ghe27l in the northern scs these data provide records of temperature and residual 18oseawater 18oresidual being used as a proxy for salinity to tentatively investigate changes in the intermediate water of the scs over the last 20 ka our results show that g inflata in the scs grew principally within the 200 450 m water depth interval thermohaline changes recorded by g inflata indicate warm and relatively freshening water during the last glacial maximum lgm 20 17 7 ka bp changing to warm and saline waters between 17 7 and 13 6 ka bp in general waters during the 13 6 8 3 ka bp period were characterized by high temperatures and salinity with obvious millennial scale fluctuations after which during the holocene they became cold and fresh we suggest that the temperature and salinity of the intermediate water of the scs recorded by g inflata in core ghe27l were possibly associated with a switch in intermediate water masses during the lgm the intermediate water in the northern scs was mainly impacted by north pacific intermediate water npiw but that subsequently the influence of antarctic intermediate water strengthened during the last deglaciation and pre boreal period 17 7 8 3 ka bp after this period npiw was the principal control of the intermediate water of the scs again

in situ calibration of mg ca ratio in planktonic foraminiferal shell using time series sediment trap a case study of intense dissolution artifact in the south china sea this study examines mg ca temperature equations through the use of planktonic foraminifers collected from continuous time series sediment traps at four water depths in the south china sea this deployment provides an opportunity to refine partial dissolution artifacts and to identify responses of shell chemistry to changes in ambient seawater conditions paired mg ca and 18o measurements on shells are strongly correlated with seasonal variability in terms of temperature at specific habitat depths however partial dissolution can significantly alter mg ca ratios even at depths well above the calcite lysocline or carbonate compensation depth of the three species studied neogloboquadrina dutertrei is the most sensitive species to dissolution relative to the other surface dwelling species globigerinoides ruber and globigerinoides sacculifer differences between the mg derived temperature equation here and those from previously established core top or sediment trap calibrations can be attributed to various degrees of dissolution and lateral advection thus highlighting the need for in situ empirical calibration for different ocean basins

tropical forcing of north pacific intermediate water distribution during late quaternary rapid climate change abstract evidence is presented demonstrating intermediate water 500 m temperature variability at odp hole 893a in santa barbara basin during submillennial climate change 11 60 ka benthic 18 o oscillations are considered to result primarily from shifts in intermediate water temperature at the site detailed comparison of both benthic and planktonic records from the basin provide crucial evidence for differing surface and intermediate water mass temporal responses to rapid climate change gradual warming of intermediate water compared to abrupt cooling suggests mechanistic differences between processes controlling north pacific intermediate water expansion and contraction relative to southern component intermediate waters comparisons suggest intermediate water warming preceded by 60 200 years the most rapid interval of surface warming inferred to be associated with north pacific atmospheric reorganization tropical forcing of sea level anomalies in the eastern pacific via trade wind strength may control california undercurrent flow 300 500 m and be the cause of early intermediate water warming in santa barbara basin

planktonic foraminiferal records of east asia monsoon changes in the southern south china sea during the last 40 000 years planktonic foraminiferal assemblages and benthic foraminiferal oxygen isotopes were obtained in a gravity core n507 25 6 degrees 39 945 n 113 degrees 32 9361 e water depth 2006 m collected from the southern south china sea scs to investigate east asia monsoon changes during the last 40 000 years four cold events identified from four peaks of the relative abundance of neogloboquadrina pachyderma dex and globigerina quinqueloba correlate well with those in the hulu monsoon record within age uncertainty and can be linked to heinrich events in the northern atlantic high latitudes we suggest that the relative abundance of n pachyderma dex and g quinqueloba in the southern scs can be used as a direct proxy for east asia winter monsoon eawm changes during glacial periods in contrast to its low abundance in the northern scs and okinawa trough the relative abundance of pulleniatina obliquiloculata shows high values during the last glacial in the southern scs caused likely by the combined impact of optimum winter sea surface temperature sst and stronger mixing enhanced upwelling at that time a p obliquiloculata minimum event pme found in the okinawa trough and the northern and southern scs during the h1 period was possibly related to a large drop in winter sst due to the intensified eawm we propose that this pme can be also used as a reliable regional stratigraphic marker as the holocene one a 9 cm sandy silt layer deposit in core ns07 25 during the hi period probably related to the enhanced current that was caused by the especially strengthened eawm at that time the last deglacial warming recorded in the relative abundance of warm and cold species of planktonic foraminifer reveals that changes between the easm and eawm were not in phase but alternating between a winter monsoon dominated northern hemisphere influence and a summer monsoon dominated influence of the tropical dynamics and or southern hemisphere climate changes c 2009 elsevier b v all rights reserved

reconciling the hemispherical structure of earth s inner core with its super rotation earth s solid inner core grows through solidification of material from the fluid outer core onto its surface at rates of about 1 mm per year1 freezing in core properties over time and generating an age depth relation for the inner core a hemispherical structure of the inner core is well documented an isotropic eastern hemisphere with fast seismic velocities contrasts with a slower anisotropic western hemisphere2 3 4 independently the inner core is reported to super rotate at rates of up to 1 per year5 6 7 considering the slow growth steady rotation rates of this magnitude would erase frozen in regional variation and cannot coexist with hemispherical structure here we exploit the age depth relation using the largest available pkikp pkikp seismic travel time data set to confirm hemispherical structure in the uppermost inner core and to constrain the locations of the hemisphere boundaries we find consistent eastward displacement of these boundaries with depth from which we infer extremely slow steady inner core super rotation of 0 1 1 per million years our estimate of long term super rotation reconciles inner core rotation with hemispherical structure two properties previously thought incompatible it is in excellent agreement with geodynamo simulations8 9 while not excluding the possibility that the much larger rotation rates inferred earlier5 6 7 correspond to fluctuations in inner core rotation on shorter timescales10

the pathway and circulation of north pacific intermediate water 1 it has been speculated that the subtropical north pacific intermediate water npiw was formed by a shortcut of okhotsk sea source into the western subtropical gyre because this is the geographically shortest distance and based on incomplete data this mechanism is contradictory to the distribution of seawater properties and dynamically is inconsistent with a basin wide distribution of npiw and associated gyre circulation a lengthy transpacific pathway has been identified for the transformed npiw source waters that first enter the eastern subtropical gyre which is robust in a water mass age distribution using an updated hydrography and a water mass mixing scheme combining property distribution with flow streamfunction the present study establishes a dynamically self consistent gyre circulation of npiw and its pathway from the subpolar formation regions source to the indonesian throughflow sink

mg ca of globorotalia inflata as a recorder of permanent thermocline temperatures in the south atlantic 1 we present a species specific mg ca calcification temperature calibration for globorotalia inflata from a suite of 38 core top samples from the south atlantic from 8 s to 49 s g inflata is a deep dwelling planktonic foraminifer commonly occurring in subtropical to subpolar conditions which qualifies it for reconstructions of the permanent thermocline apparent calcification depths and calcification temperatures were determined by comparing measured 18o with equilibrium 18o of calcite based on water column properties based on our core top samples g inflata apparent calcification depth is constant throughout the south atlantic midlatitudes with a depth of 350 400 m within the permanent thermocline the resulting mg ca calcification temperature calibration is mg ca 0 72 0 045 0 042 exp 0 076 0 006 calcification temperature r2 0 81 and covers the temperature range 3 1 c 16 5 c we applied our mg ca calibration to gravity core ps2495 3 from the mid atlantic ridge at 41 s to test its validity by reconstructing a low resolution record covering the last two glacial interglacial cycles our paleotemperature record reveals large changes in temperature for terminations i and ii when permanent thermocline temperature increased by as much as 8 c the g inflata paleotemperature record suggests that oceanic fronts repeatedly migrated over the location of core ps2495 3 during the last 160 kyr this study shows the potential of g inflata mg ca to reconstruct paleotemperatures in the permanent thermocline

sea surface temperature variability and sea ice extent in the subarctic northwest pacific during the past 15 000 years past changes in north pacific sea surface temperatures and sea ice conditions are proposed to play a crucial role in deglacial climate development and ocean circulation but are less well known than from the north atlantic here we present new alkenone based sea surface temperature records from the subarctic northwest pacific and its marginal seas bering sea and sea of okhotsk for the time interval of the last 15 kyr indicating millennial scale sea surface temperature fluctuations similar to short term deglacial climate oscillations known from greenland ice core records past changes in sea ice distribution are derived from relative percentage of specific diatom groups and qualitative assessment of the ip25 biomarker related to sea ice diatoms the deglacial variability in sea ice extent matches the sea surface temperature fluctuations these fluctuations suggest a linkage to deglacial variations in atlantic meridional overturning circulation and a close atmospheric coupling between the north pacific and north atlantic during the holocene the subarctic north pacific is marked by complex sea surface temperature trends which do not support the hypothesis of a holocene seesaw in temperature development between the north atlantic and the north pacific key points millennial scale changes in sst in the north pacific during the last 15 kyr changes in sea ice extent suggest a close coupling to sst fluctuations middle to late holocene ssts show no clear sst trend in the north pacific