nannoplankton successions in the northern red sea during the last glaciation 60 to 14 5 ka bp reactions to climate change abstract due to its restricted connection with the indian ocean the desert enclosed red sea is extremely sensitive to global sea level changes and thus ideally suited for paleoceanographic studies of what occurred during the last glaciation the understanding of its glacial history is however still limited a serious obstacle to obtain satisfactory paleoecological information has been the rarity of microfossil proxy species caused by high salinities here we present a continuous and well dated calcareous nannoplankton record from the northern red sea covering the interval from 60 14 5 ka bp our investigation shows that the composition of the calcareous nannoplankton community varied between 32 ka bp and 14 5 ka bp in response to rapid environmental changes which are closely correlated to climatic fluctuations described from the north atlantic region heinrich events h3 h2 and h1 are dominated by emiliania huxleyi gephyrocapsa oceanica and especially gephyrocapsa ericsonii are abundant between h3 h2 and h2 h1 a less pronounced response of the calcareous nannoplankton to the high latitudinal climatic oscillations is documented prior to 32 ka bp suggesting that a strong atmospheric coupling between the northern red sea and the north atlantic realm was established in the late marine isotope stage 3 in contrast to the previously held view of a sea level related salinity increase as the major cause for changes of the plankton communities within the glacial red sea we interpret the documented variations as being caused by local hydrographic changes under the atmospheric control from the extratropics temperature changes and especially variations of the water stratification appear to be critical selective factors for the calcareous nannoplankton composition

precessional forcing of nutricline dynamics in the equatorial atlantic climate control of nutricline depth in the equatorial atlantic can be monitored by variations in the abundance of the phytoplankton species florisphaera profunda a conceptual model based on in situ evidence associates high abundances of f profunda with a deep nutricline and low abundances with a shallow nutricline a 200 000 year record of f profunda relative abundances obtained from a deep sea core sited beneath the region of maximum equatorial divergence at 10 w has 52 percent of its variance centered on the 23 000 year precessional band cross spectral analysis between the signals of f profunda and sea surface temperature independently derived from zooplankton species shows their 23 000 year cycles to be coherent and nearly in phase abundance minima of f profunda coincide with times of december perihelion whereas abundance maxima coincide with june perihelion these relations indicate that nutricline dynamics in the divergence region of the equatorial atlantic are controlled by variations in the tropical easterlies forced by the precessional component of orbital insolation on time scales greater than 10 000 years

tectono sedimentary constraints to the oligocene to miocene evolution of the peloritani thrust belt ne sicily abstract the peloritani thrust belt belongs to the southern sector of the calabrian arc and is formed by a set of south verging tectonic units including crystalline basement and sedimentary cover from the top aspromonte u mela u mandanici u fondachelli u longi taormina u piled up starting from late oligocene at least two main terrigenous clastic formations lie with complicated relationships on top of the previous units the frazzano fm oligocene and the stilo capo d orlando fm late oligocene early miocene as syn to post tectonic deposits these clastic deposits have different characteristics in space and time representing or flysch like sequences involved in several thrust events frazzano fm or molassic like sequences stilo capo d orlando fm which unconformably overlie the tectonic units in the present paper we describe a kinematic model of the progressive foreland migration of the peloritani thrust belt starting from oligocene carrying piggy back basins and incorporating foredeep deposits recognised in the frazzano stilo capo d orlando terrigenous successions in general the facies and structural observations on the overall oligo miocene clastic sequences outcropping in the western peloritani mts indicate a the distal character of the frazzano fm b a complex group of terrigenous facies of the stilo capo d orlando fm with lateral to vertical organisation characterised by a distal to proximal to distal facies trend c facies analogies of the basal portions of the stilo capo d orlando fm with the frazzano fm d the involvement of the frazzano fm in lowermost and more external thrusting and of the basal late oligocene distal stilo capo d orlando facies in the higher and inner thrusting during the early stages of deformation e the involvement of the proximal stilo capo d orlando facies in the tectonic edifice during the early miocene deformation f the generally unconformable stratigraphical contacts of the higher proximal to distal early miocene stilo capo d orlando facies on the constructing mobile belt and g the presence of various thrust faults distinguished in a sequential order the collected data allow us to hypothesise that the oligo miocene tectono sedimentary history was characterised by a foredeep with a deforming internal flank probably lying in onlap on the constructing tectonic edifice frazzano lower stilo capo d orlando fms and then deformed and covered by a piggy back like sequence middle upper stilo capo d orlando fm which was subsequently also deformed the tectono sedimentary evolution of the peloritani belt has been probably developed through a progressive migration towards the foreland of a foredeep compressional front couple and the chain body the thrust stack progressively incorporates terrigenous foredeep deposits and in turn carried piggy back basins

quantitative analysis of quaternary nannoplankton in the subtropical northwestern pacific ocean abstract time progressive changes of nannoflora and biometry of coccoliths for the last 1 3 m y were investigated for a piston core recovered from the west mariana ridge the species compositions were quantitatively investigated under an electron microscope and six assemblages assemblages a through f were identified significant changes in relative abundances of various types of genus gephyrocapsa are the main cause for the stratigraphic change of the flora a dominant occurrence of gephyrocapsa protohuxleyi var a which can be identified only under an electron microscope was observed for the first time in a thin sequence which corresponds to the lowest part of the brunhes epoch 0 75 0 62 ma because of this characteristic occurrence assemblage d was further subdivided into three subassemblages the dominant occurrence of small gephyrocapsa which is well known in the small gephyrocapsa zone of the equatorial pacific ocean was not observed but the almost complete absence of medium to large gephyrocapsa during approximately 200k years of the middle pleistocene was confirmed a stratigraphically restricted occurrence of a large form of reticulogenestra was also confirmed by the biostratigraphic study under a light microscope and the last and first occurrences of the largest form reticulofenestra sp a 6 5 m were identified at 0 81 and 0 98 ma respectively in addition to these four events precise ages for another five well known evolutionary events were also calibrated these ages are generally in good agreement with previously reported ages from other world oceans and diachronism was not evident for most of these evolutionary events

paleoceanography of the mid pleistocene the fossil record of the pleistocene calcareous nannoplankton indicates that during the mid pleistocene 0 93 1 25 my occurred an episode of overwhelming dominance of smallgephyrocapsa during this episode normally abundant large size specimens of this genus mainlygephyrocapsa oceanica were virtually excluded from the phytoplankton of tropical and subtropical oceans the best modern analog of this dominantly smallgephyrocapsa assemblage is the subpolaremiliania huxleyi assemblage which implies that nutrient content was significantly greater and water temperature was lower in the photic water column of the tropical oceans than they are today increased equatorial upwelling in the oceans on a scale much greater than today may explain the above pattern to achieve such broad equatorial upwelling there must be a source and a drive for cold dense water the arctic ocean which was probably seasonally free of ice during this interval of the mid pleistocene is capable of providing the requisite source as well as a drive for the inferred equatorial upwelling the energy balance of a predominantly ice free arctic ocean requires an approximately three to seven fold increase of hydrospheric heat transport from the north atlantic to the arctic ocean which dictates a corresponding or even greater increase in the volume of warm water entering the arctic ocean at the surface and cold dense water exiting at depth to the north atlantic such enhanced dense water formation in the arctic ocean could drive the intensified equatorial upwelling implied by the smallgephyrocapsa dominance interval if the above scenario is correct then the climate of the earth s northern hemisphere during the mid pleistocene may have been very different from the younger pleistocene climate one manifestation of this difference may be the mid pleistocene shift in climatic cycle periodicity from 40 ky to 100 ky another important aspect is that the enhanced greenhouse effect expected during the next century because of an increase of atmospheric co2 is thought to lead directly to melting of the arctic ocean ice cover and of the greenland ice sheet thus the greenhouse arctic ocean and its attendant ocean circulation would resemble the inferred mid pleistocene conditions

subtropical front fluctuations south of australia 45 09 s 146 17 e for the last 130kayears based on calcareous nannoplankton abstract calcareous nannoplankton assemblages from a late quaternary deep sea core gc07 46 09 s 146 17 e south of australia provide information on regional palaeoceanography and palaeoclimate changes in the southern ocean in particular the movement of the subtropical front for the past 130 ka years marine isotope stages 1 5 are identified through changes in calcareous nannoplankton assemblages supported by 14c dates and oxygen isotope and caco data two distinct assemblages are recognised a warm water assemblage with higher abundances of calcidiscus leptoporus emiliania huxleyi helicosphaera carteri syracosphaera pulchra gephyrocapsa caribbeanica and gephyrocapsa oceanica and a cold water assemblage with higher abundances of gephyrocapsa muellerae and coccolithus pelagicus alternation between these two assemblages downcore in gc07 reflect movement of the subtropical front across the location and can be correlated to marine isotope stages mis 1 5 sediments with a cold water assemblage indicate the position of the subtropical front equatorward of the site when transitional to sub antarctic waters were overlying the site conversely sediments with a warm water assemblage indicate the subtropical front was poleward of gc07 when warmer subtropical waters were over the site mis 1 and 5 are interpreted as warmer than mis 3 based on species composition with the subtropical front more poleward than for mis 3 during mis 3 the subtropical front is interpreted as adjacent to or immediately poleward of gc07 some species including c leptoporus and c pelagicus show negative covariance and are considered to be reliable species in identifying glacial and interglacial intervals in this region comparison with established biostratigraphy based on calcareous nannoplankton showed the datum event for the reversal between e huxleyi and g muellerae of 73 ka in transitional waters is not applicable in this region the reversal between these two species occurs between 48 and 30 cm downcore in gc07 with a 14c date of 11 020 year bp at 49 48 cm i e the reversal event is younger than this date

southern ocean deglacial record supports global younger dryas abstract in northern hemisphere deglaciation records the transition from the last glacial to the holocene indicates a rapid return to near glacial conditions during the younger dryas whereas their southern hemisphere ice core counterparts record two separate cooling events the antarctic cold reversal and the oceanic cold reversal spatial distribution and relative timing of these events in both hemispheres are central for our understanding of causes and mechanisms of abrupt climate change to date no marine record from the southern mid latitudes conclusively demonstrates that the younger dryas was a significant event in the southern ocean here we present high resolution oxygen isotope and iron content records of a radiocarbon dated sedimentary sequence from the great australian bight which constrains oceanic and atmospheric changes during the last deglaciation oxygen isotopes from planktonic foraminifera indicate two rapid cold reversals between 13 1 and 11 1 kyr bp separated by a brief warming the sedimentary iron content interpreted as a proxy for wind strength indicates a simultaneous change in atmospheric circulation pattern both records demonstrate the existence of cooling events in the southern hemisphere which are synchronous with the northern hemisphere younger dryas cold reversal between 12 9 and 11 5 kyr bp such evidence for the spatial distribution and timing of abrupt climatic fluctuations is essential data for groundtruthing results derived from global climate models

late quaternary nannofossil indicators of climate change in two deep sea cores associated with the leeuwin current off western australia the stratigraphic variations in nannoflora observed in the two deep sea cores recovered from the offshore western australia revealed a sequence of paleoceanographic changes for the last 250 kyr the dominance of small placolith taxa in the upper photic flora indicates continuous mild upwelling for the isotope stages 7 5 in this region the most important controlling factor for the abundance variation of florisphaera profunda in this region is considered to be the lower photic temperature rather than the stability of water column or the water turbidity the significant reduction in the abundance of f profunda combined with the stable in the northern core rs96gc21 and reduced in the southern core rs9 150 abundance of the small taxa suggest an intensified upwelling for the penultimate glaciation the sharp increase in f profunda abundance indicates a weakening of upwelling at the last interglacial climax lic offshore western australia after isotope stage 5 the existence of upwelling is not clear except in stage 2 when it was not strong enough to produce blooms of emiliania huxleyi among the subordinate taxa calcidiscus leptoporus calciosolenia murrayi neosphaera coccolithomorpha and oolithotus fragilis provide meaningful paleoceanographic signals supporting the conclusions of previous studies a weakening or cessation of leeuwin current for the glacial periods the shift of dominance from small gephyrocapsa mostly g ericsonii to small reticulofenestra mostly r parvula can be an useful datum event offshore western australia the reduced diversity of nannoflora during the interglacial periods can be explained by a lessened competition within nannoplankton community caused by particularly favorable conditions for the opportunists such as e huxleyi f profunda and small placoliths the variations in nannofossil abundance suggests an increased aeolian flux at the stages 6 and 2 offshore north west cape as well as at stage 6 offshore southwestern australia

calcareous nannofossil biostratigraphy biochronology and paleoecology at the tortonian messinian boundary of the faneromeni section crete abstract a detailed calcareous nannofossil analysis was performed on 180 samples from the astronomically dated faneromeni section to identify the most important calcareous nannofossil events across the tortonian messinian t m boundary in the mediterranean and to date and correlate them precisely to the previously observed sections here we confirm the reliability of the genus amaurolithus the successive entries of amaurolithus primus amaurolithus aff amplificus and amaurolithus delicatus have been dated at 7 430 7 388 and 7 250 ma respectively the first occurrence and the first common occurrence of reticulofenestra rotaria are further confirmed bioevents dated at 7 421 and 7 264 ma these events improve the biostratigraphic resolution in the t m boundary interval at least for the mediterranean quantitative analysis revealed marked changes in the calcareous nannofossil assemblage associated with the sapropels as previously observed in other sections of the same time interval a decrease in the total number of coccoliths but an increase in abundance of the genera rhabdosphaera and helicosphaera characterize sapropels the observed fluctuations are comparable to the previous findings in neogene mediterranean sapropel sediments and suggest that similar mechanisms were responsible for their formation during this interval the possible influence of preservation on nannofossil assemblages is discussed

calcareous nannofossils and the origin of eastern mediterranean sapropels a quantitative analysis of calcareous nannofossil assemblages was carried out with an optical microscope on four deep sea cores raised from the eastern mediterranean and selected to form a nw se transect a total of 748 samples were studied including a very detailed analysis of sapropels s5 and s6 in two out of the four cores this paper is restricted to the discussion of the results obtained on florisphaera profunda which provided important insights on the mechanisms of sapropel formation an intricated and unravelled puzzle for the scientists of the last decades on the basis of abundance variations of f profunda the only species of calcareous nannoplankton which inhabits the lower part of the photic zone i suggest that sapropel formation was triggered by increased primary production either confined to a deep chlorophyll maximum dcm a concept previously introduced by rohling and gieskes 1989 or extended to a thicker layer of the photic zone when increased primary production was confined to the dcm sapropel s3 s4 s5 s7 and s1 this latter only in the eastern part of the basin the abundance of f profunda was enhanced greatly with respect to all other species living in the higher part of the photic zone on the contrary when the increased primary production was extended to a thicker layer of the photic zone glacial sapropels s6 and s8 the production of most nannoplankton species was favored decreasing the relative proportion of f profunda

the last interglacial ocean the final effort of the climap project was a study of the last interglaciation a time of minimum ice volume some 122 000 yr ago coincident with the substage 5e oxygen isotopic minimum based on detailed oxygen isotope analyses and biotic census counts in 52 cores across the world ocean last interglacial sea surface temperatures sst were compared with those today there are small sst departures in the mid latitude north atlantic warmer and the gulf of mexico cooler the eastern boundary currents of the south atlantic and pacific oceans are marked by large sst anomalies in individual cores but their interpretations are precluded by no analog problems and by discordancies among estimates from different biotic groups in general the last interglacial ocean was not significantly different from the modern ocean the relative sequencing of ice decay versus oceanic warming on the stage 6 5 oxygen isotopic transition and of ice growth versus oceanic cooling on the stage 5e 5d transition was also studied in most of the southern hemisphere the oceanic response marked by the biotic census counts preceded led the global ice volume response marked by the oxygen isotope signal by several thousand years the reverse pattern is evident in the north atlantic ocean and the gulf of mexico where the oceanic response lagged that of global ice volume by several thousand years as a result the very warm temperatures associated with the last interglaciation were regionally diachronous by several thousand years these regional lead lag relationships agree with those observed on other transitions and in long term phase relationships they cannot be explained simply as artifacts of bioturbational translations of the original signals

paleoenvironmental conditions at core kc01b ionian sea through mis 13 9 evidence from calcareous nannofossil assemblages quantitative analyses on calcareous nannofossil assemblages on high temporal resolution 600e800 years have been carried out from core kc01b in the ionian sea eastern mediterranean throughout marine isotope stage mis 13e9 between 500 and 300 ka this is an interval of considerable climate changes known as the mid brunhes event which includes mis 11 considered as a possible analogue for future interglacial conditions in the mediterranean core the interval is characterized by the dominance of gephyrocapsaspp as also known fromocean records calcareous nannofossil abundance fluctuations have been interpreted in terms of modification of sea surface primary productivity water stratification and temperature specifically the increase in abundance of gephyrocapsa caribbeanica and small gephyrocapsa coupled with decreases of florisphaera profunda syracosphaera spp and rhabdosphaera spp suggests enhanced primary productivity mixed surface waters during interglacial stages and at the terminations which can be interpreted in terms of interaction between climate changes and mesoscale oceanographic circulation on the other hand distributions of calciosolenia spp oolithotus spp and umbilicosphaera sibogae which are inphase with d 18 o curve showing higher abundances at the lighter values of the marine

florisphaera profunda a possible nannoplankton indicator of late quaternary changes in sea water turbidity at the northwestern margin of the pacific three piston cores from the ryukyu trench slope northwestern margin of the pacific ocean contain nearly continuous paleoceanographic records of the last 320 165 and 105 kyr ages of the cores are constrained by planktic 18o stratigraphy and roughly substantiated by the presence of two calcareous nannofossil events spectral analysis of the changes in relative abundance offlorisphaera profunda a nannoplankton species presently living in the lower euphotic zone reveals a maximum power at 0 01 cycles kyr corresponding to the 100 kyr cycle of orbital eccentricity much lower power is observed at the 23 kyr precessional band this differs from the equatorial atlantic ocean variations which show dominant power in the 23 kyr precessional band in the changes off profunda abundances molfino and mcintyre 1990a besides our cores were taken outside the equatorial divergence zone we also show a rather close relationship betweenf profunda abundance and sea water transparency secchi depth in the present northwest pacific based on data from 204 sites of surface sediment samples because sea water transparency is primarily affected by bio productivity change in open ocean stratigraphic changes off profunda abundances in our cores seem to have been caused by productivity change as well pointed out by molfino and mcintyre 1990a b a mechanism proposed by them for its change however is not applied to our cases due to differences in spectral analysis results and in geographic situation alternatively we suggest that geographic change of the northwestern margin of the pacific during the late quaternary causedf profunda abundance change through the sea water turbidity change which has been affected not only by bio productivity but also by land origin particles supply

history of the last deglaciation in the alboran sea western mediterranean and adjacent north atlantic as revealed by coccolith floras abstract a series of cores recovered from the alboran sea western mediterranean and the adjacent part of the north atlantic has revealed very high rates of accumulation which have enabled us to identify the stages of the last deglaciation in great detail isotopic analyses of the cores show the two steps of the deglaciation terminations 1a and 1b separated by the bolling allerod warm phase 14 c dating of the cores has allowed the dating og the climatic succession we have identified each event of the deglaciation on the basis of changes in the coccolith flora especially in species of the genus gephyrocapsa such changes reflect surface water changes since coccolith live only in the photic zone the abundance of g muellerae in the cold intervals prior to each termination is greater than that in the bolling allerod and holocene warm intervals which follow the terminations coversely g oceanica is virtually absent during cold intervals but becoms more common during the warmer periods during the first deglacial warming there is a large influx of fine grained detrital material presumably derived from increased run off from the nearby mountains of southern spain and north west africa in the alboran sea cores with the most expanded sections there is a marked increase in the percentage of syracosphaera histrica at the beginning of this increase of detritus no increase was found in the atlantic core at this time

response of deep sea benthic foraminifera to late quaternary climate changes southeast indian ocean offshore western australia the late quaternary benthic foraminifera of four deep sea cores off western australia odp 122 760a odp122 762b bmr96gc21 and rc9 150 have been examined for evidence of increased surface productivity to explain the anomalously low sea surface paleotemperatures inferred by planktic foraminifera for the last and penultimate glaciations the 13c trends ofcibicidoides wuellerstorfi and differences between the 13c trends of planktics globigerinoides sacculifer and benthicsc wuellerstorfi in the four cores indicate that during stage 6 bottom waters were significantly depleted in 13c and strong 13c gradients were established in the water column while during stage 2 and the last glacial maximum 13c trends did not differ greatly from that of the holocene two main assemblages of benthic foraminifera were identified by principal component analyses one dominated byuvigerina peregrina another dominated byu proboscidea abundance of these uvigerinids and of taxa preferring an infaunal microhabitat and ofepistominella exigua andbulimina aculeata indicate that episodes of high influx of particulate organic matter were established in most sites during glacial episodes and particularly so during stage 6 while evidence for upwelling during the last glacial maximum is less strong the penultimate glaciation upwellings were established within the areas of low sea surface paleotemperature indicated by planktic foraminifera during the last interglacial climax upwelling appears to have been established in an isolated region offshore from a strengthened leeuwin current off north west cape last glacial maximum 13c values ofc wuellerstorfi at waterdepths of less than 2000 m show smaller than global mean glacial interglacial changes suggesting the development of a deep hydrological front a similar vertical stratification bathyal front was also established during the penultimate glaciation

floral and solution patterns of coccoliths in surface sediments of the north pacific coccolith assemblages from core top samples of the north pacific seafloor follow the distribution of surface water masses gephyrocapsa caribbeanica umbellosphaera tenuis and coccolithus pelagicus are the most important identifiers of surface water mass different multivariate statistical techniques group shallow samples in somewhat different spatial patterns factor analysis condenses the information contained in sixteen ies percentages to four new variables that can be interpreted as species assemblages by canonical correlation analysis these assemblages can in turn be related to the environment the first canonical correlation indicates that factor 2 the g caribbeanica assemblage is represented in samples underlying cooler surface water a second possible correlation describes a direct relationship between factor 3 the umbilicosphaera sibogae assemblage and the remaining environmental variable surface water salinity factor 1 the g oceanica assemblage and factor 4 the emiliania huxleyi assemblage are not as closely related to the selected environmental measures of temperature salinity dissolved oxygen and inorganic phosphate phosphorus as are factor 2 and factor 3 because samples were coded according to their overlying water mass group separations produced by discriminant analysis are easily interpreted in terms of the environment overlap of group assignments occurs for samples from the south china sea and extreme western pacific even partially dissolved samples retain the signature of surface water mass group assignment for those samples is generally reliable with the exception of samples from the central water mass where almost half of the shallow and half of the deep samples show strongest affinities with one of the other three water masses selective solution therefore only partially obscures the record of floral provinciality partial dissolution of coccolith assemblages does not proceed according to one systematic rank order the sequence of species removal is variable from region to region the more abundant species tend to consistently appear at an extreme of the ranking for example umbilicosphaera sibogae is among the least resistant and c leptoporus and g oceanica are among the most resistant species maximum depths of coccolith lysocline and compensation depth occur generally in the central part of the basin and shoal towards its margins as previously observed for planktonic foraminifera

statistical description of seismic reflection wavefields a step towards quantitative interpretation of deep seismic reflection profiles summary seismic modelling designed to compare the statistics of a realistic acoustic impedance field with a statistical description of the resulting backscattered wavefield demonstrates a strong correlation between the spatial properties of the impedance field and the resulting wavefield experiments in the weak and strong scattering regimes indicate significant and predictable differences in the spatial properties of the wavefield depending upon the scattering mode wavefields generated in a mixed scattering regime with concurrent weak and strong scattering are dominated by the strong scattering response the results of these experiments suggest that the statistical description of reflection wavefields may provide a basis for the quantitative interpretation of the complex reflection wavefields most commonly observed in seismic reflection profiles across crystalline basement rocks and a tool for extracting more of the information content of the seismic data

calculating erosion by deep sea turbidity currents during initiation and flow turbidity currents transport massive amounts of sediment from continental margins to the deep sea individual flows can catastrophically remove and redeposit as turbidites many hundreds of cubic kilometres of material1 2 with the larger events reaching the bottom of the continental slope to form the abyssal plains3 here we show that the age range of sediments in individual turbidites can be used directly to estimate both the thickness of failed sediment in the source region even when its exact location is unknown and the extent to which the turbidity current caused erosion of the sea bed our method involves the comparison of the abundance ratios of microfossil coccolith species in turbidites with those in the ocean margin sediments of the source region analysis of a recently emplaced turbidite on the madeira abyssal plain shows that it contains a mixture of sediments with an age range of about 200 000 years equivalent to the failure of a block of sediment about 15 m deep radiocarbon dating and coccolith ratios show that the turbidite contains only about 12 of recent near surface sediment indicating that this turbidity current caused surprisingly little erosion en route

large scale reorganization of ocean currents offshore western australia during the late quaternary abstract the history of coastal surface currents in the eastern indian ocean over the last 130 kyr has been studied through the application of the fi 2 transfer function to planktic foraminifera in deep sea cores in a n s transect offshore western australia the concept of sea surface temperature sst gradient residuals is the amount by which the sea surface temperature gradient of a given time differs from that in the modern sea the sst gradient residuals for several episodes of climate extremes in the late quaternary the last glacial maximum 20 kyr b p the last interglacial maximum 122 120 kyr b p and at the end of the penultimate glaciation 130 kyr b p indicate that areas north of 18 s off western australia have changed very little during the extremes in climate over the last 130 kyr while south of 18 s there have been significant changes in surface water temperatures large areas of anomalously cool surface water were established off north west cape 22 s 24 s during both glacial and interglacial extremes these reflect the increased influence of the west australian current on the surface water circulation during the last glacial maximum and at the end of the penultimate glaciation cold sea surface temperature anomalies were established near to the coast indicating that the leeuwin current did not warm the coastal zone as it does today during the last interglacial maximum the leeuwin current flowed as an intensified current in a narrow zone close to the coast but did not significantly warm surface waters offshore as far as 20 25 s where a zone of cold water was maintained

nutricline variation in the equatorial atlantic coincident with the younger dryas variations in nutricline depth during the last deglaciation are recorded by the phytoplankton species florisphaera profunda a stacked record of six deep sea cores shows that across the entire equatorial atlantic there was a brief shallowing of the nutricline centered on 11 ka coincident with the younger dryas this shallowing is linked with high latitude north atlantic deglacial events we invoke high albedo and cool sea surface temperatures in the northern latitudes during 11 ka which steepened an already higher than expected winter insolation and hence temperature gradient for a time of june perihelion we postulate that the resultant increased pressure gradient caused an intensification of the northern hemisphere winter tropical easterlies which in turn caused equatorial divergence to occur in boreal winter

age dating and the orbital theory of the ice ages development of a high resolution 0 to 300 000 year chronostratigraphy using the concept of orbital tuning a continuous high resolution deep sea chronostratigraphy has been developed spanning the last 300 000 yr the chronology is developed using a stacked oxygen isotope stratigraphy and four different orbital tuning approaches each of which is based upon a different assumption concerning the response of the orbital signal recorded in the data each approach yields a separate chronology the error measured by the standard deviation about the average of these four results which represents the best chronology has an average magnitude of only 2500 yr this small value indicates that the chronology produced is insensitive to the specific orbital tuning technique used excellent convergence between chronologies developed using each of five different paleoclimatological indicators from a single core is also obtained the resultant chronology is also insensitive to the specific indicator used the error associated with each tuning approach is estimated independently and propagated through to the average result the resulting error estimate is independent of that associated with the degree of convergence and has an average magnitude of 3500 yr in excellent agreement with the 2500 yr estimate transfer of the final chronology to the stacked record leads to an estimated error of 1500 yr thus the final chronology has an average error of 5000 yr