variations in high latitude oceanographic fronts in the southern indian ocean an estimation based on faunal changes a quantitative estimate of the magnitude of late pleistocene holocene variations in the migration of siliceous microfauna is calculated from fossil assemblages preserved in marine sediments from piston cores located in the southeast indian ocean sector of the subantarctic results of this modern analog technique indicate that fauna characteristic of colder waters today occupied surface and near surface waters overlying the core sites for much of the last half million years warm water fauna inhabited these waters for only brief time periods usually during the early portion of interglacial isotopic stages the estimated faunal migration pattern from the most southern sites is similar in most respects to that of atmospheric temperatures over antarctica recorded in the vostok ice core a model of changes in the positions of the subtropical convergence and the antarctic polar front constructed from time series of faunal variations indicates that although southward migrations of these oceanographic fronts in this region of the southern ocean were limited to approximately 4 of latitude northward displacements were of the order of 5 to 7 of latitude fauna at the antarctic polar front react earlier than either the fauna at the subtropical convergence or the global ice volume signal to major global warming terminations providing further documentation of the early response of the high latitude southern ocean relative to other components of the climate system to the various factors forcing pleistocene climate

genesis of palimpsest cool water carbonate sediment on the continental margin of southern australia abstract the continental margin of southern australia is a site of extensive quaternary cool water carbonate sedimentation seafloor sediments are a mixture of holocene biofragments and late pleistocene relict and stranded particles relict sediments produced during marine isotope stages 3 and 4 are generally preserved as iron stained intraclasts such grains in the great australian bight are photozoan in character they include symbiont bearing benthic foraminifers and coralline algal particles and indicate that the wide shelves were bathed in shallow relatively warm oligotrophic waters and floored by marine grasses similar to many modern shallow inboard embayments in the region today in contrast east of the great australian bight relict sediments are more heterozoan in character with coralline algal and molluscan facies on the inner shelf and bryozoan sediments on the outer shelf stranded sediments marooned during the sea level rise associated with marine isotope stage 2 are gray to buff in color and composed of both biofragments and intraclasts these particles are mainly heterozoan in character throughout the region with subtropical photozoan marine grassbank facies localized to portions of the inner great australian bight stranded sediments are interpreted to have accumulated in an areally restricted photic zone and upon an overall narrow shelf covered in cool nutrient rich waters swell driven seafloor sediment disturbance to depths of 100 m along the southern australian margin in conjunction with reduced rates of sedimentation that characterize the cool water carbonate realm have resulted in mixing of sediment currently being produced with exhumed relict and stranded sediments generated during previous sea level stands the composition of these deposits and the nature of their pre burial alteration are a function of sea level history late pleistocene relict sediments originally accumulated in low energy inboard environments but were modified in the surf zone during subsequent sea level fluctuations this resulted in the formation of intraclasts abraded infilled and cemented biofragments of local origin the widespread distribution of intraclasts and of composite grain assemblages derived from multiple sedimentary environments that display highly variable degrees of seafloor alteration may be signatures of modern cool water carbonate assemblages worldwide while such palimpsest sediments may complicate paleoenvironmental interpretation their differentiation in the rock record can be utilized to discern subtleties in paleoceanography and sea level history

southern ocean bottom water of the australian new zealand sector the bottom water characteristics of the southeast indian ocean and southwest pacific ocean reveal northward transfer of cold water across the mid ocean ridge at the discordance zone near 120 e and at the balleny fracture zone near 155 e a principal northward flow which transfers cold continental margin waters of antarctic origin to lower latitudes within the south indian basin occurs to the east of kerguelen plateau within the south indian basin near the 0 c isotherm the s o2 and si relations display significant slope changes the more variable water below 0 c is of local origin while the water above 0 c represents larger scale regional effects

a diatom and benthic foraminiferal record from the south tasman rise southeastern indian ocean implications for palaeoceanographic changes for the last 200 000 years abstract the last two glacial interglacial cycles represented in core md88 779 in the southeastern indian ocean over the south tasman rise 47 50 69 s 146 32 75 e 2260 m water depth have been analysed an oceanographic reconstruction for this region is presented based principally on the recovery of benthic foraminiferal and diatom assemblages the most striking feature of the microfossil record from core md88 779 is the lack of diatoms during glacials despite evidence of high oceanic productivity benthic foraminiferal data suggest significant increases in ocean surface productivity during glacial periods and in particular during isotopic stages 2 late 3 and 6 for these periods of elevated surface productivity substantial and at times total dissolution of diatom frustules occurred we propose that increased influx of aeolian dust and especially associated iron during glacial periods may have reduced the intake of silica in diatoms thus resulting in less silicified diatoms additionally winnowing is suggested to have removed remaining frustules from the sedimentary record increased productivity at the sea surface is indicative that both the subtropical front and the subantarctic front may have shifted northward during glacial periods and that the subantarctic front was near the coring site on the south tasman rise for these periods we also postulate based on diatom floral evidence that southward moving eddies generated by the subtropical east australian current may have intermittently reached the coring site even during glacial periods

climatic records over the past 30 ka from temperate australia a synthesis from the oz intimate workgroup temperate australia sits between the heat engine of the tropics and the cold southern ocean encompassing a range of rainfall regimes and falling under the influence of different climatic drivers despite this heterogeneity broad scale trends in climatic and environmental change are evident over the past 30 ka during the early glacial period 30 22 ka and the last glacial maximum 22 18 ka climate was relatively cool across the entire temperate zone and there was an expansion of grasslands and increased fluvial activity in regionally important murray darling basin the temperate region at this time appears to be dominated by expanded sea ice in the southern ocean forcing a northerly shift in the position of the oceanic fronts and a concomitant influx of cold water along the southeast including tasmania and southwest australian coasts the deglacial period 18 12 ka was characterised by glacial recession and eventual disappearance resulting from an increase in temperature deduced from terrestrial records while there is some evidence for climatic reversals e g the antarctic cold reversal in high resolution marine sediment cores through this period the high spatial density of holocene terrestrial records reveals an overall expansion of sclerophyll woodland and rainforest taxa across the temperate region after 12 ka presumably in response to increasing temperature while hydrological records reveal spatially heterogeneous hydro climatic trends patterns after 6 ka suggest higher frequency climatic variability that possibly reflects the onset of large scale climate variability caused by the el nino southern oscillation

oceanographic and climatic changes over the past 160 000 years at deep sea drilling project site 594 off southeastern new zealand southwest pacific ocean high resolution textural carbonate microfossil and oxygen 18o and carbon 13c stable isotopic analyses are presented for the late quaternary isotopic stages 1 to 6 interval of a core at deep sea drilling project site 594 situated just south of the present subtropical convergence in northernmost subantarctic surface waters on the southern flank of chatham rise in the southwest pacific downcore alternations of pelagic and hemipelagic oozes correspond to interglacial and glacial episodes respectively interglacial oozes contain a northern subantarctic assemblage of planktonic foraminifera with rare cool subtropical species while glacial oozes are characterized by species typical of southern most subantarctic waters and include radiolaria with affinity for antarctic waters the planktonic 18o record for the site supports a 3 6 c temperature change in near surface waters between interglacial and glacial stages and indicates that during stage 5e the near surface waters were about 1 c warmer than at present a pronounced cooling during stage 5d matches that of the vostok ice core d record and negative excursions at the end of stages 2 and 6 support a southern latitude warming preceding northern hemisphere deglaciation benthic foraminifera typical of cold intermediate to deep waters can increase dramatically in abundance in the hemipelagic ooze intervals when 18o results suggest a temperature drop in glacial stage bottom waters of 2 4 c possibly a result of upward displacement of antarctic intermediate water by circumpolar deep water at the site the foraminiferal 13c records support a reduced influence of north atlantic deep water in the southwest pacific during glacial stages when nutrient enhancement occurred in both bottom and surface waters despite the pronounced changes between interglacial and glacial conditions inferred at site 594 contributed to by a substantial northward shift by at least 5 of latitude in the position of the antarctic convergence south of new zealand during glacial episodes we conclude that the subtropical convergence remained locked to chatham rise approximately 44 s throughout stages 1 to 6 major compression of the intervening belt of subantarctic water during glacial episodes and the associated very steep thermal gradients and intensified atmospheric and oceanic circulation patterns that developed in this part of the southwest pacific account for the harsh frigid environment reported for on land southern new zealand at these times

late quaternary productivity changes from offshore southeastern australia a biomarker approach reconstructions of primary productivity at low latitudes have been the focus of several studies to better understand how the export of nutrient rich intermediate southern ocean so waters influences productivity at these latitudes this was triggered by the general observation of minima in the planktonic foraminiferal delta c 13 values during deglaciations which was interpreted as an isotopic signal of intermediate so waters together with a concomitant increase in diatom productivity at some equatorial sites however the impact of these so waters on productivity at higher latitudes is not well constrained here we compare a high resolution planktonic foraminiferal delta c 13 record with total organic carbon and biomarker records for proboscia diatoms and haptophytes in marine sediments from offshore southeastern australia the planktonic foraminiferal delta c 13 record shows distinct minima during deglaciations and the marine isotope stage 4 3 transition tentatively suggesting that c 13 depleted so waters reached the coast of southeastern australia however it did not result in increased productivity during these periods instead the highest primary productivity period as indicated by total organic carbon and alkenone accumulation rates occurred during the last glacial maximum while proboscia diatoms mainly proliferated during interglacials and marine isotope stage 3 matching periods of increased diatom productivity in some sites of the eastern equatorial pacific our study suggests that increased primary productivity offshore southeastern australia was mainly due to stronger westerly winds during glacial periods while proboscia diatom productivity was probably controlled by the transport of silicic acid to this area

from source to sink a new perspective on the past dynamics of the murray canyon group from benthic foraminiferal communities abstract we present fossil benthic foraminiferal assemblage data from marine sediment core ss02 06 gc2 located in the abyssal plain of the murray canyon group offshore south australia the sedimentological characteristics indicate the presence of turbidite deposits showing classical bouma like sequences dated between 40 and 12 cal ka bp these results confirm the previous interpretation of the observed large deep water holes in the abyssal area where the core was sampled as being gouged by surges of high energy turbidity currents the presence of good indicator taxa and unique assemblages occupying specific bathymetric depths allows the determination of the source origin of the sediments making the turbidites three distinct faunal groups are found 1 mostly shelf species 2 mostly bathyal species and 3 mostly abyssal species in the sediment core these groups present a quasi systematic succession with nearly all bouma like sequences starting with the dominance of bathyal species in the coarse grained base followed by the dominance of shallow species in the silty part and finally with abyssal species in the clays to explain such phenomena turbidites triggered by mixed hyperpycnal hypopycnal flow processes and turbidity currents during periods of river floods are considered for the first time within the murray canyon group they are mostly related to periods of increased fluvial discharges during wet phases in the murray darling basin

test of the predictability of the pi method for recent large earthquakes in and near tibetan plateau five large earthquakes of m 7 0 based on the magnitude scale of the china earthquake networks center occurred in and near the tibetan plateau during 2008 2014 including the wenchuan m8 0 earthquake on may 12 2008 bjt in this paper the tibetan plateau was chosen to be the study region and calculating parameters of pattern informatics pi method with grid of 1 1 and forecasting time interval of 8 years were employed for the retrospective study according to the previous studies for m7 earthquake forecasting the sliding step of forecasting interval was 1 year and the hotspot diagrams of each forecasting interval since 2008 were obtained year by year the relationships among the hotspots and the m 7 0 earthquakes that occurred during the forecast intervals were studied the predictability of pi method was tested by verification of receiveroperating characteristic curve roc and r score the results show that the successive obvious hotspots occurred during the sliding forecasting intervals before four of the five earthquakes while hotspots only occurred in one forecasted interval without successive evolution process before one of the five earthquakes which indicates that four of the five large earthquakes could be forecasted well by pi method test results of the predictability of pi method by roc and r score show that positive prospect of pi method could be expected for long term earthquake forecast

carbonate dissolution fluctuations in the western equatorial pacific during the late quaternary planktonic foraminiferal test fragmentation in three cores along a depth transect from the western equatorial pacific erdc 93p 1619 m rc17 177 2600 m v28 238 3120 m thompson 1976 were examined for the last 500 kyr at sample intervals from 2 5 to 5 kyr to study the fluctuations of dissolution in the western equatorial pacific the age models were constructed by correlating the 18o records with the specmap stack imbrie et al 1984 results showed that intermediate and deep waters experienced the same patterns of dissolution through climatic cycles fragmentation varied with a greater amplitude and the carbonate ion concentration changed less in the deep than in the intermediate water dissolution has significant variance distributions and coherencies with 18o over the 100 41 and 23 kyr periods of orbital variations dissolution maxima lag ice volume minima by 6 to 20 kyr the dissolution variability was consistent with recent geochemical models which seek to explain the reduction of atmospheric co2 concentration at the last glacial maximum broecker 1982 boyle 1988

the last deglaciation in the southern ocean the isotopic and micropaleontological deglacial records of three deep sea cores from 44 s to 55 s have been dated by accelerator mass spectrometry the available records did not allow accurate dating of the initiation of the deglaciation by 13 000 years b p sea surface temperatures reached values similar to the present values a cool oscillation abruptly interrupted this warm phase between 12 000 and 11 000 years b p initiation of this cooling therefore preceded the northern hemisphere younger dryas by approximately 1000 years complete warming was reached by 10 000 years b p more or less synchronous with the northeast atlantic ocean

changes in the position of the subtropical front south of new zealand since the last glacial period this study fills an important gap in our understanding of past changes in the southern subtropical front s stf in the southwest pacific ocean paleo sea surface temperatures sst were estimated from planktic foraminiferal census counts from cores straddling the modern s stf in the solander trough south of new zealand the estimated sst were compared for 6 time slices glacial period 25 21 ka last glacial maximum lgm 21 18 ka early deglaciation 18 16 ka late deglacial early holocene period 14 8 ka mid holocene period 8 4 ka and late holocene period 4 0 ka the position of the s stf was determined by two methods 1 the location of the 10 degrees c isotherm and 2 the location of the highest sst gradients these new results suggest that the s stf was not continuous between east and west of new zealand during the glacial period steep sst gradients indicate that a strong s stf rapidly shifted south during the lgm and early deglaciation during the late deglacial and holocene periods the position of the s stf differs between the two methods with reduced sst gradients suggesting amore diffuse s stf in the solander trough at this time the glacial sst data suggest that the s stf shifted north to the west of new zealand while to the east there was a stronger sst gradient across the front this was possibly the result of an increased wind stress curl which could have been caused by stronger or more northerly southern hemisphere westerly winds shww or a merging of the shww split jet in this region

surficial cool water carbonate sediments on the otway continental margin southeastern australia abstract the otway continental margin of southern australia is a swell dominated open cool water carbonate platform it is partitioned into a series of depth related zones of biological sediment production and accumulation by three hydrodynamic interfaces 1 abrasion depth 70 m 2 swell wavebase 130 m and 3 storm wavebase 250 m the otway shelf profile drops steeply from the strandline the shallow shelf lies largely between 30 and 70 m and is a high energy zone of carbonate sediment production intensive destructive diagenesis and erosion the seafloor is characterized by widespread exhumed limestone substrates which host dense encrusting assemblages of molluscs sponges bryozoans and red algae loose sediment accumulation is patchy and consists of a thin quartz rich palimpsest gravel veneer the middle shelf 70 to 130 m is a zone of swell wave shoaling and production and accumulation of coarse mega rippled 2 d dunes bryozoan sands deep shelf areas 130 to 180 m accumulate finer bioclastic sands foraminiferal echinoid bryozoan that are intensely bioturbated and episodically reworked by storms grains are variably fragmented and marginally bored at the shelf edge and top of slope 180 to 350 m nutrient rich upwelling currents support laterally extensive aphotic biostromal hermal bryozoan sponge coral communities which generate and accumulate thick successions of muddy skeletal sand sediments of the upper slope 350 to 500 m are a bioturbated mixture of periplatform bioclastic debris and pelleted foraminiferal nannofossil mud turbidites and resedimentation features are common bioturbation and shelf derived skeletal content decrease progressively downslope and pelagic muds dominate below 500 m lower slope areas are cross cut by gullies and have low accumulation rates the base of slope is characterized by sediment apron deposits consisting of interbedded shelf derived coarse grained turbidites and pelagic ooze

last glacial maximum to early holocene wind strength in the mid latitudes of the southern hemisphere from aeolian dust in the tasman sea dust transported by southern hemisphere mid latitude westerly winds from australia and deposited in the tasman sea shows no evidence for stronger winds during the last glacial maximum lgm compared to the holocene features of the particle size distributions of the dust do however indicate enhanced dry deposition of dust in the lgm changing to rainfall scavenging during deglaciation and the early holocene as climate ameliorated from these results it appears that activation of desert dunefields over 40 of australia during the lgm was the result of a reduction in stabilizing vegetation and more frequent episodes of sand movement rather than of increased wind strength the lgm climate of inland australia must have been considerably more stressful for plants as a result of lower precipitation and or carbon dioxide stress to achieve the implied levels of surface destabilization enhanced atmospheric dust loads in the southern hemisphere and deposition over antarctica were most likely the result of greatly expanded source areas in the mid latitude southern continents and a weaker hydrological cycle rather than greater entrainment or more efficient transport by stronger winds during the lgm wind strength appears to have varied regionally and predominantly in high latitudes rather than uniformly for all zonal winds

giant kiruna type deposits form by efficient flotation of magmatic magnetite suspensions kiruna type iron oxide apatite ioa deposits are an important source of fe ore and two radically different processes are being actively investigated for their origin one hypothesis invokes direct crystallization of immiscible fe rich melt that separated from a parent silicate magma while the other hypothesis invokes deposition of fe oxides from hydrothermal fluids of either magmatic or crustal origin here we present a new model based on fe and o stable isotopes and trace and major element geochemistry data of magnetite from the 350 mt fe los colorados ioa deposit in the chilean iron belt that merges these divergent processes into a single sequence of events that explains all characteristic features of these curious deposits we propose that concentration of magnetite takes place by the preferred wetting of magnetite followed by buoyant segregation of these earlyformed magmatic magnetite bubble pairs which become a rising magnetite suspension that deposits massive magnetite in regionalscale transcurrent faults our data demonstrate an unambiguous magmatic origin consistent with the namesake ioa analogue in the kiruna district sweden further our model explains the observed coexisting purely magmatic and hydrothermal magmatic features and allows a genetic connection between kiruna type ioa and iron oxide copper gold deposits contributing to a global understanding valuable to exploration efforts

surface water temperature changes in the high latitudes of the southern hemisphere over the last glacial interglacial cycle a set of numerical equations is developed to estimate past sea surface temperatures sst from fossil antarctic diatoms these equations take into account both the biogeographic distribution and experimentally derived silica dissolution the data represent a revision and expansion of a floral data base used previously and includes samples resulting from progressive opal dissolution experiments factor analysis of 166 samples 124 holocene core top and 42 artificial samples resolved four factors three of these factors depend on the water mass distribution one subantarctic and two antarctic assemblages factor 4 corresponds to a dissolution assemblage inclusion of this factor in the data analysis minimizes the effect of opal dissolution on the assemblages and gives accurate estimates of sst over a wide range of biosiliceous dissolution a transfer function dtf 166 34 4 is derived from the distribution of these factors versus summer sst its standard error is 1 c in the 1 to 10 c summer temperature range this transfer function is used to estimate sst changes in two southern ocean cores 43 s and 55 s which cover the last climatic cycle the time scale is derived from the changes in foraminiferal oxygen and carbon isotopic ratios the reconstructed sst records present strong analogies with the air temperature record over antarctica at the vostok site derived from changes in the isotopic ratio of the ice this similarity may be used to compare the oceanic isotope stratigraphy and the vostok time scale derived from ice flow model the oceanic time scale if taken at face value would indicate that large changes in ice accumulation rates occurred between warm and cold periods

a review of the australian new zealand sector of the southern ocean over the last 30ka aus intimate project the australia new zealand region of the southern ocean is influenced by several of the major global water masses of the oceans and is the prime entry point for cold deep waters into the pacific basin during the last glacial there was increased sea ice extent around antarctica as far north as 55 s as well as increased iceberg presence inferred from ice rafted debris evidence from microfossil assemblages suggests that sea surface temperatures sst were up to 7 c cooler consistent with recent estimates of cooling for new zealand derived from glacier modelling and other terrestrial proxies the subtropical front stf subantarctic front saf and polar front pf had migrated north except where the position of the fronts were controlled bathymetrically despite the potential for iron fertilisation by increased dust input into the ocean during the glacial there is limited evidence for higher total biological productivity in the pacific sector of the southern ocean the altered oceanic circulation during the glacial also decreased nutrients in the surface waters and affected the outgassing of co 2 this contributed to an increased storage of co 2 in the deep waters and lowering of the carbonate lysocline during the deglaciation sea ice retreat and sst increased rapidly at 18 ka roughly synchronous with the reinvigoration of deep water circulation in the southern ocean and the release of co 2 stored in the deep waters the gradient in carbon isotopes 13 o benthic between antarctic intermediate water aaiw and lower circumpolar deep water lcdw was greatest at the start of the deglaciation suggesting that the aaiw ventilation preceded lcdw ventilation or there was a significant change in air sea fractionation of 13 o benthic there was a slight enrichment in 18 o planktic decrease in ssts and a reduction in intermediate and deep water circulation between 14 and 12 5 ka bp during the antarctic cold reversal acr coincident with glacier advances in the new zealand southern alps and other terrestrial records of cooling following the acr there was a second more minor release of deep water co 2 most likely related to reinvigoration of north atlantic deep water nadw from 10 ka onwards the modern intermediate and deep water circulation was established air temperatures and ssts reached a maximum in the early holocene with the stf located at its most southerly position and there was a widespread retreat of antarctic ice sheets to their modern position a decline to modern sst and air temperatures in the mid to late holocene followed while millennial cycles overprinted on the sst and 18 o planktic records may be the result of subtle changes in the position and strength of the westerly winds during the holocene

thermal isolation of campbell plateau new zealand by the antarctic circumpolar current over the past 130 kyr 1 campbell plateau occupies a key position in the southwest pacific sector of the southern ocean the plateau confines and steers the antarctic circumpolar current acc along its flanks isolating the subantarctic plateau from cold polar waters oxygen and carbon isotope records from campbell plateau cores provide new records of water mass stratification for the past 130 kyr during glacial climes strengthening of the subantarctic front saf caused waters over the plateau flanks to be deeply mixed and 3 c cooler waters of the plateau interior remained stratified and isolated from the cold southern waters in the west waters cooled markedly 4 c owing to reduced entrainment of tasman sea water marked cooling also occurred north of campbell plateau under increased entrainment of polar water by a branch of the saf the acc remained along the flanks of campbell plateau during the last interglacial when interior waters were stratified and warmer by 1 c than now

ergodicity and earthquake catalogs forecast testing and resulting implications recently the equilibrium property of ergodicity was identified in an earthquake fault system tiampoet al phys rev lett 91 238501 2003 phys rev e 75 066107 2007 ergodicity in this context not only requires that the system is stationary for these networks at the applicable spatial and temporal scales but also implies that they are in a state of metastable equilibrium one in which the ensemble averages can be substituted for temporal averages when studying their behavior in space and time in this work we show that this property can be used to identify those regions of parameter space which are stationary when applied to the seismicity of two naturally occurring earthquake fault networks we apply this measure to one particular seismicity based forecasting tool the pattern informatics index tiampoet al europhys lett 60 481 487 2002 rundleet al proc national acad sci u s a suppl 1 99 2463 2002 in order to test the hypothesis that the identification of ergodic regions can be used to improve and optimize forecasts that rely on historic seismicity catalogs we also apply the same measure to synthetic catalogs in order to better understand the physical process that affects this accuracy we show that in particular ergodic regions defined by magnitude and time period provide more reliable forecasts of future events in both natural and synthetic catalogs and that these improvements can be directly related to specific features or properties of the catalogs that impact the behavior of their spatial and temporal statistics

recent benthic foraminifera from the continental margin of northwest africa community structure and distribution abstract sediment grab samples were collected at 107 locations along the continental margin of northwest africa these samples form a series of depth transects between the straits of gibraltar and dakar senegal the greater than 250 m size fraction was retained for a census of both the live and dead foraminifera after deleting trace occurrences jaccard and correlation coefficient based cluster analyses were performed to decipher the community structure for this margin the geographic distribution of the four major faunal provinces recognized is conventional in that for both the live and dead assemblages three are related to depth upper slope and shelf middle slope and lower slope and continental rise the biotopes and thanatotopes within these provinces are strongly restricted along vertical or latitudinal boundaries when the data are analysed using jaccard coefficients dendrograms constructed from correlation coefficients emphasize depth related faunal communities dominant species such as cibicides lobatulus trifarina fornasinii planulina ariminensis uvigerina finisterrensis and c wuellerstorfi are generally distributed within a definite depth range along this margin and strongly influence the correlation coefficient based dendrograms other distributions are clearly not depth related but correspond to various environmental variables for example cancris auriculus coarse substrate bolivina subaenariensis oxygen minimum cibicidoides kullenbergi and hoeglundina elegans low organic carbon uvigerina peregrina is also a notable exception to depth dependence in that this dominant species and the province it represents are generally confined to the continental slope south of cape blanc its preference for that region may arise from the high organic carbon and fine grain size of the sediment there from low salinity of the bottom water or from other unknown variables the most important vertical faunal boundary occurs between cape barbas and cape blanc between 22 and 21 n latitude in contrast the canary island ridge intersects the continental margin at a saddle depth of about 1500 m but that physiographic barrier has little effect on provincialism of the deep water benthic foraminifera

quaternary ostracods as palaeoceanographic indicators a case study off southern australia abstract there is increasing use of ostracods in palaeoceanographic interpretation yet few comparisons have been made with existing foraminiferal indicators this paper examines ostracod records from two cores taken off southern australia and compares them with foraminiferal records of abundance and dissolution core e55 6 from the continental margin of victoria is located in 2346 m water depth core e27 30 located south of tasmania in a water depth of 3552 m lies to the north of the present position of the subtropical convergence while benthic foraminiferal abundances parallel ostracod abundances in core e55 6 this is not the case in core e27 30 in the latter core peaks in ostracod abundance are offset from peaks in foraminiferal abundance this is attributed to high phytodetrital input associated with the subtropical convergence an ostracod based dissolution index is compared with foraminiferal dissolution data from both cores the ostracod dissolution index shows greater sensitivity than foraminiferal fragmentation in water depths well above the lysocline and suggests that carbonate dissolution at these depths may be underestimated using foraminiferal indices the impact of dissolution on ostracods can also be seen as a reduction in abundance this is evident in both cores although the impact is greater in the shallower core suggesting that carbonate saturation may be a factor in the distribution of ostracods in the deep sea further investigation of the effects of carbonate saturation on individual ostracod taxa will enhance their utility as palaeoceanographic tools

southwest pacific ocean response to a warming world using mg ca zn ca and mn ca in foraminifera to track surface ocean water masses during the last deglaciation in situ measurements of mg ca zn ca mn ca and ba ca in globigerinoides bulloides and globigerina ruber from southwest pacific core top sites and plankton tow are reported and their potential as paleoproxies is explored the modern samples cover 20 degrees of latitude from 34 degrees s to 54 degrees s 7 19 degrees c water temperature and variable influence of subantarctic saw and subtropical stw surface waters trace element signatures recorded in core top and plankton tow planktic foraminifera are examined in the context of the chemistry and nutrient profiles of their modern water masses our observations suggest that zn ca and mn ca may have the potential to trace saw and stw intraspecies and interspecies offsets identified by in situ measurements of mg ca and zn ca indicate that these ratios may also record changes in thermal and nutrient stratification in the upper ocean we apply these potential proxies to fossilized foraminifera from the high resolution core md97 2121 at the last glacial maximum surface water mg ca temperature estimates indicate that temperatures were approximately 6 7 degrees c lower than those of the present accompanied by low levels of mn ca and zn ca and minimal thermal and nutrient stratification this is consistent with regional dominance of saw and reduced stw inflow associated with a reduced south pacific gyre spg upper ocean thermal and nutrient stratification collapsed during the antarctic cold reversal before poleward migration of the zonal winds and ocean fronts invigorated the spg and increased stw inflow in the early holocene together with reduced winds this favored a stratified upper ocean from circa 10ka to the present

planktic foraminifera based sea surface temperature record in the tasman sea and history of the subtropical front around new zealand over the last one million years abstract planktic foraminiferal assemblages in a composite section from two cores md06 2989 2986 off the west coast of new zealand s south island 42 43 5 s provide a 1 myr mis 31 1 sea surface temperature sst record 3 4 kyr resolution in the tasman sea a significant overall faunal change occurred near the end of the mid pleistocene climate transition mpt at 600 ka mis 15 mean annual ssts were estimated using the artificial neural network ann method glacial interglacial g i cycles in the mpt had 9 c sst range whereas in the post mpt sst range was 6 7 c the sst and faunal changes imply that the subtropical front stf migrated 6 in latitude to lie just north of the sites in mpt glacials mis 28 16 but only migrated 3 5 north in post mpt glacials these g i latitudinal migrations of the stf west of new zealand contrast with the situation east of new zealand where migrations of both the stf and subantarctic front were prevented by the chatham rise and campbell plateau subtropical water is inferred to have only flowed around the south of new zealand as it does today during mis 11 and the late pleistocene holocene mis 5 1

sea surface temperatures around the australian margin and indian ocean during the last glacial maximum abstract we present new last glacial maximum lgm sea surface temperature sst maps for the oceans around australia based on planktonic foraminifera assemblages to provide the most reliable sst estimates we use the modern analog technique the revised analog method and artificial neural networks in conjunction with an expanded modern core top database all three methods produce similar quality predictions and the root mean squared error of the consensus prediction the average of the three under cross validation is only 0 77 c we determine lgm sst using data from 165 cores most of which have good age control from oxygen isotope stratigraphy and radiocarbon dates the coldest sst occurred at 20 500 1400 cal yr bp predating the maximum in oxygen isotope records at 18 200 1500 cal yr bp during the lgm interval we observe cooling within the tropics of up to 4 c in the eastern indian ocean and mostly between 0 and 3 c elsewhere along the equator the high latitudes cooled by the greatest degree a maximum of 7 9 c in the southwest pacific ocean our maps improve substantially on previous attempts by making higher quality temperature estimates using more cores and improving age control

the ecology of living stained deep sea benthic foraminifera from the sulu sea the distribution of living rose bengal stained deep sea benthic foraminifera was determined in the upper 20 cm of sediments of eight soutar box cores taken from two depth transects 510 4515 m in the thermospheric 10 c sulu sea despite the uniformity of bottom water temperatures salinities and dissolved oxygen levels below 1000 m significant faunal differences exist at different depths in the low oxygen 1 25 ml l below 1000 m basin the shallowest site 510 m is dominated 10 of the calcareous fauna by cibicidoides uvigerina 150 m and bolivina 63 m while siphonina is codominant with cibicidoides and uvigerina in the 1005 m core the 2000 m cores are dominated by cibicidoides gyroidinoides and oridorsalis while cibicidoides bradyi and oridorsalis umbonatus dominate the 3000 and 4000 m cores infaunal assemblages of valvulineria mexicana are found in the sediments of the 4515 m core relatively low bottom water oxygen values do not necessarily yield typical low oxygen taxa such as bolivina uvigerina chilostomella bulimina and globobulimina changes in the abundances of these taxa in fossil assemblages have been used as indicators of changes in ancient bottom water oxygen levels but may instead reflect organic carbon contents of the sediments an examination of the vertical distributions of foraminiferal assemblages from the 63 m and 150 m fractions reveals that taxa have microhabitat preferences similar to those observed in other regions taxa found in the upper 0 to 1 cm interval epifaunal include cibicidoides wuellerstorfi and hoeglundina elegans while taxa such as chilostomella and globobulimina reach maximum abundances in subsurface sediments and have infaunal microhabitat preferences cibicidoides bradyi and o umbonatus live in sediment depths from 0 to 4 cm and have transitional preferences with both epifaunal and infaunal occurrences intrageneric differences in test morphologies including pore distribution rounded peripheries and variable spire height are observed in cibicidoides and gyroidinoides and are suggested to be related to microhabitat preferences vertical distributions of a number of taxa found in both the 63 to 150 m and 150 m fractions are similar suggesting that juveniles and adults live under similar microhabitat conditions ontogenetic changes in microhabitat preferences of most species are not observed in this study and therefore would not be expected to account for isotopic vital effects reported for some taxa in previous studies

south tasman sea alkenone palaeothermometry over the last four glacial interglacial cycles alkenone palaeothermometry has demonstrated a wide spatial and temporal applicability for the reconstruction of sea surface temperatures sst some oceanic realms however remain poorly studied we document u37 index data for two sediment cores retrieved from the south tasman sea one west of new zealand so136 gc3 and the other southeast of tasmania fr1 94 gc3 extending back 280 kyr bp for the former and 460 kyr bp for the latter high climatic sensitivity on orbital time scales is observed at both locations particularly west of new zealand where typical glacial interglacial sst amplitudes always span more than 7 c southeast of tasmania sst amplitudes are lower in amplitude 4 3 to 6 9 c with the exception of termination iv which involved a sst change over 8 c the evolution of maximum glacial cooling through time is different at each location offshore new zealand maximum cooling during glacial stages increases with time whereas south of tasmania maximum cooling decreases with time in addition our data suggest heterogeneity in the spatial expression of sst during the penultimate and last glacial stages these glacial periods are recorded differently in both areas with marine isotopic stage 6 being warmer than marine isotopic stage 2 west of new zealand but slightly colder southeast of tasmania the area southwest of new zealand appears susceptible to expansions and contractions of the western pacific warm pool and or meridional migrations and changes in intensity of currents associated with the tasman front the region southeast of tasmania seems more sensitive to thermal changes as seen at high southern latitudes

evolving towards a critical point a review of accelerating seismic moment energy release prior to large and great earthquakes there is growing evidence that some proportion of large and great earthquakes are preceded by a period of accelerating seismic activity of moderate sized earthquakes these moderate earthquakes occur during the years to decades prior to the occurrence of the large or great event and over a region larger than its rupture zone the size of the region in which these moderate earthquakes occur scales with the size of the ensuing mainshock at least in continental regions a number of numerical simulation studies of faults and fault systems also exhibit similar behavior the combined observational and simulation evidence suggests that the period of increased moment release in moderate earthquakes signals the establishment of long wavelength correlations in the regional stress field the central hypothesis in the critical point model for regional seismicity is that it is only during these time periods that a region of the earth s crust is truly in or near a self organized critical soc state such that small earthquakes are capable of cascading into much larger events the occurrence of a large or great earthquake appears to dissipate a sufficient proportion of the accumulated regional strain to destroy these long wavelength stress correlations and bring the region out of a soc state continued tectonic strain accumulation and stress transfer during smaller earthquakes eventually re establishes the long wavelength stress correlations that allow for the occurrence of larger events these increases in activity occur over longer periods and larger regions than quiescence which is usually observed within the rupture zone of a coming large event the two phenomena appear to have different physical bases and are not incompatible with one another

australian dust deposits modern processes and the quaternary record abstract dust raising and transport are common and important processes in australia today the aridity of the australian continent and high climatic variability result in widespread dust raising in the arid and semi arid areas and transport to the humid margins and surrounding oceans the supply of erodible particles appears to be the greatest limitation on total flux of transported dust dust raising is greatest in the lake eyre basin including the simpson desert and murray darling basin where internal drainage renews supplies of fine particles to the arid zone in the west and northwest dust entrainment is low despite considerable aridity the marine record of dust flux shows at least a threefold increase in dust flux compared with the holocene in the last glacial maximum in both tropical and temperate australia driven by weakened australian monsoon rains and drier westerly circulation respectively despite the widespread confirmation of aeolian dust deposits in southeastern and southwestern australia dated or quantified records are extremely rare the dominant model of australian dust deposits the clay rich parna is shown to be poorly substantiated while modern and ancient dust deposits examined in detail are shown to bear a strong similarity to conventional definitions of loess

palaeocirculation across new zealand during the last glacial maximum at 21 ka abstract what circulation pattern drove southern alps glacial advances at 21 ka late 20th century glacial advances in new zealand are commonly attributed to a dual precipitation increase and cooler than normal temperatures associated with enhanced westerly flow that occur under synoptic pressure patterns termed zonal regimes kidson 2000 but was the circulation pattern that supported major southern alps glacial advances during the global lgm similar to the modern analog here a regional climate regime classification rcrc time slice was used to infer past circulation for new zealand during the lgm at 21 ka palaeoclimate information that supported the construction of the 21 ka time slice was derived from the nz intimate climate event stratigraphy ces one new auckland maar proxy record and additional low resolution data sourced from the literature the terrestrial evidence at 21 ka implicates several possibilities for past circulation depending on how interpretations for some proxies are made the interpretation considered most tenable for the lgm based on the agreement between terrestrial evidence marine reconstructions and palaeoclimate model results is an anticyclonic zonal circulation regime characterized by increased influences from blocking highs over the south island during winter and an increase in zonal and trough synoptic types with southerly to westerly quarter wind flow during summer these seasonal circulation traits would have generated lower mean annual temperatures cooler than normal summer temperatures and overall lower mean annual precipitation for new zealand particularly in the western south island at 21 ka the anticyclonic zonal time slice reconstruction presented in this study has different spatial traits than the late 20th century and the early little ice age signatures suggesting more than one type of regional circulation pattern can drive southern alps glacial activity this finding lends support to the hypothesis that temperature over precipitation change is more important as the primary modulator of southern alps ice advances the rcrc approach also demonstrates some subtle advantages of integrating multi proxy data within a palaeocirculation context for new zealand notably because this reconstruction technique enables direct comparisons to coarsely resolved palaeoclimate model outputs that do not have downscaled information

pattern informatics and its application for optimal forecasting of large earthquakes in japan pattern informatics pi technique can be used to detect precursory seismic activation or quiescence and make an earthquake forecast here we apply the pi method for optimal forecasting of large earthquakes in japan using the data catalogue maintained by the japan meteorological agency the pi method is tested to forecast large magnitude m 5 earthquakes spanning the time period 1995 2004 in the kobe region visual inspection and statistical testing show that the optimized pi method has forecasting skill relative to the seismic intensity data often used as a standard null hypothesis moreover we find in a retrospective forecast that the 1995 kobe earthquake m 7 2 falls in a seismically anomalous area another approach to test the forecasting algorithm is to create a future potential map for large m 5 earthquake events this is illustrated using the kobe and tokyo regions for the forecast period 2000 2009 based on the resulting kobe map we point out several forecasted areas the epicentral area of the 1995 kobe earthquake the wakayama area the mie area and the aichi area the tokyo forecast map was created prior to the occurrence of the oct 23 2004 niigata earthquake m 6 8 and the principal aftershocks with 5 0 m we find that these events were close to in a forecasted area on the tokyo map the pi technique for regional seismicity observation substantiates an example showing considerable promise as an intermediate term earthquake forecasting in japan

pleistocene variability of the subtropical convergence at east tasman plateau evidence from planktonic foraminiferal mg ca odp site 1172a combined measurements of mg ca and stable oxygen isotopes in tests of the planktonic foraminifer g bulloides from ocean drilling program odp site 1172a east tasman plateau allowed us to reconstruct sea surface temperature sstmg ca sea surface salinity sss and hence variations in the subtropical convergence stc in the southwestern tasman sea over the last four major glacial interglacial changes during interglacials the commonly enhanced sstmg ca and sss correspond to a lowered marine productivity and a lowered terrigenous flux implying that the stc separating cool high nutrient subantarctic surface water from warm saline oligotrophic subtropical surface water and hence the band of zonal westerlies responsible for the eolian dust flux were located south of east tasman plateau the warm east australian current was well established during warm periods and propagated far south during glacial times sstmg ca and sss were lower while both marine productivity and eolian flux increased such conditions prevailed during glacial marine isotope stages mis 12 mis 10 and to a lesser degree mis 6 and implied the extended northward influence of subantarctic surfacewater and a shift of the stc to 44 s the overall climatic signal at site 1172a appears to be largely attenuated when compared to published climate records from comparable latitudes to the west and to the east sstmg ca amplitudes were more pronounced in the subantarctic indian ocean and at chatham rise they exhibit a consistent pattern suggesting that latitudinal shifts of the stc occurred synchronously in the subantarctic indian ocean and at chatham rise but were largely damped at east tasman plateau due to the influence of the east australian current

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

modification of the pattern informatics method for forecasting large earthquake events using complex eigenfactors abstract recent studies have shown that real valued principal component analysis can be applied to earthquake fault systems for forecasting and prediction in addition theoretical analysis indicates that earthquake stresses may obey a wave like equation having solutions with inverse frequencies for a given fault similar to those that characterize the time intervals between the largest events on the fault it is therefore desirable to apply complex principal component analysis to develop earthquake forecast algorithms in this paper we modify the pattern informatics method of earthquake forecasting to take advantage of the wave like properties of seismic stresses and utilize the hilbert transform to create complex eigenvectors out of measured time series we show that pattern informatics analyses using complex eigenvectors create short term forecast hot spot maps that differ from hot spot maps created using only real valued data and suggest methods of analyzing the differences and calculating the information gain

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

testing the pattern informatics index on synthetic seismicity catalogs based on the non critical past abstract the non critical precursory accelerating seismicity theory or non critical past has recently been proposed to explain the formation of accelerating seismicity that may be observed before large earthquakes it has led to the possibility of constructing synthetic seismicity catalogs where patterns of accelerating seismicity activation and quiescence which occur in the same space time window can be evaluated by existing forecasting techniques in this study the pattern informatics or pi index is tested on synthetic catalogs where a realistic spatiotemporal clustering has been added on top of the theoretical precursory seismicity we show that the pi index is successful at identifying the precursory quiescent signal but fails in identifying precursory accelerating seismicity directly being more sensitive to aftershock sequences of background events than to the activation like behavior of the acceleration formed by background events alone we also show that the pi index has a high success rate in finding precursory quiescence even for a low signal to noise ratio as for the few false negatives they are usually due to interfering aftershocks as well which skew seismicity rates to higher means the non critical past by helping to better understand the behavior of the pi algorithm in synthetic catalogs gives new perspectives on how to improve it and on how to use it in real catalogs

late quaternary vegetation and climate change in southeastern australia palynological evidence from marine core e55 6 abstract palynological analysis of core e55 6 obtained from off shore western victoria provides a record of vegetation and climate change in the southeastern south australian and western victorian region spanning much of the last 125 000 yr an accompanying oxygen isotope record provides a chronology for the sequence the pollen record suggests that maximum effective precipitation occurred during the height of the last interglacial oxygen isotope substage 5e with wet sclerophyll forest and rainforest widespread in the region effective precipitation appears to have decreased during substage 5d promoting the expansion of dry sclerophyll communities then increased slightly during substage 5c with the limited re occurrence of wetter forest types climatic conditions gradually became drier from substage 5b with the replacement of eucalypt dominated forest by more open heath and mallee type communities in the arid glacial conditions of isotopic stage 4 a brief phase of increased effective precipitation occurred during the interstadial stage 3 with limited expansion of eucalyptus followed by a steady decline in effective precipitation and the expansion of open heath and grass communities pollen is very sparse in the top section of the core making environmental interpretation difficult nevertheless it appears that grass and heath communities dominated the region during stage 2 there is no clear record of the holocene due to the presence of mudflow sediments in the top of the core the pollen evidence also suggests that continental shelf exposed as sea levels fell was colonised by a mosaic of coastal vegetation including myrtaceae dominated scrub eucalypt and casuarina woodland asteraceae and chenopodiaceae dominated heath and grassland the charcoal record expressed as a ratio to pollen concentration gives evidence of increased burning during the height of the last interglacial period most likely in response to increased fuel loads with the expansion of eucalypt dominated forest this record also indicates a second phase of increased burning commencing in stage 2 which gives possible evidence for increased anthropogenic activity in the region

benthic foraminiferal proxy evidence for the neogene palaeoceanographic history of the southwest pacific east of new zealand abstract canonical correspondence analysis indicates that the distribution of neogene benthic foraminiferal faunas 63 m in seven dsdp and odp sites 500 4500 m water depth east of new zealand 38 51 s 170 e 170 w is most strongly influenced by depth water mass stratification and secondly by age palaeoceanographic changes influencing faunal composition and biotic evolution stratigraphic faunal changes are interpretted in terms of the pulsed sequential development of southern and later northern polar glaciation and consequent cooling of bottom waters increased vertical and lateral stratification of ocean water masses and increased overall and seasonal surface water productivity oligocene initiation of the antarctic circumpolar current and deep western boundary current dwbc flowing northwards past new zealand resulted in extensive hiatuses throughout the southwest pacific some extending through into the miocene planktic foraminiferal fragmentation index values indicate that carbonate dissolution was significant at abyssal depths throughout most of the neogene peaking at upper abyssal depths in the late miocene 11 7 ma with the lysocline progressively deepened thereafter miocene abyssal faunas are dominated by globocassidulina subglobosa and oridorsalis umbonatus with increasing epistominella exigua after 16 ma at upper abyssal depths peak abundances of epistominella umbonifera indicate increased input of cold southern component water to the dwbc at 7 6 ma faunal association changes imply establishment of the modern oxygen minimum zone upper circumpolar deep water in the latest miocene significant latitudinal differences between the benthic foraminiferal faunas at lower bathyal depths indicate the existence of an oceanic front along the chatham rise location of present subtropical front since the early late miocene at least with more pulsed productivity higher e exigua along the south side modern antarctic intermediate water faunal associations were established north of the chatham rise at 10 9 ma and south of it at 3 1 5 ma middle upper bathyal faunas on the campbell plateau are dominated by reticulate bolivinids during the early and middle miocene indicative of sustained productivity above relatively sluggish suboxic bottom waters faunal changes and hiatuses indicate increased current vigour over the campbell plateau from the latest miocene on surface water productivity food supply appears to have increased in three steps at times of enhanced global cooling marked by substantially increased relative abundance of 1 abditodentrix pseudothalmanni alabaminella weddellensis cassidulina norvangi 16 15 ma increased pulsed productivity 2 bulimina marginata f aculeata nonionella auris trifarina angulosa uvigerina peregrina 3 1 5 ma increased overall productivity and 3 cassidulina carinata 1 0 5 ma increased overall productivity three intervals of deep sea benthic foraminiferal taxonomic turnover are recognised 16 15 11 5 10 2 0 5 ma corresponding to intervals of enhanced global cooling and possible productivity changes the late pliocene middle pleistocene extinction associated with increasing northern hemisphere glaciation culminating in the middle pleistocene climatic transition was more significant in the study area than the earlier neogene turnovers

late pleistocene palaeocenography of the tasman sea implications for the dynamics of the warm pool in the western pacific quantitative analyses of planktonic foraminifera from 47 core top samples spatially distributed through the tasman sea and cores rc12 113 e36 23 dsdp sites 588 592 593 and odp site 828a from a n s transect supplemented with stable isotope analyses indicate that three planktonic foraminiferal assemblages defined by factor analysis on core top material correlated with three hydrographic modes defined on the basis of sea surface temperatures temperature profiles seasonal changes in temperature and mixed layer depth similar assemblages were found in down core material along the tasman sea transect that combined with semi quantitative analyses of foraminiferal assemblages provinces and the coiling ratio of globorotalia truncatulinoides allows reconstruction of the position of the tasman front or the subtropical divergence during the late brunhes chron the results indicate that the tasman front migrated from its present position at 30 s to 26 s during the last glacial maximum the northward migration of the tasman front may indicate a reduction in volume of the equatorial warm pool and or an increase in the strength of cool subtropical water masses the late pleistocene distribution of g truncatulinoides left coiling from appears to be related to the formation of subantarctic mode water thermostads this relationship may explain the evolutionary origin of this species in the southwest pacific at 2 4 ma simultaneously with the onset of late pliocene glaciations the past position of the subtropical convergence is reconstructed by means of coilingv directions in neogloboquadrina pachyderma the convergence apparently migrated slightly north of 43 s core e36 23 during glacial stages 6 10 and 12

frontal structure water masses and circulation in the crozet basin due to topographic steering by the crozet and kerguelen plateaus the antarctic circumpolar current acc core in the crozet basin area is shifted to its northernmost position in the southern ocean along the southern limb of the south indian subtropical gyre here the jet like current is embedded within a narrow band 26 5 kg m3 in the western half of the basin and heavier mode 26 7 kg m3 in its eastern half these different varieties of crozet basin mode water are closely correlated with the degree of exchange and mixing between subtropical and subantarctic waters along the dynamically active frontal zone the area north of the kerguelen plateau appears to be an important source of water mass modification antarctic intermediate water advected from the west also undergoes there significant modification by intrusions across the frontal zone of fresher oxygen richer colder subantarctic water energetic eddy activities observed along the frontal zone likely enhance such cross frontal exchange of water masses equatorward spreading of the modified thermocline water masses mode water antarctic intermediate water occurs as part of the anticyclonic circulation in the south indian subtropical gyre which is centered within the basin strong injection of north indian deep water into the acc south of amsterdam island is clearly evidenced for the first time this deep oxygen minimum water centered at about 3000 m can be traced to the east of madagascar from where it spreads southward through the eastern part of the crozet basin due to the influence of this water mass north atlantic deep water characteristics of the circumpolar deep water are significantly altered in kerguelen amsterdam passage our results indicate a cyclonic deep level circulation pattern in the crozet basin with a northward flow 9 sv of circumpolar deep water antarctic bottom water as a deep western boundary current and a partially compensating southward flow 3 sv of north indian deep water through the eastern part of the basin it is concluded that the crozet basin constitutes an important passage for the exchange of water masses between the southern ocean and the indian ocean

use of ostracodes to recognize downslope contamination in paleobathymetry and a preliminary reappraisal of the paleodepth of the prasas marls pliocene crete greece benthic ostracodes are well suited as tracers of downslope contamination the transportation toward greater depth of organic remains used in the paleobathymetric analysis of ancient fossiliferous sediments the method of analysis consists of two steps 1 establishing displacement and 2 ascertaining its downward nature the first step is based on common sense and does not require any specialist skills the second step relies on ostracode biobathymetry and therefore some expert knowledge is needed the main virtue of this step lies in the option to detect paleoslope instability as a case in point a preliminary reappraisal is given of the paleodepth of the late pliocene prasas marls near iraklion crete greece

modern carbonate and terrigenous clastic sediments on a cool water high energy mid latitude shelf lacepede southern australia the wide lacepede shelf and narrow bonney shelf are contiguous parts of the south eastern passive continental margin of australia the shelves are open generally deeper than 40 m covered by waters cooler than 18 c and swept by oceanic swells that move sediments to depths of 140 m the lacepede shelf is proximal to the delta of the river murray and the coorong lagoon shelf and upper slope sediments are a variable mixture of holocene and late pleistocene quartzose terrigenous clastic and bryozoa dominated carbonate particles bryozoa grow in abundance to depths of 250 m and are conspicuous to depths of 350 m they can be grouped into four depth related assemblages coralline algae the only calcareous phototrophs are important sediment producers to depths of 70 m active benthic carbonate sediment production occurs to depths of 350 m but carbonate sediment accumulation is reduced on the open shelf by continuous high energy conditions the shelf is separated into five zones the strandline is typified by accretionary sequences of steep shoreface beach and dune carbonate siliciclastic sediments similar shoreline facies of relict bivalve limestone cobble ridges are stranded on the open shelf the shallow shelf c 40 70 m deep is a wide extremely flat plain with only subtle local relief it is a mosaic of grainy quartzose palimpsest facies which reflect the complex interaction of modern bioclastic sediment production dominated by bryozoa and molluscs numerous highstands of sea level over the last 80 000 years modern mixing of sediments from relatively recent highstands and local introduction of quartz rich sediments during lowstands the middle shelf c 70 140 m deep is a gentle incline with subtle relief where holocene carbonates veneer seaward dipping bedrock clinoforms and local lowstand beach complexes carbonates are mostly modern uniform clean coarse grained sands dominated by a diverse suite of robust to delicate bryozoa particles produced primarily in situ but swept into subaqueous dunes the deep shelf edge c 140 250 m deep is a site of diverse and active bryozoa growth resulting accumulations are characteristically muddy and distinguished by large numbers of delicate branching bryozoa the upper slope between 250 and 350 m depth contains the deepest platform related sediments which are very muddy and contain a low diversity suite of delicate branching cyclostome bryozoa this study provides fundamental environmental information critical for the interpretation of cenozoic cool water carbonates and the region is a good model for older mixed carbonate terrigenous clastic successions which were deposited on unrimmed shelves

pattern dynamics and forecast methods in seismically active regions large extended fault systems such as those in california demonstrate complex space time seismicity patterns which include repetitive events precursory activity and quiescence and aftershock sequences although the characteristics of these patterns can be qualitatively described a systematic quantitative analysis remains elusive our research suggests that a new pattern dynamics methodology can be used to define a unique finite set of seismicity patterns for a given fault system in addition while a long sought goal of earthquake research has been the reliable forecasting of these events very little progress has been made in developing a successful consistent methodology in this report we document the discovery of systematic space time variations in seismicity from southern california using a new technique here we present examples of this analysis technique on data obtained prior to events in seismically active areas that show coherent regions associated with the future occurrence of major earthquakes in the same areas these results strongly support the hypothesis that seismic activity is highly correlated across many space and time scales within large volumes of the earth s crust

the distribution of living benthic foraminifera on the continental slope and rise off southwest norway abstract surface sediment samples taken by corer from 45 stations on the norwegian continental margin and in the norway basin have been investigated for their benthic foraminiferal content unlike previous studies the living benthic foraminiferal fauna was differentiated from empty tests comprising the foraminiferal death assemblage factor analysis of both the living and dead faunal data reveals six living species assemblages and five corresponding dead assemblages the additional living assemblage is characterized by the arenaceous speciescribrostomoides subglobosum that dominates between 1400 and 2000 m water depth but is rare in the dead faunal data trifarina angulosa and to a lesser extent cibicides lobatulus characterize the shallowest foraminiferal assemblage from 200 to 600 m water depth where it is associated with strong bottom currents and warm saline atlantic water of the north atlantic drift on the slope between 600 and 1200 m water depth themelonis zaandami species assemblage dominates particularly in areas characterized today by rapid sedimentation of terrigeneous material between 1000 and 1400 m depth where the slope is covered by fine grained organic rich terrigeneous mud the living foraminiferal assemblage is characterized bycassidulina teretis andpullenia bulloides below 1400 m three foraminiferal assemblages are found c subglobosum is found from 1400 to 2000 m cibicidoides wuellerstorfi andepistominella exigua predominantly live from 2000 to 3000 m water depth and below 3000 m oridorsalis umbonatus andtriloculina frigida dominate the fauna all of theelphidium excavatum tests found in this study and thecassidulina reniforme tests found above 500 m water depth were found to be reworked analysis of the sediment grain size distribution and the organic carbon content in surface samples from the deepest stations suggest that the abundance ofc wuellerstorfi ande exigua is positively correlated to relatively coarse caused by planktic foraminifera and organic rich sediments whereas high frequencies ofo umbonatus andt frigida coincide with low organic carbon content we suggest thatc wuellerstorfi is adapted to deep sea environments with relatively high food supply tolerating relatively low interstitial water oxygen content whereaso umbonatus may tolerate lower food supply prefering well oxygenated interstitial waters

holocene sediment dynamics on a cool water carbonate shelf otway southeastern australia the otway shelf is covered by cool ocean waters and veneered by bryozoan dominated carbonate sediments radiocarbon dating and stratigraphy of shelf vibracores and slope gravity cores document late pleistocene holocene deposition shelf sediments of the late pleistocene highstand 60 26 ky are rare either never having been deposited or having been removed during the following sea level fall 26 17 ky during the subsequent lowstand the shelf was exposed facies shifted basinward and beach dune complexes were constructed near the shelf edge the deep shelf was characterized by nondeposition and hardground formation and the shelf margin became locally erosional upper slope bryozoan sponge assemblages continued to grow actively and lower slope foraminifera and nannofossil ooze was increasingly enriched in hemipelagic terrigenous mud swept off the wide shelf coarse shelf debris and lowstand dune sands were erosively reworked and transported onto the upper slope and redistributed to deep slope aprons during early transgression 17 10 ky this event locally terminated shelf edge bryozoan and sponge growth continued erosive shoreface retreat formed a bored and cemented ravinement surface mantled by bivalves and lithoclasts across the open shelf base level rise reduced the amount of terrigenous material reaching the continental slope slower transgressive flooding from 10 to 6 5 ky allowed infilling of shallow embayments on the shelf and outer shelf sediment accumulation began by 7 ky sea level stabilized near its present level by 6 5 ky and the area is now partitioned into three zones by an energetic wave and swell regimen 1 inboard protected embayments and or beach dune complexes with high sediment accumulation rates about 100 cm ky 2 an open shelf where although sediment production is active accumulation is patchy 3 5 cm ky to nonexistent within the zone of wave abrasion and minimal about 23 cm ky between maximum abrasion depth and swell wave base and 3 a deep shelf edge and upper slope where sediment is accumulating at rates of 2 50 cm ky interpreted deep water 100 m bryozoan sponge mounds are growing at rates of 105 cm ky accumulation decreases progressively down slope with deep slope pelagic carbonate sedimentation at rates of 5 cm ky the late quaternary shelf record resembles that of flat topped warm water platforms with holocene sediment overlying pleistocene tertiary limestone but for different reasons much of this high energy shelf is still within lag depth more than 10 ky after flooding the steady state deep water shelf margin bryozoan factory has been largely unaffected by 50 100 m eustatic changes in sea level and has contributed to slow but continuous platform progradation the slow growth potential uniform profile of sediment production and distribution and inability of constituent organisms to construct rigid frameworks favor maintenance of a shallow ramp profile and makes the cool water carbonate system an excellent modern analog for interpretation of many ancient ramp successions

application of a modified pattern informatics method to forecasting the locations of future large earthquakes in the central japan we propose a modification of the pattern informatics pi method that has been developed for forecasting the locations of future large earthquakes this forecast is based on analyzing the space time patterns of past earthquakes to find possible locations where future large earthquakes are expected to occur a characteristic of our modification is that the effect of errors in the locations of past earthquakes on the output forecast is reduced we apply the modified and original methods to seismicity in the central part of japan and compared the forecast performances we also invoke the relative intensity ri of seismic activity and randomized catalogs to constitute null hypotheses we do statistical tests using the molchan and relative operating characteristic roc diagrams and the log likelihoods and show that the forecast for using the modified pi method is generally better than the competing original pi forecast and the forecasts from the null hypotheses using the bootstrap technique with monte carlo simulations we further confirm that earthquake sequences simulated based on the modified pi forecast can be statistically the same as the real earthquake sequence so that the forecast is acceptable the main and innovative science in this paper is the modification of the pi method and the demonstration of its applicability showing a considerable promise as an intermediate term earthquake forecasting tool

northeastern atlantic benthic foraminifera during the last 45 000 years changes in productivity seen from the bottom up we studied benthic foraminifera from the last 45 kyr in the 63 mu m size fraction in biogeochemical ocean flux studies bofs cores 5k 50 degrees 41 3 n 21 degrees 51 9 w depth 3547 m and 14k 58 degrees 37 2 n 19 degrees 26 2 w depth 1756 m at a time resolution of several hundreds to a thousand years the deepest site showed the largest fluctuations in faunal composition species richness and benthic foraminiferal accumulation rates the fluctuations resulted from changes in abundance of epistominella exigua and alabaminella weddellensis in the present oceans these species bloom opportunistically when a spring plankton bloom results in seasonal deposition of phytodetritus on the seafloor the phytodetritus species had very low relative abundances and accumulation rates during the last glacial maximum a strong increase in absolute and relative abundance of e exigua and a weddellensis during deglaciation paralleled the decrease in abundance of the polar planktonic foraminifer neogloboquadrina pachyderma s and the increase in abundance of warmer water planktonic species such as globigerina bulloides this strong increase in relative abundance of the phytodetritus species and the coeval increase in benthic foraminiferal accumulation rate were thus probably caused by an increase in the deposition of phytodetritus to the seafloor and thus probably of surface productivity when the polar front retreated to higher latitudes the abundance of phytodetritus species decreased during the younger dryas but not to the low levels of fully glacial conditions during heinrich events periods of excessive melt water formation and ice rafting benthic accumulation rates were very low as were the absolute and relative abundances of the phytodetritus species supporting suggestions that surface productivity was very low during these events in both cores pullenia and cassidulina species were common during isotope stages 2 3 and 4 as were bolivinid buliminid and uvigerinid species high relative abundances of these species have been interpreted as indicative either of sluggish deep water circulation or of high organic carbon fluxes to the seafloor in our cores relative abundances of these species are negatively correlated with benthic foraminiferal accumulation rates and we can thus not interpret them as indicative of increased productivity during glacials the percentage of these low oxygen species calculated on a phytodetritus species free basis decreased slightly at deglaciation at 5k but not at 14k this suggests that decreased production of north atlantic deep water during the last glacial might have slightly affected benthic foraminiferal faunas in the eastern north atlantic at 3547 m depth but not at 1756 m in conclusion major changes in deep sea benthic foraminiferal faunas over the last 45 000 years in our cores from the northeastern atlantic were the result of changes in surface water productivity not of changes in deep water circulation productivity was lower during the glacial probably because of extensive ice cover

low degree spherical harmonic influences on gravity recovery and climate experiment grace water storage estimates we estimate terrestrial water storage variations using time variable gravity changes observed by the gravity recovery and climate experiment grace satellites during the first 2 years of the mission we examine how treatment of low degree gravitational changes and geocenter variations affect grace based estimates of basin scale water storage changes using independently derived low degree harmonics from earth rotation eop and satellite laser ranging slr observations grace based water storage changes are compared with estimates from nasa s global land data assimilation system gldas results from the 22 grace monthly gravity solutions covering the period april 2002 to july 2004 show remarkably good agreement with gldas in the mississippi amazon ganges ob zambezi and victoria basins combining grace observations with eop and slr degree 2 spherical harmonic coefficient changes and slr observed geocenter variations significantly affects and apparently improves the estimates especially in the mississippi ob and victoria basins

precursory seismic activation and critical point phenomena in this paper we relate the behavior of seismicity prior to a characteristic earthquake to the excitation in proximity to a spinodal instability we illustrate the spinodal instability as the upper limit of superheated water prior to a steam explosion we draw an analogy between the steam explosion and a characteristic earthquake and show that the power law activation associated with the spinodal instability is essentially identical to the power law increase in benioff strain observed prior to characteristic earthquakes we find that theory and actual data give very similar results

late quaternary palaeoceanography near tasmania southern australia abstract this study of the palaeoceanographic record south of australia is based on two cores taken from lower circumpolar deep water depths core e27 30 located south of tasmania in water depth of 3552 m to the north of the present location of the subtropical convergence and core e55 6 from the continental margin off victoria at 2346 m depth in a region of very low surface productivity a preliminary examination of planktonic foraminiferal faunas in core e27 30 located south of tasmania provides a record of movement of the subtropical convergence through the late quaternary that is consistent with records elsewhere in the southeast indian ocean the convergence has been located equatorward of its present position through much of the late quaternary with poleward excursions in the holocene and at oxygen isotope stage 5e benthic foraminiferal faunas contrast strongly in the two cores despite their location at similar depths within the same water mass core e55 6 is largely dominated by deep infaunal taxa while core e27 30 has a high proportion throughout of epifaunal taxa the benthic foraminiferal fauna in core e27 30 is dominated by epistominella exigua known to feed directly on phytoplankton detritus in the modern deep sea abundances of that species coincide with the presence of the subtropical convergence at or near the site indicating that surface phytoplankton production has had a major influence on benthic productivity dissolution records in the two cores also differ markedly core e55 6 records a strong dissolution event in oxygen isotope stage 4 the cause of the event is not clear although it appears to be associated with increased productivity levels this pronounced dissolution event is not evident in core e27 30 suggesting either the event is localised or that the record in core e27 30 has been overprinted by the convergence the extent to which the records in the two cores vary emphasises the influence of frontal structures on core records in this region and the need to take this into account when investigating southern ocean history

the 1999 chi chi taiwan earthquake as a typical example of seismic activation and quiescence 1 the pattern informatics algorithm which has recently shown promising performance for earthquake forecasting in southern california has been used to detect the locations where precursory seismic activity occurred preceding the 1999 chi chi taiwan earthquake using the pattern informatics method as presented in this paper the epicenter of the chi chi main shock was found to exhibit signatures of anomalous activity related to the seismic activation and quiescence in the taiwan region over a time span of about 6 years before the main shock a strategy of making intermediate term earthquake hazard assessment by means of pattern informatics is therefore proposed on the basis of retrospective analysis of the chi chi earthquake

a chronology for the long pollen record from lake wangoom western victoria australia as derived from uranium thorium disequilibrium dating the chronology of a long pollen record from lake wangoom one of the few long palaeoenvironmental records from southeastern australia is discussed in light of the acquisition of new uranium thorium disequilibrium utd dates of crucial importance has been the estimation of ages for two major pre holocene phases of forest expansion recorded in the sequence with implications for the timing of periods of high effective precipitation in the region the new utd ages indicate that the oldest forest phase falls within the penultimate interglacial whereas the later phase corresponds with the last interglacial this is older than indicated by previously reported utd and radiocarbon dates but confirms a chronology based on direct correlation with the pollen record from marine core e55 6 the new chronology of the lake wangoom sequence provides evidence that phases of sustained forest development in southeast australia relate to interglacial periods in comparison interstadial periods appear to be characterised by only minor arboreal development marked differences in the pattern of vegetation development evident in each of the interglacials are thought to reflect varying climatic and anthropogenic influences copyright 2002 john wiley sons ltd

a late quaternary sedimentary record of steryl alkyl ethers from offshore southeastern australia steryl alkyl ethers saes have been reported from marine sediments ranging from holocene to lower cretaceous and their production has been linked to upwelling of cold nutrient rich water however the lack of continuous stratigraphic records for them has complicated validation of the precise connection of their production sedimentary distribution and survival to climatic conditions here we report an sae record that spans the last ca 135 ka from a core taken offshore southeastern australia in the murray canyons group region the saes are composed predominantly of c 27 c 30 steroid moieties with one or two double bonds ether bound to c 10 c 11 alkyl moieties some of the saes are identical to those reported in marine sediments whereas others have not been identified previously they do not exhibit any systematic change in distribution over the past 110 ka but sediments older than 110 ka possess a different assemblage with a higher amount of constituents containing a c 11 alkyl moiety the sae accumulation rate increases rapidly during glacial episodes and for intervals characterized by a sharp decline in sea surface temperature the results suggest that saes may be related to marine eukaryotes that thrive when there is an influx of cold deep waters in the murray canyons group region likely triggered by stronger westerlies over southeastern australia forcing deeper water to reach the surface during glacials

eigenpatterns in southern california seismicity 1 earthquakes in seismically active regions of the world are known to be associated with a variety of spatial and temporal patterns examples include precursory quiescence or activation seismic clustering and mogi donuts although the characteristics of these patterns can be qualitatively described a systematic quantitative analysis has proved elusive in this paper we employ a new method developed using numerical simulations that allows a systematic quantification of the spatial and temporal characteristics of the patterns in historic seismicity in southern california this method decomposes a set of boolean activity functions representing historic seismicity into their orthonormal eigenvalues and eigenfunctions here we show the results of this analysis which strongly support the hypothesis that seismic activity is highly correlated across many space scales and timescales within large volumes of the earth s crust

statistical physics approach to understanding the multiscale dynamics of earthquake fault systems 1 earthquakes and the faults upon which they occur interact over a wide range of spatial and temporal scales in addition many aspects of regional seismicity appear to be stochastic both in space and time however within this complexity there is considerable self organization we argue that the occurrence of earthquakes is a problem that can be attacked using the fundamentals of statistical physics concepts of statistical physics associated with phase changes and critical points have been successfully applied to a variety of cellular automata models examples include sandpile models forest fire models and particularly slider block models these models exhibit avalanche behavior very similar to observed seismicity a fundamental question is whether variations in seismicity can be used to successfully forecast the occurrence of earthquakes several attempts have been made to utilize precursory seismic activation and quiescence to make earthquake forecasts some of which show promise

paleoproductivity from benthic foraminifera abundance glacial to postglacial change in the west equatorial pacific surface productivity is correlated with the rate of accumulation of benthic foraminifera on the deep sea floor as a rule of thumb for each 1 mg of organic carbon arriving at the sea floor one benthic foram shell 150 m is deposited the correlation can be used to reconstruct organic flux to the sea floor in the past and hence the productivity of past oceans applying the appropriate equations to box core data from the ontong java plateau in the western equatorial pacific we found that productivity during the last glacial maximum exceeded present productivity by a factor of between 1 5 and 2 0 with intermediate values for the mid transition period accumulation of benthic foraminifera was depressed on top of the plateau during the glacial and transitional period presumably because increased winnowing removed part of the food supply

seismicity based earthquake forecasting techniques ten years of progress abstract earthquake fault systems interact over a broad spectrum of spatial and temporal scales and in recent years studies of the regional seismicity in a variety of regions have produced a number of new techniques for seismicity based earthquake forecasting while a wide variety of physical assumptions and statistical approaches are incorporated into the various methodologies they all endeavor to accurately replicate the statistics and properties of both the historic and instrumental seismic records as a result the last ten years have seen significant progress in the field of intermediate and short term seismicity based earthquake forecasting these include general agreement on the need for prospective testing and successful attempts to standardize both evaluation methods and the appropriate null hypotheses here we differentiate the predominant approaches into models based upon techniques for identifying particular physical processes and those that filter or smooth the seismicity comparison of the methods suggests that while smoothed seismicity models provide improved forecast capability over longer time periods higher probability gain over shorter time periods is achieved with methods that integrate statistical techniques with our knowledge of the physical process such as the epidemic type aftershock sequence etas model or those related to changes in the b value for example in general while both classes of seismicity based forecasts are limited by the relatively short time period available for the instrumental catalog significant advances have been made in our understanding of both the limitations and potential of seismicity based earthquake forecasting there is general agreement that both short term forecasting on the order of days to weeks and longer term forecasting over five to ten year periods is within reach this recent progress serves to illuminate both the critical nature of the different temporal scales intrinsic to the earthquake process and the importance of high quality seismic data for the accurate quantification of time dependent earthquake hazard

carbon isotope evidence for changes in antarctic intermediate water circulation and ocean ventilation in the southwest pacific during the last deglaciation 1 deep sea sediment core fr1 97 gc 12 is located 990 mbsl in the northern tasman sea southwest pacific where antarctic intermediate water aaiw presently impinges the continental slope of the southern great barrier reef analysis of carbon 13c and oxygen 18o isotope ratios on a suite of planktonic and benthic foraminifera reveals rapid changes in surface and intermediate water circulation over the last 30 kyr during the last glacial maximum there was a large 13c offset 1 1 between the surface dwelling planktonic foraminifera and benthic species living within the aaiw in contrast during the last deglaciation termination 1 the 13cplanktonic benthic offset reduced to 0 4 prior to an intermediate offset 0 7 during the holocene we suggest that variations in the dominance and direction of aaiw circulation in the tasman sea and increased oceanic ventilation can account for the rapid change in the water column 13cplanktonic benthic offset during the glacial interglacial transition our results support the hypothesis that intermediate water plays an important role in propagating climatic changes from the polar regions to the tropics in this case climatic variations in the southern hemisphere may have led to the rapid ventilation of deep water and aaiw during termination 1 which contributed to the postglacial rise in atmospheric co2

disconformities and paleoceanography in the southeast indian ocean during the past 5 4 million years biostratigraphy and magnetostratigraphy are used to identify deep sea disconformities in the southeast indian ocean the hiatuses are used to define periods of increased bottom water activity and to indicate deep sea circulation patterns during the pliocene and pleistocene seven zones of hiatus are restricted to areas confined by topographic restrictions or by water depth control on bottom water flow an analysis of hiatus frequency reveals that a water depth of about 4 200 m separates disconformities formed by antarctic bottom water 4 200 m and circumpolar deep water 4 200 m hiatus zones in deep basins occur in the tasman emerald balleny and south indian basins and east of the macquarie ridge shallow water hiatus zones 4 200 m occur at the junction of the southeast indian rise the macquarie ridge and the tasman basin and along the antarctic margin changes in the extent of these regional hiatuses are examined by analysis of hiatus occurrence in seven time slices during the past 5 4 m y although the timing of hiatuses produced by deep and shallow water masses are not synchronous the causes of increased bottom water activity may be correlated with paleoclimatic events southern ocean cooling and the proposed re establishment of the west antarctic ice sheet and its fringing ice shelves in the late gilbert chron t 4 2 to 3 6 m y b p were accompanied by increased antarctic bottom water and circumpolar deep water activity as revealed by the frequency of both shallow and deep disconformities the formation of the northern hemisphere barents ice sheet at 3 5 m y b p however led to a decrease in antarctic bottom water production by inhibiting the formation of saline north atlantic deep water which combines with cold antarctic shelf water to form antarctic bottom water cool southern ocean climatic conditions that culminated in the late matuyama chron t 1 66 to 0 72 m y b p resulted in a widespread disconformity produced by increased circumpolar deep water activity and a more restricted disconformity produced by antarctic bottom water the areal extent of both deep and shallow disconformities was reduced after the late matuyama chron t 0 72 m y b p in response to decreased bottom current activity

glacial interglacial changes in sediment rain rate in the sw indian sector of subantarctic waters as recorded by 230th 231pa u and δ15n high resolution records of opal carbonate and terrigenous fluxes have been obtained from a high sedimentation rate core md84 527 43 50 s 51 19 e 3269 m by normalization to 230th this method estimates paleofluxes to the seafloor on a point by point basis and distinguishes changes in sediment accumulation due to variations in vertical rain rates from those due to changes in syndepositional sediment redistribution by bottom currents we also measured sediment 15n to evaluate the changes in nitrate utilization in the overlying surface waters associated with paleoflux variations our results show that opal accumulation rates on the seafloor during the holocene and stage 3 based on 14c dating were respectively tenfold and fivefold higher than the vertical rain rates at this particular location changes in opal accumulation on the seafloor appear to be mainly controlled by sediment redistribution by bottom currents rather than variations in opal fluxes from the overlying water column correction for syndepositional sediment redistribution and the improved time resolution that can be achieved by normalization to 230th disclose important variations in opal rain rates we found relatively high but variable opal paleoflux during stage 3 with two maxima centered at 36 and 30 kyr b p low opal paleoflux during stage 2 and deglaciation and a pronounced maximum during the early holocene we interpret this record as reflecting variations in opal production rates associated with climate induced latitudinal migration of the southern ocean frontal system sediments deposited during periods of high opal paleoflux also have high authigenic u concentrations suggesting more reducing conditions in the sediment and high pa 231 th 230 ratios suggesting increased scavenging from the water column sediment 15n is circa 1 5 per mil higher during isotopic stage 2 and deglaciation the low opal rain rates recorded during that period appear to have been associated with increased nitrate depletion this suggests that opal paleofluxes do not simply reflect latitudinal migration of the frontal system but also changes in the structure of the upper water column increased stratification during isotopic stage 2 and deglaciation could have been produced by a meltwater lid leading to lower nitrate supply rates to surface waters

benthic foraminifera and the late quaternary last 150 ka paleoceanographic and sedimentary history of the bounty trough east of new zealand abstract the bounty trough east of new zealand lies along the southeastern edge of the present day subtropical front stf and is a major conduit via the bounty channel for terrigenous sediment supply from the uplifted southern alps to the abyssal bounty fan census data on 65 benthic foraminiferal faunas 63 m from upper bathyal odp 1119 lower bathyal dsdp 594 and abyssal odp 1122 sequences test and refine existing models for the paleoceanographic and sedimentary history of the trough through the last 150 ka marine isotope stages mis 6 1 cluster analysis allows recognition of six species groups whose distribution patterns coincide with bathymetry the climate cycles and displaced turbidite beds detrended canonical correspondence analysis and comparisons with modern faunal patterns suggest that the groups are most strongly influenced by food supply organic carbon flux and to a lesser extent by bottom water oxygen and factors relating to sediment type major faunal changes at upper bathyal depths 1119 probably resulted from cycles of counter intuitive seaward landward migrations of the southland front sf north south sector of the stf benthic foraminiferal changes suggest that lower nutrient cool subantarctic surface water saw was overhead in warm intervals and higher nutrient bearing warm neritic subtropical surface water stw was overhead in cold intervals at lower bathyal depths 594 foraminiferal changes indicate increased glacial productivity and lowered bottom oxygen attributed to increased upwelling and inflow of cold nutrient rich antarctic intermediate water aaiw and shallowing of the oxygen minimum zone upper circum polar deep water cpdw the observed cyclical benthic foraminiferal changes are not a result of associations migrating up and down the slope as glacial faunas dominated by globocassidulina canalisuturata and eilohedra levicula at upper and lower bathyal depths respectively are markedly different from those currently living in the bounty trough on the abyssal bounty fan 1122 faunal changes correlate most strongly with grain size and are attributed to varying amounts of mixing of displaced and in situ faunas most of the displaced foraminifera in turbiditic sand beds are sourced from mid outer shelf depths at the head of the bounty channel turbidity currents were more prevalent during but not restricted to glacial intervals

the contributions of uranium thorium and marine palynology to the dating of the lake wangoom pollen record western plains of victoria australia abstract an extended pollen record from lake wangoom provides clear evidence for two climatic cycles incorporating three major effective precipitation peaks the existing radiocarbon dates and age estimates derived from uranium thorium dating and correlation with the pollen sequence from an isotopically dated marine record presented here provide conflicting chronologies for these cycles the radiocarbon dates indicate the youngest and middle precipitation peaks correspond respectively to the holocene and the last major interstadial oxygen isotope stage 3 by extrapolation the oldest peak correlates most closely with substage 5c uranium thorium disequilibrium dates suggest both the middle and oldest precipitation peaks occur within the isotope stage 5 complex the middle phase corresponding with an interstadial and the oldest with the height of the last interglacial the most reliable chronology at least for the later cycle is considered to be provided by comparison with the pollen record from a marine core with an oxygen isotope sequence from offshore victoria this record indicates that the last time precipitation levels attained those of the holocene was during the last interglacial period and suggests that the wangoom record extends back to the penultimate interglacial of isotope stage 7

global observational properties of the critical earthquake model the preshock critical regions of 20 mainshocks with magnitudes between 6 4 and 8 3 which occurred recently since 1980 in a variety of seismotectonic regimes greece anatolia himalayas japan california were identified and investigated all these strong earthquakes were preceded by accelerating time to mainshock seismic crustal deformation benioff strain the time variation of the cumulative benioff strain follows a power law with a power value m 0 3 in very good agreement with theoretical considerations we observed that the dimension of the critical region increased with increasing mainshock magnitude and with decreasing long term seismicity rate of the region an increase of the duration of this critical preshock phenomenon with decreasing long term seismicity rate was also observed this spatial and temporal scaling expresses characteristics of the critical earthquake model which are of importance for earthquake prediction research we also showed that the critical region of an oncoming mainshock coincides with the preparing region of this shock where other precursory phenomena can be observed

dust induced changes in phytoplankton composition in the tasman sea during the last four glacial cycles 1 an increase in iron supply associated with enhanced dust inputs could be responsible for higher marine phytoplankton production leading to the typically lower glacial atmospheric co2 concentrations as suggested by the iron hypothesis the enhanced dust supply may also have provided the oceans with significant amounts of silica which would have favored the growth of diatoms over coccolithophores as suggested by the silica hypothesis here we present new data on molecular biomarkers in a sediment core from the midlatitudes of the southern hemisphere which reveal dust induced changes in the relative contribution of the phytoplankton to total productivity our results illustrate a shift in the relative abundance of siliceous over calcareous organisms during glacial times when terrestrial aeolian input was enhanced although we did not detect a significant glacial decrease in coccolithophorid productivity the decrease in the caco3 corg rain ratio could have still contributed to some extent in lowering atmospheric co2 levels

a benthic foraminiferal proxy of pulsed organic matter paleofluxes in the temperate open ocean of the modern northeast atlantic the spring bloom of phytoplankton leads to a seasonal pulse of detrital organic material phytodetritus to the ocean floor opportunistic benthic foraminifera rapidly colonise this food resource producing large numbers of individuals whose tests are ultimately added to the sediment one of these taxa epistominella exigua shows periodic peaks in abundance in the fossil record at many open ocean sites previously such peaks have been commonly interpreted to result from changes in physicochemical properties of bottom water mass and thus deep sea circulation the main purpose of this paper is to propose thate exigua may be used as a proxy of pulsed organic matter inputs to the deep ocean and therefore as an indicator of relative changes in productivity

high resolution stratigraphic correlation of benthic oxygen isotopic records spanning the last 300 000 years abstract in order to compare the response of different oceanographic regions to global climate change very detailed stratigraphic techniques are required the global signal of ice volume changes recorded in the oxygen isotopic composition of foraminifera can provide the tool for developing the necessary high resolution stratigraphy in order to evaluate the resolution of a stratigraphy based on detailed isotopic records two techniques are used to correlate a set of benthic oxygen isotope records from seven piston cores taken in the north and south atlantic the indian and the equatorial and north pacific oceans the first technique was modified from the graphic correlation procedure of shaw 1964 this procedure requires the identification of isotopic events that are correlated from core to core detailed correlations for intervals of the cores between events are provided by a series of straight line segments connecting all common events the second technique developed by martinson et al 1982 uses inverse procedures to define a continuous non linear mapping function that correlates the isotopic records the mapping function maximizes the correlation coefficient between data sets being compared the techniques are independent in that they rely on different criteria for correlating the data series stratigraphic correlations obtained by these procedures are in excellent agreement the mean difference between the correlations is on the order of the sampling intervals of each core and when corrected for sedimentation rates suggests that benthic isotope records from the suite of seven cores can be correlated to a resolution of 2000 to 4000 yrs

late quaternary palaeoceanography of the circumpolar deep water from the south tasman rise we use sediment cores from the south tasman rise str to reconstruct deepwater circulation in the southwest pacific sector of the southern ocean sediment cores md972106 45 09 s 146 17 e 3310 m water depth and gc34 45 06 s 147 45 e 4002 m water depth preserve records covering the last 160 k yr with chronology controlled by calibrated accelerator mass spectrometry radiocarbon dates and benthic foraminiferal 18o tied to specmap the stir benthic foraminiferal 13c records provide new 13c values for southern ocean deep water spanning the last 160 kyr at sites unlikely to be affected by variations in productivity the records establish that glacial benthic foraminifera cibicidoides spp 13c values are lower relative to interglacial values and are comparable to previous glacial benthic 13c records in the indian and pacific sectors of the southern ocean comparisons of the benthic foraminiferal 13c time series at the str are made with the equatorial pacific v19 30 and site 846 and the equatorial atlantic geob1115 the similarity of benthic 13c records at the str to the equatorial pacific suggest the southern ocean deep water mass closely tracked those of the deep pacific and the presence of a 13c gradient between the str and the equatorial atlantic suggests there was continual production of northern source deep water over the past 160 k yr

deep sea benthic foraminiferal assemblage response to a surface ocean productivity gradient a test a transect of samples from the eastern equatorial pacific where surface ocean productivity is the only changing environmental variable was used to test the response of benthic foraminiferal assemblages to an open ocean productivity gradient the transect runs along the east pacific rise from the highly productive waters near the equator to the oligotrophic south pacific subtropical gyre surface sediment benthic assemblages show progressive change along the transect with strong compositional shifts corresponding to the rapid productivity gradient near the equator and to the position of the southern convergence near 18 19 s the relationship of the assemblages to surface ocean productivity was tested by statistical regression of quantitative estimates of productivity on the assemblage principal component scores calculated for each sampling location the regression yielded an r squared of 0 87 demonstrating a clear relationship between surface ocean productivity and deep sea benthic foraminiferal assemblage composition the species most important to this relationship display a consistent response to oceanic productivity for long stretches of geologic time this conservative behavior and the results of the regression analysis indicate that benthic foraminiferal assemblages can be used to estimate surface ocean productivity for the geologic past

late quaternary caco3 production and preservation in the southern ocean implications for oceanic and atmospheric carbon cycling recent geochemical models invoke ocean alkalinity changes particularly in the surface southern ocean to explain glacial age pco2 reduction in such models alkalinity increases in glacial periods are driven by reductions in north atlantic deep water nadw supply which lead to increases in deep water nutrients and dissolution of carbonate sediments and to increased alkalinity of circumpolar deep water upwelling in the surface southern ocean we use cores from the southeast indian ridge and from the deep cape basin in the south atlantic to show that carbonate dissolution was enhanced during glacial stages in areas now bathed by circumpolar deep water this suggests that deep southern ocean carbonate ion concentrations were lower in glacial stages than in interglacials rather than higher as suggested by the polar alkalinity model broecker and peng 1989 our observations show that changes in southern ocean caco3 preservation are coherent with changes in the relative flux of nadw suggesting that southern ocean carbonate chemistry is closely linked to changes in deepwater circulation the pattern of enhanced dissolution in glacials is consistent with a reduction in the supply of nutrient depleted water nadw to the southern ocean and with an increase of nutrients in deep water masses carbonate mass accumulation rates on the southeast indian ridge 3200 3800 m and in relatively shallow cores 3000 m from the kerguelen plateau and the south pacific were significantly reduced during glacial stages by about 50 the reduced carbonate mass accumulation rates and enhanced dissolution during glacials may be partly due to decreases in caco3 corg flux ratios acting as another mechanism which would raise the alkalinity of southern ocean surface waters the polar alkalinity model assumes that the ratio of organic carbon to carbonate production on surface alkalinity is constant even if overall productivity in the southern ocean were held constant a decrease in the caco3 corg ratio would result in increased alkalinity and reduced pco2 in southern ocean surface waters during glacials this ecologically driven surface alkalinity change may enhance deepwater mediated changes in alkalinity and amplify rapid changes in pco2

the δ13c in benthic foraminiferal tests of fontbotia wuellerstorfi schwager relative to the δ13c of dissolved inorganic carbon in southern ocean deep water implications for glacial ocean circulation models on a transect between 20 and 70 s in the eastern atlantic ocean and weddell sea water samples from 19 hydrographic stations and bottom water from 55 surface sediment samples taken with a multiple corer were investigated for the stable carbon isotopic composition of the total dissolved inorganic carbon 13c co2 these measurements were compared to 13c values determined on live specimens of the benthic foraminifer fontbotia wuellerstorfi and closely related genera from the same stations in addition at 16 stations the stable carbon isotope composition of sedimentary organic carbon was measured general deepwater and bottom water mass circulation patterns as inferred from the 13c co2 are in close agreement with those known from other nonconservative tracers very low 13c values of upper circumpolar deep water 0 3 pee dee belemnite pdb in the polar front region and the eastern limb of the weddell gyre coincide with nutrient maxima however a significant decoupling of the dissolved phosphate signal from the 13c co2 signal is indicated in the abyssal weddell sea we attribute this to temperature dependent fractionation processes during gas exchange of surface waters with the atmosphere at sites of bottom water formation multiple corer water from the sediment water interface is slightly 13c depleted relative to deepwater and bottom water 13 co2 the surface sediment organic carbon 13c is 3 to 4 lower south of the polar front than north of it and the 13corg in freshly accumulated phytodetritus is 3 to 4 lower than surface sediment organic carbon 13c comparison of live f wuellerstorfi 13c and related genera with bottom water 13c co2 exhibits at most stations between the subtropical front 41 s and the southern boundary of the antarctic circumpolar current 55 s a significant lowering of foraminiferal 13c values compilation of a mean last glacial interglacial 13c amplitude 13c from six published southern ocean cores results in a shift of 0 99 0 13 pdb this shift is greater than that in all other regions however all of these cores are from positions close to recent oceanic fronts thus for these peripheral areas of the southern ocean we suggest about half of the glacial interglacial shift can be explained by varying frontal zone positions and widths accompanied by a change in mode and height of export production

predictive modeling of the seismic cycle of the greater san francisco bay region the seismic cycle for the san francisco bay region is synthesized by a model combining the pre and post 1906 seismic histories the long term acceleration of seismic release seismic moment benioff strain release or event count in the seismic cycle and the shorter term accelerations preceding the larger earthquakes within that cycle are modeled using an empirical predictive technique called time to failure analysis in which rate of seismic release is proportional to an inverse power of the remaining time to failure the exponent of time to failure in the accelerating sequences appears to be scale invariant and the length of the full cycle is estimated at 269 50 years the 1989 loma prieta earthquake which is the culmination of the first subcycle in the present long term seismic cycle should have been predictable with an uncertainty of 2 years in time and 0 5 in magnitude although the specific location at loma prieta was not predictable by this technique if our model is correct and if the loma prieta earthquake is the culmination of a subcycle the san francisco bay region should be entering a relatively long 20 50 years period of seismic quiescence above magnitude 6 a great earthquake such as the 1906 san francisco event would appear to be more than a century in the future

detecting precursory earthquake migration patterns using the pattern informatics method 1 in this paper we analyze the evolution of seismic activity using a dynamic modification of the pattern informatics method this method identifies locations that have systematic fluctuations in seismicity on pi maps by investigating the evolution of hotspot configurations on the pi map and calculating the distance between hotspots and the epicenter of the impending large earthquake a migrating pattern of increasing or decreasing precursory change in seismicity is revealed we find that hotspots on the pi map appear increasingly closer to the epicenter as the time of the forthcoming earthquake is approached implying the existence of an earthquake preparation process the migration pattern and associated decreasing distance is confirmed by a stochastic test and therefore we conclude that a preparation process prior to large earthquakes can be detected

glacial interglacial changes in the east australian current the east australian current eac is the western boundary current of the south pacific gyre transporting warm tropical waters to higher southern latitudes recent modelling shows that the partial separation of the eac 32 s and the coupled formation of the tasman front 34 s are caused by a steep gradient in the zonally integrated wind stress curl analysis of oxygen isotope ratios 18o in the planktonic foraminifer globigerinoides ruber from sediment cores from the coral sea and tasman sea indicates that the eac separation shifted northward to between 23 and 26 s during the last glacial we suggest these results indicate a significant change in the pacific wind stress curl during the glacial given recent evidence for el nino like conditions in the pacific during the last glacial with a reduction in the east west sea surface temperature sst gradient we suggest that weaker trade winds combined with more northerly stronger westerlies were associated with a change to the wind stress curl which repositioned the eac separation and tasman front in contrast by 11 ka bp the eac separation was forced south of 26 s this southward shift was synchronous with a rapid warming of tropical ssts and the onset of a la nina like sst configuration across the tropical pacific it appears that the south pacific trade winds strengthened accordingly causing the eac to readjust its flow this readjustment of the eac marks the onset of modern surface ocean circulation in the southwest pacific but the present eac transport was only achieved in the late holocene after 5 ka bp

planktic foraminiferal and sea surface temperature record during the last 1 myr across the subtropical front southwest pacific planktic foraminiferal faunas and modern analogue technique estimates of sea surface temperature sst for the last 1 million years myr are compared between core sites to the north odp 1125 178 faunas and south dsdp 594 374 faunas of the present location of the subtropical front stf east of new zealand faunas beneath cool subtropical water stw north of the stf are dominated by dextral neogloboquadrina pachyderma globorotalia inflata and globigerina bulloides whereas faunas to the south are strongly dominated by sinistral n pachyderma 80 95 in glacials with increased g bulloides 20 50 and dextral n pachyderma 15 50 in interglacials beneath subantarctic water or saw canonical correspondence analysis indicates that at both sites sst and related factors were the most important environmental influences on faunal composition greater climate related faunal fluctuations occur in the south significant faunal changes occur through time at both sites particularly towards the end of the mid pleistocene climate transition mis18 15 e g decline of globorotalia crassula in stw disappearance of globorotalia puncticulata in saw and during mis8 5 interglacial sst estimates in the north are similar to the present day throughout the last 1 myr to the south interglacial ssts are more variable with peaks 4 7 c cooler than present through much of the early and middle pleistocene but in mis11 mis5 5 and early mis1 peaks are estimated to have been 2 4 c warmer than present these high temperatures are attributed to southward spread of the stf across the submarine chatham rise along which the stf appears to have been dynamically positioned throughout most of the last 1 myr for much of the last 1 myr glacial sst estimates in the north were only 1 2 c cooler than the present interglacial except in mis16 mis8 mis6 and mis4 2 when estimates are 4 7 c cooler these cooler temperatures are attributed to jetting of saw through the mernoo saddle across the chatham rise and or waning of the stw current to the south glacial sst estimates were consistently 10 11 c cooler than present similar to temperatures and faunas currently found in the vicinity of the polar front one interpretation is that these cold temperatures reflect thermocline changes and increased circumpolar surface water spinning off the subantarctic front as an enhanced bounty gyre along the south side of the chatham rise for most of the last 1 myr the temperature gradient across the stf has been considerably greater than the present 4 c during glacial episodes the stf in this region did not migrate northwards but instead there was an intensification of the temperature gradient across it interglacials 4 11 c glacials 8 14 c

testing earthquake prediction algorithms statistically significant advance prediction of the largest earthquakes in the circum pacific 1992 1997 abstract algorithms m8 and msc i e the mendocino scenario were used in a real time intermediate term research prediction of the strongest earthquakes in the circum pacific seismic belt predictions are made by m8 first then the areas of alarm are reduced by msc at the cost that some earthquakes are missed in the second approximation of prediction in 1992 1997 five earthquakes of magnitude 8 and above occurred in the test area all of them were predicted by m8 and msc identified correctly the locations of four of them the space time volume of the alarms is 36 and 18 correspondingly when estimated with a normalized product measure of empirical distribution of epicenters and uniform time the statistical significance of the achieved results is beyond 99 both for m8 and msc for magnitude 7 5 10 out of 19 earthquakes were predicted by m8 in 40 and five were predicted by m8 msc in 13 of the total volume considered this implies a significance level of 81 for m8 and 92 for m8 msc the lower significance levels might result from a global change in seismic regime in 1993 1996 when the rate of the largest events has doubled and all of them become exclusively normal or reversed faults the predictions are fully reproducible the algorithms m8 and msc in complete formal definitions were published before we started our experiment keilis borok v i kossobokov v g 1990 premonitory activation of seismic flow algorithm m8 phys earth and planet inter 61 73 83 kossobokov v g keilis borok v i smith s w 1990 localization of intermediate term earthquake prediction j geophys res 95 19763 19772 healy j h kossobokov v g dewey j w 1992 a test to evaluate the earthquake prediction algorithm m8 u s geol surv ofr 92 401 m8 is available from the iaspei software library healy j h keilis borok v i lee w h k eds 1997 algorithms for earthquake statistics and prediction vol 6 iaspei software library

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