tree rings and the climate of new caledonia sw pacific preliminary results from araucariacae abstract the dendroclimatologic potential of some araucariacae of new caledonia including agathis or kauris and araucaria is assessed using ring thickness and 18o measurements new caledonia is a group of islands in the sw pacific that are currently under influence of enso events endemic to new caledonia the long living species of agathis lanceolata and a ovata growing on poor ultramafic derived soils may provide valuable proxies for the local climate and for enso these trees present visible growth bands of changing thickness along their circumference however several bands are locally absent and the growth axis is generally offset with respect to the geometrical axis of the tree this led us to compute so called composite ring thickness profiles accounting for the geometry of growth bands on the whole surface of a tree disk our computational method involves 10 optical density profiles measured along 10 equally spaced radii drawn from the bark toward the growth axis and 10 to 20 master rings that can be easily identified on the whole disk growth bands visible on less than 5 radii were discarded our method is similar to the cross dating method used by dendrochronologists except that it is applied here to a single tree disk our samples consist of three disks of a lanceolata one disk of a ovata and one disk of araucaria columnaris multiple regressions have been computed between composite profiles and climatic variables i e monthly and yearly temperatures and rainfall amounts the best correlation is found between the width of the ring growing between july n 1 and june n with the rainfalls of june n june n 1 and june n 2 monthly rainfalls allow to explain between 20 to 50 of the ring thickness variance a result similar to that obtained with other studies on agathis of new zealand no temperature parameter appears in the most stable regressions 30 measurements of tree ring cellulose 18o have been conducted on one single disk selected for the strong climate ring width correlation while earlier studies have used 18o measurements to identify seasonal cycles in tropical woods and date the rings our data suggest that the direct use of 18o is misleading due to false rings that do not correspond to a complete growth year when these false rings are identified from the disk analysis and discarded a fair visual correlation with the total rainfall during the growth season is obtained this requires information that cannot be found in single growth band thickness profiles for example as obtained by coring thus araucariacae of new caledonia may present a valuable potential for dendroclimatology however reconstructing a chronology of this region will require more extensive sampling and possibly an account of additional species

geochemistry and skeletal structure of diploria strigosa implications for coral based climate reconstruction abstract geochemical tracers incorporated into the skeleton of reef building corals are ideal proxies for reconstructing environmental parameters of ambient seawater such as temperature and salinity at subseasonal resolution however validation concerns of these environmental proxies due to the complex skeleton of some tropical atlantic corals have hindered such coral based environmental reconstructions in this region compared to the tropical pacific in order to identify complications associated with the complex skeletal architecture of the massive brain coral diploria strigosa we performed microsampling experiments along and across individual skeletal elements we demonstrate that the mesoscale heterogeneity of sr ca 18o and 13c is a systematic feature of d strigosa and is linked to different vital effects between skeletal elements the thecal wall is significantly depleted in sr 18o and 13c compared to the adjacent septa and columella and differences between apparent temperature signatures of several degrees are greater for sr ca suggesting that this temperature proxy is more sensitive to skeletal mixing than 18o parallel subseasonal microsampling experiments performed along individual skeletal elements of a single corallite of a d strigosa coral which grew at a rate of 0 65 cm year allow for investigating potential biases associated with its complex skeletal mesoarchitecture highest correlation between sr ca and 18o from skeletal material retrieved from the centre of the thecal wall suggests that microdrilling the theca provides the best environmental signal compared to adjacent microsampling profiles moreover based on monthly mean climatology the temperature dependence of sr ca for this profile is comparable to previous calibrations published from faster growing d strigosa based on these results we conclude that accurate microsampling along the centre of the thecal wall of d strigosa is a prerequisite for generating robust climate reconstructions from its skeleton

automatic lineament extraction from potential field images using the radon transform and gradient calculation linear anomalies are critical in the interpretation of gravity and magnetic data visual identification of lineaments is usually done by experienced interpreters and identification results then have to undergo a digitization or import procedure the traditional identification method has unavoidable subjectivity and inefficiency to overcome these limitations we fuse the radon transform rt with gradient calculation to process gravity or magnetic data and to realize automatic detection and extraction of lineaments as part of the detection procedure we define the rt based mean gradient mg effective mean gradient emg and residual mean gradient rmg in order to highlight long linear segments or to enhance short linear ones in the transform domain the gradient forms are applied self adaptively and self selectively to gravity or magnetic images according to specific conditions gradient directions are also taken into account in the transformation procedure to emphasize the characteristics of linear anomalies to extract the position and length of the detected lineaments from the transform domain a constraint inverse searching method cism is given and used to locate the starting and end points of the lineaments the method can deal with the condition that there is at least one linear section in a specific direction or that separate linear sections may belong to one lineament through tests with synthetic images and with real data from the haijiao upheaval area in the east china sea basin the detection and extraction methods are shown to be more effective and robust than the conventional rt applications the results from the real data roughly coincide with major geologic faults that are visually identified these results show that the methods constitute a useful tool to aid fault interpretation

lateral variation of crustal properties from aerogeophysical data in northern brazil abstracta new method is proposed for the study of crustal azimuthal anisotropy and the lateral variation of other crustal aerogeophysical parameters using a quantitative approach the processing of a large newly acquired high resolution set of aerogeophysical data is considered using the existing radon transform and the geostatistical analysis approaches the data set includes an area of the guyana shield in northern brazil which was not included in previous surveys the area is covered by dense rain forest vegetation and thick soil layers parameterization was performed considering the possible anisotropic character of the geophysical 2d data application of the newly proposed geostatistical data processing yielded high resolution images of the lateral variation of quantitative geophysical parameters which indicate good correlation with previously determined seismic anisotropy in the area average anisotropy as measured by the radon transform and variogram analysis is scale dependent at scales gr

semiautomated geologic mapping using self organizing maps and airborne geophysics in the brazilian amazon abstracta self organizing map som approach has been used to provide an integrated spatial analysis and classification of airborne geophysical data collected over the brazilian amazon magnetic and gamma ray spectrometric data were used to extract geophysical signatures related to the spatial distribution of rock types and to produce a geologic map over the prospective anapu tuere region particular emphasis was given to discriminating and identifying rock types and the processes related to gold mineralization which are known to occur in the anapu tuere region som was able to identify and map distinctive geophysical signatures related to the various geologic units identified on the published geologic map furthermore som was able to identify and enhance very subtle signatures derived jointly from the magnetic and gamma ray spectrometric data that could be related to geologic processes present in the area these results demonstrate the effectiveness of using som as a tool for geophysical data analysis

seasonal and interannual variability of the mid holocene east asian monsoon in coral δ18o records from the south china sea understanding the full range of past monsoon variability with reference to specific monsoon seasons is essential to test coupled climate models and improve their predictive capabilities we present a 54 year long high resolution skeletal oxygen isotope 6180 record extracted from a well preserved massive porites sp coral at hainan island south china sea to investigate east asian monsoon variability during summer and winter similar to 4400 calendar yr ago analysis of modem coral 6180 confirms that porites from hainan island are well positioned to record winter monsoon forcing of sea surface temperature sst as well as the influence of summer monsoon rainfall on sea surface salinity sss the coral record for similar to 4400 yr ago shows similar to 9 amplification of the annual cycle of 6 delta o 18 in good agreement with coupled ocean atmosphere models showing higher summer rainfall lower coral 618 0 and cooler winter ssts higher coral delta o 18 in response to greater northern hemisphere insolation seasonality during the middle holocene mean ssts in the south china sea during the mid holocene were within 0 5 degrees c of modem values yet the mean 6 180 for the fossil coral is similar to 0 6 parts per thousand higher than that for the modem coral suggesting that the 6 180 of surface seawater was higher by at least similar to 0 5 parts per thousand relative to modem values the o 18 enrichment is likely to be driven by greater advection of moisture towards the asian landmass enhanced monsoon wind induced evaporation and vertical mixing and or invigorated advection of saltier o 18 enriched pacific water into the relatively fresh south china sea the o 18 enrichment of the northern south china sea similar to 4400 yr ago contributes to mounting evidence for recent freshening of the tropical western pacific today winter sst and summer sss variability in the south china sea reflect the interannual influence of enso and the biennial variability inherent to monsoon precipitation spectral analysis of winter ssts similar to 4400 yr ago reveals a strong enso cycle at 6 7 y which is significantly longer than the average 3 6 y cycle observed since 1970 the results suggest that the influence of enso on winter ssts in the south china sea was well established by similar to 4400 yr ago however spectral analysis of summer sss similar to 4400 yr ago shows no significant enso cycle suggesting that teleconnections between enso and summer monsoon rainfall were restricted taken together the results indicate marked differences in enso monsoon interactions during the winter and summer monsoon seasons in the past the fossil coral delta o 18 record also shows that the amplitude of interannual sst and sss variability was stronger similar to 4400 yr ago despite enso variability being significantly weaker in the pacific region thus it appears that the strengthened mid holocene monsoon was sensitive to forces other than enso that acted as alternative drivers of interannual monsoon variability if this is the case greater interannual climate variability could accompany the strengthening of the asian monsoon predicted to occur during the 21st century as transient greenhouse warming preferentially warms eurasia even if enso perturbations remain relatively stable c 2005 elsevier b v all rights reserved

middle to late jurassic equatorial seawater temperatures and latitudinal temperature gradients based on stable isotopes of brachiopods and oysters from gebel maghara egypt abstract stable isotope 18 o 13 c analyses of brachiopod and oyster shells from the gebel maghara egypt were used to reconstruct the first detailed dataset on peri equatorial water temperatures during the middle to late jurassic throughout this time interval temperatures remained relatively constant around an average of 25 7 c slightly warmer conditions existed in the early bathonian 27 0 c while the kimmeridgian shows the lowest temperatures 24 3 c as expected for a tropical palaeolatitude the seasonality was very low 18 o value of seawater

ross ice shelf response to climate driven by the tectonic imprint on seafloor bathymetry ocean melting has thinned antarctica s ice shelves at an increasing rate over the past two decades leading to loss of grounded ice the ross ice shelf is currently close to steady state but geological records indicate that it can disintegrate rapidly which would accelerate grounded ice loss from catchments equivalent to 11 6 m of global sea level rise here we use data from the rosetta ice airborne survey and ocean simulations to identify the principal threats to ross ice shelf stability we locate the tectonic boundary between east and west antarctica from magnetic anomalies and use gravity data to generate a new high resolution map of sub ice shelf bathymetry the tectonic imprint on the bathymetry constrains sub ice shelf ocean circulation protecting the ice shelf grounding line from moderate changes in global ocean heat content in contrast local seasonal production of warm upper ocean water near the ice front drives rapid ice shelf melting east of ross island where thinning would lead to faster grounded ice loss from both the east and west antarctic ice sheets we confirm high modelled melt rates in this region using rosetta ice radar data our findings highlight the significance of both the tectonic framework and local ocean atmosphere exchange processes near the ice front in determining the future of the antarctic ice sheet the boundary between west and east antarctica is a tectonic feature that bisects the ross ice shelf this boundary constrains ocean circulation under the ice which affects ice stability according to airborne survey data and ocean simulations

oxygen isotope systematics in diploastrea heliopora new coral archive of tropical paleoclimate diploastrea heliopora forms dense robust dome shaped coral colonies throughout the reef ecosystems of the tropical pacific and indian oceans this slow growing 2 to 6 mm yr coral has the potential to yield continuous paleoclimate records spanning up to 1000 yr for the warmest waters on earth the indo pacific warm pool and has a long fossil history as a single recognizable species despite the potential of diploastrea to be an important new paleoclimate archive little is known about the systematics of geochemical tracers incorporated into its skeleton to fill this knowledge gap we compared skeletal delta 18 o signatures in live diploastrea and porites colonies from southwest lagoon near amedee lighthouse new caledonia at the southern latitudinal limit for diploastrea and alor indonesia in the core area of the indo pacific warm pool we designed a new microsampling technique to minimize smoothing and distortion of the isotopic records due to the complex calyx architecture and slow growth of diploastrea high resolution isotope profiles from the septal portion of the diploastrea corallite are attenuated whereas those restricted to the central columella are similar in quality to those extracted from the well established porites coral archive the delta 18 o temperature relationship for the columellar portion of diploastrea 0 18parts per thousand degreesc is in good agreement with that derived for a nearby porites 0 19parts per thousand degreesc quinn et al 1996 on the basis of comparison with an in situ sea surface temperature record from amedee lighthouse there is a measurable difference of 0 3 0 1parts per thousand between the kinetic biological disequilibrium offsets from seawater delta 18 o composition for diploastrea and porites despite this offset in mean delta 18 o diploastrea accurately records the regional differences in mean temperature and salinity between new caledonia and the indo pacific warm pool additional tests show that diploastrea records el nino southern oscillation enso interannual variability in sea surface temperature and salinity across the southwestern pacific indicating that it should yield dependable paleo enso records based on these results we propose that d heliopora has the potential to provide an important new coral archive of tropical paleoclimate c copyright 2003 elsevier science ltd

el nino during the last interglacial period recorded by a fossil coral from indonesia measurements of oxygen isotopes and elemental ratios in a fossil coral that grew 124 000 years ago in north sulawesi indonesia reflect interannual variability in precipitation and sea surface temperature sst due to the el nino southern oscillation enso this indicates that enso was robust during the last interglacial period a time when global climate was slightly warmer than the present the pattern of enso frequency behavior in the past is similar to variability in modern instrumental records but distinct from the most recent period since the mid 1970s supporting the hypothesis that enso behavior in recent decades is anomalous with respect to natural variability

geochemistry based coral palaeoclimate studies and the potential of non traditional non massive porites corals recent developments and future progression understanding the natural variability of the earth s climate system and accurately identifying potential anthropogenic influences requires long term geographically distributed records of key climate indicators such as temperature and precipitation that extend prior to the last 400 years of the holocene reef corals provide an excellent source of high resolution climate records and importantly represent the tropical marine environment where palaeoclimate data are urgently required recent decades have seen significant improvement in our understanding of coral biomineralisation the associated uptake of geochemical proxies and methods of identifying and understanding the effects of both early and late post depositional diagenetic alteration these processes all have significant implications for interpreting geochemical proxies relevant to palaeoclimatic reconstructions this paper reviews the current state of the art in terms of coral based palaeoclimate reconstructions and highlights a key remaining problem the majority of coral based palaeoclimate research has been derived from massive colonies of porites however massive porites are not globally abundant and may not provide material of a particular age of interest in those regions where they are present therefore there is great potential for alternate coral genera to act as complimentary climate archives while it remains critical to consider five key factors vital effects differential growth morphologies geochemical heterogeneity in the skeletal ultrastructure transfer equation selection and diagenetic screening of skeletal material in order to allow the highest level of accuracy in coral palaeoclimate reconstructions it is also important to develop alternate taxa for palaeoclimate studies in regions where porites colonies are absent or rare currently as many as nine genera other than porites have proven at least limited utility in palaeothermometry most of which are found in the atlantic caribbean region where massive porites do not exist even branching taxa such as acropora have significant potential to preserve environmental archives increasing this capability will greatly expand the number of potential geochemical archives available for longer term temporal records of palaeoclimate

diploastrea heliopora sr ca and δ18o records from northeast luzon philippines an assessment of interspecies coral proxy calibrations and climate controls of sea surface temperature and salinity

refining temperature reconstructions with the atlantic coral siderastrea siderea abstract developing coral based temperature reconstructions for a particular coral species requires determining the optimal sampling path orientation and resolution for geochemical analysis to avoid sampling artifacts and to increase reproducibility furthermore a robust coral archive should have high intracolony and intercolony reproducibility for determining the common environmental signal here we assessed sampling path orientation and sampling resolution for siderastrea siderea colonies within the dry tortugas national park in the gulf of mexico 24 42 n 82 48 w to determine the optimal sampling protocol and to assess reproducibility of coral sr ca 18o and 13c we identified a sampling artifact due to extracting samples from the coral columella resulting in cold bias up to 5 2 c in coral sr ca we found no shift to higher coral sr ca values i e colder for years with a 50 reduction in average extension rate 2 1 mm year 1 or for sampling along paths up to 70 off the vertical axis of the colony our sampling resolution comparison 1900 1993 indicated that the resolution of 6 samples year 1 used in a previous study for coral sr ca and 18o may not capture seasonal extremes and thus produces muted seasonal cycles but that resolution is not biased towards one season reproducibility or average deviations assessed using absolute differences ad and root mean square rms among the monthly resolved coral sr ca records for intracolony to intercolony comparisons were within 2 of our analytical precisions average deviations were reduced by 19 to 61 when assessing interannual variability 36 month smoothed and mean annual suggesting that subannual dating uncertainties i e assigning a coral sr ca value to a particular month were the largest source of error in our monthly resolved coral sr ca reconstruction similarly coral 18o was reproducible within 2 of our analytical precision ad 0 10 and rms 0 07 however coral 13c and linear extension records were not reproducible our assessment of coral geochemical variations from multiple s siderea colonies suggests this species is suitable for paleoclimatic reconstructions including subfossil corals and microatoll colonies that grow laterally

tectonic fault control of wetland distributions in the central amazon revealed by jers 1 radar imagery abstract a mosaic of jers 1 l band synthetic aperture radar sar images was used to investigate the influence of tectonic faults on wetland distributions in 200 000 km2 of central amazon lowland 0 4 lat s 60 64 long w the geographic distribution of flooded wetland was clearly evident on the mosaic due to the unique characteristics of l band radar two distinct linear boundaries were encountered limiting the northern distribution of wetlands one north of the negro river main channel and west of the branco river oriented wnw ese and one south of the negro main channel and east of the branco oriented nw se the orientations and positions of these boundaries were consistent with the prevailing tectonic fracture pattern in the region geophysical pedological and geomorphological data supported the hypothesis that these boundaries are tectonically controlled the ecological economic and biogeochemical implications of the observed wetland distribution were considered the distributions of wetland dependent biota were expected to be severely limited north of the negro main channel fish production wetland timber yields and methane emissions were also predicted to be exceptionally low in this region

reliability of coral isotope records from the western pacific warm pool a comparison using age optimized records stable isotope analysis of two separate corals from nauru island in the warm pool of the western tropical pacific confirm that coral oxygen isotopes are a robust recorder of environmental variables coral delta 18 o faithfully records interannual variability even when strongly influenced by kinetic effects interannual to decadal variability of coral delta 13 c remains enigmatic only one of the two corals exhibits the expected light delta 13 c response in the interannual band coral delta 18 o from this region has a great similarity to global instrumental temperature records reflecting the impact of the pacific warm pool and variations of the indonesian low in concert with el nino southern oscillation on global climate since 1896 coral delta 18 o has exhibited a cumulative decrease of 0 7 parts per thousand which reflects a combination of warming and more frequent el nino events precipitation affecting the surface waters of this region

fidelity of δ18o as a proxy for sea surface temperature influence of variable coral growth rates on the coral porites lutea from hainan island china 1 the extremely high temporal resolution nearly daily interval measurement was conducted on the coral porites lutea oxygen isotope compositions 18oc to examine the detailed relationship between 18oc and sea surface temperature sst and seawater oxygen isotope composition 18ow from hainan island china although sst and sea surface salinity sss or 18ow varied in a wide range at the studied site the dynamic range of 18oc recorded in coral was much smaller than expected from sst and sss 18ow changes the extremely high 30 c and low 22 c sst and low 27 sss are not suitable for coral calcification and coral could not record the information as their skeletal 18o estimated coral extension rates the overall rate is 15 mm year varied by a factor of about 18 within one year from very slow in winter to very fast in spring light availability could affect the extension rate of coral skeleton through the activity of photosynthesis of symbiont algae such cessation and acceleration of calcification cause a serious distortion of the 18o profile which makes it difficult to make a correlation between 18o and sst because high and low extension rates correspond to low and high density bands respectively a detailed examination of the density structure may assist the correction for distortion of the 18o profile

high resolution isotopic records from corals using ocean temperature and mass spawning chronometers abstract we present a 6 year long 1978 1984 18 o and 13 c record from a great barrier reef pandora reef porites lutea coral based on near weekly sample intervals a sampling technique was designed to minimise any smoothing or distortion of the isotopic record due to complex coral growth calyx architecture and calcification at depth within the tissue layer the arrival time of the mid winter minimum sea surface temperature is very consistent 2 weeks near pandora reef and provides an annual time marker offering more precision than the traditional density band chronometer the improved chronology and high resolution record demonstrate that signal distortion in porites due to calcification within the tissue layer and variable intra annual coral extension is generally negligible also confirmed is that the arrival time of monsoonal floods is precisely preserved 1 week within the skeleton of porites the sensitivity of weekly sampling allows the detection of a subtle warm to cool sea surface temperature anomaly which preceded by more than one year a similar temperature anomaly associated with the 1982 83 el nin o in the east pacific sharply higher 13 c values coincide with the time of the annual coral mass spawning event in the great barrier reef recognition of this mass spawning signal should simplify the interpretation of coral 13 c records and provides an additional precise time marker with which to adjust chronologies when intra annual coral extension is not constant

calibration of stable oxygen isotopes in siderastrea radians cnidaria scleractinia implications for slow growing corals geochemical proxies in the skeletons of corals used for the purpose of reconstructing environmental records have typically been obtained from relatively fast growing corals usually 8 mm yr 1 and from only a few key genera most commonly porites and montastraea in many areas however there are no suitable fast growing corals available for such reconstructions here we investigate the potential of siderastrea radians a slow growing atlantic and caribbean zooxanthellate coral as an archive of sea surface temperature sst and salinity over the period from 1891 to 2002 sampling the skeleton of three corals from the cape verde islands we were able to reproduce a clear seasonal signal but with limited correlation to monthly sst arising from inadequate chronologic constraint of the individual samples the sst 18o calibration slopes for different sampling scales on several cores can range from about 9 c 1 to 2 c 1 compared to other published values of around 5 to 4 c 1 careful treatment produced a 18o sst calibration equation where sst c 12 56 1 20 3 86 0 39 c w the recognition of the limitations of calibration at such small growth rates due to skeletal complexity and suspicion of environmental interferences suggests the need for careful consideration in the interpretation of climate proxy results from s radians and other slow growing corals

quaternary raised coral reef terraces on sumba island indonesia a spectacular sequence of coral reef terraces six steps broader than 500 meters and many minor substeps is developed near cape laundi sumba island between an ancient patch reef 475 meters high and sea level several raised reefs have been dated with the electron spin resonance and the uranium series dating methods the uplift trend deduced from these reefs is 0 5 millimeter per year most terraces although polycyclic in origin appear to correspond to specific interglacial stages with the oldest terrace formed 1 million years ago this puts them among the longest and most complete mid quaternary terrace sequences

the oxfordian stable isotope record δ18o δ13c of belemnites brachiopods and oysters from the kachchh basin western india and its potential for palaeoecologic palaeoclimatic and palaeogeographic reconstructions abstract the study combines the results of stable isotope 13c 18o analyses of 187 belemnites brachiopods and oysters from the middle to upper jurassic upper callovian to kimmeridgian of the kachchh basin in western india generally belemnites show lower 13c and higher 18o ratios than the benthic fauna it is proposed that this discrepancy is caused by different life habitats of both groups with belemnites spending major parts of their life in deeper water outside the kachchh basin and entering shallow areas only occasionally e g during seasonal migrations to spawning grounds a mode of life as fast swimming nektonic predators similar to many modern squid species seems plausible the study emphasises that results of stable isotope analyses should be evaluated separately for each fossil group in addition to the influence of diagenetic alteration weathering salinity changes and sea level fluctuations the ecology of the analysed fossil taxa has to be considered temperatures calculated from 18o ratios point to relatively warm conditions around the middle to late jurassic transition with no evidence for a glacial phase which had been proposed for this boundary a distinct fall in temperatures is observed during the middle oxfordian reaching a minimum in the early late oxfordian it is tempting to connect this event with the break up of gondwana causing stronger upwelling in the northwestern tethys or alternatively the influx of polar water by the opening of the transgondwanan seaway however such connections cannot be verified without further data preferably from localities in the southern malagasy gulf e g madagascar and from younger horizons kimmeridgian tithonian

eastern pacific sea surface temperature since 1600 a d the δ18o record of climate variability in galapagos corals we measured stable oxygen isotope ratios and skeletal growth rates in the massive corals pavona clavus and p gigantea from the west coast of isabela island galapagos to assess interannual to decadal climate variability in the eastern pacific comparisons of instrumental data sets show that sea surface temperatures sst in the galapagos region are representative of a broad portion of the eastern equatorial pacific the site is especially well suited for long term studies of the el nino southern oscillation enso phenomenon as it lies within the eastern pacific center of action for thermal anomalies associated with enso the p gigantea isotope record is nearly monthly in resolution spans the period 1961 1982 and shows strong correlation with a galapagos instrumental sst record r 0 90 for annual averages cross spectral analysis shows that sst can explain greater than 80 of the variance in 18o at both the annual cycle and within the high frequency portion of the enso band 3 5 years the p clavus record is annual in resolution extends from 1587 to 1953 a d and was obtained from a 10 m diameter colony preserved within the urvina bay uplift because seawater 18o variations in the region are very small we interpret the urvina bay coral 18o record in terms of annual average sst the isotopic record appears to be a very good but not perfect indicator of enso events and shows good correspondence with the historical enso reconstruction of quinn et al 1987 a number of low 18o excursions that we observe during the 17th and 18th centuries very likely represent enso events that are missing from the historical tabulations most interannual 18o variations between 1607 and 1953 a d represent annual average temperature excursions of 1 to 2 5 c during the little ice age the annual 18o series correlates well with many north american tree ring records and shows low temperatures during the early 1600s and early 1800s and relatively warmer conditions during the 1700s unlike most northern hemisphere tree ring and instrumental records we see no evidence at this site for warming between 1880 and 1940 but rather observe a slight cooling 28 of the total variance the main enso mode is centered at 4 6 years and accounts for 12 of the total variance additional significant oscillations occur at periods of 3 3 6 8 11 17 22 and 34 years both annual growth rate and 18o show variance at periods equivalent to the solar and solar magnetic periods e g 11 and 22 years respectively in addition the amplitude of the 11 year 18o cycle generally varies with the amplitude of the solar cycle supporting previous suggestions that the solar cycle may modulate interannual to decadal climate variability in the tropics the dominant oscillatory modes both within the enso and interdecadal frequency bands shift to shorter periods from the early to middle 1700s and again from the middle to late 1800s this may reflect major reorganizations within the tropical ocean atmosphere system and suggests that tropical pacific climate variability is linked across timescales ranging from years to decades

evaluating the use of the massive coral diploastrea heliopora for paleoclimate reconstruction 1 to date coral based paleoclimate research in the pacific has primarily utilized core samples from the genus porites and has been most successful reconstructing past variability on interannual timescales particularly the el nino southern oscillation enso the indo pacific coral genus diploastrea however owing to its slower extension rate denser structure and longer lifespan can potentially preserve geochemical proxy records 2 3 times longer than porites cores of the same length before its potential can be realized diploastrea must first be calibrated and its climate signal assessed we present oxygen isotope 18o and sr ca results from two diploastrea cores collected in fiji 16 49 s 179 14 e that allow for simultaneous evaluation of this coral s paleoclimatic utility and the reproducibility of each tracer at this site comparison to a porites record from the same location allows for further evaluation of diploastrea as a paleoclimatic archive we demonstrate that diploastrea s septal and columellar material yield similar 18o sst relationships and that despite some sacrifice of the seasonal 18o amplitude bulk sampling of either region is satisfactory for resolving interannual and lower frequency modes of climatic variability therefore paleoclimate reconstructions employing either a septal or columellar sampling regime of this genus may be useful at filling in spatial and temporal sampling gaps which currently hinder the reconstruction of long term changes in major climate fields in the western pacific

new views of tropical paleoclimates from corals abstract corals offer a rich archive of past climate variability in tropical ocean regions where instrumental data are limited and where our knowledge of multi decadal climate sensitivity is incomplete in the eastern equatorial pacific coral isotopic records track variations in enso related changes in sea surface temperature further west corals record variability in sea surface temperature and rainfall that accompanies zonal displacement of the indonesian low during enso events these multi century records reveal previously unrecognised enso variability on time scales of decades to centuries outside the enso sensitive equatorial pacific long term trends towards recent warmer wetter conditions suggest the tropics respond to global forcings new coral paleothermometers indicate that surface ocean temperatures in the tropical southwestern pacific were depressed by 4 6 c during the younger dryas climatic event and rose episodically during the next 4000 yr high temporal resolution measurements of sr ca and 18 o in corals provide information about the surface ocean hydrologic balance and can resolve the seasonal balance between precipitation and evaporation radiocarbon measurements in corals coupled with ocean circulation models may be used to reconstruct near surface ocean circulation past mixing rates and the distribution of fossil fuel co2 in the upper ocean most recently seasonal to interannual variations in the radiocarbon of corals from the equatorial pacific have been linked to the redistribution of surface waters associated with the enso

coralline algal growth increment widths archive north atlantic climate variability over the past decade coralline algae have increasingly been used as archives of paleoclimate information encrusting coralline algae which deposit annual growth increments in a high mg calcite skeleton are amongst the longest lived shallow marine organisms in fact a live collected plant has recently been shown to have lived for at least 850 years based on radiometric dating while a number of investigations have successfully used geochemical information of coralline algal skeletons to reconstruct sea surface temperatures less attention has been paid to employ growth increment widths as a temperature proxy here we explore the relationship between growth and environmental parameters in clathromorphum compactum collected in the subarctic northwestern atlantic results indicate that growth increment widths of individual plants are poorly correlated with instrumental sea surface temperatures sst however an averaged record of multiple growth increment width time series from a regional network of c compactum specimens up to 800 km apart reveals strong correlations with annual instrumental sst since 1950 hence similar to methods applied in dendrochronology averaging of multiple sclerochronological records of coralline algae provides accurate climate information a 115 year growth increment width master chronology created from modern collected and museum specimens is highly correlated to multidecadal variability seen in north atlantic sea surface temperatures positive changes in algal growth anomalies record the well documented regime shift and warming in the northwestern atlantic during the 1990s large positive changes in algal growth anomalies were also present in the 1920s and 1930s indicating that the impact of a concurrent large scale regime shift throughout the north atlantic was more strongly felt in the subarctic northwestern atlantic than previously thought and may have even exceeded the 1990s event with respect to the magnitude of the warming

reconstruction of seasonal temperature variability in the tropical pacific ocean from the shell of the scallop comptopallium radula we investigated the oxygen isotope composition d 18 o of shell striae from juvenile comptopallium radula mollusca pectinidae specimens collected live in new caledonia bottom water temperature and salinity were monitored in situ throughout the study period external shell striae form with a 2 day periodicity in this scallop making it possible to estimate the date of precipitation for each calcite sample collected along a growth transect the oxygen isotope composition of shell calcite d 18 oshell calcite measured at almost weekly resolution on calcite accreted between august 2002 and july 2003 accurately tracks bottom water temperatures a new empirical paleotemperature equation for this scallop species relates temperature and d 18 oshell calcite

carbon and oxygen isotope composition of nautilus macromphalus a record of thermocline waters off new caledonia abstract this study investigates the controls on the stable isotope composition of shell nacreous layer of a modern nautilus macromphalus from new caledonia closely spaced samples were taken both along growth lines isochrons and growth axis time series carbon isotope compositions 13 c 0 3 to 1 pdb of the shell decrease in the domains of maximal growth 0 3 and muscle insertion 0 4 maximal 13 c variations of about 1 are recorded in time series a global ontogenetic decrease of 13 c values is observed for both dorsal and ventral areas 0 4 to 0 8 and can be ascribed to a metabolic effect with age or to changes in the food source by contrast oxygen isotope compositions are quite constant 1 1 18 o

ontogeny and habitat change in mesozoic cephalopods revealed by stable isotopes δ18o δ13c abstract stable isotope 18 o and 13 c ratios were measured in successive aragonitic shell sequences of ammonoids class cephalopoda to determine whether their depth distributions changed within ontogeny and whether stable isotope values differ in various morphological groups e g leiostraca vs trachyostraca we concentrate mainly on 18 o for temperature results and added 13 c data to obtain information on the ontogenetic history for which full spiral measurements were undertaken for the first time to obtain valid stable isotope data from ammonoid shells we measured ontogenetic sequences full shell within different genera data sets from the jurassic cadoceras and cretaceous hypacanthoplite s nowakites were chosen due to the pure primary aragonitic shell preservation the study was designed to extract better information on the habitat and life cycle of fossil cephalopods e g ammonoids in comparison with recent cephalopods e g nautilus spirula sepia possessing equivalent or comparable hard parts the data from three genera suggest different modes of life in at least two morphological groups we detected and established two main groups with different ontogenetic strategies based on the 18 o data the wcw type warm cool warm type of cadoceras resembles strategies in nautilus and sepia which migrate from shallow into deeper environments and back in ontogeny wc type warm cool type and the cw type cool warm type of hypacanthoplites resembling the first two migration phases of spirula cwc type which migrates from deeper into shallower and back again into deeper habitats the main three phases revealed by both 18 o and 13 c data sets most probably reflect diet changes in juvenile to mid aged individuals followed by a habitat change for spawning adults in cadoceras the temperatures range from 21 2 c for juveniles down to 12 1 c for mid aged individuals and back up 16 9 c in adults the cw type strategy of hypacanthoplites involves a temperature range of 22 8 c to 28 9 c the respective mean values are 24 2 c juveniles 25 8 c middle phase and 27 8 c adults the 13 c values also revealed three ontogenetic stages in cadoceras and hypacanthoplites including two major shifts from positive to negative and from negative to positive values which probably correspond to sexual maturation the initiation of reproduction and concomitant changes in diet the presented data combined with previous ontogenetic studies e g stable isotopes on spirula nautilus and sepia can be used as proxies to directly correlate the habitats and ontogeny of recent and fossil cephalopods

comparing crustal and mantle fabric from the north american craton using magnetics and seismic anisotropy a central target in earth sciences is the study of deformation at various depth levels within the earth seismology has offered a remarkable tool for doing this via seismic anisotropy it is however not always clear how to interpret those observations a question of interest is to understand the relation between the deformation of the mantle and the crust and in studying the relation between the two mantle deformation is expressed in seismic anisotropy in this paper we seek an objective way of extracting information about crustal fabric as well to be able to compare with seismic anisotropy the magnetization of crustal rocks offers an attractive possibility for doing this we thus explore the use of magnetic data and we compare magnetic crustal fabric orientation with mantle fabric observations from seismic anisotropy we apply our technique to the north american craton for which we have an excellent magnetic dataset and we show that there is a clear relation between crustal and mantle fabric for the cratonic region this has important implications for crustal formation and for interpreting seismic anisotropy observations

oxygen isotope fractionation in marine aragonite of coralline sponges oxygen isotope values of the extant caribbean coralline sponge ceratoporella nicholsoni are compared with published temperatures and 18o of water calculated from salinities the measured values from aragonitic sponge skeletons have a mean offset of 1 0 0 1 from calculated calcite equilibrium values aragonite calcite 1 0010 this is in good agreement with published values from synthetic aragonite they further agree with published near equilibrium oxygen isotope values of temperate and cold water molluscs and foraminifera extrapolated to the temperature range of the coralline sponges these results and the mode of skeleton formation of ceratoporella nicholsoni suggest that these sponges precipitate aragonite close to isotopic equilibrium the temperature dependence of oxygen isotopic fractionation between the aragonite of ceratoporella nicholsoni and water is only roughly constrained by the available data due to the narrow temperature range of the caribbean reef sites however as the data suggest oxygen isotopic equilibrium we can calculate a well constrained temperature equation combining temperate and cold water equilibrium values from molluscs and foraminifera with our sponge data full size image 1 k and full size image 1 k

improving coral base paleoclimate reconstructions by replicating 350years of coral sr ca variations abstract coral based climate reconstructions are typically based on a single record and this lack of replication leads to questions in regards to chronology accuracy and reliability of the inclusive geochemical variations to record climate viability here we present two multi century coral sr ca records recovered from a porites lutea colony offshore of amedee island new caledonia 22 28 8 s 166 27 9 e the chronology was developed by cross dating the coral sr ca time series and verifying the chronology with high precision absolute 230th dating we identify chronological discrepancies of 2 3 and 3 7 years century 1 for reconstructions based on a single core with uncertainty increasing after 250 years we assess the impact of porites skeletal architecture on coral geochemistry by characterizing centimeter scale architectural structures with respect to sampling optimal sampling paths are those on the slab surface parallel to the growth direction of individual corallites along the central axis of an actively extending corallite fan coral sr ca time series extracted from optimal skeletal structures are highly reproducible with a mean absolute difference of 0 021 mmol mol 1 or 0 39 c for monthly determinations suboptimal skeletal architecture is characterized by corallites extending through the slab surface and the coral sr ca determinations derived from suboptimal paths tend to produce a warm bias that varies between 0 04 and 2 30 c disorganized skeletal architecture is characterized by small terminating or unclear corallite fans that produce a cold bias of 0 11 to 2 45 c in coral sr ca determinations these problematic architecture types also produce biases in coral 18o determinations but to a lesser extent we assess the impact of sampling a coral colony along paths that vary from vertical to horizontal in large and small porites colonies with extension rates 6 mm year 1 and we determine there is no significant difference in the coral sr ca records

evaluation of sampling resolution in coral stable isotope records a case study using records from new caledonia and tarawa we have generated a 40 year long monthly stable isotope record from a porites lutea coral collected offshore of amedee new caledonia 22 s 167 e to investigate the relation between sampling resolution in coral isotope studies and retrieval of sea surface environmental information we interpret the high correlation between our oxygen isotope record and a twenty year long sea surface temperature record at the monthly timescale r 0 88 to indicate that our coral isotope record is an accurate monitor of environmental conditions offshore of amedee the character of the signal and the percent variance explained in the record at the annual band at the quasi biennial oscillation band qbo 2 0 2 4 years and at the el nino southern oscillation band enso 3 8 years changes little in response to a reduction in sampling density from monthly to bimonthly to quarterly similar results have been obtained in a reanalysis of a coral isotope record from tarawa kiribati our results indicate that a significant amount of the information obtained from high density sampling can also be retrieved from lower density sampling in particular bimonthly sampling yields virtually no drop off in variance explained and quarterly sampling is satisfactory for resolving interannual and decadal scale trends in time series the proposed sampling approach may enable a more rapid filling in of numerous spatial holes in coral sampling sites needed for reconstruction of long term decadal scale variations in climate

refining the sampling approach for the massive coral diploastrea heliopora for δ 18 o based paleoclimate applications abstract studies on the indo pacific coral diploastrea have demonstrated that this genera can potentially be used to generate multi century length climate reconstructions however some concerns remain regarding sampling protocols this study further explores the utility of diploastrea heliopora for paleoclimatic reconstructions by examining 18 o along short coral cores of d heliopora and porites lutea from kandavu fiji these results indicate that sampling of the columellar part of the corallite in d heliopora is optimal to capture the full annual 18 o cycle and that bi monthly 0 5 mm sampling resolution is the optimal temporal resolution for the kandavu d heliopora results from kandavu d heliopora show high intra core reproducibility as well as a significant correlation to a 18 o record from a nearby porites colony monthly resolution r 0 71 n 186 df 54 p 0 01 annual resolution r 0 59 n 16 df 16 p 0 01 at our fiji study site d heliopora and porites skeletal 18 o have similar sensitivities to sea surface temperature and sea surface salinity validating the approach of using both coral species to create robust climate reconstructions these results indicate that microanalyses of the columellar portion of d heliopora skeleton produce time series 18 o results similar in quality to that extracted from porites

the apparently isotropic australian upper mantle 1 we investigate shear wave splitting measurements performed on two years of data recorded at stations deployed in the tasmal experiment a network of 20 broadband seismological stations designed to record data on each side of the controversial tasman line in australia whereas a subset of measurements previously performed on one year of data exhibited a curvilinear pattern similar to that of the tasman line suggesting anisotropy frozen in the lithosphere considering the whole data set drastically changes the situation apparent isotropy in the australian upper mantle is observed at numerous stations this apparent isotropy together with the ew or ns orientations of the polarization plane of the fast s wave f observed at some stations is consistent with a two layer anisotropic system underneath the australian continent with a perpendicular orientation of f in each layer from the latest tomographic results the transition between the precambrian western and phanerozoic eastern australia appears to define blocks of various thickness unlike the situation across the tesz in europe these blocks do not seem to be correlated with a different behavior in terms of seismic anisotropy citation heintz m and b l n kennett 2006 the apparently isotropic australian upper mantle geophys res lett 33 l15319 doi 10 1029 2006gl026401

high resolution palaeoclimatology of the last millennium a review of current status and future prospects this review of late holocene palaeoclimatology represents the results from a pages clivar intersection panel meeting that took place in june 2006 the review is in three parts the principal high resolution proxy disciplines trees corals ice cores and documentary evidence emphasizing current issues in their use for climate reconstruction the various approaches that have been adopted to combine multiple climate proxy records to provide estimates of past annual to decadal timescale northern hemisphere surface temperatures and other climate variables such as large scale circulation indices and the forcing histories used in climate model simulations of the past millennium we discuss the need to develop a framework through which current and new approaches to interpreting these proxy data may be rigorously assessed using pseudo proxies derived from climate model runs where the answer is known the article concludes with a list of recommendations first more raw proxy data are required from the diverse disciplines and from more locations as well as replication for all proxy sources of the basic raw measurements to improve absolute dating and to better distinguish the proxy climate signal from noise second more effort is required to improve the understanding of what individual proxies respond to supported by more site measurements and process studies these activities should also be mindful of the correlation structure of instrumental data indicating which adjacent proxy records ought to be in agreement and which not third large scale climate reconstructions should be attempted using a wide variety of techniques emphasizing those for which quantified errors can be estimated at specified timescales fourth a greater use of climate model simulations is needed to guide the choice of reconstruction techniques the pseudo proxy concept and possibly help determine where given limited resources future sampling should be concentrated

a multicentury stable isotope record from a new caledonia coral interannual and decadal sea surface temperature variability in the southwest pacific since 1657 a d a 335 year stable isotope record from a new caledonia coral 22 s 166 e helps fill a large gap in historical climate reconstructions although the long term coral 18o based sea surface temperature sst trend is one of warming there are notable decadal fluctuations especially in the early 18th and early 19th centuries mean annual ssts between 1658 and 1900 are estimated to be 0 3 c lower than the 20th century average with interdecadal excursions of 0 5 0 8 c time series analyses of the coral isotope record reveals significant concentrations of variance in the el nino band an inderdecadal spectral peak is present but its robustness requires additional statistical evaluation a secular but irregular decrease in coral 13c values begins in the mid 1800s and may reflect the anthropogenic perturbation of the carbon reservoir these and other results indicate that the new caledonia coral isotope record is a valuable source of information on southwest pacific climate history

sea surface temperature and salinity reconstruction from coral geochemical tracers massive scleractinian corals secrete an aragonitic skeleton which incorporates a large array of chemical tracers corals present several advantages for palaeoclimate research they grow continuously and can live up to 1000 years they are easy to date and they can be sampled at high resolution weekly to monthly resolution both live and fossil corals can be collected in the field in the past two decades significant efforts have been made to identify robust tracers of sea surface temperature sst and salinity sss in corals to date sr ca and 18o are considered to be the most reliable sst tracers although changes in seawater 18o can significantly alter sst reconstructed from coralline 18o because these variations in seawater 18o can be linked to sss changes this initial problem can in fact be turned into an advantage and provide us with an sss tracer the sst component in the coral 18o signal can either be evaluated through sr ca measurements or in some case simply filtered out however there is still much uncertainty concerning the exact mode of incorporation of trace elements and stable isotopes into the coral skeleton the effects of growth rate light intensity feeding habits ph and water chemistry are still poorly documented a review of the strength and weaknesses of sr ca and 18o is presented together with some examples of sst and sss reconstructions other potential sst tracers are also reviewed it is expected that the ability to grow corals in aquarium under controlled conditions and that the development of sophisticated analytical techniques at the micrometric level should help us understand better the robustness of each tracers and the factors controlling their incorporation in coral aragonite

sst spatial anisotropic covariances from metop avhrr data the advanced very high resolution radiometer avhrr instrument on board the metop satellite is designed to provide very accurate measurements of sea surface temperature sst in this work using one year of metop avhrr data and a geostatistical approach we characterize the spatial anisotropy and non stationarity of the sst variability using oriented ellipsoids the method is also able to separate the true sst variability from the artificial error introduced by the metop avhrr sensor these spatial parameters are then used for producing variability atlases available on line over the whole ocean

calibration of stable isotopic data an enriched δ18o standard used for source gas mixing detection and correction we present empirically based calibrations of our measurements made on a finnigan mat252 equipped with a kiel device to vienna pee dee belemnite using an enriched 18o standard calibrations include corrections for biases caused by the differences in isotopic composition of carbonate standards measured on the two parallel extraction lines of the kiel device and for decreases in the isotopic difference between the reference and sample gas caused by mixing in the source after correcting for these biases the precision of 2200 nbs19 analyses 10 300 g is 0 07 for 18o and 0 03 for 13c we have shared our standard enriched in 18o with 18 laboratories engaged in paleoceanographic research producing the first large scale interlaboratory calibrations for this community using correction procedures reported here water mass reconstructions using data produced on multiple mass spectrometers may now be possible with a precision approaching the level necessary to reconstruct temperature salinity and density variability in the deep ocean

enhanced multidecadal climate variability in the seventeenth century from coral isotope records in the western indian ocean 1 the slowly growing coral diploastreaheliopora affords a novel opportunity to obtain multicentury records of paleoclimate including details of the interannual rhythms associated with the el nino southern oscillation enso system we examine climate variability in an enso teleconnected region using new oxygen isotope records from d heliopora spanning most of the twentieth 1896 1998 and seventeenth 1622 1722 centuries from the mafia archipelago tanzania the modern record demonstrates coherency with relevant instrumental and proxy time series documents twentieth century warming and displays significant power at enso periodicities the seventeenth century record lacks any trend exhibits interannual variance comparable to the modern record and displays a pronounced interdecadal signal not evident in the twentieth century that correlates with other tropical and hemispheric climate records we find no clear evidence of solar irradiance influence on interannual variability in the western indian ocean during these intervals although the mean sea surface temperature appears to vary inversely with insolation

deep sea coral geochemistry implication for the vital effect abstract deep sea corals hold a great potential as a key to important aspects of paleoceanography for at least two reasons 1 they offer temporal high resolution records of deep sea environment because they have growth banding structures 2 and they are well suited for studying vital effects because the deep sea environment does not change over short time scales however the relationship between the chemical composition of deep sea coral skeletons and environmental factors is not well understood in this study the chemical composition of deep sea corals was measured in bulk individuals and along skeletal micro structures among the bulk individuals 18 o value and sr ca ratio show a negative but weak correlation with ambient temperature on the other hand the mg ca ratio has a positive weak correlation with the temperature large variations were found among samples collected from similar temperature the variation is up to 3 8 for 18 o 0 9 mmol mol for sr ca ratios and 0 78 mmol mol for mg ca ratios among samples with ambient average temperature within 1 c this variation may be due to a large vital effect the centers of calcification cocs which were formed at high calcification rate have lower sr ca u ca and higher mg ca ratios than surrounding fasciculi this chemical distribution supports the model that elemental incorporation depends on calcification rate this suggests that calcification rate is a very important factor for the chemical composition in deep sea corals and is one of the most significant mechanisms of the vital effect because of this large vital effect further investigations are essential to use the deep sea coral as a temperature proxy

large variations of surface ocean radiocarbon evidence of circulation changes in the southwestern pacific radiocarbon 14c and stable isotope 18o and 13c records are presented for biannual samples from a 323 year banded coral series collected from the southern great barrier reef australia the high precision 14c record contains variations on an interannual timescale that are particularly large between a d 1680 and 1730 by comparison with tree ring 14c records stuiver and quay 1980 m stuiver personal communication 1992 it is clear that these shifts were not caused by changes in the 14c of atmospheric co2 changes in vertical mixing and large scale advective changes involving source waters to the western coral sea region are likely processes that could account for these large 14c variations most low 14c values for the period a d 1635 1875 coincide with el nino southern oscillation enso events as reported by quinn et al 1987 for the eastern tropical pacific however enso does not explain all of the variations especially during 1875 1920 when 14c values remained high cross spectral analysis of the early half of the 14c and 18o records a d 1635 1795 reveals that the 6 year period is coherent this coherency is not present in the latter half a d 1797 1957 of the isotope records these data support the concept of century timescale changes in the nature of enso as it is manifest in the southwestern pacific our coral record shows no evidence of a suess effect the lowering of 14c from late 1800s through 1955 due mainly to co2 input from fossil fuel burning this is coincident with the change we observe in the nature of enso and is further evidence that a long term change in mixing of upper waters occurred in this region

seasonal changes in sea surface temperature and salinity during the little ice age in the caribbean sea deduced from mg ca and 18o 16o ratios in corals abstract the oxygen isotopic composition 18 o of coral skeletons reflects a combination of sea surface temperature sst and the 18 o of seawater which is related to sea surface salinity sss in contrast the magnesium calcium mg ca ratio of a coral skeleton reflects sst independent of salinity by using the relationships among coral mg ca ratios coral 18 o seawater 18 o and sst it is possible to determine past sst and sss uniquely such determinations were made and calibrated using the mg ca ratio and the 18 o of the modern part of a 3 m long coral core montastrea faveolata collected from the southwest coast of puerto rico in the caribbean sea where both sst and sss changes seasonally and the seawater 18 o measured at the coral site our results yielded three relationships coral mg ca sst 18 o coral 18 o water sst and 18 o water sss with these calibration equations seasonal changes in sst and sss during the little ice age lia in the caribbean sea were reconstructed the 18 o and mg ca ratio of the coral skeleton between 1699 and 1703 suggests that the sst during the lia was approximately 2 c cooler than present with the sss showing greater seasonal changes as well these results are in good agreement with climate based reconstruction from corals based on oxygen isotopes although the possibility of some uncertainty remain in our estimation including long term decadal scale trends in climate

the holocene alluvial plain of the middle amazon river brazil abstract the fluvial belt of the amazon river is a complex of quaternary sedimentary units of different ages and formation conditions present position of the channel and the morphology and size of the alluvial plain are related to neo tectonic lineaments in the study area the main channel of the solimoes is nearly straight the river may be considered anastomosed albeit with few islands and anabranches the main holocene units are the impeded floodplain and the channel dominated floodplain the channel dominated floodplain is a complex mosaic of fluvial forms including younger channels active sandbars islands levees scroll dominated plains and abandoned belts the impeded floodplain is a widespread unit characterised by a very flat surface and round or irregularly shaped lakes the impeded drainage flood plain is only partially affected by the present floods and even those parts affected by floods receive little or no sediment from the main channel more important sediment contribution is by alluvial plain channels from the solimoes branches that generate deltas in the impeded floodplain lakes the impeded floodplain is interpreted to be an earlier stage in the evolution of the holocene alluvial belt the formation was marked by widespread vertical accretion and a channel morphogenetically less active than at present the later stage is associated with an active main channel and the paranas and generation of a scroll dominated plain this very large river system had a complex and delayed response to variations in the hydrological conditions induced by changes in the regional climate during the late holocene

crustal and upper mantle structure in the amazon region brazil determined with broadband mobile stations 1 three broadband stations operated from march 1997 to september 1998 in the amazon region north of manaus brazil which including the iris station ptga pitinga covered an area of roughly 60 200 km applying the receiver function technique to determine the crustal structure there is evidence for an increase of the moho depth from about 38 km below the amazon basin to approximately 48 km north of the basin in addition we analyzed the polarization of sks waves to determine anisotropy the observed splitting parameters in a majority of the data set can be accounted for by a layer of axial symmetric anisotropy with the fast direction oriented roughly n110e this direction cannot be associated with the present day plate motion of the south american plate however the anisotropy may be related to a lithospheric fabric that was generated during the early tectonic history of the amazonian craton

source mechanisms of moderate size earthquakes and stress orientation in mid plate south america summary fault plane solutions of six mid plate earthquakes with magnitudes ranging from 4 8 to 5 5 mb were determined using p wave first motion data and the relative amplitudes of short period teleseismic depth phases pp and sp these results together with previous studies show a predominance of reverse and strike slip faulting indicating horizontal compressional stresses in mid plate south america the orientation of the p axes however is not uniform in western and southwestern brazil the p axes are oriented approximately e w probably due to the nazca south america plate convergence in eastern brazil the direction of the p axes show more scatter but an average e w direction is consistent with the available data on the contrary in northern brazil the p axes of two events in the amazon basin trend approximately n s a direction perpendicular to the direction of absolute plate motion as well as to the relative plate motions nazca south america and south america africa

carbon isotope records from extant caribbean and south pacific sponges evolution of δ13c in surface water dic stable isotope records of demosponges from the caribbean and coral sea are described for the purpose of studying the influence of fossil fuel co2 on the carbon isotopic composition of dissolved inorganic carbon dic in surface water the slow growing sponges precipitate calcium carbonate in isotopic equilibrium with ambient sea water and are used to detect changes in 13cdic from pre industrial times early 19th century to the present we observed similar shapes and ranges in 13c curves measured on caribbean specimens collected from water depths of 25 84 and 91 m as well as a specimen collected in shallow waters off new caledonia the records reveal a highly significant correlation with atmospheric 13cco2 13cdic values for caribbean and coral sea surface waters were calculated using the 13c sponge records while 13c of atmospheric co2 decreased by about 1 4 from the early 19th century to 1990 13cdic of caribbean and coral sea surface waters decreased by 0 9 0 2 and 0 7 0 3 respectively no isotopic equilibrium between surface water dic and atmospheric co2 was observed either during the pre industrial steady state or during the last 100 years the lower amount of depletion in the surface water 13cdic with respect to the atmospheric anthropogenic signal is explained by the dilution of the surface waters by biologically altered subsurface water dic the lower 13c decrease in the coral sea points to a stronger influence of the subsurface water source compared to the caribbean

coral oxygen isotope records of interdecadal climate variations in the south pacific convergence zone region 1 the south pacific convergence zone spcz a region of high rainfall is a major feature of subtropical southern hemisphere climate and contributes to and interacts with circulation features across the pacific yet its past temporal variability and forcing remain only partially understood here we compare coral oxygen isotopic 18o series spanning a d 1997 1780 and a d 2001 1776 from two genera of hermatypic corals in fiji located within the spcz to examine the fidelity of these corals in recording climate change and spcz interdecadal dynamics one of these coral records is a new 225 year subannually resolved 18o series from the massive coral diploastreaheliopora diploastrea s use in climate reconstructions is still relatively new but this coral has shown encouragingly similar interannual variability to porites the coral genus most commonly used in pacific paleoclimate studies in fiji we observe that interdecadal 18o variance is also similar in these two coral genera and diploastrea contains a larger amplitude interdecadal signal that more closely tracks instrumental based indices of pacific interdecadal climate change and the spcz than porites both coral 18o series record greater interdecadal variability from 1880 to 1950 which is consistent with the observations of folland et al 2002 who reported higher variability in spcz position before 1945 these observations indicate that diploastrea will likely provide a significant new source of long term climate information from the spcz region

caribbean sea surface temperatures two to three degrees cooler than present during the little ice age we determined the seasonal environmental conditions during the little ice age lia by interpreting isotope proxies in the coral skeleton of montastrea faveolata from the northeast caribbean the oxygen isotope composition was determined for three time intervals during the lia 1700 1705 1780 1785 1810 1815 thought to correspond to the coldest intervals the period 1984 1989 was used to represent modern calibration conditions we determined that ssts from the lia intervals are nearly 2 3 c cooler than present lia cooling in the caribbean may have resulted from regional oceanic and atmospheric circulation differences especially in winter we propose that a trough of cold air from the north atlantic may have extended farther south than present into the northern caribbean although there are indications from pacific corals that seasonality was greater during the lia this does not seem to be the case for the caribbean

calibration of stable oxygen isotope signatures in galapagos corals a 2 year 1993 1994 study was conducted in the galapagos islands ecuador to determine the relationship between 18o in skeletal carbonate and sea surface temperature sst in three species of reef building corals pavona clavus pavona gigantea and porites lobata coral samples were grown at 3 10 and 3 m depth at bartolome island champion iisland and urvina bay isabela island respectively hourly measurements of sst and sea surface salinity sss were taken at each site immediately adjacent to colonies which were stained biannually to establish the chronology of growth in addition surface waters were sampled periodically bimonthly to monthly at each site to determine variation in 18o seawater results indicate the mean annual ssts were similar between sites varying from 22 9 c at champion to 23 8 c at urvina bay comparisons of monthly sst averages between instrumental and remote sensing satellite 1 1 grid data show a high correspondence r2 ranging from 0 84 to 0 94 indicating that remote sensing data are useful for interpreting the 18o record in corals when instrumental data are lacking here 18ocoral analyses of eight specimens show that coralline aragonite is a reliable indicator of sst in galapagos in general higher resolution coral sampling year resolved more of the monthly variation in sst up to 97 at a sampling resolution of 1 4 samples per millimeter of linear skeletal growth comparisions of the 18ocoral signal among and between species at the same site showed consistent seasonal patterns of variation closely tracking sst in addition comparisons between sites were highly concordant with some differences reflecting local variation in sst seasonal patterns however were essentially the same over the entire region thus we conclude that the 18ocoral signal from coral skeletons in galapagos can be used to interpret regional changes in sst variation

the late quaternary evolution of the negro river amazon brazil implications for island and floodplain formation in large anabranching tropical systems abstract the rio negro has responded significantly in the late pleistocene and holocene to lagged environmental changes largely associated with activity during the last glacial in the amazon basin on the basis of geological structure the rio negro can be divided into six distinct reaches that each reflects very marked differential processes and geomorphological styles no deposits of the upper pleniglacial were recognized in the field the oldest recognizable late pleistocene alluvial unit is the upper terrace of middle pleniglacial age ca 65 25 ka reach i tentatively correlated with the oldest terrace identified on the left bank of reach iii at that time the river was mainly an aggradational bed load system carrying abundant quartz sand a product of more seasonal conditions in the upper catchment the late glacial 14 10 ka is represented by a lower finer grained terrace along the upper basin reach i which was recognized in the tiquie curicuriari and vaupes rivers at that time the river carried abundant suspended load as a response to climatic changes associated with deglaciation since about 14 ka the river has behaved as a progradational system infilling in downstream series a sequence of structurally controlled sedimentary basins or compartments creating alluvial floodplains and associated anabranching channel systems reach ii was the first to be filled then reach iii both accumulating mainly sand fine deposits increase downstream in reach iii and become predominant in some anabranch islands of the distal reach the lowermost reaches of the negro v and vi have been greatly affected by a rising base level and associated backwater effect from aggradation of the amazon during late glacial and recent times reach v has acted almost entirely as a fine sediment trap the remarkable anavilhanas archipelago is the product of holocene deposition in the upper part of this sedimentary basin however suspended sediment load declined about 1 5 ka prior to the lower part of this basin becoming infilled the progradational behavior of the rio negro filling tectonic basins as successive sediment traps with sand in the upper basins and fines in the downstream ones illustrates how a large river system responses to profound changes in late quaternary base level and sediment supply the most stable equilibrium conditions have been achieved in the holocene in reaches iib and iiia where an anabranching channel and erosional relictual island system relatively efficiently convey water and sediment downstream reaches iiib and v never achieved equilibrium conditions during the holocene characterised as they are today with incomplete floodplains and open water

evidence for stronger el nino southern oscillation enso events in a mid holocene massive coral we present a 47 year long record of sea surface temperature sst derived from sr ca and u ca analysis of a massive porites coral which grew at 4150 calendar years before present b p in vanuatu southwest tropical pacific ocean mean sst is similar in both the modern instrumental record and paleorecord and both exhibit el nino southern oscillation enso frequency sst oscillations however several strong decadal frequency cooling events and a marked modulation of the seasonal sst cycle with power at both enso and decadal frequencies are observed in the paleorecord which are unprecedented in the modern record

modern sedimentation in the lower negro river amazonas state brazil abstract the negro river which flows through the north central amazon basin is one of the largest tributaries of the amazon the name negro comes from the colour of its water which reflects the large quantity of dissolved humic acids and iron oxides that also gives the water its characteristic acid ph the river is estimated to have the fifth largest water discharge in the world about 30 000 m3 s the negro river is characterized by a high dissolved load but a low energy system neotectonics and water quality are the principal factors that control the modern sedimentation in the lower negro river the lower negro river is controlled largely by a nw se tectonic lineament that is a segment of a major tectonic transcurrent dextral megasystem of the amazon basin neotectonism in this area is responsible for the depth of the river and for the occurrence of steep falesias cliffs along some parts of its borders it also seems that neotectonics have influenced the origin of the anavilhanas islands which are a series of anastomosed elongated silty clayey channel bars with internal round or long narrow lakes the igapo which is the forested area flooded during part of the year appears to have a neotectonic origin as well igapos are located on intermediate blocks between the high blocks of the terra firme and the low blocks of the channel the absence of clastic sediments carried in suspension is related to the rare appearance of floodplains which are limited to very thin layers of fine sediments located on the abrasion shelfs carved in clastic deposits of the alter do chao formation sand bars occur in places along the base of the cliffs and along the edges of the channel system these sand bars are composed of quartz sand derived from the reworking of the sand of the alter do chao formation

a skeletal sr ca record preserved in dipsastraea favia speciosa and implications for coral sr ca thermometry in mid latitude regions 1 a core 900 mm long of the scleractinian coral dipsastraea favia speciosa was collected from iki island 33 48 n japan one of the highest latitude coral reefs known to exist at present where winter monthly mean sea surface temperature sst drops to 13 c the sr ca profile was constructed using a bulk sampling method for the uppermost 280 mm interval of the core which grew between 1966 and 2007 to test whether it could act as a suitable proxy for sst in a harsh environmental setting where reef building coral do not usually survive the sr ca sst relationship derived from the annual sr ca and sst extremes predicted the observed monthly averaged summer sst extremes within an error range of 1 1 c 1 s d n 40 the obtained sr ca sst calibration was also found to be valid for subtropical dipsastraea favia corals proving its broad applicability however low amplitude winter peaks were observed in the slow growing intervals which we confirmed using individual spot analysis along a continuous growth line result from the mixing of theca grown at different times our bulk sampling approach across multiple growth lines in the skeleton of d f speciosa led to the mixing of asynchronous skeletal part at the study site d f speciosa grows continuously even during the cold season suggesting that the skeletal sr ca obtained from specimens of d f speciosa can be used as an sst proxy in the northwest pacific marginal seas

reconstruction of the east china sea palaeoenvironment at 16 ka by comparison of fossil and modern faviidae corals from the ryukyus southwestern japan we conducted paired measurements of the sr ca ratio and oxygen and carbon stable isotopes of a fossil faviidae coral specimen myk90 age 16 ka collected from near miyako island the ryukyus southwestern japan our study aimed to reconstruct the palaeoenvironment in the east china sea at 16 ka by comparing the fossil sample with modern faviidae corals our data with annual or longer time resolution may be very suitable for palaeoceanographic reconstruction although no general calibration method for faviidae corals has been reported our calibration showed that the annual mean sea surface temperature was approximately 5 c lower and sea surface salinity sss at the study site was locally higher at 16 ka than at present even though the mouths of the yellow and changjiang rivers were east of their present locations because sea level was much lower our results suggest that the influence of the terrestrial water discharge may not have extended to miyako island weak summer monsoon activity during the last glacial which decreased summer precipitation over the asian continent and an enhanced winter monsoon which may have led to more evaporation likely contributed to the inferred high sss at the study site copyright 2009 john wiley sons ltd

interdecadal variation in the extent of south pacific tropical waters during the younger dryas event during the younger dryas event about 12 000 years ago the northern hemisphere cooled by between 2 and 10 degrees c refs 1 2 whereas east antarctica experienced warming but the spatial signature of the event in the southern mid latitudes and tropics is less well known as records are sparse and inconclusive here we present high resolution analyses of skeletal sr ca and 18o 16o ratios for a giant fossil diploastrea heliopora coral that was preserved in growth position on the raised reef terraces of espiritu santo island vanuatu in the southwestern tropical pacific ocean our data indicate that sea surface temperatures in vanuatu were on average 4 5 1 3 degrees c cooler during the younger dryas event than today with a significant interdecadal modulation the amplified annual cycle of sea surface temperatures relative to today indicates that cooling was caused by the compression of tropical waters towards the equator the positive correlation in our record between the oxygen isotope ratios of sea water and sea surface temperatures suggests that the south pacific convergence zone which brings 18o depleted precipitation to the area today was not active during the younger dryas period

climatic fluctuations and seasonality during the kimmeridgian late jurassic stable isotope and clay mineralogical data from the lower saxony basin northern germany abstract in previous palaeoclimatic models the kimmeridgian stage has been defined as a typical greenhouse time interval with weak latitudinal gradients however palaeoclimatic information based on biogenic low mg calcite 18o for the kimmeridgian is still limited here shell materials n 81 precipitated by brachiopods oysters and trichites bivalves from the lower saxony basin northern germany are evaluated for their potential to act as archive for marine sea surface temperatures furthermore the associated clay mineral assemblages based on bulk materials are used to infer hinterland weathering patterns and overall climatic conditions simultaneously the established sea surface temperature curve reveals an overall slightly warming trend through the kimmeridgian weak seasonality 4 c in sea surface temperatures is documented by oxygen isotope variations measured along the growth lines of a large trichites shell distinctly higher 18o values observed in the lower kimmeridgian late baylei chron are interpreted to be related to the short term influx of cooler boreal water masses judging from the corresponding smectite dominated interval however the positive oxygen isotope anomaly may also be partly explained by a relatively drier climate causing enhanced 18oseawater values due to intensified evaporation the kaolinite illite chlorite ratio points to a slightly long term decrease in humidity through the kimmeridgian on the landmasses surrounding the lsb the short term fluctuations in humid arid conditions correlate significantly with sea level changes with humid climates accompanying high sea levels and arid climates accompanying low sea levels results from this study provide new insights into late jurassic climatic dynamics and help to establish a reliable subboreal late jurassic sea surface temperature curve

the effect of colony topography on climate signals in coral skeleton the stable oxygen isotope composition of the aragonitic skeleton of hermatypic corals is a potential archive of paleotemperature and rainfall data biological processes also influence coral 18o although it has been difficult to determine which processes are involved and whether or not they dominate the stable isotope signal we show here that colony topography or surface bumpiness is associated with significant differences in 18o 13c and the timing of high density band formation between same age corallites in the central and fastest growing region of a coral colony these differences reflect changes experienced by individual corallites as they grow from the summit of a bump toward the bottom of a valley corallites on the bump record isotopic temperatures more than 1 c higher and accrete high density skeleton about 2 months earlier than their valley counterparts just 20 mm away we propose that these changes are not caused by corallite aging but rather by changes in the overall rate and timing of light enhanced calcification which is lower and occurs later in shaded valleys than it does on exposed bumps although we conclude that sea temperature is the dominant influence on 18o values in our coral our results show that significant isotopic variations may be expected over a small surface area in a single colony the production of accurate and reproducible coral based climate records thus requires an understanding of the complexities of coral growth processes and incorporation of this knowledge into sampling strategies and interpretation of data