good neighbours shaped by vigorous currents cold water coral mounds and contourites in the north atlantic abstract over the recent years two research fields addressing continental slope sedimentary systems have gained significant momentum contourites and cold water coral mounds being both related to intense bottom currents and being both dependent on sediment supply they share some commonalities resulting in their widespread co occurrence however as cold water coral mounds predominantly occur in shallow to intermediate water depths this co occurrence is restricted to these depth levels for both systems the available knowledge is derived basically from north atlantic ocean settings indicating the potential to discover such systems hidden in the other ocean basins as well as still hidden in the atlantic contourites and cold water coral mounds have the capability of providing high resolution palaeo environmental records although with often differing temporal ranges and or temporal resolutions applying the concept of a joint exploitation of sedimentary records obtained from mounds and contourites offers the unique possibility of analysing contourite and mound development as well as the related palaeo environmental settings much more comprehensively than done when only considering one of these archives thus after two decades of intense research providing significant knowledge about contourites and cold water coral mounds from the north atlantic new ideas and concepts may arise from a close collaboration of scientists working in these two fields

effect of calcite precipitation on stable strontium isotopic compositions insights from riverine and pool waters in a karst cave abstract radiogenic and stable sr isotope ratios 87 sr 86 sr 88 86 sr serve as potential tracers for evaluation of weathering sources and associated physicochemical processes in terrestrial environments despite carbonate weathering sourcing two thirds of the total continental sr flux to the ocean however few attempts have been aimed at studying stable sr isotope fractionation in carbonate dominated aquifers here we present a monthly resolved monitoring dataset of major ion concentrations and sr isotope ratios for karst riverine and pool waters at the luofang cave in the central china to understand the potential controls responsible for water 88 86 sr compositions under various climatic conditions with the exception of some pool waters in the dry period significantly heavier 88 86 sr were detected in the riverine and pool waters 0 20 to 0 42 compared to bedrock 88 86 sr 0 24 to 0 28 which can t be interpreted solely by lithology a sequential leaching experiment of the local soils suggests limited stable sr isotope fractionation during incongruent silicate mineral dissolution local plant utilization and biological activity in the soil overlying the cave are possible processes for causing the observed heavier 88 86 sr in cave water however air partial pressure of co 2 in cave monitoring water ph and sr isotopic mass balance calculations suggest that plant utilization is unlikely to be the primary control on the heavier water 88 86 sr on the other hand significant stable sr isotope fractionation was found between the cave dripping waters and calcite precipitates and the 88 86 sr car aq was estimated to be 0 15 0 07 2sd precipitation of secondary calcites might be a potential process responsible for the heavier 88 86 sr in the waters the negative correlation between 88 86 sr and sr na ratios in the cave waters is consistent with a scenario of preferential incorporation of the light sr isotope by solid phase furthermore by combining the calcite saturation states and water ph our results suggest that calcite precipitation is the most likely process controlling 88 86 sr compositions in cave water we demonstrate that secondary calcite precipitation in carbonate dominated catchments could be important in controlling the riverine water 88 86 sr compositions

reefs of the deep the biology and geology of cold water coral ecosystems coral reefs are generally associated with shallow tropical seas however recent deep ocean exploration using advanced acoustics and submersibles has revealed unexpectedly widespread and diverse coral ecosystems in deep waters on continental shelves slopes seamounts and ridge systems around the world advances reviewed here include the use of corals as paleoclimatic archives and their biogeological functioning biodiversity and biogeography threats to these fragile long lived and rich ecosystems are mounting the impacts of deep water trawling are already widespread and effects of ocean acidification are potentially devastating

boron isotope composition of the cold water coral lophelia pertusa along the norwegian margin zooming into a potential ph proxy by combining bulk and high resolution approaches abstract high latitude cold water coral reefs are particularly vulnerable to climate change due to enhanced co2 uptake in these regions to evaluate their physiological functioning and potential application as ph archives we retrieved both recent and fossil samples of lophelia pertusa along the norwegian margin from oslofjord 59 n over to trondheimsfjord sula and lopphavet 70 6 n boron isotope analyses 11b were undertaken using solution based and laser ablation multi collector inductively coupled plasma mass spectrometry mc icp ms la icp ms and secondary ion mass spectrometry sims epi fluorescence microscopy was employed to provide a rapid pre screening routine for structure specific subsampling in the coral skeleton this integrated approach enabled us to assess heterogeneities within single specimens as well as to investigate the role of local environmental influences including recent and past variations all three mass spectrometry methods show substantial differences in the 11b of the theca wall tw and the centres of calcification coc s micro bulk subsamples milled from the theca wall of modern specimens originating from different habitats but with comparable seawater ph 8 8 16 gave consistent 11b values averaging 26 7 0 2 2 n 4 while coc subsamples systematically deviated towards lower b ca by 40 and depleted 11b values minimum 22 7 0 3 2 implying a difference of at least 4 between tw and coc sims and la icp ms measurements identified much larger internal heterogeneities with maximum variation of 10 between the distinct skeletal structures minimal sims 11b values of 17 3 1 2 2 were associated with the pure coc material our findings may be interpreted in terms of the occurrence of two main but likely different biomineralisation mechanisms in l pertusa with the coc s generally exhibiting minimal ph up regulation potentially supporting the use of bicarbonate in the early stages of biomineralisation furthermore we highlight the potential utility of l pertusa for palaeo proxy studies if targeting the compositionally homogenous tw zones devoid of coc admixtures which appear to provide highly reproducible measurements

radiogenic and stable sr isotope ratios 87 sr 86 sr δ 88 86 sr as tracers of riverine cation sources and biogeochemical cycling in the milford sound region of fiordland new zealand this study reports radiogenic sr isotope ratios 87sr 86sr stable sr isotope ratios 88 86sr and major ion concentrations for river rock sediment soil and plant samples collected from the cleddau and hollyford catchments in the milford sound region of fiordland new zealand the catchments primarily drain gabbro but some tributaries access limestone and volcanogenic sediments the goal of the study was to understand controls on riverine 88 86sr values in a landscape with multiple factors that may influence chemical weathering including dense vegetation high rainfall and abundant freshly eroded holocene fluvio glacial and landslide debris rivers draining gabbro have higher 88 86sr values than bedrock by as much as 0 14 and the 88 86sr values strongly correlate with molar ca sr ratios r2 0 69 leaching of rocks and sediment reveals no evidence for the preferential dissolution of minerals having high 88 86sr values and ca sr ratios in stream sr isotope fractionation seems unlikely because comparison against 87sr 86sr and ca sr ratios demonstrates that riverine 88 86sr values conservatively trace water mass mixing the riverine data are best explained by the input of soil water which is distinct from potential bedrock end members i e silicates and carbonates based on 88 86sr but indistinguishable in terms of ca sr and 87sr 86sr while strontium isotope fractionation during secondary mineral formation and pedogenesis is possible clay mineral formation is minor and most soils are poorly developed instead soil water 88 86sr values more likely reflect plant uptake plant samples yielded a wide range of 88 86sr values but on average they are lower than those for bedrock consistent with the expectation that plants preferentially incorporate lighter sr isotopes mass balance constraints together with 87sr 86sr ratios indicate that soil water 88 86sr values are 0 30 higher than bedrock 88 86sr values and mixing calculations show that the plant fractionated soil water pool contributes 27 of the riverine sr for tributaries accessing limestone and volcanogenic sediments ca sr and 87sr 86sr ratios appear consistent with two component mixing between silicate and carbonate weathering but 88 86sr values reveal a third contribution from soil water inputs similar to gabbro catchments the results of this study suggest that sr isotopes behave conservatively during water mass mixing and stream transport but non conservatively in soil where plant uptake can elevate soil water 88 86sr values relative to bedrock plant uptake or related biogeochemical processes such as ion exchange on organic matter surfaces also appear to modify soil water ca sr ratios many studies use 87sr 86sr and ca sr ratios to apportion riverine solutes between silicate and carbonate weathering but ca sr ratios may be non conservative in densely vegetated areas the stable sr isotope tracer shows promise for resolving riverine cation sources as well as effects from biological cycling

giant carbonate mud mounds in the southern rockall trough seismic profiles sidescan sonar data bottom photography and sampling proved for the first time that there are giant carbonate mounds bioherms in the rockall trough the pelagia mounds on the northern porcupine bank are relatively isolated whereas most of the logachev mounds on the southeast rockall bank form a field of closely spaced contiguous mounds they are all found on the upper slope at depths between about 500 and 1200 m and as a result of this study about 500 have been mapped they have a variety of shapes and the larger ones are very steep sided up to 350 m high and 2 km wide at the base sediment samples show that the mounds consist of pale coloured muds mainly aragonite usually with live and or dead cold water corals at the seafloor and with buried dead corals coral thickets appear to be detected as a brush like signature on high resolution profiles and as a speckled pattern on high resolution sidescan sonar records shelly sands are found on the seabed between the mounds currents in the mound areas are strong enough to transport sands along slope as medium sized sand waves and to prevent pelagic deposition thus providing surfaces for initial coral settlement by the winnowing of fines to leave glacial dropstones and exposed rocks these observations show that the poleward directed upper slope current of the eastern north atlantic extends further south than hitherto known and that there is a southwesterly directed current on rockall bank there are waves on the logachev mounds with a wavelength of about 20 30 m that are thought to be moulded in carbonate muds by across slope directed internal tidal currents and or cascading currents mounds develop above erosional surfaces seen on seismic data the huge amount of carbonate mud seems to be produced by the rapid growth and breakdown of cold water corals living in a very favourable environment intermediate nepheloid layers formed upstream by the strong currents may provide the food source for the deep water suspension feeders conditions for giant mound growth require an ideal balance between current speed and sedimentation rate among other factors no evidence for the suggested link to methane seepage has been found so far

the influence of skeletal micro structures on potential proxy records in a bamboo coral assessing the physicochemical variability of the deeper ocean is currently hampered by limited instrumental time series and proxy records bamboo corals isididae form a cosmopolitan family of calcitic deep sea corals that could fill this information gap via geochemical information recorded in their skeletons here we evaluate the suitability of high resolution chemical imaging of bamboo coral skeletons for temperature and nutrient reconstruction the applied elemental mapping techniques allow to verify the suitability of the chosen transect on the sample section for paleo reconstructions and enhance the statistical precision of the reconstruction we measured mg ca via electron microprobe at 1 m resolution and ba ca via laser ablation icp ms at 35 m resolution in a historic specimen of keratoisis grayi from the blake plateau off eastern florida long term growth temperatures of 7 1 3 4 c 2 sd that are in agreement with recent ambient temperature range can be reconstructed from mg ca ratios provided that anomalously mg enriched structural features around the central axis and isolated features related to tissue attachment are avoided for reconstruction skeletal ba ca measurements reflect mean seawater barium ba sw concentrations ba sw 51 24 nmol kg 1 2 sd in agreement with instrumental data 47 nmol kg 1 we show for the first time that ba ca forms concentric structures in a bamboo coral skeleton section our investigations suggest that while bamboo coral skeletons do record environmental parameters in their mean chemical composition the magnitude of environmental variability reconstructed from high resolution chemical maps exceeds that expected from instrumental time series this necessitates additional investigation of the factors driving bamboo coral skeletal composition

decoupling of pacific subduction zone guided waves beneath central japan evidence for thin slab the fine scale seismic structure of the northeast japan subduction zone is studied based on waveform analyses of moderate sized m4 5 6 deep focus earthquakes h 350 km and the finite difference method fdm simulation of high frequency up to 8 hz wave propagation strong regional s wave attenuation anomalies for specific source receiver paths connecting the cluster of events occurring in central part of the sea of japan recorded at fore arc stations in northern and central japanese islands honshu are used to model the deeper structure of the subducting pacific plate where recent teleseismic tomography has shown evidence for a possible slab tear westward beneath the sea of japan the character of the observed anomalous s wave attenuation and the following high frequency coda can be captured with the two dimensional 2 d fdm simulation of seismic waves in heterogeneous plate model incorporating the thinning of the plate at depth which is also compared with other possible causes of dramatic attenuation of high frequency s wave due to low q or much weaker heterogeneities in the slab the results of simulation clearly demonstrate that the dramatic loss of high frequency s wavefield from the plate into the surrounding mantle occurred due to the variation in the plate geometry i e thinning of the plate at depth near the source rather than due to variation in physical properties such as due to the lowered q and weaker heterogeneities in the plate the presence of such a thin zone defocuses the high frequency slab guided s wave energy from the subducting plate into the surrounding mantle and acts as a geometric antiwaveguide based on the sequence of simulation results obtained we propose thinning of pacific plate at depth subducting beneath northeastern japan localized to central part of honshu in agreement with the observations

88sr 86sr fractionation in inorganic aragonite and in corals conflicting results have been reported for the stable sr isotope fractionation specifically with respect to the influence of temperature in an experimental study we have investigated the stable sr isotope systematics for inorganically precipitated and biogenic coral aragonite natural and laboratory cultured inorganic aragonite precipitation experiments were performed from natural seawater using the co2 diffusion technique the experiments were performed at different temperatures and different carbonate ion concentrations 88sr 86sr of the inorganic aragonite precipitated in the experiments are 0 2 lighter than seawater but showed no correlation to the water temperature or to co32 concentration similar observations are made in different coral species cladocora caespitosa porites sp and acropora sp with identical fractionation from the bulk solution and no correlation to temperature or co32 concentration the lack of 88sr 86sr variability in corals at different environmental parameters and the similarity to the 88sr 86sr fractionation in inorganic aragonite may indicate a similar sr incorporation mechanism in corals skeleton and inorganic aragonite and therefore the previously proposed rayleigh based multi element model gaetani et al 2011 cannot explain the process of sr incorporation in the coral skeletal material it is proposed that the relatively constant 88sr 86sr fractionation in aragonite can be used for paleo reconstruction of seawater 88sr 86sr composition the seawater 88sr 86sr ratio reconstruction can be further used in calcite samples to reconstruct paleo precipitation rates

stable strontium isotopes δ88 86sr in cold water corals a new proxy for reconstruction of intermediate ocean water temperatures abstract zooxanthellate scleractinian corals are known as archives for temporal variations of climate variables such as sea surface temperature salinity or productivity the use of azooxanthellate cold water corals as potential archives for intermediate water mass properties and climate variability was tested recently however the correlation of established proxies such as 18o and 13c with temperature is difficult since there is no direct temperature equation applicable as in shallow water corals other temperature proxies such as sr ca mg ca and u ca are influenced by the complex microstructure of the aragonite skeleton the rate of calcification and other vital effects observed for coral species for the first time we show that the stable strontium isotope ratio 88 86sr incorporated in the skeletons of the cold water coral species lophelia pertusa portrays the ambient seawater temperature the temperature sensitivity from live samples collected along the european continental margin covering a temperature range from 6 to 10 c is 0 026 0 003 c 2 standard error which is a sensitivity similar to the tropical shallow water coral record of pavona clavata this indicates a similar fractionation process of strontium for both zooxanthellate and azooxanthellate corals for coral aragonite the 88 86sr ratio may serve as a new paleo temperature proxy and introduces new perspectives in paleoceanography with respect to intermediate water dynamics

evidence for stable sr isotope fractionation by silicate weathering in a small sedimentary watershed in southwestern taiwan abstract radiogenic sr isotopes 87 sr 86 sr are robust for provenance identification in hydrology affected mainly by the age of background lithologies and the degree of chemical weathering however there is limited knowledge concerning the fractionation mechanism of stable sr isotopes 88 sr 86 sr in rivers in this study river water was collected on a weekly to monthly basis throughout dry and wet seasons furthermore to study the variations of radiogenic and stable sr isotopes during intense weathering a major flooding event 2000 mm precipitation in three days typhoon morakot water was captured within a small drainage catchment system 161 km 2 along the hou ku river in southwestern taiwan for a better constraint on the end member compositions bedload sediments suspended particles and several host rocks were sampled for a systematic investigation the carbonate and silicate phases of these solids were chemically separated dissolved major elements indicate that the watersheds were predominated by silicate weathering stable sr isotopes show no significant variation 88 sr 0 24 0 31 temporally and spatially with an average of 0 28 additionally all solids showed lower 88 sr values than the river water while the host rocks had higher 88 sr values 88 sr 0 20 0 26 than the residual weathering products 88 sr 0 08 0 22 indicating preferential leaching of heavy sr into the hydrosphere and leaving light sr in the residual solids results of laboratory acid leaching experiments reveal that dissolution of high 88 sr value minerals occurred at an early stage of weathering the variation of weathering intensity does not alter stable sr isotopes in silicate weathering dominated river water which contains higher stable sr isotopes than the associated sediments the silicatic sedimentary rocks preferentially released higher stable sr isotopes into the hydrosphere during chemical weathering thus leaving lower stable sr isotopes in the residual solids

the origin and migration of mud volcano fluids in taiwan evidence from hydrogen oxygen and strontium isotopic compositions abstract mud volcanoes are important gateways for deep fluids to migrate upward and provide windows for studying fluid sediment interaction at depth fluids emitted from 40 terrestrial mud volcanoes were collected in southern and eastern taiwan to study their chemical compositions including h o and sr isotopes 87sr 86sr and 88 86sr relative to seawater the mud volcano fluids are depleted in cl mg so42 and d and are elevated in b ba li and 18o possibly due to water rock interaction and clay dehydration mainly smectite to illite transformation in the source region the distribution of sr in mud volcano fluids shows patterns associated with their localities and geological settings most fluids have higher 87sr 86s than seawater indicating water rock interaction at depth the low na 87sr 86s and high ca fluids emitted from eastern taiwan imply intense interaction with igneous basement most fluids have higher sr cl and lower 88sr than seawater except mud volcanoes in the northern chu kou fault which emit low sr cl and extremely high 88sr up to 0 82 fluids we performed laboratory carbonate precipitation experiments that indicate that these high sr isotope ratios are caused by co precipitation of carbonates from high alkalinity fluids mud volcano fluids in taiwan originate at depth and their chemical compositions are controlled by the host rock degrees of water rock interaction and clay dehydration but also are masked by retrograde progresses such as carbonate precipitation during migration our results show that an approach combining water isotopes d and 18o and strontium isotopes 87sr 86sr and 88 86sr provides a robust tool for tracing fluid sources and migration pathways in accretionary prisms

environmental boundary conditions of cold water coral mound growth over the last 3 million years in the porcupine seabight northeast atlantic iodp expedition 307 made it for the first time possible to investigate the entire body of a cold water coral carbonate mound here we provide new insights into the long term history of challenger mound on the european continental margin off ireland this study is based on age determinations 230th u 87sr 86sr and geochemical signals mg li and ba ca measured in the scleractinian cold water coral lophelia pertusa from iodp site 1317 in the porcupine seabight the paleoceanographic reconstructions reveal that coral growth in the porcupine seabight was restricted to specific oceanographic conditions such as enhanced export of primary production and bottom water temperatures bwt between 8 10 c related to the water mass stratification of the mediterranean outflow water mow and eastern north atlantic water enaw the geochemical signals from the coral skeletons can be explained by the close interaction between cold water coral growth sea surface productivity and the surrounding water masses the boundary layer between mow and enaw enhanced sea surface productivity and the build up of a stable water mass stratification between enaw and mow caused enhanced nutrient supply at intermediate water depths and facilitated a steady mound growth between 3 0 2 1 ma with the decrease in sea surface productivity and related reduced export productivity the food supply was insufficient for rapid coral mound growth between 1 7 1 ma during the late pleistocene over the last 0 5 myr mound growth was restricted to interglacial periods during glacials the water mass boundary between enaw mow probably was below the mound summit and hence food supply was not sufficient for corals to grow

introducing δ88 86sr analysis in archaeology a demonstration of the utility of strontium isotope fractionation in paleodietary studies abstract isotopic methods are widely used in archaeology to investigate paleodiet here we present a new method to identify trophic level in archaeological human populations and to investigate paleodiet we demonstrate that strontium isotope compositions reported as 88 86sr vary in a mass dependent manner with increasing trophic level and can elucidate paleodiet in archaeological human populations we present new mass dependent strontium isotope data from tooth enamel and bone from individuals buried during the late intermediate period c ad 1000 1300 in the large cemeteries of chiribaya alta chiribaya baja san geronimo and el yaral in the ilo and moquegua valleys of southern peru we compare these data to radiogenic strontium isotope data 87sr 86sr and light stable isotope data 15ncol and 13ccol from the same individuals to investigate geologic variability in strontium sources as well as marine food consumption among the chiribaya our results demonstrate the utility of measurements of strontium isotope fractionation as a new tool for archaeological investigation of paleodiet importantly this new technique can be used to generate paleodietary 88 86sr and paleomobility 87sr 86sr data from the same specimen minimizing destructive analyses of invaluable archaeological material and provides a new way to examine paleodiet through hydroxyapatite which is particularly important when collagen is poorly preserved

exploring the impact of diagenesis on isotope geochemical and microstructural alteration features in biogenic aragonite for the quaternary and neogene aragonitic biogenic and abiogenic carbonates are frequently exploited as archives of their environment conversely pre neogene aragonite is often diagenetically altered and calcite archives are studied instead nevertheless the exact sequence of diagenetic processes and products is difficult to disclose from naturally altered material here experiments were performed to understand biogenic aragonite alteration processes and products shell subsamples of the bivalve arctica islandica were exposed to hydrothermal alteration thermal boundary conditions were set at 100 degrees c 175 degrees c and 200 degrees c these comparably high temperatures were chosen to shorten experimental durations subsamples were exposed to different o 18 depleted fluids for durations between two and twenty weeks alteration was documented using x ray diffraction cathodoluminescence fluorescence and scanning electron microscopy as well as conventional and clumped isotope analyses experiments performed at 100 degrees c show redistribution and darkening of organic matter but lack evidence for diagenetic alteration except in delta 47 which show the effects of annealing processes at 175 degrees c valves undergo significant aragonite to calcite transformation and neomorphism the delta o 18 signature supports transformation via dissolution and reprecipitation but isotopic exchange is limited by fluid migration through the subsamples individual growth increments in these subsamples exhibit bright orange luminescence at 200 degrees c valves are fully transformed to calcite and exhibit purple blue luminescence with orange bands the delta o 18 and delta 47 signatures reveal exchange with the aqueous fluid whereas delta c 13 remains unaltered in all experiments indicating a carbonate buffered system clumped isotope temperatures in high temperature experiments show compositions in broad agreement with the measured temperature experimentally induced alteration patterns are comparable with individual features present in pleistocene shells this study represents a significant step towards sequential analysis of diagenetic features in biogenic aragonites and sheds light on reaction times and threshold limits the limitations of a study restricted to a single test organism are acknowledged and call for refined follow up experiments

determination of temperature dependent stable strontium isotope 88sr 86sr fractionation via bracketing standard mc icp ms stable strontium isotopes here 88sr 86sr are introduced as a new member of the nontraditional stable isotopes we have developed a bracketing standard method for the determination of 88 86sr using an axiom mc icp ms and normalizing to strontium srm nbs987 for individual measurements the external reproducibility is better than about 25 ppm 1 rsd for the iapso seawater standard a 88 86sr value of 0 381 0 010 2sem was determined for the first time a temperature dependent strontium isotope fractionation during calcium carbonate precipitation could be shown aragonite samples inorganically precipitated under temperature control between 10 and 50 c revealed a 88 86sr temperature dependency of 0 0054 5 c r2 0 987 in contrast for natural coral samples pavona clavus from a proxy calibration study 23 to 27 c we did determine 0 033 5 c r2 0 955 the processes causing this sixfold stronger temperature dependency for the natural coral samples have to be studied in more detail in future studies in a first approach the different slopes can be interpreted as effects of kinetic fractionation of strontium ions with or without a hydrate shell of 22 to 29 water molecules

deep sea coral aragonite as a recorder for the neodymium isotopic composition of seawater deep sea corals have been shown to be useful archives of rapid changes in ocean chemistry during the last glacial cycle their aragonitic skeleton can be absolutely dated by u th data freeing radiocarbon to be used as a water mass proxy for certain species of deep sea corals the growth rate allows time resolution that is comparable to ice cores an additional proxy is needed to exploit this opportunity and turn radiocarbon data into rates of ocean overturning in the past neodymium isotopes in seawater can serve as a quasi conservative water mass tracer and initial results indicate that deep sea corals may be reliable archives of seawater nd isotopes here we present a systematic study exploring nd isotopes as a water mass proxy in deep sea coral aragonite we investigated five different genera of modern deep sea corals caryophyllia desmophyllum enallopsamia flabellum lophelia from global locations covering a large potential range of nd isotopic compositions comparison with ambient seawater measurements yields excellent agreement and suggests that deep sea corals are reliable archives for seawater nd isotopes a parallel study of nd concentrations in these corals yields distribution coefficients for nd between seawater and coral aragonite of 1 10 omitting one particular genus enallopsamia the corals and seawater did however not come from exactly the same location and further investigations are needed to reach robust conclusions on the incorporation of nd into deep sea coral aragonite lastly we studied the viability of extracting the nd isotope signal from fossil deep sea corals by carrying out stepwise cleaning experiments our results show that physical removal of the ferromanganese coating and chemical pre cleaning have the highest impact on nd concentrations but that oxidative reductive cleaning is also needed to acquire a seawater nd isotope signal

mollusc and brachiopod skeletal hard parts intricate archives of their marine environment the biogenic carbonate hard parts of fossil bivalves cephalopods and brachiopods are among the most widely exploited marine archives of phanerozoic environmental and climate dynamics research the advent of novel analytical tools has led many workers to explore non traditional geochemical and petrographic proxies and work performed in neighbouring disciplines sheds light on the complex biomineralization strategies applied by these organisms these considerations form a strong motivation to review the potential and problems related to the compilation and interpretation of proxy data from bivalve cephalopod and brachiopod hard parts from the viewpoint of the sedimentologist and palaeoceanographer specific focus is on the complex biomineralization pathways of a given dissolved ion or food particle from its aquatic environment via the digestion and biomineralization apparatus in molluscs and brachiopods and its incorporation into a biomineral given that molluscs and brachiopods do not secrete their hard parts from seawater but rather from their mantle and periostracum this paper evaluates differences and similarities of seawater versus that of body fluids cephalopods bivalves and brachiopods exert a strong biological control on biomineralization that to some degree may buffer their shell geochemistry against secular changes in seawater chemistry disordered amorphous calcium carbonate precursor phases later transformed to crystalline biominerals may be significant in carbonate archive research due to expected geochemical offset relative to the direct precipitation of stable phases a reasonable level of understanding of the related mechanisms is thus crucial for those who use these skeletal hard parts as archives of the palaeo environment the impact of what is commonly referred to as biological factors on the geochemistry of mollusc and brachiopod hard parts is explored for conventional isotope systems such as carbon oxygen strontium and traditionally used element to calcium ratios in particular the often used 13ccarb or the mg ca and sr ca elemental proxies are fraught with problems an interesting new research field represents the analysis calibration and application of non traditional proxies to mollusc and brachiopod hard parts examples include the carbonate clumped isotope 47 approach and the analysis of the isotopes of ca mg n li s or element to ca ratios such as li ca or b ca and rare earth elements based on considerations discussed here a series of do s and don ts in mollusc and brachiopod archive research are proposed and suggestions for future work are presented in essence the suggestions proposed here include experimental work also field experiments making use of recent archive organisms or where possible a reasonable recent analogue in the case of extinct groups moreover the detailed understanding of the architecture of mollusc and brachiopod hard parts and their ultra structures must guide sampling strategies for geochemical analyses where feasible a detailed understanding of the diagenetic pathways and the application of multi proxy and multi archive approaches should form the foundation of fossil carbonate archive research the uncritical compilation of large data sets from various carbonate shelled organisms collected at different locations is not encouraged

environmental constraints on holocene cold water coral reef growth off norway insights from a multiproxy approach high latitude cold water coral cwc reefs are particularly susceptible due to enhanced co2 uptake in these regions using precisely dated u th cwcs lophelia pertusa retrieved during research cruise pos 391 lopphavet 70 6 n oslofjord 59 n we applied boron isotopes 11b ba ca li mg and u ca ratios to reconstruct the environmental boundary conditions of cwc reef growth the sedimentary record from these cwc reefs reveals a lack of corals between 6 4 and 4 8 ka the question remains if this phenomenon is related to changes in the carbonate system or other causes the initial postglacial setting had elevated ba ca ratios indicative of meltwater fluxes showing a decreasing trend towards cessation at 6 4 ka with a oscillation pattern similar to continental glacier fluctuations downcore u ca ratios reveal an increasing trend which is outside the range of modern u ca variability in l pertusa suggesting changes of seawater ph near 6 4 ka the reconstructed bwt at lopphavet reveals a striking similarity to barent sea surface and sub sea surface temperature records we infer that meltwater pulses weakened the north atlantic current system resulting in southward advances of cold and co2 rich arctic waters a corresponding shift in the 11b record from 25 0 to 27 0 probably implies enhanced ph up regulation of the cwcs due to the higher pco2 concentrations of ambient seawater which hastened mid holocene cwc reef decline on the norwegian margin

large deep water coral banks in the porcupine basin southwest of ireland the porcupine basin southwest of ireland was one of the earliest sites from where the deep water corals lophelia sp and madrepora sp were recovered these deep water corals have since been found all along the atlantic margins of europe in water depths ranging from 50 to more than 2000 m recent geophysical studies have demonstrated the mound building potential of deep water corals available data indicate that three major provinces of coral bank occurrences can be identified in the porcupine basin 1 high relief surface mounds which have a dimension of 1 by 5 km and a height up to 200 m hovland mounds flanked to the north by 2 a swarm of buried mounds somewhat smaller up to 90 m and with more irregular shapes than those recognised in area 1 magellan mounds and 3 outcropping or buried conical mounds single or in elongated clusters up to 150 m high occurring on the southeastern slope of the basin belgica mounds as far as can be inferred from shallow cores the surface lithology predominantly consists of an upper layer rich in foraminiferal sand and terrigenous silty clay with intercalations of biogenic rubble the banks host a remarkable number of colonies of living and dead lophelia pertusa and madrepora oculata the living and dead assemblages are underlain by a significant layer of coral debris in a muddy matrix deep water coral debris together with a living association of the same species covers the surface of the belgica and hovland mounds which may suggest that these corals have played a significant role in the development of the mound structures the capacity for mound formation by scleractinian corals in the aphotic zone has been known for some time examples are found at different locations along the shelves and the continental margins of the north atlantic the role of the corals in these deep water build ups is still a point of debate though the genesis and initial control of mound settings in this basin might be related to hydrocarbon seeps it appears that the major development of the porcupine coral banks in recent geological times has most likely been controlled by oceanic circulation and dynamics in water masses and nutrient supply

radiogenic and stable strontium isotopes in provenance studies a review and first results on archaeological wood from shipwrecks abstract different approaches are used to study wood provenance but most of them are based on tracers in wood that are generally controlled by climatic factors the strontium isotopic ratio 87 sr 86 sr in trees and soils is related to the signature of the local bedrock despite being used in diverse archaeological studies sr isotopes have rarely been used to trace the provenance of archaeological wood and especially wood from shipwrecks in addition recent analytical advances have allowed the detection of mass dependent fractionation of sr isotopes during biogeochemical processes as reflected in the variation of 88 86 sr values between different environmental materials the 88 86 sr values could be used in conjunction with the 87 sr 86 sr isotope ratio to improve constraints on the sources of sr in the archaeological materials being studied this paper discusses the potential and limitations of using both of these sr isotope ratios to trace the provenance of wood from shipwrecks we review the 87 sr 86 sr and 88 86 sr variations in rocks waters soils plants and other living organisms and discuss how to determine the local sr isotopic signature of potential sites we also compile a list of known wood post mortem modifications in seawater possible implications in terms of the modification of the original sr isotope ratios of wood during storage in seawater are illustrated through preliminary observations this paper points out some limitations and perspectives for using sr isotopes in provenancing wood from shipwrecks and suggests future research to test and apply this approach for tracing the origin of archaeological wood

slip distribution and tectonic implication of the 1999 chi chi taiwan earthquake we report on the fault complexity of the large m w 7 6 chi chi earthquake obtained by inverting densely and well distributed static measurements consisting of 119 gps and 23 doubly integrated strong motion records we show that the slip of the chi chi earthquake was concentrated on the surface of a wedge shaped block the inferred geometric complexity explains the difference between the strike of the fault plane determined by long period seismic data and surface break observations when combined with other geophysical and geological observations the result provides a unique snapshot of tectonic deformation taking place in the form of very large 10m displacements of a massive wedge shaped crustal block which may relate to the changeover from over thrusting to subducting motion between the philippine sea and the eurasian plates

reassessing the stable δ88 86sr and radiogenic 87sr 86sr strontium isotopic composition of marine inputs the stable strontium isotope system 88 86sr has recently been suggested to be a suitable proxy for determining variations in the strength of the marine carbonate system the principal output flux of oceanic sr however in order to be able to interpret carbonate driven variations in 88 86srseawater a robust understanding of 88 86srinput is required surprisingly only a limited amount of 88 86sr data currently exists for rivers and hydrothermal fluids thus this study assesses the variability of 88 86sr and 87sr 86sr in global rivers hydrothermal fluids and porewaters as well as minor marine sr sources such as continental dust rainwater and glacial ice our analyses broadly confirm the findings of krabbenhoft et al 2010 and reveal flux weighted 88 86srriverine and 87sr 86srriverine compositions of 0 32 and 0 71299 respectively the hydrothermal fluids analysed in this study are consistent with an end member 88 86srhydrothermal composition that is the same as the oceanic crust at 0 24 although three samples that display 88 86sr compositions offset from the seawater hydrothermal mixing trend suggest that the precipitation of alteration phases such as anhydrite may drive 88 86srhydrothermal to higher values porewater fluids obtained from sediment cores in the atlantic and pacific oceans have 88 86sr compositions within error of seawater 0 39 implying that the diagenetic flux of sr may not significantly affect the 88 86sr composition of seawater continental loess samples have 88 86sr compositions that are consistently lighter than or equal to terrestrial silicates with their tendency to lower values thought to reflect the preferential removal of heavier sr isotopes into solution during weathering finally rainwater and glacial ice samples have 88 86sr compositions that are also isotopically lighter than their associated water sources a factor that may be attributed to interaction with isotopically light loess and additional sr contributions from the bedrock together the principal marine inputs define flux weighted oceanic 88 86srinput and 87sr 86srinput compositions of 0 32 and 0 71161 these values are consistent with an elevated supply of riverine sr to the oceans due to increased post glacial weathering but require the enhanced weathering of exposed carbonate shelves during glacial periods or significant changes in the rate of carbonate burial to match observed changes in the 87sr 86sr ratio of seawater our results confirm that providing a diagenetically robust proxy can be found the 88 86sr and 87sr 86sr isotope systems should provide a useful proxy for investigating changes in the marine carbonate system through time

benthic dynamics at the carbonate mound regions of the porcupine sea bight continental margin a brief review is given of some dynamical processes that influence the benthic dynamics within the carbonate mound provinces located at the porcupine bank sea bight margin ne atlantic the depth range of the mounds in this region 600 1 000 m marks the upper boundary of the mediterranean outflow water above which eastern north atlantic water dominates both water masses are carried northwards by the eastern boundary slope current in the benthic boundary layer both the action of internal waves and other tidal period baroclinic waves may enhance the bottom currents and add to both the residual and maximum flow strength both residual and maximum bottom currents vary at different mound locations with stronger currents found at belgica se porcupine sea bight mound and pelagia nw porcupine bank mound regions whilst weakest currents are found at the hovland and magellan mounds at the northern sea bight margin the differences may be attributed to the presence of internal waves pelagia or bottom intensified diurnal waves belgica these different dynamical regimes are likely to have implications for the distribution patterns of live coral at the different locations

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

ostracod shell chemistry as proxy for paleoenvironmental change abstract the application of ostracod shell chemistry as a paleoenvironmental tool has grown within the past decades most studies have investigated mg and sr in ostracod shells as proxies for temperature and salinity and the use of a wide range of trace elements as prospective paleoenvironmental indicators has yet to be developed for lacustrine systems only a few preliminary studies have used trace metals in paleolimnological studies such as cd ba and zn as paleonutrient indicators or mn fe and u as redox and oxygenation indicators this paper reviews the state of the art of geochemical analyses in microfossils such as ostracods foraminifera and corals and provides insights in new trace element proxies with the goal to promote the use of trace elements in ostracod shells as paleoenvironmental proxies in paleoceanography foraminifera and corals are most prominently used to reconstruct past climate conditions well established proxies such as 18o mg ca and sr ca provide information about changes in sea surface temperatures in addition a great number of new proxies have been developed recently such as radiogenic isotopes and redox sensitive trace elements in paleolimnology ostracod shell chemistry is widely used to assess paleohydrological changes reconstruction of temperature and salinity changes in lake environments is often achieved by oxygen isotopes as well as mg ca and sr ca ratios but depending on the hydrological and geological settings of the lake system local calibrations are needed to assess which proxy is suited to reflect which processes new proxies need to be tested by novel techniques that recently have become available compared to conventional instrumentation used in ostracod shell chemistry methods such as laser ablation icp ms and nanosims allow single shell analysis and provide high resolution data the potential of ostracods in paleolimnology is not yet fully assessed but can be developed by learning from paleoceanographic studies

strontium isotope fractionation of planktic foraminifera and inorganic calcite we have investigated the strontium isotope fractionation 88 86srcarb aq between inorganic calcite and aqueous sr2 ions by precipitation experiments at a constant temperature of 25 c and precipitation rates r ranging from 102 3 to 104 2 mol m2 h strontium isotope ratios were measured using the 87sr 84sr double spike technique it was found that strontium isotope fractionation in these calcites is strongly dependent on the precipitation rate view the mathml source the measured 88 86sr values are significantly correlated with previously measured 44 40ca and sr ca values of the same calcite samples 88 86srcarb aq 0 18 44 40cacarb aq 0 01 view the mathml source the slope of 88sr 86sr versus 44ca 40ca fractionation is 0 18 0 04 and compatible with a kinetic fractionation during dehydration of the strontium and calcium ions but not with isotope fractionation in a diffusive boundary layer using published equilibrium 44 40cacarb aq and view the mathml source values we estimate the equilibrium isotope fractionation of strontium to be very close to zero 88 86sreq carb aq 0 01 0 06 this estimate is confirmed by strontium isotope values of natural inorganic calcites that precipitated very slowly in basalts of the ocean crust the results from the inorganic calcites are used to explain strontium isotope fractionation of planktic foraminifera specimens of two warm water species globigerinoides ruber and globigerinoides sacculifer were picked from the holocene section of a caribbean sediment core we found no significant difference in 88 86sr between the two species in addition g ruber specimens from marine isotope stage 2 in the same core show 88 86sr values identical to the holocene specimens the strontium isotopes of both foraminifera species are strongly fractionated 88 86srcarb aq 0 248 0 005 when compared to published data of other major marine calcifiers applying the results from the inorganic precipitation experiments we find that the strong foraminiferal strontium isotope fractionation can be explained by calcification in a largely open system at high precipitation rates comparable in magnitude to rates known from scleractinian reef corals this interpretation is in good agreement with the kinetic calcification model for planktic foraminifera by kisakurek et al 2011 which was based on calcium isotopes and elemental sr ca ratios

strontium isotopes trace biological activity in the critical zone along a climate and vegetation gradient abstract weathering and ecosystem nutrition are intimately linked through the supply of fresh mineral nutrients from regolith and bedrock the geogenic nutrient pathway however the prominence of this link is dependent on the efficiency of nutrient recycling from plant litter the organic nutrient cycle isotope ratios of strontium sr an element that behaves similarly to ca in ecosystems confer two types of information radiogenic sr isotopes inform as to the sources of sr and the degree of weathering while stable sr isotopes constrain partitioning between compartments of the critical zone bedrock water secondary solids and plants to date however neither the reactions nor the mass balance between compartments that fractionate sr isotopes nor the fractionation factors involved are well understood here we present geochemical budgets of sr using radiogenic and stable sr isotopes and ca sr ratios at four sites along a substantial climate and primary production gradient in the coastal mountains of chile we found that sr release through weathering is isotopically congruent and released sr is not strongly isotopically fractionated either during secondary mineral formation or transfer into the exchangeable pool despite this the 88sr 86sr ratio of bio available sr which should reflect the ratio of dissolved sr is higher than that of rock and regolith we propose that this offset is caused by plants while 88sr 86sr in plant organs at the four study sites systematically increased from roots towards their leaves whole plant sr isotope compositions indicate preferential uptake of light sr into plants with a fractionation of up to 0 3 relative to the bio available pool despite this strong biological fractionation 88sr 86sr ratios in bio available sr do not covary with biomass production across our study sites because with greater plant growth sr is recycled more times after release by weathering an isotope neutral process rather the loss of sr from the ecosystem in solid organic material sets the isotope ratio of dissolved or bio available sr organic solids thus appear to constitute a significant export path of elements released during weathering with the removal of solid plant debris reducing the recycling factor of sr and possibly that of other mineral nutrients too

environmental changes and growth history of a cold water carbonate mound propeller mound porcupine seabight on and off mound sediment cores from propeller mound hovland mound province porcupine seabight were analysed to understand better the evolution of a carbonate mound the evaluation of benthic foraminiferal assemblages from the off mound position helps to determine the changes of the environmental controls on propeller mound in glacial and interglacial times two different assemblages describe the holocene and marine isotope stage mis 2 and late mis 3 31 kyr bp the different assemblages are related to changes in oceanographic conditions surface productivity and the waxing and waning of the british irish ice sheet biis during the last glacial stages the interglacial assemblage is related to a higher supply of organic material and stronger current intensities in water depth of recent coral growth during the last glaciation the benthic faunas showed high abundances of cassidulinid species implying cold bottom waters and a reduced availability of organic matter high sedimentation rates and the domination of elphidium excavatum point to shelf erosion related to sea level lowering 50 m and the progradation of the biis onto the shelf a different assemblage described for the on mound core is dominated by discanomalina coronata gavelinopsis translucens planulina ariminensis cibicides lobatulus and to a lower degree by hyrrokkin sarcophaga these species are only found or show significantly higher relative abundances in on mound samples and their maximum contribution in the lower part of the record indicates a higher coral growth density on propeller mound in an earlier period they are less abundant during the holocene however this dataset portrays the boundary conditions of the habitable range for the cold water coral lophelia pertusa which dominates the deep water reefal ecosystem on the upper flanks of propeller mound the growth of this ecosystem occurs during interglacial and interstadial periods whereas a retreat of corals is documented in the absence of glacial sediments on mound glacial conditions with cold intermediate waters a weak current regime and high sedimentation rates provide an unfavourable environmental setting for lophelia corals to grow a late pleistocene decrease is observed in the mound growth for propeller mound which might face its complete burial in the future as it already happened to the buried mounds of the magellan mound province further north

sr ca and mg ca vital effects correlated with skeletal architecture in a scleractinian deep sea coral and the role of rayleigh fractionation deep sea corals are a new tool in paleoceanography with the potential to provide century long records of deep ocean change at sub decadal resolution complicating the reconstruction of past deep sea temperatures mg ca and sr ca paleothermometers in corals are also influenced by non environmental factors termed vital effects to determine the magnitude pattern and mechanism of vital effects we measure detailed collocated sr ca and mg ca ratios using a combination of micromilling and isotope dilution icp ms across skeletal features in recent samples of desmophyllum dianthus a scleractinian coral that grows in the near constant environment of the deep sea sr ca variability across skeletal features is less than 5 2 relative standard deviation and variability of sr ca within the optically dense central band composed of small and irregular aragonite crystals is significantly less than the surrounding skeleton the mean sr ca of the central band 10 6 0 1 mmol mol 2 standard error and that of the surrounding skeleton 10 58 0 09 mmol mol are statistically similar and agree well with the inorganic aragonite sr ca temperature relationship at the temperature of coral growth in the central band mg ca is greater than 3 mmol mol more than twice that of the surrounding skeleton a general result observed in the relative mg ca ratios of d dianthus collected from separate oceanographic locations this large vital effect corresponds to a 10 c signal when calibrated via surface coral mg ca temperature relationships and has the potential to complicate paleoreconstructions outside the central band mg ca ratios increase with decreasing sr ca we explain the correlated behavior of mg ca and sr ca outside the central band by rayleigh fractionation from a closed pool an explanation that has been proposed elsewhere but which is tested in this study by a simple and general relationship we constrain the initial solution and effective partition coefficients for a rayleigh process consistent with our accurate metal ca measurements a process other than rayleigh fractionation influences mg in the central band and our data constrain a number of possible mechanisms for the precipitation of this aragonite understanding the process affecting tracer behavior during coral biomineralization can help us better interpret paleoproxies in biogenic carbonates and lead to an improved deep sea paleothermometer

constraining the marine strontium budget with natural strontium isotope fractionations 87sr 86sr δ88 86sr of carbonates hydrothermal solutions and river waters we present strontium sr isotope ratios that unlike traditional 87sr 86sr data are not normalized to a fixed 88sr 86sr ratio of 8 375209 defined as 88 86sr 0 relative to nist srm 987 instead we correct for isotope fractionation during mass spectrometry with a 87sr 84sr double spike this technique yields two independent ratios for 87sr 86sr and 88sr 86sr that are reported as 87sr 86sr and 88 86sr respectively the difference between the traditional radiogenic 87sr 86sr normalized to 88sr 86sr 8 375209 and the new 87sr 86sr values reflect natural mass dependent isotope fractionation in order to constrain glacial interglacial changes in the marine sr budget we compare the isotope composition of modern seawater 87sr 86sr 88 86sr seawater and modern marine biogenic carbonates 87sr 86sr 88 86sr carbonates with the corresponding values of river waters 87sr 86sr 88 86sr river and hydrothermal solutions 87sr 86sr 88 86sr hydend in a triple isotope plot the measured 87sr 86sr 88 86sr river values of selected rivers that together account for not vert similar18 of the global sr discharge yield a sr flux weighted mean of 0 7114 8 0 315 8 the average 87sr 86sr 88 86sr hydend values for hydrothermal solutions from the atlantic ocean are 0 7045 5 0 27 3 in contrast the 87sr 86sr 88 86sr carbonates values representing the marine sr output are 0 70926 2 0 21 2 we estimate the modern sr isotope composition of the sources at 0 7106 8 0 310 8 the difference between the estimated 87sr 86sr 88 86sr input and 87sr 86sr 88 86sr output values reflects isotope disequilibrium with respect to sr inputs and outputs in contrast to the modern ocean isotope equilibrium between inputs and outputs during the last glacial maximum 10 30 ka before present can be explained by invoking three times higher sr inputs from a uniquely glacial source weathering of shelf carbonates exposed at low sea levels our data are also consistent with the weathering peak hypothesis that invokes enhanced sr inputs resulting from weathering of post glacial exposure of abundant fine grained material

compositional variability in a cold water scleractinian lophelia pertusa new insights into vital effects we analyzed sr ca and mg ca ratios in the thecal wall of lophelia pertusa a cold water coral using sims ion microprobe techniques the wall grows by simultaneous upward extension and outward thickening compositional variability displays similar trends along the upward and outward growth axes sr ca and mg ca ratios oscillate systematically and inversely the sensitivity of lophelia sr ca ratios to the annual temperature cycle 0 18 mmol mol 1 c is twice as strong as that exhibited by tropical reef corals and four times as strong as the temperature dependence of sr ca ratios of abiogenic aragonites precipitated experimentally from seawater a comparison of the skeletal composition of lophelia with results from precipitation calculations carried out using experimentally determined partition coefficients suggests that both temperature dependent element partitioning and seasonal changes in the mass fraction of aragonite precipitated from the calcifying fluid influence the composition of lophelia skeleton results from calculations that combine these effects reproduce both the exaggerated amplitude of the sr ca and mg ca oscillations and the inverse relationship between sr ca and mg ca ratios

a biological origin for climate signals in corals trace element vital effects are ubiquitous in scleractinian coral skeletons 1 laser ablation icp ms was used to analyze mg sr and u at fine hundreds of microns and seasonal spatial scales in the reef coral porites and the non photosynthetic deep sea corals lophelia oculina and desmophyllum tropical corals display strong seasonal correlations between mg sr and u even when normal cycles are perturbed by unknown factors an inverse relationship between mg and u is a universal feature of all the corals but is much larger in deep corals despite stable environmental conditions this correlation originates from two aragonitic skeletal types mg rich opaque centers of calcification and u rich large translucent crystals the mg rich material probably precipitates rapidly and corresponds to materials strongly deficient in 18o and 13c compared to isotopic equilibrium combined these observations imply that varying proportions of the two skeletal types may account for most of the temperature or climate signal in tropical corals as well as anomalous vital effects

cold water coral carbonate mounds as unique palaeo archives the plio pleistocene challenger mound record ne atlantic through the interplay of a stabilising cold water coral framework and a dynamic sedimentary environment cold water coral carbonate mounds create distinctive centres of bio geological accumulation in often complex continental margin settings the iodp expedition 307 drilling of the challenger mound eastern porcupine seabight ne atlantic not only retrieved the first complete developmental history of a coral carbonate mound it also exposed a unique early pleistocene sedimentary sequence of exceptional resolution along the mid latitudinal ne atlantic margin in this study a comprehensive assessment of the challenger mound as an archive of quaternary palaeo environmental change and long term coral carbonate mound development is presented new and existing environmental proxy records including clay mineralogy planktonic foraminifer and calcareous nannofossil biostratigraphy and assemblage counts planktonic foraminifer oxygen isotopes and siliciclastic particle size are thereby discussed within a refined chronostratigraphic and climatic context overall the development of the challenger mound shows a strong affinity to the plio pleistocene evolution of the northern hemisphere climate system albeit not being completely in phase with it the two major oceanographic and climatic transitions of the plio pleistocene the late pliocene early pleistocene intensification of continental ice sheet development and the mid pleistocene transition to the more extremely variable and more extensively glaciated late quaternary mark two major thresholds in challenger mound development its late pliocene 2 74 ma origin and its middle late pleistocene to recent decline distinct surface water perturbations i e water mass polar front migrations productivity changes melt water pulses are identified throughout the sequence which can be linked to the intensity and extent of ice development on the nearby british irish isles since the earliest pleistocene glaciation induced shifts in surface water primary productivity are thereby proposed to fundamentally control cold water coral growth which in turn influences on mound sediment accumulation and hence coral carbonate mound development throughout the pleistocene as local factors such as proximal ice sheet dynamics and on mound changes in cold water coral density significantly affected the development of the challenger mound they can potentially explain the nature of its palaeo record and its offsets with the periodicities of global climate variability on the other hand owing to this unique setting a regionally exceptional high resolution palaeo record of early pleistocene ca 2 6 to 2 1 ma environmental change including early british irish ice sheet development broadly in phase with the 41 ka paced global climate system is preserved in the lower challenger mound all in all the challenger mound record highlights the wider relevance of coral carbonate mound archives and their potential to capture unique records from dynamic continental margin environments

grounding pleistocene icebergs shape recent deep water coral reefs the widespread view that scleractinian corals in cold and deep waters of high latitudes are slow growing organisms that do not form reefs is challenged by the discovery of a huge coral reef over 13 km in length 10 to 35 m in height and up to 300 m in width formed by the coral lophelia pertusa in water depths of 270 to 310 m at 64 n on the sula ridge mid norwegian shelf cruises in 1994 1995 and manned submersible operations in may 1997 provide data and observations from which the structure and development of the sula ridge coral reef have been determined the fennoscandian icesheet retreated from the mid norwegian shelf prior to 12 000 years before present and modern oceanographic conditions were established at 8000 years before present coral growth since that time has resulted in a large deep water shelf reef for which recent stable isotopic studies have demonstrated high growth rates for these azooxanthellate cold water corals information on the geometry of deep water coral reefs and their environmental controls is still fragmentary controversial and raises issues of conservation in this area of active fishing and oil exploration this paper reports on the discovery of what is probably one of the largest deep water coral reefs existing in the northeast atlantic and indicates that its siting is due to post glacial structures iceberg plough marks events the second storegga slide and local conditions on the seafloor surprisingly reef accumulation rates on the sula ridge are comparable with those measured on tropical coral reefs