the geochemistry of deep sea coral skeletons a review of vital effects and applications for palaeoceanography deep sea corals were discovered over a century ago but it is only over recent years that focused efforts have been made to explore the history of the oceans using the geochemistry of their skeletal remains they offer a promising archive of past oceanic environments given their global distribution layered growth patterns longevity and preservation as well as our ability to date them using radiometric techniques this paper provides an overview of the current state of the art in terms of geochemical approaches to using deep sea coral skeletons to explore the history of the ocean deep sea coral skeletons have a wide array of morphologies e g solitary cup corals branching colonial corals and materials calcite aragonite and proteins as such their biomineralization strategies are diverse leading to complex geochemistry within coral skeletons notwithstanding these complications progress has been made on developing methods for reconstructing the oceanographic environment in the past using trace elements and isotopic methods promising approaches within certain coral groups include clumped isotopes and mg li for temperature reconstructions boron isotopes and radiocarbon for carbon cycling end and radiocarbon for circulation studies and 15 n p ca and ba ca for nutrient tracer studies likewise there is now a range of techniques for dating deep sea corals skeletons e g u series radiocarbon and determining their growth rates e g radiocarbon and 210 pb dating studies on historic coral populations in the atlantic southern ocean and pacific point to climate and environmental changes being dominant controls on coral populations over millennial and orbital timescales this paper provides a review of a range of successes and promising approaches it also highlights areas in which further research would likely provide new insights into biomineralization palaeoceanography and distribution of past coral populations

magnetic fabric and its significance in the sills and lava flows from taimyr fold belt arctic siberia abstract magnetic fabric research on the emplacement of the taimyr fold belt is still absent therefore we have performed magnetic fabric studies on samples collected from 23 sites from mafic igneous rocks 75 n 100 e in south taimyr this study indicates a correlation between the anisotropy of magnetic susceptibility ams magma flow and fold related compression in the rocks ams measurements on 183 unheated and 122 heated samples reveal the magma flow directions the magma flow direction is mainly parallel to the ese wnw and secondarily parallel to the ssw from the nne in the mafic sills the unheated and heated basaltic flows reveal a ne trending flow vector in some of the sills ams shows a tight clustering of the maximum k1 axes close to the bedding pole which is not thought to define the flow direction corresponding ams measurements on igneous rocks allow us to infer the existence of magnetic fabrics of tectonic origin linked to the main folding episode that occurred subsequent to the mid triassic magmatic event in latest triassic early jurassic times in the sills the distribution of most maximum k1 axes is close to ns that corresponds to the maximum compressive stress or folding directions contrarily the minimum k3 axes have an elongated distribution along the ew direction or parallel to the fold axis before exchanging k1 and k3 axes for inverse fabrics but close to the ns stress direction after exchanging k1 and k3 axes for inverse fabrics in the basaltic flows the minimum k3 axes almost parallel to the ns folding direction the structural interpretation of all ams data taken from the igneous bodies is in accordance with a nnw sse stress related folding taking place around 198 ma in the taimyr peninsula arctic siberia the relationship of susceptibility axes to bedding surfaces and magnetic foliation planes is a criterion that permits differentiation of normal magnetic fabrics from inverse fabrics in the igneous samples single domain sd and small pseudo single domain psd magnetite crystals in the sill samples are the main carriers of the ams fabrics implying the abundance of inverse magnetic fabrics psd and multidomain md titanomagnetite tm grains as well as minor hematite are identified in the basalt flows suggesting the occurrence of more normal magnetic fabrics in the basalts than in the sills

dike surface lineations as magma flow indicators within the sheeted dike complex of the troodos ophiolite cyprus mesoscopic flow lineations and anisotropy of magnetic susceptibility ams have been measured for dikes within the cretaceous age troodos ophiolite with the goal of comparing the direction of initial magma flow through dike conduits immediately following crack propagation with that of flow of subsequent magma emplaced during later stages of dike growth dike margin indicators of flow include cusp axes and elongate vesicles found high in the ophiolite pseudostratigraphy and ridge and groove structures termed hot slickenlines found throughout the complex a unique flow direction is determined where elongate vesicles near dike margins display imbrication with respect to the margin significant changes in vesicle elongation directions across dikes likely indicate either changes in magma flow direction after dike propagation or back flow of magma during the waning stages of intrusion surface lineations generally lie subparallel to the direction of flow inferred from ams determinations on cores within 5 cm of dike margins surface lineations also lie subparallel to the long axis e1 of the orientation ellipsoid defined by long axes of groundmass plagioclase phenocrysts measured in sections from ams cores correlation of surface lineations with interior indicators of flow ams plagioclase trachytic texture indicate that the surface features are good proxies for grain scale magma flow directions during dike propagation in troodos dikes orientations of surface flow features in the dikes of the troodos ophiolite indicate an approximately equal mix of subhorizontal to near vertical magma flow contradicting the paradigm of primarily vertical flow of magma beneath continuous axial magma chambers at oceanic spreading centers our data are consistent with a model of magma emplacement both vertically and horizontally away from isolated magma chambers beneath axial volcanoes spaced along a ridge crest

shallow intrusive directions of sheeted dikes in the troodos ophiolite anisotropy of magnetic susceptibility and structural data sheeted dikes play a central role in the formation of oceanic crust it is commonly assumed that sheeted dikes intrude vertically upward from elongated mid ocean ridge mor magma chambers but there are no direct observational data bearing on this hypothesis this assumption contrasts with the intrusive behavior of subaerial volcanoes where magmas rise into shallow central magma chambers that laterally feed vertically oriented dikes the authors have studied intrusive directions of sheeted dikes in a structural analogue to oceanic crust the troodos ophiolite structural and magnetic fabric data of 65 dikes provide consistent results and suggest a broad distribution of shallow 20 degree to nearly vertical upward magma transport directions these data suggest that horizontal emplacement has to be considered for sheeted dikes at mors implying more centralized mor plumbing systems than previously thought such plumbing systems provide ample opportunity for complex mixing fractionation and contamination of mor lavas in magma chambers and tabular magma storage volumes whether the mor magma supply is linear or centralized also has a fundamental effect on crustal accretion processes and the geometry of hydrothermal convection systems

major shifts in nutrient and phytoplankton dynamics in the north pacific subtropical gyre over the last 5000 years revealed by high resolution proteinaceous deep sea coral δ15n and δ13c records abstract the north pacific subtropical gyre npsg is the largest continuous ecosystem on earth and is a critical component of global oceanic biogeochemical cycling and carbon sequestration we report here multi millennial scale sub decadal resolution records of bulk stable nitrogen 15 n and carbon 13 c isotope records from proteinaceous deep sea corals data from three kulamanamana haumeaae specimens from the main hawaiian islands extend the coral based time series back 5000 yrs for the npsg and bypass constraints of low resolution sediment cores in this oligotrophic ocean region we interpret these records in terms of shifting biogeochemical cycles and plankton community structure with a main goal of placing the extraordinarily rapid ecosystem biogeochemical changes documented by recent coral records during the anthropocene in a context of broader late holocene variability during intervals where new data overlaps with previous records there is strong correspondence in isotope values indicating that this older data represents a direct extension of anthropocene records these results reveal multiple large isotopic shifts in both 15 n and 13 c values similar to or larger in magnitude to those reported in the last 150 yrs this shows that large fluctuations in the isotopic composition of export production in this region are not unique to the recent past but have occurred multiple times through the mid to late holocene however these earlier isotopic shifts occurred over much longer time intervals millennial vs decadal timescales further the 15 n data confirm that the extremely low present day 15 n values recorded by deep sea corals 8 are unprecedented for the npsg at least within the past five millennia together these records reveal centennial to millennial scale oscillations in npsg biogeochemical cycles further these data also suggest a number of independent biogeochemical regimes during which 15 n and 13 c trends were synchronous similar to recent coral records or distinctly decoupled we propose that phytoplankton species composition and nutrient source changes are the dominant mechanisms controlling the coupling and de coupling of 15 n and 13 c values likely primarily influenced by changing oceanographic conditions e g stratification vs entrainment the decoupling observed in the past further suggests that oceanographic forcing and ecosystem responses controlling 15 n and 13 c values of export production have been substantially different earlier in the holocene compared to mechanisms controlling the present day system

effects of drill cuttings on larvae of the cold water coral lophelia pertusa abstract fossil fuel consumption is predicted to dominate energy needs until at least 2040 to make up for reduced production from maturing fields oil and gas exploration activities on the norwegian continental shelf have greatly increased over the past several years strict emission controls have resulted in a substantial reduction in the release of hazardous chemicals however because of the increased exploration the discharges of water based drill cuttings and muds have increased substantially temporarily increasing water column sediment loads the stony coral lophelia pertusa is the most widely distributed and well studied of the structure forming cold water corals cwc and it thrives in norwegian waters where many reefs are located in the vicinity of oil platforms or exploration areas this species provides habitat for a diverse and abundant assemblage of invertebrates and fishes including commercially valuable species high sediment loads are known to negatively affect adult corals but impacts on the early life history stages are unknown we investigated the effects of a range of drill cutting concentrations 0 5 640 ppm on larvae of l pertusa at ages five days and 15 20 days one set of experiments was conducted in static experimental chambers that exposed larvae to decreasing concentrations over time and the other maintained continuous drill cutting concentrations for the duration of the experiment 24 h increased sediment load for a duration of 24 h caused significant larval mortality but there was an age dependent difference in sensitivity of larvae younger larvae were significantly more susceptible to lower concentrations of drill cuttings than older larvae while the older larvae were significantly more affected at higher concentrations five day old larvae were affected at treatment concentration 40 ppm the larval cilia became clogged preventing the larvae from swimming actively and ultimately causing mortality larvae of many species use cilia for swimming and feeding so negative impacts of increased sediment may not be limited to corals

geochemistry of the siberian trap of the noril sk area ussr with implications for the relative contributions of crust and mantle to flood basalt magmatism the sequence investigated of the siberian trap at noril sk ussr consists of at least 45 flows that have been divided into six lava suites the lower three suites consist of alkalic to subalkalic basalts the ivakinsky suite overlain by nonporphyritic basalts the syverminsky suite and porphyritic and picritic basalts the gudchikhinsky suite the upper three suites are tholeiitic the uppermost 750 m of dominantly non porphyritic basalt belong to the mokulaevsky suite and are characterized by a nearly constant mg number 0 54 0 56 sio2 48 2 49 1 wt ce 12 18 ppm and ce yb 5 8 the underlying 1100 m of dominantly porphyritic basalt belong to the morongovsky and nadezhdinsky suites there is a continuous increase in sio2 48 1 55 2 wt ce 12 41 ppm and ce yb 5 18 from the top of the mokulaevsky to the base of the nadezhdinsky with little change in the mg number 0 53 0 59 mokulaevsky magmas have trace element signatures similar to slightly contaminated transitional type mid ocean ridge basalts the change in major and trace element geochemistry in the upper three suites is consistent with a decline in the degree of anatexis and assimilation of tonalitic upper crust by mokulaevsky magma the nadezhdinsky and underlaying lavas thicken within and thus appear to be related to an elongate basin centred on the noril sk talnakh mining camp the mokulaevsky and morongovsky lavas thicken to the east and appear to be related to a basin centred more than 100 km to the east of the noril sk region these magmas may have risen up out of a different conduit system

gerardia bristlecone pine of the deep sea we measured carbon isotope abundances in the layered proteinaceous skeleton of a zoanthid gerardia collected from 620 m depth off the little bahama bank 27 n 79 w the 14c values decreased from 76 in the outer growth edge to an average of 267 in the center of three portions of the skeleton these 14c data suggest an age for this living organism of 1800 300 years the possibility that the large decrease in 14c reflects the gradual input of bomb 14c over the entire growth of the organism is inconsistent with the post bomb 14c values obtained for the most recent growth tips if the age estimate of two millennia is correct it may be the longest lived animal yet observed in the ocean gerardia may serve as a long lived recorder of ocean chemistry similar to the bristlecone pine tree that has served as a millennial timescale recorder for atmospheric 14co2 suess 1980 and climate in particular there is potential for gerardia to serve as a millennial scale integrator of upper ocean particle flux and possibly reveal past changes in the productivity of the surface ocean

magnetic and plagioclase linear fabric discrepancy in dykes a new way to define the flow vector using magnetic foliation in basaltic dykes the magnetic lineation k1 maximum magnetic susceptibility axis is generally taken to indicate the flow direction during solidification of the magma this assumption was tested in tertiary basaltic dykes from greenland displaying independent evidence of subhorizontal flow the digital processing of microphotographs from thin sections cut in k1 k2 planes yields the preferred linear orientation of plagioclase which apparently marks the magma flow lineation in up to 60 of cases the angular separation between k1 and the assumed flow direction is greater than 45 this suggests that the uncorroborated use of magnetic lineations in dykes is risky a simple geometrical method is proposed to infer the flow vector from ams in dykes based solely on magnetic foliations

magma flow inferred from anisotropy of magnetic susceptibility in the coastal parana etendeka igneous province evidence for rifting before flood volcanism the parana etendeka igneous province is one of the largest flood volcanic provinces in the world peak magmatic activity at 132 ma is believed to have occurred about 5 m y before the birth of south atlantic sea floor and development of rift basins along the brazilian coastal margin anisotropy of magnetic susceptibility ams measurements on 283 samples 28 flows and 3 sills from the etendeka igneous province of namibia and 180 samples 21 flows from the parana province in brazil reveal remarkably consistent fabric orientations with maximum susceptibility k1 axes subhorizontal and parallel to the rifted margin the ams results are most likely due to shape anisotropy reflecting magma flow directions suggesting that lava flows and intrusive conduits near the eventual rifted margin were controlled by structures having topographic expression in existence at the time of peak flood volcanism these results imply that rifting preceded flood volcanism at least in the portion of the magmatic province within 100 km of the nascent mid atlantic ridge

rock texture and magnetic lineation in dykes a simple analytical model abstract we develop two simple models for simulating the combination of magnetic sub fabrics related to magma flow in dykes the basic assumptions are i the petrofabric is representative of the flow fabric and ii the petrofabric is composed of s c type structures related to flow the first model consists of summing the magnetic tensors of two identical sub fabrics differing solely by their relative rotation this model accounts for the possible change of the macroscopic magnetic lineation from a flow related fabric to a lineation situated at the geometric intersection between the two sub fabrics such a result is obtained in the case of oblate to highly oblate sub fabric ellipsoids the second model integrates the effect of very oblate grains of variable orientations into calculating the shape controlled magnetic tensor of each sub fabric and emphasizes the possible under estimation of fabric superposition due to microscopic disordering the magma fluxes along the east greenland volcanic margin are illustrated by the flow pattern within the major dyke swarm the magmatic flow vectors inferred from the imbrication of magnetic foliation at the dyke margins are primarily horizontal the classic use of magnetic lineation can lead to contradictory results giving flow vectors perpendicular to the flow directions the magnetic lineation is situated close to the zone axis of magnetic foliation planes over a wide range of scales throughout the dyke swarm suggesting that the contradiction may arise from the association of several textural domains at the sample scale forward modelling of macroscopic magnetic fabrics using the first model yields good agreement with the measured magnetic fabric of the east greenland dykes our results which are applicable to strained sedimentary rocks highlight the possible misuse of the magnetic lineation due to combination of magnetic textures the exchange between a microscopic lineation i e mineralogical lineation and a macroscopic lineation i e intersection lineation is particularly expected for dykes that generally bear oblate magnetic textures

drained creep of undisturbed cohesive marine sediments long term drained triaxial creep and direct simple shear creep tests were conducted on undisturbed marine specimens from the gulf of mexico and the north central pacific results indicated that time dependent deformations can be represented by a power law equation and the creep strain rate can be represented by an equation similar to that suggested earlier by other researchers however it was found that the m parameter suggested by these scientists was not a constant but dependent on stress level and sediment plasticity ageing effects were evidenced in triaxial specimens by the increase of shear strength with both test duration and stress level the results provided a guide for the development of mathematical stress strain time relationships that will be developed in a separate paper key words drained triaxial creep simple shear creep stress strain time behavior

the internal structure of lava flows insights from ams measurements ii hawaiian pahoehoe toothpaste lava and a ā abstract we studied the anisotropy of magnetic susceptibility ams of 22 basaltic flow units including s type pahoehoe p type pahoehoe toothpaste lava and a emplaced over different slopes in two hawaiian islands systematic differences occur in several aspects of ams mean susceptibility degree of anisotropy magnetic fabric and orientation of the principal susceptibilities among the morphological types that can be related to different modes of lava emplacement ams also detects systematic changes in the rate of shear with position in a unit allowing us to infer local flow direction and some other aspects of the velocity field of each unit a flows are subject to stronger deformation than pahoehoe and also their internal parts behave more like a unit according to ams the central part of pahoehoe commonly reveals a different deformation history than the upper and lower extremes probably resulting from endogenous growth

is this magnetic fabric normal a review and case studies in volcanic formations abstract when studying weakly anisotropic rocks non standard relationships between magnetic and expected petrofabric axes are sometimes observed in particular the so called inverse or intermediate fabrics a review of possible explanations for these effects is presented and leads to the conclusion that a majority of abnormal magnetic fabrics often encountered in magnetite rich volcanic rocks are due to abnormal preferred orientations or distributions of magnetite grains through case studies in dikes from skye island yemen and the iberian peninsula and magma and ash flows from the ethiopian traps and southern corsica the various possible origins of such fabrics are examined it is possible to retrieve reliable magma flow directions from these sites provided proper data selection is performed leading to non unique interpretations

distribution anisotropy the cause of ams in igneous rocks understanding of ams in pristine basic igneous rocks in terms of flow orientation of ellipsoidal magnetite grains is thwarted by the fact that these grains 1 typically are irregularly equant or skeletal rather than distinctly ellipsoidal and 2 usually crystallize interstitially and late after magma flow has ceased however the distribution of such grains will be relatively anisotropic if they grew in residual liquid volumes within a preferredly oriented by flow silicate template this constraint may impose a slight preferred shape orientation to the irregular magnetite grains during their growth but in addition we suggest it is the anisotropic magnetic interaction between the grains which is the basic cause of ams experiments involving the casting of magnetite epoxy mixtures in various foliated or lineated glass templates have yielded samples with the expected ams symmetry i e k3 perpendicular to glass plates or k1 parallel to glass rods slicing of near isotropic synthetic blank and natural rock cores and interleaving with glass slides showed a progressive increase in anisotropy of the blank from 0 4 to 2 and the natural rock from 0 9 to 2 9 in both the k3 axis migrates to be perpendicular to the glass slides

magnetic fabric flow directions and source area of the lower miocene peach springs tuff in arizona california and nevada we have used anisotropy of magnetic susceptibility ams to define the flow fabric and possible source area of the peach springs tuff a widespread rhyolitic ash flow tuff in the mojave desert and great basin of california arizona and nevada the tuff is an important stratigraphic marker from the colorado plateau to barstow california a distance of 350 km however the location of its source caldera is unknown dated at 18 5 ma by 40ar 39 ar the tuff erupted during the early stages of miocene extension along the lower colorado river the thicker accumulations 100 m occur at kingman arizona and in the piute mountains california on opposite sides of the colorado river extensional corridor our ams studies produced well defined magnetic lineations in 30 of 42 sites distributed throughout the tuff typical ratios of the principal ams axes are 1 01 for the magnetic lineation kmax kint and 1 02 for the foliation kint kmin the bulk magnetic susceptibility of the peach springs tuff averages 2 0 10 3 in the si unit system the subhorizontal lineations which presumably parallel the flow directions form a pattern radiating outward from the approximate center of the outcrop area magnetic foliations define an imbrication that generally dips away from the distal margins and toward the center of the outcrop of the tuff the lineation and imbrication indicate a source region near the southern tip of nevada defining the best intersection of the ams lineations required restoration of major extension strike slip faulting and associated tectonic rotation in the disrupted tuff the optimum intersection of magnetic lineations lies in the southern black mountains of arizona on the eastern side of the colorado river extensional corridor no caldera structures are known from that area but the area contains thick sections of the peach springs tuff above a silicic volcanic center the caldera may be buried under younger deposits in the mohave valley of arizona tertiary granite in the newberry mountains may represent a deeper level of the peach springs tuff vent that has been exhumed by detachment faulting

decade time scale variability of ventilation in the north atlantic high precision measurements of bomb radiocarbon in banded corals the first high precision radiocarbon measurements for the upper ocean are presented for banded corals from two sites in the north atlantic ocean the striking dissimilarities between the post 1950 records at bermuda in the sargasso sea and the florida straits in the gulf stream illustrate the different mixing processes in the upper ocean at each site convective overturn associated with 18 degree water formation during late winter in the northern sargasso sea facilitates storage of considerable quantities of bomb radiocarbon at depth which accounts for the damping of the 14c signal at bermuda during the 1960s a multibox isopycnal mixing model is used to estimate the ventilation rate of the upper 700 m of the water column in the sargasso sea from 1950 to 1983 an inverse model is used that is the water mass renewal rate was calculated for the post bomb period in order to satisfy the bomb radiocarbon time history in the corals sea water radiocarbon measurements made during the geosecs 1972 1973 and transient tracers in the ocean 1980 1981 surveys are used to constrain the subsurface radiocarbon values calculated by the model results show that the rate of water mass renewal in the sargasso sea was high during 1963 1964 decreased during the late 1960s and remained low during most of the 1970s the 14c derived record of water mass renewal precedes by about 4 years that derived from isopycnal salinity in the sargasso sea jenkins 1982 illustrating that the coral 14c record is controlled to a large extent by changes in ocean circulation rather than by atmospheric exchange of co2

magnetostratigraphy of the lower triassic volcanics from deep drill sg6 in western siberia evidence for long lasting permo triassic volcanic activity summary the deep drill hole sg6 in western siberia 66 n 78 5 e penetrated 1 1 km of lower triassic basalts which are possibly an extension of the central siberian permo triassic flood basalt province about 300 samples of these basalts were progressively demagnetized and measured principal component analysis often shows multiple magnetizations carried by haematite and magnetite the corrected mean inclinations are 77 and 77 for the haematite component a magnetostratigraphic scale was derived and showed a n r n r n succession this is quite diverent from the noril sk and taimyr typical polarity scale r n the basalts found in the sg6 deep drill hole are slightly younger than those of central siberia and taimyr they correspond to middle upper induan age whereas the noril sk and taimyr sections correspond to an uppermost permian and lower induan age altogether they indicate that after a high output rate of volcanic material near the permo triassic boundary this activity slowed down drastically on the siberian platform and taimyr but persisted for several million years in western siberia

flow dynamics in mid jurassic dikes and sills of the ferrar large igneous province and implications for long distance magma transport abstract magma flow paths in sill fed dikes of the ferrar large igneous province lip contrast with those predicted by classic models of dike transport in lips and magmatic rift settings we examine anisotropy of magnetic susceptibility ams flow paths in dike networks at terra cotta mountain and mt gran which intruded at paleodepths of 2 5 and 1 5 km these intrusions up to 30 m thick exhibit irregular interconnected dike sill geometries and adjoin larger sills 200 300 m thick at different stratigraphic levels both shallowly dipping and sub vertical magma flow components are interpreted from ams measurements across individual intrusions and often match macroscopic flow indicators and variations in dike attitudes flow paths suggest that intrusive patterns and magma flow directions depended on varying stress concentrations and rotations during dike and sill propagation whereas a regional extensional tectonic control was negligible or absent unlike giant dike swarms in lips elsewhere e g 1270 ma mackenzie lip dikes of the ferrar lip show no regionally consistent vertical or lateral flow patterns suggesting these intrusion were not responsible for long distance transport in the province in the absence of regionally significant colinear dike swarms or observed intrusions at crustal depths 4 km we suggest that long distance magma transport occurred in sills within beacon supergroup sedimentary rocks this interpretation is consistent with existing geochemical data and thermal constraints which support lateral magma flow for 3 500 km across the gondwana supercontinent before freezing

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

flow patterns in the siberian traps deduced from magnetic fabric studies summary the siberian traps rank among the largest flood basalt provinces in the world major magmatic activity is restricted to several short periods of less than 1 myr around the permo triassic boundary we measured the anisotropy of magnetic susceptibility ams of 183 basaltic samples from 28 individual lava flows belonging to the northwestern part of the flood basalt province in order to test the reliability of such data in structural interpretation these preliminary ams data show a remarkably consistent pattern of magnetic lineations that likely reflect the primary flow related texture of the basalt our results also emphasize that ams data are consistent with the well documented petrological and geochronological data the inferred flow directions are also consistent with flow directions expected from isopach maps our results suggest that the entire 2 km thick lava pile was fed by fissure eruptions located in the rifted basin that bound the siberian platform and was controlled by topographical features particularly major rift zones

uranium series dating and growth characteristics of the deep sea scleractinian coral enallopsammia rostrata from the equatorial pacific the deep sea coral enallopsammia rostrata a member of the dendrophylliidae family is a major structure forming species that creates massive dendroid colonies up to 1 m wide and 0 5 m tall living colonies of e rostrata have been collected using the pisces submersibles from three locations from 480 to 788 m water depth in the line islands similar to 160 degrees w in the equatorial pacific we have applied to these colonies a high sensitivity low blank technique to determine u series ages in small quantities 70 15 mg of modern and near modern calcareous skeletons using mc icp ms multi collector inductively coupled plasma mass spectrometer the application of this method to living slow growing colonies from a range of sites as well as the observations of axial growth patterns in thin sections of their skeletons offer the first expanded and well constrained data on longevity growth pattern and mean growth rates in e rostrata absolute dated specimens indicate life spans of colonies ranging from 209 8 yrs to 605 7 yrs with radial growth rates from 0 012 to 0 072 mm yr 1 and vertical extension rates from 0 6 to 1 9 mm yr 1 the linear growth rates reported here are lower than those reported for other deep sea scleractinian corals lophelia pertusa and madrepora oculata the u series dating indicates that the growth ring patterns of e rostrata are not consistent with annual periodicity emphasizing the importance of absolute radiometric dating methods to constrain growth rates slow accretion and extreme longevity make this species and its habitat especially vulnerable to disturbances and impacts from human activities this dating method combined with observation of growth patterns opens up new perspectives in the field of deep sea corals since it can provide quantitative estimates of growth rates and longevity of deep sea corals in general

growth rate of a deep sea coral using 210pb and other isotopes abstract a deep sea coral was studied to determine its growth rate and to reconstruct time histories of isotope distributions in the deep ocean the specimen was collected at a depth of 600 m off little bahama banks using the deep submergence vehicle dsv alvin the growth rate of the calcitic coral trunk was determined using excess 210pb measured in concentric bands excess 210pb was found in the outer half of the coral s radius and a growth rate of 0 11 0 02 mm a is calculated assuming a constant growth rate during formation of the entire trunk an age of 180 40 a is estimated for the coral the decrease observed in radiocarbon activities measured on the same bands griffin and druffel 1989 concurred with the growth rate estimated from excess 210pb activity 239 240pu activities measured by mass spectrometry were also detected in the outer two bands of the coral as expected from the 210pb chronology stable oxygen and carbon isotopes measured in samples collected by a variety of techniques are positively correlated this is evidence of a variable kinetic isotope effect most likely caused by variations in the skeletal growth rate long lived corals such as this specimen have the potential for serving as integrators of seawater chemistry in the deep sea over several century timescales

deep water antipatharians proxies of environmental change deep water 307 697 m antipatharian black coral specimens were collected from the southeastern continental slope of the united states and the north central gulf of mexico the sclerochronology of the specimens indicates that skeletal growth takes place by formation of concentric coeval layers we used 210 pb to estimate radial growth rate of two specimens and to establish that they were several centuries old bands were delaminated in koh and analyzed for carbon and nitrogen stable isotopes carbon values ranged from 16 4 to 15 7 the oldest specimen displayed the largest range in values nitrogen values ranged from 7 7 c to 8 6 two specimens from the same location and depth had similar 15 n signatures indicating good reproducibility between specimens

interpretation of anisotropy of magnetic susceptibility fabric of ignimbrites in terms of kinematic and sedimentological mechanisms an anatolian case study abstract a study of the neogene low aspect ratio kizilkaya ignimbrite in the calc alkaline central anatolian volcanic province turkey has been carried out using the anisotropy of magnetic susceptibility ams technique on 46 sites irm hysteresis loops and curie temperature analysis indicate that magnetite is the main carrier of the magnetic signal in the ignimbrite the shape of the ams ellipsoids varies widely from site to site and the anisotropy is commonly low we review the data processing used in the literature on the ams of ignimbrites to calculate principal directions or to evaluate the quality of the results and we develop various simple techniques data filtering and contouring procedures in order to more accurately define the axis or symmetry of the ams fabric there is no simple relationship between the shape of the ams ellipsoids and the shape of the petrofabric ellipsoids similarly there is no direct relationship between magnetic and kinematic axes our results show that the source of the measured magnetic signal in these rocks is a complex result of various contributions including shape anisotropy of free and fixed magnetic crystals shape ams crystallization of magnetic grains on all surfaces and discontinuities during cooling of the ignimbrite distribution anisotropy and alteration by hydrothermal and meteoric water particular attention is paid to the interpretation of the ams stereoplots departing from the standard fabric of sedimentary rocks formed under unidirectional flow in order to explain these non standard ams fabrics we discuss their possible origin 1 in analytical and mineralogical terms instrumental artifact pollution by xenoclasts mineralogical inversion of the susceptibility axes secondary mimetic fabric and 2 in terms of sedimentological mechanisms rheology depositional processes in the present state of knowledge we conclude that due to the physico chemical complexity of the magnetic source the ams signal should be used and interpreted with care when attempting to decipher the sedimentological or rheological processes occurring in moving pyroclastic flows on the other hand ams has it greatest potential when used in conjunction with other techniques and when a large number of sampling sites and specimens is used

synchrony and causal relations between permian triassic boundary crises and siberian flood volcanism the permian triassic boundary records the most severe mass extinctions in earth9s history siberian flood volcanism the most profuse known such subaerial event produced 2 million to 3 million cubic kilometers of volcanic ejecta in approximately 1 million years or less analysis of 40 ar 39 ar data from two tuffs in southern china yielded a date of 250 0 0 2 million years ago for the permian triassic boundary which is comparable to the inception of main stage siberian flood volcanism at 250 0 0 3 million years ago volcanogenic sulfate aerosols and the dynamic effects of the siberian plume likely contributed to environmental extrema that led to the mass extinctions

the transfer of bomb radiocarbon and anthropogenic lead to the deep north atlantic ocean observed from a deep sea coral abstract deep ocean c 14 pb concentrations and pb isotopes were reconstructed from a deep sea coral enallopsammia rostrata from 1410 m depth off of bermuda our high resolution time series is created from closely spaced radial cross sections with samples taken from the center of concentric coral growth bands that we show to be the oldest portion of the section prebomb radiocarbon ages from the coral demonstrate that the vertical growth rate of the coral is linear and the age of the coral is estimated to be 560 630 yr old based on the growth rate using this age model to reconstruct c 14 in deep seawater we first detect bomb radiocarbon at the coral growth site around 1980 and show that c 14 increased from 80 1 average 1930 1979 to a plateau at 39 3 1999 2001 pb ca of the coral ranges between 1 1 4 5 nmol mol during the 16th and 17th centuries and pb isotope ratios 206pb 207pb 1 21 208pb 207pb 2 495 in this period agree with pre anthropogenic values found in the pelagic sediments of the north atlantic ocean basin coral pb ca is slightly elevated to 6 2 0 9 nmol mol between the 1740s and the 1850s and then increases to 25 1 0 2 nmol mol in the 1990s the increase in coral pb ca is accompanied by a decrease in coral 206pb 207pb and 208pb 207pb indicating that the increase was caused by the infiltration of anthropogenic pb to the coral growth site comparing our data to the surface coral c 14 and pb records from bermuda reveals a time scale of tracer transport from the surface ocean to the coral growth site some characteristic features e g the bomb derived c 14 increase appear in the deep ocean approximately 25 yr later than the surface but the overall increase of c 14 and pb in the deep ocean is smaller and slower than the surface showing the importance of mixing during the transport of these tracers

growth rates and ages of deep sea corals impacted by the deepwater horizon oil spill the impact of the april 2010 deepwater horizon dwh spill on deep sea coral communities in the gulf of mexico gom is still under investigation as is the potential for these communities to recover impacts from the spill include observation of corals covered with flocculent material with bare skeleton excessive mucous production sloughing tissue and subsequent colonization of damaged areas by hydrozoans information on growth rates and life spans of deep sea corals is important for understanding the vulnerability of these ecosystems to both natural and anthropogenic perturbations as well as the likely duration of any observed adverse impacts we report radiocarbon ages and radial and linear growth rates based on octocorals paramuricea spp and chrysogorgia sp collected in 2010 and 2011 from areas of the dwh impact the oldest coral radiocarbon ages were measured on specimens collected 11 km to the sw of the oil spill from the mississippi canyon mc 344 site 599 and 55 cal yr bp suggesting continuous life spans of over 600 years for paramuricea biscaya the dominant coral species in the region calculated radial growth rates between 0 34 m yr 1 and 14 20 m yr 1 are consistent with previously reported proteinaceous corals from the gom anomalously low radiocarbon 14 c values for soft tissue from some corals indicate that these corals were feeding on particulate organic carbon derived from an admixture of modern surface carbon and a low 14 c carbon source results from this work indicate fossil carbon could contribute 5 10 to the coral soft tissue 14 c signal within the area of the spill impact the influence of a low 14 c carbon source e g petro carbon on the particulate organic carbon pool was observed at all sites within 30 km of the spill site with the exception of mc118 which may have been outside of the dominant northeast southwest zone of impact the quantitatively assessed extreme longevity and slow growth rates documented here highlight the vulnerability of these long lived deep sea coral species to disturbance

growth and composition of high mg calcite in the skeleton of a bermudian gorgonian plexaurella dichotoma potential for paleothermometry 1 we used a secondary ion mass spectrometry sims ion microprobe to analyze magnesium to calcium mg ca and strontium to calcium sr ca ratios of high mg calcite loculi within the skeleton of a shallow water gorgonian plexaurella dichotoma from bermuda a cross section of the gorgonian skeleton reveals loculi embedded within proteinaceous gorgonin arranged in concentric rings about the axial core viewed in cross section the loculi are fan shaped 10 140 m in diameter and composed of bundles of needle shaped crystals that appear to radiate out from a calcification center discrete sample spots each 20 m diameter were sputtered from successive loculi along a sample track 3 mm long over this distance 25 bands of high low density gorgonin couplets were encountered estimated to represent the period 1963 to 1988 mg ca ratios show an overall positive correlation with annual sea surface temperatures ssts that is strongest in the autumn months october december high resolution analyses along the growth axes of individual loculi reveal low variability and no trend consistent with our interpretation of seasonal growth of these calcite inclusions the sensitivity of mg ca to interannual changes in average autumn temperatures is 0 47 mmol mol per c conversely interannual variability in calcite sr ca does not follow the interannual variability in sst and may be influenced primarily by growth rate

palaeomagnetism of east siberian traps and kimberlites two new poles and palaeogeographic reconstructions at about 360 and 250 ma summary we studied basalt sills and dykes and kimberlite pipes from the eastern part of the siberian platform these are spread out over a few hundred kilometres and are divided into two age groups late permian early triassic mir aikhal and olenyek regions and late devonian early carboniferous viluy and markha basins aikhal region the palaeomagnetic poles determined for each sill or dyke are statistically different from each other but averaging all corresponding directions from these sills and dykes with those from kimberlites of different generations yields results with acceptable statistics this is probably due to the averaging out of secular variation and or changes in magnetic polarity the resulting palaeomagnetic poles allow one to reconstruct the palaeopositions of siberia during the two large flood basalt events at about 360 and 250 ma a significant rotation of the siberian platform during the devonian and carboniferous is suggested the new data are in general agreement with some earlier palaeomagnetic poles for the late permian early triassic traps of the tungusska basin and significantly reduce uncertainties for previous late devonian early carboniferous siberian poles which were very scattered together with geological and absolute age data the palaeomagnetic data support the hypothesis that kimberlite magmatism and trap intrusions were both rapid and relatively close in time the 360 ma event is emerging as a magmatic event with considerable extent over the russian and siberian platforms related to incipient continental break up and triple junction formation possibly at or near the time of the frasnian famennian mass extinction

paleomagnetism and magnetostratigraphy of the traps from western taimyr northern siberia and the permo triassic crisis abstract the siberian traps were emplaced near the permo triassic boundary and are among the largest continental igneous provinces a 1750 m thick section of traps from the western taimyr 72 9 n 84 e has been sampled this section is equivalent to the lower and middle part of the total siberian traps section thirty one oriented hand samples were studied and demagnetised by alternating fields and heating cycles a stable characteristic component passes the fold test and is thought to be primary the mean direction is d 84 i 75 with 95 10 n 29 and the corresponding pole is 59 n 150 e the bottom part 660 m is of reversed polarity the middle part 900 m is normal and the uppermost level 150 m is mixed correlations with reference permo triassic magnetostratigraphic timescales are discussed the most probable correlation indicates an age quite close to the permian triassic boundary and a duration for the volcanism of less than 1 m y the data are therefore consistent with the hypothesis that this volcanism triggered the permian triassic crisis

proteinaceous corals as proxy archives of paleo environmental change abstract high resolution marine data are critical to evaluating anthropogenic impacts on our environment considering the spatial and temporal limitations of direct instrumental measurements proxy data extracted from marine environmental archives are necessary to separate anthropogenic changes from those that would occur naturally the majority of late holocene high resolution environmental reconstructions are derived from marine carbonates including tropical scleractinian corals bivalves crustose coralline algae and sclerosponges however these archives are restricted to the top hundreds of meters of the water column and only preserve environmental variability that is captured by calcium carbonate skeletons at a very few select locations marine sediments archive annual environmental variability in organic and inorganic materials recently additional types of corals are proving to yield information complimentary to these traditional marine archives including cold water scleractinian corals and proteinaceous corals a taxonomically diverse group the proteinaceous corals are broadly defined as those having a branching gross morphology with skeleton comprised at least partly of protein rich organic material they encode characteristics of their food and ambient environment into the chemical and physical composition of their skeleton this environmental encoding combined with their banded skeleton and significant longevity means that proteinaceous corals hold information in their skeleton that helps fill the spatial and temporal gaps in our knowledge of past and present ocean conditions here i review the environmental reconstructions derived from geochemical measurements of the proteinaceous coral skeletons this information is grouped into the mesopelagic environmental variability captured in the skeleton of bamboo corals surface processes captured in the organic skeletons of corals across all ocean depths and environmental variability documented by skeletal radiometric isotopes we include animals from two separate subclasses within the class anthozoa including the parasitic zoanthids that secrete a sclero proteic skeleton since the proteinaceous corals are taxonomically diverse we consider the unique features that define this group of corals including their distribution morphology nutrition and longevity we find that uncertainty surrounding biological parameters limits the precision of reconstructions derived from the calcitic skeleton in contrast analytical effort and cost constrain the number of reconstructions from the organic skeleton through this discussion we provide insights into the uses challenges and directions for future research for this important environmental archive