kinetic control of skeletal sr ca in a symbiotic coral implications for the paleotemperature proxy modeling of past climates is critically dependent on estimates of past sea surface temperatures ssts for which one of the principal techniques used is the measurement of sr ca ratios in corals guilderson et al 1994 mcculloch et al 1999 hughen et al 1999 the link between coral sr ca and sst is not well understood and there have been a number of discrepant observations de villiers et al 1995 alibert 1998 corals with symbiotic zooxanthellae are known to show large diurnal fluctuations in calcification rate associated with the photosynthetic activity of their symbionts using detailed measurements with the ion microprobe we compared the sr ca content of discrete daytime and nighttime skeletal structures in the massive hermatypic coral porties lutea over the course of 1 year and a seasonal temperature range of 4 c the sr ca content of daytime skeleton is always lower than that of adjacent nighttime skeleton while the slope of the nighttime sr ca sst correlation is close to that seen in inorganic aragonite precipitates that of the daytime correlation is 4 times as steep we attribute these differences to the role of photosynthesis in calcification and conclude that bulk sr ca is related principally to daytime calcification rate rather than directly to sst more reliable estimates of past sst may be arrived at through selective analysis of nighttime skeleton

analysis of local seismic waveforms from underground nuclear explosions forward modeling for effective source functions at pahute mesa in this study we use forward modeling of surface particle velocity data recorded within 15 km of underground nuclear explosions at pahute mesa in the nevada test site a plane layered velocity structure model is developed and effective source functions are obtained for six events with yields of 155 1300 kt kilotons recorded at ranges presumed to be well outside the zone of inelastic deformation we then use the effective source functions determined from well outside the elastic radius to compute synthetic seismograms for comparison with recordings within the spall zone prior to the onset of spall the comparison is good enabling us to estimate effective source functions for two additional events for which only recordings from the spall zone are available as surface zero is approached however the first half cycle of the observed velocity records includes an inflection which appears as a shoulder in acceleration records this suggests that in addition to the elastic arrival we are seeing secondary arrivals due to spall opening or inelastic shock wave propagation elastic wave propagation predicts the observed peak velocities well beyond a scaled slant range of about 175 m kt but overpredicts the first phase at closer ranges this limit of applicability of elastic wave propagation provides a useful estimate of the elastic radius for pahute mesa explosions yield scaling relations are determined using three events of known yield and these are then used to estimate yields for the eight pahute mesa explosions modeled in this study finally implications for the attenuation of teleseismic body waves are discussed

yield estimate 230 kt for a mueller murphy model of the 3 september 2017 north korean nuclear test m bneic 6 3 from teleseismic broadband p waves assuming extensive near source damage

pyritized chuarids with excystment structures from the late neoproterozoic lantian formation in anhui south china we report an unusual instance of macrofossil pyritization in the precambrian three dimensionally pyritized internal molds of chuarids from the late neoproterozoic lantian formation 550 600 ma in southern anhui province south china these chuarid internal molds are composed almost entirely of iron oxide pseudomorphs after pyrite framboids 5 20 m in diameter and polyhedra 1 2 m in diameter pyritization probably occurred near the water sediment interface during authigenesis the internal molds are typically enveloped by a diagenetic quartz rim furthermore about half of the lantian chuarid population display medial split excystment structures suggesting that the lantian chuarids are eukaryotic megacysts rather than colonial prokaryotes applying a similar megacyst interpretation to other proterozoic chuarid populations may not be straightforward largely because of the lack of diagnostic features in most chuarids chuarids in particular those in sole chuaria assemblages may therefore represent a polyphyletic group of diverse eukaryotic and perhaps prokaryotic origins although the chuaria tawuia association may represent a biologically and biostratigraphically coherent group

modular construction of early ediacaran complex life forms newly discovered exceptionally preserved soft bodied fossils near spaniard9s bay in eastern newfoundland exhibit features not previously described from ediacaran terminal neoproterozoic fossils all of the spaniard9s bay taxa were composed of similar architectural elements centimeter scale frondlets exhibiting three orders of fracticality in branching frondlets were combined as modules atop semi rigid organic skeletons to form a wide array of larger constructions including frondose and plumose structures this architecture and construction define the rangeomorphs a biological clade that dominated the mistaken point assemblage 575 to 560 million years ago but does not appear to be ancestral to any phanerozoic or modern organisms

ediacaran δ13c chemostratigraphy of south china abstract we report new 13 c chemostratigraphic data of the ediacaran system in south china using litho and biostratigraphic markers as independent calibrators we combine new and previously published 13 c data to construct a composite 13 c profile for the ediacaran system in south china the composite curve shows in chronostratigraphic order 1 a negative 13 c excursion en1 in the doushantuo cap carbonate that overlies the ghaub age nantuo diamictite 2 a pronounced positive 13 c excursion ep1 in the lower doushantuo formation where doushantuo type acanthomorphic acritarchs red algae and animal embryos first appear 3 a mild negative 13 c excursion en2 in the middle doushantuo formation 4 a positive 13 c excursion ep2 in the upper doushantuo formation where doushantuo type acanthomorphic acritarchs micrometazoans and stem group florideophyte red algae become abundant and diverse 5 a pronounced negative 13 c excursion en3 near the uppermost doushantuo formation 6 a strongly positive 13 c excursion up to 6 3 pdb ep3 in the lower dengying formation 7 a stable 13 c plateau ca 2 5 pdb ei in the middle and upper dengying formation where abundant vendotaenid algae macroscopic ediacaran fossils biomineralized animal tubes and mostly horizontal animal traces occur and 8 a 10 negative 13 c excursion en4 immediately below the ediacaran cambrian boundary the general pattern of this composite 13 c curve is robust despite a considerable amount of variation among the 13 c profiles of different sections this composite 13 c curve provides a first order chemostratigraphic framework for the subdivision and correlation of the ediacaran system in south china

effects of source rdp models and near source propagation implication for seismic yield estimation ithas proven difficult to uniquely untangle the source and propagation effects on the observed seismic data from underground nuclear explosions even when large quantities of near source broadband data are available for analysis this leads to uncertainties in our ability to quantify the nuclear seismic source function and consequently the accuracy of seismic yield estimates for underground explosions extensive deterministic modeling analyses of the seismic data recorded from underground explosions at a variety of test sites have been conducted over the years and the results of these studies suggest that variations in the seismic source characteristics between test sites may be contributing to the observed differences in the magnitude yield relations applicable at those sites this contributes to our uncertainty in the determination of seismic yield estimates for explosions at previously uncalibrated test sites in this paper we review issues involving the relationship of nevada test site nts source scaling laws to those at other sites the joint verification experiment jve indicates that a magnitude m b bias 6m b exists between the semipalatinsk test site sts in the former soviet union fsu and the nevada test site nts in the united states generally thissmbis attributed to differential attenuation in the upper mantle beneath the two test sites this assumption results in rather large estimates of yield for largem b tunnel shots at novaya zemlya a re examination of the us testing experiments suggests that thissm b bias can partly be explained by anomalous nts pahute source characteristics this interpretation is based on the modeling of us events at a number of test sites using a modified haskell source description we investigated the influence of the source reduced displacement potential rdp parameters lkand bby fitting short and long period data simultaneously including the near field body and surface waves in general estimates of band kare based on the initial p wave pulse which various numerical analyses show to be least affected by variations in near source path effects the corner frequency parameter kis 20 lower at nts pahute than at other sites implying larger effective source radii the overshoot parameter bappears to be low at nts although variable relative to other sites and is probably due to variations in source conditions for a low b the near field data require a higher value of to match the long period m s and short periodmbobservations this flexibility in modeling proves useful in comparing released fsu yields against predictions based onm b andm s

depth calculation for the january 06 2016 the september 09 2016 and the september 03 2017 nuclear tests of north korea from detailed depth phases using regional and teleseismic arrays north korea has conducted six underground nuclear explosions so far in this study we determined source depth and characterization for the 2016j 2016s and 2017s tests which were conducted on january 6 2016 2016j september 9 2016 2016s and september 3 2017 2017s respectively it has been difficult to ascertain the accurate depth of north korean nuclear explosions due to paucity of data and information we explore the depth calculation for the north korean nuclear tests based on the detailed depth phases using teleseismic and regional arrays we present the coherent spectral nulls from the average spectra of pp p sp p and ppn pn spn pn which correlate with the depth phases showing 180 phase reversals with the p wave arrivals we estimated the burial depths at 2 12 2 10 1 98 km for the 2016j 2016s and 2017s nuclear tests respectively we anticipate our absolute findings to be significant since in the past depth estimates for north korean nuclear tests have been inconclusive and unclear owing to not only paucity of data but also trade offs of the relative assessment based on the satellite images between the true source location and the tunnel entrance for the 2006 nuclear test used as a reference event

oceanic ph control on the boron isotopic composition of foraminifera evidence from culture experiments culture experiments were carried out with the species orbulina universa at four different ph values 7 70 0 05 8 15 0 05 8 60 0 05 and 9 00 0 10 in order to establish the ph dependence of boron isotope fractionation between seawater and foraminifera a clear relationship between the boron isotopic composition of the foraminifera and the ph of the seawater culture solutions was found showing heavier boron isotopic composition at higher ph this finding supports the viability of boron isotopes as a paleo ph tool it is important to note that orbulina universa cultured in natural seawater as well as those obtained from coretop samples have a significantly lighter boron isotopic ratio than globigerinoides sacculifer from coretop samples suggesting that at least for this species a vital effect is active

problematic fossils in the late neoproterozoic wonoka formation south australia abstract complex biogenic structures are described from the upper wonoka formation late neoproterozoic of the adelaide geosyncline south australia the structures are preserved within silty limestones and calcareous siltstones as dark bedding plane markings defining branching arrays of parallel elongate curved elements the fossils bear at least a superficial resemblance to the putative trace fossil palaeopascichnus normally preserved in siliciclastic sediments and reported from a number of late neoproterozoic sections worldwide the material from the wonoka formation is not a trace fossil and seems most likely to represent a surface encrusting alga the nature of palaeopascichnus needs to be carefully reassessed in the light of the possibility that the wonoka fossils represent a different preservational window into the same phenomenon the thin ca 2 m but widespread nature of the fossil horizon makes it a useful stratigraphic marker within the wonoka formation with the potential to aid in regional correlation within the adelaide geosyncline

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

ph control on oxygen isotopic composition of symbiotic corals abstract boron carbon and oxygen isotopic compositions were determined at the micrometre scale by high resolution ion microprobe in a sample of modern coral massive hermatypic coral porites lutea the ion probe data show for b and o much larger isotopic variations at the micrometre scale than those measured at the millimetre scale by conventional techniques 18opdb values range from 10 6 0 9 to 0 2 0 5 and 11b values range from 18 6 1 5 to 30 6 1 6 by contrast 13c values show the same range of variations from 4 6 0 65 to 2 2 0 67 at the micrometre and millimetre scales the range of 11b values indicates that significant ph variations from 7 1 to 9 0 are present at the sites of calcification the largest 18o variations correspond to the highest 11b values i e to the highest phs this measurement of ph allows modelling the oxygen isotopic fractionation occurring during aragonite precipitation taking into account the rate of o isotopic equilibrium between dissolved carbonate species h2co3 hco3 and co32 and water via the two reactions of hydration and hydroxylation the full range of 18o values measured at the micrometre scale can be modelled for residence times of dissolved carbonates in the calcifying fluid ranging between 1 h and at maximum 12 h the ph controls the 18o of the growing carbonate through the relative fractions of dissolved carbonate species and through the kinetics of their isotopic equilibration with water via hydration and hydroxylation the so called vital effect systematically observed for 18o in corals can thus be understood as representing an average of rapid ph variations due to coral biology during coral growth selectively measuring 18o values in the zones of coral skeletons that have low 11b values i e formed at low ph should significantly improve the quality of palaeoclimatic reconstructions based on 18o values

a new modular palaeopascichnid fossil curviacus ediacaranus new genus and species from the ediacaran dengying formation in the yangtze gorges area of south china non biomineralizing ediacaran macrofossils are rare in carbonate facies but they offer valuable information about their three dimensional internal anatomy and can broaden our view about their taphonomy and palaeoecology in this study we report a new ediacaran fossil curviacus ediacaranus new genus and species from bituminous limestone of the shibantan member of the dengying formation in the yangtze gorges area of south china curviacus is reconstructed as a benthic modular organism consisting of serially arranged and crescent shaped chambers the chambers are confined by chamber walls that are replicated by calcispars and are filled by micritic sediments such modular body construction is broadly similar to the co occurring yangtziramulus zhangii and other ediacaran modular fossils such as palaeopascichnus the preservation style of curviacus is similar to yangtziramulus although the phylogenetic affinities of both genera remain unresolved the new fossil adds to the diversity of ediacaran modular organisms

affirming life aquatic for the ediacara biota in china and australia the ediacara biota has been long championed as a snapshot of the marine ecosystem on the eve of the cambrian explosion providing important insights into the early evolution of animals fossiliferous beds in the eponymous ediacara member of south australia have been recently reinterpreted as paleosols and ediacara fossils as lichens or microbial colonies that lived on terrestrial soils this reinterpretation here dubbed the terrestrial ediacara hypothesis would fundamentally change our views of biological evolution just prior to the cambrian explosion we take a comparative paleobiology approach to test this hypothesis the ediacara member shares a number of forms with assemblages in ediacaran marine black shales in south china shales that show no evidence of pedogenesis thus the shared ediacara fossils and by extension other co occurring fossils are unlikely to have been terrestrial organisms a terrestrial interpretation is also inconsistent with functional morphological evidence some of the shared forms are not morphologically adapted to address the most critical challenges for terrestrial life e g mechanical support and desiccation thus the terrestrial ediacara hypothesis can be falsified on comparative paleobiological and functional morphological grounds and we urge paleopedologists to critically reevaluate evidence for pedogenesis in the ediacara member and other ediacaran successions

seismic yield estimation using teleseismic p and pkp waves recorded at the grf grafenberg array summary in this paper the transportability of magnitude yield relations for nuclear explosions at the nevada test site nts usa is investigated this test of applicability is done by comparing the yield estimates obtained in this study for the nts and other test sites at eastern kazakhstan novaya zemlya and mururoa french polynesia to selected yield estimates of more large scale investigations using different and more comprehensive data sets it is shown that the transportability of magnitude yield relations becomes possible if the differences in the absorption of seismic body waves in the upper mantle beneath the different test sites are correctly accounted for to estimate the yields of explosions from the four test sites a single magnitude yield relation has been used and a uniform methodology has been applied for the determination of source region corrections for upper mantle attenuation a linear relation between the grafenberg station magnitude mb grf and the network magnitude of the isc is established which can be used to predict the network mb from a measurement of mb grf recordings from pkp waves from french nuclear explosions in mururoa can through the appropriate determination of a core phase magnitude mb grf be used analogously for yield estimation however because of the possible network bias problem for mb measurements of mururoa events and because of the less well known absorption correction the results for that test site must be considered less substantiated using the derived magnitude yield relations the smallest observed magnitudes can be converted into yield values the detection threshold of the grf array for the single station a1 lies in the kt range for the eastern kazakhstan and novaya zemlya test sites and in the 10 kt range for the nevada test site the detection threshold of the grf array beam for the mururoa test site lies in the kt range

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

a procedure for modelling shallow dislocation sources summary expressions for displacements on the surface of a layered half space due to an arbitrary oriented shear dislocation are given in terms of generalized ray expansions useful approximations of these expressions for shallow events as recorded at teleseismic distances for realistic earth models are presented the results of this procedure are used to generate synthetic p sv and sh waveforms for various assumptions of stress drop

orbisiana linearis from the early ediacaran lantian formation of south china and its taphonomic and ecological implications abstract orbisiana is an ediacaran fossil characterized by linearly arranged circular or cylindrical units the genus was first described from the late ediacaran redkino series in the moscow syncline of russia where it is preserved as pyritic molds in siltstone here we report orbisiana linearis originally described as seirisphaera lineare from black shale of the early ediacaran lantian formation in south china unlike the type species o simplex o linearis is preserved as carbonaceous compressions on the bedding surface with rare specimens preserved three dimensionally allowing morphological characterization using x ray microct techniques morphological paleoecological and taphonomic analysis suggests that o linearis was a chain like modular organism characterized by uniserially arranged millimeter sized and tangentially contacting circular or cylindrical units ontogenetic growth of o linearis was likely achieved through both accretionary addition of new modules and inflational expansion of existing units and it appears that inflational growth was determinate although its phylogenetic affinity remains uncertain o linearis was likely a procumbent epibenthic or semi endobenthic organism that lived on the seawater sediment interface or partly buried in sediments o linearis in the lantian formation was preserved in situ although some specimens are disarticulated and many are tectonically deformed orbisiana joins a growing list of ediacaran genera that have a remarkable range of stratigraphic environmental ecological and taphonomic distribution

source characteristics of two underground nuclear explosions summary broadband seismic waveform data recorded in the distance range of 1 11 km from two underground explosions detonated at pahute mesa of the nevada test site have been used to estimate the source time functions for the second order moment tensors of these events data were available from eight three component stations for the explosion harzer and from 11 stations for the explosion chancellor stable moment tensor estimates with a good signal to noise ratio were obtained in the frequency range of 0 2 5 0 hz the moment tensors are dominated by the diagonal elements but a significant asymmetry is present with vertical force couples being larger having additional low frequency energy in the 0 3 0 4 hz range and having a different time dependence in the 0 5 2 5s range than the horizontal force couples considerable evidence points to the possibility that this asymmetry is related to spall processes taking place in the depth interval between the explosion and the free surface when the isotropic parts of the moment tensors are interpreted as reduced displacement potentials the results are in reasonable agreement with theoretical and empirical models except that the characteristic times are about three times those predicted by published scaling relationships this difference is most likely due to the effects of spall but the fact that the explosions were detonated in unsaturated materials may also be a contributing factor

beyond the stony veil reconstructing the earth s earliest large animal traces via computed tomography x ray imaging abstract trace fossils are superb lines of evidence for examining the ancient biologic world because they offer an opportunity to infer behavioral ecology of organisms however traces can be difficult to parse from their matrix which leads to the loss of important morphological and behavioral data this is especially true for the earliest marine animal traces from the ediacaran period 635 541 ma which are usually small

carbonate hosted avalon type fossils in arctic siberia avalon type fossils are crucial to understanding the origin of phanerozoic ecosystems but their usual occurrence in volcaniclastic and siliciclastic facies greatly limits their paleobiological resolution the unique carbonate hosted assemblage of the khatyspyt formation on the olenek uplift of north central siberia promises a much enhanced anatomical and paleo ecological view of these enigmatic organisms avalon type fossils are preserved by authigenic carbonate cementation in intervals of finely laminated nodular limestones khatyspyt type taphonomic window interbedded silicified calcareous mudstones yield diverse carbonaceous compressions occasionally with taphonomic phantoms of avalon type taxa miaohe type taphonomic window styles of moldic preservation do not appear to be taxon selective and therefore cannot alone be responsible for the morphological distinctiveness of ediacaran macrofossils and the profound disparity in the taxonomic composition between fossil assemblages on the other hand the exclusion of avalon type fossils from carbonaceous compressions miaohe type preservational window is a real taphonomic signal that provides an important constraint on the properties of certain ediacaran tissues

yield estimation of the 25 may 2009 north korean nuclear explosion we collect nine vertical component broadband seismograms from the 25 may 2009 north korean nuclear explosion for a regional seismic network in which eight stations also recorded the 9 october 2006 north korean nuclear test comparing the observed waveforms and spectra from the two events we estimate that the amplitudes of the records from the second event are approximately five times those from the first one additionally we use 599 vertical broadband seismograms from 82 regional events recorded on the regional network between december 1995 and may 2009 to calibrate the network lg wave magnitude the calibrated network is used to calculate the lg wave body wave magnitude m b lg 4 53 for the 25 may 2009 north korean nuclear explosion based upon 15 first arrivals from the two north korea nuclear explosions the regional pn velocity in the northeast china north korea region is calculated to be 8 0 km s this result along with the regional geological structures suggests that the north korean test site nkts is located at a relatively stable continental region we thus use a modified fully coupled magnitude yield relation to estimate the explosion yield and the result shows that the yield of the 25 may 2009 north korean nuclear test is approximately 2 35 kt under the minimum burial depth assumption online material epicentral parameters computed m b lg and corrected m b lg for 82 events used in the study

estimating the relative yields of novaya zemlya tests by waveform intercorrelation summary the relative size of 15 underground nuclear explosions at the novaya zemlya test site is determined by applying a relative waveform analysis called intercorrelation to 566 teleseismic short period p waves the waveforms are corrected for the effects of pp interference and yield scaling of the explosion source functions so that signals from different events recorded at the same station can be analytically compared for events within a single test site this procedure accounts for common path and receiver effects relative explosion source strengths in the 0 5 2 0 hz frequency band determined by intercorrelation are consistent with the results of conventional mb analysis absolute yield estimates from both intercorrelation and mb analyses have much greater uncertainty due to unknown baselines the yield estimates for the 15 events range from 36 to 3886 kt assuming that te 0 5 s and that yield scaling relations for the amchitka test site are appropriate for novaya zemlya the pp delay times obtained from intercorrelation of novaya zemlya events are similar to the delay times for amchitka events with equivalent yields consistent with both being hardrock sites the analytical waveform comparisons also provide criteria for identifying anomalous events the novaya zemlya test site has two subsites separated by about 300 km one of the 11 events in the northern subsite and one of the four events in the southern sub site have anomalous waveforms a waveform modelling study indicates that the anomalous southern event was a double explosion northern and southern novaya zemlya have different waveform and amplitude patterns apparently caused by different focusing and defocusing of seismic energy by laterally varying structure near the sources

trace fossils in the ediacaran cambrian transition behavioral diversification ecological turnover and environmental shift abstract after taxonomic revision trace fossils show a similarly explosive diversification in the ediacaran cambrian transition as metazoan body fossils in shallow marine deposits of ediacaran age trace fossils are horizontal simple and rare and display feeding strategies related to exploitation of microbial matgrounds equally notable is the absence of arthropod tracks and sinusoidal nematode trails this situation changed in the early cambrian when a dramatic increase in the diversity of distinct ichnotaxa is associated was followed by the onset of vertical bioturbation and the disappearance of a matground based ecology agronomic revolution on deep sea bottoms animals have been present already in the ediacaran but ichnofaunas were poorly diverse and dominated by the horizontal burrows of undermat miners as shown by the ichnogenus oldhamia this life style continued to be predominant into the early and to a lesser extent middle cambrian nevertheless there was an explosive radiation of behavioral programs during the early cambrian when exactly the bioturbational revolution arrived in the deep sea is uncertain in any case the nereites ichnofacies was firmly established in the early ordovician the rich ichnofauna in the early cambrian guachos formation of northwest argentina probably marks a first step in this ecological onshore offshore shift

the pwaves from the amchitka island explosions summary there is evidence that the equivalent seismic sources of the amchitka island explosions longshot milrow and cannikin depart significantly from the simple model of a point compressional source in a layered elastic medium consequently modelling the observed seismograms using standard source models may not be the most efficient method of determining source properties here an alternative to modelling is used to obtain information on the seismic sources due to the explosions broad band bb estimates of the p signals are obtained from the short period sp seismograms corrected for attenuation and interpreted in terms of p pp and radiation from secondary sources the main conclusions are i bb estimates of the radiated displacement from the explosions can be obtained with only a small reduction in the signal to noise ratio seen on sp seismograms ii observations of differences in pulse amplitudes and spectra are not necessarily due to differences in anelastic attenuation iii p and pp at a given station may differ in shape so that notches in the signal spectrum may not be related to source depth iv there is evidence of arrivals that others have identified as due to slapdown but which could be interpreted as an overshoot to pp v direct interpretation of the estimated ground displacement is a better procedure for determining the seismic source properties of explosions than modelling sp seismograms using idealised models as a starting point

modeling near field and teleseismic observations from the amchitka test site during the amchitka testing program recordings were made of the near field ground velocity for events milrow and cannikin these records exhibited a p arrival a feature associated with near field pp and a developing rayleigh wave in this investigation simple models were found which match the complete seismograms they simultaneously predict the amplitude wave shape timing and periodicity of both the body waves and the surface waves models for both the amchitka crustal structure and the source time functions were developed the crustal model is similar to previous models in its average properties so travel time constraints are still satisfied small modifications have been made to match the waveform data the events on amchitka can apparently be represented as isotropic point sources with the types of simple source time histories predicted by classical yield scaling laws a source model for event longshot was developed on the basis of the yield scaling laws since no near field records are available for it the source models were tested by comparing the teleseismic body waveforms they predict with observations short period p waves long period p waves and long period ps waves were considered the short period p waves provided the best constraint to match them it was necessary both to develop a model for teleseismic pp since it arrives later than the near field model would predict and to estimate the average value of t the milrow and cannikin teleseismic short period p waves indicate that the average effective t for teleseismic ray paths from amchitka is 0 9 s the scatter about this value however is very substantial the accuracy of the scaling laws was tested by comparing synthetics for longshot to teleseismic observations the predicted amplitudes and wave shapes fall within the scatter in the observations though again this scatter is substantial

estimating explosion yield by analytical waveform comparison summary the yields of 28 underground nuclear explosions at nts 25 on pahute mesa are estimated by applying a relative waveform analysis called intercorrelation to 1256 teleseismic short period p waves recorded at 74 wwssn and csn stations corrections for the effects of pp interference and yield scaling of the explosion source functions are determined and applied to the waveforms enabling analytical comparison of signals from events with different yields and burial depths the procedure accounts for common receiver and propagation effects relative explosion source strengths in the 0 5 2 0 hz frequency band are determined with results of near field modelling of strong ground motions establishing the absolute source spectral levels four events with detailed near field models are used as master events in the intercorrelation process and it is demonstrated that the relative source strengths are better resolved than the absolute values events with announced yields are used to determine empirical relations between yield and source strength which in turn predict the yields of the other events these yield estimates are shown to be comparable with those obtained by standard mb and relative amplitude analysis the analytical waveform comparisons also provide estimates of the pp parameters for each event and criteria for identifying anomalous events such as pipkin and muenster for which the waveforms differ from those of other events in the test site possible mechanisms affecting the anomalous events are considered pahute mesa is shown to be a distinct subsite within nts with different teleseismic amplitude and waveform variations than observed at other subsites

eight armed ediacara fossil preserved in contrasting taphonomic windows from china and australia we report the preservation of the eight armed ediacara fossil eoandromeda octobrachiata as carbonaceous compressions in the doushantuo black shale of south china and as casts and molds in the rawnsley quartzite in south australia the contrasting preservational styles in two taphonomic windows indicate that e octobrachiata may have had a relatively recalcitrant organic integument which rules out its close comparison with giant agglutinated foraminifers such as xenophyophores its octaradial symmetry and dextrally spiraling arms suggest that it may be a diploblastic grade animal sharing some features with cnidarians and ctenophores although its phylogenetic affinity remains open it is the first and only unambiguously identified ediacaran macrofossil that occurs in two drastically different taphonomic windows thus bridging the conventional biological and taxonomic gaps between the ediacara and miaohe biotas which collectively record the earliest known macroscopic and complex life

intraspecific variations in carbon isotope and oxygen isotope compositions of a brachiopod basiliola lucida collected off okinawa jima southwestern japan abstract this study presents intraspecific variations in carbon isotope 13 c and oxygen isotope 18 o compositions of nine specimens of a subtropical brachiopod basiliola lucida collected west of okinawa jima ryukyu islands southwestern japan the 13 c values of samples collected along the maximum growth axis ontogenetic samples from two modern and seven older pre 1945 cal ad shells show no seasonal changes the modern shells which were collected from comparable depths have similar 13 c values that fall within the range of calcite precipitated in isotopic equilibrium with ambient seawater equilibrium calcite 13 c ec values and their mean 13 c values are 1 1 1 6 less than those from the older shells this decrease in 13 c values is similar in magnitude to the decreases in atmospheric co 2 and the oceanic dissolved inorganic carbon at the sea surface in recent years 13 c suess effect suggesting that the effect can even be detected at water depths of 200 300 m in the subtropical northwestern pacific ocean the 18 o values fluctuate within a narrow range 0 26 0 41 with no seasonal changes and they exhibit small 0 14 0 51 offsets from those of equilibrium calcite 18 o ec values a statistically significant negative linear relationship is established between seawater temperature and mean 18 o values of the nine shells but the slope 0 31 c is steeper than those of equilibrium calcite 0 23 c and other calcareous organisms 0 15 to 0 26 c the cross plots of the 13 c and 18 o values suggest that the degree of the vital effect varies among individuals in this species the 13 c and 18 o values of b lucida are potentially useful for reconstructing the 13 c and 18 o evolution of ancient oceans because both values show small intraspecific variations the former is identical to the 13 c ec values and the latter shows small within shell variations and small nearly constant offsets from the 18 o ec values

the oldest skeletal macroscopic organism palaeopascichnus linearis abstract the existing problems regarding the phylogenetic resolution of ediacaran macroscopic organisms stem from a failure to factor in the information captured through different taphonomic windows here we integrate the information from sandstone and limestone hosted occurrences of the fossil palaeopascichnus linearis that together show a conspicuously greater range of taxonomic and taphonomic variation the limestone hosted material comes from a new locality discovered on the northwestern slope of the olenek uplift in arctic siberia that characterises the uppermost ediacaran strata of the khatyspyt formation khorbusuonka group detailed taphonomic and morphodynamic studies of the fossil material revealed evidence of possible chamber wall agglutination and growth through addition of new chambers with little sideway growth palaeopascichnus linearis outlived the intra ediacaran 550 myr ago drop in species richness the advent of bilaterians and the increase in complexity of burrowing behaviour in metazoans it remains to be seen whether or not the remarkable ecological success achieved by palaeopascichnus linearis during the times of rich evolutionary experimentation has anything to do with the invention of an agglutinated test palaeopascichnus poses major scientific challenges and it is now clear that such preservation as occurs in siberia may hold the answer to what they were how they lived and what they were related to

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

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

integrated ediacaran sinian chronostratigraphy of south china abstract the ediacaran period was a critical time in the history of life and earth understanding the complex interactions between geological and biological events during this interval requires high resolution chronostratigraphy thanks to its uniquely favorable palaeogeographic setting south china is an ideal region for constructing a framework for global chronostratigraphic correlation of ediacaran strata here continuous ediacaran successions contain both siliciclastic and carbonate rocks that range from shallow to deep marine and contain rich fossil assemblages showing a variety of preservation styles as part of the present study 62 reference sections distributed throughout the yangtze platform were investigated analyses of the sedimentary facies and sequence stratigraphy of more than 40 sections revealed four major sequences in the shallow marine facies three major sequence boundaries occur respectively in the middle and upper parts of the doushantuo formation and in the middle part of the dengying formation subdivision and correlation of the ediacaran successions of the yangtze platform based on sequence stratigraphy is congruent with the carbon isotope chemostratigraphy of 12 reference sections 1075 samples the sequence boundary sb2 in the middle part of the doushantuo formation is suggested here as the lower xiadongian upper yangtzean series boundary of the ediacaran which coincides with several globally recognizable events namely 1 the end of the neoproterozoic glaciations 2 the first appearance of animals 3 the sudden increase in the diversity of acanthomorphic acritarchs and 4 a negative 13 c excursion the ediacaran system of south china may be subdivided into five stages furthermore the criteria for defining these stages may be applicable throughout the world also the composite carbon isotope profile of the ediacaran of south china can be used as a global reference for chronostratigraphic subdivision and correlation in addition to the globally recognizable negative 13 c excursion in the cap carbonate at the base of the ediacaran the negative 13 c excursion in the uppermost doushantuo wonoka shuram interval represents another globally correlatable major excursion the positive 13 c excursion immediately following the uppermost doushantuo excursion and ending at 548 ma is also useful for global correlation current ediacaran chronostratigraphy and global correlations indicate that the upper doushantuo wonoka shuram negative 13 c excursion ranges from ca 560 ma to 551 ma and therefore coincides with the evolutionary renovation of life feedback between evolutionary innovation and geochemical cycling was the key mechanism for this unique and most strongly negative 13 c excursion in earth history our chronostratigraphic correlations also imply that the earliest known metazoan biotas namely the weng an and characteristic ediacaran biotas do not constitute two temporally separate evolutionary lineages as proposed previously but represent two parallel evolutionary pathways preceding the cambrian explosion of animal life

paleoenvironmental analysis of the late neoproterozoic mistaken point and trepassey formations southeastern newfoundland the mistaken point and trepassey formations conception and st john s groups respectively comprise a terminal neoproterozoic deep marine succession of fine grained turbidites and volcanogenic deposits that are part of the avalonian terrane debris flow beds slumped units the low dispersion of turbidity current paleoflow directions and the absence of wave generated structures together indicate that the sediment was deposited on a deep water southeast facing slope channels were not present in the study area the upward increase in the abundance of slump structures suggests that these units represent toe of slope and mid slope environments respectively these units prograded over basin floor deposits of the drook and briscal formations which have axial paleocurrent directions that are orthogonal to the inferred downslope flow that characterized the overlying deposits within the mistaken point and trepassey formations a diverse assemblage of soft bodied non phototrophic ediacaran organisms is

boron isotopic compositions of corals seawater or diagenesis record abstract the first analyses of modern and fossil corals calcite free using a positive ion cs2bo2 tims technique and a chemical procedure for b extraction are reported the 11b for modern corals fluctuates between 23 3 and 25 5 the range of variation of fossil corals from the last interglacial period is greater from 23 5 to 27 3 and the lowest 11b corresponds to the corals close to last glacial maximum boron concentrations show a variation from 49 to 58 ppm in the recent corals and from 39 to 52 ppm in ancient corals for the ancient corals linear correlations are observed in both 11b vs b concentration and 11b vs 1 b plots but these correlations are not observed for modern corals two interpretations are presented to account for these observations and to test the potential of 11b for reconstructing paleo ocean ph the first interpretation assumes a thermodynamic partitioning of b between seawater and carbonates and shows that both boron isotopic compositions and concentrations can be used to calculate the ph of seawater in which corals grow for our data such a model requires that both the ph and the co2 of the deglacial ocean was lower than present day values the second interpretation is based on the correlation observed for ancient corals between boron isotopic compositions and 1 b we suggest that the measured boron isotopic compositions of ancient corals are caused by the mixing of a primary aragonite the coral skeleton and secondary aragonite precipitated from 10b enriched reef pore fluids the characteristics 11b and b concentrations of the diagenetic aragonite and the fluids from which it precipitates can be constrained if this proves correct only the non recrystallised parts of ancient corals can be used for paleo ph reconstructions these recrystallisation processes did not affect the 234u 238u ratios of the corals

application of waveform modeling to determine focal mechanisms of four 1982 miramichi aftershocks the objective of this study is to determine the focal mechanisms of small earthquakes at very near epicentral distances and use them to predict the observed waveforms to achieve our objectives the following steps were adopted before attempting to match the entire waveform a obtain an appropriate velocity model b calculate the green s functions and predict ground motions due to an earthquake specified by dip slip and strike of a fault c select all mechanisms which satisfy the first motion polarity at all stations d select a subset of focal mechanisms from those obtained in step c which produce p and s amplitudes and p sv and sv sh amplitude ratios correctly and e use focal mechanisms of step d to match waveforms as an alternative approach a least squares inversion for the moment tensor elements was performed and decomposition of moment tensor matrix to two double couples major and minor was performed green s functions were computed using the cagniard de hoop theory helmberger and harkrider 1978 we applied the above approaches to four aftershocks mblg 3 5 of the new brunswick earthquake of 9 january 1982 and succeeded in obtaining focal mechanisms and producing synthetic waveforms very similar to the observed waveforms two groups of focal mechanisms are found two of the earthquakes are found to have reverse fault geometry similar to that of the main event of 9 january 1982 mb 5 7 while the other two have significant components of strike slip motion on a dipping plane the results obtained from the least squares analysis support the results of the search method the fault geometries determined by the search method correspond well to the results of the major double couple of the least square inversion for completeness of the source characteristics investigation spectral analysis of the seismograms was performed to determine the source parameters corner frequencies fc seismic moments source dimensions and stress drops

strong motion seismology strong motion seismology is concerned with earthquake ground motion in the amplitude range that poses the threat of human injury or property damage because the occurrence of strong motion cannot be predicted in advance and because the time between significant events at any one place may range from tens to thousands of years strong motion data is recorded on triggered instruments that typically must be maintained in readiness for years between periods of significant recording as a consequence the strong motion data set is sparse because of the engineering need for estimates of future ground motion the scope of the field of strong motion seismology encompasses seismic source theory and any other aspect of seismology that can provide insights helpful in making the best possible estimates given the limited data this relationship with the rest of seismology is a reciprocal one in that strong motion data gives perhaps the best information available on earthquake source processes

a tale of three taphonomic modes the ediacaran fossil flabellophyton preserved in limestone black shale and sandstone abstract ediacaran macrofossils are typically preserved in three taphonomic modes casts molds in siliciclastic rocks casts molds in carbonate rocks and carbonaceous compressions in black shales only a few taxa are known to be preserved in more than one of these taphonomic modes flabellophyton is a genus that has been previously reported from lower ediacaran black shale of the lantian formation 635 551 ma in south china and upper ediacaran sandstone of the ediacara member 560 550 ma in south australia here we report flabellophyton from upper ediacaran limestone of the shibantan member of the dengying formation 551 539 ma in south china making flabellophyton the only genus that occurs in all three taphonomic modes we also provide a systematic description of flabellophyton based on material from the lantian and dengying formations in south china recognizing three morphospecies f lantianense f typicum sp nov and f obesum sp nov flabellophyton is reconstructed as an erect epibenthic marine organism attached to sandy carbonate and muddy substrates its phylogenetic affinity remains ambiguous though it was historically interpreted as an algal fossil the wide environmental and stratigraphic distribution of flabellophyton allow comparative taphonomic and paleoecological analysis taphonomic analysis of flabellophyton indicates that multiple taphonomic pathways can facilitate the preservation of ediacaran macrofossils as a window into ediacaran paleoecology flabellophyton and other ediacaran fossils played a crucial role in the construction of epibenthic communities in ediacaran oceans and helps to understand the ecological migration and evolutionary expansion from deeper to shallower oceans during the ediacaran period

structure of the earth mantle and core the deep interior structure of the earth has been extensively analyzed using a wide variety of seismic phases and techniques during the last four years most studies have emphasized quantitative three dimensional mapping of the lateral velocity heterogeneity of the mantle and core these aspherical velocity variations are believed to be direct manifestations of thermal and compositional heterogeneity associated with convective processes a first generation of global models for the lateral velocity variations in the deep earth has been produced providing tantalizing images of large scale structures suggestive of a non steady state thermal convection system the upper 400 km of the mantle has the strongest lateral velocity variations of up to 10 for shear velocity surface wave analyses that do not require a priori regionalizations have demonstrated that there is a strong association between surface tectonic provinces and the uppermost mantle velocity variations thus the thermal and convective state of the upper 200 km of the mantle can be reliably interpreted in the context of plate tectonics the upper mantle models support the contention that continents have deep roots with differences in velocity structure from oceanic and active tectonic regions extending as deep as 400 km very long wavelength lateral velocity variations of a few percent have been detected in the transition zone at depths from 400 to 670 km as well as throughout the lower mantle these deep seated variations have little correspondence to surface tectonics and efforts to interpret their nature are just beginning the lowermost 200 km of the mantle d region has lateral velocity fluctuations comparable to those in the upper mantle and evidence has been presented for the presence of a sizable velocity discontinuity at the top of the d layer a combined thermal and compositional boundary layer roughly mirroring the lithosphere is a likely explanation for this anomalous zone the core mantle boundary appears to have significant 10 km long wavelength topography presumably sustained by dynamic stresses from deep mantle convection the inner core may have strong lateral heterogeneity or axially symmetric anisotropy suggesting a complex thermal and compositional state significant progress has been made in characterizing the frequency dependence of anelastic attenuation in the mantle in the short period body wave band models for teleseismic p wave attenuation operators have converged with t values of 0 7 1 0 s appropriate at 1 hz and t values of 0 4 0 6 s appropriate at 4 hz regional variations of attenuation are slowly being mapped out as well

silicified horodyskia and palaeopascichnus from upper ediacaran cherts in south china tentative phylogenetic interpretation and implications for evolutionary stasis horodyskia is one of the earliest known macroscopic life forms with a fossil record dating from c 1 4 ga palaeopascichnus represents a key ediacaran element with world wide distribution however their body constructions and affinities are poorly understood partly because previously described species are mostly preserved as casts and moulds in siliciclastic rocks silicified specimens from the upper ediacaran liuchapo formation in eastern guizhou south china are described as horodyskia minor sp nov and palaeopascichnus jiumenensis sp nov their taxonomic assignments are based on their uniserial arrangement of spheroidal or discoidal units which are connected by a filament and surrounded by a quartz halo they are unlikely to be brown algae animal traces faecal pellets colonial metazoans or giant sulphide oxidizing bacteria instead we propose that horodyskia and palaeopascichnus may be phylogenetically related and their collective morphologies allow tentative comparison with agglutinated foraminifers the segments can be compared with cytoplasm filled chambers connecting filament with small passage between chambers and quartz haloes with agglutinated tests however their ontogeny appears to be distinct from that of modern foraminifers the occurrences of horodyskia fossils in mesoproterozoic and ediacaran rocks indicate an extremely long range c 900 ma and echoes the proposition of extended evolutionary stasis in the proterozoic

a reassessment of the problematic ediacaran genus orbisiana sokolov 1976 abstract the genus orbisiana was established in 1976 by b s sokolov based on a collection of seven specimens within core material from a borehole drilled through the ediacaran age gavrilov yam formation of the moscow basin russia here we reassess the original material for the type species orbisiana simplex sokolov 1976 which was long considered to be lost fix the holotype of the type species and revise the original diagnosis of the genus and species pyritisation of the fossils which are preserved in finely laminated shales allows three dimensional morphological characterisation of this taxon using x ray microtomography ct morphological and taphonomic analyses of the type material and additional three dimensionally preserved specimens from the verkhovka formation vendian of the white sea area suggest that orbisiana simplex consisted of submillimetric to millimetric globular chambers arranged in compact grape like clusters or forming sinuous to linear aggregates occasionally aggregates can bifurcate with no appreciable change in chamber dimensions or shape the phylogenetic affinity of orbisiana remains uncertain but its chambered construction putative agglutinated structure of the chamber walls and compact occasionally branching chamber arrangement are shared with agglutinated tests of the ediacaran genus palaeopascichnus our reassessment and systematic study of the genus orbisiana sheds new light on one of the least studied members of the late ediacaran macroscopic biota

changes in ph in the eastern equatorial pacific across stage 5 6 boundary based on boron isotopes in foraminifera estimates of paleo ph for the eastern equatorial pacific ocean across the oxygen isotopic stage 5 6 boundary have been made based on the boron isotopic composition of planktonic orbulina universa and benthic mixed species foraminifera from core v19 28 the estimated deep ocean ph during the penultimate glacial period was about 0 3 0 1 ph units higher compared to the modern deep ocean this is consistent with previously estimated deep ocean ph changes across the stage l 2 boundary in the western equatorial pacific and tropical atlantic thus arguing against the possibility that the benthic foraminifera analyzed to estimate deep ocean ph changes have been significantly affected by anomalous local environment and or diagenesis the estimated changes in the deep ocean carbonate chemistry require a decoupling of several kilometers between the saturation horizon and the lysocline during the glacial periods though such a decoupling could be achieved by enhanced respiration co2 driven calcite dissolution in sediments during glacial periods it lacks support from the calcite sedimentary records the boron isotopic compositions of planktonic foraminifera on the other hand indicate no significant ph change in the eastern equatorial pacific surface ocean during the glacial interglacial transition this is inconsistent with an expected higher surface ocean ph during the glacial period due to lower atmospheric pco2 and is also in contrast with the previously estimated boron isotope based glacial interglacial ph change of 0 2 0 1 ph units in the western equatorial pacific and tropical atlantic the lack of change in eastern equatorial pacific surface ocean ph between glacial interglacial periods could be attributed to less nutrient utilization efficiency and or enhanced calcite production during glacial periods such a decrease in nutrient utilization efficiency and or increase in calcite production would lead to a greater disequilibrium between the pco2 of eastern equatorial pacific surface ocean and that of the atmosphere making this part of the ocean a greater source of co2 to the atmosphere during glacial periods compared to today

depth estimate of the dprk s 2006 10 09 2009 05 25 and 2013 02 12 underground nuclear tests using local and teleseismic arrays abstract the democratic people s republic of korea dprk aka north korea conducted underground nuclear explosions on october 9 2006 m 4 3 may 25 2009 m 4 7 and february 12 2013 m 5 1 we expanded standard depth calculation methods to encompass full depth utilizing spectral nulls of spectra using body waves and rayleigh waves from local and teleseismic arrays the depths of burial were calculated from the fundamental mode rayleigh wave spectra as well as the average spectra of depth phase pp p sp p ppn pn spn pn considering take off angles based on the flat earth model the average depths of the 2006 2009 and 2013 nuclear tests were thus estimated at 2 12 km 2 06 km and 2 05 km respectively it should be noted that those depths are significantly greater than expected from the standard experiment practice the possibility of the over buried nuclear tests would affect the interpretation of ms mb discriminants as well as the estimation of the yield

an explanation of the effect of seawater carbonate concentration on foraminiferal oxygen isotopes abstract stable oxygen isotope ratios of foraminiferal calcite are widely used in paleoceanography to provide a chronology of temperature changes during ocean history it was recently demonstrated that the stable oxygen isotope ratios in planktonic foraminifera are affected by changes of the seawater chemistry carbonate system the 18 o of the foraminiferal calcite decreases with increasing co 3 2 concentration or p h this paper provides a simple explanation for seawater chemistry dependent stable oxygen isotope variations in the planktonic foraminifera orbulina universa which is derived from oxygen isotope partitioning during inorganic precipitation the oxygen isotope fractionation between water and the dissolved carbonate species s h 2 co 3 hco 3 co 3 2 decreases with increasing p h provided that calcium carbonate is formed from a mixture of the carbonate species in proportion to their relative contribution to s the oxygen isotopic composition of caco 3 also decreases with increasing p h the slope of shell 18 o vs co 3 2 of orbulina universa observed in culture experiments is 0 0022 mol kg 1 1 spero et al 1997 whereas the slope derived from inorganic precipitation is 0 0024 mol kg 1 the theory also provides an explanation of the nonequilibrium fractionation effects in synthetic carbonates described by kim and o neil 1997 which can be understood in terms of equilibrium fractionation at different p h the results presented here emphasize that the oxygen isotope fractionation between calcium carbonate and water does not only depend on the temperature but also on the p h of the solution from which it is formed

correlation of boron isotopic composition with ultrastructure in the deep sea coral lophelia pertusa implications for biomineralization and paleo ph using the crpg cnrs cameca 1270 ion microprobe facility we have measured boron isotopic compositions b 11 b 10 in different ultrastructural components of the deep sea aragonitic scleractinian coral lophelia pertusa we observe a systematic difference in b isotopic composition between the early mineralization zone emz and adjacent fibrous skeleton in emz the measured delta 11 b values are consistently low fibrous aragonite is characterized by systematically higher delta 11 b values but also displays b isotopic heterogeneity associated with specific growth bands in the calyx wall the magnitude of the observed b isotopic variations cannot be explained by changes in environmental conditions and is likely caused by biological processes involved in the biomineralization of new skeleton i e vital effects the observed b isotopic variations are opposite to the predictions of geochemical models for vital effects these models are based on the idea that stable isotopic fractionations including c and o in coral skeleton are driven by changes in ph of the fluid from which the skeleton is presumed to precipitate our data indicate that ph variations are not responsible for the observed stable isotopic fractionations geochemical models therefore do not provide an adequate framework within which to understand coral skeletal formation without a better understanding of these processes the use of b isotopic composition to reconstruct paleo ph variations in the oceans must be considered problematic at least as far as lophelia pertusa is concerned