morphological disparity of ammonoids and the mark of permian mass extinctions the taxonomic diversity of ammonoids in terms of the number of taxa preserved provides an incomplete picture of the extinction pattern during the permian because of a strongly biased fossil record the analysis of morphological disparity the variety of shell shapes is a powerful complementary tool for testing hypotheses about the selectivity of extinction and permits the recognition of three distinct patterns first a trend of decreasing disparity ranging for about 30 million years led to a minimum disparity immediately before the permian triassic boundary second the strongly selective capitanian crisis fits a model of background extinction driven by standard environmental changes third the end permian mass extinction operated as a random nonselective sorting of morphologies which is consistent with a catastrophic cause

origination and extinction through the phanerozoic a new approach abstract temporal patterns of origination and extinction are essential components of many paleontological studies but it has been difficult to obtain accurate rate estimates because the observed record of first and last appearances is distorted by the incompleteness of the fossil record here i analyze observed first and last appearances of marine animal and microfossil genera in a way that explicitly takes incompleteness and its variation into consideration this approach allows estimates of true rates of origination and extinction throughout the phanerozoic substantial support is provided for the proposition that most rate peaks in the raw data are real in the sense that they do not arise as a consequence of temporal variability in the overall quality of the fossil record even though the existence of rate anomalies is supported their timing is nevertheless open to question in many cases if one assumes that rates of origination and extinction are constant through a given stratigraphic interval then

transient metazoan reefs in the aftermath of the end permian mass extinction microbes were thought to be the dominant reef constructors following the end permian mass extinction sponge microbe reef deposits formed in the early triassic from the western united states suggest that instead metazoan reef building continued immediately following the extinction wherever marine conditions allowed

ammonoid recovery after the permian triassic mass extinction a re exploration of morphological and phylogenetic diversity patterns the explosive ammonoid rediversification after the permian triassic mass extinction is now well understood in terms of taxonomic richness and biogeography using an updated dataset of early triassic ammonoids we compare morphological disparity and taxonomic richness patterns at the regional and global scales disparity evolved similarly at both scales suggesting a global influence of abiotic factors morphological diversification occurred early in the smithian and a marked contraction of the morphospace took place during the end smithian extinction we confirm that trends in disparity and richness were decoupled during the griesbachian and dienerian three macroevolutionary processes may be involved 1 a nonselective extinction at the permian triassic boundary 2 a dienerian constrained radiation with several homeomorphic genera 3 a potential deterministic extinction during the end smithian crisis we also demonstrate a superfamily imprint upon disparity for the spathian when most superfamilies occupied a restricted part of the morphospace sphaerocones were the most affected by the dienerian and end smithian extinction but explanations remain elusive on the one hand this may be linked to widespread harsh conditions at those times on the other hand as the sphaerocones occurred episodically during the early triassic this might be explained by a relaxing of ecological constraints or simply by convergent evolution supplementary materials the database including measurements of specimens illustrated in previously published plates and of unpublished specimens from utah south china and spiti as well as the number of genera present in each studied substage of the early triassic are available at www geolsoc org uk sup18571

timing of the early triassic carbon cycle perturbations inferred from new u pb ages and ammonoid biochronozones based on analyses of single thermally annealed and chemically abraded zircons a new high precision u pb age of 251 22 0 20 ma is established for a volcanic ash layer within the kashmirites densistriatus beds of early smithian age early triassic from the luolou formation northwestern guangxi south china this new date together with recalculated uncertainties of previous u pb ages from the same section m ovtcharova h bucher u schaltegger t galfetti a brayard j guex new early to middle triassic u pb ages from south china calibration with ammonoid biochronozones and implications for the timing of the triassic biotic recovery earth planet sci lett 243 2006 463 475 allows constraining the time framework of the early triassic and leads to an estimated duration of i ca 0 7 0 6 my for the smithian and ii a maximal duration of ca 1 4 0 4 my for the griesbachian dienerian time interval the new u pb age considerably reduces the absolute age gap comprised between the permian triassic boundary and the spathian late early triassic the new age framework provides the basis for the calibration of a new carbonate carbon isotope and ammonoid records of the early triassic luolou fm which in turn are of high significance for global correlations and for carbon cycle modeling this calibration indicates that the most significant and fastest early triassic carbon isotope perturbations occur between the earliest smithian and the early spathian thus spanning a time interval of about 1 my whatever caused these carbon cycle shifts of high intensity and short duration there is evidence for connections between these fluctuations the pulsate recovery of ammonoids and conodonts as well as climate changes

relative sea levels of japan from tide gauge records we attempted to separate tectonic ocean ographic and eustatic components of change in relative sea levels derived from the many tide gauge records of japan acquired during the past 50 yr a modified eigenanalysis permitted use of station data of unequal lengths regression analysis and eigenanalysis revealed systematic spatial differences in relative sea level rise of 25 mm yr although the difference is too great to be solely eustatic in origin data are insufficient to permit accurate separation of tectonic and eustatic effects on relative sea levels the low frequency patterns periods longer than 50 yr may have been derived from subduction of the pacific and philippine plates beneath japan higher frequencies 12 6 and 2 yr periods are correlated with oceanographic factors such as shifts in the position of the kuroshio and the el nino southern oscillation the contours of relative change in sea levels provide convincing evidence that neither a single nor several japanese tide gauges can be selected to authentically demote present or past eustatic sea level rise

monthly mean sea levels in greece during 1969 1983 compared to relative vertical land movements measured over different timescales sea level data from 16 tide gauge stations in greece have been used in an analysis of the seasonal cycle of mean sea level in greek waters together with an investigation of the interannual variability of sea level in the region for the period 1969 1983 the recorded seasonal cycle is found to vary considerably across the area and to agree well with sea level observations from neighbouring coastlines the greek data result in knowledge of the mean sea level seasonal cycle being now available from throughout the northeastern mediterranean an overall drop of sea levels is observed during the mid 1970 s while the larger peaks and dips in the records are found to be coherent over the whole area and on several occasions to be general to the entire northern mediterranean the tide gauge data set has also provided measurements of the secular trends in relative mean sea levels over the same 15 year period a wide geographical variation of sea level trends is observed spanning a range from 21 to 11 mm yr measured relative to sea levels at katakolon after inversion these measurements provide estimates of relative vertical land movements of the present epoch which can be compared to those obtained from archaeological and geological sources i e changes over timescales of thousands tens of thousands and tens of millions of years differences in the sign and magnitude of the relative vertical land movements of this geologically complicated region obtained from the different data sets are discussed in detail it is shown that the direction of vertical movement recorded by the tide gauges correlates well with that observed over longer periods and that with relatively few exceptions sites which are uplifting submerging relatively rapidly over one timescale are uplifting submerging relatively rapidly at all timescales while the rate of vertical movement throughout the aegean and southern greece usually preserves the same sign at a given site over timescales of 101 107 yrs its magnitude decreases approximately by a factor 1t 0 4 where t is the measurement averaging period

relative sea level changes from tide gauge records of eastern asia mainland records from 22 tide gauge stations along the mainland coast of eastern asia document low frequency vertical movements of the land perhaps biased by unevaluated changes of sea level the land is rising relative to sea level as much as 5 mm yr 1 in the areas of massifs and ancient foldbelts and subsiding as much as 9 mm yr 1 in areas of cenozoic basins and foldbelts although the tide gauge records are sparse inferences from them are supported by the stratigraphy and structure of the region and by raised and submerged sea level terraces thus relative changes of sea level are heavily influenced here by tectonic and isostatic as well as eustatic factors just as in japan scandinavia and north america where tide gauge records are much more abundant higher frequency 2 25 yr periods sea level fluctuations show broad peaks between 2 and 4 yrs and near 10 yrs some of these fluctuations correlate with behavior of the kuroshio current which along with freshwater inflow dominates the hydrography of the eastern asian continental shelves observations of water mass fluctuations are too sparse to identify direct causes of all high frequency variability

thermal constraints on the seismogenic portion of the southwestern japan subduction thrust for coastal cities an important factor in earthquake hazard from subduction zone earthquakes is the landward extent of the seismogenic portion of the subduction thrust fault in this study we test the hypothesis that the maximum downdip extent is defined by a critical temperature we have developed a transient thermal model for the nankai subduction zone of southwest japan to allow comparison of the thermally estimated downdip extent of the seismogenic zone with that from 1 seismicity and tsunami data for two great subduction earthquakes 2 the coseismic faulting extent of these events estimated from geodetic deformation data and 3 the interseismic locked zone determined from interseismic geodetic data the nankai margin has extensive heat flow and heat production data to control thermal models and thus crustal temperatures it has earthquake tsunami and geodetic data that constrain the coseismic rupture portion of the subduction thrust fault for past great earthquakes and the portion of the thrust fault that is locked and storing interseismic elastic strain on the nankaido margin off shikoku island the thermal model indicates that a temperature of 350 c taken to be the limit for seismic initiation from laboratory and field data is reached on the subduction thrust fault 150 km from the trench a transition zone into which rupture may extend with decreasing offset taken to be 450 c extends an additional 45 km downdip the thermal model results are in excellent agreement with the maximum downdip extent of coseismic displacement for the 1946 nankaido ms 8 2 earthquake off shikoku island and with the downdip extent of the present locked zone in the region of the 1944 tonankai ms 8 2 earthquake to the northeast the subduction angle is much steeper and the thermal models indicate a narrower downdip seismogenic extent the seismogenic locked zone from earthquake and geodetic data is also narrower thus our analysis of the southwest japan margin indicates that all three constraints on the downdip extent of the seismogenic zone thermal coseismic and interseismic geodetic data are in general agreement the study also supports the hypothesis that the seismogenic portion of subduction thrust faults is limited primarily by temperature the thermal control implies that subduction thrust faults with shallow dip have wider seismogenic zones compared to those with steep dip the subducting plate age and thus heat flow and the thickness of the insulating sediments on the incoming plate are also very important to the thermal regime and thus to the seismogenic width the relation of the maximum seismic rupture area to the interseismic locked zone is particularly important for earthquake hazard estimation on subduction margins such as cascadia where there have been no great historical events

the early triassic ammonoid recovery paleoclimatic significance of diversity gradients ammonoids recovered much faster than other marine shelly invertebrates after the end permian mass extinction based on a refined global data set at the basin level we investigate the paleobiogeographical global latitudinal and longitudinal diversity patterns in terms of climatic changes during the early triassic such analysis differs from already published qualitative or quantitative studies in that it estimates faunal patterns and endemicity at an ecologically meaningful level of spatial resolution i e at the basin level during the early triassic the global first order trend in increasing ammonoid diversity was accompanied by a progressive change from cosmopolitan to latitudinally restricted distributions this led to the emergence of a clear latitudinal diversity gradient during most of the smithian and spathian stages which entails increased steepness of the sea surface temperature gradient during the late early triassic however two brief episodes of ammonoid cosmopolitanism combined with low global diversity interrupted the first order increasing trend at the very beginning of the smithian and at its very end the longitudinal analysis of smithian distributions indicates a westward decrease of diversity within the tethys which faded away during the spathian analysis of endemicity indicates a rapid biogeographical maturing and structuring of faunas concomitant with the edification of the latitudinal diversity gradient

recovery tempo and pattern of marine ecosystems after the end permian mass extinction high resolution sampling of more than 10 000 microfossils from seven late permian middle triassic paleoequatorial sections in south china refutes claims for a 5 m y recovery delay after the end permian mass extinction we show that level bottom seafloor diversity began to recover in the early smithian little more than 1 m y after the mass extinction while recovery of reef building metazoans began 4 m y later in the anisian a further mass extinction in the late smithian identified in the pelagic fossil record is weakly manifest as a temporary pause in diversification among benthic communities in the early triassic of south china the offshore diversity increase began before then in shallower settings the recovery from the end permian mass extinction in south china was therefore significantly more rapid and environmentally more complex than hitherto known

ammonite shell shape covaries with facies and hydrodynamics iterative evolution as a response to changes in basinal environment shell shape varies within many ammonoid species and some ammonoid lineages appear to have evolved in concert with changes in their environment we report variation within an upper cretaceous ammonoid species that correlates with facies differences and is consistent with a hydrodynamic explanation in the turner sandy member of the carlile shale turonian of south dakota and wyoming more compressed morphs of scaphites whitfieldi cobban are found in nearshore sandy facies whereas more depressed morphs occur in offshore muds we measured drag forces on models of juvenile and adult shells that differed in lateral compression of the shell plots of drag coefficient as a function of reynolds number indicate that thinner more compressed morphs swam more efficiently at higher velocities and depressed morphs swam more efficiently at low velocities higher swimming velocities may be essential for life in nearshore sandy environments which have higher ambient current velocities shelled cephalopods swim most efficiently at low swimming speeds therefore lower velocity more energetically economical swimming should be preferred in more quiescent offshore settings an analysis of power consumption supports this interpretation correlated changes in shell compression and environmental factors here observed within a species have been documented in numerous ammonite lineages these iterative evolutionary changes within lineages may be similarly explained by selection for shell morphologies appropriate to environments that fluctuate cyclically with sea level

conodont diversity and evolution through the latest permian and early triassic upheavals abstract a study of latest permian and early triassic multielement conodonts identifies eight steps in their evolutionary history during an interval when earth s biosphere was highly stressed these steps are 1 gradual decline of families and genera through the changhsingian up to the late griesbachian 2 conodont biofacies change and extinction of tethyan endemic species close to the permian triassic boundary ptb 3 faunal turnover with extinction and origination in the late griesbachian 4 initial radiation in gondolellids and diversification in apparatuses during the dienerian 5 explosive radiation in the early middle smithian 6 major extinction in the late smithian 7 major radiation early in the spathian 8 gradual turnover and decline in the late spathian through early anisian conodontophorids were reduced from five families at the beginning of the changhsingian to three by the ptb and to two late in the griesbachian from the changhsingian to the late griesbachian there was a single multielement apparatus represented in the gondolellidae whereas by the olenekian there were at least twelve given absolute age constraints the conodont recovery in the aftermath of the ptb was extraordinary conodont evolution during the dienerian remains obscure but was very significant in terms of changes in multielement apparatuses in spite of induan extinctions generic diversity generally increased from the ptb up to the late smithian in terms of species genera and multielement apparatuses the acme of triassic conodonts was in the middle smithian and the biggest extinction was in the late smithian after this extinction generic and apparatus diversity quickly returned to high levels marking a significant spathian recovery gradual decline characterized the late spathian and persisted into the early anisian a synthetic summary of the temporal distribution and proposed relationships amongst all known lower triassic conodonts provide an improved foundation for biostratigraphic and biochronologic studies extinction and radiation trends correlate well with sea level changes and sequence boundaries faunal turnovers correspond to lowstands in the late griesbachian late smithian and late spathian and radiations correspond to transgressions in the early griesbachian early smithian and early spathian the trends also correlate with perturbations in the carbon cycle with lower triassic 13c minima corresponding to extinction and faunal turnover and positive values generally occurring during radiations however middle triassic recovery of marine benthos follows a positive maxima and an overall decline in conodont diversity new taxa borinella chowadensis b megacuspa neogondolella griesbachensis and n mongeri are described

the recovery and radiation of early jurassic ammonoids morphologic versus palaeobiogeographical patterns abstract the recovery and radiation of the early jurassic ammonoid morphospace as represented by nine morphologic groups identified in an earlier study are traced through the first 36 subzones of the hettangian to domerian time interval a quantitative survey of the dispersion of 436 species over 15 palaeogeographical areas reveals seven palaeobiogeographical patterns each corresponding to an exclusive set of species exhibiting similar characteristics in terms of distribution and abundance this study combines morphologic chronostratigraphical and palaeobiogeographical data in an attempt to investigate possible connections between morphologic recovery and radiation patterns and the history of ammonoid distribution on a global scale two out of nine morphologic groups are found to be prevalent in a single palaeobiogeographical pattern through the major part of the studied time interval and a single morphologic group prevails in all the marine areas considered during domerian times all the other relationships identified are less tightly constrained in space and time and indicate loose ties over more limited periods and narrower distributions the present results suggest that such complex relationships can be deciphered more successfully by using analytical palaeobiogeographical patterns as proposed here rather than classical palaeobiogeographical units biochores

smithian and spathian early triassic ammonoid assemblages from terranes paleoceanographic and paleogeographic implications early triassic paleobiogeography is characterised by the stable supercontinental assembly of pangea however at that time several terranes such as the south kitakami massif sk south primorye sp and chulitna respectively and presently located in japan eastern russia and alaska straddled the vast oceans surrounding pangea by means of quantitative biogeographical methods including cluster analysis non metric multidimensional scaling and bootstrapped spanning network applied to smithian and spathian early triassic ammonoid assemblages we analyze similarity relationships between faunas and suggest paleopositions for the above cited terranes taxonomic similarities between faunas indicate that primary drivers of the ammonoid distribution were sea surface temperature and currents possible connections due to current controlled faunal exchanges between both sides of the panthalassa are shown and terranes such as sk sp and chulitna played an important role as stepping stones in the dispersal of ammonoids sk and sp terranes show strong sub equatorial affinities during the smithian thus suggesting a location close to south china at the same time the chulitna terrane shows strong affinities with equatorial faunas of the eastern panthalassa this paleoceanographic pattern was markedly altered during the spathian possibly indicating significant modifications of oceanic circulation at that time as illustrated by the development of a marked intertropical faunal belt across tethys and panthalassa

age and timing of the permian mass extinctions u pb dating of closed system zircons the age and timing of the permian triassic mass extinction have been difficult to determine because zircon populations from the type sections are typically affected by pervasive lead loss and contamination by indistinguishable older xenocrysts zircons from nine ash beds within the shangsi and meishan sections china pretreated by annealing followed by partial attack with hydrofluoric acid result in suites of consistent and concordant uranium lead u pb ages eliminating the effects of lead loss the u pb age of the main pulse of the extinction is 252 6 0 2 million years synchronous with the siberian flood volcanism and it occurred within the quoted uncertainty

relative sea level change from tide gauge records of western north america negligible success of investigators in relating tide gauge records of the west coast of north america to eustatic changes of sea level is the result of tectonic movements of the land reference level beneath the tide gauges the vertical tectonic movements are caused by horizontal movements of oceanic crustal plates sinking of 12 mm yr at cordova alaska is associated with intense subduction at the east end of the aleutian trench rising by 6 mm yr at skagway may be caused by resistance to lateral crustal movement toward the filled trench rising of 1 mm yr in southern alaska uplift above slow subduction little vertical movement between sitka and mendocino fracture zone translation and slow subduction including fracture zones and thick sediments sinking of 1 mm yr west of the san andreas fault translation and sinking of 2 mm yr along northwestern mexico effects of cooling of late rifted crust and only diagonal subduction superimposed on this tectonism due to plate motion is broad scale isostatic adjustment both rise and fall resulting from deglaciation removal of rigid plate motion deltas helps resolve subplate tectonic processes higher frequency 0 05 0 5 cpy sea level changes as well as large scale pressure fluctuations and wind stress events are associated with el nino southern oscillation an apparent increase in relative sea level rise near 1935 also observed in other regions remains to be explained

coastal neo tectonics of the mediterranean from tide gauge records abstract records from tide gauges in israel and egypt supplement the many geological and archeological investigations that have contributed information about relative sea level changes in the mediterranean region seven such records reveal changes during the past few decades that accord with prior inferences about land movements in this region emergence along the coast of israel and at alexandria and subsidence at the nile delta and the head of the gulf of suez twenty four other tide gauge records for the rest of the mediterranean region indicate more uniformity submergence of land or rise of sea level in the west but with greater movements of the land attributed to probable plate underthrusting in turkey and greece to volcanism near mount etna to deltaic compaction at izmir and to deltaic compaction coupled with water pumping at the po delta

new trace fossil evidence for an early recovery signal in the aftermath of the end permian mass extinction abstract new ichnological data from the lower triassic werfen formation dolomites italy revealed an unexpectedly diverse and complex ichnofauna in mixed siliclastic carbonate shelf sediments of the western tropical tethys shortly after the end permian mass extinction event common elements are thalassinoides palaeophycus and planolites other associated ichnogenera include spongeliomorpha rhizocorallium lockeia catenichnus helminthopsis and taenidium one structure is tentatively determined as curvolithus biostratigraphic data conodonts and bivalves of the trace fossil interval lower seis siusi member suggest a late griesbachian age less than 1 ma after the end permian mass extinction event similarly diverse ichnofossil communities from this time interval have recently been described from the boreal realm but this is the first record of a diverse griesbachian ichnoassemblage from the tropics indicating that the early recovery of trace fossil producers was not latitudinally restricted as previously proposed accordingly relatively advanced recovery stages were reached on a global scale much earlier than the spathian as is commonly acknowledged the early and interregional peak in ichnofaunal recovery implies subsequent ecological setbacks in post griesbachian times that explain the overall delay of benthic recovery until the spathian rather than persistent catastrophic conditions during the griesbachian a global and synchronous succession of crises and relaxation phases after the griesbachian is proposed as an explanatory model for the recovery pattern of benthic ecosystems

seismicity patterns their statistical significance and physical meaning introduction seismicity patterns their statistical significance and physical meaning rethinking earthquake prediction is earthquake seismology a hard quantitative science how can one test the seismic gap hypothesis the case of repeated ruptures in the aleutians evolving towards a critical point a review of accelerating seismic moment energy release prior to large and great earthquakes seismic cycles and the evolution of stress correlation in cellular automaton models of finite fault networks detailed distribution of accelerating foreshocks before a m 5 1 earthquake in japan foreshock occurrence rates before large earthquakes worldwide time distribution of immediate foreshocks obtained by a stacking method pattern characteristics of foreshock sequences precursory activation of seismicity in advance of the kobe 1995 m 7 2 earthquake the variation of stresses due to aseismic sliding and its effect on seismic activity precursory seismic quiescence before the 1994 kurile earthquake mw 8 3 revealed by three independent seismic catalogs seismicity analysis through point process modeling a review representation and analysis of the earthquake size distribution a historical review and some new approaches universality of the seismic moment frequency relation physical basis for statistical patterns in complex earthquake populations models predictions and tests use of statistical models to analyze periodic seismicity observed for clusters in the kanto region central japan pore creation due to fault slip in a fluid permeated fault zone and its effect on seismicity generation mechanism of earthquake swarm coupled stress release model for time dependent seismicity recognition of a locked state in plate subduction from microearthquake seismicity seasonality of great earthquake occurrence at the northwestern margin of the philippine sea plate eruptions of pavlof volcano alaska and their possible modulation by ocean load and tectonic stresses re evaluation of the hypothesis based on new data from 1984 1998 seismicity patterns are they always related to natural causes

smithian spathian boundary event evidence for global climatic change in the wake of the end permian biotic crisis one of the most important carbon cycle perturbations following the end permian mass extinction event straddles the smithian spathian boundary ssb olenekian early triassic this anomaly is characterized by a prominent positive carbon isotope excursion known from tethyan marine rocks its global signifi cance is established here by a new high paleolatitude record spitsbergen paleontological evidence such as boreal palynological data barents sea norway and global patterns of ammonoid distribution indicates a synchronous major change in terrestrial and marine ecosystems near the ssb the reestablishment of highly diverse plant ecosystems including the rise of woody gymnosperms and decline of the formerly dominating lycopods is interpreted as an effect of a major climate change this hypothesis is supported by modeling of ammonoid paleobiogeography the distribution patterns of which are interpreted as a proxy for sea surface temperatures sst the latest smithian thus appears to have been a time of a warm and equable climate as expressed by an almost fl at pole to equator sst gradient in contrast the steep spathian sst gradient suggests latitudinally differentiated climatic conditions we propose that this drastic climate change and the global carbon cycle perturbation were triggered by a massive end smithian co2 injection the ssb event could therefore represent one of the causes for stepwise and delayed recovery of marine and terrestrial biotas in the wake of the end permian biotic crisis

changing coastal levels of south america and the caribbean region from tide gauge records abstract tide gauge records from southern mexico the caribbean islands and central and south america that span the interval 1940 1970 reveal long term changes of relative sea level according to regression analysis and eigenanalysis the results indicate such large variations in both direction and rate of secular movement as to rule out changes in volume of ocean water as being more than a subordinate factor the only satisfactory explanation is that the land level beneath the tide gauges is rising in some places and sinking in others complex spatial patterns of relative seal level change in southern mexico and the caribbean mirror the tectonic regime of these regions exhibiting both submergence and emergence of the land central american tide gauge records similarly show considerable complexity responding to relative movement along plate boundaries the pacific coast of south america appears to correlate with the depth of the benioff zone subduction of aseismic ridges produces local highs in the benioff zone flanked by troughs at either side near the benioff highs relative land level is rising between these ridges relative land level is falling sea level trends in southern and atlantic coasts of south america are closely linked with continental crustal rifting and subsidence data do not allow unambiguous separation of changes in ocean level from changes in land level and no simple eustatic ocean level change can be estimated accurately from these data

principal component analysis of geodetically measured deformation in long valley caldera eastern california 1983 1987 typical geodetic measurements of deformation consist of repeated surveys of a particular geodetic network such deformation data can be interpreted as a consequence of one or more self coherent sources by means of principal component analysis a self coherent source is defined as any source that produces deformation that is time and space separable principal component analysis then gives the time and space factors that characterize the deformation attributed to each self coherent source geodetic measurements of deformation at long valley caldera provide two examples of the application of principal component analysis a 40 line trilateration network surrounding the caldera was surveyed in midsummer 1983 1984 1985 1986 and 1987 principal component analysis indicates that the observed deformation can be represented by a single coherent source the time dependence for that source displays a rapid rate of deformation in 1983 1984 followed by less rapid but uniform rate in the 1984 1987 interval the spatial factor seems consistent with expansion of a magma chamber beneath the caldera plus some shallow right lateral slip on a vertical fault in the south moat of the caldera an independent principal component analysis of the 1982 1983 1984 1985 1986 and 1987 leveling across the caldera requires two self coherent sources to explain the deformation the deformation pattern produced by the larger of these two sources appears to be roughly consistent with that found from the trilateration data the deformation due to the second source is a nearly uniform tilt in the uplift profile presumably that tilt is simply an artifact of systematic error in the leveling

new estimates of secular sea level rise from tide gauge data and gia modelling summary during the last three decades at least 30 independent estimates of the secular global mean sea level rise gmslr have been published based on sufficiently long tide gauge tg records despite its apparent simplicity the problem of gmslr is fraught with a number of difficulties which make it one of the most challenging questions of climate change science not surprisingly published estimates show considerable scatter with rates ranging between 1 and 2 mm yr 1 for observations on the century timescale in previous work the importance of glacial isostatic adjustment gia upon the assessment of the gmslr has been clearly demonstrated in particular starting from the 1980s gia models have been routinely employed to decontaminate tg observations from the effects of melting of the late pleistocene ice sheets to fully highlight the sea level variations driven by climate change however uncertainties associated with the earth s rheological profile and the time history of the past continental ice sheets can propagate into the gia corrections after revisiting previous work and estimates we suggest a significant modification of the criteria for the selection of the tgs which are most suitable for the robust assessment of the secular gmslr in particular we seek a set of tgs for which gia corrections are essentially independent of the parametrization of the rheological profile of the earth s mantle and of the detailed time chronology of surface loading this insensitivity is established by considering predictions based upon three gia models widely employed in the recent literature namely ice 3g ice 5g and the one developed at the research school of earth sciences of the national australian university applying this approach and selection criteria previously proposed in the literature we identify a set of 22 sufficiently evenly distributed tgs by simple statistical methods these records yield a preferred gia independent gmslr estimate since 1880 namely 1 5 0 1 mm yr 1 rms 0 4 mm yr 1 wrms 0 3 mm yr 1 this value is consistent with various previous estimates based on secular tg observations and with that proposed for the 20th century by the intergovernmental panel on climate change ipcc fourth assessment report 1 7 0 5 mm yr 1

decoding the origins of vertical land motions observed today at coasts in recent decades geodetic techniques have allowed detecting vertical land motions and sea level changes of a few millimetres per year based on measurements taken at the coast tide gauges on board of satellite platforms satellite altimetry or both global navigation satellite system here contemporary vertical land motions are analysed from january 1993 to july 2013 at 849 globally distributed coastal sites the vertical displacement of the coastal platform due to surface mass changes is modelled using elastic and viscoelastic green s functions special attention is paid to the effects of glacial isostatic adjustment induced by past and present day ice melting various rheological and loading parameters are explored to provide a set of scenarios that could explain the coastal observations of vertical land motions globally in well instrumented regions predicted vertical land motions explain more than 80 per cent of the variance observed at scales larger than a few hundred kilometres residual vertical land motions show a strong local variability especially in the vicinity of plate boundaries due to the earthquake cycle significant residual signals are also observed at scales of a few hundred kilometres over nine well instrumented regions forming observation windows on unmodelled geophysical processes this study highlights the potential of our multitechnique database to detect geodynamical processes driven by anthropogenic influence surface mass changes surface loading and glacial isostatic adjustment and tectonic activity including the earthquake cycle sediment and volcanic loading as well as regional tectonic constraints future improvements should be aimed at densifying the instrumental network and at investigating more thoroughly the uncertainties associated with glacial isostatic adjustment models

organic matter and palaeoenvironmental signals during the early triassic biotic recovery the salt range and surghar range records latest permian to the middle triassic mixed siliciclastic carbonate shelf deposits of the northern gondwana margin have been studied in four sections nammal chhidru chitta landu and narmia in the salt range and surghar range of pakistan sedimentological and palynofacies patterns combined with a high resolution ammonoid based age control have been used to assess environmental changes such as sea level change distance from the shore and oxygenation conditions of the sections in the aftermath of the end permian mass extinction the base and the top of the early triassic are marked by second order sequence boundaries srt1 srt8 within the early triassic two third order sequence boundaries could be delineated by means of palynofacies analysis and sedimentology one near the dienerian smithian srt2 and the second one near the smithian spathian boundary srt5 the extinction event at the smithian spathian boundary seems to be closely associated to the latter globally recorded sea level low stand five additional sequences of undetermined order srt3 srt 4 srt5 1 srt6 and srt7 are reflected in the sedimentological record of the studied sections the observed changes in the composition of the particulate organic matter pom indicate a general shallowing upward trend which is modulated by smaller transgressive regressive cycles supporting the sedimentologically defined sequences the pom is mostly dominated by terrestrial phytoclasts and sporomorphs the strongest marine signal is reflected by increased abundance of amorphous organic matter aom in the lower part of the ceratite marls at nammal late dienerian and chhidru earliest smithian and the lower ceratite limestone at chitta landu late dienerian aom of marine origin is characteristic for deeper distal basinal settings and is preferentially preserved under dysoxic and anoxic conditions indicating reduced oxygen conditions during these intervals up section transgressive events are reflected by increased numbers of acritarchs reaching up to 50 of the pom well oxygenated conditions and low total organic carbon contents toc continue up to the top of the early triassic mianwali formation the most pronounced terrestrial influx is expressed in the middle triassic organic carbon isotope data parallel the carbonate carbon isotope records from the tethyan realm therefore they reflect real global changes in the carbon cycle independent of the om composition the biomarker study of the apolar hydrocarbons of three samples from the nammal section indicates an enhanced bacterial productivity especially in the smithian and spathian reflected in high relative abundances of hopanes pom toc data and redox sensitive biomarkers together with high resolution biostratigraphy demonstrate that well oxygenated environmental conditions prevailed in the early triassic with the exception of the dienerian to earliest smithian interval the pom assemblages of late permian to late griesbachian age indicate well oxygenated conditions during this time interval there is no evidence in support of an anoxic event in the late griesbachian in these sections

spatiotemporal characteristics of the displacement field revealed with principal component analysis and the mode rotation technique abstract principal component analysis pca was applied to the displacement field recorded at 147 gps stations in the kanto tokai district japan for the period from january 1999 to february 2003 some prominent geophysical events occurred during this period using pca we attempted to decompose the displacement field into some representative spatial modes and their corresponding temporal modes to quantitatively extract the primary geophysical events that have caused rapid crustal deformation in this region the displacement field was roughly decomposed into modes corresponding to the following three major events 1 the miyake kozu volcanic event which occurred in the region south of tokyo in 2000 it included large scale dyke intrusion and intensive earthquake swarm between the miyakejima and kozushima islands 2 the tokai slow slip event which is considered to have begun just after the miyake kozu volcanic event and is ongoing as of november 2005 it occurred on the boundary between the subducting philippine sea plate and the overriding eurasian amurian plate in the tokai district 3 the boso slow slip event which lasted for approximately 10 days in october 2002 it occurred on the boundary between the subducting pacific plate and the overriding north american plate near the boso peninsula in the decomposition process we combined the mode rotation technique with ordinary pca this is because pca causes contamination between modes i e a mode obtained with pca is contaminated by other modes for example the first principal mode corresponding to the miyake kozu volcanic event which is by far the largest in magnitude was clearly seen in many other modes in order to remove such contamination we applied the mode rotation technique in which the principal axes derived from pca are rotated so as to minimize the correlation coefficients between different temporal modes for a time period in which some prominent change occurs combining the mode rotation technique with pca exhibited a better performance in separating the displacement field

glacial rebound and relative sea levels in europe from tide gauge records abstract relative sea levels recorded by tide gauges during the past century in northern europe are dominated by isostatic readjustment of the land following the latest deglaciation of scandinavia and scotland maximum relative uplift of the land is centered near the northern gulf of bothnia at a rate of 6 7 mm yr with a smaller secondary maximum over scotland also at a rate of 6 7 mm yr although there probably is a relaxing peripheral bulge surrounding the regions of maximum uplift such a former bulge is poorly defined by coastal tide gauges in the north sea evidence for sinking of a former peripheral bulge of glacial origin is complicated by post carboniferous basin deepening with sediment loading and possible rejuvenation associated with glaciation other data gravity radiocarbon geomorphology support the interpretation that glacial isostasy controls the structure of relative sea level change included in this pattern of relative rise of land is a eustatic signal that biases the estimates of glacial rebound such a eustatic signal could not be isolated from the isostatic signal using the present data but glacial isostasy clearly is a major control for relative sea levels of the region absence of significant higher frequency 2 50 yr cycles in mean annual sea levels of northern europe reflects the complex hydrologic oceanographic forces to which sea levels must respond whereas other coastal regions show significant higher frequency peaks in the energy spectra of relative sea levels the many marginal seas in northern europe preclude a clear relation between hydrologic oceanographic forcing and relative sea levels although this relation must exist on a more local scale

high resolution biochronology and diversity dynamics of the early triassic ammonoid recovery the smithian faunas of the northern indian margin a new high resolution biozonation based on the unitary association ua method is constructed for the dienerian ammonoid succession of the northern indian margin it includes 12 ua zones and leads to the subdivision of the dienerian into three parts early middle and late the corresponding diversity analyses coupled with results previously obtained for the early smithian ammonoids of the same regions highlight the four following phases 1 a first modest peak of diversity in the early dienerian 2 a very low diversity persisting throughout the middle dienerian 3 a slow increase of diversity during the late dienerian and 4 a marked diversification in the early smithian turnover rates are very high during this entire time interval and the boundaries between early middle and middle late dienerian are emphasised by complete renewals of the ammonoid faunas the low diversity values in the middle and early late dienerian are concomitant with an anoxic event on outer continental shelves and coincide with warmer temperatures than those of the early dienerian and early smithian this diversity pattern stands in strong contrast with the credo of a protracted or stepwise recovery following the end permian mass extinction together with the end smithian extinction the middle and early late dienerian diversity crises were likely both radical setbacks in the recovery of early triassic ammonoids however these two diversity crises do not necessarily imply identical environmental triggers that ultimately led to anoxic bottom waters on outer continental platforms in both cases

australia an unstable platform for tide gauge measurements of changing sea levels a reply twenty five tide gauge records non uniformly distributed along the coast of australia were used to evaluate the stability of australia as a platform from which to measure changes in sea levels the spatial and temporal variabilities of relative sea levels were defined using a multivariate analytical tool eigenanalysis on 13 of these stations low frequency period 20 years and greater relative sea levels are believed to reflect the combined effects of subsistence due to sediment and water loading subsidence due to thermal cooling of oceanic crust and emergence along a convergent plate boundary global eustatic sea level rise cannot be identified unambiguously from these data but clearly it is not responsible for the observed patterns of relative sea level the straight average rate of rise of relative sea level around australia is 1 3 mm yr submergence with general submergence in the south at an average rate of 1 8 mm yr and emergence in the north 0 5 mm yr the latter an average of two sta

late early triassic climate change insights from carbonate carbon isotopes sedimentary evolution and ammonoid paleobiogeography the late early triassic sedimentary facies evolution and carbonate carbon isotopemarine record 13ccarb of ammonoid rich outer platform settings show striking similarities between the south china block scb and the widely distantnorthern indianmargin nim the studied sections are located within the triassic tethyshimalayan belt losar section himachal pradesh india and the nanpanjiang basin in the south china block jinya section guangxi province respectively carbon isotopes from the studied sections confirm the previously observed carbon cycle perturbations at a time of major paleoceanographic changes in the wake of the end permian biotic crisis this study documents the coincidence between a sharp increase in the carbon isotope composition and the worldwide ammonoid evolutionary turnover extinction followed by a radiation occurring around the smithian spathian boundary based on recent modeling studies on ammonoid paleobiogeography and taxonomic diversity we demonstrate that the late early triassic smithian and spathian was a time of a major climate change more precisely the end smithian climate can be characterized by a warm and equable climate underlined by a flat pole to equator sea surface temperature sst gradient while the steep spathian sst gradient suggests latitudinally differentiated climatic conditions moreover sedimentary evidence suggests a transition froma humid and hot climate during the smithian to a dryer climate fromthe spathian onwards by analogywith comparable carbon isotope perturbations in the latedevonian jurassic andcretaceouswe propose that high atmosphericco2 levels could have been responsible for the observed carbon cycle disturbance at the smithian spathian boundary we suggest that the end smithian ammonoid extinction has been essentially caused by a warm and equable climate related to an increased co2 flux possibly originating froma short eruptive event of the siberian igneous province this increase in atmospheric co2 concentrations could have additionally reduced the marine calcium carbonate oversaturation and weakened the calcification potential of marine organisms including ammonoids in late smithian oceans

interseismic deformation at the nankai trough japan subduction zone uplift along the coast of southwestern japan following the 1944 tonankai ms 8 0 and 1946 nankaido ms 8 2 earthquakes has been inferred from the 1950 1985 tide gage records although uplift rates vary with geographic position the temporal dependence at each site can be described as the superposition of an exponentially decaying time constant 5 years transient significant only in the first decade postseismic and a steady interseismic rate the steady interseismic uplift rate is defined only over the 1956 1985 interval but the linearity in time ofthat uplift record is such that uplift over the remainder of the interseismic cycle 80 years might reasonably be expected to occur at the same rate moreover the spatial pattern and magnitude of the steady uplift rate are reasonably close to those predicted by a simple dislocation model of subduction however the currently observed steady uplift rate is not consistent with the uplift rate inferred from geodetic leveling for the final half of the previous earthquake cycle thus either the hypothesis of a steady interseismic uplift rate after the first decade postseismic is wrong or the strain accumulation pattern for one earthquake need not be the same as for the preceding earthquake on the same segment