tsunami source uncertainty estimation the 2011 japan tsunami this article was published in the journal of geophysical research solid earth 2016 american geophysical union and the definite version is available at http dx doi org 10 1002 2015jb012764 the journal s website is at http onlinelibrary wiley com doi 10 1002 2015jb012764 abstract jsessionid bf5813b61924fb094f31bc8f213840a1 f02t04

danian selandian boundary stratigraphy paleoenvironment and ostracoda from sidi nasseur tunisia abstract two detailed records nsf and 05nsc sidi nasseur tunisia across the danian selandian d s boundary were investigated for their micropaleontological content calcareous nannofossils and planktic foraminifera provided a biostratigraphic framework the interval spans part of planktic foraminiferal zone p2 subzone p3a and part of subzone p3b this corresponds to calcareous nannoplankton zone np4 using a more detailed nannofossil zonation the studied section spans part of zone ntp6 zone ntp7a and part of ntp7b quantitative ostracod and qualitative benthic foraminiferal data were used to characterize environmental changes across the d s boundary the two subsections have yielded a total of 50 ostracod taxa the ostracod assemblage of the entire section belongs to the southern tethyan type showing subtle but distinct changes up section based on statistical analysis of the quantitative ostracod data faunal changes at a glauconitic maker bed p3a p3b boundary were demonstrated the local reticulina proteros assemblage with the typical species r proteros oertliella vesiculosa and cytheroptheron lekefense is gradually replaced by the protobuntonia nakkadii assemblage with the typical species cristaeleberis arabii xestoleberis tunisiensis cytheropteron sp and p nakkadii across the glauconitic bed the benthic foraminifera also demonstrated distinct changes at this marker bed the changes in ostracods and foraminifera are related to changes in paleoproductivity and an overall relative sea level fall the lithological and faunal changes at the p3a p3b zone boundary within the sidi nasseur sections seem to correspond to the d s boundary in the type region in danmark and are characterized by a significant hiatus yielding this section not suitable as a gssp candidate for this boundary

finite faults and inverse theory with applications to the 1979 imperial valley earthquake abstract using a representation theorem from elastodynamics subsurface slip on a known fault is formulated as the solution to an inverse problem in which recorded surface ground motion is the data two methods of solution are presented the least squares method which minimizes the squared differences between theory and data and the constrained least squares method which simultaneously maintains a set of linear inequalities instabilities in the solution are effectively eliminated in both methods and the sensitivity of the solution to small changes in the data is quantitatively stated the inversion methodology is applied to 77 components of near field ground acceleration recorded during the 15 october 1979 imperial valley earthquake the faulting is constrained to propagate bilaterally away from the epicenter at an average velocity of 90 per cent of the shear wave speed on a vertical fault plane extending from the surface to 10 km depth inequality constraints are used to keep the faulting sequence physically reasonable by maintaining right lateral motion and positive slip velocity the preferred solution is stable and provides a good fit to the data it is also realistic and consistent with observed surface offsets and independent estimates of seismic moment

paleocene sea level and productivity changes at the southern tethyan margin el kef tunisia integrated analysis of quantitative distribution patterns of organic walled dinoflagellate cysts dinocysts and benthic foraminifera from the paleocene el kef section nw tunisia allows the reconstruction of sea level and productivity fluctuations our records indicate that the environment evolved from an initially oligotrophic open marine outer neritic to upper bathyal setting towards a more eutrophic inner neritic setting influenced by coastal upwelling by the end of the paleocene an overall second order change in paleodepth is reflected by both microfossil groups from the base of planktic foraminifera zone p4 onwards the main phase of shallowing is evidenced by an increase of inner neritic dinocysts of the areoligera group disappearance of deeper water benthic foraminifera and increasing dominance of shallow marine taxa several buliminids haplophragmoides spp trochammina spp the total magnitude of this shallowing is obscured by interaction with a signal of eutrophication but estimated to be around 150 m from 200 to 50 m superimposed on the overall trend third order sea level fluctuations have been identified and correlated to sequences in other regions paleoproductivity indicators notably protoperidinioid dinocysts and buliminids show a trend from an oligotrophic to a eutrophic setting d 2005 elsevier b v all rights reserved

dinoflagellate cysts sea level changes and planktonic foraminifers across the cretaceous tertiary boundary at el haria northwest tunisia abstract dinoflagellate cysts and planktonic foraminifers have been studied from the cretaceous tertiary k t boundary interval at el haria northwest tunisia a high resolution integrated biostratigraphy is presented the k t boundary is drawn at the level of extinction of cretaceous planktonic foraminifers and is coincident with the first occurrence of the dinoflagellate cyst species danea californica the final extinction of planktonic foraminifers is foreshadowed by a reduction in their total abundance some 5 kyr earlier at the base of the boundary clay this reduction is coeval with reported anomalies in siderophyle elements and 13 c values in the same area dinoflagellate cysts do not show accelerated rates of extinction at k t time associations of dinoflagellate cysts however change drastically and parallel changes in relative numbers of sporomorphs spores and pollen and in the quantity of land derived organic matter jointly these changes reflect a rapidly falling sea level during the final 17 kyr of the mesozoic which culminates at the level of the k t boundary this steep sea level fall at k t time represents a peak regressive pulse at the end of the well documented latest cretaceous regressive trend this short term sea level fall might show to be a wide spread phenomenon which could have caused an excess shrinking of the already reduced areal extent of marginal seas since deep waters in cretaceous oceans were primarily produced in shallow marginal seas the rate of formation of deep water might have been minimized at k t time minimum rates of formation of deep water might have curtailed the slow upward mixing of relatively cool and nutrient rich deeper water through which the thermocline weakened and surficial waters became depleted in nutrients consequently phytoplankton productivity rapidly diminished which in combination with a weakened thermal gradient pushed the highly depth stratified cretaceous planktonic foraminiferal fauna to extinction over a period of time of some 5 kyr guembelitria cretacea was the sole planktonic foraminifer which could accommodate to the low productivity conditions the oscillating rise in sea level at the beginning of the cenozoic reinforced the upward mixing of relatively cool and nutrient rich deeper water steepened the thermocline and replenished the photic layer with nutrients concomitant niche differentiation in the photic layer progressively stimulated morphological innovation amongst early cenozoic planktonic foraminifers the final return of normally sized planktonic foraminifers and of stable and well balanced dinoflagellate cyst associations at about 125 kyr after the k t boundary seems to indicate that primary productivity and niche differentiation in the photic layer begin to revert to optimum levels the earliest cenozoic planktonic foraminiferal species globoconusa minutula and parvularugoglobigerina fringa are thought to have developed from a benthic foraminiferal species rather than having a planktonic ancestry

increasing restriction of the egyptian shelf during the early eocene new insights from a southern tethyan carbonate platform the evolution of the isolated galala carbonate platform has been studied intensively with respect to the paleocene eocene thermal maximum petm and the strong climatic variability from the late paleocene to the early eocene in this study we compare the results of different approaches which deal with the early palaeogene evolution of the egyptian shelf including new data from the galala platform microfacies analyses along a platform to basin transect reveal a sedimentological response to a massive tectonic uplift along the syrian arc fold belt in the early eocene this uplift triggered the restriction of the egyptian shelf by modulating and weakening tethyan onshore currents from the north the increasing deposition of quartz and proliferating gastropods green algae and radiolaria which indicate elevated nutrient levels reflect an intensified eutrophication of shallow marine platforms and deeper marine shelf environments strongly depleted carbon isotope ratios in the sediments of the galala succession strongly suggest the presence of restricted conditions throughout the early eocene we assume that a strong climatic divergence with arid conditions on the shelf and humid conditions at the african hinterland triggered intensified chemical weathering at the nubian arabian craton the enhanced riverine transport of terrestrial organic material to the north african shelf caused the increased availability of trophic resources and a strong negative shift of carbon isotope ratios between np10 and np14a the recovery to open ocean conditions is linked to the termination of tectonic uplift along the syrian arc fold belt in the latest early eocene and to stronger ocean currents caused by increasing latitudinal temperature gradients additionally the post petm carbon isotope evolution at the galala platform indicates at least two further negative carbon isotope excursions which reflect hyperthermal events on a global scale the associated reorganization of shallow marine assemblages as described for example for the larger foraminifera turnover at the petm boundary event is however missing we assume that the absence of a foraminiferal reorganization in this region can be linked to an increasing robustness of the major early eocene platform organisms larger benthic foraminifera and their adaption to unfavorable conditions and repeated environmental shifts 2011 elsevier b v

oil shale sedimentology and geochemistry in cenozoic mae sot basin thailand the intermontane mae sot basin thailand contains carbonate rich oil shales in which oil yield mineralogy and major and trace element geochemistry are related to the rock type higher grade oil shale is significantly enriched in silicate minerals quartz feldspars clays and analcite relative to carbonates and in dolomite relative to calcite couplets of organic rich and mineral rich laminae increase in mean thickness from 0 080 mm to 0 670 mm from high to low grade oil shale the organic material consists mainly of lamalginite and yields up to 341 l of oil mt 81 8 gal ton on retorting fish and vascular plant fragments are the main megafossils mappable oil shale sequences 10 m 33 ft thick are interstratified with marlstone sandstone sequences 70 m 230 ft thick markov chain analysis applied to stratigraphic sequences indicates that low grade oil shale passes gradually into high grade oil shale and vice versa the strata are interpreted as the deposits of extensive fresh to brackish lakes with oil shale sequences formed in perennial stratified lakes and marlstone sandstone sequences formed in shallow perennial lakes and subaerially exposed flats dolomite in the oil shales was authigenic the systematic changes in mineralogy and geochemistry between rock types probably reflect a gradient in redox potential from the center to the margins of the lake sandstone and siltstone beds and some carbonate laminae are interpret d as density flow deposits and form a significant proportion of the sequences the episodic deposition of oil shales reflects changes in lake level within the enclosed basin probably due to climatic fluctuations on a 24 000 to 46 000 year scale

style and intensity of late cenozoic deformation in the nagoorin basin eastern queensland australia and implications for the pattern of strain in an intraplate setting eastern australia was affected by late cenozoic intraplate deformation in response to far field stress transmitted from the plate boundaries but little is known about the intensity and pattern of this deformation we used recently surveyed two dimensional seismic reflection lines and aeromagnetic data and data from the recently released australian stress map to investigate the structure of the nagoorin basin in eastern queensland the western margin of the nagoorin beds was displaced by the boynedale fault which is a nnw striking sw dipping oblique strike slip reverse fault with a vertical throw of c 900 m and c 16 km sinistral displacement a significant part of this large sinistral displacement is interpreted to have occurred prior to late cenozoic time several low angle 30 thin skinned thrusts with a flat ramp geometry also displaced the nagoorin beds which are interpreted to have developed along detachment surfaces in oil shales and claystone the boynedale fault is a segment within longer nnw striking faults that include the north pine and west ipswich fault systems in eastern queensland these nnw striking faults are potentially active and may accommodate neotectonic thrust movement in response to the present day ne sw orientation of s results of this study in conjunction with previous information on sedimentary basins in eastern australia indicate that cenozoic contractional deformation is stronger at the continental margins possibly due to the presence of pre existing rift related structures

bayesian rupture imaging in a complex medium the 29 may 2012 emilia northern italy earthquake we develop a new approach to image earthquake rupture from strong motion data we use a large data set of aftershock waveforms interpolated over the seismic fault to obtain green s function approximations next we deploy a bayesian inversion method to characterize the slip distribution the rupture velocity the slip duration and their uncertainties induced by errors in the green s functions the method is applied to the 29 may 2012 mw 6 emilia earthquake which ruptured a fault buried below the po plain sediments northern italy despite the particularly complex wave propagation the near field strong motion observations are well reproduced with 15 rupture parameters the rupture and slip velocities were notably slow 0 5 vs and 0 5 m s respectively implying that the fault was difficult to break this method opens some perspectives for earthquake rupture studies in areas where numerical simulations suffer from imprecise knowledge of the velocity structure

the use of back scattered electron imaging for the petrographic study of sandstones and shales abstract in this paper the imaging of mineral grains in sedimentary rocks by atomic number contrast using back scattered electrons bse in the sem is discussed the analyses of polished thin sections of a sandstone and a shale are used to illustrate the technique and particularly to demonstrate its usefulness in petrographic studies of fine grained sedimentary rocks the coupling of energy or wavelength dispersive x ray elemental analysis to atomic number contrast allows minerals to be readily identified and paves the way for detailed geochemical and mineral crystallochemical studies of fine grained sediments

introduction of covariance components in slip inversion of geodetic data following a non uniform spatial distribution and application to slip deficit rate estimation in the nankai trough subduction zone when spatial distribution of observation stations has bias in geodetic slip inversion modeling errors in the inversion scheme may result in significant unnatural short wave components in estimated slip distribution which overfit to data combined use of both land and seafloor geodetic data in slip inversion often leads to such situations to avoid overfitting i proposed a method to incorporate proper covariance components in the data covariance matrix originated by modeling errors in the geodetic slip inversion because linearity of the inversion problem is retained widely known approaches to introduce prior constraints to the inversion which assumes linear inversion are easily applied to the proposed method synthetic tests showed that the introduction of covariance components allowed for the estimation of slip distributions closer to the true one avoiding overfitting to geodetic data in biasedly distributed observation stations compared to a conventional approach that does not introduce covariance components i applied the proposed method to the estimation of the slip deficit rate in the nankai trough subduction zone using geodetic data of displacement rates provided by land gnss stations and seafloor gnss acoustic stations the proposed method estimated a reasonably smooth distribution of slip deficit rate compared to the conventional approach spatial distribution of residuals in the displacement rates suggested that the proposed method successfully avoids overfitting to the block motion at the south of the median tectonic line which the physical model i assumed here cannot describe

finite fault bayesian inversion of teleseismic body waves abstract inverting geophysical data has provided fundamental information about the behavior of earthquake rupture however inferring kinematic source model parameters for finite fault ruptures is an intrinsically underdetermined problem the problem of nonuniqueness because we are restricted to finite noisy observations although many studies use least squares techniques to make the finite fault problem tractable these methods generally lack the ability to apply non gaussian error analysis and the imposition of nonlinear constraints however the bayesian approach can be employed to find a gaussian or non gaussian distribution of all probable model parameters while utilizing nonlinear constraints we present case studies to quantify the resolving power and associated uncertainties using only teleseismic body waves in a bayesian framework to infer the slip history for a synthetic case and two earthquakes the 2011 m w 7 1 van east turkey earthquake and the 2010 m w 7 2 el mayor cucapah baja california earthquake in implementing the bayesian method we further present two distinct solutions to investigate the uncertainties by performing the inversion with and without velocity structure perturbations we find that the posterior ensemble becomes broader when including velocity structure variability and introduces a spatial smearing of slip using the bayesian framework solely on teleseismic body waves we find rake is poorly constrained by the observations and rise time is poorly resolved when slip amplitude is low electronic supplement figures of histograms of slip and rise time waveform comparisons between data and synthetics and slip velocity along the fault plane for a synthetic case as well as for the 2011 m w 7 1 van east turkey earthquake and the 2010 m w 7 2 el mayor cucapah baja california earthquake

transdimensional uncertainty estimation for dispersive seabed sediments abstractwe have applied probabilistic inversion using a transdimensional hierarchical model to ocean acoustic reflection measurements to recover shallow sediment structure including sound velocity dispersion frequency dependent attenuation and their uncertainties parameter and uncertainty inferences were obtained from markov chain simulations using the metropolis hastings algorithm for transdimensional models where the number of sediment layers is unknown transdimensional algorithms often exhibit slow convergence that is greatly exacerbated by computationally intensive data predictions advances were made to improve the performance of markov chain simulation and data prediction chain mixing across dimensions was addressed using a tempered sequence of interacting markov chains which substantially improves convergence rates the acoustic recordings were processed to give seabed reflection coefficients as a function of frequency grazing angle and integration time penetration depth such reflection

extending resolution of fault slip with geodetic networks through optimal network design geodetic networks consisting of high precision and high rate global navigation satellite systems gnss stations continuously monitor seismically active regions of the world these networks measure surface displacements and the amount of geodetic strain accumulated in the region and give insight into the seismic potential sugar sumatra gps array in sumatra geonet gnss earth observation network system in japan and pbo plate boundary observatory in california are some examples of established networks around the world that are constantly expanding with the addition of new stations to improve the quality of measurements however installing new stations to existing networks is tedious and expensive therefore it is important to choose suitable locations for new stations to increase the precision obtained in measuring the geophysical parameters of interest here we describe a methodology to design optimal geodetic networks that augment the existing system and use it to investigate seismo tectonics at convergent and transform boundaries considering land based and seafloor geodesy the proposed network design optimization would be pivotal to better understand seismic and tsunami hazards around the world land based and seafloor networks can monitor fault slip around subduction zones with significant resolution but transform faults are more challenging to monitor due to their near vertical geometry

abrupt deep sea warming palaeoceanographic changes and benthic extinctions at the end of the palaeocene a remarkable oxygen and carbon isotope excursion occurred in antarctic waters near the end of the palaeocene 57 33 myr ago indicating rapid global warming and oceanographic changes that caused one of the largest deep sea benthic extinctions of the past 90 million years in contrast the oceanic plankton were largely unaffected implying a decoupling of the deep and shallow ecosystems the data suggest that for a few thousand years ocean circulation underwent fundamental changes producing a transient state that although brief had long term effects on environmental and biotic evolution

trans dimensional surface reconstruction with different classes of parameterization portions of this software development were funded by auscope through the national collaborative research infrastructure strategy ncris an australian federal government programme r h and t b are funded by the european unions horizon 2020 research and innovation programme under grant agreement 716542

paleooceanography of the mesogean sea based on ostracods of the northern tunisian continental shelf between the late cretaceous and early paleogene a new method analysis used in the study of the el kef section north western tunisia led to the paleooceanographic reconstruction of the mesogean between late cretaceous and early paleogene several changes observed are in fact worthy of particular mention paleobathymetrically the area changed from an upper bathyal environment of about 400 m deep to an outer shelf domain of 100 50 m furthermore the oxygen minimum zone o m z became highly intense at a the cretaceous tertiary transition catastrophic event b the p1 p2 boundary intense thermic stratification and c between p4 and p6 very active paleoproductivity in this last episode the continental shelf environment was subjected to intense upwelling responsible for the formation of a prephosphatic environment at water sediment interface the paleooceanographic history of phosphates in the gafsa metlaoui basin is in fact in perfect stratigraphic and paleoenvironmental agreement with the paleobathymetric evolution of the kef region finally paleooceanographic communication between the mesogean and the north atlantic was at this period highly free because of lack of hydrologic relations between the north atlantic and the norwegian sea

a benthic foraminiferal record of paleocene sea level and trophic redox conditions at gebel aweina egypt we quantitatively analyzed benthic foraminiferal assemblages in order to reveal biotic and paleoenvironmental trends in the paleocene section of gebel aweina egypt on the southern tethyan shelf the first correspondence axis ranks taxa along an empirically derived bathymetric gradient with neritic taxa e g discorbis duwi and haplophragmoides walteri opposed to bathyal taxa e g nuttallides truempyi and gavelinella beccari ormis the estimated paleodepth as reflected by the various assemblages was mostly 200 m but varied between 50 m p3a np4 and 300 m p4 n p8 the resultant four relative sea level cycles appear to be at least of regional extent and may in part be eustatically controlled the second correspondence axis reflects trends in trophic and redox development low food high oxygen conditions prevailed during biochrons plc p3b np4 np5 and late p4 np8 when assemblages were mostly dominated by cibicidoides spp most oligotrophic conditions coincided with maximum paleodepth intermediate trophic levels were established during middle p4 np6 and early p5 np9 from the level of the latest paleocene benthic extinction event bee middle p5 and np9 onwards until biochron p6a np10 assemblages dominated by buliminids marked increased trophic levels and reduced ventilation probably resulting from enhanced surface productivity enhanced surface productivity along the southern tethyan margin started during biochron p4 and at least on some shelves intensified after the bee increasing productivity during the latest paleocene contrasts with global trends this may be expected during climatic warming and an expanding trophic resource continuum leading to regionally intensified eutrophy and oligotrophy high productivity through upwelling along the southern tethyan provides support for gcm predictions of intense wind stress in this region during the warm late to latest paleocene 1998 elsevier science b v

source inversion of w phase speeding up seismic tsunami warning w phase is a long period phase arriving before s wave it can be interpreted as superposition of the fundamental first second and third overtones of spheroidal modes or rayleigh waves and has a group velocity from 4 5 to 9 km s 1 over a period range of 100 1000 s the amplitude of long period waves better represents the tsunami potential of an earthquake because of the fast group velocity of w phase most of w phase energy is contained within a short time window after the arrival of the p wave at a distance of 50 w phase energy is contained within 23 min after the origin time which is the distinct advantage of using w phase for rapid tsunami warning purposes we use a time domain deconvolution method to extract w phases from the broad band records of global seismic networks the bandwidth of w phase is approximately from 0 001 to 0 01 hz and we bandpass filter the data from 0 001 to 0 005 hz in most cases having extracted w phase from the vertical component records we perform a linear inversion using a point source to determine mw and the source mechanism for several large earthquakes including the 2004 sumatra andaman earthquake the 2005 nias earthquake the 2006 kuril is earthquake and the 2007 sumatra earthquake w phase inversion yields reliable solutions and holds promise of the use of w phase for rapid assessment of tsunami potential

comparison of seismic waveform inversion results for the rupture history of a finite fault application to the 1986 north palm springs california earthquake the july 8 1986 north palm springs earthquake is used as a basis for comparison of several different approaches to the solution for the rupture history of a finite fault the inversion of different waveform data is considered both teleseismic p waveforms and local strong ground motion records linear parametrizations for slip amplitude are compared with nonlinear parametrizations for both slip amplitude and rupture time inversions using both synthetic and empirical green s functions are considered in general accurate green s functions are more readily calculable for the teleseismic problem where simple ray theory and flat layered velocity structures are usually sufficient however uncertainties in the variation in t with frequency most limit the resolution of teleseismic inversions a set of empirical green s functions that are well recorded at teleseismic distances could avoid the uncertainties in attenuation in the inversion of strong motion data the accurate calculation of propagation path effects other than attenuation effects is the limiting factor in the resolution of source parameters the assumption of a laterally homogeneous velocity structure is usually not a good one and the use of empirical green s functions is desirable considering the parametrization of the problem any degree of fault rupture complexity can be described in terms of a linear parametrization for slip amplitudes however a nonlinear parametrization for rupture times and slip amplitudes can have a distinct advantage over a simple linear one by limiting the number of unknown parameters regardless of the choice of data or the type of parametrization the model or solution will be affected by the choice of minimization norm and the type of stabilization used

stable isotope toc and caco3 record across the cretaceous tertiary boundary at el kef tunisia we report the results of stable oxygen and carbon isotope analysis of carbonate fine fraction and benthic and planktic foraminifers caco3 and toc determinations of sediments across the cretaceous tertiary k t boundary at el kef tunisia we used grain size analysis of the fine fraction carbonate to determine possible compositional effects and smearslide and scanning electron microscope examinations to evaluate possible diagenetic alteration and microfossil preservation the data suggests the following sequence of events upper maastrichtian oxygen and carbon isotope signals indicate relatively warm temperatures a decreasing thermal gradient possibly related to a shallowing sea and relatively high surface water productivity a sharp cooling appears to begin just below the k t boundary the k t boundary is characterized by a sudden 2 negative shift in fine fraction 13c a slight 0 6 enrichment in benthic 13c and a reduction of about 40 in caco3 sedimentation these data imply strongly reduced surface water productivity as also observed in numerous deep sea sequences worldwide the lower danian planktic foraminiferal zones p0 p1a is marked by generally low productivity and unstable environmental conditions as indicated by generally low but fluctuating fine fraction 13c values and low 5 15 carbonate deposition at the base of subzone p1b caco3 benthic and fine fraction 13c values increase gradually and reach near pre k t boundary levels in subzone p1c indicating initial recovery after the k t boundary event about 300 000 400 000 years after the k t boundary the prolonged low productivity episode after the k t crisis and the pre k t boundary cooling associated with a major reduction in planktic foraminiferal diversity are difficult to explain by a single k t boundary bolide impact

logarithmic model joint inversion method for coseismic and postseismic slip application to the 2017 mw 7 3 sarpol zahāb earthquake iran

paleoenvironmental change at the danian selandian transition in tunisia foraminifera organic walled dinoflagellate cyst and calcareous nannofossil records abstract in the present study we document paleoenvironmental change across the danian selandian transition planktic foraminiferal interval p2 p3b calcareous nannofossil zone np4 subzones ntp6 ntp8a 61 59 ma in nw tunisia diversifications of paleogene planktic foraminifera with the evolution of the muricate and photosymbiotic lineages morozovella acarinina and igorina and of the biostratigraphically important nannofossils genus fasciculithus are recorded within this interval the present study aims to understand early paleogene environmental changes in the southern tethys by analyzing the evolution of surface water and to a lesser extent seafloor conditions three localities were investigated ain settara elles and el kef all representing outer neritic deposition in the same basin the tunisian trough paleoenvironmental changes are explored by combining planktic foraminiferal organic dinocyst and calcareous nannofossils assemblages and several proxy parameters planktic benthic ratio numbers of planktic foraminifera per gram peridinioid gonyaulacoid ratio terrestrial marine palynomorph ratio in addition also some geochemical parameters calcite content and stable isotopes are examined our records indicate that the environment evolved from an initially oligotrophic open marine deep outer neritic setting in p2 p3a towards a shallower and nutrient rich setting from the base of subzone p3b this change is seen in the foraminiferal assemblages with the substitution of praemurica by morozovella among the planktic foraminifera and an upward decrease in deeper benthic taxa also the organic dinocyst assemblages show a peak of peridinioid cysts cerodinium and lejeunecysta associated to these dinocyst assemblages the lowest occurrence of apectodinium is recorded which seem to have evolved in this region possibly in response to enhanced nutrient levels on the shelf additionally a distinct change in calcareous nannofossil assemblages is also described marked by the lowest appearance of chiasmolithus edentulus the lowest consistent occurrence of fasciculithus and a slight increase in near shore taxa essentially pontosphaera this project provides an accurate understanding of paleoenvironmental change across the danian selandian transition in tunisia especially integrating different proxies demonstrates a paleobathymetric shallowing from the danian to the selandian associated to increase surface paleoproductivity furthermore the results are compared with those from other localities along the southern tethyan margin egypt and jordan and a more regional paleoclimatic paleoceanographic perturbation in the southern tethys is suggested

bayesian inversion of marine csem data with a trans dimensional self parametrizing algorithm summary the posterior distribution of earth models that fit observed geophysical data convey information on the uncertainty with which they are resolved from another perspective the non uniqueness inherent in most geophysical inverse problems of interest can be quantified by examining the posterior model distribution converged upon by a bayesian inversion in this work we apply a reversible jump markov chain monte carlo method to sample the posterior model distribution for the anisotropic 1 d seafloor conductivity constrained by marine controlled source electromagnetic data unlike conventional gradient based inversion approaches our algorithm does not require any subjective choice of regularization parameter and it is self parametrizing and trans dimensional in that the number of interfaces with a resistivity contrast at depth is variable as are their positions a synthetic example demonstrates how the algorithm can be used to appraise the resolution capabilities of various electromagnetic field components for mapping a thin resistive reservoir buried beneath anisotropic conductive sediments a second example applies the method to survey data collected over the pluto gas field on the northwest australian shelf a benefit of our bayesian approach is that subsets of the posterior model probabilities can be selected to test various hypotheses about the model structure without requiring further inversions as examples the subset of model probabilities can be viewed for models only containing a certain number of layers or for models where resistive layers are present between a certain interval as suggested by other geological constraints such as seismic stratigraphy or nearby well logs

trans dimensional finite fault inversion summary this paper develops a probabilistic bayesian approach to the problem of inferring the spatiotemporal evolution of earthquake rupture on a fault surface from seismic data with rigorous uncertainty estimation to date uncertainties of rupture parameters are poorly understood and the effect of choices such as fault discretization on uncertainties has not been studied we show that model choice is fundamentally linked to uncertainty estimation and can have profound effects on results the approach developed here is based on a trans dimensional selfparametrizationofthefault avoidsregularizationconstraintsandprovidesrigorousuncertainty estimationthataccountsformodel selectionambiguityassociatedwiththefaultdiscretization in particular the fault is parametrized using self adapting irregular grids which intrinsically match the local resolving power of the data and provide parsimonious solutions requiring few parameters to capture complex rupture characteristics rupture causality is ensured by parametrizing rupture onset time by a rupture velocity field and obtaining first rupture times from the eikonal equation the bayesian sampling of the parameter space is implemented on a computer cluster with a highly efficient parallel tempering algorithm the inversion is applied to simulated and observed w phase waveforms from the 2010 maule chile earthquake simulation results show that our approach avoids both over and underparametrization to ensure unbiased inversion results with uncertainty estimates that are consistent with data information the simulation results also show the ability of w phase data to resolve the spatial variability of slip magnitude and rake angles in addition sensitivity to spatially dependent rupture velocities exists for kinematic slip models application to the observed data indicates that residual errors are highly correlated and likely dominated by theory error necessitating the iterative estimation of a non stationary data covariance matrix the moment magnitude for the maule earthquake is estimated to be 8 9 with slip concentrated in two zones updip of and north and south of the hypocentre respectively while this aspect of the slip distribution is similar to previous studies we show that the slip maximum in the southern zone is poorly resolved compared to the northern zone both slip maxima are higher than reported in previous studies which we speculate may be due to the lack of bias caused by the regularization used in other studies

latest paleocene lithologic and biotic events in neritic deposits of southwestern new jersey in the southwestern new jersey coastal plain four drill holes contain continuous neritic sedimentation across the paleocene eocene boundary calcareous nannofossil zone np 9 np 10 boundary significant lithologic and biotic changes occur in these strata near the top of the paleocene global warming increased precipitation and other oceanographic and climatic events that have been recognized in high latitude deep oceanic deposits of the latest paleocene also influenced mid latitude shallow marine and terrestrial environments of the western north atlantic the diverse well preserved calcareous nannofossil flora that is present throughout the entire new jersey boundary section accurately places these events within the uppermost part of the upper paleocene zone np 9 several rapid but gradational changes occur within a 1 1 m interval near the top of zone np 9 the changes include 1 a change in lithology from glauconitic quartz sand to clay 2 a change in clay mineral suites from illite smectite dominated to kaolinite dominated 3 a change in benthic foraminiferal assemblages to a lower diversity fauna suggestive of low oxygen environments 4 a significant increase in planktonic foraminiferal abundance and 5 an increased species turnover rate in marine calcareous nannofossils pollen was sparse in the new jersey drill holes but terrestrial sporomorph species in virginia exhibit increased turnover rates at a correlative level foraminiferal assemblages and lithology indicate that relative sea level rose in new jersey at the same time as these late paleocene events occurred in late biochron np 9 the higher sea levels influenced sediment type and absolute abundance of planktonic foraminifers in the deposits above the initial increase of kaolinite in the upper part of zone np 9 the kaolinite percentage continues to increase and the maximum kaolinite value occurs in the uppermost part of zone np 9 there are few changes in either the sediments or the biota precisely at the zone np 9 np 10 boundary in new jersey the clay rich deposits with a high kaolinite clay mineral suite the lowered diversity benthic foraminiferal assemblages the abundant planktonic foraminiferal specimens and the calcareous nannofossil assemblages continued essentially unchanged into the earliest eocene zone np 10 within the lower part of zone np 10 the kaolinite percentage decreased to very low values

the paleoclimatic interpretation of clay minerals in sediments a review abstract the application of paleoclimatic interpretation to clay minerals from continental and marine sediments is reviewed and the advantages of this method are indicated levels relatively rich in chlorite illite palygorskite and quartz are interpreted as corresponding to relatively dry periods while more humid periods lead to more intensive weathering and consequently to the dominance of clay minerals more advanced in the relative stability scale such as kaolinite smectite is taken to indicate a climate with contrasting seasons and a pronounced dry season using this and similar schemes the paleoclimates of areas adjoining the mediterranean basin north sea north atlantic southern arctic equatorial and north west pacific and north phillipine sea are reconstructed clay minerals in sediments particularly marine sediments can be useful indicators of paleoclimatic conditions while they do not produce direct indications of climatic parameters they provide integrated records of overall climatic impact occasionally they may be superior to the more conventional paleoclimatic methods such as pollen or oxygen isotope analysis the limitations imposed on the paleoclimatic interpretation of clay minerals in sediments are discussed on the basis of examples the distinction between authigenic and detrital clay minerals is shown to be problematic particularly with regard to smectite the relationship between climatic parameters and clay mineral formation is complicated by the intervention of extra climatic factors such as topography geomorphology lithology and time post depositional diagenetic changes may not be recognized differentiation during transport due to size sorting or differential flocculation may overlap climate induced differentiation the association of clay mineral assemblages with specific source areas presents difficulties due to dispersal pathways that are affected by type of transport agency i e water ice or wind transport agencies are not constant with time by an interdisciplinary approach with the paleoclimatic information derived from clay minerals being correlated with that obtained from the analysis of microfossils and oxygen isotope data many of these limitations can be overcome

geodetic data inversion based on bayesian formulation with direct and indirect prior information summary mechanical interaction between adjacent plates which causes crustal deformation in plate boundary zones is rationally represented by tangential displacement discontinuity fault slip at plate interfaces given fault slip distribution we can compute surface displacements on the basis of elastic dislocation theory thus we can determine the functional form of a stochastic model to extract information about unknown fault slip distribution from observed surface displacement data in addition to observed data we usually have prior information for example plate tectonics postulates that primary fault slip is parallel to relative plate motion this is direct prior information that bounds the values of model parameters within certain ranges from physical consideration we may impose prior constraint on the roughness of fault slip distribution this is indirect prior information that regulates the structure of stochastic models by combining the direct and indirect prior information with observed data in a proper way we constructed a bayesian model for geodetic data inversion which has a hierarchic flexible structure controlled by hyper parameters the optimum values of hyper parameters are objectively determined from observed data by using akaike s bayesian information criterion abic the inversion formula derived from the bayesian model unifies the jackson matsu ura formula with direct prior information and the yabuki matsu ura formula with indirect prior information in a rational way we demonstrated the effectiveness of the unified inversion formula through the analysis of the surface displacement data associated with the 1923 kanto earthquake in the analysis with direct and indirect prior information we obtained the bimodal distribution of fault slip almost parallel to plate convergence on the north american philippine sea plate interface if we ignore the direct prior information in the analysis additional significant distribution of fault slip perpendicular to plate convergence appears to the east which is incomprehensible from plate tectonics

benthic foraminifera and environmental turnover across the cretaceous paleogene boundary at blake nose odp hole 1049c northwestern atlantic sediments recovered at lower bathyal odp site 1049 on blake nose northwestern atlantic offer an opportunity to study environmental changes at the cretaceous paleogene k p boundary relatively close to the chicxulub impact structure on the yucatan peninsula mexico in hole 1049c the boundary is located at the base of a 9 cm thick layer with abundant spherules considered to be impact ejecta uppermost maastrichtian oozes below and lowermost danian pelagic oozes above the spherulebed contain well preserved bathyal benthic foraminifera the spherule bed itself in contrast contains a mixture of shallow neritic and deeper bathyal species and specimens vary strongly in preservation this assemblage was probably formed by reworking and down slope transport triggered by the k p impact across the spherule bed i e the k p boundary only f7 of benthic foraminiferal species became extinct similar to the low extinction rates of benthic foraminifera worldwide quantitative analysis of benthic foraminiferal assemblages and morphogroups in the 63 am size fraction indicates a relatively eutrophic stable environment during the latest maastrichtian interrupted by a sudden decrease in the food supply to the benthos at the k p boundary and a decrease in diversity of the faunas followed by a stepped recovery during the earliest danian the recovery was probably linked to the gradual recovery of surface dwelling primary producers d 2004 elsevier b v all rights reserved

palaeoenvironmental changes across the danian selandian boundary in the north sea basin abstract the danian selandian boundary 60 ma marks the cessation of 40 million years of carbonate deposition in the north sea basin and a shift to siliciclastic deposition on the basis of variations in lithology benthic and planktonic foraminifera and calcareous nannofossils in three cores from storebaelt in the eastern part of the north sea basin we have reconstructed the palaeoenvironmental changes across the boundary the benthic foraminiferal faunas belong to the midway type fauna they are extremely rich and more than 260 taxa have been recognized q mode cluster analysis groups the benthic assemblages into four biofacies which correspond fairly closely to lithological units correlation of the storebaelt records with marine palaeorecords from the danish basin and the north sea basin indicate that the transformation of the north sea from a carbonate to a siliciclastic basin occurred in four steps separated by relatively long stable periods the most important external factors involved in the change are firstly a drop in the relative sea level during the late danian leading to the disappearance of bryozoans from the north sea basin and to non deposition and erosion in many areas secondly coinciding with the danian selandian boundary an uplift of the scotland shetland area resulting in a massive input of siliciclastic deposits to the north sea basin thirdly during the early selandian inversion of the sorgenfrei tornquist zone and mesozoic basins in the southern and eastern part of the north sea basin resulted in a huge influx of reworked cretaceous chalk and an almost complete stop of carbonate production finally later in the early selandian in connection to a general sea level rise and a reduction in the gateway between the north sea basin and the tethys sea the sea bottom conditions became colder and more acidic this resulted in partial dissolution of the carbonates and the deposition shifted from marl to clay comparison with records from the western pyrenees the nile basin and the eastern north america suggests that sea level changes across the danian selandian boundary are primarily of eustatic nature

a new geochemical classification of sedimentary environments because of the relative constancy of ph in most subaqueous sediments and the general lack of measurability of eh these parameters are not practically useful for classifying sedimentary environments in their place a new classification is offered which derived from studies of modern sediments is based on the presence or absence of dissolved oxygen and dissolved sulfide in the sediments at the time of authigenic mineral formation sedimentary environments are first of all divided into oxic and anoxic depending upon the presence or absence of measurable dissolved oxygen anoxic environments in turn are divided into sulfidic and non sulfidic depending upon the presence of measurable dissolved sulfide anoxic nonsulfidic environments are further divided into postoxic or resulting from oxygen removal without sulfate reduction weakly reducing and methanic or resulting from complete sulfate reduction with consequent methane formation strongly reducing the environments are shown to succeed one another during early diagenesis in the order oxic post oxic sulfidic methanic iron and manganese minerals characteristic and stable in each environment are listed and discussed so that they may be used to distinguish the environments when studying the ancient geological record

the 1994 northridge california earthquake investigation of rupture velocity risetime and high frequency radiation a hybrid global search algorithm is used to solve the nonlinear problem of calculating slip amplitude rake risetime and rupture time on a finite fault thirty five strong motion velocity records are inverted by this method over the frequency band from 0 1 to 1 0 hz for the northridge earthquake four regions of larger amplitude slip are identified one near the hypocenter at a depth of 17 km a second west of the hypocenter at about the same depth a third updip from the hypocenter at a depth of 10 km and a fourth updip from the hypocenter and to the northwest the results further show an initial fast rupture with a velocity of 2 8 to 3 0 km s followed by a slow termination of the rupture with velocities of 2 0 to 2 5 km s the initial energetic rupture phase lasts for 3 s extending out 10 km from the hypocenter slip near the hypocenter has a short risetime of 0 5 s which increases to 1 5 s for the major slip areas removed from the hypocentral region the energetic rupture phase is also shown to be the primary source of high frequency radiation 1 15 hz by an inversion of acceleration envelopes the same global search algorithm is used in the envelope inversion to calculate high frequency radiation intensity on the fault and rupture time the rupture timing from the low and high frequency inversions is similar indicating that the high frequencies are produced primarily at the mainshock rupture front two major sources of high frequency radiation are identified within the energetic rupture phase one at the hypocenter and another deep source to the west of the hypocenter the source at the hypocenter is associated with the initiation of rupture and the breaking of a high stress drop asperity and the second is associated with stopping of the rupture in a westerly direction

perturbation of a tethyan coastal environment during the paleocene eocene thermal maximum in tunisia sidi nasseur and wadi mezaz abstract despite the large number of studies on the paleocene eocene thermal maximum petm the knowledge of environmental and biotic responses in shallow marine environments remains quite poor benthic foraminiferal assemblages of the sidi nasseur and wadi mezaz sections in tunisia were studied quantitatively and the paleoecologic interpretations provide new insights into the complex relationship between petm global warming and perturbations of shallow marine settings these sections expose upper paleocene to lower eocene shales and marls of the el haria formation up to the phosphate layers of the chouabine formation underlying the el garia limestones the sidi nasseur section contains a more complete and expanded paleocene eocene boundary interval compared to wadi mezaz although being truncated at the top the wadi mezaz section contains a more complete post petm interval the studied interval can be subdivided into a sequence of 4 biofacies representing respectively a latest paleocene biofacies two petm biofacies and one post petm eocene biofacies the latest paleocene biofacies 1 consists of numerous calcareous benthic foraminifera e g anomalinoides midwayensis frondicularia aff phosphatica and various bulimina and lenticulina species abundant non calcareous taxa haplophragmoides and rare planktic foraminifera indicating a slightly hypersaline eutrophic inner neritic to coastal environment regularly interrupted by oxygen deficiency moderate dysoxia during the latest paleocene this highly productive environment shallowed as indicated by the increasing abundances of a midwayensis the variable dominance of non calcareous agglutinated taxa in biofacies 1 indicates post mortem dissolution effects the toc 13 c org record reveals a sharp negative excursion marking the base of the eocene in general the absence of lithologic changes an increasing sedimentation rate and absence of reworking indicate that the initial part of the petm is complete and expanded in the sidi nasseur section a sharp faunal turnover coincides with this negative 13 c org excursion and is characterized by the disappearance or diminution of common paleocene taxa in this area during the petm benthic foraminifera are less abundant and consist of opportunistic non calcareous taxa together with deeper dwelling middle neritic lagenids and buliminids biofacies 2 and 3 planktic foraminifera dominated by flat spired acarinina mainly a multicamerata become more abundant as observed in many open marine sequences worldwide all these faunal parameters suggest more stressed probably severe dysoxic sea floor conditions within a transgressive phase during the onset of the petm an estimation of the total duration of the sidi nasseur petm interval is difficult to establish yet the lack of recovery carbon isotope values suggests that the preserved petm interval reflects only a part of the cie core the top of the petm interval is truncated due to local erosion during the early eocene the eocene recovery fauna is mainly composed of lenticulina and stainforthia species biofacies 4 indicating restricted coastal to hyposaline lagoonal eutrophic conditions distinctly different from earlier environmental conditions

sedimentology mineralogy and isotopic analysis of pellet lake coorong region south australia gravity cores of holocene sediments from a shallow ephemeral lake in the coorong region pellet lake southeastern coastal australia show a mineral assemblage and sequence particular to its hydrology the mineralogical sequence above an initial dolomitic siliciclastic sand reflects conditions of increasing salinity in the lower portions of the core i e organic rich aragonite to magnesite hydromagnesite aragonite followed by a relative decrease in salinity i e magnesite aragonite hydrornagnesite to aragonite hydromagnesite in the upper portions of the core this sequence is capped by 0 4 m of micritic dolomite and minor amounts of hydromagnesite with the relative abundance of dolomite increasing upwards three stratigraphically and spatially distinct dolomite units upper lower and margin are recognized using stable carbon and oxygen isotope data unit cell calculations and mgc03 mole per cent data of the dolomite detailed x ray diffraction xrd analyses of samples with more than 80 dolomite shows that the dolomite is ordered average unit cell parameters calculated from the xrd patterns indicate that the upper dolomite unit has crystal lattices expanded in the c direction c 16 09 a relative to ideal dolomite c 16 02 a and contracted in the a direction a 4 796 a relative to ideal dolomite a 4 812 a the mol fraction of mgc03 in the upper dolomite shows up to 4 0 f 2 0 mole per cent excess mg in the dolomite crystal lattice calculated from xrd this unusual dolomite crystal chemistry is probably generated by rapid precipitation from solutions which have greatly elevated mg ca ratios transmission electron microscopy reveals that the upper dolomite has a heterogeneous microstructure which also suggests rapid precipitation from solution the modulated microstructure found in calcium rich dolomite is completely lacking dolomite ordering reflections are present in electron diffraction patterns but are weak stable oxygen and carbon isotope values of the upper dolomite are tightly grouped ave 6l80 x 7 55 6i3c 4 10 yet show three upward lightening oxygen cycles the oxygen cycles correlate with three upward decreases in the calculated mg content of the dolomite zone these cycles may indicate the increased importance of rain water dilution of the brine at times when the water in the lake was at its shallowest levels analyses of the lower dolomite and the margin dolomite suggest that these units precipitated more slowly from less evaporitic brines than the upper dolomite unit the lower dolomite is close to stoichiometric has less evaporitic stable isotope values than the upper dolomite and has only a slightly expanded c axis the margin dolomite is ca rich has a more homogeneous microstructure and has expanded a and c axes the abundance of relatively soluble mg bearing phases such as hydromagnesite and magnesite may supply additional magnesium for the dolomitization of aragonite and calcite during subsequent diagenesis and burial of the sediment this process may leave a finely laminated dolomicrite deposit which retains little if any evidence of evaporite minerals

origin of lacustrine rocks of wilkins peak member wyoming wilkins peak member of the green river formation with its interbeds of trona oil shale and dolomitic mudstone contrasts markedly with the predominantly oil shale and calcitic mudstone sequences of the remainder of the succession much discussion has centered on the origin of these lacustrine rocks a perennial meromictic stratified lake model has been replaced in recent years by a playa lake model the subsurface stratigraphy however was not well known when the models were developed paleogeographic reconstruction indicates that the region was subjected to variations in hydrographic conditions mainly in response to climatic fluctuations during humid subtropical periods widespread during the deposition of the tipton shale member and laney member the lakes were p edominantly open meromictic systems with rivers entering the basin from the north these environmental conditions were modified during deposition of the wilkins peak member as the climate became more arid and along the southern margin of the basin shallow saline alkaline playa lakes formed in response to these changes the widespread occurrence in the subsurface of fluvial clastic sequences of the wasatch formation associated with the wilkins peak member would indicate that the playa lakes were frequently flooded and freshened by southern drainage systems therefore the lakes were continuously undergoing modifications under the influence of climatic and possibly tectonic processes a composite model is supported that combines aspects of both the meromictic and playa lake models beca se of these complexities it is unlikely that one modern lake can serve as an analog for ancient lake gosiute

changes in coiling direction of cibicidoides pseudoacutus nakkady across the cretaceous tertiary boundary of tunisia palaeoecological and biostratigraphic implications abstract the analysis of coiling direction preference in the benthic foraminifera cibicidoides pseudoacutus nakkady has been carried out across the cretaceous tertiary boundary k t boundary from four tunisian sections representing a palaeobathymetric transect from a middle outer neritic to lower upper bathyal depositional setting our study reveals that c pseudoacutus developed a preference for sinistral coiling in a short time period during the lowermost danian the comparison of the coiling ratio number of sinistral vs dextral individuals record with isotope data and dinoflagellate cyst assemblage distribution suggests that the development of sinistrally coiled populations of cibicidoides pseudoacutus might be related to a short term cooling of both surface and bottom waters which occurred at the k t boundary and lasted for some 7 kyr the continuous occurrence and the high abundance of cibicidoides pseudoacutus through the k t boundary in neritic to upper bathyal depositional environments around southern tethys make identification of the shift in its coiling ratio relatively easy the development of a sinistrally coiled population in this benthic foraminiferal species is regarded as a potential marker for the base of planktonic foraminiferal zone p0 in tethyan shallow water settings

the 2011 magnitude 9 0 tohoku oki earthquake mosaicking the megathrust from seconds to centuries geophysical observations from the 2011 moment magnitude m w 9 0 tohoku oki japan earthquake allow exploration of a rare large event along a subduction megathrust models for this event indicate that the distribution of coseismic fault slip exceeded 50 meters in places sources of high frequency seismic waves delineate the edges of the deepest portions of coseismic slip and do not simply correlate with the locations of peak slip relative to the m w 8 8 2010 maule chile earthquake the tohoku oki earthquake was deficient in high frequency seismic radiation a difference that we attribute to its relatively shallow depth estimates of total fault slip and surface secular strain accumulation on millennial time scales suggest the need to consider the potential for a future large earthquake just south of this event

trace elements stable isotopes and clay mineralogy of the elles ii k t boundary section in tunisia indications for sea level fluctuations and primary productivity abstract trace elements and stable isotopes in bulk rocks and foraminifera bulk rock and clay mineral compositions are used as palaeoproxies to evaluate sea level fluctuations climatic changes and variations in primary productivity across the k t transition at elles ii in tunisia from 1 m 33 kyr below to 1 m 70 kyr above the k t boundary results on clay minerals major and trace elements stable isotopes in bulk rock samples e g ca cu zn rb sr zr ba 13c and 18o and in foraminifera sr ca 13c 18o indicate that the latest maastrichtian last 33 kyr in tunisia was marked by a relatively warm but humid climate and a rising sea level the transgressive surface is marked by deposition of a foraminiferal packstone just below the k t boundary followed by maximum flooding across the k t boundary red layer and black clay layer humid warm conditions accompanied the maximum flooding along with increased total organic carbon values and rapidly decreasing primary productivity at the k t boundary an impact event ir anomaly ni rich spinels spherules exacerbated already stressed environmental conditions leading to the mass extinction of tropical planktic foraminifera increasingly more humid conditions prevailed within the lowermost danian zone p0 50 kyr culminating in a sea level lowstand near the top of p0 a slow recovery of the ecosystem in zone p1a coincided with a rising sea level and gradually less humid climatic conditions

adaptive regularization of earthquake slip distribution inversion abstract regularization is a routine approach used in earthquake slip distribution inversion to avoid numerically abnormal solutions to date most slip inversion studies have imposed uniform regularization on all the fault patches however adaptive regularization where each retrieved parameter is regularized differently has exhibited better performances in other research fields such as image restoration in this paper we implement an investigation into adaptive regularization for earthquake slip distribution inversion it is found that adaptive regularization can achieve a significantly smaller mean square error mse than uniform regularization if it is set properly we propose an adaptive regularization method based on weighted total least squares wtls this approach assumes that errors exist in both the regularization matrix and observation and an iterative algorithm is used to solve the solution a weight coefficient is used to balance the regularization matrix residual and the observation residual an experiment using four slip patterns was carried out to validate the proposed method the results show that the proposed regularization method can derive a smaller mse than uniform regularization and resolution based adaptive regularization and the improvement in mse is more significant for slip patterns with low resolution slip patches in this paper we apply the proposed regularization method to study the slip distribution of the 2011 mw 9 0 tohoku earthquake the retrieved slip distribution is less smooth and more detailed than the one retrieved with the uniform regularization method and is closer to the existing slip model from joint inversion of the geodetic and seismic data

in search of the latest danian event in a paleobathymetric transect off kasserine island north central tunisia danian lower paleocene sequences in north central tunisia are dominantly composed of marls and shales but a conspicuous indurated glauconite bearing marker bed is associated with the p3a p3b transition this glauconite bed is considered to correlate with the latest danian event lde described from the nile basin in egypt with the top chron c27n event atlantic and pacific oceans and with the cie ds1 zumaia spain the lde is thought to reflect a short period of global warming similar to the paleocene eocene thermal maximum but of lesser magnitude the presence of a glauconitic bed at the p3a p3b transition in tunisia suggests that the sequence is condensed which is confirmed by planktic foraminifer and nannofossil biostratigraphy and by the absence of the typical lde beds found in most egyptian sections benthic foraminiferal assemblages were quantitatively analyzed in three sections in north central tunisia sidi nasseur garn halfaya elles in order to characterize the paleoenvironmental evolution during the late danian and compare this with sections in egypt the benthic foraminiferal assemblages indicate that the tunisian sections were located along a depth and a paleoenvironmental gradient on the shelf north of kasserine island the reconstructed depth range is comparable with sections in egypt and encompasses middle neritic sidi nasseur section to shallow upper bathyal depths elles section with up to 16 gavelinella beccariiformis below the p3a p3b like in egypt assemblage shifts across the p3a p3b subzonal transition indicate shallowing and a transition to a more eutrophic paleoenvironment characterized by relatively high abundances of buliminids and stainforthia sp the 13c and 18o records generated on well preserved specimens of the ostracode species bairdia failed to demonstrate the presence of the carbon isotope excursion cie associated with the lde at the base of subzone p3b a condensed section or a hiatus associated with the glauconite bed would explain why the cie is not recorded in the tunisian sections

modern dolomite deposition in continental saline lakes western victoria australia microcrystalline dolomite forms a major constituent of holocene sediments of numerous continental saline playa lakes in southeastern australia the lake waters are highly supersaturated with respect to dolomite as well as other mg carbonates but undersaturated or near saturation with respect to calcite and aragonite the dolomite shows no replacement textures and most likely formed by direct precipitation conditions in these lakes that appear conducive to the precipitation of dolomite are 1 high salinity 2 high mg ca ratios and 3 high alkalinity the moderate sulfate levels of the brines do not seem to be inhibiting carbonate precipitation

the 2010 mw 8 8 maule megathrust earthquake of central chile monitored by gps large earthquakes produce crustal deformation that can be quantified by geodetic measurements allowing for the determination of the slip distribution on the fault we used data from global positioning system gps networks in central chile to infer the static deformation and the kinematics of the 2010 moment magnitude m w 8 8 maule megathrust earthquake from elastic modeling we found a total rupture length of 500 kilometers where slip up to 15 meters concentrated on two main asperities situated on both sides of the epicenter we found that rupture reached shallow depths probably extending up to the trench resolvable afterslip occurred in regions of low coseismic slip the low frequency hypocenter is relocated 40 kilometers southwest of initial estimates rupture propagated bilaterally at about 3 1 kilometers per second with possible but not fully resolved velocity variations

benthic foraminiferal assemblages between two major extinction events the paleocene el kef section tunisia abstract the development of benthic foraminiferal assemblages from the paleocene outcrops of the el haria formation near el kef tunisia is discussed qualitatively and quantitatively the aim of the study is to reconstruct the paleoenvironmental evolution between the k pg boundary interval and the late paleocene event and to compare this evolution with results from other sites along the southern tethyan margin eighty four samples covering virtually the entire paleocene provide a dataset that allows detailed qualitative and multivariate analysis the benthic foraminiferal faunas indicate a complex pattern of environmental changes during the paleocene marked by the succession of different benthic associations following the k pg boundary event community restoration was characterized by the gradual build up of faunal diversity decreasing dominance and the entry of taxa common to normal marine outer neritic to upper bathyal environments indicate the completion of the ecosystem restoration in zone plb a highly diverse benthic foraminiferal assemblage persisted throughout the remainder of the early paleocene into the earliest late paleocene at the p3a p3b zonal transition relative sea level lowering is evidenced by the sudden disappearance or decreasing abundance of deeper water taxa e g anomalinoides affinis a susanaensis gavelinella beccariiformis neritic deposition continued into zone p4 when trophic levels at the seafloor increased as indicated by the entry and increasing dominance of species such as anomalinoides cf aegyptiacus bulimina midwayensis and b strobila which we consider to be sensitive to eutrophication the combined effect of shallowing and the subsequent eutrophication led to the establishment of assemblages similar to late paleocene benthic foraminiferal assemblages from egyptian sections some of which record the latest paleocene extinction event these assemblages were interpreted to be indicative of a middle neritic highly eutrophic environment enhanced vertical fluxes of organic matter along the southern tethyan margin may have resulted from intensified upwelling this eventually led to oxygen deficiency at the seafloor it appears that oxygen deficient high productivity shelves were a common feature of the southern tethyan margin during the latest paleocene

petrology of two tertiary oil shale deposits from queensland australia sediments from two queensland tertiary lacustrine oil shale deposits the lowmead and duaringa basins have been petrologically characterized from standard x ray powder diffraction analyses backscattered electron microscopy and electron microprobe data the results presented illustrate the potential of backscattered electron imagery for the study of diagenesis in fine grained organic rich sediments the lowmead formation consists of lamosites claystones and brown coals deposited in freshwater lacustrine and fringing peat swamp environements their dominant constituents are kaolinite and quartz with opaline silica and siderite important as eogenetic phases despite its similar geological setting the duaringa formation contains a more varied lithological assemblage with less organic matter being preserved freshwater lacustrine claystones and lamosites are interbedded with carbonate sediments deposited during periods of saline alkaline conditions in the lake within these carbonate sediments major growth of eogenetic mineral phases occurred principally dolomite and analcite as in the lowmead basin siderite is an important eogenetic phase in the duaringa formation two types of sideritic ironstone band occur throughout both basins sphaerosiderites within claystone coal sediments and fine grained bands of siderite within lamosites the bulk mineralogy of the siliciclastic detritus shows no significant trends with depth within either basin

paleoproductivity from benthic foraminifera abundance glacial to postglacial change in the west equatorial pacific surface productivity is correlated with the rate of accumulation of benthic foraminifera on the deep sea floor as a rule of thumb for each 1 mg of organic carbon arriving at the sea floor one benthic foram shell 150 m is deposited the correlation can be used to reconstruct organic flux to the sea floor in the past and hence the productivity of past oceans applying the appropriate equations to box core data from the ontong java plateau in the western equatorial pacific we found that productivity during the last glacial maximum exceeded present productivity by a factor of between 1 5 and 2 0 with intermediate values for the mid transition period accumulation of benthic foraminifera was depressed on top of the plateau during the glacial and transitional period presumably because increased winnowing removed part of the food supply

joint time frequency domain inversion of reflection data for seabed geoacoustic profiles and uncertainties this paper develops a joint time frequency domain inversion for high resolution single bounce reflection data with the potential to resolve fine scale profiles of sediment velocity density and attenuation over small seafloor footprints approximately 100 m the approach utilizes sequential bayesian inversion of time and frequency domain reflection data employing ray tracing inversion for reflection travel times and a layer packet stripping method for spherical wave reflection coefficient inversion posterior credibility intervals from the travel time inversion are passed on as prior information to the reflection coefficient inversion within the reflection coefficient inversion parameter information is passed from one layer packet inversion to the next in terms of marginal probability distributions rotated into principal components providing an efficient approach to partially account for multi dimensional parameter correlations with one dimensional numerical distributions quantitative geoacoustic parameter uncertainties are provided by a nonlinear gibbs sampling approach employing full data error covariance estimation including nonstationary effects and accounting for possible biases in travel time picks posterior examination of data residuals shows the importance of including data covariance estimates in the inversion the joint inversion is applied to data collected on the malta plateau during the scarab98 experiment

seabed roughness parameters from joint backscatter and reflection inversion at the malta plateau this paper presents estimates of seabed roughness and geoacoustic parameters and uncertainties on the malta plateau mediterranean sea by joint bayesian inversion of mono static backscatter and spherical wave reflection coefficient data the data are modeled using homogeneous fluid sediment layers overlying an elastic basement the scattering model assumes a randomly rough water sediment interface with a von karman roughness power spectrum scattering and reflection data are inverted simultaneously using a population of interacting markov chains to sample roughness and geoacoustic parameters as well as residual error parameters trans dimensional sampling is applied to treat the number of sediment layers and the order zeroth or first of an autoregressive error model to represent potential residual correlation as unknowns results are considered in terms of marginal posterior probability profiles and distributions which quantify the effective data information content to resolve scattering geoacoustic structure results indicate well defined scattering roughness parameters in good agreement with existing measurements and a multi layer sediment profile over a high speed elastic basement consistent with independent knowledge of sand layers over limestone

the impact of paleocene eocene boundary events on middle neritic benthic foraminiferal assemblages from egypt abstract a 25 m upper paleocene to lower eocene marly sequence exposed at gebel duwi quseir red sea coast of egypt provides a good opportunity for studying paleocene eocene p e boundary stratigraphy and events various bio eco and isotope stratigraphic correlations accurately delineate the position of the p e boundary i e the level of stable isotopic excursions and deep sea benthic extinctions in the middle part of this section within zones p5 and np9 in this paper the impact of p e boundary environmental perturbations on benthic foraminiferal communities of the shallow tethyan shelf is examined benthic foraminiferal assemblages from gebel duwi characterized by large frondicularia phosphatica and f nakkadyi in addition to a number of other neritic taxa but without any typical outer neritic bathyal taxa suggest middle neritic 75 100 m deposition throughout the studied interval and only minor relative sea level variations perhaps some 10 20 m across the boundary sea level appears to have been stable yet a distinct faunal turnover marks the p e boundary of this shallow site which in contrast to deep sea records is less abrupt being preceded by a gradual diversity decrease starting some four meters below the boundary moreover most exits are either local or just temporary and thus not true extinctions many lazarus taxa reappear at some point above the boundary while all but one of the disappearing taxa are known from other lower eocene neritic deposits in egypt in general benthic foraminiferal assemblages display low diversities and high dominance values notably anomalinoides aegyptiacus up to 74 suggesting high levels of environmental stress at the sea floor in combination with occasionally very high p b ratio s up to 98 p and generally laminated sediments the character of the benthic assemblage points to a strong influence of recurrent dysoxia and or anoxia we suggest that these resulted from surface eutrophication by intermittent coastal upwelling and reduced ventilation of the bottom environment although these conditions prevailed during most of the time interval studied they were most severe during the latest paleocene and early eocene when eutrophication intensified and the organic carbon flux to the sea floor increased enhanced atmospheric contrasts between the tethys seaway and the african continent resulting in intensified longshore tradewinds may have controlled these changes at the p e boundary the bottom environment became minimally ventilated perhaps due to reduced oxygen advection from deeper waters three meters above the boundary a succession of increasingly diverse assemblages indicate a gradual decrease of environmental stress and a return to more normal conditions although the organic carbon flux to the sea floor remained high

paleoproductivity the benthic planktonic ratio in foraminifera as a productivity index abstract when the effects of differential dissolution are excluded the benthic to planktonic ratio in deep sea foraminifera can be read as a productivity index for pelagic conditions we use the bz index which is the product of the benthic planktonic ratio in percent and the depth of deposition which controls supply of organic matter for hemipelagic conditions we use bz d which is the product of the bz value and a factor for proximity to the shore square root of distance from land which controls coastal productivity anomalous values readily stand out from the normal populations which cluster around typical values of bz or bz d off northwest africa wherever calcite dissolution can be excluded as a factor because of presence of aragonite these anomalies are due to lateral supply of redeposited organic matter

simple and reliable finite fault solutions for large earthquakes using the w phase the maule m w 8 8 and tohoku m w 9 0 earthquakes 1 we explore the ability of w phase waveform inversions to recover a first order coseismic slip distribution for large earthquakes to date w phase inversions for point sources provide fast and accurate moment tensor solutions for moderate to large events we have applied w phase finite fault inversion to seismic waveforms recorded following the 2010 maule earthquake mw 8 8 and the 2011 tohoku earthquake mw 9 0 firstly a w phase point source inversion was performed to assist us in selecting the data for the finite fault solution then we use a simple linear multiple time window method accounting for changes in the rupture velocity with smoothing and moment minimization constraints to infer slip and rake variations over the fault our results describe well the main features of the slip pattern previously found for both events this suggests that fast slip inversions may be carried out relying purely on w phase records

the depth dependency of planktonic benthic foraminiferal ratios constraints and applications abstract study of the ratio between planktonic and benthic foraminifera in a great number of areas shows that variation of this ratio with depth can be described using organic matter flux equations essentially the share of benthic foraminifera in the total association is inversely proportional to depth as is the amount of organic matter resulting from primary productivity reaching the sea bottom variation in the p b ratio from area to area appears to be strongly dependent on the amount of inbenthic living foraminifera if the ratios are corrected for this the regressions between the proportion of planktonic foraminifera p and depth appear to be near identical in the gulf of mexico the gulf of california the west coast of the usa and the adriatic sea this regression can be described by depth e 3 58718 0 03534 p a study of the behaviour of this function in nine cores from the adriatic upper quaternary reveals that the palaeodepth reconstructions are not influenced by fluctuations in productivity and temperature but that they are significantly influenced by redeposition of fine grained deposits

time lapse imaging of coseismic ruptures for the 2019 ridgecrest earthquakes using multiazimuth backprojection with regional seismic data and a 3 d crustal velocity model

primary and diagenetic carbonates in the anoxic sediments of lake bosumtwi ghana cores of organic rich muds from the tropical meteorite crater lake bosumtwi ghana contain laminae of authigenic calcite polyhedra and aragonite needles as well as scattered diagenetic calcite mg calcite spherulites and aggregates of dolomite crystals their respective origins are traced by analyses of oxygen and carbon stable isotopes anoxic dolomite and mg calcite formed in pore waters reflecting highest degrees of evaporative concentration and high rates of methanogenesis carbon dioxide reduction must have been the dominant methanogenic pathway producing diagenetic carbonates with delta sup 13 c values up to 27 pdb this example shows the inherent problems of interpreting bulk samples with progressive mineralogical sequences of calcite to mg calcite to aragonite to dolomite merely in terms of mg sup 2 ca sup 2 in lake waters it provides a model for the interpretation of ancient lacustrine carbonates from organic rich environments

inversion of strong ground motion and teleseismic waveform data for the fault rupture history of the 1979 imperial valley california earthquake a least squares point by point inversion of strong ground motion and teleseismic body waves is used to infer the fault rupture history of the 1979 imperial valley california earthquake the imperial fault is represented by a plane embedded in a half space where the elastic properties vary with depth the inversion yields both the spatial and temporal variations in dislocation on the fault plane for both right lateral strike slip and normal dip slip components of motion inversions are run for different fault dips and for both constant and variable rupture velocity models effects of different data sets are also investigated inversions are compared which use the strong ground motions alone the teleseismic body waves alone and simultaneously the strong ground motion and teleseismic records the inversions are stabilized by adding both smoothing and positivity constraints the moment is estimated to be 5 0 10 25 dyne cm and the fault dip 90 5 dislocation in the hypocentral region south of the united states mexican border is relatively small and almost dies out near the border dislocation then increases sharply north of the border to a maximum of about 2 m under interstate 8 dipslip motion is minor compared to strike slip motion and is concentrated in the sediments the best fitting constant rupture velocity is 80 per cent of the local shear wave velocity however there is a suggestion that the rupture front accelerated from the hypocenter northward the 1979 imperial valley earthquake can be characterized as a magnitude 5 earthquake at the hypocenter which then grew into or triggered a magnitude 6 earthquake north of the border

imaging short period seismic radiation from the 27 february 2010 chile mw 8 8 earthquake by back projection of p pp and pkikp waves 1 teleseismic short period 0 5 5 s p waves from the 27 february 2010 chile earthquake mw 8 8 are back projected to the source region to image locations of coherent short period seismic wave radiation several receiver array configurations are analyzed using different p wave arrivals including networks of stations in north america p japan pkikp and europe pp as well as a global configuration of stations with a broad azimuthal distribution and longer period p waves 5 20 s coherent bursts of short period radiation from the source are concentrated below the chilean coastline along the downdip portion of the megathrust the short period source region expands bilaterally with significant irregularity in the radiation comparison with finite fault slip models inverted from longer period seismic waves indicates that the regions of large slip on the megathrust are located updip of the regions of short period radiation a manifestation of frequency dependent seismic radiation similar to observations for the great 2011 tohoku earthquake mw 9 0 back projection of synthetic p waves generated from the finite fault models demonstrates that if the short period energy had radiated with the same space time distribution as the long period energy back projection analysis would image it in the correct location updip we conclude that back projection imaging of short period signals provides a distinct view of the seismic source that is missed by studies based only on long period seismic waves geodetic data and or tsunami observations

geodetic data inversion using a bayesian information criterion for spatial distribution of fault slip summary we developed a new inversion method to reconstruct static images of seismic sources from geodetic data using akaike s bayesian information criterion abic coseismic surface displacements are generally related with a slip distribution on a fault surface by linear integral equations parametric expansion of the fault slip distribution by a finite number of known basis functions yields a set of observation equations expressed in a simple vector form incorporating prior constraints on the smoothness of slip distribution with the observation equations we construct a bayesian model with unknown hyperparameters the optimal values of the hyperparameters which control the structure of the bayesian model are objectively determined from observed data by using abic once the values of hyperparameters are determined we can use the maximum likelihood method to find the optimal distribution of fault slip we examined the validity of this method through a numerical experiment using theoretical data with random noise we analysed geodetic data associated with the 1946 nankaido earthquake ms 8 2 by using this method the result shows that the fault slip distribution of this earthquake has two main peaks of 4 and 6 m located off kii peninsula and muroto promontory these two high slip areas are clearly separated by a low slip zone extending along kii strait such a slip distribution corresponds with the fact that the rupture process of this earthquake in the western part is notably different from that in the eastern part

remote sensing of sediment density and velocity gradients in the transition layer the geoacoustic properties of marine sediments e g bulk density and compressional velocity commonly exhibit large variations in depth near the water sediment interface this layer termed the transition layer is typically of o 10 1 100 m in thickness depth variations within the transition layer may have important implications for understanding and modeling acoustic interaction with the seabed including propagation and reverberation in addition the variations may contain significant clues about the underlying depositional or erosional processes characteristics of the transition layer can be measured directly e g coring or remotely remote measurements have the advantage of sampling without disturbing the sediment properties they also have the potential to be orders of magnitude faster and less expensive than direct methods it is shown that broadband seabed reflection data can be exploited to remotely obtain the depth dependent density and velocity profiles in the transition layer to high ac

the campanian paleoenvironment inferences based on benthic foraminifera from northeastern iran abstract the benthic foraminifera from the campanian rocks globotruncanita elevata to globotruncana aegyptiaca zones exposed in the kopeh dagh basin northeast iran are studied quantitatively to reconstruct the campanian paleoenvironment based on unconstrained heriarchial clustering nonmetric multidimensional scaling nmds and analysis of similarity anosim three statistically significant benthic foraminiferal assemblages are noted paralabamina lunata lower and upper haplophragmoides spp and gyroidinoides nitida based on benthic foraminiferal marker species the following paleodepths are assigned lower p lunata upper bathyal upper p lunata upper middle bathyal boundary haplophragmoides spp and g nitida outer neritic the p lunata assemblage can be further subdivided into a lower coryphostoma incrassata dominated interval whereas the upper interval is p lunata dominated and reflects a change in the quality of food the upper experienced higher input of fresh phytodetritus the overall p lunata assemblage reflects a stable bottom water environment the haplophragmoides spp assemblage is characterized by reduced paleoproductivity and environmental instability whereas the g nitida assemblage is marked by increasing oligotrophy within a well oxygenated bottom water and ventilated basinal conditions the partial least squares regression yielded significant correlations with planktic positive proxy for sea level and agglutinated species negative proxy for shallow depths and low organic flux the reduced major axis regression models also yielded significant negative correlations with agglutinated and infaunal species nutrient availability suggesting that these factors were responsible for the inferred benthic foraminiferal distribution patterns two globally comparable shallowing trends are also noted one in the middle of the r calcarata zone haplophragmoides spp assemblage and the other in the g aegyptiaca zone gyroidinoides nitida assemblage that coincide with kca6 and kca7 sequence boundaries and lowstands respectively for the kca6 event the occurrence of spiroplectammina haplophragmoides spp assemblage represents a shallow water outer neritic fauna invasion event within a deeper upper bathyal setting paralabamina lunata assemblage and for the kca7 event a similar shallowing from upper middle bathyal boundary to outer neritic depths is noted g nitida assemblage and attributed to eustasy and basinal paleohighs and lows

biotic turnover in benthic foraminifera across the cretaceous tertiary boundary at el kef tunisia abstract the cretaceous tertiary boundary section exposed near el kef tunisia is the most complete boundary sequence known to date it contains nearly 1 m of black and gray boundary clay containing planktic foraminiferal zone poa b 2 m of clayey shales of p1a globigerina eugubina zone and 4 m of shales and marls of p1b g taurica zone quantitative analysis of the benthic foraminiferal fauna suggests that deposition during the latest cretaceous occurred in an upper slope to outer shelf environment which shallowed at the k t boundary to an outer to middle shelf depth and shallowed further by p1b time to mid shelf depth a major reduction in benthic diversity occurred near the k t boundary with about 50 of the fauna disappearing diversity remained an average of 37 lower during deposition of the first 3 m of sediment above the boundary poa b p1a and productivity was very low surviving and thriving foraminifers during this interval were primarily low oxygen tolerant epifaunal and infaunal species a sharp decrease in the low oxygen tolerant fauna and appearance of a shallow mid shelf fauna at about 4 m above the boundary p1b zone signals a second regression return to higher oxygen levels and higher productivity although the environmental effects of the k t boundary event can be inferred from benthic faunas the ultimate cause remains elusive faunal changes prior to and the long recovery period after the k t boundary are difficult to explain by a single impact hypothesis