validating earth and ocean tide models using tidal gravity measurements summary o1 and m2 observations from well calibrated spring gravimeters and superconducting gravimeters from the global geodynamics project ggp are used to test models of the earth s body tide and 10 ocean tide models it is shown that some of the ocean tide models give anomalous results in various parts of the world for example the schwiderski ocean tide model gives discrepancies in several areas and the fes series of ocean tide models have problems in the western pacific china japan and australia the majority of the high quality tidal gravity measurements in europe are in close agreement with the dehant defraigne and wahr ddw elastic and inelastic body tide models the gravimetric factors for the ddw elastic and inelastic models only differ by 0 12 per cent and the present calibration accuracy does not allow us to distinguish between these models but does reduce the previous upper bound on inelastic gravimetric factors the european observations give a phase lag of a few hundredths of a degree for the o1 body gravity tide which is consistent with the mathews inelastic body tide model at some european and worldwide stations the gravimetric factors differ by up to 0 3 per cent from the ddw model and it is suggested that further checks on the gravimeter calibrations are required accurate determinations of instrumental phase lags are now easier to achieve and the imaginary out of phase component of tidal gravity can be used for accurate tests of this component of ocean tide models

petrological and organic geochemical investigation of recent peats with known environments of deposition abstract a series of recent peat samples from tropical sub tropical and temperate locations were investigated using coal petrographical and organic geochemical techniques maceral and biomarker compositions were examined to see if they correlated or diverged from the known environment of deposition of the peats the proportion of humotelinite was related to the water depth and the frequency of dry periods the ph and trophic level have a modifying influence on the preservation of tissues furthermore the proportions of sclerotinite in the peats seem to reflected the oxygen status in the mire which was also mirrored in the abundance of humic and fulvic acids a facies diagram was calculated for the peat samples to see how maceral indices would fare in interpreting their known environments of deposition the results proved to be generally unsuccessful as the herbaceous and woody peats did not always give the predicted high humodetrinite and humotelinite compositions respectively the aliphatic hydrocarbon fraction from the extracts of the peat samples show that mainly odd numbered n alkanes are present diterpenoids triterpenoids and hopanoids were found in most samples and were mainly unsaturated in nature the relative proportion of hopanoids in pears appears to be related to bacterial activity in acidic environments de a triterpenoids were also detected in the peat stage of diagenesis in an angiosperm dominated peat type mariscus polycyclic aromatic triterpenoids were present in the aromatic fraction of the extract their occurrence and proportion appears to be related to the degree of humification in a taxodium peat mono di and triaromatic diterpenoids were detected the presence of these aromatic biomarkers indicate the rapid formation of these compounds in the peat stage mainly mediated by microbial activity

intercomparison of recent ocean tide models one of the tremendous achievements of the topex poseidon t p satellite mission is the release of 12 new global ocean tide models during 1994 virtually all of these models are based on the high precision altimetry obtainable from the t p satellite and all of the models are superior to both the cartwright and ray 1990 1991 model as well as to the schwiderski 1980a b model when compared to tide gauges in the present intercomparison only global ocean tide models released during 1994 have been tested as t p continues to operate new ocean tide models will continue to be released and existing ocean models will be updated hence this intercomparison can only present a snapshot of the state of the art within ocean tide modeling however the intercomparison demonstrates the high accuracy and consistency of all these recent ocean tide models from a comparison with a common 104 tide gauge data set compiled by le provost and others unpublished data the general result is that six of the new ocean tide models have rms agreement better than 3 cm the obtainable accuracy with different tide gauge types raises the question about the accuracy of ground truth as ocean tide models become increasingly more accurate the accuracy of the harmonic constants derived from the tide gauge recordings becomes significant generally the rms agreement between models based on 2 years of t p altimetry is significantly better than the agreement between models based on 1 year of t p altimetry for models based on two years of t p altimetry the rms agreement has values around 2 0 1 4 1 0 and 0 7 cm for the m2 s2 k1 and o1 constituents respectively as a preliminary evaluation these values might be taken as a measure of the consistency of ocean tides estimated from the first part of the t p mission which is extremely promising for future ocean tide models derived from t p altimetry using 3 or more years of data this also suggests that further improvement using 3 or more years of data will only be marginal the differences arise when studying the ocean tides on continental shelves surrounding the ocean major differences are seen especially on the patagonian shelf as the continental shelves are critical for tidal dissipation it will be very important to improve tide models on the shelves in future global ocean tide models

vegetation zones and diagnostic pollen profiles of a coastal peat swamp bocas del toro panama abstract a survey of the dominant vegetative cover of a large domed coastal swamp near changuinola in the province of bocas del toro panama has been undertaken as an initial step in reconstructing the holocene history of peat accumulation on this coast seven phasic communities of peat forming vegetation are defined and mapped 1 rhizophora mangle mangrove swamp 2 mixed back mangrove swamp 3 raphia taedigera palm swamp 4 mixed forest swamp 5 campnosperma panamensis forest swamp 6 sawgrass stunted forest swamp 7 myrica cyrilla bog plain pollen extracted from surface peat samples and collected from dominant vegetation at representative sites is used to prepare a pollen profile of each phasic community these profiles are then compared to pollen distribution in 2 peat cores one from the deep central part of the deposit and the second from a site near the marine margin in order to construct a history by floral succession of the 4000 year evolution of the deposit the changuinola mire originated as freshwater palm and hardwood forest swamps that developed in close proximity to both the changuinola river mouth probably behind a barrier bar and freshwater lagoon system adjacent to a low energy mangrove dominated bay the early swamp was likely drained to the southeast by brackish blackwater creeks much as it is today and formerly extended considerably farther in the direction of almirante bay the palm swamp was succeeded by hardwood forest swamp dominated by a very limited number of specialized species only one of which campnosperma panamensis is prone to forming monospecific stands increasing accumulation of woody peat promoted by the everwet climate impeded drainage of the mire leading to doming increased oligotrophy and establishment of bog plain conditions in a manner similar to that described by the anderson model of succession in the coastal swamps of malaysia and indonesia development of the changuinola mire did not require the initial mangrove phase which is common to the peat swamps of southeast asia as the palm raphia taedigera is able to colonise and institute peat accumulation in a variety of freshwater and brackish environments

geotechnical and geophysical characteristics of muskeg samples from alberta canada abstract a series of laboratory tests have been performed to explore the geotechnical and geophysical characteristics of fibrous muskeg i e grassy bog using undisturbed block samples obtained from alberta canada the basic index properties of muskeg show similar values to the reference data for other organic soils and they significantly differ from those of typical inorganic soils due to high organic content muskeg has high water content high compressibility and high initial permeability the effective stress and porosity play a major role in controlling the stress dependent geophysical properties of shear wave velocity real permittivity and electrical conductivity the values of peak drained friction angle obtained in the direct shear tests are in the range of 26 to 51

accuracy assessment of recent ocean tide models over 20 global ocean tide models have been developed since 1994 primarily as a consequence of analysis of the precise altimetric measurements from topex poseidon and as a result of parallel developments in numerical tidal modeling and data assimilation this paper provides an accuracy assessment of 10 such tide models and discusses their benefits in many fields including geodesy oceanography and geophysics a variety of tests indicate that all these tide models agree within 2 3 cm in the deep ocean and they represent a significant improvement over the classical schwiderski 1980 model by approximately 5 cm rms as a result two tide models were selected for the reprocessing of topex poseidon geophysical data records in late 1995 current ocean tide models allow an improved observation of deep ocean surface dynamic topography using satellite altimetry other significant contributions include theft applications in an improved orbit computation for topex poseidon and other geodetic satellites to yield accurate predictions of earth rotation excitations and improved estimates of ocean loading corrections for geodetic observatories and to allow better separation of astronomical tides from phenomena with meteorological and geophysical origins the largest differences between these tide models occur in shallow waters indicating that the current models are still problematic in these areas future improvement of global tide models is anticipated with additional high quality altimeter data and with advances in numerical techniques to assimilate data into high resolution hydrodynamic models

facies in the lower kittanning coal bed appalachian basin u s a abstract facies changes in the form of maceral and palynomorphic composition and textures are observed in thin sections and polished sections both vertically and horizontally in the lower kittanning coal bed allegheny formation middle pennsylvanian westphalian d over a large area in western pennsylvania u s a the lower half of the coal bed is characterized by abundant well defined telocollinate and thin walled lycopod spores which are interbedded with thin layers of mixtures of clearly outlined inertodetrinite and vitrodetrinite the uppermost layer in places where the coal is thought to be influenced by marine conditions is characterized by a densosporerich desmocollinite with abundant inertinite cluster quasigelifusinite the transitional layers between the lower half and the uppermost layer are dominated by fine grained vitrinite with disseminated spores of distinctive shape and size punctatisporites sp and schopfites sp in many places a clay or mineral rich parting with abundant alginite fragmented megaspores and clay filled microspores are also observed in the transitional layers any layer composed of unique plant assemblage a plant community representing a specific environment in time and space is termed a phytostrome the unique association of macerals is termed a lithotype five genetic lithotypes are recognized kittosite herbosite klastosite arborosite and allosite representing 1 brackish 2 transitional 3 limnic 4 freshwater arboreous and 5 reworked peat respectively the accumulation of the last phase of the lower kittanning coal appears to have been influenced by a transgressive sea

enhancement of sub daily positioning solutions for surface deformation monitoring at deception volcano south shetland islands antarctica deception island is one of the most visited places in antarctica there are biological geological and archeological features that are major attractions within port foster its horse shoe shaped natural inner bay and two scientific bases that are occupied during austral summers deception island is an active volcano however and needs to be monitored in order to reduce risk to people on the island surface deformation in response to fluid pressure is one of the main volcanic activities to observe automated data acquisition and processing using the global navigation satellite systems allow measurements of surface deformation in near real time nevertheless the positioning repeatability in sub daily solutions is affected by geophysical influences such as ocean tidal loading among others such periodic influences must be accurately modeled to achieve similar repeatability as daily solutions that average them however a single solution each 24 h will average out the deformation suffered during that period and the position update waiting time can be a limitation for near real time purposes throughout the last five austral summer campaigns in deception using simultaneous wireless communications between benchmarks a processing strategy was developed to achieve millimeter level half hourly positioning solutions that have similar repeatability as those given by 24 h solutions for these half hourly solutions a tidal analysis was performed to assess any mismodeling of ocean tide loading and a discrete kalman filter was designed and implemented to enhance the sub daily positioning repeatability with these solutions the volcano dynamic activity resulting in localized surface deformation for the last five austral summer campaigns is addressed although based on only three carefully located benchmarks it is shown that deception has been shortening and subsiding during these last 4 years the method s accuracy in baselines up to a few hundred kilometers assures its applicability to other volcanoes worldwide

accumulation of organic rich sediments in a dendritic fluvial lacustrine mire system at tasik bera malaysia implications for coal formation abstract the tasik bera mire system represents deposition of peat and peaty sediments within a dendritic fluvial drainage basin in the humid tropics as such it serves as an analogue for the earliest stages of coal deposition in low relief topogenous coal swamps peaty sediments have been accumulating for at least 4500 years in the lowest part of the basin but accumulation rates and hence the thickness and lateral extent of the mire underwent a rapid increase and expansion beginning at about 660 years b p the sediments are highly variable both vertically and laterally the variations principally controlled by the type of vegetation dominant vegetation in turn is related to the degree of wetness of the site three distinct environments of deposition contribute peat with physical characteristics which can be related to coals the limnetic environment dominated by algae and easily degraded aquatic macrophytes contributes very fine hemic peaty sediment with high fine silt content and a large algal component the littoral environment is dominated by sedges and the woody shrub pandanus both of which have a large subaqueous biomass and are quite resistant to degradation sediment from this environment is woody hemic to coarse hemic with a moderate to high very fine silt content and a much smaller algal element forest swamps which occupy most of the mire area contribute woody fibric to hemic peaty sediments with low to moderate mineral matter content in the form of clays and very fine silt succession from both limnetic to forest swamp and the reverse is recorded in cores from different sites in coals these transitions would be manifest as both brightening upward algaedominated peat to woody peat and dulling upward the reverse sequence trends the first in the topographically lower part of the basin the second in the middle reaches no part of the mire yet studied is approaching oligotrophic conditions allowing for a compression ratio of 5 1 thin stony coals from the tasik bera mire would be laterally discontinuous and would vary from about 1 m in thickness at channel margins tapering out to nothing as they onlap the interfluves

itrf2000 a new release of the international terrestrial reference frame for earth science applications 1 for the first time in the history of the international terrestrial reference frame the itrf2000 combines unconstrained space geodesy solutions that are free from any tectonic plate motion model minimum constraints are applied to these solutions solely in order to define the underlying terrestrial reference frame trf the itrf2000 origin is defined by the earth center of mass sensed by satellite laser ranging slr and its scale by slr and very long baseline interferometry its orientation is aligned to the itrf97 at epoch 1997 0 and its orientation time evolution follows conventionally that of the no net rotation nnr nuvel 1a model the itrf2000 orientation and its rate are implemented using a consistent geodetic method anchored over a selection of itrf sites of high geodetic quality ensuring a datum definition at the 1 mm level this new frame is the most extensive and accurate one ever developed containing about 800 stations located at about 500 sites with better distribution over the globe compared to past itrf versions but still with more site concentration in western europe and north america about 50 of station positions are determined to better than 1 cm and about 100 sites have their velocity estimated to at or better than 1 mm yr level the itrf2000 velocity field was used to estimate relative rotation poles for six major tectonic plates that are independent of the trf orientation rate a comparison to relative rotation poles of the nuvel 1a plate motion model shows vector differences ranging between 0 03 and 0 08 m y equivalent to approximately 1 7 mm yr over the earth s surface itrf2000 angular velocities for four plates relative to the pacific plate appear to be faster than those predicted by the nuvel 1a model the two most populated plates in terms of space geodetic sites north america and eurasia exhibit a relative euler rotation pole of about 0 056 0 005 m y faster than the pole predicted by nuvel 1a and located about 10 n 7 e more to the northwest compared to that model

groundwater transformation of a low sulfur to a high sulfur coal the harlem coal of the northern appalachian basin abstract the harlem coal is postulated to have been deposited in raised bog settings it was initially deposited as low sulfur peat but groundwater of a later origin altered portions of it to high sulfur coal the total sulfur content of 172 samples from 31 locations on a moisture and ash free basis have a quadrimodal distribution with two major modes at 0 75 s and 2 0 s multiple sampling and analyses at specific mine sites indicate that the addition of sulfur of a later origin occurred either laterally adjacent to sandstone channels or vertically adjacent to faults significant sulfur addition also occurred above clay partings at these sites the original low sulfur nature is preserved where the coal bed is isolated from descending groundwater by a thick impervious layer trace element analyses show high concentrations of mobile elements such as na and mn in the high sulfur coals

nonlinear and minor ocean tides in the bay of biscay from the strain tides observed by two geodetic laser strainmeters at canfranc spain this work presents and discusses the tidal analysis of about 2 5 years of strain data recorded by two 70 m long high resolution laser strainmeters which are operating in the canfranc underground laboratory central pyrenees spain spectra show clear tidal peaks whose frequencies range from the diurnal band to at least 8 cycles per day strain amplitudes relative change in length for each strainmeter range from few 10 12 to 10 8 the reliability of observations and corrections for local distortions are testified by the excellent agreement between measurements and computations for all the diurnal and semidiurnal tides included in the tpxo8 and fes2012 tidal atlases with the exception of l2 observed higher frequency strain tides are mostly attributed to loading by nonlinear shallow water constituents in the bay of biscay more than 120 km from the measurement site the signals are quantitatively compared with computations using tpxo8 mn4 m4 and ms4 and fes2012 m3 n4 mn4 m4 ms4 and m6 computations fully agree with m4 observations for one strainmeter overestimate m4 by about 30 for the other strainmeter and m6 by about a factor of two and underestimate the other tides this work shows that data from high sensitivity strainmeters installed in high quality sites may provide valuable additional information for studying the nonlinear tidal dynamics and energetics of coastal waters and minor ocean tides at spatial resolutions of tens to thousands square kilometers depending on the strainmeter location with respect to the coastline

discussion on the concepts in paleoenvironmental reconstruction from coal macerals and petrographic indices abstract organic facies analyses quantify the coal constituents and plot various associations to discriminate the paleoenvironment for coal bearing successions this allows the relation of coal composition to mire ecosystems or environments coal petrographic models are used extensively to reconstruct the nature of ancient peat forming environments many authors proposed relations between specific maceral assemblages and or micro lithotypes and peat forming environments the key controlling factors which affect peat environment include hydrogeology redox ph vegetation type clastic influx sedimentation and peat accumulation rate etc recent advancements in coal maceral study and organic petrology reveal the pros and cons of the available indices and models the main reasons for the failure of the petrographic models are oversimplification of the effects of humification on tissue preservation vs destruction the use of post diagenetic processes e g geochemical gelification in determining depositional environments changes in petrographic composition related to floral evolution geological age rank increase and compaction lack of distinction between different inertinite maceral in some models here the widely used petrographic indices and models are reviewed based on the observations of several workers and the applicability and concepts of paleo environmental reconstruction are discussed a multi disciplinary approach including petrography palynology chemistry etc has been recommended which is more logical and scientific than the exclusive use of petrographic composition for paleoenvironmental interpretation

slip distribution beneath the central and western himalaya inferred from gps observations summary underthrusting of the indian plate beneath the himalaya has been the cause of many hazardous thrust faulting earthquakes along the arc moderate earthquakes with magnitudes of 5 occur frequently in this region releasing the elastic strain accumulated over many years around the plate boundary these events can be attributed to slip deficits where the indian and eurasian plates are locked during interseismic periods geodetic measurements can help discriminate the distribution of the interlocking areas and the steadily slipping areas beneath the himalaya to understand the deformation across the central and western himalaya and the associated slip on thrust faults campaign mode gps data were collected in the garhwal kumaun region of the western himalaya gps sites velocities show that the deformation is currently concentrated between the lesser and higher himalaya horizontal velocities are used to estimate the slip distribution for the estimation a model of the interseismic surface deformation caused by buried non uniform creep dislocation nuc on a curved fault surface is used the slip distribution shows that there might be structural discontinuity on the fault between the kumaun and garhwal regions of the himalaya the estimated slip rate at the depth around 20 40 km in the central himalaya and at the depth of 15 km in the western himalaya is 10 mm yr 1 the nuc model indicates that the shallow part 20 km of the thrust fault system along the plate boundary is almost locked the locking depth appears to be deep in the central himalaya and shallower in the western himalaya further most of the historical large seismic events are observed to have occurred in an area with a slip velocity less than 10 mm yr 1 i e in a locked zone at the plate interface

comparisons of central appalachian carboniferous coal beds by benches and a raised holocene peat deposit abstract three carboniferous age coals from southern west virginia u s a were examined at bench level and compared to a holocene peat deposit the snuggedy swamp south carolina u s a data for all deposits consisted of coal or peat thickness ash content and petrographic composition as well as parting or overlying clastic sediment thickness comparison of coal and parting thickness showed an inverse relationship in all cases bimodal distribution patterns for coal peat thickness versus area indicate that the transition between areas of extensive thick coal peat and extensive thin coal peat was rapid in the coal deposits at bench level both ash and organic inert content increased toward the transition to thin coal the areas of thick coal contained the highest vitrinite reactive contents and lowest ash values volumetrically this is similar to the distribution of low ash well preserved thick peat occurring in the central raised areas of the snuggedy swamp surrounded by areas of high ash decomposed peat subject to flooding although the depositional environments interpreted for each of the three coal beds and the snuggedy peat deposit differ widely the deposits themselves show similar distribution trends in thickness ash content and petrographic composition

combining organic petrography and palynology to assess anthropogenic impacts on peatlands part 1 an example from the northern everglades of florida abstract wetland peat deposits can be excellent archives of past changes in the depositional and ecological conditions under which they formed part of the story of these changes can be obtained from analysis of the palynomorphs preserved in these deposits however a more meaningful reconstruction can be achieved by combining organic petrography with palynology an example of this approach is presented from a study of three sites in the northern everglades of florida the primary purpose of this study was to test these combined methods for their utility in distinguishing between long term natural successions and recent anthropogenically derived disruptions of the ecosystem such as diversions of drainage and introductions of contaminants from human sources the combined palyno petrographic method supported by 137 cs and 210 pb dating was able to establish with some certainty the first appearance of contaminant driven plant types such as cattails and duckweeds into the region with the organic petrography being more accurate in determining the actual presence of invading plants at a particular site and the palynologic analysis providing a broader picture of regional changes in the ecosystem such as the direction of the plant invasion the distribution of petrographic pyrite in these freshwater peats provided an additional new piece of evidence for contamination from the agricultural lands and also supported other evidence relative to the direction of contaminant infusion into the region additionally the occurrence of significant quantities of pyrite at all three sites suggests that in fact none of these sites can be said to be totally unaffected by anthropogenic contamination longer hydroperiods were generally indicated by both methods for all sites before the early 1900s confirming persistently wetter conditions in the everglades prior to manmade changes in drainage more specific paleohydrologic conditions could also be elucidated by this combined method with all three sites displaying significant differences in hydrologic histories additionally one of the sites is hypothesized to have been until recently in the center of a surface water flow pathway as indicated by the continuous presence at this site of deeper water aquatics such as water lilies and the smaller number of zones containing algal derived carbonates and or other petrographic indicators of oxidation or bioturbation

organic geochemistry of the lower miocene oberdorf lignite styrian basin austria its relation to petrography palynology and the palaeoenvironment abstract in the oberdorf trough at the northwestern margin of the styrian basin austria an up to 36 m thick lower miocene ottnangian lignite seam occurs within the fluvial koflach voitsberg formation previous results indicate that the lignite originated in a topogenous mire within a wet forest swamp palaeoenvironment differences in soluble organic matter som yield of borehole samples from the lignite seam are related to free lipids present in plant waxes or resins and the presence of thermally labile polymers indicated by the contents of liptinite macerals i e resinite suberinite and liptodetrinite the n alkane distribution patterns are dominated by high molecular weight lipids with marked odd over even predominance originating from plant waxes a contribution of algae to the even numbered short chain lipids observed in considerable amounts in the footwall sediments is proposed terpenoid biomarkers characteristic for conifers and angiosperms were detected consistent with palynomorphic spectra which are dominated by forest swamp pollen taxodiaceae cupressaceae and pollen from plants living in a mixed mesophytic forest excellent relationships between higher plant biomarker composition and palynologic data indicate that the organic geochemical results reflect the varying inputs of coniferales vs angiosperms the data further imply that cuparene may be used for taxonomical differentiation of coniferales families organic geochemical data provide evidence that the content of land plant derived biomarkers is controlled by the input of resin rich conifers concentrations of hopanoids dominated by hop 17 21 ene generally increase towards the top of the lignite a section characterised by high extents of aromatisation of triterpenoid biomarkers the results suggest that the aromatisation of angiosperm derived biomarkers may be governed by the activity of anaerobic rather than by aerobic bacteria however changes in the depositional environment and palynologic facies during peat formation probably influenced the origin and fate of angiosperm derived triterpenoids the results indicate how biomarker composition may contribute to the evaluation of environmental changes cross correlations of organic geochemical parameters with palynological data and petrography based facies indicators will provide further insights in the peat forming vegetation and biogeochemical activities in the mire

importance of ocean tidal load corrections for differential insar large time series of interferometric synthetic aperture radar insar measurements make it possible to detect slow tectonic motions of the earth s surface on the order of millimeters per year here we illustrate the importance of correcting insar data for the effects of ground displacements due to ocean tidal loads otl these loads can cause displacement gradients greater than 3 cm per 100 km which is larger than the accuracy of insar techniques and can be a significant percentage of the measured displacement due to slow tectonic processes we demonstrate the importance of otl with predicted displacements from selected regions of tectonic interest

validation of ocean tide models around antarctica using onshore gps and gravity data 1 ocean tide models around antarctica are presently only sparsely tested against independent data ocean tide modeling errors along with subsequent ocean tide loading otl displacement modeling errors alias into altimetry and time variable gravity e g gravity recovery and climate experiment grace time series for example to validate various ocean tide models around antarctica gps data from 15 sites have been used to derive three dimensional displacement estimates at eight diurnal and semidiurnal tidal frequencies using hundreds of days of gps data harmonic parameters were estimated on a daily basis then combined these were then compared with otl displacement estimates derived from global and regional ocean tide models in east antarctica where the tides are well defined submillimeter differences are demonstrated in each coordinate component with the lunar n2 and q1 constituents in closest agreement as found in other studies k1 and especially k2 agree less well the spatial variation in the misfits for these two constituents indicates a site dependency with the k2 errors also suggesting an interaction with satellite dependent effects in west antarctica where sites are nearer the largest ice shelves agreement with the older models csr3 and tpxo 2 and nao 99b is poor for all constituents modeled tidal gravity variations were also compared with gravity measurements at the south pole overall the gps and gravity data agree best with newer tide models namely tpxo 6 cada00 10 fes99 and cats02 01 however validation data are lacking at the southern extents of the large ice shelves and hence some uncertainty still exists in all ocean tide models in these regions

peat accumulating depositional systems of sarawak east malaysia many coal deposits originate in deltaic estuarine and coastal plain settings and a knowledge of interrelationships between the tectonic and depositional elements active at the time of sediment deposition is necessary to formulate basin scale models the prograding coastal depositional systems of sarawak all contain domed peat accumulating environments in which low ash low sulfur peats are being deposited in areas of active clastic siliciclastic sedimentation these depositional systems are as large as 11 400 km2 and individual peat deposits within systems are in excess of 20 m thick and 1000 km2 in area the geographic positions and drainage basin areas of each depositional system are controlled by fault and fold systems although prograding into the same receiving basin individual system geomorphology is variable and ranges from a wave dominated microtidal delta to a wave dominated meso to macro tidal delta coastal plain system to a tide dominated macrotidal estuarine embayment along a 450 km stretch of coastline system variation is a function of sediment supply shelf and embayment geometry wave climate and tidal range these factors which control depositional system geomorphology also control the resulting long axis orientation of the thick domed peat deposits the surface vegetation and internal characteristics of most domed peat deposits however are similar internal characteristics consist of basal high ash high sulfur degraded peats overlain by low ash low sulfur well preserved peats in vertical profile these systems demonstrate variable responses to late pleistocene holocene sea level rise and in these instances the variation is most attributable to local differences in siliciclastic sediment supply which is a function of the drainage basin area

the causes of the high friction angle of dutch organic soils abstract dutch organic soils have been found in past experiments to possess extremely high effective strength parameters since this finding is not expected and the phenomenon has yet to be explained the high yield strength value is not used in practice understanding the abnormal properties of dutch organic soils would thus be beneficial from the practical point of view a programme aimed at understanding the unusual properties of dutch organic soils non peat soils in particular was performed on the representative organic soils in dutch nature reserve park oostvaardersplasen ovp near almere highly variable fabric of these organic soils was characterized by computed tomography x ray scanner and environmental electronic microscope recognized fabric is in line with the geology of the ovp site the multi scale investigation as presented eventually identified the major role played by subhorizontal laminae and other non organic microstructural elements microfossil skeleton in the high values of ovp organic soils deformation mechanisms of the microstructural elements are proposed and these make the unusual geotechnical properties explainable organics as involved were believed to have a primary contribution in increasing atterberg limits and compressibility and to allow the generation of high pore water pressures and low effective confining pressures during shearing it has been also observed that high value is always correlated to the low effective confining pressure

spatial variability in modern tropical peat deposits from sarawak malaysia and sumatra indonesia analogues for coal petrographic and chemical variability in two tropical low ash domed peat deposits of similar age and physiographic setting but different external morphology were examined as modern analogues for coal both occur in microtidal alluvial to deltaic plain settings support similar arborescent vegetation and have accumulated in the past 5 000 years one deposit is an extremely convex mature done with a surface that rises 10 m above river level the other is a low gradient dome rising only 3 m above river level but with a concave base up to 6 m below both deposits have been eroded by adjacent rivers yet peat in the mature dome has accumulated remote from persistent flooding and exhibits distinctive internal stratigraphy decomposed sapric peat floors the deposits and is overlain by increasingly better preserved woody hemic and a cap of coarse fibrous peat derived from less arborescent vegetation consistent flooding in the low gradient dome has maintained conditions for the accumulation of predominantly woody hemic peat which interfingers with and is overlain by oxidised sapric peat and levee derived clastic sediments peat types in both deposits exhibit distinctive polymodal textures and organo chemical signatures that correspond to botanical input and degree of decay due to the abundance of pre huminite vitrinite macerals in all peat types from these deposits megascopic and microscopic texture is a better discriminator for comparison to ancient coal types it is suggested that the upward vertical sequence of decreasing woodiness and increasing lightness in colour observed in the mature dome might best be compared to sequences observed in tertiary brown coals this typical sequence can be modified or overprinted due to flooding in the burial process

review and update of the applications of organic petrology part 1 geological applications abstract organic petrology developed as coal petrology at the beginning of the 20th century dedicated mainly to the study of coals because of their utilization in industry coal petrology was then considered a branch of coal science later with the development of specialized nomenclature classification of coal components and the standardization and improvement of analytical microscopical methods this discipline expanded in interests and name becoming organic petrology organic petrology carries a broader context being as well a tool applied in the study of dispersed organic matter in sedimentary rocks due to its importance in exploration for fossil fuel resources at present organic petrology is a discipline widely recognized for its role in fundamental and applied research with respect to both coal utilization and in geosciences throughout the 20th century several important monographs have been published on the discipline of organic petrology including stach s textbook of coal petrology 1st edition 1935 2nd 1975 3rd 1982 updated as the more general organic petrology by taylor et al 1998 more recently the text applied coal petrology the role of petrology in coal utilization was published by suarez ruiz and crelling 2008 this review is the first in a two part review series that describes and updates the role of organic petrology in geosciences a second part complementing this one and focused on the applications of organic petrology to other scientific fields will follow

a microstructural investigation of osaka bay clay the impact of microfossils on its mechanical behaviour a recent microstructural investigation of osaka bay clay sediments has revealed the presence of abundant microfossils particularly in the marine layers which appear to influence directly the micr

crustal displacements due to continental water loading the effects of long wavelength 100 km seasonal variability in continental water storage on vertical crustal motions are assessed the modeled vertical displace ments arm have root mean square rms values for 1994 1998 as large as 8 mm with ranges up to 30 mm and are predominantly annual in character regional strains are on the order of 20 nanostrain for tilt and 5 nanostrain for hori zontal deformation we compare arm with observed global positioning system gps heights aro which include ad justments to remove estimated effects of atmospheric pres sure and annual tidal and non tidal ocean loading for 147 globally distributed sites when the aro time series are ad justed by arm their variances are reduced on average by an amount equal to the variance of the arm of the aro time series exhibiting a strong annual signal more than half

geodetic tools for hydrogeological surveys 3d displacements above a fractured aquifer from gps time series deep porous reservoirs are subject to charge and discharge of fluids oil gas or water either naturally or induced by human exploitation this leads to a variation in pressure inside the reservoir and consequently to a deformation of the overlying material the knowledge of the ground surface displacements allows inferring the fluid migrations and the hydromechanical properties in the porous reservoir different kinds of geodetic tools are able to measure this ground deformation gps radar interferometry insar tiltmeters or leveling each of them has its own spatial and time characteristics and accuracies that conduct to different kind of applications after a review of the geodetic studies applied to hydrogeological processes we describe two examples of gps time series measurements above the granitic fractured aquifer of ploemeur located in french brittany these time series records the 3d displacements induced by the sum of different processes in this site the involved processes are mainly the ground deformation related to piezometric level variations in the aquifer that we are looking for and the ocean tide loading that can reach several centimeters in the study area we present the protocol of the gps data survey and the processing strategy applied to extract the effect of hydrogeological process with sufficient accuracy two different experiments were studied the long term deformation corresponding to seasonal hydrological cycle and the short term deformation associated to a pumping test for a same variation in piezometric levels the vertical ground displacements show larger amplitude for long term signal than for short one indicating a behavior depending on the duration of the hydrogeological load this difference of reactivity in time can be related to the heterogeneity of the studied aquifer finally this work shows that geodetic measurements provide important constraints for characterizing aquifer system response

a new global mode of earth deformation seasonal cycle detected we have detected a global mode of earth deformation that is predicted by theory precise positioning of global positioning system sites distributed worldwide reveals that during february to march the northern hemisphere compresses and the southern hemisphere expands such that sites near the north pole move downward by 3 0 millimeters and sites near the equator are pulled northward by 1 5 millimeters the opposite pattern of deformation occurs during august to september we identify this pattern as the degree one spherical harmonic response of an elastic earth to increased winter loading of soil moisture snow cover and atmosphere data inversion shows the load moment s trajectory as a great circle traversing the continents peaking at 6 9 1022 kilogram meters near the north pole in winter indicating interhemispheric mass exchange of 1 0 1016 0 2 1016 kilograms

provenance and sediment dispersal in the rajang river delta coastal plain system sarawak east malaysia preliminary sedimentologic investigations were conducted in the rajang river delta coastal plain system in sarawak east malaysia to determine the processes and timing of siliciclastic transport and sedimentation in tropical peat dominated systems methods involved depth profiling and collection and analysis of bottom and suspended sediment load samples from channels and offshore areas and coring and trenching of subaerial channel shoreline and backswamp features the rajang delta occurs in an embayment formed by the folded mesozoic and cenozoic sediments of the central borneo massif it covers an area of 11 000 km2 and is physiographically separated into an alluvial valley floodplain an abandoned tidally flushed delta plain and an actively accreting rectilinear delta coastal plain from 50 to 80 of the surface area is covered by peat 1 to 20 m thick during the dry season of july august 1992 river channels varying from 2 to 45 m deep with discharge rates from 100 to approximately 3550 m3 s were carrying suspended sediment loads ranging from 0 to 2281 mg l at present approximately 8 2 x 10 10 kg yr of fine grained sediment is supplied to the system and areal accretion rates are over 1 0 km2 yr the structural configuration of the uplands receiving basin and subsequent drainage patterns and tidal influence results in a contradictory distribution of mature fine grained sediments in the channels of the active delta coastal plain and immature coarse grained angular sands and gravels in the channels of the abandoned delta lobe the contemporaneity of the peat and clastic accumulation is evidenced by the margins of the thick domed low ash peat deposits interfingering with and being overlain by root penetrated siliciclastic sediments much of the fine grained sediment however bypasses the delta plain due to in channel density gradients delta coastal plain accretion occurs by distributary mouth bar buildup sand bar welding and ridge and runnel accretion all subaerially exposed surfaces are quickly vegetated the aberrant depth and configuration of some channels suggest that drainage is in part controlled by contemporaneous faulting

nloadf a program for computing ocean tide loading the loading of the earth by the ocean tides produces several kinds of signals which can be measured by geodetic technique in order to compute these most accurately a combination of global and local models of the ocean tides may be needed the program nloadf convolves the green functions for loading with ocean tide models using a station centered grid with fixed dimensions making it easy to combine different ocean models without overlap in the convolution the program computes all the quantities of interest gravity displacement tilt and strain and includes the case where measurements are made beneath the surface of the ocean

the geology botany and chemistry of selected peat forming environments from temperate and tropical latitudes abstract peat has been studied in several geologic settings 1 glaciated terrain in cold temperate maine and minnesota u s a 2 an island in the atlantic ocean off the coast of maine where sea level is rising 3 the warm temperate u s atlantic and gulf coastal plains where sea level has changed often and 4 the tropical coast of sarawak malaysia and the tropical delta of the batang hari river sumatra indonesia most of these deposits are domed ombrotrophic or partly ombrotrophic bogs in which peat accumulation continued above the surface of the surrounding soil however the bogs of the u s atlantic and gulf coastal plains are comparatively not as domed and many have almost level surfaces in some bogs aquatic or semi aquatic plant materials accumulated replaced water in the depressions and formed a surface on which marsh or swamp vegetation could subsequently live die and accumulate in others the plant materials accumulated initially on level silt or sand surfaces supporting marshes or swamps as the peat dome formed plants growing on it changed from luxuriant ones near the base of the dome where nutrients were brought into the bog by surface and ground water to stunted ones at the top of the dome where the raised bogs are fed by nutrient poor precipitation the physical and chemical changes that take place in the sequence of environments from the pond stage of deposit development through the grassy marsh stage through the forested swamp stage and finally through the heath dome stage can be measured in terms of acidity and ash volatile matter carbon hydrogen nitrogen sulfur and oxygen contents as well as in the kind and distribution of trace elements the organic and inorganic contents of the deposits relate to geomorphology and geomorphology relates to their settings as models of coal formation some domed peat deposits may help in solving problems of distribution and character of ancient coal beds but clearly not all peat deposits are precursors of coal most holocene peat deposits are subject to destruction by erosion fire and decomposition through microbial and chemical oxidation before burial the best environments for coal precursors have biomass accumulation a continuously rising water table within the mass and minimum influx of clay and silt until preservation by burial the most suitable settings for future economic coal deposits are domed bogs that accumulate thick widespread peat having low ash and low sulfur contents the ombrotrophic peat deposits of tropical sarawak and sumatra are thick and extensive contain low ash and low sulfur peat and have high heating values they are considered to be the best tropical coal analogs because of their extent and chances of preservation the base of the peat is below adjacent river levels and chemical and structural conditions are favorable for accumulation

occurrence and distribution of sulfur in peat forming environments of southern florida abstract cores and surface samples of peats from the everglades mangrove region of southern florida were analyzed for total sulfur and pyritic sulfur these values were compared with the petrographic botanical components of the peats as determined from point counts of oriented microtome sections pyrite occurs as individual euhedral crystals loosely packed framboids and lenses or crusts of minute crystals framboids and minute crystals are often associated with organic matter and sometimes with bacteria and fungi pyrite tends to selectively occur in void spaces in or between peat tissues in samples containing very small amounts of pyrite framboidal pyrite is the prevalent form marine to brackish peats contain the highest pyrite and total sulfur contents with brackish peats generally containing more pyrite than marine peats pyrite tends to be lower in all peats within 30 cm of the surface whether marine or brackish burial of freshwater peats beneath marine or brackish peats tends to increase the total sulfur and pyritic sulfur in the underlying peats burial beneath brackish water clay rich deposits such as splays tends to increase total sulfur and pyritic sulfur in the underlying deposits more than burial beneath less clay rich deposits

lithotype maceral composition and variation as correlated with paleo wetland environments gates formation northeastern british columbia canada abstract lithotype samples collected from mid albian gates formation coal seams in northeastern british columbia were analysed in order to gain a better understanding of coal facies variation compositional boundaries between lithotypes are gradational from bright to dull coals there is a progressive decrease in vitrinite and increase in inertinite liptinite is negligible

modelling the engineering behaviour of fibrous peat formed due to rapid anthropogenic terrestrialization in hangzhou china abstract peat is a very variable but normally weak material while engineering failures involving peat are common the full diversity of engineering behaviours exhibited by peat has not been well classified due to its large range of possible compositions this paper presents the behaviour of a fibrous peat which is a fill made ground originating from the most recent dredging of the west lake a site of cultural and historic importance in china given its relatively unique mechanism of deposition the distinctive characteristics of this peat are presented in comparison to other peats reported in the literature highlighting its unique engineering behaviour a laboratory study carried out on the peat at jiangyangfan eco park located in hangzhou china identifies that it has its special aspects when compared to other peats the shearing behaviour of peat can be described using the framework of critical state theory the most prominent characteristic of the west lake peat is that its undrained stress path bends towards the left at the very beginning of shearing which indicates that plastic deformation occurs at very small stress ratios a constitutive model based on critical state theory for predicting the undrained shear behaviour of this type of peat from low stress to critical state levels is presented this model also includes several elements of peat behaviour previously reported and it may therefore be applied to a wider range of peat soils

coal petrology and the origin of coal macerals a way ahead the development of coal petrology and the establishment of a nomenclatural system have proved of major use both for the industrial utilization of coal and for the development of a broad understanding of coal formation and diagenesis the development over the past 30 years however of nomenclature that includes aspects of plant origin and process is a retrograde step e g pyrofusinite degradofusinite and funginite equally problematic is the use of prescriptive formulae to indicate coal origins this paper reviews some of the problems involved with coal petrology as it is usually practiced in addition new advances in organic geochemical techniques have led to a fuller understanding of the relationship of plants and coal macerals recent research on the origin of coal macerals is presented and there is a discussion of the problems and challenges facing coal petrologists a holistic approach to studies of the origin of coal and coal macerals which includes not only petrographic but also chemical and biological studies is advocated d 2002 elsevier science b v all rights reserved

the changuinola peat deposit of northwestern panama a tropical domed back barrier coal forming environment abstract a large approximately 82 km2 low ash low sulfur peat deposit has formed on the northwestern coast of panama fig 1 its low ash and sulfur contents can be attributed partly to 1 doming 2 the occurrence of a marine blocking beach barrier shoreline feature and 3 leaching of the mineral matter the coal seam formed by this deposit would be roughly rectangular in shape and oriented with its longest axis parallel to the beach barrier shoreline it would be bright and finely banded in its thickest central region and more coarsely banded at its margins its northwestern margin would be characterized by interfingering of coal with sandstones and siltstones of the changuinola river flood plain whereas its southeastern boundary would be characterized by truncation of the upper part of the seam and replacement with marine to brackish bay rocks total sulfur was found to be very low less than 0 2 dry wt except in a few places in these rare cases nearly all of the sulfur was pyritic and the total sulfur content was anomalously light approximately 14 although the general tendency was for total sulfur to increase wherever the deposit was influenced by marine conditions one case was found where the sulfur was high a the base of an inland freshwater core suggesting the need for a new mechanism to explain sulfur enrichment in such a case differences in inherent fixed carbon and btu contents due to changes in peat type tended to mask seam wide trends in these parameters however fixed carbon and btu showed a slight tendency to increase with depth especially if plotted for single peat types vitrinite reflectance within the hypothetical changuinola coal seam can be predicted to increase toward the margins of the deposit toward the bottom and top of the seam and toward stream channels or tidal inlets a detailed description of this deposit and discussion of its relevance to coal genesis can be found in cohen et al 1989

tidal observations on floating ice using a single gps receiver 1 we measure ocean tides as experienced by sea ice or ice shelves using a single gps receiver such a method allows for tidal measurements to be made with the same precision regardless of its distance from a gps base station since such a base station is not required single epoch observations are shown to be accurate to about 50 mm when compared with concurrent bottom pressure gauge bpg observations the differences between the gps and bpg observations are largely free from power at tidal frequencies furthermore harmonic tidal analyses show that these gps observations allow the correct determination of diurnal and semi diurnal tidal constituents meaning that observations of this type can be assimilated into numerical tide models

ocean tide loading displacements in western europe 2 gps observed anelastic dispersion in the asthenosphere gps observed vertical ocean tide loading displacements show in cornwall southwest england and in brittany northwest france discrepancies of 2 3 mm with predicted values based on the isotropic preliminary reference earth model for the main tidal harmonic m2 yet in central europe the agreement is better than 0 5 mm by comparison of ocean tide models and validation with tide gauge observations we demonstrate that the uncertainties in the former are too small to cause this disagreement furthermore we find that different local models of the crust and different global elastic reference models derived from seismological observations can only reduce the observed discrepancies to 1 2 mm which still exceeds the gps observational uncertainty of 0 2 0 4 mm it is customary to use the elastic properties of the earth as given by seismic models previously there has been insufficient evidence to determine how to modify these properties during the transformation from seismic to tidal frequencies to account for possible anelastic dispersion in the asthenosphere and so this effect has been ignored if we include this effect then our discrepancies reduce further to 0 2 0 4 mm this value is of the same order as the sum of the remaining errors due to uncertainties in the ocean tide models and in the gps observations themselves this research provides evidence in western europe of a reduction of around 8 10 of the seismic shear modulus in the asthenosphere at tidal frequencies in addition we find that the asthenosphere absorption band frequencies can be represented by a constant quality factor q

carrier phase ambiguity resolution for the global positioning system applied to geodetic baselines up to 2000 km the global positioning system gps carrier phase data are biased by an integer number of cycles a successful strategy has been developed and demonstrated for resolving these integer ambiguities for geodetic baselines of up to 2000 km in length resulting in a factor of 3 improvement in baseline accuracy and giving centimeter level agreement with coordinates inferred by very long baseline interferometry in the western united states for this experiment a method using pseudorange data is shown to be more reliable than one using ionospheric constraints for baselines longer than 200 km an automated algorithm exploits the correlations between the many phase biases of a gps receiver network to enable the resolution of ambiguities for very long baselines a method called bias optimizing has been developed which unlike traditional bias fixing does not require an arbitrary confidence test bias optimizing is expected to be preferable to bias fixing for poorly configured networks in order to enable ambiguity resolution for long baselines it is recommended that future gps networks have a wide spectrum of baseline lengths ranging from 1000 km and that gps receivers be used which can acquire dual frequency p code data

ocean tide loading displacements in western europe 1 validation of kinematic gps estimates gps has been extensively used to estimate tidal ground displacements but the accuracy of this has not been systematically verified using more than 20 sites distributed across western europe we show that postprocessed kinematic precise point positioning gps with appropriately tuned process noise constraints is capable of recovering synthetic tidal displacements inserted into real data with a typical accuracy of 0 2 mm depending on the time series noise the kinematic method does not result in erroneous propagation of signals from one coordinate component to another or to the simultaneously estimated tropospheric delay parameters it is robust to the likely effects of day to day equipment and reference frame changes and to outages in the data a minimum data span of 4 years with at least 70 availability is recommended finally we show that the method of reducing apparent coordinate time series noise by constraining the tropospheric delay to values previously estimated in static batch gps analysis in fact results in the suppression of true tidal signals using our kinematic gps analysis approach periodic displacements can be reliably observed at the 0 2 mm level which is suitable for the testing and refinement of ocean tide and solid earth response models

peat or no peat why do the rajang and mahakam deltas differ abstract coastal and deltaic holocene peat accumulations around the equatorial island of borneo southeast asia have served as models for economic coal bearing sequences in the stratigraphic record although climatic conditions vegetational communities and sedimentary regimes are comparable peat accumulations are not found on both the western and eastern sides of the island the rajang river delta and coastal plain sarawak east malaysia are covered in areally extensive thick peat deposits that have attained at least a thickness of 13 m in ombrogenous peat domes marudi baram river peat swamp biomass began to accumulate over pleistocene podzols when sea level stabilized 7 5 ka and delta progradation was initiated the mahakam river delta and coastal plain east kalimantan indonesia also began progradation at this time but there is no evidence in any part of the coastal region for peat accumulation rather poorly developed organic rich gleysols occur throughout the delta plain both the rajang river and mahakam river deltas are tidally influenced fine grained systems with a sediment provenance in the central massif sediment transported through the rajang river delta differs in that as much as 60 of the clay minerals deposited in the system are mixed layer i s and expandable k e clays that act to restrict pore water flow in the tidal and overbank deposits that comprise the delta plain these result in the development of an aquiclude above which paludal conditions develop promoting accumulation of organic matter in contrast there is a low proportion of mixed layer and expandable clays transported in the mahakam river system this precludes the development of a stilted water table within the delta allowing for organic matter recycling without peat accumulation the presence of a high proportion of expandable clay minerals on the western side of borneo is a reflection of the weathering and eroding source rocks on this side of the central borneo massif

global mapping functions for the atmosphere delay at radio wavelengths i have developed expressions for calculating the ratios mapping functions of the line of sight hydrostatic and wet atmospheric path delays to their corresponding zenith delays at radio wavelengths for elevation angles down to 3 the coefficients of the continued fraction representation of the hydrostatic mapping function depend on the latitude and height above sea level of the observing site and on the day of the year the dependence of the wet mapping function is only on the site latitude by comparing with mapping functions calculated from radiosonde profiles for sites at latitudes between 43 s and 75 n the hydrostatic mapping function is seen to be more accurate than and of comparable precision to mapping functions currently in use which are parameterized in terms of local surface meteorology when the new mapping functions are used in the analysis of geodetic very long baseline interferometry vlbi data the estimated lengths of baselines up to 10 400 km long change by less than 5 mm as the minimum elevation of included data is reduced from 12 to 3 the independence of the new mapping functions from surface meteorology while having comparable accuracy and precision to those that require such input makes them particularly valuable for those situations where surface meteorology data are not available

gps estimates of ocean tide loading in nw france determination of ocean tide loading constituents and comparison with a recent ocean tide model summary ocean loading effects cause 3 d displacements large enough to affect space geodesy measurements either at the subdiurnal periods or at longer time scales by the means of spurious signals gps measurements in turn could provide local improvements of the models in coastal areas if their ability to precisely monitor such rapid displacements is assessed in this paper we use 105 days of continuous gps measurements collected in 2004 in the french brittany and cotentin region to investigate 1 the precision achieved by the gps analysis on measuring 3 d subdiurnal displacements and amplitude and phase of the tidal constituents 2 the quality of the most recent ocean tide model fes2004 in such a complex coastal context indeed in this area tide amplitudes are among the largest in the world up to 16 cm of loading displacements on the vertical component and are believed to show strong shallow water tides from a state of the art gps analysis using the scientific gamit software over 2 h sessions we test two independent strategies for the realization of the reference frame the position time series are then compared with the displacements predicted by the fes2004 model applied on an elastic earth model the two sets of results are consistent with each other at the same level of agreement than with the predicted displacements namely 3 5 mm on the horizontal components 10 mm on the vertical this assesses the capability of this technique for measuring 3 d ocean tide loading deformation we validate the fes2004 model in the brittany area even though it slightly 2 7 mm underestimates the three components amplitudes with a harmonic analysis of the observed position time series we obtain nevertheless an agreement at a submillimetre level for the m2 n2 o1 q1 tidal constituents and at a millimetre level for the k1 and s2 tidal constituents moreover we can extract a significant m4 load signal at the 95 per cent confidence level from the gps time series at the stations located in the mont st michel area the detection of other shallow water constituents would be helpful to understand the amplitude deficit between the fes2004 predicted and gps observed displacements

geochemical and petrographical characteristics of a domed bog nova scotia a modern analogue for temperate coal deposits a freshwater domed bog in nova scotia canada was investigated for its petrographic mineralogical and geochemical characteristics three cores were taken from the lagg zone margin and centre to examine different stages of evolution in a fen to domed bog sequence based on this study a model was developed which shows the relationship between factors controlling peat geochemistry and petrography all of them being dependent on trophic conditions the bog may represent a modern analogue for temperate coal deposits and thus can be used to help understand spatial variability within coal beds rheotrophic conditions in the early stages of mire development result in the formation of high ash highly humified carex dominated peat while the evolution toward ombrotrophic conditions is reflected in a progressive replacement by low ash and well preserved sphagnum dominated peat the associated decrease in ph reflects a decrease of groundwater influence which is also supported by the mineralogical assemblage and petrographic data decrease in reflectance and change in maceral composition except for cl br i and se which are associated with the organic fraction variations in elemental composition can be explained in terms of mineral matter abundance i e decrease upward and with increasing distance from the margin sea spray is the most probable origin for halogen enrichment in the peat

compressibility and creep of a diatomaceous soil abstract diatomaceous soils are composed by a mix of sand fines and fossilized diatoms which are unicellular microalgae composed by a strong silica frustule of 10 to 100 m in size with rough surface and enclosing a void that could give the soil a very low dry density due to high water storage capacity within frustules diatomaceous soils present high liquid limit and classifies as high plastic silt mh in classical soil mechanics low density and high plasticity are properties associated to very soft soils however previous studies have reported that diatomaceous soils could mobilize high shear strength and present relatively high yield stress due to large diversity of natural diatomaceous soils in nature their geotechnical singularities are still not fully understood and reported data on undisturbed samples remain scarce in this paper a laboratory experimental study is presented on a diatomaceous soil from mejillones bay in northern chile focused on compressibility and creep microscopic observations and mineralogical analyses indicate that the soil contains siliceous diatom frustules of 10 to 60 m in size which gives the soil a very low dry density and high natural water content compression tests on undisturbed samples results in yield stress much higher than the overburden pressure high contrast between compressibility before and after yielding and significant creep strains the diatomaceous soil does not follow empirical correlations typically used in soil mechanics and is significantly more compressible than fine soils with similar geotechnical classification qualitative microscopic observations after compression show that a large amount of frustules have crushed which probably explains the high compressibility of the soil

geotechnical characterization of soft soil deposits in northern poland abstract this paper presents a geotechnical characterization of deltaic soft soil deposits in the vistula marshlands northern poland it shows the limited applicability of organic soil classifications based on cone penetration tests cptu and dilatometer tests dmt none of the in situ based classifications correctly identifies peat analysis of the behaviour of contractive dilative soil layers according to robertson s updated classification 2016 is shown to be in agreement with volumetric changes observed during triaxial compression tests the coefficient of primary compression cc is found to decrease exponentially with the initial bulk density d0 and to increase linearly with the in situ water content wc the presented geotechnical characterization and reference data can be used for foundation design and soil improvement in the soft organic soils of northern poland

aliased tidal signatures in continuous gps height time series 1 coordinate time series are often derived from continuous gps data processed as discrete 24 hour solutions under this regimen residual semi diurnal and diurnal crustal tide signatures are under sampled resulting in aliased periodic signals in the coordinate time series a secondary aliasing effect well known from satellite altimetry studies but generally ignored in gps analysis arises from the repeat period of the satellite orbits being longer than the nyquist period of the semi diurnal and diurnal tidal signatures this paper derives the theoretical periods for these two aliasing effects for the principal semi diurnal and diurnal tidal constituents the presence of both types of aliased signals in gps time series is then demonstrated using simulated gps data and also considered for time series derived from real gps data it is shown that the beating of the two aliased signals invariably results in spurious signatures in the time series with semi annual and annual periods

slow slip events in mexico revised from the processing of 11 year gps observations 1 the world s largest observed slow slip events sse occurred in 2001 2002 and 2006 in the guerrero subduction zone mexico using an improved gps processing that accounts for time varying atmospheric phenomena as well as oceanic atmospheric and hydrologic loading corrections the 11 year gps position time series in guerrero show a noise reduction of 50 with respect to previous studies thanks to the improved position time series and in particular the simultaneous analysis of the three dimensional gps observations we can provide new information about sses in the studied area first we detect seven nonperiodic anomalous displacements with subcentimeter amplitude but no quasi annual anomalies as proposed previously the displacements seem to occur simultaneously with the observed peaks of non volcanic tremor activity in the area second we refine the characteristics of the two major sses in terms of timing duration and cumulative displacements and highlight the complex surface spatiotemporal evolution of the displacements during these sses in particular we observe a clear initiation phase for the 2006 sse as well as ending phases for both large sses the ending phase shows a strong deceleration of the anomalous displacements with respect to the main displacement phase already observed for the 2001 2002 and 2006 sses the duration of the sses increases by 30 40 including the initiation and ending phases for the 2006 sse the main displacement phase also shows spatiotemporal complexity our results demonstrate the need for improved three dimensional gps processing technique in order to undertake detailed studies of sses

the tidal displacement field at earth s surface determined using global gps observations 1 we investigate the 3 d tidal displacement field on earth s surface recorded globally by 456 continuous global positioning system gps stations of igs spanning 1996 2011 for eight principal diurnal and semidiurnal tidal constituents in phase and quadrature amplitudes of the residual tidal displacements after removal of an a priori body tide model are estimated using the precise point positioning ppp technique on the daily gps data the resultant daily estimates are combined to derive final estimates for each tide at each station the results are compared with the predictions of eight recent global ocean tide models separately for coastal 307 and inland 149 stations we show that gps can provide tidal displacement estimates accurate to the level of 0 12 mm horizontal and 0 24 mm vertical for the lunar only constituents m2 n2 o1 and q1 and less favorably for solar related tidal constituents s2 k2 k1 and p1 although improved by ambiguity resolution most recent ocean tide models fit the gps estimates equally well on the global scale but do not agree well between them in certain coastal areas especially for the vertical displacements suggesting the existence of model uncertainties near shallow seas the tidal residuals for the inland stations after removing both body tides and ocean tidal loading otl furthermore show clear continental scale spatial coherence implying deficiencies of the a priori body tide modeling in catching lateral heterogeneity in elastic as well as inelastic properties in the earth s deep interior we assert that the gps tidal displacement estimates now achieve sufficient accuracy to potentially provide constraints on the earth s structure

cordaiteans in paleotropical wetlands an ecological re evaluation abstract cordaiteans in cordaite dominated permineralized peat from pennsylvanian coals in iowa have been reconstructed as mangroves using root anatomy peat taphonomy and geochemical data macrofloral palynofloral and conodont biostratigraphy indicate that these peats come from the latest atokan blackoak coal and earliest desmoinesian cliffland coal mid moscovian both in the kalo formation thus their depositional setting can be used to evaluate the mangrove hypothesis in recent mires thick mangrove peats have accumulated in tropical to subtropical carbonate systems in contrast thick tropical freshwater peats have accumulated in siliclastic systems kalo formation coals which we interpret as freshwater deposits formed in siliciclastic depositional settings similar to those of modern tropical freshwater peat and to other pennsylvanian coals in north america interpreted as freshwater deposits in the late atokan and earliest desmoinesian mid moscovian cordaiteans and tree ferns predominated in the western interior and illinois basins lycopsids and cordaiteans predominated in the appalachian and donets basins the scarcity of lycopsid only mires in north america during the late atokan earliest desmoinesian mid moscovian suggests drier climates than during the mid to late desmoinesian late moscovian rather than indicating mangrove swamps cordaite dominated peat may indicate climates with a low rain season although most plants in cordaite dominated peat probably grew in freshwater coastal mires in climate zones with seasons of low rain may harbor mangrove taxa the changuinola swamp of panama a modern peat accumulating wetland that has a low rain season is a possible analog of ancient cordaite dominated mires in changuinola most plants require freshwater however mangroves sustained by salt water influx into the swamp grow along the seaward edge and along blackwater creeks the low rain season hypothesis has implications for understanding rainfall amount and continuity during pennsylvanian cyclothem deposition the floral succession in diverse cordaite coals from cordaiteans to tree ferns to lycopsids suggests increasingly wet climate during coal accumulation the position of these coals immediately above the sequence boundary suggests humid climate during early glacial melting for these cyclothems

some observations regarding the potential effects of doming of tropical peat deposits on the composition of coal beds abstract several important concepts relative to the origin of coal beds can be gleaned from studies of modern domed and planar peat deposits in tropical subtropical settings these are 1 laterally some portions of a single continuous peat deposit may be domed and some portions may be planar 2 domed deposits are most often found to have begun as planar deposits 3 domed formed peat facies may be overridden by planar formed peat facies due to such factors as sea level rise and or increased rate of local and basinal subsidence 4 domed peat facies tend to have less mineral matter and contain fewer inorganic splits than planar facies 5 sulfur intrusion from marine waters can be retarded by doming allowing low sulfur peats to form relatively near to the coastline 6 marine transgression can cause high sulfur marine influenced planar peat facies to override freshwater domed or planar facies resulting in enrichment of the upper parts of these underlying facies in sulfur and ash 7 dome formed peat facies tend to be thicker and more uniform in composition than planar formed facies with dome formed peat facies having the potential to produce the more uniform bright coal types clarains and vitrains and planar formed peat facies often producing duller coal types and or alternating durainic inertinite rich and vitrainic wood derived bands 8 actively developing peat domes in wet settings often exhibit no appreciable increase in inertinitic material toward their tops although the tops of either domed or planar peat deposits can be enriched in inertinitic material if the water table is lowered by either local or regional changes in hydrology or climate

the changuinola peat deposit of northwestern panama a tropical back barrier peat coal forming environment abstract a large 82 km 2 thick 8 m low ash low sulfur peat deposit has formed on the northwestern coast of panama its low ash and low sulfur contents can be attributed partly to 1 doming 2 the occurrence of a relatively continuous marine blocking beach barrier shoreline feature and 3 leaching of the mineral matter this deposit is roughly rectangular in shape and oriented with its longest axis parallel to the beach barrier shoreline it would produce an economic coal bed that is bright and finely banded in its thickest central region and more coarsely banded at its margins its northwestern margin would be characterized by interfingering of coal with sandstone and siltstone of the changuinola river flood plain whereas its southeastern boundary would be characterized by truncation of the upper part of the seam by marine to brackish shales siltstones and carbonates that were derived from almirante bay total sulfur was found to be very low less than 0 2 dry wt except in a few places in these rare cases nearly all of the sulfur was pyritic and the total sulfur content was anomalously high 14 although the general tendency was for total sulfur to increase wherever the deposit was influenced by marine conditions one case was found where sulfur was high at the base of an inland freshwater peat core which suggests either a hidden marine influence or the need for some new mechanism to explain sulfur enrichment in such an anomalous case differences in inherent fixed carbon contents and calorific values due to changes in peat type and analytical uncertainties tended to mask seamwide trends in these parameters however fixed carbon contents and calorific values showed a slight tendency to increase with depth especially if plotted for single peat types vitrinite reflectance within the hypothetical changuinola coal bed would be expected to increase as follows 1 toward the margins of the deposit 2 toward the bottom and top of the bed and 3 toward stream channels or tidal inlets

probing asthenospheric density temperature and elastic moduli below the western united states periodic ocean tides continually provide a cyclic load on earth s surface the response to which can be exploited to provide new insights into earth s interior structure we used geodetic observations of surface displacements induced by ocean tidal loads to constrain a depth dependent model for the crust and uppermost mantle that provides independent estimates of density and elastic moduli below the western united states and nearby offshore regions our observations require strong gradients in both density and elastic shear moduli at the top and bottom of the asthenosphere but no discrete structural discontinuity at a depth of 220 kilometers the model indicates that the asthenosphere has a low density anomaly of 50 kilograms per cubic meter a temperature anomaly of 300 c can simultaneously explain this density anomaly and inferred colocated minima in elastic moduli

holocene evolution of the western orinoco delta venezuela the pristine nature of the orinoco delta of eastern venezuela provides unique opportunities to study the geologic processes and environments of a major tropical delta remote sensing images shallow cores and radiocarbon dating of organic remains form the basis for describing deltaic environments and interpreting the holocene history of the delta the orinoco delta can be subdivided into two major sectors the southeast sector is dominated by the rio grande the principal distributary and complex networks of anastomosing fluvial and tidal channels the abundance of siliciclastic deposits suggests that fluvial processes such as overbank flooding strongly influence this part of the delta in contrast the northwest sector is represented by few major distributaries and overbank sedimentation is less widespread relative to the southeast sector peat is abundant and occurs in herbaceous and forested swamps that are individually up to 200 km 2 in area northwest directed littoral currents transport large volumes of suspended sediment and produce prominent mudcapes along the northwest coast mapping of surface sediments vegetation and major landforms identified four principal geomorphic systems within the western delta plain 1 distributary channels 2 interdistributary flood basins 3 fluvial marine transitional environments and 4 marine influenced coastal environments coring and radiocarbon dating of deltaic deposits show that the northern delta shoreline has prograded 20 30 km during the late holocene sea level highstand progradation has been accomplished by a combination of distributary avulsion and mudcape progradation this style of deltaic progradation differs markedly from other deltas such as the mississippi where distributary avulsion leads to coastal land loss rather than shoreline progradation the key difference is that the orinoco delta coastal zone receives prodigious amounts of sediment from northwest moving littoral currents that transport sediment from as far away as the amazon system 1600 km late holocene progradation of the delta has decreased delta plain gradients increased water levels and minimized overbank flooding and siliciclastic sedimentation in the northwest sector these conditions coupled with large amounts of direct precipitation have led to widespread peat accumulation in interdistributary basins because peat forming environments cover up to 5000 km 2 of the delta plain the orinoco may be an excellent analogue for interpreting ancient deltaic peat deposits

peat forming history of the ancestral souris mire palaeocene ravenscrag formation southern saskatchewan canada analysis of the palaeocene souris lignite northern williston basin using coal petrology and palynology reveals the existence of seven different mire types forming six cycles of varying thickness and composition the order of mire types within the individual cycles allows an idealized mire type succession to be defined the principle factor driving the idealized mire type succession is decreasing water depth within the peat forming environment terrestrialization which leads to an increase in species diversity and a change in floral character from ferns angiosperms gymnosperms increases in water depth are the primary agent responsible for the termination of individual cycles in the ancestral souris mire changes in nutrient status of the mire may also promote major changes in the floral assemblage contributing to cycle termination comparison of densinite ulminite ratios for the central part of the souris seam shows an overall decrease in the degree of humification south westward indicating increa

gps height time series short period origins of spurious long period signals gps height time series used in geophysical studies are often formed from discrete continuous nonoverlapping 24 hour processing sessions with such a strategy unmodeled periodic ground displacements with approximately semidiurnal and diurnal periods have often been assumed to average close to zero by analyzing several years of continuous gps data from globally distributed sites at which controlled errors were not modeled this paper shows such an assumption to be erroneous it is shown that each unmodeled sub daily periodic displacement can propagate to several spurious long wavelength features in a gps height time series ranging in period from about 2 weeks to 1 year admittances ratio of amplitude of spurious long wavelength output signal in the gps height time series to amplitude of unmodeled periodic ground displacement depend on the coordinate component and the tidal constituent considered for example it is shown that an unmodeled s2 north component periodic ground displacement can propagate to a semiannual height signal with admittance of greater than 100 whereas the height admittance is around 5 10 since model errors in ocean tide loading atmospheric pressure loading and solid earth tide displacement amplitudes can be several millimeters long wavelength spurious signals of up to these amplitudes may be expected to appear in gps height time series this paper provides an indication of how such errors will propagate where such errors are greatest and hence how spurious fortnightly semiannual and in some cases annual effects may be present at some sites copyright 2007 by the american geophysical union

analysis and modelling of tsunami induced tilt for the 2007 m 7 6 tocopilla and the 2010 m 8 8 maule earthquakes chile from long base tiltmeter and broadband seismometer records we present a detailed study of tsunami induced tilt at in land sites to test the interest and feasibility of such analysis for tsunami detection and modelling we studied tiltmeter and broadband seismometer records of northern chile detecting a clear signature of the tsunamis generated by the 2007 tocopilla m 7 6 and the 2010 maule m 8 8 earthquakes we find that these records are dominated by the tilt due to the elastic loading of the oceanic floor with a small effect of the horizontal gravitational attraction we modelled the maule tsunami using the seismic source model proposed by delouis et al and a bathymetric map correctly fitting three tide gauge records of the area antofagasta iquique and arica at all the closest stations 7 sts2 2 long base tiltmeters we correctly modelled the first few hours of the tilt signal for the maule tsunami the only phase mismatch is for the site that is closer to the ocean we find a tilt response of 0 005 0 01 m at 7 km away from the coastline in response to a sea level amplitude change of 10 cm for the maule earthquake we observe a clear tilt signal starting 20 min before the arrival time of the tsunami at the nearest point on the coastline this capability of tilt or seismic sensors to detect distant tsunamis before they arrive has been successfully tested with a scenario megathrust in the southern peru northern chile seismic gap however for large events near the stations this analysis may no longer be feasible due to the large amplitude of the long period seismic signals expected to obscure the loading signal inland tilt measurements of tsunamis smooth out short often unmodelled wavelengths of the sea level perturbation thus providing robust large scale images of the tsunami furthermore tilt measurements are not expected to saturate even for the largest run ups nor to suffer from near coast tsunami damages tiltmeters and broadband seismometers are thus valuable instruments for monitoring tsunamis in complement with tide gauge arrays

shallow water tides in the northwest european shelf region from topex poseidon altimetry during recent years the accurate measurements from the topex poseidon satellite have improved global ocean tide models considerably however these global ocean tide models are still not accurate enough on the continental shelves for detailed oceanographic studies the need for increasing accuracy in shelf regions calls for inclusion of more than just semidiurnal and diurnal constituents in future global ocean tide models this is because a considerable part of the tidal variability on the shelves is caused by shallow water constituents one example is the m4 constituent which exceeds 50 cm at several locations on the northwest european shelf so far topex poseidon has not been considered for resolving these constituents mainly owing to its coarse ground track resolution reliable empirical estimates of several major shallow water constituents can be obtained from topex poseidon by combining along track and crossover observations estimates of the major shallow water constituents for the northwest european shelf m4 m6 and ms4 are presented in this study and compared with tide gauges and existing hydrodynamic models

anatomy of recent and peatified calluna vulgaris stems implications for coal maceral formation abstract anatomical characteristics of peatified calluna vulgaris stems isolated from a selection of northwest european raised bog peat deposits were compared with intact stems in order to reveal anatomical modifications caused by the peatification process four main decomposition processed were discerned 1 loss of structural integrity of cell walls and cell inclusions 2 gelification and swelling of cell walls 3 discolouration of cell walls and 4 deposition of matter in cell lumina fibre tracheids and wood parenchyma appear to be the most affected cell types the two main decomposition trends discerned in these were related to different fungal types precipitation of decay products was mainly observed in vessels bark tissues primary xylem and medullary parenchyma were characterized by an excellent anatomical preservation in the first stages of peatification a rapid decrease in cell contents was observed in bark tissues swelling and gelification was mainly seen in cell walls of the cambium and vessels we conclude that different types of cell walls respond differently to decay conditions this is probably related to differences in the original cell wall chemistry a high intra and intracellular variability in degree of preservation was sometimes observed in identical tissues the microscopic variability arising during peatification of wood and bark testifies to the heterogeneity of coal macerals derived from these tissues