three dimensional density spectra of sandy sediments power spectra of density variability for sandy sediments offshore panama city florida are estimated and modeled using digital x ray computed tomography images of sediment structure spectral analysis reveals that while shell pieces and mud mixtures are the main contributors to density variability at large scales intrinsic density variability associated with sand grain contacts dominates at small scales the power spectrum of sandy sediments is modeled by an analytic form that consists of two power law components one associated with the shell and mud contributions and the other with the intrinsic density variability of sand the dominant term has a much higher power law exponent than previously reported implications for the scattering of high frequency sound in sandy sediments are discussed

late pleistocene relic ultisols and alfisols in an alluvial fan complex in coastal tuscany detailed stratigraphic sedimentary facies and palaeosol analyses were performed on an outcrop on late quaternary deposits in the coastal area of tuscany the outcrop was selected as representative of one of the major quaternary alluvial fan complexes of central italy the ancient cecina river fan and as showing contrasting if related palaeosols the oldest relic palaeosol was identified as an ultisol representative of the most developed soil type normally found as relic soil in italy and about whose possible ages only approximate interpretations presently exist osl dating set the whole succession of sediments palaeosols and geomorphic surfaces into a firm chronological setting as a result evolution of the cecina fan complex in late pleistocene could be fully reconstructed assessment of the age of the relic ultisol produced results contrasting with current interpretations showing how such a soil type can have developed in italian conditions in a relatively short time i e since about mis 5d

the mass balance of soil evolution on late quaternary marine terraces northern california mass balance interpretation of a soil chronosequence provides a means of quantifying elemental addition removal and transformation that occur in soils from a flight of marine terraces in northern california six soil profiles that range in age from several to 240 000 yr are developed in unconsolidated sandy marine and eolian parent material deposited on bedrock marine platforms soil evolution is dominated by 1 open system depletion of si ca mg k and na 2 open system enrichment of p in surface soil horizons 3 relative immobility of fe and al and 4 transformation of fe si and al in the parent material to secondary clay minerals and sesquioxides net mass losses of bases and si are generally uniform with depth and substantial in some cases approaching 100 however the rate of loss of each element differs markedly causing the ranking of each by relative abundance to shift with time loss of si from the sand fraction by dissolution and particle size diminution from 100 to 80 to 90 to 10 concurrently with an increase of ai in the organic sesquioxide and clay phases to 10 and 50 respectively while only minor increases occur in the nonorganic sesquioxide phases

velocity variabilities and other physical properties of marine sediments measured by crosswell acoustic tomography high resolution images of the compressional wave velocity structure within various bottom sediments have been determined from high frequency crosswell acoustic tomography the three dimensional wave number spectra of the velocity variabilities were determined for each measured velocity image the sediment velocity variability spectra are anisotropic in general the variability frequency in the vertical direction is much higher than in the horizontal direction the aspect ratio of the two is found to be approximately 5 0 in addition the major and minor axes of the anisotropy are often tilted from the vertical and the horizontal direction respectively the angle of tilt called dip is found to be as much as 33 deg the measured velocity power spectra approximate a power law the spectral strength depends on the sediment type and the location based on the rock mechanics transformation procedure by yamamoto et al geophysics 59 1530 1541 1994 the sediment porosity density permeability and shear st

a soil chronosequence study of the reno valley italy insights into the relative role of climate versus anthropogenic forcing on hillslope processes during the mid holocene abstract relatively few soil chronosequences with good age control exist for late pleistocene and holocene deposits in the mediterranean region of europe yet surface soils and their young buried counterparts can provide meaningful information about the timing and processes of landscape response to external forcing such as climate or anthropogenic change here we present the results of a study that examines a well dated chronosequence of nineteen soil exposures in surficial deposits ranging in age from hundreds of years to hundreds of thousands of years located in the reno river valley near bologna italy the soil forming climate of the reno valley sits on a threshold between that which facilitates the accumulation of caco 3 and that which facilitates the translocation and formation of clay minerals and iron oxides once formed secondary iron oxides are relatively immobile in oxidizing conditions in the soil profile and therefore consistently record age trends with feo fed ratios decreasing predictably with soil age for all soils in the chronosequence the morphology of secondary carbonate accumulation and its depth of leaching also vary predictably with soil age but only for soils younger than about 12 000 years in these young soils horizons that contain secondary carbonate progress from relatively shallow stage i bk horizons in late holocene aged soils to deeper stage iii bk horizons in latest pleistocene aged soils in soils older than approximately 12 000 cal ybp however carbonate dissolution during wetter climates and the addition of colluvium and or dust to terrace surfaces become important factors in the preservation of carbonate in the profile and carbonate content is not predictable by age alone without significant depositional additions these older soils become decalcified pedogenic carbonate precipitated during drier climates is susceptible to dissolution during wetter periods as evidenced by discontinuous carbonate coatings on grains in some soils therefore overall measurable pedogenic carbonate content is spatially and temporally variable as a function of input of fresh carbonate and locally controlled soil moisture conditions particle size does not decrease predictably with soil age for reno valley soils and appears to be strongly influenced by parent material variability in younger soils and by dust additions in older soils our detailed examination of soil stratigraphy in the reno valley revealed evidence of significant aggradation of colluvium and tributary fans in the middle holocene between 6000 and 4000 ybp this aggradation pre dates bronze age agricultural expansion and appears to be instead attributable to the climate conditions of the middle holocene that have been documented elsewhere in italy for this time period this study demonstrates that late pleistocene and holocene surface soils in the mediterranean region of europe can effectively help elucidate rates and processes of landscape evolution

the importance of water column processes on the dissolution properties of biogenic silica in deep sea sediments i solubility abstract flow through experiments have been performed to study the thermodynamics of biogenic silica opal dissolution in deep sea sediments they were applied for the first time on sediment from the southern ocean van cappellen and qiu 1997a van cappellen and qiu 1997b we have extended the use of these experiments to other deep sea settings thereby covering a wide range of in situ silicic acid asymptotic concentrations casympt 200 to 900 mol l and biogenic opal content bsi 0 5 to 80 performing these experiments under in situ bottom temperatures allows for the comparison between experimental apparent solubilities and casympt concentrations low values of bsi apparent solubilities have been measured in the deepest sections of the multicores collected in the northeast atlantic 229 mol l and in the equatorial pacific 505 mol l they are only 10 to 20 higher than the in situ casympt concentrations this demonstrates a clear control of pore water silicic acid concentrations by the in situ apparent solubility of the bsi i e the solubility of bsi within a complex sedimentary matrix that includes important quantities of silicate minerals in regions where the percentage detrital percentage biogenic ratio is low the apparent solubility of the biogenic silica is close to that of in situ biogenic silica in the opposite case when the percentage detrital percentage biogenic ratio is high reprecipitation reactions induce strong interference on the dissolution properties of the opal both in situ and in flow through experiments in such a sedimentary matrix it is important to determine the appropriate opal solubility to be used in early diagenetic models i e the solubility of the biogenic silica just before deposition on the seabed this has been achieved by performing flow through experiments on sediment trap material from the north atlantic site comparison of apparent biogenic silica solubility measured by flow through experiments and the silicic acid concentrations measured in the cups of the sediment traps suggested that the solubility of biogenic silica that reaches the sediment water interface is not unique and varies spatially and temporally in fact it is the degree of coupling between surface waters and the sediment water interface that will control the aging of biogenic silica in the water column and hence the dissolution properties of the biogenic silica deposited at the sediment water interface all these results call for a strong improvement of biogenic silica early diagenetic models that should include not only a reprecipitation term that takes into account interaction with silicate minerals but also the existence of several phases of biogenic silica and thus that should operate in a non steady state mode to account for seasonal variations in the quality of deposited biogenic silica

relative sea level fall since the last interglacial stage are coasts uplifting worldwide the growing interest in quantification of vertical ground motion stems from the need to understand in detail how the earth s crust behaves for both scientific and social reasons however only recently has the refinement of dating techniques made possible the use of paleoshorelines as reliable tools for tectonic studies although there are many local studies of quaternary vertical motions of coastlines we know of no comprehensive worldwide synthesis here we provide a compilation of 890 records of paleoshoreline sequences with particular emphasis on the last interglacial stage marine isotopic stage mis 5e 122 ka the quality of dating mis 5e makes it a reliable marker to evaluate vertical ground motion rates during the late quaternary on a global scale the results show that most coastal segments have risen relative to sea level with a mean uplift rate higher than 0 2 mm yr i e more than four times faster than the estimated eustatic drop in sea level the results also reveal that the uplift rate is faster on average for active margins than for passive margins neither dynamic topography nor glacio hydro isostasy may explain sustained uplift of all continental margins as revealed by the wide distribution of uplifted sequences of paleoshorelines instead we suggest that only plate tectonic processes reconcile all observations of quaternary coastal uplift we propose that long term continental accretion has led to compression of continental plates and uplift of their margins therefore this study concludes that plate tectonics processes impact all margins and emphasizes the fact that the notion of a stable platform is unrealistic these results therefore seriously challenge the evaluation of past sea levels from the fossil shoreline record

weathering profiles and clay mineralogical developments bornholm denmark abstract saprock saprolite associations were studied by field and laboratory methods optical microscopy x ray powder diffraction scanning electron microscopy electron microprobe in order to describe regolith development in the crystalline rocks of the nygard kaolin pit bornholm denmark the clay sequences and stages of porosity development are similar to those observed for reservoir rocks from the utsira high riber et al 2016 the weathering of the parent granite began before the end of the mesozoic two stages of syn pre burial alteration followed by diagenesis during burial and then post uplift weathering have been recognized in stage plagioclase and some biotite biotite vermiculite kaolinite reacted to form elongate booklets of highly ordered kaolinite or smaller blocky pseudohexagonal crystals stage ii represented more extreme weathering developed along local fracture systems the higher potential for fluid flow in the fractures caused highly ordered kaolinite to alter to halloysitic poorly ordered kaolinite plagioclase biotite and k feldspar continued to interact with formation water and formed additional quantities of secondary clay minerals as a consequence of inter intra and trans granular cracks the original rock fabric deteriorated and porosity increased during later burial diagenetic siderite crystals filled voids and chlorite formed at the expense of kaolinite after re exposure calcite precipitated in localized zones smectite formed on a broader scale wherever high ionic strength groundwaters were present a mineralogical key to predicting where high porosity and permeability zones occur is the recognition of halloysitic poorly ordered kaolinite highly ordered kaolinite is abundant but it is ubiquitous siderite chlorite and smectite adversely affect permeability riber l dypvik h sorlie r and ferrell r 2016 clay minerals in deeply buried paleoregolith profiles norwegian north sea clays clay miner doi 10 1346 ccmn 2016 064036

late quaternary deformation of marine terraces on the cascadia subduction zone near cape blanco oregon the cape blanco region of south coastal oregon sits on the upper plate of the cascadia subduction zone about 60 70 km east of the base of the continental slope though the region has no historic coseismic deformation late quaternary deposits and landforms show abundant evidence of uplift folding and faulting a set of five late quaternary marine terraces and one uplifted holocene beach berm are preserved in the cape blanco region stratigraphic and altitudinal surveys of these physiographic features combined with several numerical and correlation age determinations permit a reconstruction of tectonic deformation near cape blanco in approximately the last 200 000 years the most cogent aspects of the neotectonics in this part of the cascadia subduction zone are that an east west trending anticline deforms the lower three terraces 80 125 ka as well as accounting for uplift of the holocene storm berm latest movement on the anticline was no more than 2 000 years ago but the anticline also deforms sediments as old as middle miocene the anticline is consistent with a north south principal contraction axis at cape blanco in about the last 100 000 years an older terrace at cape blanco approximately 200 ka is offset by two reactivated faults whose movements prior to the eocene served to suture several terranes to the north american continent tectonic tilting in the older terrace is not consistent with a north south principle axis of contraction but the axis of tilt is parallel to north northwest striking structures developed in the quaternary fold belt offshore on the continental shelf the observed deformation indicates that regional stress in the vicinity of cape blanco in the late quaternary has been accommodated by a variable pattern of strain

soil development on a beach ridge chronosequence in the gulf of mexico coastal plain and its relation to the ancient land use abstract a soil chronosequence study is presented in a beach ridge system at the mouth of the usumacinta and grijalva rivers mexico formed since a strong decrease in the rate of sea level rise some 6000 years ago four sites were selected for the chronosequence study simon sarlat ss rancho magdaleno 1 and 2 rm1 rm2 cocoteros cc and playa cocoteros pc located on beach ridges that range in age between 5000 years old to recently formed the soils show poor to moderate degree of development and the change in the pedogenic properties has been clearly evaluated the most pronounced changes are the following from the older ss rm2 to the younger soils pc cc color becoming yellowish brown in the better developed soils an increase in the amount of organic matter clay and fed iron extracted with dithionite solution a better structure with more stable aggregates a decrease in the feo proportion fe extracted with oxalate solutions and an increase in the content of fine magnetic particles formed by pedogenesis this area was densely populated and thus affected by human activities since the pre classic period 800 300 bc as many archaeological sites have been registered we evaluated soil agronomic quality in order to understand the ancient land use the results show that the soils in this area no matter their age have low agronomic quality which must have limited their use by ancient population however the strategic position near main trade routes near rich aquatic resources and a low susceptibility to flooding were favorable for human settlement on the beach ridges

effects of shear elasticity on sea bed scattering numerical examples it is known that marine sediments can support both compressional and shear waves however published work on scattering from irregular elastic media has not examined the influence of shear on sea bed scattering in detail a perturbation model previously developed by the authors for joint roughness volume scattering is used to study the effects of elasticity for three sea bed types sedimentary rock sand with high shear speed and sand with normal shear wave speed both bistatic and monostatic cases are considered for sedimentary rock it is found that shear elasticity tends to increase the importance of volume scattering and decrease the importance of roughness scattering relative to the fluid case shear effects are shown to be small for sands

analysis of high frequency acoustic scattering data measured in the shallow waters of the florida strait experiments were conducted in the florida strait region of the united states in july 1995 to investigate the contribution of sediment volume scattering to measured acoustic backscatter levels at frequencies of 7 5 and 15 khz five sites were analyzed for bottom backscattering level in the radial and azimuthal directions sediment geophysical parameters were established by a cross well tomographic measurement and used as inputs for modeling both sediment volume and rough interface scattering models were utilized in analyzing the data comparison of model predictions with measured data showed that for grazing angles at the water sediment interface from the critical angle to approximately 60 degrees volume scattering dominated for angles greater than approximately 60 degrees surface roughness scattering consistently dominated in geographic areas where the interface sound speed ratio exceeded one roughness scattering controled the backscattered level for grazing angles less than the critical angle in

soil morphology of an alluvial chronosequence from the little river north carolina coastal plain usa abstract a soil chronosequence on terraces of the little river in the north carolina coastal plain was characterized to evaluate age related trends in pedogenesis five representative pedons per landform were studied from six late quaternary fluvial surfaces and temporal trends were assessed by regression of morphological parameters against previously reported terrace optical age estimates solum b horizon and bt horizon thickness subsoil clay content and buntley westin index rubification have strong positive correlations with age and together distinguish between soils of the floodplain 200 yr bp the first terrace 9 9 2 0 ka intermediate surfaces t2 t3b t4 17 4 4 2 74 6 10 4 ka and the oldest terrace t5b 94 0 15 9 ka over time soils develop from entisols with respective a c and a e bw c profiles on the floodplain and first terrace to ultisols with increasing argillic horizon thickness rubification and clay content on t2 t5b solum thickness bt horizon thickness and clay content display linear increases through time with soil thickening reflective of downward pedogenesis through permeable coarse grained alluvium increasing argillic horizon clay content is attributable to illuviation and possibly also to a combined bioturbation translocation process whereby clays scattered throughout sandy parent sediments are delivered to the surface by bioturbation then concentrated in b horizons by eluviation illuviation rubification increases with age and reflects transformation and subsoil concentration of inherited free iron rather than iron oxide formation from primary mineral weathering t5b pedons display morphologies comparable to those of 200 ka to 1 ma soils along coastal plain rivers that also drain the appalachian piedmont probably because sandy coastal plain derived little river alluvium has a higher hydraulic conductivity that promotes faster rates of downward weathering clay translocation and rubification than the more finely grained sediments of piedmont draining rivers thus textural differences related to sedimentary provenance should be recognized when interpreting chronosequences from the region although rates of pedogenesis differ among coastal plain alluvial soils linear trends in the 100 ka little river chronosequence may nonetheless correspond to the early more linear phases of development in studies from the region that span much longer intervals of time

relationships between topography and spatial variations in groundwater and soil morphology within the taoyuan hukou tableland northwestern taiwan this study examines the relationships between topography and spatial variations in groundwater and soil morphology within the multi step taoyuan hukou tableland in northwest taiwan several different geomorphological and pedological approaches were jointly undertaken including analyses of a digital elevation model dem a reclassified soil map field survey results engineering borehole data and a hydrological simulation five major geomorphic surfaces were identified based on terrace scarps observed in the dem minor surfaces separated by small fluvial scarps or tectonic scarps were also mapped the simplified soil map and field study of soil morphology reveal a number of soil distribution patterns associated with specific topographic settings soil morphology changes from homogeneous red soils in the fore edge of surfaces to mottled soils and finally to gley soils in back edge regions such a pattern is more pronounced in the proximal part of a surface while toward the distal zone the patterns tend to be obscured by increasing amounts of mottled and gley soils the proportion of homogeneous soils increases with narrowing of the surface for fan shaped surfaces soil types appear to be dominated by mottled soils except for at terrace edges where homogeneous red soils occur while homogeneous soils dominate tectonically elevated surfaces a toposequence of homogeneousmottled gley soils occurs in the surrounded lowlands borehole data and hydrological models indicate that these soil distribution patterns are strongly related to groundwater occurrence and fluvial processes both of which are generally governed by topography despite the observed pedodiversity in this area the common feature of these toposequences i e the distribution of homogeneous red soils along the surface fore edge may serve as a basis for establishing a reliable soil chronosequence for the area 2007 elsevier b v all rights reserved

soil chronosequence studies in temperate to subtropical low latitude low relief terrain with data from the eastern united states the coastal plain of the eastern united states is a low latitude low altitude low relief terrain composed primarily of gently dipping marine and marginal marine sediments that range in age from cretaceous to quaternary population density of the area is moderate and most of the population is concentrated along the coast inland of the coast agriculture including growing trees for pulp is the dominant economy in this region soils have developed along two different pathways one pathway is dominated by the dissolution and movement of oxyhydroxides and the accumulation of organic matter the other by the accumulation of clays and oxyhydroxyides and the adsorption or oxidation of organic matter the first pathway has resulted in the formation of spodosols the second in the development of ultisols no clearly distinguishable age trends have been identified in the spodosols but the properties of ultisols can be measured to quantify surface material alteration through time ultisols are therefore suited to order of magnitude chronostratigraphic interpretations potentially data derived through the study of ultisols can be used to develop models that predict how surface processes will change due to continued weathering and pedogenesis or as the result of climate change

fine scale sedimentary structure implications for acoustic remote sensing abstract detailed measurements of sediment properties and acoustic scattering were made at a carbonate sand silt clay site off dry tortugas in the florida keys the sediment is characterized by varying scales of biologically controlled random roughness and heterogeneity as well as surficial stratification on centimeter scales the interface roughness was determined from stereo photogrammetric digitization and parameterized by a power spectrum whereas sediment volume heterogeneity was determined from core measurements and parameterized by first order autoregressive models for sound speed and density fluctuations in contrast to previous investigations fine scale sediment bulk density fluctuations were examined in sediment cores with computerized tomography in addition to the standard gravimetric technique furthermore the strongly delineated sediment density and sound velocity transition layer was parameterized by piecewise linear fits these characterizations of the random and deterministic properties were used in acoustic scattering models in an effort to determine the feasibility of remotely measuring fine scale features of the seafloor the result was negative older low resolution models gave moderately good fits to the acoustic data but the fit did not improve for newer higher resolution models it is suggested that scattering due to shell fragments must be included to account for all features observed in the scattering data at this site

a model data comparison for low frequency bottom backscatter this article describes a model for bottom backscattering strength applicable over the frequency range 100 1000 hz the model includes backscatter due to both a rough water sediment interface and internal sediment inhomogeneities i e sediment volume scattering within an upward refracting sediment the net result is predictions for bottom backscattering strength that depend on the following frequency sound speed of the water near the water sediment interface density ratio sound absorption within the sediment near surface sound speed gradient within the sediment two interfacial roughness parameters and a parameter proportional to the scattering cross section of a unit volume of sediment the sediment sound speed profile is specified in terms of near surface values for the sound speed ratio and gradient salient features of the modeled backscatter strength include marked departures from lambert s law for sediments with sound speed ratios greater than 1 1 5 db oscillations as a function of grazing an

interactions between dissolved silica and carbonate minerals an experimental study at 25 50 c abstract replacement of carbonate minerals by silica polymorphs in marine and meteoric environments is a common early diagenetic feature of sedimentary rocks although relatively few experimental investigations have been made of interactions between carbonate minerals and dissolved sio 2 at moderate temperatures available data suggest that silica uptake onto carbonate surfaces can be significant we present results of experiments conducted between 25 and 50 c of the uptake of aqueous sio 2 from artificial seawater mg na cl ca hco 3 i 0 7 and meteoric type cacl 2 na 2 co 3 i m a reasonable upper limit for natural diagenetic waters dissolved silica carbonate mineral interactions were investigated under three experimental conditions 1 in solutions near equilibrium with respect to calcite 2 in calcite seeded precipitation experiments at fixed degrees of calcite supersaturation and 3 during closed system dissolution precipitation of metastable carbonate minerals aragonite and 18 mole mg calcite to low mg calcite lmc in artificial seawater asw maintained near equilibrium with respect to calcite at various p co2 values silica uptake from solution onto calcite surfaces 1 15 mol si gram seed was irreversible and strongly time and ph dependent the rate of uptake was greatest in the first 5 hr and in solutions of lower ph higher p co2 silica uptake was only nominally dependent on solution mg and temperature over the range studied silica uptake was greater in asw than in otherwise comparable experiments conducted in low ionic strength solutions controlled calcite precipitation rates were unaffected by the adsorption of silica during recrystallization of aragonite and mg calcite in low ionic strength solutions silica uptake 1 6 mol g was similar to values frorn near equilibrium experiments for synthetic calcite in asw experimental si adsorption values were comparable to si adsorption values determined for modem metastable sediments 3 4 mol g 1 despite considerable variation in the experimental carbonate equilibrium disequilibrium mineralogy and solution chemistry si uptake at near surface and moderate burial conditions 25 50 c was limited to 15 mol g 1 si even in solutions maintained near opal ct saturation over a period of days to weeks

age estimates and uplift rates for late pleistocene marine terraces southern oregon portion of the cascadia forearc marine terraces are prominent landforms along the southern oregon coast which forms part of the forearc region of the cascadia subduction zone interest in the cascadia subduction zone has increased because recent investigations have suggested that slip along plates at certain types of convergent margins is characteristically accompanied by large earthquakes in addition other investigations have suggested that convergent margins can be broadly classified by the magnitude of their uplift rates with these hypotheses in mind we generated new uranium series amino acid and stable isotope data for southern oregon marine terrace fossils these data along with terrace elevations and two alternative estimates of sea level at the time of terrace formation allow us to determine terrace ages and uplift rates uranium series analysis of fossil coral yields an age of 83 5 ka for the whisky run terrace at coquille point in bandon oregon a combination of amino acid and oxygen isotope data suggest ages of about 80 and 105 ka for the lowest two terraces at cape blanco these ages indicate uplift rates of 0 45 1 05 and 0 81 1 49 m kyr for coquille point and cape blanco respectively late quaternary uplift rates of marine terraces yield information about deformation in the overriding plate but it is unclear if such data vary systematically with convergent margin type in order to assess the utility of the southern oregon uplift rates for predicting the behavior of the cascadia subduction zone we compared late quaternary uplift rates derived from terrace data from subduction zones around the world on the basis of this comparison the southern oregon rates of vertical deformation are not unusually high or low furthermore late quaternary uplift rates show little relationship to the type of convergent margin these observations suggest that local structures may play a large role in uplift rate variability in addition while the type of convergent margin may place an upper limit on possible uplift rate greater upper limits serve to increase the range of possible uplift rates in the case of the southern oregon coast variability in uplift rate probably reflects local structures in the overriding plate and the rate of uplift cannot be used as a simple index of the potential for great earthquakes along the southern cascadia subduction zone

identification of podzols and podzolised soils in new zealand by relative absorbance of oxalate extracts of a and b horizons abstract a method for separating podzols and podzolised soils from other new zealand soils is proposed the method is based on measurement of the optical density of acid oxalate extracts of soils a number of soil leaching sequences and some individual soils are examined it is assumed that the optical density of the oxalate extracts is due mainly to extracted fulvic acid and that detection of appreciable quantities of this material in the b horizon indicates that podzolisation is an active process in the soil the technique separated the soils of the leaching sequences well following the observable increase of podzolic characteristics with increased leaching when the b horizon a horizon odoe optical density of the oxalate extracts ratios were compared with the criteria for the spodic horizon in soil taxonomy soil survey staff 1975 it was found that all soils with a ratio of less than 1 0 did not satisfy spodic horizon criteria and were not classified as podzol podzolised all the soils examined with ratios 1 0 satisfied spodic horizon criteria or were classified as podzol podzolised usually both

soil forming processes and rates on uplifted marine terraces in southwestern oregon usa soil chronosequences were examined on flights of tectonically uplifted marine terraces near cape blanco and cape arago southwestern oregon all of the soils contain abundant organic c and are strongly acidic ph in h2o 30 of the exchange sites saturated with al the soils in the two areas show a progression in development from spodosols to spodosols with clay enriched horizons and eventually to ultisols although the spodic and argillic horizons appear to be forming concurrently in the soils evidence is presented to support the concept that the spodic horizon is eventually masked by clay accumulation because of weathering in situ neoformation of clays and clay translocation the primary age related trends include increases in 1 the relative abundance of silt and clay 2 the ratio of quartz to feldspars in the very fine sand 100 50 m fraction and 3 the amounts of dithionite extractable fe and al and crystalline forms of fe in the profile

forward modeling for marine sediment characterization using chirp sonars this paper investigates the forward modeling of chirp sonar data for the quantitative characterization of marine subbottom sediment between 1 and 10 khz the forward modeling based on a transfer function approach included impacts of layering or impedance mismatch attenuation roughness and transitional layers i e continuous impedance variations the presented approach provided the best compromise between the number of available geoacoustic parameters from chirp sonar data and the subbottom modeling accuracy the forward model was tested on deep sea chirp sonar data acquired at a central frequency of 3 5 khz comparisons between synthetic and experimental seismograms showed good agreement for the first 15 m of buried layers performance of the inversion using this forward model was also examined through sensitivity analysis the results suggested that estimations of layer thickness impedance and transitional layer thickness were robust whereas roughness and attenuation estimations were subject to wavelength and layer thickness conditions

soil evolution over the quaternary period in a semiarid climate segre river terraces northeast spain abstract a macro and micromorphologic study was done on the soils from a stepped sequence of seven dated fluvial terraces in the lower segre river valley lleida northeast spain under a present day semiarid mediterranean climate the soils have evolved from the holocene through the early pleistocene providing an excellent morphostratigraphic framework for evaluating time dependent factors influencing soil formation in a dry and calcareous environment throughout the chronosequence some properties are regularly age related specially carbonatation in subsurface horizons the carbonates occur mainly as micrite and although microsparite and sparite also appear in the oldest soils they are replaced by fine grained calcite by dissolution reprecipitation processes micritization process which is active at present some pedological paleofeatures as the presence of sparite and recarbonated argillans in oldest terrace can be interpreted as the reflex of climatic changes during the quaternary in spite of this climate variability the soils display progressive and systematic patterns of carbonate accumulation on the lowest terraces the soils do not yet have secondary carbonates but in the beginning late pleistocene calcic horizons with carbonate pendents are developed these pendents increase its thickness with age although pendent growth rates decreases from late pleistocene to middle pleistocene in the middle of the late pleistocene calcic horizons evolved to petrocalcic horizons which increase its thickness in the middle and specially in early pleistocene the presence of calcic and petrocalcic horizons is the primary basis for soil classification this criterion is applicable not only to the soils of the lower segre river basin but also to many soils throughout the semiarid mediterranean region

soil genesis along a chronosequence on marine terraces in eastern taiwan abstract soil chronosequences developed on elevated marine terraces are ideal for studying changes in soil forming processes with time the coastal range of eastern taiwan is a product of active arc continent collision vertisols mollisols and entisols are generally found on the different levels of marine terraces herein but no detailed investigations of soil chronosequence have been conducted by integrating field morphology physio chemical characterization micromorphology and mass balance interpretations five soil pedons were selected on the three marine terraces including tt 1 and tt 2 pedons typic hapluderts on the first higher level with the oldest soil age 9 10 ka tt 3 vertic hapludolls and tt 4 pedons typic hapludolls on the second intermediate level 5 6 ka and tt 5 pedon typic udipsamments on the third lower level with the youngest soil age 3 5 ka the morphological characteristics showed that strongly developed angular blocky structures pressure faces and slickensides are more common in higher terrace soils than in lower terrace soils in this study depth to c horizon solum thickness and thickness of the clay enriched zone increase with relative terrace age although only one to two profiles per terrace were characterized the following soil analytical characterizations increase with time the degree of sand grains weathering ph h2o organic carbon cec contents of fed feo and mnd based on x ray diffraction analysis of the clay size fraction soils on all terraces have a mixed mineralogy mica smectite and kaolinite have slightly increased with increasing terrace age furthermore the dominant processes identified with mass balance analysis include loss of bases ca and mg iron and clay with time the soil properties including analytical and mineralogical characterizations which do not have notable changes with time are primarily due to relatively young soil age

paleoclimatic fingerprints of ferromanganese nodules in subtropical chinese soils identified by synchrotron radiation based microprobes abstract ferromanganese nodules are important pedogenic indicators in soil they are usually characterized by clearly expressed ring structures although these features are believed to be significant environmental fingerprints the reasons for their formation still await interpretation here we interpreted these fingerprints by the synergistic use of noninvasive synchrotron radiation based techniques and advanced analytical methods the results revealed that the soil nodules were formed due to the filling of the pore networks of the soil matrix that was mediated by both abiotic and biotic factors during alternative soil wetting drying cycles the ring structures are therefore the memories of the soil redox history the variations in elemental compositions of the ring structures indicates the soil moisture conditions at the time of formation their porosity reflects the rate of change in soil redox potential and the soil redox potential is mainly affected by precipitation

rates and processes of soil evolution on uplifted marine terraces northern california time dependent changes in soil development have been evaluated for two flights of uplifted marine terraces with similar site characteristics and a range in terrace ages 3 9 ka to 330 ka in northern california six pedogenic properties of soils developed in unconsolidated deposits overlying bedrock marine platforms have systematic time dependent trends but each property differs in rate of change and in the time period over which its changes are useful as relative age dating or correlation tools changes in accumulated mass of organic carbon and ph are useful properties only for the youngest soils and probably for soils less than 10 20 ka in this climatic region soils on terraces older than 29 ka have nearly similar amounts of mass of organic carbon with values of about 3 6 by weight for the upper meter of the soil profile soil reaction ph in the top 20 cm of the soil profile decreases at a rapidly declining rate reaching and maintaining a value of 5 by 39 40 ka total mass of accumulated clay is an excellent indicator of relative soil age during all stages of soil development the rate of accumulation of clay is about 0 4 g cm2 soil column per thousand years so that pedons on terraces with inferred ages of about 124 ka have accumulated at least 50 g cm2 soil column of clay systematic and linear increases in accumulated mass of several forms of pedogenic iron make them very useful for chronological purposed for at least 240 ky of soil development crystalline forms of iron enable greater distinction among young soils than amorphous forms which have negligible accumulations until at least 40 ka the rate of accumulation of crystalline forms of iron fed feo is about 0 02 g cm2 soil column per thousand years so that pedons on terraces with inferred ages of about 124 ka have accumulated about 3 g cm2 soil column of crystalline forms of pedogenic iron changes with time in accumulated mass of amorphous forms of pedogenic aluminum alo are negligible within the first 29 ka then reflect a rapid increase in rate of accumulation until at least 124 ka two pedons from the same terrace inferred age 124 ka contain strikingly different amounts of pedogenic alo however and suggest that alo may be an unreliable indicator of the degree of soil development in addition to mass values of different soil substances maximum percent values were calculated soils developed on marine terraces older than 29 ka have at least 10 maximum clay older than 100 ka at least 30 maximum clay and older than 240 ka at least 40 50 maximum clay soils on terraces younger than 29 ka have less than 1 maximum fed and soils older than 240 ka at have at least 4 maximum fed these easily obtained values provide textural and chemical boundaries for separating marine terraces younger or older than about 29 100 and 240 ka in this region but are useful only as very general tools for correlation maximum percent clay is a more reliable indicator of soil age than maximum percent fed as the latter is greatly influenced by local groundwater flux and percent values of fed have a high degree of scatter

diversity of diagnostic horizons in soils of the contiguous usa a case study abstract many previous studies of pedodiversity have emphasized the lateral variability of soils in this study the vertical distribution of diagnostic horizons is examined at the soil series level unlike genetic horizons diagnostic soil horizons are based on quantitatively defined morphological and analytical properties and they form the basis of modern soil classification systems an examination of 1600 soil series in 63 representative out of 226 major land resource areas mlras in contiguous usa revealed that they contain from one to seven diagnostic soil horizons with an average of 2 6 1 2 about 20 of the soil series contain 4 or more diagnostic horizons 80 of these soil series are in seven great groups the glossudalfs haplorthods fragiorthods endoaquods epiaquods fraglossudalfs and glossaqualfs the laurentide great lakes region contains a discordant number 57 of soils with 4 or more diagnostic horizons the most common being ochric 100 albic 91 argillic 85 glossic 69 spodic 51 and a fragipan 19 several factors appear to contribute to the diversity of diagnostic horizons including proximity to the great lakes where abundant snowfall precludes soil freezing and enables water to percolate rapidly through the soil in a short interval during the spring the prevalence of stratified glacial deposits often containing a lithologic discontinuity and a fluctuating water table all of which enable specific weathering products to accumulate at different depths

estimation of sonic layer depth from surface parameters mixed layer depth mld is an important oceanographic parameter however the lack of direct observations of mld hampers both specification and investigation of its spatial and temporal variability an important alternative to direct observation would be the ability to estimate mld from surface parameters easily available from satellites in this study we demonstrate estimation of mld using artificial neural network methods and surface meteorology from a surface mooring in the arabian sea the estimated mld had a root mean square error of 7 36 m and a coefficient of determination r 2 of 0 94 about 67 91 of the estimates lie within 5m 10 m of the mld determined from temperature sensors on the mooring

late quaternary tectonic deformation in the cape arago bandon region of coastal oregon as deduced from wave cut platforms the cape arago region of south central oregon sits on the upper plate of the cascadia subduction zone about 80 km east of the base of the continental slope the style of late pleistocene deformation along the cascadia forearc near cape arago is well expressed by the altitudinal variation of a set of five uplifted wave cut platforms these platforms record open folding with a half wavelength of about 6 7 km as well as late quaternary offset on flexural slip reverse faults that parallel bedding in the underlying bedrock the folds have produced both landward and seaward tilts to the uplifted wave cut platforms because the folds cut obliquely across the coastline the magnitude of coastal uplift is variable in the case of the lowest 80 ka wave cut platform this variable uplift has resulted in coastal deformation ranging from subsidence to a maximum uplift of 0 8 m kyr quantitative analysis of the mechanism of flexural slip folding for the south slough syncline near cape arago indicates that the late quaternary strain rate has decreased in the last 200 kyr evidence of past great subduction style earthquakes such as regional uplift and regional landward tilting of wave cut platforms or regional submergence of coastlands is lacking inmore the cape arago region instead the deformational style is controlled by folding though localized folding is dominant the occurrence of great subduction style earthquakes is not precluded because localized folding could occur concurrently with regional coseismic deformation less

a quaternary soil chronosequence study on the terraces of the alcanadre river semiarid ebro basin ne spain abstract a sequence of dated alluvial terraces can provide an excellent geomorphological framework for studying soil evolution over time the aim of this study is to establish a soil chronosequence over the last million years on the calcareous fluvial deposits of the alcanadre river in the semiarid ebro basin ne spain moreover two methods for determining total caco 3 content are compared by calcimetry in the lab and by a portable xrf analyzer in the field pedogenic caco 3 accumulation is the most characteristic age related pedofeature in the studied semiarid conditions this accumulation directly affects soil classification the soils evolved from an initial calcaric fluvisol into haplic calcisol and later into petric calcisol as well as some management properties e g reducing water holding capacity from 170 to 14 mm profile the young holocene soils that developed on the lower terraces maintain their original fluvic and calcaric properties but calcic horizon can be found as pendants on soils from the early holocene to late pleistocene from 10 1 ka on middle pleistocene from 176 14 ka terraces petrocalcic horizon is found whose thickness is greatest on the soil evolved on oldest early pleistocene surface this net retention of carbonates over time suggests the predominance of dry periods over wet ones during soil evolution the measure of total carbonates by xrf in the field and those on fine earth by calcimetry in the laboratory shows a highly significant linear regression r 2 0 91 which highlights the efficiency of in situ approach for measuring them

a soil chronosequence on quaternary marine terraces san clemente island california a soil chronosequence on marine terraces was examined on san clemente island california in an arid mediterranean climate in order to see which soil properties differ most systematically with time ages of the geomorphic surfaces were determined by radiocarbon uranium series and amino acid racemization techniques and range from 1 000 000 yrs soils on surfaces 200 000 yrs old are vertisols or alfisols with vertic properties such as slickensides and cracks and they exhibit both prismatic and angular blocky sphenoidal or only angular blocky structure solum thickness increases linearly with age of geomorphic surface clay soluble salts ald smectite mica ratios in the clay fraction and quartz plagioclase ratios in the silt fraction when expressed as profile summations show increases with age of geomorphic surface the best fit regression equations are linear with the exception of ald which is best expressed as a power function important soilforming processes appear to be alteration of mica to smectite accumulation at depth of soluble salts derived from marine aerosols possibly additions of eolian materials clay illuviation in the younger soils and pedoturbation in the older soils the observations reported here allow the following conclusions to be drawn about soils in this environment 1 certain soil properties which show distinct trends with time can be used for relative age dating in geomorphic and stratigraphic studies 2 soils have not reached a steady state condition with respect to many of their properties and 3 alfisols and mollisols with natric b horizons may be precursors to vertisols

variation in soil surface area in a chronosequence of soils from glen feshie scotland and its implications for mineral weathering rate calculations abstract the inorganic component of soil horizons from a chronosequence of six soils developed in glen feshie scotland shows an increase in surface area with soil age and a decrease in surface area with increasing depth in the soil profiles surface area increases due to the development of discontinuous porous coatings on mineral grains the preferential dissolution of specific areas of individual minerals resulting in complex highly irregular grain shapes and a general reduction in grain size due to dissolution the discontinuous coatings consist predominantly of oxalate extractable al si oxyhydroxides and account for between 61 and 94 of the total inorganic surface area failure to take into account the increase of mineral surface area with time can lead to predictions of decreasing mineral dissolution rate with soil age in contrast to laboratory studies which assume that mineral dissolution can reach a steady state the difference between total and reactive mineral surface area may help to explain the frequently reported result that laboratory measured mineral dissolution rates are up to several orders of magnitude greater than those measured in the field

mechanisms for subcritical penetration into a sandy bottom experimental and modeling results this paper presents preliminary results of a recent study whose overall objectives are to determine the mechanisms contributing significantly to subcritical acoustic penetration into ocean sediments and to quantify the results for use in sonar performance prediction for the detection of buried objects in situ acoustic measurements were performed on a sandy bottom whose geoacoustical and geomorphological properties were also measured a parametric array mounted on a tower moving on a rail was used to insonify hydrophones located above and below the sediment interface data covering grazing angles both above and below the nominal critical angle and in the frequency range 2 15 khz were acquired and processed the results are compared to two models that account for scattering of sound at the rough water sediment interface into the sediment although all possible mechanisms for subcritical penetration are not modeled the levels predicted by both models are consistent with the levels observed in the experime

low grazing angle bistatic sea floor scattering on the florida atlantic coastal shelf observations of bistatic scattering at moderate frequencies 3750 hz 7500 hz and 15 000 hz and low grazing angles 2 20 are presented with a geoacoustical description of the site given a source receiver separation of 80 7 m bistatic scattering strengths in the sandy sediments at the measurement site range from 70 to 15 db the observed bistatic scattering at low grazing angles depends primarily on the incident bearing angle bistatic scattering values are highest along the transect between the source and receiver maximum scattering strengths 20 to 15 db appear 30 m from the receiver regions of high scattering 30 db strength are centered along the direct path between the source and receiver the contribution of volume scattering to the observed scattering pattern is not very clear however given the sandy sediments found at the site roughness scattering is expected to be a major contributor to the observed bistatic scattering patterns

pilot experiment for the acquisition of marine sediment properties via small scale tomography system a 3 d high resolution crosswell acoustic tomography system was designed and tested in a shallow water environment this system makes use of a damped least squared inversion technique and is used to construct compressional wave velocity images from measured travel time data use of singular value decomposition allowed checks of the linear inversion confirming the validity of the modeled environment it is shown that when the ratio of width to depth of the cross section is about unity or smaller and the domain has not been overparametrized the inverted image model has sufficiently good figures of merit in resolution and variance to visualize small variations in the magnitude compressional velocity field

from a black to a gray box a mass balance interpretation of pedogenesis we utilize chemical elements as tracers in a mass balance analysis that provides functional relationships among soil chemical composition bulk density and volume change in relation to parent material these analytical functions are based on the principle of conservation of mass and include a term quantifying mass flux into out of the soil and between horizons we apply the technique to the oldest member of a chronosequence developed on marine terraces in northern california it is an alfisol that evolved from beach sand to its present state nearly one third of its weight is composed of secondary clay minerals in about 240 ky aside from large increases in organic carbon desilication is the dominant factor in soil evolution 29 50 83 g cm 2 si was leached from the beach sand during pedogenesis the rate of desilication is roughly 2 1 t km 2 yr 1 0 21 g cm 2 ky 1 an order of magnitude slower than that implied by the si denudation rate calculated for the mattole river watershed weathering of primary minerals and synthesis of secondary minerals is relatively well advanced suggesting that the rate of desilication may be declining the local beach is composed of quartz and sodic plagioclase with smaller amounts of chlorite mica and kaolinite the soil has substantially different mineralogy sand is dominated by quartz and clay is dominated by kaolinite halloysite chloritic intergrades and gibbsite bases are also leached though the total mass was much less 57 2 55 g cm 2 of na in the beach sand was lost as plagioclase weathered by focusing on elemental and mineralogical gains and losses we emphasize the essential connection between the pedologic environment and the external hydrochemical environment

soil development relative dating and correlation of late quaternary marine terraces in southwestern oregon abstract flights of tectonically uplifted late quaternary marine terraces are preserved at several localities along the oregon coast intervening coastal areas without marine terraces reflect net subsidence these gaps in the coastal terrace record make it difficult to correlate terraces along the pacific coast to test the utility of soils in relative dating and correlation two flights of marine terraces near cape blanco and cape arago were investigated the terraces could be distinguished in each area from soil morphological properties and a quantitative index of soil development derived from field descriptions the soils in the two areas show a progression in development from spodosols to spodosols underlain by clayey material to ultisols the lowest two terraces at cape blanco which have reported age estimates of 80 000 and 105 000 yr are correlative with the lowest two terraces at cape arago the fifth and oldest terrace at cape blanco has no equivalent at cape arago soil development indices for the third and fourth terraces at each area allow two alternative sets of correlations

mass balance of soil evolution on late quaternary marine terraces in coastal oregon mass balance analysis was used to quantify elemental losses gains and transformations for a soil chronosequence developed on elevated marine terraces in south coastal oregon the four soils analyzed in the study range in age from 80 ka to greater than 250 ka and are inceptisols spodosols and ultisols dominant soil forming processes include 1 desilication and loss of base cations from the solum 2 redistribution of iron and aluminum from surface to subsurface horizons 3 transformation of iron and aluminum from sand and silt size fractions to secondary clay and crystalline sesquioxide fractions and 4 accumulation of organic matter silica represents the largest mass loss of any element from the system and varies from 6 48 g cm2 11 loss from solum compared to original amount of si in parent material to 42 99 g cm2 22 with increasing terrace age losses of silica from the sand size fraction over time 2 to 17 are accompanied by increases of silica in the clay size fraction base cations represent only a small portion of the soil mass but up to 53 0 09 g cm2 of the sodium present in the parent material is lost due to weathering and leaching iron and aluminum are redistributed within the sola of younger terraces during podzolization but are lost from the older soils due to intense weathering and leaching over time the majority of iron is transformed from the sand and silt size fractions to the crystalline sesquioxide fraction in contrast the majority of aluminum lost from the sand and silt size fractions is transformed to the clay size fraction

problems with biogenic silica measurement in marginal seas abstract surface sediment samples from the bohai yellow sea and the pacific were used to assess biogenic silica bsi content and to study uncertainties in bsi measurements the contents of bsi in the bohai and yellow sea are all less than 1 the dissolution of bsi in sediments from the bohai and yellow sea is very important to maintain high levels of silicate in the water column the non biogenic silica from clay minerals has an obvious effect on bsi of sediment samples in the bohai and yellow sea with low bsi and high clay minerals the solid to solution ratio was found to have a great influence on bsi measurement which can induce uncertainties up to 75 the effect of loss by sorption and centrifugation is negligible interlaboratory comparison of techniques for bsi measurement by the wet alkaline extraction technique of mortlock and froelich deep sea res 36 1989 1415 1426 with clay correction was suggested to give no significant differences however differences in sediment compositions and reagent to sample ratio may limit the application of the wet alkaline extraction method

acoustic scattering from the seafloor modeling and data comparison an existing model of seafloor backscattering d r jackson d p winebrenner and a ishimaru j acoust soc am 79 1410 1422 1986 was implemented with the additions of volume scattering from a random inhomogeneous continuum and scattering from subbottom interfaces results of computer simulations with the extended model were compared with values of scattering strength obtained from processed gloria data from the monterey fan off the coast of california regions of well delineated high and low backscatter are seen in the gloria imagery the geoacoustic input parameters for the simulation runs were either taken directly from or estimated from core data obtained by ground truth sampling in the image area from the model simulation results it appears that the main factor causing the observed dichotomous character of the strength of returns in the fingers area is the presence or absence of a topmost inhomogeneous silt clay layer with a thickness of around 1 1 5 m in the high backscatter areas inh

scattering from a rough sedimental seafloor containing shear and layering a simple first order perturbation approach is presented which directly determines the acoustic field scattered by a rough seafloor the theory is based on the born approximation the seafloor is allowed to be shear supporting or to be layered scattering strengths are derived for both monostatic and bistatic scattering and discussed with respect to their dependence on seafloor parameters and roughness spectrum power law wave number spectra are found to be appropriate for explaining important features of backscatter which are the magnitude the frequency and grazing angle dependence for grazing angles below critical shear wave velocities exceeding some 350 m s 1 significantly modify the scattering strength with respect to narrow band acoustic signals layering of the seafloor may be of importance numerical results are presented for the frequency range 10 100 khz

modeling of bottom backscattering from three dimensional volume inhomogeneities and comparisons with experimental data in this paper backscattering from 3d volume inhomogeneities in the seabed is modeled and the results compared with experimental data at 250 650 hz the experiment was part of the acoustic reverberation special research program arsrp and the data were obtained in a sediment pond on the western flank of the mid atlantic ridge a volume scattering model based on first order perturbation theory is developed incorporating contributions from both sound speed and density fluctuations with the propagators i e the green s functions handled accurately through numerical wave number integration and random fluctuations generated effectively by a new scheme modified from the spectral method the model is capable of simulating monostatic backscattered fields in the frequency domain as well as in the time domain owing to 3d volumetric sediment inhomogeneities the model compares favorably and consistently with the arsrp backscattering data over the entire frequency band with the fluctuations of sound speed and

hornblende etching and quartz feldspar ratios as weathering and soil development indicators in some michigan soils weathering can be used as a highly effective relative age indicator one such application involves etching of hornblende grains in soils etching increases with time duration and decreases with depth in soils and surficial sediments other variables related to intensity of weathering and soil formation are generally held as constant as possible so as to only minimally influence the time etching relationship our study focuses on one of the variables usually held constant climate by examining hornblende etching and quartz feldspar ratios in soils of similar age but varying degrees of development due to climatic factors we examined the assumption that the degree of etching varies as a function of soil development even in soils of similar age the spodosols we studied form a climate mediated development sequence on a 13 000 yr old outwash plain in michigan their pedogenic development was compared to weathering related data from the same soils in general soils data paralleled weathering data hornblende etching was most pronounced in the a and e horizons and decreased rapidly with depth quartz feldspar ratios showed similar but more variable trends in the two most weakly developed soils the q f ratio was nearly constant with depth implying that this ratio may not be as effective a measure as are etching data for minimally weathered soils our data indicate that hornblende etching should not be used as a stand alone relative age indicator especially in young soils and in contexts where the degree of pedogenic variability on the geomorphic surface is large d 2004 university of washington all rights reserved