micromorphlogy of recent and buried soils in a semi arid region of northwestern india abstract profiles of four recent soils and of eleven soils buried under archaeological sites of known ages were investigated in an area between the ghaggar valley and the northern piedmont of the arawalli hills in northwestern india the principal approach was through study of micromorphology data were also obtained on mineralogies of several size fractions characteristics shared by the recent and buried soils indicate that essentially the same processes operated in their formation the oldest soils are buried under protohistoric sites and thus were formed at least 5000 years ago they are developed on sediments rich in sand sized mica flakes which indicate an alluvial origin others are buried beneath historic sites with ages ranging from 500 b c to 1500 a d these soils and the recent ones have a silt fraction low in mice major features of both buried and recent soils are attributed to biological activity reflected in extensive channeling and additions of excrements throughout profiles local distribution of clay silt and carbonates indicates translocation of these components furthermore the forms of calcitic features indicate modifications of various kinds evidence of biological activity as expressed in characteristics of the soils becomes progressively weaker from older to younger profiles soil development seems to have weakened over that period as well these changes are correlated with the decline with time in the proportions of mica flakes in coarse fractions the decline is attributed to lack of alluvial sedimentation since the protohistoric period and to greater transport and winnowing of sediments by wind we believe this has reduced fertility of the soils formed during the last 4000 years

comparative micromorphology of two late pleistocene paleosols in the paris basin summary the micromorphology of two late pleistocene paleosols in the paris basin st pierre les elbeuf and bois du moulin were studied in order to characterize their pedogenic and sedimentary processes and to reconstruct and interpret the pedosedimentary history and climate of each profile the micromorphological observations of greatest interpretive value were the types of clayey and silty textural accumulations argillans and siltans pedality and porosity of lesser value were papules bioactivity and concretions during the last interglacial period on both profiles developed a sol brun lessive comparable to those developed during the holocene with the onset of cold conditions of the last glaciation the two differentiate pedologically and sedimentologically at elbeuf in the seine valley we observe colluviation of silts and the development of grey forest soils with strong textural degradation under cold and moderately dry local conditions at moulin on the plateau the grey forest phase is very weak and probably brief and is followed by a marked phase of churning and eluviation of silt conditions were wetter than in the valley such that the upland position protected the profile from colluvial truncation the advantages of micromorphology in interpreting pedo sedimentary sequences is discussed

pedogenic modification of loess significance for palaeoclimatic reconstructions abstract this review considers the role of pedogenic processes in modifying wind blown dust loess concentrating particularly on the ways that resulting properties may be interpreted as indicators of past climatic conditions and changes emphasis is placed on the sequences of palaeosols developed within loess deposits that are frequently regarded as some of the best terrestrial equivalents of marine sediment records of long term global climatic change a palaeosol is generally interpreted in terms of the broad pedogenic processes and environments assumed to be currently responsible for that type of soil forming at the present surface even the very presence of a palaeosol may have palaeoclimatic significance however in that it is often taken to indicate a period of relative land surface stability and warmer and or moister conditions between cold and or arid phases of loess accumulation in reality it may be more useful to consider many loess palaeosol sequences in terms of changing balances between pedogenesis and loess accumulation over geological time in most regions it seems that the balance swings towards pedogenesis during interglacials or interstadials when sediment supply and transport are limited and the climate is warmer and or wetter where accumulation rates are still appreciable during these soil forming intervals however the soils and palaeosols may be accretionary with surface build up keeping pace with pedogenesis welding may also occur where covering sediments are insufficiently thick to isolate an underlying palaeosol from the effects of pedogenesis active at a new land surface further complications occur due to reworking of palaeosols and syndepositional pedogenic alteration of loess units generally such pedocomplexes can only be deciphered if the different pedogenic geomorphic and sedimentary processes are identified and ordered within a pedosedimentary reconstruction a recent trend has been to treat some loess palaeosol sequences as quasi continuous time series particularly when comparing depth functions of climatic proxy properties such as magnetic susceptibility and grain size with marine and ice core isotope curves

the 2010 maule chile earthquake downdip rupture limit revealed by space geodesy radar interferometry from the alos satellite captured the coseismic ground deformation associated with the 2010 mw 8 8 maule chile earthquake the alos interferograms reveal a sharp transition in fringe pattern at 150 km from the trench axis that is diagnostic of the downdip rupture limit of the maule earthquake an elastic dislocation model based on ascending and descending alos interferograms and 13 near field 3 component gps measurements reveals that the coseismic slip decreases more or less linearly from a maximum of 17 m along strike average of 6 5 m at 18 km depth to near zero at 43 48 km depth quantitatively indicating the downdip limit of the seismogenic zone the depth at which slip drops to near zero appears to be at the intersection of the subducting plate with the continental moho our model also suggests that the depth where coseismic slip vanishes is nearly uniform along the strike direction for a rupture length of 600 km the average coseismic slip vector and the interseismic velocity vector are not parallel which can be interpreted as a deficit in strike slip moment release

coseismic gravity changes of the 2010 earthquake in central chile from satellite gravimetry 1 the first map of coseismic changes in gravity and geoid height has been drawn using the data from the gravity recovery and climate experiment grace satellites for the 2004 sumatra andaman earthquake here we present the second case of coseismic gravity change observation by satellite gravimetry i e the change caused by an interplate thrust earthquake that occurred on 27 february 2010 in central chile mw 8 8 gravity showed a negative jump with the largest drop of 5 gal on the back arc side the observed changes agree with those calculated assuming the realistic earth and fault parameters inferred from coseismic displacements of global positioning system gps stations gravity in this area shows large seasonal and inter annual variability and postseismic gravity changes could be isolated only by carefully removing hydrological signals

micromorphology of atlantic rankers on the coast of northern portugal summary the micromorphological examination of atlantic rankers on the coast of northern portugal shows the importance of alternating phases of landscape stability and instability during the genesis of the profiles archaeological artifacts and marine deposits allow the dating of these events recent pedogenesis is characterized by the formation of a microgranular structure and the illuviation of amorphous organic matter remnants of an older leached phase in the gelfa section reflect an initial weakly base desaturation stage during historical times the soil was buried under eolian sands

an archaeopedological and phytolitarian study of the dark earth on the site of rue de dinant brussels belgium during the excavations of the site of rue de dinant in the historic centre of brussels belgium remains of the first city wall dating from the 13th century have been discovered intra muros thick dark sediment units predating this wall are observed these dark units are among the oldest occupation traces so far encountered in this higher eastern part of the historic centre of brussels in order to characterise them and to understand the human activities and natural processes behind their formation an interdisciplinary research integrating archaeopedology and phytolith study has been undertaken this approach permitted us to identify a range of natural and cultural processes leading to the formation of these dark layers and to characterise different activities remains of a hearth old plough land cropfields and grassland have been identified all activities referring to a rural landscape organisation later on the area changes into an enormous silt extraction area whereby dark earth is thrown into the dug pits finally the construction of the first city wall marks the area as becoming part of the city the study of dark earth shows to be a potentially valuable tool to shed light on the development and spatial organisation of pre urban brussels a historically very poorly documented period

coseismic deformation from earthquake faulting on a layered spherical earth summary a method for calculating the static displacement field following earthquake faulting in a layered spherical earth is presented at shallow levels the earth s layering is characterized by sharp jumps in bulk and shear moduli at the conrad discontinuity and the moho and is therefore important to consider when evaluating crustal deformation the solution to the equations of static equilibrium is represented as a superposition of spheroidal and toroidal components that each depend on spherical harmonic degree and the moment tensor a method that has recently been applied to the problem of wave propagation on a layered spherical earth is here applied to the static deformation field by representing the point source in terms of discontinuities in the displacement stress vector the green s function for a particular source geometry is derived directly numerical tests are presented to verify the accuracy of the method and to illustrate the effects of sphericity and layering on the calculated deformation fields the effect of sphericity is generally less than about 2 per cent of maximum deformation within 100 km of an earthquake source at crustal depths comparisons between the deformation calculated on a spherical homogeneous earth and spherical layered earth show that up to 20 per cent errors would be introduced if the earth s layered structure were ignored the effect of layering is strongest for sources with a strong horizontal slip component

early holocene soil cryoturbation in northeastern usa implications for archaeological site formation abstract the study of buried soil archives in alluvial settings can be used to characterize floodplain and terrace habitats and complement other paleoenvironmental and archaeological archives this study examines the early holocene alluvial paleopedology along the delaware river valley in the northeastern usa chronological and alluvial stratigraphic data show that a widespread loam alluvial paleosol formed from 10 7 to 9 3 ka herein referred to as the jennings lane pedocomplex jlp the jlp at the jennings lane locality along the delaware river nj is a loam to silt loam soil that formed on mixed alluvium and windblown and or reworked dust likely sourced from nearby periglacial fines this finding supports previous interpretations of late quaternary dust deposition and reworking in the region fragic properties e g firm peds with brittle manner of failure and rapid slaking in water and cryogenic micromorphological features lenticular pores stone jacking and shattered grains present within the jlp suggest cryoturbation soil mass balance modeling suggests that the strain in immobile elements ti and zr show a dilation collapse profile these data indicate that organic matter and or dust addition and freeze thaw created soil dilation at the jlp paleosurface mass balance additions in fe k and mg are consistent with illuviated fe rich clay coatings present in thin section the x ray diffraction results show that these clays are illite vermiculite and kaolinite paleosol data presented here suggest that the jlp was overprinted by later pedogenic processes during the middle holocene ti na shows minimal loss throughout much of the profile although rapid thaws may have promoted downward translocation of fines the cold environment impeded base loss through either minimal release of cations from primary minerals or negligible water flux as suggested by ti na profiles and gains in ti k and ti mg this silt rich jlp pedofacies experienced minimal chemical depletion over the course of 1200 3500 years this cold climate weathering coincides with rapid temperature fluctuations 10 5 9 3 8 2 ka during the early holocene in northeastern usa this soil cryoturbation evidence has archaeological implications as well the cryoturbation in this early holocene pedocomplex suggests that vertical and lateral artifact redistribution is possible archaeologists should use caution when interpreting archaeological stratigraphy and intrasite artifact patterns at mid to high latitude archaeological sites

comparison of soils in midwestern united states and western europe with the interglacial record abstract paleosols that formed primarily before the last glaciation cannot be adequately explained by a model of holocene like interglacial periods of about 10 000 yr in length which has been inferred from the marine 18 o 16 o record geological and palynological evidence from terrestrial midlatitude sites suggests that temperate conditions conducive to soil formation existed for periods greatly in excess of 10 000 yr during the middle and late pleistocene available data on soils formed during this interval from western europe and midwestern united states are best explained by relatively long interglaciations or the development of composite soils over a number of temperate periods climatic contrasts between the interglaciations appear to have been overemphasized widespread assumptions regarding greater warmth in interglaciations prior to the present one are generally unproven in the absence of precise dating progress in relating paleosols to fragmentary local records of quaternary climatic changes will be achieved by detailed analytical techniques such as soil micromorphology

palaeoenvironmental and stratigraphic significance of the valley farm and barham soils in eastern england abstract the valley farm and barham soils are important stratigraphic units representing an early and or middle pleistocene depositional hiatus within parts of eastern england the barham soil buried beneath anglian sediments is recognised by a variety of large and small scale cryogenic features which developed in cromerian sediments or were superimposed upon the valley farm soil during the early anglian the valley farm soil is rubified mottled and contains substantial quantities of translocated clay originally attributed solely to temperate cromerian stage pedogenesis its stratigraphic status has changed over recent years as the age range of its kesgrave sands and gravels parent material has been extended currently the valley farm soil is regarded as a complex stratigraphic unit with component soils developed on a series of different age surfaces perhaps spanning cold and temperate intervals over more than a million years detailed micromorphological studies of the valley farm soil on some of these surfaces have confirmed its variable pedological complexity a number of theoretical and practical problems however need to be confronted and solved before its pedological record can be used routinely to provide an independent means of dating and reconstructing detailed palaeoenvironments

studying urban stratigraphy dark earth and a microstratified sequence on the site of the court of hoogstraeten brussels belgium integrating archaeopedology and phytolith analysis abstract soil micromorphology has become an important tool in urban archaeology to investigate enigmatic dark humus rich apparently homogeneous units known as dark earth it has also proven to be of great value to study microstratified sequences such as floors allowing a finer grained picture phytolith studies have also shown to be of particular interest to investigate archaeological layers especially where other botanical remains are poorly preserved the integration of phytolith studies and micromorphology allows understanding of the distribution and orientation patterns of the phytoliths and their relation to other features fabrics contributing to a better understanding of taphonomical processes and the identification of different human activities the aim of the present article is to demonstrate the possibilities of such an integrated approach by the example of the site of the court of hoogstraeten situated near the top of a steep slope next to the palace of the dukes in the centre of brussels belgium the present article focuses on one complex sequence that includes two levels of dark earth and a microstratified sequence the integrated study demonstrates that the formation of the dark earth on the site of the court of hoogstraeten results from multiphased processes whereby various human actions interact with natural phenomena among the human activities pasturing crop growing manuring and composting have been identified the microstratified sequence has been identified as a potential floor layer as such this approach does not only allow understanding the site formation processes both from homogenised units like dark earth and microstratified ones but also identification of ancient activities that are rather difficult to interpret based on field data alone

pleistocene sediments soils and landscape evolution at stebbing essex pleistocene sediments and soils exposed at stebbing in central essex england are described analysed and interpreted the sand and gravel units above eocene london clay and upper pliocene red crag are shown to be a high level member of the kesgrave formation with a surface immediately beneath that of the westland green gravels which are tentatively assigned to the pre pastonian a stage of the british quaternary succession the rubified argillic soil developed in the surface of these fluvial deposits is a composite of the valley farm and barham soils and displays micromorphological evidence of several phases of clay illuviation gleying and clay coating disruption originally truncated and buried beneath anglian gelifluction deposits cover sand and till the soil has been exhumed in most places by subsequent erosion the full succession however is preserved within large gulls that formed by periglacial cambering prior to this erosion more recent loess incorporation and pedogenesis have modified the exhumed soil and the materials within the gulls

medieval markets a soil micromorphological and archaeobotanical study of the urban stratigraphy of lier belgium market places remain underrepresented in studies of archaeological soil micromorphology in lier micromorphology was applied to gain understanding of the stratigraphy and formation processes of the medieval grote markt block samples were obtained from a sediment profile that spanned the 11th 15th century and contained three separate phases of thick dark coloured humic homogeneous layers so called dark earth combined with textural and archaeobotanical analyses seeds fruits and phytoliths the results shed light on the formation processes that shaped this site the oldest dark earth dated to the 11th century was characterised by agricultural activities the second dark earth 12 13th century formed as a result of intensive human activities witnessing the site s transformation to an urban space this layer contained large amounts of organic matter and anthropogenic inclusions and developed gradually in situ it probably represents an early market or open space close to dwellings or small courtyards units that contain evidence for intensive building activity separate the second and third dark earth and are possibly the result of a spatial re organisation of the square the formation of the third dark earth which started in the 14th century is characterised by an intensification of traffic and craftworking activities surfaces may have been maintained by spreading organic matter such as leaves sand and hearth detritus however there is no evidence for a kept empty urban square before a thick layer of levelling sand was deposited in the second half of the 14th century at earliest and the market was cobbled the analysis shows that mixed market activities took place in this intensively used zone and presents a number of micromorphological characteristics and inclusions typical of a medieval market place in a temperate climate

pedosedimentary division rock magnetism and chronology of the loess palaeosol sequence at roxolany ukraine abstract the loess mantle of the viii dniestre terrace at roxolany in the black sea area of ukraine is subdivided into six units which encompass the following palaeosol taxons pedocomplexes pk with evidence for several soil forming and sedimentary episodes incipient monogenetic palaeosols and horizons of carbonate concretions these cyclical loess palaeosol units provide a depositional record from the end of the matuyama chron through the holocene the detailed pedosedimentary subdivision of loesses at roxolany is generally consistent with magnetic susceptibility depth functions and seems to reflect global climatic variations earlier chronologies guidebook of the international geological congress xxvii session 1984 are re estimated on the basis of a revised position of the matuyama brunhes boundary and by detailed rock magnetic and micromorphological studies the strongly developed chernosem of pk 4 at approximately 22 m depth showing features of rubefication and the highest magnetic susceptibility value is viewed as a good stratigraphic marker of the late cromerian and seems to represent the climatic optimum of the brunhes chron oxygen isotope stage 13 the uppermost pk 2 is represented in the lower part by a chernosem analogous to surface soils of the area and is argued to be no younger than the last interglacial oxygen isotope stage 5e the poor preservation of pk 2 seems to result from processes of soil degradation and deflation at the time of interglacial glacial transition the closely spaced palaeosols between pk 2 and pk 4 seem to relate to three independent interglacials highest resolution of the palaeoclimatic record is found at the final matuyama chron from pk 9 to pk 8 and in incipient soils that contain either humic horizons with enhanced magnetic susceptibility or only horizons of large carbonate concretions

offshore geodetic data conducive to the estimation of the afterslip distribution following the 2003 tokachi oki earthquake a cable based seafloor observatory located offshore of hokkaido japan provides the world s first direct observation of offshore post seismic displacement after removing thermal noise this data is used to constrain the distribution of offshore afterslip from a great interplate earthquake mw 8 0 that occurred during 2003 along the southern kuril trench a checkerboard resolution test showed a great contribution of the offshore data to improving the spatial resolution on the plate interface slip near the trench the 1 yr afterslip is distributed in a u shaped pattern encircling its co seismic slip area this result indicates that the stick slip frictional properties of the plate interface are distributed in a patch like pattern as opposed to a banding pattern as previously assumed in young subduction zones

the influence of gravity on the displacement field produced by fault slip we calculated surface displacements produced by a synthetic megathrust earthquake using two spherical layered elastic dislocation models which differ only in that one model accounts for the coupling between elasticity and gravity and the other does not we show that including gravity perturbs the displacement field differently in the near medium and far fields as a result slip inversions based on an earth model without gravity cannot simultaneously fit the near medium and far field displacements generated using a forward model including gravity this suggests that the spatially systematic misfits between observations and dislocation predictions seen in the literature arise at least in part because these studies are based on models that neglect gravity although the magnitude of the far field displacements is small compared to those of the near field our slip inversions show the most improvement when we both up weight the far field observations and use a physically consistent model in the inversion

micromorphological approach to polycyclic pedogenesis on the messak settafet plateau central sahara formative processes and palaeoenvironmental significance the messak settafet is a wide plateau located in the libyan central sahara sw fezzan it is cut into the nubian sandstone and interpreted as relic of a tertiary peneplain heavily affected by aeolian deflation notwithstanding degradation phenomena discontinuous thin soil bodies are locally preserved below the hamada several profiles located in correspondence of different geomorphological units the hamada the endorheic depressions and the southern escarpment were described and sampled for micropedological analyses micromorphology outlined that the main characteristics of the residual b horizons from each geomorphological units are i high concentration of ferruginous nodules ii multiple generations of clay illuviation iii fragmentation and deformation of textural pedofeatures and iv calcite mobilization and redeposition according to horizon macro and micromorphological characteristics these pedologic bodies do not seem to be in equilibrium with the present day climatic conditions and should be regarded as paleosols generated by processes regulated by large water availability and warm temperature such as rubification clay translocation and calcite redistribution the development of horizons acted mainly since the early middle pleistocene during subsequent pluvial periods and was interrupted by several erosional and aeolian input phases arid periods pedological processes ended at the onset of the severe dry environmental conditions at the mid late holocene transition the development of this kind of paleosols in the central sahara is also discussed in comparison with pedogenetic processes occurring in temperate regions during interglacial and interstadial intervals

structural boundaries and biotite and garnet isograds in the otago and alpine schists new zealand the otago and alpine schist belts of southern new zealand have traditionally been treated as structurally continuous metamorphic belts with minor modification by brittle faulting mapping of biotite and garnet isograds has been hindered by rock types unfavourable for index mineral growth closer examination of well exposed boundaries between metamorphic zones shows that they juxtapose rocks of different type and structural history apparent structural continuity across these zones is due to development of a locally pervasive boundary parallel foliation on both sides of the boundary in a broad boundary zone up to 2 km wide this feature has implications for mapping and metamorphic petrology in other metamorphic belts where structural continuity has traditionally been assumed true metamorphic isograds may be rare and metamorphic zones may more commonly represent structural slices of complex tectonically disrupted metamorphic piles

a micromorphological and chemical study of a buried saalian till deposit in the northern part of the netherlands abstract macro and micromorphological characteristics as well as textural chemical and mineralogical properties of a reddish brown saalian till deposit covered by a 50 cm aeolian sand layer are discussed morphological observations show an interaction between pedogenetic processes and frost effects the glacial origin of the till resulted in a very dense fabric mechanical action of ice lense growth has further enhanced this compaction the occurrence of alternating freezing and thawing conditions was indicated by sorted platy structures superimposed on these frost effects and therefore younger are features of biological activity brunification and clay illuviation these originated from interglacial pedogenesis under more temperate conditions the occurrence of an aeolian deposit on top of the till indicated a subsequent cold and dry period disrupted clay illuviation coatings in the 2btg horizon and the absence of these clay coatins in situ in a network of frost cracks and sandy involutions in the 2btg horizon provide evidence of more recent periglacial conditions silt and impure clay coatings dominantly present in frost cracks are typical sorting and accumulation products due to micro erosion enhanced by snow meltwater under cold conditions surface water gley features like iron and manganese compounds overlay periglacial structures and clay illuviation and are therefore younger ferrolysis occurring predominantly in the e horizon and in frost fissures favoured textural heterogeneity of the soil

pedosedimentary history and floodplain dynamics of the lower cretaceous upper blairmore group southwestern alberta canada thick alluvial successions in the upper blairmore group in the foothills of southwestern alberta contain few well developed paleosol profiles but abundant evidence of pedogenic modification the pedogenically modified successions are characterized by vertical root traces compound illuvial clay coatings and ferruginous coatings and nodules five representative paleosol successions composed of nine microfacies are analyzed the paleosol successions indicate soil development on more or less continuously aggrading floodplains however locally rates of sedimentation and pedogenesis were highly variable the paleosol successions contain features similar to modern alluvial soils brunisols and luvisols vertical trends within individual paleosol successions preserve the changing paleoenvironmental record at each site the dynamic nature of the floodplain topography is reflected in alternating drainage conditions represented by quasi regular colour banding compound clay coatings and the type and degree of pedogenic development upwards within the paleosol successions overall the paleosols indicate soil development under a warm temperate paleoclimate with seasonal precipitation although representing minor diastems the paleosols formed contemporaneously with sedimentation and are an integral part of the alluvial successions local variations in paleosol development are attributed to variations in sediment supply and water table conditions related to the overall floodplain geomorphology

loess and early land use geoarchaeological investigation at the early neolithic site of guobei southern chinese loess plateau abstract prehistoric land use at the guobei site and its relationship with the local environment are examined by applying osl dating micromorphological examination and geo physical analysis the majority of the osl dates are of early to middle holocene ages and are thus comparable to many osl dates derived from other studies in the same region according to the particle size analysis silt sized particles 2 60 m were predominant throughout the profiles examined however there are spatial and temporal variations of different size groups of particles throughout the profiles which provide complementary information for the micromorphological interpretation the total organic component of the samples examined through loi is relatively high all 2 with those of the overlying holocene deposits higher than those of the underlying malan loess by about 0 2 moreover in all three profiles the highest organic contents appear in the palaeosols confirming that there was greater organic accumulation during soil formation periods the groundmass of most slides collected from the early to middle holocene horizons displays a very homogeneous pattern while the abundance and distribution of different kinds of pedo features mainly including clay textural calcitic iron mn and crustal features vary greatly temporally and spatially these different lines of information demonstrate diversified pedo sedimentary processes due to variations in micro environmental conditions and cultural activities we discuss the importance of a palaeo ecological perspective allowed by the geoarchaeological study to an improved understanding of the relationship between loess changing hydrology prehistoric farming practice and land use and long term landscape change in the chinese loess area this will thus contribute to a comparison on the dynamic relationship between loess and prehistoric farming in other regions of the world such as europe and north america

general formulations of global co seismic deformations caused by an arbitrary dislocation in a spherically symmetric earth model applicable to deformed earth surface and space fixed point summary based on the authors previous work co seismic deformations for a spherical symmetric earth model are summarized and reformulated unified expressions presented herein accommodate physical deformations displacement potential gravity geoid and strain changes the corresponding green s functions are derived by combining spheroidal and toroidal deformations sign errors in previous publications are corrected in these new formulas these expressions are developed basically for a deformed earth surface because most traditional geodetic measurements are performed on the terrain surface however through development of space geodetic techniques such as the satellite gravity missions co seismic gravity changes can be detected from space in this case the above dislocation theory e g the co seismic gravity change cannot be applied directly to the observed data because the data do not include surface crustal deformation the free air gravity change correspondingly the contribution by the vertical displacement part must be removed from the traditional expressions for this purpose we present the corresponding expressions applicable to space observations some numerical technical problems are discussed in addition a smoothing technique is necessary to damp the high frequency contribution so that the theory can be applied reasonably global co seismic deformations caused by the 2004 sumatra andaman earthquake m9 3 are studied as an application of the new green s function that earthquake caused a global deformation detected by gps strain metres and even a satellite gravity mission these global deformations are calculated based on the derived green s functions and the seismic wave derived earth model a segment summation scheme is used considering the slip distribution on a limited fault plane the results are useful for interpreting observed deformations especially those in the far field the earthquake reveals global co seismic deformations and effects of spherical curvature and the earth s layered structure comparisons between results for a spherical earth mode and a half space model show a large discrepancy at an epicentral distance of about 1000 km implying that effects of spherical curvature and layer structure are considerably large in addition the theoretical results are compared with the real observed strain steps horizontal displacements and gravity changes caused by that earthquake good agreement validates the results of the current theoretical work finally we discuss the application the above theory to the grace data through several case studies

buried palaeosols of nw sardinia italy as archives of the late quaternary climatic fluctuations abstract a multi disciplinary approach was performed to investigate two compound geosols included between wind blown deposits at the top and interglacial mis 5 beach sediments at the bottom located along the alghero coast north western sardinia italy a sedimentological and morphological study was carried out on the profile in the field and samples collected on the main pedomembers were subjected to several laboratory analyses consisting of physical and chemical determinations on bulk samples mineralogy xrd micromorphology on undisturbed samples thin section sem and edax micro probe analyses dating was performed by means of optically stimulated luminescence osl the studied geosols show the evidence of a complex pedosedimentary evolution around 80 to 70 ka the lower geosol underwent weathering and clay illuviation wet and warm conditions followed by calcification recalcification processes dry contrasted and finally by strong bioturbation around 70 ka the onset of the glacial period mis 4 is marked by the deposition of a sand dune capping the lower geosol these results indicate that the coastal area of the central mediterranean kept the relatively warm conditions typical of the interglacial climate for most of the early wurm and reached cold conditions only at about 70 ka possibly in relation to the rapid cooling of the heinrich event h7 the upper geosol developed on colluvial material including abundant pedorelicts and reddish earth material deposited around 50 ka before being buried by aeolian sand around 43 ka this deposit underwent pedogenesis phases possibly associated to middle wurm interstadial events indicating that in the study area these events were intense enough to influence pedogenesis

gravitational viscoelastic postseismic relaxation on a layered spherical earth viscoelastic relaxation of a ductile asthenosphere underlying a purely elastic plate is a strong candidate process for explaining anomalous rates of crustal deformation observed following large earthquakes the nongravitational treatment of pollitz 1992 which is valid on a global scale and includes the effects of compressibility is here extended to permit the calculation of gravitational viscoelastic relaxation for a specified spherically layered viscoelastic rheology following an earthquake in an elastic layer the simple approximations we adopt make the resulting treatment particularly suitable for near field calculations for an asthenosphere with a maxwell rheology the effect of gravitational coupling is manifested only many relaxation times after the earthquake as obtained by previous investigators its effect is generally to speed up the long wavelength component of the relaxation process and attenuate the overall vertical displacement pattern several subtle features common to the relaxation behavior from several different fault types thrust rift and strike slip are identified the effect of gravitational coupling on horizontal displacements is consistent with flexure of the upper elastic plate driven by the corresponding effects on the vertical displacement stress diffusion away from the source region generally exhibits pulse like behavior which is dispersive in both space and time if the asthenosphere is confined to a relatively narrow channel then the dispersion branches governing relaxation are radically altered and stress diffusion effects far from the coseismic rupture zone exhibit a complicated time dependence reflecting the competing tendencies of toroidal and spheroidal mode relaxation

use of micromorphology for palaeoenvironmental interpretation of complex alluvial palaeosols an example from the mill creek formation albian southwestern alberta canada abstract field observations are often not sufficient for process based interpretations of palaeosols particularly where they form parts of thick aggradational pedocomplexes within alluvial successions under such conditions micromorphology provides genetic temporal and spatial information on soil forming processes that is critical to an understanding of past environmental conditions thick alluvial successions of the albian mill creek formation contain abundant evidence of pedogenesis but few well developed palaeosol profiles and therefore provide an ideal case study in which to demonstrate the usefulness of micromorphological data for palaeoenvironmental interpretation the micromorphological features of greatest interpretive value are types of clay coatings and ferruginous segregations structure and fabric papules evidence of bioactivity and ferruginous concretions provide information on geomorphic surface stability and assist in reconstructing temporal changes in drainage conditions while individual features can provide some palaeoenvironmental information the relationships of features to one another and assemblages of features provides additional information when analysed hierarchically to establish a sequence of sedimentologic and pedogenic events a common recurring sequence of palaeoenvironmental events subject to local variations can be recognized throughout the mill creek formation the presence of illuvial clay requires that water percolated through the soil and that the soil periodically dried out so that the translocated clay was retained dark reddish clay coatings indicate clay illuviation under freely drained conditions while pale yellow and silty clay coatings suggest that phases of free drainage alternated with phases of poorly drained or saturated soil conditions the presence of iron depletion coatings iron nodules and quasiferrans indicates that these units were at least periodically saturated and the occurrence of multiple overlapping phases within single thin sections demonstrates that redox conditions fluctuated strongly suggesting development in the vadose zone recent soils containing similar assemblages of features develop under warm temperate seasonal climates alternating phases of well drained and saturated conditions on the mill creek floodplains are attributed to changing sediment supply and local palaeogeomorphology rather than to any major regional climate change this type of process based micromorphological analysis should have broad application in other complex pedogenically modified alluvial successions and similar studies would lead to a more detailed understanding of ancient palaeoenvironments

coseismic slip distribution of the february 27 2010 mw 8 8 maule chile earthquake 1 static offsets produced by the february 27 2010 mw 8 8 maule chile earthquake as measured by gps and insar constrain coseismic slip along a section of the andean megathrust of dimensions 650 km in length 180 km in width gps data have been collected from both campaign and continuous sites sampling both the near field and far field alos palsar data from several ascending and descending tracks constrain the near field crustal deformation inversions of the geodetic data for distributed slip on the megathrust reveal a pronounced slip maximum of order 15 m at 15 25 km depth on the megathrust offshore lloca indicating that seismic slip was greatest north of the epicenter of the bilaterally propagating rupture a secondary slip maximum appears at depth 25 km on the megathrust just west of concepcion coseismic slip is negligible below 35 km depth estimates of the seismic moment based on different datasets and modeling approaches vary from 1 8 to 2 6 1022 n m our study is the first to model the static displacement field using a layered spherical earth model allowing us to incorporate both near field and far field static displacements in a consistent manner the obtained seismic moment of 1 97 1022 n m corresponding to a moment magnitude of 8 8 is similar to that obtained by previous seismic and geodetic inversions

short term afterslip in the 1994 sanriku haruka oki earthquake the sanriku haruka oki earthquake that occurred on december 28 1994 at the japan trench as a typical interplate thrust event was followed by year long afterslip as large as the slip in the high speed rupture heki et al 1997 here we report on the transition between these inferred from crustal movements during the five days interval before and after the earthquake since this timescale is too long for seismometers but not suitably long for global positioning system gps we rely primarily on strainmeter data taken 200 km southwest of the epicenter to confirm that the recorded strain changes are not local disturbances we compare them with crustal movements derived by high time resolution analyses of gps data in the same period the transition to the long term afterslip was gradually achieved by slow fault slip with a time constant of a few hours the cumulative slow slip in 24 hours amounts to 1 3 of the coseismic slip i e we may overestimate the coseismic displacement if we look at gps data time series composed of daily solutions the result presented here indicates that a single earthquake could have multiple aspects in its slowness visible with different seismological and geodetic tools and we need to use all such data to understand fully such a hybrid earthquake

inverting for slip on three dimensional fault surfaces using angular dislocations the increasing quality of geodetic data synthetic aperture radar interferometry insar dense global positioning system gps arrays now available to geophysicists and geologists are not fully exploited in slip inversion procedures most common methods of inversion use rectangular dislocation segments to model fault ruptures and therefore oversimplify fault geometries these geometric simplifications can lead to inconsistencies when inverting for slip on earthquake faults and they preclude a more complete understanding of the role of fault geometry in the earthquake process we have developed a new three dimensional slip inversion method based on the analytical solution for an angular dislocation in a linear elastic homogeneous isotropic half space the approach uses the boundary element code poly3d that employs a set of planar triangular elements of constant displacement discontinuity to model fault surfaces the use of triangulated surfaces as discontinuities permits one to construct fault models that better approximate curved three dimensional surfaces bounded by curved tiplines shapes that commonly are imaged by three dimensional reflection seismic data and inferred from relocated aftershock data we demonstrate the method s ability to model three dimensional rupture geometries by inverting for slip associated with the 1999 hector mine earthquake the resulting model avoids displacement anomalies associated with the overlapping rectangular dislocations used in previous models improving the fit to the geodetic data by 32 and honors the observed surface ruptures thereby allowing more direct comparisons between geologic and geodetic data on slip distributions online material hector mine input files and file format description

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

architecture of the lower terraces and evolution of the dordogne river at bergerac southwest france during the last glacial interglacial cycle the lower terraces of the dordogne river at bergerac south west france were studied in detail using cores trenches ground penetrating radar profiles and 14 c optically stimulated luminescence and infrared stimulated luminescence dating this study shows that the lowest terrace fx is made up of two major lithostratigraphic units i dominantly horizontal gravel strata interpreted as compound bar deposits in a braided river which pre date 18 17 ka and ii thick lateral accretion gravel units point bars formed in an anabranching river during the late pleniglacial and lateglacial most of the anabranching channels were abandoned at ca 11 10 ka following shrinkage of the river bed into a single meandering channel and were partially filled by gyttjas during the boreal chronozone finally the channels were plugged by overbank fines until about 5 ka floods seldom reached the fx terrace during the late holocene and accretion became negligible the main phase of bedrock incision spanned the holocene whereas the period of channel adjustment to change in river regime during late marine isotope stage mis 2 only led to a redistribution of the pleniglacial gravels the higher terrace fw3 formed before the eemian and was covered by colluvial fans mainly during mis 2 and 3

2010 maule earthquake slip correlates with pre seismic locking of andean subduction zone analysis of seismic data and global positioning system gps observations from the region around the site of the recent magnitude 8 8 maule earthquake in chile have been combined with modelling of the andean subduction zone to build up a detailed image of the event the earthquake occurred at a seismic gap part of the fault that has not experienced a major earthquake since 1835 and it seems to have released most of the stress accumulated since that time the observations suggest that coseismic slip heterogeneity at the scale of single asperities and therefore the seismic potential of future great earthquakes might be anticipated by geodetic observations these authors show evidence for a high coherence between the slip distribution inferred from the 2010 maule earthquake chile and the patchwork of interseismic locking distribution derived from global positioning system observations during the previous decade their work suggests that coseismic slip heterogeneity at the scale of single asperities should indicate the seismic potential of future earthquakes which thus might be anticipated by geodetic observations the magnitude 8 8 maule chile earthquake of 27 february 2010 ruptured a segment of the andean subduction zone megathrust that has been suspected to be of high seismic potential1 2 3 4 5 6 it is the largest earthquake to rupture a mature seismic gap in a subduction zone that has been monitored with a dense space geodetic network before the event this provides an image of the pre seismically locked state of the plate interface of unprecedentedly high resolution allowing for an assessment of the spatial correlation of interseismic locking with coseismic slip pre seismic locking might be used to anticipate future ruptures in many seismic gaps6 7 8 9 10 11 12 given the fundamental assumption that locking and slip are similar this hypothesis however could not be tested without the occurrence of the first gap filling earthquake here we show evidence that the 2010 maule earthquake slip distribution correlates closely with the patchwork of interseismic locking distribution as derived by inversion of global positioning system gps observations during the previous decade the earthquake nucleated in a region of high locking gradient and released most of the stresses accumulated in the area since the last major event in 1835 two regions of high seismic slip asperities appeared to be nearly fully locked before the earthquake between these asperities the rupture bridged a zone that was creeping interseismically with consistently low coseismic slip the rupture stopped in areas that were highly locked before the earthquake but where pre stress had been significantly reduced by overlapping twentieth century earthquakes our work suggests that coseismic slip heterogeneity at the scale of single asperities should indicate the seismic potential of future great earthquakes which thus might be anticipated by geodetic observations

recycled loesses a micromorphological approach to the determination of local source areas of weichselian loess the article presents the results of micromorphological studies of selected neopleistocene loess palaeosol sequences broader studies of thin sections are presented for the polanow samborzecki zlota site they served as models for analysis for similar targeted observations in other sequences on their basis 3 groups of microfeatures litho pedo and cryogenic were described an additional group are pedogenic features clay concentrations selected fe and mn fe nodules as well as charcoals documented in non soil locations generally limited to loess macroscopically defined as primary an analysis of these features shows that these are redeposited pedogenic microfeatures occurring in a secondary location according to this genetic interpretation they can be identified as pedorelicts and possibly also as lithorelicts these features clearly show that the older pedogenically modified layers were involved in the formation of younger loesses these studies show that the younger loesses are partially built of older loess material

luvisols or cambisols micromorphological study of soil truncation in young morainic landscapes case study brodnica and chelmno lake districts north poland abstract eight soil profiles in brodnica lake district and chelmno lake district were described and sampled the profiles were divided into four pairs study areas dissimilar in lithology relief or land use each pair of profile contained soil located on the crest or upper slope exposed to erosion and back slope slightly exposed to erosion positions the relief of this area is inherited from the last vistulian glaciation and represents mostly flat and hummocky moraine plateau landscapes all investigated pedons have a b horizon five profiles have vertical contrasting texture and contain a significantly developed eluvial zone a and e horizons above b horizon in three cases pedons have a b c horizon sequence to date numerous studies have shown that the soils with a b c profiles developed on moraine tills should be treated as cambisols on existing soil agricultural maps these soils are also marked as cambisols the b horizons are enriched in the clay fraction and contain low amount of carbonates in comparison with the parent material all these criteria can be used to distinguish a cambic horizon but analysis of thin sections revealed the presence of significant amounts of clay and silt illuvial features the illuvial pedofeatures resulted in these horizons being classified as argic horizons bt these soils cannot be classified as cambisols which are characterized by absence of appreciable amounts of illuvial silt and clay instead the a b c profile forms represent truncated luvisols in which the material from eluvial horizons was entirely removed the soils described in this study occur in areas where soil erosion is common the upper part of slopes and crests in arable areas the illuvial origin of b horizons in truncated pedons a b c was also confirmed by the presence of eluvial horizons in nearby soils on the back slope position slightly or non exposed to erosion the results showed that accelerated erosion had a significant role in development of soil cover in agriculture moraine landscapes of brodnica and chelmno lake districts the micromorphological analysis confirmed that the loamy soils with the a b c profile developed on ground moraine tills should be classified as truncated eroded luvisols the b horizons of these soils have significant accumulation of clay and silt features the illuvial microforms are the relic feature of eluviation illuviation lessivage process the material from the eluvial horizons of luvisols was entirely removed this study is important to understand the influence of soil erosion processes on soil cover development in young glacial regions further investigations concerning formation and characteristic of a b c soils and appropriate classification of described pedons are very important for understanding the impact of accelerated erosion in young glacial landscapes

saint illiers la ville and the micoquian of weichselian sequences of the paris basin abstract the excavation at saint illiers la ville revealed an archaeological level which contained one micoquian biface of a kind known in the vicinity and across the paris basin since the 19th century beginning of palaeolithic archaeology and through the doctoral research of francois bordes as the stratigraphy of these old collections appears similar to that of saint illiers la ville this geographical and chronological proximity raises questions about the possible technical unity of these groups in this view the technical characteristics of saint illiers la ville industries are presented and compared in this paper with the old series of the paris basin as well as with other series subsequently attributed to this micoquian entity it emerges that the micoquian biface is not suitable to define a group because it constitutes one technical solution among others present in various moments and places of prehistory however when inserted into its wide geographical chronological and technical context this type of biface is able to define a techno cultural reality accordingly it is suggested that the term micoquian should be abandoned and that a new name be chosen to designate these industries of the beginning of the last glaciation in the paris basin

palaeoclimate sedimentation and soil development during the last glacial stage devensian heathrow airport london uk abstract the langley silt complex overlying the taplow terrace of the river thames at prospect park near heathrow airport west of london is described in terms of lithology carbonate content organic carbon content particle size characteristic macrostructure micromorphology and stratigraphic position the langley silts were deposited by wind or water in cold climate conditions and include evidence for the development of periglacial structures and for devensian lateglacial and holocene soil formation the langley silts rest upon a last interglacial ipswichian ois 5e soil developed in the taplow gravel deposited during the previous cold stage ois 6 during the early devensian and the dimlington stadial and younger dryas of the late devensian wind deposited the silts and during the middle devensian wind and surface wash built up a laminated silt and sand during the middle devensian seasonal dessication formed non sorted polygonal patterns as this laminated unit aggraded but this process ceased with the return to loess deposition in the late devensian argillic soil development occurred during the windermere interstadial only to be disrupted by ground ice processes during the succeeding younger dryas cold phase the site provides one of the most complete sedimentary sequences through the last glacial stage in britain and confirms recent interpretations of soil development and evidence for aeolian deposition in britain during the lateglacial

paleoclimatic implications of micromorphic features of quaternary paleosols of nw himalayas and polygenetic soils of the gangetic plains a comparative study abstract micromorphological examination of the paleosols 50 10 ka developed in alluvial fan deposits of the nw himalayas and the bordering polygenetic soils mainly holocene of the gangetic plains has been used to differentiate the pedosedimentary features indicating climatic changes during late quaternary time the paleosols within rapidly aggrading sediments of the alluvial fans of the dehradun valley resulted in response to the reduced rate of sedimentation and climatic changes and correspond to the mis3 and mis2 stages distinctive micromorphic features of these paleosols provided the details of the prevalent pedogenesis in response to the paleoclimatic changes during 50 ka microfabrics of these paleosols show reorganization of the pedality from massive and or subangular blocky to platy and prismatic structures strong to very strong mobilization of the plasma different types of textural pedofeatures along with faunal activities these pedofeatures are indicative of cold humid climate with subsequent change to even colder but drier conditions during the last glaciation comparison of the micromorphological characters of the paleosols of the nw himalayas and the polygenetic soils of the gangetic plains show the same degree of soil development indicating 5 10 ka pedogenic intervals in alluvial fans of the dehradun valley however the difference in their pedofeatures is attributed to different pedogenic environments the paleosols of the dehradun valley show predominance of the illuvial features with superposed impure silty clay on earlier clay pedofeatures and banded clay fabric features without any pedogenic calcium carbonate the bordering gangetic plains are covered with polygenetic soils developed on stable surfaces and are

micromorphology of loess paleosol sequences a record of paleoenvironmental change abstract the record of paleoenvironmental change retained within thin sections from loess paleosol sequences is discussed with reference to case studies from western europe china and northwestern usa the paleoenvironmental significance of individual micromorphological features such as calcitic concentrations clay coatings and cryogenic structures are first evaluated and the value of recognising and interpreting microstratigraphic relationships of features in terms of paleoenvironmental change is illustrated recent developments have seen a greater emphasis on using micromorphology within a pedosedimentary approach whereby both pedogenic and sedimentary processes are taken into account when interpreting loess paleosol sequences this has led not only to the acquisition of important information on conditions during phases of enhanced loess accretion and periods of climatic transition but also to an increased awareness of spatial changes in processes and environmental controls during particular time periods micromorphologically based reconstructions have enabled the isolation of key stages of pedosedimentary development although absolute dating of stages is often limited by lack of age controls a novel approach aimed at addressing this limitation afforded by presence of datable tephra in microstratigraphic association with key micromorphological features is discussed

a dislocation model of strain accumulation and release at a subduction zone strain accumulation and release at a subduction zone are attributed to stick slip on the main thrust zone and steady aseismic slip on the remainder of the plate interface this process can be described as a superposition of steady state subduction and a repetitive cycle of slip on the main thrust zone consisting of steady normal slip at the plate convergence rate plus occasional thrust events that recover the accumulated normal slip because steady state subduction does not contribute to the deformation at the free surface deformation observed there is completely equivalent to that produced by the slip cycle alone the response to that slip is simply the response of a particular earth model to embedded dislocations for a purely elastic earth model the deformation cycle consists of a coseismic offset followed by a linear in time recovery to the initial value during the interval between earthquakes for an elastic viscoelastic earth model elastic lithosphere over a viscoelastic asthenosphere the postearthquake recovery is not linear in time records of local uplift as a function of time indicate that the long term postseimic recovery is approximately linear suggesting that elastic earth models are adequate to describe the deformation cycle however the deformation predicted for amore simple elastic half space earth does not reproduce the deformation observed along the subduction zones in japna at all well if stick slip is restricted to the main thrust zone as recognized earlier by shimazaki seno and kato the uplift profiles could be explained if stick slips were postulated to extend along the plate interface beyond the main thrust zone to a depth of perhaps 100 km but independent evidence suggests that stick slip at such depths if unlikely less

the fifth paleosol layer in the southern part of china s loess plateau and its environmental significance through field investigations dark redebrown lumpy ferruginous argillans lfas and an underlying weathered loess layer under the fifth layer s5 paleosol were discovered in the guanzhong plain in the southern part of the loess plateau in northwest china s shaanxi province the ultramicrotexture of the lfas and their mineral and chemical compositions were analyzed experimental results showed that mixed illiteesmectite minerals comprise about 90 of the lfas in mineral composition with 40 sio2 content and high fe2o3 about 10 0 and al2o3 about 22 5 contents in chemical composition neoformed microcrystalline grains of clay minerals dominated the lfas the micromineral crystal grains in the lfas were mainly plates with some degree of alignment giving the argillans crystalline optical properties red lfas and weathered loess layers under the s5 and the depth to which fe2o3 and caco3 from the s5 have been removed indicate that chemical weathering was much stronger when the paleosol layers formed than that at present while the s5 paleosol was developed a subtropical climate prevailed in the southern loess plateau with a mean annual temperature and rainfall about 4 c and 500 mm higher respectively than that at present the adequacy in moisture in at least 4 2 m of the gravitational water zone during the formation of s5 was suitable for forest growth during the warmest and moistest climate span of growth for 2 5 million years when s5 was formed the qinling mountains lost its function as a climatic boundary between the subtropical and temperate zones of east asia when the summer air masses crossed the qinling mountains and reached the guanzhong plain bringing rich precipitation

slip distribution of the february 27 2010 mw 8 8 maule earthquake central chile from static and high rate gps insar and broadband teleseismic data 1 the shallow depth underthrust earthquake of february 27 2010 mw 8 8 ruptured the subduction plate interface in central chile between 34 s and 38 s we retrieve the spatial and temporal distribution of slip during this mega earthquake through a joint inversion of teleseismic records insar and high rate gps hrgps data additionally our model is shown to agree with broadband surface waves rupture initiated at about 32 km depth and propagated bilaterally resulting in two main slip zones located ssw and nne of the hypocenter nucleation did not take place within or at the edge of one of these main asperities but in between during the first 30s slip propagated predominantly southwards later on the rupture evolved more slowly and more symmetrically eventually the northern asperity became predominant with maximum slip reaching about 20 m most of the seismic moment was released within 110s a relatively short time explained by the bilateral propagation the overall average rupture velocity is 2 6 km s but propagation occurred initially faster towards the south 3 2 km s large slip did not reach the trench a result consistent with the moderate size of the tsunami down dip rupture stopped at about 50 km depth in agreement with the lower limit of the locked zone inferred by ruegg et al 2009 from pre seismic gps data

seismic and aseismic slip on the central peru megathrust slip on a subduction megathrust can be seismic or aseismic with the two modes of slip complementing each other in time and space to accommodate the long term plate motions although slip is almost purely aseismic at depths greater than about 40 km heterogeneous surface strain suggests that both modes of slip occur at shallower depths with aseismic slip resulting from steady or transient creep in the interseismic and postseismic periods thus active faults seem to comprise areas that slip mostly during earthquakes and areas that mostly slip aseismically the size location and frequency of earthquakes that a megathrust can generate thus depend on where and when aseismic creep is taking place and what fraction of the long term slip rate it accounts for here we address this issue by focusing on the central peru megathrust we show that the pisco earthquake with moment magnitude m w 8 0 ruptured two asperities within a patch that had remained locked in the interseismic period and triggered aseismic frictional afterslip on two adjacent patches the most prominent patch of afterslip coincides with the subducting nazca ridge an area also characterized by low interseismic coupling which seems to have repeatedly acted as a barrier to seismic rupture propagation in the past the seismogenic portion of the megathrust thus appears to be composed of interfingering rate weakening and rate strengthening patches the rate strengthening patches contribute to a high proportion of aseismic slip and determine the extent and frequency of large interplate earthquakes aseismic slip accounts for as much as 50 70 of the slip budget on the seismogenic portion of the megathrust in central peru and the return period of earthquakes with m w 8 0 in the pisco area is estimated to be 250 years

a micromorphological index of soil development for the quaternary geology research abstract profile development indices of harden harden j w 1982 a quantitative index of soil development from field examples from a chronosequence in central california geoderma 285 1 98 and ferrari and magaldi ferrari g magaldi d 1983 significato ed applicazioni della paleopedologia nella stratigrafia del quaternario boll mus civ st nat verona 10 315 340 have shown their utility for comparative dating of some paleosols during geomorphological and geological surveys in italy and other countries pedostratigraphic methods have been commonly applied to soil profiles formed in continental formations unfortunately buried and relict paleosols are very scarce or badly preserved in some areas of italy due to past and recent tectonic activity and to strong human impact dating back to prehistoric times in order to use relict paleosols for correct chronostratigraphic interpretation of relict paleosols and in order to correlate them with old landscape forms for the reconstruction of quaternary sequences a new micromorphological index misodi for assessing soil development and degree of weathering was devised the index was tested in the extensional tectonic basin of l aquila scoppito abruzzi central italy where some chronostratigraphic information is available results demonstrate that there is a good relationship between presumed relative age of paleosols and degree of weathering and pedogenesis in b and b c horizons as assessed by this index the index has the potential to be adapted for application to other paleosol types in other countries

evidence for temperate soil development during the early devensian in gower south wales investigations into the micromorphology of the pwll du red beds in gower south wales have revealed pedo features in the form of compound void coatings overlying marine deposits dated to the ipswichian oxygen isotope substage 5e the red beds are interpreted as the product of sedimentation and pedogenesis during early devensian time

sedimentary and pedological processes in the upper pleistocene loess of northern italy the bagaggera sequence abstract the bagaggera sequence consists of two late pleistocene loesses superimposed on the top of middle pleistocene fluviatile sediments the lower loess includes at its base a mousterian archaeological level represented by artifacts dated by tl as 60 500 7500 bp and charcoal from hearths which mainly consists of boreal forest species at the top of the lower loess aurignacian artifacts occur which suggest a tentative date of 35 000 bp the sedimentary and pedological processes which lead to the formation of the sequence were reconstructed by means of mineral and textural analyses and thin section analysis and can be summarized as follows erosion and colluviation of the eemian soil at the base of the sequence during the early wurm isotopic substages 5 a c sedimentation of the lower loess deposits during the first pleniglacial period isotopic stage 4 a large number of coarse pedofeatures in this soil suggests that primary aeolian dust has been redistributed in place or for short distances by syngenetic slight pedogenesis and by water reworking as a result of alternating phases of wet and dry climate an alfisol characterized by strong clay illuviation developed in the lower loess during the hengelo arcy interstadial phase its top was affected by reworking and slight frost activity at the beginning of the second pleniglacial period isotopic stage 2 the upper loess was deposited in a drier environment during the second pleniglacial period isotopic stage 2 water reworking was less effective holocene weathering is expressed by clay illuviation and slight hydromorphism

micromorphology of a mousterian paleosol in aeolianites at the site habonim israel abstract a paleosol with mousterian tools in aeolianites at the habonim site carmel coastal plain israel is a complex pedosedimentary sequence which records a succession of soil forming episodes and stages of coastal dune instability we identified three strong soils and one accretionary soil within mousterian pedocomplex via micromorphological techniques coupled with ftir and sem edax in the lowermost red sandy soil hamra in unit iv decalcification led to the formation of micritic coatings disrupted by faunal churning while rubefication resulted in red ferric segregations illuviation of ferruginious clay in the form of clay coatings is lacking probably due to its strong incorporation into the matrix redox features were intensified in the pseudogley of the next stage unit iii polyphase calcitic features here indicate that illuviation of clay pre dates illuviation of micrite and its later recrystallization into sparitic calcite further deterioration of drainage conditions and increased accumulation of fine particles led to the formation of vertisol unit ii paleovertisol is characterized by a maximum of clay stress originated microfabric abundant mn precipitates and calcitic pseudomorphs the peak of landscape instability occurred later and is recorded in the upper unit i in which micromorphological signs of colluvial and aeolian processes are juxtaposed with various ferric accumulations associated with gleying the final episode occurred at a time of climatic instability devegetation and probably a simultaneous groundwater rise in the littoral zone

implications of postseismic gravity change following the great 2004 sumatra andaman earthquake from the regional harmonic analysis of grace intersatellite tracking data 1 we report gravity recovery and climate experiment grace satellite observations of coseismic displacements and postseismic transients from the great sumatra andaman islands thrust event mw 9 2 earthquake in december 2004 instead of using global spherical harmonic solutions of monthly gravity fields we estimated the gravity changes directly using intersatellite range rate data with regionally concentrated spherical slepian basis functions every 15 day interval we found significant step like coseismic and exponential like postseismic behavior in the time series of estimated coefficients from may 2003 to april 2007 for the spherical slepian functions after deriving coseismic slip estimates from seismic and geodetic data that spanned different time intervals we estimated and evaluated postseismic relaxation mechanisms with alternate asthenosphere viscosity models the large spatial coverage and uniform accuracy of our grace solution enabled us to clearly delineate a postseismic transient signal in the first 2 years of postearthquake grace data our preferred interpretation of the long wavelength components of the postseismic gravity change is biviscous viscoelastic flow we estimated a transient viscosity of 5 1017 pa s and a steady state viscosity of 5 1018 1019 pa s additional years of the grace observations should provide improved steady state viscosity estimates in contrast to our interpretation of coseismic gravity change the prominent postearthquake positive gravity change around the nicobar islands is accounted for by seafloor uplift with less postseismic perturbation in intrinsic density in the region surrounding the earthquake

floodplain palaeosols of the cenomanian dunvegan formation alberta and british columbia canada micromorphology pedogenic processes and palaeoenvironmental implications

the reconstruction of palaeoenvironment during development of the fourth palaeosol in the southern loess plateau of china abstract the fourth palaeosol s4 of the brunhes epoch 780 000 0 years b p at shuangzhu tianjiapo and hejiacun in the guanzhong plain developed over about 40 ka and varies in thickness from 3 6 to 4 0 m it consists of four horizons the first uppermost is a well developed red brown clay horizon bts the second is a dark yellowish brown weathering cracked loess horizon cs with red ferruginous argillans the third is a yellowish brown weathering cracked loess horizon cl without red ferruginous argillans and the fourth consists of caco3 nodules ck the two weathering cracked loess horizons which are a major feature differentiating a pedocomplex from a palaeosol have not been found previously in chinese palaeosol the ferruginous clay argillans are composed of montmorillonite illite with some kaolinite minerals the pedocomplex suggests that a moist subtropical climate prevailed between 420 000 and 360 000 years in the southern parts of the chinese loess plateau its profile is bts cs cl ck co when the pedocomplex was developed the mean annual temperature and precipitation were about 16 c and 1000 mm respectively about 3 c higher and 400 mm more than at present in the guanzhong plain the removal depth of caco3 and the weathering cracked loess layer indicate that the gravitational water reached a depth of at least 3 2 m and the moisture content in s4 would have been sufficient to sustain forest development at that time in the typical interglacial in which s4 was developed the qinling mountains lost their function as the boundary between the subtropical and temperate zones of china and water bearing air masses resulting in rich rainfall could frequently reach the southern loess plateau