paleopedology and stable isotope chemistry of late silurian vertic paleosols bloomsburg formation central pennsylvania abstract paleosols with vertic vertisol like features occur in repetitively stacked fining upward sequences bounded by marine erosional surfaces in the bloomsburg formation ludlovian to pridolian of central pennsylvania paleosol development was strongly influenced by repeated changes in relative sea level which resulted in subaerial exposure and pedogenesis of marginal marine sediment accumulating along a low energy mud dominated coastline in a delta plain environment bloomsburg paleosols are characterized by very weak horizonation abundant pedogenic slickensides and a micromorphology dominated by sepic fabrics and peds bounded by stress cutans pedogenic carbonate is sparse occurring principally as micrite nodules stable carbon isotope compositions of stratigraphically low pedogen c carbonate mean 13c 1 92 pdb are attributed to pedogenesis proximal to a marine coastline in stratigraphically high paleosols showing evidence of rhizolith development isotopic compositions of pedogenic carbonate suggest a significant contribution of carbon from c3 flora atmospheric p co2 levels estimated for these calcretes 4500 5500 ppmv are significantly greater than present day values low 18o values for pedogenic carbonate mean 18o 12 12 pdb record isotopic exchange between paleosol carbonate and 18o enriched fluids associated with the conversion of original soil smectites to illite and chlorite during burial diagenesis paleosols bounded by marine erosional surfaces show variable degrees of marine hydromorphism attributable to rising water table during transgression evidence for hydromorphism includes extensive reduction of iron as well as relative increases in cao mno mgo p2o5 na2o and sr at the tops of paleosols due to introduction of marine fluids and sediment into open soil fractures and burrows the abundance of vertic features in all bloomsburg paleosols by analogy with holocene vertisols indicates the recurrence of a seasonally wet dry dry 4 8 months year paleoclimate n the central appalachian region at a paleolatitude of about 20 south

stable isotopic investigation of clay minerals and pedogenesis in an interfluve paleosol from the cenomanian dunvegan formation n e british columbia canada abstract mineralogical and stable hydrogen and oxygen isotopic compositions have been obtained for clay minerals comprising an interfluve paleosol clayhurst ch 2 from the early to middle cenomanian dunvegan formation british columbia canada this paleosol provides a special opportunity to determine the stable isotopic composition of early late cretaceous paleoprecipitation on the western coast of the western interior seaway at a very northerly paleolatitude 65 detrital kaolinite and illite and complex dioctahedral mixed layer clay minerals of pedogenic origin are abundant throughout the paleosol in the d values of 93 to 81 and 18 o values of 12 9 to 11 6 were generally obtained for the ancient soil water and hence paleoprecipitation for one thin interval near the top of the paleosol higher values are indicated for the ancient soil water these results may indicate processes arising from a westward transgression of the western interior seaway

use of multiple oxygen isotope proxies for elucidating arctic cretaceous palaeo hydrology stable oxygen isotope analysis of siderite and dinosaur tooth enamel phosphate from the campanian maastrichtian prince creek formation alaska usa are analysed to determine the palaeohydrology of the ancient colville basin north of the ancestral brooks range do of freshwater siderites relative to v pdb ranges between 214 86 and 216 21 dinosaur tooth enamel do from three different sites kikak tegoseak pediomys point liscomb range between 3 9 and 10 2 0 dometeoric water are calculated from dosiderite that formed at seasonal temperatures ranging from 22 to 14 5 8c with a mean annual temperature of 6 3 8c at 6 3 8c the dow calculated from siderite ranged between 222 23 and 220 89 v smow ingested water compositions are estimated from dinosaur teeth assuming body temperatures of 37 8c and local relative humidity of 77 5 resulting in values ranging from 228 7 to 220 4 v smow suggesting consumption of meteoric water and orographically depleted runoff from the brooks range the ranges in calculated dometeoric water are compatible between the two proxies and are mutually corroborating evidence of extremely o depleted precipitation at high latitudes during the late cretaceous relative to those generated using general circulation models this depletion is proposed to result from increased rainout effects from an intensified hydrological cycle which probably played a role in sustaining polar warmth supplementary material parameters used for generation of equations compared to kohn 1996 can be found at http www geolsoc org uk sup18642 stable isotopic proxies are invaluable tools for understanding past and current climates pedogenic carbonates siderite and calcite are commonly used to determine the isotopic composition of meteoric water lohmann 1988 hays grossman 1991 ludvigson et al 1998 ufnar et al 2004a suarez et al 2011 when analysed over a range of latitudes the resulting isotopic gradients can be used to determine global isotopic groundwater gradients this gradient is related to the isotopic composition of the precipitation which is itself related to temperature gradients humidity and in some instances orographic effects isotopic studies of the cretaceous are of particular importance because future climatic conditions kiehl 2011 are predicted to approach those pco2 temperature seen in the various greenhouse worlds of the cretaceous several studies on the cretaceous climate have revealed shallow equatorial topole air and ocean temperature gradients wolfe upchurch 1987 amiot et al 2004 jenkyns et al 2004 puceat et al 2007 while others have indicated equator to pole precipitation do gradients that are steeper than the modern climate system ludvigson et al 1998 ufnar et al 2002 suarez et al 2011 this steep gradient has been explained as resulting from increased rainout thereby increasing latent heat transport from the equator to the poles during greenhouse conditions ufnar et al 2004b these conclusions are based on empirical from bojar a v melinte dobrinescu m c smit j eds isotopic studies in cretaceous research geological society london special publications 382 http dx doi org 10 1144 sp382 3 the geological society of london 2013 publishing disclaimer www geolsoc org uk pub ethics by guest on june 17 2013 http sp lyellcollection org downloaded from

genesis of placic horizons in andisols from terceira island azores portugal abstract the placic horizon is a common feature of andisols developed under perudic conditions in terceira island azores this paper reports morphological physical and chemical characteristics of three pedons placic horizons developed above weakly cemented bs bc horizons are approximately 10 mm thick with abrupt and wavy boundaries in two of the pedons carvao and lavacal and up to 20 mm thick in the third s barbara which shows a gradual lower boundary active al and fe contents are small in the upper horizons of all three pedons and are mostly complexed with humus but the placic horizons are fe rich in thin sections a typical component is egg yellow or red limpid isotropic material sometimes with a globular aspect this is apparently superposed on the original micromass whose amorphous character and limpidity without any identifiable cracked dark coatings suggests that the iron is in the form of an hydr oxide rather than complexed with organic matter ferrihydrite is indicated by chemical analysis formation of the three placic horizons is attributed mainly to reduction in organic rich horizons under wet conditions followed by reoxidation in the drier soil horizon below

rayleigh waves guided by sea trench topography a later phase of large amplitude is observed at a station in hokkaido from several events of the december 1991 off urup earthquake swarm in the kurile islands region the phase is characterized by a narrow frequency band with a dominant period of about 15 s and retrograde particle motion in a vertical plane with a strike very different from the great circle direction between the station and the epicenter the phase is observed from only the earthquakes that are located at shallow depths beneath the inner wall of the kurile trench where sea depth is greater than 4 km these characteristics indicate that the phase is a packet of rayleigh waves that arrive at the station from an azimuth considerably different from the great circle direction rayleigh waves with periods around 15 20 s are well excited by the shallow earthquakes beneath the inner wall of the trench this is supported by the dominance of a spectral peak at 15 20 s in the spectra of the direct rayleigh waves and the later phase rayleigh waves that propagate in an oceanic region are strongly influenced by the thickness of the water layer at periods shorter than about 25 s the group velocity decreases by 80 at 15 s with the increase of the sea depth from 4 km to 6 km the sea trench topography therefore forms a strong low velocity zone the observed later phase can be interpreted as a rayleigh wave packet guided by this velocity complexity

fossil andisols identified with mass balance geochemistry oligocene john day formation oregon u s a mass balance geochemistry of thick sequences of fossil soils oligocene john day formation central oregon show trends similar to those produced by modern andisol soil forming processes these andic trends include phosphorus accumulation potassium retention and alumina and iron depletion identification of these trends benefited from the geochemical comparison of numerous fossil soil horizons from two paleosol sequences one andic and one non andic the comparison of two paleosol sequences is justified because both sequences developed from the same type of parent material in nearly identical tectonic depositional settings the two sequences are 1 the early oligocene big basin member dominated by clayey alfisol like paleosols and 2 the mid oligocene turtle cove member dominated by ash rich andisol like paleosols with calcareous horizons the change in paleosol type occurred circa 30 ma throughout the john day basin and is most likely due to global cooling which changed climatic conditions in central oregon from humid to subhumid drier climate is interpreted to have caused a decrease in weathering intensity so that amorphous weathering products of volcanic glass accumulated in soils to form andisols prior to this circa 30 ma transition weathering produced crystalline clays from volcaniclastic detritus to form alfisols rather than amorphous weathering products

lithologic and tectonic controls on bedrock channel form at the northwest himalayan front 1 recognition that channel form reflects a river s ability to erode rock and transport material has spawned stream power models that estimate incision patterns by approximating energy dissipation within a channel these models frequently assume that channel width scales as a power law with drainage area partly because drainage area is easily extracted from digital elevation models dems however this assumption is often confounded by local variations in rock strength and rock uplift rate that can cause channel constriction downstream here we investigate the morphological response to spatial changes in rock strength and rock uplift rate of 10 bedrock channels traversing the mohand range along the northwest himalayan front we present a new method to continuously measure and compare channel width slope and other hydraulic parameters that integrate satellite imagery and dem analysis our method corrects for an 13 overestimation of average channel gradient from a 90 m resolution dem that arises from short circuits of fine scale meanders we find that channels 1 narrow 1 km upstream from knickpoints formed by an increase in rock strength 2 adjust laterally more than vertically in response to downstream decreases rock erodibility and uplift rate and 3 meander where shear stresses are high and channel widths are low we attribute these results to a high ratio of sediment supply to transport capacity which enhances lateral erosion relative to vertical incision our results suggest that substrate strength and sediment supply substantially influence channel form and that channel width should be explicitly measured when interpreting tectonic signals from bedrock channel morphology

development of long period ground motions from the nankai trough japan earthquakes observations and computer simulation of the 1944 tonankai mw 8 1 and the 2004 se off kii peninsula mw 7 4 earthquakes strong ground motions recorded in central tokyo during the 1944 tonankai mw8 1 earthquake occurring in the nankai trough demonstrate significant developments of very large 10 cm and prolonged 10 min shaking of long period t 10 12 s ground motions in the basin of tokyo located over 400 km from the epicenter in order to understand the process by which such long period ground motions developed in central tokyo and to mitigate possible future disasters arising from large earthquakes in the nankai trough we analyzed waveform data from a dense nation wide strong motion network k net and kik net deployed across japan for the recent se off kii peninsula mw 7 4 earthquake of 5 september 2004 that occurred in the nankai trough the observational data and a corresponding computer simulation for the earthquake clearly demonstrate that such long period ground motion is primarily developed as the wave propagating along the nankai trough due to the amplification and directional guidance of long period surface waves within a thick sedimentary layer overlaid upon the shallowly descending philippine sea plate below the japanese island then the significant resonance of the seismic waves within the thick cover of sedimentary rocks of the kanto basin developed large and prolonged long period motions in the center of tokyo the simulation results and observed seismograms are in good agreement in terms of the main features of the long period ground motions accordingly we consider that the simulation model is capable of predicting the long period ground motions that are expected to occur during future nankai trough m 8 earthquakes

polygenetic history of paleosols in middle upper pennsylvanian cyclothems of the illinois basin u s a part ii integrating geomorphology climate and glacioeustasy abstract distinct lateral and stratigraphic trends in paleosol morphology and clay mineralogy in conjunction with the stable isotope composition of sub millimeter scale spherulitic siderite sphaerosiderite and flint clay kaolinite in middle upper pennsylvanian cyclic coal bearing strata of the illinois basin ib presented herein provide proxy records of middle late pennsylvanian equatorial terrestrial environments collectively these data provide a better understanding of the polygenetic history of ancient soils preserved in cyclic strata and indicate that low latitude pennsylvanian ib soil profiles were influenced by a combination of autogenic and allogenic controls lateral variations in paleosol morphology from the interior of the basin to the northern margin indicate that soil development was dominantly influenced by autogenic controls such as differences in local paleohydrology i e groundwater fluctuations and subsidence rates across the basin conversely allogenic controls i e glacioeustasy and climate are interpreted to be principally responsible for the preservation of features in gleyed protosols gleyed vertisols and gleyed calcic vertisols that occur in the interior of the ib these paleosols are characterized by a polygenetic development history that includes 1 an initial period of soil formation in well drained environments with seasonal wetting and drying of the profile followed by 2 a subsequent period of waterlogging and development of reducing conditions paleosols that lack evidence for extensive periods of waterlogging are restricted with the exception of two examples to the northern margin of the basin and they become abundant in the stratigraphic record near the middle upper pennsylvanian boundary uppermost desmoinesian the stratigraphic distribution of these paleosols in conjunction with a decrease in the relative abundance of kaolinite in the 2 m size fraction of ib paleosols near the desmoinesian missourian d m boundary is interpreted to reflect a shift in the overall low latitude regional climate to drier conditions the stable isotope compositions of sphaerosiderite and flint clay kaolinite in middle upper pennsylvanian strata of the ib provide an additional proxy record of past equatorial terrestrial environments and are used to constrain the magnitude of paleoclimate change across the d m moscovian kasimovian boundary sphaerosiderite 18ov pdb and 13cv pdb values range from 3 6 to 0 5 and 12 8 to 3 2 respectively in particular sphaerosiderite 18o values from the b horizons of paleosols display an approximate 1 5 shift across the d m boundary this stratigraphically short isotopic shift occurs across the d m boundary on the order of one cyclothem 400 kyr and is followed by a subsequent shift on the order of one cyclothem back to more positive siderite 18o values the average 18ov smow and dv smow values of kaolinite isolated from the 0 2 m size fraction of a latest desmoinesian flint clay breccia are 21 0 and 46 5 these values correspond to a latest desmoinesian crystallization temperature of 27 2 c and a meteoric water 18ov smow value of 3 1 combination of sphaerosiderite 18o values and co occurring flint clay kaolinite d and 18o values suggest a possible warming of up to 6 c across the d m boundary corresponding to an approximate temperature change of siderite crystallization from 27 to 33 c this temperature increase in conjunction with distinct stratigraphic trends in the clay mineralogy and morphology of ib paleosols is consistent with previous paleoclimate interpretations and it suggests that low latitude pennsylvanian paleoclimate became drier and warmer across the d m boundary

constituents of vertical component coda waves at long periods aki 1969 first modeled coda waves of a local earthquake as a superposition of scattered surface waves this paper attempts to clarify the constituents of surface wave coda at long periods at very long lapse times for a large earthquake of magnitude 7 or larger vertical component oscillation in periods from 90 to 180 s persists for more than 20 hours from the earthquake origin time although the early portion of the coda envelope is successfully modeled by assuming incoherent scattered rayleigh waves by heterogeneities distributed all over the earth the later potion of the observed coda envelope roughly later than 35 000 s has systematically larger amplitude than theoretical prediction to clarify the cause of this discrepancy we studied the constituents of vertical component seismograms of three large earthquakes recorded by the f net in japan using the f k power spectral analysis we found that the direct and scattered fundamental mode rayleigh waves of velocity about 3 7 km s are dominant in the earlier part of each envelope it justifies the use of a scattering model of the fundamental rayleigh waves for synthesizing the envelope at lapse times later than 20 000 s 35 000 s higher modes with phase velocities around 20 km s become dominant the transition time to the dominance of higher modes is found to become earlier for a deeper focus earthquake the small coda attenuation factor from 1 90 0 23 10 3 to 2 38 0 32 10 3 estimated from later coda envelopes recorded at iris stations distributed worldwide also agrees with the attenuation factor of spheroidal modes according to prem we may interpret that higher mode waves are uniformly distributed at large lapse time due to large velocity dispersion and or scattering and they dominate over the fundamental mode waves because of smaller attenuation in the lower mantle the coda attenuation measurement proposed by aki is found to be useful even for long periods and at very large lapse times

strong sh to love wave scattering off the southern california continental borderland seismic scattering is commonly observed and results from wave propagation in heterogeneous medium yet deterministic characterization of scatterers associated with lateral heterogeneities remains challenging in this study we analyze broadband waveforms recorded by the southern california seismic network and observe strongly scattered love waves following the arrival of teleseismic sh wave these scattered love waves travel approximately in the same azimuthal direction as the incident sh wave at a dominant period of 10 s but at an apparent velocity of 3 6 km s as compared to the 11 km s for the sh wave back projection suggests that this strong scattering is associated with pronounced bathymetric relief in the southern california continental borderland in particular the patton escarpment finite difference simulations using a simplified 2 d bathymetric and crustal model are able to predict the arrival times and amplitudes of major scatterers the modeling suggests a relatively low shear wave velocity in the continental borderland

the late cretaceous environment of the arctic a quantitative reassessment based on plant fossils abstract late cretaceous megafossil floras from the palaeo arctic of northeastern russia and northern alaska are reviewed in respect of their age composition structure and floral dynamics palaeofloral correlations and comparisons are made between the two regions nine angiosperm rich predominantly cenomanian to coniacian floras from the palaeo arctic are re evaluated using climate leaf analysis multivariate program clamp calibrated using a global gridded 0 5 0 5 climate data set derived from that used in climate modelling additional floras from lower palaeolatitudes were used to derive latitudinal temperature gradients seven from n america five from around 30 n palaeolatitude in europe and one from kazakhstan the arctic climatic determinations similar to previous estimates support the existence of a northern pacific ocean cold gyre and a warm arctic ocean at palaeolatitudes greater than 80 n floras are insufficiently diverse in woody dicot taxa to use clamp but using clamp derived latitudinal temperature gradients arctic ocean coastal environments at 70 ma and 82 n and which supported a diverse dinosaur magafauna are predicted to have experienced a mean annual temperature of 6 3 2 2 c a warm month mean of 14 5 3 1 c and a cold month mean no colder than 2 0 3 9 c all uncertainties are 2 the new estimates are in good agreement with a wide range of non palaeobotanical climate proxies and render as an outlier warmer temperature estimates for the arctic ocean derived from the tex 86 proxy modelling however shows that land to ocean temperature gradients could have been steep the clamp estimates also suggest high values for humidity and precipitation consistent with sedimentological indicators and coupled with warm temperatures support the existence of a persistent polar cloud cap that helped maintain high terrestrial air temperatures throughout prolonged periods up to 5 months of winter darkness

downstream changes in the channel geometry of a large gravel bed river 1 field data obtained on a nearly contiguous segment of the colorado river in western colorado and eastern utah are used to examine the mechanisms driving downstream changes in channel geometry measurements characterizing the bank full hydraulic geometry bed material grain size and average channel gradient were made at closely spaced intervals in 10 alluvial and quasi alluvial reaches covering 260 km of the river these data indicate that changes in surface and subsurface grain sizes are small in relation to the change in channel slope over the full length of the study area the median grain size of the surface sediment decreases by a factor of a little more than 2 whereas the average channel slope decreases by a factor of about 5 the decreases in slope and median grain size are offset by a large increase in bank full depth relative to width such that the bank full shields stress b is constant downstream for the reach as a whole b averages 0 049 which is roughly 50 higher than the threshold for bed load transport

paleofloristic and paleoenvironmental information from a late cretaceous maastrichtian flora of the lower cantwell formation near sable mountain denali national park alaska abstract the lower cantwell formation in denali national park alaska is a late cretaceous high latitude fluvial succession that contains dinosaur and bird footprints diverse invertebrate traces and plant fossils new fossil discoveries and stratigraphic descriptions in the sable mountain area allow for refined paleoenvironmental reconstructions and age interpretations the formation consists of well indurated conglomerate sandstone siltstone and shale interpreted as gravelly and sandy channel levee crevasse splay sheetflood lacustrine and floodplain sediments with interspersed debris flows the overall depositional environment is interpreted as a braided river floodplain that interfingered with distal alluvial fan sedimentation plant fossils include leaves branches cones and rare seeds of taxodiaceous and other conifer taxa fern fronds rhizomes and stem segments of equisetites linear and broad lanceolate monocot leaf fragments cf kenella and impressions of diverse angiosperm broad leaf morphotypes likely belonging to menispermoid platanoid and several late cretaceous hamamelid groups a sparse palynoflora extracted from the finer grained facies yielded the pollen taxa taxodiaceaepollenites aquilapollenites and alnipollenites monosulcate cycadophyte or ginkgophyte pollen grains bisaccate and monosaccate conifer pollen grains and a variety of trilete fern and psilate horsetail spores the middle to late maastrichtian pollen taxon aquilapollenites conatus provides a maximum age for the sable mountain deposits floral assemblages occur within distinct lithofacies deposited in a variety of depositional settings in the ancient floodplain angiosperm leaf fossils are dominant in channel and levee facies and were part of a mixed forest assemblage growing in floodplain and lake margin environments a variety of different types of conifers indicated by saccate pollen types and rare long thin leaf fragments probably inhabited distal floodplain realms and uplands frequent and abrupt changes in lithology and floral assemblages imply transitory habitats in a rapidly aggrading depositional setting a climate leaf analysis multivariate program clamp applied to a composite leaf collection yielded a mean annual temperature of 7 42 1 2 c a warmest monthly mean of 17 1 1 6 c and a coldest monthly mean of 2 3 1 9 c growing season precipitation is estimated at 229 4 334 5 mm over 4 8 0 7 months results are suggestive of a cool temperate and highly seasonal paleoclimate with short warm dry summers and long comparatively mild and probably wet winters temperature calculations are consistent with previous estimates from alaska s north slope and northeastern russia suggesting a low polar temperature gradient and a slight cooling trend during the middle to early late maastrichtian precipitation estimates for the growing season are low compared to overall wet climate predictions for the maastrichtian like other late cretaceous arctic floras the cantwell flora is classified herein as a polar broad leaved deciduous forest flora

scattering of teleseismic p waves by the japan trench a significant effect of reverberation in the seawater column abstract we detected a scattered wave train in data from the high sensitivity seismograph network in japan hi net following the arrival of the near vertically incident p wave generated by the 2009 earthquake mw 7 8 off the south island of new zealand the scattered wave train represented predominantly vertical ground motion at a period of 20 to 50 s and with an apparent velocity of 3 5 km s it propagated cylindrically westward through the kanto area of central japan array analysis showed that the scattered wave train developed beneath the pacific ocean near the boso triple junction southeast of the kanto area a 3d finite difference simulation of seismic wave propagation using a high resolution model incorporating subsurface structure topography and bathymetry revealed that the strong scattered waves that were generated along the japan trench and propagated normal to the trench axis represented multiple reverberations of seismic waves between the seafloor and the pacific plate boundary in addition strong reverberation of acoustic waves in the seawater column above the boso triple junction causes elongated scattered waves which reasonably explains our observations

origin of clay minerals in alluvial paleosols prince creek formation north slope alaska u s a influence of volcanic ash on pedogenesis in the late cretaceous arctic abstract paleosols formed from weathering of alluvial mudstones in the late cretaceous maastrichtian prince creek formation north slope alaska are dominated by detrital smectite discrete illite kaolinite chlorite quartz and pedogenic illite smectite i s mixed layer clays in the fine clay fraction 80 low bulk density phosphorus accumulation fe and al mass balance trends and the presence of fe al humus complexes in one paleosol profile is interpreted as evidence of andic soil properties and these paleosols are interpreted therefore as andept like alluvial soils these results demonstrate that clay mineralogical studies in conjunction with geochemical data of paleosols can be used to identify paleo andic soil properties which have not been widely recognized in the ancient rock record alternating wetting and drying conditions required to form pedogenic i s in these alluvial paleosols resulted from a highly seasonal moisture regime in the late cretaceous arctic

a multi disciplinary perspective on habitat preferences among dinosaurs in a cretaceous arctic greenhouse world north slope alaska prince creek formation lower maastrichtian abstract the prince creek formation of northern alaska is the most abundant source of polar dinosaur remains in the world and now corroborating data from this well studied rock unit allow for making inferences about the paleoecological preferences for these extinct polar animals the rock unit records high latitude alluvial sedimentation and soil formation on a low gradient muddy coastal plain compound and cumulative andic entisols and inceptisols formed on levees point bars crevasse splays and along the margins of floodplain lakes ponds and swamps abundant organic matter carbonaceous root traces fe oxide depletion coatings and zoned peds indicate periodic waterlogging anoxia and gleying consistent with a high water table in contrast fe oxide mottles ferruginous and manganiferous segregations bioturbation and less common illuvial clay coatings indicate recurring oxidation and periodic drying out of some soils an integrated reconstruction of pedogenic processes and biota suggests that this ancient arctic coastal plain was influenced by seasonally fluctuating water table levels and floods and in distal areas marine waters four of the five bonebeds in this study are from more distal areas represented by lower delta plain facies while the fifth bonebed is from a more proximal part of the basin represented by a somewhat better drained coastal plain facies bonebeds in the distal areas are dominated by edmontosaurus sp while the more proximal bonebed is dominated by the remains of the ceratopsian pachyrhinosaurus perotorum the distribution of these bonebeds sedimentological facies paleosols and biota suggests that pachyrhinosaurus may have preferred more upland environments while edmontosaurus preferred lowland deltaic environments this distribution may be the result of physiological adaptation to the pronounced seasonality provided by polar terrestrial ecosystems in contrast to a preferred habitat distribution of these large herbivores the large predatory dinosaur nanuqsaurus hoglundi seems to have had a more ubiquitous distribution across the landscape

characterizing the transient geomorphic response to base level fall in the northeastern tibetan plateau analysis of hillslope gradient landscape relief and channel steepness in the daxia river basin provides evidence of a transient geomorphic response to base level fall on the northeastern tibetan plateau low gradient channels and gentle hillslopes of the upper watershed are separated from a steeper high relief landscape by a series of convex knickzones along channel longitudinal profiles downstream projection of the relict portions of the profiles implies 800 850 m of incision consistent with geologic and geomorphic records of post 1 7 ma incision in the lower watershed we combine optically stimulated luminescence dating of fluvial terrace deposits to constrain incision rates downstream of knickpoints with catchment averaged 10be concentrations in modern sediment to estimate erosion rates in tributary basins both above and below knickpoints both sources of data imply landscape lowering rates of 300 m ma 1 below the knickpoint and 50 100 m ma 1 above field measurements of channel width n 48 and calculations of bankfull discharge n 9 allow determination of scaling relations among channel hydraulic geometry discharge and contributing area that we employ to estimate the patterns of basal shear stress unit stream power and bed load transport rate throughout the channel network our results imply a clear downstream increase of incision potential this result would appear to be consistent with a detachment limited response to imposed base level fall in which steepening of channels drives an increase in erosion rates in contrast however we do not observe apparent narrowing of channels across the transition from slowly eroding to rapidly eroding portions of the watershed rather the present day channel morphology as well as its scaling of hydraulic geometry imply that the river is primarily adjusted to transport its sediment load and suggest that channel morphology may not always reflect the presence of knickpoints and differences in landscape relief

paleosol classification problems and solutions abstract paleosols are soils that formed on landscapes of the geologic past three kinds exist buried exhumed and relict to help reconstruct paleoenvironments and for ease of comparison we suggest a property based classification system linked to genetic processes we use enduring properties because alteration of paleosols following burial is common morphological properties such as horizonation soil fabric root and worm casts and redoximorphic features are resistant to alteration and thus are valuable as criteria field observable and micromorphological properties degree of weathering and proportion of resistant minerals are also useful as criteria for paleosol orders total chemical analysis provides a proxy measure for base saturation and clay mineralogy we use proxy criteria to help classify paleosols that have changed markedly or have been lithified during or after burial to an earlier version of the system we add two new orders and include buried relict lithified and exhumed units at the suborder level our system clearly separates paleosol taxon names from those of all ground soils we use the prescript paleo at the order level and kryptic to designate the buried enduric to designate the relict lithic to designate the lithified and emergent to designate the exhumed paleosol suborders we use prescript modifiers to describe the physical characteristics of the paleosols and postscripts for parent material origin and the extensiveness of the paleosol landscape we present data and classify a number of paleosols as examples of the system

fdm simulation of seismic wave propagation for an aftershock of the 2009 suruga bay earthquake effects of ocean bottom topography and seawater layer abstract feasibility studies on simulating seismic wave propagation in media for a suboceanic earthquake including both land and ocean bottom topographies and a seawater layer are scarce some of the conventional staggered grid finite difference method fdm simulations use a simplified structure model without a seawater layer and with a flat ocean bottom topography in this study we apply our heterogeneity oceanic layer and topography scheme hot fdm and a 3d structure model including land and ocean bottom topographies a seawater layer and a fluid solid boundary condition to an aftershock m w 5 8 of the 2009 suruga bay earthquake we attempt to reproduce observations at seismic stations near the coast and then simulate waveforms in the ocean bottom stations our results show that a large difference between the cases with and without topographies can be seen in the coda part after the s wave in the simulated waveforms in terms of amplitudes and elongations the synthetic waveforms in the model with topographies are in agreement with the observed waveforms our results also show that a significant difference in the amplification of the coda part between the cases with and without the seawater layer can be found at the ocean bottom stations this coda part is the s and rayleigh wave propagation associated with the ocean and the underlying sediment layers our results show that a realistic model with topographies and a seawater layer is needed in fdm simulations in order to precisely reproduce observed waveforms or predict seismic motion for a suboceanic earthquake

waveform modeling of the slab beneath japan 1 the tomographic p wave model for the japan subduction zone derived by zhao et al 1994 has two very striking features a slab about 90 km thick with p wave velocities 3 6 higher than the surrounding mantle and a mantle wedge with 6 low velocity anomalies we study three component seismograms from more than 600 hi net stations produced by two earthquakes which occurred in the downgoing pacific plate at depths greater than 400 km we simulate body wave propagation in the three dimensional 3 d p wave model using 2 d finite difference fdm and 3 d spectral element sem methods as measured by cross correlation between synthetics and data the p wave model typically explains about half of the traveltime anomaly and some of the waveform complexity but fails to predict the extended sh wave train in this study we take advantage of the densely distributed hi net stations and use 2 d fdm modeling to simulate the p sv and sh waveforms our 2 d model suggests that a thin elongated low velocity zone exists atop the slab extending down to a depth of 300 km with an s wave velocity reduction of 14 if a thickness of 20 km is assumed further 3 d sem simulations confirm that this model explains a strong secondary arrival which cannot easily be imaged with standard tomographic techniques the low velocity layer could explain the relatively weak coupling associated with most subduction zones at shallow depths 50 km generally involving abundant volcanic activity and silent earthquakes and it may also help to further our understanding of the water related phase transition of ultramafic rocks and the nature of seismicity at intermediate depths 70 300 km

constitutive mass balance relations between chemical composition volume density porosity and strain in metasomatic hydrochemical systems results on weathering and pedogenesis relations characterizing the chemical physical and mechanical changes resulting from metasomatic hydrochemical processes are developed using mass balance models which formally link chemical composition to bulk density mineral density volumetric properties porosity and amount of deformation strain rigorous analysis of aqueous solute transport effects is then made possible in a variety of porous media flow environments including chemical weathering pedogenesis soil formation diagenesis ore deposition and enrichment and metamorphism application of these linear constitutive relations to chemical weathering profiles shows that immobile and locally mobile chemical elements with masses conserved on the scale of soil profiles can be accurately identified from analysis of appropriate data arrays and then used as natural geochemical tracers to infer the nature and extent of hydrochemical weathering processes and volume changes during pedogenesis assumptions commonly made in the past about the supposed immobility of certain elements e g ti and zr become unnecessary quantitative differentiation between the effects of residual and supergene fractionation is then easily made these methods are applied to ni rich laterites developed by weathering of ultramafic rocks showing that during ordinary residual enrichment ni is concentrated by as much as 4 protolith peridotite concentrations this occurs simply by silicate mineral dissolution and removal of chemical elements other than ni e g mg with a corresponding reduction in saprolite density and increase in bulk porosity without significant deformation in contrast laterites with mineable concentrations of ni which are similarly undeformed such as the nickel mountain mine in riddle oregon have experienced in addition to residual enrichment strong supergene enrichment by fractionation of ore elements between a leached zone from which ni is extracted and a complementary enriched zone positioned farther along the direction of ground water flow soil forming processes in podzol chronosequences developed on sandy beach terraces of the mendocino coast of california involved soil column collapse of 60 percent by dissolution of silicate minerals in the albic horizon of al and fe leaching and 70 percent dilation expansion in the overlying organic rich layer by root growth the amount of erosion based upon paleosurface reconstructions using the excess mass of fe al pb ga and cu in the zone of supergene enrichment spodic horizon below the ground water table indicates that subsurface erosion by dissolutional collapse is three times that of surficial erosion finally using published chemical data for ti zr and cr on major bauxite deposits in australia where erosion rates are thought to be low we infer that there may have been major amounts of dissolutional collapse to explain the upwards increase of detrital zircon and rutile in weathering profiles

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

clay mineralogy of phyllic and intermediate argillic alteration at bingham utah the earliest alteration mineral zones in the porphyry cu mo au ore deposit at bingham utah include the outermost propylitic and inner potassic alteration of igneous rocks innermost phyllic and intermediate argillic alteration is superimposed on propylitic and potassic alteration petrographic x ray diffraction and electron microprobe analyses are used to characterize the clay mineralogy of phyllic and intermediate argillic alteration phyllic alteration affects monzonite near the contact with the quartz monzonite porphyry in the southwest and northeast portions of the deposit and consists primarily of veins and vein selvages of illite interstratified with an average of 7 percent smectite r 3 ordering the veins and selvages also contain small amounts of smectite and kaolinite the illite smectite interstratification is a mixture of 1m and 2m polytypes structural formulas for the illite show less k and al and more si than muscovite octahedral mg and both a tetrahhedral and an octahedral layer charge the kubler crystallinity index and smectite content increase systematically as particle size decreases consistent with an increase in smectite in the interstratification in the smaller size fractions intermediate argillic alteration consists of smectite illite and kaolinite that occur primarily as a replacement of plagioclase phenocrysts a few veins of intermediate argillic minerals are present in the quartz monzonite porphyry illite is interstratified with an average of 6 percent smectite r 3 ordering but a few samples contain a regular interstratification of illite with 40 to 50 percent smectite r1 ordering the smectite replacing plagioclase is montmorillonite and smectite that occurs in one vein is beidellite statistical trends in intermediate argillic alteration mineralogy within the quartz monzonite porphyry show that illite and kaolinite abundances increase generally upward and toward the northeast smectite abundance increases generally downward and toward the southwest in a cross section near the center of the deposit abundances of kaolinite and illite decrease as abundance of smectite increases with increasing depth the occurrence of interstratified illite smectite averaging 6 to 7 percent smectite together with discreet smectite suggest formation near 200 c a temperature difference between phyllic and intermediate argillic alteration could not be resolved from the mineralogy temperature estimates from fluid inclusions for phyllic alteration at other porphyry copper deposits generally range from 200 to 350 c the activity ratio of na k for the fluid calculated from na k in illite averages 5 0 for a phyllic vein that crosscuts propylitic alteration 1 4 for a phyllic vein that crosscuts potassic alteration and 2 8 for intermediate argillic alteration superimposed on potassic alteration log f h 2 o f hf of the hydrothermal fluid computed from the fluorine content of illite averages 6 1 for a phyllic vein that crosscuts propylitic alteration 5 8 for a phyllic vein that crosscuts potassic alteration and 5 7 for intermediate argillic alteration log f h 2 o f hf of fluids forming late stage biotite is about 5 0 intermediate argillic alteration could not be correlated with sulfides in the quartz monzonite porphyry an increase in illite upward and toward the northeast may correlate with massive sulfides in sediments recently discovered in that region

interference of long period seismic wavefield observed by the dense hi net array in japan 1 in order to recover small signals of long period ground motions recorded by a short period seismometer we designed a time domain recursive filter that simulates seismic waves recorded with broadband seismometers we applied the time domain filter to seismograms recorded by the dense hi net array which consists of 800 stations at intervals of approximately 20 km the effectiveness of the time domain filter is demonstrated through the comparison of broadband waveforms obtained by the filter and sts 2 true broadband seismograms from the f net at the same site good agreement is observed between filtered and true broadband waveforms with high correlation coefficients for periods of up to 100 s for waveforms from the 2007 sumatra earthquake m7 9 which occurred approximately 5000 5800 km away from japan the applicability of the time domain filter to the recovery of long period signals from the record of a short period seismometer depends on the signal to noise ratio as a result a limited bandwidth of broadband signal is recovered for smaller earthquake from the spatiotemporal variation of the long period t 20 100 s wavefield obtained by the time domain filter we newly found an anomalous phase pattern of splitting of polarity along the wavefront particularly for the relatively short period band of from 20 50 s array analysis of the dense broadband waveforms revealed multipathing of the rayleigh waves which propagated toward central japan from two directions with slightly different slowness vectors the interference of two rayleigh waves caused such splitting of wavefield

effects of realistic surface topography on seismic ground motion in the yangminshan region of taiwan based upon the spectral element method and lidar dtm we combine light detection and ranging lidar digital terrain model dtm data and an improved mesh implementation to investigate the effects of high resolution surface topography on seismic ground motion based upon the spectral element method in general topography increases the amplitude of shaking at mountain tops and ridges whereas valleys usually have reduced ground motion as has been observed in both records from past earthquakes and numerical simulations however the effects of realistic topography on ground motion have not often been clearly characterized in numerical simulations especially the seismic response of the true ground surface here we use lidar dtm data which provide two meter reso lution at the free surface and a spectral element method to simulate three dimensional 3d seismic wave propagation in the yangminshan region in taiwan incorporating the effects of realistic topography a smoothed topographic map is employed beneath the model surface in order to decrease mesh distortions due to steep ground surfaces numerical simulations show that seismic shaking in mountainous areas is strongly affected by topography and source frequency content the amplification of ground motion mainly occurs at the tops of hills and ridges whilst the valleys and flat topped hills experience lower levels of ground shaking interaction between small scale to pographic features and high frequency surface waves can produce unusually strong shaking we demonstrate that topographic variations can change peak ground accel eration pga values by 50 in mountainous areas and the relative change in pga between a valley and a ridge can be as high as a factor of 2 compared to a flat surface response this suggests that high resolution realistic topographic features should be taken into account in seismic hazard analysis especially for densely populated moun tainous areas

characteristics of cryogenic soils along a latitudinal transect in arctic alaska the morphological chemical and physical properties of arctic tundra soils were examined along a 200 km latitudinal gradient in northern alaska which includes two major physiographic provinces the arctic coastal plain and the arctic foothills annual air temperature and precipitation increase along the gradient from north to south soils on the arctic coastal plain support wet nonacidic tundra vegetation and have high carbonate contents soil on the arctic foothills support moist nonacidic tundra in the northern part and moist acidic tundra in the southern part most arctic tundra soils are characterized by medium texture poor drainage and high organic matter content from north to south along the transect the base saturation of the active layer decreases and exchangeable aluminum increases from north to south most soils have strongly developed cryogenic features including warped and broken horizons ice lenses thin platy structure and organic matter frost churned into the ice rich upper permafrost horizons

paleoclimate reconstruction of the prince creek formation arctic alaska during maastrichtian global warming abstract the upper cretaceous maastrichtian prince creek formation of arctic alaska 82 85 n paleolatitude preserves successions of alluvial paleosols that are used to estimate mean annual precipitation map mean annual temperature mat and meteoric water oxygen isotope composition for the prince creek formation the highest map estimates range between 1000 and 3900 mm yr and the lowest range between 350 and 1200 mm yr the precipitation variability derived from stable carbon isotope analysis occurs on a time scale of 104 years map values agree with previous interpretations from fossil pollen pedological features soil types vegetation composition sedimentological indicators and clamp estimates that suggest high precipitation amounts and high humidity despite the considerable uncertainty with mat proxies our values are consistent with warm month mean temperatures obtained previously from paleobotanical data the 18o of smectite from bentonite beds clusters around 5 0 vsmow the 18o of meteoric water calculated from bentonitic smectite is 23 vsmow assuming a mean annual temperature of 6 3 c which is slightly more 18o depleted than meteoric water calculated from pedogenic siderite in stratigraphically younger beds closer to the brooks range chronostratigraphic correlation with the lower cantwell formation denali national park alaska 64 n paleolatitude suggests higher precipitation rates and highly 18o depleted precipitation in the late cretaceous paleo arctic compared to central alaska these data are consistent with previous studies that suggest a warmer and moister greenhouse earth and an intensified hydrological cycle that enhanced latent heat transport resulting in increased rainout effects

classification of paleosols despite increased interest in paleosols during the past decade no satisfactory classification is in current use presented here is a largely descriptive classification system that utilizes those pedogenic features that have the highest preservation potential in the rock record emphasized in the classification are morphological and mineralogical features that are easily recognizable in the field and through the petrographic microscope the classification is based on evaluation of the relative prominence in a paleosol of six pedogenic features or processes organic matter content horizonation redox conditions in situ mineral alteration illuviation of insoluble minerals compounds and accumulation of soluble minerals the most prominent of these six features processes provides the key to classifying a paleosol into one of nine orders four of the order names are borrowed from soil taxonomy histosol spodosol oxisol vertisol whereas the other five order names are presented here for the first time calcisol gypsisol gleysol argillisol protosol the orders may be preceded by one or more subordinate modifiers that describe other important features of the paleosol the classification is relatively easy to apply to the rock record and should enhance communication and aid in the standardization of terminology

uplift histories of africa and australia from linear inverse modeling of drainage inventories this is the final version it first appeared at http onlinelibrary wiley com wol1 doi 10 1002 2014jf003297 abstract

geomorphic limits to climate induced increases in topographic relief recognition of the potential for strong dynamic coupling between atmospheric and tectonic processes has sparked intense cross disciplinary investigation and debate on the question of whether tectonics have driven long term climate change or vice versa it has been proposed that climate change might have driven the uplift of mountain summits through an isostatic response to valley incision because isostasy acts to compensate mean elevations the debate hinges on the question of whether climate change can significantly increase topographic relief or more precisely increase the volume of missing mass between summits and ridges here we show that in tectonically active mountain ranges geomorphic constraints allow only a relatively small increase in topographic relief in response to climate change thus although climate change may cause significant increases in denudation rates potentially establishing an important feedback between surficial and crustal processes neither fluvial nor glacial erosion is likely to induce significant isostatic peak uplift

rayleigh wave multipathing along the west coast of north america we have created a movie of surface ground motion for the 3 november 2002 denali fault earthquake based on spectral element simulations using crustal model crust2 0 mantle model s20rts topography and bathymetry model etopo5 and a finite fault slip model the movie features two anomalous wave packets that travel along the west coast of the north american plate following off great circle paths these wave packets are rayleigh waves with dominant periods around 20 sec which are also found in seismograms recorded by the southern cali fornia seismic network one of these packets is the direct surface wave whose group arrival time changes laterally as dictated by the shape of the oregon coast the other packet is a surface wave reflected by a lateral interface underneath the rocky moun tains a linear reflector parallel to the canadian coast offsetting it by a few hundred kilometers can explain its arrival time but the offsetting distance derived from the synthetic seismograms puts the reflector 350 km northeast of the result obtained from the data indicating a need to update the crustal and mantle models in this area online material animation of normalized simulated vertical displacement for the 2002 denali earthquake

reflection of seismic surface waves at the northern apennines abstract seismic surface waves with periods of 15 to 20 s are reflected laterally at the northern apennines for earthquakes originated and recorded in the wider alpine area a few hundred kilometres north of the apennines we can directly observe late arrivals of reflected regional surface waves these have a characteristic polarization of particle motion and often dominate the intermediate period surface wave coda love waves are the most prominent coda arrivals while reflected rayleigh waves show smaller amplitudes and become clear only after rotation of the recordings to the reflection incidence direction we can track the development of the love wave reflection along a temporary broad band transect across the northern apennines indicating the location of the reflector near to the highest topography from spectral element simulations of three dimensional wave propagation we attribute the reflection to a continuous 270 km long offset in the crust mantle boundary under the mountain belt with vertical throw of 20 km thus supporting a deep crustal root under the outer side of the apennines fold and thrust belt and significant crustal thinning on the inner side amplitude reflection coefficients for near normal incidence can be estimated as 7 for both love and rayleigh waves

structure and development of the sagami trough and the boso triple junction abstract the sagami trough is located at the particular plate margin where the izu forearc is subducted underneath the honshu forearc at its southeastern end the world s only known ttt type triple junction boso triple junction has developed several different kinds of basins occur in different segments along the sagami trough and at the triple junction the bathymetric geologic and geophysical data obtained during the kaiko project and from additional studies are summarized together with our onland studies we suggest that the right lateral oblique plate motion formed an eduction margin in the sagami basin while a normal subduction margin and an oblique subduction margin have been formed in the middle sagami trough basin these tectonic phenomena resulted from the long lasting compressional covergence between the philippine sea plate and eurasian plate since the early or middle miocene the north basin on the northeasternmost margin of the philippine sea plate near the boso triple junction has developed as a stretched basin due to the westward motion of the philippine sea plate with respect to the eurasian plate

anomalous surface waves associated with deep earthquakes generated at an ocean ridge summary broad band seismograms observed at regional distances from deep earthquakes display large amplitude rayleigh and love waves with a predominant period of about 20 s although deep earthquakes in laterally homogeneous structures do not generate such surface waves since the propagation direction of the surface waves inferred from particle motion is approximately radial and the group velocity of the surface waves observed at each station is similar it can be assumed that the surface waves have travelled close to the great circle paths back projection allows us to determine the region in which these surface waves are generated manyof the zones from which the surface waves appear to originate are located close to the norfolk ridge where crustal structure has strong lateral heterogeneity this suggests that the surface waves are generated by the interaction of body waves from the deep earthquakes with this strongly heterogeneous crustal structure in order to investigate the eiect of such heterogeneity in crustal structure on seismic wave elds we have modelled the p sv wave eld using a pseudospectral method the results show that surface waves such as those observed can be generated by ridge structures and indicate that sedimentary layer thickness plays a very important role we suggest that such unexpected surface waves from deep earthquakes may prove useful for delineating heterogeneity in shallow structure

nature of mixed layer clays and mechanisms of their formation and alteration abstract mixed layer clay minerals are intermediate products of reactions involving pure end member clays they come from natural environments ranging from surface to low grade metamorphic and hydrothermal conditions most often mixed layering is essentially two component but more complicated interstratifications have also been documented variable tendency to form regular 1 1 interstratifications has been observed and explanations of this phenomenon have been proposed mixed layer clays are either di or trioctahedral di trioctahedral interstratifications are rare most mixed layer clays contain smectite or vermiculte as a swelling component exceptions are all trioctahedral serpentine chlorite in low temperature environments and mica chlorite and talc chlorite at high temperatures solid state transformation and dissolution crystallization are the two mechanisms responsible for the formation of different mixed layer clays in general the weathering reactions that produce mixed layering are revers

sediment supply and channel morphology in mountain river systems 1 relative importance of lithology topography and climate 1 quantifying landscape scale variations in sediment supply to streams and rivers is fundamental to our understanding of both denudational processes and stream channel morpho dynamics previous studies have linked a variety of sediment supply proxies to climatic topographic or geologic factors but few have connected these directly to the characteristics of fluvial systems draining these landscapes here we correlate landscape controls on sediment supply to observed sedimentology and channel patterns through direct measurements of water and sediment fluxes in over 80 drainage basins ranging in area from 1 4 to 35 000 km2 in the northern rocky mountains usa these data show that the relative sediment supply defined by the bankfull sediment concentration is dominated by basin lithology while exhibiting little correlation to factors such as relief mean basin slope and drainage density bankfull sediment concentrations bed load and suspended load increase as much as 100 fold as basin lithology becomes dominated by softer sedimentary and volcanic rocks relative to basins with more resistant lithologies as bed load concentrations increase stream beds become less armored and bed load grain size coarsens at very high sediment concentrations bed surface subsurface and bed load grain sizes converge and a transition from single thread to to braided channel patterns is commonly observed

scattering of teleseismic body waves by the lateral crustal heterogeneity at the pacific trench of mexico we examine the scattered field generated at the pacific trench of mexico upon the incidence of teleseismic body waves and the waveguide properties associated with the structure of the subduction zone in this study we analyze seismic records from a portable array perpendicular to the trench that show a distinctive phase with a phase velocity of graphic 1 following body wave phases this signal is better observed following phases with high incident angles such as ps sp and ss arriving from the ocean side of the trench and for events at teleseismic distances with magnitudes larger than m w 7 0 although weak scattered signals were detected for events down to m w 6 2 and for direct p and s phases we found that the lateral transition between the dipping slab and continental crust with an inclined boundary formed by the subducting slab at the trench generates a strong discontinuity that scatters seismic waves generating a secondary field with amplitude comparable to the incident wave this phase appears for incident body wave arrivals with characteristic wavelength comparable to the thickness of the continental crust analysis of the observed scattered field shows that the trapped waves are vertically polarized surface waves numerical modeling suggests that the impedance contrast at the trench and the geometry of the subducting slab form a waveguide like structure that efficiently generates and transmits trapped seismic waves along the continental margin 1 embed inline graphic 1 gif

localized damage caused by topographic amplification during the 2010 m 7 0 haiti earthquake microzonation maps use local geological conditions to characterize seismic hazard but do not generally consider topography ground motions during the haiti earthquake are found to have been significantly amplified along a high topographic ridge which caused substantial structural damage indicating that topography can play an important role in seismic hazard local geological conditions including both near surface sedimentary layers1 2 3 4 and topographic features5 6 7 8 9 are known to significantly influence ground motions caused by earthquakes microzonation maps use local geological conditions to characterize seismic hazard but commonly incorporate the effect of only sedimentary layers10 11 12 microzonation does not take into account local topography because significant topographic amplification is assumed to be rare here we show that although the extent of structural damage in the 2010 haiti earthquake was primarily due to poor construction topographic amplification contributed significantly to damage in the district of petionville south of central port au prince a large number of substantial relatively well built structures situated along a foothill ridge in this district sustained serious damage or collapse using recordings of aftershocks we calculate the ground motion response at two seismic stations along the topographic ridge and at two stations in the adjacent valley ground motions on the ridge are amplified relative to both sites in the valley and a hard rock reference site and thus cannot be explained by sediment induced amplification instead the amplitude and predominant frequencies of ground motion indicate the amplification of seismic waves by a narrow steep ridge we suggest that microzonation maps can potentially be significantly improved by incorporation of topographic effects

co2 forced climate and vegetation instability during late paleozoic deglaciation the late paleozoic deglaciation is the vegetated earth9s only recorded icehouse to greenhouse transition yet the climate dynamics remain enigmatic by using the stable isotopic compositions of soil formed minerals fossil plant matter and shallow water brachiopods we estimated atmospheric partial pressure of carbon dioxide pco2 and tropical marine surface temperatures during this climate transition comparison to southern gondwanan glacial records documents covariance between inferred shifts in pco2 temperature and ice volume consistent with greenhouse gas forcing of climate major restructuring of paleotropical flora in western euramerica occurred in step with climate and pco2 shifts illustrating the biotic impact associated with past co2 forced turnover to a permanent ice free world

cosmocalc an excel add in for cosmogenic nuclide calculations as dating methods using terrestrial cosmogenic nuclides tcn become more popular the need arises for a general purpose and easy to use data reduction software the cosmocalc excel add in calculates tcn production rate scaling factors using lal stone dunai and desilets methods topographic snow and self shielding factors and exposure ages erosion rates and burial ages and visualizes the results on banana style plots it uses an internally consistent tcn production equation that is based on the quadruple exponential approach of granger and smith 2000 cosmocalc was designed to be as user friendly as possible although the user interface is extremely simple the program is also very flexible and nearly all default parameter values can be changed to facilitate the comparison of different scaling factors a set of converter tools is provided allowing the user to easily convert cut off rigidities to magnetic inclinations elevations to atmospheric depths and so forth because it is important to use a consistent set of scaling factors for the sample measurements and the production rate calibration sites cosmocalc defines the production rates implicitly as a function of the original tcn concentrations of the calibration site the program is best suited for be 10 al 26 he 3 and ne 21 calculations although basic functionality for cl 36 and c 14 is also provided cosmocalc can be downloaded along with a set of test data from http cosmocalc googlepages com

quantitative paleoenvironmental and paleoclimatic reconstruction using paleosols abstract paleosols fossil soils are preserved throughout the geologic record in depositional settings ranging from alluvial systems to between basalt flows until recently paleosols were studied using primarily qualitative methods in recent years paleopedology has shifted from a largely qualitative field based on comparisons with modern analogues to an increasingly quantitative endeavor some of this change has been a result of applying existing techniques to new materials but many of the innovations have been the result of applying new techniques to new materials including thermodynamic modeling of soil formation isotope geochemistry and applications of empirical relationships derived from modern soils a variety of semi quantitative and quantitative tools has been developed to examine past weathering and pedogenesis and to reconstruct both paleoenvironmental and paleoclimatic conditions at the time that the paleosols formed though it is often not possible to achieve the same temporal resolution as with marine records for paleoclimatic reconstructions proxies based on paleosols are potentially a much more direct means of making paleoclimatic reconstructions because soils form at the earth s surface in direct contact with the atmospheric and climatic conditions at the time of their formation paleoclimatic and environmental properties that may be reconstructed using the new proxies include provenance weathering intensity mean annual precipitation and temperature during pedogenesis nutrient fluxes into and out of the paleosols the atmospheric composition of important gases including co2 and o2 the moisture balance during pedogenesis the soil gas composition reconstructed vegetative covering and paleo altitude

substrate sediment and slope controls on bedrock channel geometry in postglacial streams the geometry of channels controls the erosion rate of rivers and the evolution of topography following environmental change we examine how sediment slope and substrate interact to constrain the development of channels following deglaciation and test whether theoretical relationships derived from streams reacting to tectonic uplift apply in these settings using an extensive data set of channel geometry measurements from postglacial streams in the scottish highlands we find that a power law width drainage area scaling model accounts for 81 of the spatial variation in channel width substrate influences channel form at the reach scale with bedrock channels found to be narrower and deeper than alluvial channels bedrock channel width does not covary with slope which may be due to downstream variations in sediment flux bedrock channel width to depth ratios increase with discharge or area and sediment flux consistent with increasing bed cover promoting lateral widening we find steep wide and shallow bedrock channels immediately below lakes which we interpret as the result of limited erosion due to a lack of sediment tools where sediment supply is sufficient to exceed transport capacity alluvial channels develop wider shallower geometries constrained primarily by flow hydraulics our results indicate that simple scaling models of channel width with drainage area are applicable at regional scale but locally channel width varies with substrate and in the case of bedrock channels with sediment flux

reverse propagation of surface waves reflected from seamounts in the northwestern pacific abstract the reverse propagation of a surface wave traveling through the japanese islands from southwest to northeast was detected for major shallow earthquakes that occurred in northeastern japan the wave is predominant in the transverse component having a period of 20 sec and lasting longer than 200 sec the propagation velocity is around 3 8 km sec which is characteristic of a typical surface wave semblance analysis using a dense seismograph network shows that the wave was generated near the kyushu palau ridge southeast of kyushu island numerical simulation with a 3d finite element method can explain the surface wave reflection predominant in the transverse component as reflection from seamounts with a crustal root 10 km deeper than the moho discontinuity at the surrounding ocean floor the observed long duration of the reverse propagating surface wave might represent the superposition of a reflected wave from other seamounts and or the thick sedimentary layer along the nankai trough

low temperature illitization of smectite in the late eocene and early oligocene of the isle of wight hampshire basin u k variegated palaeosols which formed from weathering of clays silts and brackish to freshwater limestones are present in the late eocene early oligocene solent group of the hampshire basin southern u k the detrital clay mineral suite is dominated by illite and illite smectite with minor kaolinite and chlorite in pedogenically modified palaeosol and evaporitic lacustrine clay rich sediments the proportion of illite in the illite smectite is greater than in the non pedogenically modified sediments and where alteration is most intense kaolinite and chlorite are absent the smectite to illite transition has been investigated in the 0 5 m fraction by xrd analysis powder and oriented mounts thermogravimetry tg analytical sem and chemical analysis of fe2 modeling of xrd data reveals that the illite smectite is a mixture of compositions overall 60 95 illite r 0 with high rotational stacking disorder dehydroxylation occurs mainly at 500 c but also at higher temperatures indicating heterogeneous octahedral cation composition analytical sem and chemical analysis of fe2 indicate that the illite to smectite transition occurs through fe reduction in octahedral sites leading to increased layer charge coupled with k fixation the driving mechanism for what appears to be irreversible fe3 reduction is wetting reducing and drying oxidizing cycles in gley soil in which reoxidation of reduced fe is never complete

quantitative geochemical approach to pedogenesis importance of parent material reduction volumetric expansion and eolian influx in lateritization abstract using mass balance techniques we test the prevalent view that laterite genesis is dominated by in situ residual enrichment during chemical weathering of bedrock through calculation of net mass fluxes through the laterite soils in mali west africa we show that residual enrichment by removal of mobile elements with a corresponding increase in bulk porosity and decrease in bulk density contributes only a very minor fraction of the enrichment of al fe si and au instead we demonstrate that the abundance of these elements is due to the influx and accumulation by selective retention of chemically mature detritus of local and foreign origin clearly evident in micromorphological infilling features at the same sample depths that accumulation reaches extreme values we show that volumetric expansion in excess of 200 has occurred locally we infer that these spatially coincidental zones of mass influx of rock forming metals fe al si and also au with dilational hyperstrains result from a mutually reinforcing mechanical interaction between material influx and the effects of subsurface deformational processes such as shrink swell cycles and root growth and decay we propose that with progressive infilling of available connected voids by illuvial microsedimentary deposits of insoluble resistate and neoformed minerals the capacity for the combined skeleton and plasma to remain isovulumetric is exceeded we speculate that the resultant space problem is relieved by upwards expansion towards the overlying free surface continued translocation and void infilling occur and are limited to the depth where the size of translocational particles is smaller than that of the connected voids consequently progressive hyperstrains accumulate above this critical depth by the long term influence of a proposed translocational wedge of chemically resistant minerals against which numerous generations of plant roots have exerted stresses eclectic surficial contaminants involved are continuously derived from above leaving no indication of a relict source region within the present soil profile from which they might have been extracted instead the source region is largely the existing regolith column itself which releases local material and in addition is supplemented by deposition of colluvial detritus shed nearby by escarpment retreat

fdm simulation of seismic waves ocean acoustic waves and tsunamis based on tsunami coupled equations of motion we have developed a new unified modeling technique for the total simulation of seismic waves ocean acoustic waves and tsunamis resulting from earthquakes based on a finite difference method simulation of the 3d equations of motion using the equilibrium between the pressure gradient and gravity in these equations tsunami propagation is naturally incorporated in the simulation based on the equations of motion the performance of the parallel computation for the newly developed tsunami coupled equations using a domain partitioning procedure shows a high efficiency coefficient with a large number of cpu cores the simulation results show how the near field term associated with seismic waves produced by shallow earthquakes leads to a permanent coseismic deformation of the ground surface which gives rise to the initial tsunami on the sea surface propagation of the tsunami along the sea surface as a gravity wave and ocean acoustic waves in seawater with high frequency multiple p wave reflections between the free surface and sea bottom are also clearly demonstrated by the present simulations we find a good agreement in the tsunami waveform between our results and those obtained by other simulations based on an analytical model and the navier stokes equations demonstrating the effectiveness of the tsunami coupling simulation model based on this simulation we show that the ratio of the amplitude of ocean acoustic waves to the height of the tsunami both of which are produced by the earthquake strongly depends on the rise time of the earthquake rupture this ratio can be used to obtain a more detailed understanding of the source rupture processes of subduction zone earthquakes and for implementing an improved tsunami alert system for slow tsunami earthquakes

spatial variability of palaeosols across cretaceous interfluves in the dunvegan formation ne british columbia canada palaeohydrological palaeogeomorphological and stratigraphic implications a basic sedimentological and palaeopedological framework is now in place for non marine sequence models the variability of interfluve palaeosols has not however been systematically documented nor have the stratigraphic implications of that variability been incorporated into sequence models interfluve palaeosol variability in the deltaic dunvegan formation ne british columbia canada is investigated for which a detailed allostratigraphic and palaeogeographic framework has been developed based on abundant well 2300 logs and outcrop 60 sections control regionally extensive valley fills and interfluves have been mapped in coastal plain deposits over an area of about 50 000 km 2 this palaeogeographic framework permits interfluve surfaces exposed in outcrop to be located in terms of distance from the margins of coeval valleys the micromorphological geochemical and mineralogical characteristics of five representative sequence bounding palaeosols located from 250 m to more than 15 km from coeval valley margins are described these interfluve palaeosols are similar to modern alfisols and all record i aggradation on an alluvial coastal plain ii a subsequent static and or degradational phase related to valley incision nondeposition and soil thickening and iii a final aggradational phase related to valley filling and renewed sedimentation across the coastal plain within this overall template however variations in palaeosol thickness redoximorphic features illuvial clay content and geochemistry suggest developmental control by hydrological characteristics that were influenced by both the nature of the underlying alluvial sediments and distance from the valley margin the presence of mature interfluve palaeosols with complex developmental histories suggests that landscape dissection may have been related to terrace development associated with valley incision palaeosols closer to valley margins are thicker contain more illuvial clay and display characteristics suggesting better drained conditions relative to those palaeosols that developed further from valley margins subsequent deposition on interfluves also reflects distance from valleys with those sites close to valleys accumulating cumulic soils with evidence of brackish groundwater whereas far from valleys 10 15 km groundwater was fresh and clastic supply minimal encouraging peat formation variations in drainage and palaeotopography during landscape dissection resulted in different palaeosol development styles on interfluve surfaces that can be shown on the basis of physical correlation to have the same geomorphic age these observations support the concept of the soil forming interval as a basis for pedostratigraphic correlation in ancient terrestrial deposits palaeosol variability on interfluves is to be expected and recognition and documentation of this variability is an important prerequisite to palaeogeomorphological palaeoclimatic and sequence stratigraphic interpretations

cover effect in bedrock abrasion a new derivation and its implications for the modeling of bedrock channel morphology the sediment load of a bedrock river plays an important role in the fluvial incision process by providing tools for abrasion the tools effect and by covering and thereby protecting the bed the cover effect we derive a new formulation for the cover effect in which the fraction of exposed bed area falls exponentially with increasing sediment flux or decreasing transport capacity and explore its consequences for the model of bedrock abrasion by saltating bed load erosion rates predicted by the model are higher than those predicted by earlier models in a closed system the maximum erosion rate is predicted to occur when sediment supply is equal to transport capacity for a flat bed by optimizing the channel geometry to minimize the potential energy of the stream and using representative values for both discharge and grain size we derive equations for the geometry of a bedrock river and explore how predictions for width slope and bed cover vary as functions of drainage area rock uplift rate and rock strength the equations predict a dependence of channel width on drainage area similar to the relations using a simple shear stress incision law the slope area relationship is predicted to be concave up in a log log regime with a curvature dependent on uplift rate however this curvature does not deviate sufficiently from a straight line to allow discrimination between models using empirical data dependence of channel width and slope on rock uplift rate can be separated into two domains for low uplift rates channel geometry is largely insensitive to uplift rate due to a threshold effect at high uplift rates there is a power law dependence bed cover is predicted to increase progressively downstream and to increase with increasing uplift rate in our model the width to depth ratio is a function of both tectonic and climatic forcing this indicates that the scaling between channel width and bed slope is neither a unique indicator of tectonic forcing at steady state nor a signature of transience or steady state we conclude that sediment effects need to be taken into account when modeling bedrock channel morphology

the growth of northeastern tibet and its relevance to large scale continental geodynamics a review of recent studies recent studies of the northeastern part of the tibetan plateau have called attention to two emerging views of how the tibetan plateau has grown first deformation in northern tibet began essentially at the time of collision with india not 10 20 myr later as might be expected if the locus of activity migrated northward as india penetrated the rest of eurasia thus the north south dimensions of the tibetan plateau were set mainly by differences in lithospheric strength with strong lithosphere beneath india and the tarim and qaidam basins steadily encroaching on one another as the region between them the present day tibetan plateau deformed and its north south dimension became narrower second abundant evidence calls for acceleration of deformation including the formation of new faults in northeastern tibet since 15 ma and a less precisely dated change in orientation of crustal shortening since 20 ma this reorientation of crustal shortening and roughly concurrent outward growth of high terrain which swings from nne ssw in northern tibet to more ne sw and even ene wsw in the easternmost part of northeastern tibet are likely to be in part a consequence of crustal thickening within the high tibetan plateau reaching a limit and the locus of continued shortening then migrating to the northeastern and eastern flanks these changes in rates and orientation also could result from removal of some or all mantle lithosphere and increased gravitational potential energy per unit area and from a weakening of crustal material so that it could flow in response to pressure gradients set by evolving differences in elevation

solutions of the stream power equation and application to the evolution of river longitudinal profiles 1 erosion by bedrock river channels is commonly modeled with the stream power equation we present a two part approach to solving this nonlinear equation analytically and explore the implications for evolving river profiles first a method for non dimensionalizing the stream power equation transforms river profiles in steady state with respect to uniform uplift into a straight line in dimensionless distance elevation space second a method that tracks the upstream migration of slope patches which are mathematical entities that carry information about downstream river states provides a basis for constructing analytical solutions slope patch analysis explains why the transient morphology of dimensionless river profiles differs fundamentally if the exponent on channel slope n is less than or greater than one and why only concave up migrating knickpoints persist when n 1 at migrating knickpoints slope patches and the information they carry are lost a phenomenon that fundamentally limits the potential for reconstructing tectonic histories from bedrock river profiles stationary knickpoints which can arise from spatially varying uplift rates differ from migrating knickpoints in that slope patches and the information they carry are not lost counterparts to migrating knickpoints called stretch zones are created when closely spaced slope patches spread to form smooth curves in distance elevation space these theoretical results are illustrated with examples from the california king range and the central apennines

tropical chemical weathering of hillslope deposits and bedrock source in the aburra valley northern colombian andes abstract tropical chemical weathering produces extensive lateritization and formation of deep weathering profiles both processes are fundamental to landscape evolution and slope instability the aburra valley of the northern colombian andes is characterized by tropical conditions the valley slopes are mostly covered by hillslope deposits originating from four basement rock suites which comprise contrasting granitoid volcanic sedimentary ophiolitic and metamorphic sources respectively tropical chemical weathering of the aburra hillslope deposits and their respective bedrock were examined using x ray fluorescence and x ray diffraction analysis to document and quantify their chemical weathering profiles compositions and mineralogical properties the chemical index of alteration cia loss on ignition loi and the mobiles index imob were used to quantify the degree of weathering of hillslope deposits and bedrock source weathering trends were analyzed using a cn k and a cnk fm diagrams the material mantling the slopes in the aburra valley records an intense weathering history chemical weathering is characterized by increased development of clay minerals kaolinite halloysite and iron and aluminum sesquioxides lateritization characterizes the final stage of the weathering profiles concentrations of cao na2o k2o decrease markedly in the weathering products compared to the fresh bedrock source whereas concentrations of al2o3 fe2o3 and mgo increase significantly cia ratios of matrix slope deposits derived from all four sources near 100 whereas those of boulder slope deposits and saprolites are lower but exceed source rock values different a cn k weathering paths are evident for each lithotype validating the correlation established between the hillslope deposits and their various parents chemical weathering indices in some samples are strongly influenced by the presence of sesquioxides as reflected by high loi anomalously low cia and varying enrichment trends on the a cnk fm diagrams consequently different chemical indices based on different criteria need to be combined to obtain best results as illustrated here by the combination of loi cia and imob the overall results suggest that tropical conditions have dominated for a long time in the northern colombian andes leading to uniformly high weathering indices in matrix slope deposits irrespective of parent lithotype prolonged warm and humid conditions could thus be responsible for the weathering and remobilization of extensive old hillslope deposits during the quaternary however in addition to the influence of climatic factors tectonism has also undoubtedly influenced slope evolution in the aburra valley

late paleocene arctic ocean shallow marine temperatures from mollusc stable isotopes late paleocene high latitude 80 n arctic ocean shallow marine temperatures are estimated from molluscan 18o time series sampling of individual growth increments of two specimens of the bivalve camptochlamys alaskensis provides a high resolution record of shell stable isotope composition the heavy carbon isotopic values of the specimens support a late paleocene age for the youngest marine beds of the prince creek formation exposed near ocean point alaska the oxygen isotopic composition of regional freshwater runoff is estimated from the mean 18o value of two freshwater bivalves collected from approximately coeval fluviatile beds over a 30 34 range of salinity values assumed to represent the tolerance of c alaskensis the mean annual shallow marine temperature recorded by these individuals is between 11 and 22 c these values could represent maximum estimates of the mean annual temperature because of a possible warm month bias imposed on the average 18o value by slowing or cessation of growth in winter months the amplitude of the molluscan 18o time series probably records most of the seasonality in shallow marine temperature the annual temperature range indicated is approximately 6 c suggesting very moderate high latitude marine temperature seasonality during the late paleocene on the basis of analogy with modern chlamys species c alaskensis probably inhabited water depths of 30 50 m the seasonal temperature range derived from 18o is therefore likely to be damped relative to the full range of annual sea surface temperatures high resolution sampling of molluscan shell material across inferred growth bands represents an important proxy record of seasonality of marine and freshwater conditions applicable at any latitude if applied to other regions and time periods the approach used here would contribute substantially to the paleoclimate record of seasonality

an uplift history of the colorado plateau and its surroundings from inverse modeling of longitudinal river profiles 1 it is generally agreed that a region encompassing the colorado plateau has been uplifted by sub crustal processes admittance calculations tomographic studies and receiver function analyses suggest that dynamic support is generated by some combination of convective upwelling and lithospheric thickness changes notwithstanding advances in our understanding of present day setting uplift rate histories are poorly constrained and debated an improved history will aid discrimination between proposed models here we show that a regional uplift rate history can be obtained by inverting longitudinal river profiles we assume that the shape of a river profile is controlled by uplift rate and moderated by erosion in our model uplift rate is allowed to vary smoothly as a function of space and time upstream drainage area is invariant with time simultaneous inversion of river profiles from the colorado rio grande columbia and mississippi catchments shows that three phases of regional uplift occurred the first phase occurred between 80 and 50 myrs when 1 km of uplift was generated at a rate of 0 03 mm yr a second phase occurred between 35 and 15 myrs when 1 5 km of uplift was generated at a faster rate of 0 06 mm yr a final phase of uplift commenced 5 myrs ago these distinct phases of late cretaceous and oligocene uplift are corroborated by stratigraphic considerations by thermochronometric data and by stratigraphic evidence of periodic clastic efflux delivered into the gulf of mexico an episodic uplift history is consistent with staged removal of thick lithospheric mantle beneath a large region which is currently centered on yellowstone

fdm simulation of an anomalous later phase from the japan trench subduction zone earthquakes we investigated the development of a distinct later phase observed at stations near the japan trench associated with shallow outer rise earthquakes off the coast of sanriku northern japan based on the analysis of three component broadband seismograms and fdm simulations of seismic wave propagation using a heterogeneous structural model of the japan trench subduction zone snapshots of seismic wave propagation obtained through these simulations clearly demonstrate the complicated seismic wavefield constructed by a coupling of the ocean acoustic waves and the rayleigh waves propagating within seawater and below the sea bottom by multiple reflections associated with shallow subduction zone earthquakes we demonstrated that the conversion to the rayleigh wave from the coupled ocean acoustic waves and the rayleigh wave as they propagate upward along the slope of seafloor near the coast is the primary cause of the arrival of the distinct later phase at the station near the coast through a sequence of simulations using different structural models of the japan trench subduction zone we determined that the thick layer of seawater along the trench and the suddenly rising sea bottom onshore of the japanese island are the major causes of the distinct later phase the results of the present study indicate that for realistic modeling of seismic wave propagation from the subduction zone earthquakes a high resolution bathymetry model is very crucial although most current simulations do not include a water column in their simulation models

variation in the reference shields stress for bed load transport in gravel bed streams and rivers 1 the present study examines variations in the reference shear stress for bed load transport r using coupled measurements of flow and bed load transport in 45 gravel bed streams and rivers the study streams encompass a wide range in bank full discharge 1 2600 m3 s average channel gradient 0 0003 0 05 and median surface grain size 0 027 0 21 m a bed load transport relation was formed for each site by plotting individual values of the dimensionless transport rate w versus the reach average dimensionless shear stress the reference dimensionless shear stress r was then estimated by selecting the value of corresponding to a reference transport rate of w 0 002 the results indicate that the discharge corresponding to r averages 67 of the bank full discharge with the variation independent of reach scale morphologic and sediment properties however values of r increase systematically with average channel gradient ranging from 0 025 0 035 at sites with slopes of 0 001 0 006 to values greater than 0 10 at sites with slopes greater than 0 02 a corresponding relation for the bank full dimensionless shear stress bf formulated with data from 159 sites in north america and england mirrors the relation between r and channel gradient suggesting that the bank full channel geometry of gravel and cobble bedded streams is adjusted to a relatively constant excess shear stress bf r across a wide range of slopes

seismic and tsunami wave propagation of the 2011 off the pacific coast of tohoku earthquake as inferred from the tsunami coupled finite difference simulation abstract the 2011 tohoku earthquake m 9 0 caused significant hazards including strong ground motion coseismic ground deformation and tsunamis for a deeper understanding of these phenomena we conducted a large scale parallel computer simulation by means of the finite difference method fdm with newly developed tsunami coupled equations of motion this method is based on the equations of motion for an elastic medium treating seawater as elastic material having zero s wave velocity tsunami waves are included by taking into account gravity and their equilibrium with the pressure gradient an effective method of fdm simulation using the state of the art massively parallelized k computer is also studied with the use of a 3d layered velocity structure that includes topography and bathymetry basement structure moho depth and plate boundaries and use of the appropriate source rupture model based on joint inversion of seismic waves and geodetic observations the simulated seismic waves demonstrate anomalous seismic wave propagation by the thick 3d basin structure inland we also found that the sea column acts as a strong absorber of seismic waves for shallow up dip slip on the ocean side coseismic deformation and tsunamis are dynamically generated in this simulation tsunami attacks on the subsided pacific coast are simulated without any additional assumptions we also modeled the tsunami and seismic records of ocean bottom pressure gauges above the fault because sea bottom tsunami and seismic observation is powerful but very complex recording both seismic and tsunami waves the use of these coupled numerical simulations has great potential for resolving complex source fault rupture processes in a 3d heterogeneous structure online material mpeg movies of fault slip seismic wave propagation seafloor and ground displacement and tsunamic propagation

distributed deformation around the eastern tip of the kunlun fault whether active strain within the indo asian collision zone is primarily localized along major strike slip fault systems or is distributed throughout the intervening crust between faults remains uncertain despite refined estimates of slip rates along many of the major fault zones relatively little is known about how displacement along these structures is accommodated at fault terminations here we show that a systematic decrease in left lateral slip rates along the eastern 200 km of the kunlun fault from 10 mm year to 1 mm year is coincident with high topography in the anyemaqen shan and with a broad zone of distributed shear and clockwise vorticity within the tibetan plateau geomorphic analysis of river longitudinal profiles coupled with inventories of cosmogenic radionuclides in fluvial sediment reveal correlated variations in fluvial relief and erosion rate across the anyemaqen shan that reflect ongoing differential rock uplift across the range our results imply that the termination of the kunlun fault system is accommodated by a combination of distributed crustal thickening and by clockwise rotation of the eastern fault segments

distribution of active rock uplift along the eastern margin of the tibetan plateau inferences from bedrock channel longitudinal profiles 1 current models of long term river incision into bedrock suggest that the local rate of differential rock uplift should exert a primary control on the gradient of channel longitudinal profiles however discrimination of this effect from the influence of variations in substrate erodibility sediment flux precipitation and transient changes in profile shape has proved difficult in practice here we investigate the controls on the spatial distribution of bedrock channel gradients adjacent to the sichuan basin in an effort to assess the degree and nature of active deformation along this margin of the tibetan plateau analysis of river longitudinal profiles utilizing a channel steepness index a measure of profile gradient normalized for drainage area reveals a zone of anomalously steep channels adjacent to the topographic front of the plateau margin channel profiles are systematically less steep in their headwater reaches on the plateau and in their lower reaches east of the plateau margin comparison of steepness indices to mapped lithologic variations reveals that lithology has only a limited influence on channel gradient in this field area we observe no systematic relationship between steepness indices and upstream drainage area channels of all size are steeper near the plateau margin we argue that these systematic changes are not readily explained as a consequence of increased sediment flux or of orographic precipitation we are led to conclude that steep channel profiles along the topographic front of the plateau reflect active differential rock uplift between this region and the foreland