mineralogy of soils from two continental scale transects across the united states and canada and its relation to soil geochemistry and climate abstract quantitative mineralogy correlates with major minor and trace element chemistry for 387 samples of a horizon and deeper soils collected from east west and north south transects across the usa and canada where the deeper soils were collected beneath the a horizon samples concentrations of the major elements correlate with specific mineral phases minor and trace element concentrations correlate with the same phases as the major elements with which they share similar geochemical behavior concentrations of quartz and feldspar correlate with precipitation trends east of the rocky mountains and are independent of the underlying rock type and age indicating that the weathering of soils in this region may have reached a steady state mineralogy other trends in mineralogy relate to physiographic province the combination of quantitative mineralogy and chemical analysis yields a much richer portrait of soils than can be gained from chemistry alone because the origins of chemical trends and the chemical availability of specific elements are related to mineralogy

paleoclimatic interpretations of buried paleosols within the pre illinoian till sequence in northern missouri usa abstract northern missouri preserves shallow buried paleosols ranging in age from early to late pleistocene that are developed in six pre illinoian tills beneath illinoian mis 6 and wisconsinan mis 4 2 loess the morphology of these paleosols changes with age reflecting a changing climate during the pleistocene and cosmogenic nuclide burial dates of the respective sola provide age control on the timing of these changes the depth to secondary calcium carbonate nodules within the weathering profiles increases with younger age indicating a transition to moister conditions during the pleistocene and these nodules are absent entirely within the modern soils after approximately 0 4 ma the sola became distinctly redder even as the time available for pedogenesis became shorter culminating in the bright red sangamon geosol mis 5 this trend is consistent with increasing interglacial temperatures and or precipitation finally erosion rates determined from cosmogenic nuclide concentrations within the sola also increase systematically with younger age this increase may be due to some combination of changing climate more frequent glaciations and the deposition of a thick cover of unconsolidated glacial sediment above the stable residuum dominated preglacial landscape

chemical weathering indices applied to weathering profiles developed on heterogeneous felsic metamorphic parent rocks abstract chemical weathering indices are commonly used for characterizing weathering profiles by incorporating bulk major element oxide chemistry into a single metric for each sample generally on homogeneous parent rocks weathering indices change systematically with depth however the weathering of heterogeneous metamorphic rocks confounds the relationship between weathering index and depth in this paper we evaluate previously defined chemical weathering indices for their suitability in characterizing weathering profiles developed on felsic heterogeneous metasedimentary bedrock from coweeta hydrologic laboratory north carolina usa among the weathering indices evaluated here the weathering index of parker wip is the most appropriate for application to weathering profiles on heterogeneous and homogeneous parent rock because the wip includes only the highly mobile alkali and alkaline earth elements in its formulation it yields values that differ greatly from those of the parent rock in addition the wip allows for aluminum mobility unlike other weathering indices these characteristics combine to make the weathering index of parker the most applicable index for studying the weathering of heterogeneous metasedimentary rocks however the wip should be applied judiciously as alkali and alkaline earth metals may be readily depleted during weathering in addition to reflecting weathering the chemical index of alteration cia chemical index of weathering ciw plagioclase index of alteration pia and vogt s residual index v may be sensitive to subtle geochemical changes such as hydrothermal alteration along a fault and or alteration at the water table weathering indices that include iron in their calculations were not included in this study because they do not distinguish between ferric and ferrous iron the oxidation state and distribution of iron in a weathering profile is influenced by the proportion of oxidation states in the pre weathered metamorphic rock and interaction with groundwater during weathering

thermal electric ice core drills history and new design options for intermediate depth drilling ice coring of temperate and polythermal glaciers demonstrates some limitations of most electromechanical em and thermal electric te drills most te drills are heavy require a heavy power system work slowly and cannot operate in boreholes going through the cold temperate ice transition antifreeze thermal electric drills ated are capable of operating in polar ice caps polythermal and temperate glaciers in boreholes filled with water and or hydrophilic fluids performance of the ated drill can be improved by using an open top core barrel and low power and narrow kerf coring head ated type drills can be modified for an open top core barrel equipped with low power coring head and include a new scheme for drilling fluid circulation using two pumps a small metering pump releases pure ethanol above the top of the drill and a second pump enables circulation of the borehole fluid an ethanol water solution ews above the kerf use of a narrow kerf coring head reduces power requirements and makes it possible to design a lightweight drilling system that includes the em and te drills for shallow and intermediate depth drilling

macropore flow on a reclaimed surface mine infiltration and hillslope hydrology abstract surface coal mining in central pennsylvania alters the physical and hydrological properties of soil from its undisturbed state and changes the surface hydrologic response to precipitation newly reclaimed minesoils exhibit low steady state rates of infiltration 1 2 cm h and produce runoff dominated by infiltration excess overland flow within 4 years after reclamation rates of infiltration on some minesoil surfaces approach pre mined rates 8 cm h as a greater percentage of rainfall infiltrates these reclaimed minesoils little change occurs in the total volume of surface storm runoff on an event basis this indicates that infiltrated water contributes to storm runoff by the processes of throughflow and return flow as the rate of infiltration increases with time the hydrologic response of the minesoil is controlled by rapid macropore throughflow within the unsaturated minesoil application of fluorescent dyes on the reclaimed surface reveals preferred flowpaths through macropores surrounding the numerous large rock fragments in the minesoil development and integration of a macropore network on a reclaimed surface mined watershed has a significant direct effect on the contributions to surface storm runoff from infiltration excess overland flow throughflow and return flow as rates of infiltration increase through time and slightly delayed macropore return flow increases the peak rate of surface storm runoff is reduced therefore reducing the potential for severe gully erosion on the reclaimed site in addition throughflow moves predominantly within the minesoil horizon and has limited contact with potentially acid producing backfill better understanding of the process of macropore flow in reclaimed minesoils will help investigators evaluate past strategies and develop new reclamation techniques that will optimize the long term effluent and ground water quality while minimizing the short term surface erosional effects of mining and reclamation

paleosols in the cretaceous goshoura and mifune groups sw japan and their paleoclimate implications abstract cretaceous sedimentary basins in kyushu island japan are developed as half grabens which accommodated very thick clastic wedges of non marine to shallow marine facies the albian to cenomanian goshoura group in western kyushu ca 1000 m thick consists of interbedded channel sandstone conglomerate and mudstone the cenomanian to turonian mifune group in central kyushu ca 2300 m thick comprises red and drab sandstone and intercalated siliceous ash fall tuff different types of paleosols occur in the goshoura and mifune groups paleosols in the goshoura group contain diagnostic vertic features such as subangular blocky peds irregularly directed slickensides and downward tapering fissures few obvious calcic horizons are developed except for the calcretes of rhizogenic origin paleosols in the upper formation of the mifune group are composed of cyclic acidic tuff vertic paleosol intervals with abundant pedogenic calcretes paleosols of the goshoura group belong to the order of vertic inceptisols and those of the mifune group can be classified as calcic vertisols in spite of diagenetic alteration of the paleosols paleo vertic soils of the goshoura and mifune groups show the exceptional preservation of a number of pedological features among various soil forming factors diversity in each paleosol is mainly attributed to differences in paleoclimatic conditions during the middle cretaceous our results show that the paleoclimatic conditions in the subtropical warm temperate region had changed from subhumid to semi arid with time

late quaternary sediment yield from the high arctic svalbard area late quaternary sediment yields from the isfjorden drainage area 7327 km 2 a high arctic region on svalbard characterized by an alpine landscape have been reconstructed by using seismic stratigraphy supported by sediment core analysis the sediments that accumulated in the fjord during and since deglaciation can be divided into three stratigraphic units the volumes of these units were determined and converted into sediment yield rates averaged over the drainage basin during deglaciation 13 to 10 ka the sediment yield was sim 860 tons t cdot km 2 cdot yr 1 in the early holocene it decreased to 190 t cdot km 2 cdot yr 1 and then increased to 390 t cdot km 2 cdot yr 1 during the late holocene little ice age when normalized to the approximate glacierized area these rates correspond to a sediment yield of sim 800 t cdot km 2 cdot yr 1 sediment yield from non glacierized parts of the drainage is estimated to be 35 t cdot km 2 cdot yr

total suspended particulate matter emissions at high friction velocities from desert landforms 1 most wind erosion studies that characterize dust emission potential measure particulate matter smaller than 10 mm pm10 for air quality purposes or atmospheric modeling because the pm10 size fraction is only a portion of the total range of fine grained particles potentially emitted from desert landforms we modified the miniature portable in situ wind erosion lab pi swerl by adding a new instrument to measure total suspended particulate matter tsp the modified pi swerl is capable of measuring tsp with diameters 500 mm emitted from highly erodible surfaces at friction velocities up to 1 28 m s 1 undisturbed and artificially disturbed surfaces of six common landforms in the negev desert of israel were studied to evaluate the utility of tsp measurements these landforms include alluvial fans and plains armored by desert pavements loessial soils with silt rich surficial crusts fluvial loess with biological crusts and active sand dunes the landforms differ in character and surface age thereby exhibiting a wide range of surface covers soil properties and soil strengths our results indicate that the magnitude of tsp emission is primarily controlled by geomorphic setting and surface characteristics tsp and pm10 concentrations measured from dust rich loessial soils were significantly correlated and tsp emission was best predicted at all sites using pm10 content and bearing capacity our results demonstrate that further research is needed to determine correction factors for friction velocities related to erodible anisotropic surface roughness elements and that the modified pi swerl is a promising tool to quantify total potential emission flux from desert landforms

bioclastic carbonate sediments on the southwestern svalbard shelf the poleward continuation of one of the largest known arctic carbonate factories the western spitsbergenbank of the barents sea has been surveyed along the narrow sw svalbard shelf on this shelf formation of cold water carbonate sediments occurs under glaciomarine environmental conditions mya truncata and hiatella arctica colonized a soft glacio marine diamicton 3000 6000 years after the final retreat of the icedome from the sw svalbard shelf since 2600 yr b p an increase of along shelf bottom currents washed out the fine terrigenous deposits leaving behind a shelly lag deposit and winnowed boulders on a morainic shelf topography the most favourable depth interval promoting the establishment of an amalgamated bioclastic blanket is located in 50 80 m water depth in this interval strong bottom currents prevent sedimentation thus facilitating colonisation of filter feeding benthic communities dominated by balanus balanus and chlamys islandica additional skeletal components are supplied by echinoderms bryozoans serpulids brachiopods and gastropods in shallower water depths carbonate production is hampered by intense iceberg scouring and release of ice rafted debris from the still glaciated hinterland of svalbard in deeper water 80 m olive grey muds with dispersed pebbles rich in benthic foraminiferans clinocardium ciliatum and taxodont bivalves are present on all surveyed shelf banks the deepest unit is a blue mud in water depths 120 m with benthic foraminiferans taxodont bivalves and sipunculids compared to spitsbergenbank carbonate production is much more restricted and impoverished on the sw svalbard shelf but is still an instructive modern example for the formation of skeletal carbonates resting on tillites in the geological record

size sorting in marine muds processes pitfalls and prospects for paleoflow speed proxies the basis for and use of fine grain size parameters for inference of paleoflow speeds is reviewed here the basis resides in data on deposited sediment taken in conjunction with flow speed measurements in the field experimental data on suspended sediment transport and deposition and theoretical treatments of the generation of size distributions of deposits from suspension controlled by particle settling velocity and flow speed in the deep sea sorting events occur under resuspension deposition events in benthic storms at flow speeds below 10 15 cm s 1 size in the noncohesive sortable silt 10 63 m range is controlled by selective deposition whereas above that range removal of finer material by winnowing also plays a role the best particle size instruments to measure a flow speed related grain size employ the settling velocity method while laser diffraction sizers can yield misleading results because of particle shape effects potential problems including source effects downslope supply on continental margins spatial variability of flow over bedforms and influence of ice rafted detritus are examined a number of studies using the sortable silt flow speed proxy are reviewed and inverse modeling of grain size distributions is examined outstanding problems are that corroboration is sparse because almost no studies have yet used the full range of proxies for flow rate and water mass identification and that the sortable silt mean size is not yet properly calibrated in terms of flow speed

minimal change in antarctic circumpolar current flow speed between the last glacial and holocene relatively little is known about the dynamics of the antarctic circumpolar current during the last glacial period estimates of current speeds over the past 20 000 years based on sediment grain size suggest that average flow speeds during the last glacial were comparable to modern speeds but not in the areas with overlying winter sea ice

lateritized tephric palaeosols from central patagonia argentina a southern high latitude archive of palaeogene global greenhouse conditions palaeosols of the koluel kaike formation a red colour banded pyroclastic succession from southern argentina constitute a proxy for eocene climate changes reticulated and vertically elongated ferric mottles along with iron and manganese nodules are the most significant climate indicators which originated by alternating cycles of waterlogging and drying conditions causing fe mn mobilization and fixation clay minerals vary from a kaolinite smectite suite in the lower and middle sections to a smectite kaolinite one in the upper part high concentrations of iron oxides hydroxides and kaolinite lack of exchangeable bases absence of carbonate cement presence of ironstone and redness of hue in most of the palaeosols suggest intense chemical weathering related to leaching and lateritization processes five pedotypes ordered in a stratigraphic sense were identified strongly developed red to orange chornk fragiaquult and kapenk plinthaquult pedotypes display argillic horizons abundant ferric nodules and slickensides they are dominant in the lower and middle sections and formed in seasonal humid and megathermic tropical conditions with a mean annual precipitation of 1200 to 1300 mm and a mean annual temperature of 15 c weakly developed less structured ornek vitrand and polnek placaquand pedotypes occur in the middle and upper sections and originated in sub humid and mesic megathermic conditions with a mean annual precipitation around 1000 mm and a mean annual temperature around 12 c the brownish soorsh argialboll pedotype exhibits a granular structure and is present at the uppermost part of the unit it developed in sub humid semi arid and mesic conditions with a mean annual precipitation of 600 to 700 mm and a mean annual temperature around 10 c this pedotype succession and clay mineral distribution indicates a decrease in chemical weathering and degree of soil development with time koluel kaike palaeosols from central patagonia are some of the first continental non palaeobiological data linked to the early palaeogene global warming in south america they show an especially close relationship with the early eocene climatic optimum and the following long term cooling and drying initiated by middle to late eocene time

collapse of the late triassic megamonsoon in western equatorial pangea present day american southwest during the late triassic western equatorial pangea in the present day american southwest was unusually humid as indicated by sedimentological evidence and inferred from general circulation models these studies show that once equatorial pangea was assembled cross equatorial summer air flow penetrated into western equatorial pangea bringing abundant megamonsoon rainfall and warm temperatures however many of these investigations indicate that gradual aridification began sometime during the late triassic to jurassic we show from field properties geochemical transfer functions and isotopic analysis of paleosols in the chinle formation of petrified forest national park arizona that the western equatorial pangea megamonsoon collapsed by 214 7 ma during the middle norian climate shift paleosols include entisols inceptisols vertisols aridisols and alfisols with transfer functions for mean annual precipitation chemical index of alteration minus potassium cia k and mean annual temperature nak salinization developed from analogous modern data sets the most notable shift is the appearance of carbonate enriched paleo inceptisols and paleo vertisols after 214 7 ma and paleo aridisols after 210 ma prior to the middle norian climate shift the region is classified as humid humidity province based on rainfall estimates initiation of the middle norian climate shift was characterized by an increase in paleosol carbonate content and rapidly declining rainfall as the region shifted to subhumid and eventually to semiarid and arid after 210 ma paleosol derived temperatures are indicative of warm temperate to subtropical ecozones whereas general circulation models show higher temperatures and tropical conditions perhaps because boundary conditions were set to atmospheric p co 2 4 5 present elevations of 1 5 2 km adjacent to the cordilleran magmatic arc complex located 400 km west of the study area may account for nontropical temperatures after 210 ma however temperatures began to increase possibly as a result of escalating atmospheric p co 2 from shale oxidation during marine regression and from coal and paleosol organic matter oxidation during prolonged aridification paleomagnetic studies have suggested northward continental drift of western equatorial pangea to outside of the intertropical convergence zone as the cause of monsoonal collapse during the late triassic to early jurassic the formation of a rain shadow as a result of the evolving cordilleran magmatic arc as the cause of aridification is supported by recent magnetostratigraphic work substantiating that the region remained in the tropics through the triassic according to our age model the middle norian climate shift is dated to near the same time as the manicouagan impact crater but there is no evidence of such an event in the study area either geochemically or sedimentologically at our scale of observation however a regionally defined faunal turnover may have been a response to rapidly changing climates in the region

morphology and distribution of fossil soils in the permo pennsylvanian wichita and bowie groups north central texas usa implications for western equatorial pangean palaeoclimate during icehouse greenhouse transition analysis of stacked permo pennsylvanian palaeosols from north central texas documents the influence of palaeolandscape position on pedogenesis in aggradational depositional settings palaeosols of the eastern shelf of the midland basin exhibit stratigraphic trends in the distribution of soil horizons structure rooting density clay mineralogy and colour that record long term changes in soil forming conditions driven by both local processes and regional climate palaeosols similar to modern histosols ultisols vertisols inceptisols and entisols all bearing morphological mineralogical and chemical characteristics consistent with a tropical humid climate represent the late pennsylvanian suite of palaeosol orders palaeosols similar to modern alfisols vertisols inceptisols aridisols and entisols preserve characteristics indicative of a drier and seasonal tropical climate throughout the lower permian strata the changes in palaeosol morphology are interpreted as being a result of an overall climatic trend from relatively humid and tropical moist conditions characterized by high rainfall in the late pennsylvanian to progressively drier semi arid to arid tropical climate characterized by seasonal rainfall in early permian time based on known late palaeozoic palaeogeography and current hypotheses for atmospheric circulation over western equatorial pangea the pennsylvanian palaeosols in this study may be recording a climate that is the result of an orographic control over regionalscale atmospheric circulation the trend towards a drier climate interpreted from the permian palaeosols may be recording the breakdown of this preexisting orographic effect and the onset of a monsoonal atmospheric circulation system over this region

a strand plain soil development sequence in northern michigan usa abstract a practical problem limiting the theoretical application of a soil chronosequence study lies in the difficulty of identifying an appropriate geomorphic age sequence with more than a few surfaces a sequence of approximately 75 strand plain beach ridges located along the northern shore of lake michigan usa overcomes this problem and was used to explore rates of soil development in the initial stages of podzolization well drained pedons were sampled on 24 of the ridges with an age range of 10 to 5200 years chronofunctions were developed using statistical regression techniques for most forms of extractable fe and al both linear and log linear functions adequately describe the changes in property with surface age dithionite citrate extractable fe content however shows little correlation with surface age high r 2 values 0 7 for chronofunctions representing most extractable sesquioxide forms suggest that b horizon sesquioxide content increases with surface age as expected for soils undergoing podzolization visual inspection of chronofunction data suggests that scatter increases on surfaces older than 3000 years possibly because soil spatial variability increases with surface age theory suggests that the log linear form of chronofunctions may be preferable to the linear form for these pedons in general equation slopes are steeper for chronofunctions representing only the initial 1650 years of soil development than for those representing the entire 5200 year sequence suggesting that initially rapid pedogenesis slows over time most chronofunctions for ph and weighted profile organic c are not statistically significant possibly because the temporal resolution of the chronosequence is too coarse to detect valid trends for properties that rapidly approach a steady state

pleistocene plateau ice fields in the high atlas morocco large ice fields 25 km2 formed over the tazaghart and iouzagner plateaux of the high atlas morocco during the late pleistocene the plateau ice fields were drained by large valley glaciers forming a series of moraine assemblages four moraine units have been mapped and subdivided on the basis of morphostratigraphy and the degree of soil weathering soil profile development index pdi values indicate that the moraine units are widely separated in time with the oldest moraines deeply weathered and degraded whereas soils are absent on the youngest moraines the highest moraine unit was formed by a small niche glacier which was present as recently as the mid 20th century pleistocene glaciers are likely to have been associated with wetter conditions than today in addition to colder air temperatures combined with ice in neighbouring areas such as the toubkal massif the sw high atlas supported some of the largest glaciers in africa during the pleistocene the extent of glaciation with ice exploiting and breaching drainage divides has major implications for landscape development the evolution of the high atlas is therefore strongly shaped by glaciation and this is closely intertwined with tectonic fluvial and slope processes

marine 14c reservoir ages for 19th century whales and molluscs from the north atlantic abstract in order to compare radiocarbon dates on marine and terrestrial samples the former have to be corrected for a reservoir age we present reservoir ages from dating 21 whales collected 1860 1901 and recalculating dates of 23 molluscs collected 1857 1926 most of the whales were caught along the coast of norway but one is from france and one from iceland we assume the former mainly lived in the north and equatorial atlantic and in the norwegian sea whales feed only on pelagic organisms and will provide the reservoir age for the open ocean surface water however they travel long distances and will integrate the reservoir ages of the different water masses along their way molluscs dated from norway spitsbergen and arctic canada are stationary and monitor the sea water passing their dwelling site but some also take up carbon from particulate food or sediment pore water coastal water also often contains some continental carbon we present two different views on how to analyze and interpret the data mangerud recommends to use reservoir ages based on a combination of the whale and mollusc dates i e 380 30 and 360 30 yr relative to intcal04 and british oak respectively and a r value of 20 30 for the surface water in the n atlantic and norwegian sea bondevik and gulliksen maintain that the reservoir age and r along the norwegian coast is latitude dependant with r values increasing from 3 22 in the south to 105 24 at spitsbergen whales reflecting north atlantic open ocean surface water have lower r 7 11 than most molluscs

lateglacial and early holocene climatic oscillations on the western svalbard margin european arctic abstract a multi proxy sediment core record on the continental margin off western svalbard european arctic reflects large climatic and oceanographic oscillations at the lateglacial early holocene transition based on studies of planktonic foraminifera their stable oxygen and carbon isotopic composition and ice rafted debris we have reconstructed the last 14 cal ka bp the period 14 13 5 cal ka bp was characterized by highly unstable climatic conditions short lived episodes of warming alternated with meltwater pulses and enhanced iceberg rafting this period correlates to a regional warming of the northern north atlantic an overall decrease in meltwater took place during the deglaciation 14 10 8 cal ka bp the late younger dryas and subsequent transition into the early holocene is characterized by a reduced flux of planktonic foraminifera and increased iceberg rafting a major warming took place from 10 8 to 9 7 cal ka bp the influence of meltwater ceased and the flux of warm atlantic water increased from 9 7 to 8 8 cal ka bp the western svalbard margin surface waters were significantly warmer than today this warm period the thermal maximum was followed by an abrupt cooling at 8 8 cal ka bp caused by an increased influence of arctic water from the arctic ocean the results document that the european arctic was very sensitive to climatic and oceanographic changes at the end of the last glacial and during the holocene

geomorphic expression of midcrustal extension in convergent orogens 1 channel orientation gradient drainage basin spacing drainage patterns and alluvial fan sedimentology define a set of geomorphic observables for fingerprinting modes of extensional tectonism in convergent settings anomalous finely textured trellis drainage patterns in the alps are spatially coincident with the low angle simplon and brenner detachments the detachment footwalls are characterized by numerous high angle brittle faults which are etched out by low order stream gullies and channels we quantify the relationship between these faults and watershed scale geomorphology using high resolution digital topography to extract channel and basin metrics topographic data are complemented by a field data set of channel gradients and the integrated erosional response of the watersheds preserved in valley bottom alluvial fans in footwall regions adjacent to the detachments channels are steeper more closely spaced have statistically coherent orientations and feed coarse steep alluvial fans drainage spacing increases in the footwall away from the detachment and the trellis pattern diminishes in the detachment hanging walls which typically lack high angle brittle faults there is a poor correlation between channel steepness density or orientation and hanging wall alluvial fans tend to be relatively larger gentler and debris flow dominated comparisons are made to the ticino dome region of the alps as well as to the pioneer core complex of central idaho in both cases our analysis suggests high angle brittle faulting of the footwall is particularly well preserved in the region adjacent to a detachment these results are consistent with a subvertical simple shear model for footwall extrusion as well as annealing or a lack of reactivation of brittle structures in the footwall distal to the rolling hinge

geogenesis pedogenesis and multiple causality in the formation of texture contrast soils abstract coarse over fine vertical texture contrasts vtc are common in soils and weathering profiles in a variety of environmental settings including many where inheritance or surficial processes alone cannot account for them a multiple causality model is presented here which shows that texture contrasts can form in response to a combination of ubiquitous phenomena there are six key elements downward translocation by water erosional winnowing soil mixing by bioturbation the tendency for surface clay additions to be mobilized while subsurface clays are more likely to remain in place and biological facilitation of moisture flux no element alone is sufficient to create a vtc but not all are necessary in any given regolith the model is illustrated by application to case studies in the ouachita mountains arkansas ridgetops in eastern kentucky the lower coastal plain of north carolina and the upper coastal plain of east texas the implications for interpretation of soils paleosols and weathering profiles is that the presence of a textural contrast by itself does not connote any particular set of geogenic or pedogenic processs or controls texture contrasts may be geogenic pedogenic or both given the widespread occurrence of the mechanisms of the multiple causality model vertical texture contrasts are inevitable

evaluating natural site formation processes in eolian dune sands a case study from the krmpotich folsom site killpecker dunes wyoming abstract eolian dune sands commonly contain archaeological material in both surface and buried contexts however because of the dynamic nature of dunes the original context of an archaeological site can be severely modified or destroyed as a result of post occupational geomorphic processes this paper examines a folsom occupation associated with a buried soil in the killpecker dunes in southwestern wyoming field and labortory data are compared to determine the likely scenario of natural site formation processes responsible for the current context of the archaeological assemblage two primary eolian stratigraphic units are present at the site and are separated by the buried artefact bearing soil radiocarbon and optical luminescence ages indicate that the folsom artefacts occur across a temporal hiatus and that the buried soil is late holocene in age sedimentological data indicate that the highest frequencies of artefacts by depth are associated with an erosional contact characterized by a concentration of coarse grained material thus the folsom assemblage appears to have been vertically displaced as a result of post occupational erosion and deflation this case study indicates that evaluating the context of an archaeological occupation in a dune setting is best carried out utilizing multiple lines of evidence derived from both field and laboratory work

holocene paleoceanography and glacial history of the west spitsbergen area euro arctic margin two sediment cores from the west spitsbergen area euro arctic margin md99 2304 and md99 2305 have been investigated for paleoceanographic proxies including benthic and planktonic foraminifera benthic foraminiferal stable isotopes and ice rafted debris core md99 2304 is located on the upper continental margin reflecting variations in the influx of atlantic water in the west spitsbergen current core md99 2305 is located in van mijenfjord picturing variations in tidewater glacier activity as well as fjordocean circulation changes surface water warmer than today was present on the margin as soon as the van mijenfjord was deglaciated by 11 200 cal years bp relatively warm water invaded the fjord bottom almost immediately after the deglaciation a relatively warm early holocene was followedby an abrupt cooling at 8800 cal years bp on the continental margin another cooling in the fjord record 8000 4000 cal years bp is documented by an increase in ice rafted debris and an increase in benthic foraminiferal d 18 o the ird record indicates that central spitsbergen never was completely deglaciated during the holocene relatively cool andstable cond itions similar to the present were establishedabout 4000 cal years bp

heavy minerals in the 2011 tohoku oki tsunami deposits insights into sediment sources and hydrodynamics abstract the 2011 tohoku oki tsunami left sand and mud deposits more than 4 km inland on the coastal plain of sendai japan the tsunami deposits pre tsunami soils and beach sediments were analysed for grain size and heavy mineral content and assemblages to test the applicability of heavy mineral analyses in the identification of tsunami deposits and interpretation of associated sedimentation processes heavy minerals comprised on average 35 of the tsunami deposit in the 0 125 0 25 mm grain size fraction the most common were orthopyroxenes clinopyroxenes amphiboles limonites and opaque minerals heavy mineral concentrations and assemblages were similar in the tsunami deposits beach and pre tsunami soils and sediments and thus tsunami deposits could not simply be identified based on their heavy minerals sediment provenance analysis revealed that tsunami deposits left within 1 5 km of the shoreline were mostly eroded from the beach dune and local soils while deposits farther inland 1 5 km were mostly derived from local soil erosion no evidence was found for a significant contribution of offshore sediments detailed analyses revealed that the lowermost portion of tsunami deposits was mostly of local origin while the sediment source of the upper portion was variable a comparison with a previous study of heavy minerals in 2004 iot deposits confirms that heavy minerals in tsunami deposits are mostly source dependent and may represent a useful supplementary tool in studies of tsunami deposits however the interpretation must always be placed in the local geological context and corroborated with other tsunami proxies

comparison of modern and ancient vertisols developed on limestone in terms of their geochemistry and parent material identification of paleosol parent material can be difficult a common simplistic assumption is that nonpedogenic strata directly beneath paleosols are representative of the parent material field relationships petrography and geochemical massbalance were used to test the simple hypothesis that the parent material of both an early carboniferous late mississippian vertic vertisol like paleosol and a modern analog soil vertisol was immediately subjacent marine carbonate rock an alternative hypothesis also tested was that the paleosol formed primarily from siliciclastic sediment deposited on top of the carbonate the modern ancient analog comparison is valid because both the paleosol and the modern soil have high clay contents extensive shrink swell features and rest directly on top of marine carbonate substrates field and thin section observations indicate minor assimilation of marine carbonate into both the paleosol and soil matrices mass balance of both the paleosol and soil calculated assuming that the subjacent carbonate was the parent material and that ti was immobile during weathering indicated 25 75 net volume loss during weathering and 25 99 net losses of many alkali alkaline earth and redox sensitive elements however calculations based on an alternative hypothesis of clayshale parent material for the paleosol indicated only 10 25 volume loss and lower translocation losses for weathering of this material the insoluble residue content of the dolostone would require that a fourfold volume reduction during weathering occurred if the dolostone were the only parent material if the paleosol formed from clayshale then significantly less volume loss characterised weathering these results collectively illustrate that the simplest interpretation of paleosol parent material may not always be correct and that paleosols can be derived from weathering of more than one parent material d 2002 elsevier science b v all rights reserved

the role of mining and agricultural activity in creating coexisting but divergent soils san luis valley colorado usa abstract application of irrigation water especially through flood or furrow methods can have profound impacts on soil morphological chemical and physical properties using a variety of field and laboratory techniques we examined the impact of both acidic and alkaline irrigation water on a host of soil properties in the san luis valley of southern colorado impacts on calcium carbonate clay content and gypsum to a depth of 1 m are presented for 4 sites a control two sites exposed to acidic irrigation water and one site exposed to alkaline irrigation water along with the increased water in this arid ecosystem water quality and sediment content have likely contributed to the pedologic changes observed in this system one of the most prominent changes is the removal of carbonate within the upper meter of soil at the site with the greatest exposure to acidic irrigation water changes in soil structure and color differences in clay mineralogy and rock fragment weathering and the presence of jarosite provide further evidence of accelerated weathering along this management gradient the sum of these changes has resulted in a shift in the soil classification and has potential implications on buffering capacity and soil productivity

geochemical and c o sr and u series isotopic evidence for the meteoric origin of calcrete at solitario wash crater flat nevada usa calcite rich soils calcrete in alluvium and colluvium at solitario wash crater flat nevada usa contain pedogenic calcite and opaline silica similar to soils present elsewhere in the semi arid southwestern united states nevertheless a ground water discharge origin for the solitario wash soil deposits was proposed in a series of publications proposing elevation dependent variations of carbon and oxygen isotopes in calcrete samples discharge of ground water in the past would raise the possibility of future flooding in the unsaturated zone at yucca mountain nevada site of a proposed high level nuclear waste repository new geochemical and carbon oxygen strontium and uranium series isotopic data disprove the presence of systematic elevation isotopic composition relations which are the main justification given for a proposed ground water discharge origin of the calcrete deposits at solitario wash values of 13c 4 1 to 7 8 per mil 18o 23 8 17 2 87sr 86sr 0 71270 0 71146 and initial 234u 238u activity ratios of about 1 6 in the new calcrete samples are within ranges previously observed in pedogenic carbonate deposits at yucca mountain and are incompatible with a ground water origin for the calcrete variations in carbon and oxygen isotopes in solitario wash calcrete likely are caused by pedogenic deposition from meteoric water under varying quaternary climatic conditions over hundreds of thousands of years

new correlation of stable carbon isotopes with changing late holocene fluvial environments in the trinity river basin of texas usa a late holocene alluvial sequence in north central texas has a 1 m thick buried cumulic soil with an a c profile called the west fork paleosol it formed 2300 to 1000 yr bp and is a local equivalent of the copan paleosol that is present throughout the southern us great plains stable carbon isotopes indicate that the paleosol and underlying gray clay formed under vegetation dominated by c4 species mean 13c 18 3 0 3 diverse paleoenvironmental studies indicate that the period of paleosol formation was cool and wet and that alluvial water tables were high resulting in broad wet meadows across alluvial valleys characterized by communities of grasses present day wet meadows and bottomlands with mollisols with a c profiles along streams in the great plains are dominated by c4 tallgrass species and may serve as analogues to wet meadow environments during the late holocene a shift in climate to warm dry conditions about 1000 yr bp was accompanied by deep channel cutting low alluvial water tables an

halloysite as a kinetically controlled end product of arid zone basalt weathering abstract mineralogical and isotope results paired with field observations suggest that halloysite is the favored albeit metastable aluminosilicate end product of arid zone basalt weathering on kohala hawai i and that the formation of smectite has been inhibited by kinetic factors soils sampled on constructional lava flows having ages ranging from 4 to 350 ka provide a chronosequence that has had minimal physical disturbance thus allowing us to interpret chemical and mineralogical changes as the result of a time dependent process the halloysite content of the soil increases with increasing soil age its growth is at the expense of allophane which in turn forms at the expense of primary minerals these mineral relationships suggest that halloysite has been forming continuously throughout the lifetime of the soil smectite the thermodynamically stable phyllosilicate phase predicted by soil solution composition is not found in these arid soils we determined that our soil system is controlled by kinetic factors and that therefore thermodynamic predictions do not reflect reality the main factors favoring kinetic control of halloysite formation are intense but short wet periods followed by prolonged extremely dry seasons and microenvironmental conditions leading to immediate uptake of released al by the halloysite precursor mineral allophane the 18o relationship between present day soil water and halloysite formed over the last 170 ka was used as a tracer of past soil conditions results from a reconstruction of paleo climate and soil conditions combined with 18o data observed mineral relationships along the 350 ka chronosequence and field evidence for long term aridity rule out the possibility that the arid side of kohala was affected by prolonged periods of higher rainfall that could have produced more dilute soil waters and therefore altered mineralogical stabilities we conclude that pedogenic halloysite has been continually forming from the early stage of soil formation and that it has consistently formed under isotopic equilibrium conditions indicating that halloysite 18o compositions imply paleoclimatic conditions over the time of its formation that are similar to today s

the growth and decay of the late weichselian ice sheet in western svalbard and adjacent areas based on provenance studies of marine sediments the history of the late weichselian northwestern barents shelf including western svalbard has been investigated by provenance sedimentologist studies of five cores from the continental shelf and slope west of svalbard the chronostratigraphy of the cores is based on ams 14c dates and oxygen isotope analyses interpretations of the cores suggest that the ice sheets of western svalbard and northwestern barents sea experienced advances and retreats in two steps the first significant ice advance beyond the present coastline occurred ca 22 000 14c yr b p and was followed by an ice advance to the shelf edge ca 18 000 14c yr b p ice recession from the outer shelf and the southwestern barents sea began 14 800 14c yr b p and was followed by a second ice recession between 13 000 and 12 000 14 c yr b p during which ice withdrew from the inner shelf a minor readvance of the ice sheet on the shelf west of svalbard occurred close to 12 400 14c yr b p the first deglaciation event was associated with release of icebergs containing ice rafted detritus while the later episode also included significant amounts of meltwater and fine grained sediment

comparison of soil thickness in a zero order basin in the oregon coast range using a soil probe and electrical resistivity tomography abstractaccurate estimation of the soil thickness distribution in steepland drainage basins is essential for understanding ecosystem and subsurface response to infiltration one important aspect of this characterization is assessing the heavy and antecedent rainfall conditions that lead to shallow landsliding in this paper we investigate the direct current dc resistivity method as a tool for quickly estimating soil thickness over a steep 33 40 zero order basin in the oregon coast range a landslide prone region point measurements throughout the basin showed bedrock depths between 0 55 and 3 2 m resistivity of soil and bedrock samples collected from the site was measured for degrees of saturation between 40 and 92 resistivity of the soil was typically higher than that of the bedrock for degrees of saturation lower than 70 results from the laboratory measurements and point depth measurements were used in a numerical model to evaluate the resistivity contrast at the soil bedrock interface a dec

holocene tectono geomorphic evolution of parts of the upper and middle gangetic plains india abstract using multispectral scanning mss images and digital elevation models dems 26 terrain morphological units were delineated in the study area between the rapti and kosi rivers in the gangetic plains based on the degree of soil development and the infrared stimulated luminescence chronology these terrain morphological units have been grouped into six members of a morphostratigraphic sequence with ages 1 65 1 65 5 3 5 3 7 5 7 5 8 5 8 5 10 and 10 ka integrated use of geomorphic markers including different drainage patterns identified from mss images significant breaks in topographic profiles terminal fans and artifact terrain features e g cliffs and significant breaks in slopes in dems digital terrain models dtms with highly exaggerated vertical dimensions were made to infer and map 20 nascent faults in the region between the ghaghara and kosi rivers in the flat gangetic plains the three major tectonic blocks are the upland ghaghara rapti block of the upper gangetic plain and the rapti gandak and gandak kosi blocks of the middle gangetic plain marked by high rates of subsidence and sedimentation the ghaghara rapti block bounded by the incised ghaghara and rapti rivers is an upland region and is primarily overlain by 10 ka old soils subsequent activity along the ne sw trending transverse normal faults led to deposition of young terminal fans southward tilt of the ghaghara rapti block generated two e w trending terraces on the left bank of the ghaghara river southwestward tilting of the upper part of the ghaghara rapti block led to development of the widest old ghaghara plain and rapti floodplain in the sw direction northeastward tilting of the rapti gandak block shifted the gandak river from west to east over a distance of 80 km during the period from 10 to 8 5 ka further compression from the sw caused development of four extensional normal faults the activity of three faults between 5 7 and 1 0 ka generated four terminal alluvial fans on this block the gandak kosi block is marked by a set of seven thrust splays off the himalayan frontal thrust hft in the footwall activity of these thrust splays in the foothill region caused progradation of the gravel piedmont and thus developed the widest piedmont zone 124 km in the gangetic plains this is the first report of gravel piedmont progradation from a modern environment and role of thrust splays in such a progradation in the southernmost part of this block the continuous occurrence of terminal fans over a length of 140 km south of the south muzaffarpur fault forms a terminal fan piedmont bajada orientation of the faults was used to interpret compression from the sw in the ghaghara rapti interfluve plain in the west since 10 ka and compression from the south in the gandak kosi interfan region in the east after 4 5 ka the rapti gandak region in the central part shows the effects of mainly compression from the sw and compression from the south at different times in addition to terminal fans formed because of low relief terrain features created by the activity of faults by involvement of the entire discharge of small meandering braided streams a new type of fan formed by splays from a large river on the downthrown sides of faults called splay terminal fans is observed from the rapti gandak block

arctic planktic foraminiferal assemblages implications for subsurface temperature reconstructions abstract earlier reconstructions of the inflow of atlantic water to arctic and subarctic oceans based on foraminiferal proxy data have been obstructed by uncertain quantitative reconstructions of sea surface and subsurface temperatures in this study surface sediment samples with undisturbed sediment water interface from polar north atlantic and barents sea were retrieved and prepared at the size fractions from 100 m to 1000 m the foraminiferal analyses show that neogloboquadrina pachyderma constitutes 96 99 of the fauna in arctic and polar surface water masses the same result is obtained when investigating the 150 m size fraction however in arctic areas influenced by atlantic water additional faunal information is obtained when using the smaller 100 m size fraction in these areas n pachyderma is reduced to about 50 and the relatively small species turborotalita quinqueloba becomes very frequent this also applies to the coastal water masses which are dominated by neogloboquadrina incompta and globigerinita uvula transfer functions using the current dataset based on the 100 m size fraction were developed and assessed different statistical models were tested using both seasonal and annual temperature data from 0 m 10 m 50 m and 100 m water depth the most precise reconstructions of subsurface temperatures were found when using summer temperatures from the 100 m depth level the transfer function was tested on holocene foraminiferal records and compared to previous reconstructions the results show that our new transfer function based on the 100 m fraction generally yields lower temperatures at both 10 and 100 m water depth than earlier reconstructions e g hald et al 2007 this could be due to the increased number of samples containing both small species and or the presence of more small specimens representing cold conditions

the influence of slope aspect on soil weathering processes in the springerville volcanic field arizona abstract a comparison was made between soils on north and south facing slopes of six cinder cones in the springerville volcanic field svf arizona in order to determine the influence of slope aspect on soil weathering processes twenty four soil pedons were sampled on different aspects of six cinder cones to control for the influence of slope on pedogenesis all sample sites possessed slopes of 17 2 soil weathering processes were characterized by solum depth texture and ca zr chemical weathering indices quartz and mica were used to identify eolian additions to the volcanic soils accelerated rates of weathering and soil development were found to occur in soils on south facing slopes while no trend with aspect was found for eolian additions accelerated rates of weathering and soil development may influence cinder cone degradation and cone morphology

meteoric be 10 from sirius group suggests high elevation mcmurdo dry valleys permanently frozen since 6 ma abstract a long standing debate concerning neogene antarctic climate in the mcmurdo dry valleys relies largely on evidence from landscape evolution glacial modeling and stratigraphy we provide new evidence from meteoric 10 be for the onset of frozen hyper arid conditions on a high elevation 1840 m interfluve at table mountain a simple decay model for the co occurrence of meteoric 10 be and illuviated clay in cores of ice cemented glacial sediments indicates that the clays were actively migrating down from the surface in a warm climate until the system froze between 6 and 9 ma although this age range may be sensitive to possible interference by in situ produced 10 be the implied minimum age of 6 ma for the sirius group indicates that the dry valleys were permanently frozen down to this elevation at this time the model also suggests denudation rates of 1 6 cm myr 1 since freezing these data provide an independent test of glacial stratigraphic evidence used to determine antarctic paleoclimate

holocene periodicity in north atlantic climate and deep ocean flow south of iceland climate fluctuations during the past millennium are relatively well documented1 on a longer timescale there is growing evidence of millennial scale variability of holocene climate at periodicities of 2 500 and 950 years possibly caused by changes in solar flux 2 3 and 1 500 years maybe related to an internal oscillation of the climate system 4 5 6 but the involvement of deep water masses in these holocene climate changes has yet to be established here we use sediment grain size data from the iceland basin to reconstruct past changes in the speed of deep water flow the study site is under the influence of iceland scotland overflow water isow the flow of which is an important component of the thermohaline circulation that modulates european climate flow changes coincide with some known climate events the little ice age and the mediaeval warm period and extend over the entire holocene epoch with aquasi periodicity of 1 500 years the grain size data indicate afaster isow flow when the climate of northern europe is warmer however a second mode of operation is observed in the early holocene when warm climate intervals are associated with slower isow flow at that time the melting remnant of land based glacial age ice may have provided a sufficient source of fresh water to the ocean to reduce isow flow south of iceland

oceanic and atmospheric variations during the last deglaciation in the fram strait arctic ocean a coupled high resolution organic geochemical and sedimentological study abstract from a high sedimentation rate core obtained from the yermak slope arctic ocean we deduced short term climatic fluctuations of the last deglaciation lasting from 17 000 to 9000 years bp by using a coupled organic geochemical and sedimentological approach we reconstructed near bottom current conditions and assessed their significance in relation with comparable global thermohaline circulation patterns and surface water conditions highest concentrations and fluctuations of specific marine phytoplankton biomarkers were obtained in the bolling allerod when the major deglaciation of the svalbard barents sea ice sheet sbis occurred the marine biomarker record and the sedimentological record are consistent with climate reconstructions obtained from greenland ice cores and thermohaline circulation variations however beginning with the younger dryas yd episode bottom currents decreased during this time period but surface waters remained very productive the atmospheric conditions of the western fram strait reconstructed from biomarker data and thermohaline circulation signals reconstructed from sedimentological data were decoupled in the yd maximum insolation values of solar radiation and fohn like winds enabled open water conditions and increased productivity values in the northern fram strait at least in summer

on the origin and age of the great sand dunes colorado abstract over the past 100 yr several hypotheses have been proposed for the origin and age of the great sand dunes these hypotheses differ widely in the descriptions of dune morphometry the immediate source of eolian sand and when sand transport occurred the primary purpose of this paper is to evaluate these hypotheses and where warranted to present new ideas about the origin and age of the great sand dunes to evaluate the previous hypotheses we had to develop more detailed information about the surficial geology of the northern san luis valley thus we mapped the surficial geology of an area extending several tens of kilometers north south and west of the great sand dunes and examined subsurface stratigraphy in more than 200 wells and borings in addition we used relative dating criteria and several radiocarbon and osl ages to establish the chronology of surficial deposits and we determined the u pb ages of detrital zircons to obtain information about the sources of the sand in the great sand dunes the first principal finding of this study is that the lower part of the closed basin north of the rio grande referred to here as the sump is the immediate source of the sand in the great sand dunes rather than the late pleistocene flood plain of the rio grande the most widely accepted hypothesis a second principal finding is that the great sand dunes are older than late pleistocene they postdate the draining of lake alamosa which began 440 ka and predate the time when streams draining the west flank of the sangre de cristo mountains were deflected by incipient dunes that formed near the mountain front geomorphic and stratigraphic evidence indicate that this deflection occurred prior to the end of the next to last glaciation bull lake i e prior to 130 ka

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

the preboreal oscillation around the nordic seas terrestrial and lacustrine responses the occurrence of an early preboreal climatic cooling oscillation pbo in lacustrine and glacial records from northwest europe iceland and greenland is reviewed and documented the often subtle response of the proxy records to this oscillation in combination with its short duration make it difficult to detect owing to its chronostratigraphic position between the 10 000 9900 and 9600 9500 14 c plateaux c 11 300 11 150 calendar yr bp it is also difficult to 14 c date with precision we find that the vegetation response to the pbo varies between sites and regions in contrast to the pioneer vegetation in iceland and southern sweden the expanding birch pine forest in germany denmark was more susceptible to deteriorating growing conditions the combined lacustrine tree ring and glacial records imply that the pbo was characterised by cool and humid conditions throughout northwestern and central europe this is documented by vegetation changes decreased aquatic production increased soil erosion increased 2 h and 13 c content in tree rings readvances or stillstands of the ice sheet in norway and finland and ingression of brackish water into the baltic icelandic proxy records from lake sediments and glacial moraines imply cooler conditions than during the previous preboreal period but not as extreme as during the younger dryas greenland records suggest that the early preboreal was characterised by ice readvances as an effect of cool climate and increased precipitation in relation to the younger dryas it was not until the end of the pbo that climate was warm enough to melt the land based ice sheet this preboreal oscillation found on both sides of the nordic seas is interpreted as an effect of increased freshwater forcing on the thermohaline circulation in the nordic seas which is implied by a simultaneous and distinct rise in the atmospheric 14 c 12 c ratio a slow down of the thermohaline circulation may tempor arily have pushed the polar front further south 1997 by john wiley sons ltd preboreal oscillation thermohaline circulation lacustrine records glacial records chronology

the last glacial maximum on spitsbergen svalbard most scientists have concluded previously that the west coast of spitsbergen svalbard remained ice free during the late weichselian between 25 000 and 10 000 yr b p we conclude that the glaciation was more extensive terraces that were postulated to have been ice free are covered by a thin late weichselian till sudden drop in the marine limit and basal radiocarbon dates of raised glaciomarine sediments demonstrates that the glaciers in the main fjords isfjorden and van mijenfjorden terminated west outside of the fjord mouths basal radiocarbon dates from glaciomarine clay above till in cores from the continental shelf west of spitsbergen yielded ages of about 12 500 yr b p from which we conclude that the ice extended to the shelf edge based on the extent of amino acid diagenesis in radiocarbon dated molluscs the duration of the maximum extension of the late weichselian glaciation was short certainly less than 10 000 years during the ice free period preceding that glaciation at least back to 40 000 yr b p the glaciers on svalbard were not significantly larger than at present as shown by marine deposits close to the glacier snouts many radiocarbon dates place deglaciation of the outer coast at about 12 500 yr b p at about 10 000 yr b p the rest of the archipelago rapidly became ice free

the 8200 cal yr bp event reflected in the arctic fjord van mijenfjorden svalbard detailed stratigraphic investigations of a high resolution sediment core from the arctic fjord van mijenfjorden svalbard reveal significant reductions in benthic foraminiferal 18o of 0 4 and 0 2 0 3 dated to c 8200 and 8450 cal yr bp respectively these reductions combined with changes in the benthic foraminiferal fauna and ird indicate substantial changes in the hydrography of the fjord such as freshening of the bottom water enhanced sea ice distribution and reduced biogenic production the age and duration 100 years of the youngest event is directly in phase with the 8200 cal yr anomaly in the 18o record gisp2 and ngrip of the greenland ice sheet the changes around 8450 cal yr bp compare well to the timing of the initial freshwater drainage of the proglacial lake agassiz therefore the proxy record of van mijenfjorden lends support to the theory explaining the 8200 cal yr bp event as a cumulative response to a freshwater forced reduction in the meridional overturning circulation in

weathering release rates of base cations from soils within a boreal forested catchment variation and comparison to deposition litterfall and leaching fluxes long term 10 200 years average annual weathering rates mass losses of base cations ca mg and k for ten podzolic soil profiles in a remote forested catchment in eastern finland were determined using the zr depletion method three of the profiles were developed in sorted glaciofluvial parent material sand overlying till and seven developed in stony till parent material the aims were to determine the variation in base cation weathering rates within the catchment to determine if weathering rates differed between the two types of parent material and to compare the weathering rates with other ecosystem fluxes of base cations namely total deposition td litterfall lf and soil leaching 40 cm soil and parent material were sampled to a depth of 3 5 m and total elemental concentrations in the 2 mm fraction determined using xrf annual mean 1989 1997 td lf and leaching fluxes have been determined at two of the plots as part of long term ecosystem monitoring programmes there was no significant p 0 05 difference in ca mg k weathering rates between the two deposit types with rates averaging 15 3 and 14 9 mmolc m 2 year 1 for glaciofluvial sand and till profiles respectively the coefficient of variation in ca mg k weathering rates across all ten profiles was 31 the weathering rates were similar in size to the lf and leaching fluxes of base cations and were also sufficient to neutralize the td load of so4 2 acidity our results indicate that soil weathering is an important source of base cations and essential to the sustainability of site productivity of boreal catchments receiving low deposition loads even when having soil parent material dominated by acidic silicate minerals

postglacial variability in near bottom current speed on the continental shelf off south west spitsbergen this study documents changes in the sedimentary environment on the outer continental shelf off south west spitsbergen during the last 14 000 cal a bp using sedimentological mineralogical and geochemical data from a sea bed sediment core we use the sortable silt fraction to infer fluctuations of near bottom current speed and determine sediment provenance and sediment transport paths for most of the record length sediments were derived from distal sources by the west spitsbergen current wsc and the east spitsbergen current esc however before 12 000 and after 1800 cal a bp sediments were also sourced from proximal sources in south west spitsbergen the slowest near bottom currents were recorded between 10 300 and 9700 cal a bp when an increase in water stratification occurred probably due to the strengthening of the esc and an associated reduction in the northward water and heat flux near bottom currents related to wsc activity were at their maximum between 9000 and 7500 cal a bp i e during a period of elevated water temperature probably resulting in maximum relative heat fluxes to the arctic

cosmogenic nuclide and uranium series dating of old high shorelines in the western great basin usa closed basin pluvial lakes are sensitive recorders of effective moisture and they provide a terrestrial signal of climate change that can be compared to marine and ice records of glacial interglacial cycles although the most recent deep lake cycle in the western great basin at ca 16 ka has been studied intensively comparatively little is known about the longer term quaternary lacustrine history of the region lacustrine features higher than those of the most recent highstand have been discovered in many locations throughout the western great basin qualitative geomorphic and soil studies of shoreline sequences above the latest pleistocene level suggest that their ages increase as a function of increasing altitude the results of cosmogenic nuclide dating using chlorine 36 depth profiles from three sites in nevada walker lake columbus salt marsh and newark valley combined with uranium series and radiocarbon ages corroborate the geomorphic and soil evidence the 36 cl results are consistent with available 14 c ages and together indicate that the most recent highstands of all three lakes occurred ca 20 15 ka late in marine isotope stage mis 2 as shown by previous ages the 36 cl ages indicate that older lakes in all three basins reached highstands between 100 and 50 ka and most likely during mis 4 shorelines of this age are at about the same or higher altitudes as the younger mis 2 shorelines in those basins the 36 cl results combined with uranium series ages and one tephra correlation obtained on shorelines higher in altitude than those of mis 4 and 2 lakes suggest that there were also major lake highstands in the western great basin at ca 100 200 ka likely corresponding with mis 6 and during at least two older periods from these results we conclude that the preserved shorelines show an apparent decrease in maximum levels with time suggesting long term drying of the region since the early middle pleistocene

paleo critical zones windows into the changing life and landscapes during the quaternary period the critical zone cz as visualized in 1998 was a way to integrate the research of the four scientific spheres lithosphere hydrosphere biosphere and atmosphere at the surface of earth and to study the linkages feedbacks and record of processes rather than closeting studies by a variety of disciplines into their respective pigeonholes the cz perspective provides the symbiotic framework from which the tendrils of improved understanding can radiate outward to new disciplines and or feedback into the component disciplines during the last 2 decades cz research has been limited to the modern environment knowledge gained from the modern and the focus on interpreting ancient records allows for the development of paleo czs pczs pczs provide a powerful tool for improved understanding of the landscapes during the quaternary period and the response of this thin skin to glaciations sea level fluctuations and evolving life case studies from hominins in east africa and homo sapiens in the americas provide examples of the rich records stored in pczs as we move into the space age the cz can provide a platform from which to guide future exploration of the proto critical zones on the rocky planets and asteroids of our solar system

sediment accumulation rates in subpolar fjords impact of post little ice age glaciers retreat billefjorden svalbard abstract the little ice age 1600 1900 ad and 20th century sediment accumulation rates in billefjorden a subpolar fjord on svalbard were reconstructed by applying 210 pb 137 cs and ams 14 c datings the modern sediment accumulation rate decreases from more than 0 39 cm y 1 at the fjord head to 0 08 cm y 1 close to the fjord mouth however during the little ice age the sediments accumulated at a much lower rate of 0 02 cm y 1 in the central fjord basin this difference is most likely related to the rapid retreat of glaciers during the 20th century when most of them withdrew up to 2 km the post little ice age increases in temperature and a negative glacier mass balance resulted in a larger meltwater discharge transferring substantial amounts of sediments released from the glaciers as well as those eroded from previously stored unconsolidated glacial sediments a comparison of data from the subpolar fjords of svalbard suggests that the increase in the sediment accumulation rate is a common trend and further increases might be expected if climate warming continues the properties of the fjord sediments grain size ird coarse fraction composition clay mineralogy from the little ice age and the 20th century showed no distinct differences the change in the accumulation rate may be the most evident sedimentary record of this climatic change

climate induced sediment palaeosol cycles in a late cretaceous dry aeolian sand sheet marilia formation north west bauru basin brazil aeolian sand sheets which are characterized by low relief surfaces that lack dunes are common in arid and semi arid climatic settings the surface of an aeolian sand sheet can either be stable and subject to pedogenetic effects or unstable such that it is affected by deflation or sedimentation the maro lia formation late cretaceous may be interpreted as an ancient aeolian sand sheet area where alternating phases of stability and instability of the accumulation surface have been recorded detailed field studies were carried out in several sections of the maro lia formation where cyclic alternations of palaeosols and aeolian deposits were evident using palaeopedological and facies analysis methods supported in the laboratory by the analysis of rock samples cut and polished in slabs thin sections scanning electron microscope images and x ray diffraction data from the clay minerals the deposits comprise three lithofacies that in order of abundance are characterized by i translatent wind ripple strata ii flood deposits and iii ephemeral river channel deposits palaeosols constitute on average 65 of the vertical succession three types of palaeosols pedotypes are recognized i aridisols ii entisols and iii vertisols erosional surfaces due to aeolian deflation divide the top of the palaeosol profiles from the overlying aeolian deposits the palaeoenvironmental interpretation of the deposits and the palaeosols allows the depositional system of the maro lia formation to be defined as a flat area dominated by aeolian sedimentation with subordinate ephemeral river sedimentation and characterized by a dry climatic setting with occasional rainfall the climate is the main forcing factor controlling the alternation between episodes of active sedimentation and periods of palaeosol development a climate controlled model is proposed in which i the palaeosols are indicative of a stable surface that is developed during the more humid climatic phases and ii the erosional surfaces and the overlying aeolian sediments attest to periods of deflation and subsequent sedimentation thereby increasing the availability of sediment during the drier climatic phases the ephemeral fluvial deposits mark the more humid climatic conditions and contribute to the lagged sediment influx caused during the drier periods by the erosion of previously stored sediment

clay mineral distribution in surface sediments of the south atlantic sources transport and relation to oceanography abstract surface samples mostly from abyssal sediments of the south atlantic from parts of the equatorial atlantic and of the antarctic ocean were investigated for clay content and clay mineral composition maps of relative clay mineral content were compiled which improve previous maps by showing more details especially at high latitudes large scale relations regarding the origin and transport paths of detrital clay are revealed high smectite concentrations are observed in abyssal regions primarily derived from southernmost south america and from minor sources in southwest africa near submarine volcanoes of the antarctic ocean south sandwich bouvet island smectite contents exhibit distinct maxima which is ascribed to the weathering of altered basalts and volcanic glasses the illite distribution can be subdivided into five major zones including two maxima revealing both south african and antarctic sources a particularly high amount of mg and fe rich illites are observed close to east antarctica they are derived from biotite bearing crystalline rocks and transported to the west by the east antarctic coastal current chiorite and well crystallized dioctaedral illite are typical minerals enriched within the subantarctic and polarfrontal zone but of minor importance off east antarctica kaolinite dominates the clay mineral assemblage at low latitudes where the continental source rocks west africa brazil are mainly affected by intensive chemical weathering surprisingly a slight increase of kaolinite is observed in the enderby basin and near the filchner ronne ice shelf the investigated area can be subdivided into ten large scale clay facies zones with characteristic possible source regions and transport paths clay mineral assemblages of the largest part of the south atlantic especially of the western basins are dominated by chlorite and illite derived from the antarctic peninsula and southernmost south america and supported by advection within the circumantarctic deep water flow in contrast the east antarctic provinces are relatively small assemblages of the eastern basins north of 30 s are strongly influenced by african sources controlled by weathering regimes on land and by a complex interaction of wind river and deep ocean transport the strong gradient in clay mineral composition at the brazilian slope indicate a relatively low contribution of tropically derived assemblages to the western basins

concepts of sediment deposition and accumulation applied to the continental shelf near the mouth of the yangtze river a fundamental understanding of how sedimentary strata form requires distinction between deposition and accumulation of particles deposition refers to the temporary emplacement of particles on the seabed accumulation is the net sum of many episodes of sediment deposition and removal the difference between rates of deposition and accumulation affects the ability of an environment to record sedimentary events radionuclide profiles of 234 th and 210 pb within the seabed can be used to determine 100 day deposition rates and 100 yr accumulation rates respectively on the continental shelf near the mouth of the yangtze river short term deposition rates are about 4 4 cm month whereas accumulation rates integrated over a century are an order of magnitude less about 5 4 cm yr

ca cycling and isotopic fluxes in forested ecosystems in hawaii 1 biogeochemical processes fractionate ca isotopes in plants and soils along a 4 million year developmental sequence in the hawaiian islands we observed that plants preferentially take up 40ca relative to 44ca and that biological fractionation and changes in the relative contributions from volcanic and marine sources produce a significant increase in 44ca in soil exchangeable pools our results imply moderate fluxes enriched in 44ca from strongly nutrient depleted old soils in contrast with high 40ca fluxes in young and little weathered environments in addition biological fractionation controls divergent geochemical pathways of ca and sr in the plant soil system while ca depletes progressively with increasing soil age sr ca ratios increase systematically sr isotope ratios provide a valuable tracer for provenance studies of alkaline earth elements in forested ecosystems but its usefulness is limited when deciphering biogeochemical processes involved in the terrestrial ca cycle ca isotopes in combination with sr ca ratios reveal more complex processes involved in the biogeochemistry of ca and sr

arctic warming through the fram strait oceanic heat transport from 3 years of measurements we present estimates of volume and heat transport through fram strait for the period 1997 to 2000 from data of moored instruments full depth volume transports at 78 55 n were in the order of 10 sv both northwards and southwards with an annual mean net transport between 2 and 4 sv to the south the temperature of the northward flow of atlantic water had a strong seasonality with a minimum in winter nevertheless the northward heat transport was highest in winter caused by the winter maximum of northward volume transport during the three years of observation the heat transport in the west spitsbergen current increased from 28 to 46 tw as a result of both increased speed and temperature in contrast to the west spitsbergen current the volume and heat transport of east greenland current remained fairly constant an integration over a subsection of the east greenland current showed similar values of volume transport to that obtained by measurements in the 1980s foldvik et al 1988 the southward heat transport through modified atlantic water weakened slightly between 1997 and 1999 despite increased temperatures

nonequilibrium regolith thickness in the ouachita mountains abstract interpretations of regolith and soil thickness in the context of landscape evolution are typically based on the notion that thickness is controlled by the interaction of weathering rates and erosion and tuned to topography on sideslopes of the ouachita mountains arkansas however there is a high degree of local spatial variability that is largely unrelated to topography this indicates nonequilibrium in the sense that there is no evidence of a balance between rates of weathering and removal as is postulated in some conceptual models in geomorphology and pedology johnson s soil thickness model is applied as an alternative to interpret local variations in regolith thickness at the study sites regolith thickness is not generally related to slope curvature elevation or pedogenic development in the solum this indicates that variability in thickness is related chiefly to processes and controls acting in the lower regolith below the solum the primary controls of variability are local lithol

berino paleosol late pleistocene argillic soil development on the mescalero sand sheet in new mexico abstractthe berino paleosol is the first record of a directly dated aridisol in the american southwest where paleoclimatic conditions during the time of pedogenesis can be estimated the noncalcic argillic paleosol formed in eolian sand during the cool wet climate of the mid and late wisconsin marine isotope stages 3 and 2 in presently semiarid southeastern new mexico optically stimulated luminescence dating of the mescalero sand sheet and the berino indicates that soil formation occurred during the period 50 18 ka the paleosol is a red 2 5yr hue bt horizon 120 cm thick with 25 clay 0 36 fe and an absence of visible carbonate it is buried by younger eolian sand although at the edges of the sand sheet it is unburied and a relict soil red argillic paleosols in other sand sheets in the region may correlate with the berino the berino paleosol is formally named as a pedostratigraphic unit

the glacial history of the pindus mountains greece abstract geomorphological evidence for pleistocene glaciation has been mapped in the pindus mountains of northwest greece and the chronology of glaciation in this area has been established through soil profile analysis and u series dating of secondary carbonates calcite formed within glacial deposits three glacial stages are evident in the sedimentological and geomorphological records the earliest and most extensive recorded glaciation predates 350 000 yr b p and was characterized by extensive valley glaciers and ice fields a more recent glaciation occurred before the last interglacial and was characterized by glaciers that reached midvalley positions the last phase of glaciation in greece is recorded by small cirque glacier moraines and relict periglacial rock glaciers the glacial and periglacial sequence on mount tymphi has been used in conjunction with a reference parastratotype the long lacustrine sequence at ioannina to provide a chronostratigraphical framework for cold stage deposits in g

laser vs settling velocity differences in silt grainsize measurements estimation of palaeocurrent vigour the use of grain size distribution of muds for the reconstruction of past deep ocean currents is becoming established and applied in the palaeoceanographic community the methods are also applicable to shallow marine and tidal flat muds with similar inferences concerning the energy of wave and current sorting being drawn fine sediment grain size distributions can be obtained using a variety of instruments based on fundamentally different theoretical principles these machines may give varying sometimes misleading results giving divergent interpretations of flow speed history the new evidence presented here combined with earlier work suggests that of the three most commonly used analytical methods for fine silts with clays settling velocity sedigraph should be the method and instrument of choice with electrical resistance pulse counters e g coulter counter as a suitable alternative the data also show that laser particle sizers should be avoided for palaeocurrent reconstructions because the measured size of platey minerals can be dominated by their large projected area this causes them to be recorded as the same size as larger equant grains although they have much smaller settling velocity and were deposited in aggregates this produces results with a weaker relationship to the dynamics of deposition the central problem is thus that some coarse clay fine silt is recorded as medium to coarse silt the key size in the sortable silt mean size method of inferring changes in flow speed for coarse silts e g loess the laser gives more satisfactory results

vertisol carbonate properties in relation to mean annual precipitation implications for paleoprecipitation estimates abstract previous publications combining the properties of multiple soil orders show that depth to carbonate dtc increases systematically between 350 and 1000 mm of mean annual precipitation map we hypothesize that carbonate in vertisols clay rich shrink swell soils respond differently to water flux than other soil orders because of lower permeability to test this hypothesis we compiled soil description and characterization data from multiple published sources across a late pleistocene climosequence of the coast prairie of texas to assess the relationship between map 700 1400 mm and dtc the dtc of carbonate nodules represents an index of accumulation and the dtc of calcium carbonate equivalent total carbonate 2 0 mm diam an index of leaching the dtc for 1 2 and 5 abundances were assessed using regression analysis the r2 values were highest for the dtc of 2 nodules and of 1 calcium carbonate equivalent in vertisol microlows surprisingly relatively high r2 values were calculated

late quaternary slip rate of the southern elsinore fault southern california dating offset alluvial fans via 230th u on pedogenic carbonate 1 to understand how strain is accommodated along the pacific north american plate boundary and to assess the associated seismic hazard estimates of long term 103 105 year slip rates for strands of the san andreas fault system are needed the mean slip rate over the past 40 kyr for the southernmost elsinore fault one of the principal strands of the san andreas fault system in southern california was determined using offset alluvial fans dated by u series on pedogenic carbonate two displaced fans correlated with their source drainages using distinctive gravel clast assemblages define offsets of 60 20 and 83 31 m milligram size samples of dense carbonate clast coatings from fan soils provide 230th u based ages of 39 1 5 3 and 46 4 5 3 kyr all errors are 2 respectively for the offset fans our results indicate that the elsinore fault near its southern terminus slipped at a mean rate of 1 6 0 4 mm yr over the past 40 kyr however slip associated with the most recent earthquake on the southern elsinore fault increases northward from the study area and if this pattern has repeated through time the peak slip rate on the southern elsinore fault may significantly exceed our measured rate

advection of atlantic water to the western and northern svalbard shelf since 17 500 cal yr bp abstract the changes in flow and character of the warm atlantic water through the last 17 500 cal yr are reconstructed from the distribution of benthic foraminifera species planktonic and benthic foraminifera abundances stable oxygen isotopes and lithology in two cores from the western and northern shelf of svalbard the results show almost continuous presence of atlantic water at the shelf areas since 14 500 cal yr bp the bolling and allerod intervals stand out as periods of highest bottom waters temperatures the strong inflow of saline but chilled atlantic water during the early holocene was followed by cooling and freshening of the bottom waters during the mid and late holocene the two records reveal synchronous oceanographic changes that are closely tied to changes in the flow of atlantic water recorded further south in the nordic seas the early holocene warming was not just an effect of higher solar insolation but was also due to increased heat flux from the stronger atlantic water inflow driven by wind force and or thermohaline circulation

timing and distribution of alluvial fan sedimentation in response to strengthening of late holocene enso variability in the sonoran desert southwestern arizona usa abstract the integration of geomorphic mapping soil stratigraphy and radiocarbon dating of alluvial deposits offers insight to the timing magnitude and paleoclimatic context of holocene fan sedimentation near yuma arizona mapping of 3400 km2 indicates about 10 of the area aggraded in the late holocene and formed regionally extensive alluvial fan and alluvial plain cut and fill terraces fan deposits have weakly developed gravelly soils and yielded a date of 3200 2950 cal yr bp from carbonized wood alluvial plain deposits have weakly developed buried sandy soils and provided a date of 2460 2300 cal yr bp from a terrestrial snail shell precipitation records were analyzed to form historical analogues to the late holocene aggradation and to consider the role of climatic variability and extreme hydrologic events as drivers of the sedimentation the historical precipitation record indicates numerous above average events correlated to the southern oscillation index soi in the region but lacks any significant reactivation of alluvial fan surfaces the timing of aggradation from 3200 to 2300 cal yr bp correlates well with other paleoclimatic proxy records in the southwestern u s and eastern pacific region which indicate an intensification of the el nino southern oscillation enso climatic pattern and rapid climate change during this period

high resolution proxy record of holocene climate from a loess section in southwestern nebraska usa abstract multi proxy analysis was used to produce a high resolution paleoclimatic record from an exceptionally thick section of the holocene bignell loess near wauneta southwestern nebraska in the central great plains the wauneta section has excellent age control based on optically stimulated luminescence osl and radiocarbon dating and records multiple episodes of rapid loess deposition alternating with slower deposition and soil formation the lowermost and uppermost osl ages obtained from the bignell loess are 10 250 610 years 5 9 m depth and 100 10 years 0 1 m depth respectively as a result the holocene has been temporally confined stratigraphically the bignell loess overlies the late pleistocene peoria loess deposited 21 14 ka and the two units are separated by the brady soil which is distinguished by its color and other pedogenic features l a b color parameters and organic carbon content of bignell loess are sensitive proxies to differentiate drought induced aeolian sediment layers from the intercalated soil horizons soil organic carbon derived 13 c data suggest that the c 3 dominated floral environment during peoria loess deposition shifted dramatically to a c 4 dominated environment during brady soil formation in response to a warming trend even greater c 4 abundance characterized the late holocene high resolution 13 c data support the contention that c 3 vs c 4 vegetation change in the holocene reflects ecosystem response to frequent vegetation disturbance under arid conditions time series analysis reveals that 13 c and color parameters display high frequency variation with periodicities of 103 118 years and 103 years respectively similar periodicities were also reported in studies of north dakota lakes though the physical mechanism responsible is uncertain comparison of bignell loess color and tropical pacific sea surface temperatures ssts allows evaluation of a proposed teleconnection between drought in the great plains and la nina like conditions in the tropical pacific the loess color index and eastern tropical pacific sst display broad similarities through the late pleistocene and holocene that are consistent with this teleconnection on the other hand drought centered at 3800 years ago is not consistent with the teleconnection and the end of early holocene aridity at the wauneta section around 6500 years ago is much earlier than the corresponding rise in sst and increase in el nino frequency in the eastern tropical pacific

recent distribution and accumulation of organic carbon on the continental margin west off spitsbergen the study compiles the controlling factors for organic matter sedimentation patterns from a suite of organogeochemical parameters in surface sediments off spitsbergen and direct seabed observations using a remotely operated vehicle rov in addition we assess its storage rates as well as the potential of carbon sinks on the northwestern margin of the barents sea with short sediment cores from a selected fjord environment storfjord while sedimentation in the fjords is mainly controlled by river meltwater discharge and coastal erosion by sea ice glaciers resulting in high supply of terrigenous organic matter atlantic water inflow and thus enhanced marine organic matter supply characterizes the environment on the outer shelf and slope local deviations from this pattern particularly on the shelf are due to erosion and out washing of fine grained material by bottom currents spots dominated by marine productivity close to the island have been found at the outer isfjord and west off prins karls forland as well as off the kongsfjord krossfjord area and probably reflect local upwelling of nutrient rich atlantic water derived water masses accumulation rates of marine organic carbon as well as reconstructed primary productivities decreased since the middle of the last century negative correlation of the isfjord temperature record with reconstructed productivities in the storfjord could be explained by a reduced annual duration of the marginal ice zone in the area due to global warming extremely high accumulation rates of marine organic carbon between 5 4 and 17 2 g m 2 yr 1 mark the storfjord area and probably high latitude fjord environments in general as a sink for carbon dioxide

soil evolution over the quaternary period in a mediterranean climate se spain palaeosols in the granada basin se spain have been studied in two different situations surface soils on geomorphically stable surfaces since the early pleistocene with younger pedogenic overprinting and buried soils on unstable surfaces from the middle late pleistocene on which successive erosional depositional episodes have alternated with pedogenic episodes for each soil clay and iron accumulation indices the fet alt sit ratio clay mineralogy and micromorphological features were used to estimate the degree of soil development from the early to the early late pleistocene the main pedogenic processes were the leaching of carbonates weathering illuviation and rubification which resulted in bt horizons with red colours clay texture clay coatings and kaolinite neoformation the degree of weathering and the development of these bt horizons varied over time and the soils that formed on the surfaces from the early pleistocene show strongest weathering and development however after their formation there were periods in which they were partially truncated and recalcified resulting in polygenetic soils the different degrees of development of the buried soils during the last 474 000 years indicate that the wettest warm period was stage 7 and the driest stage 5 stages 9 and 11 must have had climates with intermediate wetness since the clay accumulation and iron oxide accumulation indices the differences in fet alt sit ratio between bt and c horizons the extent of kaolinite neoformation and the micromorphological features of the soils formed during stage 7 are all similar to the surface soils that formed on early pleistocene deposits these features cannot be used to date surfaces older than 242 000 bp by contrast the soils that formed during stage 7 and later periods show different extents of development and thus can be used for the approximate dating of landforms d 2002 elsevier science b v all rights reserved

latest pleistocene and holocene slip rate for the san bernardino strand of the san andreas fault plunge creek southern california implications for strain partitioning within the southern san andreas fault system for the last 35 k y an alluvial succession on the northeast side of the san bernardino strand of the san andreas fault includes distinctive aggradational and degradational features that can be matched with correlative features on the southwest side of the fault key among these are 1 a terrace riser on the northeast side of the fault that correlates with an offset channel wall on the southwest side of the fault and forms a basis for slip estimates for the period ca 35 ka to the present and 2 a small alluvial fan on the southwest side of the fault that has been matched with its most likely source gullies on the northeast side of the fault and forms a basis for slip estimates for the last 10 5 k y slip rate estimates for these two separate intervals are nearly identical the rate for the older feature is most likely between 8 3 and 14 5 mm yr with a 95 confidence interval of 7 0 15 7 mm yr the rate for the younger feature is most likely between 6 8 and 16 3 mm yr with a 95 confidence interval of 6 3 18 5 mm yr these rates are only half the previously published slip rate for the san andreas fault 35 km to the northwest in cajon pass a rate that traditionally is extrapolated southeastward along the san bernardino section of the fault results from plunge creek suggest that about half of the 25 mm yr rate at cajon pass transfers southeastward to the san jacinto fault as proposed by other workers on the basis of regional geologic relations these results indicate that the discrepancy between latest quaternary slip rates and present day rates of strain accumulation across the san bernardino section of the san andreas fault from geodesy can be largely explained by slip transfer between faults leading to spatial variation in rate along the san andreas fault nonetheless the latest pleistocene and holocene slip rate at plunge creek is still somewhat faster than rates inferred for the san bernardino section of the san andreas fault based on elastic block modeling of geodetic data and may be more appropriate than those rates for hazard estimation

geochemical characterization and dating of r tephra a postglacial marker bed in mount rainier national park washington usa the oldest postglacial lapilli ash tephra recognized in sedimentary records surrounding mount rainier washington state usa is r tephra a very early holocene deposit that acts as an important stratigraphic and geochronologic marker bed this multidisciplinary study incorporates tephrostratigraphy radiocarbon dating petrography and electron microprobe analysis to characterize r tephra tephra samples were collected from tipsoo lake and a stream cut exposure in the cowlitz divide area of mount rainier national park field evidence from 25 new sites suggests that r tephra locally contains internal bedding and has a wider distribution than previously reported herein we provide the first robust suite of geochemical data that characterize the tephra glass compositions are heterogeneous predominantly ranging from andesite to rhyolite in ash to lapilli sized clasts the mineral assemblage consists of plagioclase orthopyroxene clinopyroxene and magnetite with trace apatite and ilmenite subaerial r t

anthropogenic origins of a late holocene basin wide unconformity in the middle reaches of the yellow river the luoyang basin henan province china we evaluate the relative importance of climate change fluvial dynamics and anthropogenic environmental modification in forming the holocene sedimentary record of the luoyang basin a tributary drainage basin of the yellow river located in western henan province china our 2011 fieldwork south of the erlitou site in the luoyang basin indicates that an unconformity dating to ca ad 1100 is roughly coincident with a major southward shift in the lower course of the yellow river in ad 1128 the governor of kaifeng breached the dikes of the yellow river to impede an advancing army causing the yellow river to flow south out to the yellow sea we argue that the dike breach not only changed the fluvial dynamics of the yellow river but also switched the rivers in the luoyang basin from an aggrading to an incising system the resumption of sedimentation in the luoyang basin is roughly coincident with the next major shift of the yellow river s main course northward to the bohai sea in ad 1855 the unconformity found in the luoyang basin may be a legacy of historically contingent human agency rather than climatic shifts or gradual environmental modification

propagation of the storegga tsunami into ice free lakes along the southern shores of the barents sea this paper is part of anders romundset s doctoral thesis which is available in munin at http hdl handle net 10037 2703

the impact of climate on the biogeochemical functioning of volcanic soils abstract rainfall and the amount of water available to leach ions from soil are among the most important features determining mineral weathering secondary mineral synthesis and soil chemical properties along an arid to humid climosequence on kohala mountain hawaii we sampled 16 soil profiles and found that weathering and soil properties change in a nonlinear fashion with increased rainfall the lavas are influenced by a strong rain shadow with mean annual precipitation map averaging 160 mm near the coast and rising to 3000 mm near the summit a temperature decline from 24 to 15 c with increasing elevation is matched by lower potential evapotranspiration et a water balance model monthly precipitation minus monthly et defines three broad climate zones along the sampling transect an arid zone with moisture deficit in every month an intermediate zone with moisture deficit during low rainfall summer months and moisture surplus during high rainfall winter months and a humid zone with moisture surplus during every month the annualized water balance can be ratioed with the integrated porosity of the top meter of soil to provide a leaching index the index reaches 1 total filling of the pore space on an annual basis at about 1400 mm map index values 1 imply intense leaching conditions because of pore water replacement in these 170 ka soils leaching losses of soluble base cations and si are nearly complete at index values 1 whereas only 60 of al has been lost at index values 1400 mm soil buffering capacity has been totally exhausted leading to low ph and low ecec the nonlinear decline in ecec is irreversible under natural conditions base cation depleted soils will remain so even if the climate shifts to drier conditions in contrast a climate shift to wetter conditions can drastically modify surface chemical properties existing in the drier soils as weathering depletes primary minerals elements are lost to leaching and surface chemistry is modified there is a time dimension implied in climate gradient studies soils forming in recently rejuvenated landscapes contain more primary minerals and should experience loss of buffering capacity at higher rainfall loss of buffering capacity means that biological acidity will move more deeply into the vadose zone or into the aquatic system the details of this transfer depend on present and past climate and the age and erosional stability of landscapes

soil forming rates and processes on quaternary moraines near lago buenos aires argentina thirty four pedons on four moraine groups spanning the last 1 myr are used to investigate mechanisms and rates of soil development in santa cruz province argentina all soils are coarse loamy mesic typic haplocalcids or calcic haploxerolls occurring under short grass shrub steppe in a semi arid climate the dominant soil forming processes are the accumulation of organic matter carbonate and clay sized particles organic carbon accumulates rapidly in these soils but significantly higher amounts in the oldest two moraine groups are likely the result of slight differences in soil forming environment or grazing practices accumulation rates of carbonate and clay decrease with age suggesting either decreased influx in the earliest part of the record or attainment of equilibrium between influx and loss there are no changes in soil redness and preservation of weatherable minerals in the oldest soils indicates there is little chemical weathering in this environment measured dust input explains the accumulation of both clay and carbonate we present a carbonate cycling model that describes potential sources and calcium mobility in this environment calibration of rates of soil formation creates a powerful correlation tool for comparing other glacial deposits in argentina to the well dated moraines at lago buenos aires

paleoceanographic evolution of the sw svalbard margin 76 n since 20 000 14c yr bp abstract two cores from the southwestern shelf and slope of storfjorden svalbard taken at 389 m and 1485 m water depth have been analyzed for benthic and planktic foraminifera oxygen isotopes and ice rafted debris the results show that over the last 20 000 yr atlantic water has been continuously present on the southwestern svalbard shelf however from 15 000 to 10 000 14c yr bp comprising the heinrich event h1 interval the bolling allerod interstades and the younger dryas stade it flowed as a subsurface water mass below a layer of polar surface water in the benthic environment the shift to interglacial conditions occurred at 10 000 14c yr bp due to the presence of a thin upper layer of polar water surface conditions remained cold until ca 9000 14c yr bp when the warm atlantic water finally appeared at the surface neither extensive sea ice cover nor large inputs of meltwater stopped the inflow of atlantic water its warm core was merely submerged below the cold polar surface water

pedogenic approach to resolving the geomorphic evolution of the pakua river terraces in central taiwan abstract the southern part of the pakua tableland in taiwan comprises a series of wide unpaired river terraces that have as many as six altitude levels from pk 1 highest to pk 6 lowest the terrace surfaces are covered with lateritic soils this study described sampled and analyzed the soils from each terrace soil taxonomies are oxisol ultisol and inceptisol soil morphological characteristics were quantified as a profile development index pdi to determine the degree of soil development the chemical analyses included cation exchange capacity cec and selected extraction of fe in soils based on the degree of soil development surface deposits on terrace flights form the post incisive soil chronosequence supporting the hypothesis of terrace formation by fluvial processes soil ages were estimated based on iron crystallinity fed feo fet analytical results indicate that river terraces in the pakua tableland are aged 40 400 ka the long term uplift rate of the tableland can be estimated using terrace ages and folding geometry the variation of uplift rates demonstrates that the landscape underwent increased shortening of frontal thrusting by the changhua fault running beneath the tableland

sortable silt and fine sediment size composition slicing parameters for palaeocurrent speed and palaeoceanography fine sediment size 63 ixm is best measured by a sedimentation technique which records the whole size distribution repeated size measurement with intermediate steps of removal of components by dissolution allows inference of the size distribution of the removed component as well as the residue in this way the size of the biogenic and lithogenic noncarbonate fractions can be determined observations of many size distributions suggest a minimum in grain size frequency curves at 8 to 10 ixm the dynamics of sediment erosion deposition and aggregate breakup suggest that fine sediment behavior is dominantly cohesive below 10 1xm grain size and noncohesive above that size thus silt coarser than 10 ixm displays size sorting in response to hydrodynamlc processes and its properties may be used to infer current speed silt that is f mer than 10 ixm behaves in the same way as clay 2 xm useful parameters of the distribution are the 10 63 ixm mean size and the percentage 10 63 ixm in the fine fraction we cannot use size distributions to distinguish the nature of the currents therefore to infer water mass advection speeds i e the mean kinetic energy of the flow ku regions of high eddy kinetic energy ke must be avoided at the present such abyssal regions lie under the high surface k e of major current systems gulf stream kuroshio agulhas antarctic circmpolar current and brazil falldand currents in the argenthe basin this is probably a satisfactory guide for the pleistocene with regard to the carbonate subfraction of the size spectrum size modes due to both cocco iths and foramlnlferal fragments can be recognized and analyzed with the boundary between them again at about 10 lm the flux of less than 10 lm carbonate at pelagic sites above the lysocline is another candidate for a productivity indicator

pedogenic properties of surface deposits used as evidence for the type of landform formation of the tadu tableland in central taiwan abstract the tadu tableland is located at the deformation front of the western foothills in central taiwan the surface of the tableland is covered by reddish soils and gravels and is folded symmetrically with gently dipping strata running toward both wings previous geomorphic studies suggested a fluvial terrace landform developed on the surfaces of the tableland however other suggestions have been proposed in recent years this study attempts to solve the argument by examining the pedogenesis of surface deposits five soil pedons were sampled to the depths of c horizons in the surface deposits of the tableland strong migration of illuvial clay was indicated by the accumulation of significant clay coatings in the sub surface soils these soils were classified as paleudult and kandiudult of ultisols according to soil taxonomy in addition their morphological characteristics were further quantified in terms of soil development by the horizon index and weighted profile development index wpdi the wpdi values of 0 64 0 73 for the soils of the tadu tableland agree with those of ultisols developed on the pakua tableland both qualification and quantification assessments indicate all soils of the tadu tableland are equivalent in terms of degree of pedogenesis as a result all the geomorphic surfaces on the tableland probably developed at the same time which rules out the interpretation of fluvial terraces developing on the tableland the pedogenic evidence conditionally supports the recently proposed kinematic model for the development of the tadu tableland

weathering and vegetation effects in early stages of soil formation abstract bedrock surfaces in the ouachita mountains arkansas exposed by spillway construction and which had not previously been subjected to surface weathering environments developed 15 20 cm thick soil covers in less than three decades all open bedrock joints showed evidence of weathering and biological activity rock surfaces and fragments also showed evidence of significant weathering alteration the results suggest a soil production function whereby weathering and increases in thickness are initially rapid the rapid initial rate 5 to 10 mm year 1 is facilitated by a weathering favorable regional climate local topography favoring moisture and sediment accumulation and aggressive vegetation colonization the ages of the trees on the bedrock benches suggests that a short period