characteristics and formation of eastern south pacific intermediate water 1 newly gathered hydrographic data from the eastern south pacific is combined with other high quality data mainly woce to reassess the properties and boundaries of the eastern south pacific intermediate water espiw to date the espiw has been only poorly described the espiw core is found off central and northern chile between the coast and 90 w and 20 38 s located at 50 400 m of depth its temperature varies between 11 13 c salinity ranges from 34 1 34 3 and its sigma t lies between 25 75 26 25 kgm 3 espiw spreads with the subtropical gyre circulation and can be traced to at least 150 w formed through the process of subduction southeastward of the wind driven gyre circulation the espiw communicates surface properties of the waters off central chile to tropical latitudes

properties and development of soils on reclaimed alluvial sediments of the humber estuary eastern england abstract sunk island an area of reclaimed estuarine alluvial sediments in the lower humber estuary provides a series of recent surfaces ranging from around 100 to 260 years old upon which soil properties associated with soil ripening can be examined free from the disturbance of subsequent flooding and sedimentation within the first 100 years of pedogenesis overall bulk density of the sediment has increased and profile differentiation has resulted from structural development organic matter accumulation and tillage the original sedimentary structures of the soil have gradually become obscured and overprinted by ped and pore patterns related to wetting and drying burrowing and root development aeration has accelerated organic matter decay and accentuated the difference between topsoil and subsoil contents variations in aeration and moisture content have resulted in mottling which has become less prevalent as the soils develop properties such as available water content organic c and cation exchange capacity cec depend upon the grain size characteristics in particular clay content exchangeable bases have been progressively removed reaching a state of quasi equilibrium within 150 years of reclamation crystallisation of goethite has extended progressively deeper into the profile through time accompanied by a decrease in amorphous iron compounds

the role of the magellan strait on the southwest south atlantic shelf abstract we analyze historical hydrographic data together with recent high resolution hydrographic and underwater glider observations collected in the magellan strait to determine the water mass characteristics and exchanges between the continental shelves of the southeast south pacific and southwest south atlantic around southern south america the near surface salinity distribution and water mass analyses indicate a strong interoceanic connectivity associated with diluted subantarctic waters of the pacific ocean through the magellan strait which in turn are further diluted largely by inflows from the almirantazgo fjord via the whiteside channel the lowest salinity waters reach the atlantic shelf via the magellan strait this core of low salinity waters s

changes in biological productivity and ocean climatic fluctuations during the last 1 5 kyr in the humboldt ecosystem off northern chile 27 s a multiproxy approach abstract a sedimentary box core biac072014 collected in a coastal environment in the humboldt current ecosystem hce inglesa bay 27 s northern chile was used to reconstruct the changes in biological productivity and ocean climate fluctuations during the last 1 5 kyr via geochemical mineralogical and micropaleontological analyses from 510 ce to 930 ce el nino like conditions prevailed while during the medieval climate anomaly mca 950 ce to 1450 ce la nina like conditions predominated this pattern might have resulted from weakening strengthening of the walker cell contraction expansion of the south pacific sub tropical high spsh and a predominance of warm cold phases of the pacific decadal oscillation pdo between 1820 ce and the present inglesa bay experienced a reduction in the oxygen minimum zone omz intensity and biological productivity an increase in the detritic input and a decrease in sea surface temperature sst despite the regional intensification and secular cooling 14 s and 27 s of coastal upwelling the similarity between the reduction in biological productivity and omz intensity in this region and that in the central zone of chile 36 s suggests that inglesa bay acts a transition zone in relation to the oceanographic behaviour of the hce the reduction in the omz intensity and biological productivity during the last 200 years could be explained by greater subsurface ventilation in intermediate depths due to more northward displacement of the subduction region of the eastern south pacific intermediate water espiw near 30 s in response to the strengthening of the circulation of the subtropical gyre the coastal cooling observed in the northern section of hce during the current warm period suggests that it is not possible to demonstrate that el nino like conditions promoted the reduction in biological productivity and omz intensity in inglesa bay

evolution of the lower gangetic plain landforms and soils in west bengal india abstract three major landforms uplands old fluvial deltaic plains and young fluvial plains are identified from the lower gangetic plains of west bengal india on the basis of remote sensing and field studies morphologic quantitative and thermoluminescence studies of soils of the study area have been conducted two types of uplands are recognised upland in the west overlain by red soils autochthonous and allochthonous types and upland in the north barind tract characterised by three topographic levels aspects of the autochthonous upland red soils lower to middle pleistocene age show the ferrugination ferrisol phase of development soils of the old fluvial deltaic plains 6 3 ka and lower level of the barind tract have argillic horizons and exhibit the fersiallitisation phase of development development of ferrugination and fersiallitisation phases was favored due to the pre weathered nature of the parent material soils of the old fluvial deltaic plains barind tract lower level and young fluvial plains show effects of hydromorphism due to waterlogging in the form of segregations of fe mn oxides gleying and chloritisation probably due to ferrolysis in the upper horizons of some of these soils neotectonics seems to have affected development of landforms and soils significantly due to reactivation of some basement faults in the western region some tectonic blocks subsided causing transgression during the early pleistocene and at ca 7 ka subsequent uplift of these blocks caused regressions and development of soils on the exposed landscapes episodic uplift of the barind tract in the northern region may have given rise to three topographic levels some faults confine the courses of the damodar ganga and bhagirathi rivers

the formation of a subsurface anticyclonic eddy in the peru chile undercurrent and its impact on the near coastal salinity oxygen and nutrient distributions the formation of a subsurface anticyclonic eddy in the peru chile undercurrent pcuc in january and february 2013 is investigated using a multi platform four dimensional observational approach research vessel multiple glider and mooring based measurements were conducted in the peruvian upwelling regime near 12 30 s the dataset consists of 10000 glider profiles and repeated vessel based hydrography and velocity transects it allows a detailed description of the eddy formation and its impact on the near coastal salinity oxygen and nutrient distributions in early january a strong pcuc with maximum poleward velocities of 0 25 m s at 100 to 200 m depth was observed starting on january 20 a subsurface anticyclonic eddy developed in the pcuc downstream of a topographic bend suggesting flow separation as the eddy formation mechanism the eddy core waters exhibited oxygen concentrations 1 mol kg an elevated nitrogen deficit of 17 mol l and potential vorticity close to zero which seemed to originate from the bottom boundary layer of the continental slope the eddy induced across shelf velocities resulted in an elevated exchange of water masses between the upper continental slope and the open ocean small scale salinity and oxygen structures were formed by along isopycnal stirring and indications of eddy driven oxygen ventilation of the upper oxygen minimum zone were observed it is concluded that mesoscale stirring of solutes and the offshore transport of eddy core properties could provide an important coastal open ocean exchange mechanism with potentially large implications for nutrient budgets and biogeochemical cycling in the oxygen minimum zone off peru

mineralogic information from a new airborne thermal infrared multispectral scanner a new six channel aircraft multispectral scanner has been developed to exploit mineral signature information at wavelengths between 8 and 12 micrometers preliminary results show that igneous rock units can be identified from their free silica content and that carbonate as well as clay bearing units are readily separable on the digitally processed images

the south pacific current the southern hemisphere subtropical front stf is a narrow zone of transition between upper level subtropical waters to the north and subantarctic waters to the south it is found near 40 degrees s across the south atlantic and south indian oceans and is associated with an eastward geostrophic current band the current band in each basin is found at or just north of the surface front except near the eastern boundaries where most of the subtropical waters turn north into the eastern limbs of the subtropical gyres the bands associated with the stf are thus distinct features separated from the strong zonal flows of the antarctic circumpolar current farther south the authors have referred to the current bands in the two respective oceans as the south atlantic current and the south indian ocean current in this paper the authors use the historical database from the south pacific ocean to investigate the geostrophic flow associated with the stf there the stf extends across the southern tasman sea from south of tasmania to southern new zealand and a weak eastward flow appears to be associated with it the transport amounts to only about 3 sv 1sv 10 6 m 3 s 1 little of which passes south of new zealand mixing within the eddy rich tasman sea may account for this weakness while also setting up another more significant front in the northern tasman sea the tasman front it branches off from the east australian current toward the north of new zealand along which moves a flow of about 14 sv after passing north of new zealand a portion of this current flows east to contribute to a current band near 30 degrees s while another portion turns south as the east auckland current and meets with subantarctic waters near chatham rise 44 degrees s thus reestablishing the stf an enhanced eastward current band is associated with the front there one that extends across the remainder of the south pacific and is referred to as the south pacific current in comparison with its counterparts in the other basins which typically begin by carrying 30 sv atlantic to 60 sv indian in the upper 1000 m in their western portions before weakening to 10 15 sv in the east the south pacific current is weak near chatham rise it starts with a transport of approximately 5 sv and it remains near this strength as it shifts gradually north across the basin toward south america the current appears to split into two smaller bands in the region of 115 degrees 85 degrees w while near 28 degrees 5 83 degrees w it begins to turn more strongly north and becomes shallower and weaker potential vorticity distributions indicate that this current acts as an impediment toward the northward spreading of antarctic intermediate water but why the south pacific current east of new zealand should be so much weaker than its counterparts in the other basins is not particularly clear it may be due to the presence of new zealand and other topographic barriers to deep now east of australia to the axis of the subtropical gyre in the south pacific shifting more rapidly southward with depth than those elsewhere thus causing greater reductions in the underlying zonal velocities and to strong poleward eddy heat and salt fluxes in the other two basins leading to smaller cross stf gradients in the pacific

water masses in the humboldt current system properties distribution and the nitrate deficit as a chemical water mass tracer for equatorial subsurface water off chile abstract three sections are used to analyze the physical and chemical characteristics of the water masses in the eastern south pacific and their distributions oceanographic data were taken from the scorpio may june 1967 piquero may june 1969 and krill june 1974 cruises vertical sections of temperature salinity dissolved oxygen nitrate nitrite phosphate and silicate were used to analyze the water column structure five water masses were identified in the zone through t s diagrams subantarctic water subtropical water equatorial subsurface water antarctic intermediate water and pacific deep water their proportions in the sea water mixture are calculated using the mixing triangle method vertical sections were used to describe the geographical distributions of the water mass cores in the upper 1500 m several characteristic oceanographic features in the study area were analyzed the shallow salinity minimum displacement towards the equator the equatorial subsurface salinity maximum associated with a dissolved oxygen minimum zone and a high nutrient content displacement towards the south and the equatorward intermediate antarctic salinity minimum associated with a dissolved oxygen maximum the nitrate deficit generated in the denitrification area off peru and northern chile is proposed as a conservative chemical tracer for the equatorial subsurface waters off the coast of chile south of 25 s

mapping playa evaporite minerals and associated sediments in death valley california with multispectral thermal infrared images efflorescent salt crusts and associated sediments in death valley california were studied with remote sensing data acquired by the nasa thermal infrared multispectral scanner tims nine spectral classes that represent a variety of surface materials were distinguished including several classes that reflect important aspects of the playa groundwater chemistry and hydrology evaporite crusts containing abundant thenardite sodium sulfate were mapped along the northern and eastern margins of the cottonball basin areas where the inflow waters are rich in sodium gypsum calcium sulfate crusts were more common in the badwater basin particularly near springs associated with calcic groundwaters along the western basin margin evaporite rich crusts generally marked areas where groundwater is periodically near the surface and thus able to replenish the crusts though capillary evaporation detrital silicate minerals were prevalent in other parts of the salt pan where shallow groundwater does not affect the surface composition the surface features in death valley change in response to climatic variations on several different timescales for example salt crusts on low lying mudflats form and redissolve during seasonal to interannual cycles of wetting and desiccation in contrast recent flooding and erosion of rough salt surfaces in death valley probably reflect increased regional precipitation spanning several decades remote sensing observations of playas can provide a means for monitoring changes in evaporite facies and for better understanding the associated climatic processes at present such studies are limited by the availability of suitable airborne scanner data however with the launch of the earth observing system eos am 1 platform in 1998 multispectral visible near infrared and thermal infrared remote sensing data will become globally available

effects of treethrow microtopography on the characteristics and genesis of spodosols michigan usa summary this study examined the pedogenic effects of pit and mound microtopography formed by tree uprooting in a spodosol haplorthods landscape most soils in treethrow pits were entic haplorthods or spodic upidsamments whereas mound soils usually classified as typic udipsamments suggesting that degree of profile development is undisturbed pit mound given that pit and mound soils are substantially younger than pedons on undisturbed sites rates of pedogenesis are thought to be pit undisturbed mound strong pedogenesis in pits was explained by 1 greater water contents in the upper sola which may facilitate weathering processes 2 thicker o horizons which may lead to increased production of organic acids and 3 greater insulation by thick litter and snow cover which reduces the incidence of soil freezing in winter mound soils may develop impermeable layers of concrete soil frost that impede infiltration of snowmelt waters whereas pit soils remain unfrozen or acquire only a porous granular frost layer thus saturated flow of snowmelt within pits is relatively unrestricted resulting in maximal leaching and profile differentiation

rates of weathering and chemical depletion in soils across a chronosequence of lake michigan sand dunes abstract accumulation of soil organic matter and depletion of base cations and trace metals were measured in surface soils i e o horizon and upper 15 cm of mineral soil across a 4150 year soil chronosequence of dune capped beach ridges bordering northern lake michigan within 400 years of beach ridge formation coniferous forest develops soil c and n accumulate to steady state levels of 40 and 1 3 mg ha 1 respectively and the ph of the upper mineral soil decreases from 8 5 to 4 3 as carbonate minerals dissolve after substantial proportions of ca and mg have been removed an incipient spodic horizon can be observed the upper surface of which progressively deepens with increasing soil age analysis of soil strain of the upper mineral soil showed gradual dilation reaching 121 after several centuries of soil development after accounting for soil dilation quantities of ca mg p zn mn fe and v in the upper 15 cm of mineral soil decreased exponentially to low asymptotic levels representing quantities contained in weathering resistant minerals mass balance modeling indicated weathering and elemental losses in the order of decreasing decay constant as ca mg mn zn p v fe al k na ti this sequence is consistent with weathering of carbonates then ferromagnesian minerals then feldspars p levels are tightly coupled with ca losses in soils older than 200 years suggesting that ca rather than fe or al stabilizes p high concentrations of heavy metals in the organic horizon relative to the upper mineral soil indicate atmospheric inputs of industrial pollutants

mars white rock feature lacks evidence of an aqueous origin results from mars global surveyor the white rock feature on mars has long been viewed as a type example for a martian playa largely because of its apparent high albedo along with its location in a topographic basin a crater data from the mars global surveyor thermal emission spectrometer tes demonstrate that white rock is not anomalously bright relative to other martian bright regions reducing the significance of its albedo and weakening the analogy to terrestrial playas its thermal inertia value indicates that it is not mantled by a layer of loose dust nor is it bedrock the thermal infrared spectrum of white rock shows no obvious features of carbonates or sulfates and is in fact spectrally flat images from the mars orbiter camera show that the white rock massifs are consolidated enough to retain slopes and allow the passage of saltating grains over their surfaces material appears to be shed from the massifs and is concentrated at the crests of nearby bedforms one explanation for these observations is that white rock is an eroded accumulation of compacted or weakly cemented aeolian sediment

thermal infrared emission spectroscopy of anhydrous carbonates the objective of this study is to present the thermal emission spectra of various anhydrous calcite and dolomite series carbonate minerals to illustrate the effect of the structural cation ca 2 mg 2 fe 2 mn 2 zn 2 on shifting the positions of the carbonate absorption bands all of the carbonate mineral emission spectra included in this study exhibit three absorption features related to three specific vibrational modes of the carbonate anion co 3 2 these anion vibrations include the out of plane bend the asymmetric stretch and the in plane bend i e the 2 3 and 4 modes respectively the positions of the absorption band emissivity minima are unique for each carbonate chemistry and are thus diagnostic of mineralogy the average 2 3 and 4 wavenumber positions for the various carbonate minerals are as follows calcite caco 3 883 1523 and 712 cm 1 magnesite mgco 3 901 1572 and 748 cm 1 siderite feco 3 876 1523 and 736 cm 1 rhodochrosite mnco 3 877 1535 and 726 cm 1 smithsonite znco 3 882 1509 and 742 cm 1 dolomite camg co 3 2 894 1547 and 728 cm 1 and kutnahorite camn co 3 2 882 1526 and 716 cm 1 carbonates as a general mineral class crystallize in a variety of geological environments however each specific carbonate mineralogy typically is limited to a narrow range of geologic settings in which it forms thermal infrared emission data to be received from the mars global surveyor thermal emission spectrometer will contain the spectral signature of carbonates if they are present above the detectibility limit on the surface of mars this study presents the spectral information necessary to recognize carbonate as a mineral class as well as identify the specific type of carbonate from thermal emissivity data knowledge of distinct carbonate mineralogy will be useful for interpreting the environmental conditions that were present on mars during the carbonate formation the result of this study is that the major carbonate mineral species calcite dolomite magnesite siderite and smithsonite can be identified from thermal infrared emission data provided moderate 10 cm 1 spectral sampling because of the similarity of absorption band positions between kutnahorite and calcite high 2 cm 1 spectral sampling is required to distinguish kutnahorite moderate spectral sampling data are also sufficient to determine the amount of mg and fe in mg fe solid solution minerals to within 3 5 of the cation abundance

freshwater structure and its seasonal variability off western patagonia abstract climatological hydrographic data for the southeastern pacific from the world ocean atlas show an extended low salinity region associated with high rainfall river runoff along the chilean patagonia coast however the structure and variability of this extensive freshwater area is poorly understood due to the lack of periodic hydrographic observations here we use 15 years of satellite observations in combination with hydrographic data from argo profiling floats to increase our understanding of the freshwater structure and its seasonal variability off western patagonia satellite derived seasonal fields of surface salinity from aquarius sac d and smap soil moisture active passive satellite missions reveal a prominent coastal band of low salinity water year round fresher during spring and summer hydrographic profiles from argo floats confirm this coastal freshening the major content of freshwater is located off central patagonia where the low salinity surface layer dominates the stratification of the upper ocean in contrast the freshwater content plays a minor role in setting up the stratification off northern and southern patagonia a warm surface layer greatly increases the stability of the upper 500 m in the northern sector especially in summer and fall whereas cold temperatures in the southern region tend to damp zonal density gradients and decrease the stratification future studies at interannual scales are suggested considering the melting of patagonian icefields since the 1960s

modern warfare as a significant form of zoogeomorphic disturbance upon the landscape abstract the damage exerted by warfare on the physical landscape is one of many anthropogenic impacts upon the environment bombturbation is a term that describes the impacts of explosive munitions upon the landscape bombturbation like many other forms of zoogeomorphology is a disruptive force capable of moving large amounts of sediments and denuding landscapes to the point where changes in micro and mesotopography have long term implications the long term implication of bombturbative actions depends on the type and duration of explosive device that rendered the disturbance and the geographic context of the landscape disturbed i e cultural and physical factors recovery from bombturbative activity in the context of this research is measured by vegetative regrowth and soil development in cratered disturbances a comparison and contrast between the two battlefields of verdun france and khe sanh vietnam show that bombturbative actions have significantly altered the topography at each location thus influencing surface runoff and processes of soil development principals of the runge pedogenic model or the energy of water moving through the soil profile best explain how the varying climate and parent material at each location influence post disturbance soil development rates whereas the data collected at verdun suggest that explosive munitions have put that landscape on diverging path of development thus rendering it much different post disturbance landscape khe sanh displays much different recovery patterns preliminary research at khe sanh indicates that reforestation and soil development following disturbance are not so much influenced by bombturbative patterns as land use activities in the area of study

main eddy vertical structures observed in the four major eastern boundary upwelling systems in the four major eastern boundary upwelling systems ebus mesoscale eddies are known to modulate the biological productivity and transport near coastal seawater properties toward the offshore ocean however little is known about their main characteristics and vertical structure this study combines 10 years of satellite altimetry data and argo float profiles of temperature and salinity and our main goals are i to describe the main surface characteristics of long lived eddies formed in each ebus and their evolution and ii to depict the main vertical structure of the eddy types that coexist in these regions a clustering analysis of the argo profiles surfacing within the long lived eddies of each ebus allows us to determine the proportion of surface and subsurface intensified eddies in each region and to describe their vertical structure in terms of temperature salinity and dynamic height anomalies in the peru chile upwelling system 55 of the sampled anticyclonic eddies aes have subsurface intensified maximum temperature and salinity anomalies below the seasonal pycnocline whereas 88 of the cyclonic eddies ces are surface intensified in the california upwelling system only 30 of the aes are subsurface intensified and all of the ces show maximum anomalies above the pycnocline in the canary upwelling system 40 of the aes and 60 of the ces are subsurface intensified with maximum anomalies extending down to 800 m depth finally the benguela upwelling system tends to generate 40 50 of weak surface intensified eddies and 50 60 of much stronger subsurface intensified eddies with a clear geographical distribution the mechanisms involved in the observed eddy vertical shapes are discussed

infrared stealthy surfaces why tes and themis may miss some substantial mineral deposits on mars and implications for remote sensing of planetary surfaces 1 infrared spectral observations have yielded many important insights into the nature of mars however spectral effects tied to surface roughness and particle size can make mineral deposits substantially more difficult to detect and identify than is generally known including for current investigations the effects hold for mars and other planets but here we focus on the impact on the exploration of mars laboratory spectra of pure smooth surfaced minerals have previously been used to conclude that the 1996 global surveyor thermal emission spectrometer tes and the 2001 mars odyssey thermal emission imaging system themis will detect a mineral deposit that covers 10 of a pixel those laboratory spectra have formed the foundation for modeling and interpretations of tes themis data and for development of the 2003 mars rover minites here for the first time we compare tes themis foundation data to laboratory field and unique airborne spectra of rough surfaces we demonstrate that substantial well crystalline regional mineral deposits including rock outcrops can be 100 exposed and remain undetected at the sensitivity of tes themis we then detail the physics which apply to all geologic materials previous studies have demonstrated the complicating physical effects for solids versus particulates for a range of minerals including oxides sulfates carbonates and each of the seven silicate classes we identify three cases of spectral behavior that can impact interpretations in case 1 physical effects cause a target to be undetectable by a given infrared instrument infrared stealthy in case 2 variations in spectral contrast mimic abundance variations which confounds abundance mapping in case 3 alteration of the spectral band shape impacts compositional interpretations optically smooth materials will be well represented in tes themis minites identifications conversely if a material forms an optically rough surface or sufficiently small particles on mars then it will be comparatively underrepresented or missed surface roughness occurs on three broad scales and roughness at the grain scale can be a primary variable in whether a mineral is detectable nondetection of certain key minerals e g carbonates can significantly impact geologic and climatic interpretations and landing site selection the tes themis detection threshold may be 10 coverage on the basis of specific laboratory samples but for field measurements that prediction represents an idealized lower bound interpretations built on nondetection should be revisited after defining the uncertainties in detection capabilities for specific instruments as applied to expected mineral surface textures on mars including at the grain scale the impact on future measurement strategies including minites should also be assessed

near coastal circulation in the northern humboldt current system from shipboard adcp data the near coastal circulation of the northern humboldt current system is described analyzing 8700 velocity profiles acquired by a shipboard acoustic doppler current profiler sadcp during 21 surveys realized between 2008 and 2012 along the peruvian coast this data set permits observation of i part of the peru coastal current and the peru oceanic current that flow equatorward in near surface layers close to the coast and farther than 150 km from the coast respectively ii the peru chile undercurrent pcuc flowing poleward in subsurface layers along the outer continental shelf and inner slope iii the near surfacing equatorial undercurrent renamed as ecuador peru coastal current that feeds the pcuc and iv a deep equatorward current referred to as the chile peru deep coastal current flowing below the pcuc a focus in the pcuc core layer shows that this current exhibits typical velocities of 5 10 cm s 1 the pcuc deepens with an increasing thickness poleward consistent with the alongshore conservation of potential vorticity the pcuc mass transport increases from 1 8 sv at 5 s to a maximum value of 5 2 sv at 15 s partly explained by the sverdrup balance the pcuc experiences relatively weak seasonal variability and the confluence of eddy like structures and coastal currents strongly complicates the circulation the pcuc intensity is also affected by the southward propagation of coastally trapped waves as revealed by a strong pcuc intensification in march 2010 coincident with the passage of a downwelling coastal wave associated with a weak el nino event

a quantitative comparison of soil development in four climatic regimes abstract a new quantitative soil development index based on field data has been applied to chronosequences formed under different climatic regimes the four soil chronosequences developed primarily on sandy deposits have some numeric age control and are located in xeric inland merced calif xeric coastal ventura calif aridic las cruces n mex and udic susquehanna valley pa soil moisture regimes to quantify field properties points are assigned for developmental increases in soil properties in comparison to the parent material currently ten soil field properties are quantified and normalized for each horizon in a given chronosequence including two new properties for carbonate rich soils in addition to the eight properties previously defined when individual properties or the combined indexes are plotted as a function of numeric age rates of soil development can be compared in different climates the results demonstrate that 1 the soil development index can be applied to very different soil types 2 many field properties develop systematically in different climatic regimes 3 certain properties appear to have similar rates of development in different climates and 4 the profile index that combines different field properties increases significantly with age and appears to develop at similar rates in different climates the soil development index can serve as a preliminary guide to soil age where other age control is lacking and can be used to correlate deposits of different geographical and climatic regions

a pacific hydrographic section at 88 w water property distribution full depth conductivity temperature depth ctd hydrographic measurements with high horizontal and vertical resolution were made in february april 1993 along a line lying at a nominal longitude of 88 w and extending from southern chile 54 s to guatemala 14 n it crossed five major deep basins southeast pacific chile peru panama and guatemala basins east of the east pacific rise vertical sections of potential temperature salinity potential density oxygen silica phosphate nitrate and nitrite are presented to illustrate the structure of the entire water column some features of interest found in the sections are described and an attempt is made to interpret them in terms of the isopycnal property distributions associated with the large scale ocean circulation these features include various near surface waters observed in the tropical and subtropical regions and the fronts that mark the boundaries of these waters the possible importance of salt fingering to the downward salt transfer from the high salinity subtropical water a shallow thermostad pycnostad developed at 16 18 5 c in the subtropical water low salinity surface water in the subantarctic zone west of southern chile large domains of extremely low oxygen in the subpycnocline layer on both sides of the equator and a secondary nitrite maximum associated with a nitrate minimum in these low oxygen domains high salinity low oxygen high nutrient subpycnocline water that is carried poleward along the eastern boundary by the peru chile undercurrent the subantarctic mode and antarctic intermediate waters middepth isopycnal property extrema observed at the crest of the sala y gomez ridge influences of the north pacific and the north atlantic upon deep waters along the section and the characteristics and sources of the bottom waters in the five deep basins along the section

soil genesis optical dating and geoarchaeological evaluation of two upland alfisol pedons within the tertiary gulf coastal plain abstract much of the gulf coastal plain is mantled by sandy a and e soil horizons overlying finer grained bt horizons researchers have applied optical stimulated luminescence osl dating to a variety of depositional settings such as hillslopes and terraces in an attempt to understand depositional versus pedogenic origins of the sandy horizons and archaeological burial processes these investigations have documented a range of integrity conditions from pristine to highly bioturbated however little work has been conducted in upland summits thus we integrated field morphological descriptions constituent mass balance reconstruction and optical dating to reconstruct the timing and pedogenic pathways of two summit alfisols on the tertiary gulf coastal plain in texas investigations reveal that the sandy a and e horizons and the bt horizons in each pedon are genetically related with textural contrasts resulting from pedogenic processes optical dating revealed highly complex age structures strongly influenced by bioturbation weathering and the presence of coarse clay plus total silt particle sizes pedogenic mixing is extensive in the a and e horizons which effect apparent osl ages

late quaternary variability of sedimentary nitrogen isotopes in the eastern south pacific ocean 1 we present high resolution bulk sedimentary 15n data from the southern edge of the present day oxygen minimum zone of the eastern south pacific the record is interpreted as representing changes in water column nitrogen removal during the last 70 000 years we found significant fluctuations in the isotopic signal that suggest major reorganizations of the oxygen minimum zone at millennial timescales these fluctuations were not related to other millennial scale changes like the northern hemisphere s dansgaard oeschger climate swings or local changes in primary productivity so appear to be dictated by the southern hemisphere s climate rhythm this is preliminarily corroborated by an overall agreement between our 15n data and the sedimentary proxy of ice sheet dynamics in patagonia which is in turn correlated with surface water properties at the midlatitude subduction region of the eastern south pacific intermediate waters finally potential implications on late quaternary changes in atmospheric co2 concentrations are discussed

development of texture contrast soils by a combination of bioturbation and translocation abstract soils and weathering profiles in a wide variety of parent materials and environmental settings exhibit coarse over fine vertical textural contrasts where these cannot be attributed to inherited texture contrasts or erosion deposition the most common explanations are based on translocation eluviation illuviation which removes clays from surface layers and deposits them in the subsoil or bioturbation where preferentially fine material is delivered to the surface by organisms from whence erosional winnowing creates a coarse surface layer in some soils of the lower coastal plain of north carolina u s a neither explanation is sufficient to explain the observed texture contrasts a heuristic model based on a combination of translocation of fine material from surface to subsoil and bioturbation driven delivery and recycling of material to the surface can explain the observed vertical textural contrasts the key elements in the model are coastal plain sediments which include some fine material eluviation illuviation by percolating water delivery of additional fine and mixed grain size material to surface by bioturbation making it available for translocation concentration of fine material originally scattered throughout the parent material in a b horizon and maintenance of vertical moisture fluxes by bioturbation the model is supported by morphological evidence of the key mechanisms argillic horizons that are finer than both the surface layers and underlying parent material evidence that argillic horizon formation is not limited by the rate of clay synthesis and the absence of texture contrasts in nearby soils formed from dune sands which lack fines

late cenozoic marine deposition in the united states atlantic coastal plain related to tectonism and global climate abstract major hiatuses in upper cenozoic marine deposits in the united states atlantic coastal plain are recognized on the basis of molluscan faunal changes at erosional unconformities these hiatuses generally coincided with periods of global cooling and ice sheet formation such hiatuses provide information to supplement global climatic data major hiatuses are recognized within the early miocene 23 20 m y ago at the end of the middle miocene 11 10 m y ago at the end of the late miocene 6 5 5 m y ago at the end of the early pliocene 4 0 2 5 m y ago at the end of the late pliocene 1 9 or 1 8 m y ago within the pleistocene 1 1 0 5 m y ago and several times within the last 0 4 m y estimates of the amount of water contained in ice sheets at different times in the pliocene and pleistocene facilitate calculation of probable minimum sea levels on the coastal plain during different high stands of the sea the altitudes of dated shoreline deposits in the atlantic coastal plain show that the amount of uplift in the cape fear area has averaged at least 1 3 cm per 1000 years since the beginning of pliocene time the coastal plain of georgia has apparently experienced relatively little vertical deformation during this same time

controls on sedimentary nitrogen isotopes along the chile margin chilean margin sedimentary n isotope records have been the focus of paleoceanographic studies examining the extent of water column denitrification in the eastern south pacific in the past here we use 15n 14n of nitrate and surface sedimentary n along the chilean coast to investigate the relative contributions of water column denitrification and surface nitrate assimilation by phytoplankton to the sedimentary n isotope record off northern and central chile subsurface enrichment of 15no3 is associated with the lowest oxygen concentrations and maximum nitrate deficits the product of water column denitrification locally at 21 s and through the transport of denitrified waters to the south while elevated the 15n of pycnocline nitrate shows no distinct trend with distance from the omz and is nearly homogenous within the shallow subsurface layer presumably due to lateral circulation along the margin moreover an isotopically depleted and relatively uniform layer exists within the shallow subsurface possibly as a result of the remineralization of newly fixed nitrogen that may work to further homogenize the 15n of the upwelling nitrate whereas the high 15n of sedimentary n in the region is clearly a product of denitrification and its isotopic imprint on nitrate along the margin the northward increase in sedimentary 15n from higher southern latitudes also reflects the degree of surface layer nitrate consumption by phytoplankton the northward increase in sedimentary 15n corresponds to a regional decrease in the surface nitrate concentration and isotopic fractionation during nitrate assimilation is apparent in shallow nitrate 15n a comparison of the 15n in shallow subsurface nitrate and sedimentary n suggests that north of 30 s nearly complete nitrate consumption causes the 15n of sediments to converge on that of the nitrate supply such that denitrification should be the dominant signal in downcore 15n records from these latitudes moreover the lateral homogeneity of the denitrification signal in the subsurface within this region suggests that such records will provide robust reconstructions of denitrification intensity

relative age dating of transported regolith and application to study of landform evolution in the appalachians abstract surficial deposits in the appalachians generally are thin discontinuous and difficult to date in the absence of numerical dates particularly for older deposits relative age indices based on degree of weathering and soil development have been used to distinguish and correlate deposits of different ages a favorite locale of relative age studies has been stream terraces where chronosequences have been developed to shed light on the relationship between time and weathering soil development the lack of applicable numerical dating techniques has led some researchers to establish relative chronosequences in which height of stream or fan terraces above modern river level arl serves as a proxy for time approximate incision rates can then be used to estimate numerical ages of the deposits relative age correlations between the weathering indices on the terraces and comparable indices on dated deposits on the coastal plain and in nearby glaciated regions suggest that ages so estimated are the right order of magnitude relative age indices show correlations with height arl that are as high as those with time perhaps because more data sets are available for relative chronosequences than for true chronosequences analogous relative age sequences can be established for alluvial fans and even for hillslope colluvium many weathering indices have been employed but weathering rind thickness on mafic to intermediate clasts has proved to be a particularly consistent and useful parameter in addition to showing how weathering and soil development progress over time relative age dating has shed light on the manner in which landforms evolve along some rivers for example the areal extent of old highly weathered alluvium far exceeds that of younger alluvium suggesting that formerly floodplains and low terraces were much more extensive than at present in addition the manner in which weathering indices on some river terrace sequences vary with height arl suggests that incision rate has changed through time relative age mapping of alluvial fans produces a map pattern of older and younger fan surfaces that allows the sequence of fan development to be inferred in one case suggesting a scenario different from those previously described for fans mapping also shows that the relative abundance of young intermediate and old fan surfaces varies greatly from one area to another several studies have demonstrated clustering of relative age values into a small number of groups suggesting temporal grouping and thus episodic deposition on fans regression of weathering rind thickness against height above modern drainageways of remnant fan surfaces in two areas suggests that fans are being incised more rapidly in one area than in another relative age of hillslope colluvium also aids geomorphic interpretation young brown colluvium is much more common than old red colluvium near the glacier border where red colluvium rarely occurs at the surface but typically is covered by brown colluvium probably mobilized during the late pleistocene distant from the ice margin however red colluvium is extensively exposed on interfluves relatively stable hillslopes can also be distinguished from active ones in this manner for example colluvium on hillslope noses is somewhat more weathered than that on hollow floors and sideslopes

a different perspective for the mars rover opportunity site fine grained consolidated hematite and hematite coatings 1 since 2001 there have been two parallel interpretations of mars global surveyor thermal emission spectrometer tes observations of sinus meridiani which are 1 coarse grained gray hematite is the only spectral match and 2 fine grained hematite with particles closer than wavelength fine intimate hematite e g coating ferricrete is a better match but coarse hematite is also viable the tes team interpreted the spectra as consistent only with a large deposit 750 km 350 km of coarse hematite 5 10 m grain size coarse hematite is considered strong evidence for longstanding water which led to the decision to land the rover opportunity there on the other hand the aerospace lpi remote sensing team argued that fine intimate hematite can better match tes spectra a thin coating 5 10 m thick and a low exposure 5 could cause the observed signatures the distinction is important because 1 it is unknown whether fine grained hematite implies abundant water 2 fine intimate hematite may explain the non detection of coexisting aqueous alteration minerals and the lack of hematite wind streaks 3 current hematite abundance maps may instead map the surface texture 4 coatings may be of astrobiology interest 5 studies are needed to determine whether visible infrared spectra can definitively distinguish fine intimate from coarse hematite

vertical structure of mesoscale eddies in the eastern south pacific ocean a composite analysis from altimetry and argo profiling floats 1 the mean vertical structure of mesoscale eddies in the peru chile current system is investigated by combining the historical records of argo float profiles and satellite altimetry data a composite average of 420 526 profiles acquired by argo floats that surfaced into cyclonic anticyclonic mesoscale eddies allowed constructing the mean three dimensional eddy structure of the eastern south pacific ocean key differences in their thermohaline vertical structure were revealed the core of cyclonic eddies ces is centered at 150 m depth within the 25 2 26 0 kg m 3 potential density layer corresponding to the thermocline in contrast the core of the anticyclonic eddies aes is located below the thermocline at 400 m depth impacting the 26 0 26 8 kg m 3 density layer this difference was attributed to the mechanisms involved in the eddy formation while intrathermocline ces would be formed by instabilities of the surface equatorward coastal currents the subthermocline aes are likely to be shed by the subsurface poleward peru chile undercurrent in the eddy core maximum temperature and salinity anomalies are of 1 c and 0 1 with positive negative values for aes ces this study also provides new insight into the potential impact of mesoscale eddies for the cross shore transport of heat and salt in the eastern south pacific considering only the fraction of the water column associated with the fluid trapped within the eddies each ce and ae has a typical volume anomaly flux of 0 1 sv and yields to a heat and salt transport anomaly of 1 3 1011 w and 3 8 103 kg s 1 respectively

the ventilation of the world s oceans maps of the potential vorticity field abstract maps of potential vorticity q within four different density layers are presented for the north and south atlantic north and south pacific and indian oceans potential vorticity is evaluated as f 0 z a prescription that is valid for large slow scales and that allows its mapping from hydrographic data alone here f is the coriolis frequency p0 the potential density and z the vertical coordinate it is shown that the character of a layer within the thermocline of a subtropical gyre will vary greatly depending on the extent to which the layer is isolated from surface boundary conditions and forcing fluid particles recirculating within ventilated layers have their potential vorticity and other properties reset with virtually every circuit round the gyre when they pass through the outcrop zone by contrast particles within unventilated or dynamically isolated layers have time to share their properties with neighboring particles and approach a common homogenized state the north

meridional volume transport in the south pacific mean and sam related variability the large increase in upper ocean sampling during the past decade enables improved estimation of the mean meridional volume transport in the midlatitude south pacific and hence of the climatically important meridional overturning circulation transport is computed using argo float profile data for geostrophic shear and trajectory data for reference velocities at 1000 m for the period 2004 2012 the mean geostrophic transport across 32s is 20 6 6 0 sv in the top 2000 m of the ocean from west to east this includes the southward east australian current 23 3 2 9 sv its northward recirculation 16 3 3 6 sv the broad interior northward flow 18 4 4 1 sv and the net northward flow 9 2 2 2 sv in opposing currents in the eastern pacific the basin integrated geostrophic transport includes 7 3 0 9 sv of surface and thermocline waters 4 9 1 0 sv of subantarctic mode water and 4 9 1 4 sv of antarctic intermediate water interannual variability in volume transport across 32s in the south pacific shows a southern annual mode signature characterized by an increase during the positive phase of the southern annular mode and a decrease during the negative phase maximum amplitudes in geostrophic transport anomalies seen in the east australian current and east australian current recirculation are consistent with wind stress curl anomalies near the western boundary key points improved meridional volume transport in the south pacific using argo eac transport variability tied to the sam published 2014 this article is a u s government work and is in the public domain in the usa

isotopic evidence for complex biogeochemical cycling of cd in the eastern tropical south pacific abstract over the past decades observations have confirmed decreasing oxygen levels and shoaling of oxygen minimum zones omzs in the tropical oceans such changes impact the biogeochemical cycling of micronutrients such as cd but the potential consequences are only poorly constrained here we present seawater cd concentrations and isotope compositions for 12 depth profiles at coastal nearshore and offshore stations from 4 s to 14 s in the eastern tropical south pacific where one of the world s strongest omzs prevails the depth profiles of cd isotopes display high 114 110 cd at the surface and decreasing 114 110 cd with increasing water depth consistent with preferential utilization of lighter cd isotopes during biological uptake in the euphotic zone and subsequent remineralization of the sinking biomass in the surface and subsurface ocean seawater displays similar 114 110 cd signatures of 0 47 0 23 to 0 82 0 05 across the entire eastern tropical south pacific despite highly variable cd concentrations between 0 01 and 0 84 nmol kg this observation best explained by an open system steady state fractionation model contrasts with previous studies of the south atlantic and south pacific oceans where only cd deficient waters have a relatively constant cd isotope signature for the subsurface to about 500 m depth the variability of seawater cd isotope compositions can be modeled by mixing of remineralized cd with subsurface water from the base of the mixed layer in the intermediate and deep eastern tropical south pacific 500 m seawater cd and 114 110 cd appear to follow the distribution and mixing of major water masses we identified modified aaiw of the etsp to be more enriched in cd than aaiw from the source region whilst both water masses have similar 114 110 cd a mass balance estimate thus constrains a 114 110 cd of between 0 38 and 0 56 for the accumulated remineralized cd in the etsp nearly all samples show a tight coupling of cd and po4 concentrations whereby surface and deeper waters define two distinct linear trends however seawater at a coastal station located within a pronounced plume of h2s is depleted in cd and features significantly higher 114 110 cd this signature is attributed to the formation of authigenic cds with preferential incorporation of lighter cd isotopes the process follows a rayleigh fractionation model with a fractionation factor of 114 110 cd seawater cds 1 00029 further deviations from the deep cd po4 trend were observed for samples with o2

melting of the patagonian ice sheet and deglacial perturbations of the nitrogen cycle in the eastern south pacific local 230 th normalized biogenic vertical fluxes from the chilean continental margin they document in detail the sharp transition from relatively low wcd rates during the last glacial maximum lgm to high ones during the deglaciation and holocene but give no evidence that the glacial interglacial difference of wcd could have been caused by changes in local primary productivity furthermore we found no evidence that changes in ventilation due to samw formation could explain the nitrogen isotope record we present evidence for an alternative mechanism related to the melting of the patagonian ice sheet pis which is consistent with recent published proxy data and the regional physical oceanography

albeluvisol development with time in loamy marine sediments of southern norway abstract this paper reports a study on soil development in loamy marine sediments on both sides of the oslofjord vestfold ostfold this region has been subject to steady glacio isostatic uplift during the whole holocene hence land surface age continuously increases from the coast inland several sea level curves based on radiocarbon datings enable estimation of land surface age for all locations clay illuviation starts in less than 1650 years e horizons become lighter with age but their lower boundary stays around 40 cm for more than 10 000 years albeluvic tongues develop between 4600 and 6200 years initially they form along intersections of cracks as preferential flow and leaching along the cracks continues the tongues increase in length and width progressively consuming the prisms between the cracks in the upper bt horizon the fe d fe t ratios weighted means of the upper meter show a clear linear increase with soil age and may be used for pedo dating i e for estimating the ages of non dated land surfaces covered with similar sediments in contrast the logarithmic decrease of base saturation and ph with rapid changes in the first time but only very slight changes between 2000 and 10 000 years makes these parameters unsuitable for pedo dating

a comparison of mineralogical techniques and potassium adsorption isotherm analysis for relative dating and correlation of late quaternary soil chronosequences abstract the utility of potassium adsorption isotherm analysis kia for relative dating and correlation of soil chronosequences was assessed by a comparison with some widely used mineralogical techniques the soils studied near detroit michigan are brown 10yr calcareous entisols developed in holocene 4 ka floodplain sediments and inceptisols and alfisols with redder 7 5yr 5yr cambic and argillic b horizons formed on late pleistocene 14 5 12 4 ka fluvial terraces fluvial paleochannels and paleoshorelines beach ridges of proglacial lakes the soils show a positive linear correlation between soil age and clay content depth of carbonate leaching and fe oxide accumulation in contrast the duration of soil formation is too short for variations in heavy mineral frequencies to discriminate soil age reliably scanning electron microscopy shows that chemical weathering stage is indicated by progressive etching and pitting of calcite apatite and amphibole with increasing soil age k isotherms are linear or slightly curvilinear indicating that ion exchange is dominant over specific adsorption a statistically significant linear correlation between k distribution constant and soil age attributed to progressive weathering of mica suggests that kia is useful for relative dating of genetically related soils once a well dated chronosequence is established kia produces results comparable to or better than mineralogical techniques however soil morphology and a clay redness index are more effective than mineralogical and chemical techniques for interchronosequence correlation

alluvial soil chronosequence in the inner coastal plain central virginia abstract a chronological sequence of soils formed on a series of alluvial depositional surfaces ranging in age from late middle miocene to late pleistocene was characterized to clarify soil geomorphic relations and provide a basis for allostratigraphic subdivision of the inner coastal plain on quaternary river terraces ultic hapludalfs containing abundant weatherable mineral species and clast types are estimated to have formed in 60 000 120 000 yr whereas typic hapludults greatly depleted in weatherable minerals and showing strong weathering of clast types are estimated to be 700 000 1 600 000 yr old typic paleudults with incipient plinthite duripan and ferricrete development characterize interfluves that have been little eroded since early pliocene time 3 4 5 3 myr ago typic plinthic paleudults with intense weathering of siliceous clasts and moderate to strong duripan and ferricrete development are found on surfaces that formed near the beginning of late miocene time 10 8 13 0 myr ago chemical weathering in the chronosequence may be classified into three progressive stages 1 decomposition of unstable sand and silt sized minerals into a mixed stable unstable clay mineral suite stable fe al si bulk chemical composition 107 yr not all soil properties show unidirectional development nor is a steady state of pedon development observed even after approximately 107 yr of chemical weathering soil development in the chronosequence is episodic the transition from one phase to the next is marked by a change in rate and sometimes a reversal in the direction of development of one or more soil properties

quaternary climates and sea levels of the u s atlantic coastal plain uranium series dating of corals from marine deposits of the u s atlantic coastal plain coupled with paleoclimatic reconstructions based on ostracode marine and pollen continent data document at least five relatively warm intervals during the last 500 000 years on the basis of multiple paleoenvironmental criteria we determined relative sea level positions during the warm intervals relative to present mean sea level were 7 5 meters at 188 000 years ago 7 5 1 5 meters at 120 000 years ago 6 5 3 5 meters at 94 000 years ago and 7 3 meters at 72 000 years ago the composite sea level chronology for the atlantic coastal plain is inconsistent with independent estimates of eustatic sea level positions during interglacial intervals of the last 200 000 years hydroisostatic adjustment from glacial interglacial sea level fluctuations lithospheric flexure and isostatic uplift from sediment unloading due to erosion provide possible mechanisms to account for the discrepancies alternatively current eustatic sea level estimates for the middle and late quaternary may require revision

mapping alluvial fans in death valley california using multichannel thermal infrared images we have mapped alluvial fans in death valley california using nasa s 8 12 m six channel airborne thermal infrared multispectral scanner tims we are able to recognize both composition and relative age differences age unit boundaries are generally consistent with those obtained by conventional mapping composition was verified by field investigation and comparison with existing geologic maps bedrock and its young derived fan gravels have similar emissivities the original composition of the fans is modified by differential erosion and weathering permitting relative age mapping with tims

quaternary deposits and landscape evolution of the central blue ridge of virginia abstract a catastrophic storm that struck the central virginia blue ridge mountains in june 1995 delivered over 775 mm 30 5 in of rain in 16 h the deluge triggered more than 1000 slope failures and stream channels and debris fans were deeply incised exposing the stratigraphy of earlier mass movement and fluvial deposits the synthesis of data obtained from detailed pollen studies and 39 radiometrically dated surficial deposits in the rapidan basin gives new insights into quaternary climatic change and landscape evolution of the central blue ridge mountains the oldest depositional landforms in the study area are fluvial terraces their deposits have weathering characteristics similar to both early pleistocene and late tertiary terrace surfaces located near the fall zone of virginia terraces of similar ages are also present in nearby basins and suggest regional incision of streams in the area since early pleistocene late tertiary time the oldest debris flow deposits in the study area are much older than wisconsinan glaciation as indicated by 2 5yr colors thick argillic horizons and fully disintegrated granitic cobbles radiocarbon dating indicates that debris flow activity since 25 000 ybp has recurred on average at least every 2500 years the presence of stratified slope deposits emplaced from 27 410 through 15 800 ybp indicates hillslope stripping and reduced vegetation cover on upland slopes during the wisconsinan glacial maximum regolith generated from mechanical weathering during the pleistocene collected in low order stream channels and was episodically delivered to the valley floor by debris flows debris fans prograded onto flood plains during the late pleistocene but have been incised by holocene stream entrenchment the fan incision allows holocene debris flows to largely bypass many of the higher elevation debris fan surfaces and deposit onto the topographically lower surfaces these episodic high magnitude storm events are responsible for transporting approximately half of the sediment from high gradient low order drainage basins to debris fans and flood plains

an exchange window for the injection of antarctic intermediate water into the south pacific antarctic intermediate water aaiw occupies the intermediate horizon of most of the world oceans formed in the southern ocean it is characterized by a relative salinity minimum with a new denser in situ national oceanographic data center dataset the authors have reanalyzed the export characteristics of aaiw from the southern ocean into the south pacific ocean these new data show that part of the aaiw is exported from the subpolar frontal region by the large scale circulation through an exchange window of 10 width situated east of 90 w in the southeast corner of the pacific basin this suggests the origin of this water to be in the antarctic circumpolar current a set of numerical modeling experiments has been used to reproduce these observed features and to demonstrate that the dynamics of the exchange window is controlled by the basin scale meridional pressure gradient the exchange of aaiw between the southern and pacific oceans must therefore be understood in the context of the large basin scale dynamical balance rather than simply local effects

the influence of water mass mixing on the dissolved si isotope composition in the eastern equatorial pacific silicon isotopes are a powerful tool to investigate the cycling of dissolved silicon si in this study the distribution of the si isotope composition of dissolved silicic acid 30si oh 4 was analyzed in the water column of the eastern equatorial pacific eep where one of the globally largest oxygen minimum zones omzs is located samples were collected at 7 stations along two meridional transects from the equator to 14 s at 85 50 w and 82 00 w off the ecuadorian and peruvian coast surface waters show a large range in isotope compositions 30si oh 4 2 2 to 4 4 with the highest values found at the southernmost station at 14 s this station also revealed the most depleted silicic acid concentrations 0 2 mol kg which is a function of the high degree of si utilization by diatoms and admixture with waters from highly productive areas samples within the upper water column and the omz at oxygen concentrations below 10 mol kg are characterized by a large range in 30si oh 4 which mainly reflects advection and mixing of different water masses even though the highly dynamic hydrographic system of the upwelling area off peru does not allow the identification of clear si isotope signals for distinct water masses therefore we cannot rule out that also dissolution processes have an influence on the 30si oh 4 signature in the subsurface water column deep water masses 2000 m in the study area show a mean 30si oh 4 of 1 2 0 2 which is in agreement with previous studies from the eastern and central pacific comparison of the new deep water data of this study and previously published data from the central pacific and southern ocean reveal substantially higher 30si oh 4 values than deep water signatures from the north pacific as there is no clear correlation between 30si oh 4 and silicic acid concentrations in the entire data set the distribution of 30si oh 4 signatures in deep waters of the pacific is considered to be mainly a consequence of the mixing of several end member water masses with distinct si isotope signatures including lower circumpolar deep water lcdw and north pacific deep water npdw

a lithosequence of soils in extremely gravelly dolomitic parent materials bois blanc island lake huron abstract eight extremely gravelly pedons on bois blanc island were characterized and pathways and processes of genesis were examined the soils are developed in dolomitic gravels and cobbles and contain 1 50 mean 15 fine earth most pedons are in coarse loamy or skeletal particle size families in extremely gravelly parent materials with less than 5 fine earth b horizons have not formed accumulation of organic matter on the surface and between coarse fragments in the upper solum is the main pedogenic process in such soils borofolists in other soils distinct eluvial and illuvial zones are present with organic carbon silts fine sands and caco 3 being the primary constituents undergoing translocation quantity and mineralogical composition of the fine earth appear to alter the pathways of pedogenesis as the amount of fine earth and the percentage of non carbonate materials derived from crystalline rocks increase cambic horizons with spodic morphology may develop

marine radiocarbon reservoir effect along the northern chile southern peru coast 14 24 s throughout the holocene abstract through an extensive sampling and dating of pairs of associated shells and charcoal fragments combined with reanalysis of all the available previous data we reconstruct the evolution throughout the holocene of the regional marine radiocarbon reservoir effect r values along the northern chile southern peru area 14 24 s after elimination of the cases in which the terrestrial component yielded older ages than the marine shells to which they were associated the study is based upon data from 47 pairs of associated marine and terrestrial material our results suggest major changes in both the magnitude and variability range of r during the whole holocene period 1 between 10 400 and 6840 cal yr bp high values 511 278 yr probably result from a strengthened se pacific subtropical anticyclone and shoaling of equatorial subsurface waters during intensified upwelling events 2 between 5180 and 1160 cal yr bp lower values 226 98 yr may reflect a major influence of subtropical water and diminished coastal upwelling processes 3 during the last thousand years high values between 355 105 and 253 207 yr indicate an increased influence of 14 c depleted water masses and of enso for the early twentieth century a r value of 253 207 yr was calculated

benthic megafaunal and demersal fish assemblages on the chilean continental margin the influence of the oxygen minimum zone on bathymetric distribution abstract benthic megafaunal and demersal fish assemblages were sampled in three areas off chile during the german chilean expedition puck so 156 onboard the r v sonne from march to may 2001 at depths ranging from 120 to 2201 m these samples taken with an agassiz trawl are among the deepest ever taken in chilean waters a total of 147 species were recorded mainly decapod crustaceans galatheidae pandalidae crangonidae gastropods trochidae muricidae volutidae ophiuroids asteronychidae gorgonocephalidae ophiolepididae ophiurinae asteroids pterasteridae solasteridae goniopectinidae polychaetes onuphidae aphroditidae maldanidae and demersal fish macrouridae ipnopidae squalidae species richness and rarefaction analyses suggest that the fauna was undersampled from the 147 species identified in this study 36 species 24 5 occurred only once and another 24 species occurred only twice 16 3 depth and dissolved oxygen levels were found to be the main factors influencing megafaunal changes along the continental shelf and in bathyal areas as indicated by principal component and pearson s correlation analyses some species appear to be limited to distinct areas in the upper and lower bathyal zones whereas other species have a wider range extending from the continental shelf to lower bathyal zones biogeographic relations exist with the pacific south atlantic and southern oceans but the latter seem to be weaker than would be expected considering the connection by antarctic intermediate water

white rock an eroded martian lacustrine deposit the existence and location of ancient lake sites and sediments have important implications for martian paleoclimate and exobiology white rock an enigmatic crater interior deposit may be the eroded remnant of such a lacustrine deposit stereogrammetric analysis of newly processed viking images allows better determination of the dimensions of white rock 12 5 x 15 km thickness 180 to 540 m volume 40 km 3 reveals differences in erosion patterns that may reflect differences in depositional environment and allows the identification in or on the crater wall of a possible source region of the high albedo white rock material if white rock is the remnant of a once larger deposit then open system circulation may have been required to deliver the required quantity of evaporites

divergent evolution and the spatial structure of soil landscape variability abstract the spatial structure of soil variability at the landscape scale was examined on adjacent geomorphic surfaces dating from 80 to 200 ka in eastern north carolina the purpose was to determine whether there is evidence at broader scales distances of 102 104 m for the divergent evolution observed in the field at very detailed scales distances of 100 102 m the state probability function spf which measures spatial dependence for categorical environmental data along a transect was applied to soil series mapped at a 1 24 000 scale the older talbot terrace and younger pamlico terrace surfaces showed distinctly different patterns of spatial variability the range of spatial dependence was shorter on the older surface about 200 vs 300 m and the spf was higher at any given distance indicating more variability the spf for the pamlico surface also indicates a periodicity related to fluvial dissection of the landscape which is not readily detectable on the talbot transect despite its greater degree of dissection the results confirm earlier field studies which suggest that pedogenesis is marked by divergence whereby differences in initial conditions or local perturbations persist and increase to produce a more variable soil cover

on the wind driven circulation of the south pacific ocean abstract a layered model of the study circulation in the south pacific ocean is constructed along the lines of luyten pedlosky and stommel and driven by the mean annual wind stress distributions computed by hellerman and rosenatein the results of the model agree quite well with published maps of topography of density surfaces and circulation best agreement is found in the deeper layers the deepest modeled layer of density range 26 90 0 27 30 which contains the core layer of the antarctic intermediate water transports northwards some 14 sv 1 sv 106 m3 s 1 between new zealand and south america of this about three quarters comes from the west in an intense zonal jet that rounds the southern tip of new zealand and quickly fans out from the boundary current along those islands into the anticyclonic gyre some 5 sv returns southwards in the australian boundary current much of the anticyclonic gyre in the western south pacific is taken up by a shadow zone formed in the shelter of new zealand

impact of a coastal trapped wave on the near coastal circulation of the peru upwelling system from glider data alongshore velocity data from a glider repetitive section off the coast of peru 14 s are used to study the cross shore structure and temporal variability of the peru current system during a 5 week period in april may 2010 besides providing substantial information on the surface frontal jet associated with the peru coastal current and the surfacing peru chile undercurrent that flows poleward trapped on the continental shelf and slope the glider data reveal the presence of an intense deep equatorward current which transports up to 2 5 sv the dynamics of this current are investigated using an eddy resolving regional model the variability of the vertically sheared alongshore flow is shown to be related to the passage of a poleward propagating coastal trapped wave likely of equatorial origin solutions from a two dimensional linear coastal wave model suggest that the alongshore current observed vertical structure is associated with the second and third baroclinic modes of the coastal trapped wave

chromophoric and fluorescent dissolved organic matter in and above the oxygen minimum zone off peru key points two amino acid like and three humic like fdom components were found in and above the oxygen minimum zone off the coast of peru the distribution of cdom and amino acid like fdom covaried with chl a suggesting phytoplankton as their major source presence of dom microbial reworking and dom release by anoxic sediment was illustrated by the distribution of humic like fdom as a result of nutrient upwelling the peruvian coastal system is one of the most productive regions in the ocean sluggish ventilation of intermediate waters characteristic for the eastern tropical south pacific etsp and microbial degradation of a high organic matter load promotes deoxygenation at depth dissolved organic matter dom plays a key role in microbial respiration and carbon cycling but little is known on dom distribution and cycling in the etsp dom optical properties give important insights on dom sources structure and biogeochemical reactivity here we present data and a conceptual view on distribution and cycling of chromophoric cdom and fluorescent fdom dom in and above the oxygen minimum zone omz off peru five fluorescent components were identified during parafac analysis highest intensities of cdom and of the amino acid like fluorescent component c3 occurred above the omz and coincided with maximum chl a concentrations suggesting phytoplankton productivity as major source high intensities of a marine humic like fluorescent component c1 observed in subsurface waters indicated in situ microbial reworking of dom fdom release from inner shelf sediment was determined by seawater analysis and continuous glider sensor measurement and included a humic like component c2 with a signature typical for terrestrially derived humic acids upwelling supplied humic like substances to the euphotic zone photo reactions were likely involved in the production of a humic like fluorescent component c5 our data show that variable biological and physical processes need to be considered for understanding dom cycling in a highly dynamic coastal upwelling system like the etsp off peru

effects of human disturbance and cryoturbation on soil iron and organic matter distributions and on carbon storage at high elevations in the cairngorm mountains scotland soil profiles were sampled at 43 sites on granitic parent material at altitudes ranging from 970 to 1300 m in the cairngorm mountains scotland many soils under undisturbed vegetation showed evidence of iron and organic matter translocation with distinctive bh or bs horizons approximately 50 of the sites sampled had no or partial vegetation cover due either to human activity trampling or active geomorphic processes such as cryoturbation on patterned ground exposed cols and summit ridges were most heavily affected by trampling with extensive areas of path development and some erosion trampling was principally associated with loss of the upper soil horizons and cryoturbation processes with disturbance of horizon development median total organic matter at the vegetated sites ranged from 4 8 to 22 0 kg m y2 with a median of 9 5 kg m y2 there was significantly less total organic matter at the unvegetated sites with median of 4 6 kg m y2 and range from 1 5 to 11 9 kg m y2 there was little difference in total organic matter between sites where vegetation disturbance was due to human trampling or to cryoturbation q 2000 elsevier science b v all rights reserved

exploring for a record of ancient martian life the immediate task facing exopaleontology is to define a strategy to explore mars for a fossil record during the decade long exploration program that lies ahead consideration of the quality of paleontological information preserved under different geological conditions is important if we are to develop a strategy with broad applicability the preservation of microbial fossils is strongly influenced by the physical chemical and biological factors of the environment which acting together determine the types of information that will be captured and retained in the rock record in detrital sedimentary systems preservation is favored by rapid burial in fine grained clay rich sediments in chemical sedimentary systems preservation is enhanced by rapid entombment in fine grained chemical precipitates for long term preservation host rocks must be composed of stable minerals that are resistant to chemical weathering and that form an impermeable matrix and closed chemical system to protect biosignatures from alteration during subsequent diagenesis or metamorphism in this context host rocks composed of highly ordered chemically stable mineral phases like silica e g cherts or phosphate e g phosphorites are especially favored such lithologies tend to have very long crustal residence times and along with carbonates and shales are the most common host rocks for the precambrian microfossil record on earth although we make the defensible assumption that mars was more like the earth early in its history clearly the geological and historical differences between the two planets are many such differences must be carefully considered when adapting an earth based strategy to mars

global observations of submesoscale coherent vortices in the ocean abstract subsurface intensified anticyclones are ubiquitous in the ocean yet their impact on the large scale transport of heat salt and chemical tracers is poorly understood these submesoscale coherent vortices scvs can trap and advect waters thousands of kilometers away from the formation region providing a transport pathway that is unresolved by low resolution earth system models however knowledge of the importance of these eddies for the large scale circulation is hindered by the lack of systematic observations here we take advantage of the global network of argo floats to identify occurrences of these eddies which appear as weakly stratified anomalous water masses with gaussian shaped vertical structures we develop a general algorithm to detect subsurface eddies that have propagated away from their source region and apply it to the database of argo float profiles resulting in roughly 4000 detections from more than 20 years of observations we further group detections into regional populations to identify hot spots of generation and mechanisms of formation analysis of regional scv statistics reveals important sites of scv generation in eastern boundary upwelling systems marginal sea overflows and mode water formation regions along major open ocean fronts because of the heat and salt anomaly contained within their cores scv could leave a significant imprint on the hydrographic properties of water masses in regions of high scv density

are there carbonate deposits in the valles marineris mars the thick sequences of layered deposits found in the valles marineris have recently been determined by s s nedell s w squyres and d w andersen 1987 icarus 70 409 441 to contain a minimum of 105 km3 of material we suggest that this material could be derived from the precipitation of 30 mbar of atmospheric co2 as carbonates in lakes as surface temperatures fell on mars the presence of an insulating ice cover would have allowed liquid water to exist fed by transitory surface melting atmospheric co2 would have accumulated in such lakes enhancing carbonate precipitation support for this hypothesis comes from processes that occur in the perennially frozen lakes in the dry valleys of antarctica where the mean temperature is 253 k and the lake water is supersaturated with atmospheric gases a search of the recently reissued mariner 6 7 infrared spectrometer data in the wavelength region between 2 and 6 m failed to confirm the presence of carbonates due to the fact that no spectral footprints appear to directly overlie the layered deposits and that deposits may be blanketed by an eolian mantle this negative result is inconclusive we feel that the canyon deposits are still a prime site for future searches for carbonates on mars

sulfate mineralogy of fumaroles in the salton sea geothermal field imperial county california abstract the salton trough lies in the transition between the san andreas fault and oblique spreading centers and transform faults in the gulf of california the salton sea geothermal field is the northernmost expression of those spreading centers in 2007 two ammonia emitting fumarole fields that had been submerged beneath the salton sea were exposed for the first time in nearly 50 years as the sea level continued to drop these fields have developed a number of boiling pools mud pots gryphons and a unique suite of ammonium sulfate minerals these have been studied over time with long wave infrared remote sensing coupled with ground truth surveys backed by laboratory analyses of the minerals many vents lie at the center of concentric rings of mineralization with systematic occurrence of different minerals from center to edge three semi concentric zones fumarole transition and evaporite have been defined with respect to ammonia emitting vents and bubbling pools the scale of these zones range from several meters localized around individual vents to that of the fumarole fields as a whole the fumarole zone is closest to the vents and locally contains cavernous sulfur crystals and significant deposits of gypsum mascagnite boussingaultite and other ammonium sulfates the transition zone comprises a dark brown surficial band of inconspicuous sodium nitrate underlain by anhydrite bassanite that is thought to have formed by ammonia oxidizing microbes interacting with the ammonium sulfates of the outer fumarole zone the evaporite zone is the outermost and contains blodite thenardite and glauberite which are typical of the sulfates associated with the shoreline of the salton sea remote sensing has shown that the mineral zones have remained relatively stable from 2013 to 2017 with minor variations depending on rainfall temperature and levels of agricultural runoff

evidence for montmorillonite or its compositional equivalent in columbia hills mars 1 during its exploration of the columbia hills the mars exploration rover spirit encountered several similar samples that are distinctly different from martian meteorites and known gusev crater soils rocks and sediments occurring in a variety of contexts and locations these independence class samples are rough textured iron poor equivalent feo 4 wt have high al si ratios and often contain unexpectedly high concentrations of one or more minor or trace elements including cr ni cu sr and y apart from accessory minerals the major component common to these samples has a compositional profile of major and minor elements which is similar to the smectite montmorillonite implicating this mineral or its compositional equivalent infrared thermal emission spectra do not indicate the presence of crystalline smectite one of these samples was found spatially associated with a ferric sulfate enriched soil horizon possibly indicating a genetic relationship between these disparate types of materials compared to the nearby wishstone and watchtower class rocks major aqueous alteration involving mineral dissolution and mobilization with consequent depletions of certain elements is implied for this setting and may be undetectable by remote sensing from orbit because of the small scale of the occurrences and obscuration by mantling with soil and dust

quantitative compositional analysis using thermal emission spectroscopy application to igneous and metamorphic rocks the mineral composition of a suite of igneous and metamorphic rocks was determined using the thermal infrared emission spectra of these rocks in a linear spectral deconvolution algorithm this algorithm assumes that the infrared spectrum of each rock is a linear mixture of the component mineral spectra weighted by volume abundance a diverse suite of 36 common rock forming and accessory minerals was used in the deconvolution the model was tested by comparing the mineralogy derived from the infrared spectrum with petrographically estimated abundances for 45 igneous and 51 metamorphic rock samples the mineral abundances derived from these two techniques agree to within 67 15 for the primary minerals feldspar pyroxene quartz and calcite dolomite and 69 17 for secondary minerals such as micas and amphiboles these differences are comparable to the error for traditional thin section mode estimates which are 65 15 for major minerals and 5 for minor minerals the detection limit for the primary and secondary minerals found in the rocks analyzed ranged from 5 to 10 each major rock type studied here was easily distinguished by its spectral characteristics the best results in both the qualitative determination of the rock type and dominant minerals and the quantitative reproduction of absorption features and mineral composition were obtained for igneous rock samples for metamorphic rocks pelite and quartzo feldspathic samples gave slightly better results than calcareous or mafic samples a controlled analysis in which the end member suite was reduced based on an initial estimate of the rock type only improved the results by several percent for most primary and secondary minerals the quality of the obtained results demonstrates that a linear deconvolution of infrared emission spectra provides an accurate rapid technique for determining the quantitative mineral composition of rock samples in a laboratory and has application to future in situ measurements

presence and detection of carbonates on the martian surface the messages we receive from mars about the presence of carbonates are quite contradictory on the one hand images of the planet clearly show the signatures of past bodies of standing water where the accumulation of sedimentary deposits should have occurred on the other hand the apparent absence of carbonates in the homogeneous fines covering the martian surface raises the question where could carbonates hide now in this paper we discuss the subject and demonstrate that a proposed destruction mechanism the photodecomposition caused by uv radiation cannot account alone for the missing carbonates by means of simulations we show that the difficulties in detecting the carbonates can be ascribed to the low temperatures of the emitting zones observed up to now finally we derive the minimum amount of such minerals that could possibly be detected in future observations of mars and we compare the results of simulations with observed spectra

first use of an airborne thermal infrared hyperspectral scanner for compositional mapping in may 1999 the airborne thermal infrared hyperspectral imaging system spatially enhanced broadband array spectrograph system sebass was flown over mormon mesa nv to provide the first test of such a system for geological mapping several types of carbonate deposits were identified using the 11 25 m band however massive calcrete outcrops exhibited weak spectral contrast which was confirmed by field and laboratory measurements because the weathered calcrete surface appeared relatively smooth in hand specimen this weak spectral contrast was unexpected here we show that microscopic roughness not readily apparent to the eye has introduced both a cavity effect and volume scattering to reduce spectral contrast the macroroughness of crevices and cobbles may also have a significant cavity effect the diminished spectral contrast is important because it places higher signal to noise ratio snr requirements for spectroscopic detection and identification this effect should be factored into instrumentation planning and interpretations especially interpretations without benefit of ground truth sebass had the required high snr and spectral resolution to allow us to demonstrate for the first time the ability of an airborne hyperspectral thermal infrared scanner to detect and identify spectrally subtle materials

orbital evidence for more widespread carbonate bearing rocks on mars carbonates are key minerals for understanding ancient martian environments because they are indicators of potentially habitable neutral to alkaline water and may be an important reservoir for paleoatmospheric co 2 previous remote sensing studies have identified mostly mg rich carbonates both in martian dust and in a late noachian rock unit circumferential to the isidis basin here we report evidence for older fe and or ca rich carbonates exposed from the subsurface by impact craters and troughs these carbonates are found in and around the huygens basin northwest of hellas in western noachis terra between the argyre basin and valles marineris and in other isolated locations spread widely across the planet in all cases they cooccur with or near phyllosilicates and in huygens basin specifically they occupy layered rocks exhumed from up to 5 km depth we discuss factors that might explain their observed regional distribution arguments for why carbonates may be even more widespread in noachian materials than presently appreciated and what could be gained by targeting these carbonates for further study with future orbital or landed missions to mars

distribution of pleuroncodes monodon larvae over the continental shelf of south central chile field and modeling evidence for partial local retention and transport abstract in situ and modeled spatial distribution of squat lobster pleuroncodes monodon larvae over the continental shelf off south central chile 35 37 s was analyzed along with currents and hydrography we aimed to identify the main larval transport retention characteristics in the study area which constitutes the southernmost p monodon fishing grounds embedded in the humboldt current system we hypothesized that the main contribution to population renewal originates in the two persistent adult aggregations close to the nursery ground that occurs over a continental shelf terrace limited by two submarine canyons two extensive bio physical field campaigns were carried out during the main 2001 2002 upwelling season field data indicated that larvae were released from late austral winter to spring from spots to the north and south of the nursery zoea i were found mainly below 50 m depth in southward flowing waters whereas older zoea dominated in northward flowing layers above 50 m larvae were circumscribed between the coast and the shelf break front and pelagic retention areas were identified over the widest shelf area megalopa and juveniles during march were only found over the nursery area individual based simulations coupled to the output of a hydrodynamic model climatological configuration for the studied area showed that the release sites close to the nursery made the largest contribution to recruitment sites further north could also contribute to recruitment if hatching occurred later in the upwelling season the contribution of vertical behavior to larval success was also important as was the former s interaction with the site and time of larval release our results support the relevance of coastal circulation affected by topography on the persistence of p monodon populations off southern chile and the modulation of temporal variability these results might apply to other abundant species in the area

an observational search for carbonates on mars a search for carbonates and other salts exposed on the surface of mars was undertaken by observing areas of the surface in the 2 6 m to 4 2 m spectral region using the university of hawaii 2 2 m telescope at the mauna kea observatory hawaii observations of four mars areas syrtis major hellas arabia and an area northeast of hellas were made on the night of september 19 1986 the reflectance spectra for two partially overlapping areas show a weak absorption band in the 3 8 m to 3 9 m region which is in the spectral region where carbonate absorptions appear 3 8 m to 4 0 m the mars area of overlap contains syrtis planum the spectral feature from about 3 76 m to 3 95 m is clearly shortward of and broader than the calcium carbonate band about 3 9 m to 4 0 m and is at a slightly shorter wavelength position than magnesium carbonate magnesite bands about 3 8 m to 3 96 m as measured in this study positive identification of this band cannot be made by us at this time measurements for two other mars areas show no evidence of carbonate or other bands if the band is due to absorptions in the mars surface material spectrum and if it is due to carbonates then the results imply about 3 to 5 wt of a carbonate such as magnesite on average in the upper few millimeters of the mars surface material over the two areas where the weak spectral feature appears we can place an upper limit of 3 to 5 wt calcium carbonate and about 5 wt magnesite for all areas observed the interpretations are based on laboratory measurements of the reflectance spectra of calcite and magnesite and their mixtures with palagonite effects of thermal emission on the detection of carbonates were also explored for a wide range of temperatures thermal effects are not sufficient to mask the presence of calcite in the 3 to 5 wt range theoretical reasoning strongly supporting the presence of carbonates as a component of the mars surface is reviewed these and earlier observations do not rule out carbonates below the surface in other locations as small outcrops or in concentrations of less than 3 to 5 of the areas observed

rare earth element concentrations and nd isotopes in the southeast pacific ocean 1 three vertical profiles of rare earth element concentrations and nd isotopic compositions have been measured in the remote southeast pacific ocean the three stations represent contrasting environments the oligotrophic center of the gyre station gyr the transition zone east of the south tropical front station egy and the peru chile upwelling marked by a pronounced oxygen minimum station upx rare earth concentrations display nutrient like vertical profiles except at upx where surface waters are enriched at this station nd isotopic compositions are clearly more radiogenic than in the open ocean suggesting that boundary exchange process is releasing lithogenic rare earth element from the volcanic andes unexpected radiogenic values end reaching 3 7 are also observed at 2000 m at station gyr in the upper circumpolar deep water that commonly have end values around 6 exchange processes related to hydrothermal activity are suspected to produce this increase in end in the vicinity of the east pacific rise these results provide some guidance for higher resolution studies planned in this region by the international geotraces program

oceans on mars an assessment of the observational evidence and possible fate the edges of the northern plains and interpreted to be shorelines remaining from these former standing bodies of water we examine the elevations and geologic relations along these contacts in detail and find little support for their interpretation as shorelines some contacts are clearly of volcanic origin and all have significant variations in elevation better support for the former presence of water over large parts of the northern plains is provided by the vastitas borealis formation vbf most of the post noachian fill within the northern basin is ridged plains of lower hesperian age interpreted to be volcanic in origin overlying the ridged plains is the vbf a thin veneer of material of upper hesperian age the vbf may have been deposited from large floods support for this interpretation is the similarity in age between the outflow channels and the vbf the presence of the vbf at the lower ends of the outflow channels and identification of numerous features in the outcrop areas of the vbf that are suggestive of basal melting of an ice sheet to cover all the area over which the vbf is exposed would require 2 3 10 7 km 3 of water spread over the entire surface of mars this volume is equal to a global layer global equivalent layer or gel 156 m deep we find no support for the larger estimates of ocean volumes that range up to 3 10 8 km 3 and which imply comparable amounts of water per unit area as are currently present on the surface of the earth under present climatic conditions on mars an ocean would freeze in a geologically short time period 10 4 years then would sublimate away at rates strongly dependent on the presence or absence of debris on the ice surface the present vbf is interpreted as a sublimation residue from the ponded outflow channel effluents the fate of a volume of water thought to have been emplaced by the outflow channels 2 3 10 7 km 3 is largely accounted for by the presence of other existing reservoirs on the planet an approximately 20 30 m gel of water is estimated to be in the present polar caps and a 50 m gel may have escaped to space since the hesperian leaving 80 m gel unaccounted for this amount may be partly trapped in other volatile rich deposits on the surface and a significant amount could have reentered the groundwater system by south polar basal melting and been progressively cold trapped at the base of a growing cryosphere on the basis of our assessment of the hesperian aged deposits we predict that testing of the clifford and parker 2001 hypothesis that a noachian aged ocean covered up to one third of the surface of mars will be made very difficult by the enhanced degradation rates in the noachian and subsequent geological events in the northern lowlands index terms 6225 planetology solar system objects mars 4267 oceanography general paleoceanography 5407 planetary sciences atmospheres evolution 5470 planetary sciences surface materials and properties 1635 global change oceans 4203 keywords mars oceans channels shorelines hesperian

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

terrestrial analogs for interpretation of infrared spectra from the martian surface and subsurface sulfate nitrate carbonate and phyllosilicate bearing atacama desert soils 1 hyperarid 6 5 m was not suited for salt and phyllosilicate detection because of overlapping spectra from primary silicates e g feldspar water and carbon dioxide the visible near infrared 0 35 2 5 m region was suited for detecting carbonate nitrate gypsum water of hydration and phyllosilicate hydroxyls without interference from primary silicates however gypsum water of hydration features can obscure phyllosilicate hydroxyl carbonate and nitrate features if gypsum levels are high overtone combination absorption features in the midinfrared were determined to be the best indicators of sulfate 4 48 4 70 m nitrate 4 12 m and carbonate 3 98 m because interferences from overlapping primary silicate and water features are not present in this region interferences from co2 and thermal emission effects in the overtone combination region are possible but may be minimized by corrective techniques infrared analysis of atacama desert soils can provide insight into the spectral search of sulfate nitrate carbonate and phyllosilicate containing soils on mars

combined use of visible reflected infrared and thermal infrared images for mapping hawaiian lava flows the weathering of hawaiian basalts is accompanied by chemical and physical changes of the surfaces these changes have been mapped using remote sensing data from the visible and reflected infrared and thermal infrared wavelength regions they are related to the physical breakdown of surface chill coats the development and erosion of silica coatings the oxidation of mafic minerals and the development of vegetation cover these effects show systematic behavior with age and can be mapped using the image data and related to relative ages of pahoehoe and aa flows the thermal data are sensitive to silica rind development and fine structure of the scene the reflectance data show the degree of oxidation and differentiate vegetation from aa and cinders together data from the two wavelength regions show more than either separately the combined data potentially provide a powerful tool for mapping basalt flows in arid to semiarid volcanic environments

finescale vertical structure of the upwelling system off southern peru as observed from glider data abstractthe upwelling system off southern peru has been observed using an autonomous underwater vehicle a slocum glider during october november 2008 nine cross front sections have been carried out across an intense upwelling cell near 14 s during almost two months profiles of temperature salinity and fluorescence were collected at less than 1 km resolution between the surface and 200 m depth estimates of alongshore absolute geostrophic velocities were inferred from the density field and the glider drift between two surfacings in the frontal region salinity and biogeochemical fields displayed cross shore submesoscale filamentary structures throughout the mission those features presented a width of 10 20 km a vertical extent of 150 m and appeared to propagate toward the shore they were steeper than isopycnals and kept an aspect ratio close to f n the inverse of the prandtl ratio these filamentary structures may be interpreted mainly as a manifestation of submesoscale turbulence through sti

surface circulation and fronts of the south pacific ocean east of 120 w the south pacific surface circulation east of 120 w is studied using satellite tracked drifters from 1979 2004 the major currents of this region are described such as the antarctic circumpolar the south pacific the chile peru and the cape horn currents we suggest the presence of a branch exiting from the acc between 100 120 w and transporting subantarctic surface water toward lower latitudes we also show the existence of an anticyclonic recirculation cell north of 35 s finally based on hydrographic sections we show that in the eastern south pacific the core of the subtropical front corresponds to the 14 c isotherm at 150 m depths and to the 2 7 m of dynamic height relative to 3000 m the subantarctic front is located by maximum temperature gradients in the range 3 8 c at 100 400 m depth

seasonal climatology of hydrographic conditions in the upwelling region off northern chile over 30 years of hydrographic data from the northern chile 18os 24os upwelling region are used to calculate the surface and subsurface seasonal climatology extending 400 km offshore the data are interpolated to a grid with sufficient spatial resolution to preserve cross shelf gradients and then presented as means within four seasons austral winter july september spring october december summer january march and fall april june climatological monthly wind forcing surface temperature and sea level from three coastal stations indicate equatorward upwelling favorable winds throughout the year weakest in the north seasonal maximum alongshore wind stress is in late spring and summer december march major water masses of the region are identified in climatological t s plots and their sources and implied circulation discussed surface fields and vertical transects of temperature and salinity confirm that upwelling occurs year round strongest in summer and weakest in winter bringing relatively fresh water to the surface nearshore surface geostrophic flow nearshore is equatorward throughout the year during summer an anticyclonic circulation feature in the north which extends to at least 200 rn depth is evident in geopotential anomaly and in both temperature and geopotential variance fields subsurface fields indicate generally poleward flow throughout the year strongest in an undercurrent near the coast this undercurrent is strongest in summer and most persistent and organized in the south south of 21os a subsurface oxygen minimum centered at 250 m is strongest at lower latitudes low salinity subsurface water intrudes into the study area near 100 m predominantly in offshore regions strongest during summer and fall and in the southernmost portion of the region the climatological fields are compared to features off baja within the somewhat analogous california current and to measurements from higher latitudes within the chile peru current system

structure and surface properties of eddies in the southeast pacific ocean 1 a number of studies have posited that coastally generated eddies could cool the southeast pacific ocean sep by advecting cool upwelled waters offshore we examine this mechanism by characterizing the upper ocean properties of mesoscale eddies in the sep with a variety of observations and by estimating the surface layer eddy heat flux divergence with satellite data cyclonic and anticyclonic eddies observed during two cruises featured deep positive salinity anomalies along the 26 5 kg m 3isopycnal indicating that the eddies had likely trapped and transported coastal waters offshore the cyclonic eddies observed during the cruises were characterized by shoaling isopycnals in the upper 200 m and cool near surface temperature anomalies whereas the upper ocean structure of anticyclonic eddies was more variable using a variety of large scale observations including argo float profiles drifter records and satellite sea surface temperature fields we show that relative to mean conditions cyclonic eddies are associated with cooler surface temperatures and that anticyclonic eddies are associated with warmer surface temperatures within each data set the mean eddy surface temperature anomalies are small and of approximately equal magnitude but opposite sign eddy statistics drawn from satellite altimetry data reveal that cyclonic and anticyclonic eddies occur with similar frequency and have similar average radii in the sep a satellite based estimate of the surface layer eddy heat flux divergence while large in coastal regions is small when averaged over the sep suggesting that eddies do not substantially contribute to cooling the surface layer of the sep

analogue modelling of volcano flank terrace formation on mars of the features that characterize large shield volcanoes on mars flank terraces remain the most enigmatic several competing mechanisms have been proposed for these laterally expansive topographically subtle landforms here we test the hypothesis that horizontal contraction of a volcano in response to the down flexing of its underlying basement leads to flank terracing we performed a series of analogue models consisting of a conical sand plaster load emplaced on a basement comprising a layer of brittle sand plaster atop a reservoir of viscoelastic silicone our experiments consistently produced a suite of structures that included a zone of concentric extension distal to the conical load a flexural trough adjacent to the load base and convexities terraces on the cone s flanks the effects of variations in the thickness of the brittle basal layer as well as in the volume slope and planform eccentricity of the cone were also investigated for a given cone geometry we find that terrace formation is enhanced as the brittle basement thickness decreases but that a sufficiently thick brittle layer can enhance the basement s resistance to loading such that terracing of the cone is reduced or even inhibited altogether for a given brittle basement thickness terracing is reduced with decreasing cone slope and or volume our experimental results compare well morphologically to observations of terraced edifices on mars and so provide a framework with which to understand the developmental history of large shield volcanoes on the red planet

rates and patterns of late cenozoic denudation in the northernmost atlantic coastal plain and piedmont topography of a 2800 km 2 section of the u s atlantic coastal plain and piedmont is reconstructed at five times from the late miocene to the holocene the reconstructions are based on mapping of fluvial colluvial and marginal marine deposits that are dated by radiocarbon palynostratigraphy and correlation to adjacent glacial and marine units denudation rates and patterns are calculated by subtracting successive topographies with 60 m horizontal resolution and 6 m vertical resolution the overall late miocene to holocene denudation rate of 10 m m y is similar to other estimates of long term denudation in the region the overall rate resolves spatially into a wide range of local rates varying from a minimum of 0 2 m m y on residual uplands to as high as 600 m m y in glacially rerouted stream channels the distribution of local rates shows that denudation is accomplished by stream incision in response to long term glacio eustatic decline followed by slope retreat into residual uplands from the incised channels slope retreat replaces the uplands with pediments and straths pediment landforms and sediments and observation of modern scarps and valley heads indicate that groundwater seepage from the base of residual uplands is an important mechanism of slope retreat this process is self limiting because as the volume of residual upland is reduced seepage diminishes and slope retreat slows until small residuals undergo little or no further reduction thus relict topography is preserved even as most of the landscape actively erodes

emi as a non invasive survey technique to account for the interaction between ww i relicts and the soil environment at the western front abstract after the war the greater part of the disturbed areas within the western front zone of world war i ww i was taken back into culture even 100 years after date it can be assumed that the soil within these areas still contains the traces of the war to account for a thorough inventory of both the soil variability the ww i relicts and the anthropogenic disturbances and to identify their interactions a large scale non invasive approach employing a multi receiver frequency domain emi instrument was proposed with this instrument both lateral variations of the soil apparent electrical conductivity a and apparent magnetic susceptibility a from multiple overlapping soil volumes were obtained at a battlefield site within the western front zone inverting the multiple simultaneous a measurements allowed for a detailed representation of the depth to the interface between both contrasting loess and clay layers at the study site additionally anomalies caused by buried metal objects could be separated from more subtle anomalies caused by shell holes moreover inverting the a measurements improved the identification of different ww i trenches finally the integration of all ww i and soil features allowed for an enhanced understanding about the impact of the war activities on the soil environment and vice versa

weathering trends in terrace deposits up to 350 000 years old in northeast southland new zealand abstract gravelly floodplain deposits and six terrace treads in the waimea plains northeast southland new zealand range in age from ca 1000 years old to 350 000 yr old deposits are progressively more weathered with increasing parent material age soils developed in them are classified as recent soils brown soils and ultic soils in the new zealand soil classification and udifluvents dystrochrepts haplohumults hapludults and paleudults in the usda soil classification soil taxonomy the youngest soils are slightly acid those developed in deposits 35 000 70 000 yr old are strongly acid in soils in deposits 160 000 yr old and older that have weathered in two or three interglacial periods including the present one ph and total exchangeable bases values are higher than in soils in younger deposits the higher ph of the soils in older deposits is attributed to release of cations by stone weathering soils developed in deposits up to 70 000 yr old have clays dominated by mica and chlorite stones in these soils are at most weakly weathered and the two phases of weathering are distinguished a phase of approximate duration 100 000 yr in which most weathering and leaching occurs in the matrix which becomes increasingly acidified and a phase from 100 000 to 350 000 yr which is dominated by cation release from stones reversal of the acidification trend and breakdown of stone fabric

distribution of 236u in the u s geotraces eastern pacific zonal transect and its use as a water mass tracer abstract we report dissolved concentrations of the long lived radioisotope 236u measured in the water column along the 2013 us geotraces eastern pacific zonal transect gp16 this transect followed a 10 15 s line from manta ecuador to papeete haiti french polynesia crossing the southern east pacific rise intercepting one of the largest hydrothermal plumes as well as a productivity gradient which includes the upwelling zone and associated low oxygen waters offshore from peru and the oligotrophic sub tropical gyre accelerator mass spectrometry was used to measure dissolved seawater 236u concentrations as low as 1 103 atom kg 1 which are among the lowest levels reported to date differences in upper water column 236u distributions from east to west are a result of variable contributions from different surface and intermediate waters encountered along the transect the distribution of 236u both in depth and geographically provides complementary information to that obtained from 14c and helium isotopes demonstrating that 236u concentrations are diagnostic in the identification of and contributions from the different deep and bottom water masses encountered along the epzt jenkins et al 2017 for example we observe minimum 236u concentrations along the epzt between 2000 and 3000 m that are consistent with contributions attributed to pacific deep water we also observe increases in 236u below 3000 m at the eastern and western termini of the epzt this is consistent with contributions associated with antarctic bottom water and lower circumpolar deep water our results indicate that 236u may be used in conjunction with 14c and 3he isotopes as an additional tool with which to identify and resolve contributions from different water masses in the pacific ocean this article is part of a special issue entitled cycles of trace elements and isotopes in the ocean geotraces and beyond edited by tim m conway tristan horner yves plancherel and aridane g gonzalez

quaternary soil chronosequences on terraces of the susquehanna river pennsylvania abstract susquehanna river terraces are used to establish time lines along a 150 km reach of the river from the lower piedmont to the edge of the appalachian plateau this is achieved by generating soil chronosequences at two locations marietta pa in the lower piedmont and muncy pa near the glacial border on the boundary between the valley and ridge province and the appalachian plateau these sites preserve the most complete record of fluvial incision on the susquehanna river with flights of seven quaternary terraces ranging in elevation from 3 m to 51 m above the modern river soil characteristics used to develop the soil chronosequences include complexity of horizonization thickness of b horizon clay content of b horizon soil color cbd extractable fe al and mn total extractable fe and clay mineralogy terrace age constraints are based on soil development correlation to regional glacial stratigraphy correlation to dated fluvial and glaciofluvial deposits and by paleomagnetic analysis of sediments terrace ages at the muncy site range from modern

analysis of terrestrial and martian volcanic compositions using thermal emission spectroscopy 1 determination of mineralogy chemistry and classification strategies we have examined and applied existing classification schemes for volcanic rocks and developed new schemes using thermal emission spectra of terrestrial volcanic rocks laboratory thermal infrared spectra 5 25 m at 2 cm 1 spectral sampling deconvolved modal mineralogies and derived mineral and bulk rock chemistries were used to distinguish basalt basaltic andesite andesite and dacite modal mineralogies derived from linear deconvolution of terrestrial volcanic rocks were compared to modes measured by an electron microprobe phase mapping technique to determine the accuracy of linear deconvolution in modeling specific mineral abundances one standard deviations of the absolute differences between modeled and measured mineral abundances range from 2 4 to 12 2 vol with an average standard deviation of 4 8 vol being in agreement with average uncertainties calculated in previous studies weighted average compositions of feldspars in the deconvolution generally overlap the measured ranges of plagioclase compositions and the presence of low calcium and high calcium pyroxenes was correctly identified bulk chemistries of volcanic rocks were derived with a relatively high degree of accuracy 1 standard deviations ranging from 0 4 to 2 6 vol by combining the compositions of spectrally modeled phases in proportion to their relative abundances in a particular sample these data were collectively used to examine existing and develop new volcanic rock classification schemes however no single classification scheme was effective in accurately classifying all samples multiple steps of classification were required to distinguish volcanic rocks reflecting the mineralogic diversity and continuum of compositions that exists in volcanic rock types in a companion paper hamilton et al this issue these schemes are applied to the classification of martian surface compositions

soil development on the wwi battlefield of verdun france abstract much research has been done on how the physical environment can influence the outcome of battle but few have studied the inverse the effects of warfare upon the environment the goal of this research is to characterize and help understand soil development within areas disturbed by explosive munitions on the wwi battlefield of verdun france 1916 encompassing an area of 29 000 km 2 the battlefield remains one of the most heavily shelled of all time twenty seven pedons were sampled and described at three sites on the battlefield some pedons were within artillery craters while others were on adjacent undisturbed soils site selection reflected the diversity of bedrock and drainage characteristics across the study area soil development was characterized within the crater bottoms and sides many craters penetrated the shallow limestone bedrock and blasted out fragments of limestone on nearby undisturbed pedons had already been incorporated into the profile despite the short period of time since the battle 88 years measurable amounts of weathering and pedogenesis has occurred in the soils within the craters a major pedogenic process operative here is the accumulation and decomposition of organic matter which is intimately associated with and aided by earthworm bioturbation based on elemental analysis of the fine earth fraction measurable amounts of leaching and weathering have occurred in the 88 years since the battle this study provides insight into the ability of a landscape to recover following a catastrophic anthropogenic disturbance

how element translocation by plants may stabilize illitic clays in the surface of temperate soils abstract it has been described several times that plant activity enriches the upper part of soil profiles in the inorganic elements they use for their growth si k ca mg this phenomenon called nutrient uplift or element translocation can counteract element loss via leaching in surface soils and may therefore impact clay mineral stability in upper soil horizons however apart from some studies in tropical ecosystems the link between element translocation and clay mineral stability has been poorly investigated yet the present work explores the consequences of element translocation on clay mineral stability in temperate grassland soils through the use of a geochemical model initially studies indicating that silicon and potassium translocation stabilizes 2 1 clay minerals and especially illitic clay minerals in surface soil were compiled using this analysis as a basis we propose a simple biogeochemical model linking plant primary productivity and clay mineral thermodynamic stability that allowed explaining how plant activity may stabilize clay minerals in the upper part of temperate grassland soils the influence of various parameters such as rainfall primary production elemental composition of plants or acidifying activity of roots was also investigated using the model the outputs of the model suggested that plant activity under certain conditions may well stabilize illitic clay in surface soils which opens wide perspectives for modellers and experimentalists

changes in the source of nutrients associated with oceanographic dynamics offshore southern chile 41 s over the last 25 000 years abstract in order to obtain a better knowledge of past oceanographic variability offshore southern chile this study reappraises the changes in the sources of nutrients over the last 25 ka based on a detailed comparison of previously published nitrogen isotope and microfossil records dinoflagellate cysts coccoliths and diatoms from odp site 1233 41 s our findings support the main conclusions of martinez et al 2006 in the sense that both the subantarctic surface water and the gunther undercurrent are potential sources for the recorded late quaternary sedimentary 15 n signatures at site 1233 with variable contributions of both sources during different time periods this study indicates that subantarctic surface water forms the main source for nutrients during the last glacial maximum 25 18 6 cal ka bp the first part of the deglaciation 18 6 15 7 cal ka bp and the holocene 9 8 cal ka bp until present an increased contribution of equatorial subsurface water as a source of nutrients to the photic zone offshore southern chile is observed between 14 4 and 9 8 cal ka bp which is indicative for upwelling conditions at least after 13 2 cal ka bp as indicated by the microfossil data