soil mineralogy trends in california landscapes california s diverse environmental gradients serve as natural experiments for examining controls on soil mineral distribution in landscapes in this paper we use example soilscapes from throughout california to examine how lithology climate topography and duration of pedogenesis interact to produce distinctive weathering environments and characteristic suites of soil minerals seven soil geomorphic sequences were assembled from the literature to illustrate major soil mineralogical trends 1 granitic terrain of the peninsular ranges 2 granitic terrain of the central sierra nevada 3 andesitic terrain of the northern sierra nevada 4 fluvial terraces on the east side of the great valley 5 marine terraces of the central coast 6 ultramafic terrain of the klamath mountains and 7 an alluvial fan in the mojave desert results of this analysis show that kaolin is present in virtually all pedons irrespective of climate parent material age or topographic position kaolin does not form in ultramafic soils due to insufficient aluminum many secondary clay minerals reflect the state s strong climatic influence with palygorskite smectite and vermiculite in the dry hot environments hydroxy interlayered minerals gibbsite and short range ordered minerals in the cool moist environments in arid and semi arid regions the distribution of calcite gypsum and soluble salts is strongly related to patterns of eolian dust deposition and water infiltration and leaching

reappraisal of the beekmantown group sedimentology and stratigraphy montreal area southwestern quebec implications for understanding the depositional evolution of the lower middle ordovician laurentian passive margin of eastern canada detailed lithostratigraphic mapping of the beekmantown group of southwestern quebec has refined the field application of the previously proposed tripartite division of the group i e theresa beauharnois and carillon formations the group is a peritidal dominated succession that accumulated on the epicontinental laurentian passive margin biostratigraphic data based on conodonts from this group indicate an early to early middle ordovician age and are partially time correlative with the wallace creek to naylor ledge strata of the philipsburg group southern quebec this conodont biostratigraphy sheds new light on the temporal evolution and depositional framework of the beekmantown platform the platform evolved as a distally steepened ramp during deposition of the theresa formation and the ogdensburg member of the beauharnois formation early to middle ibexian correlative strata of the philipsburg group include the wallace creek and morgan corner formations which represent outer platform sediments the coarse grained sandstone of the theresa formation accumulated in the innermost platform whereas coarse grained carbonates of the ogdensburg member indicate open marine subtidal to intertidal carbonate sand shoals by late ibexian the platform developed a pronounced margin where thrombolites flourished under high energy conditions these are represented by the thrombolite rich hasting creek and naylor ledge formations of the philipsburg group consequently a broad lagoon formed on the lee side of the platform margin where low energy conditions prevailed and accumulation of burrow mottled dolostones of the huntingdon member of the upper beauharnois formation took place the lagoon became more restricted during the latest stages of the basin fill whiterockian and high intertidal to supratidal sediments of the carillon formation were deposited

time specific black mudstones and global hyperwarming on the cambrian ordovician slope and shelf of the laurentia palaeocontinent abstract the early paleozoic featured nine intervals of strong expansion of an upper slope dysoxic anoxic d a water mass with eustatic rise or epeirogenic transgression strong expansion of this d a water mass led to deposition of time specific macroscale alternations of dark grey black mudstone within oxic green to red mudstone on the middle lower slope this d a facies even onlapped warm carbonate and cool water siliciclastic shelves as in the mesozoic d a muds were deposited in shallow water perhaps tens of metres deep with sea level rise these nine d a macroscale alternations correspond to intervals of global hyperwarming times of very intense greenhouse conditions that resulted from a feedback initiated by higher insolation and heat storage as shallow seas onlap tropical palaeocontinents warm epeiric seas heated the ocean and thermal expansion accelerated eustatic rise ever more extensive epeiric seas heightened oceanic and global temperature as heat storage capacity increased deep ocean circulation intensity fell below that of a greenhouse interval and lead to d a deposition low on the slope and on the platforms to provide the signature of global hyperwarming global hyperwarming differs from a hothouse interval as it does not require co 2 input from large igneous provinces to produce high temperatures and never shows deep sea anoxia late ordovician and late devonian black mudstones that cover much of laurentia record epeirogenic transgressions that led to global hyperwarming and suggest that cold water upwelling or plant terrestrialisation had nothing to do with epeiric sea anoxia global hyperwarming reduced oxygen solubility in these seas and erosion of orogens produced muddy water that limited light penetration and promoted shallow water anoxia the global hyperwarming hypothesis means that relative eustatic and epeirogenic sea levels complement the effect of global pco 2 on climate and sea level must also be regarded as a primary driver of phanerozoic climate

quartz arenites of the cambro ordovician kamouraska formation quebec appalachians canada ii eolian sands in deep sea sedimentary gravity flow deposits the kamouraska formation is a quartz arenitic unit of latest cambrian earliest ordovician age in the quebec appalachians that was deposited by hyperconcentrated to concentrated density flows in a meandering submarine canyon on the continental slope bordering the iapetus ocean as outlined in a companion paper detailed petrographic study of the quartz arenites of the kamouraska formation combined with scanning electron microscopy of grain surface textures suggests that the quartz sands are of eolian origin having been derived from an inland desert or less likely a barrier beach dune system transport of the mature quartz arenitic sand onto the shelf and deposition into the deep sea was not accompanied by substantial mixing with material from other sources thus preserving the inherited eolian characteristics a modern analogue for the eolian interpretation of the deep sea quartz arenite beds is as follows thick late pleistocene eolian sand beds on a modern abyssal plain in the east atlantic referred

estimating millennial scale rates of dust incorporation into eroding hillslope regolith using cosmogenic nuclides and immobile weathering tracers 1 dust fluxes are of wide interest because of the effects of dust on climate oceanic primary productivity terrestrial biogeochemical cycles and regolith composition estimating long term dust deposition rates however can be difficult especially in steep eroding terrain here we present a geochemical mass balance method for estimating long term average rates of dust incorporation into regolith on steadily eroding hillslopes this method requires measurements of the local regolith production rate and the concentrations of two immobile elements in the regolith its parent rock and dust dust incorporation rates inferred with this method are averaged over the long timescale of regolith residence on the hillslope typically 103 105 years and thus may serve as long term averages against which modern day dust fluxes may be compared we apply this model to 17 field sites in the south fork of the salmon river in the idaho batholith where rock and regolith compositions imply that mafic rich material has been added to the otherwise granitic regolith we suggest that the most likely source of this mafic material is dust sourced from the same glacial outburst flood sediments that generated the palouse loess on the columbia plateau and we use the published composition of these sediments to infer dust incorporation rates of 3 13 t km 2 yr 1 at these sites comparable to modern day dust fluxes elsewhere in the western united states

importance of environment on the order of mineral weathering in olivine basalts hawaii examination of weathering rinds from lava flows on hawaii with backscatter electron microscopy and electron micro probe analysis reveals that olivine weathers more slowly than adjacent clinopyroxene and plagioclase in environments with a paucity of organic acids yet when weathering rinds are in contact with abundant organic acids secreted by lichens olivine weathers before clinopyroxene and plagioclase weathers last the exception to goldich s widely accepted mineral stability series in organic poor environments runs counter to a thermodynamics explanation for the order of mineral weathering and illustrates the importance of the biogeochemical environment

clay mineralogy of weathering rinds and possible implications concerning the sources of clay minerals in soils weathering rinds on volcanic clasts in quaternary deposits in the western united states contain only very fine grained and poorly crystalline clay minerals rinds were sampled from soils containing well developed argillic b horizons in deposits about 105 yr old or more the clay size fraction of the rinds is dominated by allophane and iron hydroxy oxides whereas the b horizons contain abundant well crystallized clay minerals the contrast between the clay mineralogy of the weathering rinds in which weathering is isolated from other soil processes and that of the associated soil matrices suggests a need to reassess assumptions concerning the rates at which clay minerals form and the sources of clay minerals in argillic b horizons this study suggests that crystalline clay minerals form more slowly in weathering rinds than is generally assumed for soil environments and that the weathering of primary minerals may not be the dominant source of crystalline clay minerals in middle to late pleistocene soils

tribes hill rochdale formations in east laurentia proxies for early ordovician tremadocian eustasy on a tropical passive margin new york and west vermont slow subsidence and tectonic quiescence along the new york promontory margin of laurentia mean that the carbonate dominated tribes hill and overlying rochdale formations serve as proxies for the magnitude and timing of tremadocian eustatic changes both formations are unconformity bound deepening shoaling depositional sequences that double in thickness from the craton into the parautochthonous western appalachian mountains a consistent layer cake succession of member level units of the formations persists through this region the tribes hill formation late early tremadocian late skullrockian late fauna b rossodus manitouensis chron unconformably overlies the terminal cambrian little falls formation as the lowest ordovician unit on the new york promontory it was deposited during the strong early tremadocian or stonehenge transgression that inundated laurentia brought dysoxic anoxic d a slope water onto the shelf and led to deposition of the schaghticoke d a interval black mudstone and ribbon limestone on the laurentian continental slope the uniform lithofacies succession of the tribes hill includes a lower sand rich member a middle dark grey to black mudstone that records d a in eastern exposures and an upper shoaling up carbonate highstand facies a widespread 12000 km 2 thrombolitic interval in the highstand carbonate suggests the new york promontory was rimmed by thrombolites during deposition of the tribes hill offlap and erosion of the tribes hill was followed by the relatively feeble sea level rise of the rochdale transgression new in laurentia and deposition of the rochdale formation the rochdale transgression correlated with the kierograptus drowning interval in baltica marks a eustatic rise the rochdale formation represents a short early ordovician interval early late tremadocian middle late stairsian macerodus dianae chron it correlates with a depositional sequence that forms the middle boat harbour formation in west newfoundland and with the rte 299 d a interval on the east laurentian slope the rochdale has a lower carbonate with abundant quartz silt comstock member new and an upper thrombolitic hawk member new high stand facies tribes hill and rochdale faunas are mollusc rich generally trilobite poor and have low diversity laurentian faunal province conodonts ulrichodina rutnika landing n sp is rare in rochdale conodont assemblages trilobites are also low in diversity but locally form coquinas in the middle tribes hill the poorly preserved rochdale trilobites include the bathyurid randaynia at least two hystricurid species and leiostegium

rates of soil development from four soil chronosequences in the southern great basin abstract four soil chronosequences in the southern great basin were examined in order to study and quantify soil development during the quaternary soils of all four areas are developed in gravelly alluvial fans in semiarid climates with 8 to 40 cm mean annual precipitation lithologies of alluvium are granite gneiss at silver lake granite and basalt at cima volcanic field limestone at kyle canyon and siliceous volcanic rocks at fortymile wash ages of the soils are approximated from several radiometric and experimental techniques and rates are assessed using a conservative mathematical approach average rates for holocene soils at silver lake are about 10 times higher than for pleistocene soils at kyle canyon and fortymile wash based on limited age control holocene soils in all four areas appear to develop at similar rates and pleistocene soils at kyle canyon and fortymile wash may differ by only a factor of 2 to 4 over time spans of several millennia a preferred model for the age curves is not linear but may be exponential or parabolic in which rates decrease with increasing age these preliminary results imply that the geographical variation in rates within the southern great basin mojave region may be much less significant than temporal variation in rates of soil development the reasons for temporal variation in rates and processes of soil development are complexly linked to climatic change and related changes in water and dust erosional history and internally driven chemical and physical processes

a soil chronosequence in the semi arid environment of patagonia argentina abstract soil development with time was investigated on beach ridges with ages ranging from about 1380 to 6240 14c years bp at the eastern coast of central patagonia the main pedogenic processes are accumulation of organic matter and carbonate leaching and accumulation within the upper part of the soils soil formation is strongly influenced by incorporation of eolian sediments into the interstitial spaces between the gravel of which the beach ridges are composed different amounts of eolian material in the soils lead to differentiation into leptosols containing 10 fine earth in the upper 75 cm and regosols containing 10 fine earth soil depth functions and chronofunctions of organic carbon calcium carbonate ph ca zr mg zr k zr na zr fe zr mn zr and si al obtained from x ray fluorescence analysis were evaluated to establish soil chronofunctions mean values of the horizon data of 0 10 cm below the desert pavement were used which were weighted according to the horizon thicknesses the depth function of ph shows a decrease towards the surface indicating leaching of bases from the upper centimeters chronofunctions of ph show that within 6000 radiocarbon years of soil development ph drops from 7 0 to 6 6 in the leptosols and from 8 1 to 7 5 in the regosols the higher ph of the regosols is due to input of additional bases from the eolian sediments chronofunctions of ca zr and k zr indicate progressive leaching of ca and k in the regosols showing close relationships to time r2 0 972 and 0 995 na leaching as indicated by decreasing na zr ratios shows a strong correlation to time only in the leptosols r2 0 999 both leptosols and regosols show close relationships to time for fe zr r2 0 817 and 0 824 mn zr r2 0 940 and 0 803 and si al 0 971 and 0 977 indicating enrichment of fe and mn and leaching of si leaching of mobile elements takes place on a higher level in the regosols than in the leptosols from the beginning of soil formation hence a significant part of the eolian sediments must have been incorporated into the beach ridges very soon after their formation

regional variations in water quality and relationships to soil and bedrock weathering in the southern sacramento valley california usa abstract regional patterns in ground and surface water chemistry of the southern sacramento valley in california were evaluated using publicly available geochemical data from the us geological survey s national water information system nwis within the boundaries of the study area more than 2300 ground water analyses and more than 20 000 surface water analyses were available ground waters from the west side of the sacramento valley contain greater concentrations of na ca mg b cl and so 4 while the east side ground waters contain greater concentrations of silica and k these differences result from variations in surface water chemistry as well as from chemical reactions between water and aquifer materials sediments that fill the sacramento valley were derived from highlands to the west the coast ranges and east the sierra nevada mountains the former having an oceanic provenance and the latter continental these geologic differences are at least in part responsible for the observed patterns in ground water chemistry thermal springs that are common along the west side of the sacramento valley appear to have an effect on surface water chemistry which in turn may affect the ground water chemistry

ducted coastal ridging over s e australia the intense and rapidly established coastal ridging which is a regular occurrence over south eastern australia during the warm seasons is investigated using a detailed case study and mesoscale numerical model simulations we suggest that the ridge is initiated by a forced kelvin type edge wave which forms on the south western edge of the great dividing range and is ducted in an anticlockwise sense around the coast the ridge is then stabilized by inertial modification and decays over a synoptic time scale of a few days our results apply to similar phenomena in other parts of the world notably southern africa and south america

genetic interpretations of elemental and chemical differences in a soil chronosequence california abstract soils developed on fluvial terraces in central california have similar parent materials climatic settings vegetation cover and slopes but range in age from 40 000 to 3 000 000 years the soils have chemical compositions that change systematically with increasing age such chemical differentiation is most likely the result of long term weathering and mineralogical transformations that occurred since deposition of terrace fills and stabilization of the geomorphic surfaces the changes in composition with time closely mimic other studies on mineral weathering in which alkali and alkali earth elements are lost more rapidly than transitional elements the relative rates of element loss were determined by changes in element ratios over time net losses and gains of elements in different size fractions were monitored by their concentrations relative to zr the most stable constituent both sand and finer size fractions have lost considerable amounts of ca mg na and k aluminum appears to have been lost from the sand fraction and gained in the fine fraction over a 3 million year time span although there is no evidence for losses of fe and ti from sands there is a net influx of fe and ti into finer fractions probably gained from undetectable yet significant weathering of sand grains etching of sand grains clay mineralogy and microprobe analyses also indicate that the soils have undergone these chemical transformations during their formation mineralogical analyses also mimic other studies on mineral weathering in which the pyroxenes weather more rapidly than hornblende which weathers more rapidly than sphene or zircon

lower ordovician ibexian trilobites from the tribes hill formation central mohawk valley new york state the early ordovician tribes hill formation of east central new york state is a sequence of peritidal to subtidal carbonates and minor shales that rests disconformably on late cambrian carbonates and is in turn succeeded disconformably by middle ordovician strata more than 800 trilobites from 24 collections are assigned to six species bellefontia gyracantha raymond clelandia parabola cleland hystricurus ellipticus cleland hystricurus cf hystricurus oculilunatus ross symphysurina convexa cleland and symphysurina cf symphysurina woosteri ulrich two distinct biofacies are present the bellefontia biofacies in subtidal shales with thin storm generated bioclastic interbeds and the gastropod rostroconch biofacies in shallow carbonate bank lithofacies the trilobites of the tribes hill formation are assigned to a single informal biostratigraphic unit the clelandia parabola fauna which is correlative with trilobite zone b of the garden city formation of utah and with the bellefontia frank

tempo of earliest ordovician graptolite faunal succession conodont based correlations from the tremadocian of quebec successive tremadocian planktic dendroid graptolite assemblages from continental slope sequences in quebec can be correlated with north american platform biozonations on the basis of conodonts anisograptid bearing assemblage 2 middle tremadocian matane faunas are associated with early ordovician rossodus manitouensis zone new designation conodonts younger middle tremadocian faunas with adelograptids assemblage 3 are no younger than the rossodus manitouensis zone key dendroid evolutionary immigration events take place within the lower conodont fauna b interval rooted dendroids near cap des rosiers quebec and in eastern new york state occur with lower fauna b conodonts and the trilobites pareuloma and borthaspidella however the earliest tremadocian and earliest ordovician dendroid immigration event represented by the local lowest occurrence of faunas with dictyonema flabelliforme s l at localities in western newfoundland eastern new york state norway and eastern china also lies with

generation of coastal lows by synoptic scale waves a model is presented in which eastward propagating synoptic waves interact with a meridional escarpment it is shown that under suitable conditions trapped waves are produced at the escarpment the dominant wave being poleward propagating this model is intended to represent the generation of coastally trapped disturbances like those found in southern africa

a trilobite fauna from the highest shineton shales in shropshire and the correlation of the latest tremadoc a rich fauna dominated by trilobites and calcified chordates has been collected in shropshire from the arenaceous beds the highest member of the tremadoc shineton shale formation and hitherto regarded as poorly fossiliferous this fauna shows that shelf conditions persisted longer in shropshire than has been supposed it is likely that even younger tremadoc is cut out at the unconformity below the caradoc in the shineton inlier the correlation of the later tremadoc is reviewed and the nomenclature of british tremadoc biozones is revised the trilobites described here are a mixture of previously known and new forms the name shumardia conophrys salopiensis callaway is revived for british material traditionally assigned to the scandinavian species shumardia pusilla sars from which it is distinct the new taxa litagnostus meniscus sp nov apatokephalus sarculum sp nov and skljarella cracens sp nov are described the type species of asaphellus a homfrayi and leptoplastides l salteri are redescribed and geragnostus callavei pseudokainella impar and parapilekia sp are recorded new information on the ontogeny of s c salopiensis and a homfrayi is given litagnostus and skljarella are recorded from the british isles for the first time

the use of element clay ratios assessing gains and losses of iron manganese and phosphorus in soils of sedimentary rocks on a landscape scale abstract quantitative statements about soil development on a landscape level of scale are difficult to work out especially in soils of stratified sediments this article presents an easily applicable method to infer gains and losses of fe mn and p in soilscapes developed on sedimentary rocks for this an element clay ratio was introduced the amounts of pedogenic cbd fe mn and total p in kg were calculated on a pedon basis i e for the volume under 1 m 2 down to the c horizon or any arbitrary depth in soils without a c horizon and divided by the amounts of clay in the same volume p ratio a comparison with the element clay ratio of the mixture of parent material s c ratio allows semi quantitative statements about elemental gains and losses due to solutional processes if only transformation processes are working p ratios should equal the c ratios in the case of fe and mn i e remaining constant with time any depletion or relative or absolute accumulation of the elements can be inferred from values which differ from this trend in the case of phosphorus the p ratios should decrease with time compared to the c ratios relative and absolute gains should result in minor differences between p and c ratios or p ratios exceeding c ratios the results of mass balance calculations on 27 pedons of southwestern germany with a broad amplitude of parameters fe mn p clay redoximorphism as well as the results of chronosequences of different climates parent materials and durations of soil development fits very well with the results of the ratio method developed by using the ratio method areas of depletion and accumulation can be identified in catenary studies as well as linkages between soils inferred e g interpedon translocations deductions of influences of man are possible too the assumptions and restrictions of the method were discussed in detail

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

chemical weathering of a soil chronosequence on granitoid alluvium ii mineralogic and isotopic constraints on the behavior of strontium the use of strontium isotopes to evaluate mineral weathering and identify sources of base cations in catchment waters requires an understanding of the behavior of sr in the soil environment as a function of time our approach is to model the temporal evolution of 87sr 86sr of the cation exchange pool in a soil chronosequence developed on alluvium derived from central sierra nevada granitoids during the past 3 ma with increasing soil age 87sr 86sr of ammonium acetate extractable sr initially decreases from values typical of k feldspar to those of plagioclase and hornblende and then remains constant even though plagioclase and hornblende are absent from the soils after approximately 1 ma of weathering the temporal variation of 87sr 86sr of exchangeable sr is modeled by progressively equilibrating sr derived from mineral weathering and atmospheric deposition with sr on exchange sites as waters infiltrate a soil column observed decreases in quartz normalized modal abundances of plagioclase hornblende and k feldspar with time and the distinct87sr 86sr values of these minerals can be used to calculate sr flux from weathering reactions hydrobiotites in the soils have nearly constant modal abundances chemistry and 87sr 86sr over the chronosequence and provide negligible sr input to weathering solutions the model requires time and soil horizon dependent changes in the amount of exchangeable sr and the efficiency of sr exchange as well as a biologic cycling term the model predicts that exchangeable sr initially has 87sr 86sr identical to that of k feldspar and thus could be dominated by sr leached from k feldspar following deposition of the alluvium the maximum value of 87sr 86sr observed in dilute stream waters associated with granitoids of the yosemite region is likewise similar to that of the k feldspars suggesting that k feldspar and not biotite may be the dominant source of radiogenic sr in the streams this study reveals that when attempting to use strontium isotopes to identify sources of base cations in catchment waters and biomass both preferential leaching of sr from minerals during incipient soil development and changing sr exchange efficiency must be considered along with chemical contributions due to mineral dissolution

geochemistry of surface water in alpine catchments in central colorado usa resolving host rock effects at different spatial scales the us geological survey is conducting a study of surface water quality in the rocky mountains of central colorado an area of approximately 55 000 km 2 using new and existing geologic maps the more than 200 rock formations represented in the area were arranged into 17 groups based on lithologic similarity the dominant regional geologic feature affecting water quality in central colorado is the colorado mineral belt cmb a ne trending zone hosting many polymetallic vein or replacement deposits and porphyry mo deposits many of which have been mined historically the influence of the cmb is seen in lower surface water ph 5 and higher concentrations of so

evaluating u series tools for weathering rate and duration on a soil sequence of known ages four soil profiles of known age 40 250 600 and 3000 ka from the merced soil chronosequence in california were analysed for u and th isotopes and for major and trace element compositions to test the assumption that leaching of u series isotopes is a first order process with an invariant rate constant as frequently assumed when applying this isotopic tool to determine weathering duration and sediment residence time average 230 th 238 u values for each profile decrease from a high of 1 28 in the youngest soil 40 ka to 1 09 0 99 and 0 98 in the 250 ka 600 ka and 3000 ka soils respectively 234 u 238 u values also show variation across the 4 soils the simultaneous variation in 230 th 238 u and 234 u 238 u cannot be explained by a first order kinetic model with invariant rate constants and instead requires that leaching coefficients for the u series isotopes change with time the observed data is consistent with a two stage model that reflects an initial period of fast leaching of u and th from a readily weathered soil pool such as grain boundaries or defects followed by slow leaching from a more resistant soil pool application of such a two stage model may lead to significantly shorter calculated timescales of weathering than those obtained by the widely applied single stage model of u series weathering which assumes no change in leaching coefficients over time the results of this study have wide implications for published and future use of u series tools in weathering studies

chemical weathering rates of a soil chronosequence on granitic alluvium iii hydrochemical evolution and contemporary solute fluxes and rates although long term changes in solid state compositions of soil chronosequences have been extensively investigated this study presents the first detailed description of the concurrent hydrochemical evolution and contemporary weathering rates in such sequences the most direct linkage between weathering and hydrology over 3 million years of soil development in the merced chronosequence in central california relates decreasing permeability and increasing hydrologic heterogeneity to the development of secondary argillic horizons and silica duripans in a highly permeable younger soil 40 kyr old pore water solutes reflect seasonal to decadal scale variations in rainfall and evapotranspiration et this climate signal is strongly damped in less permeable older soils 250 to 600 kyr old where solutes increasingly reflect weathering inputs modified by heterogeneous flow elemental balances in the soils are described in terms of solid state exchange and pore water reservoirs and input output fluxes from precipitation et biomass solute discharge and weathering solute mineral nutrients are strongly dependent on biomass variations as evidenced by an apparent negative k weathering flux reflecting aggradation by grassland plants the ratios of solute na to other base cations progressively increase with soil age discharge fluxes of na and si when integrated over geologic time are comparable to solid state mass losses in the soils implying similar past weathering conditions similarities in solute and sorbed ca mg ratios reflect short term equilibrium with the exchange reservoir long term consistency in solute ratios when contrasted against progressive decreases in solid state ca mg requires an additional ca source probably from dry deposition amorphous silica precipitates from thermodynamically saturated pore waters during periods of high evapotranspiration and result in the formation of duripans in the oldest soils the degree of feldspar and secondary gibbsite and kaolinite saturation varies both spatially and temporally due to the seasonality of plant respired co2 and a decrease in organically complexed al in deeper pore waters k feldspar is in equilibrium and plagioclase is about an order of magnitude undersaturated hydrologic heterogeneity produces a range of weathering gradients that are constrained by solute distributions and matrix and macropore flow regimes plagioclase weathering rates based on precipitation corrected na gradients vary between 3 and 7 10 16 mol m 2 s 1 these rates are similar to previously determined solid state rates but are several orders of magnitude slower than for experimental plagioclase dissolution indicating strong inhibitions to natural weathering partly due to near equilibrium weathering reactions

kelvin type coastal surges generated by tropical cyclones abstract measurements of sea level along the coat of western australia during the period 1969 to 1982 when 12 southward moving tropical cyclones occurred showed distinct peaks with amplitudes of about 1 to 2 m propagating southwards with speeds ranging between 400 600 km day 1 similar observations of sea level along the east coast of australia during the period 1971 to 1980 of 7 southward moving tropical cyclones showed no such peaks these data suggest that the large peaks occurring on the west coast are a result of a resonance phenomenon when the southward component of the cyclone speed is close to that of southward propagating shallow water kelvin waves 11 is shown that the coastal response to moving atmospheric forcing fields may be described by a kelvin type disturbance which at any instant is confined to a localized coastal region dependent on the kelvin wave speed and the longshore speed of the tropical cyclone this region expands in the longshore direction at a rate equal to the difference

two million year record of deuterium depletion in great basin ground waters fluid inclusions in uranium series dated calcitic veins from the southern great basin record a reduction of 40 per mil in the deuterium content of ground water recharge during the pleistocene this variation is tentatively attributed to major uplift of the sierra nevada range and the transverse ranges during this epoch with attendant increasing orographic depletion of deuterium from inland bound pacific storms

taphonomy and palaeoecology of the emuellid trilobite balcoracania dailyi early cambrian south australia monospecific assemblages of the trilobite balcoracania dailyi occur in lower cambrian strata within the adelaide geosyncline in south australia biostratinomic data from single bedding plane assemblages within the warragee and coads hill members of the billy creek formation and white point conglomerate reveal a range of taphonomic signatures from census to within habitat timeaveraged assemblages these assemblages are interpreted as having inhabited protected shallow marginal marine environments size frequency distributions coupled with taphonomic data show that the warragee member census assemblage represents a living population in a physically stressful environment within a tidally influenced lagoon while the original population structure of the coads hill member and white point conglomerate assemblages has been lost due to varying degrees of taphonomic overprinting integration of taphonomic stratigraphic and sedimentological data supports the interpretation of b dailyi as representing an opportunistic species a preserved body cluster from the warragee member assemblage is considered to characterise a congregation formed for the purpose of synchronous reproduction and ecdysis representing one of the oldest examples of gregarious behaviour in the arthropod fossil record furthermore by analogy with modern horseshoe crabs the high number of juveniles i e protaspides and early meraspides within the same assemblage are believed to be constituents of a nursery within the intertidal zone with adults migrating into the shallows to copulate and spawn preserved moult ensembles from the coads hill member and white point conglomerate have enabled the description of exuviation techniques for b dailyi 2007 elsevier b v all rights reserved

soil development on stable landforms and implications for landscape studies abstract soil development parameters include a wide variety of morphological chemical and mineralogical parameters but some of the best indicators of time and surface stability are derived from field morphology over long time spans the most common time function for soil development is exponential or logarithmic in which rates decrease with increasing age over shorter time spans in semi arid and moister climates holocene and pleistocene soil development functions appear as linear segments with holocene rates about 10 to 50 times those of pleistocene rates in contrast to significant temporal variation in rates geographical variation in rates within a the southern great basin and b the east central valley of california is on the order of 2 or 3 times when comparing soil development indices of the semi arid great basin to those of moister central california holocene rates are similar but pleistocene rates are more than 10 times slower in the great basin in a range of climatic settings the reasons for declining rates over time are several and are complexly related to erosional history fluxes in water and dust related to climatic changes rates of primary mineral dissolution and intrinsic soil processes

classification of the late cambrian trilobite idiomesus raymond idiomesus raymond 1924 has been considered to be a late cambrian member of the blind family shumardiidae on the basis of its small size absence of eyes effacement and marginal sutures however evaluation of new material including previously undescribed species demonstrates that idiomesus is a member of the ptychaspidid subfamily ptychaspidinae the genus now includes both sighted and blind species as well as furrowed and effaced species with both marginal and opisthoparian sutures new species are idiomesus granti i greggi and i ultimus

early ordovician community evolution with eustatic change through the middle beekmantown group northeast laurentia abstract the beekmantown group records the important early interval of the ordovician radiation this upper cambrian middle ordovician carbonate dominated tropical succession was deposited near the eastern passive margin of the laurentian platform this depositional setting remained remarkably stable although the craton was flooded repeatedly with eustatic rises and unconformity bound macroscale sedimentary cycles were deposited as successive geological formations the individual depositional cycles i e formations show a nearly identical vertical succession with a type 1 sequence boundary a basal conglomerate transgressive sandstones locally a subtidal shale dominated unit that marks the deepest facies and a highstand carbonate facies with thrombolite buildups in its middle part the thrombolitic buildups of each depositional cycle contain a mollusc dominated macrofauna that changed remarkably from cycle to cycle in the limestones of the upper cambrian ritchie and rathbunville school members the macrofauna is very rare and of low diversity by comparison the absolute abundance of macrofossils is high throughout the lower ordovician thrombolitic limestones the genus level diversity of brachiopods trilobites gastropods and cephalopods increased moderately during the three lower ordovician depositional sequences dramatic changes in cephalopod disparity body size and biomass indicate significant paleoecological changes at the top of the ecosystem food chains and are an indication of community evolution and intrinsic evolutionary processes increased coiling and ornamentation in cephalopods and an increasing number of large gastropod genera with thick shells indicate an escalation among predators we interpret these changes as evidence for a rise in competition within ecological guilds by a continuing increase in internal differentiation of the food web increased organismal interaction and the differentiation of the food web i e community evolution are regarded as a major driving mechanism early in the ordovician radiation

influence of climate and eolian dust on the major element chemistry and clay mineralogy of soils in the northern bighorn basin u s a abstract soil chronosequences in the northern bighorn basin permit the study of chronologic changes in the major element chemistry and clay mineralogy of soils formed in different climates two chronosequences along rock creek in south central montana formed on granitic alluvium in humid and semiarid climates over the past two million years a chronosequence at the kane fans in north central wyoming formed on calcareous alluvium in an arid climate over the past 600 000 years detailed analyses of elemental chemistry indicate that the soils in all three areas gradually incorporated eolian dust that contained less zirconium considered to be chemically immobile during weathering than did the alluvium b and c horizons of soils in the wettest of the chronosequences developed mainly at logarithmic rates suggesting that leaching initially rapid but decelerating dominated the dust additions in contrast soils in the most arid of the chronosequences developed at linear rates that reflect progressive dust additions that were little affected by leaching both weathering and erosion may cause changes with time to appear logarithmic in a horizons of soils under the moist and semiarid climatic regimes clay minerals form with time in the basal b and c horizons and reflect climatic differences in the three areas vermiculite mixed layer illite smectite and smectite form in the soils of the moist climate chronosequence smectite forms in the semiarid climate chronosequence and smectite and palygorskite form in the arid climate chronosequence

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

a regional soil and sediment geochemical study in northern california abstract regional scale variations in soil geochemistry were investigated in a 20 000 km 2 study area in northern california that includes the western slope of the sierra nevada the southern sacramento valley and the northern coast ranges over 1300 archival soil samples collected from the late 1970s to 1980 in el dorado placer sutter sacramento yolo and solano counties were analyzed for 42 elements by inductively coupled plasma atomic emission spectrometry and inductively coupled plasma mass spectrometry following a near total dissolution these data were supplemented by analysis of more than 500 stream sediment samples from higher elevations in the sierra nevada from the same study site the relatively high density data 1 sample per 15 km 2 for much of the study area allows the delineation of regional geochemical patterns and the identification of processes that produced these patterns the geochemical results segregate broadly into distinct element groupings whose distribution reflects the interplay of geologic hydrologic geomorphic and anthropogenic factors one such group includes elements associated with mafic and ultramafic rocks including cr ni v co cu and mg using cr as an example elevated concentrations occur in soils overlying ultramafic rocks in the foothills of the sierra nevada median cr 160 mg kg as well as in the northern coast ranges low concentrations of these elements occur in soils located further upslope in the sierra nevada overlying tertiary volcanic metasedimentary and plutonic rocks granodiorite and diorite eastern sacramento valley soil samples defined as those located east of the sacramento river are lower in cr median cr 84 mg kg and are systematically lower in this suite compared to soils from the west side of the sacramento valley median cr 130 mg kg a second group of elements showing a coherent pattern including ca k sr and ree is derived from relatively silicic rocks types this group occurs at elevated concentrations in soils overlying volcanic and plutonic rocks at higher elevations in the sierras e g median la 28 mg kg and the east side of the sacramento valley median 20 mg kg compared to soils overlying ultramafic rocks in the sierra nevada foothills median 15 mg kg and the western sacramento valley median 14 mg kg the segregation of soil geochemistry into distinctive groupings across the sacramento river arises from the former presence of a natural levee now replaced by an artificial one along the banks of the river this levee has been a barrier to sediment transport sediment transport to the valley by glacial outwash from higher elevations in the sierra nevada and more recently debris from placer au mining has dominated sediment transport to the eastern valley high content of mafic elements and low content of silicic elements in surface soil in the west side of the valley is due to a combination of lack of silicic source rocks transport of ultramafic rock material from the coast ranges and input of sediment from the late mesozoic great valley group which is itself enriched in mafic elements a third group of elements zn cd as and cu reflect the impact of mining activity soil with elevated content of these elements occurs along the sacramento river in both levee and adjacent flood basin settings it is interpreted that transport of sediment down the sacramento river from massive sulfide mines in the klamath mountains to the north has caused this pattern the pb and to some extent zn distribution patterns are strongly impacted by anthropogenic inputs elevated pb content is localized in major cites and along major highways due to inputs from leaded gasoline zinc has a similar distribution pattern but the source is tire wear

left behind delayed extinction and a relict trilobite fauna in the cambrian ordovician boundary succession east laurentian platform new york two completely dissimilar faunal changes occur between the sunwaptan and skullrockian stages ptychaspid and symphysurid biomeres in the uppermost cambrian on the east laurentian craton an undolomitized section in the little falls formation in washington county new york shows a typical biomere extinction with highest sunwaptan trilobites followed by the abrupt appearance of cordylodus proavus zone conodonts and the lowest post extinction trilobites parakoldinioidia endo 5 0 m higher this stage boundary interval is very condensed by comparison with coeval great basin and texas sections approximately 70 km southwest typical pre extinction taxa the catillicephalid acheilops ulrich and several dikelocephalid species are shown for the first time to persist well beyond the extinction as they occur with middle c proavus zone conodonts clavohamulus elongatus or more likely hirsutodontus simplex subzone the ritchie limestone member of the uppermost little falls formation yields a succession of conodont faunas that spans the c elongatus h simplex clavohamulus hintzei subzones middle upper c proavus zone these data prove that the trilobites are a relict fauna that persisted into the symphysurina zone of the skullrockian stage the massive burrow churned mollusc dominated ritchie limestone with the second upper cambrian cephalopod locality in east laurentia represents an inner shelf refugium for sunwaptan trilobites that has not been previously encountered final extinction of typical sunwaptan clades is at least locally diachronous and a simple genus based approach to trilobite biostratigraphy in the cambrian ordovician boundary interval is untenable the relict fauna appears to be distinct at the species level so it is likely that a viable species based biostratigraphy can be developed teridontus gallicus serpagli et al 2008 is a synonym of t nakamurai nogami 1967 and t francisi landing sp nov with a large base and tiny cusp is a lower c proavus zone form new trilobites are acheilops olbermanni westrop sp nov and parakoldinioidia maddowae westrop sp nov the lowest ordovician gailor dolomite is a junior synonym of the tribes hill formation and the ritchie limestone is assigned to the top of the terminal cambrian little falls formation