pedogenic carbonate proxies for amount and seasonality of precipitation in paleosols the depth to carbonate nodular bk horizon in soils d in cm is correlated with mean annual precipitation p in mm so that bk horizons are deep in subhumid regions but shallow in semiarid regions previous quantifications of this relationship are unchanged by this new compilation of 807 soils p 137 24 6 45 d 0 013 d 2 where r 2 0 52 and standard error s e 147 mm in most north american postglacial soils the bk horizon is thin and well defined whereas in monsoonal tropical soils of pakistan and kenya the bk horizon is thick and diffuse data from 675 modern soils define the relationship between the thickness of soil with nodules t in cm and mean annual range of precipitation m in mm difference between monthly means of wettest and driest months m 0 79 t 13 71 where r 2 0 58 and s e 22 mm the relationship between carbonate nodule size s in cm and soil age a in ka is quantified by 9 radiocarbon dated soils from las cruces new mexico a 3 92 s 0 34 where r 2 0 57 and s e 1 8 k y these transfer functions are applied to reconstructing paleoclimatic change from paleocene eocene paleosols of the north horn formation and flagstaff limestone of axhandle canyon utah the terminal paleocene spike of warmth recorded by fossil plants in nearby wyoming was coincident with a brief peak in both mean annual precipitation and mean annual range of precipitation in utah

palaeoclimate of the late jurassic of portugal comparison with the western united states investigation of the palaeoclimatic conditions associated with upper jurassic strata in portugal and comparison with published palaeoclimate reconstructions of the upper jurassic morrison formation in western north america provide important insights into the conditions that allowed two of the richest terrestrial faunas of this period to flourish geochemical analyses and observations of palaeosol morphology in the informally named upper jurassic lourinhaformation of western portugal indicate warm and wet palaeoclimatic conditions with strongly seasonal precipitation patterns palaeosol profiles are dominated by carbonate accumulations and abundant shrink swell vertic features that are both indicative of seasonal variation in moisture availability the d 18 osmow and ddsmow values of phyllosilicates sampled from palaeosol profiles range from 22ae4 to 22ae7 and 53ae0 to 37ae3 respectively these isotope values correspond to temperatures of formation between 32 c and 39 c 3 with an average of 36 c which suggest surface temperatures between 27 c and 34 c average 31 c on average these surface temperature estimates are 1 c higher than the highest summer temperatures modelled for late jurassic iberia using general circulation models elemental analysis of matrix material from palaeosol b horizons provides proxy chemical index of alteration minus potassium estimates of mean annual precipitation ranging from 766 to 1394 mm year with an average of approximately 1100 mm year palaeoclimatic conditions during deposition of the lourinhaformation are broadly similar to those inferred for the morrison formation except somewhat wetter seasonal variation in moisture availability does not seem to have negatively impacted the ability of these environments to support rich and relatively abundant faunas the similar climate between these two late jurassic terrestrial ecosystems is probably one of the factors which explains the similarity of their vertebrate faunas

quantifying pedogenic carbonate accumulations using stable carbon isotopes abstract four pedons from a late quaternary chronosequence developed in calcareous alluvium in central texas were investigated to assess the ability of the stable c isotope method to partition and quantify pedogenic carbonate accumulations to quantify pedogenic carbonate accumulations with this method 13 c values of bulk pedogenic and parent carbonate must be known for each pedon 13 c values of bulk carbonate were measured on a horizon by horizon basis the parent carbonate end member for all pedons was approximated by averaging the bulk 13 c values for all horizons from the weakly developed floodplain soil the diffusion model of cerling 1984 and quade et al 1989 was used to estimate the pedogenic carbonate end member quantification of pedogenic carbonate accumulations by the isotopic method was compared to quantitative estimates conducted by field morphology binocular light microscope point counts and thin section point counts results suggest that the isotopic method is superior to other methods of quantifying pedogenic carbonate accumulations whole soil pedogenic carbonate accumulations as calculated by the isotopic method for the chronosequence were 1 1 to 4 vol by 2000 years 2 4 to 15 vol by 5000 years and 3 1 to 12 vol after 15 000 years these results reveal net soil carbonate loss through time for central texas climates this corroborates similar conclusions drawn for the same chronosequence using mass balance analysis to calculate the flux of carbonate net carbonate loss through time also indicates that these soils do not serve as long term carbonate c sequesters

depth to pedogenic carbonate horizon as a paleoprecipitation indicator an analysis of 1168 modern soil profiles from the u s natural resources conservation service yields no correlation between mean annual precipitation and depth to the top of the carbonate horizon r 2 0 03 p 0 001 parent material and soil texture both play negligible roles in this regression when combined with similar published studies n 1481 r 2 improves slightly r 2 0 31 p 0 001 caution is therefore advised in using this or any previously published regression for inferring paleoprecipitation from paleosols however in the combined data set carbonate horizon bearing soils correlate with a mean annual precipitation of 760 mm p 0 05 thus the presence vs absence of pedogenic calcium carbonate is a good indicator of paleoprecipitation above or below this value

early oligocene paleosols of the dagshai formation india a record of the oldest tropical weathering in the himalayan foreland abstract this study reports paleopedological features of the fossil soils that formed during the earliest phase of continental sedimentation in the himalayan foreland the fluvial sequence of the dagshai formation 31 6 3 9 ma to 30 3 3 9 ma exposed along the koshaliya river nw himalaya contains four pedofacies named pedofacies a d of ferruginous paleosol sequences contained within overbank sediments the dagshai formation unconformably overlies the marine subathu formation pedofacies a consists of 3 4 well developed ferruginous paleosols overlain by gray sandstone beds pedofacies b d are marked by a progressive decrease in pedogenesis these paleosols occur as 0 5 m to 1 5 m thick bw bt btk bk bss horizons that are marked by extensive development of rhizoliths pedogenic carbonate and iron rich clay pedofeatures that correspond to modern entisols inceptisols alfisols and vertisols based on early oligocene paleogeographic position of the northward drifting indian plate it is inferred that these paleosols were formed at 18 n paleolatitude in the dagshai sub basin in the himalayan foreland micromorphology geochemical analyses weathering indices and stable isotope composition of paleosols indicate tropical climate paleoprecipitation of 947 1256 mm and paleotemperature of 25 c with an initial phase of monsoonal conditions during pedogenesis these paleoclimatic conditions favored c3 paleovegetation immediately after the transition from greenhouse to icehouse conditions

physical compaction of vertic palaeosols implications for burial diagenesis and palaeo precipitation estimates burial compaction is one of several major obstacles to estimating palaeoprecipitation from depth to pedogenic carbonate in favourably preserved palaeosols palaeosols must be decompacted and the preburial depth to the pedogenic carbonate obtained vertic palaeosols may be particularly good candidates for palaeoprecipitation estimates because of their increased likelihood of preserving clastic dykes one of the best features for estimating burial compaction compaction estimates from clastic dykes and literature based depth of burial estimates suggest vertic palaeosols undergo significantly less burial compaction than may be commonly assumed late carboniferous vertic palaeosols buried to 2 5 3 0 km compacted to 93 of their original thickness in contrast clastic dykes in a nonpedogenic shale directly underlying one of the late carboniferous palaeosols records compaction to 70 of original thickness similarly obtained burial compaction and burial depth estimates for early carboniferous ordovician and proterozoic vertic palaeosols were used to test a burial compaction curve and equation specific to vertic palaeosols results suggest this vertic calibrated curve and equation can be used to estimate burial compaction for vertic palaeosols lacking clastic dykes but additional testing is needed naturally high bulk densities may have limited the compactibility of vertic palaeosols likewise high initial bulk density and an abundance of swelling clays may have severely limited the transmissivity of some vertic palaeosols as they passed from pedogenic to burial environments upon burial these vertic palaeosols may have behaved as closed systems which has implications for understanding their diagenetic modification additional efforts to understand burial compaction of vertic palaeosols also promises to improve our understanding of aquifer aquiclude and hydrocarbon reservoir seal relationships in sedimentary basins containing intercalated palaeosols

paleoenvironmental reconstruction of jurassic dinosaur habitats of the vega formation asturias spain jurassic aged strata of asturias spain contain trace fossils including sauropod theropod and ornithopod dinosaur footprints but their paleoenvironmental context has been relatively unstudied a coastally exposed continuous section at playa de vega shows a clear transition from the marine middle jurassic rodiles formation to the terrestrial upper jurassic vega formation within the 100 m of vega formation stratigraphy that was logged there four distinct types of paleosols were identified 1 entisols 2 inceptisols 3 vertisols and 4 composite or cumulative paleosols the paleosol types and their features indicate a floodplain depositional setting with short stature shrubby vegetation theropod and ornithopod tracks have been identified at the base of the section indicating that a dinosaurian fauna was present at playa de vega during the jurassic results from well characterized climofunctions based on modern soils and paleosol b horizon chemical composition of the inceptisols and vertisols yield mean annual precipitation estimates of 400 980 mm yr 1 and mean annual temperature estimates of 8 15 c the presence of vertisols with both evidence for shrink and swell behavior and dispersed pedogenic carbonate is consistent with a strongly seasonal precipitation regime the 13 c analyses of pedogenic carbonates yield values that range from 7 09 to 8 88 relative to vienna peedee belemnite vpdb and indicate carbon dioxide levels about six times pre industrial levels consistent with previous results the asturian vertebrate track assemblage is remarkably similar to that of the morrison formation western united states but it has greater overall richness the pattern is reversed for body fossils the reconstructed paleoenvironmental and paleoclimatic conditions indicate similar depositional settings in both places but with a cooler wetter more seasonal environment in asturias the greater seasonality indicated by the vega formation relative to the morrison formation may explain the observed differences in richness

c4 plant productivity and climate co2 variations in south central texas during the late quaternary abstract a continuous record of organic carbon 13c from a buried soil sequence in south central texas demonstrates 1 strong coupling between marine and adjacent continental ecosystems in the late pleistocene as a result of glacial meltwater entering the gulf of mexico and 2 ecosystem decoupling in the holocene associated with a reduction of meltwater and a shift in global circulation patterns in the late pleistocene reduction in c4 plant productivity correlates with two well documented glacial meltwater pulses 15 000 and 12 000 14c yr b p indicating a cooler than present adjacent continental environment increased c4 production between 11 000 and 10 000 14c yr b p suggests that the younger dryas was a warm interval responding to the diversion of glacial meltwater away from the mississippi river with waning meltwater flow c4 productivity generally increased throughout the holocene culminating in peak warm intervals at 5000 and 2000 14c yr b p shifts in the abundances of c3 c4 plants through the late quaternary show no correlation to ecophysiological responses to atmospheric co2 concentration

late devonian tetrapod habitats indicated by palaeosols in pennsylvania abstract late devonian famennian tetrapods from the duncannon member of the catskill formation near hyner pennsylvania usa have been found within palaeosols that offer a new line of evidence for their ancient environments hyner has yielded at least two fossil tetrapod species hynerpeton basseti and densignathus rowei subhumid vertisol palaeosols and semiarid aridisol palaeosols alternate at hyner as in other catskill formation sedimentary cycles attributed to milankovitch eccentricity periods 100 ka tetrapods were found in palaeosols of subhumid not semiarid phases of 100 ka palaeoclimate cycles in addition palaeosols at hyner record an unusually warm and wet climatic episode compared with other palaeosols of the catskill formation and correlated with the european annulata black shale event tetrapod bones are cracked and disarticulated in red palaeosols of an oxbow lake margin as if victims of dry season death decay and subaerial weathering vegetation choked swales and floodplains would have afforded shelter from 3 4 m long predatory fish hyneria lindae of open water and offered food of large dead fish small live fish arachnids myriapods and scorpions if these early tetrapods lived on land at all it was during wet seasons of feeding and breeding rather than fatally dry seasons supplementary material chemical data are available at http www geolsoc org uk sup18373

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

palaeosol stratigraphy across the permian triassic boundary bogda mountains nw china implications for palaeoenvironmental transition through earth s largest mass extinction abstract upper permian and lower triassic palaeosols from northeastern tethyan localities exposed within the bogda mountains nw china provide a wealth of information regarding long term palaeoclimatic and palaeoenvironmental variations wuchiapingian palaeosols are characterized by intense redoximorphy accumulation of vascular plant matter accumulation of clay minerals and fe oxides slickensides and clastic dikes suggesting a soil moisture regime that ranged from perennially wet to distinctly seasonal in soil moisture budget changsinghian to early induan palaeosols include subsurface accumulations of clay and carbonate as well as surficial accumulations of organic matter indicative of sub humid to sub arid soil moisture and variable soil moisture regimes induan to olenekian palaeosols contain pedogenic caco 3 accumulations and gypsum pseudomorphs indicating a drier environment characterized by net soil moisture deficiency elemental composition of palaeosol matrix was used to estimate palaeoprecipitation through the chemical index of alteration minus potassium cia k proxy estimates from various wuchiapingian strata indicate relatively stable palaeoprecipitation during the late changsinghian and early induan palaeoprecipitation appears to have decreased from 1100 to 230 180 mm year over less than 100 m of vertical stratigraphic section in the induan and olenekian palaeoprecipitation appears much less stable than in wuchiapingian with values vacillating from 290 to 1014 mm year the transition to a relatively unstable precipitation state coincides generally with the permian triassic boundary and may reflect climatic disturbances associated with the end permian extinction event in addition to altered atmospheric circulation patterns resulting from regional tectonics moisture availability and expansion of the subtropical high pressure belt

life of a bifurcation in a gravel bed braided river channel bifurcation is a key element in braided rivers determining the water and sediment distribution and hence controlling the morphological evolution recent theoretical and experimental findings as well as field observations showed that bifurcations in gravel bed braided rivers are often asymmetrical and highly unstable in this paper field data are presented on a bifurcation in the tagliamento river northeast italy the planform configuration of the bifurcation and its temporal evolution was monitored by an automatic digital camera during a series of seven floods with different magnitudes this remote sensing technique allowed a high temporal resolution pictures were acquired every hour that was proved to be essential in a highly dynamic system as the one considered here digitized maps of the channels provided information on the location of the bifurcation the width of the anabranches the angle between them along with the occurrence and migration of sediment bars data were acquired at two different water levels giving the possibility to compare low and high flow conditions the monitored bifurcation is largely unstable and shows sudden changes in the water distribution mainly driven by the bar migrating in the upstream channel and entering the distributaries a relationship between width asymmetry and flood magnitude was observed confirming previous analyses moreover recent theoretical findings were applied in order to test the possibility to estimate general trends in bifurcation evolution the analysis pointed out the relevance of a correct assessment of the characteristic temporal scales as the bifurcation evolves on a timescale similar to that of bar migration and flood duration understanding the interactions between these processes is therefore crucial in order to increase the ability to model and predict the morphological evolution of a braided network copyright 2012 john wiley sons ltd

palaeoclimatic and site specific conditions in the early permian fossil forest of chemnitz sedimentological geochemical and palaeobotanical evidence abstract as significant indicators of deep time palaeoclimate a number of new palaeontological pedological and geochemical characteristics are provided for the chemnitz fossil lagerstatte to depict more precisely its environmental conditions for the first time several lines of evidence indicate that this fossil forest instantaneously preserved by volcanic deposits once received an annual precipitation of around 800 1100 mm but grew on a nearly unweathered palaeosol although the composition of this rich and diverse t0 assemblage suggests a hygrophilous dense and multi aged vegetation dominated by conservative lineages the habitat was affected by environmental disturbances and pronounced seasonality repeated changes in local moisture availability are suggested by geochemical proxies the co occurrence to intergrowth of calcic and ferric glaebules in the palaeosol and developmental traits of perennial vegetational elements specific substrate adaptation is reflected by different root systems and cyclic growth interruptions recorded in the stems branches and roots of long lived woody plants many differentially adapted terrestrial animals complete the more comprehensive reconstruction of a late sakmarian ecosystem and its climatic and preservational controls albeit spatially confined this diverse in situ record may contribute to understand wetland dryland dynamics of sub tropical northern hemisphere pangaea

preservation of a paleo vertisol and an estimate of late mississippian paleoprecipitation abstract a late mississippian paleosol satisfying all of the morphological criteria required for classification of holocene vertisols provides quantitative paleoclimate information in addition to the now commonplace interpretation of precipitation seasonality based on the presence of vertic features paleoprecipitation was estimated using the empirical relationship between depth to pedogenic carbonate horizon in quaternary soils burial compaction erosional truncation and high paleoatmospheric co2 concentration all factors that complicate paleoprecipitation estimates are unusually well constrained for this paleosol allowing for 10 compaction the paleosol had a pre burial depth of 100 cm for the pedogenic carbonate horizon yielding a mean annual paleo precipitation estimate f 648 141 mm this is comparable to the mean annual precipitation for brownsville texas where similar soils are found today a dolomicrite crust developed in gilgai microlows is well preserved in the paleo vertisol higher late mississippian paleotemperatures and rates of evapotranspiration associated with a lower latitude paleogeography for central tennessee during the late mississippian may explain in part why holocene coastal vertisols in the brownsville region lack surficial crusts similar to that of the paleo vertisol we qualitatively define the late mississippian climate of central tennessee as semiarid

new weathering index improves paleorainfall estimates from vertisols vertisols are clayey shrink swell soils that are widely recognized in the rock record thus generating the need to better understand the dynamics of elemental concentrations on the development of weathering indexes for climate interpretations we assessed the weathering performance of the four major base forming oxides cao mgo na 2 o k 2 o along a modern vertisol climosequence spanning a strong precipitation gradient and discovered that the concentration of bulk soil cao and mgo yields the strongest correlation to mean annual precipitation map based on this fi nding we introduce the calmag weathering index defi ned as al 2 o 3 al 2 o 3 cao mgo 100 which improves rainfall estimates for vertisols relative to the wellestablished cia k chemical index of alteration minus potassium weathering index rather than documenting the hydrolysis of weatherable minerals common in many other soil orders in vertisols calmag principally tracks the fl ux of calcium and magnesium sourced from calcium carbonate detrital clay and exchangeable ca 2 and mg 2 application to two mesozoic paleosols reveals that in drier climates cia k yields higher map estimates than calmag but that the reverse is true in wetter climates this work improves paleorainfall estimates from vertisols and suggests that a family of weathering indexes is needed for different paleosol types

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

pedogenic iron manganese nodules in vertisols a new proxy for paleoprecipitation the total fe content of pedogenic iron manganese fe mn nodules taken from a vertisol climosequence on the texas gulf coastal plain correlates with mean annual precipitation map r 2 0 92 no significant trend of total fe fetot with depth was noted in profiles using the regression developed from modern vertisol data fetot contents of paleozoic paleo vertisol fe mn nodules yielded map regimes comparable to previously inferred paleoenvironmental interpretations paleoprecipitation estimates derived from fe mn nodules for an uneroded late mississippian paleo vertisol are very close to estimates determined from a depth to pedogenic carbonate horizon dch proxy determined from the modern vertisol climosequence the lack of soil depth dependence of the fe mn nodule proxy provides a consistent paleoprecipitation estimate even in eroded paleo vertisols and in combination with the dch may be useful in determining original paleosol thickness

soil climate system across the prairies in midwestern u s a abstract among mollisols across the prairie plains from eastern iowa to western kansas coincident systems of loess stratigraphy and sedimentology climate and soils are separated at 96 to 97 w longitude to the east udolls are formed peopeoria loess that dates back 14 000 radiocarbon years and are currently in a subhumid climate to the west ustrols are cormed in bignell loess that dates back to

tectonic implications of 40ar 39ar hornblende ages from late proterozoic cambrian plutons in the avalon composite terrane nova scotia canada alternative interpretation and reply

distinguishing climate in the soil record using chemical trends in a vertisol climosequence from the texas coast prairie and application to interpreting paleozoic paleosols in the appalachian basin u s a a suite of vertisols clay rich soils with high shrink swell potential were examined across a climosequence climatic transect in twelve soil pits from the coast prairie of texas in order to determine if mean annual precipitation map exerts a control on the chemistry of these soils and if the observed chemical trends are useful for interpreting paleoclimate records of paleovertisols in the geologic record the precipitation regime of the climosequence spans a range between 144 and 86 cm year with moisture regimes classified as udic udic ustic ustic and aridic ustic in a general northeast to southwest direction other soil forming factors such as soil age 35 40 ka parent material fluviodeltaic beaumont formation of late pleistocene age landscape low relief coastal plain and vegetation prairie or mixed woody shrubs are relatively constant across the climosequence climate sensitive chemical proxies of map identified include dithionite citrate extractable fe fedith acid oxalate extractable fe feoxal caco3 equivalent caco3equiv s and ammonium acetate extractable na k and mg naacet kacet and mgacet respectively which vary across the climosequence because of differences in effective depths of leaching and intensity of wetting and drying cycles these standard usda wet chemical climate proxies are related to bulk oxide or element chemistry of soils and paleosols measured using xrf which supports the use of geochemical climate proxies for interpreting the paleoclimate records of paleovertisols application of the chemical index of alteration minus potash cia k geochemical climofunction to late mississippian paleosols from the appalachian basin of the eastern u s demonstrates evidence for a shift from a lower to a higher map paleoclimate that is consistent with previous paleoclimate models and with observed morphological changes in the paleosols we advocate actualistic research using bulk chemistry of soils and paleosols as a means of obtaining soil information useful for interpreting paleosols in the geological record

paleosols as indicators of paleoenvironment and paleoclimate paleosols are ancient soils that have been incorporated into the geological record soils form in response to interactions among the lithosphere hydrosphere biosphere and atmosphere so paleosols potentially record physical biological and chemical information about past conditions near earth s surface as a result paleosols are an important resource for terrestrial environmental and climatic reconstructions long standing paleosol research topics include morphology classification and clay mineralogy all of which provide information about pedogenic processes and local paleoenvironments paleosols are also used to infer processes involved in the development of stratigraphic architecture and basin evolution recent paleosol research has introduced semiquantitative and quantitative measures for environmental and chronometric reconstructions that provide insight into major regional to global changes in temperature precipitation and atmospheric pco2 these new proxies focus on morphological and chemi

vertisol genesis in a humid climate of the coastal plain of texas u s a numerous genetic studies of vertisols have been conducted using qualitative and semi quantitative methods across a broad range of climates however no detailed investigations exist on vertisols formed in humid climates using multiple pedogenic techniques on both a microlow ml and microhigh mh hence we sampled and characterized a ml and mh from a lake charles pedon mean annual rainfall 1090 mm mean annual temperature 20 c in the late pleistocene coastal plain beaumont formation of east texas according to the official series description the lake charles classifies as a fine smectitic hyperthermic typic hapludert with mollic and calcic diagnostic horizons coupled with field morphology and characterization data micromorphology and constituent mass balance interpretations were used to reconstruct the major pathway of pedogenesis in response to greater water recharge the ml contains darker colors more organic carbon greater depth of carbonate leaching and lower ph the proportion of oxalate extractable iron increases toward the surface and is in greater abundance in the ml than mh in contrast dithionite extractable iron increases with depth and has similar quantities in both the ml and mh the parent material and lower profiles contain asepic microfabric dominated by micaceous rich coarse clay and silt the asepic zone deep contains an abundance of soft carbonate masses and iron manganese segregations that appear to be forming contemporaneously with the presence of argillans substantiating clay translocation during the early history of soil formation sepic microfabric dominates the upper profiles of both the ml and mh in part from the transformation of biotite to smectite which is more pronounced in the microlow because of more intense weathering hard carbonate nodules and iron manganese concretions are abundant in the upper sepic zone and contain skelsepic microfabric suggesting that they are no longer growing dilation was the dominant strain force during pedogenesis from volume expansion in response to crack infills and shrink swell processes mass flux calculations indicate that total clay gains occurred in both the ml and mh during pedogenesis late pleistocene vertisols appear to approach steady state when forming in humid climates the soil mechanics model best explains the observed depth distribution of properties including slickensides with pedoturbation playing a secondary role in the genesis of these humid climate vertisols

revisiting the equable climate problem during the late cretaceous greenhouse using paleosol carbonate clumped isotope temperatures from the campanian of the western interior basin usa abstract greenhouse climates such as the late cretaceous period provide important reference frames for understanding modern anthropogenic climate change upper cretaceous terrestrial climate proxies have been interpreted as evidence for equable climates with reduced seasonal variations in temperature however climate models have largely failed to reproduce these reconstructions unless parameters such as atmospheric co2 concentrations are set to unreasonable values to help resolve such model proxy disagreements we reconstruct mean annual range in temperature mart for the campanian 75 ma kaiparowits south central utah and two medicine northwest montana formations using warmest mean monthly temperature reconstructions from the clumped isotope composition of paleosol carbonate nodules and reconstructions of local mean annual air temperatures from other methods an evaluation of the applicability of bulk elemental soil geochemistry temperature proxies in these deposits supports the use of previous leaf physiognomy based estimates of mean annual temperature for our mart reconstructions we test the validity of several common assumptions made in reconstructing mart in two novel ways first mart is commonly calculated as twice the difference between local mean annual air temperature and warmest mean monthly temperature and we validate this method by estimating modern mart for a range of environments using climate reanalysis data second we constrain the effect of radiative soil heating on our soil carbonate temperature estimates by showing that for most environments likely to be preserved in the geologic record summer soil temperatures are 9 c larger than previous proxy reconstructions of late cretaceous mart these results add to a growing body of literature showing that terrestrial mart during ancient greenhouse periods was not significantly different from modern seasonal temperature variations finally the similarity in mart between the kaiparowits and two medicine formations suggests that latitudinal changes in mart did not contribute to the faunal provincialism that has been proposed by some paleontologists