a low temperature transfer of alh84001 from mars to earth the ejection of material from mars is thought to be caused by large impacts that would heat much of the ejecta to high temperatures images of the magnetic field of martian meteorite alh84001 reveal a spatially heterogeneous pattern of magnetization associated with fractures and rock fragments heating the meteorite to 40 c reduces the intensity of some magnetic features indicating that the interior of the rock has not been above this temperature since before its ejection from the surface of mars because this temperature cannot sterilize most bacteria or eukarya these data support the hypothesis that meteorites could transfer life between planets in the solar system

a weathering related origin of widespread monazite in s type granites the s type granite suites comprising more than a quarter of the extensively developed granites in the lachlan fold belt australia contain monazite which may be related to the chemical weathering of the sedimentary source rocks we report a process whereby chemical weathering fixes mobile rare earth elements ree in hydrous phosphate phases such as florencite and rhabdophane this material contains up to 50 wt lree and occurs as very small particles 3 m dehydration of these hydrous ree phases during anatexis directly yields monazite the low solubility of phosphorus in s type granite melts inhibits dissolution of both monazite and apatite refractory monazite may be thus entrained and transported in s type granites in a manner similar to processes resulting in inherited zircon since both th and the light ree are major components in monazite materials containing this minute phase may be of widespread geochemical significance in both granites and metamorphic rocks

vertical distribution of trace elements in laterite soil suriname abstract the vertical distribution of 20 elements in a 12 5 m thick laterite profile from suriname south america has been investigated using neutron activation analysis atomic absorption spectrometry and x ray fluorescence the mineralogical composition was quantitatively determined from calculations based on results from x ray diffraction thermal gravimetric methods and from the data obtained for major elements using x ray fluorescence the most characteristic change observed in the mineralogy with depth is the increase in kaolinite relative to gibbsite a considerable fractionation with depth is found for different trace elements the enrichment of the lanthanoids la and ce at 3 4 m below surface and of sm and eu at 10 12 5 m depth demonstrates that the distribution of elements despite the similarity in chemical properties is seriously affected by weathering processes the laterite soil samples were also separated in al and fe rich fractions using naoh these separation experiments demonstrated that the trace elements are mainly associated with the fe rich red mud fraction of the laterite soil

chemical alteration in the micro weathering environment within a spheroidally weathered anorthosite boulder a chemical and mineralogical study of the innermost rindlets of a spheroidally weathered boulder from the wichita mountains oklahoma details incipient alteration of minerals along solution channels alteration products in plagioclase areas are highly aluminous whereas ferruginous residuum is commonly found in olivine alteration zones alteration of plagioclase along solution channels results in sharp weathering contacts as contrasted with wider zones of limonite bordering solution channels in olivine in certain instances cores of fresh olivine are surrounded by limonite indicating that diffusion may play a role in this type of alteration mobility of sesquioxides is evidenced by aluminum rich debris adjacent to mafic materials in solution channels and iron bearing material in channels cutting through plagioclase not resolved is whether the movement of sesquioxides in solution channels is by transport of colloidal particulates or by diffusion of dissolved species calcic plagioclase alters to calcite along the innermost solution channel it is postulated that solution exterior to the boulder and undersaturated with respect to calcite enters the rind system via solution channels cut off from the co2 reservoir of the atmosphere by the narrow confines of this solution channel the solution reacts with the bytownite to precipitate calcite apart from the occurrence of calcite no crystalline weathering products were found in the innermost rindlet samples a poorly crystallized illite was identified in the outermost rindlet these findings suggest that initial alteration products on weathering rinds are amorphous and that with time these products attain a degree of identifiable crystallinity

termite nests rhizoliths and pedotypes of the oligocene fluviomarine rock sequence in northern egypt proxies for tethyan tropical palaeoclimates abstract the present study gives an account of the development of several associations of the continental trace fossils within a particular type of palaeosols on the oligocene fluviomarine rock sequence that is equivalent to the jebel qatrani formation and their palaeoclimatic and palaeoenvironmental implications in the northern western desert of egypt this study made use of field observations binocular and polarizing microscopy investigation of isotropism and anisotropism of the materials and the birefringence fabric of the finest materials also the study carried out scanning electron microscopy investigation and x ray diffraction analysis of termite nests rhizoliths and palaeosols the present contribution recognises four pedotypes represented by oxisols aridisols entisols and spodosols based on the macro and micromorphologic attributes mineralogy and by comparison with extant soils the four pedotypes bear similar types of rhizoliths and termite nests but with variable abundance and depths of emplacement the pedogenic features associated with the studied continental trace fossils overprint the marine trace fossils and the sedimentary facies of the studied fluviomarine rock sequence the features of the developed associations reveal that during the oligocene the northern western desert terrain of egypt was closely similar to the fayum depression where the lowland coastal plain was characterised by wet soil and seasonal rainfall the developed associations on the coastal plain represent in situ proxies for the palaeoclimatic setting under which they were formed their attributes indicate that tropical wet dry conditions with the fluctuating moisture regime were prevalent during the deposition of the studied rock sequence

chemical processes affecting the mobility of major minor and trace elements during weathering of granitic rocks abstract the behaviour of 38 major and trace elements as well as changes in the mineralogy have been examined in 10 weathering profiles developing on some portuguese granitic rocks element mobilities are calculated from geochemical data normalized with respect to ti in the fresh parent rock chemical elements are divided into two groups immobile and mobile on the basis of their geochemical distribution during weathering elements that are immobile during weathering are zr hf fe al th nb sc and the ree very mobile are ca na p k sr ba rb mg and si mobile elements are derived mainly from leachable minerals such as feldspars micas and apatites whereas immobile elements are either concentrated in resistate phases or strongly adsorbed by secondary minerals the geochemical behaviour of mn cr v fe and ce is very dependent on redox conditions redox transformations of these elements can be used to set limits on the oxidation state of a weathering suite the ree are mobilized or fractionated during late stages of weathering but not during moderate stages of weathering this fractionation is caused by selective leaching of rocks composed of both stable and unstable minerals containing ree

regolith breccia allan hills a81005 evidence of lunar origin and petrography of pristine and nonpristine clasts mno feo ratios in pyroxene texture abundant brown swirly glass in general typical of lunar regolith breccias and overall composition 75 plagioclase all indicate that allan hills a81005 is of lunar origin it is presumably from a heretofore unsampled region of the moon it differs in detail from other regolith samples e g it has exceptionally low contents of na and kreep a pristine clast contains exceptionally coarse augite compared to similar apollo samples alha81005 is not perceptibly more shocked than typical apollo regolith breccias therefore its discovery on earth lends further credence to suggestions that snc achondrites were derived by impact ejection from mars

uranium and rare earth elements in co2 rich waters from vals les bains france abstract waters from springs at vals les bains result from the mixing of a co2 rich highly mineralized water with dilute shallow subsurface water total content of dissolved species vary from 5 mmol 1 to 100 mmol 1 for many elements mixing of these waters is non linear non conservative and further water rock reactions take place the ph is controlled by co2 outgassing redox conditions are controlled by both the iron hydroxide siderite buffer and the introduction of oxygen with shallow subsurface waters among the major elements concentrations of ca mg mn fe are related to mixing co2 outgassing and carbonate precipitation uranium shows a complex behaviour controlled by carbonate complexing redox conditions mixing of waters and leaching from the rocks the 234 u 238 u activity ratio is near secular equilibrium in the more dilute waters dissolved rare earth element ree patterns are almost flat with a slight negative eu anomaly in the concentrated waters heavy rare earth elements gd yb hree are strongly enriched relative to light rare earth elements ce eu lree we relate the enrichment in hree to water chemistry and to complexing with carbonate species

distribution of uranium and thorium in core samples from the underground research laboratory lease area southeastern manitoba canada abstract petrographic examination of core samples from seven boreholes in the underground research laboratory lease area of the lac du bonnet batholith revealed that the granitic core can be divided into four sample groups 1 grey granite 2 pink granite 3 deep red granite and 4 cream coloured clay rich granite the order of these four groups represents an evolutionary sequence that can be related to the alteration of the grey granite u and th concentrations were determined for the four groups of granitic core samples the u concentration in the four groups of core samples showed a distinct variation whereas the th concentration showed little variation the distribution pattern of u in the four sample groups can be related to its mobility and concentration under various stages of rock alteration while the uniform distribution of th is interpreted to be due to its limited mobility

the hercynian gabbro tonalite granite leucogranite suite of iberia geochemistry and fractionation detailed geochemical and geochronological study of hercynian granites and related rocks in portugal and w spain the ibergranite project has inspired new ideas about their origin formerly regarded as the sole products of crustal anatexis trace element petrology shows descent by crystal fractionation from mantle derived parent magmas of basic composition

mobilities of alkalis alkaline earths and halogens during weathering abstract concentrations of alkali metals alkaline earths and halogens were monitored in an australian weathering profile and in brazilian soils and bauxite the materials analysed are considered to represent a range of chemical weathering histories which are distinguished with respect to their degree of leaching by the dominant aluminosilicate assemblages during initial weathering concentrations of alkalis and alkaline earths are similar or enriched relative to average crustal abundances as weathering proceeds depletion is attenuated by the capacity of a particular element to participate in adsorption and ion exchange processes strong depletion of alkalis and alkaline earths is common as weathering advances and clay minerals are replaced by al oxide phases e g gibbsite with much lower capacities for exchanging and incorporating ions halogen concentration trends are more variable f retention during weathering is likely due to substitution in mineral phases for hydroxyl groups cl and i are commonly observed to accumulate as weathering advances and some of these accumulations may be due to atmospheric additions

geochemistry of the granitic rocks and their minerals from serra da estrela central portugal abstract several types of hercynian peraluminous granitic rocks ranging from biotite muscovite granodiorite to muscovite granite occur in the horst of serra da estrela variation diagrams of most major and trace elements of the rocks and biotites and cr and v of muscovites show fractionation trends however nb li rb k rb li mg variation diagrams of the rocks and muscovites and also of sn cs cs k of the muscovites indicate that the muscovite granite probably originated by another mechanism least squares analysis of major elements and modelling of trace elements indicate that the coarse grained porphyritic biotite muscovite granite granite porphyry and fine to medium grained muscovite biotite granite were derived from the granodiorite magma by fractional crystallization of plagioclase quartz and biotite emplacement of granodiorite magma took place at 3 5 3 kb and 720 c granites and granite porphyry probably originated about 690 c but were completely crystallized about 520 c o2 was about 10 17 for the granodiorite and hcl hf was higher whereas log h2o hcl was lower in the granodiorite than in the other granitic rocks of the fractionated series the coarse grained porphyritic biotite muscovite granite was hydrothermally altered between 400 350 c and 260 230 c at about 1 5 1 kb the hydrothermal fluids were probably mainly meteoric in origin but some fluids released during the late stage of granite solidification might also have been involved

megarhizoliths in pleistocene aeolian deposits from gran canaria spain ichnological and palaeoenvironmental significance the pleistocene dune field of tufia located on the east of gran canaria spain contains different stratigraphic levels of indurated pillar like structures that are interpreted as megarhizoliths the megarhizoliths occur at the top of different aeolian sets and reach 31 5 cm in diameter and over 1 m in height these scattered free standing vertical cylindrical to slightly conical columns usually appear as hollow cylinders displaying elliptical cross sections aligned with the prevailing wind on the leeward side of some specimens the external wall shows a tail of rock matrix resembling a sort of wind shadow these tails and other remains of the associated rock matrix show a texture composed of long horizontal parallel cylinders orientated with the wind internally the most complete structures show five concentrically arranged zones zone a is a central pore corresponding to the cavity originally occupied by the root zones b and c which include alveolar and laminated carbonate textures indicating that carbonate precipitation was mostly induced by the roots and their associated microorganisms and zones d and e consisting mostly of aeolian sands in d the sand grains show thin micritic coatings whereas in e vadose aragonite cements can be seen on the grain surface suggesting a less biogenic influence in their formation the degree of cementation and the time of the precipitation of carbonate around the roots controlled the preservation of these zones thus in some cases zones b c and or d are not preserved cylinders are up to 30 the diameter of the root that nucleated them the presence of the megarhizoliths at the top of the aeolianite beds indicates that aeolian sedimentation halted several times allowing soil formation and plant colonisation during slightly more humid periods the occurrence of megarhizoliths is further proof of the alternation of arid and slightly more humid climates in the north atlantic during the last glacial period it is also noted that they may be misinterpreted as animal trace fossils or tree trunk casts resulting in incorrect ichnological or palaeoenvironmental interpretations

early carbonate diagenetic fabrics in the rhizosphere of late pleistocene aeolian sediments analysis of a range of aeolianite deposits from the western mediterranean roquetas in southern spain and campo de tiro in mallorca and the bahamas crab cay on san salvador island has shown that biota can be important in the diagenesis of deposits in the vadose zone and this may aid in the interpretation of palaeoenvironments particularly where pedogenic calcretes are absent this paper looks at how the growth of roots into dune sediments and the associated profusion of micro fauna and micro flora can have on a local scale a profound affect on the early diagenetic and sediment fabric these fabrics are affected at three levels 1 at the site of the former root 2 directly surrounding the root the peritrophic zone and 3 from the peritrophic zone to a few tens of centimetres from the former root

paleoclimatic records of late triassic paleosols from central ethiopia abstract the present study documents the major paleosols types within the lower adigrat sandstone in the blue nile basin of central ethiopia with the aim of unraveling the paleoclimatic signatures embedded in them the paleosols developed within an 80 m thick siliciclastic succession deposited in a mixed tide and wave dominated incised valley estuary during the late triassic based on down profile variations in pedogenic features three major paleosol types i e types i ii and iii were identified type i paleosols dominate the lower part of the section and are interpreted as moderately well drained argillic vertisols the dominant pedogenic process was shrinking and swelling of expandable clays i e smectite through repeated wetting and drying cycles the morphologies and the mineralogy of the paleosols provide persuasive evidence for pedogenesis under semi arid subtropical climatic conditions with pronounced wet dry seasonality highly fluctuating soil moisture regime and deep groundwater table the presence of a calcic bk horizon deep in the profiles is consistent with elevated soil moisture deficits and low to moderate mean annual precipitation map type ii paleosols interpreted to represent vertic gleysols are more common in the middle part of the section the pervasive gleying reflects poor soil drainage and a shallow groundwater table where the soil is waterlogged most of the year these paleosols suggest a humid tropical climate characterized by alternating wet dry seasonality but with more wet months per year the top of the unit is dominated by type iii paleosols that represent gleyed oxisols reflecting a more humid equatorial climate marked by wet seasons elevated annual soil moisture content and a high water table the presence of plinthite laterite is in agreement with a wet equatorial climate characterized by extensive chemical weathering and long periods of landscape stability the observed vertical progression in the major paleosol types from vertsols to gleysols and oxisols implies a systematic change in the number of wet months most probably in response to regional tectonics and long term climate change because the number of wet months is in part related to latitude and monsoonal climates the upward stratigraphic trend in paleosol orders is interpreted to signal the northward or equatorward migration of the blue nile basin and central ethiopia within pangea from dry subtropical low latitudes in the early late triassic carnian norian toward the humid wet equatorial possibly monsoonal paleoclimatic zone in the late triassic norian rhaetian

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

a micromorphological record of contemporary and relict pedogenic processes in soils of the indo gangetic plains implications for mineral weathering provenance and climatic changes

reconnaissance of upper jurassic morrison formation ichnofossils rocky mountain region usa paleoenvironmental stratigraphic and paleoclimatic significance of terrestrial and freshwater ichnocoenoses seventy five types of ichnofossils documented during a four year reconnaissance study in the upper jurassic morrison formation demonstrate that highly diverse and abundant plants invertebrates and vertebrates occur throughout most of the morrison or equivalent strata invertebrate ichnofossils preserving the most environmentally and climatically sensitive in situ behavior of morrison organisms are in nearly all outcrops terrestrial ichnofossils record biotic processes in soil formation indicating soil moisture and water table levels freshwater ichnofossils preserve evidence of water depth salinity and seasonality of water bodies ichnofossils categorized as epiterraphilic terraphilic hygrophilic and hydrophilic new terms reflect the moisture regime where they were constructed the ichnofossils are vertically zoned with respect to physical chemical and biological factors in the environment that controlled their distribution and abundance and are expressed as surficial shallow intermediate and deep the sedimentologic stratigraphic and geographic distribution of morrison ichnofossils reflects the environmental and climatic variations across the basin through time marginal marine tidal to brackish water ichnofossils are mainly restricted to the windy hill member very large to small termite nests dominate the salt wash member similar size ranges of ant nests dominate the brushy basin member soil bee nests dominate in the salt wash decreasing in abundance through the brushy basin deeper and larger insect nests indicate more seasonal distribution of precipitation and rainfall shallower and smaller insect nests indicate either dry or wet substrate conditions depending on the nest architecture and paleopedogenic and sedimentologic character of the substrate trace fossil indicators of flowing or standing water conditions are dominant in the tidwell member and in fluvial sandstones of the salt wash and brushy basin members large communities of perennial freshwater bivalve traces are abundant in the tidwell and brushy basin members but to a lesser extent in the salt wash member shallow crayfish burrows indicating a water table level close to the surface 1 m are restricted to channel bank and proximal alluvial deposits in the salt wash recapture and brushy basin members sauropod theropod pterosaur and other vertebrate tracks occur throughout the morrison formation associated with alluvial lacustrine and transitional marine shoreline deposits ichnofossils and co occurring paleosols in the morrison reflect the local and regional paleohydrologic settings which record the annual soil moisture budget and were largely controlled by the climate in the basin contributions to near surface biologic systems by groundwater from distant sources were minor except where the water table perennially seasonally or ephemerally intersected the ground surface the jurassic morrison formation in the southern portion of the basin experienced a mosaic of seasonal climates that varied from a drier tidwell windy hill deposition to a wetter lower and middle salt wash deposition and slightly drier upper salt wash deposition tropical wet dry climate returning to a wetter tropical wet dry climate near the end of morrison deposition brushy basin deposition the northern part of the basin experienced similar trends across a mosaic of mediterranean climate types the range and mosaic pattern of wet dry morrison climates is analogous to the range of climates and their seasonal variability that dominates the african savanna today

polygenetic history of paleosols in middle upper pennsylvanian cyclothems of the illinois basin u s a part i characterization of paleosol types and interpretation of pedogenic processes abstract the morphology mineralogy and stratigraphic and lateral distribution of paleosols in pennsylvanian moscovian gzhelian atokan virgilian mixed marine and terrestrial coal bearing strata i e cyclothems in the illinois basin ib are presented in order to determine the dominant pedogenic processes within a cyclic sedimentary depositional framework paleosol morphologies range from weakly developed horizons with evidence of rooting and little to no pedogenic structure to horizons with well developed pedogenic slickensides angular blocky structure and carbonate nodules and tubules the majority of paleosols in strata from the basin interior preserve 1 low chroma gley colors 2 identifiable fossil plant organic matter that increases in abundance upward in the profiles toward the interpreted paleo surface and 3 calcite sphaerosiderite and pyrite cements and nodules in contrast paleosols in strata from the northern margin of the basin display high chroma colors and calcite cements and less fossil organic matter sphaerosiderite and pyrite cements these observations indicate that paleosols from the basin interior underwent a multi phase pedogenic and shallow burial history characterized by an initial better drained oxygenated stage under seasonal precipitation followed by a poorly drained reducing stage while paleosols from the northern margin of the basin experienced overall more oxygenated conditions throughout their pedogenic development x ray diffraction analysis of the 2 m size fraction of paleosol matrix in ib paleosols indicates a mineralogical composition dominated by kaolinite randomly interstratified r0 and ordered r1 illite smectite i s and subordinate amounts of chlorite these combined observational and mineralogical datasets indicate that significant changes in paleohydrology were largely responsible for the development of pennsylvanian soil profiles in the ib

trapped noble gases indicate lunar origin for antarctic meteorite the isotopic abundances of the noble gases he ne ar kr xe are reported for antarctic meteorite alha81005 it contains solar wind implanted gases whose absolute and relative concentrations are quite similar to lunar regolith samples but not to other meteorites alha81005 also contains a large excess 40ar component which is identical to the component in lunar fines implanted from the lunar atmosphere large concentrations of cosmogenic 21ne 82kr and 126xe in alha81005 indicate a total cosmic ray exposure age of 2 108 years the noble gas data alone are strong evidence for a lunar origin of this meteorite

geochemical studies in the drainage basin of the rio vouga portugal abstract the hydrothermal waters in the vouzela region portugal have a temperature of 68 c and are characterized by a high content of f li b bicarbonate sulphate and silica ninety three water samples including two hydrothermal waters were analyzed for major and trace elements in order to investigate the genesis of the hydrothermal water in the vouzela region two older hercynian granites are exposed the abas granite and the sao pedro do sul granite the abas granite is intersected by the ribama fault albitization is ubiquitous other alteration effects are tourmalinization k feldspathization and muscovitization these processes and the associated sn w deposits were induced by the intrusion of the younger viseu granite in the present situation rainwater penetrates into the abas granite especially via the ribama fault and the greisenization zone it becomes part of a hydrothermal system leaches li f b and silica and rises via the termas fault in the hydrothermal springs of termas de sao pedro do sul geothermal equilibrium calculations yield a temperature of 205 10 c for the thermal reservoir the percentage of mixing with cold groundwater near the surface in the circulation system is estimated at 73 the circulation system is possibly maintained by the heat generated by the decay of u th k and their daughter products elements which are encountered in extremely high concentrations in the sao pedro do sul granite

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

formation of a martian pyroxenite a comparative study of the nakhlite meteorites and theo s flow the unusual composition of the nakhlites a group of pyroxenitic martian meteorites with young ages presents an opportunity to learn about nonbasaltic magmatic activity on another planet however the limited number of these meteorites makes unraveling their history difficult a promising terrestrial analog for the formation of the nakhlites is theo s flow in ontario canada this atypical 120 m thick flow differentiated in place forming distinct layered lithologies of peridotite pyroxenite and gabbro theo s pyroxenite and the nakhlites share strikingly similar petrographies with concentrated euhedral to subhedral augite grains set in a plagioclase rich matrix these two suites of rocks also share specific petrologic features mineral and whole rock compositional features and size and spatial distributions of cumulus grains the numerous similarities suggest that the nakhlites formed by a similar mechanism in a surface lava flow or shallow intrusion their formation could have involved settling of crystals in a phenocryst laden flow or in situ nucleation and growth of pyroxenes in an ultramafic lava flow the latter case is more likely and requires steady state nucleation and growth of clusters of pyroxene grains and olivine in the nakhlites circulating in a strongly convecting melt pool followed by settling and continued growth in a thickening cumulate pile trapped pockets of intercumulus liquid in the pile gradually evolved finally growing fe enriched rims on cumulus grains with sufficient evolution the melt reached plagioclase supersaturation causing rapid growth of plagioclase sprays and late stage mesostasis growth

calcification generates protons for nutrient and bicarbonate uptake abstract the biosphere s great carbonate deposits from caliche soils to deep sea carbonate oozes precipitate largely as by products of autotrophic nutrient acquisition physiologies protons constitute the critical link calcification generates protons which plants and photosynthetic symbioses use to assimilate bicarbonate and nutrients a calcium atpase based trans mechanism underlies most biological calcification this permits high calcium carbonate supersaturations and rapid carbonate precipitation the competitive advantages of calcification become especially apparent in light and nutrient deficient alkaline environments calcareous plants often dominate the lower euphotic zone in both the benthos and the plankton geographically and seasonally massive calcification concentrates in nutrient deficient environments including alkaline soils coral reefs cyanobacterial mats and coccolithophorid blooms structural and defensive uses for calcareous skeletons are sometimes overrated

oxygen and silicon isotopes in alha 81005 the antarctic meteorite alha 81005 has oxygen and silicon isotopic compositions identical with lunar highland rocks the oxygen is distinctly unlike that in calcium rich achondrites the isotopic data are entirely consistent with a lunar origin for the meteorite

stepwise climate change recorded in eocene oligocene paleosol sequences from central oregon successions of paleosols bounded by erosional surfaces in fluvial sediments of the eocene oligocene strata of central oregon can be interpreted as terrestrial equivalents of the unconformity bound units of sequence stratigraphy in the upper part of the upper eocene clarno formation and in the lower part of the lower eocene lower miocene john day formation truncation surfaces separate otherwise conformable alluvial deposits and allow for stratigraphic subdivision into informal members lower and upper red hill claystones in the clarno formation and lower middle and upper big basin members and lower turtle cove member in the john day formation paleosols in each member show a stepwise change in the degree of weathering of the most strongly developed paleosols kaolinite rich ultisollike paleosols in lower red hill claystones late eocene 42 43 ma smectite rich alfisol like paleosols in the upper red hill claystones late eocene 41 42 ma alfisols and ultisol like paleosols in the lower big

rummaging through earth s attic for remains of ancient life abstract we explore the likelihood that early remains of earth mars and venus have been preserved on the moon in high enough concentrations to motivate a search mission during the late heavy bombardment the inner planets experienced frequent large impacts material ejected by these impacts near the escape velocity would have had the potential to land and be preserved on the surface of the moon such ejecta could yield information on the geochemical and biological state of early earth mars and venus to determine whether the moon has preserved enough ejecta to justify a search mission we calculate the amount of terran material incident on the moon over its history by considering the distribution of ejecta launched from the earth by large impacts in addition we make analogous estimates for mars and venus we find for a well mixed regolith that the median surface abundance of terran material is roughly 7 ppm corresponding to a mass of approximately 20 000 kg of terran material over a 10 10 square km area over the same area the amount of material transferred from venus is 1 30 kg and material from mars as much as 180 kg given that the amount of terran material is substantial we estimate the fraction of this material surviving impact with intact geochemical and biological tracers

natural enrichment of arsenic in loch lomond sediments abstract concentrations of arsenic in surface or near surface sediment in 12 of 13 cores from the three major basins of loch lomond are substantially enhanced up to 675 mg kg compared with background values of 15 50 mg kg sedimentary as profiles are attributed to post depositional enrichment processes since there are no recent significant sources of environmental as contamination anthropogenic or natural in the loch lomond area the enrichments can be interpreted in terms of post depositional diagenetic remobilization processes in sediment reducing zones followed by upward migration of as through interstitial waters and oxidation adsorption precipitation reactions in near surface oxidizing layers confirmation of the diagenetic adsorption hypothesis is provided directly by the analysis of as species 1 5 81 g l in pore water and indirectly via comparison with sedimentary phosphorus

vertical distribution of trace elements in laterite soil suriname discussion discussion sur l article de topp s e sabu b roaldset e et jorgensen p paru dans chem geol nld 1984 47 159 174

ichnofossils and rhizoliths of the nearshore fluvial jebel qatrani formation oligocene fayum province egypt abstract the ichnofossils and rhizoliths of the oligocene jebel qatrani formation of egypt are among the best preserved most diverse in form and most abundant of such structures yet recognized in fluvial rocks twenty one forms are described the ichnofauna contains traces domichnia fodinichnia cubichnia of probable annelid insect crustacean and vertebrate origin these include the first described fossil nest structures and gallery systems of subterranean termites isoptera the first examples of ophiomorpha from wholly fluvial rocks and the first fossil vertebrate burrows from the african tertiary rhizoliths associated with the ichnofauna and those occurring elsewhere document a variety of small wetland plants coastal mangroves and much larger trees the environment suggested by these traces is consistent with the coastal tropical to subtropical monsoonal rain forest with adjacent more open areas that is indicated by independent evidence of sedimentology paleontology and paleopedology

laboratory simulation of explosive volcanic loading and implications for the cause of the k t boundary intense explosive volcanism was simulated by preheating samples to 600 c and subjecting them to dynamic stress pulses of 0 9 and 1 3 gpa the resultant ejecta was examined optically and by transmission electron microscopy tem deformation and failure was entirely by brittle fracture and most fractures were irregular and intergranular none of the features typical of k t boundary sediments and of ejecta from meteorite impact craters planar deformation features amorphization mosaicism were observed there were also no signs of intracrystalline plasticity we conclude that explosive volcanism is incapable of producing the microstructural features seen at the k t boundary and that they must have been caused by impact of a large meteorite

biopores and root features as new tools for improving paleoecological understanding of terrestrial sediment paleosol sequences abstract the important role of roots and rhizosphere processes is accepted for the top soil but still under debate for the deep subsoil including soil parent material especially for terrestrial sediments like loess and dune sands roots and root traces are mostly recognized in profile descriptions but not interpreted in the paleoenvironmental context further synchrony of sediment deposition and root trace formation is commonly assumed this is challenged by partially large maximum rooting depths of plants exceeding the soil depth and by frequent occurrence of secondary carbonates and biopores of potential root origin below recent soil and paleosols to improve understanding of paleoenvironmental records in terrestrial sediment paleosol sequences recent roots and root traces including calcified roots and root derived biopores were investigated in six soil loess and dune sand profiles across central and se europe visualization of small carbonate accumulations diameter 1 mm frequently called pseudomycelia by x ray microtomographic scanning and morphologic comparison with rhizoliths calcified roots diameter mostly 3 20 mm up to 100 mm possible indicate root origin of the former therefore requiring renaming to microrhizoliths quantification of roots biopores rhizoliths and microrhizoliths on horizontal levels yielded maximum frequencies of 2100 m 2 4100 m 2 196 m 2 and 12 800 m 2 respectively considering the pore volume remaining from former root growth this indicates their significant contribution to structural properties of the sediments and paleosols depth distribution of roots and root traces was frequently related to soil and paleosols respectively and mostly showed maximum frequencies within or immediately below these units root traces are therefore not necessarily of similar age like the surrounding sediment but are typically of younger age the time lag between root traces and the surrounding stratigraphic unit can vary between small time periods likely decades to centuries in case of microrhizoliths and several millenia in case of larger rhizoliths penetrating several stratigraphic units with assumed radii of former rhizosphere extension of 5 mm for microrhizoliths a frequency of 12 500 m 2 corresponded to 100 rhizosphere area in the respective depth interval these findings emphasize the meaning of root traces in sediment paleosol sequences potential temporal and spatial inhomogeneity of root growth on the one hand especially for shrub and tree vegetation and occurrence of root remains of different age and origin in identical depth intervals on the other hand hamper the assessment of the chronologic context of these with the surrounding sediment or paleosol nevertheless root traces in terrestrial archives provide valuable information with respect to paleovegetation and paleoenvironmental conditions if their chronological context is known

changing uranium distributions during weathering of granite abstract changes in uranium distribution during chemical weathering were investigated in three granitoid types from the new england district new south wales australia over a range of samples from unweathered rock to profoundly weathered material uranium fission track micromapping was used to characterise the three principal modes of u abundance in unweathered granitoid rock low concentrations of background u in fine fractures in quartz and in deuterically altered feldspar biotite and hornblende interstitial u in concentrations between 140 and 1500 g g 1 principally in hydrated fe oxide mn oxide and clay minerals and the greatest proportion as resistate u 90 4000 g g 1 located in the accessory minerals during low temperature chemical weathering a significant net u loss occurs and the remaining u is redistributed amongst the three modes background u is depleted and the mobilised u is adsorbed by interstitial aggregates thereby increasing interstitial u concentrations resistate u is also depleted as sphene zircon monazite and acicular apatite retain their initial u concentrations but are reduced in modal abundance prismatic apatite fluorite and allanite are progressively removed the significant net loss of u during chemical weathering provides uranium for potential secondary sedimentary mineralisation and implies that weathered granitoid rock is not an appropriate element in the geological barrier for nuclear waste

ejection of rock fragments from planetary bodies the recent discovery of alha81005 a small meteorite that undoubtedly came from the moon has raised questions about how an intact rock fragment could survive acceleration to planetary escape velocities this acceleration could only have been produced by a large impact on the lunar surface a small amount of material 0 005 to 0 02 projectile volume may be ejected from an impact crater at speeds exceeding lunar escape velocity without suffering petrographically detectable shock damage the ejected material is protected by stress wave interference close to the free surface the existence and size of this zone depend upon parameters such as the rise time of the stress pulse produced by an impact the fragment size is a function of ejection velocity the lunar meteorite was ejected during an impact event that produced a crater at least 3 6 km in diameter other meteorites may have originated in a similar way

the role of fungal biomineralization in the formation of early carboniferous soil fabrics paleosols in the lower carboniferous limestones of south wales commonly contain needle fibre calcite which is an unusual form of calcite recently shown to form by the calcification of fungal hyphae in present day soils the needle fibre calcite occurs in two associations in the paleosols as coatings on sediment grains and as rhizocretions the former can be compared with the microbial grain coatings of quaternary calcretes the latter represent the sites of fungal coats on roots and are interpreted as probable ectomycorrhizae a symbiotic fungal sheath root association these findings suggest that biomineralization was important in the formation of soil fabrics during the carboniferous as it is in present day soils

a pedotype approach to latest cretaceous and earliest tertiary paleosols in eastern montana a pedotype approach to the study of paleosols emphasizes individual profiles it is an alternative approach to the study of geosols which are laterally extensive suites of paleosols or pedofacies which are pedogenically distinctive sedimentary facies this is the first pedotype study of paleosols across the cretaceous tertiary boundary in eastern montana pedotypes allow assessment of sedimentation and fossilization the sequence of paleosols across the cretaceous tertiary boundary at bug creek is one of high temporal resolution because most available geological time can be accounted for by differing degree of development inferred for each pedotype paleosols at bug creek include pedotypes that preserve plant fossils well but were unfavorable for preservation of fossil vertebrates pedotypes also allow reassessment of ecosystem change despite indications of catastrophe at the cretaceous tertiary boundary the array of paleocene and cretaceous pedotypes are not strikingly different the upper cretaceous hell creek formation includes pedotypes interpreted as gleyed alfisols inceptisols and entisols probably formed under seasonally water logged forest and mean annual rainfall of the order of 900 1200 mm most paleosols of the lower paleocene tullock formation were histosols but some can be interpreted as gleyed inceptisols and entisols probably formed under bald cypress swamps in a humid climate with 1200 mm mean annual rainfall broadly comparable pedotypes were present before and after the cretaceous tertiary boundary although paleocene flood plain forest lived in paleosols chemically a little more oligotrophic than cretaceous paleosols this modest difference supports the idea that change to coaly facies in the earliest paleocene was a local shift in sedimentary environment such local changes do not begin to account for profound disruption in specific composition of plant and animal communities at the cretaceous tertiary boundary in eastern montana

localized shock melting in lherzolitic shergottite northwest africa 1950 comparison with allan hills 77005 the lherzolitic martian meteorite northwest africa nwa 1950 consists of two distinct zones 1 low ca pyroxene poikilically enclosing cumulate olivine fo70 75 and chromite and 2 areas interstitial to the oikocrysts comprised of maskelynite low and high ca pyroxene cumulate olivine fo68 71 and chromite shock metamorphic effects most likely associated with ejection from the martian subsurface by large scale impact include mechanical deformation of host rock olivine and pyroxene transformation of plagioclase to maskelynite and localized melting pockets and veins these shock effects indicate that nwa 1950 experienced an equilibration shock pressure of 35 45 gpa large millimeter size melt pockets have crystallized magnesian olivine fo78 87 and chromite embedded in an fe rich al poor basaltic to picro basaltic glass within the melt pockets strong thermal gradients minimum 1 c m existed at the onset of crystallization giving rise to a heterogeneous distribution of nucleation sites resulting in gradational textures of olivine and chromite dendritic and skeletal olivine crystallized in the melt pocket center has a nucleation density 1 0 x 10 3 crystals mm 2 that is two orders of magnitude lower than olivine euhedra near the melt margin 1 6 x 10 5 crystals mm 2 based on petrography and minor element abundances melt pocket formation occurred by in situ melting of host rock constituents by shock as opposed to melt injected into the lherzolitic target despite a common origin nwa 1950 is shocked to a lesser extent compared to allan hills alh 77005 45 55 gpa assuming ejection in a single shock event by spallation this places nwa 1950 near to alh 77005 but at a shallower depth within the martian subsurface extensive shock melt networks the interconnectivity between melt pockets and the ubiquitous presence of highly vesiculated plagioclase glass in alh 77005 suggests that this meteorite may be transitional between discreet shock melting and bulk rock melting

tillites diamictites and ballistic ejecta of large impacts the primary evidence for the temporal and spatial distribution of glaciation prior to the cenozoic is the occurrence of tillites these are diamictites poorly sorted mixtures of very coarse grained to fine grained sediments and associated deposits which have features considered diagnostic of glacial action the discovery that many diamictite bearing sequences were the products of debris flows and related mass flows with contemporaneous rainout of coarse sediment has led to the reinterpretation of many tillites as glaciomarine debris flow deposits fallout of ballistic ejecta from the impact of large asteroids or comets can also create large scale debris flows with simultaneous rainout of debris recent calculations of the predicted volume and distribution of impact generated diamictites suggest that they should be common in the geologic record moreover ballistic debris flow deposits can apparently exhibit a number of features considered characteristic of glacial deposits e g striated clasts er

observations of high velocity weakly shocked ejecta from experimental impacts a small proportion of meteorites found on earth are thought to come from planet sized bodies1 2 the lunar meteorites are now well established as having come from the moon3 6 on the basis of direct comparison with lunar samples the snc meteorites shergottites nakhlites and chassignites seven achondrite meteorites distinguished by extremely young formation ages 1 3 gyr high volatile contents distinctive oxygen isotopic ratios and rare earth compositions are igneous rocks believed2 to have formed on a planet probably mars but it is hard to reconcile the weakly shocked nature of many lunar and snc meteorites with the strong shock metamorphism known to accompany impacts of the size required to eject material from a planet sized body computer modelling7 10 of impacts has yet to resolve this issue although it has been proposed9 10 that surface rarefaction near an impact can produce high velocity weakly shocked ejecta here we present the results of a cratering experiment which separates and captures the ejecta from diffe rent regions around the impact site we recover high velocity weakly shocked material as predicted9 10 lending additional support both to our understanding of cratering mechanics and to a planetary or lunar origin for the snc and lunar meteorites

simulation of trajectories and maximum reach of distal impact ejecta under terrestrial conditions consequences for the ries crater southern germany abstract for impact craters with dimensions such as the ries crater corresponding to a 1 km meteorite it has become a standard reference in textbooks on planetary science that under terrestrial conditions distal transfer of boulders may reach as far as 200 km in order to test this assumption we simulated the impact induced ballistic transfer of limestone boulders ejected out of the ries crater and have come to the conclusion that reutersche blocke and ries brockhorizonte found at distances of up to 130 km away are distal ries ejecta boulders alleged to be ries components found in northern switzerland at distances of up to 200 km away can be related to the ries event if the parameters of our numerical simulation are stretched to its limits our simulation includes the following assumptions and variables 1 boulders are ejected from the interference zone at a very early stage of impact 2 starting conditions may range between velocities of 1 and 4 km s and 35 to 65 for the flight path angle 3 drag free and transitional conditions at the impact site have been incorporated into the density model of the atmosphere 4 a typical boulder is represented by an suitable aerodynamic drag model 5 an aerothermal heat model was used to determine heat load

significance of different modes of rhizolith preservation to interpreting paleoenvironmental and paleohydrologic settings examples from paleogene paleosols bighorn basin wyoming u s a abstract different modes of preservation of root traces rhizoliths provide information on soil moisture regimes in alluvial paleosols in the paleogene fort union and willwood formations of the bighorn basin wyoming u s a this paper links different styles of rhizolith preservation to paleosols whose other pedogenic attributes provide information on ancient soil drainage consequently the paleodrainage significance of different rhizolith preservation patterns is established more confidently rhizoliths consisting of elongate gray mottles rhizohaloes with red rims are common in relatively well drained red paleosols the gray zones are depleted of iron fe whereas the color of the rims indicates hematite accumulation these features are typical of surface water gley processes that caused fe and manganese mn to move from the root channel outward to the soil matrix calcareous rhizocretions either calcareous tubular concretions or micro accumulations of carbonate within gray rhizotubules are also common in moderately well drained red paleosols more poorly drained purple paleosols also have rhizoliths consisting of fe depletion zones however the rhizohaloes are surrounded by yellow brown goethite rims rather than red hematitic rims in many paleosols the red and yellow brown accumulation rims were partly removed by continued depletion producing abundant irregular shaped mottles the nature of the rhizohalo and the color of the fe oxide rim provide information about the intensity of gleying that a paleosol underwent the poorly drained paleosols also show rhizoliths preserved as goethite accumulations contained within gray depletion zones indicating movement of reduced fe from the matrix towards the root channel probably as a result of groundwater gley processes the goethite accumulations are intermingled locally with lignite representing preservation of the root organic material some rhizoliths are preserved as tube shaped concentrations of small 0 1 0 2 mm diameter black spheres whose color indicates a mix of mn and fe oxides these are most common in paleosols with low chroma gray matrix colors indicating very poor drainage the very poorly drained paleosols also show rhizoliths preserved in jarosite which is an oxidation product of pyrite careful observational and geochemical analysis of rhizoliths which are common in continental deposits can help produce a clearer and more thorough interpretation of ancient drainage conditions information about degree of ancient soil wetness or moisture is important for understanding past climatic conditions and for reconstructing terrestrial paleolandscapes

the weathering of basalt and relative mobilities of the major elements at belbex france abstract a basalt and its weathered profile have been analysed for major elements graphical examination shows al fe and ti to have been essentially immobile determining mobility sequences for this deposit is complicated by the long pedogenetic history of the area three different sequences are presented two for different stages of weathering integrated over time and one that reflects the weathering regime of the present day

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

paleosols in clastic sedimentary rocks their geologic applications interest in pre quaternary paleosols has increased over the past decade in large part because they have proved to be beneficial in solving diverse geological problems the majority of paleosols are described from continental deposits most commonly from alluvial strata criteria for recognizing these paleosols have been extensively described however classifying them has proved more complicated pre quaternary paleosols are generally classified according to one or more modern soil classification systems although one new classification has been proposed exclusively for paleosols to avoid problems using the modern soil classifications in addition to taxonomic classification paleosols can be categorized according to the interplay among deposition erosion and the rate of pedogenesis when they formed paleosols can be solitary if they formed during a period of landscape stability following the development of an unconformity such paleosols are commonly thick and extremely well developed more commonly paleosols are vertically stacked or multistory because they formed in sedimentary systems undergoing net aggradation if erosion was insignificant and sedimentation was rapid and unsteady compound paleosols generally formed if the rate of pedogenesis exceeded the rate of deposition composite paleosols developed thick cumulative paleosols indicate that erosion was insignificant and that sedimentation was relatively steady both autogenic and allogenic processes can influence depositional and erosion patterns and thus affect the kinds of soils that form consequently paleosols can help to interpret the history of sediment deposition and the autogenic and allogenic processes that influenced a sedimentary basin paleosols are also helpful in stratigraphic studies including sequence stratigraphic analyses they are used for stratigraphic correlations at the local and basinal scale and some workers have calculated sediment accumulation rates based on the degree of paleosol development in addition to their stratigraphic applications paleosols can be used to interpret landscapes of the past by analyzing paleosol landscape associations at different spatial scales ranging from local to basin wide in scope at the local scale lateral changes in paleosol properties are largely the result of variations in grain size and topography at the scale of the sedimentary basin paleosols in different locations differ because of basinal variations in topography grain size climate and subsidence rate paleosols are used to reconstruct ancient climates even to estimate ancient mean annual precipitation map and mean annual temperature mat ancient climatic conditions can be interpreted from modern soil analogs or by identifying particular pedogenic properties that modern studies show to have climatic significance stable carbon and oxygen isotopes are also used to interpret ancient climate and some effort has been made to estimate mat from isotopic composition on the basis of

zeolites in soil environments the limited occurrence of these minerals has resulted in a scant knowledge about their properties in the soils zelazny and calhoun 1977 as pointed out by the above authors the occurrence of natural zeolites in soils is rare and not well known and only about 75 papers have been published describing the occurrence of zeolites in soils these occurrences range from hot humid soils in india to cold arid soils in the dry valleys of antarctica most of these reports describe residual zeolite phases that have persisted from the parent material during soil formation however there are reports of zeolites that have formed in soil environments a variety of natural zeolites have been found in soils including analcime chabazite clinoptilolite gismondine laumontite mordenite natrolite phillipsite and stilbite over the past 25 years natural zeolites have been examined for a variety of agricultural and environmental applications because of their unique cation exchange adsorption and molecular sieving properties and their abundance in near surface sedimentary deposits natural zeolites have been used as soil conditioners slow release fertilizers carriers for insecticides and herbicides remediation agents in contaminated soils and dietary supple ments in animal nutrition ming and allen this volume pond 1995 these applications can result in direct or indirect incorporation of natural zeolites into soils if these minerals are to be used effectively in these applications it will be necessary to understand the long term stability and effects of zeolites in soils or soil like systems several reviews have been published on the occurrences and properties of zeolites in soils zelazny and calhoun 1977 ming and dixon 1987c ming and dixon 1988 ming and mumpton 1989 boettinger and graham 1995 this chapter provides an overview and update on the occurrence of zeolites in soils and briefly describes methodology used for identifying and characterizing zeolites

antarctic meteorite alha 81005 a piece from the ancient lunar crust a 128 mg sample of the antarctic meteorite alha 81005 was analysed for major and trace elements by instrumental neutron activation techniques the meteorite or at least its major components may be older than 4 billion years and represent a piece of the ancient lunar crust before the formation of the large basins on the front side of the moon the evidence is derived from the low absolute content of incompatible elements and their slightly different fractionation pattern from kreep the dominant source for these elements on the front side the basically chondritic pattern of siderophile elements ni co ir au is clearly distinguished from younger basin related meteoritic components

a classification system for buried paleosols abstract paleosols formed on prior surfaces of the geologic past and include buried exhumed and relict kinds exhumed and relict ones are subaerial and have been classified according to systems of classification for other soils at this interface one of these systems soil taxonomy includes relict and exhumed paleosols with the subaerial ground soils but would need extensive modification to include buried paleosols our approach to paleosol classification like that of the recently published mack james monger system uses some soil taxonomy orders however we use proxy criteria to incorporate plaeosols that have become lithified and add the prefix krypt hidden or covered to all order names enduring properties are used as proxy criteria because base saturation by the nh4oac method and cementation of paleosols tends to increase with additions of salt gypsum and carbonate to buried paleosols we chose as proxy criteria the weatherable mineral content of sands and silts cation exchange capacity nh4oac method to clay ratio total analysis of the