soil genesis and mineralogy across a volcanic lithosequence abstract lithology is a principle state factor of soil formation interacting with climate organisms topography and time to define pedogenesis a lithosequence of extrusive igneous lithologies rhyolite obsidian dacite andesite and basalt was identified in the clear lake volcanic field in the coast range of northern california to determine the effects of lithology on pedogenesis clay mineralogy and soil physiochemical properties based on regional landscape erosion rates 0 2 0 5 mm yr 1 the soil residence times for the investigated pedons 150 cm deep were of the order of 3000 to 7500 years indicating that the soils developed under the relatively stable holocene mesic xeric climate regime soils from all lithologies developed to a similar xeralf taxonomy with remarkably consistent physiochemical properties although total fet and dithionite citrate extractable fed iron concentrations diverged across lithologies the degree of weathering as assessed by the fed fet ratio was similar across the lithosequence in spite of large differences in silica content of the parent materials the clay mineralogical assemblage of all lithologies was dominated by kaolin minerals kaolinite and or halloysite all pedons displayed an increase in halloysite and the degree of halloysite hydration with increasing depth except the basalt pedon which was dominated by kaolinite with only trace halloysite we attribute this lack of halloysite in the basalt pedon to the lower silica activities associated with this silica poor lithology there was a lack of nanocrystalline minerals across all lithologies as inferred from selective dissolution the dominance of crystalline materials is a function of the xeric soil moisture regime whereby summer soil profile desiccation promotes dehydration and crystallization of metastable nanocrystalline precursors further the pronounced summer dry period results in dehydration of halloysite 1 0 nm to halloysite 0 7 nm also referred to as meta halloysite in some literature together with transformation to kaolinite in the upper soil profile in spite of the relatively young soil residence times of these soils holocene age the effects of lithology persisted only in differences in fe oxide concentrations fed as well as a lack of significant halloysite in basalt pedons the overwhelming effect of climate in these highly weatherable parent materials narrowed the trajectory of pedogenesis resulting in soils from contrasting lithologies converging on kaolin mineralogy a lack of nanocrystalline constituents and similar soil physiochemical properties

patterns and processes of shell fragmentation in modern and ancient marine environments shell fragments are important components of many recent and fossil marine benthic ecosystems and can provide crucial information on past and present environmental conditions interpreting such fragments requires integrated knowledge in various fields and the information potential is therefore rarely optimally utilized this paper uses the definition of a fragment as being a piece of shell having less than 90 of its original form it then outlines the potential characteristics pathways and fates that shells and their fragments can have fragmentation is a key factor shaping the shelly part of death assemblages but it is difficult to interpret because it can be broadly caused by ecological biostratinomic or diagenetic processes and also depends on shell strength strength in turn reflects multifunctionality during ontogeny and depends on a complex set of skeletal and taphonomic factors therefore no particular shell parameter clearly determines strength but thickness microstructure type and degree of organic matrix have the strongest influence on pre and post mortality strength size measurements are usually less important for shell strength than thickness although ecologically complex size refuges from predation do exist similarly shell shape sculptural features and specific aperture types in gastropods provide various defence strategies rather than increasing strength per se key ecological factors of fragmentation include predation due to crushing peeling along with mistaken predation selfinflicted damage during predation and burrowing and more physical aspects such as impacts by stones modern studies must consider damage by benthic commercial fisheries or dredging by scientific vessels key biostratinomic factors include transportinduced abrasion littoral zone of surf washed beaches bioerosion and dissolution mainly sublittoral environments diagenetically fragmentation during compaction mainly occurs when shells are in direct contact with one another or with coarser grains taphonomic features e g drillholes have only minor influence a key step in interpreting fragments is to categorize breakage into repaired versus unrepaired diagnostic versus nondiagnostic and severe versus localized damage quantifying the above categories can then provide useful information on breakage patterns and underlying processes understanding the many characteristics of shells and their fragments is a significant interpretive tool in maximizing the information gain in palaeoecological and taphofacies analyses d 2003 elsevier science b v all rights reserved

the last glacial maximum in central and southern north island new zealand a paleoenvironmental reconstruction using the kawakawa tephra formation as a chronostratigraphic marker abstract kawakawa tephra formation comprising oruanui ignimbrite flow member and aokautere ash airfall member represents the products of an exceptionally large and widespread volcanic eruption from taupo volcanic centre in the north island of new zealand the eruption occurred during the last glacial maximum and is radiocarbon dated at c 22 6 ka b p thermoluminescence ages are in broad agreement with the radiocarbon age the presence of aokautere ash in loess deposits in alluvial gully fills on river terraces and its absence from unstable sites permits a detailed assessment of geomorphic activity during the last glacial maximum widespread erosion of regolith aggradation of river valleys and deposition of loess particularly in the period following eruption of the kawakawa point to a cold dry variable climate a collation of pollen data for sediments containing aokautere ash and those 14c dated in the range 17 23 ka shows that tall forest was highly restricted in the central and southern parts of the north island an apparently subalpine grassland shrubland was present at sites from present sea level to over 800 m elevation suggesting that factors other than lower temperatures such as exposure to wind and frost fire and reduced rainfall were important in controlling vegetation patterns we conclude that the interval 23 13 ka b p broadly equivalent to oxygen isotope stage 2 represents the period of greatest environmental change in the north island

alleged mosasaur bite marks on late cretaceous ammonites are limpet patellogastropod home scars new data contradict the mosasaur bite hypothesis for the origin of holes seen in placenticeras ammonites from the late cretaceous pierre shale and bearpaw formation of the western interior of north america observations of a limpet infested placenticeras ammonite and of several placenticeras specimens with radular scratch marks reveal that the limpets dwelled on floating ammonites and their homing activity produced circular depressions when altered during diagenesis the depressions mimic tooth punctures crushing experiments on fresh nautilus shells using a mosasaur robot show that mosasaur bites could not have produced holes resembling those in the fossils furthermore sectioning of bitten ammonites reveals that sepia are sometimes intact under the holes an observation irreconcilable with penetration by a tooth we present an alternative interpretation that the alleged bite marks in placenticeras ammonites are really limpet home scars that were altered after burial while predation of mosasaurs on ammonites remains a possibility it would have to be demonstrated by other criteria our findings do not support mosasaur ammonoid coevolution in the late cretaceous

on shape orientation and structure of atmospheric cells inside wind rolls in two sar images synthetic aperture radar sar images of the sea surface often show roll vortex structures and other features which in general are spread out over several length scales and may present spatial periodicity as well as intermittence standard techniques such as two dimensional 2 d fourier analysis are unsuitable both when it is of interest to detect intermittent phenomena and to analyze the spatial disposition of the backscatter structures inside the sar images for the above reasons the 2 d continuous wavelet transform analysis has been applied to two european remote sensing mission sar images over the mediterranean sea showing wind rolls and atmospheric gravity waves through the evaluation of the wavelet variance map which ideally corresponds to the 2 d fourier spectrum it has been possible to assess the presence of two main energy areas at large from 7 28 km and small from 0 5 2 km spatial scales while the large scale fluctuations may be ascribed to atmospheric gravity waves and other features induced by the surroundings the small scale fluctuations reveal the inner structure of the atmospheric wind rolls the sar like maps obtained by adding the wavelet coefficient maps pertaining to the small scales have permitted us to highlight the high and low intensity backscatter cells associated with the wind rolls these cells have been statistically characterized by means of the frequency distributions of the size of the cells maximum and minimum axes of the orientation of the maximum axis and of their area the results indicate that high and low intensity backscatter cells have similar characteristics in both cases studied they appear of elliptic shape with the major axis along the wind roll direction the average axes ratio is 2 5 1 the frequency distributions of the cell area indicate a continuous distribution of sizes without significant gaps

predatorial borings in late precambrian mineralized exoskeletons the late precambrian tube forming cloudina the earliest known animal to produce a mineralized exoskeleton shows evidence of having been attacked by shell boring organisms of more than 500 tubes from shaanxi province china 2 7 have rounded holes 40 to 400 micrometers in diameter the relation between the size of the holes and the width of the bored tubes suggests that the attacking organism was a predator selecting its prey for size if true this would be the oldest case of predation in the fossil record and would support the hypothesis that selection pressures from predation was a significant factor in the evolution of animal skeletons around the precambrian cambrian boundary

paleokarst paleosol and rocky shore deposits at the mississippian pennsylvanian unconformity northwestern arkansas the mississippian pennsylvanian unconformity in northwestern arkansas contains pedogenically altered regolith preserved in low lying areas on paleokarst on the chesterian pitkin limestone the regolith is succeeded by transgressive rocky shore deposits of the cane hill member hale formation type morrowan pitkin cements reflect extensive meteoric phreatic diagenesis prior to karstiflcation and paleokarst features include large dissolution fragmented pitkin lithoclasts with numerous solution pipes on a low relief surface the overlying pedogenically altered regolith contains calcretized lithoclasts in clay matrix suggesting a shift from ever wet conditions to more seasonal rainfall prior to the pennsylvanian transgression that shift may represent local climatic change or short term fluctuations in mid carboniferous tropical climate the latter interpretation may support global climate models that predict warmer wetter tropics during periods of high latitude cooling basal cane hill strata consist of high energy shoreface boulder cobble conglomerate containing reworked pitkin clasts the conglomerate contains an unequivocal rockyshore community consisting of encrusting bryozoans and corals trypanites acrothoracican barnacle borings and possibly the earliest occurrence of gastrochaenolites preservation of poorly indurated paleosol beneath high energy transgressive deposits suggests very rapid transgression consistent with a glacio eustatic mechanism truncated pitkin strata were removed by karstification and subaerial erosion during the hiatus and not by erosion during transgression

mystery of naticid predation history solved evidence from a living fossil species observations of living cernina fluctuata sowerby the sole extant species of the mesozoic and cenozoic prosobranch gastropod family ampullospiridae show that this species is an algal grazer and is not a shell drilling predatory naticid gastropod all jurassic and early cretaceous gastropods previously assigned to naticidae belong to ampullo spiridae and are now inferred to be herbivores not shell drillers this finding refutes the triassic origin and favors a cretaceous origin for naticid drilling predation a preliminary revision of cenozoic and cretaceous species previously assigned to naticidae suggests that naticids were absent prior to the cretaceous campanian and diversified at a modern level in eocene time this pattern of naticid diversification from the late cretaceous onward coincides roughly with the evidence of naticid predation the fossil record of naticid drill holes once of anomalously short duration now accurately reflects the geologic history of naticid predation activity

inferring multiscale structure in atmospheric turbulence using satellite based synthetic aperture radar imagery this paper describes the multiscale structure in synthetic aperture radar sar backscatter seen in an image of a cold air outbreak as being due to the influence on the surface of the ocean of three scales of interacting atmospheric turbulence a low resolution pixels have side lengths of 100 m sar image shows the first class of backscatter pattern to be broken lines of enhanced radar backscatter of order 1 db above the background with an average cross wind scale of 5 km and downwind lengths of many tens of kilometers these are associated with quasi two dimensional roll vortices the second class of radar backscatter pattern is two dimensional backscatter regions whose linear aggregrations constitute the lines of backscatter they are on average 1 km wide in the cross wind direction and are 2 5 km long in the downwind direction a higher resolution image pixels have side lengths of 12 5 m of the same area shows a third class of structure smaller scale regions of enhanced backscatter up to several hundred meters in length downwind and greater than 100 m across wind that are associated with 7 db variations in in the unaveraged image the modulated fine scale backscatter structure compares favorably in both scale and effect to observations of the modulation of microfronts in the atmospheric surface layer by kilometer scale inactive eddies the latter being of uncertain origin therefore the hypothesis offered here is that the fine scale sar structure is caused by the influence of atmospheric microfronts on the ocean surface while the two dimensional kilometer scale backscatter features are the signature of inactive eddies linearly aggregated by or possibly intrinsic to the roll vortices

carbonate concretions from the london clay ypresian eocene of southern england and the exceptional preservation of wood boring communities marine driftwood bored by teredinid bivalves shipworms is common in the london clay formation ypresian eocene of southern england the london clay of sheppey kent has yielded six genera of teredinids and is the most diverse fossil assemblage of the family known the presence of several genera that are known exclusively from mangroves at the present day demonstrates the potential value of teredinids in the recognition of ancient mangroves the rapid sea floor burial of logs containing numerous individuals resulted in the borings becoming completely or partially sealed by the plug like pallets in this exceptional mode of preservation valves pseudofaeces and pallets are found in life position and early cementation prevented compaction of the wood and borings the bored wood acted as centres of carbonate concretion formation cement compositions mineral associations and 13 c and 18 o stable isotope data indicate that most precipitation occurred in the iron reduction zone with sulphate reduction also being an important source of carbonate for the sheppey concretions fractures and their infilling cements are demonstrably contemporaneous with the cement zones in which they terminate it is likely that rapid changes in cement chemistry are a consequence of sudden release of fluid by dewatering events whilst more gradual shifts in chemistry were controlled be evolution through the oxic fe mn and s reduction zones teredinid boring linings and the cements which infill them may have recrystallized by a dissolution reprecipitation process which has preserved the chemistry of successive cements and has probably not significantly changed 18 o values

soils and their relationship to aspect and vegetation history in the eastern southern alps canterbury high country south island new zealand abstract this study focuses on soils in a mountainous catchment area located in the eastern part of the southern alps south island new zealand the objective was to check the soils for non or poorly crystalline constituents metal organic complexes short range order minerals and if there is a relationship between pedogenesis and aspect and more recent landscape history the morphology of the soils indicates brown soils dystric cambisols dystrudepts with only few signs of podsolisation in contrast selected chemical properties of the soils reveal very strong weathering and leaching feo fed ratios are high and exceeding 0 6 in almost every soil horizon oxalate extractable aluminium and silicon show prominent peaks in the lower subsoil horizons with 1 76 2 52 alo and up to 0 68 for sio on southern aspects this is considerably higher than the values measured for soils on northern aspects 0 59 to 1 07 alo max 0 26 sio this aspect relationship is also applying to phosphate retention reaching values of more than 90 on southern aspects and not more than 70 for northern aspects additionally significant movement of organic matter in soils on southern aspects is evident by measurements of organic carbon and pyrophosphate extractable al and fe thus soil formation can be regarded as more advanced on southern aspects allophane in association with organic matter can be considered as an important constituent in southern aspect subsoils being responsible for the typical andic properties metal humus complexes and ferrihydrite are of subordinate significance considering the actual soil forming conditions under scrub grassland esp soil acidity it is unlikely that weathering and leaching is still strong enough today to allow significant podsolisation and the formation of short range order minerals under consideration of existing soil data from other studies it is proposed that these components and the podsolisation features are relicts caused by more acidic conditions under former forest cover which supported a stronger weathering and leaching

river response to an active fold and thrust belt in a convergent margin setting north island new zealand high resolution digital elevation data topsar 10 m grid are used to reconstruct late quaternary growth histories of subtle folding in the wairarapa fold and thrust belt north island new zealand outcrop data of deformed latest miocene and younger strata are combined with observations of warped and faulted late quaternary terrace surfaces to unravel the geomorphic and structural history of the huangarua river valley optically stimulated luminescence osl dating of loess that accumulated on these strath terraces and paleosol stratigraphy allow temporal correlation among the terraces and with glacial climate cycles since the last interglaciation these data indicate that five intervals of strath cutting occurred at 125 60 70 30 15 and 10 ka strath beveling is largely independent of local folding or regional base level change we hypothesize that straths are cut when an increase in sediment supply during cool climatic periods brings river sediment load and river transport capacity into balance in the wairarapa strath cutting events appear to occur near the end of cool climatic cycles this study shows that the identification of subtle departures from regional topographic trends becomes practical when a high resolution dem is available after subtraction of an average valley gradient from the digital topography the residual topography on the terrace treads reveals cross valley and longitudinal tilting although rates of folding are slow and the magnitude of deformation is commonly limited to less than a few tens of meters these topographic anomalies define fold axes that coincide with subsurface structures when combined with time control these anomalies serve to define the patterns and rates of fold growth over the past 125 kyears

clay minerals oxyhydroxide formation element leaching and humus development in volcanic soils a weathering sequence with soils developing on volcanic trachy basaltic parent materials with ages ranging from 100 115 000 years in the etna region served as the basis to analyse and calculate the accumulation and stabilisation mechanisms of soil organic matter som the transformation of pedogenic fe and al the formation and transformation of clay minerals the weathering indices and by means of mass balance calculations net losses of the main elements although the soils were influenced by ash depositions during their development and the soil on the oldest lava flow developed to a great extent under a different climate leaching of elements and mineral formation and transformation could still be measured leaching of major base cations coupled with a corresponding passive enrichment of al or fe was a main weathering mechanism and was especially pronounced in the early stages of soil formation due to mineral or glass weathering with time the weathering indexes such as the k ca ti ratio tend to an asymptotic value chemical and mineralogical changes between 15 000 and 115 000 years in the a and b horizons were small in contrast to this the accumulation of newly formed itm imogolite type materials and ferrihydrite showed a rather linear behaviour with time weathering consisted of the dissolution of primary minerals such as plagioclase pyroxenes or olivine the breakdown of volcanic glass and the formation of secondary minerals such as itm and ferrihydrite the main mineral transformations were volcanic glass imogolite kaolinite clay fraction in the most weathered horizons a very small amount of 2 1 clay minerals could be found that were probably liberated from the inner part of volcanic glass debris the rate of formation and transformation of 2 1 clay minerals in the investigated soils was very low no major changes could be observed even after 115 000 years of soil evolution this can be explained by the addition of ash and the too low precipitation rates in general soil erosion played a subordinate role except possibly for the oldest soils 115 000 years the youngest soils with an age 2000 years had the highest accumulation rate of organic c about 3 0 g c m2 year after about 15 000 years the accumulation rate of organic c in the soils tended to zero soil organic carbon reached an asymptotic value with abundances close to 20 kg m2 after about 20 000 years in general the preservation and stabilisation of som were due to poorly crystalline al and fe phases pyrophosphate extractable kaolinite and the clay content these parameters correlated well with the organic c imogolite type material did not contribute significantly to the stabilisation of soil organic matter

echinoid assemblages from the early miocene of funtanazza sardinia a tool for reconstructing depositional environments along a shelf gradient abstract lower miocene echinoid assemblages from funtanazza midwestern sardinia are studied with respect to reconstructing palaeoenvironmental conditions along a shelf gradient this is accomplished by 1 detailed logging of sedimentary facies 2 applying functional morphological reconstructions of echinoid skeletons and interpreting their behaviour and life habits 3 quantifying various taphonomic features of test preservation and 4 analysing accompanying fauna and flora the funtanazza section is dominated by fine and coarse grained siliciclastic lithologies eighteen genera of both regular and irregular sea urchins are recognized herein of these sixteen occur in seven echinoid assemblages which were distinguished with respect to abundance diversity taphonomy and lithology littoral environments are characterized by the camarodonts genocidaris and psammechinus the clypeasteroids clypeaster and echinocyamus and the echinolampadoids hypsoclypus and echinolampas the cidaroids prionocidaris and tylocidaris sardocidaris and the spatangoid spatangus are also present higher diversity is represented in inner sublittoral environments with the co occurrence of the regular echinoids prionocidaris tylocidaris sardocidaris tripneustes and genocidaris and the irregular echinoids clypeaster echinocyamus hypsoclypus echinolampas schizaster spatangus lovenia and trachypatagus outer sublittoral environments are dominated by spatangoid echinoids and the cidaroid tretocidaris stylocidaris various substrates such as boulders and pebbles mobile fine and coarse sediments secondary hardgrounds and seagrass and bryozoan patches can be inferred preservation style with respect to abrasion fragmentation and encrustation can vary widely among different taxa and environments and are interpreted as a function of constructional morphology and ambient environmental factors the echinoid assemblages of funtanazza contain taxa which in part are widespread in the miocene sedimentary successions of the circum mediterranean area the described echinoids and assemblages are compared to other similar coeval occurrences and their applicability as palaeoenvironmental indices discussed

coexistence of allophane gibbsite kaolinite and hydroxy al interlayered 2 1 clay minerals in a perudic andosol allophane and halloysite are the most common secondary aluminosilicate minerals in andosols developed in pyroclasts in humid tropical areas we studied the composition and the charge properties of the clays extracted from the weathered b horizon of a perhydrated andosol developed in andesitic ash in guadeloupe french west indies by selective dissolution x ray diffraction xrd thermal analysis and characterization of ion exchange properties the bw horizon contained weatherable minerals and exhibited an allophane content of 25 its clay fraction contained gibbsite allophane kaolinite and hydroxy al interlayered 2 1 clay minerals the occurrence of gibbsite allophane and kaolinite was linked with intense leaching of silica after oxalate dissolution of allophane the cation exchange capacity cec was 11 8 cmol c kg 1 clay i e a typical value for low activity clays subsequent citrate treatment completely dissolved gibbsite but partly extracted al interlayers from the hydroxy al interlayered phase this extraction led to a 5 6 fold increase of the cation exchange capacity 62 3 cmol c kg 1 clay and a 2 3 fold increase in k selectivity the 2 1 clay minerals involved a combination or continuum of high charge beidellite and vermiculite from our data we believe that the 2 1 clay minerals first acted as a sink for aluminium and might have expressed an anti gibbsitic effect after substantial al interlayering of 2 1 clay minerals mimicking low activity clay gibbsite might have formed in a second stage c 2003 elsevier science b v all rights reserved

halloysite neoformation during the weathering of nephelinitic rocks under humid tropical conditions at mt etinde cameroon abstract mt etinde eruptions are dated at 0 65 ma it is located on the sw oceanic border of mt cameroon and is composed essentially of nephenilitic rocks the weathering of nephelinites has resulted in the formation of a 150 cm deep andic cambisol humic consisting of three horizons ah bw c mineral weathering was studied in detail in two profiles one p 1 developed from unaltered nephelinite nephelinite u and the other p 2 formed from hydrothermally altered nephelinite nephelinite h emphasis was on the impact of hydrothermal alterations on weathering profiles to characterise the signature of halloysite in nephelinitic regoliths and to discuss the evolution of mt etinde soils on the quaternary nephelinitic parent rocks the mineralogy of nephelinite u consists predominantly of clinopyroxene nepheline leucite hauyne titanomagnetite perovskite apatite and sphene nephelinite h differs from nephelinite u by phillipsite calcite occurrence the main weathering products are halloysites 1 nm and 0 7 nm and minor occurrence of gibbsite and hematite sem micromorphological examination coupled with microprobe analyses showed halloysites resulting from in situ alterations of feldspathoids phillipsites and clinopyroxenes 1 nm hydrated halloysite neoformation characterises the alteromorphs of the saprolite while 1 nm and 0 7 nm halloysite coexist in the bw and the ah horizons of both soils during weathering these halloysites had a chemical dependence with parent mineral as follows ce rich halloysite characterises alteromorph after phillipsite fe rich halloysite alteromorph after clinopyroxene ca rich halloysite alteromorph after hauyne and k rich halloysite alteromorph after leucite ce rich halloysite is a tracer of the hydrothermal impact in soils profile the si al ratio is also characteristic of the parent mineral therefore the availability of si is the only factor that controlled the formation of 1 nm halloysite at the base of the saprolite while the presence of 1 nm and 0 7 halloysite in the upper part of the saprolite the bw horizon and the ah horizon suggesting only time controls of the evolution of the profiles by both kinetic wet dry seasons and thermodynamic si bearing factors gibbsite occurs only in the nephelinite h soil its presence is due to the hydrothermal alteration which favoured the development of an intense microporosity allowing the elimination of silica the study highlighted the influence of past hydrothermal activity on the recent weathering process in the humid tropical area

bioeroding foraminifera a review abstract twenty species of foraminifera mainly from turbulent warm shallow water environments are known to make cavities in hard substrates they range from jurassic callovian to recent in age several hypotheses feeding protection and test building have been proposed to explain this mode of life and the processes involved in boring this review indicates further studies on the biology and physiology of these foraminifera should evaluate their role in bioerosion of hard substrates and the subsequent production of grain sized sediment that may affect the biotopes of sediment dwellers

andisols of turkey an example from the cappadocian volcanic province abstract a number of studies have been conducted on the genesis of soils from volcanic deposits in semi humid and humid climates however there has been little study of the mineralogical properties and genesis of soils from volcanic rocks in arid and semi arid climates this study was conducted to understand the genesis of soils from different volcanic parent materials such as andesite dacite volcanic ash basalt and ignimbrite in the region east of the erciyes stratovolcano in central anatolia at least three soil profiles were selected from each parent material and 17 soil profiles were described soil samples were also taken from each soil horizon for physical chemical and mineralogical analyses soil profiles vary according to elevation and the types of derived parent materials and are divided into 17 pedons and 15 horizons 2a 2bw 2bw1 2c a2 bc bw bw1 bw2 bw3 c c1 c2 cr r soil acidity varied from slightly alkaline to slightly acidic in all soils organic matter contents were higher in the surface horizons and generally decreased with depth in all pedons the extractable cation values of ammonium oxalate pyrophosphate dithionite citrate and sodium pyrophosphate as well as unhydrolyzed volcanic glass allophone imogolite smectite and ferrihydrite contents of the soils are variable based on the parent materials pedons and elevations that are typical of the cappadocian volcanogenic soils in anatolia of turkey these soils can generally be described as alu andic andisols due to their alo 1 2feo values and alp alo ratios the important factors affecting the formation and development of soils are climatic variations affecting horizon development and genesis soil parent material diversities and leaching regimes originating from elevation differences

middle ordovician chazy group cavity dwelling boring sponges microcavities in lower middle ordovician bryozoan mounds from the laval formation chazy group near montreal quebec contain evidence that endolithic boring sponges were present ramose borings with scalloped walls and swellings resembling endolithic sponge galleries faceted carbonate grains similar to modern sponge chips and siliceous spicules both in situ on the cavity wall or roof and in the sediment all point to the activities of endolithic sponges in the hard substrate of the wall and roof coelobiontic cavity dwelling endolithic sponges therefore infested cavities in skeletal mounds and reefs in the middle ordovician and appear to have exploited the cavity habitat very soon after the appearance of metazoan skeletal reefs in the ordovician

occurrence and origin of soils with andic properties in calabria southern italy abstract andic like soils along with andosols have previously been reported in non volcanic ecosystems of the coastal and mountainous areas of the calabria region southern italy but little is known about their properties soil formation processes and volcanic source areas chemical mineralogical microscopic sub microscopic and magnetic analyses were carried out on 8 soils which were selected from the major calabrian geological sectors in order to assess relationships between parent material and bedrock soil chemical properties revealed an occurrence of andic or vitric properties in the studied soils as a whole and the optical microscopy enabled to identify volcanic glass micro pumices and soil isotropic matrix clearly indicating volcanic inputs three groups of soils identified on the basis of the degree of andic properties showed rather homogeneous also in terms of chemical properties clay mineralogy and land use as well as with regard to micromorphology and magnetic susceptibility part of the intra group similarities was a consequence of similar distances between sites and volcanic source area as suggested by the correlations found between ferrihydrite content andic i e of ammonium oxalate extractable al 0 5 fe and phosphate retention and magnetic properties vs distances from several sicilian districts the elemental composition obtained by sem eds analyses of soil glass fragments supported these findings and related the origin of most of the studied soils to the high potassium calc alkaline magmatism of the southernmost eolian islands mainly lipari and vulcano except for soils from the marine terraces of northern calabria pra and the aspromonte massif del which were both linked albeit uncertainly to campanian volcanism soil magnetic properties were significantly 0 79 correlated to the andic properties so confirming the high performance of magnetic susceptibility as low cost proxy for the identification of volcanic constituents

halloysite smectite mixed layered clay in fluvio volcanic soils at the southern foot of mount kilimanjaro tanzania abstract the formation of kaolinite smectite mixed layered clays results from weathering of smectite in leached and silica depleted environments halloysite smectite mixed layered clays have been proposed to form from weatherable minerals in volcanic ash soils through simultaneous formation of 1 1 and 2 1 units in silica rich environments here we report a mineralogical study of weathered b horizon material from soils developed on late quaternary fluvio volcanic deposits of basaltic origin at the southern foot of mount kilimanjaro in northern tanzania this area is characterized by a strong seasonality two months of highly humid conditions followed by a 10 month pronounced dry season during which mineral authigenesis takes place the weak leaching conditions are reflected in the high base saturation of the soils and by their high content of amorphous silica the soils contain no allophane the clay fractions contain dioctahedral 1 1 layer silicates trioctahedral mica gibbsite and feldspar as well as a substantial amount of 1 1 2 1 mixed layered clays with predominance of 1 1 layers the latter consist of dehydrated halloysite that only partially expands after formamide intercalation because of its history of drying in field conditions the interstratified phases are high charge halloysite smectite mixed layered clays cec 30 72 cmol kg 1 clay that are predominantly very fine grained

from andic non allophanic to non andic allophanic inceptisols on alkaline basalt in mediterranean climate a toposequence study in the marghine district sardinia italy abstract the properties of a non andic allophanic inceptisol pom1 and two andic non allophanic inceptisols flm5 and spm8 representative of a toposequence on basanite rocks of mt st antonio central western sardinia marghine sub region were analyzed to better elucidate factors and processes that lead to a different expression of andic properties and allophane formation in xeric mediterranean environment a series of laboratory techniques including physical chemical micromorphological x ray diffraction xrd scanning electron microscopy sem analyses were used all soils are usually rich in organic carbon dystric at the great group level with saturation base from 72 to 10 and with ph from subalcaline to acidic allophanic inceptisol appears more intensely weathered than non allophanic inceptisols volcanic glass content is in any case negligible pom1 formed on the plateau shows a shallow solum 45 cm with a 2 horizon that meets all the criteria for andic soil properties the amounts acid oxalate extractable al o and si o together with pyrophosphate extractable al p typifies such a pedon as allophanic inceptisol 0 19 p al o 2 the allophanic inceptisol pom1 is located at the plateau of the toposequence where lower surface runoff greater water infiltration rate the absence of significant erosion and colluvial movement may have increased the degree of weathering processes in these conditions the prolonged soil moistness prevents the transformation of short order components on the whole the results emphasize the role of topography and the importance of al fe amorphous compounds in expressing soil andic properties and allophane content versus the volcanic origin of parent material and the insufficiency of volcanic glass the results also suggest that the occurrence of soil with andic properties and significant allophane content in hot and dry environments like the mediterranean climate in sardinia may be more widespread than expected

mid latitude trans pacific reconstructions and comparisons of coupled glacial interglacial climate cycles based on soil stratigraphy of cover beds abstract south westland new zealand and southern chile are two narrow continental corridors effectively confined between the pacific ocean in the west and high mountain ranges in the east which impart significant influence over regional climate vegetation and soils in both these southern mid latitude regions evidence for extensive and repeated glaciations during cold phases of the quaternary is manifested by arrays of successively older glacial drift deposits with corresponding outwash plain remnants in south westland these variably aged glacial landforms are mantled by layered multisequal soils characterised by slow loess accretion and pedogenesis in an extreme leaching and weathering environment these cover bed successions have undergone repeated coupled phases of topdown and upbuilding soil formation that have been related to fluctuating cycles of interglacial warm and glacial cold climate during the quaternary in this study we recognise multisequal soils overlying glacial landforms in southern continental chile but unlike the spodic podzolic soil sequences of south westland these are of dominantly volcanigenic andic provenance and are very similar to multisequal soils of andic provenance that predominate in and adjacent to areas of rhyolitic to andesitic volcanism in north island new zealand here we develop a soil stratigraphic model to explain the observed occurrence of multisequal soils mantling dominantly glacial landforms of southern continental chile based on proxy data from southern chile we propose that persistent vegetation cover and high precipitation on the western side of the andes during colder than present episodes tended to suppress the widespread production of glacially derived loessial materials despite the pervasive occurrence of glacial and glacio fluvial deposits that have frequently inundated large tracts of this landscape during the quaternary given the lack of loess cover beds that have traditionally assisted in the relative dating of glacial episodes prior to the late quaternary surface exposure dating techniques could provide another chronological alternative to address this issue however there have been two main obstacles to successfully apply this dating technique in patagonia first minimum exposure ages may be obtained on moraines older than the last glacial cycle due to erosion although dating outwash plains is more robust second on the wet western side adjacent to the andes persistent vegetation cover during both glacial and post glacial times as well as widespread inundation by volcanic mass flows appear preventive we make a case that soil genesis within this region appears to be dominated by a constant flux of intermittently erupted andean sourced tephra which has continued to upbuild soils at the ground surface separated by intervals where topdown weathering processes are intensified as already demonstrated by new zealand studies multisequal soil successions have a clear implied connection to coupled glacial and interglacial climate cycles of the quaternary on this basis similar sequences in northwest patagonia provide a relatively untapped archive to enable quaternary glacial and environmental changes in this pervasively glaciated volcanic region to be constructed

weathering of upper quaternary tephras in new zealand 2 clay minerals and their climatic interpretation abstract forty two tephra beds that have successfully mantled the landscape during 250 000 yr at ahuroa road te kuiti new zealand have each in turn been weathered to allophane and halloysite al rich allophane proto imogolite allophane dominates in all beds except four which have greater amounts of halloysite allophane and halloysite appear to have been stable for the past 250 000 yr and the nature of the parent tephra has not influenced the type of clay formed the analytical data show that the sequence can be sub divided into two sections at bed ah 33 three quarters of the way up the sequence beds in the upper section are younger than 70 000 yr b p and have lower allophane lower total clay higher rates of accumulation and show poor colour contrast the lower section beds have high allophane high total clay lower rates of accumulation and strong colour contrast the allophane rich beds are considered to have weathered under conditions of warm temperature and moderate to high rainfall high si leaching situations during interglacial periods three of the four halloysite rich beds are considered to have weathered under low rainfall conditions low si leaching situations occurring during colder or glacial periods the last halloysite rich bed is found at the base of the sequence here halloysite is considered to have formed as a result of si enrichment when percolating waters perched in the coarse basal bed

basalt weathering in an arctic mars analog site abstract the martian surface has undergone chemical and physical weathering in the past and these processes may continue intermittently today to explore whether martian rocks are likely to retain features indicative of weathering we investigated how basaltic material weathers on earth specifically we investigated weathering of a quaternary aged basaltic flow at the sverrefjell volcano in svalbard above the arctic circle this flow weathered since deglaciation under cold dry

miocene clypeaster from valencia e spain insights into the taphonomy and ichnology of bioeroded echinoids using x ray micro tomography abstract taphonomic analysis and x ray micro tomography ct were applied to clypeaster specimens from the miocene of fuente del jarro valencia spain this enabled the identification of various preservational features including encrustation bioerosion abrasion and post depositional cracking approximately 15 of the studied specimens were affected by encrusters and or borers of particular interest was a single intensely bored specimen preserving numerous cross cutting bioerosion structures these structures exhibit a distinctive morphology consisting of clavate or flask shaped chambers with a circular to oval cross section a narrow neck region near the figure of eight shaped aperture and a chimney extending outside the clypeaster test the excellent preservation and characteristic morphology as revealed by the ct scan coupled with the observation that in some cases articulated bivalve shells are still present within the chambers allows for the identification of the tracemaker as the boring bivalve rocellaria reaffirming these tube dwelling animals as borers burrowers and crypt builders the trace fossils described herein are semi endoskeletal dwellings representing a combination of bioerosion through the plates of the echinoids bioturbation in the form of burrowing into the sediment infill of the clypeaster specimen and carbonate secretion resulting in a crypt the morphologies of the different dwellings are influenced by the limited available space within the echinoid tests this study confirms the importance of the relatively stable and thick clypeaster shells as benthic islands in cenozoic sandy littoral settings the high degree of multiple colonizations as well as the uniform orientation of the burrows suggests a long term stable position of this secondary substrate at or near the sediment surface

atmospheric boundary layer rolls observed by the synthetic aperture radar aboard the ers 1 satellite two synthetic aperture radar sar images acquired by the european remote sensing satellite ers 1 over the jade weser estuary in the german bight of the north sea on january 2 and 20 1992 are analyzed the images show sea surface manifestations of atmospheric boundary layer rolls this is inferred from the orientation of the quasi periodic sea surface patterns which are aligned approximately with the wind direction from the ratio of the wavelength of the patterns to the height of the boundary layer and from the conditions encountered in the atmospheric boundary layer as measured quasi simultaneously by radiosondes the atmospheric boundary layer rolls were generated by a dynamic instability on january 2 and by a thermal instability on january 20 for the first time quantitative estimates of variations of the wind velocity at the sea surface associated with the atmospheric rolls are extracted from a spaceborne radar sar image it is shown that wind velocities derived from sar image intensity variations are in agreement with theoretical estimates

formation of clay minerals in soils developed from basic volcanic rocks under semiarid climatic conditions in lanzarote spain abstract clay formation in soils was studied in four landscapes of different ages in lanzarote canary islands landscape iv b is about 250 years old iv a subrecent iii early young pleistocene and landscape i late tertiary the soils have developed from basic to ultrabasic pyroclastic fall deposits or basalt clay formation in soils of landscape iv b is in an initial stage having a clay content of 1 2 kg m 2 whereas in landscape iv a 30 40 kg m 2 and in landscape iii 100 200 kg clay m 2 are accumulated in polygenetic soils of landscape i more than 3000 kg clay m 2 can be found in the youngest soils iv b smectite is the most prominent clay mineral whereas iv a soils are dominated by amorphous clay the clay fraction in older soils contains illite smectite as well as kaolinite in smaller quantities the chemical composition of the clay fraction of soils with different ages changes significantly according to the mineral composition

selective sorption of potassium in a weathering sequence of volcanic ash soils from guadeloupe french west indies volcanic ash soils are usually associated within the weathering sequence glass allophane 4 halloysite on the eastern slopes of the volcano la soufriere guadeloupe this sequence occurs in a toposequence molli silicic andosol humic andosol haplic andosol haplic nitisol where the average annual rainfall decreases from 4000 mm at 420 m a s l to 2500 mrn at 30 m a s l of this sequence we selected four profiles and examined the relationships between weathering stage clay mineralogy and exchangeable k ca2 selectivity with increasing weathering the total content of alkaline and alkaline earth cations of the b horizon steadily decreased from 185 cmol c kg 1 soil in the molli silicic andosol to 24 cmol c kg 1 soil in the nitisol k selectivity was small in the molli silicie andosol but significantly increased with increasing weathering stage and increasing content of halloysite in the haplic andosol and nitisol the very strong selectivity for k ions may be linked with the presence of a 2 1 clay mineral but could not be attributed unequivocally to this mineral or to halloysite the 2 1 mineral occurred as a discrete phase mixed with halloysite and exhibited x ray diffraction features suggesting its vermiculitic nature c 2003 elsevier b v all rights reserved

soil genesis on trachytic and leucititic lavas of cimini volcanic complex latium italy abstract three distinct soils which are developing on volcanic effusive rocks of mt fogliano san martino and mt cimino and form part of the cimini volcanic complex north of rome were analysed and their physico chemical mineralogical and micromorphological characteristics are reported these soils are believed to have developed in a fairly recent time beginning around 20 000 years ago under similar climatic and vegetational conditions the mt fogliano soil a typic hapludand developed in a leucite tephritic lava showed evident andic properties and a high content of amorphous short order phases such as al rich imogolite like allophanes the formation of crystalline clays is very limited the main clay mineral being halloysite 0 7 nm the leucite appeared to be almost completely weathered in the soil the san martino soil an andic dystrochrept developed from trachytic lavas was affected by the addition of tephritic pyroclasts and showed less pronounced andic properties in fact the surface horizons exhibited a high content of allophanic materials the alo alp sio molar ratio being around 2 but they did not meet the andic requirements due to their limited thickness the main clay minerals were found to be kaolinite and illite the lower horizon contained halloysite 0 7 nm illite and a low content of allophanic constituents the mt cimino soil a vitrandic hapludalf derived from latitic lavas was characterized by a marked genesis and translocation of clay showed very faint andic properties and was found to be very poor in extractable al this pedoenvironment favours the formation of crystalline clays the main clay minerals being kaolinite illite and vermiculite at a different degree of intercalation with al hydroxy polymers the nature of the rock seems to have played a significant role in determining the different pedogenetical trends of these soils the feebly resistant leucite in the mt fogliano soil has contributed to the formation of al rich allophane like constituents and al humus complexes the holocrystalline trachytic substratum of the san martino soil rich in feldspars has promoted the production of halloysite over the formation of allophane in the deeper horizon while the latitic rock of the mt cimino soil by the weathering of feldspars and biotite present in a higher amount has induced the formation of crystalline clay minerals and favoured the formation of a non allophanic soil in a pedoenvironment where andisols are usually found

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

mineralogy and geochemistry of some so called paleosols from mt vulture volcano southern italy abstract three tephra beds with suspected paleoweathering effects from the mt vulture volcano zone potenza italy were studied grain size chemical and mineralogical analyses and sem observations were performed to estimate the stage of weathering this study reveals the difficulties in the study of early stages of weathering of pyroclastic rocks the results point out the existence of four successive stages or processes a pre depositional stage pre or eruptive features of pyroxenes quartz and phlogopite b depositional stage persistence of grain size distribution similar to unaltered materials low clay fraction content c circulating water stage in the lower bed more altered pyroxenes with depth smectite calcite mn hydroxides association increase in consistence with depth and d weathering stage decrease of allophane and amorphous silico alumina with depth release of alkali ions the existence of these overlapping processes produces variations of grain size mineralogy and chemistry through each bed paleosol that hinders the obtainment of geochemical balances or calculations

late quaternary tephra derived paleosols in central italy s carbonate apennine range stratigraphical and paleoclimatological implications abstract detailed stratigraphical pedological and geochronological 14c dating research was carried out on numerous sections located in the carbonate apennine range of central italy two paleosols late pleistocene pedomarker a and holocene pedomarker b in age were recognized as having developed from air fall pyroclastic material given their special properties and widespread distribution both soils represent valuable markers in the late quaternary stratigraphy of central italy information about the climatic conditions that have influenced their pedogenesis through time has been obtained pedomarker a formed under temperate wet conditions related to the last interstadial fluctuations of the pleniglacial its development ceased after ca 30 ka because of the onset of last glacial maximum dry cold conditions pedomarker b formed at the beginning of the holocene under udic and perudic soil moisture regimes its development ceased in some localities because of a change towards a drier climate after ca 4 5 ka petrographic and geochemical characteristics of the parent materials are discussed and correlations with the campanian ignimbrite pedomarker a and neapolitan yellow tuff pedomarker b both related to activity in the phlegrean fields are proposed

characterization functioning and classification of two volcanic soil profiles under different land uses in central mexico volcanic soils constitute an important resource for agriculture and forestry in central mexico as well as in various world regions they exhibit unique properties and high productive potential related to the amorphous materials they contain the relationship between amorphous materials soil characteristic and functioning has not been well studied the objectives of the present work were to assess the influence of land use agricultural and forest topography and other soil forming factors on physical chemical and mineralogical characteristics and pedological processes responsible for soil genesis and soil classification of two volcanic soil profiles derived from andesitic parent material located 150 m away from each other within the same toposequences the toposequence is located in the trans mexican volcanic belt tmvb a highly populated region of central mexico that provides part of the water for mexico city megapolis a series of field and laboratory techniques including physical chemical micromorphological x ray diffraction xrd transmission electron microscopy tem infra red analysis mossbauer spectroscopy were used the main factor affecting the present morphology of the soil profiles was the topography the mineralogical features of the upper layers of the maize profile pachic andosol indicate redistribution of soil material from the upper part of the toposequence the land use change favored this redistribution deeper horizons of this profile were developed from volcanic ashes deposited in situ hematite and ferrihydrite considered markers of evolution in redistributed soil material were observed in this profile associated with allophane the presence of hematite has been reported for the first time in mexican andosols the present characteristics of the forest profile dystric cambisol are mainly due to the pedological process of the volcanic ash layers remaining in situ after the redistribution and volcanic breccia it was concluded that the forest profile evolved from an andosol to an inceptisol which was evidenced by desaturation loss of silica and organic carbon in this profile the fe minerals were associated with the presence of gibbsite and halloysite the position in the toposequence and the physical and chemical characteristics of these profiles define their present functioning such as losses by erosion and c dynamics

pedogenesis and surface charge of some andic soils in washington u s a abstract chemical and surface charge characteristics were determined for three soils that were formed in a mantle of volcanic tephra along a bio climatic gradient in forest in northcentral washington state the soils are nevine silt loam typic vitrandept manley silt loam entic cryandept and moses silt loam andic cryochrept selective dissolution analyses for al fe and si suggests that the weathering products in the ash mantle are poorly crystalline aluminosilicates hydrous and crystalline fe oxides and al humus complexes in decreasing order of abundance the chemical and physical data indicate that moses silt loam has undergone a greater degree of weathering than either nevine silt loam or manley silt loam and we attribute this to differences in the weathering environment the measured points of zero charge parameters are typical for soils that are dominated by amphoteric surfaces the soils exhibit charge reversal and charge magnitude is dependent upon ph and electrolyte concentration the point of zero salt effect ranged from 5 1 to 5 3 and the point of zero net charge ranged from 4 3 in nevine silt loam to 5 4 in moses silt loam pedogenesis has not caused large enough differentiation among the soils to allow us to use zero charge parameters as indicators of the degree of pedogenesis

late jurassic coral microbial reefs from the northern paris basin facies palaeoecology and palaeobiogeography abstract during the late middle oxfordian patch reefs grew on the northern margin of the paris basin according to the facies analysis of the reef and inter reef sediments the environment was a warm clear and agitated sea with highly episodic sedimentation the bioherms were a short lived phenomenon during the third phase of regional reefal development sequence stratigraphically they are associated with a highstand system tract volumetrically and trophically dominant organisms were microbes now represented by massive clotted leiolite stalactitic hemispheroids with purely thrombolitic texture are restricted to open caves corals were of structural reef building importance due to their rapid upward growth the patch reefs are characterised by thickets of ramose corals which developed a very open framework in the vicinity of these patch reefs though in hydrodynamically higher energy environments grew thickets of more stoutly branched corals however they are rarely preserved in situ and are generally represented as abundant coral rubble the reef taxa are characterised by the notable absence of several groups e g oysters serpulids bryozoans pectinids occurring at other localities where reefs of similar age developed in similar environmental conditions the reefs also have strikingly modern aspects to them in particular the presence of cryptic elements within caves and a sponge dominated borer association dwellers belong to various life form types although encrusting taxa are exceedingly rare this may be explained by the presence of soft microbial films on most surfaces the palaeoecological analysis suggests that the major controls on faunal composition and high diversity were elevated nutrient levels highly episodic sedimentation and probably seasonal environmental disturbances structural and functional aspects of the reef community grazers trigger framebuilders borers trigger binders binders hamper borers allow ecological comparisons to be made with contemporaneous as well as recent reefs the unique combination of ecological factors resulted in a specialised previously undescribed community which differs from both tethyan and northern localities in various aspects these include cavities with cryptofauna prominence of grazing gastropods and high faunal diversity in a microbially dominated build up

investigation of an aggrading paleosol developed into andesitic ring plain deposits ruapehu volcano new zealand within a sequence of andesitic volcaniclastic deposits on the northeastern ring plain of ruapehu volcano is a ca 10 m thick sequence of weathered andesitic tephras weathering and paleosol development is most evident in 3 6 m of fine ash in this sequence the ages of these tephras are constrained between ca 23 70 ka by dated rhyolite tephras erupted from central north island volcanoes mineralogy of the fine ash deposits reveals their origin and the processes involved in their soil development the fine ash deposits are almost totally locally derived either as primary volcanic ash or fines reworked from the ring plain itself by aeolian processes aerosolic quartz input associated with regional loess deposition during the cool climatic episodes of mid 18o stage 3 and 18o stage 4 is very low having been diluted by rapid accumulation of andesitic tephras in these episodes the observed weathering features and secondary minerals within the ash sequence were derived from a complex combination of factors including climate change accretion rate and post depositional modification relatively strong weathering development in two parts of the ash sequence is correlated with two widespread soil development episodes during the last glacial observed throughout the southern north island the accretion rate of the soil surface at these times also affected the expression of climate related weathering formation of allophane with an a1 si ratio of 2 1 and ferrihydrite occurred near the soil surface as the ash was accreting the amount of allophane and ferrihydrite through the sequence appears to be inversely related to the accretion rate of the soil surface upon burial of the ash materials by a thick 20 m sequence of lahar and tephra deposits halloysite was later formed in the buried ash the leaching of silica from the thick overburden of volcaniclastics into the ash material as well as perched water is thought to have decreased the a1 si ratio in the soil solution and thus promoted the formation of halloysite from weathering andesitic glass

re deposited rhodoliths in the middle miocene hemipelagic deposits of vitulano southern apennines italy coralline assemblage characterization and related trace fossils article i nfo an integrated analysis of rhodolith assemblages and associated trace fossils borings found in hemipelagic middle miocene orbulina marls vitulano area taburno camposauro area southern apennines italy has revealed that both the biodiversity of the constituent components and taphonomic signatures represent important aspects which allow a detailed palaeoecological and palaeoenvironmental interpretation on the basis of shape inner arrangement growth forms and taxonomic coralline algal composition two rhodolith growth stages were distinguished 1 nucleation and growth of the rhodoliths and 2 a final growth stage before burial nucleation is characterized by melobesioids and subordinately mastophoroids with rare sporolithaceans and lithophylloids the rhodolith growth main increase in size is represented by abundant melobesioids and rare to common mastophoroids very rare sporolithaceans are also present the final growth stage is dominated by melobesioids with rare mastophoroids and very rare sporolithaceans each rhodolith growth stage is characterized by a distinct suite of inner arrangement and growth form successions well diversified ichnocoenoeses gastrochaenolites trypanites meandropolydora and or caulostrepsis ento bia uniglobites micro borings related to bivalves sponges polychaetes barnacles algae fungi and bacteria are distinguished in the inner intermediate rhodolith growth stage while mainly algal fungal and bacterial micro borings are present in the outer final growth stage rhodolith growth stages and associated ichnocoenoeses indicate significant change in the depositional setting during the rhodolith growth in the vitulano area the middle miocene rhodolith assemblages formed in a shallow water open shelf carbonate platform were susceptible to exportation from their production area and then to sedimentation down to deeper water hemipelagic settings where the rhodoliths shortly kept growth and were finally buried such re deposition of unlithified or only weakly lithified i e rhodoliths and intraclasts shallow water carbonates into deeper water settings was likely favoured by storm generated offshore return currents rather than sediment gravity flows

clay minerals and humus complexes in five kenyan soils derived from volcanic ash abstract clay minerals and humus complexes and their effects on soil chemical properties were studied for five profiles around the longonot and susua volcanoes in kenya morphologically all profiles have some resemblance to andepts but there were clear cut differences in clay contents and mineral composition as well as ph between profiles 1 through 4 and profile 5 which occur under semi arid to subhumid and under humid climatic conditions respectively profiles 1 through 4 contained embryonic halloysites with x rays amorphous iron oxide and silica whereas profile 5 contained a kaolin mineral chloritized 2 1 layer silicates gibbsite and hematite these mineral associations probably represent early and advanced stages of weathering of volcanic ash under weak and strong leaching conditions respectively embryonic halloysites consisted of more or less poorly ordered halloysite and 1 0 and 0 7 1 0 nm minerals the carbon contents of a horizons ranged from 100 to 112 g kg in profiles 2 3 and 5 humus complexes increased in the order fehumus al humus ca humus in profiles 2 and 3 whereas al and fe humus were found exclusively in profile 5 the ph naf phosphate retention and acid oxalate extractable al qualify only profile 5 as an andept or andisol

echinoid assemblages as a tool for palaeoenvironmental reconstruction an example from the early miocene of egypt abstract a rich lower miocene echinoid fauna has been investigated from gebel gharra nw of suez egypt the ca 140 m long section consists of a siliciclastic lower part and a carbonate dominated upper part this corresponds to a general transgression regression cycle in all 27 different echinoid taxa were recognised the level of taxonomic identification varies depending on test completeness and preservation of specific morphological characters the palaeoecology of the echinoids was inferred using a functional morphological approach and actualistic comparisons a wide variety of ecological habitats are represented with the presence of regular as well as irregular sea urchins epibenthic as well as endobenthic forms as well as a wide range of interpreted burrowing depths for different irregular echinoids seven different echinoid assemblages were distinguished which differ with respect to the species diversity skeletal taphonomy and sedimentary environment 1 the parascutella assemblage displays spectacular mass accumulations of sand dollars accumulated by proximal storm deposits and winnowing 2 the cidaroid echinacea assemblage represents a slightly deeper moderate energy environment with a highly structured habitat and corresponding variety of regular and irregular sea urchins 3 a spatangoid assemblage with a diverse fauna of burrowing echinoids 4 the transported assemblage represents an allochthonous collection of echinoids from shallow water coarse sandy substrates 5 the mixed assemblage representing a slightly shallower low to moderate energy environment with reduced sedimentation rates 6 a clypeaster martini assemblage characterising a shallow higher energy environment 7 finally the poorly diverse phyllacanthus assemblage from shallow water carbonates diversity variations within the assemblages are correlated primarily to substrate variation burrowing depths as well as taphonomic factors the transgression regression cycle is well reflected by the echinoid assemblages which show a general deepening of depositional environment followed by shallowing upward tendencies

components facies and ramps redefining upper oligocene shallow water carbonates using coralline red algae and larger foraminifera venetian area northeast italy abstract chattian mixed carbonate siliciclastic deposits from two palaeogeographic units of southern alps the lessini shelf and venetian foreland basin of northeast italy are studied with respect to facies distributions and controlling ecological factors on dominant biogenic components these ramp depositional systems are located in the western southern alps on the lessini shelf and in the eastern southern alps in the venetian foreland basin the successions show an extensive geographic distribution of at least 150 km 40 km at the southern margin of the southern alps palaeoenvironments are inferred following microfacies characteristics and floral and faunal indicators especially those of coralline red algae and larger foraminifera an inner to middle homoclinal ramp morphology is reconstructed based on facies distributions and taxonomic and coralline algal growth form proxy data the distribution along depositional strike shows variation from thinner carbonate dominated sequence in the west monti berici and monti lessini to a more variable mixed carbonate siliciclastic dominated environment to the east vittorio veneto alpago facies character and occurrence are controlled by local hydrodynamic conditions and varying water turbidity of the studied ramp depositional system the general facies succession shows a transgressive sequence from the proximal inner to proximal middle ramp a shoal belt of trough cross bedded sandstones occurs in a proximal inner ramp position in all of the studied areas in a gentle dipping homoclinal ramp most benthic organisms inhabited the relatively quite environments off these shoals in a distal inner ramp setting basinward environments proximal middle ramp constitute areas of maximal carbonate production and consist primarily of larger foraminiferal facies and rhodolith pavements larger foraminifera represented by two larger foraminiferal assemblages are most diversified in the shallower settings near the fair weather wave base distal inner proximal middle ramp whereas coralline algae predominate in deeper areas proximal middle ramp constructing extensive rhodolith pavements rhodolith pavements are distinguished with respect to rhodolith shape size growth forms and coralline algal taxonomic composition larger foraminifera are interpreted with respect to shell structures shell architectures and comparable recent counterparts the analysed benthic communities thrived in a mesotrophic regime within trophic gradients constrained by fluvial influence coralline algal dominance and a moderately diverse larger foraminiferal assemblage suggest a tropical warm temperate transition the considerable stability imposed on sediments by the rhodolith pavement must also have significantly contributed to the maintenance of a middle ramp profile bulge this study will contribute to a better understanding of oligocene carbonates which have received less attention than their eocene or miocene counterparts

mineralogy of a soil chronosequence on andesitic lava in humid tropical costa rica abstract we studied a chronosequence of three soils developed on andesitic lavas in humid tropical costa rica in order to investigate mineralogical development and to evaluate the importance of time versus other soil forming factors morphological chemical and mineralogical methods were used to unravel evolution of the soils primary minerals in the

long term controls on soil organic carbon with depth and time a case study from the cowlitz river chronosequence wa usa abstract over timescales of soil development millennia the capacity of soils to stabilize soil organic carbon soc is linked to soil development through changes in soil mineralogy and other soil properties in this study an extensive dataset of soil profile chemistry and mineralogy is compiled from the cowlitz river chronosequence crc wa usa the crc soils range in age from 0 25 to 1200 kyr spanning a developmental gradient encompassing clear changes in soil mineralogy chemistry and surface area comparison of these and other metrics of soil development with soc properties reveal several relationships that may be diagnostic of the long term coupling of soil development and c cycling specifically soc content was significantly correlated with sodium pyrophosphate extractable metals emphasizing the relevance of organo metal complexes in volcanic soils the depth distributions of organo metals and other secondary weathering products including the kaolin and short range order sro minerals support the so called binary composition of volcanic soils the formation of organo metal complexes limits the accumulation of secondary minerals in shallow soils whereas in deep soils with lower soc content secondary minerals accumulate in the crc soils secondary minerals formed in deep soils below 50 cm including smectite allophane fe oxides and dominated by the kaolin mineral halloysite the abundance of halloysite was significantly correlated with bulk soil surface area and 14 c content a proxy for the mean age of soc implying enhanced stability of c in deep soils allophane an sro mineral commonly associated with soc storage was not correlated with soc content or 14 c values in crc soils we propose conceptual framework to describe these observations based on a general understanding of pedogenesis in volcanic soils where soc cycling is coupled with soil development through the formation of and fate of organo metal or other mobile weathering products this framework highlights interactions between soc and soil development which may be applicable to other soils where organic inputs interact with the products of chemical weathering

palaeoecology and evolution of marine hard substrate communities abstract marine organisms have occupied hard substrates since the archaean shells rocks wood and sedimentary hardgrounds offer relatively stable habitats compared to unconsolidated sediments but the plants and animals which inhabit them must develop means to gain and defend this premium attachment space hard substrate communities are formed by organisms with a variety of strategies for adhering to and or excavating the substrates they inhabit while mobile grazers organically attached and even soft bodied organisms may leave evidence of their former presence in ancient hard substrate communities a superior fossil record is left by sessile encrusters with mineralised skeletons and by borers which leave trace fossils furthermore encrusters and borers are preserved in situ retaining their spatial relationships to one another and to the substrate spatial competition ecological succession oriented growth and differential utilisation of exposed vs hidden substrate surfaces can all be observed or inferred hard substrate communities are thus excellent systems with which to study community evolution over hundreds of millions of years here we review the research on modern and ancient hard substrate communities and point to some changes that have affected them over geological time scales such changes include a general increase in bioerosion of hard substrates particularly carbonate surfaces through the phanerozoic this is at least in part analogous to the infaunalisation trends seen in soft substrate communities encrusting forms show an increase in skeletalisation from the palaeozoic into the mesozoic and cenozoic which may be a response to increasing levels of predation hard substrate communities considering borers and encrusters together show a rough increase in tiering through the phanerozoic which again parallels trends seen in soft substrate communities this extensive review of the literature on living and fossil hard substrate organisms shows that many opportunities remain for large scale studies of trends through time at the community and clade levels palaeontologists will especially benefit by closer integration of their work with that of neontologists particularly in aspects of ecology such as larval recruitment competition and succession

mineralogy and weathering processes in recent and holocene tephra deposits of the pacific northwest usa abstract weathering and evolution of minerals in tephra deposits in the cascade range of washington state usa are influenced by climate vegetation time microtopography and in the vicinity of mt st helens naturally acidic precipitation we have observed the interaction of these factors in spodosols developed on holocene tephra in the central cascades and in entisols formed on the 1980 pyroclastic flow of mt st helens weathering regimens in these tephritic soils can be qualitatively characterized by the soil solution composition weathering reactions in the spodosol are driven by organic acids in the upper soil horizons and by carbonic acid in the lower b and c horizons the mineral assemblage in the spodosol reflects in part the chemical regimen dictated by each proton donor the presence of smectite in the highly acidic e horizon ph

boring predation and mesozoic articulate brachiopods abstract a systematic survey of all the mesozoic brachiopods in the large collections of the sedgwick museum cambridge university has revealed more than 213 predatory boreholes from a wide range of largely british localities it seems likely that this type of predation was not infrequent at least locally as evidenced by the proportion of bored valves at some localities and the degree of stereotypy shown in borehole positioning the size of the boreholes and their neat circular cross sections suggest that they were made by large epifaunal predators using chemical attack and those of post albian age may be comfortably if not confidentally assigned to muricid gastropods although it is likely that bivalves with their greater flesh yields were the preferred prey item in most mesozoic shelly benthic communities it is apparent that boring predators may have resulted in a significant predation pressure on articulate brachiopods

response of vertisols andosols and alisols to paddy management abstract interchanging submergence and drainage in paddy soils induce alternating redox conditions it is known that this causes changes in organic carbon stocks in amounts and crystallinity of fe oxides as well as transformation of clay minerals and subsequent changes in cation exchange capacity cec however the influence of the initial soil type on the extent of these changes is not yet well understood therefore we studied paddy soils that derived from three different soil types vertisols andosols alisols on volcanic parent material in java indonesia to account for the variability in parent materials we additionally sampled sandstone derived alisols in china adjacent non paddy soils were sampled as references samples were analyzed for texture bulk density clay mineral composition total element content ph cec phosphorus retention organic carbon oc and acid oxalate feox and dithionite citrate bicarbonate extractable fe fedcb only the alisol derived paddy soil in china showed textural changes compared to the non paddy soil evidence for paddy management induced ferrolysis was not found the smaller topsoil clay content in the paddy soil is most probable caused by clay migration only minor differences in clay minerals were found topsoils of andosol derived paddy soils however tend to be less desilicated indicating phytolith accumulation except for vertisols paddy management caused significant depletion in fe oxides in the topsoils puddled layer and plow pan due to redox processes the extent to which the reduced fe was leached or re oxidized as short range ordered fe oxides depended on the soil texture andosols and sandy alisols facilitated leaching clayey alisols re oxidation in either case the stocks of crystalline fe oxides diminished causing increased proportions of short range ordered fe oxides retention of phosphorus was directly related to changes in the absolute amounts of short range ordered fe oxides an accumulation of fe oxides in paddy subsoils was not found lateral transport with drainage water might be a reason in highly permeable soils with large vertical water fluxes e g andosols under paddy management colloidal transport might also play a role despite losses in potential oc storage capacity i e fe oxides clay minerals allophane paddy soils derived from andosols and sandy alisols in china had larger oc concentrations in the puddled topsoil whereby the other soils showed no increase in oc under paddy management therefore paddy management does not necessarily enhance carbon sequestration rather differences in organic matter input between non paddy and paddy soils seem to determine whether oc is accumulated under paddy management or not effects of paddy management on cec were little and mainly due to oc accumulation and fe oxide coating removal from clay minerals overall paddy management induced changes were partly influenced by the original soil and the parent material in turn the main characteristics of the initial soil type were preserved and not overridden by paddy management

the role of egmont sourced tephra in evaluating the paleoclimatic correspondence between the bio and soil stratigraphic records of central taranaki new zealand abstract on the lower eastern flanks of egmont volcano western north island new zealand several egmont sourced tephras have been correlated to a radiocarbon dated peat site that provides a late last glacial to early post glacial record of vegetation and climate change in central taranaki the pollen spectra at this site indicates a mosaic of grassland shrubland and prumnopitys taxifolia dominant forest at ca 13 100 bp and suggests a climate cooler and drier than at present the ominance of tall podocarp forest by ca 12 900 bp suggests that climatic amelioration was rapid towards the end of the last glacial period initially this forest was dominated by prumnopitys taxifolia but at ca 11 000 bp was succeeded by dacrydium cupressinum indicating a steady shift to warmer and moister climate tephra interbedded with peat allows precise chrono correlation into the andisol forming environment the rapidity of climatic amelioration identified from variations in andisol morphology and mineralogy concurs with that indicated from pollen changes in the peat

mineral weathering in trachydacitic derived soils and saprolites involving formation of embryonic halloysite and gibbsite at mt amiata central italy abstract mount amiata is a volcano that has been extinct for 200 ka it is located in southern tuscany central italy and is composed largely of trachydacitic rocks the soils of mt amiata show a dark carbon rich a horizon that overlies a slightly structured bw horizon or directly a very thick saprolite which at a depth of about 3 m still maintains some ellipsoidal cores of coherent material mineral weathering in two of these soils one under beech and the other under chestnut was studied in detail the mineralogy of the parent rock consists predominantly of volcanic glass with phenocrysts of feldspar principally k feldspar biotite and pyroxene the main weathering products are an embryonic form of halloysite and gibbsite while allophane is usually absent or occurs in minor amounts sem evidence indicates that the clay minerals form directly from the weathering of volcanic glass in an environment where si is preferentially depleted in relation to al in the saprolite an anomalous situation is observed where optically fresh ferromagnesian minerals are thickly coated by clay particles whereas the surfaces of the glass and feldspar grains are relatively much cleaner however the ferromagnesian minerals are also much more heavily colonised by fungal hyphae and it is proposed that this results in the preferential deposition or flocculation of colloidal suspensions which translocate from higher positions in the weathering profile

characterization of a weathering sequence of soils derived from volcanic ash in cameroon taxonomic mineralogical and agronomic implications the characteristics of eight pedons developed in quaternary basaltic pyroclasts in western cameroon under humid tropical conditions are reported the soil weathering sequence consists of an andept tropept udalf udult association andic properties physico chemical characteristics and weathering stage clearly distinguish the taxonomic units the total reserve in bases trb and the clay content measured after adequate h2o dispersion with na resins both appear to be suitable weathering indices clay mineralogy of non andic soils shows direct relationships between interstratified halloysite smectite content cec of the clay fraction and weathering stage the weathering stage of the investigated soils is reflected not only in their components and classification but also in their nutrient status and banana crop performance

taphonomic comparison between recent and fossil sand dollars abstract the taphonomy of a recent and a fossil sand dollar are compared the recent echinodiscus auritus originates from a shallow water carbonate environment in the red sea the fossil parascutella hobarthi is found in micaceous sands of the lower miocene austrian molasse zone both species show strong similarities in constructional morphology including the flattened overall shape details of the surface morphology as well as the presence of an internal support system three taphonomic features are remarkable different 1 lethal and non lethal predation especially high in the recent e auritus 2 encrustation of the test especially by coralline algae in the fossil parascutella and 3 radial cracking on implosion of the body cavity caused by sediment loading on the fossil tests differences in taphonomic signatures can be correlated with depositional environment predation and encrustation as well as factors related to burial of the fossil specimens sediment loading and diagenesis

minerals formed and mineral formation from volcanic ash by weathering abstract weathering of volcanic ash and pumice is unique regarding minerals formed and mineral formation these minerals include allophane imogolite opaline silica and some halloysites and have distinctive structures and properties studies on the surface and subsurface weathering of various volcanic ashes in different settings are reviewed this review illustrates that relatively rapid weathering of finely comminuted volcanic ash well reflects the effects of climate vegetation and time and produces various combinations of weathering products the moisture regime the nature and amount of organic matter incorporated the deposition of volcanic ash as overburden and the chemical and mineralogical composition of parent ash are important in controlling the mineral formation in weathered volcanic ash

mineralogical and chemical composition of three tuffs from northern israel abstract the mineralogical and chemical composition of three types black yellow and red of tuffs from mt peres in northern israel that differ in terms of degree of weathering were determined in order to understand the weathering sequence under mediterranean or semi arid conditions the black tuff is very slightly weathered and contains 62 volcanic glass 15 primary minerals 12 titano magnetite 5 halloysite and 4 5 hydroxyapatite the yellow tuff considered to be the weathering product of the black tuff contains only 4 volcanic glass and 21 primary minerals 8 fe rich minerals 51 amorphous material identified as halloysite like allophane 15 halloysite and 5 hydroxyapatite a different mineralogical composition from that of red tuff indicates that this material was formed during a different eruption the red tuff consisted of 29 volcanic glass 26 primary minerals different from those of the black tuff 11 iron bearing minerals 10 halloysite 5 hydroxyapatite and 19 amorphous material the specific surface area and cation exchange capacity of the black red and yellow tuff 7 28 174 m2 g 1 and 107 285 601 mmolc kg 1 at ph 7 respectively were in accord with their amorphous material contents

erodibility and runoff infiltration characteristics of volcanic ash soils along an altitudinal climosequence in the ecuadorian andes abstract soil erosion is a widespread phenomenon in andean south america where many regions are covered with soils derived from volcanic parent materials climate induced differences in the genesis of these soils have been demonstrated along toposequences on volcanic slopes this research was conducted to study the impact of such differential pedogenesis on erodibility and runoff infiltration characteristics along an altitudinal entisols inceptisols andisols sequence in the andes of northern ecuador surface soils were packed into small pans and placed on a 9 slope and a simulated rainstorm with varying intensities was applied for a duration of 30 min the runoff erosion behaviour of the studied volcanic ash soils is strongly affected by their pedological development accumulation of organic matter and precipitation of active amorphous materials at high elevations have led to the formation of well developed andisols with very stable aggregate structure these soils remain wettable when air dried show very high infiltration capacity and consequently low potential for runoff generation and soil erosion low organic matter contents and absence of active amorphous materials at low elevations have led to the formation of weakly aggregated entisols and inceptisols these soils are susceptible to surface crusting which lowers their infiltration capacity and increases their erodibility however in comparison with other soils of different origin and composition the interrill erodibilities determined for these more erodible low elevation soils are classified as low the findings of this study suggest that upland soil erosion is not a major threat to sustainability in the studied volcanic landscape which is generally confirmed by field observations

basalt weathering and pedogenesis across an environmental gradient in the southern cascade range california usa abstract basalt rocks occupy substantial land area and play a significant role in global weathering patterns and biogeochemical cycling the objective of this research was to quantify climatic controls of weathering and pedogenic processes on basalt derived soils across an environmental gradient on the western slope of the casacade range of california usa we hypothesized that climate controls mineral neogenesis with cool moist conditions favoring formation of short range order sro materials and warm dry conditions favoring smectite crystalline fe oxyhydroxides and kaolins four pedons were sampled across an elevation gradient 250 2500 m having large variation in mean annual soil temperature 5 17 c and mean annual precipitation 750 1350 mm the soil mineral assemblage was characterized by x ray diffraction selective dissolution total elemental analysis and light microscopy the degree of weathering and mineral assemblage exhibited a clear threshold at the permanent winter snowline 1200 m maximum soil development was noted just below the snowline with soils dominated by kaolinite and dehydrated halloysite crystalline fe oxyhydroxides 48 kg m 2 extensive loss of cations chemical index of alteration cia 95 and clay accumulation 447 kg m 2 in contrast the high elevation snow dominated pedons displayed less intense weathering e g cia

mineralogy of soils from basaltic ash taveuni fiji abstract the mineralogy of six soil profiles derived from basaltic ash in taveuni fiji has been investigated three stages of weathering are identified weakly weathered soils contain significant amounts of ca feldspar in sand fractions and the clay fractions are dominated by short range order allophanic materials moderately weathered soils contain subordinate ca feldspar in sand fractions and moderate to subordinate short range order allophanic materials in clay fractions strongly weathered soils contain very little ca feldspar and the clay fractions are dominated by gibbsite and 1 1 clay minerals we concluded that short range order allophanic materials are intermediate weathering products and that there is a poor or no relationship between precipitation and the amounts of 1 1 minerals and allophanic materials

lower cambrian cavity dwelling endolithic boring sponges in the lower cambrian forteau formation middle bonnia olenellus zone of southern labrador cavities in archaeocyath patch reefs contain preserved coelobiontic endolithic sponges scallops and carbonate chips produced by sponge boring spicules and preserved endolithic sponge body fossils all point to the presence of endolithic sponges in lower cambrian reef cavities the oldest previously described endolithic sponges are early ordovician in age and the oldest previously known reef interior bioerosion is middle ordovician in age the presence of endolithic sponges in reef cavities of the forteau formation therefore extends both the record of endolithic sponges and of reef interior bioerosion from the ordovician to the upper lower cambrian

comparing volcanic glass shards in unfertilised and fertilised andisols derived from rhyolitic tephras new zealand evidence for accelerated weathering and implications for land management abstract enhanced weathering associated with the use of phosphate fertilisers has been identified in some of the major farming areas of new zealand and an evaluation of its effects on soil properties and the implications for soil management are needed we assessed changes in the character of volcanic glass shards in topsoils 0 10 cm depth of two tephra derived andisols of differing ages udivitrands hapludands and with and without long term fertilisation to test if fertilising accelerates the weathering of soil constituents using visual assessment based on scanning electron microscopy and electron microprobe analyses of glass shards from samples from paired sites we showed that the average sizes of the shards and the sharpness of the glass shard edges angularity diminished with the age of the soil and that these decreases were more marked in the soils that had been fertilised silica polymorphs were observed only in the older soil hapludand that had been fertilised we concluded that the addition of phosphate containing fertiliser enhanced the dissolution of volcanic glass consistent with phosphoric acid and f induced dealumination and desilication and thus soil weathering has been accelerated the al and si may subsequently coprecipitate as secondary minerals such as allophane however silica polymorphs may form where al activity is low the occurrence of neogenic silica in topsoils despite high annual rainfall that should result in desilication of the topsoil and reprecipitation of silica deeper in the soil is explained by the seasonality of fertiliser application and the spring summer climate where the soil remains moist for periods sufficiently long enough for the dissolution of volcanic glass and possibly of other aluminosilicates the formation of al humus complexes and the subsequent precipitation of silica in dry periods implications of the accelerated weathering for soil and land management are discussed

multiple routes to mass accumulations of clypeasteroid echinoids a comparative analysis of miocene echinoid beds of sardinia abstract although clypeasteroid echinoids are very common in the shallow water sediments of the miocene of sardinia they have received little attention as far as their origin is concerned in this paper three sand dollar dominated mass accumulations from the lower miocene of sardinia are studied and compared in order to understand their genesis and palaeoecology two clypeasteroid assemblages were found in the sarcidano region central sardinia within the nurallao formation late oligocene burdigalian the third sand dollar mass occurrence crops out in the logudoro region northern sardinia within the calcari di mores formation late burdigalian these fossil echinoid deposits show a low taxonomic diversity two assemblages are dominated by the genus amphiope while the other is dominated by parascutella with subordinate clypeaster an integrated stratigraphic taphonomic and sedimentological approach allows different genetic mechanisms for these shallow water sandy shoreface deposits to be inferred the origin of these deposits is related to ecological morphological and sedimentological factors the sand dollars of cuccuru tuvullao nuragus show high degrees of abrasion and fragmentation and represent a multiple in situ reworked accumulation while the assemblage of duidduru genoni with low abrasion and variously oriented complete and fragmented specimens constitutes an example of a proximal storm deposits the sand dollar bed of monte sa loca chiaramonti consists of a dense accumulation of well preserved mainly concordant oriented juvenile and adult specimens and is considered to represent an autochthonous assemblage this paper explores the role of detailed sedimentological and taphonomic analysis in the palaeoecological and genetic interpretations of the sand dollar beds and points out the widespread distribution and diversification of these echinoids in the miocene deposits of the mediterranean area

taphonomy of cystoids echinodermata diploporita from the napoleon quarry of southeastern indiana usa the lower silurian massie formation as an atypical lagerstatte abstract diploporites like most pelmatozoan echinoderms are characterized by complex multi element skeletons prone to complete disarticulation if left exposed for extended periods of time consequently preservation of abundant articulated diploporite thecae is rare and generally restricted to environments where rapid burial events could catastrophically entomb individuals one such environment is represented by the lower portion of the wenlock age massie formation at the new point stone quarry near napoleon southeastern indiana which we recognize as a konservat lagerstatte yet taphonomic evidence does not support live burial diploporites holocystites spp are dominantly preserved as intact thecae without any portions of brachioles and with damage plate shifting and plate loss plate jumbling on one side post mortem encrustation is common but epibionts are typically present on the well preserved sides of thecae geopetal sediment fill of thecae shows that the well preserved side commonly faced upward following burial this taphonomic state is paradoxical as burial of live diploporites would have resulted in preservation of complete individuals with no encrusters and only compaction induced damage rapid burial of diploporites following a short interval of exposure would have resulted in preservation similar to observed patterns but with encrusters and geopetal infills indicating that the poorly preserved side faced up and burial after extended exposure would have resulted in thorough disarticulation of thecae rather a variable and in some cases complex taphonomic history is suggested for diploporites from the napoleon quarry with at least some individuals having experienced one or more brief episodes of exhumation prior to final burial early diagenetic cementation of initial theca filling sediment is the most likely mechanism for keeping thecae intact during subsequent exposure

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

towards a weathering model of mount lamington ash papua new guinea abstract the mount lamington ash halo has been studied at six sites both close to and distant from the volcano negligible alumina occurs in the seepage waters from the ash and so alumina is assumed constant during weathering in andesitic ashes weathering to allophane an approximation to a first order reaction was found in 1968 and is confirmed here with given infiltration and silica concentration the weathering rate constant decreases with increasing content of weathering minerals and increasing thickness of ash being weathered the rate constant also increased with increasing infiltration and decreasing median size of the ash the total weathering rate is the product of the thickness percentage of ash being weathered and the weathering rate constant the total weathering rate is the same for thick less weathered proximal ashes as it is for the thin more weathered distal ashes first order kinetics imply a high rate of leaching decreasing with time but continual burial under new ash at a nearly constant rate leads to linear leaching of the upper part of the profile the leaching rate decreases exponentially with depth and appears to ignore buried topsoil barriers it is possible to construct weathering models exploring the rate constant and to link it with leaching rates two thirds of the loss on weathering is silica and there is a total leaching rate of 3 4 mg sio 2 cm 2 year 1 as on basalt in hawaii and on andesite in st vincent water analyses show silica concentrations in the ash of 17 35 ppm and in draining streamlets of 9 20 ppm measured concentrations agree with calculated concentrations from the weathering data silica concentrations are similar in other humid tropical rivers

weathering sequence of soils from volcanic ash involving allophane and halloysite new zealand abstract the clay minerals in a series of soils from rhyolitic ash having the same stratigraphy but different leaching environments were estimated quantitatively by oxalate dissolution infrared spectroscopy differential thermal analysis electron microscopy and x ray diffraction three soils were studied in detail these were the kereone soil mean annual rainfall 1200 mm the ohaupo soil 1400 mm and the mairoa soil 2600 mm the kereone soil contained halloysite as the predominant clay mineral whereas the mairoa soil was mainly allophanic the ohaupo soil contained considerable amounts of both allophane and halloysite thus the allophane content of the soils increased as rainfall increased reflecting a sequence of increased l leaching the si concentration in soil solution decreased as rainfall increased also reflecting increasing leaching of the soils at mairoa si is rapidly removed and allophane al si 2 1 with monomeric silicate is formed whereas at kereone less leaching occurs si levels are higher and halloysite al si 1 1 with polymeric silicate is formed at intermediate sites either allophane or halloysite may form the often reported situation of younger allophanic beds overlying older 10 000 year halloysitic beds may not be due to allophane weathering to halloysite but may result from lower temperature and drier climate during the last glacial maximum between 10 000 and 26 000 years before present bp a new weathering scheme for volcanic ash in new zealand is presented

a micromorphological study of pedogenic processes in an evolutionary soil sequence formed on late quaternary rhyolitic tephra deposits north island new zealand abstract the influence of time as a soil forming factor was studied on an evolutionary sequence of five soils 1850 radiocarbo years bp ca 120 000 bp developed in rhyolitic tephra deposits in new zealand new micromorphological observations were combined with existing macromorphological chemical textural and clay mineralogical analyses to assess the extent of polygenesis in the soils the younger soils 1850 bp to ca 22 600 bp are characterised by initial weathering and little secondary mineral formation this status is expressed by abundant pumice fragments and fresh easily weatherable minerals as well as a low clay content with an isotropic character comminution and neoformation are the main pedological processes the older soils ca 120 000 bp are characterised by a high degree of alteration of primary minerals little or no pumice fragments clay illuviation gleying and a high clay content 80 consisting of a range of crystalline clay minerals including halloysite gibbsite kaolinite and vermiculite plus crystalline iron oxides evidence of polygenesis can be observed in the micromorphology of the older soils 1 the range of secondary minerals is the result of the integration and succession of soil forming processes through time 2 the accumulatory character of the tephra deposits has resulted in stronger weathering of the lower horizons than upper horizons because of continuous pedogenesis such polygenesis in the older soils supports the view that the older the soil the more polygenetic it is likely to be

palaeoecology and taphonomy of spatangoid dominated echinoid assemblages a case study from the early middle miocene of sardinia italy abstract the early middle miocene marine sedimentary succession of the borutta formation cropping out at porto torres northern sardinia represents one of the most diverse and well preserved spatangoid dominated sedimentary successions in the miocene of the mediterranean area the echinoid bearing succession is studied with the twofold purpose of firstly reconstructing the palaeoenvironmental setting in which these echinoids occurred and secondly investigating factors influencing the preservation potential of spatangoid echinoids in the fossil record these goals are accomplished by 1 detailed logging of sedimentary facies 2 applying functional morphological interpretations of echinoid skeletons in order to reconstruct their behaviour and life habits 3 quantifying the relative abundance of taxa and taphonomic features of test preservation and 4 analyzing associated trace fossils within the beds the sedimentary succession is composed mainly of fine grained sandstones which are intensely bioturbated by thalassinoides like burrows spatangoid abundance is high throughout the profile declining only in intercalated dm thick rhodolith beds a 20 cm thick bed with a bedding surface of approximately 250 m2 was investigated in detail with respect to relative abundance of spatangoid taxa and taphonomic signatures the echinoids consist almost exclusively of deposit feeding irregular forms with a dominance of the spatangoids ova and brissopsis and the minute clypeasteroid echinocyamus the spatangoids opissaster holanthus metalia and hemipatagus as well as the clypeasteroid clypeaster marginatus are also present a low energy moderately deep outer sublittoral environment with high rates of bioturbation and episodes of sediment deposition by storms is inferred interspecific competition among deposit feeding echinoids appears to be limited by their different burrowing depths feeding strategies and resource partitioning the gregarious behaviour of spatangoid echinoids their habitat in quiet deeper environments and episodes of rapid deposition seem to represent the main factors leading to this spatangoid bearing deposit since both shallow and deep burrowing spatangoid echinoids are well represented as complete specimens mode of life does not appear to play a major role in their preservation potentials

a wavelet based technique for sea wind extraction from sar images we present the follow up of our previously published work where we described a wavelet based method to characterize the sea surface backscatter structures in synthetic aperture radar sar images the method relies on the ability of the 2 d continuous wavelet technique to detect the spatial structure of the marine atmospheric boundary layer mabl and to isolate wind related cells and features the analysis of the cells geometry molded by the radiometric characteristics of the sea surface permits the identification of the wind direction inside the cells due to the along wind asymmetry of backscatter structures and thus the computation of the wind speed through standard algorithms twenty one sar images ers 2 and envisat asar wide swath over the mediterranean sea have been analyzed and the results are compared with satellite wind fields the images cover a range of meteorological conditions from low to moderate winds comparison of the sar derived wind fields with those provided by satellite scatterometers indicates a good score of success roughly 70 80 the developed methodology once tested over an adequate number of images to derive statistically reliable results could be routinely used to enrich sar images with the wind field as well as to characterize the mabl in terms of size distribution and shape of the backscatter cells