an energy dispersive miniprobe multielement analyzer emma for direct analysis of trace elements and chemical age dating of single mineral grains abstract an energy dispersive miniprobe multielement analyzer emma was designed and constructed for the analysis of trace elements as cr cu fe ga ge hf mn ni pb rb se sr th y u zn in small individual mineral grains such as apatite garnet monazite sphene zircon and other accessory minerals the instrument is sensitive ppm for most elements rapid 3 6 min per analysis non destructive and essentially no sample preparation is required with respect to single zircon grains as small as 50 m with mass as low as a few g for example the detection limits for u th and pb are on the order of 10 ppm 5 10 times better than the electron microprobe here the emma is used to illustrate the variation in hf and y concentrations in single zircon grains from pegmatites granites basalts carbonatites and kimberlites also the instrument is used for chemical age dating u th total pb of 1 single zircon grains from the berdyshevsky intrusive complex ukraine and 2 single monazite grains from a small placer deposit within the transition zone between the saxothuringikum and moldanubikum bavaria germany the average age of the single zircon grains from berdyshevsky granite determined using emma 2 19 0 17 ga 1 is consistent with the u pb zircon intrusion age of this complex 2 14 0 07 ga and monazite data ranging from 1 95 to 2 48 ga with respect to the pegmatite from this complex the average age of 1 93 0 09 ga found with emma is geologically consistent with zircon and monazite ages ranging from 1 90 to 2 29 ga regarding the monazite grains from the placer the age dates obtained using emma 328 28 ma are comparable to the isotopic ages conventional u pb and pb pb step leaching which yielded ages of 312 3 and 324 12 ma respectively

the lilliput effect in the aftermath of the end permian extinction event early triassic animal body fossils and trace fossils are small relative to those in older and younger intervals size decreases sharply through the end permian extinction event and permian triassic boundary and the smallest sizes are encountered in the parvus and isarcica zones of the earliest induan animals appearing within these two zones are also exceedingly small compared to younger congenerics and conspecifics temporary dramatic size decrease of surviving taxa in the immediate aftermath of the extinction event is an example of the lilliput effect coined by urbanek a 1993 biotic crises in the history of upper silurian graptoloids a palaeobiological model historical biology 7 29 50 body size increases somewhat from the carinata zone mid induan but remains depressed for the duration of the early triassic and pre extinction sizes are not commonly recorded until at least the middle triassic marine and terrestrial faunas appear to be similarly affected the lilliput effect and longer term size reduction could be the result of several factors environmental parameters such as marine anoxia due to low atmospheric concentrations of oxygen at this time coupled with sluggish ocean circulation in a greenhouse world and food shortage are the likely proximal causes for the early triassic lilliput effect no single cause can explain all the observations and a combination of factors are likely to be involved

last abundant appearance datum of hemidiscus karstenii driven by climate change abstract the last abundant appearance datum of the endemic southern ocean diatom hemisdiscus karstenii jouse is dated at around 190 000 years before present which provides a robust and convenient biostratigraphic marker to late pleistocene paleoceanographic studies however no prior studies have sought to understand what processes may have driven h karstenii to extinction we here present the first morphometric investigation of h karstenii over marine isotope stage mis 10 to 6 355 000 years to 150 000 years the combination of these data to records of h karstenii absolute abundances fragilariopsis kerguelensis biometry and absolute abundances and southern high latitude air and ocean temperatures over the past 355 000 years suggests that h karstenii populations reduced their mean size and productivity in response to the rapid drop in temperatures across the mis 7 to mis 6 glacial inception this prolonged cooling event may have pushed h karstenii to its adaptive limit until it could not sustain physiological viability the repetitive occurrence of very cold events during the early mis 6 may have additionally prevented surviving populations of h karstenii from re establishing abundant communities leading to extinction late in mis 6

prolonged residence times for the youngest rhyolites associated with long valley caldera 230th 238u ion microprobe dating of young zircons abstract we describe a new ion microprobe method for dating magmatic zircon growth that is based on in situ measurement of the magnitude of238u 230th disequilibrium our results support independent inferences that zircon can remain suspended for long periods 100 ka in the convecting potions of the magma from which it crystallizes because the crystallization ages date when the magma cooled to its zircon saturation temperature even when the zircons have long magmatic residence times 238u 230th zircon dating can be used to constrain the thermochemical evolution of silicic magmas 238u 230th ages have been determined for individual zircons from rhyolites associated with the long valley magmatic system of eastern california the samples are from deer mountain an 115 3 ka low silica moat rhyolite and from the coarsely porphyritic low silica rhyolite of south deadman dome one of the 0 6 ka inyo domes previous investigations have suggested that the two lavas were derived from the same magma reservoir a few of the zircon model ages calculated with respect to the isotopic characteristics of the whole rocks are within error of that for eruption of the deer mountain rhyolite however the majority of zircons from both lavas cluster around an age of 230 ka this common interval of zircon nucleation and growth for petrologically similar lavas suggests that the younger inyo dome lava may have tapped the same magma body from which the deer mountain rhyolite erupted more than 100 ka before on the other hand most of the zircon model ages are younger than previous episodes of silicic volcanism in the long valley caldera suggesting that the rhyolites may have been generated during development of a silicic upper crustal magma chamber in the western portion of long valley caldera zircon saturation temperatures for the rhyolites studied 795 810 c are the same as those obtained from coexisting fe ti oxides 809 4 c showing that the magma cooled to

field relationship of high grade neo to mesoarchaean rocks of south east greenland tectonometamorphic and magmatic evolution abstract south east greenland forms part of the north atlantic craton and is characterized by migmatitic orthogneisses narrow bands of mafic granulite ultramafic and possible meta sedimentary rocks and alkaline carbonatitic intrusive rocks mafic granulite meta sedimentary and ultramafic rocks form the basement for the emplacement of granitic intrusions at ca 2865 ma that lasted episodically until ca 2790 ma and continuously during 2750 2700 ma the area is structurally complex with evidence of at least seven deformation events including reclined and mushroom like fold interference patterns an older 2790 ma foliation formed in granitic rocks and the basement during the timmiarmiut orogeny dt deformation associated with the ca 2790 2700 ma skjoldungen orogeny folded this early foliation and is associated with a penetrative foliation that is refolded progressively in a northeast southwest oriented stress field the orientation of the stress field progressively rotated into a northnorthwest southsoutheast orientation during the last stages of the orogeny the orogeny is also characterized by syn deformational anatexis at granulite facies at approximately 800 c and 5 8 kbar ca 2790 2740 ma which decreased to the amphibolite facies at ca 2730 ma the late to post tectonic granite and alkaline rocks assigned to the skjoldungen alkaline province intruded the central northern part around 2710 ma this was followed by north south extensional deformation during the singertat stage forming discrete shear zones at greenschist facies grades which is coeval with the emplacement of pegmatite ijolite and carbonatite emplacement during ca 2680 2650 ma similar lithology and tectonic processes in the tasiusarsuaq terrane of southern west greenland and the lewisian complex in scotland suggest a possibly large archaean terrane at that time which taking the present size at least covered around 500 600 km in an east west direction and approximately 200 km in a north south direction

planktonic foraminiferal biostratigraphy and mechanisms in the extinction of morozovella in the late middle eocene the muricate planktonic foraminiferal genera morozovella and acarinina were abundant and diverse during the upper palaeocene to middle eocene and dominated the tropical and subtropical assemblages a significant biotic turnover in planktonic foraminifera occurred in the latest middle eocene with a notable reduction in the acarininid lineage and the extinction of the morozovellids these genera are extensively employed as palaeoclimatic and biostratigraphic markers and therefore this turnover episode is an important event in the record of the cenozoic planktonic foraminifera sediments from the western north atlantic ocean drilling program site 1052 were examined in order to investigate these extinction events in terms of both timing and mechanisms biostratigraphic events of the middle and late eocene have been examined with a sampling resolution of approximately 3 kyr these have been calibrated to the magneto and astrochronology to accurately define the timing of key biostratigraphic events particularly the extinction of morozovella spinulosa which is a distinct biomarker for late middle eocene sediments high resolution biostratigraphy reveals that the extinctions in the muricate group occurred in a stepwise form the large acarininids acarinina praetopilensis terminate 10 kyr prior to the extinction of m spinulosa and small acarininids acarinina medizzai and acarinina echinata continue into the upper eocene high resolution stable isotope analyses have been conducted on planktonic and benthic foraminifera from the western north atlantic to reconstruct sea surface temperatures ssts and deep water temperatures and the structure of the water column around this major biotic turnover whilst the extinctions of m spinulosa and a praetopilensis occur during a long term cooling trend the biotic turnover in the muricate group does not appear to be related to significant climatic change sea surface temperatures decrease slowly prior to the extinction events and there is no evidence for a large temperature shift associated with the faunal changes the turnover event was therefore probably related to the increased surface water productivity and the deterioration of photosymbiotic partnerships with algae d 2003 elsevier b v all rights reserved

pedogenesis and pre colombian land use of terra preta anthrosols indian black earth of western amazonia abstract the terra preta de indio indian black earth or terra preta of western amazonia is a thick dark coloured anthropic epipedon usually rich in nutrients it occurs mostly at the fringes of the terra firme along the amazon river banks overlying deep strongly weathered soils we studied selected chemical physical and mineralogical properties of seven soils ranging from the tertiary plateau down to the amazon river floodplain in the iranduba district near manaus amazonas brazil three terra preta soils were classified as anthropogenic anthropic xanthic kandiudult anthropic xanthic kandiudox and anthropic dystropepts chemical mineralogical and micropedological attributes such as high total and available p and mica flakes in pottery remains found in the terra preta indicate that the origin of soil materials of these anthrosols is closely associated with neighbouring floodplain varzea soils and sediments amazon floodplain soils were the source of soil material for pottery since 2 1 clay minerals are not found in the tertiary plateau terra firme sediments total and available p contents of terra preta are associated with microfragments of bone apatite with high p and ca values in the anthrosols under cultivation these values are less with increasing al release suggesting acidification and losses of nutrients large amounts of mn and zn occur in the anthrosols and in high fertility floodplain soils it is unlikely that well drained tertiary plateau terra firme area far away from lowland amazon floodplain soils could develop high fertility terra preta on the top of nutrient poor oxisols latosols the suggested model of terra preta formation between the tertiary plateau and nutrient rich amazon floodplain does not extend to other nutrient poor smaller floodplains draining the deep weathered interfluves of the brazilian uplands this raises reservations about estimates of precolonial human population densities for the amazon basin as a whole assuming the widespread occurrence of such anthrosols farther inland

impact of forest tree species on feldspar weathering rates abstract an in situ experimental approach was used to test the impact of several forest tree species on weathering of a plagioclase used as a test mineral tree species were norway spruce scots pine sessil oak pedunculated oak and european beech the experiment was carried out by putting a fixed mass of test mineral into the soil under different tree species stands located in the same conditions test minerals were inserted into soils at various depths 0 5 15 40 cm and then maintained over two periods 3 and 9 years at the end of their incubation period test minerals were collected weighed and analysed mass losses of test minerals were highest for bags inserted under litters 0 cm depth at 0 and 5 cm depth dissolution rates significantly decreased over the 9 years of the experiment there was a significant positive linear relation between specific surface area of test minerals and their mass losses test mineral evolution in mass and specific surface area was strongly dependent on environmental conditions mostly soil ph and soil type test minerals which were inserted into soil layers of low acidity ph 4 5 had very low mass losses and specific surface area increments coniferous species promoted mass losses more significantly than broadleaved species did tree species provoked more or less mass losses through modifications in the acidity of the soil

geochemistry and zircon u pb hf isotopes of the late neoarchean granodiorite monzogranite quartz syenite intrusions in the northern liaoning block north china craton petrogenesis and implications for geodynamic processes abstract late neoarchean weakly foliated to massive granodiorite monzogranite quartz syenite intrusions are widely distributed in the northern liaoning block north china craton la icp ms zircon dating reveals that these rocks were emplaced during 2 56 2 53 ga and underwent regional metamorphism at 2 51 ga these granitoid rocks that contain abundant k feldspar and high k 2 o contents with high k 2 o na 2 o ratios can be subdivided into four lithological types based on their lithological and geochemical characteristics including porphyritic granodiorites medium grained granodiorites medium grained monzogranites and porphyritic quartz syenitic gneisses the porphyritic granodiorites contain biotite as the main mafic mineral and are characterized by high la yb n 16 60 and sr y 46 93 ratios low yb and y contents and weakly positive eu anomalies for most samples they also show depletion of nb ta and ti in the primitive mantle normalized spidergrams with zircon e hf t 2 values of 3 8 to 6 3 suggesting that they were derived from partial melting of juvenile high k mafic rocks at the lower crust the medium grained granodiorites have major mafic minerals of hornblende and biotite they display zircon e hf t 2 values 4 6 to 7 5 similar to the porphyritic granodiorites and have higher cao contents molar cao mgo feo tot ratios and yb y contents with relatively lower la yb n 9 34 and sr y 29 43 ratios for most samples they show weakly negative eu and sr anomalies for most samples with significant nb ta and ti depletion indicating that they might be produced by partial melting of calc alkaline volcanic sources with higher cao contents at relatively higher levels of the lower crust compared with the porphyritic granodiorites the medium grained monzogranites show the highest sio 2 contents 69 71 77 64 wt strongly to moderately fractionated ree patterns la yb n 25 69 for most samples and weakly positive to significantly negative eu and sr anomalies with zircon e hf t 2 values of 2 4 to 4 7 indicating that they may be produced by partial melting of metagreywackes at middle to lower crustal levels the porphyritic quartz syenitic gneisses exhibit the highest k 2 o concentrations of 5 11 7 05 wt and are attributed to the shoshonitic series and they are featured by high la yb ratios 34 45 and positive eu and sr anomalies with zero straddling zircon e hf t 2 values 2 4 to 4 1 we consider that they might be derived from partial melting of a mixed source of juvenile mafic rocks and ancient continental materials in the deep lower crust integrating the available data from the previous studies we conclude that a late neoarchean active continental margin setting can account for the generation of these granodiorite monzogranite quartz syenite intrusions

impact of drainage on soil forming mechanisms in a french albeluvisol input of mineralogical data in mass balance modelling research on soil pedogenesis has mainly focused on the long term soil formation and has most often neglected recent soil evolutions in response to human practices such recent soil evolutions are however of considerable interest to study the timing of soil forming processes in response to changes in environmental conditions in this paper we model the albeluvisol evolution in response to agricultural drainage this was considered as a model case to study the velocity of mineralogical changes in soil as a result of eluviation and redox processes we used a space for time substitution approach in combination with mass balance modelling based on mineralogical data in order to identify and characterise the mineralogical transformations responsible for the recent soil evolution in response to subsurface drainage this approach allowed demonstrating that the main effects of subsurface drainage are i increasing precipitation of mn oxides and mn rich ferrihydrite with decreasing distance to the drain as a result of the change in redox conditions and ii increasing loss of clay sized oxides and smectites due to the enhanced eluviation in the vicinity of the drain both processes induce significant matter fluxes in comparison with those that occurred over the long term soil formation nowadays the precipitation of mn oxides and mn rich ferrihydrite seems to still be active in the studied soil on the opposite the eluviation process appears less active than immediately after the drainage network installation if not totally inactive it thus demonstrates that some soil processes may have significant impact on the soil mineralogical composition even if they are only active over very short periods of time after a change in environmental conditions

investigation of pre extinction dwarfing in cenozoic planktonic foraminifera abstract we propose a phenomenon termed pre extinction dwarfing in cenozoic planktonic foraminifera high resolution morphometric analysis shows a reduction in maximum or mean test size in the 2 20 kyr interval preceding the extinction of pliocene globorotalia exilis and globorotalia miocenica from the caribbean sea and middle eocene morozovelloides crassatus from the western north atlantic through a series of case studies and review of qualitative observations from the literature we suggest that dwarfing occurs in a number of species of planktonic foraminifera foreshadowing their demise and that such size changes are not just a phenomenon associated with mass extinction events we propose that this is a common stress induced pattern that results in diminutive size in the pre extinction interval

size variation of conodonts during the smithian spathian early triassic global warming event the early triassic smithian spathian boundary ssb crisis coincided with an episode of extreme warmth a high resolution stratigraphic framework comprising six conodont zones is provided in the jiarong section nanpanjiang basin in south china detailed size measurements of 441 conodont elements of the closely related genera neospathodus triassospathodus and novispathodus show for the first time that this clade suffered a temporary but significant size reduction during the ssb crisis the size reduction of conodonts was probably caused by an episode of global warming

an archaeopedological and phytolitarian study of the dark earth on the site of rue de dinant brussels belgium during the excavations of the site of rue de dinant in the historic centre of brussels belgium remains of the first city wall dating from the 13th century have been discovered intra muros thick dark sediment units predating this wall are observed these dark units are among the oldest occupation traces so far encountered in this higher eastern part of the historic centre of brussels in order to characterise them and to understand the human activities and natural processes behind their formation an interdisciplinary research integrating archaeopedology and phytolith study has been undertaken this approach permitted us to identify a range of natural and cultural processes leading to the formation of these dark layers and to characterise different activities remains of a hearth old plough land cropfields and grassland have been identified all activities referring to a rural landscape organisation later on the area changes into an enormous silt extraction area whereby dark earth is thrown into the dug pits finally the construction of the first city wall marks the area as becoming part of the city the study of dark earth shows to be a potentially valuable tool to shed light on the development and spatial organisation of pre urban brussels a historically very poorly documented period

illuviation intensity and land use change quantification via micromorphological analysis abstract among soil processes governing the clay size fraction distribution with depth illuviation is not only widespread but also particularly poorly understood using a micromorphological approach this study aims at i quantifying the intensity of illuviation independently of all other competing soil processes ii testing the sensitivity of illuviation to different land uses and iii assessing the relative contribution of illuviation to the genesis of textural differentiation two luvisols developed from loess in northern france were selected the first under a deciduous forest and the second under conventional agricultural management both with no change in land use for at least 100 years in addition to classical mass balance calculations clay illuviation features such as limpid and dusty clay coatings were used as diagnostic features of the illuviation process and were quantified by a point counting approach in large thin sections in the two luvisols under study illuviation was found to be responsible for 75 and 86 of the textural contrast respectively in the cultivated soil and the forested one illuviation was thus by far the dominant factor causing textural differentiation even if accessory processes involving the clay size fraction were also at play such as lithological discontinuity clay neoformation or biological and physical reworking the recognition of dusty clay coatings considered as an indicator of cultivation in the soil under forest underlines the sensitivity of illuviation to past periods of cultivation and the legacy of anthropedogenesis on the present soil properties a qualitative change in the nature of the translocated particles without significant changes in the intensity of illuviation was identified in the soil under cultivation in comparison with the soil under forest these results support the conclusion that illuviation is an active process in soils under present climatic conditions and must no more be considered as a fossil soil process

studying urban stratigraphy dark earth and a microstratified sequence on the site of the court of hoogstraeten brussels belgium integrating archaeopedology and phytolith analysis abstract soil micromorphology has become an important tool in urban archaeology to investigate enigmatic dark humus rich apparently homogeneous units known as dark earth it has also proven to be of great value to study microstratified sequences such as floors allowing a finer grained picture phytolith studies have also shown to be of particular interest to investigate archaeological layers especially where other botanical remains are poorly preserved the integration of phytolith studies and micromorphology allows understanding of the distribution and orientation patterns of the phytoliths and their relation to other features fabrics contributing to a better understanding of taphonomical processes and the identification of different human activities the aim of the present article is to demonstrate the possibilities of such an integrated approach by the example of the site of the court of hoogstraeten situated near the top of a steep slope next to the palace of the dukes in the centre of brussels belgium the present article focuses on one complex sequence that includes two levels of dark earth and a microstratified sequence the integrated study demonstrates that the formation of the dark earth on the site of the court of hoogstraeten results from multiphased processes whereby various human actions interact with natural phenomena among the human activities pasturing crop growing manuring and composting have been identified the microstratified sequence has been identified as a potential floor layer as such this approach does not only allow understanding the site formation processes both from homogenised units like dark earth and microstratified ones but also identification of ancient activities that are rather difficult to interpret based on field data alone

image analytically derived conceptual model of albeluvisol morphological degradation induced by artificial drainage in france abstract soils are a non renewable resource and evolve through time in response to changes in land use and environmental conditions to predict this soil evolution requires the development of mechanistic modelling only a few attempts of this kind exist in the literature and these often use an extremely simplified representation of soil structure with the soil being frequently considered as a succession of homogeneous boxes in this paper we have quantified the evolution of the soil structure during pedogenesis using image analysis this analysis was performed along a sequence of morphological degradation in an albeluvisol perpendicular to a drain these soils which are commonplace in europe are characterised by horizons consisting in a juxtaposition of soil volumes differing in texture silty to clayey and colour ochre pale brown white grey and black the image analysis approach was based on these differences in colour and combined i a supervised training method using erdas imagine to assign the different pixels to the different types of soil volumes and ii arcinfo for characterisation of the morphology of the different soil volumes the organisation of the different volumes in space suggests that ochre volume is transformed to pale brown one and then to grey white one whilst black volume is formed within the residual ochre one due to precipitation of mn as the process progresses along the drainage sequence progressive indentation and final disintegration of the ochre volume are responsible for the release of the black volume into the pale brown matrix ochre volume alteration takes place mainly at the border of the volume which is indicated by the geometry of the pale brown and ochre volumes finally the formation of the white grey volume from the pale brown one occurs in the core of the latter mainly by eluviation and is centripetal we conclude that soil structure needs to be considered when modelling pedogenetic soil evolution

a 3d electrical resistivity tomography survey to characterise the structure of a albeluvic tonguing horizon composed of distinct elementary pedological volumes abstract water and gas transfer in porous media like soils are determined by their porous network described by their structure in soil the horizon is usually considered to be elementary and homogeneous functioning system in the description of gas and water functioning however in some cases a horizon is heterogeneous and its structure is defined by the 3d arrangement of elementary pedological volumes epvs the horizon needs to be described in three dimensions to improve the characterisation of the structure and consequently the prediction of its hydraulic functioning the aim of this study was to determine the feasibility of describing the 3d structure of a heterogeneous albeluvic tonguing soil horizon composed of a juxtaposition of silty white and clayey ochre epvs using 3d electrical resistivity tomography ert electrical measurements were compared with geostatistical analyses from soil photographs we demonstrated that the resistivity of the white epvs was greater than that of the ochre epvs in addition the general soil structure and organisation of the soil horizon could be derived from the electrical resistivity data we proposed a method to discretise the soil electrical resistivity into a binary system that corresponded to white and ochre volumes finally a 3d representation of the soil structure was created that could be used to improve soil hydraulic models

thermotectonic evolution of a rifted continental margin fission track evidence from the kangerlussuaq area se greenland fission track analyses of apatites from sediments precambrian gneisses and caledonian to tertiary intrusive rocks from the kangerlussuaq region reveal its post caledonian thermotectonic history inland the history involves cooling to temperatures within the high temperature part of the apatite annealing interval and slow cooling or reheating continued in cretaceous times through this interval apatites from coastal areas between kangerlussuaq and tasiilaq reveal only tertiary cooling in tertiary times cooling accelerated after the main intrusive phase in the tertiary the evolution is taken as evidence for a general uplift erosion since caledonian times probably disturbed by basin formation and sedimentation and reheating due to magmatic activity thermal subsidence of the rift shoulders following the opening of the adjacent oceanic basin is not indicated annealing patterns inland of the plume centre in the kangerlussuaq provide no evidence for the earlier movement of the plume from a westerly direction

magnetite originating from bonfires in a brazilian prehistoric anthrosol a micro raman approach abstract soils within archaeological sites may show magnetic properties due to the presence of magnetic minerals such as magnetite and maghemite which form during deposition of the soil or due to local fires the similarities in the crystallographic structures of magnetite and maghemite lead to difficulties in the identification of these mineral phases this work aims to study the genesis of fe nodules at an archaeological site in a cave in quartzite with a very low fe content and no spinel group minerals the guiding hypotheses of the research are as follows i the abundant fe nodules in all the studied stratigraphic layers are of pedogenic origin and were generated by local bonfires and ii these fe nodules are composed of magnetite maghemite and hematite and the conversion of magnetite to maghemite indicates pedogenic processes micromorphological analysis and raman spectroscopy were used for mineral phase determination the results confirm the in situ pedological nature of the fe nodules associated with anthropogenic fires in the cave

soil forming processes of ancient man made soils cultural layers by the example of sites in humid dunino and arid ar dolong regions of russia a first approach abstract the specificity of cultural layer transformation by soil forming processes was examined in humid moscow region and arid kalmykia zones of russia the objects studied in the two regions are the dunino and ar dolong settlements the former is attributed to the early iron age and the latter to the bronze age archaeological excavations in both places revealed numerous ancient artifacts occurring in situ which prove the sites having been inhabited in the past though located in different natural zones the investigated objects have two features in common sandy parent material and the leading role of the anthropogenic factor in the past morphological examination was supplemented with analysis of chemical properties organic and inorganic matter total phosphorus ph at the arid site humic acids extracted from the organic matter in the ancient cultural layer have been dated by radiocarbon simultaneously the background soils were also studied though both ancient settlements were abandoned for a long time the cultural layers have not been buried under later sediments they stayed exposed and subjected to transformations by soil forming processes the duration of the latter was different at the two sites not exceeding 2 ky in the humid zone and about 3 0 3 5 ky in the arid zone after people had left the settlements younger soils developed in the course of pedogenesis their morphology being similar to the zonal soils integrated analyses of soils enable determination of how far the natural processes have gone in the cultural layer transformation the determination of the total phosphorous provides a means for cultural layer diagnosis with confidence long after the settlement had been abandoned it is possible to determine the trends for human made soil development in different climate zones from arenosol to podzol and arenosol to andosol in humid and arid zones respectively in the course of time the cultural layers of ancient settlements are being transformed into zonal soils no matter the geographical location of the region however the rate of transformation both of individual soil features and of the entire soil profiles is variable transformation rate of ancient non buried cultural layers is higher in the humid environment than in the arid environment

dwarfism of irregular echinoids echinocorys from poland during the campanian maastrichtian boundary event abstract the echinoid genus echinocorys is one of the dominant irregular echinoid in the cretaceous of poland our analysis of the body size trends of these echinoids shows that they underwent dwarfism in the early maastrichtian the reduction in body size in these echinoids was likely an ecological response to the major climate perturbations connected with the campanian maastrichtian boundary event cmbe that was characterized by a long lasting negative carbon isotope excursion and cooling this is consistent with the fact that food limitations and cold temperatures are among the major factors decreasing growth rates in modern echinoids so far in the case of echinoids the so called lilliput effect has been only recognized in the early danian early paleogene heart urchins atelostomata thus our study shows that the reduction in the body size in echinoids was a more common biotic response to environmental stress than previously thought

glacial to postglacial drop in productivity in the western equatorial pacific mixing rate vs nutrient concentrations primary productivity in the western equatorial pacific was distinctly higher during the last glacial period than today judging from the abundance patterns of benthic foraminifers in box cores from the ontong java plateau the export of organic matter dropped by a factor of 1 7 during the last glacial to interglacial transition on the basis of global calibration of estimated export against accumulation rates of benthic foraminifers using detailed information on 13 c stratigraphy of planktic and benthic foraminifers for the past 20 ka together with a simple two box ocean model we calculate that upward mixing and diffusion of subsurface waters decreased by a factor of 1 4 while nutrient content decreased by a factor of 1 2 over this time span

recovery from the end permian extinction event evidence from lilliput listracanthus abstract we report the reduction of dermal denticle size in the chondrichthyan listracanthus in the context of other in faunal changes observed in a lower triassic section near wapiti lake british columbia listracanthus is the first chondrichthyan to show this lilliput effect following the great end permian mass extinction in our attempt to collate diverse information from associated faunal assemblages and large macrofossil collections we interpret the change in denticle size in listracanthus as occurring at around the induan olenekian boundary the relatively small change in denticle size can be interpreted in terms of the relative lack of effect of the biotic crisis on this chondrichthyan and maybe others or alternatively as the relatively much larger body size of listracanthus in comparison with other permo triassic boundary lilliput taxa it is speculated the lack of denticle enameloid and well developed vascularisation along with the moderate minimum in size below the induan olenekian boundary may indicate that listracanthus denticles are not necessarily external skeletal elements but possibly modified dermal denticles gill rakers of a large basking shark it is concluded that discovery of the early triassic species listracanthus pectenatus creates a ghost lineage of 30 ma and highlights the significance of discovering perishable remains of chondrichthyans in order to understand faunal changes across the permo triassic boundary

changes in size and growth rate of lilliput animals in the earliest triassic abstract marine invertebrate taxa that survived the late permian latest changhsingian mass extinction event are all much smaller than they were prior to the event an example of the lilliput effect new taxa that first appeared in the immediate extinction aftermath are also small compared to their size in younger strata the lilliput effect is a temporary phenomenon with most surviving taxa returning to pre extinction size in the first two conodont zones of the triassic in this study the growth rates of some of the early triassic lilliput animals estimated by growth line analysis were compared from different stratigraphic levels to determine how this variable fluctuated as body size returned to pre extinction values after the event specimens were collected from the mazzin and siusi members of the werfen formation in northern italy from facies deposited in a tropical mixed siliciclastic carbonate ramp setting measurements of the bivalves unionites and claraia the gastropod bellerophon and the brachiopod lingula were made in the field with subsequent growth line analysis conducted on well preserved specimens of lingula specimens collected from the basal triassic mazzin member were smaller than those from the younger siusi member growth line analysis indicates that the smaller mazzin member specimens had a greater number of more closely spaced growth lines than the larger siusi member specimens the small lilliput animals living in the immediate aftermath of the late permian event therefore suffered more interruptions to growth and had overall slower growth rates than larger individuals living in later recovery times frequent interruptions to growth and an overall slower growth rate in specimens from the hindeodus parvus and isarcicella isarcica zones of the mazzin member lower induan reflects suboptimal environmental conditions such as the frequency or severity of low oxygen episodes temperature extremes and or disruptions to primary productivity

earthen mound formation in the uruguayan lowlands south america micromorphological analyses of the pago lindo archaeological complex the stratigraphic excavation of the pago lindo archaeological complex in central eastern uruguay la plata basin helped to propose an alternative model for mound formation that expresses the intrinsic complexity of prehistoric earthen architecture this model known as the spatial temporal discontinuous model sees mound complexes as multi functional areas with diverse earth works occupied and abandoned intermittently since earthen mound sediments are homogeneous resemble natural soils and show evidences of intense bioturbation soil micromorphology was used to confirm refute and further investigate issues raised during field work related with the prime material used for mound construction detection of major episodes of mound building identification of activity areas and taphonomic processes in this paper we present the results of the micromorphological analyses of two different earth works from the pago lindo archaeological complex a mound and a micro relief analyses proved the recurrent use of surface horizons for mound and micro relief building throughout the entire period of site occupation it also demonstrated the difficulty in identifying discrete depositional episodes and occupation surfaces because of the intense bioturbation two activity areas where recognized a domestic hut built over a platform ca 1600 yrs bp and an area of plant residue accumulation over a platform raised almost 800 hundred year after the domestic hut the practice of cleaning the occupation surfaces was interpreted from the complete absence of bioarchaeological remains bones and micro charcoal the use of micromorphology as a complementary tool in the stratigraphic excavation of pago lindo unraveled evidences that corroborate a newly proposed model for mound growth

dating constituent formation in soils to determine rates of soil processes a review abstract rates of soil processes are poorly known one approach to determine them could be through the radiogenic isotopic dating of soil constituents such methods have been recently used to date minerals in soils and weathering profiles thanks to the development of high resolution techniques such as 40ar 39ar u series of micro drilled samples u series by laser ablation and u th he and to the development of suitable methodology expanding application of the techniques to a variety of supergene minerals e g fe and mn oxihydroxides carbonates etc in this paper we identify i the main soil constituents that can be dated through these isotopic methods that are mainly fe oxides mn oxides pedogenic carbonates and organic matter ii the main pedogenic processes that leads to their formation in soils and iii the different soil settings that allow transforming soil constituent ages into rates of soil processes namely growth bands transformation fronts and chronosequences

end guadalupian extinction of the permian gigantic bivalve alatoconchidae end of gigantism in tropical seas by cooling abstract the unique permian bivalve family alatoconchidae has aberrant shell forms and extraordinary size up to 1 m representing the largest bivalve group in the paleozoic their occurrence is reported sporadically from lower middle permian shallow marine carbonates in 9 areas in the world tunisia croatia oman iran afghanistan thailand malaysia the philippines and japan that cover low latitudes of both the tethyan and panthalassan domains alatoconchids almost always occurred in close association with large tested fusulines verbeekinidae and or rugose corals waagenophyllidae of the typical tethyan assemblage suggesting their preferential adaptation to shallow warm water tropical environments this tropical trio alatoconchidae verbeekinidae and waagenophyllidae became extinct either during the late guadalupian or around the guadalupian lopingian boundary g lb their intimate association and occurrence range suggest that these 3 taxonomically distinct clades may have shared not only a common habit but also a common cause of extinction the shell structure of alatoconchids suggests their symbiosis with photosynthetic organisms algae cyanobacteria in order to maintain their large body size that required high energy consuming metabolism in contrast to smaller forms the alatoconchidae attained their largest size in the wordian middle guadalupian probably maximizing the benefits of photosymbiosis the subsequent extinction of the warm water adapted tropical trio both in tethys and panthalassa positively supports the explanation that a critical cooling took place on a global scale including low latitude oceans the end of the gigantism in fusulines and bivalves in the capitanian late guadalupian was likely caused by the collapse of photosymbiotic systems during a temporary temperature drop of seawater kamura cooling event coupled with eutrophication that was detrimental to the tropical fauna adapted particularly to oligotrophic conditions gigantism of bivalves occurred several times in the phanerozoic e g siluro devonian permian triassic early jurassic and jurassic creataceous mostly in warm periods the sea level change in the phanerozoic apparently synchronized with the intermittent rise and decline of bivalve gigantism suggesting that the photosymbiosis related gigantism in low latitudes may serve as a potential monitor of global warming cooling in the past

massive dissociation of gas hydrate during a jurassic oceanic anoxic event in the jurassic period the early toarcian oceanic anoxic event about 183 million years ago is associated with exceptionally high rates of organic carbon burial high palaeotemperatures and significant mass extinction heavy carbon isotope compositions in rocks and fossils of this age have been linked to the global burial of organic carbon which is isotopically light in contrast examples of light carbon isotope values from marine organic matter of early toarcian age have been explained principally in terms of localized upwelling of bottom water enriched in 12c versus 13c refs 1 2 5 6 here however we report carbon isotope analyses of fossil wood which demonstrate that isotopically light carbon dominated all the upper oceanic biospheric and atmospheric carbon reservoirs and that this occurred despite the enhanced burial of organic carbon we propose that as has been suggested for the late palaeocene thermal maximum some 55 million years ago the observed patterns were produced by voluminous and extremely rapid release of methane from gas hydrate contained in marine continental margin sediments

ocean stagnation and end permian anoxia ocean stagnation has been invoked to explain the widespread occurrence of organic carbon rich laminated sediments interpreted to have been deposited under anoxic bottom waters at the time of the end permian mass extinction however to a first approximation stagnation would severely reduce the upwelling supply of nutrients to the photic zone reducing productivity moreover it is not obvious that ocean stagnation can be achieved numerical experiments performed with a three dimensional global ocean model linked to a biogeochemical model of phosphate and oxygen cycling indicate that a low equator to pole temperature gradient could have produced weak oceanic circulation and widespread anoxia in the late permian ocean we find that polar warming and tropical cooling of sea surface temperatures cause anoxia throughout the deep ocean as a result of both lower dissolved oxygen in bottom source waters and increased nutrient utilization buildup of quantities of h2s and co2 in the late permian ocean sufficient to directly cause a mass extinction however would have required large increases in the oceanic nutrient inventory

mineralogy of clay fractions of some soils on loess in northern france abstract important field characteristics of soils on loess deposits in northern france result primarily from processes of clay migration two successive steps can be distinguished the first has uniformly distributed brown primary clay coatings in a brown matrix hapludalfs the second has features of hydromorphy and degradation especially bleached tongues penetrating into the horizon of clay accumulation with gray secondary clay coatings in the lower parts the mineralogy of fine and coarse clay in the two kinds of soils shows an identical mixture of different materials quartz kaolinite mica chlorite an heterogeneous complex of minerals having micaceous smectitic vermiculitic and chloritic layers and smectite the first four minerals predominate in the coarse clay the complex and the smectite in the fine clay the only fundamental difference between primary and secondary stages is a difference in distribution of free iron the latter being characterized by a strong local redistribution due to redox processes the coarse clay in the upper part of the glossic soils has an obvious increase in chlorite relative to the other minerals the chemical composition indicates that this chlorite is trioctahedral excluding a process of secondary chloritization

morphogroups and small sized tests in pseudotextularia elegans rzehak from the late maastrichtian succession of meghalaya india as indicators of biotic response to paleoenvironmental stress abstract cretaceous paleocene shelf successions of therriaghat and mahadeo in meghalaya india preserve almost the whole of the late maastrichtian stage in which the warm water tethyan planktonic foraminifera pseudotextularia elegans rzehak occurs in the racemiguembelina fructicosa zone zone cf4 and pseudoguembelina palpebra zone zone cf2 as five distinct morphogroups a e morphogroups a c commonly occur in rocks representing the transgressive regime of the r fructicosa zone at therriaghat whereas that of p palpebra zone was conducive for morphogroup d in the deeper shelf around therriaghat and morphogroup e in the near shore shelf around mahadeo the absence of p elegans in the pseudoguembelina hariaensis zone zone cf3 is postulated due to tectonic cause whereas its absence in the plummerita hantkeninoides zone zone cf1 was due to regression analysis of growth parameters including length width thickness and angle of flaring of the tests of the species reveal that morphogroups b and c are generally larger in size than the other morphogroups and the test length of the meghalaya specimens is smallest over its world occurrences diverse morphogroups and small tests are unique in the species of meghalaya however the cause of such unusual growth is difficult to explain due to development close to the tectonically active deccan volcanic province and the assam arakan and himalayan mobile belts the meghalaya shelf had unusual biotic stress due to volcanic eruption sea level fluctuations induced by plate collision and climate warming and retreat of the neo tethys during the biozones cf4 and cf2 when vigorous deccan outbursts occurred p elegans developed diverse morphogroups and acquired small size tests to cope with the changed environments and possibly to increase its chances of avoiding by microspherule missiles

soil development on moraines of mendenhall glacier southeast alaska 1 the moraines and soil morphology abstract soils on a sequence of well drained neoglacial moraines up to 240 years old plus an older soil were sampled to investigate soil development through the initial stages of podzolization pebbles and cobbles in the moraines are about 75 to 80 granitic rock computations based on minerals observed optically and on chemical analyses indicate that plagioclase and quartz are the predominant minerals in the fine earth the climate is perhumid leaching of the moraines may have begun before they were free of glacial ice but little organic matter accumulated under the initial vegetative cover of sparse dwarf fireweed 10 year site as alder thicket developed organic matter accumulated rapidly in oi oe and a horizons 38 year site as spruce trees began to replace alder organic matter was lost from the surface mineral soil to form an e horizon and an incipient bs horizon formed below it an oa horizon formed and the a horizon disappeared 70 and 90 year sites organic acid leaching continued to form a spodic bhs horizon in spruce forest 240 year site and a spodic bh horizon in spruce hemlock forest 240 year site hornblende has been etched slightly within 240 years apatite has been lost from e horizons and free fe presumeably in ferrihydrite has accumulated in b horizons the younger moraine soils both with and without incipient bs horizons are typic cryorthents and the 240 year old and older soils with spodic bhs and bh horizons are typic haplocryods they are expected to accumulate more organic matter and become andic humicryods which is the most common subgroup of soils in the area

shrimp u pb zircon geochronology of the late archaean ruinnaesset syenite skjoldungen alkaline province southeast greenland abstract a sample of the ruinnaesset syenite of the southeast greenland skjoldungen alkaline province contains a homogeneous population of zircons up to 1 mm diameter that are devoid of new overgrowths and old inherited cores u pb isotopic analyses of these zircons form a single population with weighted mean 207 pb 206 pb and 206 pb 238 u ages of 2699 4 ma and 2690 20 ma 2 respectively these dates are interpreted as giving the time of crystallisation of the syenite

soil development on moraines of mendenhall glacier southeast alaska 2 chemical transformations and soil micromorphology abstract soils on holocene age moraines of the mendenhall glacier in southeast alaska range from morphologically undeveloped to soils having field identified spodic horizons that are more strongly expressed with increasing soil age a soil chronosequence was sampled to study development of spodic features and to compare the expression of these features with chemical and micromorphological properties organic c accumulates rapidly in these soils with o horizons forming within 38 yr organic c is highly correlated with cation exchange capacity r2 0 92 variable charge r2 0 94 extractable acidity r2 0 83 and 1500 kpa water retention r2 0 97 the ph of the 10 yr old pedon is acidic with a soil ph h20 ranging from 5 0 to 6 4 the ph decreases with soil age with the lowest ph in horizons at the organic mineral contact increases in dithionite citrate sodium pyrophosphate and acid oxalate extractable fe feo are most evident in the 240 yr old soil depth trends for these measured properties within pedons are most distinctive for fe which increases from surface mineral horizons a or e to underlying horizons in all pedons the feo fed ratio increases with soil age in b horizons and in pedons 70 yr this ratio ranges from 0 3 to 0 5 in the e horizons and from 0 4 to 0 83 in b horizons immediately below these data indicate a greater proportion of poorly crystalline fe in illuvial horizons with increasing soil age allophane content is low 240 yr old pedon this chronosequence study indicates that spodic development is achieved within a relatively short period of time in soils of this region

quantitative geochemical approach to pedogenesis importance of parent material reduction volumetric expansion and eolian influx in lateritization abstract using mass balance techniques we test the prevalent view that laterite genesis is dominated by in situ residual enrichment during chemical weathering of bedrock through calculation of net mass fluxes through the laterite soils in mali west africa we show that residual enrichment by removal of mobile elements with a corresponding increase in bulk porosity and decrease in bulk density contributes only a very minor fraction of the enrichment of al fe si and au instead we demonstrate that the abundance of these elements is due to the influx and accumulation by selective retention of chemically mature detritus of local and foreign origin clearly evident in micromorphological infilling features at the same sample depths that accumulation reaches extreme values we show that volumetric expansion in excess of 200 has occurred locally we infer that these spatially coincidental zones of mass influx of rock forming metals fe al si and also au with dilational hyperstrains result from a mutually reinforcing mechanical interaction between material influx and the effects of subsurface deformational processes such as shrink swell cycles and root growth and decay we propose that with progressive infilling of available connected voids by illuvial microsedimentary deposits of insoluble resistate and neoformed minerals the capacity for the combined skeleton and plasma to remain isovulumetric is exceeded we speculate that the resultant space problem is relieved by upwards expansion towards the overlying free surface continued translocation and void infilling occur and are limited to the depth where the size of translocational particles is smaller than that of the connected voids consequently progressive hyperstrains accumulate above this critical depth by the long term influence of a proposed translocational wedge of chemically resistant minerals against which numerous generations of plant roots have exerted stresses eclectic surficial contaminants involved are continuously derived from above leaving no indication of a relict source region within the present soil profile from which they might have been extracted instead the source region is largely the existing regolith column itself which releases local material and in addition is supplemented by deposition of colluvial detritus shed nearby by escarpment retreat

paleoproductivity from benthic foraminifera abundance glacial to postglacial change in the west equatorial pacific surface productivity is correlated with the rate of accumulation of benthic foraminifera on the deep sea floor as a rule of thumb for each 1 mg of organic carbon arriving at the sea floor one benthic foram shell 150 m is deposited the correlation can be used to reconstruct organic flux to the sea floor in the past and hence the productivity of past oceans applying the appropriate equations to box core data from the ontong java plateau in the western equatorial pacific we found that productivity during the last glacial maximum exceeded present productivity by a factor of between 1 5 and 2 0 with intermediate values for the mid transition period accumulation of benthic foraminifera was depressed on top of the plateau during the glacial and transitional period presumably because increased winnowing removed part of the food supply

chemical composition of thalassinoides boxwork across the marine k pg boundary of central new jersey u s a thalassinoides isp burrow networks filled with green to dark bluish gray glauconite pellets occur in the cretaceous to paleogene hornerstown formation and in the uppermost 1 2 m of the underlying upper cretaceous navesink and new egypt formations at many central new jersey cretaceous paleogene k pg boundary sections near the base of the hornerstown formation is a renowned bonebed the main fossiliferous layer mfl which contains isolated to articulated cretaceous marine reptiles turtles birds and crocodiles interpreted as a thanatocoenosis we investigated the bulk chemical composition of the burrow fill and surrounding matrix in the largely unconsolidated sections of the k pg interval at two sites inversand and walnridge meirs farm new jersey using a niton xl3t xrf analyzer to place them in proper stratigraphic context bulk matrix zr and ti concentrations decrease up section as a result of transgression deepening and increased distance from source areas in contrast an increase in k is attributed to greater amounts and maturity of the glauconite due to decreasing sedimentation rates zr and ti concentrations in burrow fills below the mfl are virtually the same as in overlying sediments above the mfl and much less than in the surrounding matrix this suggests that burrows in the cretaceous strata were passively filled with paleogene sediments k concentrations of burrow fills are generally intermediate between the high values encountered in the paleogene matrix and the lower values of the cretaceous matrix although this may have resulted from removal of glauconite during bioturbation and burrow filling it is more likely that immature glauconite was sequestered in the burrow fills below the depth of glauconitization before it could attain full maturity therefore burrows originating above the formational contact at or above the mfl penetrate as much as two meters into underlying cretaceous sediments and are passively filled with paleogene sediment burrows originating above the mfl may translocate diagnostic danian microfossils shocked quartz and ir effectively diffusing the k pg boundary this research demonstrates that care must be taken in sampling pervasively bioturbated strata to avoid incorporating stratigraphically younger burrow fill sediments

lilliput effect in late maastrichtian planktic foraminifera response to environmental stress the lilliput effect marks morphologic and intraspecies size reductions in response to environmental stresses commonly associated with the aftermath of mass extinctions this study shows that the lilliput effect is a universal biotic response associated with greenhouse warming mesotrophic or restricted basins shallow marginal settings and volcanically active regions during the late maastrichtian sedimentary sequences analyzed from tunisia egypt texas argentina the south atlantic and indian ocean reveal that the biotic stress response appears uniform regardless of the cause varying only with the degree of biotic stress overall late maastrichtian environments span a continuum from optimum conditions to the catastrophic mass extinctions with a predictable set of biotic responses relative to the degree of stress induced by oxygen salinity temperature and nutrient variations as a result of climate and sea level changes and volcanism early stages of biotic stress result in diversity reduction and the elimination of large specialized species k strategists leading to morphologic size reduction via selective extinction disappearances and intraspecies dwarfing of survivors later stages of biotic stress result in the complete disappearance of k strategists intraspecies dwarfing of r strategists and dominance by low oxygen tolerant small heterohelicids at the extreme end of the biotic response are volcanically influenced environments which cause the same detrimental biotic effects as observed in the aftermath of the k t mass extinction including the disappearance of most species and blooms of the disaster opportunist guembelitria

zircon ages and geochemistry of late neoarchean syenogranites in the north china craton a review abstract at the end of the neoarchean continental evolution voluminous syenogranites were emplaced in the north china craton together with other magmatic rocks trondhjemite tonalite granodiorite ttg monzogranite diorite gabbro syenogranites are widely distributed in anshan benxi qinhuangdao and western shandong and also occur in southern jilin northern liaoning northwestern hebei and central henan based on geological relationships degree of metamorphism deformation and magmatic zircon ages two phases of syenogranite magmatism are recognized rocks produced during the first phase show a gneissic texture and were formed between 2 53 and 2 52 ga and locally comprise abundant ttg rocks of the second phase cut late neoarchean ttg and supracrustal rocks display a massive structure and mainly formed between 2 52 and 2 50 ga all syenogranites share the same features in major element compositions being high in sio2 and low in cao total feo mgo tio2 and p2o5 however they are different in trace and ree compositions and can be subdivided into three types 1 type 1 shows a large variation in total ree contents low la yb n ratios strong negative eu eu anomalies and ba depletion 2 type 2 is similar to type 1 but has higher la yb n ratios 3 type 3 shows a large variation in total ree and la yb n ratios and significantly do not show strongly negative eu eu anomalies and ba depletion whole rock sm nd isotopic compositions show large variations in nd t values and tdm nd modal ages ranging from 9 49 to 4 72 and 3 70 to 3 25 ga type 1 0 55 1 03 and 2 77 2 71 ga type 2 and 2 35 to 1 23 and 2 93 2 66 ga type 3 respectively hf isotopic compositions of zircons from three samples have hf t values and tdm1 hf ages of 0 7 7 2 and 2 84 2 56 ga type 1 2 6 7 4 and 2 74 2 56 ga type 2 and 2 1 6 3 and 2 76 2 60 ga type 3 it is concluded that syenogranites were generated by melting of continental crust with different mean crustal residence ages and most of them were emplaced during the second phase 2 52 2 50 ga in an extensional tectonic regime the formation of these voluminous syenogranites marks a tectono magmatic event resulting in stabilization of the north china craton at the end of the neoarchean

low temperature thermochronology of the southern east greenland continental margin evidence from apatite u th he and fission track analysis and implications for intermethod calibration abstract the southern coast of east greenland is characterized by high topographic relief and deep fjords but the evolution of the landscape and the low temperature thermochronology of the region is not well understood here we present apatite fission track and u th he ages that suggest several important features of the long term geomorphic history of this region but which also illustrate an important discrepancy in the thermal histories derived from each technique apatite from bedrock of the southern coast of east greenland between 62 n and 67 n has fission track ages ranging from 60 to 840 ma and u th he ages ranging from 21 to 250 ma the ages generally increase with elevation and distance from the coast and fission track analyses show significant differences in thermal histories for the different regions in the kangertittivatsiaq area c 66 67 n apatite fission track data and models suggest two separate periods of slow cooling prior to c 200 ma and between c 160 ma and the late cenozoic more recently than c 20 ma each of which was followed by a period of rapid cooling and inferred exhumation apatite he data in the kangertittivatsiaq region including crystal size age correlations in low elevation samples are most simply interpreted as recording an incision event of at least 1 5 km later than 20 ma near the coast this may have been caused by glacial erosion the u th he data also indicate an earlier phase of rapid exhumation at c 250 ma in the skjoldungen kap mosting area c 62 64 n approximately 200 km south of the kangertittivatsiaq apatite fission track data suggest slow exhumation from c 200 ma into the neogene followed by fast exhumation the similarity of fission track ages 200 ma at sea level in the fjords in the skjoldungen area c 62 64 n do not suggest tilting in the hinterland related to the breakup of the east greenland continental margin furthermore the cenozoic fission track ages and modeling fission track data suggest that pre breakup basins may have covered the outer coast despite the broadly similar topographic implications of the fission track and u th he data the thermal histories derived from these systems are inconsistent fission track data require thermal histories that predict he ages younger than observed and he data require thermal histories that predict fission track ages older than observed similar discrepancies have also been observed in other settings characterized by long term low temperature thermal histories and may reflect changes in annealing or diffusion behavior or both that either develop or become more apparent in such cases

evolutionary dynamics of the permian triassic foraminifer size evidence for lilliput effect in the end permian mass extinction and its aftermath abstract there is growing evidence of the lilliput effect in the end permian mass extinction and its aftermath however very little has been published on assessing the lilliput effect on protozoans in the early triassic based on quantitative analysis of a great quantity of samples from outcrop sections this study investigates foraminiferal test size variations through the changhsingian to the olenekian based on fossil records from three outcrop sections in south china the sharp reduction in foraminifer sizes coincides with the first or main episode of the end permian mass extinction foraminifers remained small in sizes in the early induan their body sizes increased slowly in the late induan to olenekian but never recovered to the pre extinction test size levels the lilliput effect on foraminifera in the aftermath of the end permian crisis is indicated by the extinction of large taxa decrease in size for surviving taxa and rise of small sized new forms physiological reactions of various foraminifer groups reveal that several defaunation events such as anoxia ocean acidification and global warming that prevailed through the permian triassic interval may be responsible for both the end permian crisis and the lilliput effect

soil production in heath and forest blue mountains australia influence of lithology and palaeoclimate an erratum has been published for this article in earth surfaces processes and landforms 25 13 2005 1683 1686 recent determinations of soil production from in situ cosmogenic nuclides indicate that production decreases exponentially with soil depth this contrasts with a long held assumption that maximum soil production occurs under a soil cover of finite depth sites in the blue mountains australia show a sharp decrease of soil depth where vegetation changes from forested plateau surfaces to heath covered spurs and bands of bare rock in the heath suggest that soil production depends on presence of a finite depth of soil the substrate varies from hard ferruginized sandstone to soft saprolite in situ 10be determinations indicate that apparent rates of erosion and soil production are greater under the relatively thin heath soil than under the thicker forest soil but in contrast to other studies these sites do not show significant depth dependence of apparent soil production the pattern reflects both hardness variation in the rock substrate and the effect of late quaternary climatic change optically stimulated luminescence osl dating indicates that soil 30 cm depth is of holocene age whereas the deeper soil is substantially older the age break coincides with a stone line interpreted as a former surface lag deposit assuming that pre holocene soil depths were 30 cm less than today recalculated soil production tends to decrease with increasing depth soil production at this site requires soil cover but bare rock patches and vegetation comprise a shifting mosaic in the long term average rates of erosion and soil production decrease with increasing soil depth copyright 2005 john wiley sons ltd

timing of late archaean terrane assembly crustal thickening and granite emplacement in the nuuk region southern west greenland abstract a breakthrough in understanding the structural and metamorphic evolution of archaean gneiss complexes occurred with the recognition that the nuuk region of southern west greenland comprised separate terranes assembled in the late archaean from northwest to southeast these are the akia 3220 2970 ma akulleq 3870 3600 and 2820 ma and tasiusarsuaq 2920 2860 ma terranes the minimum time of assembly is recorded by the first event common to all component terranes using shrimp u pb zircon geochronology the oldest events common to all terranes including emplacement of crustally derived granites contemporaneous metamorphism and anatexis have been dated at 2710 2725 ma in the akulleq terrane areas where in situ diatexite formed abundant granitoid sheets were intruded and common growth of metamorphic zircon mostly low th u in most lithologies occurred in the akia and tasiusarsuaq terranes there was only intrusion of a lesser number of 2720 ma granitoid sheets because metamorphic zircons of that age have not been found the 2720 ma event is interpreted as marking or shortly following terrane assembly when the diverse components of the akulleq terrane were tectonically juxtaposed with the other two this new documentation of metamorphic and associated igneous events within an accreting cratonic region is an illustration that the stabilisation of extensive areas of archaean gneisses can be due to accretionary tectonics long after the individual components were first formed

the stratigraphic status of the anthropocene the term anthropocene was coined to describe the present geological epoch in which human activity dominates many of the processes acting on the surface of the earth the expression has been widely adopted but remains informal and lacks precise definition there have been several attempts to establish formal stratigraphic markers to define the start of the anthropocene most recently certini and scalenghe certini g and scalenghe r 2011 anthropogenic soils are the golden spikes for the anthropocene the holocene 21 1269 1274 have argued that the best markers are anthropogenic soils and that these may be used to identify the base of the anthropocene in stratigraphic sequences unfortunately soils fail to meet many of the criteria required for the establishment of stratigraphic golden spikes their preservation potential is poor many stratigraphically important environments do not experience pedogenesis and anthrosols do not always provide the stratigraphically lowest marker of human impact in ad

clade dependent size response of conodonts to environmental changes during the late smithian extinction abstract in contrast to the benthos whose taxonomic recovery was lagging way behind that of the nekton highly diverse smithian conodont and ammonoid faunas were profoundly decimated during the late smithian ca 2 myr after the permian triassic boundary mass extinction as body size reduction is a common evolutionary response to heavy environmental stress we investigate how the size of the p1 elements of different conodont clades responded during the late smithian crisis based on three sections from the northern indian margin a major and world wide positive carbon excursion is also a consistent signature of the late smithian time interval where adequate ammonoid biochronological control is lacking i e kashmir a new carbonate carbon isotope record provides an independent age proxy for correlations with southern tibet and the salt range assuming a positive correlation between the size of p1 elements and body size we confirm that segminate conodonts underwent a size decrease during the late smithian however segminiplanate conodonts consistently displayed a substantial size increase during the same time interval thus highlighting clade specific diverging answers and precluding any simplistic generalization of size responses to the same stress event additionally a moderate but consistent size increase during the early spathian is documented for both clades thus obscuring any simple general relation between temperature stress and size among conodonts comparison of size time series with the oxygen isotopic composition of conodonts a proxy for sea water temperature suggests that only the size of segminate p1 elements may correlate positively with temperature although at a slower pace the size of segminiplanate p1 elements continued to increase during the early spathian when temperature rose again after the late smithian cooling event therefore temperature alone cannot explain the size variations of segminiplanate conodonts the late smithian was also a time of increasing burial of organic matter on continental shelves but lateral variations of this factor also obscure any relation with the documented size changes last but not least the stratigraphically more comprehensive study in nammal reveals a segminiplanate gap during the middle smithian thermal high the biogeographical expansion of this clade towards the low latitudes during the griesbachian the early smithian the late smithian and the early spathian apparently occurred during the coolest intervals of the early triassic in agreement with their supposed cooler habitat

the evolution of the east greenland margin as revealed from fission track studies abstract a comprehensive dataset of fission track analyses mainly of apatite covers the east greenland margin between ca 73 n geographical society island and ca 63 n skjoldungen it consists of data from archaean and caledonian basement post caledonian sedimentary rocks and magmatic rocks the studied areas represent different aspects of the east greenland evolution we report new apatite fission track ft analyses from the east greenland gneissic basement south of scoresby sund to skjoldungen and put them into context with existing data a regional pattern along the east greenland continental margin south of 73 n of deeply eroded shorelines and highstanding slowly eroding hinterland with remnants of old peneplain surfaces is overprinted in the central kangerlussuaq area by tertiary magmatic activity to the northeast the thermal evolution is dominated by a domal structure shown by apatite fission track ft ages to have cooled in the neogene this pattern may result from rapid erosion of the locally uplifted basaltic pile in the area and heating caused by late sill intrusions possibly enhanced on a regional scale by climatic deterioration in the hinterland to the south and west of kangerlussuaq the data restrict the basalt cover to

a conodont based revision of the 87 sr 86 sr seawater curve across the permian triassic boundary abstract based on analyses of 565 conodonts from meishan liangfengya and daijiagou south china and abadeh central iran we propose a revision of the seawater 87 sr 86 sr curve for the time period spanning 200 kyr prior to the permian triassic boundary ptb to 330 kyr after the ptb with carefully designed sample cleaning conodonts faithfully record seawater 87 sr 86 sr seawater 87 sr 86 sr was 0 707030 10 200 kyr prior to the ptb rose to 0 707070 10 approximately 39 kyr prior to the ptb at the marine extinction horizon the top of bed 24e at meishan to 0 707080 10 at the ptb and to 0 707120 20 at 330 kyr after the ptb the rate of change of seawater 87 sr 86 sr was 0 0000185 myr from the capitanian minimum to 100 kyr before the ptb and was 0 00020 7 5 myr between 100 kyr before and 330 kyr after the ptb over 6 myr this rate of change would result in a maximum 87 sr 86 sr of 0 70825 at the end of the early triassic compared with a model value of 0 7080 the sr data are consistent with the interpretation that the rise in marine 87 sr 86 sr was due primarily to an increase in the continental weathering and erosional flux and that soil binding vegetation was not re established during most of the early triassic the rapid rise in seawater 87 sr 86 sr began at least 30 kyr prior to the marine extinction at meishan indicating that the terrestrial extinction preceded that in the oceans

ferrolysis induced soil transformation by natural drainage in vertisols of sub humid south india in sub humid south india recent studies have shown that black soil areas vertisols and vertic intergrades located on flat valley bottoms have been rejuvenated through the incision of streambeds inducing changes in the pedoclimate and soil transformation joint pedological geochemical and geophysical investigations were performed in order to better understand the ongoing processes and their contribution to the chemistry of local rivers the seasonal rainfall causes cycles of oxidation and reduction in a perched watertable at the base of the black soil while the reduced solutions are exported through a loamy sand network this framework favours a ferrolysis process which causes low base saturation and protonation of clay leading to the weathering of 2 1 then 1 1 clay minerals maximum weathering conditions occur at the very end of the wet season just before disappearance of the perched watertable therefore the by products of soil transformation are partially drained off and calcareous nodules then further downslope amorphous silica precipitate upon soil dehydration the ferrolysed area is fringing the drainage system indicating that its development has been induced by the streambed incision the distribution of c 14 ages of caco3 nodules suggests that the ferrolysis process started during the late holocene only about 2 kyr b p at the studied site and about 5 kyr b p at the watershed outlet the results of this study are applied to an assessment of the physical erosion rate 4 8x10 3 m kyr since the recent reactivation of the erosion process c 2010 elsevier b v all rights reserved

causes and consequences of extreme permo triassic warming to globally equable climate and relation to the permo triassic extinction and recovery permian waning of the low latitude alleghenian variscan hercynian orogenesis led to a long collisional orogeny gap that cut down the availability of chemically weatherable fresh silicate rock resulting in a high co2 atmosphere and global warming the correspondingly reduced delivery of nutrients to the biosphere caused further increases in co2 and warming melting of polar ice curtailed sinking of o2 and nutrient rich cold brines while pole to equator thermal gradients weakened wind shear and associated wind driven upwelling lessened further diminishing productivity and carbon burial as the earth warmed dry climates expanded to mid latitudes causing latitudinal expansion of the ferrel circulation cell at the expense of the polar cell increased coastal evaporation generated o2 and nutrient deficient warm saline bottom water wsbw and delivered it to a weakly circulating deep ocean warm deep currents delivered ever more heat to high latitudes until polar sinking of cold water was replaced by upwelling wsbw with the loss of polar sinking the ocean was rapidly filled with wsbw that became increasingly anoxic and finally euxinic by the end of the permian rapid incursion of wsbw could have produced 20 m of thermal expansion of the oceans generating the well documented marine transgression that flooded embayments in dry hot pangaean mid latitudes the flooding further increased wsbw production and anoxia and brought that anoxic water onto the shelves release of co2 from the siberian traps and methane from clathrates below the warming ocean bottom sharply enhanced the already strong greenhouse increasingly frequent and powerful cyclonic storms mined upwelling high latitude heat and released it to the atmosphere that heat trapped by overlying clouds of its own making suggests complete breakdown of the dry polar cell resulting rapid and intense polar warming caused or contributed to extinction of the remaining latest permian coal forests that could not migrate any farther poleward because of light limitations loss of water stored by the forests led to aquifer drainage adding another 5 m to the transgression non peat forming vegetation survived at the newly moist poles climate feedback from the coal forest extinction further intensified warmth contributing to delayed biotic recovery that generally did not begin until mid triassic but appears to have resumed first at high latitudes late in the early triassic current quantitative models fail to generate high latitude warmth and so do not produce the chain of events we outline in this paper future quantitative modeling addressing factors such as polar cloudiness increased poleward heat transport by deep water and its upwelling by cyclonic storms and sustainable mid latitude sinking of warm brines to promote anoxia warming and thermal expansion of deep water may more closely simulate conditions indicated by geological and paleontological data

bivalve pavements from shallow water black shales in the early jurassic of northern italy a record of salinity and oxygen depleted environmental dynamics abstract thin shelled bivalve pavements which constitute the eomiodon horizon occur in a distinctive black shale unit in the lowermost part of a lower jurassic carbonate platform sedimentary system of the southern alps italy the eomiodon horizon is characterised by laminated mudstone and fissile dark grey and black organic rich marlstone and claystone yielding abundant bivalve pavements with monotypic to paucispecific assemblages dominated by eomiodon an opportunistic brackish shallow infaunal veneroid bivalve litho and biofacies indicate environmental conditions ranging from nearshore euhaline waters to oxygen depleted brackish lagoon with a high input of terrestrial organic matter culminating in marsh and terrestrial conditions these pavements were analysed using a microstratigraphic approach while considering their taxonomic composition the geometry of the beds their biofabric criteria size sorting abundance fragmentation orientation and disarticulation origin and time averaging these characteristics led to reconstruction of the following palaeoenvironmental dynamics 1 the event concentrations represented by mass mortality of stunted and juvenile individuals caused by anoxia are indicative of deeper and predominantly stagnant parts of the lagoon 2 an increase in shell sizes higher growth rate and a decrease in size sorting and winnowing illustrate higher and more continuous bottom oxygenation and enhanced life in oxygen fluctuated environmental conditions 3 poorly sorted highly fragmented and bioturbated bivalve accumulations indicate the eomiodon habitat here large sized eomiodon specimens record a decrease in water depth and sedimentation rate and almost constantly oxygenated bottom conditions 4 the appearance of byssally attached bivalves lithioperna marks the transition from the muddy soupy substrate of the eomiodon habitat to firm hard bottom conditions this new substrate allowed the settlement of lithioperna a byssate isognomonid which records a shallower and landward marsh setting the eomiodon horizon testifies to a short term warm humid climatic phase and yielded lithioperna the first genus of the lower jurassic lithiotis fauna to appear in southern alps this fauna is composed of large and aberrant bivalves which are spread throughout the lower jurassic tethyan and tropical panthalassian carbonate platforms as a result the eomiodon horizon and its salinity and oxygen depleted environmental setting represent a possible progenitor incubator for the lithiotis fauna

the influence of soil age and regional climate on clay mineralogy and cation exchange capacity of moist tropical soils a case study from late quaternary chronosequences in costa rica abstract tropical soils exhibit large differences across landscapes in many attributes notably clay mineralogy 2 1 vs 1 1 clays bulk geochemistry ca al ph cation exchange capacity cec organic matter and soil texture in order to examine the factors controlling these variables a series of three chronosequences 120 ka of tropical soils on uplifted terraces along the pacific coast of costa rica were studied the three study locations differ mainly as a function of soil moisture and leaching with conditions ranging from 2700 mm yr mean annual precipitation map on the southern nicoya peninsula 4 month dry season to 3200 mm yr in the esterillos region 3 month dry season and 4250 mm yr on the osa peninsula no dry season analytical methods include x ray diffraction xrd transmission analytical electron microscopy tem aem inductively coupled plasma optical emission and mass spectrometry icp oes icp ms ammonium acetate extraction 1 m nh4oac ph 7 for cec and c n analysis soil weathering reactions and related decrease in cec occur three to four times faster in a sequence of inceptisol to oxisol soils in the wettest climate osa compared to the less moist esterillos area in the even drier monsoon climate soils nicoya this evolved low cec the age related evolution of tropical soils appears to be a predictable sequence in lowland tropical landscapes where periodic tectonism erosion or volcanism produces unweathered parent material at the land surface empirical data from this project enables the extrapolation of simple equations applicable to tropical volcanic arc landscapes where presence of uplifted marine terrace soils facilitates determination of soil age the two variables controlling soil composition can be combined into an effective age ageeff that takes into account soil age and weathering intensity factoring in map and wet dry months from climate data and equations are of the form e g ecec 18 1 ln ageeff 77 with r2 values of 0 75 to 0 87 greatest scatter occurs in the youngest soils given the apparent prevalence of this sequence and the systematic nature of its reaction progression these results could be useful for modeling tropical soils

planktonic foraminiferal turnover diversity fluctuations and geochemical signals across the eocene oligocene boundary in tanzania a major turnover in planktonic foraminifera occurred across the eocene oligocene e o boundary new drill holes through the e o boundary in southern tanzania contain extremely well preserved and diverse assemblages of planktonic foraminifera here we document a 1 2 million year record of assemblages diversity and stable isotope fluctuations through this critical interval which is often dissolved and or recrystallised in carbonate rich facies the e o boundary is marked by the abrupt extinction of all five remaining species of the family hantkeninidae and a distinct size reduction in the genus pseudohastigerina the boundary is preceded over a short stratigraphic interval by the extinction of turborotalia cerroazulensis turborotalia cocoaensis and turborotalia cunialensis quantitative analysis of planktonic foraminiferal assemblages reveals significant changes in the abundance of certain species and the composition of the assemblages we compare diversity fluctuations to the stable isotope record of pseudohastigerina naguewichiensis and use multispecies stable isotope analyses to determine the life habitats of the most important species a major shift in the evenness occurs at 33 8 ma associated with the extinction of the t cerroazulensis group suggesting acute ecological disturbance we propose that the extinction of the t cerroazulensis group at 33 8 ma was directly related to cooling of sea surface temperatures while the extinction of hantkeninidae was due to modifications in the thermal structure of the oceans and associated productivity changes after the extinctions renewed origination and diversification occurred leading to a characteristic oligocene planktonic foraminifer assemblage

structure of the palaeoproterozoic nagssugtoqidian orogen south east greenland model for the tectonic evolution abstract the palaeoproterozoic nagssugtoqidian orogen extends over 250 km along the east coast of greenland around the settlement of tasiilaq the orogen includes archaean rocks from the adjoining rae craton to the north and the north atlantic craton to the south and palaeoproterozoic rocks the rae craton consists of orthogneiss and amphibolite included in the schweizerland and kuummiut terranes and is tectonically overlain in the kuummiut terrane by ca 2100 2200 ma units that include marble meta pelite and psammite and amphibolite assigned to the helheim and kuummiut units the kuummiut terrane was probably subducted underneath the se trending ca 1885 ma ammassalik intrusive complex which has a high temperature metamorphic halo and is characterised by a change from sinistral faulting to pure shear deformation the southern isortoq terrane consists of medium pressure amphibolite facies bimodal meta volcanic and the rocks of the kuummiut terrane were tectonically imbricated in ene verging structures during ca 1870 ma high pressure metamorphism this was followed by ne sw convergence and close to orthogonal extrusion in the weakened crust which is characterised by partial melting during decompression the rocks of the isortoq terrane were imbricated in a se vergent thrust and ramp system either during oblique subduction of the kuummiut terrane or an earlier tectonic stage elsewhere ne sw compression as in the northern terranes formed sw vergent thrust systems and folds this was most likely caused by a change in the regional stress field during collision between ca 1870 and 1820 ma in the north the schweizerland terrane was juxtaposed to the kuummiut terrane in southeasterly direction causing refolding of earlier structures in the lower amphibolite facies this hinteland type of deformation was possibly related to tectonism in western greenland the latest recognised deformation event was during ca 1740 1680 ma associated with ne sw extension which is interpreted as orogenic collapse the complex structural evolution of the orogen was caused by oblique convergence during wsw directed subduction the convergence of irregularly shaped cratons and the change of the regional stress field from ene wsw to nw se during progressive collisional tectonics between the two archaean cratons

early triassic gulliver gastropods spatio temporal distribution and significance for biotic recovery after the end permian mass extinction a reduction in body size lilliput effect has been repeatedly proposed for many marine organisms in the aftermath of the permian triassic pt mass extinction specifically reduced maximum sizes of benthic marine invertebrates have been proposed for the entire early triassic this concept was originally based on observations on early triassic gastropods from the western usa basin and the dolomites n italy and it stimulated subsequent studies on other taxonomic groups however only a few studies have tested the validity of the lilliput effect in gastropods to determine whether the paucity of large sized gastropods is a genuine signal or the result of a poor fossil record and insufficient sampling in combination with a review of the literature we document numerous new abundant large sized gastropods from the griesbachian outcrops of greenland and from the smithian early spathian interval in the southwestern usa we show that large sized gulliver gastropods i were present soon after the pt mass extinction ii occurred in various basins sedimentary facies and environmental contexts from shallow to deeper settings and iii belong to diverse higher rank taxa focusing on the western usa basin we investigate areas from which microgastropod shell beds were previously presented as being typical however we show that gulliver gastropods do occur in the very same areas insufficient sampling effort is probably the main reason for the rarity of reports of large early triassic gastropods which is supported by preliminary rarefaction based simulations finally it appears that the recently documented middle to late smithian climate shifts and the severe end smithian extinction of nekto pelagic faunas did not reduce maximum shell sizes of gastropods