reconstruction of northeast asian deformation integrated with western pacific plate subduction since 200 ma abstract the configuration and kinematics of continental deformation and its marginal plate tectonics on the earth s surface are intrinsic manifestations of plate mantle coupling the complex interactions of plate boundary forces result in plate motions that are dominated by slab pull and ridge push forces and the effects of mantle drag these interactions also result in continental deformation with a complex basin mountain architecture and evolution the kinematics and evolution of the western pacific subduction and northeast asian continental margin deformation represent a first order tectonic process whose nature and chronology remains controversial this paper implements a deep time reconstruction of the western pacific subduction continental accretion or collision and basin mountain deformation in northeast asia since 200 ma based on a newly revised global plate model we use gplates software to examine strain recovery geological and seismic tomography constraints for the western pacific plate subduction and sequentially backward rotations of deforming features the results indicate a nw se oriented shortening from 200 to 137 ma a nww see oriented extension from 136 to 101 ma a nearly n s oriented extension and uplift with a short term nww see oriented compressional inversion in northeast china from 100 to 67 ma and a nw se and nearly n s oriented extension from 66 ma to the present day the western pacific oceanic plate subducted forward under east asia along mudanjiang honshu island during the jurassic and the trenches retreated to the sikhote alin north shimanto and south shimanto zones from ca 137 128 ma ca 130 90 ma and in ca 60 ma respectively our time dependent analysis of plate motion and continental deformation coupling suggests that the multi plate convergent motion and ocean continent convergent orogeny were induced by advance subduction during the jurassic and earliest cretaceous our analysis also indicates that intra continent rifting and back arc extension were triggered by trench retreat during the cretaceous and that the subduction of the oceanic ridge and arc were triggered by trench retreat during the cenozoic therefore reconstructing the history of plate motion and subduction and tracing the geological and deformation records in continents play a significant role in revealing the effects of complex plate motions and the interactions of plate boundary forces on plate mantle coupling and plate motion intracontinental deformation coupling

40ar 39ar age constraints on cretaceous fossil bearing formations near the china north korea border abstract abundant mesozoic terrestrial plant fish and invertebrate fossils have been discovered from the lishugou formation and the underlying xiaolin formation in the eastern liaoning province of ne china since the 1970s these discoveries have great potential for substantially increasing our knowledge on the evolution of paleoecosystems and paleoenvironments in east asia however previous geological and geochronological studies for these fossil bearing formations are rare because the fossil outcrops are near the border between china and north korea here we present robust 40ar 39ar ages of 99 9 0 4 ma for one sample from the lishugou formation and 109 1 0 2 ma and 122 4 0 2 ma for two samples from the upper and lower parts of the xiaolin formation from dandong city liaoning china our new age data indicate that the lishugou and xiaolin formations were deposited contemporaneously with the jiufotang formation from the classic jehol outcrops in western liaoning therefore our results provide an accurate age calibration for the fossils discovered from the liaodong peninsula and suggest that the hypothesis of the jehol migration should be reappraised

chemical stability of the atmosphere and ocean abstract the earth system processes most of the chemical components of its atmosphere and oceans in geologically short periods of time it does this in a regulated way one that maintains a remarkably constant surface environment this we know primarily from the fossil record of uninterrupted complex life on earth that extends over the last billion years we are only beginning to understand the feedbacks that control the chemistry of the oceans and atmosphere numerical models of biogeochemical cycles are most stable when there is feedback between the amount of a chemical component in the ocean or atmosphere and its transfer to or from that reservoir coupling of subsystem especially of those operating on different time scales enhances stability an example of the role of feedback in stabilizing earth s chemical environment is the mechanism of control of atmospheric oxygen there appears to be no strong relationship between oxygen level and oxygen consumption however oxygen production may be a function of oxygen level the burial rate of organic carbon oxygen production in marine sediments may be sensitive to bottom water oxygenation levels also combustion may be an effective mechanism of transferring nutrients namely phosphorus from efficient terrestrial ecosystems to less efficient marine ecosystems when o2 rises fires become more frequent and p is transferred to the ocean stimulating marine organic carbon burial but depressing global burial rates global o2 production rates decline as does the o2 level a negative feedback models of ocean chemical composition are presently incapable of reproducingthe temporal constancy indiated by geological observations these models do not incorporate ion exchange equilibria as important processes in marine geochemical cycles when included these equilibria significantly damp the fluctuations in ion ratios calculated by the extant models

clay mineral evolution changes in the mechanisms of formation and global distribution of phyllosilicate clay minerals through 4 567 ga of planetary evolution in our solar system reflect evolving tectonic geochemical and biological processes clay minerals were absent prior to planetesimal formation 4 6 billion years ago but today are abundant in all near surface earth environments new clay mineral species and modes of clay mineral paragenesis occurred as a consequence of major events in earth s evolution notably the formation of a mafic crust and oceans the emergence of granite rooted continents the initiation of plate tectonics and subduction the great oxidation event and the rise of the terrestrial biosphere the changing character of clay minerals through time is thus an important part of earth s mineralogical history and exemplifies the principles of mineral evolution

deep fluids can facilitate rupture of slow moving giant landslides as a result of stress transfer and frictional weakening landslides accommodate slow aseismic slip and fast seismic rupture which are sensitive to fluid pressures and rock frictional properties the study of strain partitioning in the sechilienne landslide france provides a unique insight into this sensitivity here we show with hydromechanical modeling that a significant part of the observed landslide motions and associated seismicity may be caused by poroelastic strain below the landslide induced by groundwater table variations in the unstable volume near the surface calculated strain and rupture may be controlled by stress transfer and friction weakening above the phreatic zone and reproduce well high motion zone characteristics measured by geodesy and geophysics the key model parameters are friction weakening and the position of groundwater level which is sufficiently constrained by field data to support the physical validity of the model these results are of importance for the understanding of surface strain evolution under weak forcing

a new skeleton of ianthasaurus hardestii a primitive edaphosaur synapsida pelycosauria from the upper pennsylvanian of kansas a new specimen from the upper pennsylvanian of garnett kansas is referable to the edaphosaur ianthasaurus hardestii it is the second articulated skeleton known of this species and possesses pre

first record of seymouria vertebrata seymouriamorpha from early permian fissure fills at richards spur oklahoma isolated skeletal elements of the amphibian genus seymouria were recently discovered at the richards spur locality near fort sill oklahoma a prolific source of early permian tetrapod remains five of the seven described bones are of juvenile size and include three neural arches a humerus and a femur whereas the other two are partial vertebrae apparently adult all seven are morphologically similar to equivalent skeletal elements in seymouria specimens previously collected in europe and north america apart from features reflecting the early developmental stage of the juvenile bones the femur and humerus are clearly distinct from those of other seymouriamorphs such as ariekanerpeton and kotlassia the rarity of seymouria at the richards spur locality implies that it was not a regular component of the fauna and it is also associated with the less markedly terrestrial assemblage that consistently occurs at localities in the southwestern united states however its skeletal morphology and occurrence a

rise of angiosperms as a factor in long term climatic cooling by late cretaceous or early tertiary time the diversification and proliferation of angiosperm deciduous ecosystems resulted in higher rates of mineral weathering this increase in the global average weathering rate would have caused a decrease in atmospheric carbon dioxide and hence global cooling the magnitude of this decrease is quantitatively explored here by developing a formulation for global weathering which combines ecosystems that differ in their fractional global coverage and intrinsic rates of weathering incorporating this formulation into models specifically several previously developed global steady state models of the geochemical cycle of carbon between the atmosphere and carbonate rocks gives results that show signifi cant global cooling from the evolution of the angiosperm deciduous ecosystems this cooling may vary from a few degrees up to 10 c in this way deciduous ecosystems with high rates of mineral weathering could have contributed to the evolution during the past 100 m y of a cooler earth and thus were a factor in producing conditions that enhanced their global proliferation

collisions with ice volatile objects geological implications a qualitative treatment abstract an aperiodic collision of the earth with extra terrestrial ice volatile bodies is proposed as a mechanism to produce rapid changes in the geologic record due to the volatile nature of these bodies evidence for their impacts particularly in the ocean might be subtle and best seen as spikes in the geochemical or fossil record against normal background differing effects would result depending on the site of the major break up of the object in the atmosphere on land or in the ocean this paper focuses on the effects of adding material to the seas oceans and atmosphere the treatment is largely qualitative however mass balance calculations were used to estimate the relative mass needed to affect changes in a variety of reservoirs although actual impactors probably have a variable composition the effects of water c n and s containing objects are discussed in the atmosphere effects could include increased rain acidity increased levels of nutrients and enhanced greenhouse warming cooling oceanic effects might include increased oceanic productivity nitrogen containing objects as a result of increased chemical weathering and or greenhouse effects increased temperatures coupled with enhanced productivity could result in wider spread oceanic anoxia or altered calcite aragonite stability possible examples of such impacts from the geologic record and potential biotic effects are given

restudy of permo carboniferous synapsid edaphosaurus novomexicanus williston and case the oldest known herbivorous amniote reexamination of the holotype and the description of new material of edaphosaurus novomexicanus from the permopennsylvanian cutler formation of north central new mexico reveals that this species is the most primitive member of the edaphosaurus clade this assignment based previously upon supposed plesiomorphies of the postcrania is supported here by two primitive character states that occur in a derived form in the texan species of edaphosaurus the presence of two autapomorphies in e novomexicanus suggests that this species is probably not a morphological relict as previously supposed but may be part of a lineage that did not exhibit the level of diversification seen in its probable sister group the clade of texan edaphosaurids e boanerges e cruciger and e pogonias

effect of the advent and diversification of vascular land plants on mineral weathering through geologic time the origin of vascular land plants in the silurian and their subsequent diversification have had a major effect on mineral weathering through geologic tune the presence of vascular plants reduces the stability of soil minerals through a net export of ions from soil waters and through the release of complexing organic acids by root mycorrhizae additional factors that dictate the nature of plant induced mineral weathering are 1 the differences in nutrient dynamics between evergreen and deciduous species 2 the role of specific nutrient sinks biomass storage and secondary soil mineralization and outputs runoff etc in plant ecosystems and 3 the effect of long and short term ecosystem disturbances first order increases in overall mineral weathering probably took place in the middle paleozoic and early tertiary following the initial colonization and diversification of land plants and the radiation of deciduous angiospenns second order fluctuations would typify time intervals where paleoecosystem disturbances were maximized such as periods of climatic instability

current and historical perspectives on the completeness of the fossil record of pelycosaurian grade synapsids abstract understanding of the early evolution of tetrapods may have been influenced by the effects of geological and anthropogenic sampling biases as suggested by previous studies here we make a thorough assessment of how these and other biases affect the record of pelycosaurian grade synapsids a group of tetrapods that dominated the terrestrial realm during the late carboniferous and early permian modified versions of the character and skeletal completeness metrics are used to assess the completeness of the known specimens while a recently published supertree of basal synapsids is tested for congruence between the stratigraphic and phylogenetic hypotheses a historical analysis is also applied to the record in order to show how the biases in the study of this group over the past centuries may have influenced the current record the results show that the completeness of basal synapsid specimens shows very little variation throughout the early permian a peak in skeletal and character completeness metric values in the middle permian wordian is attributed to exceptional preservation of the mezen fauna a significant negative correlation is found between the skeletal completeness metric and a taxic diversity curve of pelycosaurs implying a tendency to name many species based on poor material the lack of correlation between the character completeness metric and diversity is attributed to the history of discovery in the group the majority of pelycosaur species were named between the 1930s and 1960s when character based assignments were secondary to size location and stratigraphy a strong correspondence between the phylogeny and stratigraphy implies a reliable phylogenetic hypothesis but the low relative completeness index score suggests that a great deal of the fossil record is missing while the relative completeness index has improved over the past century the rate of improvement has slowed in the last two decades and the slowing rate of discovery of new species suggests that the limit of what the fossil record of pelycosaurs has to offer is being approached a consistent shape of diversity curves over the past century implies that the same biases which affected the record in the past are still affecting it now this study highlights the need for sampling correction methods to be employed in studies of early synapsids

exploring the biological dimension to pedogenesis with emphasis on the ecosystems soils and landscapes of southwestern australia abstract this review collates and discusses an ever increasing body of evidence indicating that biota from across the world have contributed proactively towards engineering of specific pedogenetic events and have done so from the most primitive ecosystems of the precambrian onwards we consider particularly modern counterparts including podzols and mollisols and especially oligotrophic ecosystems of semi arid temperate australia in the latter setting outcomes generated by relevant biota include widespread development of various lateritic imprints associated with cluster root bearing species and the equally prevalent generation of highly characteristic clay platforms in the lateral root catchments of eucalypts these alongside other minor modifications of soil profiles such as formation of biopores and generation of hydrophobicity fall generally within our all embracing phytotarium concept this envisages that specific plant players and accompanying microbiota create niches in which maximal access to limiting resources of water and nutrients is mediated experimental studies of mechanisms involved in the better known of these cases are described and short and long term effects on stability of soils and diversity of natural ecosystems examined in a range of geographical situations special sections of the review deal with relationships within and between competing phytotaria of different type in past and contemporary settings and with the principal effects evident where erosive forces rejuvenate landscapes and sponsor emergence and spread of new classes of phytotaria final comments stress among other issues the need for further research on feedbacks between macro fauna and flora and the plethora of microorganisms which directly or indirectly shape a pedogenetic scenario

a numerical model for fluid injection induced seismicity at soultz sous forets abstract during fluid injection experiments at the geothermal site of soultz sous forets france more than 114 000 induced seismic events with magnitudes between 2 0 and 2 9 were detected by a local downhole monitoring network of these 35 039 events are sufficiently constrained to be located hypocenters align along a sub vertical planar structure with the apparent width being dominated by data scattering indicating that seismic activity predominantly occurs along a pre existing larger scale fault structure for this scenario we present a numerical model to simulate hydraulic overpressures and induced seismicity during hydraulic injection the numerical model is based on the physical processes of fluid pressure and stress diffusion with triggering of the induced seismicity being controlled by coulomb friction even in its simplest form of a fault zone without any structural heterogeneity the numerical model reproduces typical observations at soultz sous forets such as number and magnitude of induced events hypocenter locations including the kaiser effect occurrence of post injection seismicity and the largest magnitude event occurring several days after shut in

new information on the pectoral girdle and vertebral column in lupeosaurus reptilia pelycosauria ucla vp 1651 a new specimen from the lower permian admiral formation of archer county texas provides information on heretofore unknown portions of the postcranial skeleton of the large pelycosaur lupeosaurus presacral neural spines are elongate and have a subcircular cross section laterally directed tubercles are not present on any of the neural spines cervical vertebrae appear to have elongate neural spines and sharply keeled centra transverse processes are positioned relatively high above the bases of the centra through the length of axial column the pattern of tilting of the neural spines is similar to that in the primitive edaphosaur ianthasaurus hardestii the proximal end of the first sacral rib contributes significantly to the intervertebral articular facet usually formed by the centra the sacral ribs do not appear to fuse with one another distally the ventral clavicular plate is greatly expanded anteriorly the posterior edge of the subcoracoscapular fossa is very well defined the avail

searching for travertines calcretes and speleothems in deep time processes appearances predictions and the impact of plants common models for modern calcite precipitation in and around caves soils springs and streams involve co 2 supplied by thick high p co 2 biogenic soils which were probably thin or non existent before vascular plants indeed plant influenced chemical weathering might have caused accelerated terrestrial carbonate production from the devonian onwards however terrestrial carbonates have also been documented from the archaean proterozoic cambrian ordovician and silurian mechanisms which could have caused non marine carbonates to precipitate without organic rich soils are described and some geological events likely to have influenced non marine carbonate precipitation up to the origin of vascular plants are highlighted as organisms have evolved so have the petrographic characteristics of non marine carbonates some examples of this are also given here

pedogenesis and geochemical alteration of the picture gorge subgroup columbia river basalt oregon reddened clay rich horizons between basalt flows have historically been identified as baked zones or as zones of lateral groundwater movement the reddening has been attributed to thermal or chemical alteration of the permeable portion of the basalt flow many of these red horizons are instead paleosols that record significant hiatuses in basalt flow emplacement paleosols were identified in the field on the basis of features such as horizonation ped morphology and root traces terrestrial gastropods fossil plants and peats also occur locally plots of weathering indices such as base loss are consistent with a pedogenic origin for these horizons ca na mg fe 21 and p have been extensively lost from the a and bt horizons of the paleosols consistent with modern weathering patterns k and rb have been added to the upper portions of the profiles and lost in the lower portions of the profiles relative to the parent material with rb added disproportionately historically this pattern of enrichment has been cited as evidence of k metasomatism the apparent metasomatism can be explained using a new model in which there was extensive felsic volcanism contemporaneous with pedogenesis and k and rb were likely added by windborne ash the apparent discordance between k and rb contents of the paleosols can be explained by the presence of land plants because k is an important electrolyte and rb does not serve any major biological role this model could account for apparent k metasomatism in other paleosols following the advent of land plants and may be applicable to older paleosols as well

post palaeozoic evolution of weathered landsurfaces in uganda by tectonically controlled deep weathering and stripping a model for the evolution of weathered landsurfaces in uganda is developed using available geotectonic climatic sedimentological and chronological data the model demonstrates the pivotal role of tectonic uplift in inducing cycles of stripping and tectonic quiescence for cycles of deep weathering it is able to account for the development of key landforms such as inselbergs and duricrust capped plateaux which previous hypotheses of landscape evolution that are based on climatic or eustatic controls are unable to explain development of the ugandan landscape is traced back to the permian following late palaeozoic glaciation a trend towards warmer and more humid climates through the mesozoic enabled deep weathering of the jurassic mid cretaceous surface in uganda during a period of prolonged tectonic quiescence uplift associated with the opening south atlantic ocean terminated this cycle and instigated a cycle of stripping between the mid cretaceous and early miocene deep weathering on the succeeding miocene to recent african surface has occurred from miocene to present but has been interrupted in the areas adjacent to the western rift where development of a new drainage base level has prompted cycles of stripping in the miocene and pleistocene

weathering and sediment generation in the archean an integrated study of the evolution of siliciclastic sedimentary rocks of the 3 2ga moodies group barberton greenstone belt south africa abstract alluvial and braided fluvial deposits of the 3 2 ga moodies group in the barberton greenstone belt south africa are analyzed petrographically and geochemically to identify their source rocks provenance and assess the degree and type s of weathering required to produce the observed moodies sediment compositions conglomerate sandstone and shale data give somewhat differing pictures of provenance and weathering due to derivation from different components within the source terrane and size and compositional fractionation during transport the results suggest that shale geochemistry provides the most accurate estimate provenance although both rare earth element and trace element th sc zr cr and ti data must be used in combination to give the best results the source area for moodies group sediments was dominated by tonalite felsic volcanic rock komatiite basalt and granite based on mineralogical and major element divergence from estimated source area composition the moodies group sediments are remnants of an aggressive weathering environment labile materials such as komatiite basalt and coarse plagioclase grains decomposed almost entirely to clays and solutes and the chemical index of alteration for moodies shale is well above the global average an aggressive weathering environment in the archean may have been achieved by increased rainfall higher temperatures and or higher atmospheric p c o 2 more likely a combination of these conditions worked to offset the inhibitory weathering effects of a plant free environment

description of a new specimen of ianthasaurus hardestiorum eupelycosauria edaphosauridae and a re evaluation of edaphosaurid phylogeny ianthasaurus hardestiorum a basal edaphosaurid from the upper pennsylvanian of garnett kansas has been described on the basis of two incomplete juvenile specimens and a series of disarticulated vertebral elements new skeletal material of this poorly known species includes previously unknown cranial elements increasing our knowledge of the anatomy and variation in this taxon the complete ossification of the neural arches and the overall larger size of the vertebrae relative to those previously described indicate that they were part of an adult individual and marginal tooth morphology resembles more closely that seen in the genus edaphosaurus phylogenetic analysis of edaphosaurid synapsids confirms the hypothesis that ianthasaurus is a sister taxon of all other members of the clade however the incomplete fossil record of other putative edaphosaurids such as lupeosaurus and glaucosaurus makes full resolution of their phylogenetic interrelationships difficult to assess

atmospheric carbon dioxide and climate change since the late jurassic 150ma derived from a global carbon cycle model abstract a global carbon cycle model covering the late jurassic period to recent 150 0 ma with subaerial metamorphism and continental and oceanic hot spot volcanism was constructed the model s results indicate that the oae1a and valanginian oae oae oceanic anoxic event in the cretaceous period are related to increased atmospheric co2 level due to hot spot volcanism furthermore the model results based on high resolution geochemical records demonstrate that decreases in co2 associated with the termination of the oae1a oae2 and perhaps the valanginian oae are attributable to a large amount of organic carbon burial moreover the model results indicate that enhanced continental weathering and carbonate precipitation contributed to the decrease in atmospheric co2 during the oae1a period a comparison of the model results with proxy estimates of atmospheric co2 indicates that co2 degassings from the lithosphere and mantle including those from subaerial metamorphism partly contributed to high levels of atmospheric co2 in the middle cretaceous and the eocene but they are not sufficiently decisive to account for the suggested co2 levels by the proxies differences in estimated co2 between the model and the proxies in the middle cretaceous can be explained by a complex evolution of the terrestrial plants from gymnosperms to angiosperms and or continental weathering assisted by arbuscular mycorrhizal and ectomycorrhizal fungi and a fluctuation of the climate sensitivity which would have dynamically changed on geological time scales whereas an increase in non co2 greenhouse gases could explain the co2 difference in the eocene warming

change point analysis of geophysical time series application to landslide displacement rate sechilienne rock avalanche france the rank sum multiple change point method is a robust statistical procedure designed to search for the optimal number and the location of change points in an arbitrary continue or discrete sequence of values as such this procedure can be used to analyse time series data twelve years of robust data sets for the sechilienne french alps rockslide show a continuous increase in average displacement rate from 50 to 280 mm per month in the 2004 2014 period followed by a strong decrease back to 50 mm per month in the 2014 2015 period when possible kinematic phases are tentatively suggested in previous studies its solely rely on the basis of empirical threshold values in this paper we analyse how the use of a statistical algorithm for change point detection helps to better understand time phases in landslide kinematics first we test the efficiency of the statistical algorithm on geophysical benchmark data these data sets stream flows and northern hemisphere temperatures being already analysed by independent statistical tools second we apply the method to 12 yr daily time series of the sechilienne landslide for rainfall and displacement data from 2003 december to 2015 december in order to quantitatively extract changes in landslide kinematics we find two strong significant discontinuities in the weekly cumulated rainfall values an average rainfall rate increase is resolved in 2012 april and a decrease in 2014 august four robust changes are highlighted in the displacement time series 2008 may 2009 november december 2010 january 2012 september and 2014 march the 2010 one being preceded by a significant but weak rainfall rate increase in 2009 november accordingly we are able to quantitatively define five kinematic stages for the sechilienne rock avalanche during this period the synchronization between the rainfall and displacement rate only resolved at the end of 2009 and beginning of 2010 corresponds to a remarkable change fourfold increase in mean displacement rate in the landslide kinematic this suggests that an increase of the rainfall is able to drive an increase of the landslide displacement rate but that most of the kinematics of the landslide is not directly attributable to rainfall amount the detailed exploration of the characteristics of the five kinematic stages suggests that the weekly averaged displacement rates are more tied to the frequency or rainy days than to the rainfall rate values these results suggest the pattern of sechilienne rock avalanche is consistent with the previous findings that landslide kinematics is dependent upon not only rainfall but also soil moisture conditions as known as being more strongly related to precipitation frequency than to precipitation amount finally our analysis of the displacement rate time series pinpoints a susceptibility change of slope response to rainfall as being slower before the end of 2009 than after respectively the kinematic history as depicted by statistical tools opens new routes to understand the apparent complexity of sechilienne landslide kinematic

microseismic investigation of an unstable mountain slope in the swiss alps 1 risks associated with unstable rocky slopes are growing as a result of climate change and rapid expansions of human habitats and critical infrastructure in mountainous regions to improve our understanding of mountain slope instability we developed a microseismic monitoring system that operates autonomously in remote areas afflicted by harsh weather our microseismic system comprising 12 three component geophones was deployed across 60 000 m 2 of rugged crystalline terrain above a huge 30 million m 3 recent rockfall in the swiss alps during its 31 month lifetime signals from 223 microearthquakes with approximate moment magnitudes ranging from 2 to 0 were recorded determining the hypocenters was challenging for several reasons 1 p wave velocities were highly heterogeneous varying abruptly from 3 8 km s 2 first break picks were either inaccurate or lacking for some microearthquakes 3 there were no reliable s wave picks 4 numerous microearthquakes occurred just outside the network boundaries these issues were addressed by using a three dimensional 3 d p wave velocity model of the mountain slope determined from refraction tomography in a nonlinear inversion for hypocenter parameters and their probability density functions recordings from geophones at different altitudes and in boreholes constrained microearthquake depth estimates most microearthquakes were concentrated within 50 100 m of the surface in two zones one that followed the recent rockslide scarp and one that spanned the volume of highest fracture zone fault density these two active zones delineated a mass of rock that according to geodetic measurements has moved toward the scarp at 1 2 cm yr

lithologic and climatologic controls of river chemistry abstract the chemistries of rivers draining a variety of lithologic and climatic regions have been surveyed for the purpose of quantifying the fluxes of bicarbonate and silica from rivers with respect to bedrock lithology and runoff in all 101 different rivers each draining a primary lithology were examined across the united states puerto rico and iceland to minimize seasonal effects only rivers with at least two years of data were used basaltic catchments were examined in the greatest detail in a survey of hawaiian island watersheds the average river chemistries could be related to the distribution of soil associations within each catchment an analysis of cation activity relationships among rivers draining basaltic catchments shows that the river compositions define slopes which are consistent with an equilibrium ion exchange control on cation ratios among different lithologies unique weathering rate relationships were developed with yields at typical present day runoff rates 1 100 cm y increasing in the order sandstones granites basalts shales and carbonates the bicarbonate and silica fluxes for each of these lithologies have been quantified for use in global studies of chemical denudation our study confirms that the dissolved yield of a given drainage basin is determined by a balance between physical and chemical weathering thus a warm wet climate or the presence of abundant vegetation cannot guarantee high rates of chemical denudation unless accompanied by high rates of physical removal

periodic mid cretaceous oceanic anoxic events linked by oscillations of the phosphorus and oxygen biogeochemical cycles 1 a series of oceanic anoxic events oaes occurred in the mid cretaceous warm period 120 80 ma that have been linked with high rates of organic carbon burial warm high and low latitude temperatures and sea level changes oaes have been studied individually but a causal mechanism that connects them has been lacking we show that peaks in phosphorus accumulation in marine sediments broadly coincide with oaes 1a 1b 1d 2 and 3 and exhibit a 5 6 myr periodicity which for reactive p is prominent over 100 80 ma oxic anoxic oscillations of this frequency are also found in a model of the coupled n p c and o2 biogeochemical cycles these oscillations are maintained by positive feedbacks between phosphate concentration biological productivity and anoxia in the global ocean and counteracting but slower negative feedbacks involving changes in atmospheric oxygen an increase in phosphorus weathering rate above a critical threshold can shift the system into self sustaining oscillation this could have been caused by tectonic and volcanic forcing increasing atmospheric co2 and global warmth 120 80 ma augmented by the rise of flowering plants around 100 ma with a plausible forcing scenario we are able to reproduce the approximate timing of oaes 1a 1b 1d 2 and 3 in the model

seismic and geodetic signatures of fault slip at the slumgullion landslide natural laboratory 1 we tested the hypothesis that the slumgullion landslide is a useful natural laboratory for observing fault slip specifically that slip along its basal surface and side bounding strike slip faults occurs with comparable richness of aseismic and seismic modes as along crustal and plate scale boundaries our study provides new constraints on models governing landslide motion we monitored landslide deformation with temporary deployments of a 29 element prism array surveyed by a robotic theodolite and an 88 station seismic network that complemented permanent extensometers and environmental instrumentation aseismic deformation observations show that large blocks of the landslide move steadily at approximately centimeters per day possibly punctuated by variations of a few millimeters while localized transient slip episodes of blocks less than a few tens of meters across occur frequently we recorded a rich variety of seismic signals nearly all of which originated outside the monitoring network boundaries or from the side bounding strike slip faults the landslide basal surface beneath our seismic network likely slipped almost completely aseismically our results provide independent corroboration of previous inferences that dilatant strengthening along sections of the side bounding strike slip faults controls the overall landslide motion acting as seismically radiating brakes that limit acceleration of the aseismically slipping basal surface dilatant strengthening has also been invoked in recent models of transient slip and tremor sources along crustal and plate scale faults suggesting that the landslide may indeed be a useful natural laboratory for testing predictions of specific mechanisms that control fault slip at all scales

the effect of land plants on weathering rates of silicate minerals abstract land plants and their associated microbiota directly affect silicate mineral weathering in several ways by generation of chelating ligands by modifying ph through production of co2 or organic acids and by altering the physical properties of a soil particularly the exposed surface areas of minerals and the residence time of water in laboratory experiments far from equilibrium 1 mm oxalate a strong chelator of al has a negligible effect on the dissolution rate of alkali feldspars but some effect on calcic feldspars and olivine by analogy to oxalate the overall effect of organic ligands on the weathering rate of silicate minerals in nature is likely to be small except perhaps in microenvironments adjacent to roots and fungal hyphae the effect of ph on silicate mineral dissolution rate depends on ph below ph 4 5 the rate increases with decreasing ph in the circumneutral region the rate is ph independent and at ph values above around 8 the rate increases with increasing ph vegetation should thus cause an increase in weathering rate through the ph effect only where the ph is below 4 5 as an overall generalization the effect of plants on weathering rate through changes in soil solution chemistry is probably small for granitic rocks it may be greater for more mafic rocks it is the release of ca and mg from mafic rocks that has the greatest influence on the global co2 budget the effect of changes in soil physical properties on weathering rate can be major by binding fine particles plants can greatly increase weathering rates in areas of high physical erosion where erosion rates are lower the effect of plants is less clear on long timescales plants may decrease chemical weathering by binding secondary products and isolating unweathered minerals from meteoric water a major unknown in estimating the effect of the advent of land plants on weathering rates is the nature thickness particle size distribution permeability of the regolith on the pre silurian continents the indirect effect of vegetation through changing the regional distribution of precipitation may be as important as the direct effects

seismic monitoring of sechilienne rockslide french alps analysis of seismic signals and their correlation with rainfalls 1 in the french alps sechilienne rockslide is one of the natural phenomena that presents one of the highest levels of risk in terms of socioeconomical outcomes this rockslide has been active for a few decades and has been instrumented since 1985 the current very active volume of this rockslide is estimated to be up to 5 million m3 located on the border of a slowly moving mass reaching 50 100 million m3 the velocity of the most active zone reached 1 4 m yr in 2008 about twice the value of 2000 a seismic network was installed on this rockslide in may 2007 to supplement the monitoring system it has now recorded several thousand events mostly rockfalls but also hundreds of local and regional earthquakes which can be distinguished and classified from their signal characteristics rockfalls and microseismicity which occur in bursts of activity are found to be weakly but significantly correlated with rainfall rockfall occurrence increases linearly with precipitation with however strong fluctuations of the numbers of rockfalls per day for the same rainfall intensity no threshold was found for rainfall triggering with even 1 mm of rain being enough to trigger rockfalls rockfall activity starts almost immediately during a rainfall episode and lasts for several days after the rainfall rain also induces strong accelerations of the rockslide movement which also start quasi instantaneously and last for about a month

deep geophysical investigation of the large sechilienne landslide western alps france and calibration with geological data a geophysical imaging campaign including four 950 m electrical profiles and four 470 m long seismic profiles was performed on the large sechilienne landslide with the objective of constraining the depth and the volume of the affected zone compared to the undisturbed ground the moving area exhibits lower velocity and higher resistivity values comparison with existing geodetic geomorphic and geological data investigation gallery and borehole allowed showing that these geophysical parameter variations result from intense fracturing and the progressive development of air filled voids within the moving mass a maximum thickness of 150 m to 200 m was found in the most deconsolidated zones locally near vertical very low resistivity anomalies were evidenced related to cataclasis zones filled with clayey material applying the wyllie s experimental law rock mass porosity images were derived from seismic tomography profiles porosity between 30 and 4 was found from the top to the bottom of the deconsolidated zone explaining the deep water table considering a porosity threshold of 3 7 for the sound bedrock the total volume of the sechilienne landslide was estimated to about 60 10 106 m3 a more precise bracket than the previous estimations 20 106 to 100 106 m3

direct effects of co2 and temperature on silicate weathering possible implications for climate control a critical uncertainty in models of the global carbon cycle and climate is the combined effect of organic activity temperature and atmospheric co2 on silicate weathering here we present new dissolution rates of anorthite and augite which indicate that silicate weathering in organic rich solutions is not directly affected by soil co2 but is very sensitive to temperature apparently co2 accelerates silicate weathering indirectly by fertilizing organic activity and the production of corrosive organic acids the weathering dependencies highlight the ability of silicate weathering to act as a global thermostat and damp out climate change when used as input in steady state carbon cycle and climate models

inorganic geochemistry of the type caradoc series sandbian to middle katian upper ordovician onny valley shropshire uk the geochemistry and petrology of the type section of the caradoc series in the onny valley indicate that it was deposited on a marginal basin continental shelf similar to the western side of the present sea of japan the lower beds form a transgressive regressive sequence in which the rocks become less mature upwards all the coarser sediments above the basal quartzites and conglomerates are greywackes in which the apparent muddy and ferrous matrix is due to the breakdown of unstable minerals and particles higher values of na 2 o and na k ratios are found in the coarser shallow water sandstones of the horderley sandstone formation and decrease markedly in the succeeding beds accompanied by an increase in k 2 o higher values of carbonate corrected and hence related other major and minor elements like sio 2 cao p 2 o 5 mno and most trace elements correlate with the transgressive systems and maximum flooding surfaces of the three sequences recognized where they are related to condensation at those horizons chemical indices of alteration cia suggest that the horderley sandstone formation underwent greater predepositional physical weathering than lower and higher beds which is compatible with the petrography and were deposited during a cool phase within overall warm sandbian katian times trace element ratios suggest an oxic to suboxic depositional environment

high precision 40ar 39ar age constraints on the basal lanqi formation and its implications for the origin of angiosperm plants abstract abundant mesozoic terrestrial fossils were discovered in the haifanggou formation and the overlying lanqi formation in northeastern china the recent discovery of schmeissneria sinensis from the haifanggou formation provides evidence that the origin of angiosperms could be much earlier than previously believed 92 taxa of plant fossils from the lanqi formation provide unique opportunities to understand the floral evolution and its diversification in the mesozoic here we present robust high precision 40ar 39ar data of 160 7 0 4 ma and 158 7 0 6 ma for two tuffs from the lowest part of the lanqi formation near the main outcrop of floral fossils in beipiao city liaoning china our age results indicate the whole lanqi formation was deposited in the late jurassic consequently the underlying haifanggou formation and schmeissneria sinensis are at least middle jurassic in age besides its importance for floral evolution our high precision age results for the basal lanqi formation indicate the paleoenvironment in the north margin of the north china craton was dry and hot in the late jurassic moreover the new age data for the basal lanqi formation suggest that the unearthed fossils from the haifanggou formation and lanqi formation should be equivalent to the daohugou biota in inner mongolia china

spatio temporal evolution of rockfall activity from 2007 to 2011 at the piton de la fournaise volcano inferred from seismic data abstract seismic data have been used to catalog the location and volume of most of the rockfalls that occurred at the piton de la fournaise volcano from may 2007 just after the major collapse of the dolomieu summit crater floor to may 2011 this catalog made it possible to compare the evolution of the number and volume of rockfalls at a high temporal resolution and to investigate their links with eruptions seismicity deformations and rainfalls affecting the piton de la fournaise volcano results show that the purge of unstable areas created by the dolomieu crater floor collapse occurred in two phases a first phase lasting three months during which the intense rockfall activity immediately following the collapse decreased abruptly and a second phase lasting more than two years during which the daily volume of the rockfalls slowly decreased before reaching a steady state a detailed study of 4 time periods including 3 eruptive cycles indicates that strong seismicity can increase the number of rockfalls furthermore when a dike reaches the surface at the summit of the central cone giving birth to an eruption the associated local forcing can in some cases increase the volume of rockfalls possibly by creating or expanding weak zones in most cases this is not observed for dike intrusions that do not reach the surface the newly created weak zones are most often far from the eruptive fissures of the ongoing eruption but close to the location of the next eruption this suggests that these distant zones are also weakened at depth thus creating preferred paths for future dikes propagating toward the surface the impact of rainfall on rockfall activity was also studied given that la reunion island is subject to very intense rainfall events our results show that rainfall can in some cases trigger rockfalls rapidly with response times of less than a day but not systematically and no triggering rainfall threshold was found

cosmic ray exposure dating on the large landslide of sechilienne western alps a synthesis to constrain slope evolution abstract the 60 10 6 m 3 sechilienne landslide belledonne massif western alps is located on the right bank of the east west trending romanche valley which is shaped by glacial and alluvial processes during the quaternary its head scarp 35 m high was dated by le roux et al 2009 using the cosmic ray exposure cre method even though these previous results revealed that the initiation of the instability occurred several thousand years after ice down wastage in the valley the internal landslide evolution is not constrained in this paper we provide 63 additional 10 be samples collected from the internal scarps and the main scarp as well as on glacially polished rock surfaces the aim is to constrain the global landslide kinematics internal and head scarps and its relationship with glacier retreat results from glacially polished surfaces point out that complex shielding processes relict moraines soil deposits and seasonal snow cover might have affected rock dating despite scattering of the resulting ages the dataset shows that the glacial retreat was achieved between 17 5 and 13 ka exposure ages obtained on gravitational scarps reveal that the landslide initiation occurred 8 to 6 ka ago from the initiation until 2 ka the gravitational kinematics was slow 2 mm year 1 and focused around the head scarp leading to a general slope subsidence after 2 ka the exposure rates increased significantly 8 mm year 1 with the development of pervasive internal deformation of the landslide mass this new scenario for the sechilienne slope reflects a progressive rock slope weakening since 8 ka associated with a continuous activity of a deep seated surface failure

biogenic silica a neglected component of the coupled global continental biogeochemical cycles of carbon and silicon on geological time scales 106 years the global geochemical cycles of carbon and silicon are coupled by the drawdown of atmospheric co2 through chemical weathering of ca and mg silicate minerals in continental rocks rivers transport the soluble products of weathering cations alkalinity and silicic acid to the oceans where they are utilized by marine ecosystems on decadal to glacial interglacial time scales however large biotic fluxes and storages of si within terrestrial and freshwater ecosystems need to be taken into account recent studies have emphasized the importance of si accumulating plants which deposit significant amounts of amorphous hydrated silica in their tissues as opal phytoliths these include grasses sedges palms some temperate deciduous trees and conifers and many tropical hardwoods landscapes dominated by accumulator plants such as tropical rainforests grasslands herbaceous wetlands and bamboo forests act as silica factories important silica bioengineers in freshwater ecosystems comprise diatoms sponges and chrysophytes this paper reviews the biological role of si in higher plants the impact of vegetation on rates of chemical weathering the fluxes of si through catchment ecosystems lakes and rivers and the potential contribution of new geochemical and isotopic tracers to si biogeochemistry multiproxy investigations of lake sediments will provide novel insights into past variations in si biocycling from terrestrial to aquatic realms on 10 106 year time scales copyright 2008 john wiley sons ltd

use of the simultaneous seismic gps and meteorological monitoring for the characterization of a large unstable mountain slope in the southern french alps summary the presence of unstable rock slopes in the mountainous regions makes these areas particularly prone to the development of sudden dramatic events which may cause damage and injuries the efficient disaster management requires a good understanding of the main causes of these mass movements such as increased fluid pressure and seismic shaking in order to improve our understanding of the mechanics and dynamics of the mountain slope instabilities we developed a monitoring system based on microseismic geodetic and meteorological measurements the

cranial anatomy of the primitive reptile procolophon the skull of the lower triassic reptile procolophon is described on the basis of newly prepared specimens in the collection of the british museum natural history and from casts made from high fidelity natural molds it is concluded that this genus had a large tympanum supported by the supratemporal squamosal and quadratojugal the stapes remains incompletely known but probably functioned as part of an impedance matching system comparable with that of modern lizards the teeth of the upper and lower jaws are inset from the margin of the skull suggesting the presence of cheeks jaw movement is confined to the vertical plane neither resorption pits nor weakly attached crowns provide evidence of tooth replacement the position of the teeth is controlled so that the upper and lower teeth interdigitate exactly with wear facets on the anterior and posterior surfaces a natural cast of the nasal cavities resembles that of triassic cynodont therapsids suggesting the presence of turbinais and extensive olfa

late jurassic fluvial eolian deposits from the tianchihe formation ningwu jingle basin shanxi province china abstract eolian systems were widespread in china in the cretaceous however the reports of pre cretaceous eolian and its related systems are scarce which prohibits studying the construction accumulation and preservation of eolian systems as well as its allogenic and autogenic controlling factors in this paper we report on fluvial eolian successions from the late jurassic tianchihe formation in the ningwu jingle basin these successions represent the oldest reported inland fluvial eolian systems in china fourteen lithofacies types are recognized in the tianchihe formation and have been grouped into six facies associations including meandering fluvial channel levee and overbank in the lower part and eolian sandsheet eolian dune ephemeral fluvial channel and floodplain in the upper part the fluvial system comprises a series of wetting upward cycles which indicate humid climate culminating in high precipitation and shallow water table level eolian dune deposits composed of grainflow grainfall wind ripple strata and pin stripe laminations currently implies that all deposits types are internally bounded by reactivation surface and superimposition surface suggesting compound dunes or draas eolian sandsheet deposits consist dominantly of subcritical climbing translatent strata and pin stripe lamination the association of eolian dune and eolian sandsheet is development of a dry eolian system twelve drying upward cycles mainly composed of eolian sandsheet eolian dune successions and four wetting upward cycles consisting of eolian sandsheet dune ephemeral fluvial channel floodplain successions occur in the eolian system these repeated cycles likely reflect an evolving erg system directly controlled by sediment supply sediment availability and relative water table the vertical transition from fluvial to eolian systems indicate a local climatic oscillation from relatively humid to arid conditions which may be related with the uplift of the east china plateau in the late jurassic

internal structure and deformation of an unstable crystalline rock mass above randa switzerland part i internal structure from integrated geological and geophysical investigations 6m 3 of material occurred in fractured gneissic rock whose principal foliation faults and fracture zones dip into the slope above the scarp of the second rockslide the mountain continues to move at rates of up to 2 cm year in an attempt to understand failure mechanisms in fractured crystalline rock masses we have carried out a comprehensive multidisciplinary study that included detailed geological mapping borehole logging and imaging and surface and borehole geophysical surveys an integrated interpretation of the resultant data has revealed the presence of three prominent fault and fracture zone sets that define the internal structure of the rock mass some faults and fracture zones could be traced up to 85 m into the subsurface using borehole radar reflection methods the dips of the faults and fracture zones estimated from surface mapping matched those from radar reflection and borehole televiewer surveys no evidence was found for significant faults or persistent weakness planes that paralleled the 1991 rockslide failure surfaces instead the new observations were consistent with dominant failure mechanisms that involve the progressive development of major shear and brittle fracturezones and the eventual destruction of intact rock bridges immediately prior to catastrophic collapse this integrated study provides the first reliable model of the 3 d fault structure associated with and contributing to a large rock slope instability in a brittle crystalline rock mass

plant impact on the biogeochemical cycle of silicon and related weathering processes abstract the contribution of plants to the biogeochemical cycle of si and related weathering processes was studied in an equatorial rainforest ecosystem congo where the biologic turnover of si is high 58 to 76 kg ha y litterfall leaves a soil profile and groundwaters were analysed phytoliths and organic matter have a similar distribution with depth in the soil profile the model of a bicompartmental distribution of organic matter is applied to phytolith distribution and shows that about 92 of the biogenic silica input is rapidly recycled while about 8 of the biogenic silica input supplies a stable pool of phytoliths with a lower turnover reprecipitation of silica was observed at the base of the soil profile indicating a local geochemical environment that is oversaturated with respect to amorphous silica a balance in biogeochemical cycle of si requires that the vegetation absorb dissolved silicon released from weathering of minerals which otherwise would be available for mineral neoformation or export from the profile towards regional drainages plant uptake of si increases the chemical weathering rate without increasing the denudation rate this study shows that the uptake storage and release of si by the vegetation have to be taken into account when using dissolved si for tracing chemical weathering dynamics

alternation of back arc extension and compression in an overriding plate evidence from cretaceous structures in the western liaoning region eastern china the dynamic evolution in an overriding plate remains a controversial issue cretaceous structures in the western liaoning wl region of the eastern north china craton ncc an overriding plate bordering the pacific ocean provide insights into the dynamic evolution related to paleo pacific plate subduction we present structural and fault slip data from the jurassic cretaceous basins in the wl region together with previously published isotopic ages to constrain structural and stress field evolution during the cretaceous these data reveal four phases of deformation in the wl region tectonic shortening d1 at 137 136 ma extension d2 during 136 97 ma another shortening d3 at the beginning of the late cretaceous and relatively weak extension d4 during the late cretaceous inversions of the measured fault slip data yield nw se compression during d1 nw se extension during d2 nnw sse compression during d3 and n s extension during d4 deformation phases d1 and d3 correspond to shortening events b and c of the yanshan movement whereas d2 corresponds to the peak destruction of the ncc in a back arc extensional setting the structural evolution indicates that the back arc extension d2 of the early cretaceous started immediately after the brief shortening event d1 and ended with another shortening event d3 subsequently the back arc region underwent weak extension d4 during the late cretaceous a slab driven model could account for the tectonic evolution in the eastern ncc periodic changes in the kinematics of the subducting paleo pacific plate are responsible for the alternation of the back arc extension and compression in the overriding plate

a multitaxic bonebed near the carboniferous permian boundary halgaito formation cutler group in valley of the gods utah usa vertebrate paleontology and taphonomy abstract the carboniferous permian c p transition records a shift in the composition and environmental setting of tropical flora and vertebrate assemblages across western and central pangea here we report the discovery of a rare multitaxic bonebed in the lower halgaito formation cutler group in valley of the gods and its vicinity san juan county southeast utah usa the assemblage which comprises carcasses and disarticulated bones and teeth preserves aquatic and semi terrestrial elements including xenacanth chondrichthyans actinopterygians sagenodontid lungfish and the temnospondyl amphibian eryops together with terrestrial taxa including the synapsids ophiacodon navajovicus edaphosaurus and sphenacodon and a hitherto undescribed araeoscelidan reptile sedimentological paleontological and strontium isotopic evidence indicates the bonebed formed as a slackwater deposit at the confluence of a major freshwater stream channel and its tributary the deposit probably formed through late stage flooding of a likely bottlenecked fluvial system consistent with increasingly episodic or seasonal precipitation concentrating carcasses of immature and mature shore dwelling animals comparisons with vertebrate assemblages in the cutler group of new mexico usa suggest that the assemblage is correlative with the lower or middle assemblage of the el cobre canyon formation cobrean and coyotean land vertebrate faunachrons lvfs and as such is of latest carboniferous age our findings strengthen the hypothesis that dryland adapted vertebrate communities proliferated earlier in westernmost pangea well before earliest permian time compared to other tropical regions

location of seismic signals associated with microearthquakes and rockfalls on the sechilienne landslide french alps the sechilienne rockslide in the french alps has recently been instrumented with three seismic arrays this network has recorded numerous rockfalls and local microearthquakes because the media is highly fractured it is difficult to identify and pick first arrivals beam forming methods were therefore used to locate these events the method has been adapted to take into account the heterogeneity of seismic wave velocities the location accuracy has been estimated to be about 50 m for epicenters by applying the method to calibration shots depth is less constrained due to uncertainties on the velocity model and due to the seismic network geometry this method of location has then been applied to rockfalls and microearthquakes most rockfalls initiate in the most active part of the rockslide called les ruines the others are located on a recent eroded area aside from les ruines the network also allows the estimation of the rockfall trajectory and propagation speed finally 55 microearthquakes have been located within two zones microearthquakes are located within the first 250 m below the surface most microearthquakes are located in les ruines the most active part of the rockslide where the velocity has increased from 0 5 m yr in 1996 to 1 4 m yr in 2008 these events are located close to three faults that delimit a mass of about 3 6 million m3 other events are located close to the summital scarp in a zone moving at a few centimeters per year the western part of the rockslide which moves more slowly did not produce any event large enough to be detected simultaneously by all stations this seismic monitoring suggests that only a very small fraction of the deformation is released through seismic events

diachronous onset and polyphase cooling of the taili yiwulushan metamorphic core complex corridor ne china and its relationships to the formation of adjacent extensional basins abstract the aim of the study to investigate the cooling and exhumation history of deep crustal rocks along the taili yiwulushan metamorphic core complex mcc corridor and correlate these with volcanic clastic deposition in the late jurassic to early cretaceous supra detachment fuxin yixian basin in the west and the mostly eocene liaohe basin in the east this corridor exposes low to medium grade metamorphic neoarchean rocks and late triassic late jurassic and early cretaceous granitic rocks which exhumed from the middle to shallow crustal levels new 40ar 39ar ages of muscovite biotite k feldspar and apatite u th sm he ages in combination with compiled published geochronological data from the granitic rocks constrain three major stages of cooling exhumation and deformation from late jurassic through early cretaceous to eocene interrupted by late cretaceous tectonic quiescence the onset of activity and exhumation and cooling is diachronous along the mcc corridor at taili in the south the main activity of the sinistral shear zone is constrained between 160 and 140 ma with major cooling from crystallization temperatures of granitoids from 700 750 c to 160 c first stage along the waziyu ductile detachment at the western border of the yiwulushan mcc major cooling and exhumation is bracketed between 130 ma and 100 ma second stage and thus indicates a northward progradation of deformation and exhumation activity however cooling ages as old as 159 ma along the eastern margin of the yiwulushan mcc indicate an earlier initiation of cooling and westward rolling hinge type propagation first stage late cretaceous and paleogene times are characterized by a tectonically quiet period with only minor cooling and exhumation stage three the fourth and final stage of exhumation and cooling to very low temperatures occurred during late paleocene to earliest eocene times and is associated with the transtensional or extensional opening of the liaohe basin

climate change during the last 150 million years reconstruction from a carbon cycle model variations of the atmospheric co2 level and the global mean surface temperature during the last 150 ma are reconstructed by using a carbon cycle model with high resolution input data in this model the organic carbon budget and the co2 degassing from the mantle both of which would characterize the carbon cycle during the cretaceous are considered and the silicate weathering process is formulated consistently with an abrupt increase in the marine strontium isotope record for the last 40 ma the second order variations of the atmospheric co2 level and the global mean surface temperature in addition to the first order cooling trend are obtained by using high resolution data of carbon isotopic composition of marine limestone seafloor spreading rate and production rate of oceanic plateau basalt the results obtained from this model are in good agreement with the previous estimates of palaeo co2 level and palaeoclimate inferred from geological biogeochemical and palaeontological models and records the system analyses of the carbon cycle model to understand the cause of the climate change show that the dominant controlling factors for the first order cooling trend of climate change during the last 150 ma are tectonic forcing such as decrease in volcanic activity and the formation and uplift of the himalayas and the tibetan plateau and to a lesser extent biological forcing such as the increase in the soil biological activity the mid cretaceous was very warm because of the high co2 level 4 5 pal maintained by the enhanced co2 degassing rate due to the increased mantle plume activities and seafloor spreading rates at that time although the enhanced organic carbon burial would have a tendency to decrease the co2 level effectively at that period the variation of organic carbon burial rate may have been responsible for the second order climate change during the last 150 ma

application of geophysical methods for the investigation of the large gravitational mass movement of sechilienne france several geophysical techniques electromagnetic profiling electrical tomography seismic refraction tomogra phy and spontaneous potential and seismic noise measurement were applied in the investigation of the large gravita tional mass movement of sechilienne france the aim of this study was to test the ability of these methods to characterize and delineate the rock mass affected by this complex movement in mica schists whose lateral and vertical limits are still uncertain a major observation of this study is that all the zones strongly deformed previously and at present by the movement are characterized by high electrical resistivity values 3 k m in contrast to the undis turbed mass which exhibits resistivity values between a few hundred and 1 k m as shown by the surface observa tions and the seismic results this resistivity increase is due to a high degree of fracturing associated with the creation of air filled voids inside the mass other geophysical techniques were tested along a horizontal transect through the movement and an outstanding coherency appeared between the geophysical anomalies and the displacement rate curve these preliminary results illustrate the benefits of combined geophysical techniques for characterizing the rock mass in volved in the movement results also suggest that monitoring the evolution of the rock mass movement with time lapse geophysical surveys could be beneficial resume plusieurs techniques geophysiques profil electromagnetique tomographie electrique tomographie sismique et potentiel spontane et bruit de fond sismique ont ete appliquees pour la reconnaissance du grand mouvement de ter rain de sechilienne france situe dans des micaschistes l objectif de cette etude etait de tester ces methodes geophy siques afin de caracteriser et de delimiter la masse de roche affectee par ce mouvement complexe dont la limite laterale reste incertaine l etude a montre que toutes les zones tres deformees encore actuellement et dans le passe par le mouvement sont caracterisees par de fortes valeurs de resistivite electrique superieur ea3k m tandis que dans la zone non perturbee les valeurs de resistivite sont de quelques centaines de m a1k m comme le montrent les observations de surface et les profils de tomographie sismique cette augmentation de resistivite est due a une frac turation importante associee a la creation de vides remplis d air au sein du massif les techniques electromagnetiques ps et de mesure de bruit ont ete testees le long d un profil transversal recoupant le mouvement une correlation remar quable est obtenue entre les anomalies geophysiques et le taux de deplacement ces resultats preliminaires soulignent l interet de combiner les methodes geophysiques pour caracteriser la masse de roche impliquee dans le mouvement et pour determiner l evolution du mouvement par un suivi temporel des parametres geophysiques mots cles mouvement gravitaire methodes geophysiques sechilienne meric et al 1115

promotion of chemical weathering by higher plants field observations on hawaiian basalts abstract an electron microprobe and petrographic microscope were used to study the biota rock interface beneath higher plant communities and lichens as well as unvegetated surfaces on hawaiian basalt flows ranging from a few years to several thousand years in age and currently receiving moderate to extremely high annual rainfall we find dramatic order of magnitude minimum acceleration of weathering rates beneath vascular plants on the youngest flows relative to adjacent non or primitively vegetated controls notably rocks colonized by the common fruticose lichen stereocaulon uulcani bulk dissolution of plagioclase accounts for most of the weathering observed beneath higher plants on these young basalts analysis of older flows under mature forests reveals that chemical weathering beneath vascular plant communities continues unabated for thousands of years after initial colonization moreover such weathering is not limited to exterior basalt surfaces but is commonly found adjacent to joints and vesicles within the rock where it is often associated with fine sub 2 mm diameter plant roots plagioclase dissolution was also observed on lichen encrusted and unvegetated flows a few hundred to thousands of years in age but it was typically much less advanced than beneath higher plants and rarely extended more than several millimeters from exterior rock surfaces chemical denudation rates on older flows with higher plants are at minimum ten times greater than those with only lichens or microbiota in the environments studied if s uulcani and associated microflora resemble the terrestrial precursors to vascular plant communities then the results of studies such as this have implications for the history of atmospheric co 2 and the earth s climate

first report of sauropod tracks from the upper jurassic tianchihe formation of guxian county shanxi province china abstract this paper presents the first report of sauropod tracks from the upper jurassic of shanxi province china dinosaur tracks appear concentrated in five trackways in different stratigraphic levels of the late jurassic tianchihe formation tracks are dominantly small and medium size sauropod tracks and are tentatively assigned to brontopodus based on preserved track morphology trackway pattern and statistical analysis the tianchihe formation in which the tracks appear shows a gradual change from meandering fluvial to sandy braided fluvial depositional systems developed in a seasonally arid environment comparisons of the evaluated speed of bipedal to quadruped trackways indicate that the slower walk more easily produces pes dominated overprints trackways in the guxian tracksite appear following different orientations suggesting that these trackways were produced by different sauropods at different times an unusual trackway following a curved pattern has been identified in the site and could represent a special locomotion character or a social behavior the presence of eolian deposits in central shanxi province could have acted as a paleogeographic and paleoenvironmental barrier for the dispersion of the yanliao biota that survived in northern hebei western liaoning and northestern shanxi province to the ordos basin during the late jurassic

seymouria sanjuanensis amphibia batrachosauria from the lower permian cutler formation of north central new mexico and the occurrence of sexual dimorphism in that genus questioned six specimens of the amphibian seymouria preserved in a single block of matrix from the lower permian cutler formation of north central new mexico are described and referred to seymouria sanjuanensis vaughn they are the only seymouria specimens known from new mexico and provide a more extensive definition of the species it is interpreted that the specimens from new mexico were collected from an early to middle wolfcampian horizon and therefore represent the earliest known members of the genus evidence is presented that challenges previous explanations for the variability of several features of the skull and axial skeleton in specimens of seymouria baylorensis and s sanjuanensis as an indication of sexual dimorphism differences in the number of maxillary teeth depth of the maxilla and development of the maxillary dentition particularly in the canine region are interpreted as closely related morphological trends in seymouria although no satisfactory explanation is offered for differences in th

frequency and triggering of small scale submarine landslides on decadal timescales analysis of 4d bathymetric data from the continental slope offshore nice france time series bathymetric data acquired from 1967 to 2011 are used to evaluate the morphological evolution of the continental shelf and upper continental slope off the city of nice se france ligurian sea mapping in water depths of 0 300 m was undertaken to identify the changing morphology of landslide scars and their erosive chutes quantitative digital terrain model dtm comparisons reveal areas of erosion and deposition over intervals of 5 8 years sediment remobilization events on the upper slope above depths of 200 m are frequent and significant landslide scars with volumes 25 000 m3 can occur with frequencies of 200 m periods of quiescence 1980 1990 and 2006 2011 are seen to alternate with periods when rapid retrogressive failure increase sediment volumes eroded from the upper slope shelf transition by an order of magnitude 1999 2006 temporal variations in landslide activity were correlated to several potential triggering factors that individually would not induce failures including earthquake activity rapid deposition of fine grained sediments on a steep slope and rainfall leading to fresh groundwater circulation below the shelf this 4d bathymetric study suggests that over the last 50 years the most important factor triggering landslides offshore nice is overpressure due to freshwater outflows

a polygenetic palaeosol from the silurian wenlock of southwest ireland a problematic palaeosol unit caps a thick basalt at the top of the clogher head formation dunquin group late wenlock silurian in the dingle peninsula southwest ireland the main part of the unit consists of an altered calc alkaline basalt with a fine clay assemblage of chlorite corrensite and smectite probably resulting from weathering during wenlock times the uppermost part of the unit consists of detrital silicates which were admixed by bioturbation and well defined burrow fills are present the underlying weathered basalt was possibly truncated before the detrital horizon was deposited and finally the whole unit underwent a phase of surface water gleying a catenary relationship existed locally with the pseudo gley developed lower in the landscape while contemporaneous basalts in topographically higher better drained areas largely escaped the effects of gleying these now exhibit reddened tops the complex history and the possiblity of the incompleteness of the profile makes accurate assessment of the soil climate function difficult however the occurrence of calcrete bearing palaeosols in the overlying mill cove formation supports the view that the basalt was weathered under a sub humid or semi arid climate considering the alteration of the dunquin group to actinolite prehnite grade the preservation of the smectite is highly unusual there is no evidence for its origin due to more recent weathering or interstratal neoformation it is thus interpreted as a relict product of the original weathering phase

paleoclimate and the global distribution of paleosols a theoretical model is developed for the relationship between paleoclimate and paleosols for the time interval following the widespread appearance of vascular land plants the model defines four paleoclimatic zones 1 a wet equatorial zone primarily characterized by oxisols and secondarily by argillisols and histosols 2 a subtropical dry zone containing calcisols and less commonly gypsisols and vertisols 3 a moist mid latitude zone with argillisols spodosols gleysols and histosols and 4 a polar zone featuring protosols and gleysols the model is general in nature and its application to the geologic past will be affected by variability through time in paleogeography and paleoclimatic parameters

timing of the yanshan movement evidence from the jingxi basin in the yanshan fold and thrust belt eastern china evidence for the jurassic cretaceous yanshan movement orogeny was first identified in the jingxi basin a part of the yanshan fold and thrust belt yftb along the northern margin of the north china craton the disconformity or angular unconformity within the jurassic volcano sedimentary successions in the basin was interpreted to have resulted from a period of incipient shortening during the yanshan movement commonly known as event a however the absolute ages of both event a and associated jurassic units remain controversial here we present the results of zircon u pb geochronology for volcanic and clastic rocks from the jurassic units in the jingxi basin the results provide better constraints on the depositional ages of formations in the basin 1 early to early middle jurassic 175 167 ma for the nandaling formation 2 middle middle jurassic for the yaopo formation 3 late middle jurassic for the longmen formation 4 early late jurassic for the jiulongshan formation and 5 late late jurassic 157 149 ma for the tiaojishan formation stratigraphic and geochronological correlations indicate that the jiulongshan formation and the tiaojishan formation are of different depositional ages in different regions the longmen formation in the jingxi basin is equivalent to the haifanggou formation in the eastern yftb two sedimentary cycles separated by a sedimentary hiatus shown as disconformity and local angular unconformity have been identified in the jurassic sequences of the yftb depositional ages of the rocks above and below the disconformity which lies between the yaopo and longmen formations in the jingxi basin constrain the timing of event a to 167 2 ma late middle jurassic this event is the first phase of shortening deformation in eastern china induced by the paleo pacific plate subduction we propose that the shortening period was relatively transient in contrast to previous suggestions of long duration shortening

ianthasaurus hardestii n sp a primitive edaphosaur reptilia pelycosauria from the upper pennsylvanian rock lake shale near garnett kansas a new small pelycosaur ianthasaurus hardestii has been discovered in the well known richly fossiliferous locality in the upper pennsylvanian missourian stanton formation near garnett kansas it is represented by a partial semi articulated skeleton and scattered elements of at least three other individuals the small insectivorous ianthasaurus possesses a number of primitive pelycosaurian features but also shares several derived characters with the large early permian herbivore edaphosaurus justifying its inclusion in the family edaphosauridae and its recognition as the oldest and most primitive member of that group