changes of mammal assemblages in the pampean region argentina and their relation with the plio pleistocene boundary abstract a gradual impoverishment of autochthonous mammals in the southeastern pampean region central eastern argentina during the late cenozoic is detected it is partially coeval to the gradual immigration of holarctic mammals and to important climatic changes we propose that the plio pleistocene boundary at around 2 5 ma in the area is located between the vorohue formations and the base of miramar formations

preserved flora and organics in impact melt breccias impact cratering can destroy life from local to global scales and result in sudden turnovers of dominant genera and or species here we report that it can also preserve components of the local biology present at the time of impact we have investigated floral matter encapsulated within cenozoic era impact glasses produced by separate bolide impacts into the loessoid sediments of argentina that occurred between 9 2 ma miocene and 6 ka holocene the encapsulation preserved not only macro scale morphological biosignatures such as vascular bundles veins phytoliths and papillae but also structures down to the cellular level in the best preserved samples we also found evidence for organic matter while fossilization typically occurs over an extended time period as minerals slowly replace organic matter and the host rock lithifies under pressure the process documented here is instantaneous preservation of morphological and chemical biosignatures in impact events can provide snapshots of the ecology in environments that do not otherwise promote a diverse fossil record we suggest that this would provide a new strategy for identifying signs of possible early life on ancient mars where similar target conditions once existed

synchronizing terrestrial and marine records of environmental change across the eocene oligocene transition records of terrestrial environmental change indicate that continental cooling and or aridification may have predated the greenhouse icehouse climate shift at the eocene oligocene transition eot by ca 600 kyr in north america marine terrestrial environmental change asynchronicity is inferred from a direct comparison between the astronomically tuned marine eot record and published 40ar 39ar geochronology of volcanic tuffs from the white river group wrg sampled at flagstaff rim wyoming and toadstool geologic park nebraska which are type sections for the chadronian and orellan north american land mammal ages we present a new age model for the wrg underpinned by high precision 206pb 238u zircon dates from 15 volcanic tuffs including six tuffs previously dated using the 40ar 39ar technique weighted mean zircon 206pb 238u dates from this study are up to 1 0 myr younger than published anorthoclase and biotite 40ar 39ar data calibrated relative to fish canyon sanidine at 28 201 ma giving consideration to the complexities strengths and limitations associated with both the 40ar 39ar and 206pb 238u datasets our interpretation is that the recalculated 40ar 39ar dates are anomalously old and the 206pb 238u zircon dates more accurately constrain deposition 206pb 238u calibrated age depth models were developed in order to facilitate a robust intercomparison between marine and terrestrial archives of environmental change and indicate that i early orellan terrestrial cooling recorded at toadstool geologic park was synchronous with the onset of early oligocene antarctic glaciation and ii the last appearance datums of key chadronian mammal taxa are diachronous by ca 0 7 myr between central wyoming and nw nebraska

the oldest handaxes in europe fact or artefact abstract hominin presence is well documented in a number of early pleistocene and early middle pleistocene european localities however the evidence currently available indicates that acheulean handaxes spread in the fluvial basins of western europe during mis 11 400 kyr ago associated with homo heidelbergensis although a number of early middle pleistocene acheulean assemblages have been dated from mis 16 onwards for this reason the magnetostratigraphic dating in southeast spain of two archaeological localities the open air site of solana del zamborino sz and the rock shelter site of cueva negra del estrecho del quipar eq that put back the appearance of handaxes to the early middle pleistocene limit scott and gibert 2009 is of particular interest as the new ages suggest that h heidelbergensis was a contemporary of h antecessor that had the ability to produce levallois debitage and to control fire during the early middle pleistocene transition however we have detected a number of errors in the interpretation of the archaeological assemblage from the first site as well as striking discrepancies with the original faunal lists published for both localities with several large mammal species that are omitted or arbitrarily changed to make the assemblages consistent with the new ages deduced from magnetostratigraphy for this reason we suggest that 1 the finding of reverse polarity in the sediments sampled for paleomagnetism in sz may simply record one of the polarity reversals that took place during the brunhes chron although the use by scott and gibert 2009 of a composite stratigraphic column precludes correlating these levels with a specific reversal and 2 the fauna and tools of eq correspond to the late middle pleistocene sedimentary infillings of this karst site while the samples taken for paleomagnetism belong to a previous sedimentary cycle during the matuyama chron such interpretations would be in better agreement with the age estimates provided by biostratigraphy and also with the currently accepted chronology for the appearance of acheulean industries in western europe

andean tectonics as a cause for changing drainage patterns in miocene northern south america newdatafromneogenestratainnorthernsouthamericasuggestthatmiocenetectonisminthenortheasternandeswasresponsible for the genesis of the amazon river and changes in the drainage patterns of other major rivers such as the magdalena and the orinoco here we present a new model for the paleogeographic evolution of northern south america during the miocene in the early miocene a large part of the drainage of northwest amazonia was directed northward along the paleo orinoco river system to a deltainlakemaracaibo upliftoftheeasterncordillerainthelate middle miocene caused thefirst development of the amazon river however no connection with the atlantic was established and the amazon fed the paleo orinoco river system which drained toward the caribbean substantial andean uplift in the late miocene resultedinmajorchangesinpaleogeography theorinocochangedits course the amazon established a connection to the atlantic causing the drowning of carbonate platforms and the amazon caribbeanconnectionwasclosed thusthedrainageandpaleogeography ofnorthernsouthamericainthemiocenewerestronglycontrolled by tectonic movements in the northeastern andes

geochronology of type santacrucian middle tertiary land mammal age patagonia argentina mammal bearing lacustrine and tuffaceous sediments from three localities of the santa cruz formation type fauna of the santacrucian land mammal age in patagonia southern argentina are calibrated by radioisotope dating with the aid of magnetostratigraphy the strata range from about 17 6 ma to perhaps 16 0 ma and are thus of late early miocene age the santacrucian land mammal age ranges from about 18 0 ma to about 15 0 ma

spatial distribution of landslides triggered by the 2008 ms 8 0 wenchuan earthquake china abstract the ms 8 0 wenchuan earthquake of may 12 2008 is one of the most disastrous earthquakes in china the earthquake triggered tens of thousands of landslides over a broad area including shallow disrupted landslides rock falls deep seated landslides and rock avalanches some of which buried large sections of some towns and dammed the rivers the purpose of this study is to investigate correlations between the occurrence of landslides with geologic and geomorphologic conditions and seismic parameters over 56 000 earthquake triggered landslides with a total area of 811 km 2 are interpreted using aerial photographs and remote sensing images taken following the earthquake the spatial distribution of these landslides is analyzed statistically using both landslide point density lpd defined as the number of landslides per square kilometer and landslide area density lad the percentage of the area affected by landslides to determine how the occurrence of landslides correlates with distance from the epicenter distance from the major surface rupture seismic intensity and peak ground acceleration pga slope angle slope aspect elevation and lithology it is found that both lad and lpd have strong positive correlations with slope steepness distance from the major surface rupture and seismic intensity and that pre sinian schist and cambrian sandstone and siltstone intercalated with slate have the most concentrated landslide activities followed by the permian limestone intercalated with shale and devonian limestone statistical analyses also indicate that the major surface rupture has influence on the spatial distribution of landslides because lad and lpd are relatively higher on the hanging wall than on the footwall however the correlation between the occurrence of landslides with distance from the epicenter of the earthquake is complicated rather than a relatively simple negative correlation as found from other reported cases of earthquakes this is possibly due to complicated rupture processes of the earthquake

simulating the failure process of the xinmo landslide using discontinuous deformation analysis abstract the xinmo landslide slope in sichuan china was stable during the intensive wenchuan earthquake in 2008 but failed on june 24 2017 landslide debris buried xinmo village and blocked the songpinggou river at the slope toe this study aims to clarify the post failure behavior of the landslide using two dimensional discontinuous deformation analysis 2d dda the simulation results provide comprehensive information on the initiation and the evolution of the landslide the failure process determined by the dda correlates well with the seismic signal analysis results in addition the location of the calculated rock deposit is similar to that shown by the topographic map after the landslide the maximum rock velocity in the landslide is 65 4 m s therefore the impacts of the high velocity blocks and the buildings in xinmo village must be considered to simulate the burial of xinmo village by rocks and the transport of additional rocks across the songpinggou river this xinmo landslide study demonstrates that the dda accurately simulates the post failure behavior and determines the impact area of a landslide with complicated failure processes and topography

cueva negra del estrecho del rio quipar murcia spain a late early pleistocene hominin site with an acheulo levalloiso mousteroid palaeolithic assemblage abstract at cueva negra del estrecho del rio quipar biostratigraphy and palaeomagnetism indicate a time in the late early pleistocene i e somewhat before the matuyama brunhes boundary of 780 000 a 0 78 ma for the entire 5 m thick sedimentary fill excavated in the rock shelter from which there are hominin teeth cf homo heidelbergensis a rich palaeontological and palaeopalynological record demonstrating warm moist environmental conditions possibly mis 21 a fundamentally homogeneous artifact assemblage throughout the sedimentary deposit and evidence of fire at over 4 m depth a brief introduction to the site and the assemblage is offered palaeolithic artifacts were produced by three different reduction sequences because a an acheulian hand axe was flaked bifacially on a flat limestone cobble b several excavated chert flakes had been struck off small cores by recurrent flaking with one flake showing a facetted striking platform whilst two surface finds of small discoidal cores bear the broad central concave scar that in a levalloisian prepared core reduction sequence would correspond to centripetal removal of the final flake and c abundant small artifacts 25 60 mm mainly of chert reflect expedient removal of small flakes or fragments from cores by both unipolar and bipolar reduction techniques including many keeled pieces that could be residual cores which have notches slender spurs or beaks becs or a planoconvex slug like or limace shape all of which may be remnants of cores subjected to bipolar knapping in addition to very small pointed and awl like pieces and several fragments and flakes with steep abrupt mousteroid edge retouch and abundant knapping spalls and waste although the site had been interpreted conservatively in earlier publications as early middle pleistocene recent palaeomagnetic findings show that the entire sedimentary fill corresponds to the late early pleistocene somewhat over 780 000 a 0 78 ma an age which is acceptable from the standpoint of the biostratigraphical data among the aims of this paper are 1 a consideration of the palaeolithic assemblage in relation to local availability of raw materials of appropriate shapes and petrology for knapping in a palaeoenvironmental context far different from that of today 2 consideration of the implications for human cognitive and technological evolution in the european late early pleistocene and 3 a proposal that those considerations highlight practical methodological and theoretical drawbacks to the classical european interpretation of earlier palaeolithic chronologies from a perspective of typological sequences

early human evolution in the western palaearctic ecological scenarios abstract this review presents the themes of a special issue dealing with environmental scenarios of human evolution during the early pleistocene 2 6 0 78 ma mis 103 mis 19 and early middle pleistocene 0 78 0 47 ma mis 19 base of mis 12 within the western palaearctic this period is one of dramatic changes in the climates and the distribution of palaearctic biota these changes have played their role in generating adaptive and phyletic patterns within the human ancestry involving several species such as homo habilis homo georgicus homo erectus homo antecessor and homo heidelbergensis in the archaeological record these species include the oldowan mode 1 and acheulian mode 2 lithic technologies taphonomic considerations of palaeoecological research in hominin bearing sites are provided and evaluated syntheses are provided for north africa western asia the mediterranean basin britain and continental europe palaeoenvironmental reconstructions based on multidisciplinary data are given for ain boucherit ain hanech and el kherba in algeria dmanisi in georgia atapuerca cueva negra and the orce basin in spain monte poggiolo and pirro nord in italy pont de lavaud in france and mauer in germany the state of the art with the out of africa 1 dispersal model is reviewed a source sink dynamics model for palaeolithic europe is described to explain the morphological disparity of h heidelbergensis we will sometimes use the informal name heidelbergs and early neanderthals other aspects debated here are the selective value of habitat mosaics including reconstructions based on mammal and avian databases and the role of geological instability combined with topographic complexity this review is completed by addressing the question of whether the appearance of evolutionary trends within hominins is concentrated in regions of highest worldwide biological diversity biodiversity hotspots it is concluded that the keys for the activation of evolutionary change in hominins may have been geological instabilities and a shifting physiographical heterogeneity combined with high biodiversity and ecological interaction

a sliding block model for the runout prediction of high speed landslides a sliding block model is developed for predicting the runout of high speed slide like landslides based on the analysis of the dynamic mechanism of high speed landslides this model adopts the limit equilibrium analysis approach and incorporates mass dynamics and soil deformation into the calculation of soil movements the critical state is considered as the initial stress state and the interslice forces are obtained considering the equivalence of deformation energy it is possible applying this model to simulate the whole travel process of the soil mass from the onset of the landslide and to predict the travel speed of the soil mass and the hazard area of the landslide application of the model to the sale mountain landslide and the tianshui forging machine factory landslide in china gives reasonable results in comparison to the field observations the calculated results illustrate that i the fundamental causes of the high speed are the decline of the resultant friction force during sliding and the

derivation of isotope ratios errors and error correlations for u pb geochronology using 205pb 235u 233u spiked isotope dilution thermal ionization mass spectrometric data a comprehensive treatment of the derivation of u pb isotope ratios and their corresponding uncertainties from isotope dilution thermal ionization mass spectrometric measurements is presented standard parametric statistical methods of error propagation are utilized to convolve uncertainties associated with instrumental mass fractionation tracer subtraction blank pb and u subtraction and initial common pb correction derivations include errors and error correlations for total sample u pb and pb isotope ratios including radiogenic and initial common pb for two and three dimensional isochron calculations radiogenic u pb and pb isotope ratios for concordia and radiogenic model age calculations and the propagation of model age errors from radiogenic isotope ratios

a quasi three dimensional spring deformable block model for runout analysis of rapid landslide motion assessment of landslide hazard often requires a good knowledge of the landslide characteristics to investigate the dynamic runout process of the landslide across a 3d terrain a quasi three dimensional model using spring deformable block model is proposed on the assumption that the motion of landslides is continuous and variable the sliding body is divided into lots of columns the model is based on a stability analysis of landslides and allows the deformation of sliding body considering the force and moment equilibrium of deformable columns and the principle of conservation of energy a quasi three dimensional sliding body is simplified by a series of deformable blocks with different dimensions then the sliding body acceleration velocity and displacement formulas are established accordingly correlating relatively well with the discrete element method the present results are satisfactory in describing the dynamic process of landslides and predicting the impact areas of the post failure sliding body finally the present model is applied to analyze the sliding time the maximum velocity and displacement of the sliding body of jiweishan landslide in wulong chongqing southern china when comparing with distinct element method the model shows generally good agreement with them

metrology and traceability of u pb isotope dilution geochronology earthtime tracer calibration part i abstract mixed 235u 233u 205pb 202pb tracers for u pb isotope dilution isotope ratio mass spectrometry have been prepared under the auspices of the earthtime initiative the methods and results for the preparation and calibration of the u pb ratio and isotopic abundances are given and the various sources of uncertainty are discussed and quantified the accuracy of the earthtime u pb tracer isotopic composition can be traced back to si units via a series of assay and isotopic composition reference materials combined with the experiments described herein the parameters used in calculating u pb ratios and inferentially u pb dates have correlated uncertainties that result in a total uncertainty contribution to 206pb 238u dates of

prolonged impact of earthquake induced landslides on sediment yield in a mountain watershed the tanzawa region japan abstract to determine for how long a landslide affects sediment discharge the sediment yields of 15 check dam basins were compared with the time series of landslide distributions in a mountain basin in the tanzawa region central japan the distribution of sediment yield was quantitatively estimated from deposition in the sediment pools of check dams the relationship between the landslide history and sediment discharge in the nakagawa river basin was examined for an approximately 80 year period two major landslide events occurred during this period the 1923 kanto earthquake and the 1972 disaster caused by heavy rainfall the resulting trend in sediment discharge of the whole basin estimated using reservoir sedimentation in the miho dam at its base was nearly constant with high sediment discharge 2897 m 3 km 2 yr 1 in the intervening quarter century despite the recovery of vegetation on landslide areas in this period comparisons of the landslide distributions resulting from the two disasters the sediment yields of check dam basins and the sediment discharge of the whole basin indicate that recent sediment discharge contains landslide debris that was originated by the kanto earthquake that occurred over 80 years ago thus to understand high sediment discharge it is essential to investigate not only the current basin condition and recent events but also the landslide history of the basin for at least the previous 100 years

lithospheric thinning uplift and heat flow preceding rifting abstract conversion of lithosphere into asthenosphere provides an active mechanism of lithospheric thinning and formation of intracontinental rifts the movement of the lithosphere asthenosphere boundary lab considered as a phase change is determined by the solution of a stefan like problem the ascent of the lab and the surface heat flow perturbation are calculated for different boundary conditions at the base of the lithosphere the calculations show that the rate of lithospheric thinning is independent of heat conduction across the lithosphere when the temperature increases at the lab the amplitude of thinning is also independent of the thickness of the lithosphere lithospheric thinning to the base of the crust could thus take place rapidly if a temperature perturbation on the order of 250 k is maintained at the lab the characteristic time depends strongly on the latent heat and on the difference between the geothermal and phase transition temperature gradients it is estimated to range between 1 and 30 m y this mechanism of lithospheric thinning appears to be compatible with petrological and geochronometric data on temporal changes in the depth of origin of magmas from the east african rift

simulating a mining triggered rock avalanche using dda a case study in nattai north australia abstract this study numerically simulated the failure process of a mining induced landslide at nattai north australia results obtained using discontinuous deformation analysis dda matched the conceptual failure process suggested by local geologists and the observed maximum run out distance the maximum velocity of the sliding rocks exceeded 40 m s computational results showed that the slope with inward sub horizontal bedding planes and sub vertical discontinuities remained stable if the mining induced high principle stresses did not fracture the rocks near the slope toe failure of the rocks near the toe of the slope was a key causal factor in the subsequent landslide this paper presents the first numerical simulation of the post failure behavior of the mining induced landslide at the nattai north site it also represents the first dda simulation to clarify the chain reaction of a mining induced landslide and demonstrate its applicability in such investigations

evaluating the impact of homo carnivore competition in european human settlements during the early to middle pleistocene fossil remains and the technological complexes recorded in archaeological sites suggest that the human presence in europe late in the early and middle pleistocene was discontinuous moreover competition for meat with other secondary consumers could have delayed the human dispersal through europe however evaluation of the extent competition intensity among secondary consumers suggests this influenced the discontinuity of the human settlement of europe between 1 1 and 0 2 ma using a mathematical model we estimate the amount of biomass available in a community for secondary consumers the amount of available biomass is subsequently distributed among the guild of secondary consumers according to their requirements and prey preferences indexes that quantify the competition intensity among secondary consumers to compare the conditions in different paleoecosystems show that the competition intensity late in the early pleistocene early in the middle pleistocene and late in the middle pleistocene does not support the view that an increase in competition intensity constrained the expansion of human populations early in the middle pleistocene somewhat paradoxically the lowest competition intensity is estimated to have occurred early in the middle pleistocene most likely because of an increase in the number of large herbivore species and a decrease in the number of secondary consumers the early pleistocene paleoecosystems supported higher competition intensity than the middle pleistocene ecosystems likely because of the different configuration in the food webs of these two periods the early and middle pleistocene

early european mode 2 and the stone industry from the caune de l arago s archeostratigraphical levels p abstract the stratigraphical complex of the caune de l arago cave site france pyrenees orientales has been systematically excavated for over 40 years in 1981 foraging in the deposits revealed a 15 m thick quaternary infill with artefacts present throughout the stratigraphy all the way down to the basal stalagmitic floor 0 69 ma the infill most of which is correlated to mis 14 13 and 12 has yielded numerous distinct occupation floors exceptionally rich stone implements and animal fossils while some of the levels have also yielded hominin remains attributed to homo heidelbergensis over the years intensive interdisciplinary studies have contributed to defining the characteristics of these middle pleistocene occupations recently excavations have reached the so called p levels attributed to a series of occupation floors accumulated during short term stays by hominin groups during a cold dry phase of mis 14 artefact bearing levels are found intercalated between archeologically sterile sediments relatively rich in carnivore remains among the numerous large pleistocene mammals identified in the p levels horse reindeer and bison are most frequent in artefact yielding floors while argali brought into the cave by carnivores bear and panther remains are common in intercalating levels the study of the p levels stone assemblage provides new information about raw material selectivity technological behaviour and typological characteristics for one of the oldest known western european mode 2 industries it is interesting to consider the precise handiwork and care with which raw materials were selected for the confection of the fine quality instruments typical of the p levels assemblages whose acheulian character is underlined by a relative abundance of symmetrical and remarkably well worked handaxes the p levels industries seem to bear witness to long acquired technological capacities inherited perhaps from earlier african or eurasian populations

elementary theory of bed sediment entrainment by debris flows and avalanches 1 analyses of mass and momentum exchange between a debris flow or avalanche and an underlying sediment layer aid interpretations and predictions of bed sediment entrainment rates a preliminary analysis assesses the behavior of a coulomb slide block that entrains bed material as it descends a uniform slope the analysis demonstrates that the block s momentum can grow unstably even in the presence of limited entrainment efficiency a more detailed depth integrated continuum analysis of interacting deformable bodies identifies mechanical controls on entrainment efficiency and shows that entrainment rates satisfy a jump condition that involves shear traction and velocity discontinuities at the flow bed boundary explicit predictions of the entrainment rateeresult from making reasonable assumptions about flow velocity profiles and boundary shear tractions for coulomb friction tractions predicted entrainment rates are sensitive to pore fluid pressures that develop in bed sediment as it is overridden in the simplest scenario the bed sediment liquefies completely and the entrainment rate equation reduces toe 2 1gh1 cos 1 1 v 1 where is the slope angle 1 is the flow s coulomb friction coefficient h1 is its thickness 1 is its degree of liquefaction and v 1is its depth averaged velocity for values of 1ranging from 0 5 to 0 8 this equation predicts entrainment rates consistent with rates of 0 05 to 0 1 m s measured in large scale debris flow experiments in which wet sediment beds liquefied almost completely the propensity for bed liquefaction depends on several factors including sediment porosity permeability and thickness and rates of compression and shear deformation that occur when beds are overridden

the blessing of a great flood differentiation of mortality patterns in the large mammal record of the lower pleistocene fluvial site of untermassfeld germany and its relevance for the interpretation of faunal assemblages from archaeological sites the site of untermassfeld germany documents flood catastrophes of the werra river ca 1 myr years ago although all vertebrate individuals of an equivalent thanatocoenosis in principle underwent the same taphonomic history different mortality patterns have been observed for different animal species it can be demonstrated that mortality patterns preserved by the fossil record are heavily affected by the physiological capability and ethology of a particular species as well as by the particular taphonomic situation prevailing at the location of final deposition against this background mortality patterns for the interpretation of faunal assemblages from archaeological sites are discussed in a broader context

mammalian faunas ecological indices and machine learning regression for the purpose of paleoenvironment reconstruction in the miocene of south america abstract reconstructing paleoenvironments has long been considered a vital component for understanding community structure of extinct organisms as well as patterns that guide evolutionary pathways of species and higher level taxa given the relative geographic and phylogenetic isolation of the south american continent throughout much of the cenozoic the south american fossil record presents a unique perspective of mammalian community evolution in the context of changing climates and environments here we focus on one line of evidence for paleoenvironment reconstruction ecological diversity i e the number and types of ecological niches filled within a given fauna we propose a novel approach by utilizing ecological indices as predictors in two regressive modeling techniques random forest rf and gaussian process regression gpr which are applied to 85 extant central and south american localities to produce paleoecological prediction models faunal richness is quantified via ratios of ecologies within the mammalian communities i e ecological indices which serve as predictor variables in our models six climate habitat variables were then predicted using these ecological indices mean annual temperature mat mean annual precipitation map temperature seasonality precipitation seasonality canopy height and net primary productivity npp predictive accuracy of rf and gpr is markedly higher when compared to previously published methods mat map and temperature seasonality have the lowest predictive error we use these models to reconstruct paleoclimatic variables in two well sampled miocene faunas from south america fossiliferous layers fl 1 7 santa cruz formation early miocene santa cruz province argentina and the monkey beds unit villavieja formation middle miocene huila colombia results suggest general concordance with published estimations of precipitation and temperature and add information with regards to the other climate habitat variables included here ultimately we believe that rf and gpr in conjunction with ecological indices have the potential to contribute to paleoenvironment reconstruction

new 40ar 39ar stratigraphic and palaeoclimatic data on the isernia la pineta lower palaeolithic site molise italy abstract the archaeological deposits of isernia la pineta are a milestone in the european context being composed of very rich and large sized occupation layers the archaeological remains are characterised by the use of anvils in a very opportunistic and rapid way to produce a large number of flakes and residual cores usually of very small size the lithic instruments are associated with remains of large mammals which give a clear indication of the diet they are represented by bison schoetensacki freudenberg stephanorhinus hundsheimensis toula elephas palaeoloxodon namadicus falconer e cautley ursus deningeri von reichenau hippopotamus cf antiquus desmarest sus scrofa l hemitragus cf bonali harle e stehlin megaceroides solilhacus robert cervus elaphus cf acoronatus beninde dama dama cf clactoniana falconer capreolus sp and panthera leo fossilis von reichenau the rodent fauna is represented by clethrionomys sp pliomys episcopalis mehely pliomys lenki heller microtus aff arvalis pallas microtus brecciensis gieber microtus terricola gr multiplex subterraneus and arvicola cantiana hinton the insectivores are talpa sp sorex cf runtonensis hinton and crocidura sp two main archaeological layers have been identified the lower one sector i layer 3c rests on a phytoclastic travertine passing laterally to a phytohermal travertine which generated a small step in the watercourse a sandy silt layer of lacustrine environment layer 3b deposited inside travertine pools and very limited phytostromatolitic travertine sediments cover this layer the second occupation layer layer 3a rests on these sediments as well as on the travertines cross bedded fine gravelly sands cover the deposits and are interlayered with tuffs very rich in pyroxene and sanidine the latter gave 40ar 39ar ages of 610 10 and 606 2 ka 2 error this layer is covered by cross bedded gravels weathered by a thick alfisols with a well expressed bt horizon the uppermost part of the series is composed of gravels and colluvia containing another pyroclastic layer sanidines of this layer yield scattered ar ar ages with a main population at about 504 14 ka a maximum age of 474 3 ka is inferred for this layer the isernia travertines are not associated with hot water springs and indicate that the area was frequented at the end of an interglacial period the new ages demonstrate that the human frequentation occurred at the beginning of the middle pleistocene

evolution of the hawaiian emperor swell thinning of the oceanic lithosphere abstract the thinning process of the oceanic lithosphere is discussed with special reference to the evolution of the hawaiian emperor swell according to the hypothesis employed in this study the lithosphere increases its thickness depending upon the heat balance between the input heat flow from the asthenosphere cooling by thermal conduction within the lithosphere and release or absorption of latent heat at the lithosphere asthenosphere boundary the input heat flow from the asthenosphere controls this process although under ordinary conditions the lithosphere thickens with time an extra high heat flow thins the lithosphere a source of excess heat flow may be recognized as a hotspot near hawaii based on this theory thinning and thickening processes of the pacific plate beneath the hawaiian emperor swell are examined to evaluate the change in lithospheric thickness in more detail the residual gravity anomalies around the hawaiian emperor swell are calculated using available data or both gravity anomalies and crustal structures derived from explosion seismology from these data the lithospheric thickness beneath hawaii is estimated to have been decreased by about 20 km extra high heat flux from the asthenosphere in the order of 420 mw m 2 10 hfu is required in this region theoretical predictions of temporal variations of ocean bottom topography surface heat flow gravity anomalies and plate thickness along the hawaiian emperor swell fit well with the observations

estimating rates of debris flow entrainment from ground vibrations debris flows generate seismic waves as they travel downslope and can become more dangerous as they entrain sediment along their path we present field observations that show a systematic relation between the magnitude of seismic waves and the amount of erodible sediment beneath the flow specifically we observe that a debris flow traveling along a channel filled initially with sediment 0 34 m thick generates about 2 orders of magnitude less spectral power than a similar sized flow over the same channel without sediment fill we adapt a model from fluvial seismology to explain this observation and then invert it to estimate the level of bed sediment and rate of entrainment beneath a passing series of surges our estimates compare favorably with previous direct measurements of entrainment rates at the site suggesting the approach may be a new indirect way to obtain rare field constraints needed to test models of debris flow entrainment

dynamic modelling of entrainment in rapid landslides entrainment of path material is an important feature of many rapid landslides the associated increases in volume and changes in flow character can significantly influence mobility a simple material entrainment algorithm based on the assumption of natural exponential growth with displacement has been incorporated into a new computer model designed to simulate rapid landslide motion across 3d terrain the user controls the growth rate and can also implement a change in rheology at the onset of entrainment a hypothetical example is used to demonstrate the influence of the mass and momentum transfer assumptions a back analysis of the 1999 nomash river landslide is included to show that the simple model is capable of simulating the bulk characteristics of a complex event involving substantial entrainment key words landslides debris flows rock avalanches entrainment erosion dynamic modelling

oldest human expansions in eurasia favouring and limiting factors 1 introductionon november 26e28 2008 an international conference wasorganised at the museum national d histoire naturelle paris france the topic was the oldest human expansions in eurasia under theaspect of the factors which could favour or limit the humansettlements while fossil human remains are scarce in eurasia lithicassemblages suggest at least two phases of human settlement or and techno cultural spread from africa to eurasia the rst one attested by mode 1 lithic industries is observed at dmanisi georgia at 1 8 ma in asia in china and pakistan around 2 ma and in europe for example in spain since 1 2e1 4 ma at orce atapuerca in italy monte poggiolo ca 1 ma pirro nord at least1 3 ma and in france pont de lavaud le vallonnet around 1 ma some dates in china and indonesia support the idea of earliersettlementsincontinentalandislandasiathanineurope whiletheoldest tool kit in africa dates to 2 6 ma kada gona ethiopia a second phase is marked by the appearance of new tools especially handaxes and cleavers these large tools do occur inafrica around 1 6e1 7 ma konso ethiopia kokiselei kenya andaround 1 4e1 2 ma in the middle east ubeidiya israel they areconsideredasthe rstindicatorsofacheuliantradition ormode2 consisting in shaping large tools on akes or blocks these toolsappear outside africa with different time lags according togeographical areas in asia the rst ones occur around 1 2 ma isampur india and then become more signi cant with anincreasing number of sites around 800 ka in eastern asia e china and south eastern asia ngebung java in western and southerneurope acheuliansitesonlyappeararound600e700ka asattestedbythe recent discoveriesin centreregion france la noira in chervalley and they become more numerous from 500 ka onwards inspain atapuerca galeria ambrona in italy visogliano castel diguido in northern and southern france somme river terraces caune de l arago in the european continent assemblages withbifaces characteristic of acheulian onlyoccurin a geographical areastretching from southern europe to great britain however theyare lacking in central europe and the rhine river is considered asa frontier but they do exist in the caucasus near the central asianborder while they are unknown further east in tadjikistan these two waves of populating probably include numerousarrivals and we do not know whether these arrivals led each timeto a permanentsettlement particularlyif the hominin groups weresmall and geographically dispersed this time lag between asia and europe regarding the peoplingphases and their consequences is debated today within the scien ti c community what could be the migratory paths from africa toboth asia and europe or from africa to asia then to europe whomoved homo antecessor homo heidelbergensis were there somecontacts between distinct human groups rather than shiftingpopulations these questions also concern the diffusion modalitiesof technical traditions and the effect of climatic and environmentalconditions on human movements the latter could explain chro nological lags and restriction of human settlements to some areasonly however it has to be kept in mind that convergencephenomena could also happen at a regional scale in the tool kits this may be the case for acheulian people the present state of knowledge on the earth s climatic storyduringthelasttwomillionyearsshowslocalphenomenacombinedto global changes for example increase of glaciations around800ka whenclimaticcyclesshiftedtothe100kaperiodicity astheeccentricity parameter of terrestrial orbit became more importantthan the obliquity of earth s axis earlier periodicity of 41 ka mis20 characterised by strong marine regression took place at thesame time as the matuyamaebrunhes geomagnetic inversion 780 ka and is considered as an accurate chronological marker recent results of various research teams contribute to builta more complete and precise picture of the past the betterknowledge of the palaeoenvironment allows a new appraisalregarding the spread of technical behaviours in relation to theenvironmental context highlighted by new issues concerningafrica some major questions were discussed during the conference 1 the geographical dispersal of each type of lithic industry 2 the chronological gaps in the hominin settlements in thevarious areas of eurasia 3 the periods when climatic or topographic variations had animportant role favouring or limiting the human expansion insome regions

climatic and ecologic changes during miocene surface uplift in the southern patagonian andes abstract the up to 4 km high southern patagonian andes form a pronounced topographic barrier to atmospheric circulation in the southern hemisphere westerlies and cause one of the most drastic orographic rain shadows on earth geologic data imply that this climatic pattern has been established or significantly enhanced during miocene surface uplift of this andean segment we report evidence for important climatic and ecologic changes in the eastern foreland of the patagonian andes that appear to be the result of this uplift to provide constraints on miocene plant ecosystems and precipitation in the eastern leeward foreland of the patagonian andes we determined carbon and oxygen isotope values of pedogenic carbonate nodules from a 500 m thick section of the continental santa cruz formation the age of these deposits was constrained by ar ar dating of intercalated tuffs which range from 22 to 14 ma at 16 5 ma the 13 c values increase by 3 the 18 o values decrease by 2 and the scatter in the oxygen isotope data increases significantly we interpret these changes as the consequence of 1 km surface uplift in this andean segment from the 18 o values and increased aridity to its east from the 13 c values and the increased scatter in the 18 o values sediments overlying the santa cruz formation are very limited in extent and volume and dominated by coarse conglomerates related to pleistocene and older glaciations it thus seems that by 14 ma deposition in the eastern foreland of the southern patagonian andes had essentially ceased as the result of rain shadow formation

palaeoecological implications of the mid pliocene faunal turnover in the pampean region argentina abstract known since darwin s time the plio pleistocene succession exposed at the chapadmalal sea cliffs have provided abundant mammal remains even though palaeobiological studies are scarce different authors have identified several assemblages in this stratigraphic interval of homogeneous lithology which records an important mid pliocene faunal turnover dated at ca 3 3 ma this paper examines the palaeoecological characteristics and the regional importance of this faunal turnover 37 of all genera and 53 of all species became extinct between the older chapadmalalan and the younger barrancalobian chronostratigraphic units a level that is actually higher than the percentage of genera extinct at the global scaled cretaceous tertiary extinction the palaeoecological analysis permits to infer that the species rich chapadmalalan fauna seems to have been very balanced from the trophic energetic point of view on the other hand the succeeding and less explored barrancalobian represents a relatively poorer environment highly unbalanced in terms of the herbivore carnivore relationships due mainly to the absence of medium to large mammal and bird carnivores the cause of the mid pliocene faunal turnover is still debatable climatic change has been traditionally related to this faunal turnover stratigraphically an impact event dated at ca 3 3 ma is recorded in the succession this event coincides with a change in the deep sea stable isotopic record reflecting a sudden change in climate and ocean circulation this suggests that the impact might have induced regional faunal extinctions correlation with other areas different from the coast of buenos aires province is needed to establish the geographic scale of the extinction new fossils will provide a more complete and accurate picture of this remarkable faunal turnover

a 3 3 ma impact in argentina and possible consequences enigmatic glassy materials escorias and red bricklike materials tierras cocidas occur at a restricted stratigraphic level the top of the chapadmalal formation materials from one locality near mar del plata are attributed to a mid pliocene impact event with a radiometric and magnetostratigraphic age of 3 3 million years ago ma an extinction of endemic fauna including the glyptodonts and flightless cariamid birds correlates with the unit containing the impact glasses moreover the age of the glasses is coincident within dating uncertainties with a pulselike change in the oxygen isotope marine record in the atlantic and pacific oceans just before the late pliocene deterioration of the climate

positive feedback and momentum growth during debris flow entrainment of wet bed sediment debris flows typically occur when intense rainfall or snowmelt triggers landslides or extensive erosion on steep debris mantled slopes the flows can then grow dramatically in size and speed as they entrain material from their beds and banks but the mechanism of this growth is unclear indeed momentum conservation implies that entrainment of static material should retard the motion of the flows if friction remains unchanged here we use data from large scale experiments to assess the entrainment of bed material by debris flows we find that entrainment is accompanied by increased flow momentum and speed only if large positive pore pressures develop in wet bed sediments as the sediments are overridden by debris flows the increased pore pressure facilitates progressive scour of the bed reduces basal friction and instigates positive feedback that causes flow speed mass and momentum to increase if dryer bed sediment is entrained however the feedback becomes negative and flow momentum declines we infer that analogous feedbacks could operate in other types of gravity driven mass flow that interact with erodible beds the mechanisms by which debris flows acquire mass and momentum as they entrain material are unclear large scale experiments suggest that the pore pressure of wet bed sediment increases as the flow moves over the bed leading to reduced friction and progressive scouring of the base

entrainment of debris in rock avalanches an analysis of a long run out mechanism many rock avalanches entrain and liquefy saturated soil from their paths evidence for this includes mud displaced from the margins of rock avalanche deposits substrate material smeared along the base of deposits extrusion of liquefied soil upward through the deposits and increases of volume a hypothesis first suggested in 1881 and since reinforced by several authors suggests that entrainment of substrate material increases mobility although the process has been discussed in the literature for more than 100 years few detailed and quantitative descriptions exist the main purpose of this paper is to describe two recent cases from british columbia canada where rockslides entrained substrate on a very large scale influencing the character of the events estimated volume balance curves based on detailed field mapping are provided for both cases dynamic analyses are carried out using a numerical model and using the same set of rheological parameters the mechanism of material entrainment and displacement is discussed the data suggest that rapid rock failures entraining very large quantities of saturated substrate material represent a special type of landslide transitional between rock avalanche and debris avalanche many rock avalanches can thus be seen as end members of a continuum of phenomena involving rock failure followed by interaction with saturated substrate

the early acheulean technology of barranc de la boella catalonia spain abstract since 2007 excavations at barranc de la boella tarragona catalonia spain have revealed three localities with rich archaeo paleontological assemblages la mina el forn and pit 1 palaeontology palaeomagnetism and cosmogenic analyses have dated these localities to close to 1 ma the presence of mammuthus meridionalis hippopotamus antiquus stephanorhinus cf hundsheimensis mimomys savini and victoriamys chalinei stand out in the sample of macro and micro mammals the lithic assemblages from the three sites are made up of percussion cobbles choppers chopper cores cores simple flakes and some retouched flakes mainly denticulates and notches in the case of the el forn and pit 1 localities two large cutting tools have been recovered a cleaver like tool and a pick made of hard wearing schist the lithic assemblage of pit 1 which includes several refitting lithic sets is closely associated with the remains of a young adult mammuthus meridionalis in a clear butchering site context this evidence suggests that barranc de la boella is the oldest european early acheulean site and one of the oldest butchering site on the subcontinent during the late early pleistocene the study of the variability among these three localities in similar environmental conditions together with information from other sites are discussed in order to gain further knowledge about the appearance of the acheulean in europe and its continuity or discontinuity in relation to pre existing technologies

neogene stratigraphy paleoceanography and paleobiogeography in northwest south america and the evolution of the panama seaway abstract the atrato basin in the pacific coastal region of nw south america colombia exhibits stratigraphic and biostratigraphic characteristics similar to other neogene pacific coastal basins of southern central america and northern south america an evaluation of the neogene stratigraphy and foraminiferal biostratigraphy with emphasis on paleoceanographic and paleobiogeographic phenomena indicate the following 1 previous to the middle miocene well aerated deep and open oceanic conditions and free and active water circulation prevailed along the steep continental margins of nw south america 2 during the early middle miocene right after the neogene hiatus nh 2 15 2 ma tectonic disturbances triggered the initial uplift of the panama sill bottom water circulation foraminiferal and sedimentation changes are observed in both the pacific and caribbean coastal areas of nw south america 3 during the middle miocene coinciding with the neogene hiatus nh 3 12 9 11 8 ma an abrupt paleobathymetric change from lower to middle bathyal depths indicates a major uplift of the panama sill to about 1000 m reflecting the middle miocene tectonic disturbances in nw south america 4 during the late middle miocene immediately following this uplift a distinctive pacific benthic foraminiferal fauna abruptly appeared and extended from ecuador to california because these assemblages do not occur in the adjacent caribbean region a circulation barrier between the atlantic and pacific oceans as a result of intensification of the cool marginal california current is proposed anoxic middle to upper bathyal environments prevailed under well aerated cool surface waters in the pacific coastal areas of nw south america 5 during the latest miocene immediately following the neogene hiatus nh 6 7 0 6 3 ma surface water circulation between the caribbean and the pacific was re established and the previous influence of the california current disappeared a rapid filling and shallowing of the basin to mostly neritic depths is indicated along the pacific and caribbean coastal basins of colombia as well as a progressive increase in similarity between the coastal pacific and caribbean benthic biotas this shallowing in the early late miocene also appears to have been associated with the earliest terrestrial interchange of ground sloths to north america and raccoons and their allies to south america 6 immediately following early pliocene time the panamanian isthmus became completely emergent providing a terrestrial environment favourable for intermingling of terrestrial faunas and floras between north and south america i correlate this pliocene uplift with the neogene hiatus nh 8 3 7 3 1 ma four regional unconformities associated with tectonic disturbances in the nw corner of south america have also been recognized and correlated with neogene hiatuses recorded from the oceans early middle miocene middle miocene late miocene and early pliocene

constraints on unroofing rates in the high himalaya eastern nepal thermobarometric data for samples across the main central thrust zone in eastern nepal show an inversion in temperature but not in pressure these data have been interpreted to represent a portion of the paleogeotherm at the time of main central thrust deformation a 40ar 39ar age on hornblende closure temperature tc 500 50 c constrains the timing of this deformation to be 21 0 2 ma the 40ar 39ar ages of other minerals muscovite tc 350 c age t 12 0 0 2 ma k feldspar tc 220 c t 8 0 0 2 ma from the same location further constrain the cooling history of this region together the geochronologic and thermobarometric data yield an average unroofing rate of 1 2 0 6 mm yr for the high himalaya of eastern nepal simple thermal models show that these geochronologic and thermobarometric data are consistent with a wide range of different initial geotherms applied boundary conditions and magnitude of radiogenic heat production the variation through time of the unroofing rates can only be poorly constrained however the unroofing histories were found to be largely insensitive to the details of the assumed initial geotherm fairly sensitive to the magnitude of radiogenic heat production and extremely sensitive to the nature of the boundary conditions applied below the fault zone this study underscores the difficulty in constraining uplift histories on the basis of cooling rates even when thermobarometric data are available to supplement geochronologic constraints on the cooling history of the region

a model for the runout analysis of rapid flow slides debris flows and avalanches runout analyses are used for risk assessment and design of remedial measures against rapid landslides such as debris flows debris avalanches rockslide avalanches large scale liquefaction failure

effects of entrainment phenomenon on the rapid and long runout movement of landslides in wenjia gully sichuan china as a common phenomenon in landslides entrainment of loose bed material along the sliding path can enhance both the volume and mobility of the sliding mass posing a great threat to the life and property safety of people in the affected area for the purpose of revealing the mechanism of entrainment phenomenon of sliding material in the runout process a dynamic slice based model was firstly proposed in the present study in this model the motion of landslide body is assumed to follow the rheological law proposed by voellmy additionally through voellmy model the increase in kinetic energy mass and volume of landslide body and entrainment depth caused by the entrainment phenomenon were taken into consideration subsequently on the basis of the dynamic slice based model back analyses were performed on the wenjia gully landslide the effect of entrainment phenomenon on the post failure motion was analyzed the calculated results shows that the travel distance obtained from proposed model is closer to field data than that resulted from scheidegger s empirical method moreover the peak value of the maximum velocity calculated by this model is in good agreement with that get from the dynamic analysis model dan3d when considering the entrainment phenomenon the volume of sliding mass increases greatly in post failure motion this paper provides a new method for analyzing the entrainment phenomenon in landslide motion

a review of statistical chronology models for high resolution proxy based holocene palaeoenvironmental reconstruction abstract in this paper we explain the background workings and results obtained from three recently developed statistical age depth models implemented in freely available general purpose software packages bpeat oxcal and bchron these models aim to reconstruct the sedimentation rate in a single core typically lake peat or ocean given a limited number of scientific date estimates usually radiocarbon and fixed depths most importantly they provide a suitably qualified estimate of the uncertainty in the age depth chronology and thus can be used in a variety of applications we perform a large data driven study of the three models and discuss their general utility in chronology construction for palaeoenvironmental research

landslides induced by the 2008 wenchuan earthquake sichuan china the 2008 wenchuan earthquake with a magnitude of mw 7 9 induced numerous slope movements on the hanging walls of fault surface ruptures and on steep inner valleys along the minjiang river landslide moving directions showed preferred orientations normal to the fault ruptures indicating the effect of the directivity of the seismic wave the most common landslides were of carbonate rocks which are easily dissolved and decrease the contact surfaces the largest non volcanic landslide in history was induced in bedded dolomite by the earthquake and was preceded by gravitational deformation with ridge top depressions valley fill materials were mobilized at 36 locations probably by pore water pressure build up

more than three million years of community evolution the temporal and geographical resolution of the plio pleistocene western eurasia mammal faunas abstract in this study we collected in a database faunal lists for more than 800 eurasian fossil localities yielding large mammal remains so as to produce continental level ecologic evolutionary units eurasian paleocommunities ea pcoms via bootstrapped cluster analysis ea pcoms are meant to represent taxonomically distinct assemblages of species ea pcoms allow the evolution of large mammal assemblages to be traced both in time and space this latter attribute spatial resolution represents the most important innovation here and contrasts with classic biochronologic schemes from which ea pcoms clearly depart the merits and limitations of this innovation are discussed in detail

flake modification in european early and early middle pleistocene stone tool assemblages early and early middle pleistocene archeological sites provide data about human dispersals into europe from at least 1 2 ma up to now the fragmentary archeological record indicated only sporadic hominin presence with punctated migration waves not necessarily leading to colonization we consider an alternative demographical picture in which hominin presence in europe could have been sustained from this time this paper explores the possibility that early hominin groups confronted different landscapes by adapting their technology to changing ecosystems innovative technological achievements were developed into new forms out of potential existing within the variability of early stone industries leading to the production of a more diversified toolkit among these innovations the increased secondary knapping of flakes points to conceptually more complex production sequences this paper proposes a comparative view of secondary knapped flakes from some key early middle pleistocene sites in order to explore the hypothesis of demographical stability in western europe from this time

reply to the comment on chronostratigraphy and paleoclimatology of the lodeve basin france evidence for a pan tropical aridification event across the carboniferous permian boundary by michel et al 2015 palaeogeography palaeoclimatology palaeoecology 430 118 131 abstract michel et al 2015 present new radioisotopic age estimates coupled with paleosol data from the lodeve basin france that indicate a pennsylvanian permian trend toward aridity that is similar to trends seen in other western equatorial basins across tropical pangaea in their comment pochat and van den driessche 2015 call into question these newly published u pb zircon chemical abrasion isotope dilution thermal ionization mass spectrometry ca idtims age estimates from volcanic ash layers preserved within the lodeve basin furthermore pochat and van den driessche 2015 reject our assertion that the rates of sediment accumulation for the carboniferous permian strata in the lodeve basin are in need of recalculation as a result of the new geochronological dates finally pochat and van den driessche 2015 suggest that the paleosol data presented in michel et al 2015 do not provide meaningful proxies of paleoclimate change and reassert the position presented in pochat and van den driessche 2011 that sedimentary strata are not strongly affected by paleoclimatic change compared with the influence of tectonic processes of the lodeve basin

calculating dense snow avalanche runout using a voellmy fluid model with active passive longitudinal straining a quasi one dimensional dense snow avalanche model has been developed to predict avalanche runout and flow velocity in a general two dimensional terrain the model contains three different dense snow avalanche flow laws these are 1 a voellmy fluid flow law with longitudinal active passive straining 2 a voellmy fluid flow law advanced by russian researchers in which the coulomb like dry friction is limited by a yield stress and 3 a modified criminale ericksen filby fluid model proposed by norwegian researchers the application of the voellmy fluid law with active passive straining to solve practical avalanche dynamics problems is evaluated by applying the model to simulate laboratory experiments and field case studies the model is additionally evaluated by comparing simulation results using the russian and norwegian models in a final analysis the influence of the initial conditions on avalanche runout is investigated we conclude that the model resolves many of the shortcomings of the voellmy salm model which is traditionally used in switzerland to predict avalanche runout furthermore since the model contains the three well calibrated parameters of the swiss guidelines on avalanche calculation it can be readily applied in practice we discuss why we believe the russian and norwegian models are not ready for practical application finally we show that many problems remain such as the specification of the initial release conditions we conclude that numerical models require a more detailed description of initial fracture conditions

phase changes and thermal subsidence in intracontinental sedimentary basins summary a model of tectonic subsidence is developed to explain the late acceleration of subsidence observed in some intracratonic sedimentary basins the proposed mechanism combines the effect of thermal contraction of an initially hot lithosphere with the effect of a subcrustal phase transformation that moves under changing pressure and temperature conditions the subsidence following a sudden change in temperature at the base of the lithosphere is calculated the calculations show that 1 phase changes if present and activated contribute substantially to the subsidence of sedimentary basins 2 because the effect of phase change is delayed subsidence accelerates after a time on the order of 20 myr and 3 the duration of the subsidence is on the order of 100 to 150 myr during the late stages of subsidence the phase change is the dominating mechanism an application to the michigan basin is presented the calculated sediment accumulation history fits the record well when the effect of sea level changes is included in the model

movement of the lithosphere asthenosphere interface in response to erosion of thickened continental lithosphere a moving boundary approach summary models of retrograde metamorphism in many orogenic belts are based on crustal thickening and erosion of continental lithosphere the pressure and temperature evolutions in such models are generally obtained by solving the advection diffusion equation with the lithosphere asthenosphere boundary lab either fixed at a specified depth or moving downwards at the same rate as erosion from the surface however this boundary is defined as a solid partial melt boundary in many geophysical interpretations in the present work we discuss a solution of the above problem considering the lab as a phase boundary that moves this solution is obtained by the fourier series approach for a general case of surface erosion and basal heat transport the results obtained for different models of crustal thickening show a significant movement of the lab in response to erosion from the surface a corresponding variation in the lithospheric thickness is also a significant result of this analysis the earlier notion of a fixed base lithosphere seems to be a good approximation when analysing metamorphic data as we obtain nearly the same temperature profile in the crust as after including the lab motion effect however the erosion of thickened crust is found to affect the lithospheric growth these results indicate that metamorphic data sampling the thermal structure of the upper lithosphere do not preserve the signatures of such boundary motion

one million years of cultural evolution in a stable environment at atapuerca burgos spain abstract the present paper analyses the evidence provided by three sites sima del elefante gran dolina and galeria located in the trinchera del ferrocarril of the sierra de atapuerca these three sites are cave infillings that contain sediments deposited from approximately 1 2 ma to 200 kyr pollen herpetofauna and small and large mammal remains are used as proxies to obtain a general picture of the environmental changes that occurred at the sierra de atapuerca throughout the one million year period represented at these sites similarly cultural changes are tracked analyzing the evidence of human behavior obtained from the study of several bone and lithic assemblages from these three sites at least three periods with different cultural features involving technology subsistence and behavior are determined from the available evidence the first two periods correspond to the mode 1 technology and homo antecessor the first is dated around 1 2 to 1 0 ma and reflects opportunistic behavior both in technology and subsistence the second period is around 800 kyr bp mode 1 technology is still maintained but subsistence strategies include systematic hunting and the use of base camps the third period is dated between 500 ka and 200 ka and corresponds to the mode 2 technology and the acquisition of directional hunting and other organizational strategies by homo heidelbergensis a transition from mode 2 to mode 3 seems to appear at the end of this time range and may reflect the early phases of a fourth cultural change with regard to the environment our main conclusion is that there was an absence of extremely harsh conditions at atapuerca throughout this time period the presence of mediterranean taxa was constant and the dominant landscape was a savannah like open environment probably with small forest patches an alternation of mediterranean and mesic species as the dominant component of the tree storey was induced by the climatic cycles and steppes spread across the landscape during the drier periods in any case it is not possible to establish clear cut off points separating entirely different environmental episodes our results show no evidence of any relationship between environmental change and cultural change at the sierra de atapuerca

convective thinning of the lithosphere a mechanism for the initiation of continental rifting thinning of the lithosphere by heat carried convectively to its base is a possible mechanism for the initiation of continental rifting the lithosphere asthenosphere boundary marks the transition from a quasi rigid behavior of the mantle on geological time scales to a viscous one the boundary lies at or close to the solidus of the mantle material and its position is a function of temperature and pressure additional heat carried to the boundary will cause it to rise and the lithosphere to thin a one dimensional model is used to study the upward movement of the boundary from an initial equilibrium position as a consequence of an increase in the heat flux from the convecting mantle the ratio of the amount of thinning to the initial thickness is directly proportional to the increase in heat flux from the asthenosphere and inversely proportional to the difference between the final subcrustal geothermal gradient and the slope of the transition temperature profile the rate of thinning is determined by the initial and final equilibrium thicknesses the thermal diffusivity the transition temperature profile and the plume temperature profile it depends only slightly on any latent heat associated with the lithosphere asthenosphere transition during a large fraction of the time between the initial and final equilibrium states the lithosphere thins at a rate which is inversely proportional to the square root of time t even 300 km thick lithospheres may be thinned to 50 km or crustal thicknesses in tens of million years by the heat advected by mantle plumes this heat contributes to an enhanced surface heat flow because of the constant level of radioactive heat production in the crust the ratio of the final to the initial surface heat flow increases much less than the ratio of the final to the initial heat flow from the asthenosphere for large increases in asthenospheric heat flow the lithosphere is almost thinned to the crust before any significant change of surface heat flow occurs uplift due to thermal expansion upon lithospheric thinning is of the order of 102 103 m a rayleigh taylor instability acting on the thinning lithosphere may further increase thinning rates and cause magmatic intrusions of the lithosphere and surface volcanism

post failure simulations of a large slope failure using 3dec the hsien du shan slope abstract the goal of this paper is to evaluate the post failure behavior of the hsien du shan rock avalanche which was triggered by typhoon morakot in 2009 using a three dimensional 3d discrete element program namely 3dec the 3d slope topography and local joint sets are explicitly considered in the calculations and the joint sets cut the sliding rock mass into blocks with arbitrary shapes the modeled blocks exhibit the elastic behavior of the local rocks the analysis successfully simulates the wedge failure at the initiation of the landslide additionally the 3dec results clarify the local rock sliding phenomena at the boundaries of the source area the simulated depositional area correlates well with the actual area affected by the hsien du shan rock avalanche in addition the erosion of a ridge by the sliding rock near the southwestern margin of the area at an elevation of 590 m has a significant influence on the shape and size of the impacted area the interlocking effect between blocks is also considered

rapid long term rates of denudation high rates of erosion 1 15 mm yr of fluvial strata have persisted over intervals of 0 2 1 5 m y and across areas of 60 2000 km2 in the cenozoic foreland basin of northern pakistan these rates occur in areas associated with thrust shortening and they indicate that erosion nearly kept pace with the rates of latest miocene to pleistocene uplift such high rates of erosion are predicted to promote hindward imbrication of thrusts and to reduce the amount of subsidence directly attributable to thrust loading

testing the hypothesis of an impoverished predator guild in the early miocene ecosystems of patagonia an analysis of meat availability and competition intensity among carnivores abstract the lower miocene santa cruz formation dated to 18 16 ma of southern patagonia argentina preserves rich vertebrate faunas which are representative of communities that existed prior to the great american biotic interchange gabi some previous researchers have hypothesized that these pre gabi faunas had a low richness of mammalian carnivores an impoverished predator guild while others argue for a predator prey ratio similar to those of recent communities in this paper we analyze faunas from the lower part of the santa cruz formation fl 1 7 using a methodology that allows us to quantify i the meat resources that were available to the secondary consumers of the palaeocommunity and ii the competition intensity for these resources in our modeling we considered different scenarios related to meat consumption including the possibility that several taxa had a scavenging behavior and also differences in mortality rates between young and adult prey our results provide estimates of the nutritional requirements from the predator scavenger guild under maximum and minimum quantities of meat offered by the prey community which indicate the presence of a well balanced palaeocommunity moreover the competition indices point to a relatively high level of competition for prey of small to medium size although competition for resources from large mammal prey was rather low this suggests that the predator scavenger guild was not impoverished although there were insufficient carnivore species to fully consume the megaherbivore biomass

time averaging overcompleteness and the geological record time averaging makes events that happened at different times appear to be synchronous in the geological record it can generate overcompleteness by concentrating objects e g fossils clasts from a longer time interval into a unit that formed during a shorter interval time averaging results both from extrinsic agents e g vertical mixing condensation analytical pooling of data and the intrinsic properties of the fossilized objects preservational potential and abundance variation in intrinsic and extrinsic factors results in disharmonious time aver aging different taxa preserved together may be time averaged over different time scales because extrinsic and intrinsic factors vary in time and space the geological record is characterized by vertical and lateral variations in time averaging the importance of time averaging depends on the time aver aging threshold which is determined by the time scale of the process of interest significant time aver aging occurs when the scale of temporal mixi

exhumation of high pressure rocks a review of concepts and processes the exhumation of high pressure metamorphic rocks requires either the removal of the overburden that caused the high pressures or the transport of the metamorphic rocks through the overburden exhumation cannot be achieved simply by thrusting or strike slip faulting it may be caused by erosion of shortened and thickened crust but this is unlikely to be the only mechanism for exhuming rocks from depths greater than about 20 km one or more of the following additional mechanisms may be involved 1 corner flow of low viscosity material trapped between the upper and lower plates in a subduction zone can cause upward flow of deeply buried rock and may explain some occurrences of high pressure tectonic blocks in melange this process does not however appear to be adequate to explain the exhumation of regional high pressure terrains 2 buoyancy forces acting directly on metamorphic rock bodies may cause them to rise relative to more dense surroundings this is likely to be the most important mechanism of exhumation of crustal rocks subducted into the mantle but cannot explain the emplacement of coherent tracts of high density metamorphic rock into shallow crustal levels some high pressure blocks emplaced at shallow levels in accretionary terrains may have been entrained in diapiric intrusions of low density mud or serpentinite 3 extension driven by the forces associated with contrasts in surface elevation may explain the exhumation and structural setting of many high pressure terrains extension may occur in the upper part of an accretionary wedge thickened by underplating or it may affect the whole lithosphere in a region of intracontinental convergence if surface elevation has been increased by the removal of a lithospheric root in the second case extension may be accompanied by magmatism and an evolution towards higher temperature during decompression of the metamorphic terrain

the hypermobility of huge landslides and avalanches abstract catastrophic failure of large land masses which generate landslides rockfalls and debris avalanches can have hazardous consequences extending far beyond the source observations show that the mobility of such events depends strongly on the volume for volumes larger than 10 6 m 3 with many different processes invoked to explain higher mobilities hypermobility for both terrestrial and extraterrestrial events although the mobility of large events has been extensively studied there is no generally accepted mechanism for predicting extreme travel distances because the underlying physical processes are poorly understood here we show using physical and rheological arguments that the wide scatter observed for very large mass wasting events in all environments collapses to a single relationship between event volume or inundation area and mobility hypermobility is defined to be the reciprocal of the effective friction coefficient e where the scale dependent e is derived analytically as a function of the mechanical volumetric and topographical parameters of the flow the dominant term in the coefficient is the degree of fluidization involved in the flow our results show that fluidization is limited in extraterrestrial events that significant fluidization occurs in non volcanic and volcanic events and fluidization dominates submarine events this analysis demonstrates that fluidization is associated with long run out distances and that the degree of fluidization can be predicted by the volume and physical and topographic parameters the methodology is simple physically based and validated with datasets of very large terrestrial and extraterrestrial avalanche events we demonstrate that the effective coulomb friction rheology and the hypermobility function are applicable to avalanche events of any size providing an opportunity to simulate past and or potential huge landslide and debris avalanche events run out distances destructive impact and assessment of risk the model can be used to estimate the overrun area and volume in terms of known mobility data

pressure temperature time paths of regional metamorphism i heat transfer during the evolution of regions of thickened continental crust the development of regional metamorphism in areas of thickened continental crust is investigated in terms of the major controls on regional scale thermal regimes these are the total radiogenic heat supply within the thickened crust the supply of heat from the mantle the thermal conductivity of the medium and the length and time scales of erosion of the continental crust the orogenic episode is regarded as consisting of a relatively rapid phase of crustal thickening during which little temperature change occurs in individual rocks followed by a lengthier phase of erosion at the end of which the crust is at its original thickness the principal features of pressure temperature time ptt paths followed by rocks in this environment are a period of thermal relaxation during which the temperature rises towards the higher geotherm that would be supported by the thickened crust followed by a period of cooling as the rock approaches the cold land surface the temperature increase that occurs is governed by the degree of thickening of the crust its conductivity and the time that elapses before the rock is exhumed sufficiently to be affected by the proximity of the cold upper boundary for much of the parameter range considered the heating phase encompasses a considerable portion of the exhumation decompression part of the ptt path in addition to the detailed calculation of ptt paths we present an idealized model of the thickening and exhumation process which may be used to make simple calculations of the amount of heating to be expected during a given thickening and exhumation episode and of the depth at which a rock will start to cool on its ascent path an important feature of these ptt paths is that most of them lie within 50 c of the maximum temperature attained for one third or more of the total duration of their burial and uplift and for a geologically plausible range of erosion rates the rocks do not begin to cool until they have completed 20 to 40 per cent of the total uplift they experience considerable melting of the continental crust is a likely consequence of thickening of crust with an average continental geotherm a companion paper discusses these results in the context of attempts to use metamorphic petrology data to give information on tectonic processes 1984 oxford university press

the acheulean workshop of la noira france 700 ka in the european technological context abstract the prehistoric site of la noira located in the cher valley a tributary of the loire river in the center of france has yielded a lithic assemblage composed of large bifacial tools cores and flakes the archaeological level lying on the tertiary lacustrine limestone bedrock was covered and fossilized by a 6 m thick fluvial sandy formation the mean age value of esr dates obtained on bleached fluvial quartz grains sampled in the sandy levels covering the archeological level is 665 55 ka confirming the antiquity of the archaeological assemblage esr dates and the technical characteristics of the assemblage suggest that it is among the oldest sites with bifacial technology in western europe since 2011 following geological and geochronological studies the archaeological level has been excavated over a surface of about 100 m 2 the aim of this paper is to provide new data on the lithic assemblage and to place the lithic patterns of the site in the european technological framework la noira is a workshop site belonging to a key period of time with the earliest evidence of the bifacial technology in europe as for instance levels p q of arago in france or notarchirico in italy contemporaneous with 800 500 ka sites without bifacial technology such as happisburgh pakefield in england or isernia in italy this phase predates the wide scale dissemination of the bifacial technology all over western europe from the mis 12 technological comparisons between these assemblages and a discussion of the diversity of assemblages and technological features point to early episodic arrivals of new traditions in europe against a background of earlier traditions

a technique for analyzing the thermal and uplift histories of eroding orogenic belts a scandinavian example geothermometric and geobarometric data from pelitic schists in the upper plate of the forsa thrust in the northern norwegian caledonides are interpreted as recording part of the uplift trajectory of this area during erosion and slow cooling a method developed in this paper for reconstructing the thermal history of orogenic belts from such data is based on a general mathematical description of thermal conduction in a lithospheric slab with an arbitrary initial temperature distribution and uplifted at a constant rate with certain restrictions the uplift trajectory tz path of any rock parcel can be calculated from only a few temperature depth points along that uplift trajectory by applying this method to geothermometry and geobarometry data from near the forsa thrust we can 1 extrapolate tz paths measured over a limited depth range upward to the surface 2 recover geotherms present at various times during the uplift and erosion history of the mountain belt 3 obtain tz paths for rock parcels above and below those for which pt data are available and 4 use pt data in combination with geochronological data to obtain accurate estimates of uplift rates our analysis suggests that shortly after nappe emplacement the nappe stack was hot near 800 c in the lower part of the nappe stack while the underlying autochthon was cold near thermal equilibrium prior to nappe emplacement the maximum burial depth of rocks near the forsa thrust was probably between 35 and 60 km

late cenozoic uplift of the eastern cordillera bolivian andes abstract this paper analyses late cenozoic uplift in the bolivian andes using the morphology of well preserved regional paleosurfaces in the eastern cordillera that define three axially draining braided river catchments that formed between 12 and 9 ma rock uplift since the formation of the paleodrainage systems which has been quantified using four different methods is 1705 695 m with a mean erosion of 230 90 m as a consequence of entrenchment of the drainage systems the lack of faulting or tilting in the regions immediately farther west strongly suggest that rock uplift of the paleodrainage systems also extends to the western margin of the eastern cordillera balanced structural cross sections require crustal deformation at depth beneath the eastern cordillera in order to accommodate underthrusting of the brazilian shield beneath the thin skinned fold and thrust belt on the eastern margin of the bolivian andes in this case the observed uplift of the eastern cordillera is easily explained by sliding up a ramp in the major decollement dipping in the range 4 16 w as a consequence of the observed 60 110 km of shortening farther east in the subandean zone contemporaneous uplift of the western margin of the eastern cordillera is easily explained in terms of crustal thickening as a result of ductile squeezing in the lower crust accommodating at depth the subandean shortening it remains unclear how this uplift relates to that of the regions farther west in the altiplano and volcanic arc except that uplift in the eastern cordillera coincides with a phase of intense shortening in the northern altiplano commencing at 9 5 ma and continuing to 2 7 ma and possibly younger