no state change in pelagic fish production and biodiversity during the eocene oligocene transition the eocene oligocene e o boundary 33 9 million years ago has been described as a state change in the earth system marked by the permanent glaciation of antarctica and a proposed increase in oceanic productivity here we quantified the response of fish production and biodiversity to this event using microfossil fish teeth ichthyoliths in seven deep sea sediment cores from around the world ichthyolith accumulation rate a proxy for fish biomass production shows no synchronous trends across the e o ichthyolith accumulation in the southern ocean and pacific gyre sites is an order of magnitude lower than that in the equatorial and atlantic sites demonstrating that the southern ocean was not a highly productive ecosystem for fish before or after the e o further tooth morphotype diversity and assemblage composition remained stable across the interval indicating little change in the biodiversity or ecological role of open ocean fish while the e o boundary was a major global climate change event its impact on pelagic fish was relatively muted our results support recent findings of whale and krill diversification suggesting that the pelagic ecosystem restructuring commonly attributed to the e o transition probably occurred much later in the late oligocene or miocene marine fish biomass and diversity did not change during the eocene oligocene transition despite widespread cooling and antarctic ice sheet expansion according to microfossil fish teeth records from a set of deep sea cores

their lips are sealed identifying hard stone soft stone and antler hammer direct percussion in palaeolithic prismatic blade production the present experiment examined the differentiation between hard stone soft stone and antler hammer in upper palaeolithic direct percussion prismatic blade production through the experimental knapping by two knappers who were asked to produce a series of medium sized blades the use of two knappers in the experiment tested knapper variability in the resultant experimental assemblage while the majority of the attributes of blades and proximal fragments including the presence of lipping platform preparation bulb presence and prominence and curvature amongst others did not vary significantly in regards to which hammer type either knapper used a number of blade attributes differed significantly yet weakly and there was almost no direct correlation between the individual knappers blades and the hammer type they used this suggests strongly that for a given goal of producing medium sized blades this can be accomplished equally well using antler hard stone or soft stone hammers and the resultant blades will be difficult to tell apart therefore based on the results of this series of knapping experiments we would be hesitant in using the 21 variables tested here to differentiate between blades produced with antler hard stone and soft stone hammer types in the archaeological record

end cretaceous marine mass extinction not caused by productivity collapse an asteroid impact at the end of the cretaceous caused mass extinction but extinction mechanisms are not well understood the collapse of sea surface to sea floor carbon isotope gradients has been interpreted as reflecting a global collapse of primary productivity strangelove ocean or export productivity living ocean which caused mass extinction higher in the marine food chain phytoplankton dependent benthic foraminifera on the deep sea floor however did not suffer significant extinction suggesting that export productivity persisted at a level sufficient to support their populations we compare benthic foraminiferal records with benthic and bulk stable carbon isotope records from the pacific southeast atlantic and southern oceans we conclude that end cretaceous decrease in export productivity was moderate regional and insufficient to explain marine mass extinction a transient episode of surface ocean acidification may have been the main cause of extinction of calcifying plankton and ammonites and recovery of productivity may have been as fast in the oceans as on land

seabed features caused by shallow gas in north sea seepage of shallow gas mainly methane recently has been documented visually in the central section of the north sea at water depths of about 70 80 m the surface expressions caused by these seeps are not dramatic they mainly consist of small funnel shaped craters 20 cm across in the cover sand however in deeper parts of the north sea where the cover sediments consist of silt and clay the surface features are more dramatic here the craters pockmarks caused by shallow gas eruptions or seepages are up to 20 m deep and 100 m wide in some areas the pockmarks are paved with a crust of calcium carbonate cement which is believed to have formed as a result of gas efflux through the seabed furthermore the presence of these calcium carbonate reefs seems to have attracted a wide variety of marine life the presence of shallow gas has caused an enrichment of marine life that seems to be significant beside the semicircular and composite pockmarks gas induced erosion also has caused elongate depressions these occur where the top sediment bedding has caused the gas to migrate along certain axes the mode and speed of formation of the gas induced erosion features are ofmore major concern to oil exploration and development in the northern north sea research into these aspects recently has been stimulated by the discovery of one of the world s largest offshore gas reservoirs which coincidentally lies within a pockmarked area less

thermo chronological approach to reservoir diagenesis in the offshore angola basin a fluid inclusion 40 ar 39 ar and k ar investigation 1 microthermometric analyses of fluid inclusions and geochronological surveys of authigenic silicates in neocomian sandstones and albian dolomitic reservoirs from the offshore angola basin have allowed determination of the age and the physical chemical conditions for fluid migration in a late diagenetic stage the 40 ar 39 ar laser probe dating of adularia overgrowths from the albian reservoirs shows that the trapping of primary aqueous and oil inclusions occurred during the early miocene 25 6 or 3 2 ma the k ar age of authigenic illites from the neocomian sandstones is slightly younger 19 or 1 ma and the crystallization of regular illite smectite mixed layers is related to a previous eocene to paleocene diagenetic stage 51 58 ma there appears to have bee both a regional and vertical variation in the salinity of aqueous fluids during the miocene the fluid inclusion trapping temperatures were estimated by correcting the homogenization temperatures of aqueous fluids assuming that pressures during the miocene were close to the present reservoir pressures and by intersecting the isochores of aqueous and oil inclusions assuming they were trapped at strictly similar pressure and temperature conditions the fluid inclusion temperatures are consistent with those derived from the tetrahedral aluminum content aliv of authigenic chlorites 168 206 degrees c in the albian reservoirs at depths between 2350 and 3580 m and 175 237 degrees c in the neocomian sandstones at depths between 2770 and 4470 m in both reservoir formations miocene tempe atures were higher than the present ones and related either to deeper burial or higher geothermal gradient

is the dingcun lithic assembly a chopper chopping tool industry or late acheulian abstract the famous palaeolithic site of dingcun ting ts un in north china is located on the third terrace of the fenhe river which is one of the main tributaries of the yellow river after it was discovered a series of localities with similar stratigraphic profiles was excavated in 1954 since then the artifacts from dingcun have been classified as a chopper chopping tool industry assigned to the late pleistocene the authors re examined the lithic assemblage and carried out an additional field survey at these localities the local geomorphologic background and especially the chinese loess paleosol sequence re define the chronology of the site uranium series dates on mammal teeth are 160 ka 210 ka hence the site is re assigned to the late middle pleistocene the dingcun lithic assemblage is also re classified as late acheulian characterized by classic acheulian tools such as handaxes cleavers and picks with the addition of some light duty tools including scrapers notches borers and denticulates this paper aims to present a new interpretation of the chronology and the cultural characteristics of the dingcun site

vertical evolution of fluid venting structures in relation to gas flux in the neogene quaternary of the lower congo basin offshore angola abstract the processes preceding the genesis of pockmarks and their subsequent evolution has been rarely studied since pockmarks were discovered in 1970 a high resolution 3 d seismic survey from the continental slope of the lower congo basin allows us to study in detail the structures that developed before the formation of pockmarks as well as their subsequent geometric evolution this paper aims at reporting new type of fluid related structures that relate to pockmarks the objective of this research is to understand 1 the evolution of these structures and their genetic relationship with pockmarks and 2 how their morphologies may be influenced by changes in venting intensity over time pockmark and chimney structures in this survey are hosted within late miocene to quaternary hemipelagites above clastic reservoirs in a petroliferous basin they are all associated with positive high amplitude anomalies phaas on seismic data phaas are interpreted from their dramatically higher acoustic impedance relative to the background sedimentary values of the host units and by their association with seismic pull up effects from their planform and cross sectional geometry phaas are primarily interpreted as being due to the development of methane related carbonates but they may be associated with gas hydrates in one or two examples methanogenic carbonates form either by authigenic accumulation or by anaerobic methane oxidation amo once upwardly migrating methane enters the sulfate methane transition zone smtz typically within the first few tens of meters below the seabed therefore vertical accumulations of phaas are interpreted to reflect the temporal evolution of methane flux migrating upward to reach the paleo seabed or smtz timing of local scale fluid leakage can therefore be diagnosed by analyzing phaas at seep locations that occur in association with pockmark chimney structures a conceptual model for the evolution of different fluid venting structures is proposed here and is based on the analysis of venting structures that we expressed by 3 d seismic reflections in this model the main features are linked into a process based sequence culminating in the infill and termination of the pockmarks as fluid venting sites our model summarizes different rhythms of venting which are expressed by different types of phaas along with venting structures linear phaas and conduits inferred slow seeps they can be succeeded by sub circular phaas and shallow depressions which inferred slow to moderate seeps then the seep can become either a fast vent and terminated into a pockmark crater or it can become less active and be sealed afterwards subsurface sediment fluidizations and remobilizations are likely to happen in the last case and are probably caused by hydrate dissociations

ammonite and inoceramid bivalve extinction patterns in cretaceous tertiary boundary sections of the biscay region southwestern france northern spain cretaceous tertiary boundary sections located in the biscay region of southwestern france and northern spain are among the most complete of all known land based sequences across this boundary new collections of ammonites and inoceramid bivalves from five localities show quite distinct extinction patterns for these two groups of characteristic cretaceous molluscs from eight to ten ammonite species extend into the latest cretaceous and possibly to the boundary in contrast inoceramid bivalve diversity gradually diminished from a minimum of six species in the early maastrichtian to zero at the beginning of the late maastrichtian when they were replaced by the cryptic pteriomorph tenuipteria extinction of typical inoceramids well before the end of the maastrichtian is supported by data from other regions indicating that it was a global rather than local phenomenon

mid pleistocene acheulean like stone technology of the bose basin south china stone artifacts from the bose basin south china are associated with tektites dated to 803 000 3000 years ago and represent the oldest known large cutting tools lcts in east asia bose toolmaking is compatible with mode 2 acheulean technologies in africa in its targeted manufacture and biased spatial distribution of lcts large scale flaking and high flake scar counts acheulean like tools in the mid pleistocene of south china imply that mode 2 technical advances were manifested in east asia contemporaneously with handaxe technology in africa and western eurasia bose lithic technology is associated with a tektite airfall and forest burning

unlocking the barite paleoproductivity proxy a new high throughput method for quantifying barite in marine sediments abstract the accumulation rate of barite baso4 in marine sediments is a powerful tracer of paleo export productivity due to the refractory nature of barite in sediments and its ability to record ecosystem wide productivity it has been used to reconstruct past export productivity and to infer the effects of ocean circulation and nutrient supply on ocean ecosystems however the difficulty in generating large datasets of reliable barite accumulation rates has limited the use of this proxy here we present a new method for quantifying barite in marine sediments that promises a dramatic increase in sample throughput while also improving recovery of barite in a wide variety of marine sediments this method relies on selective dissolution of barite using a chelating ligand that avoids liberating ba from silicate phases and it can therefore work reliably on small 250 mg sediment aliquots rigorous evaluation of the method reveals that it quantitatively extracts barite and is largely unaffected by other ba sources due to the relatively simple analytical requirements of this barite extraction method and the small sample amount needed it can also be used to rapidly generate paleoproductivity records both during and after coring expeditions altogether this new technique should expand the study of the marine biologic system in the past by dramatically increasing analytical efficiency and widening the range of questions that are accessible using barite accumulation rate as a paleoproductivity proxy

the loessic palaeolithic in south tadjikistan central asia its industries chronology and correlation abstract this paper starts with an introductory account of the loessic palaeolithic a term used by the author from 1987 to describe those palaeolithic sites which are associated with very thick loess palaeosol successions following a discussion on movius hypothesis on the lower palaeolithic industry of eurasia a brief description of four major palaeolithic sites in south tadjikistan is given the main sites are kuldara 0 8 ma karatau 1 0 2 ma lakhuti 1 0 13 ma and obi mazar 0 09 ma they represent different periods of slowly evolved pebble culture without new influence from other regions the main features of the stone age industry called karatau culture are as follows the clear pebble technique without prepared core bifacial and levallois techniques dispersion of the pebble tools choppers stone slices wedges unifaces and flakes which are not stable for this form and dimensions the blades are practically absent no series of the tools is observed and they are the side scrapers scrapers on occasion borers points carinate tools the karatau culture is similar to the lower palaeolithic industries of china the karatau culture in south tadjikistan has better geological context than other pebble industries of central and south asia

loess stratigraphy in central china abstract loess sequences in central china provide a detailed record of climate changes during the last 2 5 million years at least 44 major shifts from glacial to interglacial conditions occurred during this time in china prolonged loess deposition lasting more than 40 millennia occurred eleven times with only four of these intervals in brunhes chron the climate oscillations took place with increased frequency between 2 4 and 0 5 ma compared to the last half million years major shifts toward cooler and drier climates occurred at about 2 4 ma 1 2 ma and 0 5 ma while less pronounced shifts are dated to 1 65 ma 0 8 ma and 0 2 ma three of the last four reversals of the earth s magnetic field whose lithostratigraphic position has been detail are recorded in a glacial deposit the low field magnetic susceptibility of loess and soils which reflects the concentration of ultrafine magnetite is related to the degree of pedogenesis and serves as a proxy measure of climate the accumulation rate of the magnetite was fairly constant throughout the last 1 2 million years and can serve as a measure of time susceptibility records from localities near xifeng and luochuan located 160 km apart are compared and used to define informal lithostratigraphic units in the loess plateau of china

the middle pleistocene handaxe site of shuangshu in the danjiangkou reservoir region central china abstract the presence of acheulean tool types e g handaxes and cleavers in east asia has recently attracted considerable attention they challenge the long lasting concept that the early palaeolithic in east asia is characterized only by mode 1 technology and they reflect the diversity and complexity of palaeolithic culture during hundreds of thousands of years in this paper we present a detailed technological analysis of the in situ artifact assemblage at the shuangshu site danjiangkou reservoir region central china as well as intra and inter regional comparisons of some characteristic traits used to test the difference between handaxes in the east and the west the results show that there are two reduction sequences taking place one is expressed in the predominant use of quartz in the production the small to medium sized artifacts which is an expedient technology that dominates the whole assemblage and the other is represented by the predominant use of quartz phyllite and trachyte in the production of large cutting tools lcts the latter displays the technical criteria characteristic of acheulean technology although its origins are much debated in addition the number of lcts and total artifacts is generally low for the size of the excavation area which probably is a result of relatively small population size and the high mobility of hominids the thickness of handaxes has been shown not to be a reliable variable in demonstrating the difference between the east and the west

interpreting carbon isotope excursions strangelove oceans large negative excursions in marine carbonate delta sup 13 c are commonly associated with period boundaries and mass extinctions explanations for these events must be consistent with limitations imposed by carbon isotope mass balance at steady state i e for excursions lasting more than 10 sup 5 yr the surface ocean delta sup 13 c is set by the organic fraction of the total carbon burial rate and the magnitude of the photosynthetic isotope effect the delta sup 13 c of the deep ocean and the surface to deep isotope gradient are set by both the organic fraction of the ocean s remineralized particulate flux and the magnitude of the isotope effect thus it is the carbon isotope composition of the deep ocean that is most reflective of internal oceanic processes the surface ocean records changes in the longer term throughput of carbon in the system the cessation of organic export from the surface ocean such as is presumed to have caused the strangelove ocean condition of the cretaceous tertiary k t boundary leads to an isotopically homogeneous ocean in decades to centuries if this condition persists the ocean s isotopic composition approaches that of the riverine weathering input in 10 sup 5 yr failure to approach this value during the k t event suggests continued production andmore burial of organic carbon dominantly in either terrestrial or shallow marine environments less

astronomical calibration of the paleocene time the first complete cyclic sedimentary successions for the early paleogene from drilling multiple holes have been retrieved during two odp expeditions leg 198 shatsky rise nw pacific ocean and leg 208 walvis ridge se atlantic ocean these new records allow us to construct a comprehensive astronomically calibrated stratigraphic framework with an unprecedented accuracy for both the atlantic and the pacific oceans covering the entire paleocene epoch based on the identification of the stable long eccentricity cycle 405 kyr high resolution x ray fluorescence xrf core scanner and non destructive core logging data from sites 1209 through 1211 leg 198 and sites 1262 1267 leg 208 are the basis for such a robust chronostratigraphy former investigated marine odp sites 1001 and 1051 and land based e g zumaia sections have been integrated as well the high fidelity chronology is the prerequisite for deciphering mechanisms in relation to prominent transient climatic events as well as completely new insights into greenhouse climate variability in the early paleogene we demonstrate that the paleocene epoch covers 24 long eccentricity cycles we also show that no definite absolute age datums for the k pg boundary or the paleocene eocene thermal maximum petm can be provided by now because of still existing uncertainties in orbital solutions and radiometric dating however we provide two options for tuning of the paleocene which are only offset by 405 kyr our orbitally calibrated integrated leg 208 magnetostratigraphy is used to revise the geomagnetic polarity time scale gpts for chron c29 to c25 we established a high resolution calcareous nannofossil biostratigraphy for the south atlantic which allows a much more detailed relative scaling of stages with biozones the re evaluation of the south atlantic spreading rate model features higher frequent oscillations in spreading rates for magnetochron c28r c27n and c26n

provenancing hornfels in the dingcun industry the exploitation of the vicinity source in this paper we attempt to determine the source of the hornfels used to make the famous late middle pleistocene lithic industry from dingcun in north china by combining geological mapping and geochemical fingerprinting xrf we demonstrate that the source of the hornfels was around the dagudui mountain 7 km east of dingcun taking into consideration the gujiao site which is also located along the fenhe river the palaeolithic inhabitants of the fenhe river drainage basin had a good knowledge of the local rock sources and used them over a very long period from the middle pleistocene to the neolithic our geochemical data not only helps us to establish the source of the dingcun industry but also provides a reliable basis for the sub classification of the hornfels that is more accurate than that resulting from visual inspection in addition our research initiates a new method for studying raw material sources of chinese paleolithic sites

the impact of atmospheric pco2 on carbon isotope ratios of the atmosphere and ocean it is well known that the equilibration timescale for the isotopic ratios 13c 12c and 14c 12c in the ocean mixed layer is on the order of a decade 2 orders of magnitude slower than for oxygen less widely appreciated is the fact that the equilibration timescale is quite sensitive to the speciation of dissolved inorganic carbon dic in the mixed layer scaling linearly with the ratio dic co2 which varies inversely with atmospheric pco2 although this effect is included in models that resolve the role of carbon speciation in air sea exchange its role is often unrecognized and it is not commonly considered in the interpretation of carbon isotope observations here we use a global three dimensional ocean model to estimate the redistribution of the carbon isotopic ratios between the atmosphere and ocean due solely to variations in atmospheric pco2 under last glacial maximum lgm pco2 atmospheric 14c is increased by 30 due to the speciation change all else being equal raising the surface reservoir age by about 250 years throughout most of the ocean for 13c enhanced surface disequilibrium under lgm pco2 causes the upper ocean atmosphere and north atlantic deep water 13c to become at least 0 2 higher relative to deep waters ventilated by the southern ocean conversely under high pco2 rapid equilibration greatly decreases isotopic disequilibrium as a result during geological periods of high pco2 vertical 13c gradients may have been greatly weakened as a direct chemical consequence of the high pco2 masquerading as very well ventilated or biologically dead strangelove oceans the ongoing anthropogenic rise of pco2 is accelerating the equilibration of the carbon isotopes in the ocean lowering atmospheric 14c and weakening 13c gradients within the ocean to a degree that is similar to the traditional fossil fuel suess effect

a short duration of the cretaceous tertiary boundary event evidence from extraterrestrial helium 3 analyses of marine carbonates through the interval 63 9 to 65 4 million years ago indicate a near constant flux of extraterrestrial helium 3 a tracer of the accretion rate of interplanetary dust to earth this observation indicates that the bolide associated with the cretaceous tertiary k t extinction event was not accompanied by enhanced solar system dustiness and so could not have been a member of a comet shower the use of helium 3 as a constant flux proxy of sedimentation rate implies deposition of the k t boundary clay in 10 2 10 3 years precluding the possibility of a long hiatus at the boundary and requiring extremely rapid faunal turnover

evaluation of the astronomical time scale for the paleocene and earliest eocene abstract the astronomical tuned time scale is rapidly extended into the paleogene but due to the existence of an eocene gap different tuning options had to be presented for the paleocene these options differ both in number and tuning of 405 kyr eccentricity related cycles and are only partially consistent with recalculated 40 ar 39 ar constraints for the cretaceous paleogene k pg and paleocene eocene p e boundaries in this paper we evaluate the cyclostratigraphic interpretation of records from odp leg 198 and 208 sites and the zumaia section to solve the problem of the different tuning options we found that the interval between the k pg boundary and the early late paleocene biotic event elpe comprises 17 instead of 16 405 kyr eccentricity related cycles as previously proposed while the entire paleocene contains 25 405 kyr cycles starting from 40 ar 39 ar age constraints for the k pg boundary a new tuning to 405 kyr eccentricity is presented for the paleocene and earliest eocene which results in ages of 66 0 and 56 0 ma for the k pg and p e boundaries respectively this tuning introduces considerable differences in age for a number of nannofossil events at odp sites 1209 and 1262 in the interval between 61 and 63 ma but eliminates large and abrupt changes in the seafloor spreading rate the tuning seems further consistent with recalculated 40 ar 39 ar ages for ash layer 17 of early eocene age however despite this apparent consistency with existing radio isotopic constraints an alternative 405 kyr younger or less likely older tuning cannot be excluded at this stage

cretaceous tertiary boundary of dsdp site 596 south pacific sediments from the cretaceous tertiary k t boundary at deep sea drilling project site 596 record accumulation of pelagic clays at about lat 45 s in the center of the ancestral south pacific the k t boundary in this region is characterized by oxidized thoroughly bioturbated sediments containing large amounts of ir and relict high pressure and high temperature mineral phases the net ir fluence 320 ng cm 2 is among the largest on earth and the number of shocked quartz grains 30 m in size 1800 cm 2 exceeds that in all localities outside of north america

towards an orbital time scale for chinese loess deposits abstract in this study we analyzed the grain size of the baoji loess soil sequence at 10 cm intervals results show that grain size variations are very sensitive to loess soil alternations with loess units being much coarser than soils such a change in loess soil grains is interpreted as the result of the glacial interglacial cyclic variations in the intensity of the winter monsoon winds out of siberia the grain size record is thus employed as a proxy indicator of the winter monsoon circulation and tuned to the orbital records calculated recently by berger and loutre 1991 under the control of major magnetic reversals the tuning is independent of any correlation with 18o signals in the deep sea sediments the resulting grain size time scale is tightly constrained as suggested by the following facts 1 the filtered obliquity and precession components from the grain size data on the orbital time scale closely match the theoretical orbital records 2 ages of the major magnetic reversals estimated from the grain size time scale are in good agreement with the k ar dated ages 3 there is close coherence between the baoji grain size time series and the orbital variations at the orbital frequency bands over the entire 0 2 5 ma period and 4 the grain size record on the orbital time scale shows a close similarity to the orbitally tuned dsdp site 607 and odp site 677 18o records examination of time dependent characteristics of the grain size record suggests that there are two major shifts of dominant periodicities in the long term monsoonal cycles one occurring at about 0 8 ma bp and the other around 1 7 ma bp

evidence for reduced export productivity following the cretaceous paleogene mass extinction the cretaceous paleogene k pg mass extinction was associated with a collapse in the carbon isotopic 13c gradient between planktonic and benthic foraminifera and a decrease in bulk carbonate 13c values these perturbations have been explained by several hypotheses global collapse of primary productivity strangelove ocean greatly reduced export but not primary productivity living ocean little or no reduction in export productivity resilient ocean and geographic heterogeneity in the change of export productivity heterogeneous ocean we tested primary versus export productivity changes in the paleoshelf of new jersey where 13c values and organic carbon accumulation rates can distinguish among different ocean responses on the shelf the k pg boundary is associated with a 2 5 13c decrease in bulk carbonate a 0 8 13c decrease in organic carbon a collapse of the surface to bottom 13c gradient and a drop in organic carbon accumulation rates we interpret an early danian 1 0 planktonic foraminiferal 13c gradient a 0 75 cross shelf benthic foraminiferal 13c gradient and a drop in carbon accumulation rates to reflect the presence of active primary but limited export productivity consistent with the living ocean hypothesis we evaluated interbasinal deep sea benthic foraminiferal 13c gradients between the pacific site 1210 and atlantic site 1262 oceans as a proxy for changes in export productivity the interbasinal 13c gradient was reduced after the mass extinction suggesting a reduction in global export productivity although our data support the living ocean hypothesis evidence from paleoupwelling zones shows significant export productivity indicating spatial heterogeneity in the wake of the k pg mass extinction heterogeneous ocean

diverse patterns of ocean export productivity change across the cretaceous paleogene boundary new insights from biogenic barium 1 one of the best studied aspects of the k pg mass extinction is the decline and subsequent recovery of open ocean export productivity e g the flux of organic matter from the surface to deep ocean some export proxies including surface to deep water 13c gradients and carbonate sedimentation rates indicate a global decline in export productivity triggered by the extinction in contrast benthic foraminiferal and other geochemical productivity proxies suggest spatially and temporally heterogeneous k pg boundary effects here we address these conflicting export productivity patterns using new and compiled measurements of biogenic barium unlike a previous synthesis we find that the boundary effect on export productivity and the timing of recovery varied considerably between different oceanic sites the northeast and southwest atlantic southern ocean and indian ocean records saw export production plummet and remain depressed for 350 thousand to 2 million years biogenic barium and other proxies in the central pacific and some upwelling or neritic atlantic sites indicate the opposite with proxies recording either no change or increased export production in the early paleocene our results suggest that widespread declines in surface to deep ocean 13c do not record a global decrease in export productivity rather independent proxies including barium and other geochemical proxies and benthic community structure indicate that some regions were characterized by maintained or rapidly recovered organic flux from the surface ocean to the deep seafloor while other regions had profound reductions in export productivity that persisted long into the paleocene

geographic controls on nannoplankton extinction across the cretaceous palaeogene boundary calcareous nannoplankton a large group of marine autotrophs that produce carbonate skeletons were decimated to less than 10 of species during the cretaceous palaeogene boundary mass extinction 65 million years ago although the mass extinction followed an impact event the exact cause of the nannoplankton mortality is not well understood here we assess the timing and spatial variability of nannoplankton extinction by analysing nannofossil counts in cretaceous palaeogene boundary sections from all of the main ocean basins we find that extinction rates were higher in the northern hemisphere oceans and diversity remained low for 310 000 years in contrast southern hemisphere oceans showed lower extinction rates and a nearly immediate recovery of normal nannoplankton populations we propose that the oblique northward impact concentrated ejected particulates into the northern hemisphere blocking sunlight and suppressing photosynthesis increased rates of extinction and a prolonged recovery would then be associated with the greatest concentration of particulates we speculate that metal poisoning from fallout of the particulates may have exacerbated and extended the nannoplankton crisis in the northern hemisphere and thereby slowed the recovery of the northern hemisphere marine food web over 90 of calcareous nannoplankton species disappeared during the cretaceous palaeogene mass extinction which occurred after an impact event palaeontological analyses show that the extinction was most pronounced in the northern hemisphere oceans possibly as a result of an increased concentration of particulates created by the impact in the north

partial collapse of the marine carbon pump after the cretaceous paleogene boundary the impact of an asteroid at the end of the cretaceous caused mass extinctions in the oceans a rapid collapse in surface to deepocean carbon isotope gradients suggests that transfer of organic matter to the deep sea via the biological pump was severely perturbed however this view has been challenged by the survival of deep sea benthic organisms dependent on surface derived food and uncertainties regarding isotopic fractionation in planktic foraminifera used as tracers here we present new stable carbon d 13 c and oxygen d 18 o isotope data measured on carefully selected planktic and benthic foraminifera from an orbitally dated deep sea sequence in the southeast atlantic our approach uniquely combines d 18 o evidence for habitat depth of foraminiferal tracer species with species specific d 13 c eco adjustments and compares isotopic patterns with corresponding benthic assemblage data our results show that changes in ocean circulation and foraminiferal vital effects contribute to but cannot explain all of the observed collapse in surface to deep ocean foraminiferal d 13 c

resilience of pacific pelagic fish across the cretaceous palaeogene mass extinction the cretaceous palaeogene mass extinction caused ecosystem upheaval fish abundance data from the tethys sea and the pacific ocean indicate heterogeneity in the extinction and recovery with greater resilience in the pacific

time scale controversy accurate orbital calibration of the early paleogene 1 timing is crucial to understanding the causes and consequences of events in earth history the calibration of geological time relies heavily on the accuracy of radioisotopic and astronomical dating uncertainties in the computations of earth s orbital parameters and in radioisotopic dating have hampered the construction of a reliable astronomically calibrated time scale beyond 40 ma attempts to construct a robust astronomically tuned time scale for the early paleogene by integrating radioisotopic and astronomical dating are only partially consistent here using the new la2010 and la2011 orbital solutions we present the first accurate astronomically calibrated time scale for the early paleogene 47 65 ma uniquely based on astronomical tuning and thus independent of the radioisotopic determination of the fish canyon standard comparison with geological data confirms the stability of the new la2011 solution back to 54 ma subsequent anchoring of floating chronologies to the la2011 solution using the very long eccentricity nodes provides an absolute age of 55 530 0 05 ma for the onset of the paleocene eocene thermal maximum petm 54 850 0 05 ma for the early eocene ash 17 and 65 250 0 06 ma for the k pg boundary the new astrochronology presented here indicates that the intercalibration and synchronization of u pb and 40ar 39ar radioisotopic geochronology is much more challenging than previously thought

pelagic evolution and environmental recovery after the cretaceous paleogene mass extinction the evolutionary recovery of planktic foraminifera from the cretaceous paleogene mass extinction was closely linked to recovery of the marine carbon system both the evolutionary recovery and the biogeochemical recovery occurred in two stages the second stage of evolutionary radiation peaked nearly four million years after the extinction immediately after the abrupt final recovery of the organic flux to deep waters the timing of these events suggests that the final postextinction recovery of planktic foraminiferal diversity was directly contingent on the final recovery of the marine carbon cycle this second radiation was defined by the diversification of tropical photosymbiotic forms that dominated low and mid latitude assemblages long into the eocene we hypothesize that this diversification was a result of the reappearance of oligotrophic oceans as the organic flux from the surface ocean to deep water fully recovered from the mass extinction

lithic raw material quality of middle pleistocene artefacts from the han river danjiangkou reservoir region central china abstract the east asian acheulean is often considered distinct from african and european acheulean technologies as large cutting tools lcts are thicker and heavier on average this distinction is generally true but exceptions occur particularly in thickness as more chinese sites are reported it has been suggested that the raw materials available in east asia have played a part in determining this dissimilarity extensive raw material studies on east asian technologies have not yet been done to determine if this is indeed the case it is thus important to investigate the impact of raw materials quality on the east asian acheulean this paper focuses on raw material attributes for lcts from the danjiangkou reservoir region central china drr with specific focus on middle pleistocene artefacts from terrace 3 of the han river extensive experimental studies were done to determine raw material attributes and how those attributes affect the knapping process in the creation of lcts a set of variables was recorded for the experimental tools and compared with a sample of archaeological lcts the variables recorded included the impurity encounter rates of various raw materials their weathering states grain sizes and shapes the results indicated that hominids occupying the drr exhibited selective behaviours for the raw materials they used to make lcts despite not having a wide variety of materials from which to select it is also evident that they showed adaptability and made strategic decisions with regards to the selected raw materials for manufacture of lcts to meet their needs

a late acheulean culture on the chinese loess plateau the techno economic behavior of the dingcun lithic industry abstract the chinese loess plateau is the largest loess area in the world and covers 400 000 km2 with a loess palaeosol sequence that is comparable with marine isotope stages mis as a quaternary terrestrial timescale of climatostratigraphy and chronology the dingcun lithic industry was recovered in 1954 in the loess plateau and has been known for its large flake acheulean tools technological analysis based on the concept of chaine operatoire was applied in this paper to update our knowledge of the techno economic behaviours at this site and in the loess plateau area the results show that there are two chaine operatoires 1 one focused on the production of large flake blanks faconnage for making large cutting tools lcts and 2 a small to medium debitage to obtain flakes for light duty tools experiments were applied to check the knapping technique the results confirmed the probability that hard hammers were used to produce large flakes on hornfels blanks and soft hammer techniques were not used when compared with the acheulian lcts of other sites in china dingcun is different from the acheulian culture of south china danjiangkou reservoir region drr and the bose basin and more similar to the luonan acheulian industry therefore it seems that a large flake acheulean was developed the loess plateau area in the late middle pleistocene

origin of a global carbonate layer deposited in the aftermath of the cretaceous paleogene boundary impact abstract microcrystalline calcite micrite dominates the sedimentary record of the aftermath of the cretaceous paleogene k pg impact at 31 sites globally with records ranging from the deep ocean to the chicxulub impact crater over intervals ranging from a few centimeters to more than seventeen meters this micrite rich layer provides important information about the chemistry and biology of the oceans after the impact detailed high resolution scanning electron microscopy demonstrates that the layer contains abundant calcite crystals in the micron size range with a variety of forms crystals are often constructed of delicate oriented agglomerates of sub micrometer mesocrystals indicative of rapid precipitation we compare the form of crystals with natural and experimental calcite to shed light on their origin close to the crater a significant part of the micrite may derive from the initial backreaction of cao vaporized during impact in more distal sites simple interlocking rhombohedral crystals resemble calcite precipitated from solution globally we found unique calcite crystals associated with fossilized extracellular materials that strikingly resemble calcite precipitated by various types of bacteria in natural and laboratory settings the micrite rich layer contains abundant bacterial and eukaryotic algal biomarkers and most likely represents global microbial blooms initiated within millennia of the k pg mass extinction cyanobacteria and non haptophyte microalgae likely proliferated as dominant primary producers in cold immediate post impact environments as surface water saturation state rose over the following millennia due to the loss of eukaryotic carbonate producers and continuing river input of alkalinity whitings induced by cyanobacteria replaced calcareous nannoplankton as major carbonate producers we postulate that the blooms grew in supersaturated surface waters as evidenced by crystals that resemble calcite precipitates from solution the microbial biomass may have served as a food source enabling survival of a portion of the marine biota ultimately including life on the deep seafloor although the dominance of cyanobacterial and algal photosynthesis would have weakened the biological pump it still would have removed sufficient nutrients from surface waters thus conditioning the ocean for the recovery of biota at higher trophic levels