the cretaceous paleogene k p boundary at brazos texas sequence stratigraphy depositional events and the chicxulub impact abstract two cores from brazos texas spanning the cretaceous paleogene k p boundary are investigated by a multidisciplinary approach aiming at unraveling environmental changes and sequence stratigraphic setting in addition the sedimentology of the k p event deposit and its correlation with the k p boundary is studied foraminifera and nannofossil stratigraphy indicates that both cores include a latest maastrichtian zone cf1 cf2 and earliest danian p0 p and p1a shale sequence with a sandy and chicxulub ejecta bearing event deposit at the k p boundary a hiatus of unknown duration may be present by the unconformable base of the event deposit planktic foraminifera as well as calcareous nannofossil abundance and diversity both decline abruptly above the event deposit k p mass extinction whereas benthic foraminifera show a pronounced faunal change but no mass extinction mineralogical and geochemical proxies suggest that except for the sandwiched k p event deposit no facies change took place across the k p boundary and no evidence for adverse an or dysoxic sedimentary conditions following the chicxulub impact was observed therefore the interval bracketing the k p event deposit is considered as highstand systems tract increased coarse detritus input and low planktic benthic p b foraminifera ratios during the earliest paleocene p0 and p both suggest an increased coastal proximity or relative sea level lowering although the k p mass extinction of planktic foraminifera might have influenced the p b ratios as well consequently the sandy shales of the early paleocene are considered as late regressive highstand or as lowstand deposit during p1a shales assigned as transgressive systems tract overlie a pyrite and glauconite rich bioturbated transgressive surface or type 2 sequence boundary the smectite dominated clay assemblage with minor illite kaolinite and chlorite indicates semiarid humid climates with no obvious shifts across the k p boundary the magnetic susceptibility signature during the maastrichtian reveals a subtle cyclic or rhythmic pattern whereas a high amplitude cyclic pattern is present during the early danian the k p event deposit shows a succession of high energetic debris flows and turbidites derived from multiple source areas followed by a period of decreasing current energy deposition was likely triggered by multiple tsunami or tempestites followed by a prolonged period of reworking and settling the chicxulub ejecta at the base of the k p event deposit consists of mg rich smectite as well as fe mg rich chlorite spherules their mineralogical composition points to target rocks of mafic to intermediate composition presumably situated in the northwestern sector of the chicxulub impact structure besides these silicic phases the most prominent ejecta components are limestone clasts accretionary carbonate clasts and microspar suggesting that the texas area received ejecta also from shallow carbonate rich lithologies at the impact site on the yucatan carbonate platform the excellent correlation of chicxulub ejecta at brazos with ejecta found in the k p boundary layer worldwide along with the associated mass extinction provides no evidence that chicxulub predated the k p boundary and allows for unequivocal positioning of the k p boundary at the event deposit

the late maastrichtian nannofossil record of climate change in the south atlantic dsdp hole 525a abstract the phytoplankton response calcareous nannofossils to the late maastrichtian climate evolution is investigated in the south atlantic dsdp hole 525a and compared to published geochemical and micropaleontological data the results point to a succession of dramatic climatic fluctuations cool water indicators ahmuellerella octoradiata kamptnerius magnificus and nephrolithus frequens suggest cool surface water conditions prevailed during chron c30n at the top of c30n their sudden drop in abundance the last occurrence of b constans and the concomitant increase in the tropical species micula murus suggest warming and lower surface water productivity an m murus acme within chron c29r reflects maximum warming during the last 100 kyr of the maastrichtian the decrease in m murus and increase in cool water indicators reflect rapid cooling with the cool climate persisting over the calcareous nannoplankton response to climate change correlate with similar findings in the equatorial atlantic hole 1258a and parallels the stable isotope record of planktic and benthic foraminifera of dsdp hole 525a as well as the decline in 187os 188os comparison of this marine record and the continental climate record in north america suggests a link between deccan volcanism and the late maastrichtian warm event

the use of the lateral tranchet blow technique at nesher ramla israel a new cultural marker in the levantine middle paleolithic abstract the open air middle paleolithic site at nesher ramla israel dated to the end of marine isotope stage 6 and marine isotope stage 5 is characterized by extensive use of the lateral tranchet blow technique this technique consists of the removal of an elongated thin spall along the retouched edge of the blank in nesher ramla this technique is used for producing a specific tool kit component unifacially retouched tools with a lateral tranchet blow ltb the tools with ltb were systematically produced throughout the 8 m thick middle paleolithic sequence of nesher ramla representing the major typological category in some of the layers together with tools with ltb the assemblages contain large numbers of ltb spalls here we present a detailed techno morphological analysis of the tools and spalls from nesher ramla unit iii one of the richest archaeological layers of the site our results suggest that the goal of the ltb technique at nesher ramla was to manufacture a tool with an edge that is partially retouched and partially sharp i e shaped by ltb the ltb technique employs a long knapping routine including a series of compulsory and optional steps implying non opportunistic behavior although on site use of the ltb technique is attested the fact that these tools were also often introduced to the site as finished objects further emphasizes their importance and suggests that most of them were not produced on site in response to an immediate need for sharp edges this tool type represents a new previously unreported component in the levantine middle paleolithic toolkit a comparison with other archaeological units along the 8 m thick stratigraphy of nesher ramla suggests that the ltb technique was one of the major techniques for manufacturing tools at that site and that the tools with ltb represent a cultural marker for nesher ramla hominins and possibly a new cultural marker in the levantine middle paleolithic according to a comparison of tools shaped by ltb from other geographic and temporal contexts most notably the central european keilmesser the nesher ramla tools with ltb were likely designed and used by right handed hominins in a longitudinal cutting motion

biostratigraphic subdivision and correlation of upper maastrichtian sediments from the atlantic coastal plain and blake nose western atlantic

the cueva del angel lucena spain an acheulean hunters habitat in the south of the iberian peninsula the cueva del angel archaeological site is an open air sedimentary sequence remnant of a collapsed cave and part of a karst complex the faunal assemblage dominated by equus ferus large bovids and cervids has been subjected to intense anthropic actions reflecting selective predation the fauna may be correlated with european faunistic associations of the end of the middle pleistocene to the beginning of the upper pleistocene the cueva del angel lithic assemblage dominated by non modified flakes and abundant retouched tools with the presence of 46 handaxes appears to fit well within the regional diversity of a well developed non levallois final acheulean industry a preliminary 230th 234u age estimate the review of the lithic assemblage and faunal evidence would favour a chronological positioning of the site in a period stretching from the end of the middle pleistocene to the beginning of the upper pleistocene mis 11 mis 5 the acheulean lithic assemblage found at the cueva del angel fits very well with the hypothesis of a continuation of acheulean cultural traditions in the site distinct from the contemporaneous uniquely mousterian complexes witnessed in other parts of the iberian peninsula and western europe

latitudinal migration of calcareous nannofossil micula murus in the maastrichtian implications for global climate change micula murus is one of the main calcareous nannofossil biostratigrapic markers of tethyan and intermediate provinces in the upper maastrichtian uppermost cretaceous a review of its first occurrence at 14 deep sea sites and sections shows that it is time transgressive from the tropical realm of the atlantic and pacific oceans to the intermediate latitudes of the north atlantic south atlantic indian ocean and the northern tethys m murus remained confined to the tropical realm for 1 2 m y in the early late maastrichtian thus supporting high latitudinal thermal gradients it subsequently spread out in the late maastrichtian to temperate latitudes and to the tethys in coincidence with the onset of a thermohaline circulation change at 67 5 ma suggesting a major change in surface water circulation and interocean communications

paleolithic caves and hillslope processes in south western samaria israel environmental and archaeological implications abstract south western samaria is emerging as a major province of paleolithic cave sites most recently discovered caves have been naturally filled with terra rossa type colluvial deposits when the hillslopes above the caves were stripped from vegetation during late quaternary times site formation processes differ significantly between caves with pit like openings such as qesem emanuel and rantis caves vs those with cliff side entrances such as shukbah tinshemet and deir kaddis caves the former favored accumulation of colluvial debris while the latter were relatively protected from these deposits caves discovered in the 20th century were mainly of the latter cliff face type while in the 21st century new discoveries commonly occur where construction works intersect previously unnoticed filled caves

formation processes and combustion features at the lower layers of the middle palaeolithic open air site of nesher ramla israel the lower stratigraphic sequence units iii vi of the middle palaeolithic site of nesher ramla was studied using geoarchaeological methods field observations indicate that the site formed within a karst depression that was infilled by colluvium and in which intermittent human activity occurred including two layers highly rich in anthropogenic remains units iii and v infrared analysis of bones determined that black bones are carbonized and that certain white bones are calcined quantitative analysis of wood ash pseudomorphs indicates specific areas of high concentrations of ash micromorphological analysis enabled identification of two distinct features associated with ash and burnt bones one is a thinly bedded complex of blacked soil overlain by ash and charcoal and the second is a 20 cm thick massive fine grained layer of mixed ash the first feature is interpreted as an in situ hearth macroscopically similar features have not yet been analyzed the second feature is interpreted as ash in secondary position i e an ash pile midden that formed following hearth rake out activities these findings are unique considering that most middle palaeolithic open air sites in the levant are single layered and that in most evidence for hominin use of fire is scarce or absent we discuss the factors that may affect the preservation of ash in open air sites and conclude that the setting of nesher ramla in a topographic low provided relative protection from wind which prevented ash deflation and at the same time hominin activity remains were buried relatively fast which detached the ashes and combustion features from direct rainfall and from decalcifying root activity

uppermost campanian maestrichtian strontium isotopic biostratigraphic and sequence stratigraphic framework of the new jersey coastal plain firm stratigraphic correlations are needed to evaluate the global significance of unconformity bounded units sequences we correlate the well developed uppermost campanian and maestrichtian sequences of the new jersey coastal plain to the geomagnetic polarity time scale gpts by integrating sr isotopic stratigraphy and biostratigraphy to do this we developed a maestrichtian ca 73 65 ma sr isotopic reference section at deep sea drilling project hole 525a in the southeastern atlantic ocean maestrichtian strata can then be dated by measuring their 87 sr 86 sr composition calibrating to the gpts of s c cande and d v kent 1993 personal commun and using the equation age ma 37 326 894 52 639 89 87 sr 86 sr sr stratigraphic resolution for the maestrichtian is estimated as 1 2 to 2 m y at least two unconformity bounded units comprise the uppermost campanian to maestrichtian strata in new jersey the lower one the marshalltown sequence is assigned to calcareous nannofossil zones cc20 21 nc19 and cc22b nc20 it ranges in age from 74 1 to 69 9 ma based on sr isotope age estimates the overlying navesink sequence is assigned to calcareous nannoplankton zones cc25 26 nc21 23 it ranges in age from 69 3 to 65 ma based on sr isotope age estimates the upper part of this sequence the tinton formation has no calcareous planktonic control sr isotopes provide an age estimate of 66 1 2 ma latest maestrichtian sequence boundaries at the base and the top of the marshalltown sequence match boundaries elsewhere in the atlantic coastal plain owens and gohn 1985 and the inferred global sea level record of haq et al 1987 they support eustatic changes as the mechanism controlling depositional history of this sequence however the latest maestrichtian record in new jersey does not agree with haq et al 1987 we attribute this to correlation and time scale differences near the cretaceous paleogene boundary high sedimentation rates in the latest maestrichtian of new jersey shrewsbury member of the red bank formation and the tinton formation suggest tectonic uplift and or rapid progradation during deposition of the highstand systems tract

the influence of closed brine pockets and permeable brine channels on the thermo elastic properties of saline ice a model of the thermo elastic behaviour of saline ice is formulated and model solutions describing thermo elastic waves tew propagating into a half space of the ice are investigated the model is based on a proposal that saline ice is a matrix which encompasses both closed brine pockets and permeable channels filled with brine experiments on the thermal expansion of saline ice samples and on tew in saline ice have been performed in the cold laboratories of the university centre in svalbard and in university college london the experimental data are compared with theoretical conclusions the experimental data support our hypothesis that the brine in saline ice is divided between closed pockets and open permeable channels this article is part of the themed issue microdynamics of ice

landscapes depositional environments and human occupation at middle paleolithic open air sites in the southern levant with new insights from nesher ramla israel abstract middle paleolithic human occupation in the levant 250 50 ka ago has been recorded in roofed cave and rockshelter and open air sites research at these different types of sites yielded different perspectives on the middle paleolithic human behavior and evolution until recently open air middle paleolithic sites in the levant were found in three major sedimentary environments fluvial lake margin and spring here we describe a unique depositional environment and formation processes at the recently discovered open air site of nesher ramla israel and discuss their contribution to understanding site formation processes in open air sites in the levant the site is 8 m thick middle paleolithic sequence osl dated to 170 80 ka that is located in a karst sinkhole formed by gravitational deformation and sagging into underground voids the sedimentary sequence was shaped by gravitational collapse cyclic colluviation of soil and gravel into the depression waterlogging in situ pedogenesis and human occupation original bedding and combustion features are well preserved in the lower archaeological sequence a rare occurrence in comparison to other open air archaeological sites this phenomenon coincides with episodes of fast sedimentation burial which also allowed better preservation of microscopic remains such as ash the upper archaeological sequence does not exhibit bedding or preservation of ash despite presence of heat affected lithic artifacts which makes it similar to other open air sites in the levant we suggest that rate of burial is the major factor that caused the difference between the upper and lower sequences the differences in the burial rate may be connected to environmental and vegetation changes at the end of mis 6 we also identified an interplay between sediment in wash and density of human activity remains i e during episodes of low natural sediment input the density of artifacts is higher relative to episodes with high rate of sediment in wash the detailed analysis of natural and anthropogenic processes at nesher ramla suggests a much wider spectrum of processes than previously reported for southern levantine paleolithic sites nesher ramla shares certain depositional and post depositional characteristics with both cave and open air sites and provides a better insight into processes which control both types of sites

calcareous nannofossil evidence for the existence of the gulf stream during the late maastrichtian 1 upper maastrichtian calcareous nannofossil assemblages from eight cores on the south carolina coastal plain onshore set and three deep sea drilling sites from the continental slope and abyssal hills offshore set were analyzed by correlation and principal component analysis to examine the ancient surface water thermal structure in addition a temperature index derived from independently published paleobiogeographic information was applied to the sample data all three methods indicate a strong separation of the samples into onshore and offshore sets with the offshore data set exhibiting significantly warmer paleotemperatures the great disparity between these two sample sets indicates that there was a strong thermal contrast between the onshore and offshore surface water masses that persisted throughout the late maastrichtian despite evident short term changes in fertility productivity and community structure this suggests the gulf stream was present as a major oceanographic feature during the late maastrichtian

new latitude based nannofossil zonations for the campanian maastrichtian of the south atlantic ocean and their paleoceanographic implications the global evolution of calcareous nannofossils during the campanian maastrichtian interval is not fully understood and nannofossil zonations for the central and south atlantic ocean are yet to be constructed here we test the applicability of previous calcareous nannofossil zonations developed for other ocean basins for biostratigraphy in the south atlantic ocean and refine campanian maastrichtian biostratigraphy in the region we document calcareous nannofossil distributions at deep sea drilling project dsdp and ocean drilling program odp sites from the high mid and low latitudes in the south atlantic ocean dsdp sites 354 356 511 525a and 530a and odp sites 690c 700b 661a and 1258a combining nannofossil occurrences with magnetostratigraphic schemes previously constructed for some of the sites we propose three new zonations tied to the global magnetostratigraphic chrons with distinct bio horizons selected at different latitudinal regions in this study we present detailed definitions of new south atlantic ocean low latitude sal south atlantic mid latitude sam and south atlantic high latitude sah zonations we identified significant diachronism of some species between latitudes throughout the campanian and maastrichtian these species diachronism mainly between zonal markers from low and mid latitudes during the late maastrichtian was probably related to migration patterns due to fundamental paleoceanographic changes

calcareous nannofossil and dinoflagellate stratigraphy across the cretaceous tertiary boundary at hor hahar israel in israel the cretaceous tertiary k t boundary at hor hahar occurs within the interval from the top of the ghareb formation maastrichtian to just below the horizon of dark marl and clay within the overlying taqiye formation paleocene the studied interval contains all the calcareous nannofossil zones micula prinsii latest maastrichtian markalius inversus np1 earliest paleocene andcruciplacolithus tenuis np2 early paleocene they correlate in sequence with theabathomphalus mayaroensis p0 p1a p1b and p1c planktic foraminiferal zones the palynological assemblages consist mainly of dinocysts with only few pollen grains and spores these assemblages are used to interpret five stratigraphic phases of environmental change across the k t boundary in the hor hahar section in the latest maastrichtian there is an overwhelming dominance of the nannofossilmicula decussata which probably reflects environmental stress preceding the terminal cretaceous mass extinction a nearshore marine environment at the boundary is suggested by the increase in number of specimens of the dinocystcyclonephelium and by the predominance of terrigenous organic matter sediment there followed two episodes of transgression and regression the calcareous cyst producing dinoflagellatethoracosphaera futterer 1976 becomes dominant in two episodes at the boundary and approximately one meter above it it alternates in abundance with the organic walled dinoflagellates which suggests that different environmental parameters were operating for each group maastrichtian dinocysts decline in abundance toward the k t boundary they reach greatest abundance and species diversity at the same strata where foraminiferids recover after their mass extinction at the boundary calcareous nannofossils recover only later in the early paleocene changes in 13c and total organic carbon as as well as dinocyst and nannofossil composition indicate an episode of strong ecological stress about one meter above the boundary

middle paleolithic sidescrapers were resharped or recycled a view from nesher ramla israel abstract the resharpening of sidescrapers is a widely discussed issue in recent middle paleolithic studies however in the levantine record the evidence for sidescraper resharpening is meager the middle paleolithic site of nesher ramla israel represents a rare case in which sidescrapers were frequently modified by removal of longitudinal spalls from their edges both parent sidescrapers and spalls long sharpening flakes lsf are abundant throughout the site s stratigraphy providing a rare opportunity for a complementary study of both artifact groups the aim of the present study is to reconstruct the life history of sidescrapers retrieved from nesher ramla we ask how the lsf removal changed the morphology of the sidescraper edge at which stage of the sidescraper life history it occurred what was the purpose of lsf removal and was it a part of a recycling system aimed at producing a new edge tool type or the maintenance of the existing tool edge the studied artifacts 100 parent sidescrapers and 60 complete lsf were sampled randomly from the most intensively occupied and richest layers of the site our results suggest that sidescraper edge modification was a well mastered and skillful process that resulted in standardized and morphologically distinct products in most cases the sidescrapers were not further retouched after the lsf removal this leads us to propose that the major goal was to transform the sidescraper into a tool with a sharp straight and flat edge the lsf removal at nesher ramla provides an exceptional case in which a simple raw edge was deliberately manufactured at the expense of the previously retouched edge this reinforces the previous assumptions that simple raw edges were often preferred over retouched ones

equations for determining the gas and brine volumes in sea ice samples on a etabli des equations utilisables pour determiner le taux de gaz inclus dans la glace de mer a partir de mesures de densite de salinite et de temperature dans des gammes de temperatures entre 2 c et 30 c inversement ces relations peuvent etre utilisees pour calculer la densite de la glace de mer en fonction de la temperature et de la salinite en prenant en compte a la fois la presence de gaz et de cristaux de sel dans la glace on donne aussi des equations qui permettent le calcul du volume de gaz et d eau salee dans la glace a des temperatures autres que celle pour laquelle la densite a ete determinee

thermal evolution of permeability and microstructure in sea ice 1 the fluid permeability k of sea ice constrains a broad range of processes such as the growth and decay of seasonal ice the evolution of summer ice albedo and biomass build up such processes are critical to how sea ice and associated ecosystems respond to climate change however studies of k and its dependence on brine porosity and microstructure are sparse here we present a multifaceted theory for k which closely captures laboratory and field data x ray computed tomography provides an unprecedented look at the brine phase and its connectivity we find that sea ice displays universal transport properties remarkably similar to crustal rocks yet over a much narrower temperature range our results yield simple parameterizations for fluid transport in terms of temperature and salinity and permit more realistic representations of sea ice in global climate and biological models

handaxe manufacture and re sharpening throughout the lower paleolithic sequence of tabun cave abstract in this paper we assess the evidence for on site manufacture and re sharpening of handaxes in the lower paleolithic layers of tabun cave by examining the ratio of thinning flakes the typical waste of bifacial manufacture to handaxes our study of twenty nine assemblages ranging from the acheulean to the acheulo yabrudian complex combining results from jelinek s and ronen s excavations shows that thinning flakes are scarce throughout the entire sequence results indicate that handaxes were commonly not manufactured or re sharpened in the excavated area and that these activities were most likely conducted outside the site the late lower paleolithic in various parts of eurasia and africa is characterized by high variability in lithic technology which in the case of the levant is best reflected in the acheulo yabrudian complex this study aids our understanding of variability in the levantine late lower paleolithic by adding the concept of segmentation of reduction as an integral part of late lower paleolithic lithic technology significantly in tabun cave the segmentation of reduction that characterizes handaxe manufacture differs from the patterns observed in amudian blade production and yabrudian scraper manufacture which were both regularly conducted on site the extent of variability and flexibility is thus reflected not only in the technologies employed but also in how different reduction sequences were segmented and executed across the landscape suggesting a link between technical knowledge mobility patterns and landscape exploitation