abrupt mousterian aurignacian boundary at c 40 ka bp accelerator 14c dates from l arbreda cave catalunya spain abstract the cultural transition from mousterian to aurignacian is abrupt at l arbreda cave and occurs within a homogeneous sedimentary unit with no visible lithologic changes fragments of milligram size charcoal were collected immediately above and below the cultural boundary for radiocarbon dating by accelerator four charcoal fragments from the lowest basal aurignacian level yielded dates of 37 7 1 0 37 7 1 0 39 9 1 2 and 38 7 1 2 ka bp average 38 5 1 0 ka bp these ages are similar to three dates from the same cultural horizon at el castillo cave in cantabria and both sets of dates are significantly older than the earliest reported for the aurignacian in the aquitaine and in other parts of central and western europe the dates are in accord with similarly early dates for aurignacian in bulgaria and suggest that appearance of aurignacian peoples is synchronous across europe three fragments from the uppermost mousterian level yielded dates of 39 4 1 4 34 1 0 75 and 41 4 1 6 ka bp discounting the spurious 34 1 ka bp result these dates are slightly older average 40 4 1 4 ka bp but overlap with counting error the basal aurignacian dates the data show that the transition from mousterian to aurignacian was chronologically abrupt at this location these results strongly support the replacement hypothesis

high salinity fluid inclusions formed from recycled seawater in deeply subducted alpine serpentinite abstract the origin of high pressure brines has been investigated in the erro tobbio peridotite western alps a mantle slice that was exposed to the seafloor of the mesozoic ligurian piedmontese tethys and was later involved in alpine subduction hydrothermal alteration by seawater derived fluids led to replacement of the mantle assemblage by cl bearing serpentine 0 35 wt cl brucite 0 2 wt cl and alkali bearing phyllosilicates 0 2 wt cl 0 2 0 55 wt na2o 1 5 wt k2o relics of these hydrous phases occur in olivine titanian clinohumite antigorite assemblages formed at 2 5 gpa and 550 600 c during partial devolatilization and veining of the hydrothermally altered peridotite the high pressure phases lack chlorine and alkalis and are coeval with fluid inclusions trapped in the syn eclogitic veins the inclusions are salt saturated and contain up to 50 wt cl na k mg and fe high fluid chlorinity was probably achieved during rehydration of relict mantle minerals and deposition of hydrous phases in the veins the data presented suggest that the seafloor hydrothermal signature was inherited by the eclogitic fluid due to partitioning of chlorine and alkalis into the fluid phase the presence of salty brines in eclogitized hydrous peridotites can indicate deep recycling of seawater derived fluids hydrous ultramafic systems can therefore act as large scale carriers of seawater into the mantle

tectonic implications of paleomagnetic and geochronologic data from the yukon koyukuk province alaska the paleomagnetic and geochronologic record of alaska is complicated by overprints that make it difficult to relate the terranes of northern and southern alaska to each other and to north america to better understand these relationships and the overprinting paleomagnetic and k ar dating samples were analyzed from the three major geologic units of the yukon koyukuk province ykp of central alaska these units consist of a basal jurassic early cretaceous volcanic island arc assemblage albian cenomanian clastic sedimentary rocks and bimodal eocene volcanic rocks k ar age determinations of the early tertiary volcanic rocks form two distinct groups the older group 65 49 ma is mostly felsic and probably represents the maximum inboard penetration of low angle subduction related volcanism these older rocks were deformed during the regional deformation of the ykp the younger group 44 43 ma is post deformational and composed dominantly of basalt these results bracket a time 49 44 ma when deformation ceased in the province this time interval is coincident with a major transition from convergence to strike slip and extensional tectonic style throughout alaska the geologic units of the ykp display two characteristic paleomagnetic signatures primary directions based on positive reversal conglomerate and or bedding tilt stability tests were obtained from the albian cenomanian sedimentary rocks and eocene volcanic rocks the mid cretaceous sedimentary rocks show about 15 of poleward motion between 90 56 ma a time of high rates of convergence between alaska and the pacific and eurasian plates age equivalent rocks from neighboring regions st matthew island and the alaskan north slope also indicate similar amounts of poleward northward motion which suggests that the whole of western and northern alaska may have moved northward about 10 relative to north america as a more or less coherent block paleomagnetic results from the eocene volcanic rocks indicate that the ykp was in place by 56 ma and formed part of the accretionary nucleus that served as a backstop for the accreted terranes of southern alaska secondary remagnetized directions are recorded in the basal island arc assemblage and in albian cenomanian sediments near younger igneous occurrences the clustering of secondary directions in the geographic reference frame indicates that they were acquired after deformation ceased 49 44 ma which is consistent with the coincidence of the mean of these directions and the 54 44 ma north american reference direction

fifty thousand years of flint knapping and tool shaping across the mousterian and uluzzian sequence of fumane cave abstract grotta di fumane a mousterian site in northern italy has been extensively explored over the last two decades in order to gather data on neanderthal behaviour from during the late pleistocene up to the appearance of modern humans the 12 m thick sedimentary sequence includes several layers that have yielded variable amounts of flint artefacts and faunal remains particularly in br11 a11 a8 a9 and a5 a6 related to repeated and complex human occupations the earliest assemblages record the exclusive use of the levallois method from s9 to br7 for the production of flakes with unidirectional and centripetal recurrent modalities in br9 bifaces and different types of cores have also been found the first striking technological replacement occurs in br6 up to br3 where there is a complex of layers with the infrequent occurrence of bones flakes and scrapers made with a method closely resembling the quina technique further evidence of variability in lithic technology is provided by the re appearance of the levallois technology during mis3 in layer a11 although here focused more on blades than flakes and by the levallois discoid alternance throughout the transect from a10v to a5 a6 the persistence of the mousterian tradition in the lowermost a4 uluzzian level continues to be evidenced by levallois flakes and cores side scrapers points and thinned implements the presence of conjoined flakes and cores proves that innovations occurred in a4 and a3 and with the disappearance of the levallois technology in a3 other methods focused on different kinds of flakes short thick blades thin bladelets and flake bladelets even though most of this evidence is similar to that of other levallois sequences in the mediterranean rim some such as the bifaces and the quina assemblages provides us with new details of the cultural scenario the former are ascribable to the vast spread of bifacial industries from north west france to central and eastern europe in mis4 and early mis3 whereas the latter can be linked to the dissemination of quina in southeast france the perspectives adopted for assessing the significance of the a units are broadly borne out in the other late mousterian industries where the replacement of levallois techniques by discoid technologies is recorded independently of geographical and palaeo environmental context and site function striking innovations in lithic technology occurring at the top of the sequence record the appearance of the uluzzian in southern italy and the balkans

accretion of southern alaska abstract paleomagnetic data from southern alaska indicate that the wrangellia and peninsular terranes collided with central alaska probably by 65 ma ago and certainly no later than 55 ma ago the accretion of these terranes to the mainland was followed by the arrival of the ghost rocks volcanic assemblage at the southern margin of kodiak island poleward movement of these terranes can be explained by rapid motion of the kula oceanic plate mainly from 85 to 43 ma ago according to recent reconstructions derived from the hot spot reference frame after accretion much of southwestern alaska underwent a counterclockwise rotation of about 50 as indicated by paleomagnetic poles from volcanic rocks of late cretaceous and early tertiary age compression between north america and asia during opening of the north atlantic 68 44 ma ago may account for the rotation

the last 40 ka tephrostratigraphic record of lake ohrid albania and macedonia a very distal archive for ash dispersal from italian volcanoes abstract a 1075 cm long core lz1120 was recovered in the south eastern part of the lake ohrid republics of macedonia and albania and sampled for identification of tephra layers magnetic susceptibility investigations show rather high magnetic values throughout the core with peaks unrelated to the occurrence of tephra layers but instead to the relative abundance of detrital magnetic minerals in the sediment naked eye inspection of the core allowed us to identify of two tephra layers at 896 897 cm and 1070 1075 cm laboratory inspection of the grain size fraction 125 m allowed for the identification of a third cryptotephra at 310 315 cm major element analyses on glass shards of the tephra layers at 896 897 cm and 1070 1075 cm show a trachytic composition and indicate a correlation with the regionally dispersed y 3 and y 5 tephra layers dated at ca 30 and 39 cal ka bp the cryptotephra at 310 315 cm has a mugearitic benmoreitic composition and was correlated with the fl eruption of mt etna dated at 3370 70 cal yr bp these ages are in agreement with five 14 c ams measurements carried out on plant remains and macrofossils from the lake sediments at different depths along the core the recognition of distal tephra from italian volcanoes allows us to link the lake ohrid succession to other archives located in the mediterranean area and in eastern europe the benmoreitic mugearitic tephra layer at 310 315 cm is the first recognition in the balkan area of a distal ash deposit from a mid intensity explosive eruption of mt etna as far as 600 km from the source

development of a brine dominated hydrothermal system at temperatures of 400 500 c in the upper level plutonic sequence troodos ophiolite cyprus abstract microthermometric analyses of quartz hosted fluid inclusions in fresh and epidotized plagiogranites from the troodos ophiolite cyprus indicate that brine rich fluids 46 56 wt nacl equivalent at temperatures 400 500 c were pervasive throughout many of the plagiogranite bodies high salinity fe bearing inclusions along healed microfractures homogenize by halite dissolution at temperatures of 400 500 c liquid dominated low salinity 2 7 wt nacl secondary fluid inclusions are ubiquitous in all plagiogranite and gabbro samples studied homogenization of the low salinity inclusions occurs at uncorrected temperatures of 200 400 c the quartz hosted high salinity fluids represent either phase separation of hydrothermal seawater or an exsolved magmatic aqueous phase at uncorrected temperatures of 400 500 c migration and segregation of brine and vapor phases into fractures near the margins of the crystallizing plagiogranite bodies resulted in preferential entrapment of the fe rich brines in the deep seated high temperature portions of the hydrothermal system subsequent fracturing of the upper plutonic rocks at temperatures of 200 400 c allowed penetration by seawater which pervasively altered the plagiogranites hydration reactions involving formation of secondary minerals and or mixing with phase separated fluids resulted in fluid salinities two times that of seawater

the nature of orthomagmatic hydrothermal fluids in the oka carbonatite quebec canada evidence from fluid inclusions fluid inclusions in apatite monticellite and calcite from the oka carbonatite complex generally comprise either aqueous liquid vapour or aqueous liquid vapour halite some inclusions also contain a variety of trapped solids including calcite strontianite nahcolite and mirabilite microthermometry and raman spectroscopy indicate that co2 is not an important constituent of these fluids microthermometric data also indicate that the hydrothermal fluids liberated from the carbonatitic magma had a wide range of salinities 4 2 to 49 eq wt nacl and densities 0 77 to 1 26 g cm3 most of the fluids had relatively low concentrations of so42 and co32 6 wt however the nature of the trapped minerals and the phase behaviour of some inclusions indicate that some fluids may have had higher concentrations of so42 co32 and or hco3 textural relationships indicate that the crystallization sequence for the host minerals was monticellite apatite calcite which when combined with fluid inclusion data from the three minerals indicates that fluid salinity decreased and fluid density increased during progressive crystallization of the magma the density increase is thought to have been mainly caused by decreasing temperature isochoric projections indicate that the fluids were exsolved at minimum pressures of 4 to 8 kb these data provide a basis with which to assess the involvement of orthomagmatic aqueous fluids in the formation of hydrothermal rare element mineralization associated with carbonatites

40ar 39ar dating of latest pleistocene 41 ka marine tephra in the mediterranean sea implications for global climate records abstract fifty one 40 ar 39 ar laser heating analyses of sanidine crystals in the c 13 tephra layer recovered out of a piston core raised from 3000 m depth in the tyrrhenian sea yielded apparent ages between 25 and 112 ka twenty four of these measurements define an age probability maximum and generate an isochron of 41 1 2 1 ka 2 with a 40 ar 36 ar intercept of 288 21 that is indistinguishable from the modern atmosphere however the entire population is skewed toward older apparent ages with smaller peaks at 48 ka 55 ka 67 ka and 110 ka the composition of glass shards in the c 13 tephra overlaps that of the sio 2 rich phase of the 150 km 3 campanian ignimbrite which erupted from the campi flegrei caldera 130 km northwest of the core site although the 41 1 2 1 ka isochron is 15 older than k ar and 14 c ages for the campanian ignimbrite it is indistinguishable from recent 40 ar 39 ar age determinations the campanian ignimbrite eruptions were also chemically similar to and correlated with the y 5 ash layer the most voluminous and widely dispersed late pleistocene tephra in the mediterranean region the age of the y 5 layer was constrained originally at 38 0 2 5 ka on the basis of astronomical dating of o isotope stages the 40 ar 39 ar ages astronomical dating plus chemical similarities permit correlation of the c 13 tephra layer with both the campanian ignimbrite and the y 5 tephra layer the older ages preserved in the c 13 tephra layer may reflect xenocrysts incorporated during the explosive eruption accompanying collapse of the campi flegrei caldera 41 ka the c 13 tephra layer is correlated with a 10 be peak in an adjacent marine core o isotope stage 3 12 and immediately preceded a cooling episode corresponding to heinrich event 4 thus the age of these features is constrained by radioisotope dating the 41 ka peak in 10 be deposition is a global phenomenon whose age matches that of the laschamp geomagnetic excursion thus our results provide a new tie point among several polar ice core and marine proxy records of paleoclimate during the past 50 kyr precise age information independent of radiocarbon dating can be recovered from latest pleistocene marine tephra using the 40 ar 39 ar laser heating method despite the presence of multiple components that may have been incorporated during or after its deposition

crvena stijena revisited the late mousterian assemblages abstract crvena stijena represents one of the key middle paleolithic sites in southeastern europe in the course of earlier investigations the upper part of the mousterian sequence was excavated on two occasions in 1956 and 1958 by m brodar and from 1961 to 1964 by basler materials from these campaigns were published separately and interpreted differently after re analysis of all these materials it has been established that the artifact assemblages can not be directly assigned to any of the traditional facies denticulate mousterian micromousterian etc but rather to an undifferentiated non levallois facies of typical mousterian which is characterized by pronounced expedient technology based on the exploitation of local raw materials and the application of ad hoc methods of core reduction and the preparation of tools this re analysis pointed out especially that in the final mousterian at crvena stijena as at several other sites in the adriatic ionian region blade bladelet technology and uluzzian elements flaking of blades and bladelets from unipolar or bipolar cores on flakes splintered pieces backed tools are present this seems to indicate continuity and connection among cultural phenomena over the entire adriatic ionian region during mis3 and suggests the possibility that the uluzzian might have spread from the southern balkans towards italy along the southern rim of the great adriatic plain all of which could have belonged to a single social territory

esr dating of tooth enamel comparison with ams14c at el castillo cave spain abstract at el castillo in cantabrian spain uncalibrated ams 14 c dating has shown the transition from mousterian to aurignacian to occur at 39 3 1 6 ka bp we found esr tooth enamel ages from the basal aurignacian level at el castillo to be 36 2 4 1 ka early and linear uptake the enamel and dentine had very low u contents but esr ages are strongly dependent upon knowledge of the moisture content history of the sediments although the aurignacian esr age is 8 younger than the weighted average uncalibrated ams 14 c age of 39 6 1 3 ka obtained from charcoal samples we have shown that the methods agree within experimental uncertainty however since no precise 14 c calibration yet exists for this period of time we are unable to specify which of the ages is more accurate nor are we able ascribe the apparent age discrepancy to a particular deficiency in the esr method

tectonic evolution of northeastern siberia and adjacent regions abstract previous models for the tectonic evolution of northeastern siberia have proposed the existence of a kolyma plate composed of the kolyma and omolon massifs of presumed precambrian age lithologic similarities between the siberian platform and the cherskiy mountains and the presence of oceanic and island arc type deposits in the kolyma indigirka interfluve suggest that no such plate exists the eastern margin of the siberian plate is suggested to lie along a line between the ulakhan sis range the alazeya uplift and the arga tas range the cherskiy mountains and the verkhoyansk fold belt are parts of the siberian plate the paleozoic deposits of the omolon massif are unlike those found in the cherskiys or siberia paleomagnetic data from the omolon massif are discordant from data from siberia it is suggested that the omolon massif represents a microplate which accreted onto siberia in the jurassic ophiolites in central chukotka are of the same emplacement age as in the western brooks range and may have been emplaced at the initiation of the rotation of arctic alaska geometric and limited stratigraphic data suggest that the east siberian sea may be floored by oceanic crust left by an incomplete closure between arctic alaska siberia and omolon the tectonic position of the prikolymsk massif remains ambiguous

the campanian ignimbrite y5 tephra at crvena stijena rockshelter montenegro clearly defined distal tephras are rare in rockshelter sediment records crvena stijena a palaeolithic site in montenegro contains one of the longest 20 m rockshelter sediment records in europe with deposits ranging in age from middle pleistocene to mid holocene a distinctive tephra is clearly exposed within the well stratified record approximately 6 5 m below the present land surface we present geochemical data to confirm that this tephra is a distal equivalent of the campanian ignimbrite deposits and a product of the largest late pleistocene eruption in europe originating in the campanian volcanic province of southwest italy this tephra has been independently dated to 39 3 ka it is a highly significant chronostratigraphic marker for southern europe macrostratigraphic and microstratigraphic observations allied with detailed particle size data show that the tephra layer is in a primary depositional context and was transported into the rockshelter by aeolian processes this site is unique because the tephra forms an abrupt boundary between the middle and upper palaeolithic records before they can be used as chronostratigraphic markers in rockshelter and cave mouth environments it is essential to establish the stratigraphic integrity of distal tephras and the mechanisms and pathways involved in their transport and deposition

hydrological relationship between the north atlantic ocean and the mediterranean sea during the past 15 75 kyr the mediterranean sea hydrology at the time of the heinrich formation in the north atlantic ocean was analyzed by comparing sea surface temperatures ssts and oxygen isotope composition of seawater w changes during the past 75 kyr in two marine cores these were compared to the palynological variations derived in the mediterranean sea core during the last glacial the two oceanic sst records show similar and synchronous patterns with several long term cooling periods ending by abrupt sst increases at the time of the heinrich events cold ssts and low salinity prevailed in the mediterranean sea the freshwater budget was similar to the modern one permitting the presence of a mixed forest on the mediterranean borderlands the post heinrich periods are marked by a freshwater budget decrease limiting oak and fir tree growth in the mediterranean region increase of precipitation or reduction of evaporation is observed before the heinrich episode and is associated with a well developed mixed mediterranean forest

supercritical two phase separation of hydrothermal fluids in the troodos ophiolite the hot 350 c black smoker springs of the ocean floor are the vents of hydrothermal systems in which cold seawater descends below the ocean floor is heated reacts with the host rock and is transformed into metal bearing brine the salinity of these brines varies between vents from 0 7 to 2 0 times seawater salinity1 4 this variation has been ascribed to crustal hydration5 crystallization of chloride bearing minerals6 or two phase separation of seawater into components of differing salinity4 7 12 here we present fluid inclusion evidence for two phase separation in the ancient troodos sulphide forming systems of cyprus and discuss with the nacl h2o system as a model how this process could explain observed salinity variations in hydrothermal fluids

early cretaceous paleolatitude of the yukon koyukuk province alaska we report results from a paleomagnetic study of the yukon koyukuk province a key region for reconstructing the cretaceous paleogeography of northern alaska and northeastern asia the province lies between the displaced continental fragment of arctic alaska and the accreted terranes of southern alaska although lower cretaceous volcanogenic rocks of the yukon koyukuk province preserve primary remanent magnetizations the primary component is masked by a pervasive overprint the over printing magnetization which has dual polarity was acquired after a late cretaceous orogeny left the region highly deformed by fitting planes to tilt corrected thermal demagnetization data and solving for the best intersection of the corresponding remagnetization circles we separated the primary component presumably a vestige of the original thermoremanent magnetization from the overprinting component of the natural remanence the primary magnetization corresponds to a mean paleopole of early cretaceous age at 60 2 n 159 e the mean paleolatitude is 69 n with the 95 confidence ellipse ranging from 60 to 75 n this analysis was successful because the tilt corrections of the sampled strata had sufficient variation to ensure a strong intersection of the remagnetization circles we infer that lower cretaceous rocks of the brooks range and the yukon koyukuk province were once separated by a wide ocean basin that was closed by subduction probably during the cretaceous the northern limb of the angayucham terrane which lies between the brooks range and the yukon koyukuk province may contain remnants of the now closed ocean basin

elemental composition of concentrated brines in subduction zones and the deep continental crust abstract it has been well established that fluids played an important part in determining chemical characteristics in many crustal terranes studies of fluid inclusions in eclogites have established that brines coexisted with the primary mineral assemblages during their metamorphic crystallization these brines are currently multiply saturated in halide salts carbonates oxides and sulfides as a first step in quantitatively bounding the composition of the brines during metamorphism the equilibrium compositions of the brines at room temperature were computed using the aqueous speciation codes eq3 6 the results demonstrate that the brines are high density solutions ca 1 4 g cm 3 that have ionic strengths of approximately 8 mol and are approximately 40 dissolved solids by weight these are predominately na and k rich brines with subordinate ca and mg the approximate na k ca mg molar ratios are 4 2 0 5 0 2 but are sensitive to the assumed hco 3 concentrations charge balance is primarily maintained by the very high cl concentrations these brines bear resemblance to brines analyzed from fluid inclusions in metamorphic rocks reported by roedder roedder e 1972 composition of fluid inclusions us geol surv prof paper 440jj p 164 although these fluids have the potential of acting as significant metasomatic agents in subduction zones and deep crustal environments their impact will be mineralogically discernible only if the fluid release and movement is channelized

trace element rich brines in eclogitic veins implications for fluid composition and transport during subduction primary and pseudosecondary fluid inclusions occur in oscillatory and sector zoned omphacite in eclogitic veins from the monviso ophiolitic complex in the western alps the inclusions contain aqueous brines and daughter crystals of halite sylvite calcite dolomite albite anhydrite and or gypsum barite baddeleyite rutile sphene fe oxides pyrite and monazite this daughter mineral suite indicates high solubilites of na k ca mg fe zr ti p ba ce la th and s species and provides direct evidence for transport of high fieldstrenght large ion lithophile and light rare earth elements as dissolved species during subduction fluid inclusion heterogeneities preserved within and between adjacent grains in the veins however suggest that the scale of fluid equilibration was small a crack seal geometry in some of the veins implies that fluid release in pulses rather than steady flow controlled mineral deposition and growth in the veins from these observations we develop a model of fluid release and entrapment in which pulses of fluid are associated in time with increments of shear and tensile failure the rate of fluid release and the reduction in porosity both depend on the rate of plastic flow vein fluids may initially be derived from decreptitation of early fluid inclusions in the host eclogites small scale fluid heterogeneities implied by the fluid inclusions in the veins are best interpreted in terms of limited fluid flow and hence limited metasomatism we conclude that element recycling into the mantle wedge during subduction will depend at least as strongly on fluid transport mechanisms as on element solubilities in the fluid phase at monviso despite evidence for high trace element solubilities in saline brines the elements were not removed from the downgoing slab prior to teaching depths of 40 km

mirabilite solubility in equilibrium sea ice brines abstract the sea ice microstructure is permeated by brine channels and pockets that contain concentrated seawater derived brine cooling the sea ice results in further formation of pure ice within these pockets as thermal equilibrium is attained resulting in a smaller volume of increasingly concentrated residual brine the coupled changes in temperature and ionic composition result in supersaturation of the brine with respect to mirabilite na2so4 10h2o at temperatures below 6 38 c which consequently precipitates within the sea ice microstructure here mirabilite solubility in natural and synthetic seawater derived brines representative of sea ice at thermal equilibrium has been measured in laboratory experiments between 0 2 and 20 6 c and hence we present a detailed examination of mirabilite dynamics within the sea ice system below 6 38 c mirabilite displays particularly large changes in solubility as the temperature decreases and by 20 6 c its precipitation results in 12 90 and 91 97 reductions in the total dissolved na and so42 concentrations respectively compared to that of conservative seawater concentration such large non conservative changes in brine composition could potentially impact upon the measurement of sea ice brine salinity and ph whilst the altered osmotic conditions may create additional challenges for the sympagic organisms that inhabit the sea ice system at temperatures above 6 38 c mirabilite again displays large changes in solubility that likely aid in impeding its identification in field samples of sea ice our solubility measurements display excellent agreement with that of the frezchem model which was therefore used to supplement our measurements to colder temperatures measured and modelled solubility data were incorporated into a 1d model for the growth of first year arctic sea ice model results ultimately suggest that mirabilite has a near ubiquitous presence in much of the sea ice on earth and illustrate the spatial and temporal evolution of mirabilite within sea ice as it grows throughout an arctic winter reaching maximum concentrations of 2 3 g kg 1

age of the final middle palaeolithic and uluzzian levels at fumane cave northern italy using 14c esr 234u 230th and thermoluminescence methods abstract this article presents and discusses the chronological layout of the final mousterian and uluzzian levels of fumane cave in northern italy using 14 c esr and tl methods given its complex sedimentary and cultural succession fumane is a key site to assess the middle upper palaeolithic transition in southern europe and to explore neanderthal behaviour and to compare it with the first aurignacians large ranges defined by the esr and tl dates cover the radiocarbon ages for units from a11 to a4 respectively from 42 8 to 32 5 ka bp become progressively younger in agreement with the stratigraphy despite high dispersions within the same unit our estimates using chronometric data seem to support the hypothesis that the sequence may cover almost 10 000 radiocarbon yr and that from comparison with the sedimentological and palaeoecological data the late middle palaeolithic and the early upper palaeolithic at fumane occur in sediments formed under moderately cool to mild climatic conditions correlated to the hengelo interstadial shifting towards cooler and drier conditions finally comparisons between the fumane data set and other sites in the north adriatic region are discussed

rapid environmental changes in southern europe during the last glacial period oxygen isotope records from greenland ice cores1 2 indicate numerous rapid climate fluctuations during the last glacial period north atlantic marine sediment cores show comparable variability in sea surface temperature and the deposition of ice rafted debris3 4 5 in contrast very few continental records of this time period provide the temporal resolution and environmental sensitivity necessary to reveal the extent and effects of these environmental fluctuations on the continents here we present high resolution geochemical physical and pollen data from lake sediments in italy and from a mediterranean sediment core linked by a common tephrochronology our lacustrine sequence extends to the past 102 000 years many of its features correlate well with the greenland ice core records demonstrating that the closely coupled ocean atmosphere system of the northern hemisphere during the last glacial4 extended its influence at least as far as the central mediterranean region numerous vegetation changes were rapid frequently occurring in less than 200 years showing that the terrestrial biosphere participated fully in last glacial climate variability earlier than 65 000 years ago our record shows more climate fluctuations than are apparent in the greenland ice cores together the multi proxy data from the continental and marine records reveal differences in the seasonal character of climate during successive interstadials and provide a step towards determining the underlying mechanisms of the centennial millennial scale variability

tectonic implications of paleomagnetic poles from lower tertiary volcanic rocks south central alaska we have determined the paleolatitude of lower tertiary volcanic rocks in southern alaska to measure possible poleward translation of the wrangellia and the peninsular terranes after 50 m y ago previous paleomagnetic studies have shown that in triassic and jurassic time these terranes were located near the equator and have moved at least 3000 km poleward relative to the north american craton our sample localities are in the northern talkeetna mountains in mildly deformed andesite and dacite flows 50 4 51 3 53 9 and 56 3 m y by k ar that overlap lower cretaceous flysch lower permian volcanic rocks of wrangellia and upper triassic pillow basalt of the susitna terrane results from 26 cooling units 23 of reversed polarity and 3 of normal polarity give a mean paleomagnetic pole at 69 5 n 179 6 e 95 12 2 stratigraphic sections from opposite limbs of a syncline yield directional paths that pass the fold test satisfying a necessary condition for primary origin of the magnetization the corresponding mean paleolatitude 76 n of the northern talkeetna mountains is 8 10 higher than the latitude predicted from the eocene reference pole for north america therefore northward drift of the talkeetna superterrane which is the amalgamation of the wrangellia and peninsular terranes during and after middle jurassic time was probably complete by 50 m y ago our results are consistent with paleomagnetic poles from uppermost cretaceous and paleocene volcanic sequences in denali national park the lake clark region northern bristol bay region and near mcgrath these poles generally lie south of the cratonic poles suggesting that the region between the kaltag bruin bay and castle mountain faults has rotated counterclockwise relative to north america since the early eocene

on the age of the laschamp geomagnetic excursion abstract the laschamp geomagnetic excursion is a critical tie point found directly in deep sea sediment cores and revealed in polar ice as an abrupt change in the rate of cosmogenic nuclide flux despite the importance of this excursion to quantifying paleoclimate proxy records archived in sediment and ice and to providing an independent calibration of the radiocarbon calendar its timing remains poorly known previous k ar 40 ar 39 ar and u th isochron determinations from lava flows at the type locality in the massif central france vary widely are imprecise and suggest a mean age of about 46 2 2 5 ka 2 results of 6 new unspiked k ar and 13 40 ar 39 ar incremental heating experiments on subsamples from three sites on the laschamp and olby flows are concordant and give a weighted mean age of 40 4 1 1 ka 2 uncertainty including analytical sources only that is 10 younger than the previous estimates considering that the 40 k 40 ar decay constant is not known to a precision better than 2 4 the most probable radioisotopic age for the laschamp excursion is 40 4 2 0 ka 2 analytical plus decay constant uncertainties this new age for the laschamp excursion agrees precisely with that deduced from the napis 75 deep sea sediment paleointensity stack when calibrated against the gisp2 ice core chronology using the o isotopes in ice and the magnetic properties of the marine cores

plinian pumice fall deposit of the campanian ignimbrite eruption phlegraean fields italy abstract a plinian pumice fall deposit associated with the campanian ignimbrite eruption 36 ka phlegraean fields caldera italy occurs at the base of the distal grey ignimbrite in 15 localities spread over an area exceeding 1500 km2 between benevento and the sorrentina peninsula in the thickest stratigraphic section at voscone 130 cm 45 km east of the phlegraean caldera centre pozzuoli the deposit consists of two units the lower fall unit lfu is well sorted exhibits reverse size grading and is composed of equidimensional light grey pumice clasts with very subordinate accidental lithics the upper fall unit ufu is from well to poorly sorted crudely stratified richer in lithics and composed of both equidimensional and prolate pumice clasts the two fall units show slightly different dispersal axis n90 for the lfu and n95 for the ufu volumes calculated with the method of pyle 1989 are about 8 km3 for the lfu and 7 km3 for the ufu the maximum height of the eruptive columns are estimated using the model of the maximum lithic clasts dispersal at 44 km for the lfu and 40 km for the ufu classifying both fall units as ultraplinian in character reverse size grading within the lfu suggests an increase of the height of the column and magma discharge rate with time moderate sorting and crude stratification of the ufu are consistent with short period oscillation of the column possibly associated with repeated partial column collapses sharp increases in lithic content at the transition to ufu and within the ufu suggest that changes in the eruptive behaviour was produced by a dramatic increase in conduit vent erosion the phase of column instability preceded the emplacement of widely dispersed pyroclastic flow the ultraplinian nature of the fall fits well with the wide dispersal of the campanian ignimbrite with an estimated aspect ratio of 3 4 10 4 lari

14c activity and global carbon cycle changes over the past 50 000 years a series of 14c measurements in ocean drilling program cores from the tropical cariaco basin which have been correlated to the annual layer counted chronology for the greenland ice sheet project 2 gisp2 ice core provides a high resolution calibration of the radiocarbon time scale back to 50 000 years before the present independent radiometric dating of events correlated to gisp2 suggests that the calibration is accurate reconstructed 14c activities varied substantially during the last glacial period including sharp peaks synchronous with the laschamp and mono lake geomagnetic field intensity minimal and cosmogenic nuclide peaks in ice cores and marine sediments simulations with a geochemical box model suggest that much of the variability can be explained by geomagnetically modulated changes in 14c production rate together with plausible changes in deep ocean ventilation and the global carbon cycle during glaciation

ecosystem impact of the campanian ignimbrite eruption in late pleistocene europe the dating of the campanian ignimbrite ci eruption to 37 000 cal yr b p draws attention to the coincidence of this volcanic catastrophe and the suite of coeval late pleistocene biocultural changes that occurred within and outside the mediterranean region these included the middle to upper paleolithic cultural transition and the supposed change from neanderthal to modern homo sapiens anatomy a subject of sustained debate no less than 150 km3 of magma were extruded in the ci eruption the signal of which can be detected in greenland ice cores as widespread discontinuities in archaeological sequences are observed at or following the ci event a significant interference with ongoing human processes in mediterranean europe is hypothesized

multistage hydrothermal alteration of gabbroic rocks from the failed mathematician ridge oxygen isotopic mineralogical and fluid inclusion data are presented for fresh and hydrothermally altered gabbroic rocks from the failed mathematician ridge the mathematician ridge though initially a fast spreading ridge presently has a deep central rift valley more typical of slow spreading rifts the inner rift walls expose rare plutonic rocks uncomplicated by proximity to deep large offset fracture zones undeformed mathematician ridge gabbros preserve most of the original texture and phase compositions and have been only slightly mineralogically or isotopically modified by post crystallization hydrothermal alteration metagabbros have been subjected to a pervasive ductile deformation and recrystallization to foliated rocks composed of aluminous amphibole low calcium plagioclase and ilmenite oxygen isotope and phase chemical data suggest this event began at temperatures of up to 700 c water rock ratios of less than one and produced modified seawater fluids with isotopic compositions of 3 5 6 0 the amphibolites are cross cut by multiple generation quartz epidote veins forming a network replacement of the amphibole grade mineralogies by greenschist grade mineralogies fluid oxygen isotopic compositions of 2 4 and a two phase separation in the fluid captured in conjugate vapor fluid inclusions are all associated with the formation of this network fluid inclusion data for the quartz indicate initial temperatures of over 500 c these samples may represent rocks from the 1 2 km deep plumbing system of black smoker type venting

rotation of the colorado plateau an analysis of paleomagnetic data hamilton 1981 has proposed that the colorado plateau has rotated clockwise relative to cratonic north america by a total of 5 7 since mid cretaceous time a rotation this small is unresolvable by most paleomagnetic studies in this paper we present a new method for simultaneously comparing all of the available paleomagnetic data from on and off the plateau in order to estimate rotation of the colorado plateau our new method examines the effect of various hypothetical plateau rotations on the dispersion of data fit to a smooth model of apparent polar wander a maximum likelihood criterion is used to estimate the amount of rotation confidence limits are found using an f ratio test assuming the plateau craton euler pole to be located at 37 n 103 w we applied this method to north american paleomagnetic data of carboniferous to cretaceous age the best paleomagnetic estimate of the rotation is 3 9 clockwise with a 95 confidence interval of 1 4 6 6 clockwise in good agreement with geologic estimates of rotation because of the dependence of published north american apparent polar wander paths on data from the colorado plateau the existence of such a rotation requires a minor revision in the apparent polar wander path the largest change being a 3 9 eastward shift of the cusp connecting the carboniferous permian triassic and jurassic cretaceous tracks

plagioclase and epidote buffering of cation ratios in mid ocean ridge hydrothermal fluids experimental results in and near the supercritical region abstract experiments have been performed with na ca k cl fluids of seawater chlorinity and diabase basalt and plagioclase bearing mineral mixtures at 350 425 c and 250 400 bars to help constrain hydrothermal alteration processes at mid ocean ridges dissolved ca na and ph for all experiments responded systematically to differences in dissolved sio2 concentrations and the compositions of plagioclase reactants diabase alteration at low fluid rock mass ratios 0 5 to 1 produces fluids undersaturated with respect to quartz during hydration of primary olivine and orthopyroxene whereas basalt alteration under similar conditions yields fluids slightly supersaturated with respect to quartz during breakdown of glass to smectite and amphibole fluid chemistry in all experiments appears to approach a partial equilibrium state with the albite and anorthite components in plagioclase and approaches a ph consistent with plagioclase alteration to epidote trace element data from vent fluids specifically b and sr together with major element chemistry ca na sio2 ph provides evidence that the reaction zone for black smoker fluids at mid ocean ridges is composed of only slightly altered diabase and is characterized by small amounts of epidote nearly fresh plagioclase and clinopyroxene and partially to completely hydrated olivine and orthopyroxene fluids reacting with this rock may be undersaturated with respect to quartz so pressure estimates based on the quartz geobarometer should be regarded as minimums using equilibrium between plagioclase the dominant reactant and epidote the dominant reaction product in experiments we estimate that temperatures in reaction zones are in excess of 375 c for most vent systems these temperatures are higher than measured vent temperatures suggesting that hotspring fluids commonly loose heat during ascent to the seafloor

tephrostratigraphy and tephrochronology in the philippi peat basin macedonia northern hellas greece abstract three tephra layers have been identified in the upper 15 m of a 190 m section of peat beneath the philippi fen they provide significant lithological and chronological markers throughout the fen and the aegean region the upper tephra pht1 consists of shards of a transparent calcalkaline felsic glass and fragments of plagioclase augite hypersthene and rare hornblende magnetite apatite and quartz peat directly beneath pht1 gave a radiocarbon approximate age of 13 000 yr the middle tephra layer pht2 which resembles pht1 in chemistry and petrography but contains more crystals and lithic fragments rests on peat dated ca 18 000 14 c yr bp the lower tephra pht3 has colorless to brown glass shards with a trachytic chemistry and a mineral assemblage of sanidine sodic plagioclase biotite aegirine augite hornblende titanite and apatite bracketing radiocarbon ages imply that pht3 accumulated about 30 000 14 c yr bp the likely ages of pht1 and pht2 together with their mineralogical and chemical characteristics suggest that these tephras came from the volcanic field of thera in the hellenic arc pht2 particularly was derived from a major known explosive eruption ca 18 000 yr bp the cape riva eruption correlative to the y 2 tephra layer evidence for pht3 suggests derivation from the campanian province of italy and correlation with the campanian ignimbrite and the y 5 ash beneath the mediterranean sea

the campanian ignimbrite and codola tephra layers two temporal stratigraphic markers for the early upper palaeolithic in southern italy and eastern europe tephra layers from archaeological sites in southern italy and eastern europe stratigraphically associated with cultural levels containing early upper palaeolithic industry were analysed the results confirm the occurrence of the campanian ignimbrite tephra ci ca 40 cal ka bp at castelcivita cave southern italy temnata cave bulgaria and in the kostenki borshchevo area of the russian plain this tephra originated from the largest eruption of the phlegrean field caldera represents the widest volcanic deposit and one of the most important temporal stratigraphic markers of western eurasia at paglicci cave and lesser sites in the apulia region we recognise a chemically and texturally different tephra which lithologically chronologically and chemically matches the physical and chemical characteristics of the plinian eruption of codola a poorly known late pleistocene explosive event from the neapolitan volcanoes likely somma vesuvius for this latter we propose a preliminary age estimate of ca 33 cal ka bp and a correlation to the widespread c 10 marine tephra of the central mediterranean the stratigraphic position of both ci and codola tephra layers at castelcivita and paglicci help date the first and the last documented appearance of early upper palaeolithic industries of southern italy to ca 41 40 and 33 cal ka bp respectively or between two interstadial oscillations of the monticchio pollen record to which the ci and codola tephras are physically correlated corresponding to the greenland interstadials 10 9 and 5 in eastern europe the stratigraphic and chronometric data seem to indicate an earlier appearance of the early upper palaeolithic industries which would predate of two millennia at least the overlying ci tephra the tephrostratigraphic correlation indicates that in both regions the innovations connected with the so called early upper palaeolithic encompassing subsistence strategy and stone tool technology appeared and evolved during one of the most unstable climatic phases of the last glacial period on this basis the marked environmental unpredictability characterising this time span is seen as a potential ecological factor involved in the cultural changes observed

fluid induced retrogression of granulites in the bergen arcs caledonides of w norway fluid inclusion evidence from amphibolite facies shear zones abstract at holsnoy island bergen arcs caledonides of w norway amphibolite facies shear zones transect grenvillian granulite facies rocks within the shear zones the orthopyroxene bearing mineral assemblages of the protolith are replaced by biotite and amphibolite bearing parageneses the shear zones are assumed to have formed at t 600 75 c and within the kyanite field but below the stability of omphacite quartz veins central in the shear zones contain saline aqueous fluid inclusions representing a fluid phase with 2 16 wt nacl and a variable na ca ratio in areas with only static retrogression aqueous fluid inclusions with variable salinity from 5 to ca 50 wt nacl are associated with co2 inclusions with minor n2 contents xn2 4 6 mole the aqueous fluid was introduced during amphibolite facies metamorphism the carbonic fluid was inherited from the protolith the composition and density properties of the aqueous fluids are compatible with introduction at the assumed amphibolite facies conditions and suggest an uplift path sub parallel to their isochores the carbonic fluid inclusions have been re equilibrated during late stages of post metamorphic uplift the data presented highlight the differences between the fluid regimes in the granulite facies co2 eclogite facies n2 rich fluids and amphibolite facies h2o salt metamorphic events at holsnoy

distribution and chemical composition of tephra layers from eastern mediterranean abyssal sediments abstract most cores of late quaternary sediments from the eastern mediterranean sea contain many ash layers glass shards from discrete layers have been analysed chemically for major elements the layers from different cores have been correlated and unambiguously related to known volcanic events on the basis of the chemical data most of the layers are derived from explosive eruptions of the santorini volcanic complex other layers have their source in other volcanoes of the hellenic arc yali nisyros kos one layer originated from the campanian area italy

calibration of br cl fractionation during subcritical phase separation of seawater possible halite at 9 to 10 n east pacific rise abstract experiments were conducted to assess br cl fractionatiodn during phase separation of seawater at 400 c and 250 to 275 bars these conditions are applicable to the 9 10 n epr system where low cl concentrations and low br cl rations in vent fluids have been attributed to phase separation of seawater at conditions below the critical point of seawater 408 c 300 bars the level of br cl fractionation observed in experiments is well below that needed to account for br cl systematics at epr 9 10 n based on our experimental results we propose an alternative model involving dissolution and precipitation of halite to account for the anomalous br cl data at 9 10 n halite can be predicted to form at pressure and temperature conditions prevailing during eruption of magma at mid ocean ridges subsequent changes in physical conditions however would induce halite to dissolve and thus decrease br cl ratios of vent fluids

palaeomagnetism of lower cretaceous tuffs from yukon kuskokwim delta region western alaska during the past decade the prescient arguments1 3 for the allochthoneity of large portions of southern alaska have been corroborated by detailed geological and palaeomagnetic studies in south central alaska4 9 the alaska peninsula10 kodiak island11 12 and the prince william sound area13 fig 1 these investigations have demonstrated sizeable northward displacements for rocks of late palaeozoic mesozoic and early tertiary age in those regions with northward motion at times culminating in collision of the allochthonous terranes against the backstop of nuclear alaska14 15 a fundamental question is which parts of alaska underwent significantly less latitudinal translation relative to the stable north american continent thereby serving as the accretionary nucleus into which the displaced microplates 16 were eventually incorporated17 18 here we present new palaeomagnetic results from tuffs and associated volcaniclastic rocks of early cretaceous age from the yukon kuskokwin delta region in western alaska these rocks were probably overprinted during the cretaceous long normal polarity interval although a remagnetization event as recent as palaeocene cannot be ruled out this overprint direction is not appreciably discordant from the expected late cretaceous direction for cratonal north america the implied absence of appreciable northward displacement for this region is consistent with the general late mesozoic early tertiary tectonic pattern for alaska based on more definitive studies little to no poleward displacement for central alaska though substantially more northward drift for the southern alaska terranes comprising alaska peninsula kodiak island prince william sound area and matunuska valley since late cretaceous to palaeocene time

tephrostratigraphy of the last 170 ka in sedimentary successions from the adriatic sea abstract in this study are discussed new sem eds analyses performed on glass shards from five cores collected in the central adriatic sea and two cores recovered from the south adriatic sea a total of 26 tephra layers have been characterized and compared with the geochemical features of terrestrial deposits and other tephra archives in the area south adriatic sea and lago grande di monticchio vulture volcano the compositions are compatible with either a campanian or a roman provenance the cores located on the central adriatic inner and outer shelf recorded tephra referred to explosive events described in the literature ap3 sub plinian activity of the somma vesuvius 2710 60 14 c years bp avellino eruption somma vesuvius 3548 129 14 c years bp agnano monte spina phlegrean fields 4100 400 years bp mercato eruption somma vesuvius 8010 35 14 c years bp agnano pomici principali eruption phlegrean fields 10 320 50 14 c years bp neapolitan yellow tuff phlegrean fields 12 100 170 14 c years bp some of these layers were also observed in the south adriatic core in68 9 in addition to younger ap2 sub plinian eruption somma vesuvius 3225 140 14 c years bp and older layers pomici di base eruption somma vesuvius 18 300 150 14 c years bp significant is the tephra record of core rf95 7 that for the first time in the adriatic sea reports the occurrence of tephra layers older than 60 ka the well known mediterranean tephra layers x2 ca 70 ka w1 ca 140 ka and v2 roman origin ca 170 ka as well as other tephra layers attributed on the basis of geochemistry and biostratigraphy to explosive eruptions occurred at vico 138 2 and 151 3 ka bp and ischia 147 140 ka bp previous tephra correlations performed on other cores in the central adriatic sea were also critically revised according to new available data and integrated with the results of this study for a correlation at a regional scale the most important key beds for correlation are the agnano monte spina and neapolitan yellow tuff tephra layers which occur in both central and south adriatic sea other tephra layers younger than 15 ka are relatively less frequent the y1 etna 14 180 260 14 c years bp and agnano pomici principali in the more recent record in the shelf cores north of gargano promontory the ap3 tephra layer is also frequent

calibration of the c 14 timescale over the past 30 000 years using mass spectrometric u th ages from barbados corals uranium thorium ages obtained by mass spectrometry from corals raised off the island of barbados confirm the high precision of this technique over at least the past 30 000 years comparison of the u th ages with 14c ages obtained on the holocene samples shows that the u th ages are accurate because they accord with the dendrochronological calibration before 9 000 yr bp the 14c ages are systematically younger than the u th ages with a maximum difference of 3 500 yr at 20 000 yrbp the u th technique thus provides a way of calibrating the radiocarbon timescale beyond the range of dendrochronological calibration

relative motions between eurasia and north america in the bering sea region knowledge of the relative motion of the north american and eurasian plates during the late mesozoic and cenozoic provides insight into the observed timing and style of deformational events in the bering sea region periods of strong convergence from 70 to 50 ma maastrichtian to paleocene are correlated with compressional deformation between the chukotsk peninsula and northern alaska and movement along the denali fault the convergence may also be the cause of a previously proposed counterclockwise rotation of western alaska transform motion between these plates from 50 to 38 ma middle to late eocene correlates with subsidence of the bering shelf creation of a series of pull apart basins along the bering margin and cessation of calc alkaline volcanism in western alaska slight compressive convergence from 37 ma to the present may be responsible for the anticlinal deformation of basin filling sediments in the anadyr and khatyrka basins

volcanic aerosol records and tephrochronology of the summit greenland ice cores the recently collected greenland ice sheet project 2 gisp2 and greenland ice core project ice cores from summit greenland provide lengthy and highly resolved records of the deposition of both the aerosol h2so4 and silicate tephra components of past volcanism both types of data are very beneficial in developing the hemispheric to global chronology of explosive volcanism and evaluating the entire volcanism climate system the continuous time series of volcanic so42 for the last 110 000 years show a strong relationship between periods of increased volcanism and periods of climatic change the greatest number of volcanic so42 signals many of very high magnitude occur during and after the final stages of deglaciation 6000 17 000 years ago possibly reflecting the increased crustal stresses that occur with changing volumes of continental ice sheets and with the subsequent changes in the volume of water in ocean basins sea level change the increase in the number of volcanic so42 signals at 27 000 36 000 and 79 000 85 000 years ago may be related to initial ice sheet growth prior to the glacial maximum and prior to the beginning of the last period of glaciation respectively a comparison of the electrical conductivity of the gisp2 core with that of the volcanic so42 record for the holocene indicates that only about half of the larger volcanic signals are coincident in the two records other volcanic acids besides h2so4 and other so42 sources can complicate the comparisons although the threshold level picked to make such comparisons is especially critical tephra has been found in both cores with a composition similar to that originating from the vatnaoldur eruption that produced the settlement layer in iceland mid a d 870s from the icelandic eruption that produced the saksunarvatn ash 10 300 years ago and from the icelandic eruption s that produced the z2 ash zone in north atlantic marine cores 52 700 years ago the presence of these layers provides absolute time lines for correlation between the two cores and for correlation with proxy records from marine sediment cores and terrestrial deposits containing these same tephras the presence of both rhyolitic and basaltic shards in the z2 ash in thegisp2 core and the composition of the basaltic grains lend support to multiple icelandic sources torfajokull area and katla for the z2 layer deposition of the z2 layer occurs at the beginning of a stadial event further reflecting the possibility of a volcanic triggering by the effects of changing climatic conditions

hydrothermal alteration processes at midocean ridges experimental and theoretical constraints from ca and sr exchange reactions and sr isotopic ratios diabase and basalt were reacted with na ca k cl fluids of seawater chlorinity at 375 425 c 375 400 bars and fluid rock mass ratios of 0 5 1 0 to assess the role of basalt chemistry and texture on sr and ca mobility during high temperature hydrothermal alteration an additional experiment utilizing an 84sr spiked fluid was performed to help quantify reaction rates of processes affecting sr mobility the experimental results help to constrain reaction processes responsible for the chemistry of hot spring fluids at midocean ridges alteration of basalt and diabase is characterized by formation of tremolite actinolite smectite chlorite and clinozoisitic epidote smectite chlorite respectively diabase alteration produced dissolved sr ca ratios similar to those observed for ridge crest hot spring fluids whereas alteration of a mostly crystalline basalt produced significantly lower ratios this observation supports the premise that the sr ca ratios observed in vent fluids may be produced during deep seated reaction of the hydrothermal fluids with diabase dikes and or gabbro at relatively low fluid rock ratios and suggests that hydrothermal alteration of primary igneous minerals at relatively high temperatures 400 c leads to formation of a mineral with low dsr ca possibly hydrothermal plagioclase results of the 84sr spiked experiment indicated that only 4 of the sr in basalt was mobilized after 800 hours of reaction despite the fact that b and li were nearly quantitatively leached it is thus suggested that b and li are good indicators of the amount of fresh rock encountered by fluids while sr concentration and isotopic data can be used to estimate the degree of alteration that the sr bearing primary minerals have undergone the degree of alteration of subsurface reservoirs may be estimated by dividing the fluid rock ratio obtained for highly mobile elements by the fluid rock ratio obtained from path integrated sr isotope and concentration data based on this method for example it can be estimated that only 5 of the primary sr bearing minerals encountered by fluids in the subsurface at epr 21 n are actually converted to secondary phases

deep sea sediment records of the laschamp geomagnetic field excursion 41 000 calendar years before present 1 we have recovered two new high resolution paleomagnetic records of the laschamp excursion 41 000 calendar years b p from deep sea sediments of the western north atlantic ocean the records document that the laschamp excursion was characterized locally by 1 declination changes of 120 2 inclination changes of more than 140 3 1200 year oscillations in both inclination and declination 4 near 90 out of phase relationships between inclinations and declinations that produced two clockwise loops in directions and virtual geomagnetic poles vgps followed by a counterclockwise loop 5 excursional vgps during both intervals of clockwise looping 6 magnetic field intensities less than 10 of normal that persisted for almost 2000 years 7 marked similarity in excursional directions over 5000 km spatial scale length and 8 secular variation rates comparable to historic field behavior but persisting in sign for hundreds of years all of these features with the exception of anomalously large directional amplitude are consistent with normal magnetic field secular variation comparison of our laschamp excursion paleomagnetic records with other late quaternary excursion records suggests that there is a group of excursions which we term class i which have strikingly similar patterns of field behavior and likely share a common cause as part of the overall core dynamo process three general models of secular variation are described that can qualitatively produce class i excursions on the basis of these observations we conclude that class i excursions epitomized by the laschamp excursion are more closely related to normal secular variation and are not necessarily a prelude to magnetic field reversal

esr and ams based 14c dating of mousterian levels at mujina pecina dalmatia croatia abstract this paper presents the first chronometric dates for sediments that contain a mousterian industry in dalmatia south croatia electron spin resonance esr dating was conducted on two teeth from the mousterian level e1 at the site of mujina pecina additionally five bone and one charcoal sample from five different strata of origin at this site were dated by accelerator mass spectrometry ams assuming 30 moisture for both the gamma and beta dose rate calculations the mean lu esr age estimate is 44 5 ka for level e1 which is statistically indistinguishable from the mean eu esr age estimate of 40 7 ka a single uncalibrated 14 c age from the e1 e2 interface yielded an age estimate of 45 170 2780 2060 years bp while the mean of the five samples from overlying mousterian levels is 39 3 ka the true calibrated age of this mean is about 42 ka which means that the entire stratigraphic profile in mujina pecina apparently was very rapidly deposited and that the esr age regardless of uptake model is in good agreement with the calibrated 14 c mean age temporally mujina pecina overlaps with pontinian mousterian sites in west central italy and vindija level g3 from northwestern croatia however there are notable differences between the mousterian industry from mujina pecina and these other sites collectively the croatian sites yield important evidence on the adaptation of european mousterian people

electron spin resonance esr dating abstract esr dating has been systematically applied in earth sciences and archaeology since 1975 when ikeya dated a stalactite from the akiyoshi cave in japan in the meantime this new technique has been successfully applied to the dating of materials such as speleothems spring deposited travertines mollusc shells corals and tooth enamel the present research focuses on the dating of quartz which allows the age assessment of heated ceramics volcanic rocks intrafault material or windblown sediments esr dating is based on the measurement of the number of paramagnetic centers in a mineral these centers are generated by alpha beta and gamma radiation of the matural radioelements such as u th and k and have accumulated over time two parameters have to be determined the accumulated dose ad and the dose rate d to which the sample was exposed this review comprises three major parts a introduction into esr dating b application of the method and c appendices giving detailed description of dose rate calculation physical basis of electron spin resonance the esr spectrometer and esr lines the major emphasis lies on the outline of the application of esr dating this includes the discussion of the esr signals of the various materials sampling sample preparation and measurement techniques

paleolatitudes versus time for southern alaska paleomagnetic determinations of the inclination of the ancient geomagnetic field for localities in the alaska peninsula wrangellia chugach and kuskokwim tectonostratigraphic terranes of alaska show systematic northward motion from late cretaceous time until the present prior to this the ambiguity of polarity of the ancient geomagnetic field allow several interpretations however the preferred interpretation involves southerly motion of the terranes from triassic to early jurrassic time and steady northward motion from then up to the present the latitudinal rate is about 6 cm yr

reconstruction of the neanderthal and modern human landscape and climate from the fumane cave sequence verona italy using small mammal assemblages abstract fumane cave located at an altitude of 350 m a s l in the monti lessini in the veneto pre alps northeastern italy is a reference site for southern europe for the study of the behaviour of neanderthals and anatomically modern humans amh from marine isotope stages 5 to 2 mis5 mis2 it is one of the few well dated and closely studied sites in the italian peninsula with a finely layered sedimentary sequence from the mousterian to gravettian in this paper we present for the first time a palaeoenvironmental and palaeoclimatic reconstruction of the mis3 and mis2 sequence based on the small mammal insectivore bat and rodent assemblages the environmental and climatic results coupled with the radiocarbon dating together with previous studies on large mammals birds and charcoal and other studies on small mammals and pollen for the same time span in italy enable us clearly to identify distinct climatic periods within our data heinrich event 5 in units a7 to a6 greenland interstadial 12 in units a5 a6 to a4 heinrich event 4 in units a3 to a1 and heinrich event 3 in unit d1e finally the study shows that neanderthals and anatomically modern humans were well adapted to the different climatic and environmental conditions of mis3 at the foot of the alps

the compositional limits of fluid immiscibility in the system h2onaclco2 as determined with the use of synthetic fluid inclusions in conjunction with mass spectrometry abstract the compositional limits of fluid immiscibility in the system nacl h2o co2 were investigated from 500 to 700 c at pressures of 1 2 and 3 kbar synthetic fluid inclusions formed in quartz prisms were equilibrated with high temperature high pressure fluids in hydrothermal pressure vessels the inclusions were analyzed optically by mass spectrometry and by microthermometry the fields of immiscibility were defined as a function of temperature and pressure mass spectrometry was used to validate the existence of the immiscible fluids and to determine the co 2 h 2 o ratios of the two coexisting phases microthermometry i e the measurement of the melting temperature of solid sodium chloride was used in conjunction with the results of the mass spectrometry measurements to define the tie lines within the two phase fields isochores and the location of a portion of the isopleth were determined for composition nacl8 9 h2o76 1 co215 0

early tertiary paleomagnetic evidence and the displacement of southern alaska paleomagnetic data from early paleocene lavas a few kilometers north of lake clark just inboard of the peninsular terrane indicate modest post early tertiary latitudinal displacement and about 55 sup 0 of counterclockwise rotation of this region with respect to north america a nearby middle eocene sequence of lava flows however gives no indication of displacement or rotation south of lake clark the paleomagnetism of five paleogene 30 to 40 ma volcanic sequences that are a part of the peninsular terrane proper shows no northward translation and no rotation a major part of the northward movement documented by other studies in the gulf of alaska region may be accounted for by cumulatively significant intraterrane displacements 32 references 3 figures 1 table

correlation of a tephra layer in western greece with a late pleistocene eruption in the campanian province of italy abstract the kalodiki fen is a 2 km 2 mire in a small basin within a tectonic depression in epirus western greece since the last glaciation the basin has been occupied by a freshwater lake and has accumulated as much as 9 m of peat which continues to form today a 10 cm thick light brown to olive fine sandy layer appears in cores at depths ranging from 2 9 to 5 7 m the sand fraction of this layer consists mostly of pumice fragments and brown and colorless glass shards with similar major element compositions and it also contains crystal fragments of feldspars mainly sanidine ferromagnesian minerals and probably sphene and apatite the colorless glass has an index of refraction 1 519 0 002 a sample of the overlying peat layer gave a minimum radiocarbon age of about 31 800 1200 yr b p for the deposition of the tephra the likely age of the tephra its index of refraction and its mineralogical and chemical characteristics display strong similarities to tephra from the campanian province of italy mineralogically similar tephra layers have also been reported from a peat deposit at philippi in northeastern greece

a regional tephrostratigraphic framework for central and southern european climate archives during the last glacial to interglacial transition comparisons north and south of the alps abstract this paper summarises the results of tephrochronological investigations into a suite of central and southern european records which include rotmeer southern germany soppensee and rotsee central swiss plateau lago di lavarone and lago piccolo di avigliana italian southern alpine foreland these sites provide records of palaeoenvironmental changes for the last glacial to interglacial transition lgit at the boundary between north atlantic and mediterranean climatic influences chemical characterisation of glass shards in volcanic ash layers indicates that multiple volcanic sources have contributed to the central european tephra record amongst other volcanic markers the laacher see tephra originating from the eifel region of germany c 12 9 0 1 ka and the vedde ash from iceland c 12 1 0 1 ka are found co located within the sediments of rotmeer soppensee rotsee and lago piccolo di avigliana these key horizons which bracket the onset of the younger dryas stadial provide precise calendrically dated tie points around which a detailed picture of the timing of local and regional environmental transitions can be constructed using the co located tephra layers the re colonisation of northern italian catchment areas by quercus is shown to occur just prior to the deposition of the laacher see tephra layer whereas to the north of the alps quercus and other thermophilous trees do not reappear until several centuries after the deposition of the vedde ash furthermore the discovery of the vedde ash in lago piccolo di avigliana and lago di lavarone is indicative of atmospheric transport of polar air into southern europe during the younger dryas stadial matching evidence proposed for such transport of polar air during the last glacial maximum lgm

assessing the exploitation of double patinated artifacts from the late mousterian implications for lithic economy and human mobility in northern italy abstract the finding of recycled lithic artifacts in the mousterian stratigraphic sequences of grotta fumane grotta san bernardino and grotta broion in the southern alps has stimulated investigations into the economic behavior and technology of neanderthals during the late pleistocene these three archives preserve remarkable evidence dated from 90 ka and 40 ka and show distinct signatures in terms of lithic technology settlement and the provisioning of flint a study has been carried out with the aim to detect the possible differentiation of tools between expedient opportunistic vs curated planned and to identify the diverse aspects of tool kit provisioning to thus infer mobility and provisioning strategies from the identification of double patinae and from comparisons between these three sites it has been possible to identify occurrences of recycling consisting of the collection and exploitation of old cores and flakes in expeditious or curated procedures the evidence suggests that the recycling of old artifacts played a variable role in the neanderthal economic strategy the final middle palaeolithic in northern italy is recorded in a handful of sheltered sites and very few open air settlements that were visited for short term occupations or that were repeatedly used to accomplish complex tasks mostly aimed at the exploitation of mineral non mineral and subsistence resources huge quantities of lithic raw material as well as the geomorphic and ecological variability in the belt between the upper alluvial plain and the pre alps depict the context in which neanderthals lived and circulated in accordance with a model of low residential mobility

cosmogenic nuclides during isotope stages 2 and 3 abstract changes in the concentration of cosmogenic nuclides measured in natural archives are related mainly to changes in the cosmic ray induced production rate in the atmosphere but also to the subsequent transport and deposition processes which depend on the geochemical properties of the nuclides a comparison of 10 be and 36 cl data from ice cores from greenland ice cores and 14 c data from tree rings and other archives provides the following information for the isotope stages 2 and 3 1 changes in the cosmogenic nuclide production rate on time scales longer than approximately 2 kyr agree well with paleomagnetic data derived from deep sea sediments in particular the geomagnetic excursions leading to weak fields around 40 kyr bp laschamp and 32 kyr bp mono lake can be clearly seen 2 production variations on shorter time scales contain information on solar variability as an example the 205 yr devries cycle already known from the analysis of 14 c tree ring data during the holocene is also present in the 10 be data of the time period 25 55 kyr bp 3 a comparison of 14 c calculated using 10 be data with the measured 14 c record points to a reduction of the global deep water formation during the younger dryas cold event 4 using information available on the production rates of cosmogenic nuclides in the past derived from paleomagnetic data the paleoprecipitation rate can be calculated this is crucial for establishing precise time scales

geochemical and geophysical implications of the radiocarbon calibration abstract a precise and accurate chronological framework is crucial to study the dynamics of a variety of phenomena which occurred during the last 45 000 years although the 14 c dating method has been widely applied since the 1950s it is recognized that the atmospheric 14 c 12 c ratio has not been stable during the past in order to calculate accurate ages these fluctuations have to be corrected by means of a calibration curve obtained by comparing raw 14 c measurements with true calendar ages provided by independent dating methods the calibration curve obtained so far is characterized by a long term trend with raw 14 c ages being significantly younger than calendar ages during most of the last 45 000 years abrupt 14 c shifts which occurred over centuries to millennia are superimposed on this long term trend of decreasing atmospheric 14 c 12 c ratio to a certain extent it is possible to outline the different causes of atmospheric 14 c variations by considering complementary information obtained from other cosmogenic nuclides studied at different latitudes 1 most high frequency changes in the atmospheric 14 c 12 c ratio are linked to magnetic fluctuations of solar origin as revealed by studying the last three centuries for which direct observations of the sun are available a similar conclusion is derived by comparing 14 c 12 c events with 10 be and 36 cl concentration maxima in polar ice cores 2 the long term trend shift of 14 c ages is due to a long period of decreased shielding effect of the geomagnetic dipole field which occurred over the interval between 10 000 and 40 000 years bp this interpretation is supported by paleomagnetic measurements performed on volcanic and sedimentary rocks and by 10 be and 36 cl analysed in low and high latitude records 3 a prominent and rapid atmospheric 14 c 12 c excursion occurred between 13 000 and 11 500 cal yr bp thus corresponding to the younger dryas cold period by contrast with the 14 c variability mentioned above which is linked to 14 c production changes this so called 14 c age plateau is probably due to an abrupt variation in the rates of exchange within the global carbon cycle this interpretation is supported by independent geochemical proxies and by numerical modelling of the carbon cycle

calcium rich brines and other hydrothermal fluids in fluid inclusions from plutonic rocks oceanographer transform mid atlantic ridge abstract fluid inclusions in metagabbro plagiogranite and epidosite from the oceanographer transform mid atlantic ridge were investigated using microthermometric measurements and laser raman spectroscopy inclusions in quartz reveal the presence of a high salinity average 40 wt nacl cacl 2 high temperature 340 c calcium rich na ca about 1 by weight fluid in metagabbro and plagiogranite at room temperature these fluids bear a halite daughter crystal and may also contain small crystals of calcite titanite and hematite a low density vapor rich fluid bearing a small amount of co 2 is closely associated with the briney fluids in one sample all samples contain a population of high temperature 150 to 400 c aqueous liquid dominated fluid inclusions commonly of secondary origin having seawaterlike salinity 3 to 8 wt nacl equivalent we conclude that the calcium rich brines are produced by a combination of two processes fluid phase separation and segregation of brines from vapor prior to trapping to generate the high salinities and extensive fluid mafic rock interaction at low water rock ratio to promote the calcium enrichment later introduction along microfractures of low salinity modified seawater at high water rock ratio is recorded by the secondary fluid inclusions the chemical complexity and association with co 2 may indicate that there is a magmatic component to the brines in addition to a seawater source differences between the oceanographer transform brines and those reported in previous studies of oceanic and ophiolite samples are attributed to variations in the degree of water rock interaction the host rock lithology and the influence of a magmatic fluid component

problems with radiocarbon dating the middle to upper palaeolithic transition in italy abstract radiocarbon dating of material from late pleistocene archaeological sites is challenging small amounts of modern 14c labelled contamination will significantly affect the reliability of dates from the period producing erroneous results recent developments in sample pre treatment chemistry have shown that problems in reliable age determination during this period are surmountable in this paper we provide an example of one such case from the middle to upper palaeolithic transitional site of the grotta di fumane in northern italy we ams dated two fractions of the same charcoal samples derived from a series of superimposed mousterian aurignacian and gravettian levels excavated at the site one fraction was treated using the routine acid base acid aba method the other with the more rigorous acid base oxidation stepped combustion abox sc method the latter method produced consistently older and almost certainly more reliable results the eruption of the known age campanian ignimbrite from the phlegrean fields near present day naples at 39 3 ka yr bp seals ulluzzian and proto aurignacian levels in the south of italy equivalent cultural levels are present at fumane and the results obtained with the abox sc methods are consistent with the ages inferred for sites in the south of italy based on the presence of the campanian ignimbrite new results from a sample found beneath the campanian ignimbrite at the russian site of kostenki obtained using both the aba and abox sc methods are also presented they support the conclusion reached at fumane by demonstrating that in many cases the abox sc treatment effectively removes contamination where the aba treatment does not the results of the work offer a sobering examination of the problems inherent in the current radiocarbon database relating to the period and highlight the dangers of an uncritical use of the corpus of 14c results obtained over the last few decades based on our results we predict that more than 70 of the 53 previously available determinations from fumane are erroneously young a way forward is suggested using these improved chemical preparation methods applying analytical methods to characterise the material dated and testing existing site chronologies to establish which previous determinations are liable to be inaccurate

paleomagnetism of the late cretaceous early tertiary north central montana alkalic province paleomagnetic results have been obtained from the late cretaceous early tertiary igneous complexes of the north central montana alkalic province data from 94 sites in eocene volcanic and intrusive rocks give a paleomagnetic pole located at 82 0 n 170 2 e a95 3 5 k 18 6 while 36 sites in paleocene intrusions yield a paleomagnetic pole at 81 8 n 181 4 e a95 5 4 k 20 2 these poles differ by only 1 6 and are not significantly different statistically the 130 site virtual geomagnetic poles show no significant elongation and suggest no significant apparent polar wander apw during the period of magnetization of the igneous centers postmagnetization structural complications in these rocks are minimal the presence of a single predominant polarity in these intrusive complexes reinforces the radiometric age data that suggest that igneous activity within individual centers was of short duration the northcentral montana data together with other early tertiary cretaceous and mid tertiary paleomagnetic results require modification of our earlier apw chronology diehl et al 1980 it now appears that apw relative to north america since the early cretaceous consists of a polar still stand during much of the cretaceous 120 75 m y b p a period of rapid movement in latest cretaceous time 75 65 m y b p and a period of slow polar movement thereafter the onset of this period of rapid apw correlates well with a major change in plate motions at 80 m y and the beginning of the laramide orogeny

stratigraphy and sedimentology of the mid cretaceous deposits of the yukon koyukuk basin west central alaska the northeast trending yukon koyukuk basin of west central alaska consists of two subbasins the kobuk koyukuk subbasin to the north and east and the lower yukon subbasin to the southwest the subbasins are separated by an arcuate lower cretaceous volcanic pile the hogatza trend which is thought to be an accreted volcanic arc the oldest part of the sedimentary fill of the subbasins consists of valanginian to lower albian volcaniclastic rocks deposited on the flanks of the hogatza trend following subsidence of the hogatza trend mid cretaceous clastic sedimentary strata of mainly albian and cenomanian age and possibly as thick as 8000 m were shed into the basin these deposits were derived from surrounding uplands or borderlands in the seward peninsula to the west the brooks range to the north and the ruby geanticline to the southeast these mid cretaceous basin fill deposits can be divided into four main facies 1 basin margin conglomerate facies chiefly alluvial fan deposits that were transported basinward and rest in part unconformably on the surrounding uplands 2 shelf facies chiefly cross stratified and hummocky cross stratified sandstone deposited by wave generated currents on a shelf that rimmed the basin on its western and northern margins 3 deltaic facies chiefly sandstone and shale deposited in delta plain and delta front environments on a large constructional delta that prograded westward from the eastern basin margin across both subbasins and across the subsided southern part of the hogatza trend and 4 turbidite facies chiefly interbedded sandstone and shale deposited as elongate deep sea fans and related deep sea clastic systems by flows that transported sediment to the axial parts of both subbasins northeastward in the lower yukon subbasin and eastward to southward in the kobuk koyukuk subbasin sedimentation appears to have ended in the santonian followed by uplift folding and faulting of the basin fill less deformed lower tertiary nonmarine volcanic and volcaniclastic rocks unconformably overlie the more highly deformed cretaceous strata

a 90 000 200 000 yrs marine tephra record of italian volcanic activity in the central mediterranean sea abstract a detailed tephrochronological study was undertaken in three deep sea cores collected in the tyrrhenian and ionian seas the age and the origin of the marine tephra were inferred from oxygen isotope records of foraminifera and from major element compositions of glass shards seventy one eruptions were detected in the time interval 90 000 200 000 yrs during which the volcanoes of the roman and campanian regions and of the southern italy were in activity this is attested by the consistency of the geochemical compositions of both marine and terrestrial deposits most of the marine tephra consisted in trachytes and phonolites characterizing a roman and campanian origin several tephra were proposed as key horizons for proximal and distal sediments among them one tephra originating from mount etna 149 300 yrs and five tephra from pantelleria island 130 000 yrs 163 600 yrs 192 500 yrs 197 400 yrs and 198 400 yrs were northerly dispersed several other key horizons originated from the campanian or roman provinces were detected as far as 1000 km from the vents

pleistocene ice caps on the coastal mountains of the adriatic sea ice caps once covered large areas of mount orjen 1894 m on the adriatic coast of montenegro bosnia herzegovina croatia the largest ice cap covered an area of c 165 km2 and reached a maximum ice thickness of c 450 m in some areas reaching down to 500 m above modern sea level u series dating of secondary carbonates within moraines indicates that the most extensive glaciation occurred during the middle pleistocene correlating with a major phase of glaciation in greece to the south during mis 12 c 480 430 ka later less extensive glaciations are also recorded in the cirques and valleys and correlate with glaciations during mis 6 190 130 ka and mis 5d 2 110 11 7 ka each phase of glaciation would have required large amounts of snow accumulation under modern precipitation values which at c 5000 mm are some of the highest in europe mean annual temperatures would need to be only c 5 6 c lower in order to form similar sized glaciers today a mean annual temperature depression of 12 13 c would still require 1000 mm of snow accumulation water equivalent to balance ablation suggesting sustained moisture supply during pleistocene cold stages such sustained precipitation supply during pleistocene cold stages is likely to have been facilitated by major temperature contrasts between the european landmass and the mediterranean sea which are likely to have sustained lee side vortices to the south of the alps in the gulf of genoa and adriatic sea forming weak moisture bearing depressions which tracked across the eastern adriatic coastal mountains large ice caps on the dinaric alps would have blocked the inland penetration of these depressions resulting in much drier conditions in the balkan interior creating favourable conditions for the deposition of thick accumulations of loess the last glaciers on orjen formed during the younger dryas 12 9 11 7 ka and confirm the influence of north atlantic ocean circulation on pleistocene climate change in this part of the mediterranean

calcium and sodium exchange during hydrothermal alteration of calcic plagioclase at 400 c and 400 bars a series of experiments were conducted to measure the effect of plagioclase composition on the composition of coexisting cl dominated hydrothermal fluids assemblages containing quartz and natural plagioclase with a composition of either an60 or an82 were reacted with na ca cl fluids at 400 c and 400 bars using flexible cell hydrothermal facilities plagioclase remained homogeneous during these experiments despite the fact that homogeneous solid solutions with intermediate compositions are likely metastable with respect to mechanical mixtures at these conditions it was found that ca and na exchange between fluids and minerals appears to be reversible and highly dependent on plagioclase composition but mca m2na ratios remained constant with increasing cl for a given plagioclase composition in fact a solid solution model which approaches ideal behavior appears to account best for the chemistry of fluids coexisting with an60 and an82 plagioclase these data may have a direct bearing on hydrothermal alteration processes responsible for the chemistry of hot spring fluids at mid ocean ridges which appear to have equilibrated with metastable plagioclase solid solutions of composition an60 to an70

applying high throughput rrna gene sequencing to assess microbial contamination of a 40 year old exposed archaeological profile abstract in recent years there has been a surge in the recovery of ancient organic molecules from archaeological contexts these analyses are yielding unprecedented insights into human evolution and cultural practices and are providing valuable data for reconstructing paleoenvironments however contamination of archaeological sediments by microorganisms can alter ancient biomolecular data furthermore the extent to which microbes can penetrate ancient archaeological sediments once these are exposed by excavation is unknown we tested this question at crvena stijena a rock shelter in the dinaric alps in montenegro that contains archaeological deposits spanning more than 80 000 years excavations in the early 1960s exposed these profiles which have been cleaned several times to permit sampling for archaeological geological and biomolecular analyses the growth of green biofilms on the exposed profiles after cleaning has prompted the question of whether this surface contamination extends into the profile to test this question we examined five different geological layers by sampling sediments from the exposed surface and at 1 cm intervals horizontally into the profile results from 16s rrna gene sequencing show that samples from sediment surfaces have distinct microbial communities from most samples collected more than 1 cm deep and microbial biomass from the deeper samples is very low together this evidence strongly indicates that microbial contamination is limited to the profile surfaces this lowers the likelihood that ancient biomolecules in these sediments have been altered by recent changes to the in situ microbial community and that cleaning of the profiles before sampling may not need to exceed 2 cm in depth these results lend further support to the research utility of limited vertical sampling along archaeological profiles and witness sections a strategy which conserves rare and limited archaeological deposits while helping to tackle key questions about the past

the modern human colonization of western eurasia when and where dating the timing of the replacement of local neandertal populations by modern humans in western eurasia at the dawn of the upper palaeolithic remains challenging due to the scarcity of the palaeontological evidence and to the complexity of the archaeological record furthermore key specimens have been discovered in the course of excavations that unfortunately did not meet today s archaeological standards the importance of site formation processes in the considered time period makes it sometimes difficult to precisely assign fragmentary remains a posteriori to distinct techno complexes the improvements in dating methods have however allowed for the clarification of many chronological issues in the past decade archaeological and palaeontological evidence strongly suggest that the initial modern colonization of eastern europe and central asia should be related to the spread of techno complexes assigned to the initial upper palaeolithic this first expansion may have started as early as 48 ka cal bp the earliest phases of the aurignacian complex protoaurignacian and early aurignacian seem to represent another modern wave of migrations starting in the levant area the expansion of this technocomplex throughout europe completed the modern colonization of the continent the interpretation of a third group of industries referred to as transitional assemblages in western and central europe is much debated at least in part these assemblages might have been produced by neandertal groups that may have survived until c 41 ka cal bp according to the directly dated neandertal specimens of saint c france and spy belgium 2014 the author published by elsevier ltd this is an open access article under the cc by nc nd license http creativecommons org licenses by nc nd 3 0

radiocarbon dating and chronology of the early upper paleolithic at kostenki abstract investigations during the last 5 years at kostenki central russia voronezh area have uncovered several new archeological assemblages dating to the earliest phase of upper paleolithic occupation 36 42 ka these discoveries in conjunction with an expanded scope of research at kostenki have forced a reassessment of the east european early upper paleolithic record and generated a set of new questions the paper addresses one of the most important of these questions the problem of two discordant chronological time scales one based on radiocarbon evidences and another on various analyses by pertinent disciplines paleomagnetism palynology tephrochronology and others

nitrogen bearing aqueous fluid inclusions in some eclogites from the western gneiss region of the norwegian caledonides minerals in eclogites from different localities in the western gneiss region of the norwegian caledonides age 425 ma contain a variety of fluid inclusions the earliest inclusions recognized are contained in undeformed quartz grains protected by garnet and consist of h2o n2 with x text h text 2 text o geqslant 0 8 the reconstructed p v t x properties of these fluid inclusions are compatible with peak or early retrograde metamorphic conditions matrix minerals quartz garnet apatite plagioclase contain a complex pattern of mostly truly secondary inclusions dominated by co2 and n2 the textural patterns and p v t x properties of these inclusions are incompatible with the high pressures of the eclogite forming metamorphic event but suggest that they were formed during uplift by a combination of remobilization of preexisting inclusions and influx of external fluids the fluid introduced at a late stage was dominated by co2 and did not contain n2 the present data agree with theoretical predictions of eclogite fluids from mineral equilibria and highlight the differences between granulite co2 and eclogite h2o n2 fluid regimes the provenance of the nitrogen in the eclogite fluid inclusions represents an important but unsolved question in the petrology of high pressure metamorphic rocks