potential links between surging ice sheets circulation changes and the dansgaard oeschger cycles in the irminger sea 60 18 kyr surface and deepwater paleoclimate records in irminger sea core so82 5 59on 31 ow and icelandic sea core ps2644 68on 22ow exhibit large fluctuations in thermohaline circulation thc from 60 to 18 calendar kyr b p with a dominant periodicity of 1460 years from 46 to 22 calendar kyr b p matching the dansgaard oeschger d o cycles in the greenland ice sheet project 2 gisp2 temperature record grootes and tuiver 1997 during interstadials summer sea surface temperatures sstsu in the irminger sea averaged to 8oc and sea surface salinities sss averaged to 36 5 recording a strong irminger current and atlantic thc during stadials sstsu dropped to 2o 4oc in phase with sss drops by 1 2 they reveal major meltwater injections along with the east greenland current which turned off the north atlantic deepwater convection and hence the heat advection to the north in harmony with various ocean circulation and ice models on the basis of the ird composition icebergs came from iceland east greenland and perhaps svalbard and other northern ice sheets however the southward drifting icebergs were initially jammed in the denmark strait reaching the irminger sea only with a lag of 155 195 years we also conclude that the abrupt stadial terminations the d o warming events were tied to iceberg melt via abundant seasonal sea ice and brine water formation in the meltwater covered northwestern north atlantic in the 1 1460 year frequency band benthic 15 80 brine water spikes led the temperature maxima above greenland and in the irminger sea by as little as 95 years thus abundant brine formation which was induced by seasonal freezing of large parts of the northwestern atlantic may have finally entrained a current of warm surface water from the subtropics and thereby triggered the sudden reactivation of the thc in summary the internal dynamics of the east greenland ice sheet may have formed the ultimate pacemaker of d o cycles

marine derived 14c calibration and activity record for the past 50 000 years updated from the cariaco basin abstract an expanded cariaco basin 14c chronology is tied to 230th dated hulu cave speleothem records in order to provide detailed marine based 14c calibration for the past 50 000 years the revised high resolution cariaco 14c calibration record agrees well with data from 230th dated fossil corals back to 33 ka with continued agreement despite increased scatter back to 50 ka suggesting that the record provides accurate calibration back to the limits of radiocarbon dating the calibration data document highly elevated 14c during the glacial period carbon cycle box model simulations show that the majority of observed 14c change can be explained by increased 14c production however from 45 to 15 ka 14c remains anomalously high indicating that the distribution of radiocarbon between surface and deep ocean reservoirs was different than it is today additional observations of the magnitude spatial extent and timing of deep ocean 14c shifts are critical for a complete understanding of observed glacial 14c variability

absolute calibration of the greenland time scale implications for antarctic time scales and for δ14c abstract we propose a new age scale for the two ice cores grip and gisp2 that were drilled at greenland summit based on accelerator mass spectrometry 14c dating of foraminifera in core md95 2042 paleoceanography 15 2000 565 calibrated by means of recently obtained paired 14c and 230th measurements on pristine corals marine radiocarbon calibration curve spanning 10 500 to 50 000 years bp thousand years before present based on paired 230th 234u 238u and 14c dates on pristine corals geological society of america bulletin 2003 submitted for publication the record of core md95 2042 can be correlated very precisely to the greenland ice cores between 30 and 40 ka bp our scale is 1 4 ka older than the grip ss09sea time scale journal of quaternary science 16 2001 299 at the older end of marine isotope stage 3 we use published 230th dates from speleothems to calibrate the record using this scale we show a 14c record that is broadly consistent with the modelled record earth planet sci lett 200 2002 177 and with the data of hughen et al science 303 2004 202 but not consistent with the high values obtained by beck et al science 292 2001 2453 or by voelker et al radiocarbon 40 1998 517 we show how a set of age scales for the antarctic ice cores can be derived that are both fully consistent with the greenland scale and glaciologically reasonable

luminescence chronology of the upper pleistocene loess record at kurtak in m iddle siberia abstract the loess palaeosol sequence of kurtak situated at the western bank of the upper yenisei in middle siberia represents one of the best developed middle and upper pleistocene sediment records in yenisei siberia more than 40 m thick loess and loess like sediments intercalated by at least four pedocomplexes are exposed at a steep erosional slope at the bank of the krasnoyarsk water reservoir infrared optically stimulated luminescence irsl and thermoluminescence tl dating techniques have been applied on 38 fine grain samples from the upper 23 m of the profile representing the penultimate and last interglacial glacial cycle the irsl and tl age estimates are in good agreement with the geological estimates up to the last interglacial soil horizon oxygen isotope substage ois 5e the luminescence ages show that the lowermost truncated palaeosol of kastanosjem type is likely to have formed during the penultimate interglacial upon subaerial deposits three weak reddish brown palaeosols intercalated by reworked loess like sediments correlate with early upper pleistocene interstadials ois5dion of a and a succession of humic horizons alternated by cryoturbation processes kurtak pedocomplex is linked with ois 3 thick loess deposits between the pedocomplexes show now significant age increase with depth indicating high accumulation rates at around 23 ka ois 2 and 60 ka ois 4

origin and consequences of cyclic ice rafting in the northeast atlantic ocean during the past 130 000 years deep sea sediment cores recovered from the northeast atlantic ocean were examined in order to elucidate the influence of the earth s orbital parameters on major ice rafting analyses of coarse grained ice rafted debris and planktonic foraminifers revealed a strong reaction to the precession signal since 130 000 yr b p dropstone layers have been deposited each half period of a precessional cycle 11 000 1000 yr ice rafting occurs during times of winter minimum summer maximum insolation and summer minimum winter maximum insolation in the first case high summer insolation forces meltwater discharge from the ice sheets into the polar seas which subsequently enhances formation of sea ice during the winter in the second case growth of continental ice enhances iceberg production which also leads to a salinity reduction of surface seawater both situations result in a southward penetration of polar water thus the marine record of dropstones documents ice rafting not only during weichselian stades but also during cold events within interstades the regularity of ice rafting yields a useful framework to calibrate and elucidate climatic changes not only in the region of the north atlantic ocean but also in remote areas such as the pacific ocean and the antarctic

riverine dunes on the coastal plain of georgia usa abstract relict eolian dunes on the georgia coastal plain line the north and east sides of many se trending streams and contain important paleoenvironmental information a detailed analysis of four dune fields characterizes dune geomorphology stratigraphy sedimentology and soils georgia s inland dunes range from parabolic to infilled parabolic to irregular in form typically merge to form long chains that parallel source streams and can occur as distinct bands typically the dunes are composed of 95 quartz sand grains with more than half the sand falling in the medium sand fraction dunes overlie flood plain and pointbar sands backswamp and peat deposits fluvial terraces and other dunes in places organic deposits occur on top of dunes cross bedding is observable in dunes more than about 4 m thick and indicates eastward dune migration paleosols found within some dunes indicate holocene reworking conditions favoring dune formation likely included at least seasonal aridity postdepositional modification of the dunes includes a smoothing of the dune surface a clay increase in the c horizon spodic horizon development bioturbation removal of weatherable minerals and fluvial incision

reconstruction of holocene high altitude vegetation cover in the french southern alps evidence from soil charcoal the study presented here from the southern french alps demonstrates the reliability of soil charcoal analysis for the study of holocene past treeline positions the occurrence of charcoal in mineral soils along transects from 1950 m up to 2920 m demonstrates the role of fire in the establishment of the present vegetation patterns the abrupt decrease of charcoal concentration at about 240 0 2 600 m which varies across the study sites corresponds to the modern transition between subalpine forest and alpine tundra charcoal particles formedinsitu providehighspatial resolutiondataforthereconstructionofpastforestandtreelinechanges soil charcoal analysis indicated that 1 treeline was 300 m higher around 6800 cal bp than today and 2 the uppermost forest belt up to 2810 m was colonized by larch larix decidua mill and arolla pine pinus cem bra l thispineispresenttodaybutpatchilydistributed itisabsentfromthethreeareasstudied radiocarbon dates ranging from c 6800 cal bp to the modern period along with historical and archaeological data sug gest that the present pattern of the uppermost forest belt and the patchy distribution of arolla pine in the stud ied area are the results of anthropogenic fire mainly agropastoral activities the question of global warming consequences on treelines in this part of the french alps is discussed

deflation and redeposition of sand dunes in finnish lapland abstract deflation and redeposition of aeolian sands in finnish lapland have been studied by analysis of their sedimentology and stratigraphy by dating buried charcoal layers and by obtaining tl dates the thickness of redeposited sands on buried soils ranges from a few decimetres to more than two metres original dune formation after deglaciation finished around 7000 bp subsequent aeolian activity has been mainly destructive in nature deflation started in some regions about 4800 bp continuing with several breaks until the present some deflation basins have stayed active for at least 1300 years however it is too early to draw general conclusions for the whole area forest fires have been important reactivators of aeolian sand drift but tend to be rather local events change in the ground water table is a basic factor affecting deflation at present human impact and overgrazing by reindeer seem to increase deflation

u series dating of locality 15 at zhoukoudian china and implications for hominid evolution this paper reports u series dates on speleothem samples from locality 15 at zhoukoudian one of the richest paleolithic sites in northern china the age of the lower part of layer 2 is securely bracketed between 155 000 and 284 000 yr the underlying layer 3 dates back at least 284 000 yr layer 4 further below should be older still possibly by a cycle on the specmap time scale before 284 000 yr ago these ages much greater than the previous estimates of 110 000 140 000 yr from u series and electron spin resonance dating of fossil teeth suggest that locality 15 was broadly contemporaneous with locality 4 new cave and with the uppermost strata of locality 1 peking man site the physical evolution and cultural development evidenced by the timing of the zhoukoudian localities are in line with the opinion of chinese anthropologists for a regional transition from homo erectus to archaic homo sapiens c 2004 university of washington all rights reserved

lower limit of hydrocarbon generation in source rocks a case study from the dongpu depression bohai bay basin east china abstract with the increasing demand for hydrocarbons exploration tends to be deeper and unconventional resources however whether there are the lower limits for exploration depth or thermal maturity ro appears to be particularly essential it is of considerable significance to determine the lower limit of hydrocarbon generation llhg since this limit can provide guidelines for hydrocarbon potential estimation according to the mechanisms of hydrocarbon generation and expulsion five methods are combined to determine and verify the llhg whose values can be expressed by llhg ro and llhg h source rock samples from the paleogene shahejie formation es in the dongpu depression were taken as an example to determine the llhg and then controlling factors of the llhg were discussed llhg ro values for es range from 3 23 to 3 97 average 3 71 and llhg h values range from 5244 m to 5525 m average 5433 m regionally llhg values display obvious differences between the northern and southern of depression llhg values in the north are roughly larger than those in the south in the northern depression the llhg ro values are ranging from 3 61 to 3 97 average 3 81 and llhg h values are ranging from 5415 m to 5545 m average 5488 m however in the southern part the llhg ro values range from 3 20 to 3 74 average 3 48 and the llhg h values range from 5265 m to 5375 m average 5278 m the main controlling factors for llhg diversity between the north and the south of depression are organic matter om type and abundance formation temperature and pressure

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

mid holocene environmental changes in the bay of skaill mainland orkney scotland an integrated geomorphological sedimentological and stratigraphical study a detailed multidisciplinary investigation of intertidal freshwater sediments exposed in the north of the bay of skaill mainland orkney scotland have revealed a complex sedimentary sequence this provided evidence for dynamic coastal environmental changes in the area since the mid holocene freshwater ponds developed on glacial sediments ca 6550 80 yr bp cal bc 5590 5305 from ca 6120 70 yr bp cal bc 5040 4855 these were infilled by blown sand from the distal edge of a dune ridge located to the west thereafter a series of sand blow events alternating with periods of quiescence occurred until ca 4410 60 yr bp cal bc 3325 2900 between ca 5240 160 and 4660 80 yr bp cal bc 4370 3115 pollen and charcoal records show evidence of anthropogenic activities associated with the nearby neolithic settlement of skara brae agriculture was probably affected by recurrent sand movement and widespread deposition of calcium carbonate in the hinterland of the bay machair development between ca 6100 and 5000 yr bp cal bc 5235 3540 corresponds to a mid holocene phase of dune formation recorded elsewhere in northwest europe the more recent and progressive formation of the bay has probably been related to increasing external forcing via storminess long term relative sea level change and sediment starvation within this exposed environment copyright 2000 john wiley sons ltd

charcoal and wood remains for radiocarbon dating upper pleistocene loess sequences in eastern europe and central siberia abstract the present paper concerns long upper pleistocene loess sequences from eastern europe with multiple upper palaeolithic occupations rich in charcoal as well as loess sequences from central siberia with abundant wood remains these complementary records have allowed establishing a high resolution climatic sequence integrating 24 interstadial episodes between ca 42 5 and 10 kyr bp here we discuss the methodology of dating used to fix the chronological framework of this climatic sequence based on a set of 240 available radiocarbon dates mainly produced on charcoal and wood remains special attention is paid to the strategy of sampling charcoal and wood material in strict accordance with stratigraphy as well as to the preparation process in the laboratory for extraction cleaning identification and selection of the best fragments to date careful stratigraphic drawing and detailed positioning of the samples for each geological layer are also considered in order to clarify the relationship of the obtained dates with respect to any sedimentary pedological or archaeological event to be dated the reliability and accuracy of the dates obtained from loess sequences are further controlled by the internal consistency with regard to stratigraphy palaeoenvironmental implications are also discussed

key factors controlling hydrocarbon enrichment in a deep petroleum system in a terrestrial rift basin a case study of the uppermost member of the upper paleogene shahejie formation nanpu sag bohai bay basin ne china abstract mineralogical petrographical geochemical analyses and fluid inclusions petrography and microthermometry were combined to investigate the basic properties of the source rock organic matter content kerogen type and thermal maturity and sandstone reservoirs composition pore systems porosity and permeability the hydrocarbon origin and the formation mechanisms of the deep 3 5 km petroleum system in the upper paleogene es1 the uppermost member of the shahejie formation in the no 3 structural belt in the nanpu sag bohai bay basin the results indicate that the es1 source rock is primarily composed of dark gray mudstone and presents a set of high quality source rocks 500 m average total organic carbon toc 1 38 in a mature stage maximum pyrolysis yield of 430 c 460 c the es1 sandstone is composed of lithic arkose formed in a braided river delta and has low porosity average 13 4 but moderate high permeability average 184 9 md the hydrocarbons originated from the es1 source rocks in the caofeidian subsag during two charging periods 10 ma and 3 ma the key factors controlling the formation of the deep petroleum system are as follows a high quality hydrocarbon supply b medium high permeability reservoirs c a favorable configuration of the source rock and reservoirs self generated and self accumulated and d late hydrocarbon charging the second factor is the most important the medium high permeability reservoirs are attributed to a high energy depositional environment distributary channels of braid delta front a high content of rigid detrital grains mainly quartz and metamorphic rock fragments provided by the archean granite provenance and the secondary pores formed by feldspar dissolution this study provides a new example for revealing the formation mechanisms of deep 3 5 km petroleum systems in the terrestrial rift basin across the bohai bay basin

charging history of paleogene deep gas in the qibei sag bohai bay basin china abstract the qibei sag qs at the western region of the bohai bay basin bbb eastern china has made significant progress in the deep gas exploration recently indicating that the deep gas reservoirs have good exploration prospects the deep gas reservoirs within the second member of the shahejie formation of the paleogene e2s2 are buried at approximately 5000 m the sources and hydrocarbon accumulation mechanisms were investigated by analyzing the regional structure integrating geologic and geochemical parameters of source rocks and natural gas analyzing results show that in the qs and adjacent areas qsaa three sets of source rocks e2s1 e2s2 e2s3 were developed which differ in organic chemical characters but have abundant organic matters in fair good standard affected by burial history e2s3 source rocks have entered into the high mature over mature stage and e2s1 source rocks are mainly in mature stage the methane content of natural gas 78 91 the methane carbon isotope value 41 3 34 6 and the positive carbon isotope sequence 13c1

plant landscape reconstruction above the current timberline at the monte cimone and corno alle scale mountain areas northern apennines italy during the late holocene the evidence from soil charcoal this paper presents the first pedoanthracological study carried out on two mountains of the northern apennines monte cimone and corno alle scale where the results provided new palaeoenvironmenta

holocene environmental change in subarctic aeolian dune fields the chronology of sand dune re activation events in relation to forest fires palaeosol development and climatic variations in finnish lapland sand dune stratigraphy radiocarbon dated charcoal layers palaeosol development and luminescence dating are used to reconstruct the holocene environmental history of the dune fields in finnish lap

geophysical investigations identify hidden deposits with great potential for discovering peking man fossils at zhoukoudian china the mysterious loss of five calvaria of homo erectus and three skulls of homo sapiens sapiens unearthed from zhoukoudian a world cultural heritage site during world war ii is a great loss for paleoanthropological research although frontal and occipital bones of homo erectus were unearthed in 1966 additional important human fossils cannot be found due to the fact that most of the fossil bearing deposits were removed in early diggings at zkd locality 1 the so called peking man site from 1995 to 2004 a series of in situ geological and geophysical investigations using electromagnetic electric panel magnetic microgravity electric tomograms surface seismic waves ground penetrating radar and test drilling methods were conducted on dragon bone hill where the peking man site is located here we report that some geophysical anomalies have been clearly detected and there are still significant deposits suitable for archaeological excavations in hidden cavities in the hill which demonstrate how some civil engineering methods can be employed for archaeological purposes

lake belau and its catchment northern germany a key archive of environmental history in northern central europe since the onset of agriculture the environmental history since the onset of agriculture was reconstructed from sediments and soils in the catchment area of lake belau schleswig holstein northern germany the established chron

late pleistocene landscape dynamics in saxony germany paleoenvironmental reconstruction using loess paleosol sequences abstract loess archives are of paramount importance for reconstructing regional paleoenvironmental conditions of past glacial periods the saxonian loess region is an area of transition between the western and the eastern european loess belt with this contribution a documented loess paleosol composite profile for the saxonian loess region is extended and a new chronostratigraphy established by high resolution osl dating of two profiles is described in addition for the first time osl age estimates for the loess paleosol sequence at seilitz are presented for the quartz and polymineral fine grain fraction based on the presented composite profile climatic and environmental conditions e g wind speed temperature are deduced based on high resolution osl dating it is possible to identify a hiatus spanning ca 30 ka this gap is located in the gleina complex where an underlying layer shows an age of ca 60 ka and the upper layer an age of ca 30 ka additionally two periods of strong loess accumulation with ages of ca 70 60 ka and 30 18 ka could be identified there is a general trend of grain size coarsening up towards the late glacial which shows a maximum at ca 21 ka correlations with french western german and polish loess sections are discussed

continuous dust concentration profile of pre holocene ice from the greenland ice sheet project 2 ice core dust stadials interstadials and the eemian in this paper we present and discuss the pre holocene dust profile of the greenland ice sheet project 2 gisp2 ice core retrieved from central greenland measured using laser light scattering lls from ice and compare it with the electrical conductivity method and oxygen isotope profiles we describe how we dated the pre holocene ice using the annual dust peaks observed with lls starting from the accepted chronology to 2250 m and obtained a chronology in substantial accord with the gas age dating of the ice we also show that the gisp2 ice core penetrated the eemian and that a record of a 10 2 kyr penultimate glaciation is present in the gisp2 core

quaternary environmental changes in the drylands of china a critical review abstract this paper reviews our current understanding of quaternary climate and landscape changes in the desert areas of northern china a key portion of the middle latitude drylands on earth combining earlier studies with our recent research and experience we offer a comprehensive picture of the state of chinese deserts during the quaternary and in the interest of enhancing future research identify knowledge gaps and areas of uncertainty lacustrine deposits found over an area ranging from china s western taklamakan desert to the eastern hunshandake sandy lands suggest that extensive lakes occurred in china s deserts during the pleistocene analysis of digital elevation models from srtm shuttle radar topography mission data supports this interpretation and shows the significant extent of these former lakes new estimates of mean annual evaporation of ca 1000 mm from lake surfaces and ca 100 mm from land surfaces confirms that local and regional rainfall is critical for maintenance of desert lakes in this temperate zone especially during intervals when the mean annual rainfall is more than 100 mm rapid shifts between sand seas and lakes in geologically and environmentally diverse settings suggest that the drylands of china are very sensitive ephemeral systems and not long lasting as previously thought available chronologies suggest that there were large lakes in the western taklamakan desert and the chadamu basin during mis marine isotope stage 3 at 30 ka probably related to a period of strong influence of northern hemispheric westerly winds channels and elevation models revealed by srtm data and remains of lacustrine sediments also indicate that there was a large lake in the hunshandake sandy lands in the eastern portion of the desert belt during the quaternary there is significant evidence that during the middle holocene strong summer monsoons led to a relatively large increase in moisture availability in the entire desert belt of northern china lacustrine records from the badain jaran desert in western inner mongolia suggest that it was generally dry before 10 cal ka becoming wetter from 10 to 4 cal ka and dry again afterwards study of palaeosols widely occurring in dune stratigraphy in the eastern portion of the desert belt suggests that there was a period of wet and warm climate in this region during the mid holocene optimum at a minimum between 6 ka and 4 ka but possibly lasting longer recent observations dealing with the generation and transport of dust from central asia indicate that the causal relationship between sand seas and loess sequences is not as close as previously assumed these results suggest that there is an urgent need to examine whether the frequency and amplitude of climatic variation in chinese deserts are somehow similar to that having occurred in the sahara desert of north africa deserts in northern china were also important focal regions for neolithic cultures during intervals when environmental conditions supported a denser vegetative cover there is evidence that some areas of woody vegetation to the west of badain jaran desert were deforested by humans by ca 4000 yr b p although it is still debatable whether humans have had a significant impact in other areas at that time opinions on the severity of desertification vary and are sometimes contradictory due to the lack of long term field based investigations

the greenland ice sheet project 2 depth age scale methods and results the greenland ice sheet project 2 gisp2 depth age scale is presented based on a multiparameter continuous count approach to a depth of 2800 m using a systematic combination of parameters that have never been used to this extent before the ice at 2800 m is dated at 110 000 years b p with an estimated error ranging from 1 to 10 in the top 2500 m of the core and averaging 20 between 2500 and 2800 m parameters used to date the core include visual stratigraphy oxygen isotopic ratios of the ice electrical conductivity measurements laser light scattering from dust volcanic signals and major ion chemistry gisp2 ages for major climatic events agree with independent ages based on varve chronologies calibrated radiocarbon dates and other techniques within the combined uncertainties good agreement also is obtained with greenland ice core project ice core dates and with the specmap marine timescale after correlation through the 18 o of o 2 although the core is deformed below 2800 m and the continuity of the record is unclear we attempted to date this section of the core on the basis of the laser light scattering of dust in the ice

neogene quaternary postrift tectonic reactivation of the bohai bay basin eastern china bohai bay basin located in eastern china is considered a cenozoic rifted basin the basin is atypical in terms of its neogene quaternary postrift subsidence history in that it experienced intensive tectonic reactivation rather than the relative tectonic quiescence experienced during this stage by most rift basins this neogene quaternary tectonic reactivation arose principally in response to two tectonic events 1 activity on a dense array of shallow faults and 2 accelerated tectonic subsidence that occurred during the postrift stage these two events were neither strictly temporally nor spatially equivalent the dense array of shallow faults form a northwest southeast trending belt in the central part of the basin with displacement induced by the reactivation of older northeast and northwest trending basement faults and an associated substantial component of strike slip displacement occurring after 5 3 ma the intensive reactivation of these faults contributed to the atypically accelerated rate of postrift tectonic subsidence of the basin that commenced ca however this was not the sole cause of this accelerated tectonic subsidence a combination of geological activity deep within the crust led to the buildup of intraplate stresses and this combined with ongoing thermal subsidence acted as an additional contributory factor that drove unusually high rates of subsidence for this basin this episode of accelerated postrift tectonic reactivation resulted in conditions favorable for hydrocarbon accumulation

anthracology and taphonomy from wood gathering to charcoal analysis a review of the taphonomic processes modifying charcoal assemblages in archaeological contexts abstract a discussion on the representativeness of charcoal from archaeological contexts and their potential for palaeoecological reconstruction is presented the charcoal deposits studied are the result of human activities and natural processes difficult to separate on the basis of their effects only this is why taphonomy should not be limited to the study of charcoal after the extinction of fire as a result our questioning has been widened to include the entire succession of processes from past vegetation to the anthracological diagram we propose a review of the taphonomic processes affecting anthracological assemblages in archaeological contexts from wood gathering to the analysis of charcoal results human practices appear clearly as the first filter determining or conditioning the assemblage the combustion process can induce a double filter by limiting the taxonomic information and by falsifying the initial quantity of burned wood post depositional agents represent a third level of filters between the vegetation and the anthracological assemblage finally sampling and quantification methods can also induce a distortion of the assemblage the aim of this paper is to present the state of the discipline today the problems already solved and the questions that remain to be studied

large scale controls on the development of sand seas in northern china abstract although sand seas are located in arid regions given that the proportions of dune areas vary greatly from region to region they are clearly influenced by other factors as well as aridity this paper discusses the distribution pattern and major features of sand seas and large fields of stabilized dunes in northern china and demonstrates the main influences on their development it appears that the availability of onsite loose sediments not wind strength is critical to the occurrence of the sand seas on a regional scale tectonic endorheic basins or areas of alluvial fans or forelands of mountain ranges are advantageous to the accumulation of fluvial sediments and thus are ideal locations of large sand seas in an arid climate the large dune fields currently stabilized by vegetation were active sand seas during the drier periods of the late pleistocene and early holocene the distribution patterns of chinese sand seas suggest that the height or size of the dunes in the sand seas are determined more by the availability of sands than any other potential factors as the sand seas in china account for a large portion of deserts in the middle latitudes of the northern hemisphere taklamakan is the second largest sand sea on earth knowledge of these sand seas past changes is important for understanding climatic changes in the terrestrial regions of mid latitudes

wood charcoal analysis at riwi cave gooniyandi country western australia abstract wood charcoals excavated from archaeological sites provide a useful tool for palaeoenvironmental reconstruction particularly in arid and semi arid zones where suitable catchments for palynological archives are often limited preservation of organic material in northern australia is characteristically poor and wood charcoal analysis provides a viable alternative to understand shifts in woody vegetation in the past the analysis of charcoal from matrix contexts at riwi cave located in the southern kimberley region of northern western australia has allowed a reconstruction of the local woody vegetation during occupation over the last 45 000 years the wood charcoal assemblage from the holocene stratigraphic units reflects the composition of the modern vegetation and illustrates that people were occupying the site during periods of relative humidity the pleistocene stratigraphic units show a shift in vegetation composition from eucalyptus spp to corymbia sp dominated savanna with an understory of secondary shrub associated with a late mis 3 arid event observed in both terrestrial and marine archives suggesting that activities continued at riwi during this arid event further anthracological analysis of other sites in the kimberley will help to build a regional picture of woody vegetation change and will further disentangle local and regional climatic signals particularly in relation to phases of occupation

new radiometric ages for the early upper palaeolithic type locality of brno bohunice czech republic comparison of osl irsl tl and 14c dating results new radiometric data are reported from the recent excavation of the type locality of the early upper palaeolithic entity of the bohunician recently obtained radiocarbon 14c data on charcoal are compared with new optically stimulated luminescence osl dating of sediment osl ages were determined on sediment from the archaeological occupation at brno bohunice as well as from the over and underlying loessic sediments multiple techniques were applied which all gave congruent results while a dual protocol post ir osl failed the quality criteria tests ages were obtained by multiple aliquot additive dose maad on polymineral material and single aliquot regeneration sar on fine grain quartz extract as well as on polymineral material fading tests show significant loss of infrared stimulated luminescence irsl after storage for 3 and 12 months for one sample but little or no fading for others the resulting uncorrected age estimates are smaller than those on quartz by osl methods the latter are considered to be more reliable estimates of the sedimentation age of these deposits the measured osl doses do not show a simple distribution and the lowest 5 was used for age calculation to represent the most likely sedimentation age the quartz from the loess overlying the archaeological layer is osl dated to 30 9 3 1 ka while the sediment for the paleosol which contains the archaeological layer gave an age of 58 7 5 8 ka the attribution of this paleosol to the hengelo interstadial is therefore questionable however if the hengelo interstadial is correlated with the dansgaard oeschger d o event 12 statistical agreement within 2 is achieved the osl result for the archaeological layer is in accordance with a weighted average tl date on heated flint artifacts of 48 2 1 9 ka from this layer as well as calibrated radiocarbon data calpal hulu 2007 from nearby locations however radiocarbon data on charcoal samples obtained during excavation at brno bohunice 2002 provide age estimates between 30 and 40 ka 14c years which translate to approximately 33 35 44 ka on the calendric time scale according to the hulu 2007 model for the underlying loess a depositional age of 104 3 10 6 ka was obtained by osl the presented osl ages indicate that a simple correlation of soil sequences between sites within a region has to be verified by chronometric dating

the siberian loess record and its significance for reconstruction of pleistocene climate change in north central asia abstract the siberian loess represents the most significant terrestrial proxy record of quaternary climatic history in northern asia loess is extensive in southern siberia between the irtysh basin in the west and the angara basin in the east palaeoenvironmental multi proxy data magnetic susceptibility ms grain size caco 3 toc pollen etc from high resolution loess palaeosol sections provide evidence for a strongly fluctuating climatic sequence in north central asia during the late quaternary displaying the globally diagnostic sequences found in the deep sea oxygen isotope records ms provides the most continuous and detailed record encompassing the last two interglacial glacial cycles in loess sections in the minusinsk basin yenisei area and on the northern altai plains evidence for periodic atmospheric shifts is provided by gradual changes in the main vegetation zones with parkland steppe and mixed taiga during warm interglacial interstadial stages being replaced by boreal tundra forest and arid periglacial tundra steppe during stadials climatic pulses from warm intervals to cold are recorded by incipient forest steppe tundra gleysols the occurrence of the highest sediment accumulation rates in glacial stages ois 4 and ois 2 in the southern plains and depressions indicates that the most intensive aeolian dust deposition followed the glacial maxima with the most recent interval dated to ca 19 15 ka bp because of its zonal distribution and pronounced climatic continentality the siberian loess region represents an important data source for reconstructing past climates in the northern hemisphere it provides a key to the correlation of other loess regions within the west east eurasian continental zone

oxygen 18 16 variability in greenland snow and ice with 10 3 to 105 year time resolution the 3 km long greenland ice sheet project 2 gisp2 ice core presents a 100 000 year detailed oxygen isotope profile covering almost a full glacial interglacial cycle measuranents of isotopic fluctuations in snow frost and atmospheric water vapor samples collected during summer field seasons up to 20 0 are compatible with the large and abrupt 80 160 changes observed in accumulated tim snow pit 15 80 profiles from the gisp2 summit area however show rapid smoothing of the 180 160 signal near the surface beyond about 2 m depth the smoothedi5180 signal is fairly well preserved and can be interpreted in terms of average local weather conditions and climate the longer climate fluctuations also have regional and often global significance in the older part of the record corresponding to marine isotope stages mis 5a to 5d the effect of orbital climate forcing via the 19 and 23 kyr precession cycles and the 41 kyr obliquity cycle is obvious from the end ofmis 5a at about 75 000 years b p till the end of the glacial at the younger dryas preboreal transition at 11 650 years b p the o180 160 record shows frequent rapid switches between intermediate interstadial and low stadial values fourier spectra of the oscillations that are superimposed on the orbitally induced changes contain a strong periodicity at 1 5 kyr a broad peak at 4 0 kyr and additional shorter periods detailed comparison of the gisp2 180 160 record with the vostok antarctica 15d record pacific ocean foraminiferal 180 160 grande pile france tree pollen and insolation indicates that a counterpart to many of the rapid 180 160 fluctuations of gisp2 can be found in the other records and that the gisp2 isotopic changes clearly are the local expression of climate changes of worldwide extent correlation of events on the independent gisp2 and specmap time scales for the interval 10 000 50 000 years b p shows excellent chronometric agreement except possibly for the event labeled 3 1 the glacial to interglacial transition evidently started simultaneously in the arctic and the antarctic but its development and its expression in greenland isotopes was later suppressed by the influence of meltwater especially from the barents sea ice sheet on deep water formation and ocean circulation meltwaters from different ice sheets bordering the north atlantic also influenced ocean circulation during the bolling allerod interstadial complex and the younger dryas and led to a distinct development of european climate and greenland 180 160 values the holocene interval with long term stable mean isotopic values contains several fluauations with periods from years to millennia dominant is a 6 3 year oscillation with amplitude up to 3 to 4 0 periodicities of 11 and 210 years also found in the solar modulated records of the cosmogenic isotopes 1obe and 14c suggest solar processes as the cause of these cycles depression of180 160 values cooling by volcanic eruptions is observed in stacked gisp215 80 records but the effect is small and not likely to trigger major climate changes

petroleum resources in the nanpu sag bohai bay basin eastern china the nanpu sag is an important secondary tectonic division of the bohai bay basin and has an area of 1532 km2 591 mi2 of which 1000 km2 386 mi2 has been explored near bohai recently exploration has gradually shifted from continental to beach to shallow marine settings with significant exploration breakthroughs having occurred in the nanpu 1 2 and 3 tectonic belts indicating good resource potential however a systematic resource assessment has yet to be performed which strongly restricts the exploration progress in this study we improved upon the pareto model and reevaluated the area s resource potential using two new methods in one method the traps are divided into several types including structural stratigraphic and buried hill traps to predict their individual resource potential and total resources of this area in the other method the normalized fluid potential is used to divide the area into several accumulation systems to calculate the resource potential the nanpu sag resources are estimated at 1 45 109 t 10 6 109 bbl which represents an increase of approximately 2 70 108 t 19 8 108 bbl compared with previous evaluations because of the increase in exploration maturity and information validation the main residual resource is distributed in beach to shallow marine settings the stratigraphic and buried hill traps present better resource potential using the trap type method such information can guide the direction of exploration and selection of potential traps

depositional systems and sequence architecture of the oligocene dongying formation liaozhong depression bohai bay basin northeast china the sequence stratigraphic framework and depositional systems of an oligocene lacustrine rift succession in the liaozhong depression of bohai bay basin in northeastern china were investigated using seismic profiles complemented by well logs and cores seven sequences are identified on the basis of unconformities on basin margins and correlative conformities in the basin center depositional systems are associated with systems tracts within sequences lowstand systems tracts are dominated by sublacustrine fans transgressive systems tracts are mainly composed of beach bar deposits and highstand systems tracts are characterized by deep lacustrine fan or braid delta deposits episodic tectonic movement was the principal factor that controlled the development of the sequences lake level changes resulting from climatic oscillations may have controlled the development of these sequences the balance between tectonic subsidence and sediment supply controlled the type of lake basin the bohai bay basin was a balanced fill basin in the early and middle stages of the dongying formation and evolved into an overfilled basin at the end of deposition of the dongying formation this study enhances the understanding of depositional system configuration and systems tracts in a typical rift basin and proposes that the most favorable sandstone reservoirs are developed in sublacustrine fan deposits relative lowstand sublacustrine fan deposits capped by relative highstand prodelta or deep lacustrine mudstones form the highest potential lithostratigraphic traps

an improved hydrocarbon generation potential method for quantifying hydrocarbon generation and expulsion characteristics with application example of paleogene shahejie formation nanpu sag bohai bay basin abstract to evaluate petroleum resources it is important to quantify the hydrocarbon generation and expulsion characteristics of source rock the hydrocarbon generation potential method is an efficient model for calculating the characteristics of source rocks and evaluating the resource potential the previous hydrocarbon generation potential model was mainly established by measured rock eval pyrolysis data and due to inappropriate preservation measures an important component volatile hydrocarbon content of source rock may be significantly reduced prior methods may therefore not objectively reflect the properties of a source rock and cause unacceptable errors in the resource assessment this study proposes an improved hydrocarbon generation potential method the new method considers the initial hydrogen index hi0 and transformation ratio tr during the evolution of source rocks which can more realistically reflect the hydrocarbon generation and expulsion history of source rocks therefore the hydrocarbon evaporative loss qloss is calibrated and the hydrocarbon generation and expulsion features of source rocks are more accurately evaluated the proposed method is used to examine the effectiveness of the third member of the upper paleogene shahejie formation es3 in nanpu sag by utilizing the improved hydrocarbon generation potential model the hydrocarbon expulsion threshold of the es3 source rock is positioned at ro 0 875 the maximum hydrocarbon generation and expulsion potential qg and qe are 593 78 and 323 78 mg hc g toc respectively and the maximum hydrocarbon expulsion efficiency is 54 the maximum hydrocarbon generation and expulsion intensities are 500 104 t km2 and 250 104 t km2 respectively which locate source rock at the laoyemiao and gaoshangpu structural belts the amounts of generated and expelled hydrocarbon are 13 7 108 t and 6 9 108 t respectively and the resource potential of the tight oil of the es3 in the nanpu sag is 0 69 104 t compared with the previous method the improved hydrocarbon generation potential method limits the maximum qg and calibrates the qloss therefore the new method more objectively reflects the hydrocarbon generation and expulsion characteristics and resource prospect of the source rock

zhoukoudian in transition research history lithic technologies and transformation of chinese palaeolithic archaeology abstract zhoukoudian near beijing is where the homo erectus sinathropus pekinensis peking man fossils were found in the 1920s and has always been a focus for studies of palaeolithic archaeology in china this paper discusses two aspects of zhoukoudian in transition research histories and lithic technologies from a historical perspective the study considers the change in research paradigms and perspectives to examine how research at zhoukoudian has transformed chinese palaeolithic archaeology in the last two decades this paper will give an overview on lithic assemblages at zhoukoudian to illustrate the complexity of lithic industries in north china which are not yet fully understood in conclusion the study suggests more research problems rather than prestige collections that were inherited by the current generation of scholars who call for careful reviews of valuable historic data including lithic faunal sediment and human remains before any further interpretations are produced this study suggests that lithic industries in transition at zhoukoudian can provide another line of evidence to support the continuous development of pleistocene hominid evolutions especially leading to the origins of modern humans in china

hydrological and climatic changes in deserts of china since the late pleistocene article i nfo article history large areas in western china were wetlands or less arid between 40 and 30 ka corresponding to the greatest lake period on the adjacent tibetan plateau during the last glacial maximum some of these western chinese deserts again experienced wetter conditions however at the same time the sandy lands in the eastern chinese desert belt experienced an activation of aeolian dunes while interpretations of the mid holocene environment in the deserts of china are controversial it is quite likely that it was more humid not only in the eastern areas influenced by monsoon climate systems but also in the western deserts where moisture is currently associated with westerlies evaluation of lacustrine records in the lakes recharged by dryland rivers and the complex interactions of these systems as well as other paleoenvironmental proxies such as the artemisia chenopodiaceae ratio should be interpreted with greater caution facing the highlighted uncertainties in our understanding of climate changes in chinese deserts it is hoped that this special issue will improve our knowledge considerably

assessing holocene vegetation and fire history by a multiproxy approach the case of stodthagen forest northern germany the woodland history of the forest of stodthagen northern germany was investigated by using complementary palaeobotanical indicators six soil profiles from the study plot were sampled the wood charcoal pieces extracted from the soil samples were quantified taxonomically identified and some were radiocarbon dated peat sequences from a small adjacent mire were also sampled and the pollen microcharcoal and macrocharcoal were analysed the pollen record shows a continuous forestation during the holocene with small indication of a disturbance phase during the late holocene this continuity of the woodland presence is confirmed by the weak quantity of macrocharcoal indicating that fire did not have a serious impact during the holocene in terms of canopy opening despite the identification of three local fire events however large amounts of wood charcoal pieces were found in the soil samples allowing the identification of at least one more fire event dated in the iron age unrecorded in the charcoa

dominance of an 150 year cycle of sand supply change in late holocene dune building along the eastern shore of lake michigan outcrops of buried soils on lake plains and glacial headlands along lake michigan s eastern shore suggest that periodic dunebuilding has occurred there after relatively long 100 yr periods of low sand supply we located described and radiocarbon dated 75 such buried soils that crop out in 32 coastal dune fields beside the lake we assume that peaks in probability distributions of calibrated 14 c ages obtained from wood charcoal and other organic matter from buried a horizons approximate the time of soil burial by dunes plotted against a late holocene lake level curve for lake michigan these peaks are closely associated with many 150 yr lake highstands previously inferred from beach ridge studies intervening periods of lower lake levels and relative sand starvation apparently permitted forestation and soil development at the sites we studied while late holocene lake level change led to development and preservation of prominent foredunes along the southern and southwestern shores of lake michigan the modern dune landscape of the eastern shore is dominated by perched dunes formed during 150 yr lake highstands over the past 1500 yr 2000 university of washington

anthropogenic influence on rates of aeolian dune activity within the northern european sand belt and socio economic feedbacks over the last 2500 years in north western europe pleistocene sand sheets have been reactivated during phases of holocene deforestation and agricultural land use although there are temporal overlaps between anthropogenic activity and sand sheet reactivation the root cause and subsequent feedbacks between aeolian activity and societal response remain largely unknown here we seek to establish cause and effect by examining the detailed co variation in both timing and magnitude of aeolian and anthropogenic activity through the quantification of holocene dune sediments in combination with archaeological and pollen records these records indicate a series of complex phases of aeolian activity followed by landscape stabilization which we attribute primarily to changing patterns of human impact we find that a steady increase in dune deposition rates in the medieval period corresponds to an increase in settlement activity and deforestation ad 1000 1500 at their peak medieval deposition rates were 3 4 times larger than during th

the absence of acheulean qiliting mode 1 site and the mode 1 occupations in southeast china abstract qiliting is an early to middle pleistocene open air site sealed within vermiculated laterite and xiashu loess in zhejiang province southeast china based on palaeomagnetic work at this site and stratigraphic comparisons the position of the artifacts in the xiashu loess indicates that human activities occurred in an upper cultural layer ca 0 30 0 12 ma a lower cultural layer in the vermiculated laterite is dated palaeomagentically by the kamikatsura event above this horizon in comparative section and the santa rosa event below it which estimated its age to 0 94 0 886 ma bp the flaking and tool modification strategies in the qiliting assemblages are those of a typical mode 1 industry which includes simple flakes and cores with limited modification of the modified tools scrapers and picks these features are also characteristic of the other regional sites as well as of many other early sites in south china no core preparation occurs nor any extensively retouched specimens the stone working is represented by a system of debitage sensu stricto and not by a compound system of debitage and shaping as occurs in mode 2 industry

evidence for massive discharges of icebergs into the north atlantic ocean during the last glacial period sediments in the north atlantic ocean contain a series of layers that are rich in ice rafted debris and unusually poor in foraminifera1 here we present evidence that the most recent six of these heinrich layers deposited between 14 000 and 70 000 years ago record marked decreases in sea surface temperature and salinity decreases in the flux of planktonic foraminifera to the sediments and short lived massive discharges of icebergs originating in eastern canada the path of the icebergs clearly marked by the presence of ice rafted detrital carbonate can be traced for more than 3 000 km a remarkable distance attesting to extreme cooling of surface waters and enormous amounts of drifting ice the cause of these extreme events is puzzling they may reflect repeated rapid advances of the laurentide ice sheet perhaps associated with reductions in air temperatures yet temperature records from greenland ice cores appear to exhibit only a weak corresponding signal moreover the 5 10 000 yr intervals between the events are inconsistent with milankovitch orbital periodicities raising the question of what the ultimate cause of the postulated cooling may have been

wood charcoal from an inland dune complex at joldelund northern germany information on holocene vegetation and landscape changes abstract the charcoal content of an inland dune complex close to joldelund in northern germany was analysed as part of a project which aims to reconstruct holocene aeolian activity in high spatial and temporal resolution the eleven investigated profiles contained numerous charcoal enriched layers providing evidence for the potential of inland dunes as palaeoarchives for anthracology earlier studies have found late roman iron age settlement activity and iron ore productions in the research area and in its vicinity charcoal assemblages date to roman iron age as well as early high and late medieval times according to radiocarbon dating of single species identified charcoal fragments and the stratigraphic correlation of sedimentary units the dominance of quercus oak and significant proportions of ericaceae charcoal probably calluna vulgaris heather especially in the early and high medieval samples indicate the presence of a heathland with quercus trees which was managed by fire in the younger layers of sand a greater diversity of taxa were found including the dominant quercus fagus beech alnus alder betula birch corylus hazel fraxinus ash salix willow populus salix poplar willow type acer maple pinus pine maloideae apple subfamily tilia lime as well as some ericaceae the diversity of species indicates that some charcoals were transported by wind together with the sand from the surrounding areas and do not represent the local vegetation on the dunes but rather a nonspecific regional input the differences in the charcoal assemblages and thus the possible correlation of aeolian units support the stratigraphic correlation of the sedimentary aeolian units the comparison with the available pollen data from nearby mires showed a good agreement of the proportions of woody taxa with only few exceptions

ancient pine forest on inland dunes in the spanish northern meseta abstract we present a new stratigraphic pollen and nonpollen microfossils and charcoal particle sequence with five ams dates covering about the last 9000 yr of a core collected from the spanish northern meseta one of the territories of the iberian peninsula for which little paleobotanical information is available the results support the hypothesis of the permanence of the pine forests in more or less pure masses or large timber stands during the holocene in some iberian continental zones the typical substitution in postglacial dynamics of heliophyllous species such as pines or cupressaceae by broadleaf trees did not occur in this inland region presumably factors linked to the substrate in this case very deep sand dunes covering vast areas may have contributed to the scarce local competitiveness of the broadleaf trees which would account for the hegemony of pines in this region based on the dynamics of aquatic plants and nonpollen microfossils an initial phase previous to 7500 14c yr b p of high levels in the lake can be identified by high percentages of hydrophytes a progressive increase in helophytes and the gradual infilling of the lake over the last 5000 yr appear to indicate a phase of aridification similar to those established for the western mediterranean study of charcoal particles more abundant in the last 2500 yr has given rise to certain hypotheses regarding the incidence of recurring fires of a local or regional nature

in situ charcoal fragments as remains of natural wild fires in the upper wurm of the carpathian basin charcoal layers were found in loess layers of the younger wurm period at 11 localities around kopasz hill tokaj in the carpathian basin detailed sedimentological geochemical radiocarbon palaeontological and anthracological investigations show that picea containing taiga forest steppe habitats existed on the area between 29 000 and 21 000 years bp on the basis of radiocarbon measurements these forests fell victim to extensive fires that seem to have spread across the basin this fact is supported by the characteristic macro and microstructure of the charred remains using sem identification and thermoanalytical examination the firing temperature was 600 700 c suggesting a natural forest fire fire scars can also be observed on the remains as well as the burnt sediment forming a silhouette the so called burning court of the fallen trunks or roots thus these fragments have remained in their in situ position

climatic cycles investigated by sediment analysis in peking man s cave zhoukoudian china abstract the cave sediments at locality 1 in zhoukoudian which are more than 40 m thick have been divided into 17 layers according to recent dating by thermal ionization mass spectrometry tims the age of the sediments has been increased by about 200 ka on the basis of cluster and factor analyses of mammal fossils and sporopollen in the cave sediments and of the vicarious paleoclimatic indexes such as the weathering index and content of trace elements the paleoclimatic cycles recorded by the cave sediments have been quantitatively established based on the age of layer 2 410 ka bp by tims and the occurrence of the brunhes matuyana palaeomagnetic boundary in the upper part of layer 14 layers 1 14 of the cave sediments may be recorrelated with stages 11 19 of the 18o curve of deep sea cores or s4 s7of the loess sequences in china the secondary climatic variations in each paleoclimatic cycle may be correlated to one another to some extent according to deep sea core chronology the upper culture layer layer 4 the lower culture layer layer 8 9 and the bottom culture layer layer 10 were formed between about 470 and 670 ka bp and peking man should be at least 400 ka old