external dose rate determinations for esr dating at bau de l aubesier provence france abstract at bau de l aubesier provence france mousterian artefacts and human teeth occur in inhomogeneous lumpy sedimentary deposits that include bone and tooth fragments due to uranium u uptake by the bones and teeth the external dose rate experienced by the teeth has changed over time such changes must be considered when calculating thermoluminescence tl ages for burnt flint artefacts or electron spin resonance esr ages for the teeth therein here we assess the external dose rates using three methods in situ tl dosimetry gives the modern dose rate whereas volumetrically averaged geochemical analysis is used to estimate time averaged dose rates that consider u uptake by u rich sedimentary components blackwell and blickstein 2000 quarternary international 68 71 329 343 in esr isochron analysis blackwell and schwarcz 1993 applied radiation and isotopes 44 243 252 multiple subsamples with variable u concentrations measure the external dose rate experienced by the tooth regardless of reworking but do depend on the uptake model assumed the methods each suggest significantly different dose rates tl dosimetry for two combustion horizons measured external dose rates at 0 143 0 012 mgray y in layer iv and 0 184 0 016 mgray y in layer h geochemical analysis when volumetrically averaged to account for the influence from different sedimentary components indicates external dose rates ranging from as low as 0 094 0 024 mgray y assuming ru for u rich sedimentary components to a maximum of 0 251 0 048 mgray y assuming eu for the u rich components isochron analyses suggest more variable dose rates ranging from a minimum of 0 009 0 040 mgray y lu in the lower layers to a high of 1 103 0 160 mgray y eu in layer h1 three isochrons indicated that the teeth had experienced u leaching or a second uptake event which would affect the accuracy of the dose rate determinations for those teeth other teeth may have experienced similar processes quaternary researchers who want reliable dates in the age ranges for esr or tl must carefully consider both the nature of the sediment especially u rich bone fragments and its geometric arrangement around the samples to be dated corresponding results using more than one analytic method may be required for a reasonable confidence level

coherence between solar activity and the east asian winter monsoon variability in the past 8000 years from yangtze river derived mud in the east china sea ams 14 c dating and grain size analysis for core pc 6 located in the middle of a mud area on the inner shelf of the east china sea ecs were used to rebuild the holocene history of the east asian winter monsoon eawm the 7 5 m core recorded the history of environmental changes during the postglacial transgression the core s mud section the upper 450 cm has been formed mainly by suspended sediment delivered from the yangtze river mouth by the ecs winter coastal current ecswcc since 7 6 kyr bp using a mathematical method called grain size vs standard deviatiow we can divide the core pc 6 s grain size distribution into two populations at about 28 mu m the fine population 28 mu m is considered to be transported by the ecswcc as suspended loads content of the fine population changes little and represents a stable sedimentary environment in accord with the present situation thus variation of mean grain size from the fine population would reflect the strength of ecswcc which is mainly controlled by the east asian winter monsoon abrupt increasing mean grain size in the mud section is inferred to be transported by sudden strengthened ecswcc which was caused by the strengthened eawm thus the high resolution mean grain size variation might serve as a proxy for reconstruction of the eawm a good correlation between sunspot change and the mean grain size of suspended fine population suggests that one of the primary controls on centennial to decadal scale changes of the eawm in the past 8 ka is the variations of sun irradiance i e the eawm will increase in intensity when the number of sunspots decreases spectral analyses of the mean grain size time series of core pc 6 show statistically significant periodicities centering on 2463 1368 128 106 100 88 91 7678 and 70 72 years the eawm and the east asian summer monsoon easm agree with each other well on these cycles and the east asian monsoon eam and the indian monsoon also share in concurrent cycles in holocene which are in accord with the changes of the sun irradiance c 2005 elsevier b v all rights reserved

clay minerals in cenozoic sediments off cape roberts mcmurdo sound antarctica reveal palaeoclimatic history abstractthe clay mineral assemblages of the ca 1600 m thick cenozoic sedimentary succession recovered at the crp 1 crp 2 2aand crp 3 drill sites off cape roberts on the mcmurdo sound shelf antarctica were analysed in order to reconstruct thepalaeoclimate and the glacial history of this part of antarctica the sequence can be subdivided into seven clay mineral unitsthat reflect the transition from humid to subpolar and polar conditions unit i 35 33 6 ma is characterised by an almostmonomineralic assemblage consisting of well crystalline authigenic smectite and therefore does not allow a palaeoclimaticreconstruction unit ii 33 6 33 1 ma has also a monomineralic clay mineral composition however the assemblage consistsof variably crystallized smectite that at least in part is of detrital origin and indicates chemical weathering under a humidclimate the main source area for the clays was in the transantarctic mountains minor amounts of illite and chlorite appear forthe first time in unit iii 33 1 31 ma and suggest subordinate physical weathering the sediments of unit iv 31 30 5 ma have strongly variable smectite and illite concentrations indicating an alternation of chemical weathering periods and physicalweathering periods unit v 30 5 24 2 ma shows a further shift towards physical weathering unit vi 24 2 18 5 ma indicates strong physical weathering under a cold climate with persistent and intense illite formation unit vii 18 5 ma topresent documents an additional input of smectite derived from the mcmurdo volcanic group in the south d 2005 elsevier b v all rights reserved

age of the mousterian industry at hayonim cave northern israel using electron spin resonance and 230th 234u methods abstract electron spin resonance esr analysis was done on teeth excavated at hayonim between 1993 and 1997 230 th 234 u analysis was done on two of these teeth and one calcite speleothem excavated in 1992 small amounts of uranium uptake into teeth provided nearly ideal conditions for esr age determinations the combined esr 230 th 234 u analyses on teeth confirmed that uranium uptake occurred according to values constrained by early eu and linear lu uptake esr model age estimates suggesting that eu and lu esr model ages on other teeth were reliable burial ages a speleothem stratigraphically above all the teeth yielded a 230 th 234 u age of 155 3 2 9 1 4 ka the eu and lu esr mean model ages for teeth in layers just below the speleothem were 177 12 and 182 15 ka respectively teeth in the lowest part of the section in the central area yielded younger ages apparently due to the increase in radioactive potassium content associated with the formation of siliceous aggregate mineral assemblages nearby these results were rejected the ages of the reliably dated portion of the section were contemporaneous with levels at tabun cave containing both tabun c type and d type lithics but they were significantly younger than the levels at tabun which contain only the d type lithics the use of infrared spectroscopy to identify mineral assemblages in close proximity to teeth were important to be able to select only those teeth not affected by changes in radioactive dose rate through time

pleistocene chemical weathering history of asian arid and semi arid regions recorded in loess deposits of china and tajikistan quaternary loess soil sequences in china and tajikistan are valuable archives of the chemical weathering history for arid and semiarid regions of asia the development of new proxies independent of grain size are vital to reconstruct the long term chemical weathering history of eolian deposits in this study we analyze major elemental and rb sr and ba concentrations of decarbonated residue from representative loess and soil units along a north south transect on the chinese loess plateau and compare these concentrations among different grain size fractions results show that most of the elemental abundances and ratios vary considerably among different grain size fractions for both loess and paleosols indicating transport driven compositional differentiation of minerals during subaerial transport however cao na2o mgo tio2 ratios show little variation among different size fractions for the loess soil transect loess soil sequences at lingtai northern china and chashmanigar southern tajikistan for the past 1 50 1 77 ma show lower cao na2o mgo tio2 ratios in soil units than in adjacent loess horizons in good agreement with greater weathering intensity in soils than in loess units the cao na2o mgo tio2 ratio of the decarbonated residue is therefore a reliable proxy for chemical weathering of loess deposits that is independent of grain size the cao na2o mgo tio2 ratios of the lingtai and chashmanigar sections display a relatively regular oscillation within a narrow range in the early pleistocene and a rapid increase in average values and in variance from 0 85 0 6 ma to the present indicating lowered chemical weathering intensity in both the dust source regions and the depositional areas this event may be causally related to the expansion of northern hemisphere ice and or the regional tectonic uplift of high mountains in asia since the mid pleistocene

geochemistry of shales from the archean 3 0 ga buhwa greenstone belt zimbabwe implications for provenance and source area weathering abstract phyllites from the archean 3 0 ga buhwa greenstone belt zimbabwe were deposited on a stable cratonic platform analyses of the phyllites generally define a single geochemical group based on major and trace element abundances the phyllites are strongly depleted in cao na2o and sr with respect to average archean upper crust by contrast k2o ba and rb are enriched several times relative to average archean upper crust reflecting basin scale k metasomatism transition metals are somewhat depleted whereas high field strength elements are typically enriched relative to average archean upper crust samples generally have fractionated lree patterns average cen smn 2 4 with small negative eu anomalies average eu eu 0 78 and generally flat hrees average gdn ybn 1 3 such geochemical characteristics suggest that the source dominantly consisted of tonalite with less common occurrences mafic volcanic rocks and granite mixing calculations which massbalance the rees and th sc suggest 70 tonalite 15 mafic volcanic rocks and 15 granite as possible proportions for the source of the phyllites a nearby early archean 3 5 ga continental nucleus preserves similar lithologies and is the probable source intense chemical weathering of the source terrane is indicated by premetasomatized chemical index of alteration values of 95 100 nearly complete depletion of cao and na2o and high al2o3 na2o ratios fine grained sediments of comparable age and presumed tectonic setting elsewhere in southern africa show similar geochemical characteristics implying that source area compositions and weathering intensities were similar these mature platformal deposits suggest a tectonically stable environment where intense chemical weathering took place at 3 0 ga across southern africa

tl dates of burnt flints from jelinek s excavations at tabun and their implications abstract a selection of 37 burnt flints from jelinek s excavations at tabun were dated by thermoluminescence the results indicate that the bottom of unit i garrod s layer c should be given an age of 171 17 ky bp transition from oxygen isotope stage 7 to 6 and that units xiii to ii layers ed to d were deposited between c 330 and 210 ky bp i e during the oxygen isotope stages 9 8 and the beginning of 7 these dates raise the possibility that a a pre wurmian neanderthal population may have settled in the levant during the oxygen isotope stage 6 and that b the transition from mugharan acheuleo yabrudian yabrudian and amudian to levallois mousterian type lithic industries occurred at the end of stage 8 more than 200 ky ago these early dates whose reliability was consistent with isochron analysis of the data are not that different from those now accepted for the development of the levallois mousterian industries in europe

esr dating of archaeologically relevant authigenic terrestrial apatite veins from tabun cave israel abstract apatite veins exposed at tabun cave were collected for an electron spin resonance esr dating feasibility study the dose response and thermal stability of the esr signals were found to be suitable for an age determination using a signal at g 2 0015 the early and linear uptake esr ages were found to be in the range of 45 75 ka since the apatite vein is known to have crystallized in situ after the formation of the host sediments the age was expected to be younger than that of the host sediments thermoluminescence dating of heated flints j archaeol sci 22 1995 495 in corresponding units establish the age of the host sedimentation to be 306 33 ka or greater the apatite veins ages were found to be at least 200 ka younger consistent with their expected younger age we emphasize that these results are not relevant to a resolution of the controversy that remains in the literature regarding the burial ages of sediments at tabun cave the significance of this dating approach is discussed in relation to diagenesis of bone and guano which is important to our understanding of cave sediment formation and to the determinations of sediment ages using other radiation exposure techniques

chemical weathering of the loess deposits in the lower changjiang valley china and paleoclimatic implications abstract loess deposits xiashu loess are widely distributed in the lower changjiang valley east china and are considered to be of eolian origin with a similar provenance to the well documented loess of north central china the xiashu loess is characterized by strong dissolution of carbonate and considerable weathering of some silicate minerals especially plagioclase chemical mobility of ca sr na mg was observed in the xiashu loess sediments whilst most transition metals are relatively enriched chemical index of variation cia and element ratios of k na and k ca record several paleoclimate events in the lower changjiang valley during the mid late quaternary corresponding with isotopic records in deep sea sediments east china might be governed by stronger summer monsoons than north central china during interglacial periods of the mid late quaternary which may somewhat obscure the record of winter monsoons during glacial periods

esr dating of the last interglacial mousterian at karain cave southern turkey abstract we have obtained esr ages on 18 teeth from archaeological levels ah16 ah27 exposed at the east profile in compartment e at karain cave this sequence exhibits a transition in lithic assemblage from a classic charentian to a karain zagros type mousterian between levels ah27 and ah25 and two calcite cemented soils at levels ah22 and ah16 which have been interpreted as climatic warm phases since we found no systematic increase in tooth ages with depth we assigned this sequence a mean early uptake eu age of 108 23 ka and mean linear uptake lu age of 121 27 ka on the basis of 37 subsamples from 16 teeth in this site the precision of individual tooth ages suffered little from the problems associated with uranium uptake however this advantage was offset due to uncertainties arising from the rather inhomogeneous nature of the enclosing strata which contained various sizes of limestone blocks with intervening sediment this led to difficulties in ascribing a precise annual gamma radiation dose to individual teeth in such a lumpy gamma radiation field considerable scattering of the individual tooth ages occurred mainly because the annual gamma dose comprised greater than 50 of the total annual dose to the individual teeth on the basis of the esr dating results we infer that deposition of the two different lithic assemblages and both the penultimate and the final climatic warm phases at karain probably occurred during oxygen isotope stage 5 we also conclude that these lithic assemblages are significantly different than contemporaneous levantine mousterian industries which occur about 700 km to the southeast

sedimentation and diagenesis of chinese loess implications for the preservation of continuous high resolution climate records chinese loess has been extensively utilized to produce continuous and high resolution climate records of the late cenozoic such work assumes uninterrupted loess deposition and limited diagenesis here closely spaced optically stimulated luminescence osl dates are used to characterize the holocene and late pleistocene sedimentation histories of three sites across a nw se transect of the chinese loess plateau the results suggest that sedimentation is episodic at subglacial interglacial time scales with rates rapidly varying within units and between sites unconformities noneolian deposition and mixing of sediments also appear to be common existing understanding of loess deposition therefore requires reexamination while previous reconstructions of rapid climate change not dated using absolute methods should be regarded with caution loess deposits may still yield detailed climate records from specific high sedimentation rate strata and evidence for rapid climate change may yet be obtainable by targeting these units through absolute dating the rapid changes in sedimentation presented here indicate the east asian monsoon has the capacity to vary on millennial scales

weathering and global denudation a negative correlation between sediment yield and weathering history as measured by the chemical alteration cia of the suspended sediment is observed for many of the world s major rivers and other regions of denudation the weathering history is a first order control on the sediment yield of such areas termed equilibrium denudation regions for other areas data scatter with either apparent increases or decreases of sediment yield for given cia values these areas are termed nonequilibrium denudation regions low sediment yields can be attributed to moderated erosion either natural or human induced and or the incorporation of unweathered glacial debris accelerated erosion resulting in high sediment yield is primarily human induced and results from cultivation and other land use each of these effects has a profound influence on global sediment discharge from the continents pre human suspended sediment discharge from the continents is estimated to be 12 6 times 10 15 g yr or about 0 6 the

use of multi proxy approaches to determine the origin and depositional processes in modern lacustrine sediments carajas plateau southeastern amazon brazil abstract geochemical and isotopic compositions of surficial sediments from a plateau lake in carajas southeastern amazon region were investigated to understand the spatial distribution of major and trace elements 13 c 15 n and c n ratio depositional processes and the origin of inorganic and organic fractions the 13 c 15 n and c n ratio indicate mainly an autochthonous source with siliceous sponge spicules and algae being the major source of organic matter in the center of the lake sector 3 while an allochthonous source mainly derived from c3 vascular forest plants dominates in the shallowest portion of the lake sector 1 consequently there was an apparent dilution of c4 plants montane savanna in the sediment water interface among major elements fe 2 o 3 is highly enriched in sector 3 which is controlled by the erosion of catchment laterites and underwater topography while al 2 o 3 and p 2 o 5 enrichment near the northern border of the lake is controlled by the weathering of mafic rocks similar spatial distribution of sio 2 with total organic carbon toc and isotopic evidence indicate that si distribution is partially controlled by organic components such as siliceous sponge spicules and algae the occurrence of most of the trace and rare earth elements ree is independent of fe 2 o 3 and toc but controlled by detrital aluminum silicates and heavy minerals indicating a lack of post depositional diagenetic control on their distribution the distribution of as and mo are possibly controlled by organic matter mineralization during early diagenesis and subsequently precipitation of fe phases the values of the chemical index of alteration cia in the sediments are very high 94 99 and similar to those of the source rocks suggesting that sediment composition is mainly controlled by mechanical weathering rather than chemical weathering geochemical indices al k ti k al ti la th ti zr zr hf hf nb la al co th ba sr and th sc together with the a cn k plot suggest that the provenance of the inorganic sediments remained relatively uniform or constant during the depositional period and that they were mainly derived from laterite crusts and subordinately from mafic soils this inference was further substantiated by the chondrite normalized ree patterns and discrimination plots geochemical indices such as u th authigenic u mo al and v cr indicate that the sediments were deposited under an oxic environment

geochemical characteristics and the provenance of sediments in the bransfield strait west antarctica abstract the bransfield basin is a quaternary marginal basin separating the south shetland islands from the antarctic peninsula we analyzed major trace and rare earth element chemistries and the nd sr and pb isotopic compositions for six piston core sediments from the western and eastern bransfield basins to determine the sediment provenance and factors controlling the composition of the sediments the bransfield sediments have chemical characteristics similar to sediments deposited in a tectonically active setting where the source rocks are predominated by igneous rocks of intermediate to mafic composition low k and high cn in the a cn k diagram low la sc low th sc and lower lree hree than average shale the low chemical alteration index of the sediments about 45 on average suggests the effect of weathering on the sediment composition was minimal the source rocks of the bransfield sediments are mostly composed of mesozoic to tertiary arc volcanic and plutonic rocks in the antarctic peninsula and the south shetland islands meanwhile contributions from other rock types in the northern antarctic peninsula region such as the trinity peninsula group or scotia metamorphic complex seem to be negligible the bransfield sediments can be divided into three distinct compositional groups group i sediments have a lower la yb and a less prominent negative eu anomaly than group ii sediments they are also characterized by negative ce anomalies group i sediments have been derived mainly from the south shetland islands whereas group ii sediments which are more widespread than group i sediments in the bransfield strait have been derived mainly from the antarctic peninsula group iii sediments which are very low in la yb with the lowest 87 sr 86 sr and the highest 143 nd 144 nd values have been derived from deception island the composition of the bransfield sediments is largely controlled by the composition of nearby source rocks the distribution of sediments is further modified by the current and topography of the basin

oligocene miocene antarctic continental weathering record and paleoclimatic implications cape roberts drilling project ross sea antarctica abstract the bulk chemistry of mudrocks in ross sea drillcores on the antarctic inner shelf is re evaluated to extract records of continental paleotemperatures and ice extent the chemical index of alteration cia of the sedimentary sequence derived from the composite of the cape roberts cores changes in accordance with pco 2 pagani m zachos j c freeman k h tipple b bohaty s 2005 marked change in atmospheric carbon dioxide concentrations during the paleogene science 309 600 603 the k 2 o na 2 o al 2 o 3 molar ratio of the mudrocks is used as a mean summer temperature proxy for continental antarctica and it shows similarities with benthic mg ca temperatures for the southern ocean billups k schrag d p 2002 paleotemperatures and ice volume of the past 27 myr revisited with paired mg ca and stable isotope measurements on benthic foraminifera paleoceanography 17 doi 10 1029 2000pa000567 the ratio is calibrated using intervals with significant pollen assemblages and the temperature proxy enables extrapolation of the paleoclimatic data over a larger portion of the drilled record the cia and k na al ratios support a persistent cooling and drying of climate through the oligocene miocene transition the results reinforce the strong coupling between east antarctic continental temperatures and ice volume with deep sea temperatures and concentrations of atmospheric carbon over long timescales

the loess record in southern tajikistan and correlation with chinese loess in the present study the chashmanigar loess soil sequence in southern tajikistan is studied this loess section has a paleomagnetic basal age of about 1 77 myr magnetic susceptibility color reflectance and grain size were systematically measured for closely spaced samples from the section paleosols consistently have a finer grain size distribution higher magnetic susceptibility redder color reflectance and lower dust sedimentation rate than loess horizons suggesting a colder drier and dustier environment during glacial periods than in interglacial periods the grain size record was tuned to variations in obliquity and precession of the earth s orbit the resulting magnetic susceptibility grain size and color reflectance time series all show well expressed astronomical periodicities during the pleistocene the mid pleistocene climate transition characterized by a shift of dominant climatic periods from 41 kyr to 100 kyr at about 1 0 0 8 myr is clearly documented in these proxy records comparison of the chashmanigar loess record with the lingtai loess section in china and the odp site 677 n 18 o record shows that during the entire pleistocene the climate cycles recorded by the central asian loess can be well correlated to the chinese loess and deep sea oxygen isotope records it is suggested that alternations of loess and soil horizons both in central asia and china could be basically forced by global ice volume variations although different wind systems have controlled the pleistocene loess transport and sedimentation in the two areas 2002 elsevier science b v all rights reserved

analysis of late palaeozoic glacial to postglacial sedimentary successions in south africa by geochemical proxies response to climate evolution and sedimentary environment abstract records of incisive climate changes during the late palaeozoic era are best documented in sedimentary basins of south africa glacial upper carboniferous early permian dwyka group and equivalents and postglacial deposits early to middle permian ecca and beaufort groups are known from the main karoo basin in south africa from the kalahari basin namibia and botswana and other late palaeozoic basins of south gondwana glacial deposits comprise diamictites and tillites followed by postglacial shales with variable organic matter contents and intercalated carbonate horizons this study covers the final glaciation phase upper pennsylvanian asselian sakmarian and the transition into the postglacial stage of the middle to late permian for sedimentary successions from the karoo and eastern kalahari basin element geochemical proxies chemical index of alteration zr ti rb k v cr and organic carbon content supported by mineralogical data record pronounced variation in sedimentary conditions these took place in the course of glacier retreat at the dwyka ecca boundary where climate and weathering processes are known to have changed the proxy signals indicate an increase in sea level and salinity and a shift in redox conditions from oxygenated to temporary anoxic euxinic conditions due to the synchronicity of these events distant sampling localities in the karoo basin can be correlated despite facies differences between the eastern kalahari and karoo basin the geochemical proxies point to a comparable climatic evolution during the postglacial phase for the early permian proxy signals indicate warm humid conditions in the karoo and kalahari basin during the middle permian increased aridity hampered chemical weathering processes as indicated by decreasing cia values results show that i proxies reflect provenance synsedimentary redox regime and late diagenetic alteration ii by combination of different independent geochemical proxies primary conditions of sedimentation and climate can be deduced iii the geochemical proxies applied are independent of local environments and iv the data reveal supra regional or even hemispherical changes in climate and sedimentary conditions thus geochemical proxies can be used as reliable markers for basin wide correlations knowledge about synchronicity on basin scale contributes to an improved understanding of sw gondwana s interaction with and influence on global climatic evolution

reevaluating the tectonic uplift of western mount carmel israel since the middle pleistocene abstract reevaluation of geological and archaeological evidence from western mount carmel constrains its maximal tectonic uplift since the middle pleistocene tabun cave presently 45 m above sea level asl revealed human occupation from about 600 ka to 90 ka before present the 25 m thick archaeological strata at tabun are composed of laminated fine sand silt and clays moreover no marine deposits were found in tabun or nearby caves since sea level in the last 600 ka reached a maximal of 5 to 10 m asl tabun cave could not have been uplifted since then by more than 35 to 40 m that is a maximal average rate of 58 to 67 mm ka

late quaternary dust flow on the chinese loess plateau abstract the dust flux of over 25 g cm2 103yr was reached in the central part of the chinese loess plateau during the last glacial maximum this is more than three times higher than during the last interglacial and early glacial time the grain size of the pleniglacial dust reached a peak shortly after 20 000 years ago and testifies to the occurrence of strong winds and frequent dust storms

the effects of thermal stress and fluid pressure on induced seismicity during stimulation to production within fractured reservoirs we use a continuum model of reservoir evolution to explore the interaction of coupled thermal hydraulic and chemical processes that influence the evolution of seismicity within a fractured reservoir from stimulation to production events occur from energy release on seeded fractures enabling moment magnitude frequency and spatial distribution to be determined with time event magnitudes vary in the range 2 to 2 with the largest event size 2 corresponding to the largest fracture size 500 m and a prescribed stress drop of 9 mpa modelled b values 0 6 0 7 also correspond to observations 0 7 0 8 for response in the cooper basin australia we track the hydrodynamic and thermal fronts to define causality in the triggering of seismicity the hydrodynamic front moves twice as fast as the thermal front and envelops the triggered seismicity at early time days to month with higher flow rates correlating with larger magnitude events for later time month to years thermal drawdown and potentially chemical influences principally trigger the seismicity but result in a reduction in both the number of events and their magnitudes

confirmation of a near 400 ka age for the yabrudian industry at tabun cave israel abstract the important lower and middle palaeolithic site of tabun has been previously dated using esr u series and tl esr ages throughout the site are substantially younger than tl dates although these methods have been shown to agree at other sites in israel and elsewhere all previous esr dates have been obtained on museum specimens using only attached sediments for dosimetry here we report the first esr and u series analyses of a tooth found in situ in an area equivalent to the lowest part of layer ed we obtain a combined esr u series age of 387 49 36ka in good agreement with a tl age of 340 33 ka for similar levels and substantially older than an esr u series age using attached or nearby sediment for dosimetry we conclude that the most likely explanation for the previous shorter esr chronology was the use of inappropriate gamma dose rates based on sediments attached to teeth

weathering rates as a function of climate results from a climosequence of the val genova trentino italian alps a soil sequence in northern italy along an elevational gradient ranging from moderate 950 m a s l to high alpine 2440 m a s l climate zones was investigated with respect to element losses ca mg k na fe al si mn and the development of clay minerals element losses were derived from mass balance calculations that are based on enrichment depletion factors using immobile element contents ti mass balance calculations indicated that extensive mineral weathering resulted in significant leaching losses of major base cations with losses up to 80 of the initial content in the parent material al particularly from upper horizons and si element denudation was greatest in subalpine forests near the timberline weathering rates decreased with both higher and lower altitudes the pattern of smectite distribution along the climosequence has strong similarities to the al si na and k losses while an inverse trend could be detected for clay minerals with a high amount of interlayered al highest smectite contents with up to 30 of the clay fraction and also highest weathering rates were found at sites in subalpine forest near the timberline higher precipitation rates and the production of chelating compounds in the soil are believed to promote the appearance of smectites weathering rates of na and k were additionally modelled as a function of precipitation and temperature the relationship between climate and element weathering is strongly nonlinear and is thought to be overshadowed by the pronounced podzolisation effect near the timberline

pervasive autocorrelation of the chemical index of alteration in sedimentary profiles and its palaeoenvironmental implications the chemical index of alteration has been used widely for reconstruction of the palaeoclimate however the mechanisms and environmental factors controlling the chemical index of alteration of sediments are not yet fully understood in this study autocorrelations of the chemical index of alteration in nine sedimentary profiles from both the land and the sea spanning different geological times are discussed the sediments of these profiles have different origins dust fluvial or ocean sediments and are from various climate situations and sedimentary environments autocorrelations of chemical index of alteration series are ubiquitously evident in all profiles it is suggested here that autocorrelations may be caused by post depositional changes such as persistent weathering and diagenesis as a result the chemical index of alteration may not reflect climatic conditions during the time of sediment deposition this study strongly recommends the confirmation of the reliability and veracity of the chemical index of alteration before it is adopted to evaluate the weathering degree of parent rocks and to reconstruct the past climate significant autocorrelations in loess profiles were specifically observed suggesting that the existing understanding of loess deposition in terms of climate conditions requires re examination and that previous reconstructions of rapid climate changes for example in centennial millennial scales should be treated with caution

locating the boundary between the pleistocene and the holocene in chinese loess using luminescence a detailed chronology has been obtained for a loess section at yuanbao situated at the northwestern edge of the chinese loess plateau the ages were obtained by the measurement of the optically stimulated luminescence osl from coarse silt sized quartz grains these ages showed that deposition at this site was continuous from 17 ka to the present but that there was a decrease in the sedimentation rate from 0 60 to 0 10 m ka at 13 489 1 15 ka and this is proposed as the location of the pleistocene holocene p h boundary a change in osl sensitivity occurs at this depth the depth and sharpness of this boundary is compared with the change obtained in low field magnetic susceptibility ms measurements on 65 samples from the section the ms changes gradually over 1 9 m and thus does not provide an easily discernible boundary the new osl based sedimentation rates are used to calculate the mass accumulation rates for the holocene and the end of the pleistocene

climatic and tectonic controls on weathering in south china and indochina peninsula clay mineralogical and geochemical investigations from the pearl red and mekong drainage basins 1 results of clay mineralogy major element geochemistry and sr and nd isotopes in 93 argillaceous samples collected from drainage basins of the pearl red and mekong rivers reveal different degrees of chemical weathering in southeast asia despite similar climate conditions across these regions the kaolinite illite ratio illite chemistry index and illite crystallinity can be used as indicators of chemical weathering intensity these mineralogical proxies combined with the k2o na2o cao molar ratio chemical index of alteration cia and weathering trends observed from major element results indicate intensive silicate weathering in the pearl river basin moderate to intensive in the mekong river basin and moderate in the red river basin although a significant modification of epsilon nd 0 values in our riverine sediments during chemical weathering and transport is unlikely sr 87 sr 86 ratios are controlled by various states of chemical weathering of high sr minerals such as plagioclase rich in na and ca with a linear decrease trend from the pearl mekong to red river basins our results suggest that it is not the warm climate with heavy monsoon precipitation but tectonics playing the most significant role in controlling weathering and erosion processes in south china and indochina peninsula strong physical erosion caused by tectonic activities and river incision along the eastern margin of the tibetan plateau and along the red river fault system is responsible for high contents of primary minerals in the lowlands of red and mekong river basins

origin weathering and geochemical composition of loess in southwestern hungary abstract loess geochemistry generally reflects paleo weathering conditions and it can be used to determine the average composition of the upper continental crust ucc in this study major and trace element concentrations were analyzed on loess samples from southwestern hungary to determine the factors influencing their chemical compositions and to propose new average loess compositions all studied loess samples had nearly uniform chemical composition suggesting similar alteration history of these deposits chemical index of alteration values 58 69 suggested a weak to moderate degree of weathering in a felsic source area typical non steady state weathering conditions were shown on the al 2 o 3 cao na 2 o k 2 o patterns indicating active tectonism of the alpine carpathian system during the pleistocene whole rock element budgets were controlled by heavy minerals derived from a felsic magmatic or reworked sedimentary provenance geochemical parameters indicated that dust particles must have been recycled and well homogenized during fluvial and eolian transport processes

decomposing biases in paleoenvironmental proxy data from pollen and micromammalian remains in caves an actualistic approach abstract multiple forms of bias must be taken into account when interpreting paleoenvironmental proxy records in terrestrial quaternary sequences this fact complicates attempts to correlate records from different types of proxy data accumulated at the same site we applied an actualistic approach to assess the correspondence between two major types of proxy data pollen and micromammalian remains in their representation of background vegetation within a cave site in mount carmel israel data on both pollen and micromammalian remains were extracted from a relatively large sample of 27 owl pellets accumulated inside the cave these pellets were compared to other pollen sources from inside as well as outside the cave including owl nest sediment and samples from moss and lichen these data were analyzed through multivariate correspondence analysis to examine associations among different pollen sources as well as between the pollen and micromammalian remains within the pellets the pooled composition of the pellets revealed close association between pellets and moss samples from inside the cave moss and lichen samples from outside the cave on the other hand showed clear over representation of pinus pollen in spite of some associations that we detected among specific pollen types and micromammalian taxa in the pellets when considering frequency data there was good correspondence among the cave sources in representation of the mediterranean quercus maquis vegetation formation extending below the cave we attribute these results in part to the relatively large sample of pellets and high taxonomic diversity these findings are also explained by the interaction between two key factors including the orientation of the cave towards the nearby quercus maquis and accumulation of both windblown pollen and pellets within the cave from this nearby source we conclude that long term pellet accumulations inside caves can contribute to inter proxy correlation when dealing with pollen and micromammalian remains from pellet sources and provide important and reliable sources of paleoenvironmental data