time scales of sedimentary transfer and weathering processes from u series nuclides clues from the himalayan rivers abstract in order to define time scales of erosion and sedimentary transfer in the himalaya 238 u 234 u 230 th disequilibria have been analysed in river bank sediments and in bedloads collected along the kali gandaki river one of the main nepalese rivers and in the ghaghara and gandak rivers two major plain tributaries of the ganges the th activity ratios and u th ratios in river sediments of the two ganges tributaries constantly decrease from upstream to downstream this is related to the maturation of sediments by weathering during their transfer to the plain the u series data allow to calculate a transfer time for the sediments in the alluvial gangetic plain from the chain front to the confluence with the ganges of about 100 kyr for both rivers the kali gandaki river sediment data highlight a decrease of both the th isotopic and u th ratios which is explained by a mixing between two sources with similar u th ratios but having suffered a different u th fractionation history interpretation of the u series data in the frame of this scenario gives long time scales of weathering of several 100 s kyr for the himalayan terranes the results imply that himalayan bedrocks are submitted to a long in situ stage of weathering before their erosion and transfer into the rivers in addition occurrence of similar u sr signatures in dissolved i e

u series dating of fossil teeth and carbonates from snake cave thailand abstract snake cave thailand is an important site for the study of the evolution in southeast asia leading to a discovery of rich and various faunas including a human tooth fossils of large and small mammals converge to indicate on the basis of faunal assemblage a late middle pleistocene age for the fossiliferous layers on the other hand previous u series dating of carbonates furnished a lower limit for the fossils of about 130 ky in order to achieve a better comprehension of the chronology of the cave the uranium series method for absolute age determination has been applied to some carbonates older than those studied previously and to fossils themselves we used the isochron technique approach to yield valuable ages because spleleothem samples consist in a mixture of calcite and detrital contamination the results obtained suggest that the main fossiliferous level is older than about 160 ky the application of the u series method to tooth samples from this tropical cave leads to erroneous ages probably because of post depositional groundwater movements

quaternary sediments in the dien bien phu fault zone nw vietnam a record of young tectonic processes in the light of osl sar dating results abstract the dien bien phu fault zone dbp orientated nne to n is one of the most seismically active zones in indochina in nw vietnam this zone is 160 km long and 6 10 km wide cutting sedimentary and metamorphic rocks of the late proterozoic palaeozoic and mesozoic age as well as palaeozoic and late triassic granitoids along the dbp relatively small narrow pull apart basins occur the three largest of which chan nua lai chau and dien bien phu have been studied in detail all of them are bounded by sinistral and sinistral normal faults responsible for offset and deflected drainage presence of numerous shutter ridges and displaced terraces and alluvial fans the normal component of motion is testified to by well preserved triangular facets on fault scarps highly elevated straths in river watergaps overhanging tributary valleys as well as high and uneven river bed gradients our observations indicate a minimum recent sinistral offset ranging from 6 8 to 150 m for holocene valleys to 1 2 9 75 km for middle late pleistocene valleys in different fault segments the thickness of quaternary sediments varies from 5 25 m in the lai chau area to some 130 m in the dien bien phu basin in the lai chau basin the middle terrace 23 m alluvia of nam na river at muong te bridge have been optically stimulated luminescence single aliquot regenerative dose technique osl sar dated at 23 40 to 13 ka these sediments were normal faulted by some 11 m after 13 ka and mantled by vari coloured slope loams 8 12 m thick containing colluvial wedges composed of angular debris these wedges were probably formed due to at least three palaeoseismic events postdating 6 ka in the dien bien phu basin in turn alluvium of the upper holocene terraces has been osl sar dated to 6 5 7 and 1 7 1 0 ka whereas the younger sub recent terrace sediments give ages of 0 5 0 2 ka displaced terraces and alluvial fans allow us to suppose that the sinistral and sinistral normal faults bounding narrow pull apart basins in the southern portion of the dbp fault reveal minimum rates of left lateral strike slip ranging from 0 6 to 2 mm year in holocene and 0 5 3 8 mm year in pleistocene times whereas rates of holocene uplift tend to attain 1 mm year north of lai chau and 0 4 0 6 mm year west of dien bien phu more precise estimations however are difficult to obtain due to poor age control of the displaced drainage rates of quaternary strike slip are comparable with those of the red river fault the sense of movement being however opposite taking into account the presence of two phases of late cenozoic strike slip of contrasting sense of motion as well as the geometry of the two fault zones we hypothesize that the red river and dien bien phu faults are conjugate faults capable of generating relatively strong earthquakes in the future

oxygen isotopes and sea level from the time that detailed oxygen isotope records derived from foraminifera living in the constant temperature environment of the abyssal ocean became available there has been a discrepancy between the ice volume record that these records imply and that derived from the altitude of dated coral terraces around the world here we re examine the data and conclude that the temperature of the abyssal ocean has been an actively varying component of the climate system

long term behaviour of continental hydrothermal systems u series study of hydrothermal carbonates from the french massif central allier valley abstract u series dating of hydrothermal carbonates deposited by co2 rich thermo mineral waters of the french massif central provides new insights on the long term behaviour of a continental hydrothermal system dating of aragonite veins and travertines impregnating old terrace levels of the allier river allowed identification of the main episodes of surface deposition and thus factors likely to influence these circulations fifteen layers from three veins and four travertines from two separate areas were analysed sr isotope compositions were also measured on vein samples the results show that this region was subjected to at least 3 main episodes of surface or near surface hydrothermal deposition 253 to 208 ky 135 to 100 ky and less than 8 ky comparison of these ages with a global climatic curve indicates that preferential deposition of carbonates occurs during warm periods suggesting a strong influence of climatic conditions on the hydrothermal system it is suggested that this climatic influence does not necessarily imply the absence of carbonate deposition during cold and dry periods but rather that carbonate precipitation might occur at depth before the geothermal fluids reach the surface in addition the isotope compositions of fluids recorded by the 87sr 86sr and 234u 238u initial ratios in the aragonite veins from coudes remained remarkably constant over 250 ky ranging from 0 71360 to 0 71371 and from 3 10 to 3 39 respectively the two samples coming from saladis show a slightly higher 234u 238u initial ratio around 3 95 the constancy of these ratios over such a long period suggests a hydrothermal system in a near steady state with respect to water rock interaction we thus propose a possible model allowing a conservative steady state despite variations in the water recharge rates in response to the climatic variations the difference between 234u 238u initial ratios measured in the coudes and saladis systems suggests the existence of two separate reservoirs and constrains their lateral extension to a few km at most

interpretation of t bar penetrometer tests at shallow embedment and in very soft soils the cylindrical t bar penetrometer was developed for profiling the undrained strength of soft soils in the centrifuge and is now a widely used offshore site investigation tool the conventional interpretation of the t bar test is to convert the measured penetration resistance to soil strength using a single bearing factor associated with steady flow of soil around the bar this paper describes a new analysis for the interpretation of t bar penetrometer tests at shallow embedment and in soft soils which is an increasingly significant consideration in the design of seabed infrastructure including pipelines the analysis captures two mechanisms that are usually neglected i soil buoyancy and ii the reduced bearing factor arising from the shallow failure mechanism mobilized prior to the full flow of soil around the bar the framework derives from theoretical considerations and is calibrated using large deformation finite element analyses the depth at which the steady deep penetration condition is reach

uranium series dating of marine and lacustrine carbonates of the possible uranium series dating schemes the most important and most widely applied to marine carbonates is 230th dating with 231pa dating playing an increasingly important role for this reason this review will focus on these two methods 230th dating also referred to as u th dating or 238u 234u 230th dating involves calculating ages from radioactive decay and ingrowth relationships among 238u 234u and 230th 232th is also typically measured as a long lived essentially stable index isotope over the time scales relevant to 230th dating at present 230th dating can in principle be used to date materials as young as 3 years and in excess of 600 000 years edwards et al 1987a 1993 edwards 1988 see stirling et al 2001 for an example of dating corals in excess of 600 000 years old 231pa dating also referred to as u pa dating involves calculating ages from the ingrowth of 231pa from its grandparent 235u at present 231pa dating can be used to date materials as young as 10 years and as old 250 000 years edwards et al 1997 230th dating covers all of the 231pa time range and more with somewhat higher precision and is therefore the method of choice if a single method is applied however the combination of 231pa and 230th dating is of great importance in assessing possible diagenetic mobilization of the pertinent nuclides and thereby the accuracy of the ages allegre 1964 ku 1968 even if the primary age exceeds the 250 000 year limit of 231pa dating the combined methods can be used to assess the degree to which the samples have remained closed over the past 250 000 years e g edwards et al 1997 thus

comparison of pore systems of clay rich and silica rich gas shales in the lower silurian longmaxi formation from the jiaoshiba area in the eastern sichuan basin china abstract the jiaoshiba area in the eastern sichuan basin hosts the largest commercial shale gas field in china with an annual production of 1 7 bcf the gases are primarily produced from the clay rich siliceous marine shales in the wufeng and longmaxi formations in this paper sixteen organic rich shale samples from a variety of lithofacies from the longmaxi formation in the jiaoshiba area were studied to evaluate the pore systems of clay rich shales by comparison with the silica rich gas shales the investigation includes the assessment of porosity and pore size distribution by means of shale bulk and skeletal density measurements low pressure n2 co2 gas adsorption and mercury intrusion the shale samples with different lithofacies have porosity values ranging from 3 25 to 5 65 and display similar fractional volumes of micropores mesopores and macropores and corresponding specific surface areas all three pore fractions contribute to the shales total pore volumes while the total specific surface areas are mainly contributed to by micropores and mesopores there is a positive correlation between pore volumes and toc contents indicating that the porosities in the shales are dominated by organic matter pores with toc content being the main parameter controlling pore development toc normalized pore volumes decrease with a further increase in the toc content from 1 6 to 4 2 this may be related to the fact that the toc rich shales are more susceptive to mechanical compaction clay mineral content appears to have little effect on the pore volume or specific surface area development in the shales shale samples with clay rich siliceous shale lithofacies display similar toc contents porosities and fractional volumes of all pore sizes and specific surface areas with those of the silica rich argillaceous and argillaceous siliceous mixed lithofacies this suggests that the marine shales with silica rich argillaceous and argillaceous siliceous mixed lithofacies from the longmaxi formation in the jiaoshiba area are capable of generating significant amount of pore spaces for shale gas storage

u th ra fractionation during weathering and river transport the potential of radioactive disequilibria as tracers and chronometers of weathering processes has been recognised since the 1960 s e g rosholt et al 1966 hansen and stout 1968 this interest results from the dual property of the nuclides of the u and th radioactive series 1 to be fractionated during water rock interactions and 2 to have radioactive periods of the same order of magnitude as the time constants of many weathering processes and chemical transfers to ground and river waters therefore the study of radioactive disequilibria in surface environments should help to bring information about the nature the intensity but also the time scale of the water rock interactions produced during weathering and related chemical transfers these different properties have justified many of the studies on u th series in weathering profiles and river waters rosholt 1982 scott 1982 and osmond and ivanovich 1992 gave a synthesis of the studies of u series in weathering and surface hydrology up to the 1980 s and the 1990 s respectively here we present the main directions taken in these domains over the last decade they were partly stimulated by the analytical developments made in the measurement of the medium half life nuclides of 238u series i e 234u 230th 226ra in the mid 1980 s namely the use of thermal ionisation mass spectrometry tims e g chen et al 1986 edwards et al 1987 cohen et al 1991 chabaux 1993 chabaux et al 1994 and more recently the use of mc icp ms turner et al 2001 robinson et al 2002 for u and th isotope analysis details of these developments are given in this volume goldstein and stirling 2003 compared to the radioactive counting methods previously used the new techniques permit 1 a reduction by one order of magnitude or more of the size of the sample required for

soil deformation measurement using particle image velocimetry piv and photogrammetry a deformation measurement system based on particle image velocimetry piv and close range photogrammetry has been developed for use in geotechnical testing in this paper the theory underlying this system is described and the performance is validated digital photography is used to capture images of planar soil deformation using piv the movement of a fine mesh of soil patches is measured to a high precision since piv operates on the image texture intrusive target markers need not be installed in the observed soil the resulting displacement vectors are converted from image space to object space using a photogrammetric transformation a series of validation experiments are reported these demonstrate that the precision accuracy and resolution of the system are an order of magnitude higher than previous image based deformation methods and are comparable to local instrumentation used in element testing this performance is achieved concurrent with an order of magnitude increase in the number of meas

u isotope ratios as tracers of groundwater inputs into surface waters example of the upper rhine hydrosystem major elements trace elements and sr and u isotopes were analyzed in the dissolved load of water samples collected in the main reservoirs of the rhine graben i e the rhine river its main tributaries and the shallow and deep ground waters in several different aquifers our results confirm that the variations of major elements trace elements especially sr and rb and sr isotope ratios of the water samples are mainly correlated to the lithological variations of the watershed the atmospheric inputs can be considered as a minor cause for the chemical variability of the surface waters in the rhine hydrosystem except for a few chemical elements in the mountain streams human activity in particular the pollution by the exploitation of the alsace potash mines mainly affects the na and cl concentrations of the rhine and the south alluvial groundwaters but remains negligible for the other water samples the specific study of the lauter stream located in the lower triassic sandstones buntsandstein sequences demonstrates the importance of groundwater influences onto the chemical composition of river waters up to 50 of the total dissolved load tds of this stream is supplied by deep waters this contribution significantly modifies the chemical composition of the stream especially the 238u 234u radioactive disequilibrium which in turn can be used as a specific tracer of deep water inputs into surface waters and could be useful to distinguish in the dissolved load of rivers surface weathering fluxes from deeper ones

centrifuge experiments on the settlement of circular foundations on clay centrifuge experiments were conducted to investigate the mechanisms governing the settlement of shallow circular foundations on clay model tests were performed on both soft and firm beds of overconsolidated kaolin clay foundation loads were applied as dead weight and also through pneumatic loading a perspex window in the centrifuge package allowed digital images to be captured of a vertical cross section during and after the application of loading soil displacements deduced by particle image velocimetry piv allow deformation mechanisms to be presented for undrained penetration creep and consol idation caused by transient flow a technique is presented for discriminating consolidation settlements from the varying rates of short and long term creep the mobilizable strength design msd method is shown to make useful predictions of the undrained penetration using an estimated stress strain behaviour of the clay with allowances made for anisotropy and rate effects subsequent creep and consolidation settlements were then determined using established correlations

modern humans in sarawak malaysian borneo during oxygen isotope stage 3 palaeoenvironmental evidence from the great cave of niah abstract during recent reinvestigations in the great cave of niah in borneo the hell trench sedimentary sequence seen by earlier excavators was re exposed early excavations here yielded the earliest anatomically modern human remains in island southeast asia calibrated radiocarbon dates pollen algal microfossils palynofacies granulometry and geochemistry of the hell trench sequence provide information about environmental and vegetational changes elements of geomorphic history and information about human activity the hell sediments were laid down episodically in an ephemeral stream or pool the pollen suggests cyclically changing vegetation with forest habitats alternating with more open environments indicating that phases with both temperatures and precipitation reduced compared with the present these events can be correlated with global climate change sequences to produce a provisional dating framework during some forest phases high counts of justicia a plant which today colonises recently burnt forest areas point to fire in the landscape this may be evidence for biomass burning by humans presumably to maintain forest edge habitats there is evidence from palynofacies for fire on the cave floor in the hell area since the area sampled is beyond the limit of plant growth this is evidence for human activity the first such evidence is during an episode with significant grassland indicators suggesting that people may have reached the site during a climatic phase characterised by relatively open habitats 50 ka thereafter people were able to maintain a relatively consistent presence at niah the human use of the hell area seems to have intensified through time probably because changes in the local hydrological regime made the area dryer and more suitable for human use

a 400 000 year record of vegetational and climatic changes from a volcanic basin leizhou peninsula southern china abstract the tianyang lake in leizhou peninsula is an enclosed crater formed during the early to middle pleistocene over 200 m of diatomaceous mud and clay were deposited in the last 400 000 years providing a continuous middle and late quaternary lacustrine sequence for paleoenvironmental studies the pollen record spans the last four glacial interglacial cycles equivalent to oxygen isotope stages ois 10 to 1 during most of the glacial phases fagaceous monsoon forest was replaced by altitudinal vegetation indicating a regional landscape transformation on the peninsula the montane forest reached down to the lowland by at least 600 m during the ois 6 and 8 in a cool and relatively wet condition with temperature estimated to be more than 4 c lower than present a further lowering of the montane forest belts by about 800 1000 m occurred in the ois 4 2 as implied by the appearance of many temperate elements during the last glacial maximum this mixed forest subsequently gave way to the poaceae grassland a savanna vegetation type favored by drier and cooler climatic conditions this drastic change implies a more significant drop in temperature and precipitation than the previous three glacial periods ois 10 8 and 6 it is thus inferred that the weakening of summer monsoon was more significant towards the end of the late pleistocene particularly during the last glacial maximum lgm

new palaeontological assemblage sedimentological and chronological data from the pleistocene ma u oi cave northern vietnam abstract this paper describes recent material gathered during the second fieldwork at ma u oi in november 2002 by a vietnamese french japanese team the ma u oi cave located in the province of hoa binh 60 km sw from hanoi northern vietnam belongs to a karstic network developed in triassic dark grey limestones the cave is filled with coarse grained breccias containing numerous fossil remains partially preserved at several loci inside the cave wall vault and ground we describe new teeth which confirm the occurrence of mammal taxa already mentioned at ma u oi bacon et al 2004 bacon a m demeter f schuster m long v t thuy n k antoine p o sen s nga h h huong n t m 2004 the pleistocene ma u oi cave northern vietnam palaeontology sedimentology and palaeoenvironments geobios 37 305 314 while others mainly microvertebrates emphasize the occurrence of new species for the pleistocene of vietnam we report here for the first time the occurrence of these microvertebrates of different groups primates rodents insectivores small reptiles and amphibians in the faunal assemblage among mammal taxa the presence of one more hominid affiliated to archaic homo is also attested by our findings u th dating carried out on 2 samples extracted from breccia speleothems confirms the biochronological estimate with fossiliferous fillings ranging from late middle pleistocene to late pleistocene

a 135 000 year record of vegetational and climatic change from the bandung area west java indonesia sedimentological and palynological analyses of sediment cores from the intramontane bandung basin west java indonesia provide a first palaeoclimatic record for the indonesian region covering continuously the last 135 000 years our data on palaeosol development indicate anomalously dry conditions for the final part of the penultimate glacial period around 135 000 yr b p and very warm and humid interglacial conditions from 126 000 to 81 000 yr b p during the transition to the last glacial period around 81 000 yr b p freshwater swamp forest of the bandung plain was replaced by an open swamp vegetation dominated by grasses and sedges indicating a change to considerably drier conditions possibly related to reduced moisture uptake by the nw monsoon as a consequence of lower sea levels at the onset of glacial conditions a strong reduction in asplenium ferns from 81 000 to 74 000 yr b p suggests that drier conditions may also have occurred in the mountains of the bandung area while increased numbers indicate that from 74 000 to 47 000 yr b p it was slightly wetter again inferred depression of montane vegetation zones and reduced fern percentages suggests distinctly cooler and possibly drier climatic conditions prevailed in the bandung area from 47 000 to approximately 20 000 yr b p for the last glacial maximum 4 7 c lower temperatures are recorded

corrigendum strength mobilization in clays and silts the range of settlements implied by the range of m 2 in the database shown in fig 10 is calculated as 2 2 to 65 1 mm at the upper end of this range there would be serviceability concerns for most structures increasing m to 3 5 reduces this range to 0 9 25 5 mm the upper end of this range roughly corresponds to an upper limit on tolerable settlements this further underlines the finding of the paper that a large mobilization factor is needed for settlement control if no knowledge of soil stress strain behaviour is considered the authors apologise to the readers of canadian geotechnical journal for these mistakes in the original paper

chemical mobilizations in laterites evidence from trace elements and 238u 234u 230th disequilibria geochemical and mineralogical investigations including measurements of major and trace elements sr isotope ratios and 238u 234u 230th activity ratios were made on an old african laterite to reconstruct its formation steps and assess recent chemical mobilization the present data support a scenario of discontinuous formation for the laterite with different bedrock weathering conditions during the formation of each unit rather than a scenario of continuous formation absolute accumulation of fe u and lanthanides in the uppermost ferruginous unit suggests an autochthonous origin of this iron cap by leaching of an older overlying profile present chemical distributions of lanthanides as well as of rb k ba and sr within the profile cannot be linked to the mineralogical distribution of both relictual primary and authigenic secondary phases complementary lanthanide patterns indicate that these elements were primarily accumulated in the uppermost ferruginous unit before further remobilization and accumulation in the underlying horizons these redistribution processes may be related to the chemical instability of the ferruginous cap the 238u 234u 230th disequilibria indicate that recent u mobilization occurs in the whole profile and that as for lanthanides there is a vertical redistribution of u from the uppermost ferruginous unit to the underlying horizons moreover these data show that both u losses and gains exist at each level of the profile a simple modeling of this double u mobilization process is proposed to interpret the 238u 234u 230th data differences in the mobilization and fractionation intensities of the u input and removal processes can account for the two evolution trends which distinguish the ferruginous unit from the underlying ones furthermore on the basis of this modeling the profile appears to be in a transient state because of recent changes in the u mobilization conditions which could correspond to major pleistocene climatic variations

the late pleistocene duoi u oi cave in northern vietnam palaeontology sedimentology taphonomy and palaeoenvironments this paper describes new fossil materials recovered at the duoi u oi site in december 2003 by a vietnamese french japanese team the duoi u oi cave is located in man duc village 25 km of hoabinh city in northern vietnam it belongs to a karstic network developed in a dark grey micritic marine limestone dated from the lower to the middle triassic the sedimentary fill produced a rich mammalian fauna essentially composed of isolated teeth of middle to large sized mammals artiodactyla perissodactyla proboscidea carnivora rodentia primates and characteristic of late pleistocene the results of the duoi u oi fieldwork are of great interest for the following reasons 1 the biochronological age of the fauna is consistent with 230 th 234 u 238 u dating from the calcitic floors 6673 ka the duoi u oi fauna is thus the oldest well dated modern fauna known for the southeast asian mainland 2 in terms of sedimentology the analysis of the formation of the fossiliferous breccia and that of the processes of deposits shows a close relation between the karstic deposits inside the cave and the deposits in the alluvial terraces the observation of three levels of alluvial terraces associated with three caves situated at 62 10 and 3 m above the present alluvial plain suggests that exokarstic and endokarstic sediments evolved together 3 in terms of palaeobiogeography duoi u oi is the continental fauna showing the strongest resemblance with the late pleistocene faunas from indonesian islands punung gunung dawung lida ajer sibrambang and djambu caves this implies that at the time of duoi u oi ca 70 ka the sundaland was mainly characterised by faunas of modern aspect 4 the analysis of major taphonomic factors that led to the mammal assemblage reveals a combination of selective agents selective role of predators and porcupines selective destruction of age classes for some species selective preservation of fossils due to the deposition processes in the karstic network which contribute to the poor representation of the diversity of the fauna no arguments show that humans present at duoi u oi might have a possible role in the taphonomic process 5 the palaeoenvironmental reconstruction based on the composition of the faunal assemblage suggests a forested area and some open habitats under warm and humid conditions

cavity expansion model for the bearing capacity and settlement of circular shallow foundations on clay the use of an ellipsoidal cavity expansion model to estimate the bearing capacity and settlement of circular shallow foundations on clay is presented the model uses an upper bound energy approach with contours of constant soil displacement taken to be ellipsoidal within a hemispherical outer boundary the elastic and plastic work done within the soil are equated to the footing work with yield being defined using the von mises yield criterion it is shown that for two different soil rigidities results are consistent with those obtained from finite element analyses available in the literature a relationship between the bearing stress on a circular shallow foundation and its normalised settlement is developed with an expression provided for the linear working range

biogeography and migration routes of large mammal faunas in south east asia during the late middle pleistocene focus on the fossil and extant faunas from thailand abstract thailand has long held a key position in south east asia because of its location at the boundary of the indochinese and sundaic provinces the major biogeographical regions of south east asia these provinces are distinct climatically floristically and faunistically the present day limit between them is located at the kra isthmus in peninsular thailand previous studies of the javanese large mammal fossil faunas and the recent study of fossil large mammal faunas from thailand strengthen the hypothesis of a continental migration route in contrast with the insular hypothesis via taiwan and the philippines during the late middle late pleistocene period thailand was even part of this migration route during the glacial periods the faunal exchanges were favored by the emersion of a huge continental shelf called sundaland south east asian continental area connected to borneo and indonesia islands by land bridges when the sea level was low no geological biogeographical or paleobiogeographical evidence supports the hypothesis of a migration route via taiwan and the philippines analysis of the extant and late middle pleistocene large mammal faunas carnivora primates proboscidea and ungulata points out the antiquity of the indochinese and sundaic provinces this idea is also supported by the fact that mainland faunas already displayed modern character whereas the javanese faunas were mainly composed of endemic forms however the occurrence of the extinct species elephas namadicus found in a malaysian site tambun indicates that the limit between the two provinces if not close to the present place was located more southward than today possibly in peninsular malaysia it is also confirmed by the presence of northern species such as ailuropoda melanoleuca baconi and crocuta crocuta ultima in late middle pleistocene sites of thailand in fact because of climatic cooling that occurred in the northern hemisphere during the pleistocene the northern faunas had to move southward to our knowledge the hypothesis of the antiquity of the south east asian provinces with a boundary south of the present day one is mentioned here for the first time previous biogeographical studies were based mainly on insular data from the philippine archipelago geological and mainly present day zoogeographical data but also from indonesia and borneo paleontological data however the recent discovery of thai large mammal faunas from late middle pleistocene allows to bridge the gap in the fossil record between the northern faunas of south east asia and the southern ones these thai faunas are characterized mainly by extant forms but some are today absent from the thai territory ailuropoda melanoleuca crocuta crocuta pongo pygmaeus sus cf barbatus rhinoceros cf unicornis cervus eldii

dated co occurrence of homo erectus and gigantopithecus from tham khuyen cave vietnam abstract tham khuyen cave lang son province northern vietnam is one of the more significant sites to yield fossil vertebrates in east asia during the mid 1960s excavation in a suite of deposits produced important hominoid dental remains of middle pleistocene age we undertake more rigorous analyses of these sediments to understand the fluvial dynamics of pleistocene cave infilling as they determine how skeletal elements accumulate within tham khuyen and other east asian sites uranium thorium series analysis of speleothems brackets the pleistocene chronology for breaching infilling and exhuming the regional paleokarst clast analysis indicates sedimentary constituents including hominoid teeth and cranial fragments accumulated from very short distances and under low fluvial energy electron spin resonance analysis of vertebrate tooth enamel and sediments shows that the main fossil bearing suite s1 s3 was deposited about 475 thousand years ago among the hominoid teeth excavated from s1 s3 some represent homo erectus and gigantopithecus blacki criteria are defined to differentiate these teeth from more numerous pongo pygmaeus elements the dated co occurrence of homo erectus and gigantopithecus blacki at tham khuyen helps to establish the long co existence of these two species throughout east asia during the early and middle pleistocene