vegetation history and climate in the savanna biome south africa since 190 000 ka a comparison of pollen data from the tswaing crater the pretoria saltpan and wonderkrater abstract the long term quaternary vegetation and climate history in south africa s savanna biome since ca 190 000 yr bp is elucidated by the palynological record of lake sediments in the tswaing crater the pretoria saltpan and spring deposits from wonderkrater despite hiatuses in both sequences palaeotemperature trends from the two places are presented by means of principal components analysis pca of pollen data allowing a new regional palaeoenvironmental reconstruction correlation in the older sections of the sequences beyond radiocarbon dating is tentative suggesting that the wonderkrater sequence is roughly 4 times younger than the tswaing sequence combined temperature indications from the two sites suggest cooling at ca 14 000 yr bp and slight warming at ca 15 000 yr bp although no data are available between ca 15 000 and 21 000 and 25 000 and 31 000 yr bp generally cool conditions are suggested between ca 11 000 and 33 000 yr bp between ca 33 000 and an extrapolated age of ca 80 000 yr bp at least three warmer pulses of varying intensity occurred no data are available between ca 80 000 and 150 000 yr but between 150 000 and ca 190 000 yr bp two cool and two moderately warm phases are suggested

late quaternary climate variability and vegetation response in ziro lake basin eastern himalaya a multiproxy approach abstract pollen phytolith and stable carbon isotopic records provide new insights into the palaeoenvironmental and palaeoclimatic changes in ziro lake basin sub himalayan arunachal pradesh india since pre lgm time phytoliths record a minor change in grass woodland cover and appear to be more sensitive than pollen grains to climate fluctuations both pollen and non pollen palynomorph data suggest prevalence of a dense c3 species dominated moist semi evergreen forest in the area until the lgm which shows conformity with 13c data the phytolith assemblage indicates an alteration in forest cover with expansion of c4 grasses during the lgm the study further indicates a climatic amelioration with intensification of south west monsoon during 10 2 3 8 ka and an expansion of forest cover after 3 8 ka there was a rising trend of dryness shrinkage in forest cover and a slight increase in c4 species while c3 plants dominated ecosystem variability also points towards a hydrological transformation in the area since pre lgm time application of coexistence approach on pollen data reveals that prior to the lgm the mean annual temperature and mean annual precipitation were approximately 19 3 0 001 c and 1925 15 mm respectively between 10 2 and 3 8 ka mat was about 19 4 0 5 c while map was 1901 41 3 mm between 3 8 and 1 2 ka and onwards a slight increase in mat 0 3c was observed with further decrease in map to 1861 33 4 mm during pre and post lgm times mat was more or less similar in the ziro lake basin which increased gradually after 3 8 ka and was 1 2 c higher than today prior to the lgm map was higher than the present day by 94 mm between 10 2 and 3 8 ka by 70 mm and since 3 8 ka onwards by 30 mm showing a tendency of gradual decline suggesting a consequent increase in dryness

persistent millennial scale climatic variability over the past 25 000 years in southern africa abstract data from stalagmites in the makapansgat valley south africa document regional climatic change in southern africa in the late pleistocene and holocene a new tims u series dated stalagmite indicates speleothem growth from 24 4 to 12 7 ka and from 10 2 to 0 ka interrupted by a 2 5 ka hiatus high resolution oxygen and carbon stable isotope data suggest that postglacial warming was first initiated 17 ka was interrupted by cooling probably associated with the antarctic cold reversal and was followed by strong warming after 13 5 ka the early holocene experienced warm evaporative conditions with fewer c4 grasses cooling is evident from 6 to 2 5 ka followed by warming between 1 5 and 2 5 ka and briefly at ad 1200 maximum holocene cooling occurred at ad 1700 the new stalagmite largely confirms results from shorter holocene stalagmites reported earlier the strongest variability superimposed on more general trends has a quasi periodicity between 2 5 and 4 0 ka also present are weaker 1 0 ka and 100 year oscillations the latter probably solar induced given similarities to the antarctic records the proximate driving force producing millennial and centennial scale changes in the makapansgat record is postulated to be atmospheric circulation changes associated with change in the southern hemisphere circumpolar westerly wind vortex

past tree cover of the congo basin recovered by phytoliths and δ 13 c along soil profiles abstract the tropical moist forests tmf of the congo basin are extremely diverse in terms of structure and functional diversity previous paleoecological work suggests that these forests have experienced dramatic changes over the last millennia related to climate or humans these disturbances still influence today s repartition of forests and savannas as well as species distributions the objective of this study is to explore the sensitivity of phytolith assemblages compared to the 13 c of soil organic carbon soc to reconstruct past tree cover of the present tmf large transects across different geological substrata and forest communities were explored in total 18 soil profiles were investigated for pedogenic features and 53 radiocarbon dates from soc and charcoals were obtained phytolith extractions from modern soils and along four soil profiles were performed the 13 c of soc and phytolith assemblages were interpreted in terms of tree cover changes one of the most interesting results highlighted by this study was the strong match between phytolith tree cover and the 13 c signal as it not only aids the interpretation of 13 c soil signals but also puts into question the transport behavior of phytoliths in soil by processes that are still poorly understood the 13 c soc method has been successfully used to study major vegetation changes in africa but has never been previously constrained with another proxy of tree cover this study confirms the value of a multi proxy approach to investigate past vegetation changes in african tropical moist forests and shows that soc 13 c and phytolith signatures in soil profiles display the same dynamics and are complementary they suggest that the majority of the present forested sites never experienced a true savanna phase

late quaternary paleotemperatures derived from a speleothem from cango caves cape province south africa abstract an oxygen isotope temperature record over a large part of the past 30 000 yr has been obtained for the southern cape province of south africa by combining data on the isotopic composition of a stalagmite from a deep cave with that of a confined groundwater aquifer in the same region results show that temperatures during the last glacial maximum were on average about 6 c lower than those today with peaks up to 7 c lower a detailed analysis of the past 5000 yr suggests multiple fluctuations with generally lower temperatures 1 2 c around 4500 and 3000 yr b p the carbon isotopic composition of the stalagmite indicates significant vegetation changes between the late pleistocene and today and also during the second half of the holocene

mode of occupation of tabun cave mt carmel israel during the mousterian period a study of the sediments and phytoliths alternative modes of occupation of tabun cave during the deposition of the mousterian levels b and c have been proposed garrod bate 1937 excavations at the wady el mughara volume 1 oxford clarendon press interpreted the archaeological record of both levels as being indicative of domestic occupational activities jelinek et al 1973 palaeorient 1 151 183 proposed that the presence of articulated limb bones of dama mesopotamica in the level b sediments below the cave chimney indicated that the cave was used as a natural game trap they also noted that the white ash layers in level c extended across the whole cave and proposed that this was due to the burning of natural vegetation in the cave this study aims at clarifying the modes of occupation during these periods level b sediments closely resemble the terra rossa soil that is common in this region burning activity is inferred from charcoal fragments seen in thin sections a minor wood ash component is present based on the preponderance of phytoliths with a variable morphology as compared to those with a consistent morphology as well as phytoliths with shapes characteristic of those formed in wood and bark of local trees thus fires were produced in the cave during this period the cave may also have been used as a game trap level c is composed of multiple layers of brown black and white sediments micromorphology mineralogy and phytolith analyses all show that these layers are mixtures of terra rossa soil and ash with the latter being abundant in the white layers the phytoliths in these layers are derived almost entirely from wood and bark and not from grasses these observations are consistent with a domestic occupational mode 1999 academic press

plio pleistocene environments of bed i and lower bed ii olduvai gorge tanzania abstract the plio pleistocene sediments of olduvai gorge tanzania are well known for their records of both hominid evolution and the paleoenvironments where these early hominids lived this paper investigates the paleohabitat reconstructions of bed i and lower bed ii of olduvai and provides an analysis using bovid tribes as habitat indicators the habitat inferences based upon the bovids are compared with paleoenvironmental reconstructions from studies of the micromammals pollen profiles isotope geochemistry and geology these various habitat indicators are shown to corroborate each other closely with regard to both the kind of habitat present and the timing of inferred habitat change the general agreement on habitat types appears to present especially strong support for the paleoecological reconstructions of bed i and lower bed ii paleohabitats ranged from closed woodland or forest to a mixture of open woodland and grassland to open grassland the pattern of paleohabitats through time supports the idea of a climatic trend towards greater aridity but with intermittent shifts to more humid conditions the plio pleistocene climatic history of the olduvai basin may prove useful in understanding the evolution of east africa climates

microarchaeology of a collective burial cova des pas minorca ftir and phytolith analyses have been used to understand the exceptional preservation of the organic remains at the burial cave of cova des pas minorca and to obtain high resolution data of the plant remains present in the sediments the presence of sodium nitrate and gypsum suggests a relatively dry environment that has enabled the preservation of the organic material and contributed to the natural mummification the dry conditions also favored phytolith preservation grass inflorescence phytoliths are abundant all over the site suggesting that phytolith accumulations might have an anthropogenic origin and are related to the burial ritual

phytolith rich layers from the late bronze and iron ages at tel dor israel mode of formation and archaeological significance the presence of many phytolith rich layers in late bronze and iron age deposits at tel dor israel are indicative of specific locations where plants were concentrated detailed studies of six of these phytolith rich layers and associated sediments from tel dor show that the phytoliths were derived mainly from wild and domestic grasses the most common domestic grass was the cereal triticum aestivum bread wheat three of these layers have a microlaminated microstructure associated dung spherulites and phosphate nodules characteristics that all point to the phytolith rich layers having formed from dung in animal enclosures in two of the layers the microlaminated structure is absent while dung spherulites and phosphate nodules are present suggesting that these too originate from dung that was not deposited in an enclosure the sixth layer is microlaminated but does not contain spherulites we thus cannot suggest a parsimonious explanation of its observed properties concentrations of burnt phytoliths are present in three locations implying that dung was either burnt in situ or the ashes from burnt dung were redeposited the transformation of dung accumulations into phytolith rich layers involves a loss of organic material and hence a significant reduction in sediment volume which is clearly apparent in the stratigraphy of some of the locations examined the volume reduction can be observed in the macrostratigraphy and has important implications with regard to macrostratigraphic interpretation the presence of abundant phytolith rich layers on the tell has significant implications for the concept of urbanism during these periods 2007 elsevier ltd all rights reserved

eight glacial cycles from an antarctic ice core the antarctic vostok ice core provided compelling evidence of the nature of climate and of climate feedbacks over the past 420 000 years marine records suggest that the amplitude of climate variability was smaller before that time but such records are often poorly resolved moreover it is not possible to infer the abundance of greenhouse gases in the atmosphere from marine records here we report the recovery of a deep ice core from dome c antarctica that provides a climate record for the past 740 000 years for the four most recent glacial cycles the data agree well with the record from vostok the earlier period between 740 000 and 430 000 years ago was characterized by less pronounced warmth in interglacial periods in antarctica but a higher proportion of each cycle was spent in the warm mode the transition from glacial to interglacial conditions about 430 000 years ago termination v resembles the transition into the present interglacial period in terms of the magnitude of change in temperatures and greenhouse gases but there are significant differences in the patterns of change the interglacial stage following termination v was exceptionally long 28 000 years compared to for example the 12 000 years recorded so far in the present interglacial period given the similarities between this earlier warm period and today our results may imply that without human intervention a climate similar to the present one would extend well into the future

phytoliths pollen and microcharcoal from the baringo basin kenya reveal savanna dynamics during the plio pleistocene transition abstract as part of the hominin sites and paleolakes drilling project hspdp phytoliths pollen and microcharcoal were examined from the 228 m 3 29 to 2 56 ma baringo tugen hills barsemoi drill core btb13 a total of 652 samples were collected at 10 to 32 cm intervals corresponding to sub millennial to millennial scale temporal resolution microcharcoal was well preserved throughout the core and often peaked in abundance 5 kyr before and after insolation peaks phytolith preservation varied between excellent to total dissolution in alternating intervals throughout the core pollen was rarely preserved these combined datasets indicate that prior to 3 1 ma woody cover fluctuated between open savanna 80 cover at typically precessional 19 23 kyr periodicities during the mid piacenzian warm period mpwp 3 26 3 01 ma intervals with exceptionally high microcharcoal abundance suggest that regional turnover from wooded to open habitats was driven in part by fire after 3 1 ma low elevation woody cover likely never exceeded 40 with oscillations between mesic tall grass vs xeric short grass savanna at precessional periodicities mesic c4 tall grass panicoideae peaked in abundance during insolation maxima whereas xeric c4 short grass chloridoideae peaked during insolation minima the onset of northern hemisphere glaciation nhg at 2 75 ma coincided with the appearance of deep lake phases and increases in grass density and fire frequency spectral analysis and intervals with well preserved phytoliths indicate that precession and interhemispheric insolation gradients influenced vegetation via their effects on equatorial precipitation and fire this study fills a crucial gap in pliocene vegetation reconstructions from the east african rift valley and its associated hominin localities it also provides orbitally resolved regional vegetation data useful in paleodata model comparisons for the onset of the mpwp which is often used as an analog for future warming and nhg

late cretaceous upwelling system along the southern tethys margin israel interrelationship between productivity bottom water environments and organic matter preservation organic rich upper cretaceous sequences in israel were deposited in an extensive highly productive upwelling linked system which prevailed along the southern tethys margin and lasted for 19 m y santonian to late maastrichtian an understanding of the spatial and temporal characteristics of this system was gained through detailed paleontological and geochemical analyses of subsurface sequences in two basins in israel representing an outer shefela and an inner zin facies belt the nature of the upwelling system and its effect on the sedimentary record is related to two basic environmental parameters namely paleoproductivity intensity and oxygen levels at the bottom the assessment of these parameters and their interrelationship has been performed through the development of paleontological foraminiferal criteria which are independent of the organic matter content following the establishment of these criteria it is concluded that the productivity reached its maximum intensity during the late campanian which was also the time of most notable differentiation between the center of the upwelling system in the inner belt and the less intense conditions in the outer basin this distribution is expressed in varied lithology organic rich carbonates phosphorites and siliceous rocks at the core of upwelling and a uniform lithology organic rich carbonates at the margin of this system the uniform lithology of the maastrichtian in both basins composed of organic rich carbonates is ascribed to a gradual weakening of productivity the bottom conditions in the inner belt during the late campanian the time of maximum surface productivity were near anoxic changing to more aerated dysaerobic conditions during the early maastrichtian in the outer belt a more aerated bottom dysaerobic prevailed throughout the late campanian to late maastrichtian the elevated organic matter content in both basins reflects the overall environment of high productivity its actual variations however seem to be unrelated to changes in surface productivity and bottom oxygen levels

early pleistocene fossil wood from olduvai gorge tanzania abstract olduvai gorge is a well known east african site for early hominid and faunal remains as well as stone tools and artefacts through the efforts of a multidisciplinary research team olapp olduvai landscape and palaeoanthropology project the sedimentology tephrostratigraphy dating mapping and palaeoclimatic interpretations are being used to put the whole ecosystem into context to achieve a better understanding of hominid occupation and behaviour the palaeolake together with the alluvial fan and wetland environment have shifted and fluctuated under the influence of climatic change tectonic faulting lava flows and ashfalls numerous fossil plants have been recovered from these sediments including sedges grasses twigs pollen phytoliths and wood one sample of fossil wood has been identified as guibourtia coleosperma caesalpiniaceae a relatively uncommon tree which today grows in angola botswana namibia zambia and zimbabwe this species grows on kalahari sands but must have had a wider distribution in the past the occurrence of this tree in lowermost bed ii approximately 1 81 1 78 ma indicates that there were large trees in the close vicinity and that there were periods of wetter climate large trees would have provided some shelter or safety for the hominids from other scavengers

the early holocene palaeoenvironment of ounjougou mali phytoliths in a multiproxy context abstract the site complex ounjougou on the dogon plateau mali comprises sediments up to 100 000 years old with numerous pleistocene and holocene sequences the site ravin de la mouche 11 4 10 2 ka is of special archaeological significance because in its early holocene deposits pottery sherds have been found which are among the oldest in africa for a better understanding of the environmental conditions which might have contributed to the innovation of pottery making a multi proxy approach was applied to the sediments of ravin de la mouche including phytoliths pollen palynofacies micromorphology and charcoal the multi proxy approach also allows reconstructing the complex taphonomy of the site in our phytolith study we applied a combination of the general and the indices approaches we recorded a maximum of morphotypes and used the summarized data for a calculation of the indices d p ic and iph in comparison with modern surface samples and data from other african phytolith studies with the general approach a number of morphotypes could be detected which are useful in describing the late pleistocene and the early holocene vegetation phytoliths were extracted from the pleistocene base and the early holocene layers ha1 ha2 and ha3 the pleistocene sediment samples with an age of ca 30 40 ka bp have no grass short cell phytoliths gscp and their composition is difficult to interpret ha1 is a coarse fluvial deposit with mainly redeposited phytoliths of pleistocene origin the palaeosoil in ha2 contains phytolith assemblages developed in situ from a terrestrial plant cover the vegetation was an open tropical grassland and a gallery forest with palms and marantaceae annuals from the grass subfamilies chloridoideae and panicoideae probably with a low biomass production dominated the grassland this might explain the insignificant role of fire as indicated by the very low number of micro charcoals ha3 results from a rhythmic deposition of alluvial sediments pointing to pronounced seasonality of rainfall and discharge it contains pollen charcoal and phytolith assemblages with a similar composition as in ha2 the early holocene annual grassland on the dogon plateau probably harboured a high number of species from the grass subfamily panicoideae with edible grains we suggest that the massive expansion of useful panicoid grasses during the early holocene triggered the development of important cultural innovations mainly pottery production cooking wild cereal grains in a ceramic container would have enabled a very effective exploitation of the vast sahelo sudanian grasslands which remained to be successful until modern times

palaeoecological significance of palms at olduvai gorge tanzania based on phytolith remains abstract palms are among the most abundant diverse and economically important families of plants in tropical and subtropical regions of the world their number and diversity make them an important part of the ecosystem phytoliths are abundantly produced in palms mainly the spheroid echinate type and although their number decreases notably after their deposition in soils they remain stable for long periods of time palm phytoliths were recovered from sediments at hwkee on the eastern palaeolake margin of the olduvai basin during lowermost bed ii between tuffs if and iia 1 795 1 71 ma their abundance in trench 107 the only freshwater source recognised to date occurs in three stratigraphically consecutive layers the first one located immediately above the incision layer 40 cm above tuff if above these samples there are no palm phytoliths in the fossil record the identification of the type of palms represented will be useful for determining the landscape distribution and nature of hominin activities along the lake margin and alluvial fan of the central olduvai basin here we use morphometric analysis of spheroid echinate phytoliths from fossil and modern palms phoenix reclinata and hyphaene petersiana and their corresponding soils to determine if the differences are significant and can be confidently applied to the fossil samples fossil and modern soil samples were found to be very similar to each other but the spheroid echinates from the fossil soils were bigger than the modern soil samples either the palms from the samples were different or there is a strong bias towards preserving phytoliths from the smaller end of the range if this is the case then the implication would be that the fossil samples are the leaves and inflorescences of phoenix reclinata a wider variety of modern palms needs to be analysed

vegetation landscape at dk locality olduvai gorge tanzania abstract the olduvai gorge palaeoanthropological site in northern tanzania encompasses about two million years of earth history the sedimentary facies of palaeolake olduvai have been used to reconstruct lake transgressions and regressions up to total drying out interpreted to reflect wet dry climate cycles although multidisciplinary research has been conducted during the past decades to reconstruct the palaeoenvironments and palaeolandscapes of the gorge very few focused on the dk site located about 2 km farther east in the gorge we present here a vegetation study at dk for bed i the oldest stratum based upon the phytolith and diatom recovery of the basalt lava to tuff ib stratigraphic interval these results have been analysed in relation to the different facies in which they occur sandy diamictite sandstone sandy waxy claystone waxy claystone and sandy diatomite the phytolith results from diamictite samples indicate a similar vegetation composition during these more arid periods conversely waxy claystone and sandy waxy claystone samples show a higher diversity in the vegetation composition the diatoms were indicative of a fresh water pool environment thus the dk site would have provided plant foods for hominins such as fruits from trees and shrubs and starch rich rhizomes and tubers from sedges and reeds overall the results at dk site present a different vegetation landscape in comparison to previously published phytolith results from other olduvai stratigraphic levels and regions

climate connections between the hemisphere revealed by deep sea sediment core ice core correlations abstract correlation of southern ocean deep sea sediment core records with ice core records of polar climate delineates with unprecedented detail the relationship between high latitude climate and the ocean s thermohaline circulation over the last 80 000 years our observations suggest that while north atlantic deep water variability manifests itself clearly in southern ocean nutrient proxy records over periods as short as 500 yr this deep water variability did not promote a direct link between climate variability in the high latitudes of the two hemispheres on millennial timescales in particular the proxy records indicate that on average northern hemisphere climate fluctuations lagged those of the southern hemisphere by 1500 yr

dinoflagellate cysts paleoproductivity and upwelling systems a late cretaceous example from israel abstract diverse assemblages of dinoflagellate cysts occur in coniacian maastrichtian sedimentary sequences in israel which represent the inner shallower and outer deeper seaward belt of a late cretaceous upwelling system along the margin of the southern tethys the assemblages are composed mainly of peridinioid p and gonyaulacoid g cysts in varying concentrations it is suggested that the observed fluctuations in the numerical peridinioid gonyaulacoid p g cyst ratio reflect mainly changes in upwelling intensity and productivity in the studied area high p g values represent a higher productivity and vice versa thep g curve indicates a generally high productivity during the campanian followed by a decrease during the maastrichtian the inner part of the upwelling region is characterized by higherp g values representing a higher productivity the similarity between thep g ratio curve and the foraminiferal based paleoproductivity curve from the same sections supports the utility of thep g ratio as a reliable productivity indicator applied here for the first time to upper cretaceous sediments

glacial surface temperatures of the southeast atlantic ocean a detailed record of sea surface temperature from sediments of the cape basin in the subtropical south atlantic indicates a previously undocumented progression of marine climate change between 41 and 18 thousand years before the present ky b p during the last glacial period whereas marine records typically indicate a long term cooling into the last glacial maximum around 21 ky b p consistent with gradually increasing global ice volume the cape basin record documents an interval of substantial temperate ocean warming from 41 to 25 ky b p the pattern is similar to that expected in response to changes in insolation owing to variations in earth s tilt

mineral magnetic proxies of erosion oxidation cycles in tropical maar lake sediments lake tritrivakely madagascar paleoenvironmental implications abstract mineral magnetic measurements were performed on the upper 16 m of five piston cored sedimentary sequences from lake tritrivakely madagascar ams 14 c dating and correlation of the five magnetic susceptibility records allowed establishment of a composite sedimentary record of the last 46 kyr our data suggest that mineral magnetic changes result from changes in concentration of strongly ferrimagnetic terrigenous minerals and from preservation dissolution cycles of detrital iron oxides primarily high coercivity fe iii phases such as hematite in alternately oxic and anoxic depositional environments high coercivity iron oxide phases are restricted to stratigraphic intervals that are interpreted to represent dry periods with oxic conditions comparison with other paleoenvironmental proxies pollen total organic carbon lithology suggests that the sediments record relatively humid conditions before 22 kyr bp and relatively dry conditions during the last glacial maximum lgm and the early holocene such results contrast with the previous observations of relatively dry glacial conditions and humid mid holocene conditions in the summer rainfall area of east and se africa

climatic changes along the northwestern african continental margin over the last 30 kyrs two sediment cores were investigated to study the regional climatic variability of the nw african upwelling over the late quaternary biomarker data and sea surface temperatures ssts predicted from alkenones at 25 n and 21 n exhibited distinct features the amplitude of the last deglaciation was estimated to 4 5 c at 25 n and 2 2 5 c at 21 n at 25 n terrestrial and marine glacial inputs were higher than holocene ones as a result of a strengthening of the trade winds and intensification of oceanic production in contrast at 21 n warmer ssts and lower organic carbon and alkenone productions during the last glacial suggest a regression of the upwelling and therefore a change of wind regime low glacial n alkanols are consistent with the migration of the vegetation belt during the maximum of african aridity while their decrease towards the core top may be indicative of anthropogenic disturbances

mid latitude southern indian ocean response to northern hemisphere heinrich events abstract the lack of temporal resolution and accurate chronology of southern ocean marine cores has hampered comparison of glacial millennial scale oscillations between the southern ocean antarctic ice and other records from both hemispheres in this study glacial climate variability is investigated over the last 50 ka using a multi proxy approach a precise chrono stratigraphy was developed on the high sedimentation rate core md94 103 indian southern ocean 45 35 s 86 31 e 3560 m water depth by geomagnetic synchronization between the later core and napis75 and 14c dates high resolution time series of 18o in planktonic foraminifera globigerina bulloides and neogloboquadrina pachyderma and sea surface temperatures ssts estimated from the alkenone uk 37 index and foraminifera assemblages have been generated temporal evolution of the two temperature proxy records is notably different during the last glacial period while foraminifera data indicate a consistent cooling towards the last glacial maximum anomalous warm glacial alkenone temperatures suggest a strong advection of warm detrital alkenones by surface waters of the agulhas current superimposed to this general trend during heinrich events foraminiferal ssts point to warmer surface waters while concurrent alkenone ssts exhibit apparent coolings probably caused by enhanced local alkenone production by analogy to modern observations possible influence of enso like conditions on the subantarctic southern ocean ssts is discussed

insights on neanderthal fire use at kebara cave israel through high resolution study of prehistoric combustion features evidence from phytoliths and thin sections abstract kebara cave mount carmel israel exhibits extensive use of fire by neanderthals in the middle paleolithic phytoliths are abundant indicating that plants were common in the cave in addition micromorphological analyses of archaeological deposits furnish precise contextual background to the phytolith analysis and provide constraints on how phytolith and other micro remains can be interpreted phytolith data are coupled with micromorphological observations from undisturbed combustion features from kebara from the middle and upper paleolithic in order to maximize accuracy of interpretations different factors have been taken into account such as phytolith preservation the discrimination between anthropogenic and non anthropogenic plant deposition and the variability of plant uses the results show that dissolution is an important factor in certain areas of the cave mostly because of high ph conditions whereas in other areas of the cave secondary silica has affected the original cell morphology of the phytoliths in general wood was the main fuel used for the fires and the presence of other plant remains such as grasses or dicotyledonous leaves is in certain areas mostly related to contamination attached to the bark of the trees whereas in others it might be associated with other reasons such as tinder to help start the fires seed coats of plants from the boraginaceae family which grow around the cave entrance are abundant in certain levels and mostly related to their fall out at the cave mouth

late quaternary sea ice history in the indian sector of the southern ocean as recorded by diatom assemblages abstract a modern analog technique mat5201 31 has been applied to fossil diatom assemblages to provide down core estimates of february sea surface temperatures ssts and of sea ice duration over the past 220 000 years at 56 40 s 160 14 e at the core location sea ice progression lagged the sst drop by 1 ka at interglacial glacial transitions and sea ice retreat was almost synchronous to the sst increase at glacial interglacial terminations sea ice increased continuously during glacial periods to reach its maximum extent at the end of glacial times although ssts were almost constant during glacials this indicates that ssts are the major parameter determining the advance and retreat of sea ice at transitions but that the sea ice advance during glacial conditions may be related to positive feedbacks of the ice on albedo air temperature and meridional wind stress the strong correlation r 0 75 between sea ice duration at the core location and the vostok co2 record argues for a control of antarctic sea ice extent on atmospheric co2 concentration via the modification of the ocean to atmosphere gas balance

quantitative phytolith study of hearths from the natufian and middle palaeolithic levels of hayonim cave galilee israel abstract a study of the mineralogy and phytolith assemblages of hearths and their associated sediments in hayonim cave israel shows that wood ash is a major component of the sediments of both the natufian approximately 12 000 bp and the mousterian deposits approximately 100 to 250 000 bp interestingly phytolith analyses show that in the natufian deposits grasses are the second most abundant form of vegetation preserved whereas in the mousterian deposits leaves of dicotyledonous plants are the second most abundant form of vegetation preserved significant differences were repeatedly observed in phytolith assemblages from closely associated but different stratigraphic layers showing that vertical mixing of intact sediments is not intensive and that there was a diverse input of vegetation over relatively short time periods no consistent differences were observed in the mineralogy and the phytolith assemblages between hearths and their associated sediments both contain abundant ash components this study demonstrates that quantitative analyses of phytoliths together with mineralogical analyses can provide much information on the use of plants for fuel and other purposes by the cave occupants

late postglacial paleoenvironmental change in the northeastern mediterranean region combined palynological and molecular biomarker evidence three gravity cores collected from the ne mediterranean nemr across a transect from the northern aegean sea north skyros basin to the south cretan margin scm were investigated for pollen and terrestrial biomarkers derived from epicuticular waxes of vascular plants during the last 20 ky pollen data show diversified mixed temperate forest in the northern borderlands and enhanced mediterranean vegetation in the southern areas documenting an n s climatic trend terrestrial plant biomarkers and their diagnostic geochemical indices exhibit latitudinal patterns which are interpreted in terms of the different delivery pathways fluvial runoff vs atmospheric transport resulting from the climate conditions during different periods during the late glacial and early deglaciation periods 20 14 ka bp relatively increased humidity h index is recorded in the north aegean sea while in the south drier climate was the limiting factor for vegetation development during this interval terrestrial n alkanes showed increased accumulation rates suggesting massive transport of terrestrial organic matter through runoffs and rivers followed by weaker input after 14 ka bp after 11 ka bp a major expansion of forest cover is evidenced in the nemr accompanied by a higher h index because of the climatic amelioration the forest vegetation exhibited regionally different characteristics with cool temperate taxa being more abundant in the aegean cores while the scm record is being featured by mediterranean elements at the onset of the holocene and throughout the holocene climatic optimum the delivery of terrestrial biomarkers increased and became more significant in the aegean sites compared to the scm site within the holocene the average chain length acl of long chain n alkanes exhibits lower values in the northern aegean than in the southeastern aegean and scm indicating the predominance of warmer species southwards finally the h index records a conspicuous humidity increase between 5 4 and 4 3 ka bp in the south aegean that coincides with an increase in the terrestrial biomarker supply and the deposition of a distinct sapropel like layer smh sapropel mid holocene similar trends in t temperature and h indices are slightly delayed and attenuated in the northern aegean and are accompanied by an increase in the acl index a noticeable increase in the accumulation rates ars of terrestrial biomarkers and the hpa index values during this period are clearly recorded in all three cores indicative of enhanced terrigenous inputs of organic matter along with higher in situ preservation

geomagnetic assisted stratigraphy and sea surface temperature changes in core md94 103 southern indian ocean possible implications for north south climatic relationships around h4 abstract new records of past sea surface temperatures ssts were derived in the 30 50 kyr b p time interval from a core located at 45 s in the southern indian ocean md94 103 to investigate the climatic phasing between the southern indian ocean the greenland and the antarctic ice the magnetic signal of core md94 103 was synchronized at better than millennial accuracy in the vicinity of the laschamp geomagnetic to a reference record napis 75 already placed on the gisp2 age model coccolithophorid and diatom species abundances both point to a cooling of surface waters during h4 specific diatoms also indicate lower salinity waters during the same time interval these observations do not support the idea that the south hemisphere warmed 1 5 2 kyr before the north hemisphere nature 394 1998 739 rather alkenone derived ssts suggest that cold conditions have characterized the surface waters in the south latitudes during h4 and h5 and that temperature at evaporation sites contributed to the isotopic events a1 and a2 visible in the isotopic records of central antarctica earth planet sci lett 177 2000 219 ssts obtained from foraminifera assemblages depict somewhat different temperature patterns possibly indicative of water stratification

modern soil phytolith assemblages used as proxies for paleoscape reconstruction on the south coast of south africa south africa continues to receive substantial attention from scholars researching modern human origins the importance of this region lies in the many caves and rock shelters containing well preserved evidence of human activity cultural material complexity and a growing number of early modern human fossils dating to the middle stone age msa south africa also hosts the world s smallest floral kingdom now called the greater cape floristic region gcfr with high species richness and endemism in paleoanthropological research improving our capacity to reconstruct past climatic and environmental conditions can help us to shed light on survival strategies of hunter gatherers to do this one must use actualistic studies of modern assemblages from extant habitats to develop analogies for the past and improve paleoenvironmental reconstructions here we present a phytolith study of modern surface soil samples from different gcfr vegetation types of the south coast of south africa in this study the phytolith concentration and morphological distribution are related to the physicochemical properties of soils the environmental conditions and the characterization of the vegetation for the different study areas our results show that phytolith concentration relates mostly to vegetation types and the dominant vegetation rather than to the type of soils more abundant phytoliths from restionaceae and woody shrubby vegetation are also noted from fynbos vegetation and grass phytoliths are a recurrent component in all the vegetation types in spite of being a minor component in the modern vegetation the grass silica short cells from these plants however suggest a mix of c3 and c4 grasses in most of the vegetation types with a major presence of the rondels ascribed to c3 grasses the exceptions are riparian coastal thicket and coastal forest vegetation which are characterized by the dominance of c4 grass phytoliths

synthetic reconstructions of southern african environments during the last glacial maximum 21 18kyr and the holocene altithermal 8 6kyr abstract the pash database has been assembling palaeoclimatic data from the southern hemisphere for a number of years the southern african sector now contains more than 100 records spanning the last 200 000 years a number of these relate to the last glacial maximum and holocene altithermal which represent the two most recent extremes in global temperatures syntheses of these records have permitted the preparation of preliminary palaeoenvironmental maps for the two intervals the results provide insights into probable changes in atmospheric circulation as temperatures across the subcontinent rose by 6 7 c these changes are in agreement with a present day model which has been developed to explain short term variations in southern african climate the results presented here should assist in calibrating models developed to predict future climate change

anthropocene and early human behavior when is the baseline for anthropocene the first indications of human impact on earth closely relate to early human behavior and use of resources first agricultural societies modified the landscap

seasonal variations in the region of the agulhas retroflection studies with geosat and fram abstract in this paper seasonal variations in the agulhas retroflection region are studied by analyzing data from the radar altimeter flown on the geosat satellite and output from the fine resolution antarctic model fram the observations of mesoscale variability from geosat suggest that any seasonal variation that exists is confined to certain limited areas of the agulhas retroflection region results from fram appear to show no seasonal variability despite the fact that the model is driven by a seasonally varying wind field a by product of this study is a comparison between geosat observations and fram output this shows that apart from the issue of seasonal variations there is reasonable agreement and that such differences as do exist give insights into how the model might be improved

palaeovegetation changes recorded in palaeolake olduvai ogcp core 2a 2 09 2 12 ma naibor soit formation olduvai gorge tanzania abstract for five decades olduvai gorge has been a key site to reconstruct and understand the relationship between environmental and landscape conditions and use of affordances by early african hominin populations following the first olduvai gorge coring project ogcp during 2014 a multiproxy microbiological analysis which includes phytoliths pollen diatoms sponge spicules and chrysophyte cysts was undertaken on samples collected from various borehole cores the aim of the study is to better understand palaeoenvironmental and palaeovegetation conditions and changes through time and their relationship to hominin presence and evolution this study details the first palaeobotanical and palaeoenvironmental study of borehole 2a at olduvai gorge it represents the as yet oldest known sedimentary sequence in the olduvai basin for a portion of the pre bed i naibor soit formation this is a unit that is not accessible in any natural exposures in olduvai gorge and has only recently been encountered by drilling here we present the results from a particularly phytolith prone portion between 2 09 ma and 2 12 ma phytolith results indicate a savannah environment dominated by grasses where poaceae were a key component and where the c3 pooideae grasses were mostly dominant alternating with c4 grasses oscillations between grass subfamilies c3 pooideae c4 chloridoideae and c4 panicoideae to lesser degrees indicate five substantial climatic shifts varying between more humid and arid conditions associated with phytoliths freshwater indicators such as diatoms sponge spicules and chrysophyte cysts were also identified suggesting the presence of wetlands in the lake catchment area pollen is extremely rare in the sediments but when present comprises fungal spores and poaceae pollen thus supporting the wetland and grassland reconstructions respectively these results offer for the first time a whole picture of the palaeovegetation and associated palaeoenvironments for this pre bed i period together with previous results from other areas and chronological periods they improve our understanding of the evolution and adaptation of early hominins and their close relationship to the surrounding landscape

isotopic constraints on the source of argentinian loess with implications for atmospheric circulation and the provenance of antarctic dust during recent glacial maxima we present rare earth element ree and sr nd isotopic data for argentinian loess 28 38 s with two aims 1 to examine the source regions of argentinian loess and the constraints that these put on palaeo wind directions 2 to further investigate the source of antarctic ice core dust and to test the hypothesis that some of it could be derived from a region to the north of patagonia into which the dry dusty westerly dominated patagonian climate expanded during quaternary glacial maxima sr nd isotopic data for argentinian loess from north of 37 s are distinct from patagonian loess compositions in that they have more radiogenic sr 87sr 86sr 0 7059 0 7123 and less radiogenic nd nd 0 8 to 6 4 ree patterns and sr nd isotopic values are relatively homogeneous for multiple samples taken from single loess sections but show significant differences between sections in general there is a northward change from patagonia like ree patterns and isotopic values away from volcanogenic signatures and towards those that are more like the continental crust the latitudinal nd isotopic pattern is remarkably similar to that for andean volcanic rocks and suggests derivation of loess from the andes by more or less direct westerly transport for loess sections in the north the data imply a contribution from palaeozoic gneisses to the northwest in the chilean altiplano sr nd data for extra patagonian argentinian loess north of 37 s do not support a significant role for this source region in supplying dust to antarctica at the last glacial maximum this conclusion contrasts with previous studies that suggest a significant northward shift in the climatic belts and in particular the westerlies and the antarctic polar front during quaternary glacial maxima very systematic relations between the sr nd isotopic composition of loess and their andean source highlights shifts in the sr isotopic composition of loess to more radiogenic values and strongly suggests that the slight offset between patagonian loess and ice core dust identified by previous workers is due to grain size differentiation effects

an isotopic study of paleosol carbonates from olduvai gorge the isotopic composition of paleosol carbonates from olduvai gorge can be used to give estimates of the paleoclimatic history of east africa during the plio pleistocene oxygen isotopes are indicative of major changes in the isotopic composition of meteoric water while carbon isotopes are indicative of major changes in the fraction of biomass using the hatch slack c4 photosynthetic pathway three major periods of climatic change in this terrestrial setting occurred at about 1 67 1 3 and 0 6 myr these involved major changes in flora as well as major changes in the isotopic composition of meteoric water overall the climate has become warmer and more arid over the past 2 2 myr

antarctic dome c ice core dust at 18 k y b p isotopic constraints on origins we have determined the source area from which dusts from the last glacial maximum lgm section of the dome c ice core were derived by comparing their strontium and neodymium isotopic ratios with those of samples from potential source areas the87sr 86sr and143nd 144nd isotope ratios of the dusts deposited 18 k y b p at the east antarctic dome c site were compared with potential antarctic australian southern african and south american sources the isotope ratios clearly define the patagonian provenance of the dust with the other potential source areas being at most minor contributors contributions by volcanic ash and tephra to the dust sample were also determined to be minimal based on the patterns of rare earth elements knowing the source of the dusts places constraints on the aeolian trajectory by which it was transported to antarctica and this serves as a test of the simulation of southern hemispheric circulation by atmospheric global circulation models during the lgm

petrographic classification of oil shales abstract oil shales are a diverse group of rocks that contain mineral matter and organic matter the organic matter is derived from terrestrial lacustrine and marine organisms the maceral nomeclature system of the international committee for coal petrology used widely in coal petrography and petroleum source rock studies is suitable for describing the organic matter in oil shales provided the terminology for organic matter derived from algal precursors is divided into two submacerals telalginite and lamalginite macerals of the liptinite group including alginite are volumetrically important constituents of oil shales and are the major source of the shale oil that is formed during pyrolysis liptinite is easily characterized and quantified using fluorescence mode microscopy and thus the type and abundance of liptinite can be used as a basis for a petrographic classification of oil shales oil shales are grouped using the environmental of deposition as the discriminatory criterion into the three primary divisions of terrestrial lacustrine and marine oil shales type and abundance of liptinite is then used to subdivide these three groups into cannel coal torbanite lamosite further subdivided into rundle type lamosite and green river type lamosite marinite tasmanite and kuckersite

relationship between antarctic sea ice and southwest african climate during the late quaternary here we compare late quaternary southwest african climate records from the west coast of southern africa published winter rainfall and trade wind intensity records from a core off the coast of namibia to records of antarctic sea ice extent this comparison reveals coherent changes between antarctic sea ice extent and the southwest african winter rain region since 45 k y b p with enhanced winter rainfall and trade wind vigor during periods of increased sea ice presence we propose an oceanic and atmospheric coupling between antarctic sea ice and the winter rainfall zone of southwest africa that may lead to increased desertification in the region if global warming persists

antarctic timing of surface water changes off chile and patagonian ice sheet response marine sediments from the chilean continental margin are used to infer millennial scale changes in southeast pacific surface ocean water properties and patagonian ice sheet extent since the last glacial period our data show a clear antarctic timing of sea surface temperature changes which appear systematically linked to meridional displacements in sea ice westerly winds and the circumpolar current system proxy data for ice sheet changes show a similar pattern as oceanographic variations offshore but reveal a variable glacier response time of up to 1000 years which may explain some of the current discrepancies among terrestrial records in southern south america

taphonomy of phytoliths and macroplants in different soils from olduvai gorge tanzania and the application to plio pleistocene palaeoanthropological samples the abundance and types of phytoliths in the fossil record are taphonomically biased and do not correspond with the macroplant record to better understand the bias and improve the interpretation of samples from olduvai gorge tanzania we analysed the phytoliths from three sample sets modern grasses sedges palm and dicots in the area modern soils in the area and the fossil soils from the eastern palaeolake margin in lowermost bed ii fourier transform infrared spectrometry analyses were performed in parallel to compare the mineral composition of both modern soils and fossil soils we found that the abundance of phytoliths is greatly reduced in soil samples compared with modern plant material but the morphotypes can be reliably interpreted dicotyledonous wood bark phytoliths appear to be over represented in the soil types grass phytoliths and sedges to a lesser degree are preserved in the soils but in lower abundances resulting in these groups being under represented the macroplant fossils are fragments of grass and sedge aerial culms and dicotyledonous stems that are preserved in fluvial and lacustrine deposits it is suggested that phytoliths represent the continuous flora whereas macroplant fossils represent the more robust tissues of selected plants preserved under more catastrophic conditions a post depositional model is proposed and the palaeovegetation is reinterpreted as being richer and more complex than indicated by other fossil data

a 70 kyr sea surface temperature record off southern chile ocean drilling program site 1233 1 we present the first high resolution alkenone derived sea surface temperature sst reconstruction in the southeast pacific ocean drilling program site 1233 covering the major part of the last glacial period and the holocene the record shows a clear millennial scale pattern that is very similar to climate fluctuations observed in antarctic ice cores suggesting that the southern hemisphere high latitude climate changes extended into the midlatitudes involving simultaneous changes in air temperatures over antarctica sea ice extent extension of the antarctic circumpolar current and westerly atmospheric circulation a comparison to other midlatitude surface ocean records suggests that this antarctic millennial scale pattern was probably a hemisphere wide phenomenon in addition we performed sst gradient reconstructions over the complete latitudinal range of the pacific eastern boundary current system for different time intervals during the last 70 kyr the main results suggest an equatorward displaced subtropical gyre circulation during marine isotope stages 2 and 4

dilation of anisotropic rock salt evidence from mount sedom diapir the mechanical behavior of bedded rock salt is studied using constant strain rate biaxial tests performed on 24 bedded rock salt samples from mount sedom diapir careful measurements of elastic parameters in unload reload loops indicate that they are influenced by confining pressure but are not sensitive to anisotropy the yield stress is also influenced by confining pressure but not by anisotropy the stress strain curve therefore indicates isotropy up to the yield stress initiation of dilation marks the onset of dependence of volumetric strain on anisotropy major principal compressive stress at dilation 1 d is at maximum when compression is normal to bedding planes 0 the stress decreases with increasing values of and minimum values are measured when compression is parallel to bedding planes 90 beyond onset of dilation point the relative dilation with respect to stress difference v e 1 3 1 1 d mpa 1 increases with decreasing confining pressure and with increasing namely dilation is intensified with decreasing confining pressure and as the major principal compressive stress direction becomes parallel with bedding plane orientation current models for compression dilation boundary ignore anisotropy and therefore provide site specific solutions but fail to describe general rock salt behaviour a new empirical model for compression dilation boundary in anisotropic rock salt developed for a data set from mount sedom predicts that stress at onset of dilation decreases with decreasing confining pressure and with increasing value of the rate of change of 1 d with respect to decreases with decreasing confining pressure and the rate of change of 1 d decreases with increasing confining pressure for all values of

effect of kerogen on rock physics of immature organic rich chalks abstract we study the rock physics of organic rich chalk from the shefela basin central israel based on laboratory measurements of core material from the zoharim well this deposit is an immature source rock that includes the late cretaceous ghareb and mishash formations the studied rock is composed of three dominating phases minerals kerogen and pores we investigate how porosity and kerogen influence the physical behavior of the rock based on measurements of porosity density acoustic velocities elastic moduli tensile strength and compressive strength we find that the dynamic bulk modulus and the static young s modulus decrease with increasing kerogen content as well as with increasing porosity to describe the stiffness of the solid skeleton we use two different poroelasticity models for fluid substitution assuming material isotropy biot gassmann model and marion s bam model the obtained poroelasticity coefficients indicate a soft matrix composed of kerogen micrite mixture characterized by a low bam normalized stiffness factor w 0 2 and a high biot coefficient 0 9 these values appear to vary with changes in kerogen content grain size and degree of cementation porosity which typically decreases with depth in the studied basin does not show a clear correlation with kerogen content moreover both compressive and tensile strengths decrease linearly with increasing porosity regardless of kerogen content we use a density kerogen relationship to create a porosity depth profile by combining data from continuous cores and density well logs by comparing sonic logs with laboratory measurements of p wave velocities on fully saturated cores we are able to detect a gas zone in the shallow interval of the sequence in the studied well

patagonian origin of glacial dust deposited in east antarctica vostok and dome c during glacial stages 2 4 and 6 abstract the source area of continental dust deposited at both vostok and dome c sites east antarctica during the glacial stages stage 2 18 ka last glacial maximum stage 4 60 ka and stage 6 160 ka of the last two climatic cycles has remained constant the isotopic composition 87 sr 86 sr and 143 nd 144 nd of the ice core dust has been compared with the isotopic composition of the potential source areas antarctica new zealand southern africa australia and south america this comparison reveals the southern south american provenance of the dust for all three glacial periods as has already been shown for the lgm 1 we show that the patagonian loess and the marine shelf sediments from the argentine continental shelf which was variably emerged during glacial periods display different isotopic compositions and that the composition of the patagonian loess best matches the signature of the ice core dust the identification of the patagonian region as the source of the windblown dust deposited over east antarctica during all the latest glacial periods permits a better understanding of paleo atmospheric circulations of the last climatic cycles and a better constraint on the parametrization of dust sources for paleoatmospheric general circulation models

glacial interglacial dust and export production records from the southern indian ocean abstract we present 230th normalized dust and export production fluxes for two contrasted marine sediment cores spanning the antarctic polar front close to the kerguelen plateau in the southern indian ocean covering the last glacial cycle we report glacial lithogenic fluxes comparable to the south atlantic and higher than in the south pacific sectors of the southern ocean structural and temporal discrepancies with dust reconstructions from antarctic ice cores and the atlantic and pacific sectors of the subantarctic zone saz point towards southern africa and or the kerguelen plateau as an additional source of lithogenic material to the southern indian ocean during the last ice age in the saz export production proxies respond to iron fe fertilization with total organic carbon toc fluxes as high as those previously reported from the atlantic sector of the southern ocean however the correlation between export production and dust proxies is weaker than in the other sectors and shows a muted response of export production during peak glacials we hypothesize that this muted response may be related to macronutrient co limitation imposed on phytoplankton growth possibly induced by a northward displacement of wind driven upwelling and or the polar frontal system during peak glacials the antarctic zone az record depicts the typical pattern of enhanced export production during interglacials and comparatively low productivity during glacials suggesting a decrease in the supply of macronutrients to the az surface during ice ages compared to warm periods as previously proposed however a muted response of opal fluxes during marine isotope stage mis 5e argues for a southward migration of the frontal system during warmer mis 5e possibly causing silicic acid co limitation at this site these results illustrate the important role of fe fertilization and changes in wind driven upwelling intensities in modulating the strength and efficiency of the biological carbon pump in the southern ocean but also highlight the potential role of frontal movements in explaining export production variability at sites located close to the antarctic circumpolar current acc fronts overall our new datasets provide new insights on the regional differences in dust and export production patterns that need to be considered in order to evaluate the efficiency of carbon sequestration in the different sectors of the southern ocean during ice ages

phytolith taphonomy in the middle to late holocene fluvial sediments of ounjougou mali west africa in semi arid ecosystems where lacustrine sediments are rare bio proxies preserved in fluvial deposits are needed to understand environmental changes in this study we evaluate the potential of phytoliths as a bio proxy in the yame river s deposits at ounjougou mali west africa covering the middle to late holocene 7790 4000 cal bp in soils phytolith assemblages result mainly from decomposition of local vegetation but in alluvial deposits the taphonomy of phytoliths is more complex depending on the type of transport and deposition in order to define the spatial origin of the phytolith assemblages either from local valley floor or regional vegetation catchment area we took the sedimentary characteristics of the deposits into account using a combination of general and index approaches phytoliths of 14 modern and 29 fossil samples from the yame valley were analyzed the predominant source area of represented phytoliths varies with the fluvial energy of transport channel deposits carried during periods of strong fluvial activity contain higher numbers of savanna grass phytoliths and display a lower ratio of dicotyledon versus poaceae phytoliths d p than those deposited in the floodplain where phytoliths from the local gallery forest are more strongly represented from the 5th millennium bp onwards higher percentages of grass short cell phytoliths gscp and lower d p values point to gradual vegetation opening due to increasing aridity high amounts of burned phytoliths show regular fire incidence in the gallery forest and attest for human impact on the landscapes of ounjougou from the 7th millennium bp onwards after 4500 cal bp there is evidence for pearl millet cultivation

phytoliths infer locally dense and heterogeneous paleovegetation at flk north and surrounding localities during upper bed i time olduvai gorge tanzania the phytolith content of 10 samples collected immediately under tuff if similar to 1 785 ma at flk n and other surrounding localities similar to 2 km 2 provides a direct botanical evidence for woody vegetation in the eastern margin of olduvai gorge during uppermost bed i time observation and counting of 143 phytolith types 5 to 150 mu reveal dense but heterogeneous woody cover similar to 40 90 of unidentified trees and or shrubs and palms associated to the freshwater springs surrounding flk n and more open formation presumably similar to 25 70 woody cover in the southeast at localities vek hwk w and hwk e the paleovegetation is best described as groundwater palm forest woodland or bushland which current analogue may be found near lake manyara in similar hydrogeological context freshwater springs near saline alkaline lake re evaluating the published pollen data based on this analogy shows that 70 of the pollen signal at flk n may be attributed to thicket woodland acacia groundwater woodland gallery and groundwater forests while 30 is attributed to swamp herbage and grasslands micro botanical isotopic and taphonomical studies of faunal remains converge on the same conclusion that the area surrounding flk n which attracted both carnivores and hominins in the early pleistocene was densely wooded during uppermost bed i time

a 27 kyr terrestrial biomarker record in the southern indian ocean terrestrial inputs were reconstructed using high molecular weight n alkane concentrations recorded in the sub antarctic indian ocean core md94 103 45 35 s 86 31 e 3560 m to examine regional changes in the atmospheric circulation over the last 27 kyr this record was compared to the dust content of epica dome c ice and continental data from south africa e g pollen sequences and isotope records in speleothems to get a comprehensive understanding of atmospheric links between low and midlatitudes of the indian ocean terrestrial n alkanes indicate higher glacial than holocene inputs and marked glacial oscillations minimum values during the last glacial maximum lgm are consistent with colder and drier climate and presumably caused by the persistence of subtropical anticyclones over southern africa limiting the amount of rainfall and vegetation growth the otherwise higher glacial n alkanes suggest a stronger influence of the tropical rainfall in southern africa likely associated with a contraction of the polar vortex with respect to its lgm position during northern heinrich events moderate decline of n alkanes suggests reduced rainfall over southern africa possibly caused by weaker tropical easterly winds when according to stott et al 2002 the pacific ocean would have experienced super enso conditions

hydrogeology and geochemistry of low permeability oil shales case study from hashfela sub basin israel abstract low permeability rocks are of great importance given their potential role in protecting underlying aquifers from surface and buried contaminants nevertheless only limited data for these rocks is available new appraisal wells drilled into the oil shale unit osu of the mt scopus group in the hashfela sub basin central israel provided a one time opportunity for detailed study of the hydrogeology and geochemistry of this very low permeability unit methods used include slug tests electrical logs televiewer imaging porosity and permeability measurements on core samples chemical analyses of the rock column and groundwater analyses slug tests yielded primary indication to the low permeability of the osu despite its high porosity 30 40 hydraulic conductivities as low as 10 10 10 12 m s were calculated using both the hvorslev and cooper bredehoeft papadopulos decoding methods these low conductivities were confirmed by direct measurements of permeability in cores and from calculations based on the kozeny carman approach storativity was found to be 1 10 6 and specific storage 3 8 10 9 m 1 nevertheless the very limited water flow in the osu is argued to be driven gravitationally the extremely slow recovery rates as well as the independent recovery of two adjacent wells despite their initial large head difference of 214 m indicate that the natural fractures are tight and are impermeable due to the confining stress at depth laboratory measured permeability is similar or even higher than the field measured values thereby confirming that fractures and bedding planes do not form continuous flow paths the vertical permeability along the osu is highly variable implying hydraulic stratification and extremely low vertical hydraulic conductivity the high salinity of the groundwater 6300 8000 mgcl l within the osu and its chemical and isotopic compositions are explained by the limited water flow suggesting long residence time of the water prolonged water rock interaction and mixing with ancient trapped salty water the current study demonstrates that targeted and detailed research of low permeability rocks can produce reliable hydraulic parameters using slug tests and accompanying methods the data produced is of upmost importance for quantitative risk evaluations such as models for waste burial in low permeability units

the importance of atmospheric input of terrestrial organic material to deep sea sediments the concentrations of lipids were determined in atmospheric particle gas and rain samples collected from the tropical north pacific to assess lipid sources transport mechanisms and fluxes to the ocean surface four lipid compound classes aliphatic hydrocarbons fatty alcohols fatty acid esters and salts all unequivocally show a terrestrial vascular plant source these aerosol lipids originate from wind erosion of asian and american soils and direct emission from vegetation the major fluxes result from rain rather than dry deposition these fluxes are large enough to have a major potential impact on the inventory of terrestrially derived lipid material found in deep sea sediments this has been showm for n alkanes fatty alcohols fatty acids total lipids and for organic carbon by comparing atmospheric and sediment trap fluxes with sediment accumulation rates it is suggested that some biogenic terrestrial material is more protected from degradation than marine derived material

mechanical and petrophysical behavior of organic rich chalk from the judea plains israel abstract the geomechanical and petrophysical properties of the late cretaceous organic rich chalk from the shefela basin in central israel were studied using laboratory tests performed on solid cylindrical samples from core retrieved from the resource the investigated section includes two formations the ghareb and the mishash of central israel the shefela chalk is dark brown and rich in organic matter with up to 20 toc at the middle of the ghareb formation both uniaxial compressive strength and young s modulus of the chalk display stress dependency with the mean values increasing with depth the tensile strength parallel to the bedding is found to be higher by 1 7 on average for ghareb and by 2 2 on average for mishash compared to the tensile strength normal to the bedding unconfined compressive strength appears to increase with total organic carbon toc whereas the effect of toc on tensile strength and elasticity is less conclusive a linear compression dilation boundary is defined for the shefela chalk based on analysis of uniaxial and triaxial test results the porosity is high approx 37 at the ghareb formation decreasing to 32 at the mishash formation the permeability is very low ranging between 0 001 md and 1 md and exhibits strong anisotropy with a vertical to horizontal ratio of 0 2 the porosity and permeability are found to be independent of the variation in organic content confirming co precipitation of the calcite minerals and organic matter during deposition

comparing the epica and vostok dust records during the last 220 000 years stratigraphical correlation and provenance in glacial periods a new aeolian dust record from the first 2200 m of the epica dome c ice core 75 06 s 123 21 e covering about 220 000 years of climatic history is compared to the vostok 78 28 s 106 48 e ice core nature 399 1999 429 the two dust profiles are very similar and several common dust events allow to establish stratigraphical links the late quaternary period is characterized at both sites and likely overall east antarctic plateau by high dust input during glacial periods in the epica dome c ice core the dust flux rises by a factor of 25 20 and 12 in glacial stages 2 4 and 6 with respect to interglacial periods holocene and stage 5 5 the magnitude and pattern of changes are comparable in the vostok ice core in this study the geographical origin of ice core dust icd in cold periods has been investigated at both sites through 87sr 86sr versus 143nd 144nd isotopic tracers following the previous studies of grousset et al earth planet sci lett 111 1992 175 and basile et al earth planet sci lett 146 1997 573 the new data and the existing ones allow to define the isotopic fields for dust at the two antarctic sites that are almost identical and restricted into the 0 708 87sr 86sr 0 711 and 5 end 0 5 ranges this suggests a common geographical provenance for dust at vostok and dome c and for all the glacial periods of the late pleistocene to decipher the icd provenance more than 50 samples of loess and aeolian deposits sands and fluvioglacial sediments from the potential source areas psas of the southern hemisphere have been collected however the methodology has been refined with respect to former studies first the isotopic fractionation that can occur in function of grain size has been taken into account and the psa s signature has been defined in the 5 m size range within which fine grained dust reaching antarctica is found moreover a possible contribution from carbonates on the samples from psas has also been also considered south africa and australia can be excluded as dominant sources but a partial overlap arises among southern south america new zealand and the antarctic dry valleys isotopic fields these latter two documented for the first time a possible contribution from all these three sources cannot be excluded but complementary arguments suggest the dominant contribution to east antarctic dust in glacial times deriving from the southern south american region of patagonia and the pampas this study shows a first order uniformity in the dust flux and geographical provenance to the east antarctica plateau during glacial periods

phytoliths in the middle palaeolithic deposits of kebara cave mt carmel israel study of the plant materials used for fuel and other purposes abstract kebara cave israel is a well studied archaeological site it contains abundant visible hearths ash derived minerals are a major component of the mousterian sediments and are present in varying states of preservation furthermore archaeobotanic information is available from charred remains kebara cave is thus an ideal location to study the potential of phytoliths to provide information on the mode of fire use in the cave to assess the input of other plant materials as well as to determine the effects of diagenesis on phytolith preservation twenty samples were analysed in terms of their mineralogy phytolith contents per unit weight of acid insoluble fraction and phytolith morphologies in general the preservation of the phytoliths is good except for the two samples in which the mineral component associated at present with the phytoliths is mainly ash derived calcite the cave sediments contain about ten times more phytoliths than those present in the four samples analysed from outside the cave the major source of plant material input into the cave is clearly from the wood and bark used for the fuel for fires the grass phytoliths present in the samples are also thought in part to have been brought into the cave associated with the wood bark fuel sediments from the hearths as well as those between the hearths contain abundant wood bark phytoliths the two samples of the latter contain appreciable amounts of phytoliths not known to be present in wood and bark as do other hearth derived samples plant materials other than those used as fuel were thus also brought into the cave this study shows that phytolith analyses in conjunction with detailed mineralogical stratigraphic archaeobotanic and field information can provide a more complete understanding of the use of plant materials in prehistoric caves for fuel

pre and post depositional alteration of botanical macro remains a case study from olduvai gorge tanzania abstract fossil macroplants from beds i and ii olduvai gorge around 1 9 1 7 ma have been used to reconstruct the past vegetation associated with the early hominids and fauna a taphonomic study of these remains together with modern analogous wetlands bushlands open woodlands and the plant taxa have been used to improve interpretation and reconstruction of the fossil flora weathering or degradation can occur at two different stages of the taphonomic cycle firstly between death and burial monocots and dicots show different weathering signatures aerial weathering of monocot culms results in removal of the epidermal layers exposing the pith and vascular bundles whereas sub aqueous weathering of the culms also shows collapse and ridging of the epidermal layers aerial weathering of dicot stems results in loss of bark and radial cracking secondly between preservation and recovery the exterior of the fossil is either worn smooth by wind or water after long exposure or can become more eroded as in the case of less durable smaller fragments fracturing of culms and stems may also occur but results in clear breaks that can be matched to the part and counterpart recognition of the weathering signatures aids in interpreting the depositional and post depositional conditions the abundance and distribution of plant macrofossils at olduvai gorge is affected by living plant abundance and depositional setting within the fault compartments

approaches to middle stone age landscape archaeology in tropical africa the southern montane forest grassland mosaic ecosystem in the humid subtropics southern rift valley of africa comprised the environmental context for a large area in which modern human evolution and dispersal occurred variable climatic conditions during the late pleistocene have ranged between humid and hyperarid changing the character of the ecosystem and transforming it at different points in time into a barrier a refuge and a corridor between southern and eastern african populations alluvial fans presently blanket the areas adjacent to major river systems which were key areas of prehistoric human habitation these sets of variables have created conditions that are both challenging and advantageous to conduct archaeological research lateritic soil development has resulted in poor organic preservation and facilitated insect bioturbation which has demanded an integrated micro macro scale approach to building a reliable geochronology an integrated field and analytical methodology has also been employed to identify the nature and degree of post depositional movement in alluvial deposits which preserve a wide range of spatial integrity levels in buried stone artifact assemblages between 47 and 30 ka in karonga northern malawi this paper describes the methodological advances taken toward understanding open air middle stone age archaeology in sub tropical africa and explores the inferential potential for understanding pleistocene human ecology in the important southern rift valley region

vegetation of northern tanzania during the plio pleistocene a synthesis of the paleobotanical evidences from laetoli olduvai and peninj hominin sites abstract more than 40 years of scientific investigations of the hominin bearing plio pleistocene sediments of northern tanzania have provided a number of paleobotanical data which taken as a whole provide today a way to investigate vegetation changes between 4 and 1 ma at a time when our early ancestors emerged here i have integrated the data from all vegetation proxies obtained for the paleontological sites of laetoli olduvai and peninj i e macroscopic plant remains pollen and phytolith assemblages carbon and oxygen isotopic ratios measured on carbonates and organic biomarkers this important yet discontinuous botanical record suggests some similarities between past and present day vegetation at the regional scale afromontane forests with olea podocarpus juniperus hagenia abyssinica in the highlands and wooded grasslands with grasses and drought adapted acacia commiphora capparidaceae and chenopodiaceae and or amaranthaceae in the lowlands were present in the southern serengeti crater highlands region since 4 ma grasses of the c 4 photosynthetic type made their first appearance in the record at 3 7 ma i e during the mid pliocene 700 ky before major p co 2 and temperature decline c 4 grasses became dominant in the vegetation soon after 3 66 ma probably in response to reduced precipitation at 2 6 ma phytolith and isotope indicate grassland with abundant c 4 xerophytic grasses that document strong aridity during the intensification of northern hemisphere glaciation period 2 7 2 5 ma after 2 ma the detailed and diverse record at olduvai indicates complex vegetation patterns linked to oscillating precipitation varying lake levels and the presence of geological faults hence despite low basin averaged reconstructed paleo precipitation amounts of 250 700 mm y c 4 grasslands closed woodlands wetlands and palm groves co occurred on short spatial scales near saline lake olduvai freshwater wetlands and palm rich woodlands occurred in highly localized areas on the lake margins where aquifer barriers and or outcrops caused by geologic faults allowed groundwater discharge botanical evidence of paleo springs at laetoli olduvai and peninj includes the marked presence of typha cattail and hyphaene palm tree in association with acacia pollen grains and at olduvai abundant forest indicator phytoliths and organic and isotopic biomarkers at olduvai freshwater wetlands were most developed when lake level and fluvial competence where low i e during dry periods when wet dry climate variability was extreme in east africa 1 9 1 7 ma freshwater springs may therefore have offered a sustainable habitat i e refuge for several species including hominins and favored hominin and artifact concentration at these specific places particularly during environmentally stressful times

fidelity of alkenone paleotemperatures in southern cape basin sediment drifts 0 in two drift cores tn057 21 and ocean drilling program site 1089 are nearly identical during the interval of overlapping analyses mis 4 5c ssts in a nearby nondrift core tn057 6 covary with those in core tn057 21 throughout mis 1 5c while climatological ssts overlying tn057 21 and tn057 6 are similar and consistent with reconstructed holocene ssts in the nondrift core surface waters overlying tn057 21 are 6 c colder than holocene alkenone ssts in the drift core temperatures remain 6 c warmer in tn057 21 relative to tn057 6 during the 100 kyr duration of the records we hypothesize that alkenone derived ssts in tn057 21 are higher than climatological ssts in the overlying surface water and those in tn057 6 as a result of the winnowing and focusing of sedimentary alkenones produced in warmer waters to the north climatological ssts in the central and northern cape basin are 16 20 c a 1 5 offset of fine fraction d 18 o values relative to planktonic foraminifera in tn057 21 supports this hypothesis temporal changes in sediment focusing were evaluated directly using uranium series radioisotopes while higher sediment focusing factors would be expected to result in higher alkenone derived ssts if sediment advection were the primary control on down core changes in alkenone derived ssts 230 th derived focusing factors indicate no such correlation exists we conclude that alkenone paleotemperature reconstructions from southern cape basin drifts reliably record regional sst variations in the cape basin index terms 4267 oceanography general paleoceanography 1055 geochemistry organic geochemistry 1040 geochemistry isotopic composition chemistry 3022 marine geology and geophysics marine sediments processes and transport keywords alkenones cape basin thorium

plio pleistocene macroplant fossil remains and phytoliths from lowermost bed ii in the eastern palaeolake margin of olduvai gorge tanzania abstract fossil macroplants and phytoliths occur in the sediments of the palaeoanthropological site of olduvai gorge northern tanzania current research on hominin land use in the basin during the plio pleistocene has a strong palaeoenvironmental emphasis on the palaeovegetation in particular the occurrence of macroplants and phytoliths at olduvai and their usefulness and reliability for palaeovegetation interpretation are assessed here for the first time modern reference collections from analogous environments have been established and used to identify the fossil taxa from the eastern palaeolake margin of lowermost bed ii as the test case for very detailed spatially and temporally constrained vegetation reconstruction fourier transform infrared spectrometry ftir analysis was used to identify the minerals of the fossil sediments modern plants produce more phytoliths than are preserved in the fossil soils but there were sufficient numbers to show diverse and changing vegetation over short time periods silicified macroplant fragments of sedge culms and dicot stems occur with phytoliths but do not always represent the same plant taxa a more complex flora was shown when using both forms of fossil plants during lowermost bed ii times at the locality of flkn monocots and dicots occurred indicating the presence of marshland and grassland after the deposition of tuff if at vek the phytoliths indicate a shift in dominance from dicots to monocots to a mixture of the two and including palms at hwkee initially palms dominated then there was a mixture of palms grasses and dicots the vegetation at mck comprised dicots monocots sedges and grasses this detailed vegetation data complements the more broad scale vegetation interpretations that have been deduced from the pollen isotopes and faunal data sets