geothermal history estimated from the coalification of organic matter abstract an empirical relationship is used between the rank of coal and the subsidence history as well as the geothermal condition within a sedimentary column to estimate geothermal gradients at some locations in the southern part of germany most of the boreholes investigated arc located in the middle part of the upper rhinegraben a higher temperature gradient is indicated during the lower tertiary up to 78 c km than during the upper tertiary up to 49 c km the recent temperature gradients up to 77 c km are higher than those estimated for the upper tertiary the coal rank of the borehole urach 3 reflects a thermal regime which agrees with the measured temperature gradient 46 c km two boreholes in the molasse trough show a low and constant thermal regime during the tertiary 23 to 25 c km which agrees with the thermal regime at present

atlas of pollen spores and further non pollen palynomorphs recorded in the glacial interglacial late quaternary sediments of lake suigetsu central japan abstract the record of well preserved palynomorphs from sediment samples of lake suigetsu mirrors temporal changes in the flora around the lake and spatial changes in the vegetation cover of central japan during the late quaternary this study presents photographic images of 169 identifiable types of moss lycophyte and fern spores and pollen of gymnospermous and angiospermous plants from the sg06 core sediment obtained at a standard magnification of ca 750 additionally non pollen palynomorphs npps which appeared in the pollen slides are documented including remains of fungi rhizopods arthropods rotifers flatworms as well as green algae and plant tissue fragments all documented taxa are presented in taxonomical order on 66 plates including 55 plates for pollen and spores of higher plants and 11 plates for npps this study renders an overview on quality of preservation and on the range of palynomorphs found in the last glacial interglacial sediments of lake suigetsu and furthermore may serve as a handy and thorough guide for palynological investigations aiming at the reconstruction of past vegetation environmental and climate dynamics

monsoon fluctuations in two 20 000 yr b p oxygen isotope pollen records off southwest india abstract two marine pollen diagrams for sediments off the southwest coast of india provide a 20 000 yr history of the nearby continental vegetation determined by the monsoon climate within the framework of the isotopic stratigraphy two important phases of the evolution of the monsoon climate are a very arid period about 22 000 18 000 yr b p and a very humid period culminating at 11 000 yr b p the very arid period corresponds to the lowest pollen representation of mangrove vegetation which is used here as an indirect indicator of monsoonal runoff this aridity is due to a very weak southwest airflow a great reduction of summer monsoonal rainfall and reduced runoff of the western ghats rivers the extension of the monsoon over india after the last glacial maximum has been a gradual process following the northward progression of the intertropical convergene zone the very humid period corresponding to the highest pollen representation of mangrove vegetation and the heaviest summer rainfall is a climatic response to the maximum summer insolation of the northern hemisphere at 11 000 yr b p

a less humid climate since ca 3500 yr b p from marine cores off karwar western india abstract a marked change in the vegetation of the western ghats at ca 3500 yr b p has been observed from a study of two marine cores taken from the inner shelf off karwar karnataka western india at the mouth of the kalinadi river this change is indicated by a decrease in forest pollen particularly from evergreen forests and by a corresponding increase in savanna pollen as well as by a reduction in mangrove pollen at the same time the values of the stable isotope 13 c of sedimentary organic matter increased suddenly due to a higher contribution of organic matter of margine origin all these modifications were probably induced by a less humid climate the term drier can hardly be used for an area where the annual rainfall still attains 6 m in the hills above this clear limit the same trends steady but considerably weaker also resulting a reduction in the humid conditions were recorded up to ca 2200 yr b p reduction in forest vs increase in savannas decrease in the mangrove vegetation higher 13 c values from there onwards the pollen assemblages have remained uniform up to the present day it may be deduced that a climate quite similar to the present conditions was established about 2200 yr ago and still prevails the curves representing the percentages of marine microfossils dinoflagellates organic tests of foraminifera eggs of copepods show little variation at the 3500 yr b p boundary the marine assemblages were modified drastically only at about 2200 yr b p these sharp modifications are probably due to an increase in the marine influence as a result of a reduction in the fresh water supply from the kalinadi the stability in the representation of marine assemblages which has persisted from about 2200 yr b p to the present confirms the establishment of the present day climate around that date this paleoclimatic reconstruction is in conformity with the evidence for the beginning of drier conditions recorded at about the same time in the low latitudes in many parts of the world india northern arabian sea africa sahara tropical forest east african lakes australia and the carribbean

palaeolithic landscapes of europe and environs 150 000 25 000 years ago an overview abstract when considering the evolution and migrations of neandertalers and early modem human beings the harsh conditions of the last glacial maximum are often implicitly or explicitly assumed as their environmental background this perception is false the conditions of the high glacial apply to a small fraction of late pleistocene time here we review the palaeoenvironmental history of europe from 150 000 to 25 000 years ago with the aid of data from long cores of ice and marine and continental sediments the results are displayed in four sketch maps that illustrate the landscapes of an interglacial glacial cycle the maps connected by palaeoenvironmental histories show that especially between 60 000 and 25 000 years ago a critical part of the palaeolithic the glacial landscapes were for much of the time less barren than is generally assumed but numerous climate changes on a scale of several millennia are evident placing a premium on accurate dating of the co evolution of humans and landscape moreover during the glacial interval abrupt climatic changes lasting from a century to a few millennia were common their importance for landscape changes and their impact on human activity remain to be ascertained

coalification patterns of the pittsburgh coal their origin and bearing on hydrocarbon maturation abstract the coalification pattern of the pittsburgh coal as established by isoreflectance contours has an overall trend which intersect with the prevailing structural trend of the dunkard basin reflectance values increase from 0 53 in southeastern ohio to 1 57 in the maryland panhandle divergences of the reflectance contour pattern from the overall trend coincide in part with the present areas of high geothermal gradient crustal radiogenic heat or regional geothermal heating was probably the dominant heat source responsible for the coalification of the pittsburgh coal in the dunkard basin a time temperature lopatin type diagram which was constructed for the dunkard basin near wheeling west virginia delineates conditions on maturation of sediments and provides clues to the times of petroleum migration and to the possible source beds silurian strata matured during subsidence and burial prior to the orogeny the mississippian and pennsylvanian strata matured during or after the orogeny the pennsylvanian strata west of the dunkard basin as suggested by vitrinite reflectance values are apparently still immature

a 200 ka pollen and oxygen isotopic record from two sediment cores from the eastern arabian sea abstract we present here a pollen record from the northern indian ocean that goes back to 200 ka the boundary between marine isotopic stages mis 7 and 6 pollen oxygen isotopic composition and organic carbon have been examined for two sediment cores from the eastern arabian sea 15 02 n and 71 41 e 13 16 n and 71 00 e to reconstruct the long term palaeoclimate and palaeovegetation of the indian subcontinent oxygen isotope data suggest that glacial periods mis 2 4 and 6 are characterised by low precipitation because of a weak southwest monsoon and a strong northeast monsoon in contrast interglacial periods mis 1 3 and 5 are marked by high fresh water input resulting from a strong southwest monsoon during the last glacial interglacial cycle sea surface temperature and surface salinity changed as a result of variations in the evaporation precipitation e p balance throughout the core the dominant pollen types are poaceae and chenopodiaceae and or amaranthaceae 50 their dominance during glacial periods mis 2 4 and 6 suggests that the climate was cold and dry this dominance is also suggestive of salinity tolerant vegetation colonizing large areas near seashore due to lower sea level or high e p conditions during interglacial periods mis 1 3 and 5 when there was high precipitation the arid taxa were sparse whereas poaceae and piperaceae were abundant hence chenopodiaceae and or amaranthaceae and artemisia are suggestive of cold and arid semi arid climate and poaceae and piperaceae of warm and wet conditions mangrove pollen is not well represented in the cores

global warming and south indian monsoon rainfall lessons from the mid miocene precipitation over india is driven by the indian monsoon although changes in this atmospheric circulation are caused by the differential seasonal diabatic heating of asia and the indo pacific ocean it is so far unknown how global warming influences the monsoon rainfalls regionally herein we present a miocene pollen flora as the first direct proxy for monsoon over southern india during the middle miocene climate optimum to identify climatic key parameters such as mean annual temperature warmest month temperature coldest month temperature mean annual precipitation mean precipitation during the driest month mean precipitation during the wettest month and mean precipitation during the warmest month the coexistence approach is applied irrespective of a 3 4 c higher global temperature during the middle miocene climate optimum the results indicate a modern like monsoonal precipitation pattern contrasting marine proxies which point to a strong decline of indian monsoon in the himalaya at this time therefore the strength of monsoon rainfall in tropical india appears neither to be related to global warming nor to be linked with the atmospheric conditions over the tibetan plateau for the future it implies that increased global warming does not necessarily entail changes in the south indian monsoon rainfall

productivity fluctuations in the southeastern arabian sea during the last 140 ka abstract detailed analyses of multiple geochemical productivity proxies such as calcium carbonate biogenic opal biogenic ba organic carbon and total nitrogen have been carried out on a sediment core from the southeastern arabian sea to trace the palaeoproductivity fluctuations over the last 140 ka high calcium carbonate biogenic opal biogenic ba contents wt and their mass accumulation rates g cm2 ka suggest higher productivity during major interglacials than in the glacials organic carbon content

dynamics of the monsoon in the equatorial indian ocean over the last 260 000 years abstract the coccolithophorids are excellent indicators of the variations in ocean productivity as an example the relative abundance of florisphaera profunda a species which lives exclusively in the deepest part of the photic zone constitutes a reliable monitor of the depth of the nutricline as a function of climatic variability productivity in the indian ocean is closely linked with the monsoon its intensity affects the depth of the mixing zone which deepens as the wind stress increases during the monsoon season the nutricline is shallow resulting in a higher productivity the variations in composition of coccolith assemblages in well dated oceanic sediments allows to describe the dynamics of productivity and therefore the fluctuation of the monsoon intensity core md900963 was retrieved in the equatorial indian ocean east of the maldives at a water depth of 2400 m a precise chronology was established by fine tuning the high resolution 18o record with the specmap stack coccoliths were counted from samples taken at 10 cm intervals in the core providing a resolution of 2000 years for the last 260 000 years the productivity estimates made from coccolith counts show that productivity varied greatly in the maldives area during this time the variations of the coccolith productivity index match the variations of the organic carbon content in the sediment spectral analysis reveals strong precessional cycles and weak obliquity and eccentricity cycles this implies that the solar radiation has a dominant effect on the monsoon variability south of india the productivity maxima occur during even numbered 18o stages this may indicate that the productivity events are related to increase of the winter monsoon however the analysis of the phase between the palaeoproductivity and seasonal solar radiation curves calculated for the past 260 000 years suggest an alternative hypothesis the westerlies which blow in april in the maldives area there the onset of the monsoon is in advance on the arabian sea would have a major effect on productivity since the insolation curve of the end of march at 5 n is in perfect phase with the paleoproductivity record for the last 260 000 years

palaeogeothermics in the czechoslovak part of the upper silesian basin summary the coalification data vitrinite reflectance percentage r from 49 boreholes located in the czechoslovak part of the upper silesian basin were processed and the palaeotemperature gradient which prevailed during the namurian and the early westphalian was estimated very high gradients mean 95 k km are calculated at least in the western part of the basin during the namurian a at that time the ostrava formation fm was deposited with a high subsidence rate the corresponding heat flow density of 200 mw m 2 may not reflect the characteristic heat flow density of the region but may represent a subsurface value within the uppermost 2 3 km thick layer probably sustained by the convective system inside the basin the gradient during the namurian b c and westphalian a is lower mean 77k km in the karvina fm it is suggested that the decrease in the gradient coincides with changes in the basin development an intranamurian hiatus occurred at the turn of the namurian a and b the lower thermal regime which governed during the sedimentation of the karvina fm results also from the r data of the ostrava fm at the southern rim and in the karvina part of the basin mean gradient 60 65 k km i due to the relatively small thickness of the ostrava fm and or the big thickness of the karvina fm in these areas the sediments of the ostrava fm reached the maximum temperature during the deposition of the karvina fm thus the r data must reflect the lower gradient by applying palaeogradients estimated in both formations together with present mean thermal conductivities within them a heat flow density of 115 130 mw m 2 was computed this value agrees well with the heat flow of 125mw m estimated for the westphalian a in the ruhr basin by the same method

a δ 13 c record of late quaternary climate change from tropical peats in southern india stable isotope ratios of carbon in soils or lake sediments1 3 and of oxygen and hydrogen in peats4 5 have been found to reflect past moisture variations and hence to provide valuable palaeoclimate records previous applications of the technique to peat have been restricted to temperate regions largely because tropical climate variations are less pronounced making them harder to resolve here we present a 13c record spanning the past 20 kyr from peats in the nilgiri hills southern india because the site is at high altitude 2 000 m above sea level it is possible to resolve a clear climate signal we observe the key climate shifts that are already known to have occurred during the last glacial maximum 18 kyr ago and the subsequent deglaciation in addition we observe an arid phase from 6 to 3 5 kyr ago and a short wet phase about 600 years ago the latter appears to correspond to the mediaeval warm period which previously was believed to be confined to europe and north america6 7 our results therefore suggest that this event may have extended over the entire northern hemisphere

phase relationships between millennial scale events 64 000 24 000 years ago a core recovered on the iberian margin off southern portugal can be correlated with greenland ice cores using oxygen isotope variability in planktonic foraminifera which closely matches the ice core records of temperature over greenland our age model identifies the base of every interstadial between 64 000 and 24 000 years ago and uses the greenland ice core project grip timescale the oxygen isotope signal in benthic foraminifera on this grip based timescale is quite different from the planktonic record and resembles the temperature record over antarctica when this is synchronized with greenland using the record of methane in the atmospheric air in the polar ice cores we interpret the benthic record as indicating significant fluctuations in ice volume during millennial events and we suggest that antarctic temperature changed as a function of ice volume

submerged late pleistocene reefs on the tectonically stable s e florida margin high precision geochronology stratigraphy resolution of substage 5a sea level elevation and orbital forcing abstract a well preserved submerged in situ fossil reef tract lies offshore of the southeast florida carbonate margin in the florida keys cores in two transects enabled reconstruction of reef stratigraphy and paleoenvironments paleo water depths and paleo sea levels because florida is tectonically stable the elevation data required correction only for the known minor subsidence rate twenty eight pristine aragonitic corals were dated via high precision tims u series methods to produce a comprehensive late pleistocene and early holocene geochronology the pleistocene section of the fossil reef includes a thick section of substage 5a reef growth recorded from 15 to 11 m msl spanning an age range of 86 2 80 9 ka paleoenvironmental reconstruction local water quality constraints and elevations of concurrent bahamian speleothem growth combine to limit sea level to 9 0 m msl at 83 ka this coincides unlagged with the 82 ka 65 n july insolation peak the absence of any lag suggests that the earlier peak in obliquity at 92 ka also controls paleoclimate and sea level a below present sea level estimate for substage 5a from the florida fossil reef data coincides more closely with uplift corrected reef data estimates of 15 to 13 m msl from tectonic margins such as barbados and haiti than with higher than present sea levels derived from detrital corals from bermuda and the u s atlantic coastal plain the best tims dates on corals and speleothem constraining sea level combine to produce a new regional sea level curve for the atlantic caribbean region for late isotope stage 5 and early stage 4

glacial to interglacial contrasts in the northern indian ocean differences between the 18o 16o ratios of planktonic foraminifera deposited during the last glacial maximum about 18 000 yr ago and those deposited during the holocene show that in the indian ocean the south west monsoon was weaker than today but that the north east monsoon was stronger the upwelling observed in modern conditions along the southern coast of arabia had disappeared because of the low speed of the southwestern winds during glacial summers the reduction in rainfall and runoff over the continent caused a reduction of the salinity gradient in the bay of bengal and along the western coast of india increased precipitation fell on the sea south of 10 n while strong evaporation over the northernmost arabian sea produced an enhanced salinity gradient in that area

phytoliths as paleoenvironmental indicators west side middle awash valley ethiopia phytolith assemblage analysis offers the potential to refine our knowledge of paleoecosystems where grasses and sedges predominate in this work holocene and pleistocene sediments from an arid tropical region in ethiopia have been analyzed for their phytolith content presented as detailed counts and diagrams according to the twiss classification the aim is to test the usefulness of phytolith assemblages to indicate paleoenvironments at middle awash where fossil pollen grains are poorly preserved in sediments that yielded abundant archaeological remains the vegetation in the middle awash subdesertic valley is currently a shrub steppe dominated by c4 grasses adapted to arid conditions with a narrow riparian forest limited to the awash river our results show that modern surface samples holocene and pleistocene sediments contain well preserved and different phytolith assemblages and therefore that no translocation processes from modern soil to geological strata seem to occur fossil records and modern assemblages are interpreted using phytolith ratios to estimate the density of the tree cover the aridity and the proportion of c3 versus c4 grasses as applied to phytolith assemblages from north america and west africa the phytolith assemblages from modern soil samples correctly reflect the proportion of trees and shrubs versus grasses different in the riparian vegetation and the shrub steppe modern phytolith assemblages appear to be a mixed signature of local and regional vegetation phytolith analysis of the holocene sample suggests a grassland where the grass community is constituted by the chloridoideae subfamily adapted to warm and dry conditions and where c3 pooideae cover the highlands phytolith analysis of the pleistocene sample evidences grassland formation with scattered woody elements where c4 panicoideae grasses adapted to warm and humid conditions dominate the grass cover however these conclusions need to be confirmed by more complete study on phytolith assemblages from modern vegetation from ethiopia

oxygen isotope evidence for a stronger winter monsoon current during the last glaciation a variety of palaeoclimate data from the northern indian ocean has shown that the asian summer monsoon was weaker during the last glacial maximum 18 000 years ago than it is today1 5 it has also been inferred from these data that the winter monsoon was stronger at that time5 here we present evidence that the transport of low salinity water from the bay of bengal to the arabian sea caused by the winter monsoon6 was higher during the last glacial maximum this inference is based on a negative excursion up to about 1 in magnitude in the oxygen isotope ratios of three planktonic foraminiferal species detected in a sediment core from the arabian sea by high resolution 1 2 cm sampling our results place an upper limit of about 4 000 years on the length of time during which the winter monsoon was stronger than today

variations of the monsoon regime during the upper quaternary evidence from carbon isotopic record of organic matter in north indian ocean sediment cores abstract the 13 c 12 c ratios and contents of organic carbon in deep sea sediment cores of the north indian ocean have been compared for the different climatic stages as determined by oxygen isotope stratigraphy using the differences in the 13 c values between marine and terrestrial organic matter the terrestrial contribution to the eastern gulf of bengal and the andaman sea has been determined for modern and glacial times the geographical distribution of the terrestrial organic carbon linked to sea surface circulation shows that during the last glacial period the ne monsoon circulation was the dominant feature the organic carbon abundance within the sediment which is related to local productivity was greater during glacial times in the areas where production depends on the ne monsoon strength coast of north india in the arabian sea and andaman sea suggesting its reinforcement

monsoon related changes in sea surface productivity and water column denitrification in the eastern arabian sea during the last glacial cycle sea surface salinity reconstruction for the holocene and the last glacial maximum lgm suggests that the lgm eastern arabian sea was more saline by 1 5 psu than the holocene due to weakened freshwater flux to the region and intensified winter monsoons time series of sedimentary organic carbon corg p alkenone and y 13 corg for the last 100 kyr together indicate increased glacial productivity significantly reduced sedimentary y 15 n during the lgm indicates however diminished water column denitrification in spite of increased productivity the distinct decoupling of denitrification from productivity during the lgm can be explained by vigorous ventilation of the thermocline as a result of simultaneously intensified formation of high salinity water and deep winter mixing in northern arabian sea related to the extreme cold climate the closely comparable time series y 15 n records across the arabian sea suggest basin wide homogenisation of the isotopic signal this probably resulted from combined monsoon dependent surface water mixing due to changes in the relative strength of reversing surface circulations and intermediate water mixing due to changes in north south salinity gradient d 2005 elsevier b v all rights reserved

tropical rainforest dynamics and palaeoclimate implications since the late pleistocene nilgiris india a multiproxy study involving sedimentology palynology radiocarbon dating stable isotopes and geochemistry was carried out on the parsons valley lake deposit nilgiris india to determine palaeoclimatic fluctuations and their possible impact on vegetation since the late pleistocene the 72 cm deep sediment core that was retrieved reveals five distinct palaeoclimatic phases 1 warm and humid conditions with a high lake stand before the last glacial maximum lgm 29 800 cal yr bp subsequently changing to a relatively cool and dry phase during the lgm 2 considerable dry conditions and lower precipitation occurred between 16 300 and 9500 cal yr bp during this period the vegetation shrank and perhaps was confined to moister pockets or was a riparian forest cover 3 an outbreak in the shift of monsoonal precipitation was witnessed in the beginning of the mid holocene around 8400 cal yr bp implying alteration in the shift toward warm and humid conditions resulting in relatively high pollen abundance for evergreen taxa 4 this phase exhibits a shift to heavier 13 c values around 1850 cal yr bp with an emergence of moist deciduous plants pointing to drier conditions 5 human activities contributed to the exceedingly high percentage of acacia and pinus pollen during the little ice age

palynological record of tropical rain forest vegetation and sea level fluctuations since 140 ka from sediment core south eastern arabian sea palyno chronological study of a 552 cm deep sediment core from the south eastern arabian sea covers a time span of 140 ka the age estimate is based on oxygen isotopic data of planktic foraminifera six zones were identified on the basis of palynology covering partially mis 6 and mis 5 to mis 1 marine isotopic stages the interglacial period mis 5 shows high rate of sedimentation corresponding to high percentage of terrestrial rain forest pollen the palynological study reveals highstand and intense rain forest vegetation during mis 5a which corresponds to the similar earlier records of estuarine ecosystem on land in kerala the relative sea level rise and fall since 140 ka have been inferred through quantitative estimate of marine versus terrestrial palynomorphs the terrigenous non pollen forms comprised abundant neogene extinct nanoplanktons discoaster spp until mis 3 which was transported from the varkala formation highlands of the kerala coast the pollen assemblage is comparable to the present day flora in kerala except ongokea gore which is now present in south africa and therefore the provenance of pollen recorded in the studied core is western ghats of india high percentage of planktic foraminifera and dinoflagellate cysts throughout the core indicates high productivity that suggests upwelling induced by seasonal reversals in the monsoon winds even during the glacial periods botryococcus remains and poaceous leaf cuticles dominated by the pooideae group in the marine realm also point towards active winter monsoon considerable fragmentation of rain forest took place post 74 ka and during the lgm as the sea retreated to its maximum which resulted into the vast exposure of land favoring the expanse of grassland with pockets of rain forest plant refugia on land neogene rain forest flora recorded earlier from the varkala formation and the present record of its existence since mis 6 in the region provide an understanding that the monsoon circulation over southern india was similar since the middle miocene climate optimum and the flora in the south western ghats is a fossil ecosystem and a relic of the tertiary period

major and trace element compositions including ree of mineral thermal mine and surface waters in sw germany and implications for water rock interaction abstract the near surface water cycle in a geologically complex area comprises very different sources including meteoric metamorphic and magmatic ones fluids from these sources can react with sedimentary magmatic and or metamorphic rocks at various depths the current study reports a large number of major minor and trace element analyses of meteoric mineral thermal and mine waters from a geologically well known and variable area of about 200 150 km in sw germany the geology of this area comprises a variscan granitic and gneissic basement overlain in parts by triassic and jurassic shales sandstones and limestones in both the basement and the sedimentary rocks hydrothermal mineralization occurs including pb cu as zn u co and many others which were mined in former times mineral waters thermal waters and meteoric waters flowing through abandoned mines mine waters are distributed throughout the area although the mine waters concentrate in and around the schwarzwald the present analyses show that the major element composition of a particular water is determined by the type of surrounding rock e g crystalline or sedimentary rocks and the depth from which the water originates for waters from crystalline rocks it is the origin of the water that determines whether the sample is na cl dominant deeper origin or ca hco3 dominant shallow origin in contrast compositions of waters from sedimentary rocks are determined by the availability of easily soluble minerals like calcite ca hco3 dominant halite na cl dominant or gypsum ca so4 dominant major element data alone cannot therefore be used to trace the origin of a water however the combination of major element composition with trace element data can provide further information with respect to flow paths and fluid rock interaction processes accordingly trace element analyses showed that ce anomalies can be used as an indicator for the origin of a water whereas surface waters have negative or strongly negative ce anomalies waters originating from greater depths show no or only weak negative ce anomalies eu anomalies can be used to differentiate between host rocks waters from gneisses display positive eu anomalies whereas waters from granites have negative ones waters from sedimentary rocks do not display any eu anomalies rb and cs can also be indicators for the rock with which the fluid interacted rb and cs correlate positively in most waters with rb cs ratios of 2 which suggests that these waters are in equilibrium with the clay minerals in the rocks rb cs ratios 5 indicate reaction of a water with existing clay minerals whereas rb cs ratios the chemical compositions of carbonate precipitates from thermal waters indicate that rare earth elements rees rb and cs concentrations in the minerals are controlled by the incorporation of clay particles that adsorb these elements

bottom water oxygenation history in southeastern arabian sea during the past 140 ka results from redox sensitive elements the concentrations of multiple redox sensitive elements such as re u mo cd v sb and tl were determined in sediments from the southeastern arabian sea 9 o 21 n 71 o 59 e to understand the bottom water oxygenation history throughout the past 140 ka the enrichment of redox sensitive elements re u cd and sb above average crustal abundances suggests that the last glacial maxima 17 48 ka stadials of marine isotope stage mis 5 5b and 5d and glacial termination gt ii 133 ka were associated with suboxic bottom water conditions sediments deposited during these suboxic conditions show the highest re content up to 54 ppb normalized to a carbonate free basis which is highly enriched over average continental crust 0 4ppb and these sediments appear to be the major sink for the global mass balance estimation marine isotope stages 1 3 4 and interstadials of mis 5 5a 5c 5e were all associated with near oxic conditions overall the lack of enrichment of mo and v above crustal abundance and a high re mo ppm ppm ratio avg 18 2x10 3 suggest that sediments of the southeastern arabian sea never contained free h2s during the last 140 ka these changes in the bottom water oxygen content can be related to the oceanic circulation pattern during this time and in part are reflected in relationships between the timing of redox changes and paleoproductivity proxies

centrifuge model test on the retrogressive landslide subjected to reservoir water level fluctuation abstract geological disasters have occurred frequently in the three gorges reservoir area therefore the stability and failure mode research on riverside landslides has become increasingly important taking the toe of liangshuijing landslide as a case study and combining the geological conditions of the three gorges reservoir area a centrifuge slope model is constructed in addition the fluctuation of the water level is simulated in the centrifuge model test based on the digital photography laser displacement sensors lds pore pressure transducers ppt and earth pressure sensors e multi physical data are obtained finally numerical simulation is carried out to analyze the stability and deformation characteristics of the slope model the results indicate that 1 at the water level rise stage the model is dominated by the vertical displacement and the horizontal displacement is much larger than the vertical displacement at the drainage stage 2 cracks first appear at the toe of the slope and extend to the middle and rear of the model gradually then deformation occurs in the middle platform of the slope 3 at the water level rise stage the factor of safety increases rapidly when the reservoir water level remains stable the stability of the slope decreases slowly and at the drainage stage the factor of safety decreases first and then increases 4 there is a significant positive linear correlation between the decline rate of the safety factor and the drainage rate over a certain test range and the stability of the landslides on the reservoir banks would become worse gradually during the long term cyclic operation of the three gorges reservoir

mechanics and velocity of large landslides note preface of the special issue mechanics and velocity of large landslides guest editors c bonnard l laloui s scavia m castelli special issue engineering geology vol 109 2009 reference lms article 2009 009doi 10 1016 j enggeo 2009 07 009 url http www sciencedirect com science journal 00137952 record created on 2009 10 08 modified on 2016 08 08

centrifuge model simulations of rainfall induced slope instability abstractthis study focused on landslides resulting from heavy precipitation such as rainfall from hurricanes a series of centrifuge model simulations were performed with reference to a landslide that occurred during typhoon nabi in japan in 2005 the procedures of simulation on the slope using a sand clay soil mixture were illustrated the rainfall event was simulated by applying precipitation in increments to the slope surface until it exceeded that of the field measurements the instability was examined using an infinite slope analysis and the mechanism of rainfall induced failure was discussed for this particular study the results showed that incremental rainfall of less than 200 mm led to local failures whereas total accumulation of 400 mm resulted in a global slope failure a reduction in apparent cohesion in the soil combined with an increase in pore pressure because of infiltration was responsible for the slope instability during rainfall

tropical rainforest vegetation climate and sea level during the pleistocene in kerala india abstract the southwestern ghats region of the indian peninsula is unique for its extant endemic rainforest flora supported by high rainfall throughout the year the record of tropical rainforest corresponding to the dynamic series of pleistocene interglacial glacial cycles is poorly known from peninsular india this communication discusses the palynological study of organic matter om deposits 40 ka bp in two well sections chaganachery kerala from the indian peninsula west coast a rich archive of tropical rainforest pollen spores and marine dinoflagellate cysts indicates anoxic fluvio marine estuarine depositional environments during warmer climates with an intensified asian monsoon the geochemical fingerprinting of glass shards indicates the presence of youngest toba ash of 74 ka from northern sumatra and therefore establishes a time controlled stratigraphy thus the depositional time period of the om is related to the sea level highstand of marine isotopic stage 5 1 80 ka which was the host to the ytt shards the late quaternary pollen spores diversity suggests that the modern climatic conditions in the southwestern ghats have facilitated the conservation of moist evergreen rainforest and dry moist deciduous forest the pollen grains show its lineage with the extant flora and some of the fossil pollen recorded during the mesic tertiary period from the indian peninsula thus it appears that the tropical rainforest survived here as plant refugia in xeric glacial quaternary periods perhaps as riparian vegetation and was rejuvenated during the holocene as modern extant flora

neogene and quaternary development of the neotropical rain forest the forest refugia hypothesis and a literature overview abstract the upheaval of the northern andes in miocene and pliocene time changed the drainage system in northern south america significantly and caused the present day rain forest areas of choco and the lower magdalena valley became separated from amazonas plant diversity may have reached the highest level in the miocene or pliocene and excessive present day phytodiversity may be regarded as a legacy of the tertiary rather than an evolutionary product of the quaternary in the quaternary strong temperature oscillations related to the series of ice ages were superposed on the late tertiary forest dynamics which included river displacement and latitudinal migrations of the equatorial rain belt caloric equator with the rhythm of the precession cycle of orbital climate forcing the hypothesis that claims a permanent rain forest cover all over the amazon basin during the last glacial is in contrast with the forest refugia hypothesis which accepts replacement of rain forest by savanna or savanna forest during dry climatic intervals both scenarios have been evidenced by pollen records in this paper it is suggested that both hypotheses are not necessarily conflicting and apparently did occur in different parts of the amazon basin and in different periods depending on the climatological constraints a compilation of the most important literature concerning the vegetational climatic and environmental history of the rain forest areas of amazonas and choco and surrounding dry ecosystems has been included

how reliable are non pollen palynomorphs in tracing vegetation changes and grazing activities study from the darjeeling himalaya india abstract in spite of their demonstrated implications as ecological indicators modern analogue studies of non pollen palynomorphs npps from the mountainous regions are still meagre we present here the results of a study on modern npp assemblages recovered from surface samples soils sediments from lake surface and bog etc along a c 130 3600 m a s l elevation gradient in the darjeeling eastern himalaya to test their efficacy in distinguishing different vegetation zones and correlating grazing activities we also used these data to check which of the variables i e elevation vegetation type and grazing pressure is are most influential for deposition of npps and to obtain a npp modern analogue model that may assist future regional paleoecological interpretations we subjected frequency data of 69 npps consisting of algal fungal and zoological remains each identified up to a certain taxonomic rank and some other plant remains like phytoclasts hair bases and wood elements etc to multivariate statistical methods like discriminant da and redundancy rda analyses to assess their ecological indicative values da results showed that npps might be efficient predictors that correctly classified 72 6 of the samples to their correct vegetation zones along the elevation rda results further proved elevation and grazing pressure as the most significant variables influencing npp deposition in the darjeeling himalaya considering the ecological requirements of the studied npps this study also links some npps to their corresponding vegetation zones along the rising elevation as well as different grazing pressure and emphasizes the use of modern analogue studies in palaeoecological interpretations

palaeosols and late pleistocene rainfall fluctuations in the negev desert the existence of a series of palaeosols in the present day desert region of southern israel the northern negev desert 1 2 indicates recurring periods of wetter climate in the past up to seven well developed palaeosols occur within a section and each has a horizon containing soft calcium carbonate nodules 3 15 mm in diameter the palaeosols are developed within loess or fluvially redeposited loess consisting of silty clay or clayey silt the 14c ages of the uppermost three calcic horizons average 13 000 yr bp calcic horizon ch i 28 000 yr bp ch ii and 37 000 yr bp ch iii drier phases occurred between these periods of pedogenesis especially during the last glacial maximum centred at 18 000 yr bp when extensive erosion occurred analysis of the 13c content of nodule carbonates points to the occurrence of strong north south rainfall gradients during each period of calcic horizon formation which excludes the possibility of monsoonal rains contributing to the increased rainfall during these periods the palaeosols correspond to global warm phases of the last glacial period

characterisation of dispersed organic matter from lower palaeozoic metasedimentary rocks by organic petrography x ray diffraction and micro raman spectroscopy analyses abstract dispersed organic matter dom concentrates of c rich rocks from areas with different metamorphic characteristics were studied by organic petrography x ray diffraction xrd and micro raman spectroscopy analysis the concentrates contain several types of dom with different morphologies reflectance x ray diffraction and micro raman characteristics four different morphological types were identified in the two studied areas the different types have different distributions and their reflectance is quite variable in the four types with a dominance of the highest reflectance values in the dom from the area with the highest metamorphic grade xrd analyses of samples from the areas reveal the presence of fine graphite together with non graphitised carbons the raman spectral profiles show the usual bands g 1582 cm 1 and d1 1350 cm 1 on the first order raman spectrum and s1 2700 cm 1 on the second order spectrum additional weaker bands d2 1620 cm 1 and more rarely d3 1500 cm 1 and s2 2900 cm 1 are present these are characteristic for disordered carbons in the different types of dom and in both studied areas however the raman parameters d1 g intensity area ratio and the frequency and width of g band indicate variable degrees of organisation in all dom types the existence of different types of dom with different degrees of ordering in the same lithologies and metamorphic grade seems to be related to different organic precursors as they are graphitised to different extents under the same metamorphic conditions however in the same lithologies and metamorphic grade the existence of various stages of graphitisation within the same type of dom can only be explained though the interaction of dom with the metamorphic fluids present in the rocks the ordering graphitisation process may be due to the existence of metamorphic fluid circulation events with a variety of compositions