miocene gypcretes from the calama basin northern chile gypcretes of miocene age are preserved beneath a 9 53 0 36 ma ignimbrite along the eastern margin of the oligo pleistocene calama basin northern chile they are restricted to a single stratigraphic horizon developed within laterally extensive 35 km coalesced alluvial fan deposits developed along the margin of an endorheic basin two types of gypcrete are recognized type 1 comprises almost completely gypsum cemented sandstones containing alabastrine nodules and columns sub vertical and horizontal veins of fibrous gypsum and v shaped cracks infilled by clastic material and are interpreted as surface weathered gypsic crusts type 2 gypcretes are composed of massive reddened poikilitic and mesocrystalline gypsum up to 80 of the rock with isolated bedding parallel clast rich lenses 200 30 cm and sub vertical veins of fibrous gypsum the massive texture resembles that of well developed b horizons in quaternary alluvial desert soils the crystal forms suggest an origin as a subsurface gypsic crust formed by a combination of hydromorphic poikilitic and illuvial mesocrystalline processes with the fibrous gypsum veins suggestive of periodic surface exposure gypcrete horizons are up to 25 m thick and composed of both gypcrete types they represent superimposed phases of surface and subsurface gypcrete development quaternary gypcretes are developed in arid climatic regimes but are not considered to develop under hyper arid climates an arid climate is considered to have prevailed in the study area up to 9 5 ma after which a change to hyper aridity favoured gypcrete preservation

correlation and interpretation of paleosols and loess across european russia and asia over the last interglacial glacial cycle abstract loess paleosol sequences of the last interglacial glacial cycle are correlated from european russia to central siberia and the chinese loess plateau during cold periods represented by marine oxygen isotope stages ois 2 and 4 loess deposition dominated in the russian plain and the loess plateau in central siberia loess deposition took place also but five to seven thin weakly developed paleosols are identified in both stages ois 3 in the chinese loess plateau near yangchang consists of a loess bed that is flanked by two weakly developed paleosols at kurtak siberia ois 3 is represented by two distinct stacked paleosols with no loess bed separating the paleosols in the russian plain ois 3 consists of a single possibly welded paleosol representing upper and lower stage 3 climates brunisols and chernozems dominate the profiles in china and siberia whereas regosols luvisols and chernozems are evident in the northern and southern russian plain respectively ois 5 is represented in china and the russian plain by pedo complexes in a series of welded soils whereas in contrast the kurtak site consists of six paleosols with interbedded loess the paleosols consist largely of brunisols and chernozems although the three areas examined have different climates geographical settings and loess source areas they all had similar climate changes during the last interglacial glacial cycle

atmospheric radiocarbon calibration to 45 000 yr b p late glacial fluctuations and cosmogenic isotope production more than 250 carbon 14 accelerator mass spectrometry dates of terrestrial macrofossils from annually laminated sediments from lake suigetsu japan provide a first atmospheric calibration for almost the total range of the radiocarbon method 45 000 years before the present the results confirm the recently revised floating german pine chronology and are consistent with data from european and marine varved sediments and combined uranium thorium and carbon 14 dating of corals up to the last glacial maximum the data during the glacial show large fluctuations in the atmospheric carbon 14 content related to changes in global environment and in cosmogenic isotope production

morphology and micromorphology of the loess paleosol sequences in the south of the east european plain mis 1 mis 17 abstract the micro and macromorphological studies performed on the loess soil sequences in the south of the east european plain permitted to identify and describe the type of soil formation processes that took part in the development of interstadial and interglacial paleosols four paleosol complexes are distinctly identified within the limits of the studied region vorona mis 13 15 inzhavino mis 8 9 or mis 10 11 kamenka mis 6 7 or mis 8 9 mezin mis 5 besides there are the bryansk interstadial paleosol mis 3 and rzhaksa interglacial paleosol mis 17 both well identifiable in the region the results obtained are in general agreement with the earlier conclusions by velichko et al 2012 about a general reduction of heat and moisture supply and an increase in aridity from the earlier towards later stages of the pleistocene the new data revealed however a few differences from the earlier concept to mention but one example we have found that the kamenka interglacial mis 7 or mis 9 paleosols formed in environments more humid than those of the likhvin interglacial mis 9 or mis 11

thermoluminescence dating of the orkutsay loess section in tashkent region uzbekistan central asia abstract the chronology of loess in central asia was investigated by means of thermoluminescence dating tl in the 1970s when age estimates ranging from 20 ka to over 800 ka were taken as providing an absolute chronology this has caused major misinterpretation of central asian loess stratigraphy and palaeoclimatic reconstruction we present a new tl study of a loess section at orkutsay in the tashkent region uzbekistan nine samples spreading over a large stratigraphic interval yield apparent tl ages ranging from 20 ka to 134 ka we interpret our tl results with reference to recent tl dating studies of loess from other regions we consider most of our tl age estimates obtained by the regeneration method to be underestimated a single tl date of 92 8 ka obtained by the total bleach method for loess just below the first pedocomplex pc 1 of the last interglacial is also significantly younger than expected we attribute the underestimation to sensitivity change induced by the laboratory optical bleach and instability of the tl signal we conclude that the current tl techniques as employed in this study cannot provide a reliable absolute chronology for the sequence below pc 1 and cannot provide even a relative chronology for the loess below pc2 for the orkutsay section the dating limit is around 130 ka the results of this study suggest that the previous central asian loess chronology based on early tl studies is not valid

environmental context of pleistocene peopling of the central urals abstract the broader territory of the urals has principal significance for elucidating the historical processes and environmental contexts of the pleistocene expansion of people from the south eastern parts of europe into west siberia and the northern russian arctic regions interaction of past climate change and the regional topographic modelling triggered by neotectonic activity reflected by pronounced natural transformations attest to the complexity of the quaternary development in the central urals affecting timing and intensity of the earliest human occupation of this territory the initial peopling of the western fore ural area is associated with the early palaeolithic dispersal into the marginal east european plain probably during some climatically favourable middle pleistocene interglacials the chusoaya river valley transecting the central ural mountain range was one of the main geographic corridors for the subsequent middle and upper palaeolithic migrations into the eastern trans ural regions of west siberia a long term behavioural adjustment to cold periglacial habitats is linked to progressive cultural and biological evolution during the late pleistocene the north central trans urals upper palaeolithic complex in the sosva river basin with open occupation sites based on mammoth fauna exploitation indicates adaptation to sub polar tundra steppe environments of the west siberian plain during the last glacial stage geoarchaeological records provide further insights into the timing and ecology conditions of the pleistocene colonisation of north central eurasia the present study summarises the current evidence on trajectories of the pleistocene environmental development in the broader central urals still a marginally investigated geographical area of eurasia

structure chemistry and origins of gypsum crusts in southern tunisia and the central namib desert gypsum crusts are broadly defined as accumulations at or within about 10 m of the land surface from 0 10m to 5 0 m thick containing more than 15 by weight gypsum caso4 2h2o and at least 5 0 by weight more gypsum than the underlying bedrock the deposits are often but not invariably consolidated owing to cementation by gypsum the crusts are found in many of the world s deserts where mean monthly potential evaporation exceeds mean monthly precipitation throughout the year using structural fabric and textural criteria three main types of crust may be distinguished 1 bedded crusts found either at or beneath the land surface which are made up of discrete horizontal strata up to 0 10 m thick each showing a gradation in gypsum crystal size from less than 50 m at the top to more than 0 50 mm at the base 2 subsurface crusts of which there are two forms one made up of large lenticular crystals up to 0 50 m in diameter the desert rose crusts and the other a mesocrystalline form with gypsum crystals up to about 1 0 mm in diameter and 3 surface crusts which are subdivided into columnar powdery and cobble forms all of which are made up of predominantly alabastrine gypsum crystallites less than 50 m in diameter in southern tunisia and the central namib desert bedded crusts are found around ephemeral lakes and lagoons they are characterized by size graded beds gypsum contents of 50 80 by weight and comparatively high concentrations of sodium potassium magnesium and iron they are interpreted as shallow water evaporites which accumulate when saline pools evaporate to dryness desert rose crusts or croutes de nappe generally contain 50 70 by weight gypsum and have higher sodium concentrations than the second subsurface form texturally they are characterized by poikilitic inclusion of clastic material within large lenticular crystals they are interpreted as hydromorphic accretions which precipitate in host sediments at near surface water tables through the evaporation of groundwater the second form of subsurface crust the mesocrystalline often occurs in close association with the various surface forms unlike the hydromorphic crusts they are not restricted to low lying terrain they are characterized by gypsum contents reaching 90 by weight and have a close chemical and textural similarity to columnar surface crusts this mesocrystalline form represents an illuvial accumulation the surface forms excluding the bedded crusts are exhumed examples at various stages of solutional degradation subsurface precipitation of gypsum from meteoric waters containing salts leached from the surface results in displacive gypsum accumulation in the soil zone in southern tunisia the gypsum is derived from sand and dust deflated from evaporitic basins in the central namib salts dissolved in fog water are the most likely source where other salts are present differential leaching may form two tiered crusts calcrete gypsum or gypsum halite if rainfall is sufficient to mobilize the less soluble salt yet insufficient to flush the more soluble gypsum crust genesis is restricted to arid environments and if their susceptibility to post depositional alteration is acknowledged they can provide valuable palaeoclimatic indicators

sedimentological and palaeoenvironmental study from waregi hill in the hiwegi formation early miocene on rusinga island lake victoria kenya

reply to vogt s comments on the paper fibrous clay mineral formation and soil evolution in aridisols of northeastern patagonia argentina by p j bouza m simon j aguilar h del valle and m rostagno

the occurrence and interpretation of carbonate and sulfate minerals in a sequence of vertisols in new caledonia abstract in the tamoa valley on the western coast of new caledonia a vertisol sequence shows a downslope transition from calcimagnesic vertisols containing gypsum aragonite and magnesium calcite derived from flysch colluvium to hypermagnesic vertisols rich in dolomite and magnesite and derived from peridotite and serpentinite alluvium deposited by the tamoa river gypsum magnesium calcite and magnesite were probably formed during the dry period of the last glaciation between 30 000 and 17 000 yr b p magnesite nodules seem to be allochtonous and were formed upstream by the weathering of serpentinite during the more humid period of last flandrian transgression 5000 yr b p floods of the magnesium rich waters of the tamoa river over the alluvial plain brought magnesium to the soils and lead to fluctuations of the water table these conditions favoured the formation of manganese deposits as mangans calcite pseudomorphs after lenticular gypsum crystallization of authigenic barite in calcimagnesic vertisols and dolomite formation in magnesic and hypermagnesic vertisols during the recent period apparently drier aragonite is forming in the lower part of calcimagnesic vertisols

the origin and distribution of salts on alluvial fans in the atacama desert northern chile the atacama desert has been predominantly hyperarid since the middle miocene combined ionic and x ray diffraction analysis shows that calcium sulphate is prevalent on three similar alluvial fans in salar basins across a transect of different environments in antofagasta province northern chile differences between the fans were largely due to the effect of local factors on salt input secondary redistribution and deposit preservation thus carbonate was notable in the high andes fan c and pre cordillera fan b whereas in the central valley fan a greater qualities of the more soluble salts chlorides and nitrates probably reflect the higher level of aridity and an oceanic source the camanchaca calcium sulphate distribution on the alluvial fans and on adjacent hilltops indicates an aeolian origin evidence from the pre cordillera fan b however suggests that salt input may have been episodic related to changes in conditions within the general aridity and possibly to stone pavement and soil development calcium sulphate sources range from an input in andean precipitation and the camanchaca to abundant regional evaporite deposits it is probable however that products of andean volcanism constitute the dominant primary source of calcium sulphate and that the salt has subsequently been distributed widely within the endoreic basins of the region by a combination of groundwater surface flow and the wind 1997 john wiley sons ltd

loess in europe mass accumulation rates during the last glacial period abstract upper pleistocene loess palaeosol sequences provide excellent high resolution terrestrial archives of climate forcing due to improvements in numerical age determinations especially in luminescence dating methods a more reliable time based reconstruction of the past climate and environmental change has become available for the loess record in europe chronological information was collected from 43 sites along a northwest to southeast transect in europe thirty three of these sites had sufficient age information to allow estimation of mass accumulation rates and it was possible to isolate the mass accumulation rates of primary loess during the last glacial period 28 13 ka bp at 21 of these locations these sites fall along a coarse climatic gradient from the relatively coastal climate of belgium and france to the drier more continental climate of central europe interpreting mass accumulation rates of loess in terms of this climatic gradient is not straightforward as these deposits are dominated by sources in floodplains and large river systems thus accumulation rates are influenced strongly by regional wind and precipitation patterns but mostly by the availability of glacially derived material from the alps and the periglacial terrains that characterized european fluvial systems during and immediately following glaciation

late miocene turnover in the spanish mammal record in relation to palaeoclimate and the messinian salinity crisis abstract the latest miocene and earliest pliocene is a period of marked changes in geography and climate in the circum mediterranean area its geographical situation gives spain a key position and its fossil mammal record reflects these important geographical and climatic changes particularly well the spanish mammal record shows a gradual change of composition towards the typical pleistocene and recent fauna marked by several extinction and dispersal events these events have the effect that northern eurasian elements increase while taxa that locally go extinct may live on in tropical areas superposed on this large scale trend there are some events of short lived incursions of animals of african or south asian origins which seem to reflect a short reversal of this tendency and temporary geographical changes related to the messinian crisis these latter incursions are detected very well in spain but also in other parts of southern europe the messinian salinity crisis is caused by interplay of tectonics and global sea level variations which in turn depend on climate while some of these changes were permanent causing the replacement of central italian insular faunas by mainland faunas others were temporary probably allowing the short lived incursions of african mammals into sw europe and certainly allowing for mammals to reach the balearics corsica and sardinia we document an important event around 6 1 ma of mammals adapted to dry or open environments dispersing from africa and se europe to sw europe during the messinian desiccation phase animals adapted to more humid environments reached some of the west mediterranean islands suggesting that at least during part of the desiccation phase a part of the former sea bottom was not desertic between 6 3 and 5 3 ma tectonics united the island of toscany to the european mainland thereby closing a seaway of some 10 km wide and 100 m deep

progressively cooler drier interglacials in southern russia through the quaternary evidence from the sea of azov region loess palaeosol exposures along taganrog bay sea of azov in southern russia reveal a complex succession of quaternary palaeoenvironments over the past 0 7 million years the deposits overlie marine sediments of tiraspolian cromerian age at the key section of semibalki 1 four palaeosol complexes are identified within the series the earliest palaeosol complex in the semibalki 1 section is correlated with the late muchkap interglacial the vorona palaeosol the soil type resembled modern subtropical mediterranean region soils the later middle pleistocene palaeosols bear evidence of soil forming processes typical of various temperate zone environments with a gradual transition to increasingly cooler drier conditions soils suggesting transitional development between kastenozems and chernozems developed during the likhvin interglacial inzhavino pc pc 2 kamenka interglacial is typified by eluviated luvic chernozemic soils possibly formed under prairie parkland conditions finally the mikulino integlacial of the late pleistocene mezin pc is represented by chernozems similar to the modern holocene soils of the region but showing enhanced podzolization and fewer seasonal frost features a succession of environmental changes has been traced in the study region from semi humid subtropical environments at the end of the early pleistocene to prairie environments then to boreal mild temperate during the middle pleistocene and finally towards landscapes with typical steppe soils in the late pleistocene and holocene the sequence indicates that moisture supply and temperatures during successive interglacials shifted progressively towards increasingly cooler somewhat drier climates influencing soil formation

loess paleosol formation on the russian plain abstract the east european loess province is the largest one not only in the northern hemisphere but also on the earth the chronostratigraphic scheme for this province was worked out on the basis of data obtained by different research methods accumulation of loess like deposits began at the end of the pliocene in the post akchagilian time deposition of silt material and loess formation began in the second half of the eopleistocene during this period up to the holocene about 1 ma 6 interglacial soil complexes can be identified according to paleomagnetic data the brunhes matuyama boundary occurs within the don loess which corresponds to maximum don glaciation of eastern europe the composition of the loess paleosol complex of the middle pleistocene is much more complicated there are 3 interglacial soil horizons overlain by the middle pleistocene moraine of the dnieper glaciation a well developed interstadial soil horizon bryansk soil can be distinguished within the late pleistocene formation 32 26 ka bp the structure of the loess paleosol complex varies over different regions of the east european loess province these differences can be shown on a new type of map that of loess paleosol chronocomplexes

a luminescence dating study of loess deposits from the beglitsa section in the sea of azov russia abstract the loess palaeosol deposits at the beglitsa section in the east european plain play an important role in the understanding of climate and environmental changes in eurasia however the absence of absolute geochronology has restricted the interpretation of the loess sedimentation process and its relevance to palaeoenvironmental change in this paper a detailed chronology was obtained from the beglitsa section using a quartz optically stimulated luminescence osl dating technique in the southern area of the east european plain grains with a diameter of 38 63 m extracted from 8 samples and a single aliquot regenerative dose sar protocol were applied for equivalent dose de determination the results showed that the osl ages are generally in agreement with the field observed stratigraphic order and no age inversions were apparent compared with magnetic susceptibility and previously published radiocarbon ages the osl dating results showed great potential to provide a reliable chronology sequence for loess sediments in the sea of azov with a span ranging from 5 4 0 4 to 203 8 18 0 ka deposition of the azov loess may have begun during the penultimate glaciation based on a comparative analysis of the stratigraphic composite the sedimentary thickness differences between sections around the azov region were likely affected by the local topography and the location

quaternary stratigraphy and optical dating of loess from the east european plain russia abstract optical dating of silt sized potassium feldspar grains was found to be suitable for dating the formation of key loess units at two sites on the central east european plain loess bracketing the bryansk palaeosol yielded optical ages in agreement with the well dated radiocarbon chronology when corrected for anomalous fading optical ages from loess bracketing a significant pedogenic unit below the bryansk palaeosol support our lithostratigraphic interpretation that it is the mezin palaeosol complex and its formation during the last interglaciation oxygen isotope stage ois 5 optical ages from a stratigraphically older loess unit directly underlying a significant 10 m thick till unit in conjunction with its regional stratigraphic context suggest that the loess and the till were deposited during the dnieper glaciation which probably occurred during ois 6

the matuyama brunhes boundary in loess sections in the south of the east european plain and their correlation on the basis of palaeomagnetic and palaeopedologic data abstract the matuyama brunhes boundary mbb in loess sections of the east european plain one of the greatest areas of global loess distribution is a highly debatable issue the ambiguity of the mbb position here results from the complexity of loess soil magnetization processes and an apparent delay in loess remanence acquisition and from the uncertainties of pedostratigraphic interpretations in the don glaciation area the mbb is unanimously placed below the don moraine although the exact position is still controversial in the sites of the northern azov sea the mbb is however placed in the loess horizon considered to be the equivalent of the don moraine in the north the inconsistency of this interpretation is demonstrated by detailed magnetostratigraphic and pedostratigraphic studies in the western sites of zaporozh e dnieper basin novaya etuliya lower danube basin and roxolany lower dniester basin in all these sites albeit with certain minor discrepancies the mbb is found two or three interglacial palaeosols below the don loess which is overlain by the good stratigraphic marker of the vorona pedocomplex a thick polygenetic red brown palaeosol formed supposedly in a mediterranean climate here the mbb is placed in a quadruple soil unit termed roxolany loess soil suite which consists of four closely spaced strongly calcareous soils occupying an interval between the don loess on top and the earlier well developed bobrov loess with reversed matuyama magnetization the roxolany suite can possibly be correlated with the three palaeosols of the pre don ilyinka unit of the russian unified stratigraphic scheme and thus confirms the interpretation of the mbb in the central areas of the east european plain as to the interval between the ternovka second pre don palaeosol and the troitsk third pre don palaeosol

rock magnetic signature of a miocene playa cycle in central asia and environmental implications the increased aridification of central asia during the miocene coincides in time with lake formations and the evolution of playa environments in the region however miocene continental climate dynamics and the forcing of aridification are still not well constrained neogene lacustrine mudflat deposits in the ili basin in southeast kazakhstan provide a well exposed paleoclimate archive here we present a detailed rock magnetic study of a middle miocene playa cycle deposited in a closed basin we use high resolution rock magnetic parameters lithological studies and geochemistry to reconstruct the playa environment and the depositional conditions the rock magnetic mineralogy of the playa cycle is controlled by hematite and two fine grained magnetite phases increased magnetic concentrations occur during dry mudflat conditions with a lower groundwater table and increased aridity the underlying processes controlling the observed variation in magnetic concentrations are a complex interplay of diagenetic processes during and after deposition the data support an authigenic origin of both magnetite phases one formed before and the other after sediment consolidation early diagenetic formation of fine grained magnetite by microbial activity is followed by post depositional formation of a secondary fine grained magnetite phase the rock magnetic results such as magnetic concentration dependent parameters arm sirm and s ratio indicate a sensitive record of ground water availability and aridity changes in the ili basin we suggest that they can serve as an effective proxy for detailed paleo environment reconstruction of playa evolution not only in the middle miocene ili basin but also in comparable floodplain playa lake settings

aeolian landscapes in central australia gypsiferous and quartz dune environments from lake amadeus there are two different dune systems in central australia regional quartz dunefields and transverse gypsiferous dunes associated with playa lakes these two systems especially gypsiferous dunes at lake amadeus the largest playa in central australia provide a sedimentary geomorphological and environmental history of the region during the late quaternary the gypsifierous dunes consist of a surficial gypcrete overlying an aeolian sediment sequence below a mixture of gypsum sand and quartz sand no clay pellets have been found in the dune sequence in significant contrast to the gypsiferous clay dunes in other parts of australia three possible models of the environmental controls of gypsiferous dune formation are discussed the most plausible one suggests simultaneous gypsum precipitation and deflation sandsized gypsum was precipitated in a groundwater seepage zone around the playa margin during seasonally high water tables and these crystals were deflated onto land during dry intervals forming the marginal gypsiferous dunes these processes require conditions of high regional water table strong climatic seasonality and probably a windier and overall wetter climate at least two separate gypsiferous duneforming episodes can be recognized the age of formation of the younger one has been dated by thermoluminescence at 44 54 ka the gypcrete crust capping the dunes is characterized by intergrown microcrystalline gypsum crystals showing evidence of leaching dissolution and recrystallization it is interpreted as a pedogenic product formed during a stable period after accumulation of the gypsiferous dune after the construction of the younger gypsiferous dune there was a major episode of activation of regional quartz dunefields which formed thick quartz sand mantles overlying gypsiferous dunes on both playa margins and the dune islands within the playa an equivalent aeolian sand layer was deposited within the playa soil structures in this unit indicate that the sand sheet over the playa was later colonized by vegetation activation of the regional dunefields suggests a major period of dry climate which although not dated may correlate with the last glacial maximum identified as a period of maximum aridity from 25 to 18 ka at other sites in australia

sequence stratigraphic analysis of jurassic and cretaceous strata and petroleum exploration in the central and eastern gulf coastal plain united states the formulation of an integrated sequence stratigraphic and biostratigraphic framework is fundamental in the design of an effective strategy for petroleum exploration in a sedimentary basin for the interior salt basins of the gulf coastal plain of the united states that are filled primarily with mesozoic postrift nonmarine to marine siliciclastic and carbonate deposits a sequence stratigraphic approach using transgressive regressive t r sequences and integrated with biostratigraphic information has utility as a method for establishing such a framework the sequence stratigraphy established for upper jurassic and cretaceous strata is used to categorize petroleum reservoirs in the central and eastern gulf coastal plain transgressive aggrading eolian fluvial and coastal sandstone facies of the t r sequences include highly productive hydrocarbon reservoirs in the eastern gulf coastal plain productive reservoirs in the central and eastern gulf coastal plain include regressive infilling fluvial to nearshore marine sandstone facies and nearshore marine shelf ramp and reef carbonate facies transgressive backstepping nearshore marine facies include highly productive reservoirs in the central gulf coastal plain these transgressive and regressive facies are recognized by their wireline log patterns and seismic reflection configurations knowledge of the diagnostic wireline log signatures and seismic reflection characteristics assists in the detection of exploration targets

ubiquity of anomalous fading in k feldspars and the measurement and correction for it in optical dating anomalous fading rates were measured in k feldspars separated from 49 sediment samples mainly from north america the intensity of the optically stimulated luminescence was found to decrease linea

an improved alpha scintillation counting method for determination of th u ra 226 th 230 excess and pa 231 excess in marine sediments in a previous paper it was shown that thick source counting is a simple means for determining th u th 230 excess and pa 231 excess concentrations and hence sedimentation rates for deep sea sediments here it is shown that radon escape can lead to inaccurate results if powdered samples are used and that this problem can be overcome by preparing samples as a borate glass before measurement glassed samples also permit a novel measurement of the ra 226 content by measurement of the post fusion buildup of rn 222 a determination shown to be necessary for near surface sediments that have a deficit of ra 226 it is also shown that po 210 is lost during the fusion and that this loss can be allowed for in the calculations the above observations are found on comparisons of measured and calculated count rates for several th and u standards and on comparisons with spectrometry results from four sets of deep sea core samples

pleistocene climate change natural environments and palaeolithic occupation of east kazakhstan abstract the territory of east kazakhstan the southern altai mountains the bukhtarma and zaisan black irtysh basins still insufficiently investigated because of its proximity to the kazakh russian chinese border zone shows a complex quaternary history and the associated environmental transformations reflected by intensive geomorphic processes related to the past global climate evolution in conjunction with the regional neotectonic activity the marked climatic changes are indicated by the preserved palaeolandscape forms in both the mountain and steppe regions as well as by the glacial and sedimentary geology palaeoecology and geoarchaeology proxy records indicating long term variations in temperature as well as humidity following the generally warmer early pleistocene climates witnessed by the distribution of deeply weathered red palaeosols the increased continentality and relief gradient during the middle and particularly the late pleistocene led to establishment of the present type forest steppe semi desert during warm stages and the periglacial arid steppe during cold stages correlated with the glaciations in the southern altai mountains and loess deposition in the foothills the mapped glacigenic and high resolution loess palaeosol sections and contextual environmental archaeology data from the pleistocene occupation sites provide new evidence of a rather pronounced natural dynamics spectacular glaciofluvial terraces in the principal mountain valleys indicate the presence of deep ice dammed last glacial lakes documented from other parts of the altai that were subjected to cataclysmic drainages during deglaciations the recently discovered localities in the bukhtarma river valley in diverse settings bear witness of a much earlier middle upper palaeolithic inhabitation of this geographically marginal area and adaptation to local mountain and steppe environments predating the holocene prehistoric cultures this paper summarizes some results of the initial multidisciplinary quaternary field studies in the southern altai region of east kazakhstan and the adjacent part of gorno altai 2003 2007

facies and evaporite genesis of the kuscular formation lower paleocene saline playa complex eastern turkey abstract the kuscular formation lower paleocene located in eastern turkey is an alluvial and playa foreland basin succession deposited in a semi arid climate the playa deposits of the kuscular formation composed of interbedded green sandstone siltstone mudrock gypsiferous sandstone red green gypsiferous mudrock and banded nodular secondary gypsum are found among the distal alluvial fan deposits interbedded green sandstone siltstone mudrock with desiccation cracks are interpreted as dry mudflat sandflat deposits the banded nodular secondary gypsum and gypsiferous mudrocks which contain desiccation cracks are interpreted as a saline playa and saline mudflat distal alluvial fan deposits are represented by stratified conglomerate and stratified pebbly sandstone the sulfur in the evaporites was very likely derived from the oxidation of sulfides in upper cretaceous magmatic rocks comprising the basement of the basin soft sediment deformation structures slump folds which indicate seismically active areas were formed within the playa and dry mudflad sandflat complex the facies aspects of playa deposits would suggest that the climate in turkey was semi arid during the early paleocene

pedogenic and groundwater processes in a closed miocene basin northern spain abstract the sepulveda ayllon basin sab was an episodically closed miocene basin adjacent to the tertiary duero basin northern spain the sediments studied here represent a depositional system developed from the margin to the centre of the basin by alluvial fan mud flat and saline mud flat ephemeral lacustrine environments an assemblage of authigenic lithotypes was formed in the basin their distribution being influenced by that of the depositional environments within the basin authigenesis took place mainly before sedimentation of the next set of beds in the distal alluuial fan authigenesis of smectite outer part palygorskite inner part and calcrete predominates and the original muddy deposits are still recognizable in the mud flat a more intense transformation of the sediments took place with predominant formation of palygorskite outer part interstitial gypsum calcrete outer part dolocrete inner part and brown silcrete in the saline mud flat ephemeral lake original sediment was extensively disturbed and replaced by magnesian clays sepiolite and magnesian smectite interstitial gypsum dolocrete and cream and white silcrete authigenic alteration within each cycle varied in time and place and was both pedogenic and groundwater related the authigenic assemblages point to a closed basin under evaporation in a seasonally dry climate at the end of this period the sab became connected with the duero basin to the northeast thus losing the endoreic regime consequently the authigenic evaporitic assemblages were then unstable and were partially replaced by a late sparry calcrete

middle to late pleistocene topography evolution of the north eastern azov region abstract the structure of loess soil sequences of the north eastern azov region was studied in coastal outcrops and boreholes within four key areas of the terraces of different age based on the positions of paleosols in geological sections of interfluve areas the palaeotopography during interglacial epochs of the last 500 ka was reconstructed the analysis of the topography evolution showed that the most significant features of the primary fluvial marine relief remained in subaerial stage of the surface development and were inherited even in modern relief at the same time in subaerial stage the surface of interfluves experienced considerable reworking due to loess accumulation on the one hand and erosion on the other hand it has been established that these processes were controlled by the glacial interglacial climatic cycles however their intensity varied from cycle to cycle generally before the valdai weichselian glacial epoch loess accumulation prevailed on the interfluve areas the intensity of erosion at that time was relatively low during the valdai epoch by indirect evidence during its final stage mis 2 29 12 ka a phase of exceptionally intensive erosion was detected due to it linear erosion and slope processes developed even within fairly gently slope 2 4 areas it has been determined that during this time the upper parts of gullies were growing rapidly towards watersheds in the modern topography a branched pattern of relic hollows inherits their position

late quaternary climatic changes revealed by luminescence dating mineral magnetism and diffuse reflectance spectroscopy of river terrace palaeosols a new form of geoproxy data for the southern african interior lyons j r tooth s duller g 2014 late quaternary climatic changes revealed by luminescence dating mineral magnetism and diffuse reflectance spectroscopy of river terrace palaeosols a new form of geoproxy data for the southern african interior quaternary science reviews 95 43 59

the stranded beach dune sequence of south east south australia a test of thermoluminescence dating 0 800 ka the remarkable sequence of stranded beach dunes in south east south australia deposited during the past 800 ka has provided us with a rare set of samples for testing thermoluminescence sediment dating methods here we report thermoluminescence ages obtained from quartz separated from the dunes and compare them with accepted ages for the high sea levels responsible for the dunes the independent ages of the dunes were obtained from earlier work by schwebel which has been extended and refined by modelling the dune formation using sea level variations derived from the oceanic 18o record the work is unusual in extending thermoluminescence dating to an 800 ka sequence with modest geological control of the age the agreement between thermoluminescence and geological ages is satisfactory for eight dunes with ages in the range 120 800 ka quartz is not usually thought to be useful for thermoluminescence dating in this time span two factors contribute to our success the first is that the dose rates are low about 0 5 gy ka 1 or one quarter of that typical of sediments the second is that the thermoluminescence vs dose response continues to rise monotonically above the saturation region at doses above 300 gy

sediment source regions and paleotransport of the upper jurassic norphlet formation eastern gulf of mexico the upper jurassic norphlet formation is an eolian sandstone and important hydrocarbon reservoir that overlies the louann salt in the gulf of mexico gom because the sand was concentrated into dunes formed by late jurassic winds determining the source areas and paleotransport direction of the sand can improve predictions of the distribution of the dune facies around the gom paleo wind blown sediment transport into the proto gom was controlled by wind direction and magnitude and the extant topography of the basin and adjacent uplands analysis of the norphlet formation in the eastern gom shows that wadis and alluvial fans controlled by the location of highs were the primary route for introducing sediment of varied provenance into the eolian erg eolian transport directions interpreted from dip log analyses are south directed in southern alabama and west to northwest directed in western florida interpretations of regional two dimensional prestack depth migrated seismic data show that erosional incision of the middle ground arch occurred prior to and during the time of norphlet deposition this as well as preexisting lows in the basement topography may have facilitated basinward sand transport of sediment that fed the norphlet formation erg preserved in the deep water subsurface eastern gom

the hydrological setting occurrence and significance of gypsum in late quaternary salt lakes in south australia well exposed often laminated gypsum sequences occur in many quarternary salt lakes in southern south australia the gypsum in the salt lakes is classified by increasing grain size into gypsite gypsarenite and selenite the salt lakes are classified by age and hydrological setting into coastal salinas which are holocene sea water fed groundwater lakes and continental playas which are late pleistocene endorheic basins a study of the relationships between coastal salina hydrology and the associated gypsum deposition has shown the different types of gypsum form under distinct hydrological regimes as the hydrology above a coastal salina depositional surface changes through time so does the type of gypsum deposited application of a gypsum depositional model derived from a study of the coastal salina gypsum to those portions of a continental playa gypsum unit where deposition is no longer occurring confirms the applicability of the model to non salina gypsum deposits

petrography and genesis of quaternary coastal gypcrete in north kuwait arabian gulf abstract gypcrete crusts cover late quaternary playa deposits within the northern coastal flat of kuwait bay arabian gulf this study provides insight into the genesis of the gypcrete crust associated with the fluvial playa in an arid coastal area the playa sediments are mostly muddy sand rich in diagenetic gypsum the latter is concentrated at the top part of this playa where the gypcretic crust is developed field investigation megascopic microscopic and nanoscopic examination and xrd analysis revealed the occurrence of several types of gypcretes namely massive hard crust hard clustered gypsum roses gypseous rhyzocrete and powdery crust with the exception of the last type all gypcretes are formed largely of gypsum with subordinate amounts of bassanite two genetic types of bassanite are recognised these are replacive and precipitative replacive bassanite is the most common and is mainly represented by topotactic alteration of gypsum whereas the precipitative mode is mostly restricted to the powdery crumbled crust and root cavity fill the micromorphology of both types of bassanite is discussed it is suggested that the stability of bassanite is attributed to the elevated ambient temperatures in the presence of highly saline brine and organic acids

the middle palaeolithic of the central trans urals present evidence abstract the urals and the adjacent regions located at the easternmost limits of europe and representing a geographic borderline with northern asia west siberia are of key relevance for comprehension of the culture historical trajectories and environmental contexts of early peopling to this still marginally explored montage russian territory complex quaternary transformations of regional natural settings due to climate change controlled timing and dynamics of palaeolithic occupation in the central mountain zone foothills and adjoining fore ural and trans ural plains following the earliest and still sporadically mapped presence of the pre middle pleistocene humans in the upper kama basin the first marked geoarchaeology evidence is linked to the middle palaeolithic inhabitation of the urals foothills and the mountain inner valleys the chusovaya river valley and its tributary valleys transecting the central ural s mountain range ne sw were the principal corridor for the following middle and upper palaeolithic migrations into the eastern trans ural regions and west siberia except for mountain karst formations present middle palaeolithic habitat indices come from the eastern ural foothills the leba neiva and tara river basins with occupation and workshop sites nearby natural exposures of rocky outcrops exploited as raw material deposits for lithic industry production diagnostic technological attributes of employed levallois and bifacial stone flaking techniques with corresponding lithic artefact inventories provide some means for the general pre upper palaeolithic age assessment of the investigated sites the limited number of the mapped middle palaeolithic loci does not allow evaluation of spatio temporal settlement patterns the present cultural evidence illustrates successful biological and behavioural adjustments to the central urals ecosystems in the framework of middle late pleistocene cultural development

a high resolution late quaternary climatostratigraphic record from iskitim priobie loess plateau sw siberia abstract the siberian loess being a part of the eurasian loess belt has provided the most complete terrestrial record of past climate change in the north central asia the continuous high resolution sections of aeolian dust deposits inter bedded with fossil soils from the priobie loess plateau and the northern altai plains mapped as a part of the 2000 km w e siberian palaeoclimate transect have produced extraordinary evidence of the late quaternary climate evolution and landscape development in the parkland steppe north of the altai sayan mountains a complete stratigraphic loess palaeosol record was studied at the iskitim reference section spanning the last c 250 ka mis 7 1 the climate indicative proxy data magnetic susceptibility grain size caco3 toc and thin section studies show marked and cyclic climatic variations particularly pronounced during the last interglacial glacial cycle equivalent to the loess reference sites from the yenisei and katun altai plain areas the kurtak and krasnogorskoye sections the iskitim loess palaeosol record illustrates a rapid onset of the last interglacial in agreement with the marine oxygen isotope records with a strongly continental warm climate culminating around the peak of the last interglacial mis 5e this was succeeded by a dramatic cooling mis 5d defined by a major cryogenic event that resulted in deformation of the mis 5e chernozem followed by loess deposition in congruence with the lake baikal detrital stratigraphic sequence cooler climate conditions during the subsequent interglacial sub stages mis 5c and 5a correspond to shifts in the bioclimatic zonal development with a gradual replacement of parkland steppe and mixed southern taiga by boreal forest and by cold arid periglacial tundra steppe during the stadial sub stages mis 5d and 5b following the most intensive loess sedimentation during the early last glacial mis 4 a new cycle with warm and very cold climate variations characterises the mid last glacial interstadial interval mis 3 with most favourable surface stabilisation phases represented by cryogenically distorted parkland chernozem soils the iskitim loess palaeosol sequence characterised by intensive syndepositional pedogenic processes provides unique evidence of a dynamic climate change during the late quaternary in the continental north central asia and a linkage site for transcontinental eurasian correlations of high resolution loess records

optical dating of tsunami laid sands abstract the ages of some tsunami deposits can be determined by optical dating a key requirement being that the deposits are derived from sediment that was reworked and exposed to daylight by tidal currents waves wind or bioturbation during the last years before the tsunami measurements have been made using 1 4 ev infrared excitation of k feldspar grains separated from samples of prehistoric tsunami sand sheets and modern analogs of tsunami source sediments at four sites in washington state and british columbia source sands gave equivalent doses indicative of recent exposure to daylight tsunami sand at cultus bay washington yielded an optical age of 1285 95 yr calendric years before a d 1995 1 at 2 this age overlaps the range of from 1030 to 1100 yr determined through a combination of high precision radiocarbon dating and stratigraphic correlation tsunami sands at three sites near tofino and port alberni on vancouver island british columbia have optical ages of 260 20 325 25 and 335 45 yr historical records and radiocarbon dating show that the sand at each of the three sites is between 150 and 400 yr old these optical ages support the hypothesis that the vancouver island sands were deposited by a tsunami generated by a large earthquake on the cascadia subduction zone about 300 yr ago

optical dating studies of quaternary organic rich sediments from southwestern british columbia and northwestern washington state the suitability of optical dating using 1 4 ev infrared excitation for determining the time of deposition or compaction of organic rich sediments and peat is assessed with measurements on seven samples from six different lithostratigraphic units one is of zero age two have associated 14c ages three are known to have been deposited during an interglaciation and one is 1 ma old the samples yield satisfactory optical ages ranging from 0 to over 100 ka we conclude that the muir point formation southern vancouver island and the whidbey formation northwestern washington state were both deposited during 18o stage 5 as previously deduced from other evidence the age obtained from the 1 ma sample was significantly too low the optical dating method is simpler and more precise than thermoluminescence dating and is recommended for future work

loess paleosol cryogenic formation and structure near the northern limit of loess deposition east european plain russia abstract quaternary loess paleosol series and cryogenic phenomena within the east european plain russia are less studied near their northern limit than at their southern extents the multi disciplinary study of two loess paleosol cryogenic sections were carried out in the moscow and vladimir regions of central european russia not far from the glacial limits of the middle and late pleistocene generally loess deposition within these regions has undergone syn to post deposition processes as evident from the laminated character as well as post depositional soil moisture and temperature conditions that have commonly given rise to gleyzation and cryogenic deformations the middle pleistocene dnieper loess is calcareous here but the upper pleistocene loess has been leached of carbonates both upper and middle pleistocene paleosols have strong pedogenic features allowing their genesis to be determined whereas cryogenic deformations and other post depositional features allow for the more detailed interpretation of cold epoch processes given these loess characteristics the moscow and vladimir loess region may be considered as a specific facies of the east european loess area the proposed moscow vladimir loess region exhibits the complete sequence of stratigraphic units that are correlative with well known sequences along the southern part of the east european plain in the moscow vladimir region however several horizons exhibit well developed cryogenic phenomena that indicate permafrost conditions and sufficient moistening during most of the cold epochs cryomorphic and hydromorphic processes have a strong influence on the composition and structure of loess formation the salyn paleosol of the mikulino eemian interglacial time demonstrates strong clay illuviation as well as kamenka and inzhavino paleosols of the middle pleistocene age both of which developed under boreal to sub boreal climatic conditions in contrast the bryansk and romny interstadial paleosols have gleyic properties that suggest formation during incipient discontinuous permafrost conditions

abstract mesozoic stratigraphy of near shelf edge deposits southern mississippi adjacent state and federal waters abstract onshore southern mississippi and adjacent state and federal waters were part of a region where basinward shelf edge migration occurred during the jurassic this migration provided a wide range of environments of deposition and did not become stable until the late cretaceous when more widespread environments of deposition were prevalent jurassic sediments attain a thickness of more than 6 000 ft and consist of evaporites clastics and carbonates jurassic sedimentary rocks are thickest in viosca knoll block 117 which represents the basinward facies of these rocks and correlations are difficult in the norphlet and smackover formations a thin norphlet clastic section is present in mobile block 991 and mississippi sound block 57 and extends this facies of the norphlet farther to the west offshore than previously thought in viosca knoll block 117 haynesville sediments are isolated by a gilmer aged ramp whereas in mississippi sound block 57 a clean white quartzose sandstone extends the presence of the frisco city formation into state waters 20 mi southwest of the wiggins arch onshore west of the wiggins arch the haynesville is open marine carbonates cretaceous sediments are 10 000 ft thick and consist of carbonates clastics and anhydrites lower cretaceous lithologies are less diverse than jurassic lithologies because of stabilization of the shelf edge and are more easily correlated from onshore to offshore with clastic hosston rodessa and eutaw formations interfingering with carbonates along the shelf edge the selma tuscaloosa washita fredericksburg paluxy and mooringsport formations all maintain consistent lithologies geographically figure 1 index map of mesozoic shelf edge deposits end of record last page 583

middle upper pleistocene bio climatic and magnetic records of the northern black sea coastal area loess palaeosol sequences are widespread in the northern black sea coastal area unlike the quasi continuous loess palaeosol series in central asia and the loess plateau of china the incomplete geological record of loess palaeosol successions in europe provokes different stratigraphical interpretations for different sections despite a long history of investigation many uncertainties still remain in the geochronology of the regional stratigraphy in this study some of the most representative loess palaeosol sections of moldova the dniester republic southern ukraine and southern russia were examined a multidisciplinary approach was used to establish stratigraphical markers seven palaeosols pedocomplexes are distinguished within the brunhes chron in the loess palaeosol sequence in the studied area the position of the matuyama brunhes m b reversal is drawn at the base of the kolkotova palaeosol complex in the khadzimus section the jaramillo subchron was revealed at the base of the loess formation this magnetostratigraphic framework is confirmed by biostratigraphical data small mammals are valuable serving as very important evidence for long distance correlation paleopedological data combined with magnetic susceptibility profiles provide additional stratigraphic control for a loess palaeosol correlation the results allow us to conclude that the main paleoenvironmental changes occurred ca 1 ma ago when lagoon and alluvial sedimentation was replaced by increasing loess accumulaton during some intervals erosion or variation in the loess sedimentation rate at different sites are responsible for the variability of the loess palaeosol alternation the correlation of the loess palaeosol succession in the brunhes chron with marine oxygen isotope stages suggests that the beginning of the loess palaeosol formation of the middle pleistocene was forced by more pronounced long paleoclimatic cycles than are noticed prior to the m b reversal

complexities in eolian and marine interactions processes and eustatic controls on erg development abstract the interplay between eolian and marine realms includes process interactions cycles of transgression and regression and possible inland effects of marine coastal events process interactions are geologically common and most obvious where eolian and marine environments are adjacent these interactions include sediment exchange between the two environments the supply of marine ions to the erg for surface and near surface cementation and the control directly or indirectly of marine events on the sediment budget of an erg regression accompanied by erg progradation over marine deposits occurs with both onshore and offshore winds marine transgression of ergs varies from producing a planar marine scoured surface to a planar deflation surface that precedes the transgression to varying degrees of paleotopographic dune preservation and a variety of transitional facies the extent of paleotopographic dune preservation is largely a function of the energy level of the transgressing marine realm the rate of the transgression and potential for early dune cementation general correlations between ergs and global eustatic sea level and coastal onlap curves occur for coastal and near coastal cyclic erg sequences eustatic control of inland ergs exists to the extent that sea level controls in large measure the extent of the basin exposed to subaerial processes i e regional base level and probably to a lesser extent the sediment supply to the erg direct correlation of inland erg events to coastal onlap curves is dubious at present but an indirect relationship may exist

change in atmospheric mineral aerosols in response to climate last glacial period preindustrial modern and doubled carbon dioxide climates desert dust simulations generated by the national center for atmospheric research s community climate system model for the current climate are shown to be consistent with present day satellite and deposition data the response of the dust cycle to last glacial maximum preindustrial modern and doubled carbon dioxide climates is analyzed only natural non land use related dust sources are included in this simulation similar to some previous studies dust production mainly responds to changes in the source areas from vegetation changes not from winds or soil moisture changes alone this model simulates a 92 33 and 60 change in dust loading for the last glacial maximum preindustrial and doubled carbon dioxide climate respectively when impacts of carbon dioxide fertilization on vegetation are included in the model terrestrial sediment records from the last glacial maximum compiled here indicate a large underestimate of deposition in continental regions probably due to the lack of simulation of glaciogenic dust sources in order to include the glaciogenic dust sources as a first approximation we designate the location of these sources and infer the size of the sources using an inversion method that best matches the available data the inclusion of these inferred glaciogenic dust sources increases our dust flux in the last glacial maximum from 2 1 to 3 3 times current deposition

malacological sequence of weichselian mis 5 2 loess series from a profile in grodzisko dolne southern poland and its palaeogeographic significance abstract abundant and diverse molluscan assemblages have been identified in a loess site in grodzisko dolne the profile is located in south eastern poland within a loess belt covering the kolbuszowa plateau in the exposed sequence which is 9 m thick two loess covers underlain and divided by initial soil sequences have been distinguished numerous molluscan remnants were found throughout the entire profile the malacological analysis enabled four faunal assemblages to be distinguished pupilla fauna succinella fauna arianta fauna and mixed fauna their sequence in the vertical profile is indicative of environmental changes especially concerning climate and substrate humidity the occurrence of malacofauna within the loess and soil sequence which corresponds to the early glacial and early pleniglacial mis 5 and 4 is particularly interesting the presence of molluscan shells in loesses of this age has been noted in few sites in europe the faunal studies and analyses performed in the grodzisko dolne site indicate the major importance of this profile in the research of regional differences in weichselian loess covers in europe

ice wedges growth thaw transformation and palaeoenvironmental significance frost cracking and ice wedge growth are fundamental processes within the permafrost environment extensive areas of contemporary permafrost terrain are characterised by frost fissure polygons formed by repeated thermal contraction cracking of the ground the incremental growth of ice veins and wedges along the axes of contraction cracks contributes significantly to the volume of ground ice in near surface permafrost in areas beyond the present limit of permafrost the recognition of ice wedge pseudomorphs provides one of the few unambiguous indications of the former existence of permafrost conditions an understanding of the processes of ice wedge growth and thaw transformation is essential if contemporary ice wedges are to be used as analogues for pleistocene frost fissure structures in palaeoenvironmental reconstructions

the beginning of the ice age in europe and its major subdivisions abstract the time range of the quaternary is discussed in terms of the view that this period is essentially the one in the earth s history in which during certain intervals inland ice developed in the northern hemisphere this process first became evident about 2 3 ma bp since then the quaternary thus defined has witnessed many climatic variations although for practical reasons it is not feasible to assign the status of stage to each distinclty warm or cold phase climatic change is nevertheless the most appropriate basis for world wide correlation it seems possible to use both climatic change and other correlation parameters to arrive at a practicable subdivision of the quaternary period into stages before about 1 ma vegetational succession during interglacials in western europe differed from that seen in later times a possible cause for this divergence is discussed in the later part of the quaternary after about 1 ma two distinct types of warm temperate intervals occurred one associated with high sea levels and an oceanic climate the other showing lower sea levels and a cooler and more continental climate the difference between these two types is shown by comparison of the distribution of abies during these time intervals

discovery of a landscape wide drape of late glacial aeolian silt in the western northern calcareous alps austria first results and implications abstract aeolian deposits record palaeoenvironmental conditions and may coin soil properties whereas periglacial loess is extensively investigated for 200 years the study of the intramontane wind blown deposits of the alps has just stuttered along herein we describe a drape of polymictic siliciclastic silt interpreted as an aeolian deposit that veneers extensive areas in the western northern calcareous alps nca from kames terraces near valley floors up to last glacial nunataks the nca part of the eastern alps mountain range consist mainly of triassic carbonate rocks these are overlain by deposits of the last glacial maximum lgm and its deglacial paraglacial aftermath e g glacial tills fluvio lacustrine successions alluvial fans scree slopes and a regional drape of polymictic silt newly described herein the drape is typically a few decimeters in thickness and slightly modified by soil formation it consists mainly of well sorted silt of quartz feldspars phyllosilicates muscovite chlorite biotite amphiboles and rarely calcite or dolomite the drape is unrelated to the substrate it overlies carbonate bedrock and in lateral continuity abandoned deposystems such as colluvial slopes of redeposited till kames alluvial fans scree slopes and rock avalanche deposits the drape was spotted from near the present valley floors up to lgm nunataks over a vertical range of some 2000 m it is also present in catchments of the nca that were not overridden by far travelled ice streams and that lack metamorphic rock fragments two osl quartz ages of the drape from two distinct locations 18 77 1 55 ka 17 81 1 68 ka fall into the early alpine late glacial interval shortly after the collapse of pleniglacial ice streams this fits with geological and geomorphological evidence respectively that the drape should be of early late glacial age and that it accumulated during a specific interval of time in the nca localized minor deposition of aeolian dust is documented by other authors from plateaus deglaciated only during the late glacial to holocene no evidence however exists for another phase of similarly widespread aeolian deposition such as that which gave rise to the described regional drape of silt intense aeolian transport and deposition was probably a direct consequence of the liberation of huge amounts of unsorted sediment during deglacial ice collapse perhaps combined with climatic aridification this provides a hitherto unappreciated element of the deglacial to paraglacial phase intramontane dust storms because of its large extent and the availability to osl dating the aeolian drape provides an excellent geochronological marker level identified in terrestrial post glacial successions of the eastern alps because of its fine grained siliciclastic composition the drape gives rise to widespread development of atypical cambisols on carbonate bedrocks with comparatively high water storage capacity and nutrient supply

optical dating using inclusions within quartz grains a sequence of stranded beach dunes in the southeast of south australia which resulted from the advance and retreat of the sea over a tectonically rising land surface during the past 800 ka has been securely dated by geological means and successfully used to test thermoluminescence dating based on quartz we have now obtained a series of promising results from the same sequence with a test of optical dating on inclusions within the quartz grains the innovative aspect of the measurements is the use of infrared irradiation to stimulate emission from the inclusions rather than conventional stimulation of the quartz itself by light of shorter wavelength satisfactory ages were found for seven dunes covering the time span 0 400 ka

thermoluminescence dating of sediments abstract the potential for using the thermoluminescence behaviour of sediments for dating them was first recognized by soviet scientists g v morozov and v n shelkoplyas and for over a decade their tl dates obtained from a variety of sediments have appeared in the soviet literature since 1977 tl sediment dates have been published by six additional groups using a variety of methods in this review we describe the principles of tl dating the various methods used and contrast tl dating of sediments with the now well accepted tl dating of pottery we conclude that while tl dating has the potential to solve many sedimentary problems more fundamental research needs to be carried out before such dates should be accepted a set of criteria for acceptable dates is proposed

occurrence formation and micromorphology of gypsum in soils from the central german chernozem region occurrence of gypsum in soils from loess of the central german chernozem region indicates that local climatic conditions with low precipitation average 500 mm a 1 and a real evaporation between 450 and 460 mm do not allow leaching of weakly soluble gypsum from soils at a site close to the strip mine etzdorf gypsum is accumulated in the ck horizon of a haplic chernozem down to a depth of about 1 5 m its distribution being nonuniform calculated total gypsum in the haplic chernozem amounts from 10 20 t ha 1 the highest accumulation of gypsum obviously by solution transport and evaporation can be observed in a profile exposed to the air since about 1960 in this profile maximum so42 values however are not found on the surface of the outermost aggregates with whitish efflorescence but at 20 cm depth in the profile in a eutric podzoluvisol the precipitation of gypsum developed on living roots as well as in pores of former roots in a buried chernozem large euhedral gypsum crystals with a diameter of up to 1 5 cm were found gypsum crystals occur in different shapes and sizes such as euhedral lenticular rosette like and equigranular ones even soils having undergone leaching processes reveal unusual increases of so42 at 40 50 cm depth this may be an indicator of more recent so42 input due to atmospheric deposition since the beginning of industrialization it is supposed that gypsum is formed by the reaction of atmogenic sulfuric acid with different ca sources in the soil

likhvin interglacial polygenetic paleosol a reconstruction on the russian plain abstract one of the most important quaternary terrestrial climatic proxy records is the loess paleosol sequence found in the russian plain of eastern europe along the plain the likhvin interglacial corresponds to the two phase inzhavino polygenetic paleosol ipp known as an analog of the holsteinian interglacial the objectives of this study are 1 to present new information supporting the ipp genesis and its stratigraphic correlation in the central russian plain and 2 to evaluate soil zonation for the two phases of the ipp development for the first time geographic zonality and shifts of soil zones are described for the two phases of the ipp the older interglacial optimum phase of the ipp phase a features changes from north to south as does the modern day soil in the same geographical area although soil zones of the optimum are shifted slightly southward relative to present day soil zones albeluvisols reconstructed on the north of the study area develop into cambisols luvisols phaeozems in the central part of the area and into chernozems further southward it appears that climatic conditions during paleosol formation were more humid than at present the younger post optimal phase of the ipp phase b is identified as an accretionary humic regosol on the central russian plain but developed into chernozems southward the phase b soil zonation is simplified in comparison with present day one and tentatively corresponds to interstadial conditions therefore spatial changes in the ipp features indicate that zonal structure of environment developed along the russian plain at least as early as the middle pleistocene likhvin interglacial

new geoarcheological studies at the middle paleolithic sites of khotylevo i and betovo bryansk oblast russia some preliminary results abstract the paper presents and discusses the evidence obtained as a result of recent fieldwork at the middle paleolithic sites of khotylevo 1 and betovo in the upper desna river basin bryansk oblast of russia the stone industries of both sites are based on local tabular good quality flint and contain more khotylevo 1 or less betovo representative bifacial components as well as varying quantities of levallois products previously all the middle paleolithic assemblages of khotylevo 1 were thought to occur in a redeposited alluvial context dated by different authors to either early late or even late middle pleistocene the materials of betovo were thought mainly on typological grounds to postdate those of khotylevo 1 the new stratigraphic observations supplemented with the results of sedimentological analyses show that khotylevo 1 is a multilayered site with some cultural horizons displaying few or no signs of post depositional dislocation coupled with the results of paleomagnetic studies and a radiocarbon date this data seems to suggest that the formation of the deposits enclosing the known middle paleolithic assemblages at both sites might have taken place during the first half of the middle valdai megainterstadial mis 3

a review of tertiary climate changes in southern south america and the antarctic peninsula part 2 continental conditions abstract climate changes in southern south america and the antarctic peninsula during the tertiary show a strong correlation with ocean warming and cooling events which are in turn related to tectonic processes during periods of accelerated sea floor spreading and mid ocean ridge activity sea levels rose so that parts of the continents were flooded and forests were destroyed however this was balanced by the large scale release of co2 during volcanic outgassing and carbonate precipitation on the continental shelves which caused rising air temperatures and the poleward expansion of sub tropical and temperate forests cooling episodes generally caused an increase in the north south thermal gradient because of an equatorward shift in climate belts so that the westerly winds intensified and brought higher rainfall to the lower latitudes an increase in wind blown dust caused temperatures to drop further by reflecting sunlight back into space the rising andes range had a marked influence on climate patterns up to the middle miocene it was still low enough to allow summer rainfall to reach central and north central chile but after about 14 ma it rose rapidly and effectively blocked the spill over of moisture from the atlantic ocean and amazon basin at this time the cold humboldt current was also established which together with the andes helped to create the arid diagonal of southern south america stretching from the atacama desert to the dry steppes of patagonia this caused the withdrawal of subtropical forests to south central chile and the expansion of sclerophytic vegetation to central chile however at the same time it intercepted more rain from the northeast causing the effect of the south american monsoon to intensify in northwestern argentina and southern bolivia where forest communities presently occur in patagonia glaciation started as early as 10 5 ma but by 7 ma had become a prominent feature of the landscape and continued apparently uninterruptedly into the pleistocene the antarctic peninsula saw its first mountain glaciation between 45 and 41 ma with major ice sheet expansion commencing at about 34 ma isolated stands of nothofagus forests were still present in low lying areas suggesting that the glaciers were initially wet based but dry based glaciers were established at around 8 ma although temperatures rose briefly during the messinian pliocene transition causing sub antarctic flora to retreat to higher elevations of the transantarctic mountains the present cold polar conditions were finally established by about 3 ma

optical dating of paleosols bracketing the widespread rotoehu tephra north island new zealand abstract optical dating of the fine grained mineral fraction of paleosols developed on or within loess bracketing the widespread rotoehu tephra at two sites in central north island new zealand was undertaken using infrared excitation of potassium feldspars optical ages suggest that rotoehu tephra was deposited at ca 45 ka and support several previous age determinations our optical ages are also consistent with individual k ar ages from bracketing lava flows though inconsistent with the currently preferred age for the tephra 64 4 ka which is the weighted mean of them our data also suggests that the age of two other important time stratigraphic markers tihoi and tahuna tephras estimated to have been deposited at 46 and 43 ka respectively may have instead been formed between 25 and 35 ka in the light of this the chronology of other north island tephra beds older than 30 ka may have to be revised

pedostratigraphy and chronology of the late pleistocene for the extra glacial area in the central russian upland reference section aleksandrov quarry abstract new results on stratigraphy and chronology obtained on the basis of osl and 14c dating of paleosols sediments and cryogenic deformations in the aleksandrov quarry situated at the central russian upland are discussed due to the location of the site in a paleodepression the section presents various stages of soil formation cryogenesis and sedimentation starting from the mikulino interglacial to the middle last glacial time the studied sequence is well preserved and one of the most detailed soil sedimentary terrestrial archives within eastern europe it reflects climatic variations comprising the timespan from the marine isotopic stage mis 5e to mis 3 at the base of the paleodepression the pedogenetic stages are extraordinary detailed distinct paleosols are alternating with erosion accumulative stages forming the ryshkovo pedolitocomplex during the mikulino interglacial during the early valdai time two interstadial paleosols were developed and the middle valdai section comprises two main interstadial paleosols as well in general interstadial paleosols of the late valdai time are absent in the studied quarry for the first time the chronological boundaries of the mis 5e interglacial are recorded and thus the duration of soil formation could be determined from 12 to 15 thousand years furthermore stages of periglacial conditions during the early middle and late valdai time were dated the obtained ages form the base for a chronostratigraphic framework which was correlated with those of the loess paleosol archives of eastern central and western europe

dolomite silica stromatolites in miocene lacustrine deposits from the duero basin spain the role of organotemplates in the precipitation of dolomite this research provides an ancient analogue for biologically mediated dolomite precipitation in microbial mats and biofilms and describes the involvement of highly structured extracellular polymeric secretion eps templates in dolomite nucleation the structure of eps is shown to match the hexagonal trigonal lattice geometry of dolomite which favoured the epitaxial crystallization of dolomite on the organic substrate this structure of eps also matches the arrangement of silica nanospheres in opal which further accounts for the organically templated formation of opal enabling the non replacive co existence of dolomite and silica the study is focused on a 50 m thick dolomite succession that is exposed in central areas of the tertiary duero basin and was deposited in a mudflat saline lake sedimentary complex during the middle to late miocene 9 to 15 ma in the intermediate intervals of the succession poorly indurated dolomite beds pass gradually into silica beds on the basis of sedimentological compositional geochemical and petrographic data silica and dolomite beds have been interpreted as mineralized microbial mats the silica beds formed in marginal areas of the lake in response to intense evaporative concentrations this resulted in the rapid and early precipitation of opal silicification accounted for the exceptional preservation of the microbial mat structure including biofilms filamentous and coccoid microbes and eps extracellular polymeric secretions have a layered structure each layer being composed of fibres which are arranged in accordance with a reticular pattern with frequent intersection angles at 120 and 60 therefore the structure of eps matches the lattice geometry of dolomite and the arrangement of silica nanospheres in opal additionally eps binds different elements with preference to si and mg the concurrence of suitable composition and surface lattice morphologies in the eps favoured the crystallization of dolomite on the substrate in some cases dolomite nucleation took place epicellularly on coccoid micro organisms which gave way to spheroid crystals organic surfaces enable the inorganic mineral precipitation by lowering the free energy barrier to nucleation most of the microbial mats probably developed on the lake floor under sub aqueous conditions where the decomposition of organic matter took place the subsequent formation of openly packed dolomite crystals with inter related si enriched fibrils throughout is evidence for the pre existence of fibrillar structures in the mats miocene dolomite crystals are poorly ordered and non stoichiometric with a slight ca excess up to 5 which is indicative of the low diagenetic potential the microbial dolomite has towards a more ordered and stoichiometric structure this confirms that microbial imprints can be preserved in the geological record and validates their use as biosignatures

oxygen 17 excesses of the central namib gypcretes spatial distribution abstract we present here sulfate oxygen isotopic data 72 samples with both 18o and 17o systematically collected from the central namib desert surface soils from two shore inland west east transects exhibit a gradual increase in the sulfate oxygen 17 excess 17o 17o 0 52 18o until at ca 70 km inland where no continuous gypcrete deposit is observed further east inland the oxygen isotopic compositions for water soluble sulfates extracted from soils and gypcretes range from 8 3 to 13 3 and 0 06 to 1 11 for 18o and 17o respectively the lateral pattern is similar to what has been seen in the cold deserts of the antarctic dry valleys however unlike the dry valleys no discernible correlation is found between 18o and 17o or between the depth of soil horizon and 17o in the namib possible explanations include a relatively smaller component of dimethylsulfide dms derived sulfate in the total gypsum deposits and or more active surface processes e g flooding and leaching in the central namib desert than in the antarctic cold deserts although current state of knowledge is insufficient to delineate quantitatively the sulfate contributions from different sources and reactions the measurement of sulfate 17o does identify an unmistakable atmospheric sulfate component and provides additional independent information regarding sources and reactions

pleistocene paleosols in the loess and loess like sediments of the central part of the russian plain abstract the central part of the russian plain is a key region because of the complex interrelation of the pleistocene glacials and interglacials fossil soils are not continuous in this region due to cryoturbation erosion and other later processes morphological chemical and micromorphological features of the upper eemian and middle treenian pleistocene paleosols were investigated in the sections of loess and loess like sediments on the plateau on the right bank of the river oka the eemian soils studied have a humic a1 horizon with typical biogenic multiordered microstructure and illuvial b horizon the soil morphology is similar to that of the modern grey forest soils which are widespread in this region the middle and upper pleistocene paleosols are separated by the moscow warta loess but sometimes the eemian fossil soil lies directly on the podzolic layer of the treenian soil the investigated treenian paleosol exposed in the loess has no humic horizon and is very similar to the modern spodosol indicating colder forest conditions in the region during this interglacial

textural features of holocene perennial saline lake deposits of the taoudenni agorgott basin northern mali abstract the holocene salt lake deposits of the taoudenni agorgott basin northern mali mainly consist of sediments with a high glauberite na2ca so4 2 content the remainder of the deposits largely consists of salt beds with a bloedite na2mg so4 2 4h2o thenardite na2so4 or halite nacl composition a petrographical study of the deposits demonstrates that they formed in a perennial lake that experienced a gradual decrease in water depth textural features of the glauberite dominated deposits are found to be related to water depth through the control that this factor exerts on the sensitivity of the lake to changes in water supply and to short term variations in evaporation rates in this way layering due to variations in glauberite content and crystal size is inferred to be typical of deposits that formed in shallow water whereas unstratified deposits are the product of high lake level stages halite textures are found to be indicative of the place within the water column where crystal growth occurred along the lake bottom or higher which is mainly determined by water depth and partly by evaporation rates the oldest halite beds are largely unaltered cumulate deposits whereas the youngest layers developed exclusively through bottom growth the basal part of one thick halite bed at a level between these two groups of halite layers developed by an alternation of both types of growth in response to variations in evaporation rates variations in mineralogical composition between and within the salt beds that formed during the earliest periods with a higher salinity up to the first stage with halite formation record a change in lake water chemistry with time but they are in one instance also determined by an early diagenetic mineral transformation

optical dating studies of postglacial aeolian deposits from the south central interior of british columbia canada abstract tests of the validity of optical dating of the fine grained 4 11 m component of aeolian deposits from six sites in south central british columbia using 1 4 ev infrared excitation of potassium feldspars were made making use of known age tephra beds at one site on the western side of the fraser valley samples bracketing the mazama 7 5 7 6 ka cal yrs and bridge river tephras 2 3 ka cal yrs yielded optical ages in accordance with the known ages when a correction for thermal transfer was used the same method was applied to aeolian deposits on the fraser plateau known to have been deposited between 14 and 2 3 ka cal yrs the ages obtained from five samples from four separate exposures spanning 10 km varied from 30 to 94 ka clearly indicating that this sediment was not exposed to sufficient sunlight prior to burial as a result of a detailed investigation it is suggested that the reason is that some grains had been transported over short distances

age dating and the orbital theory of the ice ages development of a high resolution 0 to 300 000 year chronostratigraphy using the concept of orbital tuning a continuous high resolution deep sea chronostratigraphy has been developed spanning the last 300 000 yr the chronology is developed using a stacked oxygen isotope stratigraphy and four different orbital tuning approaches each of which is based upon a different assumption concerning the response of the orbital signal recorded in the data each approach yields a separate chronology the error measured by the standard deviation about the average of these four results which represents the best chronology has an average magnitude of only 2500 yr this small value indicates that the chronology produced is insensitive to the specific orbital tuning technique used excellent convergence between chronologies developed using each of five different paleoclimatological indicators from a single core is also obtained the resultant chronology is also insensitive to the specific indicator used the error associated with each tuning approach is estimated independently and propagated through to the average result the resulting error estimate is independent of that associated with the degree of convergence and has an average magnitude of 3500 yr in excellent agreement with the 2500 yr estimate transfer of the final chronology to the stacked record leads to an estimated error of 1500 yr thus the final chronology has an average error of 5000 yr