dating the quaternary progress in luminescence dating of sediments abstract luminescence dating comprises a collection of numerical age techniques that are among the most significant chronological tools currently used in quaternary research this paper briefly reviews the key historical developments in luminescence dating from its roots in thermoluminescence dating of heated minerals to the development of optical dating methods for sunlight exposed sediments we describe the principles and practicalities of the various techniques commonly used in luminescence dating including multiple aliquot single aliquot and single grain procedures and we discuss some of the latest approaches to recognising and minimising potential errors in age estimation e g by means of component analysis and dose distribution methods in optical dating the overview also introduces the other papers in this special issue of quaternary science reviews which address a selection of important issues in basic research technique development and application of luminescence dating to critical questions in the geological and archaeological sciences illustrated with examples from around the world and the last million years of earth history

influence of cone morphology on dykes stromboli italy abstract the island of stromboli represents the emerged part of a 2 6 km high composite volcano elongated in a ne direction over the period 100 13 ka bp the morphological evolution of the volcano was characterised by a series of summit caldera collapses between major building phases from 13 ka bp onward a series of large lateral collapses occurred northwestwards in one sector of the cone the results of the field study of the total 94 dyke population is discussed in this paper they show that during the last 100 ka the majority of dykes were injected with a nnegssw to ene wsw strike along a ne sw weakness zone crossing the volcano summit this is interpreted as a volcanic rift the geometry of which is controlled by regional tectonic stresses dykes injected prior to 13 ka bp at lower altitudes are generally steeper than those injected at higher elevations after 13 ka bp dykes were injected along the ne sw weakness zone and parallel and close to the margins of the earliest sector collapse at dips of 20 80 inclined towards the collapse depression i suggest that this is linked to unbuttressing of the collapse depression or to seaward gravity instability of the depression infill deposits extensive emplacement of long dykes along the ne sw weakness zone occurred only when the volcano regained a conical shape some of the dykes emplaced close to the original surface of the cone bent to assume a dip direction parallel to the local slope i propose that this local change of dyke geometry can be explained by the direct influence of the free surface of the cone leading to a rotation of the least principal stress which assumes an orientation perpendicular to the slope

holocene hydrological changes in se iran a key region between indian summer monsoon and mediterranean winter precipitation zones as revealed from a lacustrine sequence from lake hamoun abstract core sediments from the dry lake bed of hamoun were subdivided into 3 main sedimentary units using a multi proxy approach e g petrography grain size analysis total organic matter and caco 3 determination to reconstruct the palaeoenvironment of the sistan basin se iran as a transition zone between the monsoon summer precipitation zone of south asia and the mediterranean winter precipitation zone of the iranian plateau during the holocene data revealed that during the late glacial to early holocene the lake and its catchment area western hindu kush were under a more prominent influence of the indian ocean monsoon and formed a moist and productive environment with less wind action as shown by the provenance of high organic matter lacustrine sediments together with the lack of an aeolian fraction due to southward migration of the inter tropical convergence zone during the mid holocene arid climate manifested by an interplay of seasonal aeolian and fluvial deposition became dominant these conditions were due to reinforcement of subtropical anticyclones on the iranian plateau the presence of green to brownish green moderate organic matter lacustrine sediments showed that during the late holocene mediterranean type winter precipitation dominated in the area during the initial part of this period the shahr i sukhteh civilization was close to the lake the environment was relatively similar with that of today some palaeostorms can also be detected during this time interval shown by occurrences of high aeolian inputs in the basin

flow patterns of magma in dikes makhtesh ramon israel directions of magma flow were measured in a system of radial dikes in makhtesh ramon israel the flow directions were determined from field observations of segments fingers grooves and groove molds of the dikes the study indicates that the mean axis of magma flow is subhorizontal toward the north in agreement with the direction of divergence of the radial dike system two modes of flow were observed 1 regular bedding parallel flow in the well stratified rock units and 2 irregular meandering flow in the massive rock units it is suggested that corrugated dike walls in well stratified host rocks cause magma channelization and random or self generated restrictions in massive host rocks cause the apparent meanders furthermore the major lithologic boundaries in the host units strongly affect segmentation of the dikes

a record of late quaternary continental weathering in the sediment of the caspian sea evidence from u th sr isotopes trace element and palynological data abstract this study presents combined mineralogical chemical isotopic 87sr 86sr and u th disequilibria series and palynological analyses on bulk sediments and on distinct mineral phases carbonates and clays from a 10 m long core drilled in the southern caspian sea and containing a late pleistocene and early holocene record the data allowed identifying 1 the main variations in sedimentation 2 the processes causing these variations 3 the modification of erosion vs weathering and 4 the influence of climatic and or caspian sea level changes in the region since the late pleistocene the chemical and mineralogical results allowed the division of the sedimentary sequence into three main units and a transition zone the lower unit unit u1 primarily consists of silicate and carbonate rich detritus sedimentation characteristics including observation of detritus in secular equilibrium are relatively constant within this unit and reflect mechanical erosion in a cold climate unit u1 probably corresponds to a glacial period when the vegetation cover was sparse and wind and river transport of pollen were strong subsequently global increase in temperatures has greatly modified the sedimentation in the caspian sea south basin biogenic sedimentation is higher in units u2 and u3 and detrital inputs varied from unit u1 variations in detrital input are likely to be caused by decreasing aeolian contribution and by relative changes in river volumes and origins the study of the bulk sediments clays and carbonates reflects an increase in chemical weathering since about 10 14c ka bp ago base of unit u2 in line with an increase in the vegetation cover our results suggest an evolution of continental weathering conditions in the catchment area of the caspian sea from dominantly mechanical physical erosion during the cold period to a continuous increase in weathering since the lateglacial period as climate improved which illustrates the strong relation between climate vegetation cover and weathering processes this paper also highlights how the u th disequilibrium series proxy combined with other geochemical and palynological studies could be a useful tool to record and constrain the modification of weathering regime in response to climatic and environmental changes at regional scale

micromorphology of the lower pleistocene loess in the iranian loess plateau and its paleoclimatic implications abstract the loess deposits in iran are a valuable archive of regional paleoclimatic and paleoenvironmental information extensive sedimentological and chronological studies have been carried out on the middle to upper pleistocene loess successions during the past decades but there is an absence of comparable research in the older loess deposits recently a 19 m thick loess paleosol sequence was discovered in the central iranian loess plateau ilp which was paleomagnetically dated to 2 4 1 8 ma and thus represents by far the oldest loess known in northern iran here we present the results of a detailed micromorphological investigation of these lower pleistocene loess paleosol sequences red sequence from the ilp our main findings are as follows 1 the agh band red sequence deposits are an extremely thick soil complex comprising paleosols in different stages of development 2 the micromorphological index of soil development miseca suggests that the moderately and well developed paleosols in the red sequence formed in an environment with mean annual precipitation ranging from around 450 to 650 mm respectively and 3 miseca suggests that the red sequence formed under a semi arid to sub humid climate and thus under wetter and more favorable conditions than the overlying late pleistocene loess and modern soils

contractional tectonics and magma paths in volcanoes abstract this study aims to contribute a possible explanation for magma migration within volcanoes located in contractional tectonic settings based on field data and physically scaled experiments the data demonstrate the occurrence of large stratovolcanoes in areas of coeval reverse faulting in spite of the widely accepted idea that volcanism can develop only in extensional transcurrent tectonic settings the experiments simulate the propagation of deformation from substrate reverse faults with different attitudes and locations into volcanoes the substrate fault splits into two main shear zones within the volcano a shallow dipping one with reverse motion propagates towards the lower volcano flank and a steeper dipping one with normal motion propagates upwards in plan view the reverse fault zone is arcuate and convex outwards whereas the normal fault zone is rectilinear structural field surveys at volcanoes located in contractional settings show similar features the plio quaternary trohunco and los cardos centinela volcanic complexes argentina lie above plio quaternary reverse faults the late pleistocene holocene el reventador volcano ecuador is also located in a coeval contractional tectonic belt these volcanoes show curvilinear reverse faults along one flank and rectilinear extensional fracture zones across the crater area consistent with the experiments these data consistently suggest that magma migrates along the substrate reverse fault and is channelled along the normal fault zone across the volcano

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

clay mineralogy and geochemistry of the lower pleistocene loess in the iranian loess plateau agh band section and implications for its provenance and paleoclimate change abstract the clay mineralogy and geochemistry of loess is sensitive to variations in sediment source area transport processes and weathering regime over time and thus careful study of them can provide some insight into past climate variability the well known loess paleosol sequences upper pleistocene loess upl on the iranian loess plateau ilp are generally underlain by the red deposits consisting of reddish clay to silt sized sediments of wind blown origin lower pleistocene loess lpl study and analyzing of this oldest brown and reddish brown loess has a specific role in paleoclimate reconstruction but no previous study of the clay mineralogical and geochemical characteristics of them has been performed to date therefore total fet and free iron fed concentrations and fed fet ratios x ray diffraction as well as geochemical analysis were carried out on a section near the agh band village in northeastern province golestan geochemical analysis revealed the same provenance of all deposits in lpl and similarity of them by upl x ray diffraction detected the kaolinite smectite chlorite illite vermiculite mica vermiculite and mica smectite minerals in the red deposits the results demonstrated that detrital input is the main source of kaolinite chlorite and illite while pedogenic formation during the early pleistocene could be the dominant cause of smectite and vermiculite occurrences in the lpl the presence of smectite and vermiculite is in accordance with the xeric and udic soil moisture regime in upl respectively as such it can be concluded that the climate at the time of agh band lpl formation varied from semi arid to sub humid climate and wetter and more favorable conditions than the overlying late pleistocene loess and modern soils these results are confirmed by al2o3 na2o na2o k2o mgo tio2 and fed fet ratios

geochronology of middle and upper pleistocene loess sections in hungary abstract the application of both thermoluminescence and infrared stimulated luminescence dating to the extensively studied classical hungarian loess paleosol sequences from basaharc mende and paks provides a reliable chronological framework and climatostratigraphic reconstruction for the last interglacial glacial cycle based on this combined luminescence dating study a new chronology is proposed for the young loess in hungary luminescence dating suggests that the loess below the mf2 horizon formed during the penultimate glaciation the mf1 horizon probably formed during an interstade within oxygen isotope stage 3 for the youngest loess overlying mf1 a very high accumulation rate was determined large time gaps occur above mf2 and mf1 indicating that most of the record of the last glaciation is missing in the standard sections at basaharc mende and paks either large discontinuities or a very low accumulation rate occurred in all three type sections during the soil forming periods high resolution studies of climatic proxies using this combined luminescence dating approach provide a reliable chronological framework for loess and loess derivatives of the last glacial cycle in hungary although a precise and complete chronostratigraphic reconstruction cannot be achieved from the incomplete records found at these sites

aeolian dust dynamics in central asia during the pleistocene driven by the long term migration seasonality and permanency of the asiatic polar front loess paleosol sequences preserve detailed archives of climate change reflecting the dynamics of aeolian dust sedimentation and the paleodust content of the atmosphere the detailed investigation of particle size distributions psds of windblown sediments is an increasingly used approach to assess the paleorecord of aeolian dust dynamics the central asian loess belt offers the potential to reconstruct pleistocene atmospheric circulation patterns along an adjacent west east transect within interior eurasia through granulometric studies in this study we present the aeolian dust record of the loess sequence at remisowka se kazakhstan which reflects a detailed signal of glacial interglacial climate and atmospheric dynamics in central asia on the basis of radiocarbon and amino acid geochronologic data long term semicontinuous trends in the aeolian dust record of the last glacial cycle are observed and interpreted to reveal their paleoclimate signal in consideration of the modern synoptical atmospheric circulation patterns and aeolian dust transport in central asia it is likely that the observed trends reflect the long term migration seasonal duration and permanency of the polar front during the late pleistocene previously published models which focused on the reciprocal glacial interglacial influence of the zonal westerlies and the asiatic high on the aeolian dust transport in central asia were overly simplified and should be modified to include the major influence of the asiatic polar front as the polar front activity is intimately connected with the development and position of the interhemispherically active high level planetary frontal zone hpfz the presented data give insight to long term aeolian dust dynamics and climate variability of interior eurasia which are linked with interhemispheric climates

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

palaeoclimatic record from a loess soil profile in northeastern bulgaria ii correlation with global climatic events during the pleistocene summary magnetic susceptibility x variations and the behaviour of the ratio of susceptibility to saturation magnetization x j s along the loess palaeosol section at koriten ne bulgaria are used to deduce climatic changes during the pleistocene in southeastern europe a good correlation of susceptibility variations with the astronomically tuned oxygen isotope record from odp site 677 enables us to propose a more precise dating of the upper part of the bulgarian loess complex close correspondence between susceptibility and d18o records demonstrates the global significance of the palaeoclimatic signal recorded although diverences in relative amplitudes of x and x j s and d18o create diyculties in making quantitative estimates of the climatic humidity in the past the role of local factors avecting the palaeoclimatic mineral magnetic record deduced from the profile studied in bulgaria is discussed

subaerial submarine evidence of structures feeding magma to stromboli volcano italy and relations with edifice flank failure and creep abstract structural field data including parameters of 109 sheets strike mostly n10 55 e average dip angle mostly 70 90 average thickness two peaks at 1 2 m and 4 2 m and of 14 eruptive fissures and vents as well as bathymetric and numerical data suggest that stromboli experienced the development of a volcanic rift zone across the cone summit with a tendency to widen towards the lower submarine flanks during the last 100 ka inside this rift zone intrusive sheets mostly strike ne and become more abundant more steeply dipping and thicker on approaching the rift axis this rift persistence reflects the edifice s state of stress with a nw se horizontal least principal stress on the magma intrusion paths after 13 ka ago sheets mainly intruded with a horseshoe shaped geometry in plan view along the boundaries of the northwestern unstable volcano flank where four main lateral collapses occurred during the last 13 ka they also intruded with a ne strike across the volcano summit and the northeastern volcano flank the horseshoe shaped geometry is influenced by the lateral creep of the volcano flank which provides space for intrusion along the transtensional boundaries of the unstable sector where thinner sheets were emplaced when the collapse depression was filled up by new deposits ne striking thicker dykes emplaced across the northwestern volcano flank indicating a rapid re establishment of regional tectonic forces across the cone unbuttressing due to the present sciara del fuoco depression and ongoing flank creeping can account for intrusions also inside the sciara del fuoco the latter in 2007

sefidrud delta and quaternary evolution of the southern caspian lowland iran abstract the southern caspian sea lowland in iran forms a thick sedimentary prism produced by interactions of marine deltaic and fluvial processes during the late neogene and quaternary deltaic and fluvial deposits have been developed mainly by the sefidrud which is the largest river of the country its drainage area ca 61 600 km 2 includes nearly the entire alborz mountain range and forms deep valleys gorges and a large delta at the southern coast of the caspian sea the sefidrud delta is so large that it covers one third of the large guilan mazanderan plain both from an aerial and volumetric point of view consequently the drainage network of the sefidrud represents the quaternary evolution of northern iran and can be used to test the hypothesized evolution of the region the sefidrud delta has been investigated using many short and long cores satellite images and lithofacies maps and the results show that this delta complex 1680 km 3 consists of a covered lower part and exposed upper deltaic sequences the lower and upper parts of the complex were formed during the early pleistocene and late pleistocene respectively the upper exposed alluvial and deltaic sediments represent a total progradation of approximately 50 km forming three separate delta subsequences d1 3 of which the last one d3 is the modern sefidrud delta the modern delta is a wave dominated blanket like sediment cover ca 30 m thick and 1550 km 2 produced during the last three millennia it was formed by 30 km progradation of six juxtaposed lobes each lobe corresponds to a long term sea level fluctuation of the caspian sea the active lobe ca 50 km 2 has been forming since 1550 ad late pleistocene deltaic sequences d1 3 particularly the modern one d3 were produced by relatively fast deposition due to high volume sediment load of the sefidrud it is suggested that they were produced after the opening of the rudbar gorge by river capture that in turn six times enlarged the drainage area previous deltaic progradation and marine transgressions were relatively slow and the development of the whole lowland at the southern caspian sea lasted ca 1 1 2 ma bp

chronostratigraphy of loess deposits in northeast iran little information is available on the paleoclimate evolution of northeast iran relating to global cold and warm stages the loess paleosol sequences from southern mashhad and kalat e naderi areas were studied to determine the landscape evolution and to set up the first chronological framework for the pleistocene deposits in northeast iran the loess deposits in these areas are less thick up to 12 m and have a more patchy distribution than in the caspian lowland of northern iran infrared stimulated luminescence irsl dating of loess or loess derivatives from the robat e khakestari tappeh salam and deh gheybi sections a and b from southern mashhad as well as kalat e naderi sections a and b in kalat e naderi area provides a more reliable chronological framework for climate and environmental changes taken place over for the time period including the penultimate and last interglacial glacial cycles the robat e khakestari section the kalat e naderi sections a and b and to some extent the tappeh salam section include loess paleosol sequences which are chronologically in excellent agreement with the loess record of the caspian lowland in northern iran the deh gheybi sections a and b include loess like sediments and fluvial deposits that make their interpretation difficult loess accumulated during mis 2 at the robat e khakestari section and at the kalat e naderi sections a and b suggesting a more windy and arid last glacial maximum lgm in northeast iran paleosols correlating most likely with mis 5 were covered by fluvial sediments at the kalat e naderi section a the absence of loess deposits correlating to mis 3 and mis 4 at the robat e khakestari section is very likely to have been caused by fluvial processes and water erosion

the agh band loess palaeosol sequence a terrestrial archive for climatic shifts during the last and penultimate glacial interglacial cycles in a semiarid region in northern iran abstract the northern iranian loess profiles host important information on quaternary climate and palaeoenvironmental changes in the region they build an important link between the eurasian loess belt and european and central asian archives due to a climatic gradient with decreasing precipitation from the west to the east and from the south to the north loess palaeosol sequences formed synchronously under different climatic conditions can be studied over short distance in the iranian caspian lowland the agh band profile is located in the so called iranian loess plateau a semi arid region with 200 350 mm annual precipitation the loess deposits at agh band reach a thickness of 60 m an about 50 m thick step profile was prepared and the litho pedostratigraphy was investigated samples for laser diffractometry grain size measurements were taken every 2 cm the magnetic susceptibility was measured in 4 cm intervals and the caco3 content in 8 cm intervals to establish a chronological framework a pirir290 luminescence dating approach was applied to the 4 11 m polymineral fraction the results show that the agh band profile yields a climate archive reaching from mis 7 to mis 2 several chronological hiatuses of some 10 ka show that periods of intense loess accumulation were interrupted by phases of only minor loess sedimentation and or erosion the agh band profile is subdivided by several shifts in grain size distribution the coarsening and fining up trends correlate with increasing and decreasing wind velocity respectively in the central part of the agh band loess sequence a weakly developed palaeosol is preserved which was developed at around 80 ka furthermore the loess deposits formed from about 100 ka to 60 ka ago show banded structures a pedocomplex including two well developed palaeosols consisting of bw y horizons and a cb horizon as well as intercalated loess can be found in the lower part of the sequence also evidenced by the increased values of magnetic susceptibility the corresponding luminescence age estimates indicate that the palaeosols represent a period of increased humidity and landscape stability during late mis 7 and mis 6 hence in the agh band loess various changes in the palaeo sedimentary system triggered by changes in climate can be observed this yields important information on the sensitive response of sedimentary systems and landscapes within semi arid regions to shifts in moisture and possibly temperature

the geochemistry of loess asian and north american deposits compared abstract loess is widely distributed over asia and north america and constitutes one of the most important surficial deposits that serve as terrestrial records of the quaternary the oldest pleistocene loess in china is likely 2 6 ma thus spanning much or all of the pleistocene in north america most loess is no older than the penultimate glacial period with the exception of alaska where the record may go back to 3 0 ma on both continents loess deposits date primarily to glacial periods and interglacial or interstadial periods are represented by paleosols both glacial and non glacial sources of silts that comprise the bulk of loess deposits are found on both continents although loess has been considered to be representative of the average upper continental crust there are regionally distinctive compositions of loess in both asia and north america loess deposits in asia from yakutia tajikistan and china have compositionally distinct major element compositions due to varying abundances of silicate minerals carbonate minerals and clay minerals in north america loess in the mississippi river valley the great plains and alaska are also distinguishable with regard to major element composition that reflects highly diverse source sediments trace element geochemistry sc th zr and the rare earth elements also shows regional diversity of loess bodies in both asia and north america on both continents most loess bodies show significant contributions from later cycle altered sedimentary rocks as opposed to direct derivation from igneous rocks further some loess bodies have detectable contributions from mafic igneous rocks as well as major contributions from average upper crustal felsic rocks intercalated paleosols in loess sections show geochemical compositions that differ significantly from the underlying loess parent materials ratios of soluble to insoluble elements show depletions in paleosols due to chemical weathering losses of calcite dolomite plagioclase mica apatite and smectite in asia and north america the last interglacial paleosol is more weathered than equivalent modern soils which could be due either to a climate that was warmer and more humid a longer period of pedogenesis or both in asia early pleistocene loess and paleosols are both more weathered than those from the middle and late pleistocene forming prior to a mid pleistocene aridification of asia from uplift of the tibetan plateau understanding the geochemistry of loess and paleosols can tell us much about past atmospheric circulation past temperature and moisture regimes and even tectonic processes

quartz osl dating of loess deposits since the late glacial in the southeast of caspian sea abstract here we present loess deposits since the late glacial dated by osl technique in the southeast of the caspian sea bordering continents of asia and europe chronology of holocene loess deposits are rarely reported in eastern europe and western asia especially for their spacious mid latitude adjacent region between balkans to the west and pamirs to the east in this study an osl based chronology was developed for loess deposits in northern iranian plateau based on the ybd loess profile which locates close to center of hilly iranian loess plateau in the southeast of the caspian sea and on the northern slope of the alborz mountains the osl characteristics and their reliability were investigated on coarse grained quartz 63 90 m of the profile a preheat plateau test and dose recovery test of which reveal that the lower preheat is suitable for loess equivalent dose determination in the area in addition the sar osl is an appropriate methodology for dating loess deposited since the late glacial in situ with preservation of a complete record of loess accumulation since the late glacial ybd section contains a potentially valuable paleoclimatic record for caspian region and hence the vast transitional region between asia and europe

late quaternary loess accumulation at the rudak section in uzbekistan central asia chronology and palaeoclimate implications abstract many studies have been carried out to understand the nature of the loess formation and its palaeoenvironmental significance in different parts of eurasia especially europe and china however in spite of its key position our knowledge about the loess deposits at the core of the eurasian loess belt in central asia is still limited particularly in terms of absolute dating this study presents a new luminescence chronology of a loess palaeosol sequence rudak section in the vicinity of the gissar range uzbekistan using both quartz optically stimulated luminescence dating and polymineral post ir irsl dating techniques the dating results suggested a loess accumulation history over the past 180 kyr at rudak section characterized by a great depositional hiatus during the entire last glacial period likely owing to too harsh climate conditions for favouring dust accretion and loess preservation in the piedmont areas of central asia hence contrasting with the traditional concept of continuous quasi continuous deposition of loess the direct stratigraphical correlation might be problematic for climatic interpretation of loess palaeosol sequence in this area furthermore magnetic susceptibility of rudak section demonstrated the moisture peaks in phase with ice volume minima over the glacial and interglacial cycles indicating moisture variation in the westerlies dominated central asia was broadly consistent with that in monsoonal asia on orbital timescales but nearly contrasting picture with each other on the suborbital timescales at least through the holocene epoch the westerlies dominated central asia has generally experienced a dry first half and a wet second half of the holocene which has likely been driven by solar insolation gradients between mid latitudes and high latitudes as well as the melt water flux

towards a revised chronostratigraphy of loess in austria with respect to key sections in the czech republic and in hungary abstract the stratigraphic ages of some well known and characteristic paleosols in austrian and hungarian loess sections have been questioned by several workers since the mid 1970s in particular a generally accepted correlation of austrian and hungarian loess stratigraphies with the well established czech loess stratigraphy has not been put forward this paper presents 41 new thermoluminescence tl dates and the first results from amino acid chronology of key sections in these areas the results are in agreement and suggest a new interregional correlation of loess paleosol sequences for loess older than the last interglacial quartz and feldspar inclusions yield more reliable tl ages than the polymineralic fine grain fraction

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

late pleistocene and holocene sea level change and coastal paleoenvironment evolution along the iranian caspian shore the authors published by elsevier b v this is an open access article under the cc by nc nd license http creativecommons org licenses by nc nd 4 0

luminescence dating of loessic sediments from the loess plateau china loess palaeosol sequences from the loess plateau in china were investigated by combined infrared optically stimulated luminescence irsl and thermoluminescence tl dating techniques in order to study the luminescence properties of the loessic sediments and to provide a direct chronological link for correlation and position of the last interglacial soil in central asia and the loess plateau in china sensitivity changes were found for all samples through artificial bleaching of the samples the greatest sensitivity changes of up to 50 were found for very old loess samples designated to be older than the matu yama brunhes magnetic boundary and hence older than 788 000 1 800 years the upper dating limit as investigated by the very old loess samples ranges from 250 000 to 300 000 years if the tl additive dose method is applied the chronological position of the last interglacial soil s1 at the section near lanzhou indicates luminescence age estimates ranging from 82 000 to 75 000 years for the marine isotope stage 5 to 4 transition however the loess from below s1 yielded luminescence age estimates between 153 200 14 200 and 110 100 20 100 years for tl and irsl additive dose methods respectively thus a direct correlation between the s1 and the first intercalated pedocomplex pc1 in central asia is most likely

a simple method for the determination of the dilation direction of intrusive sheets abstract it is shown that the occurrence of offsets of various orientations along the contacts of an intrusive sheet permits the rapid establishment of the net dilation direction for the sheet the application of the method to some dykes on arran shows that oblique opening of a fissure was sometimes accompanied by a vertical component of opening the technique provides a tool for the analysis of patterns of crustal displacement associated with dyke intrusion

processes of loess lithogenesis during the pleistocene holocene southeast siberia regional studies have been conducted on loess deposits cohesive sands and loess like neoformations in the technogenesis zones in southeast siberia cryogenic processes and distribution of geological formations have been ascribed to influential factors of loess lithogenesis the processes of loess formation are active in the present environment

magnetostratigraphy and environmental magnetism in a sedimentary sequence of miramar buenos aires argentina abstract a sedimentary sequence called fogones de la costa located at 38 17 35 s 57 50 50 w on the coastal cliffs south of miramar city was studied from geological paleomagnetic and rock magnetic viewpoints the stratigraphic column shows normal and reverse polarity records associated with chrons and subchrons of magnetopolarity the younger sediments were assigned to the brunhes polarity chron 1 9 ma on the basis of these data the sequence should span from the lower pleistocene to the holocene and may be correlated although partially with the geological formations of san andres miramar and arroyo seco described in coastal cliffs north of miramar the model of behavior of concentration parameters ms and mr is in agreement with that determined in other loess sections studied in northern buenos aires province the values of the concentration of magnetic parameters decrease with increasing pedogenesis and weathering of the original material loess and loess like this is a behavioral feature independent of the carrier agent wind or water the medium silt fraction is dominant over the other grain sizes in that fraction the amount of magnetic minerals increases significantly conversely the layers corresponding to paleochannels and paleolagoons show a decrease of magnetic minerals the medium silt fraction also decreases and the very fine silts and clays increase

ice age as a trigger of active quaternary volcanism and tectonism abstract the stress accumulation within the crust caused by the surface mass redistribution associated with the glaciation deglaciation cycle during the quaternary was numerically evaluated in order to examine the relationship between active quaternary volcanism and tectonism in island arc areas and ice age the vertical gradient of horizontal stress difference in the lithosphere for a meltwater of 130 m in equivalent sea level reaches a maximum value of 0 8 mpa km which is corresponding to the equivalent buoyancy of about 100 kg m3 for magma filled cracks for an earth model with a lithospheric layer of 20 30 km thickness and with a viscosity greater than 1023 pa s the changes in stress difference during the stages of deglaciation of 10 000 years amount to 13 mpa for both the top and bottom of the thin lithosphere thus the additional stress difference within the crust may be effective for island arc areas with thin lithospheric thickness we therefore speculate that the stress accumulation associated with ice age may be an important trigger and or accelerator on the active quaternary volcanism and tectonism for the areas along the circum pacific

optical dating of holocene paleosol development and climate changes in the yili basin arid central asia optically stimulated luminescence osl dating was conducted on the k feldspar and quartz fractions of a holocene loess paleosol sequence in the yili basin in the core area of arid central asia a

the loess sequence from remisowka northern boundary of the tien shan mountains kazakhstan part i luminescence dating abstract similar to the chinese loess the loess deposits surrounding the high mountain regions of central asia play an important role in understanding the climate and environmental change during the pleistocene in eurasia despite their thickness and widespread distribution the loess deposits in southeast kazakhstan have so far not been investigated in detail the remisowka loess palaeosol sequence is located in the vicinity of the north tien shan mountains at an altitude of 1070 m above sea level in the profile under study nine loess layers were distinguished intercalated by eight pedocomplexes and so indicating a similar cyclicity like the loess palaeosol sequences in central asia and china at the remisowka section 12 loess samples were taken to set up a more reliable chronological model for the section using a luminescence dating approach polymineral fine grains were investigated by infrared optically stimulated luminescence applying the multiple aliquot additive dose protocol preliminary fading experiments were carried out for one sample taken from the uppermost loess layer while the results of the uppermost layer are in agreement with geological age estimates and indicate a correlation to the late glacial age underestimation is very likely for the samples below the first weak palaeosol no significant age increase with depth was recognised the reason for this age underestimation is not yet fully understood but could be related to anomalous fading further methodological approaches are necessary as well as a combination of different chronometric techniques for improvement of the results

multiple sector collapses at stromboli volcano italy how they work this paper demonstrates that four large sector collapses have affected the nw flank of the stromboli volcano in the past 13 ka alternating with growth phases in order to contribute to the evaluation of the critical conditions which trigger lateral collapses a reconstruction of the geometry of each collapse of the volcano edifice in the four stages that preceded the relative collapse events is also presented and a computation of the landslide volume this reconstruction is based on new field data plotted in three dimensions prior to the initial 13 ka collapse the volcano was 1125 100 m high above sea level the collapse had a volume of 2 23 0 87 km3 whereas the pre collapse volcano volume was 218 8 7 7 km3 the next edifice that failed was 900 70 m high a s l the collapse volume was 1 0 54 km3 with a precollapse volcano volume of 201 4 5 4 km3 the edifice then grew to 1000 60 m a s l the third collapse had a volume of 1 08 0 39 km3 and occurred within a volcano with a volume of 209 1 4 6 km3 this was followed by a new growth phase followed by the last collapse with a volume of 0 73 0 22 km3 the volcano volume was about the same as the present one the present active crater zone is at 780 m a s l in the first three collapses sliding surfaces cut the main magma conduit in the last collapse the upper scarp coincided with the conduit location dyking along a main ne trending weakness zone across the volcano summit exerted a lateral force for collapse inception the decrease of the landslide volumes with the age and the concentric scarps of the four collapses suggest that the younger sliding planes tended to become more superficial and to decrease the areal extent this is interpreted as due to a successively weaker eruptive products from dominantly lavas to dominantly pyroclastics and b the feedback effects between collapses and dykes that injected along the lateral segments of the first collapse slide plane

east european river runoff and black sea and caspian sea level changes as simulated within the paleoclimate modeling intercomparison project during the last late pleistocene and post glacial epochs the caspian sea fluctuated between regressive and transgressive stages the black sea experienced fluctuations too but their amplitude was smaller because they were mainly controlled by the world ocean due to water exchange through the bosporus strait in the water budget equation the change in storage over a time period is balanced by the sum of the inflows and outflows that occur during the time period they can be calculated from atmospheric general circulation models gcms a modeling initiative the palaeoclimate modelling intercomparison project pmip could help to resolve this question the pmip has focused on two slices of the past the mid holocene 6 ka calendar years before present bp and the last cold event of the late quaternary 21 ka calendar years bp the pmip gcm simulations indicate that changes in level are primarily influenced by changes of river runoff ocean precipitation and evaporation together play a minor role at 21 ka bp the estimated level lowering was 50 and 200 m for the caspian sea and black sea respectively this lends credit to the idea of the connection between deep regressive states of caspian sea and black sea and mature stages of late quaternary glacial cooling drying planetary events

late pleistocene dust dynamics and pedogenesis in southern eurasia detailed insights from the loess profile toshan ne iran abstract in southern eurasia recurrent phases of aridization dust source extension and enhanced aeolian sedimentation alternated with moister intervals promoting reduced deflation areas and dust accumulation in the context of late pleistocene climate changes weathering and soil forming intensity in this greater region are hence mainly governed by fluctuations in the balance between dust supply and moisture availability among the hitherto known sections the toshan loess soil sequence lps represents a key site due to the quality of the record and the multitude of available data giving detailed insights into the timing and magnitude of dust accumulation and soil formation of the region to elucidate these dynamics for much of the past 130 000 years bulk mineralogical and geochemical data are presented supplemented by a high resolution magnetic susceptibility record and by the results of a detailed micromorphological study of loess at toshan the last interglacial luvisol phaeozem like mis 5e and the early glacial interstadial steppic palaeosols mis 5 c and a are characterized by gradually increasing grain size and decreasing degrees in decomposition of micaceous and mafic minerals pronounced feldspar weathering is detected in the last interglacial and modern soils only which formed under reduced or absent dust deposition on penultimate and last glacial loess respectively postsedimentary the overall pedosedimentary conditions correspond to large scale trends of increasing drought dust accumulation and wind strength in southern eurasia in relation to decreasing moisture availability towards the early pleniglacial mis 4 causing soil formation under ongoing dust deposition synsedimentary similar intervals of synsedimentary soil formation are recorded during the interglacial interstadial stadial transitions of the early glacial and during pleniglacial mis 4 to 2 interstadials the latter are marked by gradual increases in magnetic susceptibility colour and decreasing texture conversely silicate weathering could not be detected suggesting that grain size fluctuations are a primary feature thus windy and arid pleniglacial conditions in southern eurasia were interrupted by intermittent phases of synsedimentary soil formation in response to short lived and relatively moist interstadials although the interrelation of these incipient soils throughout southern eurasia is afflicted with considerable restrictions the oscillatory pattern of the toshan lps bears great similarity with millennial scale oscillations recorded in limnic archives of western asia

structural and sedimentary features in the tyrrhenian margin off campania southern italy abstract the utilization of multichannel seismic reflection profiles permits the identification of the generally e w trending miocene orogenic and plio quaternary post orogenic features of apennine nw se and anti apennine ne sw trends in the campanian margin the former features are constituted by carbonate and or allochthonous sheets which were thrust mainly towards the north and northeast during the miocene tectogenetic phases the latter are represented by extensional structures which affected the orogenic features during plio quaternary times the anti apennine tectonic trend is responsible for the recent late pliocene quaternary and remarkable block faulting differential subsidence of the southern margin as well as for its present morphology the ragged and disconnected pattern of the allochthonous units over the present day slope and their accumulation underneath the shelf area suggest that they are the result of gravitational gliding tectonics gravity cores and 3 5 khz subbottom profiles indicate that the salerno trough and capri basin areas are characterized by a particular neotectonic mobility this is proved by the thick and coarse grained sediment accumulation from steep relief produced by block faulting this faulting created uplift belts serving as sediment source

paleosols derived from loess and loess like sediments in the basin of persepolis southern iran abstract in the basin of persepolis late quaternary basin fills consist of loess loess like sediments and fine or coarse textured alluvium the loess and its derivatives are divided by various paleosols which consist of well developed fbw t horizons weakly developed fbwc and fbwgc horizons as well as fah horizons strongly developed fbtk horizons occur in stony alluvial fan deposits or superimpose residual loams of carbonate bedrock mixed with loess the different types of paleosols result from various degrees of soil development as evidenced by micromorphological features such as the birefringence fabrics and less clearly by pedochemical properties based on the stratigraphy and different degrees of soil development various phases of soil formation and sediment deposition can be distinguished infrared optically stimulated luminescence irsl thermoluminescence tl and radiocarbon dating methods are consistent with the stratigraphy and yielded except for one sample age estimates of less than about 30 ka the strongly developed fbw t and fbtk horizons reflect soil forming periods prior to the last glacial maximum lgm and probably during marine isotope stage 5 mis 5 with climatic conditions comparable to the present day the upper loess deposits likely formed under considerably cooler and drier climatic conditions during the lgm however poor bleaching of sediments prior to final deposition as indicated by greater tl than irsl dates suggest fluvial reworking of these loesses the weakly developed fah fbwc and fbwgc horizons may indicate interstadial periods of mis 3 and short phases of climate amelioration during the early holocene the formation of the modern soil probably did not start before 7 9 ka

the late pleistocene holocene history of the caspian sea abstract repeated fluctuations of the caspian sea are correlated with climate fluctuations with transgressions associated with climatic warming and regressions characteristic of cooler periods during the late pleistocene and holocene transgressions are associated with the early khvalynian 32 24 ka and late khvalynian 16 8 ka corresponding to the bryansk interstaidal and final deglaciation respectively regressions occured during the yenotavian event 24 17 ka corresponding to the last glacial maximum valdai and from 8 ka until the present corresponding to the waning of the holocene climatic optimum in the region variations in meltwater supply appear to be the primary factor controlling the caspian sea levels throughout the late quaternary

major changes in volcano behaviour after a sector collapse insights from stromboli italy in recent years increasing numbers of volcanoes are being recognized as having undergone large sector collapses how far such events can change the succeeding behaviour of the volcano is poorly known despite the importance for natural hazards and economic applications by analysing the last 100 kyr geological history of stromboli italy which has involved multiple collapses this paper illuminates the feedback effect between sector collapse and magma upwelling and emplacement the collapsed zone of stromboli is episodically unbuttressed draining magma preferentially with formation of eruptive centres in the collapse amphitheatre and dyking along the collapse shoulders after a collapse there were no further linear eruptions across the cone on opposing middle lower slopes but these occurred again after rebuilding of the cone the time averaged eruption rate increased immediately before the first collapse and remained higher during the succeeding period of frequent collapses

location and orientation of eruptive fissures and feederdykes at mount etna influence of gravitational and regional tectonic stress regimes abstract lava extrusion from fissures on the flanks of the etna volcano is a common feature of recent activity as evidenced by the eruptions of 1971 1981 1983 and 1985 and was of similar importance during prehistoric times we propose here a model within which the location and orientations of the large majority of historic eruptive fissures on etna s flanks together with their feeder dykes are explained within the framework of a gravitational stress regime stress orientations within this regime are controlled largely by the gross morphology of the volcano but are significantly modified by local topographic anomalies we propose that the gravitational stress regime largely supercedes an earlier developed regional tectonic stress regime which still operates in the sub volcanic basement and may remain the dominant control of eruptive fissure and feeder dyke disposition at lower altitudes on the flanks the proposed model is supported by 1 detailed examination of fissure locations and orientations and the relationship between fissure azimuths and topography 2 precise horizontal distance measurement and vertical ground deformation studies of a recent eruption and 3 qualitative physical modelling experiments in which coloured water is injected into solidified gelatine solutions representing variously shaped volcanic constructs a cautious approach is advocated when extrapolating trends of spatially limited fissure segments for the purpose of locating potential sites of magma ascent and implications of the model for hazard analysis are outlined

biomarkers in modern and buried soils of semi desert and forest ecosystems of northern iran abstract in northern iran mean annual precipitation and vegetation vary significantly over short distance from a semi desert to a forest biome these ecosystems likely responded differently on past climate changes we here aim at i testing the applicability of biomarkers leave derived n alkanes their stable carbon isotope composition and c and n stable isotopes of soil organic matter in loess derived soils to identify and differentiate past ecosystems and ii elucidating the variability of these biomarkers in palaeosols we sampled modern topsoils and palaeosol horizons within an ecological gradient covering a range in mean annual precipitation from 200 to 750 mm from the kopet dag semi desert to the hyrcanian forest on the footslopes of the alborz mountains c org n 13 c org 15 n and n alkanes and their compound specific 13 c were analyzed to characterize organic matter composition and sources in modern soils a systematic increase in c org and n was observed with precipitation the 15 n decreased from about 6 to 4 pointing to systematically more degraded organic matter in semi desert soils the leave wax specific ratio of nc 31 nc 33 nc 27 nc 29 n alkanes was 1 for semi desert soils and 13 c org showed no systematic trend in this gradient in loess and palaeosol profiles contents of c org n and n alkanes dropped about a factor 10 compared to modern soils the n alkane ratio and 15 n ratios remained on comparable levels as did the compound specific 13 c in n alkanes however bulk 13 c org was altered from about 27 in modern soil to 23 in loess palaeosols systematically higher c org and n values were observed in palaeo topsoils compared to loess and subsoil stable c isotopes varied rather unsystematically within loess palaeosol sequences while 15 n revealed trends within palaeosols however in contrasting directions with palaesol depth the temporal average n alkane ratio for all palaeosol horizons of one site systematically followed the modern precipitation gradient indicating that in all periods of soil formation a climatic gradient developed

cyanobacterial diversity and toxicity of biocrusts from the caspian lowland loess deposits north iran abstract biocrusts and adjacent sediments were collected from the so called loess plateau of northern iran and the loess deposits on the foothills of alborz mountains the mineralogical and granulometric analyses characterized sediments as quartz rich clayey or sandy silts cyanobacterial diversity colony morphology and grain stabilization were studied by light and scanning electron microscopy which showed glue like layers of cyanobacterial eps and dense networks of filamentous cyanobacteria immobilizing finer and bigger grains respectively amorphous tuft and globular cyanobacterial colony structures were also detected 15 cyanobacterial genera were identified in the biocrust samples including microcoleus vaginatus as the common species in all samples aphanocapsa aphanothece calothrix chroococcus chroococcidiopsis cyanosarcina hassallia homeothrix nostoc oculatella schizothrix scytonema tolypothrix and trichocoleus two biocrust samples showed traces of toxicity in a protein phosphatase inhibition assay targeting microcystins and similarly acting compounds the artemia salina assay revealed an elevated toxic response in one sample

reconstruction of the eruptive activity on the ne sector of stromboli volcano timing of flank eruptions since 15 ka a multidisciplinary geological and compositional investigation allowed us to reconstruct the occurrence of flank eruptions on the lower ne flank of stromboli volcano since 15 ka the oldest flank eruption recognised is roisa which occurred at 15 ka during the vancori period and has transitional compositional characteristics between the vancori and neostromboli phases roisa was followed by the san vincenzo eruption that took place at 12 ka during the early stage of neostromboli period the eruptive fissure of san vincenzo gave rise to a large scoria cone located below the village of stromboli and generated a lava flow most of which lies below sea level most of the flank eruptions outside the barren sciara del fuoco occurred in a short time between 9 and 7 ka during the neostromboli period when six eruptive events produced scoria cones spatter ramparts and lava flows the neostromboli products belong to a potassic series ks and cluster in two differently evolved groups after an eruptive pause of 5 000 years the most recent flank eruption involving the ne sector of the island occurred during the recent stromboli period with the formation of the large highly k calc alkaline lava flow field named san bartolo the trend of eruptive fissures since 15 ka ranges from n30 e to n55 e and corresponds to the magma intrusions radiating from the main feeding system of the volcano

palaeoclimatic record from a loess soil profile in northeastern bulgaria i rock magnetic properties summary a detailed record of mineral magnetic properties of a loess palaeosol profile comprising seven loess horizons six interbedded palaeosols and recent soil at the top in ne bulgaria is analysed a strong contrast between the soil and loess susceptibilities as well as other concentration dependent hysteresis parameters is present similar to the well documented magnetic characteristics of the chinese loess hus han 1992 maher thompson 1992 heller evans 1995 hunt et al 1995 the magnetic enhancement of the palaeosol units is caused by very fine grained pedogenic magnetite with superparamagnetic behaviour thermomagnetic analyses on bulk material suggest magnetite and maghemite as the main ferrimagnetic carriers in both soil and loess horizons their relative proportions are shown to reflect diverent palaeoclimatic conditions chernozem soils which include recent soil s 0 and first and second palaeosols s 1 and s 2 developed under steppe vegetation show a high degree of low temperature oxidation of the pedogenic magnetite to maghemite this material is characterized by coercive force h c showing even higher values than those of the parent loess material the older palaeosols s 4 to s 6 were formed during more humid climatic conditions and therefore probably developed as forest types rock magnetic data suggest the existence here of only partly oxidized magnetite grains the behaviour of the thermomagnetic curves characterized by a kink at 200 c may be due to either a release of internal stress built up as a result of partial low temperature oxidation or interactions between two phases

marker horizons in the loesses of the carpathian basin abstract two tephra horizons are known in the middle and upper pleistocene loesses of the carpathian basin the older bag tephra has been described from numerous loess outcrops in hungary whereas the younger paks tephra has been described only from the brickyard of paks in southern hungary the most characteristic heavy minerals in these horizons are various clinopyroxenes occurring in different proportions the clinopyroxenes of the bag tephra are extremely rich in ca and al while the volcanic glass is rich in k indicating high k andesitic or shoshonitic volcanism based on comparative geochemical analyses the most likely origin of the bag tephra is the roman or the campanian volcanic fields in italy geochemical investigation of the paks tephra is in progress and preliminary results suggest the same source for this younger tephra in contrast to the tephra horizons the correlation of the numerous paleosols in some hungarian loess sections and their paleoenvironmental interpretation is possible only if they are based on very detailed micromorphological studies the age determination of the loesses containing the paleosols directly by thermoluminescence tl and infrared stimulated luminescence irsl and indirectly by 14 c based isotope work should provide a reliable basis for the identification of soil forming periods in different parts of the carpathian basin

stable isotope geochemistry of pedogenic carbonates in loess derived soils of northeastern iran paleoenvironmental implications and correlation across eurasia despite the occurrence of pedogenic carbonates in loess paleosol sequences of northern and northeastern iran there is no information about stable isotope geochemistry of pedogenic carbonates in these regions this paper presents the first stable isotope data on pedogenic carbonates in loess derived soils of northeastern iran southern eurasian loess belt carbon and oxygen stable isotope values of pedogenic carbonates in different landforms were measured using mass spectrometry based on climatic data there is no possibility for soil leaching and pedogenic carbonate formation under the present arid conditions stable oxygen and carbon isotopic data suggest two separate periods of carbonate formation these periods are characterized by either lower or higher temperatures during post glacial than today and paleoecological conditions dominated by c3 and c4 plants respectively hemispheric correlation of loess deposits based on isotopic data of pedogenic carbonates shows a strong positive correlation for the post glacial carbonates nodules of northeastern iran and european russia this suggests a similar mechanism of carbonate formation and also the impact of westerlies in these regions we present the first quantitative isotopic data for paleoenvironment of northeastern iran however more quantitative investigations about the holocene and the last interglacial paleoenvironments of northeastern iran are needed

micromorphology and development of loess derived surface and buried soils along a precipitation gradient in northern iran abstract the northern footslopes of the alborz mountains and an extensive hill area in eastern golestan province are covered by thick 70 m loess deposits divided by different types of interstadial and interglacials paleosols the area shows a precipitation gradient of about 800 mm over 80 km north south along this gradient eight pedons of modern soils and six paleosols were selected in order to investigate the types of modern and past soil forming processes and to compare the degree of soil development of surface and buried soils the soils were described and sampled using standard sedimentological pedological laboratory analysis the soil ph and calcium carbonate contents show a decreasing trend with precipitation while soil organic carbon clay content and cation exchange capacity increase with rainfall the silt content however shows a decreasing trend with rainfall clay mineralogy of parental loess is illite chlorite smectite kaolinite from north to south the relative proportion of smectite in soil horizons increases reaching almost dominance in regions with typic xeric soil moisture regime smr 600 mm of rainfall in the areas with udic smr vermiculite increases and sometimes dominates micromorphology provides evidence for the formation of bt horizons and intensified decalcification and increase of clay mobilisation as indicated by b fabrics with increasing rainfall soils within the xeric and udic smrs are either alfisols or mollisols both showing clay illuviation features whereas clay mobilisation is very limited in the arid part of the area the paleosols show differential weathering degrees indicated by trends of increasing carbonate depletion clay mobilisation and clay enrichment with assumed paleo precipitation pedogenesis micromorphological properties and clay minerals in the last interglacial paleosols suggest similar climate controlled trends to those reflected in the modern soils

investigating soil magnetic properties with pedogenic variation along a precipitation gradient in loess derived soils of the golestan province northern iran abstract in the golestan province in northern iran extensive loess deposits and widespread loess derived soils crop out while a strong precipitation gradient 200 700 mm per year from north to south is characteristic temperature differences are negligible 17 18 c per year recently many studies on loess derived palaeosols and modern soils from this region were published however in these publications only limited information on the magnetic properties of loess and loess derived soils is given nor the potential of these properties to be applied as proxies for palaeoclimate reconstruction in order to study soil magnetic properties along the precipitation gradient in the golestan province six pedons of modern soils were selected the physicochemical properties the clay mineralogy and magnetic parameters of soil samples were analysed susceptibility measurements 20 2 130 77 10 8 m3kg 1 arm susceptibility values 0 00489 0 068 m3kg 1 irm values 0 0027 0 0105 am2kg 1 and hysteresis measurements provide significant evidences for an increase of the content of fine grained ferromagnetic minerals with increasing mean annual precipitation simultaneously the amount of sp sized particles increase magnetite maghemite and hematite are the major magnetic minerals in the studied samples whereby magnetite seems to be dominant in the soils of the loess plateau of northern iran by presenting data from this region of the northern iran for the first time another example is provided for the application of magnetic properties as proxies for the reconstruction of the paleoclimate the results are compared to data of the chinese loess plateau the russian steppe and loessic soils from the midwestern united state with similar relations of pedogenic susceptibility and map

grain size distribution of pleistocene loess deposits in northern iran and its palaeoclimatic implications abstract the loess deposits in northern iran are located in a key region connected to the european and central asian loess belts however the lack of previous detailed sedimentological and palaeoclimatic studies of the pleistocene loess in the region limits our understanding of the nature of ancient aeolian processes and loess history in the mid latitudes of euro asia as a whole here we present the results of grain size analyses of the pleistocene loess from the so called iranian loess plateau ilp in northern iran our results reveal that the grain size distribution of the deposits is characterized by trimodal and bimodal distributions comprising a dominant well sorted coarse dust component ca 7 75 m a small poorly sorted fine dust component ca 2 7 m and a minor pedogenic clay component

correlation of loess paleosol sequences in east and central asia with se central europe towards a continental quaternary pedostratigraphy and paleoclimatic history abstract as recent small climatic fluctuations on a 102 103 year time scale can be correlated worldwide and represent a decline of mean annual temperature of only 1 c major climatic changes on at least a 105 year scale glacial interglacial cycles and probably a 104 year scale the approximate length of an interglacial must be of similar ages throughout the temperate climatic belt of the northern hemisphere this concept allows continental pedostratigraphical correlations detailed knowledge of the genesis of paleosols is needed to establish loess paleosol stratigraphies that can be used for paleoclimatic reconstruction most paleosols however are truncated and largely recalcified from overlying loess micromorphological studies allow primary and secondary carbonates to be distinguished and provide unequivocal evidence of clay illuviation this enables the recognition of typical loess weathered loess and the recognition of different genetic soil horizons such as cb bc ah bw and bt horizons for the brunhes epoch the sequence at karamaydan tadjikistan is more detailed than the corresponding section in luochuan china and even more than in se central europe except for the last glaciation the very good correlation with the deep sea oxygen isotope record which includes the development of an accurate astronomical time scale allows a detailed chronostratigraphical subdivision of the loess paleosol sequence in karamaydan which therefore should be regarded as a key sequence for reconstructing the climatic history of the brunhes epoch this implies that the loess paleosol sequences in se central europe are less complete than thought earlier pedocomplexes in karamaydan correspond with single paleosols in se central europe e g the f6 paleosol in stari slankamen correlates with pedocomplexes pk vi and v at karamaydan which were formed over a period of about 140 ka although pedogenesis was interrupted several times by loess deposition the f6 soil is therefore an example of a welded paleosol as are the f5 the f4 and the f2 paleosols in se central europe for most of the matuyama epoch the central and lower parts of the sequence at chashmanigar show more pronounced paleosols than the equivalent parts at luochuan in se central europe only at stari slankamen are three strongly developed though truncated paleosols f9 f11 above neogene sediments mineralogical investigations of the silt and clay subfractions show that there is little difference in the type and amount of pedogenic clay mineral formation between the holocene soils and the paleosols of the brunhes epoch at karamaydan and of the matuyama epoch at chashmanigar this suggests that the interglacial climates represented by the b or bt horizons of the buried paleosols of late middle and early pleistocene age were similar to that of the holocene

climatic interpretation of loess paleosol sequences at mobarakabad and aghband northern iran abstract loess accumulation and paleosol formation are important quaternary geoarchives in northern iran two loess paleosol sequences at mobarakabad and aghband were examined using soil morphology and micromorphology mineralogy magnetic susceptibility ms free fe oxides and calcium carbonate equivalent the loess paleosol sequences provide a record of changes in paleo rainfall in the northern iran micromorphological and ms differences between the loess and paleosols in the sections reflect changes in climate the different behaviors of magnetic susceptibility between aghband and mobarakabad loess are mainly produced by their different pedogenic environments topography and climatic conditions as a result the ms at the mobarakabad section is much higher than at aghband paleoecological reconstructions coupled with magnetic depletion in paleosols at mobarakabad suggest a wetter climate dominating during the formation of the paleosols

evidence of a dyke sheet intrusion at stromboli volcano inferred through continuous tilt a tiltmeter installed in the northern sector of the island of stromboli aeolian archipelago tyrrhenian sea recorded a co seismic offset at the time of the main shock ml 3 7 of the 7 november 1994 swarm located 5 km north of the island during the three months following this event a transient tilt anomaly which was interpreted as due to a lateral intrusion and modelled through a dyke sheet dislocation was recorded the tilt data were used in an analytical inversion based on a propagating tensile source with length and width increasing in time the final result is consistent with the tectonic and structural framework of the volcano area

mechanical models for correlation of ring fracture eruptions at pantelleria strait of sicily with glacial sea level drawdown recent k ar dating of eruptions at pantelleria a peralkaline volcanic island in the strait of sicily shows a correlation between eruption of pantellerite lavas from caldera ring fractures and low stands of sea level as determined from 18o stratigraphy post caldera pantellerite lavas associated with an 114 ky old caldera erupted along the ring fracture zone during a major low stand of sea level at about 67 ka the most recent episode of lava flow emplacement began about 20 ky ago during the last glacial maximum magma vented along the ring fault of a 45 ky old caldera from fractures radial to the caldera and along faults formed by intracaldera trapdoor uplift two mechanical models based on elasticity theory are presented to explain the correlation of post caldera ring fracture eruptions at pantelleria with lowering of sea level a simple analysis of a bending circular plate of thickness t r and radius r representing the magma chamber roof block shows that tensile stress is concentrated by a factor of 0 75r 2 t 2 at the lower perimeter of the plate when sea level drops stress changes may be even greater ift r is effectively less than the stratigraphic thickness due to layering of rocks in the roof block calculated stress changes due to a 100 m drawdown of sea level are similar in magnitude to stresses associated with dike propagation more realistic model geometries including different chamber shapes a conical volcanic edifice and sea level drawdown beyond the surface projection of the magma chamber were tested using the boundary element method lowering sea level generates a horizontal tensile stress above the chamber even when sea water is removed outboard of the magma chamber for some chamber geometries the magnitude of the tensile stress maximum is greater than the 1 mpa pressure of the 100 m of removed water and is of the right order of magnitude for dike propagation dikes initiated by the change of the stress field may originate and propagate along fractures inboard of the chamber margin the magnitudes of tensile maxima along the top of the chamber decrease as original sea level is moved outboard of the chamber margin and as the chamber thickness decreases when the depth to the top of the magma chamber reaches a critical value dependent on chamber geometry the propagation of dikes to the surface is inhibited

landslide preconditions and collapse of the san francisco mountain composite volcano arizona into cold debris avalanches in late pleistocene abstract large composite volcanoes can collapse into debris avalanches even if alteration is absent and an eruption is not in progress or imminent at san francisco mountain arizona a large valley that penetrates the core of the volcano is at the apex of a large fan of bouldery volcaniclastic deposits a 115 m thick layer sampled in a borehole that penetrates the fan is composed of dense and unaltered lithic clasts in proportions similar to the bulk composition of the andesitic volcano pumiceous clasts are absent within this layer a 20 m thick deposit consists mostly of clasts from two dacite extrusions that predate the valley a flank flow and an inferred summit dome this dacite rich deposit may be from a debris avalanche that originated by failure of the summit and northeast flank of the volcano in a repose interval during the last eruptive stage which was about 0 43 to 0 22 ma preconditions for slope failure include top loaded by massive lava flows and summit dome and cone inflated by intrusion

active sand seas and the formation of desert loess abstract loess is a widespread eolian deposit dominated by coarse silt and very fine sand quartz grains 20 80 m that serve as an important archive of information on quaternary climate change despite the intensive research during the past century on desert loess formation its origin remains poorly understood and is still a fundamental problem in sedimentology the ongoing debate is focused on the first stage of loess formation the production of coarse silt quartz grains although laboratory experiments indicate the potential of dunes with their abundant quartz sand grains as a primary source for generating coarse silt grains this concept has been generally rejected because field based evidence of abrasion from sand grains eolian abrasion is scarce here we have adopted a global view of the sand sea loess association and examine in detail several well known late pleistocene loess regions in different subtropical deserts africa the middle east and arabia this analysis demonstrates that all these loess regions are located downwind of adjacent sand seas together with evidence of mineralogical similarity between the loess and the sand dunes and the contemporaneous deposition of the loess and movement of the dunes these observations suggest that sand seas are an important source for desert loess because there is only limited silt storage in sand dunes we postulate that the silt grains comprising most of the loess are not reworked from the dunes but are generated probably through active eolian abrasion of the sand grains under past climates characterized by intensified winds as a result the role of sand dunes and eolian abrasion in the formation of desert loess may be more important than previously thought

mapping clay content for subsurface drainage in the nile delta abstract drain envelope requirements for large scale subsurface drainage projects are often estimated based on the surface area with clay percentages less than a given threshold value contouring clay percentage data can be done by computer using spatial interpolation methods cross validation was used to evaluate the precision of estimation for clay percentage using five interpolation techniques closest neighbor moving average weighted moving average kriging and cokriging for a study area of 33 500 ha in the nile delta the clay content was measured at 485 sites cokriging used the correlation between clay percentage and saturated hydraulic conductivity which had been measured at 3488 sites the lowest mean absolute difference mad between observed and interpolated clay percentage values was obtained for cokriging 12 01 mad values were very close to that of cokriging in the case of moving average 12 13 weighted moving average 12 23 and kriging 12 21 whereas for the closest neighbor method a mad value of 16 44 was obtained surface areas under 30 and 40 percent clay were over estimated for the closest neighbor method and under estimated for the moving average method surface areas and contour maps based on weighted moving average kriging and cokriging were very similar use of moving average resulted in a loss of precision due to the smoothing effect

middle and late pleistocene loess sequences at batajnica vojvodina serbia abstract loess sequences in the vojvodina region northern serbia reveal a continuous record of paleoclimatic variations during the middle and late pleistocene the most detailed stratigraphic information comes from remarkable exposures on the cliffs of the right danube bank from vukovar to belgrade the batajnica loess section has been recognized as one of the most complete middle and late pleistocene records in this region a more than 40 m thick loess paleosol succession represents environmental transition from relative thin loess layers and rubified soils in lower part of profile to thick loess and fossil chernozems characterizing the last three glacial interglacial cycles the proposed stratigraphic model is based on a detailed magnetic susceptibility ms record which is related to the deep sea isotope stratigraphy and on correlation with other eurasian loess records using the distinct ms pattern of selected loess paleosol couplets this new stratigraphic model suggests serious revision of previous chronological interpretations ms as function of depth shows a well known pattern of low values in loess and high values in paleosols indicating strong enhancement of magnetic minerals during soil formation with the exception of the recent soil v s0 which is strongly contaminated by archaeological artifacts the third paleosol v s3 reveals the highest values in ms and a very distinct double peak the rock magnetic signal at batajnica resembles the typical pattern of the enviromagnetic records determined from other eurasian loess sites the paleopedological interpretations rubification index values and rock magnetic record at batajnica yield valuable data for the reconstruction of paleoclimatic fluctuations for the last 5 glacial interglacial cycles at least moreover the record provides an important link between the classical central european loess sites and the central asian and chinese loess provinces

late pleistocene loess palaeosol sequences in the vojvodina region north serbia late pleistocene loess palaeosol sequences are widespread in the vojvodina region with thicknesses reaching a maximum of about 20 m our investigations include more than 40 of these loess sections geochronology of the last glacial loess palaeosol sequences based on lumines cence dating and amino acid racemisation provides correlations between upper pleistocene loess palaeosol sediments in vojvodina and comparable deposits at other european localities sedimentary logs of magnetic susceptibility grain size measurements and carbonate content combined with malacological evidence indicate two main relatively cold and arid phases during the last glacial period related to intensive accumulation of loess units l1l1 and l1l2 as well as many brief episodes of dry and windy climatic conditions suggesting a possible relationship with cold events recorded in the north atlantic region generally late pleistocene climate in the region was dry and relatively warm compared with glacial period sites in central europe and was characterised by sharp differences between glacial and interglacial modes new data and interpretations presented in this study emphasise the significance of loess palaeosol sequences in vojvodina for the reconstruction of the temporal and spatial evolution of late pleistocene palaeoclimate in this part of europe copyright 2007 john wiley sons ltd

first results from the late pleistocene paleosols in northern western siberia implications for pedogenesis and landscape evolution at the end of mis3 abstract recent revision of the extent of late pleistocene glaciations in northern eurasia the justified search for the new paleopedological records in the center north west siberian plain we encountered paleosols in several exposures of the high alluvial terrace of the river vakh middle ob basin buried in the sequence of alluvial and lacustrine sediments a paleosol dated to the end of marine isotope stage mis 3 karga thermochron was studied in detail in the key section zeleniy ostrov the paleosol demonstrates strong morphological evidence of gleysation and accumulation of plant residues both processes indicating water logging and a reduced environment the modern soil on top of the exposure is a typical podzol formed in under conditions of perfect soil drainage and no water excess in agreement with current geological and geomorphological conditions we suppose that permafrost was the main factor hampering percolation and switching redoximorphic processes in the paleosol which thus was classified as a reductaquic cryosol presence of permafrost implies colder climate than the present one furthermore neutral reaction presence of neoformed calcium carbonate and abundance of silt fraction which points to eolian sedimentation suggest drier conditions however the studied paleosols differ considerably from the synchronous chernozems found in the loess sequences of southern siberia paleobiological proxies such as pollen plant macroremains phytoliths and fossil insects indicate a tundra or tundra steppe ecosystem possibly with some forest stands in good agreement with the paleopedological and sedimentary records

loess soil sequence at toshan northern iran insights into late pleistocene climate change abstract the knowledge of palaeoclimate in iran is still limited however insight into the timing and the dynamics of quaternary climate change in iran might offer valuable information to improve the global palaeoclimate record the loess soil sequence of toshan provides the first high resolution record of late pleistocene climate dynamics in iran and complements the hitherto known sections at neka now deh and agh band to establish a pedostratigraphic record of the north eastern caspian lowland our spectroscopic and grain size analysis are combined to propose i a pedostratigraphical scheme for the sequence at toshan ii describe and estimate the degree of soil development of selected stratigraphical units iii infer palaeoclimatic information and provide iv a correlation with previous loess palaeosol records of n iran as based on pedostratigraphic assumptions the section at toshan hosts a strongly developed reddish brown argillic palaeosol bt as well as eight moderately to weakly developed brownish palaeosol horizons lacking clay illuviation features bw bwk these remnants of fossil soils are separated by finely textured loess and horizons that host characteristics of both loess and mineral subsoils cb cbk giving evidence for syngenetic soil formation the stratigraphical succession of palaeosols loess and syngenetically altered sediments covering the last ca 130 ka gives evidence for recurrent climate changes as well as fluctuations between dominance of soil formation or dust accumulation in relation to changes in moisture regime the formation of bt and bw bwk horizons is related to relatively humid and warm conditions likely corresponding with interglacial and interstadial climate

magnetostratigraphy and magnetic parameters of a sedimentary sequence in punta san andres buenos aires argentina abstract this contribution focuses on polarity changes and magnetic parameters obtained in late cenozoic sediments exposed on the cliffs in san andres chapadmalal buenos aires province the sedimentary section studied comprises the vorohue san andres miramar and arroyo seco formations the upper layers of vorohue and the base of san andres showed records of normal polarity and were attributed to the gauss normal polarity chron 2 6 ma the main portion of san andres formation appears to have been deposited during lower and middle matuyama polarity chron including the normal polarity subchron olduvai 1 78 2 02 ma miramar formation contains polarity changes that should be assigned to middle matuyama jaramillo 1 05 ma and to jaramillo upper matuyama 0 99 ma the upper portion of the miramar formation and the lower one of the arroyo seco formation show reverse polarity levels and were assigned to the upper matuyama 0 78 ma finally the upper part of arroyo seco formation seems to have been deposited during the brunhes polarity chron

geological and geomechanical models of the pre landslide volcanic edifice of guimar and la orotava mega landslides tenerife abstract the geological and geomechanical characterizations of the volcanic rock mass succession affected by the guimar and la orotava mega landslides tenerife canary island are presented here for the first time the estimated subaerial volume of rocks mobilized by each of these landslides is in the range of 30 50 km 3 one of the largest known in the world field data gallery surveys and borehole drilling have allowed the main types of materials and their structural arrangement to be identified based on these information a geological model of the pre landslide volcanic edifice is proposed a palaeo morphological reconstruction has been produced and possible slope angles and heights of the pre landslide volcanic edifice are presented five main lithological units have been identified in the emerged part of the edifice three of them forming the flanks and two forming the structural axis of the island on the flanks lava flows predominate with different degrees of alteration and proportion of dikes increasing near the structural axis the predominant materials on the structural axis are pyroclastic deposits lava flows and dikes in the submarine edifice four main lithological units have been distinguished formed by hyaloclastites pillow lavas dikes and gravitational deposits slope and basin facies the geomechanical characterization of these materials has been obtained from field data boreholes laboratory tests and literature review the geological and geomechanical models obtained provide the fundamental basis for the explanation of the instability processes that generated the guimar and la orotava mega landslides

loess chronology of the caspian lowland in northern iran the loess palaeosol sequences of the caspian lowland in northern iran provide detailed archives of climate and environmental change showing a close relationship to global cooling and warming trends for the quaternary period the magnitude of these changes is under discussion owing to uncertainties in the chronologies for individual sites a chronological frame was set up for the last glacial loess record for three upper pleistocene key sections by infrared optically stimulated luminescence irsl in the caspian lowland irsl dating gives reliable ages for sediments covering at least the past 60 ka however for sediments older than 60 ka a significant age underestimation is likely the first strongly developed buried bt bwt horizons or pedocomplexes at the three sections under study correlate most likely with the last interglacial mis 5 at least four periods of increased sediment accumulation were determined for the last glacial period intercalated by periods of weak soil formation the loess palaeosol sequences in northern iran recorded coeval and similar major climatic changes as in south eastern central europe and central asia

the loess profile at albertirsa hungary improvements in loess stratigraphy by luminescence dating abstract a very detailed upper pleistocene record is exposed in a loess palaeosol sequence at the section at albertirsa in hungary luminescence dating was carried out to establish a more reliable chronological framework for the hungarian loess record the lowermost palaeosol of the section probably an equivalent of the mf2 horizon at the mende key section is superimposed on penultimate glacial loess an irsl age estimate of about 65 ka bp was determined for the lower part of this palaeosol indicating soil formation late in oxygen isotope stage ois 5 or early in ois 3 a significant hiatus most likely occurs in the lower part of the lower fossil soil the loess between the upper and and lower palaeosol yielded a mean luminescence age of about 50 ka bp the upper palaeosol is probably an equivalent of the mf1 horizon at the mende type section formed between 37 and 25 ka bp and so this palaeosol represents the hengelo and or denekamp interstadial of northwestern european stratigraphy the loess is intercalated by a humic horizon which yielded a mean luminescence age estimate between 21 and 19 ka at the albertirsa section

soil formation in loess derived soils along a subhumid to humid climate gradient northeastern iran abstract in order to contribute to the understanding of carbonate enrichment and clay illuviation in loess derived soils of subhumid to humid regions the development of soils was studied along a climate gradient with xeric and udic soil moisture regimes smr and thermic and mesic soil temperature regimes str respectively in the golestan province northeastern iran six representative pedons along a climate gradient were investigated soils were classified mainly as hapludalfs and haploxeralfs stability of the geomorphic surface under forest vegetation associated with high leaching conditions has provided appropriate conditions for decalcification followed by clay migration through the profile and formation of argillic horizons in all the studied soils clay content of the bt horizons soil organic carbon concentration of the a horizons and depth of the bk horizons increased significantly with increasing precipitation and decreasing temperature there was a considerable decrease in silt content with soil development the main pedofeatures observed in the bt horizons were clay coatings and decalcified zones nodules coatings and hypocoatings were the main calcitic pedofeatures observed in the bk horizons occurrence and preservation of clay coatings were more pronounced in the udic regions with illite and vermiculite as the dominant clay minerals type of clay minerals shrink swell properties and precipitation rate are factors affecting the abundance and preservation of clay coatings in the strongly developed horizons of the udic smr the occurrence of vermiculite clay minerals could reduce the shrink swell potential and increase the amount of clay coatings the presence of crystallitic b fabrics and the high carbonate contents caco 3 in the lower horizons bk were mainly related to decalcification processes under descending water flow in the overlying horizons

pedogenic carbonates archive modern and past precipitation change a transect study from soils and loess paleosol sequences from northern iran abstract stable carbon and oxygen isotope compositions in soil carbonates and in soil organic matter provide insights into paleo climatic conditions especially in arid and semiarid regions where carbonate is abundant in soils we here investigate 13c and 18o isotope composition of bulk carbonate pedogenic carbonate nodules and organic carbon from modern soils developed along a precipitation gradient entisol inceptisol mollisol and alfisol and paleosols formed within loess units in northern iran 13c values of organic carbon in the modern soils ranged from 19 5 in the arid and semiarid regions to 24 in the more humid regions with forest vegetation 13c values of bulk carbonate in the modern soils ranged from 12 1 at the wettest sites to 0 8 at the drier sites and thus a 550 mm increase in precipitation leads to a 11 decrease in 13c values of bulk carbonate in the modern soils 13c values of pedogenic carbonate nodules in the semiarid areas show higher values by 3 4 more than the regions with forest vegetation unlike 13c values of pedogenic carbonate nodules the 18o values of pedogenic carbonate nodules of modern soils in this study did not display pronounced changes across the sections the change in 13c of carbonates and organic carbon is consistent with the present above ground vegetation consisting of a mosaic of habitats with differences in the proportion of c3 and c4 vegetation tending to larger c4 contribution with increasing aridity the 13c values of carbonates coupled with climate data of the region confirm seasonal bias in the formation of carbonate nodules in the modern soils seen in studies elsewhere the 13c values of pedogenic carbonate nodules in the paleosols range from 10 in humid areas to 7 2 in semiarid areas the trends in 13c composition in modern soils are also visible in the 13c composition in the paleosols suggesting that in the foothills of the alborz and iranian loess plateau a precipitation gradient existed also in the last interglacial

late quaternary landscape evolution in a small catchment on the chinese loess plateau abstract late quaternary landscape evolution was analysed with reference to a small 0 08 km 2 drainage basin system in southeastern gansu province southwestern chinese loess plateau in this region v shaped valleys with broad valley floors are prominent landscape features whose basic shape already existed prior to mis 2 during mis 2 the valley bottoms were infilled with fluvially reworked loess today forming accumulation terraces infrared optically stimulated luminescence irsl dating of these loess like deposits assigned them to the time span ranging from 22 5 to 17 7 ka bp during the late holocene valley fills were partly eroded and the receiving stream channel was deepened by at least 25 m close to the confluence of the study site s channels these alternating erosion and accumulation phases were triggered by climatic factors or human impact in the most recent past the high landscape sensitivity of the chinese loess plateau has led to increasing soil conservation measures that have effectively confined surface erosion however the lack of drainage on the artificial terraces induces piping processes

fine grained quartz osl dating chronology of loess sequence from southern tajikistan implications for climate change in arid central asia during mis 2 abstract the desert and semi desert region of arid central asia is one of the most important areas of middle latitude dust emission and deposition in the northern hemisphere marine isotope stage 2 mis 2 was the latest and one of the most representative intervals of dust emission from the region and it is especially important for research into processes of dust transportation and deposition here we report the results of an optically stimulated luminescence study of the hoalin section in southern tajikistan which was deposited during mis 2 the fine grained quartz single aliquot regeneration sar approach was used and its reliability was verified by internal checks in addition grain size analyses calculated dust accumulation rates dars and mass accumulation rates mars were used to reconstruct the pattern of climate change during mis 2 the mean dar for southern tajikistan during mis 2 was 0 43 m ka and the corresponding average mar was 673 g cm2 a for a non river terrace site which is higher than the average mars estimated for the central and southern chinese loess plateau clp in contrast to previous suggestions the high dust dars and mars during the lgm indicate a cold dry climatic pattern rather than a cold humid pattern our results also confirm that the patterns of high dust emission and deposition during the lgm in the mid latitude arid zone of asia were synchronous

pleistocene climatic history of east and central asia based on paleopedological indicators in loess paleosol sequences a micromorphological comparison of the loess paleosol sequence of the karamaydan section central asia with the upper part of the luochuan section china clearly indicates that for the brunhes chron the sequence at karamaydan is more detailed than the corresponding section at luochuan single paleosols at luochuan correspond to pedocomplexes at karamaydan for example s 3 at luochuan corresponds to pk iii and s 4 to pk iv and both pks developed in a period longer than one interglacial about 104 years some pedocomplexes at luochuan are represented by more detailed successions at karamaydan for example the s 5 complex at luochuan corresponds to pedocomplexes v and vi the loess paleosol sequence at karamaydan should therefore be regarded as a key sequence for reconstructing the climatic history of the brunhes epoch correlation with the deep sea oxygen isotope record of bassinot et al which includes an accurate astronomical time scale allows a detailed chronostratigraphical subdivision of the loess paleosol sequence in karamaydan for the brunhes epoch the sequence in the central and lower parts of the chashmanigar section also in central asia shows much more pronounced paleosols than the equivalent sequence at luochuan although some ck or ckm horizons indicate the presence of hiatuses nevertheless for this part of the sequence it provides more paleoclimatic detail with cold dry stages represented by loess and warm humid stages interglacials by paleosols than even the deep sea cores

optical dating of sediments a new method for dating sediments is proposed which determines the time since the sediment was last exposed to sunlight an argon ion laser is used to excite electrons from thermally stable light sensitive traps and the subsequent luminescence used as a measure of the past radiation dose two sample sequences spanning the periods 0 700 kyr and 0 6 kyr show steadily increasing luminescence with age an age of 62 8 kyr is obtained for a silt radiocarbon dated at 58 8 0 3 kyr problems were found with two much younger samples

three armed rifts or masked radial pattern of eruptive fissures the intriguing case of el hierro volcano canary islands abstract using new surface structural data as well as subsurface structural data obtained from seventeen water galleries we provide a comprehensive model of the volcano tectonic evolution of el hierro canary islands we have identified measured and analysed more than 1700 volcano structural elements including vents eruptive fissures dykes and faults the new data provide important information on the main structural patterns of the island and on its stress and strain fields all of which are crucial for reliable hazard assessments we conducted temporal and spatial analyses of the main structural elements focusing on their relative age and association with the three main cycles in the construction of the island the tinor edifice the el golfo las playas edifice and the rift volcanism a radial strike distribution which can be related to constructive episodes is observed in the on land structures a similar strike distribution is seen in the submarine eruptive fissures which are radial with respect to the centre of the island however the volcano structural elements identified onshore and reflecting the entire volcano tectonic evolution of the island also show a predominant ne sw strike which coincides with the main regional trend of the canary archipelago as a whole two other dominant directions of structural elements n s and wnw ese are evident from the establishment of the el golfo las playas edifice during the second constructive cycle we suggest that the radial striking structures reflect comparatively uniform stress fields during the constructive episodes mainly conditioned by the combination of overburden pressure gravitational spreading and magma induced stresses in each of the volcanic edifices by contrast in the shallower parts of the edifice the ne sw n s and wnw ese striking structures reflect local stress fields related to the formation of mega landslides and masking the general and regional radial patterns

holocene vegetation history and sea level changes in the se corner of the caspian sea relevance to sw asia climate the palynological investigation of core tm 27 7 m long taken in a dried out lagoon reveals both holocene vegetation history in the north eastern foothills of the alborz mountains and past water level changes of the caspian sea cs the delay in woodland expansion at the beginning of the holocene which is typical of eastern turkey the iranian plateau and recorded in the cs south basin is only weakly felt as the region is close to glacial refugia of trees the succession of the main trees out of their refugia has been established as deciduous quercus carpinus betulus parrotia persica and fagus orientalis pterocarya fraxinifolia presenting therefore close affinities to south european interglacials of the early pleistocene this suggests a similarity in climate a pterocarya decline is observed after ad 495 the studied region is close to the easternmost tree distribution this could explain why it has been affected earlier than elsewhere in the northern alborz and the caucasus in addition human activities during the sasanian empire and the subsequent drying of the climate contributed to weakening the spread of this tree a maximal sea level occurs in the first part of the holocene from 10 6 to 7 2 cal ka it is suggested that the cs levels were significantly influenced by the monsoon precipitations over the western himalayas via the uzboy inflow this is followed by low levels from 7 2 to 3 5 cal ka with a minimum at 3 9 cal ka the neocaspian period should be considered a biozone rather than a chronozone as the environmental conditions reconstructed from dinocyst assemblages are different in shallow shelf waters and in the deep basins

loess chronology of the middle and upper pleistocene in tadjikistan the loess paleosol sequences of central asia are continuous terrestrial records of the quaternary period and enable detailed comparison with paleoclimatic archives such as marine and ice core records in order to reconstruct regional and global paleoclimatic and paleoecological development during the past 130 000 years thermoluminescence tl and infrared stimulated luminescence irsl dating methods are applied to the extensively studied loess paleosol sequence of the section at darai kalon chashmanigar tadjikistan in order to determine a more accurate chronological framework and climatostratigraphic reconstruction for the last interglacial glacial cycle luminescence dating suggests that the loess above the first pedocomplex from the top pc1 accumulated during the last glacial period a high accumulation rate of up to 1 20 m per 1000 years was determined for the last glacial loess especially for the uppermost 5 8 m pc1 formed during the last interglacial period oxygen isotope stage 5 the loess between pc1 and pc2 is designated to be of penultimate glacial deposition age infrared stimulated luminescence and tl age estimates are in agreement to 80 000 years before present bp indicating a long distance transport of the aeolian dust prior to deposition the upper numerical age limit range is between 300 000 and 450 000 years however reliable dating of the loess older than 130 000 years is not possible due to age scatter between samples and an inadequate increase of paleodose with depth this high resolution dating study underlines the importance of the section at darai kalon and indicates that it is one of the most continuous loess paleosol records of the northern hemisphere the chronological results are particularly important for the reconstruction of the human evolution in central asia suggesting much older age estimates than previously obtained for most of the archeological key sites associated with pc5 and pc4 in tadjikistan